Hollow fiber membrane contactors have several advantages that make them a good alternative to conventional absorption processes in the gas industry, and they have attracted the interest of many researchers. However, critical issues such as wetting hinder applications of membranes on a wide scale. Wetting is the penetration of the liquid absorbent through membrane pores, reducing mass transfer and consequently affecting the CO2 absorption efficiency and lowering the effectiveness of the separation process. The availability of membranes that can maintain a high efficiency and remain stable over a long period of operation is the main factor that is required in order to implement membranes in the industry for absorption processes. The wetting phenomenon in hollow fiber membranes is the focus of this review, which offers a critical examination of the literature published on membrane wetting, highlighting the main factors that control the effectiveness of the membrane separation process. These factors include the liquid absorbent, the membrane morphology represented by pore size and porosity, and the mutual interaction between liquid absorbents and the membranes. All of these factors are discussed in detail in view of a better understanding of the wetting phenomenon. Furthermore, methods and approaches to prevent wetting in addition to perspectives for future research in the area are presented.

The tremendous increase in energy demand due to increased population and rapid economics results in an increased level of atmospheric pollutants and global warming. The global shift to the use of renewable clean energies still has some restrictions in terms of the availability of the advanced reliable technologies and the cost of application compared to conventional fossil fuels. Until we can have this full conversion to renewables, the development of novel techniques for clean combustion of fossil fuels is appreciated. Forced by the simultaneous increased pressure of strict emissions regulations and the target of limiting the global warming to 2 °C, gas turbine manufacturers developed novel combustion techniques for clean power production in gas turbines as per the present review study. These novel techniques depend either on modification in the existing combustion system or developing novel burners for clean power production. In this review, different clean combustion techniques are presented including flame type variability, burner design, and fuel and oxidizer flexibility. The combustion and emission characteristics of different flame types including non-premixed/premixed, moderate or intense low-oxygen dilution (MILD) flameless combustion, colorless distributed combustion (CDC), and low-swirl injector (LSI) combustion flames are presented with their limitations for applications. Novel burner designs for clean burning in gas turbines are investigated in detail including swirl stabilized, dry low NOx (DLN), and dry low emission (DLE), catalytic combustion, perforated plate, environmental vortex (EV), sequential environmental vortex (SEV), advanced environmental vortex (AEV), and lean direct injection (LDI) micromixer burners. As an effective technique to control combustion instabilities within the gas turbine combustor, a fuel flexibility approach is studied, considering mainly hydrogen-enriched combustion and the associated concerns about the fuel variability technique. An oxidizer flexibility approach in gas turbines is also studied under a premixed combustion mode considering lean premixed (LPM) air combustion and oxy-fuel combustion, and both techniques are compared in terms of performance and emissions. Finally, the feasibility of the different clean combustion techniques is discussed along with the available market products utilizing such novel technologies.

In this study, the mercury release of the gypsum from the mercury coremoval wet flue gas desulfurization (FGD) process with post-thermal treatment or open-stack disposal was investigated experimentally. The results indicated that the aqueous-phase oxidized mercury could be efficiently captured and stored in the solid-phase gypsum by using the additives like NaHS, DTCR, and TMT. However, it could be found that the thermal stability of the mercury species on the resulting gypsum decreased significantly under typical wallboard-manufacturing conditions. Especially, 92.8% of mercury was released from the DTCR-treated sample. The following thermal decomposition tests further confirmed this result. The mercury ions in DTCR-Hg compounds were linked to more sulfur atoms, which were ready to transfer electrons to nearby mercury ions during heat-treatment, resulting in its lower stability. It could be also seen that the thermal stabilities of mercury species decreased with an increasing amount of additives. Moreover, the mercury leaching tests showed that additives addition could lead to an evident increase in the mercury leaching content, and the mercury leaching content increased on the order of Hg-TMT < β-HgS < Hg-DTCR. All these results suggested that more attention should be paid toward the mercury release during the post-treatment and disposal of wet FGD gypsum from the mercury coremoval wet FGD system by using additives.

The current hydrate kinetics model implemented in the multiphase flow simulator OLGA treats hydrate growth in oil-continuous systems by considering the solidification of emulsified water droplets to form a hydrate-in-oil slurry that is assumed to be stable. To date, the validity of this model has not been established for gas-dominant systems, where gas void fractions can exceed 90 vol %. Here, six experimental data sets, collected using a 40-m single-pass gas-dominant flowloop operating in the annular-flow regime, were compared with predictions made using the current hydrate kinetics model. The comparison identified discrepancies in the predicted flow regime and the gas–water interfacial area that significantly affect kinetic hydrate-growth-rate calculations; these discrepancies might be due, in part, to differences in dynamic similarity between flowloop experiments and industrial-scale simulations. By adjusting only the kinetic rate scaling factor, it was not possible to match the pressure drop observed experimentally, illustrating that the formation of a viscous hydrate slurry alone cannot account for the resistance to flow observed in gas-dominant systems. We demonstrate that it is possible to emulate deposition in the current model by adjusting the slip ratio between the hydrate particles and the condensed phases; this approach allowed stenosis-type restrictions to occur in the simulation, as well as pressure-drop behavior similar to that observed experimentally. Utilizing a simple in-house model with empirical correlations to predict the hydrodynamics, it is possible to match relatively closely the measured growth rate and pressure drop simultaneously. Such agreement could not be reached using the current hydrate implementation available in OLGA, highlighting the need for a gas-specific hydrate growth model that is capable of capturing both hydrate growth from suspended droplets in the gas phase and solid growth at the flowline wall, as well as the extent of hydrate deposition on the wall.

The controlling mechanisms for the accumulation and preservation of organic matter in residual bay environments during the transition from marine to continental settings are not well understood, although oil–gas source rocks can form in this setting. In this study, we develop a case study for the Early Cretaceous black rock series in the northern Qiangtang Basin, Tibet (i.e., the Upper Member of the Suowa Formation), by conducting a combined organic and inorganic geochemical analysis of micritic limestone, marl, and shale samples from an outcrop section. Results show that total organic carbon (TOC) contents of the studied samples are between 1.74% and 7.71%, with the organic matter being Type II/III kerogen. Of the three factors that could influence the observed TOCs and organic matter types, including paleoproductivity, preservational environment, and sedimentation rate, the preservational environment appears to be the dominant factor, independent of lithology. This is typically supported by the relatively modest covariance between redox-sensitive parameters and TOC contents, e.g., R2 = 0.625 in the Mn/Ca-TOC diagram and R2 = 0.690 in the U/Th-TOC diagram. This suggests that the suboxic–anoxic environment in the lagoon at the residual bay area promoted favorable conditions for organic matter preservation. In contrast, the other two factors, i.e., paleoproductivity and the rate of sedimentation, differed between three types of lithologies. For shales and micritic limestones, the effect of paleoproductivity was limited on the abundance of organic matter, and no significant effect of sedimentation rate was detected. In contrast, the paleoproductivity has a definite effect on the amount of organic matter preserved in the marls. These findings also add to our knowledge of the depositional environment that existed during the Early Cretaceous marine–continental transition in the Qiangtang Basin and further built our understanding of the potential hydrocarbon resources of the basin.

Asphaltenes are still problematic fractions and their composition is not fully unveiled as it relates to the original crude oil and the precipitation method. In this work, the composition of asphaltenes precipitated with n-heptane and n-pentane from ten crude oils from the Sergipe-Alagoas Basin were assessed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) using five ionization procedures (electrospray ionization (ESI), ESI(+) with formic acid, ESI(−) with ammonium hydroxide, and ESI(−) with tetramethylammonium hydroxide, and atmospheric pressure photoionization (APPI), APPI(+) and APPI(−)) in combination with a 7.2 T LTQ FT Ultra Thermo Fisher spectrometer. The purpose was to evaluate compositional differences between C5- and C7-asphaltenes according to the adopted ionization methodologies. Asphaltenes were compared as a function of heteroatomic composition and aromaticity. Chemometrics strategies were employed to evaluate the heteroatom classes of higher variation among the groups. Ions that were shared by the asphaltenes and the crude oils and between the ionization methods were also evaluated for similarity. Results showed that n-heptane asphaltenes are more aromatic than n-pentane asphaltenes, which in turn were found to be more acidic and to display a higher heteroatomic complexity. Principal component analysis and the evaluation of shared ions showed that APPI(±) is able to detected asphaltene ions directly from the whole crude oil. It was also found that the use of different ionization methods with and without additives is fundamental to obtain more comprehensive chemical profiles in terms of classes and their constituents for crude oils and their asphaltenes and that the specific n-alkane used to precipitate asphaltenes leads to different chemical profiles.

Chinese coal seams are characterized by high gas content and low permeability. The permeability of coal seams should be improved to achieve maximum extraction of coalbed methane. This study explores how coal and gas behave when subjected to hydraulic slotting. A fluid–solid coupling experimental system of gas-bearing coal subjected to hydraulic slotting was first established. Then, the fluid–solid coupling property of gas-bearing coal subjected to hydraulic slotting was revealed using the established experimental system. Meanwhile, indicators used to describe the process of hydraulic slotting were derived, and the factors affecting the process of hydraulic slotting were analyzed using the aforementioned indicators. The research achievements indicate that the gas pressure response of the monitoring points in the coal sample shows different characteristics at different stages. Corresponding to the change trend of the gas pressure, the vertical and parallel strains demonstrate the five-stage change characteristics. With the increase of gas pressure, the final deformation amount before slotting gradually increases, and the gas diffusion parameter increases exponentially. With the increase of the slot radius, the gas diffusion parameter shows a similar change tendency with the ultimate deformation amount, i.e., it tends to become flat after a rapid increase. The research achievements can provide certain theoretical and practical references for the revelation of the enhanced coalbed methane recovery mechanism through hydraulic slotting and the rational selection of the key parameters in the field test, respectively.

To investigate the effect of calcium mineral on the product distribution of low-rank coal pyrolysis, a Chinese subbituminous coal (Shenmu coal), and samples with 5% and 10% added calcium content, were selected to study with a homemade pyrolysis vacuum ultraviolet photoionization mass spectrometry (py-VUV-PIMS) system. In this system, secondary reactions of the pyrolysis products were generally inhibited because of in situ sampling, soft ionization, and high vacuum environment, which allowed direct detection of the initial pyrolytic products. Most evolved compounds during temperature-programmed heating from 30 to 650 °C were ionized by a VUV lamp (10.6 eV). The main products include five categories: alkenes, dienes, aromatics, phenols, and dihydroxy aromatics, which were formed via homolytic scission of weak bonds in side chains and bridges between aromatic nuclei in coal structure. The calcium mineral additives can dramatically affect pyrolytic product distribution, especially oxygen-containing compounds. The main reason is that calcium mineral plays a catalytic role in deoxygenation, which prompted incorporation of oxygen-containing compounds into corresponding aromatics, and resulted in the product of BTX levels increase significantly. The decrease in relative average molecular weight indicated the conversion of heavier components into lighter species, in terms of the observed m/z of the evolved gas components.

The filtration of flying char particles from coal pyrolysis vapors plays a very important role in enhancing yields and quality of pyrolysis oil. In this work, the performance of coal pyrolysis flying char particles in a granular bed filter (GBF) was studied in cold model experiments. A filtration model was developed using a macroscopic phenomenological method that describes the filtration of the GBF. The polynomial expression of the relative filter coefficient (F) and the nonlinear expression of the relative pressure drop ratio (G) were applied in the new model. The unsteady state of granular filtration was captured, demonstrating that the GBF performance could be predicted by the new model. Effects of superficial gas velocity, thickness of granular layer, and dust mass concentration on collection efficiency and pressure drop were analyzed. An excellent performance of the GBF was obtained and the total collection efficiency could reach a span between 98% and 99.9%. In the case of lower dust mass concentration, the total collection efficiency and pressure drop were slightly affected by the increasing dust mass concentration. The optimal operating conditions of the GBF were obtained: a superficial gas velocity of 0.2–0.6 m/s and a granular layer thickness of 0.07–0.11 m.

This paper entails the results of demineralization carried out on Karanpura Gondwana coals having high ash (30.57–21.80%) and low sulfur (0.29–0.20%) contents. The coal samples were subjected to demineralization using Pseudomonas mendocina strain B6-1, and the effect of various parameters, such as pH, temperature, incubation time, and pulp density, was observed. Optimum values of demineralization were found at pH 6.0, temperature of 35 °C, 6.0% (w/v) pulp density, and incubation time of 7 days. Reduction in the mineral matter (mean of 13.72–29.10%) content led to a relative increase in vitrinite, inertinite, and liptinite macerals. Further, the treatment has also caused an increase in the useful heat value, gross calorific value, and net calorific value of coal from 4824.86 to 5192.06 cal/g, from 5396.72 to 5647.47 cal/g, and from 5059.30 to 5273.80 cal/g (mean values), respectively. The method is eco-friendly and useful in obtaining clean fuel.

Sulfonated polystyrene has shown flexible action as an asphaltene dispersant/flocculant as a function of the degree of sulfonation and concentration used. In this work, samples of sulfonated polystyrene with different sulfonation degrees were assessed in precipitation assays in model asphaltene systems, with variation of the asphaltene fractions (asphaltenes extracted by n-pentane and n-heptane, C5I and C7I, respectively), asphaltene concentration, polymer concentration, and medium used to dissolve the polymer and asphaltenes. The precipitation tests were carried out with an ultraviolet–visible spectrometer, and the absorbance values were converted into asphaltene concentration values in solution by using calibration curves. The results showed that the concentration of sulfonic groups at which the polymer performs best as an asphaltene flocculant is 10 mol %. The dependence of the polymer’s effect as a flocculant or stabilizer of asphaltenes in function of its hydrophilicity and concentration was confirmed. Moreover, the results indicate there is a strong relationship between the polymer’s solubility in the medium and its flocculant action, which is significantly more effective when the polymer does not have strong affinity for the medium.

This paper analyzes the characteristics of coal measure shale using samples from the Guxian Block of the southwest Qinshui Basin. Several methods, including X-ray diffraction (XRD), Rock-Eval pyrolysis, high-pressure mercury intrusion porosimetry (MIP), low-temperature nitrogen adsorption/desorption, and isothermal adsorption experiments, were used to investigate the organic geochemical characteristics, mineral composition, pore structure, and methane adsorption characteristics of the shales. Furthermore, the effect of the total organic carbon (TOC), thermal maturity, and mineral composition on the pore structure and methane adsorption capacity of shale was also investigated. The results showed that the TOC of the shale samples ranged from 0.19 to 31.66%, and the shale samples with TOC higher than 2% account for 31.17% of the total samples. The shale samples were in the high overmature stage with high hydrocarbon conversion rates. The mineral composition of the shale samples are mainly clay minerals and quartz, and the brittleness index calculated on the basis of mineral component is distributed primarily in the range from 40 to 50%, suggesting that the shale reservoirs have better fracturing properties. The mesopores were the major provider of pore volume, followed by macropores, and the micropores provided the least pore volume. The pores are open in style and mainly consist of cylindrical pores, parallel-plate slit pores, and bottleneck pores. TOC was the main controlling factor for the development of pores, followed by clay minerals. The pore specific volume created by organic matter was far greater than that of the clay minerals. Quartz arrested the development of pores, and the increase in the quartz content reduced the porosity by approximately 0.57–1.42%. As R0 increased, the porosity first increased at the high-maturity stage and then decreased at the overmature stage. The maximum value appeared when R0 = 2.0%. The TOC-normalized methane adsorption capacity decreased as R0 increased. There was no obvious correlation between the clay mineral content and the TOC-normalized methane adsorption capacity, which may be attributed to the shale water content. Vertically, as the sedimentary facies transited from carbonate tidal flat facies to delta facies, the porosity, Brunauer–Emmett–Teller (BET) specific surface area, Barrett–Joyner–Halenda (BJH) pore volume, and Langmuir volume generally decreased and the physical reservoir properties of the shale reservoir became weaker.

Gasification is a key technology for efficient use of solid fuels. The moisture with a high content in lignite can be used during gasification reactions. Because a fluidized bed gasifier usually operates at a low temperature, a high concentrate of tar is entrained with generated syngas. Tar discharged to outside of the gasifier is processed by methods, for instance, high-temperature reformers, scrubbers, or adsorption by activated carbon, to reform tar to gas. These processes bring about an increase in running costs. The traditional evaluation index of tar is concentration in syngas, for example, “g/m3N”. It is necessary to elucidate the details of tar composition to optimize a gasification system; it is insufficient with only a concentration. The purpose of this study is to clarify the tar components generated by gasification conditions (steam gasification and pyrolysis) of lignite at 1123 K using a laboratory-scale fluidized bed gasifier in detail, by a combination of gas chromatograph mass spectrometry (GC/MS) and field desorption mass spectrometry (FD–MS). As the results, it was found that tar contained polycyclic aromatic hydrocarbons (PAHs) with a molecular weight range of 150–600 mainly in both conditions. By steam reforming, the tar concentration in steam gasification was lower than that in pyrolysis. However, the main tar components were almost the same in both conditions.

This study investigates the influence of supercritical CO2 (scCO2) injection on minerals in high-rank coal under the temperature, pressure, and hydrologic conditions of a deep coalbed. A typical high-rank coal reservoir in the Qinshui basin, the #3 coal seam, is the focus of this research. A coal–scCO2 geochemical reaction experiment is conducted to simulate the 2000 m burial depth of the coal seam. Field emission scanning electron microscopy is used to determine the locations of specific minerals and observe the effects of scCO2–H2O on these minerals at the micrometer scale. These results are combined with X-ray diffraction and inductively coupled plasma-atomic emission spectrometry and mass spectrometry analysis results, and the effects of the scCO2–H2O fluid on minerals in the high-rank coal over a short period are discussed. In addition, the influence on coal reservoir structure was studied based on intrusive mercury and liquid nitrogen adsorption experiment. The results suggest that instantaneous CO2 injection can provide a large amount of H+, and the initial ion release rate is high. Because of differences in mineral dissolution rates, scCO2–H2O has the strongest effect on calcite, followed by dolomite, aluminum hydroxide minerals, chlorite, and albite; however, effects are not obvious for illite, kaolinite, and quartz. Because of the low mineral content of the coal and the short experimental period, independent secondary carbon sequestration minerals did not form. However, the surface of aluminum hydroxide minerals reached partial dissolution equilibrium, and new layered aluminum silicate minerals were generated. The dissolution of carbonate minerals, albite, and chlorite increased the pore volume of the coal reservoir and improved the permeability of the samples. New layered aluminum silicate minerals and the chlorite with new occurrence increased the surface areas of samples after the reactions. After the reaction, porosity, pore volume, and surface area of the sample were greater, which also confirmed the positive transformation effect of the mineral changes on the reservoir.

Polymers are often used for chemical water plugging. When the reservoir temperature is lower than 50 °C, the reaction between polymers and cross-linking agents is very slow, which extensively prolongs the gelation time and even leads to unsuccessful gelation. To overcome such problems, a foamed-gel system that is capable of spontaneous in situ heat generation was developed. The optimal system was identified through the orthogonal test using the gel strength, gelation time, and gel volume as indexes. The test shows that, when the ambient temperature is fixed at 30 °C and the pH value is 6.8, the system performs well. Under such circumstances, the gelation time is 40 h, the gel strength reaches the G grade, and the volumetric expansion ratio at 10 MPa exceeds 130%. Nuclear-magnetic-resonance-based T2 spectra indicate that the foamed gel injected into the rock can effectively plug large pores and, therefore, offset the heterogeneity. It is also found that the foamed gel has great capacity for volumetric expansion-based water plugging. The synchronization between gelation and gas generation is the key to the heat-generating foamed gel. Experiments suggest the properties of the developed heat-generating expandable foamed gel can be manipulated by adjusting pH values to satisfy varied requirements for placement in different reservoirs.

Thermogravimetric analysis was used to study the pressure effect on the activation energy during asphaltene gasification. The experiments were carried out under steam atmosphere at different pressures (1–80 bar) and temperatures (100–900 °C). The measured values of the total mass loss of asphaltenes are pressure dependent. They increase with rising pressure. Kinetic parameters were determined using a first-order kinetic model and integral method with thermogravimetric analysis data. The activation energy was found to vary from 189.6 to 130.4 kJ/mol and frequency factor from 4.1 × 1010 to 1.2 × 106 min–1. A decrease of both parameters was observed with an increasing pressure. Coke produced during the gasification is obviously characterized by the bigger pore size and weaker mechanical strength as the pressure increases from 1 to 80 bar. The structure of the produced coke becomes more crumbly with raising pressure. The formation of spherical carbon particles with a radius of around 5 μm was observed at high pressure (20–80 bar). The elemental composition of these particles is roughly equal: C (∼97%), S (∼2%), and O (∼1%).

This study quantifies the advantages of a chemical looping reducer reactor modularization strategy that leverages two or more reducer reactors operating in parallel to enhance syngas production beyond what is achievable by a single reducer reactor or conventional processes. The modularized system incorporates CO2 capture and utilization as a feedstock in an iron–titanium composite metal oxide based chemical looping system to enhance coal based chemical production. Simulations conducted in ASPEN Plus software suggest that adopting a cocurrent moving bed reducer reactor based modularization strategy can improve syngas yield by greater than 11% over a single chemical looping reducer reactor. Experiments conducted on a bench scale reducer reactor confirm the findings of the simulations. The modularization simulation was scaled up and incorporated into commercial sized methanol and acetic acid production plants. Chemical looping modularization demonstrates the ability to reduce coal consumption by 25% over a baseline coal gasification process, compared to 15% reduction if a single chemical looping reducer reactor is used instead of the modular strategy, for 10 000 ton per day methanol production. Integration into a commercial scale acetic acid plant shows conditions in which the process can operate as a CO2 neutral or negative system, where the process was consuming more CO2 than it produces. These results indicate the potential for significant feedstock reduction in large-scale coal to chemical processes, like methanol, acetic acid, formic acid, and oxalic acid.

Shale oil is currently of interest for unconventional resource exploration and development. Understanding the mechanism of interaction between the complex mixture of organic compounds in shale oil and minerals making up the reservoir rock–oil interface will assist recovery. In this study, molecular dynamics simulation is used to study the adsorption characteristics of a model oil mixture within nanoscale intraparticle pores of kaolinite minerals, which form pore-filling structures in shale rock. To better understand the effects of oil composition, temperature, and pressure on the adsorption properties of the model oil mixture, a range of temperatures (298, 323, 348, and 373 K) and pressures (1, 50, 100, and 200 bar) representing up to reservoir conditions were used. This study shows that adsorption and arrangement of oil molecules is dependent on the surface of kaolinite and the distance away from it. The simulations show polar compounds are likely to be adsorbed on aluminol kaolinite basal surfaces, while alkanes preferentially adsorb on silicate surfaces. In addition, the number of oil-molecule-bound layers and the total adsorption amount on the silicate surface is greater than the aluminol surface. The density of adsorbed oil is reduced with increase in temperature, while the effect of pressure is not as significant. On the basis of performed molecular simulations, we show the adsorption rate of shale oil on the surfaces of kaolinite sheets and assess the capacity to remove the model oil.

While undesirable in aviation fuel systems, water is both ubiquitous and tenacious; thus, interactions between water and aviation turbine fuel occur regularly. From a fuel user perspective, it is important to know, understand, and be able to predict such fuel–water interactions, e.g., water solubility, water settling rate, and interfacial tension, for proper mitigation. We explore these interactions as well as surface tension of both petroleum-derived and alternative jet fuels to compare potential differences between product compositions on these physical interactions. Observations indicate a positive, nonlinear correlation between water solubility and both aromatic content and temperature (from 0 to 50 °C). Water settling rates appear to follow a Stokes’ law model; therefore, bulk chemical composition indirectly influences settling rates via density and viscosity. Finally, surface tension appears positively correlated to sample density, while interfacial tension is correlated to both surface tension and fuel aromatic content.

Polymer modifiers have been used to improve the performances of asphalt binders in pavement engineering. The modifying effect of polymers on asphalt is largely dependent on the morphological characteristics of polymer-modified asphalt. The morphologies of polymer-modified asphalt are composed of a polymer-rich phase, a asphaltene-rich phase, and the interphase between the two phases. Interfacial interactions importantly contribute to the morphology but are commonly overlooked. In this study, carbon nanotubes (CNTs) were selected to improve the interfacial interactions of polymer-modified asphalt. Fluorescence microscopy (FM), scanning electron microscopy (SEM), micro-Raman spectroscopy (MRS), and molecular dynamics (MD) simulation were used to capture the characteristics of the interphase and polymer-rich phase. CNTs-polymer-modified asphalt involves stronger intermolecular forces than those in asphalt-modified by only styrene–butadiene–styrene (SBS) or CNTs. This discrepancy highlights the intensified interfacial interaction in the former material. Raman peak and MD findings reveal that the C═C of CNTs interacted with the alkanes and aromatic hydrocarbons of asphalt. SBS were entwined or surrounded with CNTs through the π–π conjugation of the benzene rings of the two components. Consequently, a synergistic effect enhanced the intermolecular force between SBS and CNTs in the interphase. SEM results indicated that CNTs were enriched in the interphase, enhancing mechanical anchorage between the polymer and asphalt. As a result, CNTs increased the roughness of the interphase and produced a prominent cage construction of polymer-rich phase. Moreover, the observed pullout behaviors of CNTs alleviated interfacial failure. FM images displayed that CNTs enhanced the swelling degree of the polymer-rich phase. This effect was realized because CNTs served as a tunnel for transporting saturates, aromatics, and small resin molecules, as shown by molecular dynamics MD analysis. This work revealed the importance of the interfacial interactions on the micromorphologies of polymer-modified asphalt.

The metallurgical properties and the microstructure of coke after gasification reaction with pure H2O and pure CO2 were investigated in this study. Moreover, the first-principles calculation was conducted to study the reaction process of the carbon with pure H2O and pure CO2. The results show that the CRI (coke reaction index) increases sharply and the CSR (coke strength after reaction) decreases sharply, when the cokes are gasified with H2O as compared to CO2. The scanning electronic microscopy images and the coke panoramagrams show that H2O more easily leads to the generation of large pores (>500 μm) and destroys the coke structure than CO2. The X-ray diffraction results indicate that the arrangement of carbon atoms of coke becomes regular and the ordered degree of coke increases after reaction with CO2 and H2O; however, after being gasified with H2O, the cokes have a higher ordered degree than with CO2. The results of the first-principles calculation show that the H2O molecule is more likely to react with carbon as compared to the CO2 molecule due to the lower energy barriers of H2O adsorption and H2 formation. The M2 → FS reaction process is the controlled step of the C-H2O reaction process, as well as in the C-CO2 reaction system.

Diffusion coefficient is usually used to evaluate the methane (CH4) diffusion properties in the coal matrix and is vital to coalbed methane (CBM) development. Although extensive literature on the CH4 diffusion coefficient can be obtained, most of them aim at the whole coal or coal rank instead of the macrolithotype. Additionally, the primary structure of coal was destroyed with the common determination technologies (e.g., the particle, steady-state, and inverse diffusion methods) which could result in great errors. In this work, to avoid the shortcomings of the above methods, nine flake coal samples from six coal mines in the Qinshui and Ordos Basins were prepared to determine the CH4 diffusion coefficient with the slab calculation model. Meanwhile, the effects on the diffusion from the gas pressure, temperature, water saturability, and coal pore structure, and the gas adsorption capacity controlled by the coal rank and macrolithotype, were analyzed to reveal the diffusion mechanism (mode) at the CBM reservoir and laboratory conditions. Results show that the CH4 diffusion coefficient, at an order of magnitude of 10–10 m2/s measured with the flake coal sample, is more truthful. High temperature and gas pressure, low water saturability, developed pore structure, and high gas adsorption capacity contribute to large CH4 diffusion coefficient. Although the higher rank coal has the larger gas adsorption capacity, the CH4 diffusion coefficient exhibits a “U” shape (first decreasing and then increasing) with the increase of coal rank due to more micropores in low- and high-rank coals than the middle-rank coal. From the bright to dull coals at the same coal rank, the decreasing development of pore structure and gas adsorption capacity causes the decreasing CH4 diffusion coefficient. But compared to the coal rank, the influence of coal macrolithotype on CH4 diffusion coefficient is weaker. In addition, the CH4 diffusion modes in coal mainly are transitional and Fick diffusions in the CBM reservoir and laboratory.

A “volcano” plot provides a visual means for identifying statistically significant differences between two populations. Here, we introduce the volcano plot as a means for simple, visual identification and statistical ranking of compositional differences between petroleum crude oils. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry yields the relative abundances of ions in each spectrum that contains up to tens of thousands of elemental compositions (CcHhNnOoSs). From that data, a volcano plot may be generated by plotting statistical significance (p-value, obtained from t test) versus log2(relative abundance ratio). The volcano plot data may be color-coded to highlight differences in heteroatom class (NnOoSs), double bond equivalents (DBE = number of rings plus double bonds to carbon), and/or carbon number. The volcano plot may be used either directly or as a “filter” for including only the most statistically significant differences for data entered into more conventional analyses based on DBE vs carbon number, van Krevelen diagram, and Kendrick mass defect plots. In each case, the volcano plot provides statistically significant criteria, rather than visual grouping.

Light oil and natural gas are commonly found in Jurassic shales in the North Fuling area of Sichuan Bain in China. The main source rocks of the study area are shales from Lower–Middle Jurassic lacustrine layers including the Lianggaoshan Formation (J2l) and the Ziliujing Formation (J1z), which are further divided into the Da’anzhai (J1zD), Ma’anshan (J1zM), and Dongyuemiao (J1zDY) members. Multiple geochemical approaches and tests including kerogen elements, kerogen composition, vitrinite reflectance (VR), total organic carbon (TOC) content test, Rock-Eval pyrolysis, gas chromatography and gas chromatography–mass spectrometry, methane concentration, gas composition, and stable isotopes were employed to determine the geochemical characteristics of the source, oil and gas samples. J1zD shale demonstrates the best abundance and type of organic matter among all four strate and tends to be the most favorable source of hydrocarbons in this area. Crude oil in Jurassic strata is a waxy light oil. Oil samples and shale extracts are nonbiodegraded, and dominated by short-chain n-alkanes, maximizing around C12–C15. Natural gas in Jurassic shales can be categorized as wet gas. δ13C values in different components indicate the gas samples are oil-associated gas which probably originated from the cracking of crude oil. Source correlations suggest the oil and gas are probably generated from J1zD shale. The analysis leads to the general conclusion that the Jurassic shale is more favorable for conventional resources than shale gas.

The pyrolysis of hydrocarbon fuels can give rise to the formation of coke on metal substrate surfaces. Until now, there are few research reports about how the nature of these surfaces affects the formation of coke, especially the effect of surface roughness. A series of samples of different surface roughnesses was obtained by mechanical polishing, and the coking property with changed surface roughness was evaluated by cyclohexane cracking under 1 atm at 730–810 °C. The coke obtained was then analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and temperature-programmed oxidation (TPO). The results showed that reducing the surface roughness can effectively decrease the amount of coke in different ranges of cracking temperatures and cracking times, especially in high-temperature ranges (above 770 °C). The polishing process reduced the metal catalytic activity of coking to inhibit coke formation without changing the mechanism of cyclohexane cracking. Surface roughness could significantly affect the morphology of coke. The filamentous coke exhibited a cylindrical cross section with small amounts of amorphous carbon on its outer surface. The coke on the surface of the unpolished substrate had a higher degree of graphitization than that on the polished substrate, and the degree of graphitization gradually reduced as the surface roughness decreased. Generally, the decreased surface roughness was not only unfavorable to coke adhesion but also changed the properties of coke in the coking process.

Reservoir geochemistry has a practical application in petroleum exploration. A typical Paleozoic carbonate oilfield was selected from the Tabei Uplift of the Tarim Basin (northwestern China) to exhibit the method, application, and exploration implications of reservoir geochemistry. Oil–oil correlation indicates that all oils analyzed in this study belong to one single oil group. The overall oil migration direction traced by selected organic molecular markers is from the southern to the northern regions of the Halahatang region. The source kitchen for current oil accumulations in the carbonate reservoir is predicted to locate to the south of this oilfield, most likely between the Awati and Manjiaer depressions. Based on the characteristics of hydrocarbon-bearing inclusions and the histograms of the homogenization temperatures (Th) and ice-melting temperatures of associated aqueous inclusions, the oil charging temperatures were obtained. The stratigraphic-burial and geothermal histories for representative individual well were reconstructed using one-dimensional basin modeling. We concluded that the Paleozoic oil reservoir has been charged twice during its oil charging history: first from 419 to 410 Ma and second from 16 to 8 Ma. The preservation conditions for early filling oil accumulations and the mixture of oils charged during the two filling phases have controlled the density and chemical compositions of present oil accumulations. The filling points and preferential pathway indicated by isopleth maps of molecular geochemical indicators are highly indicative of oil reservoirs with high yields. It is concluded that reservoir geochemistry can be utilized, not only to determine oil migration direction and to predict the location of source kitchens, but also for favorable charging pathway and potentially prolific prospecting zones. This study suggests that traps in the southern region along the preferred oil charging pathway into the Halahatang Oilfield could be the most favorable targets for further oil exploration in this region.

Zhundong coal has attracted an increasing concern due to its super huge reserve but high content of alkali metals. Oxy-fuel combustion of Zhundong coal benefits the near-zero emission of pollutants in coal-fired power plants and promotes the large-scale utilization of high-alkali coal. However, few efforts if any have been conducted on oxy-fuel combustion of Zhundong coal. The previous studies related to Zhundong coal were mainly focused on sodium behaviors but little work has been performed on calcium and iron, while calcium and iron are very likely to generate significant influences on fouling problems in combustion of Zhundong coal. The present study aimed to elucidate the release and transformation behaviors of sodium, calcium, and iron in oxy-fuel combustion of Zhundong coal using a fixed-bed reactor. Experimental results indicated that calcium in Zhundong coal was mainly present as the ammonium acetate-soluble form, while the iron existed in forms of hydrochloric acid-soluble and insoluble. With the increasing combustion temperature, the ash yields of Zhundong coals decreased and the volatilization ratio of sodium increased, while the temperature had a weak influence on ash yield and the release of water-soluble sodium between 800 and 1000 °C. The variations of total calcium with combustion temperature were not significant, but transformations among various chemical forms occurred. The decreased iron of the hydrochloric acid-soluble form was transformed into the insoluble form and discharged into gaseous phase. Compared to the air case, oxy-fuel combustion with 21% oxygen led to more sodium and iron retained in residual ash, while it promoted the release of calcium. The mineral transformation and ash formation were susceptible to the high content of carbon dioxide under oxy-fuel condition and were strongly associated with the chemical forms of sodium, calcium, and iron within Zhundong coals. The crystalline mineral species in Zhundong ash were obviously influenced by the combustion temperature and partly affected by the atmosphere. The differences of mineral species of Zhundong ash between air and oxy-fuel cases were mainly present in the range of 800–1000 °C, which was closely related to the decomposition of calcite and transformation of calcium. The oxygen content dependency of transformation behaviors of sodium, calcium, and iron was greatly different during oxy-fuel combustion. This work possibly offered an improved understanding of the functional mechanisms of sodium, calcium, and iron on fouling issues.

Porous carbons have been widely explored and utilized in the fields of adsorption. Pore structure design is the key for achieving high-capacity and fast adsorption. Herein, we develop a simple and general method for pore regulation of coal-based activated carbons (ACs), which is based on a catalytic physical activation process by using the inherent minerals in coal precursor. By adjusting the inherent mineral distribution in the coal precursors, activated carbons with various pore configurations including microporous structure and hierarchically porous structure can be obtained. More specifically, ZD-HCF-AC from a mineral-free coal precursor shows a microporous structure with a low surface area of 345 m2 g–1, while ZD-AC from mineral-rich coal exhibits a hierarchically porous structure with remarkably improved surface area of 933 m2 g–1. Ca and Mg components in the minerals notably promote the development of mesopore and macropores and lead to the resulting ACs with hierarchical pore structure. The effect of inherent minerals is not only limited to Zhundong coal but also available to other mineral-rich coals. Evaluated as adsorbents, microporous ZD-HCF-AC exhibits excellent SO2 adsorption capacities up to 73.4 mg·g–1; hierarchically porous ZD-AC has the best performance for Rhodamine B (RhB) adsorption with capacity up to 227.8 mg·g–1. This work not only provides a simple and scalable method for preparing coal-based activated carbons for various adsorption applications but also offers a new route for adjusting the porosity of activated carbons during the physical activation process.

As an eco-friendly, cheap and readily available material, calcium-based oxides could play the dual roles of both tar reforming catalyst and CO2 sorbent, thereby producing hydrogen-rich gas with low tar concentration and low carbon emission during steam gasification of coal/biomass. This study aimed to experimentally investigate effects of different parameters on hydrogen-rich gas production during steam gasification of lignite using dual calcium-based catalysts. Furthermore, in view of the importance of the water–gas shift reaction to hydrogen-rich gas production, its catalytic kinetics with the homemade calcium sorbent was also studied. The results show that the addition of active calcium oxide remarkably decreased tar yield, leading to a significant increase of noncondensable gas yield. Increase of loading amount of homemade sorbent enhanced CO2 absorption, thereby breaking the water–gas shift reaction equilibrium and shifting it, resulting in a distinct increase of H2 yield and a decrease of CO yield. The highest H2 yield of 1.24 N m3/kg-coal was obtained in current study. Finally, the catalytic kinetics of the water–gas shift reaction with homemade sorbent were obtained using a newly developed and more precise kinetic model, and from there the conversion of the WGS reaction was well predicted by the new kinetic model.

Steam cracking of crude oil fractions gives rise to substantial amounts of a heavy liquid product referred to as pyrolysis fuel oil (PFO). To evaluate the potential use of PFO for production of value-added chemicals, a better understanding of the composition is needed. Therefore, two PFO’s derived from naphtha (N-PFO) and vacuum gas oil (V-PFO) were characterized using elemental analysis, SARA fractionation, nuclear magnetic resonance (NMR) spectroscopy, and comprehensive two-dimensional gas chromatography (GC × GC) coupled to a flame ionization detector (FID) and time-of-flight mass spectrometer (TOF-MS). Both samples are highly aromatic, with molar hydrogen-to-carbon (H/C) ratios lower than 1 and with significant content of compounds with solubility characteristics typical for asphaltenes and coke (i.e. n-hexane insolubles). The molar H/C ratio of V-PFO is lower than the one measured for N-PFO, as expected from the lower molar H/C ratio of the VGO. On the other hand, the content of n-hexane insolubles is lower in V-PFO compared to the one in N-PFO (i.e., 10.3 ± 0.2 wt % and 19.5 ± 0.5 wt %, respectively). This difference is attributed to the higher reaction temperature applied during naphtha steam cracking, which promotes the formation of poly aromatic cores and at the same time scission of aliphatic chains. The higher concentrations of purely aromatic molecules present in N-PFO is confirmed via NMR and GC × GC–FID/TOF-MS. The dominant chemical family in both samples are diaromatics, with a concentration of 28.6 ± 0.1 wt % and 27.8 ± 0.1 wt % for N-PFO and V-PFO, respectively. Therefore, extraction of valuable chemical industry precursors such as diaromatics and specifically naphthalene is considered as a potential valorization route. On the other hand, hydro-conversion is required to improve the quality of the PFO’s before exploiting them as a commercial fuel.

Determining oil quality is essential to identifying valuable resource accumulations. However, in new areas of exploration, little information is available on the processes affecting resource quality. Geochemical analyses of oil seeps from frontier regions of New Zealand’s East Coast illustrate an application of underutilized resource quality assessment techniques. Distributions of n-alkanes and isoprenoids reveal biodegradation, and thus potentially lower oil quality in the “southern” versus the “northern” oil seeps. However, sterane and terpane compounds are unaltered, indicating overall biodegradation of these oils is low to moderate. Additionally, lack of 25-norhopane indicates degradation of southern oils may be solely aerobic. Therefore, any subsurface accumulations are potentially unaffected. Investigation of sterane and hopane isomerization ratios and additional sterane and terpane maturity parameters is paired with diamondoid analyses of oil-to-gas conversion and petroleum mixing. Three distinct petroleum mixtures are identified among the sampled seeps: (1) a seep composed of an early/peak oil window component and an intensely cracked condensate/wet gas component, (2) seeps solely containing a peak/late oil window component, and (3) seeps composed of a peak/late oil window component and an intensely cracked condensate/wet gas component. Identified components indicate at least three distinct charges or stages of petroleum generation. Black oil components might indicate actively producing source rock in all regions represented by the seeps. Intensely cracked components indicate petroleum mixing via thermogenic gas infiltration and suggest an effect on oil quality. Important questions concerning migration pathways and timing, ties to New Zealand’s offshore basins, and potential for reservoir entrapment of these petroleum components remain.

Variations in the grindability of semi-cokes produced by two low-rank coals at different pyrolysis temperatures were studied. The grindability of semi-cokes prepared by Ximeng lignite (XL) had minimal changes at varying pyrolysis temperatures and was nearly similar to that of a dehydrated sample. The pore structure of XL was fully developed after dehydration and had no significant change during pyrolysis, as indicated by the observations obtained through scanning electron microscopy and results of the mercury intrusion porosimetry experiment. Thus, its grindability showed little change during pyrolysis. Meanwhile, the grindability of Shenhua sub-bituminous coal (SC) decreased considerably when the pyrolysis temperature reached 550 °C. As shown by the results of thermogravimetric experiments, X-ray diffraction, and fractal analysis of the pore structure, the coal matrix of SC had a plastic stage. Meanwhile, its volatile matter rapidly releases in this stage. After the plastic stage, considerable changes occur in the pore and chemical structures of SC. All of these factors eventually altered the grindability of SC.

Coal mined from the Talcher region of Odisha, India is known to be high-ash, surface-oxidized, and noncoking in nature. It is quite challenging to beneficiate such low-grade coal by physical or physicochemical processes due to its oxidized nature and the presence of complex ash forming mineral matter in its matrix. Chemical beneficiation is one of the alternative process to such problems. However, this chemical process consumes more chemicals, treatment time, and energy, which limits its application further. Therefore, an attempt has been made to chemically beneficiate this coal cost-effectively with optimum chemicals, treatment time, and energy. In the present study, an application of ultrasound at low frequency on alkali-acid leaching is employed to investigate on the demineralization of high-ash Indian noncoking coal. The raw coal properties such as fixed carbon content, CHNS content, Hardgrove grindability index, ash fusion temperature, and gross calorific value (GCV) were investigated before the experiments. The coal samples were leached with three different types of alkali namely, NaOH, KOH, and Na2CO3 followed by H2SO4 and HCl treatment, respectively. The quality of the treated coal was examined by proximate analysis and GCV measurement. The maximum ash removal was achieved on NaOH-leached coal followed by 30% H2SO4 treatment with 73.91% demineralization and 57.21% fixed carbon. The raw and treated coal samples were characterized by Fourier transform infrared, scanning electron microscopy, and X-ray diffraction to confirm the presence of oxygenated functional groups causing surface oxidation, surface modification by ultrasonication, and the formation of alkali aluminosilicates on the coal surface, respectively. The presence of trace elements in the alkali leachates released during ultrasonication was also determined by the inductively coupled plasma atomic emission spectroscopy technique.

To investigate the interactions between K2CO3 and coal char, a fixed-bed reactor was used to conduct catalytic pyrolysis and gasification of coal char. An in situ Raman spectroscopy system was applied to characterize the evolution of char structure. Three different ranks of Chinese coals were deashed first and pyrolyzed to chars before experiment. In catalytic pyrolysis of coal char, the release of CO proved that reactions occurred between K2CO3 and char and the release of a small amount of CO2 was connected with the oxygen content. In situ Raman spectra results showed that the char structure order decreased with rising temperature for the production of an intermediate. During the gasification process, the char structure order decreased first and then increased, attributed to the evaporation of K at high temperature. The ex situ data revealed that the intermediate did not exist at room temperature. For better understanding of the true form of chars at high temperature, an in situ Raman spectrometer is necessary.

The lab-scale fixed-bed pyrolyzer by circulating ash as heat carrier was used to study the secondary catalytic effect of circulating ash on the primary volatiles from slow and fast pyrolysis of coal. Different mass ratios of ash to coal were layered in the pyrolyzer. Combined with the simulated distillation analysis, gas chromatograph-mass spectrum (GC-MS), and elemental analysis, the yields and compositions of gas, tar, and semicoke were analyzed. The results show that circulating ash catalyzes the cracking of primary volatiles generated by both slow and fast coal pyrolysis. CO2 is very sensitive to the proportion of circulating ash; it mainly comes from the breaking of −C–O– bonds with low energy in tar. After adding circulating ash, the gas yield increases while the tar quality is improved despite the reduction in tar yield. Circulating ash is beneficial to the cracking of oxygen-containing, nitrogen-containing, and sulfur-containing bonds in asphalt. The components with carbon numbers of ≥26 in tar can be upgraded and then results in the growing yields of ≤C25 components. Circulating ash can increase the tar saturation in the secondary catalytic reaction. This study can provide basic data for the effect of secondary catalytic as well as the heating rate on the coal pyrolysis by circulating ash as solid heat carrier.

Static dissipater additives (SDAs) are conductivity improver additives that are added to aviation turbine fuels (ATFs) to avoid sudden increase in conductivity that may occur during transfer/pumping of ATF. STADIS 450 has been used globally as the SDA in aviation jet A1. The dosage of SDA into jet fuels is very closely specified (1–3 ppm). Due to surface active nature, SDA dosage may deplete with time. The monitoring of concentration of SDA is very critical and is generally carried out using conductivity measurement as per ASTM D2624 or as per liquid chromatographic technique based ASTM D7524 method entitled in “Determination of static dissipater additive (SDA) in aviation turbine fuel using HPLC technique with UV detector in the range of 1 to 12 ppm”. In this work, SDA blended ATFs in the range of 1–5 ppm have been analyzed for estimation of SDAs using both HPLC based ASTM D7524 and conductivity measurement based ASTM D2624. This paper suggests precautions that need to be taken while using the two methods. The work also recommends suggestions that can make the ASTM D7524 findings more specific and precise and ensures better recoveries. While the initial procedures were adopted from ASTM D7524, multiple collections during cartridge extraction process and use of HPLC with photodiode detector instead of UV detector bring down the detection level to 0.5 ppm of SDA in ATF.

The imbibition of solutions of a model nonionic surfactant into packed beds of crushed reservoir rocks was studied using the Washburn technique. A linear dependence between the equivalent height of capillary rise and the square root of imbibition time was observed at different stages of imbibition experiments. It has been shown that, under the conditions when surfactants did not alter the polarity of rocks, the imbibition rate of surfactant solutions correlated well with the nondispersion (polar) component of the surface free energy of the rocks. It was possible to compare data obtained for different rocks by normalizing the slopes of imbibition curves over the corresponding slopes determined for a completely wetting fluid, hexamethyldisiloxane (HMDS). Such a normalization allowed one to account for substantial differences in the morphology of crushed rock powders. Overall, the observed trends in the imbibition behavior were qualitatively similar to the trends reported previously for the rise of surfactant solutions in single capillaries. The largest qualitative impact of nonionic surfactant was observed in the imbibition into hydrophobic oily sandstone, in which case a surfactant-induced shift to hydrophilicity was observed. Overall, high concentrations were needed in order to observe the impact of surfactant on the imbibition rate.

To make full use of heavy oil by thermochemical conversion, the thermal behaviors of vacuum residue (VR) were investigated first by thermogravimetry–Fourier transform infrared spectrometry (TG–FTIR) and then via a laboratory-scale fluidized bed reactor (FBR). The TG–FTIR results showed that the changes in the absorbance of volatiles during thermal cracking were consistent with the weight loss in the derivative thermogravimetric curve. The dynamic information about the release profiles of the typical gaseous products such as CO, CO2, CH4, C2H4, light aromatics, and aliphatic olefins revealed the cleavage of varied structures and functional groups of VR at different temperatures. Moreover, the peaks for the maximum releasing rate on the evolving profiles of gaseous products became narrower and sharper, and the yield at maximum releasing rate for the gaseous species increased with increasing the heating rate. The pyrolysis experiments in a FBR with silica sand as a heat carrier showed that alkenes were the dominant gaseous products, with light olefin selectivity higher than 53%. The coke/Conradson carbon residue ratio was lower than that in the delay coking process. Furthermore, analysis of liquid oil using gas chromatography/time-of-flight mass spectrometry showed that 1-alkenes was the most abundant decomposition product and the selectivity of total olefins from C6 to C22 was 62.74%.

With the gradual popularization and application of CO2 flooding technology in oilfields, the physical properties of produced fluid, including the stability of the emulsion formed by crude oil and produced water, may be changed, consequently influencing the surface gathering and dewatering processes. In order to investigate the stability changes of heavy oil emulsions and their mechanisms after supercritical CO2 (scCO2) flooding, a device that could simulate the scCO2 treatment condition in the oil reservoir was first designed and used to pretreat the heavy oil. Then, the effects of scCO2 treatment on the stability of heavy oil emulsion were investigated by means of a bottle test and microscopic observation. The results revealed that the stability of the emulsion formed by scCO2-treated degassed heavy oil was improved. The reason for the stability improvement was then deeply explored from two aspects, i.e., the bulk viscosity and the structural strength of the water–oil interface. On the one hand, it was found that the content of heavy components in crude oil was increased due to the extraction of light components by scCO2, and the associating degree between asphaltenes was enhanced at the same time, both of which increased the apparent viscosity of the heavy oil and its emulsion, thus lowering the collision probability between dispersed droplets. On the other, with the help of interfacial rheological experiments, the interfacial dilational modulus was found to be increased after scCO2 treatment due to increased adsorption of interfacial active components in heavy oil such as asphaltenes, indicating that the structure of the interfacial film was strengthened and accordingly the emulsion became a more stable system.

To remove CO2 from CH4, tetraethylenepentamine was grafted onto coordinatively unsaturated centers of MIL-101(Cr) by postsynthetic functionalization: wet impregnation at 298 K, followed by grafting, drying, and washing. Compared to MIL-101(Cr), TEPA–MIL-101(Cr) showed 54% higher CO2 adsorption at 1 bar and 98% reduction of CH4 adsorption at 60 bar. The ideal adsorption solution theory (IAST) selectivity of CO2/CH4 for a binary gas mixture of 2% CO2 + 98% CH4 at 298 K and 60 bar predicted by the Toth equation was found to be 11 and 598 for ungrafted and grafted MIL-101(Cr), respectively. Single column breakthrough tests were performed for upgrading the 2% CO2 + 98% CH4 mixture to liquefied quality of natural gas (CO2 < 50 ppm) under various operating conditions including different temperatures and total amount of purge gas at the fixed pressure of 60 bar and temperature of 298 K. At the feed flow rate of 1000 sccm, the TEPA–MIL-101(Cr) extrudates obtained 0.89 mmol/g CO2 adsorption capacity and nearly 83% of adsorbed CO2 can be removed by regenerating extrudates at 393 K with 79 cm3/gadsorbent of total amount of purge gas.

CO2 cyclic injection is a promising method for enhanced shale oil recovery. However, the enhanced shale oil recovery mechanism is unclear, especially the adsorption and dissolution of CO2 and oil in kerogen. Therefore, it is of great importance to study the adsorption and dissolution mechanisms of CO2 and oil mixtures in shale. In this study, a new experimental apparatus was designed to test the change in the mole fractions of CO2 and oil before and after adsorption and dissolution at equilibrium conditions. For simplicity, n-dodecane (n-C12) was used as the oil. The adsorption and dissolution amounts of CO2 and n-C12 were obtained using a mathematical method. Moreover, the adsorption and dissolution characteristics of the CO2 and n-C12 mixtures in shale and the effect of pressure on the adsorption and dissolution amounts were studied. Finally, the swelling factor of the shale, which was caused by the dissolution of the mixtures, was calculated from the experimental results. The results show that dissolved n-C12 in shale could be replaced by CO2 when the mole fraction of CO2 in the free phase was larger than a threshold. The adsorption and dissolution amounts of CO2 and n-C12 increased with pressure. The lower pressure and larger mole fraction of CO2 enabled a lower swelling factor of shale. This study provides a straightforward method to experimentally determine the adsorption and dissolution properties of shale, which can be used to evaluate enhanced shale oil recovery by CO2 injection and the geological storage of CO2.

A circulating fluidized bed (CFB) reactor composed of a pyrolyzer and combustor was developed to observe tar emission during pyrolysis of low rank coal. Tar emission in the CFB pyrolyzer was examined under a wide range of operating conditions. Emissions of light tar substances (e.g., benzene, toluene, naphthalene, etc.) could be suppressed at 973 K by enhancement of contact between tar and resultant char in the pyrolyzer (i.e., enhancement of the volatile–char interaction (VCI)). It was also confirmed that about 50% of the heavy tar fraction emissions could be suppressed by the enhancement of VCI at 973 K. These trends were also observed at higher temperature (1173 K). A certain amount of heavy tar was emitted even after enhancement of VCI, so the mechanism of tar elimination was qualitatively determined using Spiral-type TOF-MS. The heavy tar was homogeneously deposited on the char and then was cracked to form lighter fractions by enhanced contact between tar and resultant char during pyrolysis.

This paper explores the applicability of nuclear magnetic resonance (NMR) technology on pore size distribution (PSD) and movable fluid distribution (MFD) in tight sandstones. Centrifugation experiments and NMR tests are performed on saturated samples. The fluid changes in pores corresponding with three different types of NMR T2 distribution after each centrifugation is then analyzed. In addition, a new method to determine the conversion factor from NMR T2 distribution to PSD is developed. In comparison with the PSD obtained by mercury intrusion porosimetry, the new method is more suitable for PSD calculation in tight sandstones. Afterward, the optimum centrifugal force to determine the threshold radius for fluid flow is obtained. On the basis of this, we analyze MFD in tight formation. Through study, the following results are arrived at: patterns of NMR T2 distributions of outcrop and subsurface cores at water saturation condition can be classified into three types (I, II, and III). Among which, type I and type II show a better pore connectivity than type III with NMR T2 distribution of a higher movable peak and a lower immovable peak. The optimum centrifugal force for the Chang 6 tight formation to determine movable fluid is 418 psi and pores show no obvious difference with throats when radii are less than 0.05 μm. Movable fluids are mostly controlled by throats with radii smaller than 1 μm, especially throats with radii between 0.3 and 1 μm. Movable fluids are mostly stored in pores around the movable peak of bimodal NMR T2 distribution with radii ranging from 10 to 100 μm. These pores are residual interparticle pores and dissolution pores. The sets of experiments and the new method presented in this paper are proved effective in quantitively describing PSD and also qualitatively evaluating pore throat connectivity in tight sandstones. Petrophysical characterization by NMR technique provides an effective approach to better understand pore throat structures and storage capacity of tight oil reservoirs.

Understanding of the absolute adsorption behavior of CH4 on shale is critically important in estimating shale gas storage in shale gas reservoirs. In this work, two approaches are applied to obtain the absolute adsorption isotherms of CH4 on shale samples. In the first approach, we first measure the excess adsorption isotherms of CH4 on two shale samples at the temperature of 298.15 K and pressures up to 12.0 MPa. Then, grand canonical Monte Carlo (GCMC) simulations are used to calculate the adsorption-phase density; such density values are consequently applied to calibrate the measured excess adsorption and obtain the accurate absolute adsorption isotherms. As for the second approach, we apply the low-field nuclear magnetic resonance (NMR) method to describe the absolute adsorption of CH4 on shale. A NMR-based setup is designed to measure the T2 spectrum distributions in shale samples by injecting CH4 into dry shale samples. The injecting pressure is set up to 12.0 MPa, which is similar to the conditions used in the excess adsorption measurements. On the basis of the measured T2 spectrum and the injected molar amount of CH4, the adsorbed molar quantity of CH4 can be assessed on the shale samples under specific conditions. We then compare the absolute adsorption isotherms obtained from both methods and evaluate the capability of the NMR approach in determining the absolute adsorption of CH4 on shale. With GCMC simulations, we find that the calculated adsorption-phase density strongly correlates with the system pressure and temperature. By taking into consideration the adsorption-phase density, the absolute adsorption isotherm is always higher than the measured excess adsorption curves; that is, the measured excess adsorption underestimates the actual adsorption capacity on shale. On the basis of the comparison results, the adsorption isotherms obtained from the NMR method have a good agreement with the corresponding absolute adsorption isotherms after calibrating with the adsorption-phase density; it indicates that the low-field NMR-based setup is a good tool in obtaining the absolute adsorption isotherms of CH4 on shale.

In this research, an ethoxylated amine surfactant is co-injected with CO2 in a series of coreflooding experiments at typical Middle Eastern reservoir conditions of high temperature, high salinity, and in situ foam is generated to reduce gas mobility in the absence of oil. The effects of reservoir permeability, injection rates, and foam quality on mobility reduction factor (MRF) and apparent viscosity of foam are discussed. In the absence of oil, an optimum foam quality of 80% is obtained using 1 wt % of surfactant solution. Shear thinning foams with viscosities ranging between 0.9 and 2.4 cP were formed at all velocities tested in this study. MRFs of 50 and 70 were obtained, respectively, in 70 and 240 mD cores at 80% foam quality, confirming that foam strength increases with increasing rock permeability. After determination of optimum foam quality and flow rate, a final coreflooding experiment was conducted in the presence of oil to quantify the effect of oil presence on foam generation and to observe the recovery performances of supercritical CO2 and CO2 foam for secondary and tertiary recovery injections. In the presence of oil, relatively weak foams were generated in a 50 mD core having apparent viscosities of 0.66, 1.65, and 3.29 cP at the tested co-injection flow rates of 0.2, 0.5, and 1 mL/min at 80% foam quality. A total recovery factor of 88.32% was obtained, with CO2 and CO2 foam floods contributing 79.34% and 8.98%, respectively.

During the fracking process in shale, an interaction occurs between shale and fracking fluid that contains a cocktail of chemicals. One of the chemicals used in fracking fluid is often surfactant, which is generally used as a viscofier. However, surfactants also have the potential of significantly influencing the wettability and thus gas desorption–key factors affecting ultimate gas recovery from shale reservoirs. Even though a few studies discussed the ability of surfactants to alter wettability in shale, the implication of that change in adsorption/desorption behavior has never been experimentally investigated beyond hypothetical inferences. In this study, the influence of the wettability change by anionic surfactant on gas adsorption/desorption behavior in shale was investigated through a series of experiments. Baseline wettability readings of two shale samples were established by measuring the contact angles (BG-1 = 22.7°, KH-1 = 35°) between a drop of pure water placed on their polished surfaces, indicating that the affinity of pure water for the BG-1 surface was greater than that for KH-1. This difference can be attributed to the higher clay content and lower total organic carbon found in BG-1 as compared to KH-1. To investigate the impact of the interaction between shale and surfactants on wettability during the fracking process, we measured the contact angles again, this time with 1 wt % solution of internal olefin sulfate surfactant. The surfactant-induced wettability changes of the two shale samples were investigated by measuring the contact angles again (BG-1 = 3.5°, KH-1 = 19.2°) between a drop of surfactant solution and their polished surfaces. The effect of wettability changes on gas adsorption/desorption was then evaluated utilizing the United States bureau of mines’ modified method. Experiments were conducted on the two shale samples in two ways: after pure water treatment, and after surfactant treatment. The results suggest that due to the wettability alteration of the two shale samples by IOS surfactant toward more water-wet during the treatment, the methane adsorption/desorption characteristics were influenced. In BG-1 sample, IOS solution dramatically changed its wettability to become completely water-wet. Therefore, the volume of desorbed methane dropped by nearly 54%. A similar but less pronounced influence was found in the KH-1 sample, where its desorbed methane dropped by 10% because of wettability alteration toward more water-wet. These reductions in the amount of desorbed gas suggest that prior to selecting a surfactant for addition to fracking fluid, its effect on wettability and gas desorption should be investigated to optimize shale gas recovery potential.

Solvent bitumen extraction processes are alternatives to thermal processes with potential for improved economic and environmental performance. However, solvent interaction with bitumen commonly results in in situ asphaltene precipitation and deposition, which can hinder flow and reduce the process efficiency. Successful implementation requires one to select a solvent that improves recovery with minimal flow assurance problems. The majority of candidate industrial solvents are in the form of mixtures containing a wide range of hydrocarbon fractions, further complicating the selection process. In this study, we quantify the pore-scale asphaltene deposition using two commonly available solvent mixtures, natural gas condensate and naphtha, using a microfluidic platform. The results are also compared with those of two typical pure solvents, n-pentane and n-heptane, with all cases evaluated with both 50 and 100 μm pore-throat spacing. The condensate produced more asphaltenes and pore-space damage than the naphtha and exhibited deposition dynamics similar to that of pentane and heptane. This similarity is due to the presence of a large amount of light hydrocarbon fractions in condensate (∼85 wt % of C5s–C7s) dictating the overall deposition dynamics. Naphtha, which contains heavier fractions (∼70 wt % of C8s–C11s) and aromatic/naphthenic components, generated less asphaltenes and exhibited a slower deposition rate, resulting in less pore damage and overall better performance.

It is hypothesized that only a fraction of the asphaltenes acts to stabilize emulsions and that this fraction consists of the most self-associated (least soluble) asphaltenes. To test the hypothesis, the effects of removing the least soluble versus the most interfacially adsorbed asphaltenes on emulsion stability, film properties, and mass surface coverage were compared. The least soluble asphaltenes were removed by precipitation from solutions of asphaltenes in heptane and toluene. The most adsorbed asphaltenes were removed by separating an asphaltene-stabilized emulsion from its continuous phase. Brine-in-oil emulsions were prepared using organic phases of 10 g/L of the residual asphaltene fractions from the supernatant or continuous phase. The stability of the emulsions was assessed in terms of percentage of water resolved after repeated treatment cycles involving heating at 60 °C and centrifugation at 3500 rpm. The three asphaltenes examined were extracted from a mined oil sand bitumen, a bitumen from a cyclic steam process, and a bitumen from a SAGD process. Only some of the species in the asphaltenes were found to strongly stabilize emulsion, and the size of this fraction ranged from 2% to >65% in the three samples of this study. The most adsorbed, highly stabilizing material tended to be concentrated in the least soluble fraction of the asphaltenes, consistent with the proposed hypothesis. The emulsion stability data were generally consistent with a previously observed threshold of 5 mg/m2 asphaltene surface coverage for stable emulsions. Fractionating the asphaltenes eventually removed enough of the self-associated material that the surface coverage dropped below the threshold and unstable emulsions were observed.

The Oltu Gemstone is located in the north of Oltu town (Erzurum–NE Turkey) city as a low rank coal. The Oltu Gemstone occurs as lenticular forms with thickness not exceeding centimeter size and lateral continuity of a few meters within the Liassic–Lower Malm Olurdere Formation consisting chiefly of claystone, sandstone, and volcanics. Coals that are operated as Oltu Gemstone are represented by very high TOC (67.39–78.56% wt), high hydrogen index (HI) values (314–379 mg HC/g TOC) and very low oxygen index (OI) values (1–3 mg CO2/g TOC). Low Pr/Ph ratios indicate that coals were prevented from oxidation and deposited under anoxic conditions. In Oltu Gemstone samples, C29 dominates over C27 and C28 steranes. In general, high (C19 + C20)/C23 tricyclic terpane, low Ts/(Ts + Tm), diasterane/sterane, and C31R/C30 hopane ratios were recorded. C29 MA steroids dominate with respect to others, and the C29/(C28 + C29) MA ratio is mostly high. DBT/P ratio of Oltu Gemstone samples has low values. Tmax values of Oltu Gemstone samples (between 416 and 436 °C) reflect immature–early mature character. 22S/(22R + 22S) homohopane, 20S/(20R + 20S), and ββ/(αα + ββ) sterane ratios and low moretane/hopane ratios, relatively high C28-TA/(C29-MA + C28-TA), MA(I)/MA(I + II), TA(I)/TA(I + II), MPI-3 (β/α MP), and MDR ratios indicate early mature character for the Oltu Gemstone samples.

Air-staged combustion is one of the most sophisticated and effective technologies for reducing NOx emission during pulverized coal combustion. However, it may also result in problems of high-temperature corrosion, slagging, and high-imperfect/incomplete combustion loss. In order to prevent these problems, the multihole wall air coupling with air-staged technology (MH&AS) has been developed. The aim of this work is to investigate the impact of MH&AS on NOx emission by applying a laboratory scale of a MH&AS furnace. The results show that there existed an optimal multihole wall air ratio to significantly reduce the NOx emission. For example, with burner air ratios of 0.6, 0.7, 0.8, and 0.9, the corresponding optimal multihole wall air ratios were 0.100, 0.075, 0.050 and 0.025, respectively. The air distribution mode with a smaller burner air ratio and its optimal multihole wall air ratio were more conducive for NOx reduction. Furthermore, the influence of coal properties on NOx emission was also evaluated. The higher the fuel ratio, the larger the optimal multihole wall air ratio, whereas the finer the pulverized coal, the smaller the optimized multihole wall air ratio. There was a critical moisture content for the specified coal to obtain the minimum of NOx emission. In addition, the effect of MH&AS on the burnout was also explored. The optimal multihole wall air ratio could simultaneously make a minimum amount of NOx emission and the ultimate value of burnout. Finally, the mechanism of NOx reduction by char during MH&AS combustion was proposed.

The Ordovician hydrocarbon migration and accumulation of the Tazhong Uplift in the Tarim Basin, northwest China, is investigated from the perspective of geological and geochemical analysis. Geochemical parameters successfully analyzed include the oil and gas properties, 17α-22,29,30-trisnorhopane/(17α-22,29,30-trisnorhopane + 18α-22,29,30-trisnorhopane) ratios, and the carbon isotope ratios of gas. Results show anomaly parameter values are observed in the no. 10 fault belt (10FB) and the no.1 fault belt (1FB). As the distance from the 10FB and 1FB increases, the parameter value anomalies weak gradually until then become disappeared in the north platform belt (NPB). This saddle-like distribution of parameters indicates the hydrocarbon is introduced into the Ordovician through 10FB and 1FB from the northern Manjiaer Depression and the uplift itself. This new conclusion is different from the conventional view to a large extent, which indicates that Ordovician hydrocarbon mainly derive from the Manjiaer Depression, and the no.1 fault is the only NW-trending oil source fault. The viewpoint of 10FB as an additional hydrocarbon charge place is further supported by the evidence from the hydrocarbon charge intensity, structural framework, source rock distribution, and significant improvement of the reservoir physical property (7–8 times that at the 10FB). Based on this hydrocarbon charge and migration process and patter, the main target for further exploration activities in the Ordovician of the Tazhong Uplift should be the SPB (south platform belt) and the south part of the 10FB, especially the southern part of the 10FB.

We report for the first time the results from a systematic investigation of how asphaltenes of different polarity affect crystallization and gelation of waxy oils. The more polar asphaltenes were found to be more aromatic in nature and more highly self-aggregated in the solvent. The presence of less polar asphaltenes in the waxy oil reduced the wax appearance temperature and wax precipitation to a greater degree compared to more polar asphaltenes, which was mainly attributed to the difference in the aggregation state of asphaltenes of different polarity. Reducing the polarity of asphaltenes present in the oil also resulted in a lower gelation temperature, lower storage modulus, and lower yield stress, which was probably because the less polar asphaltenes were more similar to wax on the molecular level and, thus, more readily interacting with wax. Notably, a 99% reduction in the yield stress was observed upon the addition of the least polar asphaltenes examined in the present work, in contrast to the 62% yield stress reduction upon the addition of the most polar asphaltenes. This observation may be of industrial significance because it suggests that the crude oil containing less polar asphaltenes may form a softer gel or deposit that is more easily broken or removed. Microscopic analysis showed that the wax crystals precipitated in the presence of less polar asphaltenes have a smaller aspect ratio.

The throughput of pyrite extraction from coal using the conventional magnetic separation method can be effectively improved by increasing the magnetic susceptibility of pyrite. The electromagnetic characteristics and absorption response of fine high-sulfur coal were studied to evaluate the strengthening effect of microwave treatment on the magnetic susceptibility of pyrite. In actual production, the microwave treated pyrite was affected by oxygen and water vapor in the air. Magnetism of fine coal stored under room temperature in air for long term will become weaker, due to the formation of pyrrhotite. Also, the pyrite is not stable in air during the microwave pretreatment process. Due to the porosity of fine coal, when it is placed in air, oxidation reaction occurs between a small amount of oxygen and coal pyrite. This is the reason for the decrease in the specific magnetic susceptibility and the weakening of the magnetic behavior of fine coal. Analysis of different sputtering times indicates the different depths from the surface. During the microwave treatment, pyrite Fe2(SO4)3 and ferrous sulfate FeSO4 are mainly present on the surface of pyrite, and surface oxidation takes place. The relative content of Fe2(SO4)3 in the treated coal is higher than that of FeSO4, which indicated that the study proposed a novel way for the coal desulfurization pretreatment.

In situ combustion (ISC) is advantageous for (ultra)heavy reserves due to its high heating efficiency and small surface footprint compared to steam injection. Herein, the focus of this work was given to the key factor in sustaining the continuity of the combustion front, the asphaltene fraction. Structure–property alterations of Tahe asphaltenes caused by low temperature oxidation (LTO) were thoroughly examined. Particular attention was placed on its combustion and pyrolysis kinetics. The results showed that after LTO 10.35 wt % coke was formed. Scanning electron microscopic observations indicated that the surfaces of the oxidative products were fairly rough as a result of air attack and the caused reactions on site, and these alterations promoted the subsequent combustion. The textures of the products were observed to be further compacted and condensed after LTO. As anticipated, distinguished reaction regions were clearly identified on the thermogravimetric (TG)/differential scanning calorimetric curves in this work. The results of TG and activation energy revealed the differences of the reaction sites in the combustion and pyrolysis processes. The coke formed after LTO exhibited the highest reaction activity and exothermic effect compared to the fresh asphaltenes and residue. It is believed that this work can add new insights to ISC with regard to the mechanisms and reaction models, which are highly valuable for field applications.

It is well-known that shale gas production is affected by the wettability of the reservoir. In this work, two gas-wetting alteration agents were synthesized and characterized by 1H NMR and FTIR. To evaluate the effect of the gas-wetting alteration agents on the shale wettability, the contact angle for droplets on the shale surface was detected, and the results showed that the contact angles of water and n-hexadecane increased from 36° and 0° to 119° and 88° after treatment with sodium [N-propyl-N-(perfluorooctanoyl)amino]acetate (SCF-102), while the contact angles increased to 122° and 110°, respectively, after treatment with sodium [N-[[N-(perfluorooctanoyl)amino]ethyl]amino]propionate (SCF-113). The surface free energy rapidly decreased from the primeval 72 to 10.3 and 6.8 mN/m at equal concentration. These values agreed with the results of spontaneous imbibition, the capillary tube rise test, and the fluid flow test. Additionally, the analysis with energy dispersive spectroscopy and scanning electron microscopy revealed that the fluorine-containing adsorption layer was formed and the roughness of the shale surface was significantly increased. This indicated that the gas-wetting surface can be achieved by using the gas-wetting alteration agents. The above results confirmed that the wettability of the shale surface is altered from the original water-wetting or oil-wetting to gas-wetting. Furthermore, the thermal analysis exhibited that the two gas-wetting alteration agents have good thermal stability under 165 and 216 °C, respectively. It demonstrated that they have greater potential to be applied to high-temperature reservoirs.

The computer-aided reconstruction of gasoline composition is an active area of petroleum and petrochemical research as a result of the demand for molecular-level management of the petroleum feed streams. To that end, in this work, a molecular compositional model based on a predefined representative molecular set was built that allows for the conversion of conventional bulk property data to an approximate molecular composition. The selection of representative molecules was based on their presence in gasoline molecular compositional measurement and their potential contribution to the key physical properties. Around 170 hydrocarbons and heteroatom species were chosen as predefined identities of molecules that can exist in a gasoline sample. The physical property data of all of the representative molecules were collected, and suitable mixing rules for the gasoline range stream were applied for the accurate prediction of bulk properties. The approximate concentration of representative molecules was obtained through fitting the predicted bulk property to the measured data. The methodology was verified through intensive tests on various gasoline samples, including straight-run naphtha, catalytic cracking gasoline, coking gasoline, and reformates. The modeling was also accomplished in a sequential order using basic to advanced measurements to find the optimum number of measurements required for detailed composition evaluation on various feedstocks. The propagation of error in the experimental measurement and prediction method on composition has been evaluated.

One of the much debated mysteries in 1H NMR relaxation measurements of bitumen and heavy crude oils is the departure from expected theoretical trends at high viscosities, where traditional theories of 1H–1H dipole–dipole interactions predict an increase in T1 with increasing viscosity. However, previous experiments on bitumen and heavy crude oils clearly show that T1LM (i.e., log-mean of the T1 distribution) becomes independent of viscosity at high viscosities; in other words, T1LM versus viscosity approaches a plateau. We report 1H NMR data at ambient conditions on a set of pure polymers and polymer–heptane mixes spanning a wide range of viscosities (η = 0.39 cP ↔ 334 000 cP) and NMR frequencies (ω0/2π = f0 = 2.3 MHz ↔ 400 MHz) and find that at high viscosities (i.e., in the slow-motion regime) T1LM plateaus to a value T1LM> ∝ ω0 independent of viscosity, similar to bitumen. More specifically, on a frequency-normalized scale, we find that T1LM> × 2.3/f0 ≃ 3 ms (i.e., normalized relative to 2.3 MHz), in good agreement with bitumen and previously reported polymers. Our findings suggest that in the high-viscosity limit T1LM> and T2LM> for polymers, bitumen, and heavy crude oils can be explained by 1H–1H dipole–dipole interactions without the need to invoke surface paramagnetism. In light of this, we propose a new relaxation model to account for the viscosity and frequency dependences of T1LM and T2LM, solely based on 1H–1H dipole–dipole interactions. We also determine the surface relaxation components T1S and T2S of heptane in the polymer–heptane mixes, where the polymer acts as the “surface” for heptane. We report ratios up to T1S/T2S ≃ 4 and dispersion T1S(ω0) for heptane in the mix, similar to previously reported data for hydrocarbons confined in organic matter such as bitumen and kerogen. These findings imply that 1H–1H dipole–dipole interactions enhanced by nanopore confinement dominate T1S and T2S relaxation in saturated organic-rich shales.

The morphological evolution of a single char particle with a low ash fusion temperature (Tf) was investigated during the whole gasification process using a high-temperature stage microscope. The experimental results showed that the final shrinkage ratio of char particles at the temperature above Tf (1300 °C) was higher than that below the deformation temperature (1000 °C). The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis results showed that the ash distribution in coal char was uniformly dispersed. Dispersed molten slag gradually aggregated to the molten slag layer during the gasification process at the temperature above Tf, and the slag layer evidently hindered the diffusion of the gasifying agent. Therefore, there was a critical shrinkage ratio during the gasification process when the temperature was above Tf and the critical shrinkage ratio of Xiaolongtan lignite (XLT) char particles was 0.7–0.8. The SEM–energy-dispersive X-ray spectroscopy (EDS) analysis results indicated that the critical points in the curve of the shrinkage ratio with time were related to the molten slag on the char surface. In addition, the reaction mechanism in this experiment was analyzed. The calculating results indicated that the critical thickness of the molten slag layer of XLT and Shenfu bituminous (SF) coal chars with different ash contents showed good agreement and the critical thickness of the slag layer was 6–18 μm. Finally, the sensitive analysis was performed to analyze the factors affecting the calculating results.

In this work, the temperature characteristics of hydrate slurry related to transition heat in the cyclopentane (CP)/methane (CH4) hydrate formation process were systematically investigated. A crystallizer with a special heat-insulating layer of aerogel was designed to hold the transition heat, and the hydrate slurry could be heated in the crystallizer. Temperatures were measured in the process of the hydrate formation under the conditions of different operating pressures, volumes of solution, methods of gas injection, and volume ratios of CP to water. The highest temperature of hydrate slurry (Th) and the maximum temperature difference (ΔTmax) relative to the initial temperature were adopted to evaluate the influence of different conditions. The experimental results indicated that the hydrate formation interface and thermal interface obviously move from the initial gas/CP interface and CP/water interface toward the bulk solution. Both the increase of operating pressure and the decrease of solution volume have positive effect on enhancing the hydrate slurry temperature. In addition, the volume ratio of CP to water also significantly affects the fluctuation of the hydrate slurry temperature. The hydrate slurry could be heated up to 294.45 K and the ΔTmax of 16.30 K could be obtained, and such high heat could be effectively collected and used elsewhere.

Both polymeric pour point depressants (PPDs) and asphaltenes can improve the flowability of waxy oils. However, the effect of polymeric PPDs together with asphaltenes on the flowability of waxy oils is not clear. In this paper, the synergistic effect of ethylene–vinyl acetate (EVA) PPD (100 ppm) and resin-stabilized asphaltenes (0.75 wt %) on the flow behavior of model waxy oils (10–20 wt % wax content) was investigated through rheological tests, DSC analysis, microscopic observation, and asphaltenes precipitation tests. The results showed that the asphaltenes disperse well in the xylene/mineral oil solvent as small aggregates (around 550 nm) with the aid of resins. The EVA or asphaltenes alone moderately improve the flow behavior of waxy oils by changing the wax crystals’ morphology from long and needlelike to a large, radial pattern or fine particles, respectively. The wax precipitation temperatures (WPTs) of waxy oils are also slightly decreased by adding EVA or asphaltenes, meaning that the cocrystallization effect between the additives and waxes is dominant. The addition of EVA together with asphaltenes cannot further decrease the WPT, but it can dramatically decrease the pour point, gelation point, G′, G″, and apparent viscosity of waxy oils, indicating that a synergistic effect exists between EVA and asphaltenes. The synergistic effect deteriorates upon increasing the wax content of waxy oils. The EVA molecules can adsorb on the surface of asphaltene aggregates, thus inhibiting the asphaltenes precipitation and forming the EVA/asphaltenes composite particles. The formed composite particles can act as wax-crystallizing templates and then greatly change the wax crystals’ morphology into large, compact, and spherelike wax crystal flocs, thus dramatically improving the waxy oil flow behavior. This work enriches the theory of micro/nano composite PPDs, which is helpful for developing new PPDs with high efficiency.

Mercury intrusion capillary pressure (MICP), nuclear magnetic resonance (NMR), routine core analysis, thin sections, and scanning electron microscope (SEM) analysis were used to gain insight into the pore structure of the Eocene Sha-3 (the third member of the Shahejie formation) low-permeability sandstones in the Raoyang sag, including pore type, pore geometry, and pore size. Quantitative NMR parameters and petrophysical properties were integrated to build up the relationship between microscopic pore structure and macroscopic performance. The pore systems of Sha-3 sandstones are dominantly of residual intergranular pores, intragranular dissolution pores, and intercrystallite micropores associated with authigenic clay minerals. The high threshold pressure and low mercury withdrawal efficiencies from MICP analysis indicate the poor pore connectivity and strong heterogeneous. Both uni- and bimodal transverse relaxation time (T2) spectrum can be found because of the coexistence of small and large pores, and the T2 of major pore size occurring at about 1.0 to 100 ms. The Sha-3 sandstones have a relatively high irreducible water content and short T2 components in the T2 range. Long T2 components can only be observed in samples rich in large pores or microfractures. T2gm (the geometric mean of the T2 distribution) correlates well with irreducible water saturation and permeability. A methodology for pore structure classification is presented integrating NMR parameters of T2gm, bulk volume of immovable fluid (BVI), and petrophysical parameters such as reservoir quality index (RQI) and permeability. Consequently, four types of pore structures (types A, B, C, and D) are identified, and characteristics of individual pore structure are summarized. The comprehensive analysis of NMR measurements combined with thin sections, SEM and MICP analysis is useful for describing microscopic pore structure, which is important to maintaining and enhancing petroleum recovery in low-permeability sandstone reservoirs.

Electromagnetic heating techniques have recently received significant attention as alternatives to conventional heating methods for thermal processing of viscous and heavy oils. One of the benefits of electromagnetic heating is that the electromagnetic field can penetrate the viscous oil and the rock matrix, allowing heating to take place a significant distance from the electromagnetic source. Opportunities exist for electromagnetic heating in overcoming the heat-transfer limitations within viscous oils and potentially as a down-hole or in situ heating technique to raise the temperature within a reservoir. The fundamental interaction of electromagnetic energy with viscous and heavy oils and their constituent components is poorly understood, and this study enhances the understanding of these interactions at microwave frequencies by establishing the effect of temperature on the dielectric properties of heavy oil and its SARA fractions. The dielectric properties of two heavy oils were studied at temperatures up to 300 °C and frequencies from 900 MHz to 3.0 GHz. The loss factor of both oils was found to increase significantly with temperature, which was linked to a corresponding reduction in viscosity. It is shown for the first time, contrary to previous assertions in the literature, that aromatics and resins are the main contributors toward dielectric loss in heavy oils, whereas saturates and asphaltenes were found to have a negligible influence on the loss factor of the oil. Thus, it will be seen that, at higher temperatures or where there is a high abundance of aromatics and resins, the oils are more susceptible to being heated directly with microwaves, opening up new opportunities for microwave processing of oils in refinery and field settings without the need for microwave-absorbing additives.

Supercritical carbon dioxide (scCO2) is considered to be an excellent candidate for miscible gas injection (MGI) because it can reduce oil viscosity, induce in situ swelling of the oil, and reduce the IFT of the in situ fluid system. However, the unfavorable mobility associated with scCO2 flooding poses a major challenge due to the large viscosity contrast between the crude oil and scCO2, resulting in viscous fingering. An effective approach to overcome this challenge is to increase the viscosity of scCO2 (scCO2 thickening) to effectively control gas mobility and improve the sweep efficiency. The primary focus of this study was on an oilfield (Field A) that is located in the Harweel cluster in southern Oman. In this work, we present results in which the suitability of a library of commercially available polymers capable of thickening scCO2 at a high temperature (377 K). Previous studies have focused on the use of polymers as viscosifiers at much lower temperatures. Out of 26 potential polymers, 4 polymers (poly(1-decene) (P-1-D), poly(ethyl vinyl ether) (PVEE), poly(iso-butyl vinyl ether) (Piso-BVE), and poly(dimethylsiloxane) (PDMS)) were found to be completely soluble in scCO2 at 377 K and 55 MPa. Given the relatively low viscosity of oil in Field A (0.23 cP), P-1-D and PVEE could be considered as effective thickeners under the in situ conditions relevant to this field. In addition, Piso-BVE was found to be less effective because it did not change the CO2 viscosity above 358 K (55 MPa) when used at a concentration of 1.5 wt %. Furthermore, although it was determined that increasing the side chain length of poly alkyl vinyl ethers would enhance the solubility of this polymer in scCO2, it was determined to be ineffective in noticeably changing the CO2 viscosity. In general, increasing temperature resulted in a decrease in the relative viscosity, while increasing the pressure caused a slight increase in relative viscosity at all temperatures and concentrations.

Accurate description of diagenetic controls on reservoir quality in “tight” sandstones can be difficult because of the inherent fine grain size and complex components of such oil reservoirs. In this study, petrological techniques and nuclear magnetic resonance (NMR) analysis were applied to fine-grained tight sandstones with varying grain sizes in order to reveal the diagenetic controls on reservoir quality. Results show that macropores in tight sandstones occur mainly as intergranular and dissolution pores, whereas micropores are distributed within ductile rock fragments, clay, and mica minerals, as well as occurring as dissolution micropores. Pore size distribution (PSD)/T2 spectra display three distribution patterns: (i) a macropore-dominant bimodal distribution, (ii) a macropore–micropore bimodal distribution, and (iii) a micropore-dominant skewed distribution. A decrease in grain size correlates with weaker framework support of particles and thus more intensive mechanical compaction, resulting in the loss of both macroporosity and microporosity. Consequently, PSD change from macropore-dominant bimodal distributions to micropore-dominant skewed distributions as the pore type shifts from being dominated by macropores to intragranular micropores. In fine-grained sandstones, an increase in the abundance of ductile components corresponds to a loss of total porosity, related to the decrease in abundance of macropores, whereas the change in micropore abundance is negligible. This change is reflected in PSD by a shift from macropore-dominant bimodal distributions to macro–micropore bimodal distributions. The authigenic minerals in tight sandstone reservoirs occur mainly as late-stage carbonate minerals, and the precipitation of this carbonate cement preferentially occurs within macropores. When carbonate cement content is low, it has a limited influence on total porosity. However, it does significantly reduce the connectivity of the pore system, which is different from what might be expected in conventional sandstone reservoirs. Therefore, particle grain size, the abundance of ductile components, and late-stage cementation all contribute to the prediction of reservoir quality in oil-bearing tight sandstones.

The expanded fluid (EF) model is known for its capacity to calculate the viscosities of crude oil and its mixtures with solvents at high pressure and temperature using a cubic equation of state with a minimum amount of experimental data. The main drawback of the EF model is usually the requirement of a proper plus-fraction characterization and accurate density input data. In this study, the sensitivity of the EF model to the characterization method and the density of the oil was evaluated against viscosity data on reservoir fluids. The oil viscosity was calculated above and below the saturation pressure in order to compare the EF model with other viscosity models available in the literature. The results confirmed that the viscosity strongly depends on the quality of the density predictions as well as on a good description of the phase behavior below the saturation pressure. This demonstrates that proper characterization is needed in order to calculate the oil viscosity accurately. Furthermore, a new tuning method with minimum experimental data improved the viscosity prediction as a function of pressure.

Accurate and fast prediction of the gas emissivity in a wide range of pressure and temperature is very essential for the accurate and efficient simulation of the combustion and gasification processes. In this work, the total emissivities of the main radiant species including H2O, CO2, CO, and their mixtures are first generated with the line-by-line (LBL) model and the HITEMP-2010 spectroscopic database at different total pressures varying from 0.1 atm to 30 atm and at different temperatures varying from 300 K to 2500 K. Then, the exponential wide band model (EWBM) is modified according to the LBL results and simplified using the polynomial fitting method and the table look-up scheme. Finally, a modified EWBM (M-EWBM) is presented. The performances of the EWBM, the M-EWBM, and the LBL model are comprehensively compared, and it is found that the M-EWBM is more accurate than the EWBM and can be as efficient as the weighted-sum-of-gray-gas model, making it very promising for the total gas emissivity prediction in the pressurized combustion and gasification simulations.

Zeta potential measurements and microscopic surface characterization and imaging were conducted on calcite and dolomite crystals aged in stearic acid model oil and exposed to different synthetic brines representing different potential scenarios of injected seawater from the Arabian Gulf. Calcite particles were negatively charged in deionized water and maintained negative surface charges in all tested brines, except in diluted Arabian Gulf seawater that contained higher concentration of Ca2+ and Mg2+ ions. Dolomite particles were positively charged in deionized water as well as in all tested brines, except in diluted Arabian Gulf seawater that contained four times higher concentration of SO42– ions. Scanning electron microscopy and atomic force microscopy experiments on cleaved calcite and dolomite chips showed different morphological changes when both samples were aged in model oil and then treated with brines. Calcite surface dissolution was observed in addition to stearic acid deposition. Surface elemental analysis using energy-dispersive spectroscopy showed Mg2+ and SO42– ions adsorb preferably on locations where stearic acid is deposited. The finding that stearic acid was adsorbing more strongly on dolomite than on calcite could indicate why the tested brines were less efficient to change the zeta potential of the dolomite systems. The current study concludes that manipulating the concentration of potential-determining ions present in the Arabian Gulf seawater, especially Mg2+ and SO42– ions, will alter the surface charges of aged calcite and dolomite samples as well as their surface morphology.

The effect of various oxygen-containing compounds added and/or inherent O-species on coal fluidity and coke strength has been investigated in detail. When several O-containing compounds, which have different O-containing groups, are added independently to caking coal, the MF value almost decreases, and the extent of the decrease being ether < ketone < lactone < hydroxyl < acid anhydride < < ether/hydroxyl/lactone < carboxyl group. The COOH content in four coals used increases with decreasing C%, and the MF values decrease with increasing the content. The evolution of gaseous O-containing species (CO, CO2, and H2O) during carbonization at 3 °C/min of four coals up to 400 °C has been studied mainly with a flow-type quartz-made fixed-bed reactor to clarify the effect of the amount of O-containing gases evolved with the Gieseler fluidity of coal particles. A positive correlation is found between the amount of CO, CO2, or H2O evolved up to 400 °C and the COOH content in coal. However, a negative correlation between MF and O-containing gases evolved up to 400 °C is observed. It is suggested that the COOH amount and/or O-containing gases evolved have adverse effects on the thermoplasticity of coal. When the indirect tensile strength of coke prepared from pelletized samples is plotted against MF values, a positive correlation is found, whereas an inverse correlation is observed between the indirect tensile strength and COOH in coals used or the O-containing gases evolved up to 400 °C during carbonization. These observations indicate that some of the oxygen-functional groups naturally present in coal have a negative effect on coal fluidity and that this effect is particularly strong in carboxyl, which can readily be decomposed into gaseous oxygen-containing species during heating up to the initial softening temperature.

A series of CoMo catalysts supported on various Al2O3 supports added with TiO2 were prepared to investigate the addition effect of TiO2 on formation of an active phase on sulfided CoMo/Al2O3 catalyst. The catalytic activity tests were carried out with hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene, hydrodenitrogenation (HDN) of acridine, and hydrodearomatization (HDA) of o-xylene, 1-methylnaphthalene (1-MN), and phenanthrene. A 20 wt % TiO2 added CoMoAlTi20 catalyst showed the lowest hydrogenation activity in HDA of 1-MN and phenanthrene and highest HDS and HDN activities. The property of a support and/or the interaction between active metal and the support significantly affect the formation of active sites for HDS and HDA. The active sites for HDS on sulfided CoMo catalysts were different from those for HDA and/or hydrogenation. The addition of TiO2 enhanced the reduction, the formation, and stacking number of CoMoS active slabs. The finding that desulfurization via the hydrogenation pathway (HYDS) activity increased while the HDA activity slightly decreased over TiO2 coated catalysts reveals that the increased amounts of formed CoMoS overcome the increase of the stacking number of CoMoS active slabs.

Antiagglomerants (AAs) are surfactants used in the upstream oil industry to prevent gas hydrate plugging in flow lines. Most, if not all, AAs used in the field today are cationic quaternary ammonium surfactants and function using the “hydrate-philic” mechanism. In this study, we have synthesized a series of butylated mono- and bis-amine oxide surfactants with aliphatic tails with chains of 9–17 carbon atoms and either amide or ester spacer groups. Their performance as hydrate-philic AAs has been investigated in a sapphire autoclave and sapphire rocking cells with a Structure II-forming natural gas mixture. There was generally good agreement regarding the performance and relative ranking of the surfactants between the two sets of equipment. The AA performance of the amine oxide surfactants depended on many factors, including the polar head and spacer groups, tail length, subcooling at hydrate onset, salinity, and the composition of the hydrocarbon fluid. Amido amine oxide surfactants performed better than the equivalent ester amine oxide, probably due to the stronger hydrogen-bonding ability of the amide group. The bis-amine oxide surfactants were designed with optimum interamine distance for best Structure II crystal growth inhibition and performed better as AAs than did the mono-amine oxide surfactants. The amido bis-amine oxide surfactants showed reasonable seawater biodegradation rates over 28 days, giving biological oxygen demand values of 25–40%. The bis-amine oxide surfactants in particular also showed a strong kinetic hydrate inhibition effect, which could be very useful for field applications. Thus, these surfactants could be used first as kinetic hydrate inhibitors (KHIs), and if for any reason hydrate formation does occur they could also function as AAs to prevent hydrate blockages under certain conditions.

Exploitation of deep extra heavy oil is a challenging work due to its high viscosity and high reservoir pressure. Supercritical water is first proposed as an injection agent, considering its favorable physiochemical properties. A novel flooding experimental system with a design temperature up to 450 °C and pressure up to 30 MPa was developed to demonstrate the feasibility of supercritical water flooding (SCWF) technology. A sand pack core with an adiabatic boundary was used to eliminate heat unbalance. The experimental results indicated that SCWF is a promising enhanced oil recovery technology. SCWF could significantly enhance oil recovery when compared with steam flooding and hot water flooding and reduce the oil viscosity simultaneously. SCWF at 25 MPa and 400 °C raised the recovery efficiency to 97.07% and reduced oil viscosity by 36.9%. The mechanism is attributed to the extraction heavy oil components into the water-rich phase by supercritical water and the formation of miscible flooding.

Formation of gas hydrates in oil/gas pipelines has to be properly managed as they can often lead to plugging, primarily by deposition, causing safety issues and significant expenses for repair and recovery. Early detection of hydrate deposition is thus critical for managing such risks and establishing stratagies for hydrate mitigation and remediation. Here, a permittivity probe is applied to a 1-in. vertical pipe system in order to detect hydrate deposition. The vertical pipe system simulates a deadleg, which is a pipe section used for intermittent services and maintenance in hydrate management. Hydrate deposition under water saturated gas environment is monitored by measuring the dielectric constant of the hydrate layer, which is considered as a three-component mixture of hydrates, gas, and water. The permittivity responses upon hydrate formation and dissociation are observed, and their physical interpretations are also provided. By applying appropriate models, thickness, wetness, and porosity of hydrate deposits are quantitatively estimated. Knowledge obtained from this work will be helpful in further developing a real-time monitoring of hydrate deposition by dielectric measurements.

Filtration failure occurs when filter media are blocked by accumulated solid particles. Suitable operating conditions were investigated for cake cleaning by partial oxidation of filter-cake particles (FCPs) during biomass gasification. The mechanism of the FCP partial oxidation was investigated in a ceramic filter and by using thermogravimetric analysis through a temperature-programmed route in a 2 vol % O2–N2 environment. Partial oxidation of the FCPs in the simulated product gas environment was examined at 300–600 °C in a ceramic filter that was set and heated in a laboratory-scale fixed reactor. Four reaction stages, namely, drying, preoxidation, complex oxidation, and nonoxidation, occurred in the FCP partial oxidation when the temperature increased from 30 to 800 °C in a 2 vol % O2–N2 environment. Partial oxidation was more effective for FCP mass loss from 275 to 725 °C. Experimental results obtained in a ceramic filter indicated that the best operating temperature and FCP loading occurred at 400 °C and 1.59 g/cm2, respectively. The FCPs were characterized before and after partial oxidation by Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunaeur–Emmett–Teller analysis. Fourier-transform infrared spectroscopy analysis revealed that partial oxidation of the FCPs can result in a significant decrease in C–Hn (alkyl and aromatic) groups and an increase in C═O (carboxylic acids) groups. The scanning electron microscopy and Brunaeur–Emmett–Teller analyses suggest that, during partial oxidation, the FCPs underwent pore or pit formation, expansion, amalgamation, and destruction.

This work investigates computationally the modeling of sugarcane bagasse pyrolysis in a bubbling fluidized bed reactor. An Euler–Euler multiphase approach, as invoked by the open code MFIX (Multiphase Flow with Interphase eXchanges), is adopted, and the simulations are carried out in a two-dimensional Cartesian domain. While several pyrolysis kinetic models have been developed for wood, coal, and generic biomass, generally using thermogravimetric analysis, no such model has been specifically tested or adapted to simulate sugarcane bagasse pyrolysis in fluidized bed reactors through computational fluid dynamics. In the present study, seven pyrolysis kinetic models available in the literature are implemented as MFIX user-supplied routines and evaluated within given operational temperature ranges. Initially, well-established wood pyrolysis results are used to validate the implementations. Following validation, six kinetic schemes are employed to simulate sugarcane bagasse pyrolysis. Results for the products distribution, formation reaction rate profiles, and tar composition at different operating temperatures of the fluidized bed reactor are obtained for all models and compared to published experimental results. Based on the assessed predictive performances of the models, indications are drawn for the most appropriate models to simulate the reactor under different operating conditions.

In 2017, the Chinese government issued a strategic policy of nationwide use of bioethanol as a gasoline-blending component by 2020 for the consideration of reducing smog and greenhouse gas (GHG) emissions. It is highly relevant to estimate the benefits of well-to-wheel (WTW) GHG emission savings using future engine technologies. However, literature about the WTW GHG emissions for ethanol blends did not cover the engine efficiency gains in engines with future technologies. In a previous publication from the authors’ group, an empirical model was developed to predict the anti-knock property and engine thermal efficiency gains of ethanol blends in spark-ignition (SI) engines. This paper is a follow-up study, looking at not only the potential engine thermal efficiency gains but also WTW GHG emissions in future engine technologies. More specifically, a case study of adding bioethanol to two representative E10 fuels (main- and premium-octane-grade fuels) from China was conducted. It is assumed that future engine technologies enable an adjustable compression ratio (CR) according to the octane rating of ethanol blends, allowing for the maximum extraction of the benefit of a high anti-knock property of ethanol blends. In addition, the sensitivity of GHG intensity of bioethanol on WTW GHG emissions is analyzed and discussed. It is found that the chemical and cooling effects of ethanol blends are the dominant factors contributing to engine thermal efficiency gains. For the ethanol blends with the RON84.5 base gasoline, the negative impact of a lower heating value (LHV) of ethanol blends on the vehicle mileage range can be completely offset by the engine thermal efficiency gain, enabled by a higher octane rating of ethanol blends. Assuming that, in China, in the future, bioethanol has a GHG intensity of 33 g of CO2 equiv/MJ (grams of CO2 equivalent per megajoules of LHV) in comparison to E10, E30 led to a 21.2% reduction of WTW GHG emissions in a turbo-charged (TC) direct-injection spark-ignition (DISI) vehicle. Among this 21.2% reduction, one-third is due to the thermal efficiency gain and two-thirds is due to the use of renewable bioethanol. Reducing the GHG intensity of bioethanol is a key to lowing WTW GHG emissions. For the TC DISI engine technology, when E10 is used as the baseline fuel, every 1 g of CO2 equiv/MJ reduction in GHG intensity of bioethanol leads to a 0.239 g of CO2 equiv/MJ of WTW GHG emission saving for vehicles fueled with E20.

We investigate and quantitate the changes in hydrocarbon product composition while evaluating the performance and operability of the National Renewable Energy Laboratory’s Davison Circulating Riser (DCR) reactor system when biomass model compounds are cofed with traditional fluid catalyst cracking (FCC) feeds and catalyst: vacuum gas oil (VGO) and equilibrium zeolite catalyst (E-Cat). Three compounds (acetic acid, guaiacol, and sorbitan monooleate) were selected to represent the major classes of oxygenates present in biomass pyrolysis vapors. These vapors can contain 30–50% oxygen as oxygenates, which create conversion complications (increased reactivity and coking) when integrating biomass vapors and liquids into fuel and chemical processes long dominated by petroleum feedstocks. We used these model compounds to determine the appropriate conditions for coprocessing with petroleum and ultimately pure pyrolysis vapors only as compared with standard baseline conditions obtained with VGO and E-Cat only in the DCR. Model compound addition decreased the DCR catalyst circulation rate, which controls reactor temperature and measures reaction heat demand, while increasing catalyst coking rates. Liquid product analyses included 2-dimensional gas chromatography time-of-flight mass spectroscopy (2D GC×GC TOFS), simulated distillation (SIM DIST), 13C NMR, and carbonyl content. Aggregated results indicated that the model compounds were converted during reaction, and despite functional group differences, product distributions for each model compound were very similar. In addition, we determined that adding model compounds to the VGO feed did not significantly affect the DCR’s operability or performance. Future work will assess catalytic upgrading of biomass pyrolysis vapor to fungible hydrocarbon products using upgrading catalysts currently being developed at NREL and at Johnson Matthey.

In this study, a novel integrated system for production of advanced synthetic diesel is proposed and analyzed from thermodynamic, economic, and environmental perspectives. This system consists of a solid oxide electrolyzer, entrained gasification, a Fischer–Tropsch reactor (FT), and upgrading processes. Eleven different combinations of precursor syngas production through steam and CO2 co-electrolysis and biomass gasification are investigated. Results show that an increasing share of produced syngas in the electrolyzer unit results in higher system efficiencies, emission savings, and levelized cost of FT diesel. Moreover, different options of heat and mass flow recovery are considered. It is concluded that recovery of produced medium pressure steam in the system is highly beneficial and recommended. Besides, it is shown that while oxygen recovery is the best choice of mass recovery, hydrogen recovery for internal use has adverse effect on the system performance.

The supercritical water gasification of xylose, a model substrate for hemicellulose, was carried out at 400 and 450 °C and at a constant pressure of 25 MPa in the presence of acetic acid using a continuous flow reactor. More specifically, we aimed to compare the reaction rate constants of xylose decomposition in both the presence and absence of acetic acid. Upon the application of a residence time of 0.5–5 s, a xylose concentration of 1.5 wt %, and an acetic acid concentration of 1.5 wt %, we successfully elucidated the effect of acetic acid on each reaction within the reaction network for the first time. In the presence of acetic acid, the retro-aldol reactions and carbon gasification production (i.e., the radical reactions) were suppressed, while the acetic-acid-catalyzed dehydration of xylulose to furfural (i.e., an ionic reaction) was enhanced by 2 orders of magnitude. As such, reaction control through the addition of chemical species to either stabilize ions or react with radicals appears possible.

In the present study, we investigated the effects of concentrating a cell suspension of a hydrocarbon-rich microalga, Botryococcus braunii, by membrane filtration on hydrocarbon recovery efficiency. B. braunii suspensions before and after filtration were mechanically pretreated with a high-pressure homogenizer or a JET PASTER high-speed mixer. Concentrating the suspension increased the apparent viscosity of the sample and altered the particle size and shape distributions. The increase of viscosity was derived from the existence probability that was caused by shear forces in the pump that introduced the suspension into the membrane filter and/or between the membrane wall and algae. Homogenizer treatment decreased the sample viscosity from 20 to 5 mPa·s due to the collapse of the bridge between the algae and polysaccharides. The treatment also decreased the hydrocarbon recovery efficiency from 60% to 15% because of the release of intracellular substances that prevented hydrocarbon extraction. In contrast, JET PASTER treatment increased the hydrocarbon recovery efficiency by removing polysaccharides surrounding the colonies and disrupting colonies, without disrupting the cells. Adding oleic acid as a model intracellular substance to the concentrated sample before extraction decreased the amount of extracted hydrocarbon. These results demonstrate that concentrating the sample by filtration combined with JET PASTER treatment can improve the hydrocarbon recovery efficiency of B. braunii. In addition, an energy analysis was performed in the present study. The energy consumption of the JET PASTER treatment combined with filtration was 7.6 times as high as the energy produced.

Catalytic fast pyrolysis of eucalyptus wood was performed on a continuous laboratory-scale fluidized bed fast pyrolysis system. Catalytic activity was monitored from use of fresh catalyst up to a cumulative biomass/catalyst ratio (B/C) of 4:1 over extruded pellets of three different ZSM-5 catalysts by tracking CO, CO2, H2, and C2H4 production and bio-oil quality. The catalysts employed were extruded HZSM-5 with two different silica/alumina ratios (30 and 80) as well as one modified with Ga (SiO2/Al2O3 = 30) by ion exchange, which was reduced under H2 prior to pyrolysis. The deactivation of the catalysts over the course of the experiment was reflected in the decline in deoxygenation activity, following the order HZSM-5 (30) > HZSM-5 (80) > GaZSM-5 (30). HZSM-5 (30) lost most of its activity before a cumulative B/C of 2:1 was reached, while HZSM-5 (80) still showed significant deoxygenated activity at this exposure level. GaZSM-5 (30) still showed deoxygenation activity at B/C of >4:1. The improvement exhibited by HZSM-5 with an increasing SiO2/Al2O3 ratio was attributed to reduced acid site density that decreased the propensity for coke formation as a result of reactions occurring between substrates at adjacent active acid sites. For reduced GaZSM-5, initial dehydrogenation activity aided in the production of aromatics by the olefin oligomerization and aromatization route up to B/C of ∼1.5:1, after which Ga became completely oxidized; however, the oxidized GaZSM-5 catalyst continued to exhibit improved decarbonylation and decarboxylation activities.

The world depends on petroleum for everything from the plastics that contain our food to the natural gas that heats our homes to the gasoline that feed our cars’ engines. With rising prices of petroleum reflecting demand for this finite resource, attention has been turned to alternative sources of energy. Biodiesel, which exhibits many of the same properties as conventional diesel but is derived from biological sources, is an attractive alternative. Fats and oils are converted to biodiesel, fatty acid methyl esters (FAMEs), by transesterification. FAMEs are subsequently thermally cracked to form more lightweight transportation fuels such as natural gas, kerosene, and possibly gasoline. We aim to further understand the thermal cracking procedure, at an atomic level, in hopes that this may aid in future engineering of viable fuels. We will present our study on the effective computational modeling of bond dissociations in the FAMEs methyl linoleate and methyl oleate, which are the most common biodiesel products of soybeans and rapeseeds (also known as canola seeds). We have employed quantum chemical methods, including the density functionals B3LYP, M06-2X, and B97D; the wave function-based MP2; and the composite CBS-QB3 method. Bond dissociation in a 44-reaction database set for which experimental energies are known is used to evaluate methods. We find that the M06-2X/6-31+G(d,p) model chemistry provides results comparable to the composite CBS-QB3 method at a much reduced cost. Last, data are compiled for possible bond dissociations in FAMEs methyl oleate and methyl linoleate.

A mixture of three model compounds of lignocellulosic biomass, namely glucose, xylose, and guaiacol, was treated in supercritical water to investigate the interactions taking place between the model compounds. All experiments were carried out at 450 °C and 25 MPa, with varying residence times of 5–40 s. The inclusion of guaiacol resulted in high yields of both 5-hydroxymethylfurfural and furfural. In addition, reaction rate constants were determined for the reaction network, and a comparison with literature values indicated that guaiacol addition suppressed radical reactions, thus increasing the yields of products derived from ionic reactions.

In this paper, selected physicochemical properties such as kinematic viscosity (ν), density (ρ), lower heating value (LHV), cold filter plugging point (CFPP), miscibility, flash point (FP), coefficient of friction (μ), lubricity (WS1.4), surface tension (σ), and copper strip corrosion (CSC) of diethyl ether/rapeseed oil blends were experimentally determined. Diethyl ether (DEE) was blended with rapeseed oil (RO) in volumetric ratios of 10, 20, 30, and 40%. The values of the LHV, kinematic viscosity, surface tension, and density of the blends were lower than the values obtained for the tested rapeseed oil. Especially, it was found that DEE has significant influence on the rapeseed oil viscosity value. The addition of merely 10% DEE to rapeseed oil decreased its viscosity by 50%. It was shown that the lubricity of all tested blends is reduced, but not as significantly as viscosity. Also, we confirmed that tested blends do not promote the corrosion processes. What is more, it was found that the temperature of the CFPP decreased when DEE was added to RO and the miscibility of all tested fuel blends is excellent in a wide range of temperature changes. For this reason the results of our research suggest that DEE/RO blends seem to be usable for engines operated in the winter season. However, it should be confirmed in further engine research carried out in low temperature conditions. In this study the diesel smoke opacity (SO) was also measured in the condition of a free acceleration test according to requirements of the United Nations Economic Commission for Europe (ECE) Regulation No. 24. Results of these tests demonstrate that the diesel smoke opacity is reduced even by 55% for DEE40 blend compared with RO.

Hydrogen production via steam reforming of bio-oil is a potential method to reduce the dependence on the conventional fossil fuels. To investigate the reactivity of bio-oil and its difference with gasification tar and conventional fossil fuels, the steam reforming of various compounds (benzene, toluene, m-xylene, m-cresol, n-hexane, cyclohexane, 1-propanol, and acetic acid) was conducted in a fixed-bed flow reactor at various temperatures over a high-performance RuNi/BaOAl2O3 catalyst. As a whole, the reactivities of these compounds in steam reforming decrease in the following trend: n-hexane > cyclohexane > benzene > toluene > m-xylene >1-propanol > m-cresol > acetic acid. For the C6 hydrocarbons, benzene showed a lower reactivity than n-hexane and cyclohexane, due to the stable benzene ring. The reactivities of aromatic hydrocarbons decrease with the addition of methyl groups to the benzene ring due to electronic and steric effects. m-Cresol showed a lower reactivity than benzene, toluene, and m-xylene, suggesting that the incorporation of a hydroxyl group to the benzene ring hindered the steam reforming reaction. Besides the steam reforming reactions, the side reactions such as hydrogenolysis, demethylation, decomposition, and methanation of CO and CO2 also occurred. A benzene ring can be formed by the dehydroaromatization of n-hexane or cyclohexane, while the reverse reaction cannot occur due to the thermodynamic limit. The largely containing acetic acid in bio-oil needs a higher reforming temperature than the other compounds and is easy to be thermally decomposed into coke at low temperatures, which increases the difficulty of bio-oil steam reforming.

Jatropha oil is a prospective non-edible resource for green diesel manufacturing. In this work, diesel-range hydrocarbons (mostly C15–C18 n-paraffins) were produced from the hydrotreatment of jatropha oil over traditional CoMo/Al2O3 and NiMo/Al2O3 catalysts in a fixed-bed reactor. The reaction variables were varied as follows: temperature, 563–653 K; pressure, 1.5–3 MPa; H2/oil ratio, 200–800 (v/v); and weight hourly space velocity, 1–4 h–1. Oil conversion was maximized (Co–Mo, 97%; Ni–Mo, 88.6%) at T = 653 K and P = 3 MPa. The hydrocarbon yield at these conditions was 62.6% (Co–Mo) and 63% (Ni–Mo). These findings were juxtaposed with our latest results on the hydrotreatment of the non-edible karanja oil. From the first-order plots of conversion of triglycerides in jatropha oil, rate constants and energy of activation were found. To improve the cold flow properties of the hydrotreated jatropha oil without isomerization, it was blended with usual diesel in varying proportions. As the concentration of usual diesel in such mixtures increased, the viscosity, cetane number, and pour point decreased. Employing tailored blends of hydrotreated vegetable oil and petroleum diesel thus appeared preferential. Finally, the performance of Co–Mo and Ni–Mo catalysts prepared by wet impregnation was tested, but the activity of the commercial catalysts was superior.

Lignocellulosic biomass is a promising feedstock for renewable fuels and chemical intermediates; in particular, lignin attracts attention for its favorable chemical composition. One obstacle to lignin utilization and valorization is the unknown chemical mechanism that gives rise to the complex product distributions observed upon deconstruction. Among possible deconstruction chemistries, fast pyrolysis is promising due to its short residence time, thus enabling high-volume production. However, the chemistry is inherently complex, thereby hampering the creation of detailed kinetic models describing pathways to specific low molecular products. To this end, we created a detailed kinetic model of lignin decomposition via pyrolysis comprised of 4313 reactions and 1615 species based on pathways suggested by pyrolysis of model compounds in the literature. Using a rule-based reaction network generation approach, a pathways-level reaction network is proposed to predict the evolution of macromolecular species and the formation of various low molecular weight products identified from experimental studies. This reaction network is coupled to a structural model of wheat straw lignin via a kinetic Monte Carlo framework to simulate lignin fast pyrolysis. The mass yields of and speciation within four commonly observed fractions, viz., light gases, an aqueous phase containing water and small oxygenates, char, and a highly complex aromatic fraction, are compared to an experimental report of a putatively similar biomass source. Additional capabilities of the model include the time-resolved prediction of volatilization profiles and the evolution of the molecular weight distribution, which may assist in efforts to valorize lignin to a higher degree than that achieved by current approaches.

Grease-trap waste (GTW) and sewage-scum grease (SSG) are under-utilized, high-lipid waste streams that have the potential to be converted into biodiesel. This paper presents a longitudinal study of GTW and SSG samples that were obtained over a 1 year period; GTW was sampled from a storage tank at a grease-collection company, and SSG was sampled from scum-concentration buildings at three wastewater resource recovery facilities. Samples were fractionated to quantify their lipids, secondary wastewater, and solids content. Results show that the average lipid content of SSG was seasonally dependent; lipid content was 15–40% in cooler months and 3–21% in warmer months. Alternatively, GTW showed an average overall lipid content of 4% in raw GTW; however, the floating layer from settled GTW had an average lipid content of 34%. These greases could serve as feedstocks for urban low-carbon biodiesel production while reducing the volume of biosolid waste disposal.

The structure–reactivity relationship in fast pyrolysis of lignin for monomeric phenolic compounds was studied on seven lignins from hardwood, softwood, and grass. The distribution of elements, functional groups, phenylpropane units, and interunit linkage bonds varied greatly across the lignins. Lignins from hardwood and grass prepared with mild conditions presented more C–O linkages. Pyrolysis–gas chromatography/mass spectrometry showed that the cleavage of unstable C–O linkages dominated the pyrolysis reaction at low temperatures, and the total yields of monomers peaked at 700 °C for most lignins. 4-Vinylphenol produced from acid extracted corn stalk lignin reached up to 4.77 wt % at 700 °C. Pyrolysis of grass lignins and woody lignins, which had more unstable C–O linkages, exhibited higher total yields of monomers. The pyrolysis behavior of lignin at low temperatures is closely related to its structural characteristics. Pyrolyzed at 500 °C, the total yields of monomeric aromatics were highly linearly correlated with the frequencies of C–O linkages (R2 = 0.86). This work demonstrates the significance of selecting the right lignin for producing monomeric aromatic compounds.

The reaction of gaseous KOH with kaolin and mullite powder under suspension-fired conditions was studied by entrained flow reactor (EFR) experiments. A water-based slurry containing kaolin/mullite and KOH was fed into the reactor and the reacted solid samples were analyzed to quantify the K-capture level. The effect of reaction temperature, K-concentration in the flue gas, and, thereby, molar ratio of K/(Al+Si) in reactants, gas residence time, and solid particle size on K-capture reaction was systematically investigated. Corresponding equilibrium calculations were conducted with FactSage 7.0. The experimental results showed that kaolin reached almost full conversion to K-aluminosilicates under suspension-fired conditions at 1100–1450 °C for a residence time of 1.2 s and a particle size of D50 = 5.47 μm. The amount of potassium captured by kaolin generally followed the equilibrium at temperatures above 1100 °C, but lower conversion was observed at 800 and 900 °C. Crystalline kaliophilite (KAlSiO4) was formed at higher temperatures (1300 and 1450 °C), whereas, amorphous K-aluminosilicate was formed at lower temperatures. Coarse kaolin (D50 = 13.48 μm) captured KOH less effectively than normal (D50 = 5.47 μm) and fine (D50 = 3.51 μm) kaolin powder at 1100 and 1300 °C. The difference was less significant at 900 °C. Mullite generated from kaolin captured KOH less effectively than kaolin at temperatures below 1100 °C. However, at 1300 and 1450 °C, the amount of potassium captured by mullite became comparable to that of kaolin.

Additives play a key role in the quality of fuel pellets. It can improve the physical, chemical, and thermal properties of the pellets. In this study, the effects of various natural additives on the quality of the sawdust fuel pellets have been investigated, and then the emissions resulting from gasification of the best pellet formulation were determined at various gasification conditions. The quality of pellets was evaluated based on density, mechanical strength (durability and hardness), porosity, and water resistance. For the pelletization process, spruce sawdust was used as a feedstock and lignin (L), lignosulfonate (LS), proline (P), corn starch (CS), and torrefied oat hull (TOH) were used as bioadditives. A lab-scale single-pelleting unit was used to compress sawdust pellets at 100 °C and 4000 N for 60 s. Results showed that lignin and proline produced the best pellets using sawdust feedstock with a preadjusted moisture content to 16%. Central composite design (CCD) was used to determine the impacts of proline and lignin contents on the quality of the pellets. Increasing proline and decreasing lignin had a positive impact on the density and mechanical strength of the pellets. Adding TOH to the pellet formulation increased heating value and slightly water resistance, but it decreased density and mechanical strength. Computed tomography (CT) analysis of the pellets showed that increasing the proline content in the pellet formulation decreased the porosity of the pellet, whereas increasing lignin or torrefied binder increased the porosity of the pellets. In the second stage, the best pellet formulation, which contained 5% lignin and 10% proline, was used to investigate the effects of gasification conditions, such as equivalence ratio (ER) and temperature, on the distribution of gaseous, liquid, and solid products as well as the composition of the produced syngas. Using a noncatalytic fixed bed downdraft gasifier, steam gasification of sawdust pellets showed that increasing ER and temperature increased total gas and syngas yields and H2 concentration, and decreased CH4 and C2H4 concentrations as well as char and tar yields.

In Europe, the official-type test method (oTT) according to the standard European Norm (EN) 13240 evaluates the emissions and thermal efficiency of firewood roomheaters only under optimal conditions, that is, heated up and at nominal load. In this study a novel test method, called “beReal”, is presented which was developed to reflect real-life operation within the testing procedure. The beReal test concept consists of a heating cycle with eight consecutive batches and covers all typical phases of real-life operation. A specific procedure based on volume flow measurements evaluating the emission and the efficiency of the whole test cycle was defined. A comparative assessment of the beReal and EN test protocol was conducted with a serial-production stove and compared with oTT results. The repeatability of EN and beReal test results regarding emissions and thermal efficiency was evaluated. The EN test results of this study were more than 200% higher compared to oTT results of the used stove model. Hence, it seems that the tested product during oTT differs from the serial-production products. The thermal efficiency of beReal tests was significantly lower compared to EN test results. However, regarding emissions, no significant differences were observed by the comparative tests according to both test protocols with the serial-production stove. An implementation of the beReal test protocol as a quality label or standard combined with market surveillance should be considered as an instrument to push innovation and technological development further and to enable better differentiation of good and poor products for the end customer.

To explore the effect of the addition of ethanol (E) on the combustion behavior of biodiesel/n-heptane (BH) blends, autoignition characteristics of the BHE blends were studied in two experimental systems: a modified cooperative fuel research (CFR) engine and a constant-volume combustion chamber (CID 510) used for rating the derived cetane number of fuels. The observations of ignition behavior include the critical compression ratio and heat release profile, which are assessed using the CFR engine. The equivalence ratio is 0.25 and 0.45, respectively, while the physical and chemical ignition delays are measured by the CID 510 under a wide range of air temperatures and oxygen dilution levels. With the addition of the ethanol, the critical compression ratio increases, which indicates that the reactivity decreases. According to the heat profiles, because of the complex composition of the blend, the onset of the high temperature heat release (HTHR) and low temperature heat release (LTHR) did not vary linearly with ethanol concentration, and the onset of LTHR of BHE15 and BHE20 is very close at both equivalence ratios at the same compression ratio (5.2). This is consistent with almost the same cetane number of BHE15 and BHE20. With the increase of ethanol in the blend, the physical ignition delay at different temperatures was BHE20 > BHE15 > BHE10 > BHE5 > BH. In addition, the chemical ignition delay increased with the addition of ethanol except for BHE5, which showed negative temperature coefficient (NTC) behavior and displayed a shorter chemical ignition delay than that of the BH blend at 853.15 K. The physical ignition delay for BH, BHE5, and BHE10 increased slightly with oxygen dilution. Moreover, the chemical ignition delay increased sharply with increasing exhaust gas recirculation (EGR). Higher addition of ethanol results in higher chemical ignition delay. The heat release profiles for the blends at different temperatures and EGR levels showed a decrease in reactivity.

Hydrothermal liquefaction of microalgae produces water-insoluble biocrude that spontaneously separates from aqueous phase by gravity. A small proportion of water-soluble biocrude can be obtained via organic solvent extraction from the aqueous phase. This work explored catalytic hydrothermal upgrading of the water-soluble biocrude with five varieties of catalysts (i.e., Pt/C, Pd/C, Ru/C, Pt/C + Pd/C, and newly synthesized CoNiMoW/γ-Al2O3) for the first time. The results show that the upgraded oil by Pt/C had the highest yield and energy recovery but the second lowest quality with respect to elemental composition and heating value. Pd/C led to the highest heating value and the lowest yield and energy recovery of upgraded oil, as well as the largest yields of CH4 and C2H6 simultaneously. Both Pt/C and CoNiMoW/γ-Al2O3 performed well in converting high-boiling-point macromolecules into smaller molecular compounds in water-soluble biocrude upgrading. More than 70% of components in upgraded oils were in the distillation range of 150–350 °C, in accord with that of petroleum diesel. A trade-off between bio-oil yield and quality is required to be made for catalyst selection in water-soluble biocrude upgrading. From the perspective of relatively high yield and quality of upgraded oil, CoNiMoW/γ-Al2O3 was a good option in catalytic hydrothermal upgrading of water-soluble biocrude.

This study evaluated the mercury sorption by activated carbon (AC) under an O2/CO2 atmosphere in a fixed-bed reactor. Effects of the oxygen concentration on the mercury sorption efficiency under both air and oxy-fuel atmospheres were explored. The kinetic studies were also used to predict the mercury sorption process by the pseudo-first-order model and the intraparticle diffusion model in this work. The experimental results indicated that the mercury sorption capacity of AC increased with the increased oxygen concentration under both air and oxy-fuel atmospheres. Oxygen might increase the oxidation of mercury by the Mars–Maessen way. A high CO2 concentration promoted AC to generate more active sites under an oxy-fuel atmosphere. Besides, the results of the kinetic analysis illustrated that the pseudo-first-order model showed better agreement with the experimental data compared to the intraparticle diffusion model. These experimental and theoretical results in this work are helpful in mercury capture under an oxy-fuel atmosphere.