One-Pot Synthesis of Menthol Starting from Citral over Ni Supported on Attapulgite-H-Beta-38 Extrudates in a Continuous Flow: Effect of Metal LocationClick to copy article linkArticle link copied!
- Irina L. SimakovaIrina L. SimakovaBoreskov Institute of Catalysis, pr. Ak. Lavrentieva 5, Novosibirsk, Russia 630090More by Irina L. Simakova
- Päivi Mäki-ArvelaPäivi Mäki-ArvelaÅbo Akademi University, Johan Gadolin Process Chemistry Centre, Henriksgatan 2, 20500 Turku/Åbo, FinlandMore by Päivi Mäki-Arvela
- Mark Martínez-KlimovMark Martínez-KlimovÅbo Akademi University, Johan Gadolin Process Chemistry Centre, Henriksgatan 2, 20500 Turku/Åbo, FinlandMore by Mark Martínez-Klimov
- Joseph MullerJoseph MullerÅbo Akademi University, Johan Gadolin Process Chemistry Centre, Henriksgatan 2, 20500 Turku/Åbo, FinlandMore by Joseph Muller
- Zuzana VajglováZuzana VajglováÅbo Akademi University, Johan Gadolin Process Chemistry Centre, Henriksgatan 2, 20500 Turku/Åbo, FinlandMore by Zuzana Vajglová
- Markus PeurlaMarkus PeurlaInstitute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI-20520 Turku, FinlandMore by Markus Peurla
- Kari EränenKari EränenÅbo Akademi University, Johan Gadolin Process Chemistry Centre, Henriksgatan 2, 20500 Turku/Åbo, FinlandMore by Kari Eränen
- Dmitry Yu. Murzin*Dmitry Yu. Murzin*Email: [email protected]Åbo Akademi University, Johan Gadolin Process Chemistry Centre, Henriksgatan 2, 20500 Turku/Åbo, FinlandMore by Dmitry Yu. Murzin
Abstract
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0009.gif)
The one-pot synthesis of menthol from citral in a continuous mode was investigated over three different types of extrudates, namely Ni supported on H-Beta-38 and extruded with attapulgite, Ni supported on attapulgite and extruded with H-Beta-38, and the extrudates, which were shaped after deposition of Ni on both H-Beta-38 and attapulgite in the powder form. These composite catalysts were characterized by X-ray diffraction, transmission and scanning electron microscopy, temperature-programmed reduction of H2, mechanical strength, and pyridine adsorption desorption. These three types of extrudates exhibited different metal particle sizes and acidity. The most promising catalyst in the one-pot menthol synthesis was Ni supported first on H-Beta-38 and then extruded with attapulgite giving a 45% yield of menthols in a trickle bed reactor. This catalyst exhibited 10 nm nickel particles and a rather high amount of strong Brønsted acid sites.
This publication is licensed under
License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
Creative Commons (CC): This is a Creative Commons license.
Attribution (BY): Credit must be given to the creator.
*Disclaimer
This summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials.
License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
Creative Commons (CC): This is a Creative Commons license.
Attribution (BY): Credit must be given to the creator.
*Disclaimer
This summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials.
License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
Creative Commons (CC): This is a Creative Commons license.
Attribution (BY): Credit must be given to the creator.
*Disclaimer
This summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials.
1. Introduction
Figure 1
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0001.gif)
Figure 1. Reaction scheme for citral transformation to menthol. Legend: A – citral, B – citronellal, C – isopulegol isomers, D – menthol isomers, E – acyclic hydrogenation products, F – defunctionalization products, dimeric ethers, and heavy components.
2. Experimental Section
2.1. Synthesis of Catalysts
2.2. Characterization of Catalysts
2.3. Catalyst Testing
3. Results and Discussion
3.1. Catalyst Characterization
extrudates | |||||||
---|---|---|---|---|---|---|---|
entry | sample | Ni content [wt %] | SBET [m2/g] | SDR [m2/g] | V [cm3/g] | Vm/Vμ | Dpore [nm] |
1 | H-Beta-38 (20) | n.d. | n.a. | 590 | 0.31 | 0.35 | 0.67 |
2 | attapulgite (powder) | n.d. | 103 | 117 | 0.25 | 6 | n.d. |
attapulgite (extrudate) | n.d. | 97 | 116 | 0.37 | 12 | n.d. | |
3 | [Ni/(H-Beta-38+Att.)] | 5.1 | 404 | 528 | 0.39 | 0.73 | n.d. |
4 | [Ni/(H-Beta-38+Att.)] spenta | n.a. | 206 | 267 | 0.23 | 1.07 | n.d. |
5 | [(Ni/H-Beta-38)+Att.] | 5.1 | 304 | 407 | 0.31 | 0.80 | 0.66 |
6 | [(Ni/H-Beta-38)+Att.] spentb | 4.8 | 193 | 246 | 0.22 | 1.20 | 0.63 |
7 | [(Ni/Att.)+H-Beta-38] | 4.8 | 355 | 460 | 0.32 | 0.63 | 0.66 |
8 | [(Ni/Att.)+H-Beta-38] spentb | 4.2 | 177 | 219 | 0.18 | 1.1 | 0.63 |
This catalyst was used first in citronellal transformation; thereafter, it was reduced in situ and used in citral transformation.
These catalysts were only used in citral transformation.
A – specific surface area (BET: Brunauer–Emmett–Teller, DR: Dubinin-Radushkevich), V – pore volume (m: meso, μ: micro). n.d. not determined, n.a. not available.
BAS [μmol/g] | LAS [μmol/g] | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
no. | sample | w | m | s | ∑ | W | m | s | ∑ | TAS [μmol/g] | BAS/LAS |
1 | attapulgite | 1 | 5 | 0 | 6 | 27 | 8 | 0 | 34 | 40 | 0.2 |
2 | H-Beta-38 | 17 | 40 | 221 | 278 | 19 | 10 | 2 | 31 | 309 | 9 |
3 | 70 wt % H-Beta-38 + 30 wt % Att.a | 12 | 29 | 155 | 196 | 21 | 9 | 1 | 31 | 186 | 6 |
4 | 70 wt % H-Beta-38 + 30 wt % Att.b | 15 | 45 | 42 | 102 | 39 | 20 | 9 | 68 | 170 | 1.5 |
5 | [Ni/(H-Beta-38+Att.)] | 13 | 19 | 35 | 67 | 96 | 33 | 26 | 155 | 222 | 0.43 |
6 | [(Ni/H-Beta-38)+Att.] | 25 | 22 | 68 | 115 | 97 | 27 | 43 | 167 | 282 | 0.69 |
7 | [(Ni/Att.)+H-Beta-38] | 9 | 48 | 44 | 101 | 62 | 38 | 9 | 109 | 210 | 0.93 |
8 | [Ni/(H-Beta-38+Att.)] spent | 10 | 6 | 17 | 91 | 7 | 3 | 8 | 115 | 206 | 0.79 |
9 | [(Ni/Att.)+H-Beta-38] spent | 14 | 72 | 17 | 103 | 44 | 31 | 5 | 80 | 183 | 1.29 |
Theoretical value calculated as the weight-average.
Measured.
Figure 2
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0002.gif)
Figure 2. XRD patterns of a) the calcined (c.), freshly reduced (r), and spent (s) [Ni/(H-Beta-38+Att.)] extrudates compared to the initial H-Beta-38 zeolite and b) the spent [Ni/(H-Beta-38+Att.)], [(Ni/H-Beta-38)+Att.], and [(Ni/Att.)+H-Beta-38] extrudates compared to the initial H-Beta-38 zeolite. Notation: spent [Ni/(H-Beta-38+Att.)] was used first in citronellal transformation; thereafter, it was reduced in situ and used in citral transformation, while spent [(Ni/H-Beta-38)+Att.] and [(Ni/Att.)+H-Beta-38] extrudates were only used in citral transformation.
XRD | TEM | |||||
---|---|---|---|---|---|---|
entry | sample | DNiO (nm) | a (Å) | DNi0 (nm) | a (Å) | D (nm) |
1 | [Ni/(H-Beta-38+Att.)] calcined | 18.0 | 4.180 | n.d. | n.d. | n.d. |
2 | [Ni/(H-Beta-38+Att.)] reduced | 11.5 | 4.181 | 14.5 | 3.524 | n.d. |
3 | [Ni/(H-Beta-38+Att.)] spent | n.d. | n.d. | 13.0 | 3.523 | n.d. |
4 | [(Ni/H-Beta-38)+Att.] calcined | 19.0 | 4.180 | n.d. | n.d. | n.d. |
5 | [(Ni/H-Beta-38)+Att.] reduced | n.d. | n.d. | n.d. | n.d. | 9.8 |
6 | [(Ni/H-Beta-38)+Att.] spent | n.d. | n.d. | 18.0 | 3.524 | n.d. |
7 | [(Ni/Att.)+H-Beta-38] calcined | 12.0 | 4.178 | n.d. | n.d. | n.d. |
8 | [(Ni/Att.)+H-Beta-38] reduced | n.d. | n.d. | n.d. | n.d. | 6.2a |
9 | [(Ni/Att.)+H-Beta-38] spent | 10.0 | 4.182 | 9.0 | 3.524 | n.d. |
Difficult to separate nickel and impurity particles in attapulgite.
Spent [Ni/(H-Beta-38+Att.)] was used first in citronellal transformation; thereafter, it was reduced in situ and used in citral transformation, while the spent [(Ni/H-Beta-38)+Att.] and [(Ni/Att.)+H-Beta-38] extrudates were only used in citral transformation. n.d. not determined.
Figure 3
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0003.gif)
Figure 3. TEM images of a) attapulgite, b) H-Beta-38, c) [Ni/(H-Beta-38+Att.)], d) [(Ni/H-Beta-38)+Att.], and e) [(Ni/Att.)+H-Beta-38].
Figure 4
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0004.gif)
Figure 4. Metal particle size distribution determined by TEM for a) [(Ni/H-Beta-38)+Att.] and b) [(Ni/Att.)+H-Beta-38].
Figure 5
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0005.gif)
Figure 5. SEM images of the fresh, reduced a) [(Ni/H-Beta-38)+Att.] and b) [(Ni/Att.)+H-Beta-38] catalysts.
Figure 6
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0006.gif)
Figure 6. Hydrogen TPR of a) [(Ni/H-Beta-38)+Att.] and b) [(Ni/Att.)+H-Beta-38].
3.2. Catalytic Results on Menthol Synthesis
Figure 7
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0007.gif)
Figure 7. a) Conversion of citronellal (■) and liquid phase mass balance (●) and b) concentration of menthols (●), acyclic hydrogenation products (■), and defunctionalized products (o) and stereoselectivity to menthol (Δ) in citronellal transformation over [Ni/(H-Beta-38+Att.)] as a function of TOS. The liquid flow rate was 0.2 mL/min during 215 min TOS; thereafter, it was 0.3 mL/min.
Figure 8
![](/cms/10.1021/acs.iecr.2c02345/asset/images/medium/ie2c02345_0008.gif)
Figure 8. a) Conversion of citral, b) cis/trans ratio of citral, c) yield of menthols, d) stereoselectivity to menthol, e) yield of pulegols, f) acyclic hydrogenation products, g) 3,7-dimethyloctanol, h) defunctionalized products, (i) menthenes, and j) menthanes as a function of time-on-stream in citral transformation to menthols over different types of Ni extrudates. Notation: (■) [(Ni/H-Beta-38)+Att.], (●) [Ni/(H-Beta-38+Att.)], and (▲) [(Ni/Att.)+H-Beta-38].
4. Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.iecr.2c02345.
Catalyst characterization: pore size distribution, XRD of extrudates. Catalytic data: selectivity to desired menthol as function of conversion, concentration of menthol vs concentration of 3,7-dimethyloctanol and their ratio vs conversion (PDF)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
Acknowledgments
The authors are grateful to the Academy of Finland for funding through the following project: Synthesis of spatially controlled catalysts with superior performance. Electron microscopy samples were processed and analyzed in the Electron Microscopy Laboratory, Institute of Biomedicine, University of Turku, which receives financial support from Biocenter Finland. I.S. is grateful for the support from the Ministry of Science and Higher Education of the Russian Federation under the governmental order for the Boreskov Institute of Catalysis (project AAAA-A21-121011390055-8).
References
This article references 40 other publications.
- 1Patel, T.; Ishiuji, Y.; Yosipovitch, G. Menthol: a refreshing look at this ancient compound. J. Am. Academy Dermat. 2007, 57 (5), 873– 878, DOI: 10.1016/j.jaad.2007.04.008Google ScholarThere is no corresponding record for this reference.
- 2Trasarti, A. F.; Marchi, A. J.; Apesteguıa, C. R. Highly selective synthesis of menthols from citral in a one-step process. J. Catal. 2004, 224, 484– 488, DOI: 10.1016/j.jcat.2004.03.016Google Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjvVGisLo%253D&md5=5ebd1bf9f6d046b1cf9ed2d3f68726e1Highly selective synthesis of menthols from citral in a one-step processTrasarti, A. F.; Marchi, A. J.; Apesteguia, C. R.Journal of Catalysis (2004), 224 (2), 484-488CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Science)For the first time the selective synthesis of menthols from citral in a one-step process is reported. Bifunctional metal/acid catalysts active and selective for menthol synthesis were developed by studying the individual steps involved in the reaction pathway leading to menthols from citral. The metallic component was selected by testing silica-supported metals for citral hydrogenation to citronellal. Acid site requirements to efficiently isomerize citronellal to isopulegols were investigated on different solid acids. Potential bifunctional metal/acid catalysts were then prepd. and tested for citral conversion to menthols. The best catalyst was Ni/Al-MCM-41, which yielded about 90% menthols and gave 70-75% of racemic (±)-menthol in the menthol mixt.
- 3Vajglová, Z.; Kumar, N.; Peurla, M.; Eränen, K.; Mäki-Arvela, P.; Murzin, D. Yu. Cascade transformations of (±)-citronellal to menthol over extruded Ru-MCM-41 catalysts in a continuous reactor. Catal. Sci. Techn. 2020, 10, 8108– 8119, DOI: 10.1039/D0CY01251CGoogle ScholarThere is no corresponding record for this reference.
- 4Plößer, J.; Lucas, M.; Claus, P. Highly selective menthol synthesis by one-pot transformation of citronellal using Ru/H-BEA catalysts. J. Catal. 2014, 320, 189– 197, DOI: 10.1016/j.jcat.2014.10.007Google ScholarThere is no corresponding record for this reference.
- 5Azkaar, M.; Mäki-Arvela, P.; Vajglová, Z.; Fedorov, V.; Kumar, N.; Hupa, L.; Hemming, J.; Aho, A.; Murzin, D. Yu. Synthesis of menthol from citronellal over supported Ru- and Pt-catalysts in continuous flow. React. Chem. Eng. 2019, 4, 2156– 2169, DOI: 10.1039/C9RE00346KGoogle Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitVaksLrE&md5=3e7f32e9b424da8f3d7f5f9c79a2c8ffSynthesis of menthol from citronellal over supported Ru- and Pt-catalysts in continuous flowAzkaar, Muhammad; Maki-Arvela, Paivi; Vajglova, Zuzana; Fedorov, Vyacheslav; Kumar, Narendra; Hupa, Leena; Hemming, Jarl; Peurla, Markus; Aho, Atte; Murzin, Dmitry YuReaction Chemistry & Engineering (2019), 4 (12), 2156-2169CODEN: RCEEBW; ISSN:2058-9883. (Royal Society of Chemistry)One-pot menthol synthesis from citronellal in a trickle bed reactor was investigated using Ru/H-beta-300 zeolite extrudates without any binder and Pt- and Ru-extrudates contg. 70 wt% H-beta-25 zeolites and 30 wt% bentonite binder using different methods of metal loading on the extrudates. The catalytic results were correlated with the physico-chem. properties of bifunctional zeolite-based extrudates. The conversion of citronellal to menthol was nearly the same for Pt extrudates being independent of catalyst acidity or the metal particle size. Ru extrudates also exhibited similar conversion levels as a function of time-onstream, except for very mildly acidic Ru/beta-300 extrudates, which gave much lower conversion. Pt extrudates showed better stability with time on stream in comparison with Ru extrudates. The best catalyst giving the highest menthol yield and a low amt. of acyclic hydrogenation products was Ru-beta-bentonite extrudates where Ru was located randomly in the mixt. of 70% H-beta-25 and 30% bentonite binder. Hydrogenation was more prominent for Pt than for Ru catalysts, most probably due to their higher hydrogenation ability. Stereoselectivity to menthol varied in the trickle bed reactor in the range of 67 to 73%. In a batch reactor for Ru- and Pt-catalysts independent of support acidity, it was in the range of 70-71%. The reuse of Ru/H-beta-300 extrudates was successfully demonstrated.
- 6Balu, A. M.; Campelo, J. M.; Luque, R.; Romero, A. A. One-step microwave-assisted asymmetric cyclisation/hydrogenation of citronellal to menthols using supported nanoparticles on mesoporous materials. Org. Biomol. Chem. 2010, 8, 2845– 2849, DOI: 10.1039/c003600eGoogle Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXmvVWktbw%253D&md5=bba1f1128bba182ba3d67e193a9d4f34One-step microwave-assisted asymmetric cyclization/hydrogenation of citronellal to menthols using supported nanoparticles on mesoporous materialsBalu, Alina Mariana; Campelo, Juan Manuel; Luque, Rafael; Romero, Antonio AngelOrganic & Biomolecular Chemistry (2010), 8 (12), 2845-2849CODEN: OBCRAK; ISSN:1477-0520. (Royal Society of Chemistry)The selective conversion of citronellal to menthols, with good diastereoselectivities to (-)-menthol for the case of (+)-citronellal as starting material, can effectively be carried out in a one-step reaction under microwave irradn. catalyzed by supported nanoparticles on mesoporous materials. 2% Pt/Ga-MCM-41 was found to be the optimum catalyst for the reaction, with a quant. conversion of starting material and selectivities above 85% to menthols obtained in short reaction times (typically 15 min). These results constitute the first report of a simple microwave-assisted one-step cyclization/hydrogenation process for the prodn. of menthols.
- 7Mertens, P.; Verpoort, F.; Parvulescu, A. N.; De Vos, D. Pt/H-beta zeolites as productive bifunctional catalysts for the one-step citronellal-to-menthol conversion. J. Catal. 2006, 243, 7– 13, DOI: 10.1016/j.jcat.2006.06.017Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XptlGhtbc%253D&md5=c1163822db7ae1cfc8caa59fd5b3af79Pt/H-beta zeolites as productive bifunctional catalysts for the one-step citronellal-to-menthol conversionMertens, Pascal; Verpoort, Francis; Parvulescu, Andrei-Nicolae; De Vos, DirkJournal of Catalysis (2006), 243 (1), 7-13CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Ltd.)Pt-loaded H-beta zeolite was identified as a highly active catalyst for the bifunctional transformation of citronellal to menthol, with isopulegol as the intermediate. With a 2 wt% Pt-loaded catalyst, citronellal is fully converted within 12 h, with only 2.5 wt% catalyst with respect to citronellal, and with a citronellal to Pt molar ratio of 2500. 1,4-Dioxane is the best reaction solvent, because it minimizes the unwanted direct hydrogenation of citronellal and promotes its stereoselective cyclization to isopulegol, leading to high menthol yields. The stereoselectivity can be improved moderately by using a Zr-impregnated support and more substantially by performing high-temp. (750 °C) treatment of the calcined and reduced catalyst. This treatment presumably creates extra Lewis acidity on the catalyst and results in 88% stereoselectivity for the desired menthol. Overall, an 85% yield of (-)-menthol was obtained.
- 8da Silva Rocha, K. A.; Robles-Dutenhefner, P. A.; Sousa, E. M. B.; Kozhevnikova, E. F.; Gusevskaya, E. Pd-heteropoly acid as a bifunctional heterogeneous catalyst for one-pot conversion of citronellal to menthol. Appl. Catal. A: Gen. 2007, 317, 171– 174, DOI: 10.1016/j.apcata.2006.10.019Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXivVKj&md5=baf703fb43d802ef49865f82b8c6d4fdPd-heteropoly acid as a bifunctional heterogeneous catalyst for one-pot conversion of citronellal to mentholDa Silva Rocha, Kelly A.; Robles-Dutenhefner, Patricia A.; Sousa, Edesia M. B.; Kozhevnikova, Elena F.; Kozhevnikov, Ivan V.; Gusevskaya, Elena V.Applied Catalysis, A: General (2007), 317 (2), 171-174CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Pd-H3PW12O40/SiO2 catalyzes the one-pot transformation of (+)-citronellal to menthol via acid-catalyzed cyclization followed by Pd-catalyzed hydrogenation, with 92% yield of menthol at 100% citronellal conversion and 85% stereoselectivity for the desired (-)-menthol.
- 9Milone, C.; Gangemi, C.; Neri, G.; Pistone, A.; Galvagno, S. Selective one step synthesis of (−)-menthol from (+)-citronellal on Ru supported on modified SiO2. Appl. Catal. A: Gen. 2000, 199, 239– 244, DOI: 10.1016/S0926-860X(99)00560-8Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXivVCitrw%253D&md5=96ce86ba2b032291b45d961097eb8dbbSelective one step synthesis of (-)-menthol from (+)-citronellal on Ru supported on modified SiO2Milone, C.; Gangemi, C.; Neri, G.; Pistone, A.; Galvagno, S.Applied Catalysis, A: General (2000), 199 (2), 239-244CODEN: ACAGE4; ISSN:0926-860X. (Elsevier Science B.V.)The isomerization of (+)-citronellal (I) has been performed under mild conditions on ZnX2 (X=Cl, Br, NO3) supported on high surface area silica. The influence of the Zn loading, counter anion and temp. of pretreatment of the catalyst on the activity and selectivity to (-)-isopulegol (II) was investigated. The catalytic activity increases with the Zn loading. The selectivity to (-)-isopulegol (II) also increases reaching the max. value (86%) on ZnBr2/SiO2 for a Zn content ≥4.0 mmol/g SiO2 ZnBr2/SiO2 is more active than ZnCl2/SiO2, while the selectivity to (-)isopulegol (II) is similar. Zn(NO3)2/SiO2 is far less active and selective. An increase of the temp. of pretreatment increases the selectivity to (-)-isopulegol (II) . A bifunctional catalyst was formulated, namely Ru-ZnBr2/SiO2, on which the one step hydrogenation of (+)-citronellal (I) to (-)-menthol (III) occurs with a yield >85%.
- 10Adilina, I. B.; Pertiwi, R.; Sulaswatty, A. Conversion of (±) -citronellal and its derivatives to (−) -menthol using bifunctional. Biopropal Industri 2015, 6, 1– 6, DOI: 10.36974/jbi.v6i1.828Google ScholarThere is no corresponding record for this reference.
- 11Nie, Y.; Chuah, G. K.; Jaenicke, S. Domino-cyclisation and hydrogenation of citronellal to menthol over bifunctional Ni/Zr-Beta and Zr-beta/Ni-MCM-41 catalysts. Chem. Commun. 2006, 790– 792, DOI: 10.1039/b513430gGoogle Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xht1Wkt7g%253D&md5=b62eb896e693802ff9b970fb8fb1da20Domino-cyclisation and hydrogenation of citronellal to menthol over bifunctional Ni/Zr-Beta and Zr-beta/Ni-MCM-41 catalystsNie, Yuntong; Chuah, Gaik-Khuan; Jaenicke, StephanChemical Communications (Cambridge, United Kingdom) (2006), (7), 790-792CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The one-pot conversion of (±)-citronellal to menthol can be selectively catalyzed by either a bifunctional Ni/Zr-zeolite beta catalyst or a dual catalyst system of Zr-beta and Ni/MCM-41, giving a high diastereoselectivity to (±)-menthol of 90-94%.
- 12Cortés, C. B.; Galván, V. T.; Pedro, S. S.; García, T. V. One pot synthesis of menthol from (±)-citronellal on nickel sulfated zirconia catalysts. Catal. Today 2011, 172, 21– 26, DOI: 10.1016/j.cattod.2011.05.005Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtFSjtbzP&md5=247354d3d4b5304641a0e221a4057396One pot synthesis of menthol from (±)-citronellal on nickel sulfated zirconia catalystsCortes, Cesar Barrales; Galvan, Victoria Tamayo; Pedro, Smid Santiago; Garcia, Tomas ViverosCatalysis Today (2011), 172 (1), 21-26CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)The one-pot synthesis of menthol from (±)-citronellal was carried out using two catalysts: nickel supported on sol-gel sulfated zirconia (Ni/ZrS) and nickel added during the synthesis of sulfated zirconia (NiZrS). The supported catalyst was prepd. by impregnation of nickel on the sulfated zirconia support, whereas NiZrS was prepd. by the co-gellation of nickel and the sulfated zirconia by the sol-gel method. Two sets of catalytic tests were carried out. In both tests the catalysts were previously treated in He stream. First, the liq. phase cyclization of (±)-citronellal was carried out with both ZrS and NiZrS catalysts. The results showed that both ZrS and NiZrS catalysts are highly active and selective towards isopulegols (100% of selectivity) and highly stereoselective towards (±)-isopulegol (∼70% of selectivity). A second reaction test was the synthesis of menthol. The catalysts were evaluated in a batch reactor at 1.4 MPa of H2 and 100 °C. The results showed that the catalysts allow to obtain a high catalytic activity and selectivity towards stereoisomers of menthol (100% selectivity of menthols) and a high selectivity towards (-)-menthol.
- 13Iftitah, E. D.; Muchalal, M.; Trisunaryanti, W.; Armunanto, R.; Psaro, R.; Ravasio, N.; Santoro, F.; Sordelli, L. One pot transformation of citronellal to menthol over Ni/γ-Al2O3. J. Appl. Sci. Res. 2011, 7, 680– 689Google ScholarThere is no corresponding record for this reference.
- 14Trasarti, A. F.; Marchi, A. J.; Apesteguía, C. R. Design of catalyst systems for the one-pot synthesis of menthols from citral. J. Catal. 2007, 247 (2), 155– 165, DOI: 10.1016/j.jcat.2007.01.016Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXjvVagu70%253D&md5=ce7aca1078b839d734478b4ceb132678Design of catalyst systems for the one-pot synthesis of menthols from citralTrasarti, A. F.; Marchi, A. J.; Apesteguia, C. R.Journal of Catalysis (2007), 247 (2), 155-165CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Ltd.)Stable, active, and highly selective bifunctional Ni/Al-MCM-41 catalysts were developed for the one-pot synthesis of menthols from citral. The liq.-phase hydrogenation of citral to citronellal was studied on silica-supported noble (Pt, Pd, Ir) and nonnoble (Ni, Co, Cu) metals. It was found that citronellal is selectively formed at the beginning of the reaction only on Pd and Ni catalysts. The consecutive ene-cyclization of citronellal to isopulegols was investigated on solid acids contg. exclusively Lewis (ZnO/SiO2) or strong Broensted (CsHPA) acid sites, and also on catalysts contg. both Lewis and Broensted acid sites of either strong (zeolites, SiO2-Al2O3) or moderate (Al-MCM-41) strength. The isopulegol formation rate was higher on samples exhibiting dual Lewis/Broensted acidity, such as SiO2-Al2O3, Al-MCM-41, and zeolite HBEA. Based on these previous results, bifunctional catalysts contg. Pd or Ni supported on SiO2-Al2O3, Al-MCM-41, or zeolite HBEA were prepd. and tested for citral conversion to menthols. The catalyst stability and the effect of hydrogen pressure and metal loading on menthol productivity were also investigated. The best catalyst was Ni(8%)/Al-MCM-41, which yielded more than 90% menthols at 2026.0 kPa and showed no significant deactivation after two consecutive catalytic tests.
- 15Nie, Y.; Jaenicke, S.; Chuah, G. K. Zr-zeolite beta: A new heterogeneous catalyst system for the highly selective cascade transformation of citral to (±)-menthol. Chem.─Eur. J. 2009, 15 (8), 1991– 1999, DOI: 10.1002/chem.200801776Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXit1Wjurg%253D&md5=c12cd711c78260f6e370bf95012cde29Zr-zeolite beta: a new heterogeneous catalyst system for the highly selective cascade transformation of citral to (±)-mentholNie, Yuntong; Jaenicke, Stephan; Chuah, Gaik-KhuanChemistry - A European Journal (2009), 15 (8), 1991-1999CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The transformation of citral to menthols involves hydrogenation steps as well as cyclization of the intermediate, citronellal. The ability of Zr-zeolite beta to catalyze the cyclization with high diastereoselectivity to (±)-isopulegol is the crit. step in this cascade transformation. Bifunctional catalysts contg. nickel or rhodium supported on Zr-zeolite beta gave menthols in yields of 87-89% and an excellent diastereoselectivity of 94% for the desired (±)-menthol. Dual catalyst systems of Zr-zeolite beta and nano-dispersed Ni on an MCM-41 support were equally effective and have the added advantage that the rates of the acid and hydrogenation-catalyzed steps can be independently varied. By applying a pressure ramp of 0.2-2 MPa, the yield of menthols could be increased to 95%, with 94% diastereoselectivity for (±)-menthol. The low initial pressure minimizes the rates of competing hydrogenation reactions to byproducts such as citronellol and 3,7-dimethyloctanol.
- 16Mäki-Arvela, P.; Kumar, N.; Kubička, D.; Nasir, A.; Heikkilä, T.; Lehto, V. P.; Sjöholm, R.; Salmi, T.; Murzin, D. Y. One-pot citral transformation to menthol over bifunctional micro-and mesoporous metal modified catalysts: Effect of catalyst support and metal. J. Mol. Catal. A: Chem. 2005, 240 (1–2), 72– 81, DOI: 10.1016/j.molcata.2005.06.023Google ScholarThere is no corresponding record for this reference.
- 17Vajglová, Z.; Navas, M.; Mäki-Arvela, P.; Eränen, K.; Kumar, N.; Peurla, M.; Murzin, D. Y. Transformations of citral over bifunctional Ru-HY-80 extrudates in a continuous reactor. Chem. Eng. J. 2022, 429, 132190, DOI: 10.1016/j.cej.2021.132190Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitVSrsrnN&md5=4a7daa1b87863c4186ec7bc887eb550cTransformations of citral over bifunctional Ru-H-Y-80 extrudates in a continuous reactorVajglova, Zuzana; Navas, Marisa; Maki-Arvela, Paivi; Eranen, Kari; Kumar, Narendra; Peurla, Markus; Murzin, Dmitry Yu.Chemical Engineering Journal (Amsterdam, Netherlands) (2022), 429 (), 132190CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)One-pot transformations of citral were investigated over Ru-catalysts in a batch and a continuous mode over a powder catalyst and extrudates, resp. Ru/H-Y-80 catalysts were prepd. by different impregnation methods to obtain different particle sizes of Ru. The highest yield of isopulegols was 15% and yield of menthols was 3% with stereoselectivity to the desired (±)-menthol isomer of 42% after 5 h over the Ru/H-Y-80 powder catalyst with the smallest metal particles prepd. by the incipient wetness impregnation method with six impregnation steps using Ru(NO)(NO3)3 as a precursor. This catalyst was synthesized with the Bindzil binder and shaped by extrusion. For comparison, also a catalyst with Ru deposited on the binder was prepd. Addn. of 30 wt% Bindzil binder to Ru/H-Y-80 catalyst caused significant catalyst deactivation. Z/E-citral ratio decreased with increasing Ru particle size. Citral conversion and the yield of acyclic hydrogenation products were higher over the powder catalysts contg. a mixt. of zeolite and binder with a larger distance between the metal and the acid sites, i.e. with Ru deposited on the Bindzil binder. Long-term expts. in the continuous mode revealed comparable catalytic behavior of both Ru-extrudates with the controlled metal location due to the presence of diffusion regime. The max. yield of menthols, 6%, with stereoselectivity to the desired (±)-menthol of 73% was obtained during the transient state, below 2 h of time-onstream. The reuse of Ru/H-Y-80 extrudates was successfully demonstrated.
- 18Vajglová, Z.; Mäki-Arvela, P.; Eränen, K.; Kumar, N.; Peurla, M.; Murzin, D. Y. Catalytic transformations of citral in a continuous flow over bifunctional Ru-MCM-41 extrudates. Catal. Sci. Techn. 2021, 11 (8), 2873– 2884, DOI: 10.1039/D1CY00066GGoogle ScholarThere is no corresponding record for this reference.
- 19Negoi, A.; Teinz, K.; Kemnitz, E.; Wuttke, S.; Parvulescu, V. L.; Coman, S. M. Bifunctional nanoscopic catalysts for the one-pot synthesis of (±)-menthol from citral. Top. Catal. 2012, 55 (7), 680– 687, DOI: 10.1007/s11244-012-9850-yGoogle Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XovVGqu7g%253D&md5=3c5be7393454df35c89c1a79ef6ebbe9Bifunctional Nanoscopic Catalysts for the One-Pot Synthesis of (±)-Menthol from CitralNegoi, Alina; Teinz, Katharina; Kemnitz, Erhard; Wuttke, Stefan; Parvulescu, Vasile I.; Coman, Simona M.Topics in Catalysis (2012), 55 (7-10), 680-687CODEN: TOCAFI; ISSN:1022-5528. (Springer)Active and selective bifunctional Me(Ir, Pd)/beta zeolite and doped nanoscopic hydroxylated fluorides (0.1 % Pd (or Pt)/AlF3) catalysts were developed for the one-pot synthesis of menthols from citral. In the case of fluoride catalysts, the strong electron-withdrawing effect of the dominating fluoride environment depletes the metal surface from electrons and hence, favors the hydrogenation of the C=C bond to citronellal on both Pd and Pt-based catalysts.
- 20Simakova, I.; Mäki-Arvela, P.; Martínez-Klimov, M.; Muller, J.; Vajglová, Z.; Peurla, M.; Eränen, K.; Murzin, D. Yu. Continuous synthesis of menthol from citronellal and citral over Ni-Beta-zeolite-sepiolite composite catalyst. Appl. Catal. A: Gen. 2022, 636, 118586, DOI: 10.1016/j.apcata.2022.118586Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XotlGht70%253D&md5=2c9f40e926b54f4f51dff784e298a3e4Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalystSimakova, Irina; Maki-Arvela, Paivi; Martinez-Klimov, Mark; Muller, Joseph; Vajglova, Zuzana; Peurla, Markus; Eranen, Kari; Murzin, Dmitry Yu.Applied Catalysis, A: General (2022), 636 (), 118586CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60-70°C under 10-29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71-76% and 72-74% were obtained from citronellal and citral resp. at the contact time 4.2 min, 70°C and 20 bar. Citral conversion noticeably decreased with time-onstream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amt. of defunctionalization products obsd. during citral conversion, esp. at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepd. by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chem. and catalytic properties.
- 21Simakova, I. L.; Vajglová, Z.; Mäki-Arvela, P.; Eränen, K.; Hupa, L.; Peurla, M.; Mäkilä, E. M.; Wärnå, J.; Murzin, D. Yu. Citral-to-menthol transformations in a continuous reactor over Ni/mesoporous aluminosilicate extrudates containing a sepiolite clay binder. Org. Proc. Res. 2022, 26, 387– 403, DOI: 10.1021/acs.oprd.1c00435Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVGjs7k%253D&md5=69dec8359b202dab2bbdc0c04e68079eCitral-to-Menthol Transformations in a Continuous Reactor over Ni/Mesoporous Aluminosilicate Extrudates Containing a Sepiolite Clay BinderSimakova, Irina L.; Vajglova, Zuzana; Maki-Arvela, Paivi; Eranen, Kari; Hupa, Leena; Peurla, Markus; Makila, Ermei M.; Warna, Johan; Murzin, Dmitry Yu.Organic Process Research & Development (2022), 26 (2), 387-403CODEN: OPRDFK; ISSN:1083-6160. (American Chemical Society)One-pot continuous synthesis of menthols from citral was performed over 5 wt % Ni supported on a mesoporous aluminosilicate catalyst with sepiolite as a binder at 70°C with a selectivity of 75% to menthols. Catalyst deactivation with time-onstream resulted in a decrease of the conversion and selectivity to menthol at the expense of higher selectivity to isopulegols. Stereoselectivity to isopulegols and menthols only slightly changed with conversion and TOS. A kinetic model capable of describing exptl. data for transformations of citral to menthol in a continuous mode was developed. It was based on a detailed reaction network and also comprised deactivation on both metal and acid sites. Numerical data fitting confirmed a good correspondence between the exptl. data and calcns.
- 22Nefzi, H.; Abderrabba, M.; Ayadi, S.; Labidi, J. Formation of palygorskite clay from treated diatomite and its application for the removal of heavy metals from aqueous solution. Water 2018, 10 (9), 1257, DOI: 10.3390/w10091257Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVKjtr3E&md5=e2526514a5b61cc603df69798c10165bFormation of palygorskite clay from treated diatomite and its application for the removal of heavy metals from aqueous solutionNefzi, Houwaida; Abderrabba, Manef; Ayadi, Sameh; Labidi, JalelWater (Basel, Switzerland) (2018), 10 (9), 1257/1-1257/15CODEN: WATEGH; ISSN:2073-4441. (MDPI AG)Environmental contamination by toxic heavy metals is a serious worldwide phenomenon. Thus, their removal is a crucial issue. In this study, we found an efficient adsorbent to remove Cu2+ and Ni2+ from aq. soln. using two materials. Chem. modification was used to obtain palygorskite clay from diatomite. The adsorbents were characterized using X-ray florescence, Fourier transform IR spectroscopy and X-ray diffraction. The effects of contact time, initial concn., temp. and pH on the adsorption process were investigated. Our results showed that the (%) of max. adsorption capacity of diatomite was 78.44% for Cu2+ at pH 4 and 77.3% for Ni2+ at pH 7, while the (%) of the max. adsorption on palygorskite reached 91% for Cu2+ and 87.05% for Ni2+, in the same condition. The results indicate that the pseudo-second-order model can describe the adsorption process. Furthermore, the adsorption isotherms could be adopted by the Langmuir and the Freundlich models with good correlation coeff. (R2). Thus, our results showed that palygorskite prepd. from Tunisian diatomite is a good adsorbent for the removal of heavy metals from water.
- 23Xie, A.; Zhou, X.; Huang, X.; Ji, L.; Zhou, W.; Luo, S.; Yao, C. Cerium-loaded MnOx/attapulgite catalyst for the low-temperature NH3-selective catalytic reduction. J. Ind. Eng. Chem. 2017, 49, 230– 241, DOI: 10.1016/j.jiec.2017.01.034Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXitlOjsL8%253D&md5=4e842290402d46dc938b8a42e4ec6d70Cerium-loaded MnOx/attapulgite catalyst for the low-temperature NH3-selective catalytic reductionXie, Aijuan; Zhou, Xingmeng; Huang, Xiaoyan; Ji, Liang; Zhou, Wenting; Luo, Shiping; Yao, ChaoJournal of Industrial and Engineering Chemistry (Amsterdam, Netherlands) (2017), 49 (), 230-241CODEN: JIECFI; ISSN:1226-086X. (Elsevier B.V.)A series of MnO2/attapulgite (ATP) and n(Ce):n(Mn)/ATP (molar ratios) catalysts were prepd. and investigated for the selective catalytic redn. of NO by NH3 (NH3-SCR) at low temp. The results showed that the 7 wt % MnO2/ATP exhibited the best NOx conversion (85% at 300°C) among all MnO2/ATP catalysts of different mass ratios. The introduction of cerium enhanced the NOx conversion at low temp., and so Ce-MnOx/ATP can reach the highest NOx conversion (95% at 300°C). Meanwhile, the as-prepd. catalysts were characterized by XRD, TEM, BET, H2-TPR, NH3-TPD, and XPS. It can be deduced from TEM, XRD, and BET, MnOx nanorods in this work mainly existed in the β-MnO2, and cerium highly dispersed on the surface of ATP to form porous structure and thus improved the deNOx performance. Moreover, the study of SO2 tolerance demonstrated that cerium can effectively inhibit SO2 poison. XPS results illustrated that Ce could enhance Mn4+ content on the surface of the catalyst and thus lead to high SCR activity. Therefore Mn(1):Ce(0.25)/ATP was proved to be an excellent catalyst for NH3-SCR.
- 24Guo, S.; Shi, L. Synthesis of succinic anhydride from maleic anhydride on Ni/diatomite catalysts. Catal. Today 2013, 212, 137– 141, DOI: 10.1016/j.cattod.2012.10.004Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs1Gkt7bL&md5=1ef4f6585eaeea664aecfa773b953881Synthesis of succinic anhydride from maleic anhydride on Ni/diatomite catalystsGuo, Shaofei; Shi, LiCatalysis Today (2013), 212 (), 137-141CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)The characteristics and catalytic properties of Ni(5%)/diatomite, Ni(5%)/γ-Al2O3, Ni(5% wt)/Bentonite clay and Ni(5%)/attapulgite clay were investigated and compared in terms of catalytic activities for liq.-phase hydrogenation of maleic anhydride (MA). The results showed that the diatomite support exhibited the highest activity and selectivity. Using Ni(7%)/diatomite catalyst, the 100% conversion of MA and 96.20% selectivity to SA were obtained for MA hydrogenation at 190°. The x-ray diffraction (x-ray diffraction) studies showed that there is only NiO on the support and no elemental nickel (Ni0) and Ni2O3 was detected in unreduced samples. X-ray diffraction and H2 temp.-programmed redn. (TPR) studies also showed that NiO species were all converted to metallic nickel (Ni0) after redn. at 350°.
- 25Anderson, J. A.; Rodrigo, M. T.; Daza, L.; Mendioroz, S. Influence of the support in the selectivity of nickel/clay catalysts for vegetable oil hydrogenation. Langmuir 1993, 9 (10), 2485– 2490, DOI: 10.1021/la00034a001Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmtVaisLc%253D&md5=c5e1a0dbbbd5823b9795d9ca6e4b6499Influence of the support in the selectivity of nickel/clay catalysts for vegetable oil hydrogenationAnderson, J. A.; Rodrigo, M. T.; Daza, L.; Mendioroz, S.Langmuir (1993), 9 (10), 2485-90CODEN: LANGD5; ISSN:0743-7463.Two naturally occurring clays of Spanish origin, bentonite and palygorskite, have been used as support material for nickel hydrogenation catalysts in which the active phase has been deposited by means of the pptn. method. The structural and textural characteristics of the supports have been studied by XRD, N2 adsorption/desorption, and mercury porosimetry and the acid sites detd. by thermogravimetry and IR studies of adsorbed pyridine. The Ni phases present were characterized by XRD, TEM, XPS, FTIR of adsorbed CO, and the degree of redn. detd. thermogravimetrically. XRD and TEM indicate Ni particle size to be equiv. for both supports although the detection by FTIR of a high proportion of bridging CO for the bentonite support suggests the presence of addn. small particles for this support which may be located between lamellae. These smaller particles are consistent with the more difficult redn. of Ni in this support. Although activity for the hydrogenation of sunflower oil was similar for both catalysts, significant differences regarding the selectivity have been obsd. which may be attributed to the differences in morphol. of the support materials. Mass transport limitations resulting from reaction of linoleic acid at Ni sites between lamellae of bentonite leads to consecutive hydrogenation through to stearic acid, whereas the palygorskite supported catalyst remained highly selective to oleic acid even at high conversion levels.
- 26Zecevic, J.; Vanbutsele, G.; de Jong, K. P.; Martens, J. A. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons. Nature 2015, 528 (7581), 245– 248, DOI: 10.1038/nature16173Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitVSiu7zL&md5=ac34c2f671e3ded4954c9c6e1fea783aNanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbonsZecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.Nature (London, United Kingdom) (2015), 528 (7581), 245-248CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for >50 years the so-called intimacy criterion has dictated the max. distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometer precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as the closer the better for positioning metal and acid sites. Here the authors show for a bifunctional catalyst-comprising an intimate mixt. of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder-that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock mols. for high-quality diesel prodn. is optimized with the catalyst that contains platinum on the binder, i.e., with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon mols. that are typically derived from alternative sources, such as gas-to-liq. technol., vegetable oil or algal oil, should benefit esp. from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, the authors anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.
- 27Harmel, J.; Roberts, T.; Zhang, Z.; Sunley, G.; de Jongh, P.; de Jong, K. P. Bifunctional molybdenum oxide/acid catalysts for hydroisomerization of n-heptane. J. Catal. 2020, 390, 161– 169, DOI: 10.1016/j.jcat.2020.08.004Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhs1yksrbP&md5=928b563a0fdadf9d85c47b2907c4331eBifunctional molybdenum oxide/acid catalysts for hydroisomerization of n-heptaneHarmel, Justine; Roberts, Tegan; Zhang, Zhaorong; Sunley, Glenn; de Jongh, Petra; de Jong, Krijn P.Journal of Catalysis (2020), 390 (), 161-169CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Inc.)Numerus research studies focus on replacing scarce noble metals by nonnoble transition metals in solid catalysts. The (de)hydrogenation function in bifunctional catalysts for hydroisomerization and hydrocracking of alkanes is usually performed by a precious metal such as Pt, or a metal sulfide such as MoS2. The authors studied the possibility of replacing Pt with a nonsulfided MoOx catalyst in combination with a mesoporous solid acid for the hydroisomerization of n-heptane. MoOx particles size as well as the prepn. techniques were varied to identify the Mo active phase for (de)hydrogenation. An optimized nonprecious metal MoOx catalyst can perform similarly to its Pt counterpart in the n-heptane conversion when used in combination with a mesoporous solid acid.
- 28Vajglová, Z.; Kumar, N.; Peurla, M.; Hupa, L.; Semikin, K.; Sladkovskiy, D. A.; Murzin, D. Yu. Effect of the preparation of Pt-modified zeolite beta-bentonite extrudates on their catalytic behavior in n-hexane hydroisomerization. Ind. Eng. Chem. Res. 2019, 58 (25), 10875– 10885, DOI: 10.1021/acs.iecr.9b01931Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtVygsLjF&md5=64efd204ca488a536c3d5dacba0ceab2Effect of the Preparation of Pt-Modified Zeolite Beta-Bentonite Extrudates on Their Catalytic Behavior in n-Hexane HydroisomerizationVajglova, Zuzana; Kumar, Narendra; Peurla, Markus; Hupa, Leena; Semikin, Kirill; Sladkovskiy, Dmitry A.; Murzin, Dmitry Yu.Industrial & Engineering Chemistry Research (2019), 58 (25), 10875-10885CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Four different types of shaped catalysts with controlled deposition of Pt and the same compn. were prepd. by extrusion of beta zeolite agglomerated with bentonite as an aluminosilicate clay binder. The catalysts were characterized using mech. strength tests; SEM for morphol.; TEM for porosity and periodicity; N physisorption for surface area, pore vol., and pore size distribution; and FTIR spectroscopy using pyridine as a probe mol. to elucidate the presence, strength, and amt. of Broensted and Lewis acid sites. Elemental anal. was carried out using energy-dispersive x-ray microanal. Activity and selectivity of catalysts in the isomerization of n-hexane were evaluated using a fixed bed reactor at 200-350°. At low temp., the performance of metal/acid bifunctional shaped catalysis was strongly affected by the metal-to-acid site ratio. This ratio and the total acidity were strongly influenced by the prepn. method of the shaped catalysts, while the textural properties were comparable. The highest conversion of n-hexane and selectivity to C6 isomers (comprising all branched isomers, such as Me pentane and dimethylbutane) was obtained with extrudates prepd. via in situ synthesis with Pt located on the zeolite. The extrudates prepd. in this way have the highest metal-to-acid site ratio and their closest proximity, albeit the lowest mech. strength.
- 29Vajglová, Z.; Simakova, I. L.; Eränen, K.; Mäki-Arvela, P.; Kumar, N.; Peurla, M.; Tolvanen, S.; Efimov, A.; Hupa, L.; Peltonen, J.; Murzin, D. Yu. The physicochemical and catalytic properties of clay extrudates in cyclization of citronellal. Appl. Catal. A: Gen. 2022, 629, 118426, DOI: 10.1016/j.apcata.2021.118426Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisFWhtrjO&md5=bce879bef3ddafefe2961eb1490accb0The physicochemical and catalytic properties of clay extrudates in cyclization of citronellalVajglova, Zuzana; Simakova, Irina L.; Eranen, Kari; Maki-Arvela, Paivi; Kumar, Narendra; Peurla, Markus; Tolvanen, Stiina; Efimov, Alexander; Hupa, Leena; Peltonen, Jouko; Murzin, Dmitry Yu.Applied Catalysis, A: General (2022), 629 (), 118426CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Four clay materials, namely, bentonite, bleaching earth, attapulgite and sepiolite, were shaped into the cylindrical body by extrusion. Clays were characterized in depth by TEM, SEM-EDX, N2 physisorption, pyridine FTIR, pH measurements, contact angle measurements, 27Al MAS NMR, and the crush test. Catalytic properties were investigated in the citronellal cyclization as a model reaction. The reaction was performed in the trickle-bed reactor at 70°C, 10 bar of Ar with 0.086 M initial citronellal concn. in cyclohexane. The best results were obtained over attapulgite with isopulegols yield of 24% and stereoselectivity to the desired isopulegol isomer of 61%. Attapulgite had the highest meso-to-micropore vol. ratio, the highest basicity, a low Bronsted-to-Lewis acid sites ratio, and the lowest amt. of Bronsted acid sites compared to other extrudates. In addn., same clay exhibited the highest mech. strength of extrudates.
- 30Emeis, C. A. Determination of integrated molar extinction coefficients for infrared absorption bands of pyridine adsorbed on solid acid catalysts. J. Catal. 1993, 141, 347– 354, DOI: 10.1006/jcat.1993.1145Google Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXltVCisLs%253D&md5=ba711e5e8cb157ce77e04900e6fb0e35Determination of integrated molar extinction coefficients for infrared absorption bands of pyridine adsorbed on solid acid catalystsEmeis, C. A.Journal of Catalysis (1993), 141 (2), 347-54CODEN: JCTLA5; ISSN:0021-9517.Integrated molar extinction coeffs. were detd. for IR absorption bands of pyridine adsorbed on acid sites in Si/Al-based catalysts. The IR spectra of five zeolites and two amorphous silica-aluminas were recorded during quant. dosing of pyridine gas at 150°. The integrated mol. extinction coeffs. were calcd. assuming that they did not depend on the catalyst or the strength of the acid site. The resulting values were 1.67 cm/μmol for the 1545-cm-1 band characteristic of pyridine on a Broensted acid site and 2.22 cm/μmol for the 1455-cm-1 band of pyridine on a Lewis acid site. The 95% confidence limits were estd. at ±15%. Subsequent anal. of the data provided no evidence for a dependence of the integrated coeffs. on the catalyst or the strength of the site. The measurements gave indications for differences between the rates of reaction of Broensted and Lewis acid sites with pyridine.
- 31Powder Diffraction File database PDF-2; International Centre for Diffraction Data: USA, 2009.Google ScholarThere is no corresponding record for this reference.
- 32Vajglova, Z.; Kumar, N.; Mäki-Arvela, P.; Eränen, K.; Peurla, M.; Hupa, L.; Nurmi, M.; Toivakka, M.; Murzin, D. Y. Synthesis and physicochemical characterization of shaped catalysts of β and Y zeolites for cyclization of citronellal. Ind. Eng. Chem. Res. 2019, 58 (39), 18084– 18096, DOI: 10.1021/acs.iecr.9b02829Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhslWgtr7N&md5=15a472044778cc132d263682710f8d94Synthesis and Physicochemical Characterization of Shaped Catalysts of β and Y Zeolites for Cyclization of CitronellalVajglova, Zuzana; Kumar, Narendra; Maki-Arvela, Paivi; Eranen, Kari; Peurla, Markus; Hupa, Leena; Nurmi, Maristiina; Toivakka, Martti; Murzin, Dmitry YuIndustrial & Engineering Chemistry Research (2019), 58 (39), 18084-18096CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Continuous cyclization of citronellal over zeolite-based extrudates was performed in a trickle-bed reactor at 35-70 °C and 10 bar of argon. Catalytic results were correlated with the physicochem. properties of the shaped catalyst prepd. by extrusion of β or Y zeolites with binders. Rheol. tests were used to elucidate the flow properties of a catalytic slurry and relate them with the extrusion performance. This study revealed that application of methylcellulose and bentonite binder modified the textural and acidic properties of the final extrudates. The main product was (-)-isopulegol at all temps. with selectivity remaining quite const. with time-onstream. The results illustrated that a binder such as bentonite cannot be considered inert. The mass-transfer limitations obsd. in extrudates did not significantly influence selectivity to the desired pulegols. This study also showed that a direct transfer of the batch reactor data to industrial continuous operation in citronellal cyclization is not straightforward.
- 33Boudriche, L.; Chamayou, A.; Calvet, R.; Hamdi, B.; Balard, H. Influence of different dry milling processes on the properties of an attapulgite clay, contribution of inverse gas chromatography. Powder technology 2014, 254, 352– 363, DOI: 10.1016/j.powtec.2014.01.041Google Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjtFSks7k%253D&md5=e9be15d6f44e9de2ae3b194fb49063a7Influence of different dry milling processes on the properties of attapulgitic clay, contribution of inverse gas chromatographyBoudriche, L.; Chamayou, A.; Calvet, R.; Hamdi, B.; Balard, H.Powder Technology (2014), 254 (), 352-363CODEN: POTEBX; ISSN:0032-5910. (Elsevier B.V.)The effect of dry milling processes on the surface properties of an attapulgitic clay, also called palygorskite, was investigated by carrying out expts. with different types of grinding devices. Ground products were then characterized by size measurement, SEM, X-ray diffraction, adsorption-desorption of N2 and inverse gas chromatog. at infinite diln. (IGC-ID) as well as finite concn. conditions (IGC-FC). These analyses were performed to evaluate the changes in particle size distribution, morphol., crystallinity and surface properties of attapulgite powder, resp. Among the tested dry grinding devices, grinding in an air jet mill (Alpine 50 AS) and a vibratory ball mill (Pulverisette 0) led to the most significant particle size redn. SEM photomicrographs showed that a breakage of the fibrous structure took place during dry grinding. Moreover, long grinding in Pulverisette 0 resulted in the complete destruction of fiber morphol. followed by agglomeration. XRD anal. showed that whatever the grinding process, the microstructure of the attapulgite was not affected. IGC confirmed that only grinding in Pulverisette 0 affected the surface properties notably. In this case, the most significant decreases were obsd. in the dispersive component of the surface energy (164 to 116 mJ/m2) and in the sp. surface area obtained with the octane probe (114.5 m2/g to 62.6 m2/g) by IGC-ID and IGC-FC, resp. At the same time, a modification of the distribution functions of the adsorption energies (DFAE), giving information about surface heterogeneity, was noticed.
- 34Nugraha, R. E.; Prasetyoko, D.; Bahruji, H.; Suprapto, S.; Asikin-Mijan, N.; Oetami, T. P.; Dai-Veit, N. Vo.; Taufiq-Yap, Y. H. Lewis acid Ni/Al-MCM-41 catalysts for H2-free deoxygenation of Reutealis trisperma oil to biofuels. RSC Adv. 2021, 11 (36), 21885– 21896, DOI: 10.1039/D1RA03145GGoogle Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtlKju7zI&md5=0615397f1c1f80c90ef4bed34b5c8ac7Lewis acid Ni/Al-MCM-41 catalysts for H2-free deoxygenation of Reutealis trisperma oil to biofuelsNugraha, Reva Edra; Prasetyoko, Didik; Bahruji, Hasliza; Suprapto, Suprapto; Asikin-Mijan, Nurul; Oetami, Titie Prapti; Jalil, Aishah Abdul; Vo, Dai-Viet N.; Taufiq-Yap, Yun HinRSC Advances (2021), 11 (36), 21885-21896CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)The activity of mesoporous Al-MCM-41 for deoxygenation of Reutealis trisperma oil (RTO) was enhanced via modification with NiO nanoparticles. Deoxygenation at atm. pressure and under H2 free conditions required acid catalysts to ensure the removal of the oxygenated fragments in triglycerides to form liq. hydrocarbons. NiO at different wt. loadings was impregnated onto Al-MCM-41 and the changes of Lewis/Bronsted acidity and mesoporosity of the catalysts were investigated. The activity of Al-MCM-41 was enhanced when impregnated with NiO due to the increase of Lewis acidity originating from NiO nanoparticles and the mesoporosity of Al-MCM-41. Increasing the NiO loading enhanced the Lewis acidity but not Bronsted acidity, leading to a higher conversion toward liq. hydrocarbon yield. Impregnation with 10% of NiO on Al-MCM-41 increased the conversion of RTO to hydrocarbons via the deoxygenation pathway and reduced the products from cracking reaction, consequently enhancing the green diesel (C11-C18) hydrocarbon products.
- 35Yang, L.; Huang, J.; Cen, J.; Chen, D. L.; Zeng, H.; Rui, Z.; Luque, R.; Duan, P. Lewis acid (Ni 2+, Co 2+/3+ or Zn 2+) modified electron-deficient Ir 4+ in IrO 2/CuO for promoting methane oxidation to ethanol and methanol. J. Mater. Chem. A 2021, 9 (11), 7094– 7101, DOI: 10.1039/D0TA10842AGoogle Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjtlClt7k%253D&md5=b8a1e7fe817b1c2100649008282beb87Lewis acid (Ni2+, Co2+/3+ or Zn2+) modified electron-deficient Ir4+ in IrO2/CuO for promoting methane oxidation to ethanol and methanolYang, Le; Huang, Jinxu; Cen, Jie; Chen, De-Li; Zeng, Hui; Rui, Zebao; Luque, Rafael; Duan, PeigaoJournal of Materials Chemistry A: Materials for Energy and Sustainability (2021), 9 (11), 7094-7101CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)This work delineates the first attempt to tune the product distribution between methanol and ethanol in the direct oxidn. of methane reaction by incorporating Lewis acids Ni2+, Co2+/3+ or Zn2+ into IrO2/CuO. The electrophilicity of Ir4+ and the (LAS-BAS)/LAS ratio (LAS: Lewis acid sites, BAS: Bronsted acid sites) are demonstrated to be two reactivity descriptors motivating CH4 activation and ethanol formation, resp. Electron-deficient Ir4+ motivates enriched *CH3 concn. and subsequent C-C coupling for C2H4 formation, while the Lewis acid promotes ethanol formation from C2H4 involving lattice O and H2O. The ethanol selectivity presents a quasi-linear relationship with (LAS-BAS)/LAS.
- 36Wei, Z.; Xia, T.; Ma, J.; Feng, W.; Dai, J.; Wang, Q.; Yan, P. Investigation of the lattice expansion for Ni nanoparticles. Mater. Charact. 2007, 58 (10), 1019– 1024, DOI: 10.1016/j.matchar.2006.08.004Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpsl2ju7w%253D&md5=ff5df38b8346b66450c35ce67b090c98Investigation of the lattice expansion for Ni nanoparticlesWei, Zhiqiang; Xia, Tiandong; Ma, Jun; Feng, Wangjun; Dai, Jianfeng; Wang, Qing; Yan, PengxunMaterials Characterization (2007), 58 (10), 1019-1024CODEN: MACHEX; ISSN:1044-5803. (Elsevier B.V.)Nickel nanoparticles with various grain sizes were successfully prepd. by anodic arc discharge plasma method. The samples prepd. by this method were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the corresponding selected-area electron diffraction (SAED) to det. the crystal structure, lattice parameter, morphol. and particle size. The expt. results indicate that the crystal structure of the samples is fcc. structure as same as the bulk materials. The lattice parameters for Ni nanoparticles are always larger than the equil. values of the perfect single crystal lattice resp., the lattice parameter increase significantly with the decrease of the grain size, the lattice expansion was found, and the expansion quantity of the lattice parameter is in direct proportion to the reciprocal of grain size. The values of the unit cell vol. increase remarkably with the decrease of the grain size. The lattice expansion is the result of the interfacial energy and surface tension mutual attraction of Ni nanoparticles, this phenomenon can be explained according to the thermodn. theory.
- 37Quindimil, A.; De-La-Torre, U.; Pereda-Ayo, B.; Gonzalez-Marcos, J. A.; Gonzalez-Velasco, J. R. Ni catalysts with La as promoter supported over Y-and Beta-zeolites for CO2 methanation. Appl. Catal. B: Env. 2018, 238, 393– 403, DOI: 10.1016/j.apcatb.2018.07.034Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtlOgs77F&md5=7bf1190b202c9aa6a53abb1d315231ceNi catalysts with La as promoter supported over Y- and BETA- zeolites for CO2 methanationQuindimil, Adrian; De-La-Torre, Unai; Pereda-Ayo, Benat; Gonzalez-Marcos, Jose A.; Gonzalez-Velasco, Juan R.Applied Catalysis, B: Environmental (2018), 238 (), 393-403CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)The hydrogenation of CO2 into methane is considered a plausible process to storage renewable energy in form of methane and reducing CO2 anthropogenic emissions. Microporous solids such as zeolites have been scarcely studied yet for this application. This study aims to evaluate and compare the catalytic performance of zeolite (Y and BETA) supported Ni catalysts for CO2 methanation. The physicochem. properties of the prepd. catalysts were characterized by XRD, BET, CO2-TPD, H2-TPR and XPS, and CO2 methanation was carried out in a tubular reactor at conditions of H2/CO2 = 4, GHSV = 10,000 h-1 and temps. from 200 to 500 C. Neutralization of both zeolites by Na+ ion exchange enhanced the CO2 conversion as weaker CO2 adsorption sites and reducibility are promoted. BETA resulted in a better support than Y zeolite due to the presence of more easily reducible Ni2+, which acts as precursor of active Ni° accessible under reaction conditions. Indeed, the surface basicity and Ni dispersion of Ni/BETA catalysts were considerably promoted by impregnation of different loads of La2O3, which increase the amt. of CO2 adsorption sites and even active hydrogenation sites resulting in a significant increase of activity and selectivity towards CH4. The optimal Ni-10%La2O3/Na-BETA formulation resulted in T50 of 320°C, CO2 conversion of 65% at 350 °C, with almost total selectivity to CH4 and maintaining stability for more than 24 h.
- 38Wang, Y.; Liang, D.; Wang, C.; Chen, M.; Tang, Z.; Hu, J.; Yang, Z.; Zhang, H.; Wang, J.; Liu, S. Influence of calcination temperature of Ni/attapulgite on hydrogen production by steam reforming ethanol. Renew. Energy 2020, 160, 597– 611, DOI: 10.1016/j.renene.2020.06.126Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVOrtb7I&md5=88e36188daabb99f88dfa206c7f247f6Influence of calcination temperature of Ni/Attapulgite on hydrogen production by steam reforming ethanolWang, Yishuang; Liang, Defang; Wang, Chunsheng; Chen, Mingqiang; Tang, Zhiyuan; Hu, Jiaxin; Yang, Zhonglian; Zhang, Han; Wang, Jun; Liu, ShaominRenewable Energy (2020), 160 (), 597-611CODEN: RNENE3; ISSN:0960-1481. (Elsevier Ltd.)Sustainable hydrogen prodn. can be realized by steam reforming ethanol (SRE) derived from renewable biomass, but develop high-efficiency and sixpenny catalyst is a major challenge. Attapulgite-supported nickel catalyst (Ni/ATP) exhibits promising potential for SRE for hydrogen prodn. The influence of calcination temp. (CT) on the microscopic morphol. and physicochem. properties of Ni/ATP was investigated by various technologies. The results revealed that increasing CT could improve metal-support interaction (MSI) and surface Ni active species content. However, extortionate CT (>700°C) significantly led to catalyst structure collapse and crystal phase transfer accompanied with the formation of new species, which enhanced the MSI and reduced the surface Nio species content. The outcomes of SRE expts. demonstrated that Ni/ATP-C600 presented maximal activity and H2 yield due to its higher surface contents of the Nio active component and Ni/ATP-C900 exhibited unique stability owing to its stronger MSI. Hence, the coordination between active species distribution and MSI in Ni/ATP can be adjusted by CT. Addnl. coke deposits on spent Ni/ATP-C300 were identified with quite arom. species, which strongly attract to the surface of catalyst and encapsulate active site, while that on used Ni/ATP-C900 had higher degrees of graphitization, but did not affect the stability.
- 39Bertero, N. M.; Trasarti, A. F.; Apesteguía, C. R.; Marchi, A. J. Liquid-phase dehydration of 1-phenylethanol on solid acids: Influence of catalyst acidity and pore structure. Appl. Catal. A: Gen. 2013, 458, 28– 38, DOI: 10.1016/j.apcata.2013.03.018Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXnsVGht7s%253D&md5=cffd590d7348b13f295c7210bc0a070dLiquid-phase dehydration of 1-phenylethanol on solid acids: Influence of catalyst acidity and pore structureBertero, Nicolas M.; Trasarti, Andres F.; Apesteguia, Carlos R.; Marchi, Alberto J.Applied Catalysis, A: General (2013), 458 (), 28-38CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)The liq.-phase dehydration of 1-phenylethanol (PHE) over different solid acids was studied at 363 K using cyclohexane as solvent. It was found that the catalyst activity and selectivity strongly depended on: (1) the nature, strength and d. of acid sites and (2) the textural properties of the catalyst. Catalysts contg. mainly surface Bronsted acid sites of medium-high strength, such as Amberlyst 15, HPA/SiO2, and HMOR zeolite, showed low initial styrene (STY) selectivity because the PHE dehydrated to alpha-methylbenzyl ether (AME) at higher or similar rates than to STY. Both primary products, STY and AME, were consecutively transformed to other heavy products (HP). Catalysts contg. predominantly Lewis acid sites, such as ZnO/SiO2, Al-MCM-41 and SiO2-Al2O3, selectively transformed PHE to AME. The ether can be sequentially converted to STY and HP, depending on the solid acidity. Solid acids having strong surface Lewis sites, e.g. SiO2-Al2O3, showed high dehydration rate and HP prodn. Samples contg. exclusively weak Lewis acid sites, e.g. γ-Al2O3, were not active in the PHE dehydration at 363 K. Only zeolites HZSM-5, HBEA and HY, with similar surface d. of Bronsted and Lewis acid sites, converted selectively PHE into STY, giving initial STY selectivities between 83 and 96%. However, HY zeolite was rapidly deactivated due to the blockage of its microporous structure by bulky compds. formed inside the large cages of 13 Å. Instead, on HBEA, STY was converted to HP that can diffuse through the solid microporous structure. Then, the selectivity to STY was drastically reduced with time. A const. and high STY selectivity at total PHE conversion was only obtained with HZSM-5. The pore size of this zeolite is enough to allow the diffusion and conversion of PHE into STY, but it is not adequate to form the surface intermediates leading to AME and HP. Thus, it was proved that: (1) the surface Bronsted to Lewis ratio strongly influences the initial selectivity in the liq.-phase PHE dehydration; (2) a similar Bronsted to Lewis ratio on the solid acid surface is necessary to obtain high initial selectivity to STY; and (3) the right porous structure is crucial to avoid HP prodn. and keep const. the STY selectivity at high PHE conversion. From the exptl. results obtained in this work, a mechanistic approach was proposed in order to explain the influence of both acid site nature and pore size on the selective PHE dehydration in liq. phase.
- 40Chuah, G. K.; Liu, S. H.; Jaenicke, S.; Harrison, L. J. Cyclisation of citronellal to isopulegol catalysed by hydrous zirconia and other solid acids. J. Catal. 2001, 200 (2), 352– 359, DOI: 10.1006/jcat.2001.3208Google Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXktVKlsLc%253D&md5=1f5d013c4df20eb3ee7585e4158cb2dfCyclization of Citronellal to Isopulegol Catalyzed by Hydrous Zirconia and Other Solid AcidsChuah, G. K.; Liu, S. H.; Jaenicke, S.; Harrison, L. J.Journal of Catalysis (2001), 200 (2), 352-359CODEN: JCTLA5; ISSN:0021-9517. (Academic Press)A review with 29 refs. The cyclization of citronellal to isopulegol is an important step in the synthesis of menthol. Several zirconia-based catalysts were evaluated for this reaction. Zirconium hydroxides and phosphated zirconia had very good activity and selectivity. Ammonia TPD and pyridine IR studies indicate the presence of strong Lewis together with weak Bronsted acid sites. Other strong acids like sulfated zirconia, Amberlyst, and Nafion were very active but the selectivity toward isopulegol was poor. They catalyzed side reactions such as dehydration, cracking, and etherification of isopulegol. Silica, with only weak Lewis acidity, showed very low activity. The presence of both Lewis and Bronsted sites is therefore essential for the reaction. A reaction mechanism is proposed where the citronellal mol. binds to a zirconium Lewis acid site via the aldehyde oxygen and the π-electrons of the double bond so that the right configuration is attained for cyclization. Subsequent protonation of the aldehyde via a neighboring Bronsted acid site initiates the cyclization to isopulegol. (c) 2001 Academic Press.
Cited By
This article is cited by 3 publications.
- Irina L. Simakova, Zuzana Vajglová, Mark Martínez-Klimov, Kari Eränen, Markus Peurla, Päivi Mäki-Arvela, Dmitry Yu. Murzin. One-Pot Synthesis of Menthol from Citral over Ni/H-β-38 Extrudates Containing Bentonite Clay Binder in Batch and Continuous Reactors. Organic Process Research & Development 2023, 27
(2)
, 295-310. https://doi.org/10.1021/acs.oprd.2c00337
- Jie Dong, Wei Ding, Jinfei Wei, Ning Tian, Xueli Nan, Junping Zhang. Preparation of Food Grade Superhydrophobic Coatings Based on Attapulgite Nanorods. ACS Sustainable Chemistry & Engineering 2023, 11
(4)
, 1405-1413. https://doi.org/10.1021/acssuschemeng.2c05915
- Päivi Mäki-Arvela, Irina Simakova, Zuzana Vajglová, Dmitry Yu. Murzin. One-Pot Synthesis of Menthol from Citral and Citronellal Over Heterogeneous Catalysts. Catalysis Surveys from Asia 2023, 27
(1)
, 2-19. https://doi.org/10.1007/s10563-022-09376-6
Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.
Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.
The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.
Recommended Articles
Abstract
Figure 1
Figure 1. Reaction scheme for citral transformation to menthol. Legend: A – citral, B – citronellal, C – isopulegol isomers, D – menthol isomers, E – acyclic hydrogenation products, F – defunctionalization products, dimeric ethers, and heavy components.
Figure 2
Figure 2. XRD patterns of a) the calcined (c.), freshly reduced (r), and spent (s) [Ni/(H-Beta-38+Att.)] extrudates compared to the initial H-Beta-38 zeolite and b) the spent [Ni/(H-Beta-38+Att.)], [(Ni/H-Beta-38)+Att.], and [(Ni/Att.)+H-Beta-38] extrudates compared to the initial H-Beta-38 zeolite. Notation: spent [Ni/(H-Beta-38+Att.)] was used first in citronellal transformation; thereafter, it was reduced in situ and used in citral transformation, while spent [(Ni/H-Beta-38)+Att.] and [(Ni/Att.)+H-Beta-38] extrudates were only used in citral transformation.
Figure 3
Figure 3. TEM images of a) attapulgite, b) H-Beta-38, c) [Ni/(H-Beta-38+Att.)], d) [(Ni/H-Beta-38)+Att.], and e) [(Ni/Att.)+H-Beta-38].
Figure 4
Figure 4. Metal particle size distribution determined by TEM for a) [(Ni/H-Beta-38)+Att.] and b) [(Ni/Att.)+H-Beta-38].
Figure 5
Figure 5. SEM images of the fresh, reduced a) [(Ni/H-Beta-38)+Att.] and b) [(Ni/Att.)+H-Beta-38] catalysts.
Figure 6
Figure 6. Hydrogen TPR of a) [(Ni/H-Beta-38)+Att.] and b) [(Ni/Att.)+H-Beta-38].
Figure 7
Figure 7. a) Conversion of citronellal (■) and liquid phase mass balance (●) and b) concentration of menthols (●), acyclic hydrogenation products (■), and defunctionalized products (o) and stereoselectivity to menthol (Δ) in citronellal transformation over [Ni/(H-Beta-38+Att.)] as a function of TOS. The liquid flow rate was 0.2 mL/min during 215 min TOS; thereafter, it was 0.3 mL/min.
Figure 8
Figure 8. a) Conversion of citral, b) cis/trans ratio of citral, c) yield of menthols, d) stereoselectivity to menthol, e) yield of pulegols, f) acyclic hydrogenation products, g) 3,7-dimethyloctanol, h) defunctionalized products, (i) menthenes, and j) menthanes as a function of time-on-stream in citral transformation to menthols over different types of Ni extrudates. Notation: (■) [(Ni/H-Beta-38)+Att.], (●) [Ni/(H-Beta-38+Att.)], and (▲) [(Ni/Att.)+H-Beta-38].
References
This article references 40 other publications.
- 1Patel, T.; Ishiuji, Y.; Yosipovitch, G. Menthol: a refreshing look at this ancient compound. J. Am. Academy Dermat. 2007, 57 (5), 873– 878, DOI: 10.1016/j.jaad.2007.04.008There is no corresponding record for this reference.
- 2Trasarti, A. F.; Marchi, A. J.; Apesteguıa, C. R. Highly selective synthesis of menthols from citral in a one-step process. J. Catal. 2004, 224, 484– 488, DOI: 10.1016/j.jcat.2004.03.0162https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjvVGisLo%253D&md5=5ebd1bf9f6d046b1cf9ed2d3f68726e1Highly selective synthesis of menthols from citral in a one-step processTrasarti, A. F.; Marchi, A. J.; Apesteguia, C. R.Journal of Catalysis (2004), 224 (2), 484-488CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Science)For the first time the selective synthesis of menthols from citral in a one-step process is reported. Bifunctional metal/acid catalysts active and selective for menthol synthesis were developed by studying the individual steps involved in the reaction pathway leading to menthols from citral. The metallic component was selected by testing silica-supported metals for citral hydrogenation to citronellal. Acid site requirements to efficiently isomerize citronellal to isopulegols were investigated on different solid acids. Potential bifunctional metal/acid catalysts were then prepd. and tested for citral conversion to menthols. The best catalyst was Ni/Al-MCM-41, which yielded about 90% menthols and gave 70-75% of racemic (±)-menthol in the menthol mixt.
- 3Vajglová, Z.; Kumar, N.; Peurla, M.; Eränen, K.; Mäki-Arvela, P.; Murzin, D. Yu. Cascade transformations of (±)-citronellal to menthol over extruded Ru-MCM-41 catalysts in a continuous reactor. Catal. Sci. Techn. 2020, 10, 8108– 8119, DOI: 10.1039/D0CY01251CThere is no corresponding record for this reference.
- 4Plößer, J.; Lucas, M.; Claus, P. Highly selective menthol synthesis by one-pot transformation of citronellal using Ru/H-BEA catalysts. J. Catal. 2014, 320, 189– 197, DOI: 10.1016/j.jcat.2014.10.007There is no corresponding record for this reference.
- 5Azkaar, M.; Mäki-Arvela, P.; Vajglová, Z.; Fedorov, V.; Kumar, N.; Hupa, L.; Hemming, J.; Aho, A.; Murzin, D. Yu. Synthesis of menthol from citronellal over supported Ru- and Pt-catalysts in continuous flow. React. Chem. Eng. 2019, 4, 2156– 2169, DOI: 10.1039/C9RE00346K5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitVaksLrE&md5=3e7f32e9b424da8f3d7f5f9c79a2c8ffSynthesis of menthol from citronellal over supported Ru- and Pt-catalysts in continuous flowAzkaar, Muhammad; Maki-Arvela, Paivi; Vajglova, Zuzana; Fedorov, Vyacheslav; Kumar, Narendra; Hupa, Leena; Hemming, Jarl; Peurla, Markus; Aho, Atte; Murzin, Dmitry YuReaction Chemistry & Engineering (2019), 4 (12), 2156-2169CODEN: RCEEBW; ISSN:2058-9883. (Royal Society of Chemistry)One-pot menthol synthesis from citronellal in a trickle bed reactor was investigated using Ru/H-beta-300 zeolite extrudates without any binder and Pt- and Ru-extrudates contg. 70 wt% H-beta-25 zeolites and 30 wt% bentonite binder using different methods of metal loading on the extrudates. The catalytic results were correlated with the physico-chem. properties of bifunctional zeolite-based extrudates. The conversion of citronellal to menthol was nearly the same for Pt extrudates being independent of catalyst acidity or the metal particle size. Ru extrudates also exhibited similar conversion levels as a function of time-onstream, except for very mildly acidic Ru/beta-300 extrudates, which gave much lower conversion. Pt extrudates showed better stability with time on stream in comparison with Ru extrudates. The best catalyst giving the highest menthol yield and a low amt. of acyclic hydrogenation products was Ru-beta-bentonite extrudates where Ru was located randomly in the mixt. of 70% H-beta-25 and 30% bentonite binder. Hydrogenation was more prominent for Pt than for Ru catalysts, most probably due to their higher hydrogenation ability. Stereoselectivity to menthol varied in the trickle bed reactor in the range of 67 to 73%. In a batch reactor for Ru- and Pt-catalysts independent of support acidity, it was in the range of 70-71%. The reuse of Ru/H-beta-300 extrudates was successfully demonstrated.
- 6Balu, A. M.; Campelo, J. M.; Luque, R.; Romero, A. A. One-step microwave-assisted asymmetric cyclisation/hydrogenation of citronellal to menthols using supported nanoparticles on mesoporous materials. Org. Biomol. Chem. 2010, 8, 2845– 2849, DOI: 10.1039/c003600e6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXmvVWktbw%253D&md5=bba1f1128bba182ba3d67e193a9d4f34One-step microwave-assisted asymmetric cyclization/hydrogenation of citronellal to menthols using supported nanoparticles on mesoporous materialsBalu, Alina Mariana; Campelo, Juan Manuel; Luque, Rafael; Romero, Antonio AngelOrganic & Biomolecular Chemistry (2010), 8 (12), 2845-2849CODEN: OBCRAK; ISSN:1477-0520. (Royal Society of Chemistry)The selective conversion of citronellal to menthols, with good diastereoselectivities to (-)-menthol for the case of (+)-citronellal as starting material, can effectively be carried out in a one-step reaction under microwave irradn. catalyzed by supported nanoparticles on mesoporous materials. 2% Pt/Ga-MCM-41 was found to be the optimum catalyst for the reaction, with a quant. conversion of starting material and selectivities above 85% to menthols obtained in short reaction times (typically 15 min). These results constitute the first report of a simple microwave-assisted one-step cyclization/hydrogenation process for the prodn. of menthols.
- 7Mertens, P.; Verpoort, F.; Parvulescu, A. N.; De Vos, D. Pt/H-beta zeolites as productive bifunctional catalysts for the one-step citronellal-to-menthol conversion. J. Catal. 2006, 243, 7– 13, DOI: 10.1016/j.jcat.2006.06.0177https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XptlGhtbc%253D&md5=c1163822db7ae1cfc8caa59fd5b3af79Pt/H-beta zeolites as productive bifunctional catalysts for the one-step citronellal-to-menthol conversionMertens, Pascal; Verpoort, Francis; Parvulescu, Andrei-Nicolae; De Vos, DirkJournal of Catalysis (2006), 243 (1), 7-13CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Ltd.)Pt-loaded H-beta zeolite was identified as a highly active catalyst for the bifunctional transformation of citronellal to menthol, with isopulegol as the intermediate. With a 2 wt% Pt-loaded catalyst, citronellal is fully converted within 12 h, with only 2.5 wt% catalyst with respect to citronellal, and with a citronellal to Pt molar ratio of 2500. 1,4-Dioxane is the best reaction solvent, because it minimizes the unwanted direct hydrogenation of citronellal and promotes its stereoselective cyclization to isopulegol, leading to high menthol yields. The stereoselectivity can be improved moderately by using a Zr-impregnated support and more substantially by performing high-temp. (750 °C) treatment of the calcined and reduced catalyst. This treatment presumably creates extra Lewis acidity on the catalyst and results in 88% stereoselectivity for the desired menthol. Overall, an 85% yield of (-)-menthol was obtained.
- 8da Silva Rocha, K. A.; Robles-Dutenhefner, P. A.; Sousa, E. M. B.; Kozhevnikova, E. F.; Gusevskaya, E. Pd-heteropoly acid as a bifunctional heterogeneous catalyst for one-pot conversion of citronellal to menthol. Appl. Catal. A: Gen. 2007, 317, 171– 174, DOI: 10.1016/j.apcata.2006.10.0198https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXivVKj&md5=baf703fb43d802ef49865f82b8c6d4fdPd-heteropoly acid as a bifunctional heterogeneous catalyst for one-pot conversion of citronellal to mentholDa Silva Rocha, Kelly A.; Robles-Dutenhefner, Patricia A.; Sousa, Edesia M. B.; Kozhevnikova, Elena F.; Kozhevnikov, Ivan V.; Gusevskaya, Elena V.Applied Catalysis, A: General (2007), 317 (2), 171-174CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Pd-H3PW12O40/SiO2 catalyzes the one-pot transformation of (+)-citronellal to menthol via acid-catalyzed cyclization followed by Pd-catalyzed hydrogenation, with 92% yield of menthol at 100% citronellal conversion and 85% stereoselectivity for the desired (-)-menthol.
- 9Milone, C.; Gangemi, C.; Neri, G.; Pistone, A.; Galvagno, S. Selective one step synthesis of (−)-menthol from (+)-citronellal on Ru supported on modified SiO2. Appl. Catal. A: Gen. 2000, 199, 239– 244, DOI: 10.1016/S0926-860X(99)00560-89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXivVCitrw%253D&md5=96ce86ba2b032291b45d961097eb8dbbSelective one step synthesis of (-)-menthol from (+)-citronellal on Ru supported on modified SiO2Milone, C.; Gangemi, C.; Neri, G.; Pistone, A.; Galvagno, S.Applied Catalysis, A: General (2000), 199 (2), 239-244CODEN: ACAGE4; ISSN:0926-860X. (Elsevier Science B.V.)The isomerization of (+)-citronellal (I) has been performed under mild conditions on ZnX2 (X=Cl, Br, NO3) supported on high surface area silica. The influence of the Zn loading, counter anion and temp. of pretreatment of the catalyst on the activity and selectivity to (-)-isopulegol (II) was investigated. The catalytic activity increases with the Zn loading. The selectivity to (-)-isopulegol (II) also increases reaching the max. value (86%) on ZnBr2/SiO2 for a Zn content ≥4.0 mmol/g SiO2 ZnBr2/SiO2 is more active than ZnCl2/SiO2, while the selectivity to (-)isopulegol (II) is similar. Zn(NO3)2/SiO2 is far less active and selective. An increase of the temp. of pretreatment increases the selectivity to (-)-isopulegol (II) . A bifunctional catalyst was formulated, namely Ru-ZnBr2/SiO2, on which the one step hydrogenation of (+)-citronellal (I) to (-)-menthol (III) occurs with a yield >85%.
- 10Adilina, I. B.; Pertiwi, R.; Sulaswatty, A. Conversion of (±) -citronellal and its derivatives to (−) -menthol using bifunctional. Biopropal Industri 2015, 6, 1– 6, DOI: 10.36974/jbi.v6i1.828There is no corresponding record for this reference.
- 11Nie, Y.; Chuah, G. K.; Jaenicke, S. Domino-cyclisation and hydrogenation of citronellal to menthol over bifunctional Ni/Zr-Beta and Zr-beta/Ni-MCM-41 catalysts. Chem. Commun. 2006, 790– 792, DOI: 10.1039/b513430g11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xht1Wkt7g%253D&md5=b62eb896e693802ff9b970fb8fb1da20Domino-cyclisation and hydrogenation of citronellal to menthol over bifunctional Ni/Zr-Beta and Zr-beta/Ni-MCM-41 catalystsNie, Yuntong; Chuah, Gaik-Khuan; Jaenicke, StephanChemical Communications (Cambridge, United Kingdom) (2006), (7), 790-792CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The one-pot conversion of (±)-citronellal to menthol can be selectively catalyzed by either a bifunctional Ni/Zr-zeolite beta catalyst or a dual catalyst system of Zr-beta and Ni/MCM-41, giving a high diastereoselectivity to (±)-menthol of 90-94%.
- 12Cortés, C. B.; Galván, V. T.; Pedro, S. S.; García, T. V. One pot synthesis of menthol from (±)-citronellal on nickel sulfated zirconia catalysts. Catal. Today 2011, 172, 21– 26, DOI: 10.1016/j.cattod.2011.05.00512https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtFSjtbzP&md5=247354d3d4b5304641a0e221a4057396One pot synthesis of menthol from (±)-citronellal on nickel sulfated zirconia catalystsCortes, Cesar Barrales; Galvan, Victoria Tamayo; Pedro, Smid Santiago; Garcia, Tomas ViverosCatalysis Today (2011), 172 (1), 21-26CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)The one-pot synthesis of menthol from (±)-citronellal was carried out using two catalysts: nickel supported on sol-gel sulfated zirconia (Ni/ZrS) and nickel added during the synthesis of sulfated zirconia (NiZrS). The supported catalyst was prepd. by impregnation of nickel on the sulfated zirconia support, whereas NiZrS was prepd. by the co-gellation of nickel and the sulfated zirconia by the sol-gel method. Two sets of catalytic tests were carried out. In both tests the catalysts were previously treated in He stream. First, the liq. phase cyclization of (±)-citronellal was carried out with both ZrS and NiZrS catalysts. The results showed that both ZrS and NiZrS catalysts are highly active and selective towards isopulegols (100% of selectivity) and highly stereoselective towards (±)-isopulegol (∼70% of selectivity). A second reaction test was the synthesis of menthol. The catalysts were evaluated in a batch reactor at 1.4 MPa of H2 and 100 °C. The results showed that the catalysts allow to obtain a high catalytic activity and selectivity towards stereoisomers of menthol (100% selectivity of menthols) and a high selectivity towards (-)-menthol.
- 13Iftitah, E. D.; Muchalal, M.; Trisunaryanti, W.; Armunanto, R.; Psaro, R.; Ravasio, N.; Santoro, F.; Sordelli, L. One pot transformation of citronellal to menthol over Ni/γ-Al2O3. J. Appl. Sci. Res. 2011, 7, 680– 689There is no corresponding record for this reference.
- 14Trasarti, A. F.; Marchi, A. J.; Apesteguía, C. R. Design of catalyst systems for the one-pot synthesis of menthols from citral. J. Catal. 2007, 247 (2), 155– 165, DOI: 10.1016/j.jcat.2007.01.01614https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXjvVagu70%253D&md5=ce7aca1078b839d734478b4ceb132678Design of catalyst systems for the one-pot synthesis of menthols from citralTrasarti, A. F.; Marchi, A. J.; Apesteguia, C. R.Journal of Catalysis (2007), 247 (2), 155-165CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Ltd.)Stable, active, and highly selective bifunctional Ni/Al-MCM-41 catalysts were developed for the one-pot synthesis of menthols from citral. The liq.-phase hydrogenation of citral to citronellal was studied on silica-supported noble (Pt, Pd, Ir) and nonnoble (Ni, Co, Cu) metals. It was found that citronellal is selectively formed at the beginning of the reaction only on Pd and Ni catalysts. The consecutive ene-cyclization of citronellal to isopulegols was investigated on solid acids contg. exclusively Lewis (ZnO/SiO2) or strong Broensted (CsHPA) acid sites, and also on catalysts contg. both Lewis and Broensted acid sites of either strong (zeolites, SiO2-Al2O3) or moderate (Al-MCM-41) strength. The isopulegol formation rate was higher on samples exhibiting dual Lewis/Broensted acidity, such as SiO2-Al2O3, Al-MCM-41, and zeolite HBEA. Based on these previous results, bifunctional catalysts contg. Pd or Ni supported on SiO2-Al2O3, Al-MCM-41, or zeolite HBEA were prepd. and tested for citral conversion to menthols. The catalyst stability and the effect of hydrogen pressure and metal loading on menthol productivity were also investigated. The best catalyst was Ni(8%)/Al-MCM-41, which yielded more than 90% menthols at 2026.0 kPa and showed no significant deactivation after two consecutive catalytic tests.
- 15Nie, Y.; Jaenicke, S.; Chuah, G. K. Zr-zeolite beta: A new heterogeneous catalyst system for the highly selective cascade transformation of citral to (±)-menthol. Chem.─Eur. J. 2009, 15 (8), 1991– 1999, DOI: 10.1002/chem.20080177615https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXit1Wjurg%253D&md5=c12cd711c78260f6e370bf95012cde29Zr-zeolite beta: a new heterogeneous catalyst system for the highly selective cascade transformation of citral to (±)-mentholNie, Yuntong; Jaenicke, Stephan; Chuah, Gaik-KhuanChemistry - A European Journal (2009), 15 (8), 1991-1999CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The transformation of citral to menthols involves hydrogenation steps as well as cyclization of the intermediate, citronellal. The ability of Zr-zeolite beta to catalyze the cyclization with high diastereoselectivity to (±)-isopulegol is the crit. step in this cascade transformation. Bifunctional catalysts contg. nickel or rhodium supported on Zr-zeolite beta gave menthols in yields of 87-89% and an excellent diastereoselectivity of 94% for the desired (±)-menthol. Dual catalyst systems of Zr-zeolite beta and nano-dispersed Ni on an MCM-41 support were equally effective and have the added advantage that the rates of the acid and hydrogenation-catalyzed steps can be independently varied. By applying a pressure ramp of 0.2-2 MPa, the yield of menthols could be increased to 95%, with 94% diastereoselectivity for (±)-menthol. The low initial pressure minimizes the rates of competing hydrogenation reactions to byproducts such as citronellol and 3,7-dimethyloctanol.
- 16Mäki-Arvela, P.; Kumar, N.; Kubička, D.; Nasir, A.; Heikkilä, T.; Lehto, V. P.; Sjöholm, R.; Salmi, T.; Murzin, D. Y. One-pot citral transformation to menthol over bifunctional micro-and mesoporous metal modified catalysts: Effect of catalyst support and metal. J. Mol. Catal. A: Chem. 2005, 240 (1–2), 72– 81, DOI: 10.1016/j.molcata.2005.06.023There is no corresponding record for this reference.
- 17Vajglová, Z.; Navas, M.; Mäki-Arvela, P.; Eränen, K.; Kumar, N.; Peurla, M.; Murzin, D. Y. Transformations of citral over bifunctional Ru-HY-80 extrudates in a continuous reactor. Chem. Eng. J. 2022, 429, 132190, DOI: 10.1016/j.cej.2021.13219017https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitVSrsrnN&md5=4a7daa1b87863c4186ec7bc887eb550cTransformations of citral over bifunctional Ru-H-Y-80 extrudates in a continuous reactorVajglova, Zuzana; Navas, Marisa; Maki-Arvela, Paivi; Eranen, Kari; Kumar, Narendra; Peurla, Markus; Murzin, Dmitry Yu.Chemical Engineering Journal (Amsterdam, Netherlands) (2022), 429 (), 132190CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)One-pot transformations of citral were investigated over Ru-catalysts in a batch and a continuous mode over a powder catalyst and extrudates, resp. Ru/H-Y-80 catalysts were prepd. by different impregnation methods to obtain different particle sizes of Ru. The highest yield of isopulegols was 15% and yield of menthols was 3% with stereoselectivity to the desired (±)-menthol isomer of 42% after 5 h over the Ru/H-Y-80 powder catalyst with the smallest metal particles prepd. by the incipient wetness impregnation method with six impregnation steps using Ru(NO)(NO3)3 as a precursor. This catalyst was synthesized with the Bindzil binder and shaped by extrusion. For comparison, also a catalyst with Ru deposited on the binder was prepd. Addn. of 30 wt% Bindzil binder to Ru/H-Y-80 catalyst caused significant catalyst deactivation. Z/E-citral ratio decreased with increasing Ru particle size. Citral conversion and the yield of acyclic hydrogenation products were higher over the powder catalysts contg. a mixt. of zeolite and binder with a larger distance between the metal and the acid sites, i.e. with Ru deposited on the Bindzil binder. Long-term expts. in the continuous mode revealed comparable catalytic behavior of both Ru-extrudates with the controlled metal location due to the presence of diffusion regime. The max. yield of menthols, 6%, with stereoselectivity to the desired (±)-menthol of 73% was obtained during the transient state, below 2 h of time-onstream. The reuse of Ru/H-Y-80 extrudates was successfully demonstrated.
- 18Vajglová, Z.; Mäki-Arvela, P.; Eränen, K.; Kumar, N.; Peurla, M.; Murzin, D. Y. Catalytic transformations of citral in a continuous flow over bifunctional Ru-MCM-41 extrudates. Catal. Sci. Techn. 2021, 11 (8), 2873– 2884, DOI: 10.1039/D1CY00066GThere is no corresponding record for this reference.
- 19Negoi, A.; Teinz, K.; Kemnitz, E.; Wuttke, S.; Parvulescu, V. L.; Coman, S. M. Bifunctional nanoscopic catalysts for the one-pot synthesis of (±)-menthol from citral. Top. Catal. 2012, 55 (7), 680– 687, DOI: 10.1007/s11244-012-9850-y19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XovVGqu7g%253D&md5=3c5be7393454df35c89c1a79ef6ebbe9Bifunctional Nanoscopic Catalysts for the One-Pot Synthesis of (±)-Menthol from CitralNegoi, Alina; Teinz, Katharina; Kemnitz, Erhard; Wuttke, Stefan; Parvulescu, Vasile I.; Coman, Simona M.Topics in Catalysis (2012), 55 (7-10), 680-687CODEN: TOCAFI; ISSN:1022-5528. (Springer)Active and selective bifunctional Me(Ir, Pd)/beta zeolite and doped nanoscopic hydroxylated fluorides (0.1 % Pd (or Pt)/AlF3) catalysts were developed for the one-pot synthesis of menthols from citral. In the case of fluoride catalysts, the strong electron-withdrawing effect of the dominating fluoride environment depletes the metal surface from electrons and hence, favors the hydrogenation of the C=C bond to citronellal on both Pd and Pt-based catalysts.
- 20Simakova, I.; Mäki-Arvela, P.; Martínez-Klimov, M.; Muller, J.; Vajglová, Z.; Peurla, M.; Eränen, K.; Murzin, D. Yu. Continuous synthesis of menthol from citronellal and citral over Ni-Beta-zeolite-sepiolite composite catalyst. Appl. Catal. A: Gen. 2022, 636, 118586, DOI: 10.1016/j.apcata.2022.11858620https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XotlGht70%253D&md5=2c9f40e926b54f4f51dff784e298a3e4Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalystSimakova, Irina; Maki-Arvela, Paivi; Martinez-Klimov, Mark; Muller, Joseph; Vajglova, Zuzana; Peurla, Markus; Eranen, Kari; Murzin, Dmitry Yu.Applied Catalysis, A: General (2022), 636 (), 118586CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60-70°C under 10-29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71-76% and 72-74% were obtained from citronellal and citral resp. at the contact time 4.2 min, 70°C and 20 bar. Citral conversion noticeably decreased with time-onstream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amt. of defunctionalization products obsd. during citral conversion, esp. at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepd. by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chem. and catalytic properties.
- 21Simakova, I. L.; Vajglová, Z.; Mäki-Arvela, P.; Eränen, K.; Hupa, L.; Peurla, M.; Mäkilä, E. M.; Wärnå, J.; Murzin, D. Yu. Citral-to-menthol transformations in a continuous reactor over Ni/mesoporous aluminosilicate extrudates containing a sepiolite clay binder. Org. Proc. Res. 2022, 26, 387– 403, DOI: 10.1021/acs.oprd.1c0043521https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVGjs7k%253D&md5=69dec8359b202dab2bbdc0c04e68079eCitral-to-Menthol Transformations in a Continuous Reactor over Ni/Mesoporous Aluminosilicate Extrudates Containing a Sepiolite Clay BinderSimakova, Irina L.; Vajglova, Zuzana; Maki-Arvela, Paivi; Eranen, Kari; Hupa, Leena; Peurla, Markus; Makila, Ermei M.; Warna, Johan; Murzin, Dmitry Yu.Organic Process Research & Development (2022), 26 (2), 387-403CODEN: OPRDFK; ISSN:1083-6160. (American Chemical Society)One-pot continuous synthesis of menthols from citral was performed over 5 wt % Ni supported on a mesoporous aluminosilicate catalyst with sepiolite as a binder at 70°C with a selectivity of 75% to menthols. Catalyst deactivation with time-onstream resulted in a decrease of the conversion and selectivity to menthol at the expense of higher selectivity to isopulegols. Stereoselectivity to isopulegols and menthols only slightly changed with conversion and TOS. A kinetic model capable of describing exptl. data for transformations of citral to menthol in a continuous mode was developed. It was based on a detailed reaction network and also comprised deactivation on both metal and acid sites. Numerical data fitting confirmed a good correspondence between the exptl. data and calcns.
- 22Nefzi, H.; Abderrabba, M.; Ayadi, S.; Labidi, J. Formation of palygorskite clay from treated diatomite and its application for the removal of heavy metals from aqueous solution. Water 2018, 10 (9), 1257, DOI: 10.3390/w1009125722https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVKjtr3E&md5=e2526514a5b61cc603df69798c10165bFormation of palygorskite clay from treated diatomite and its application for the removal of heavy metals from aqueous solutionNefzi, Houwaida; Abderrabba, Manef; Ayadi, Sameh; Labidi, JalelWater (Basel, Switzerland) (2018), 10 (9), 1257/1-1257/15CODEN: WATEGH; ISSN:2073-4441. (MDPI AG)Environmental contamination by toxic heavy metals is a serious worldwide phenomenon. Thus, their removal is a crucial issue. In this study, we found an efficient adsorbent to remove Cu2+ and Ni2+ from aq. soln. using two materials. Chem. modification was used to obtain palygorskite clay from diatomite. The adsorbents were characterized using X-ray florescence, Fourier transform IR spectroscopy and X-ray diffraction. The effects of contact time, initial concn., temp. and pH on the adsorption process were investigated. Our results showed that the (%) of max. adsorption capacity of diatomite was 78.44% for Cu2+ at pH 4 and 77.3% for Ni2+ at pH 7, while the (%) of the max. adsorption on palygorskite reached 91% for Cu2+ and 87.05% for Ni2+, in the same condition. The results indicate that the pseudo-second-order model can describe the adsorption process. Furthermore, the adsorption isotherms could be adopted by the Langmuir and the Freundlich models with good correlation coeff. (R2). Thus, our results showed that palygorskite prepd. from Tunisian diatomite is a good adsorbent for the removal of heavy metals from water.
- 23Xie, A.; Zhou, X.; Huang, X.; Ji, L.; Zhou, W.; Luo, S.; Yao, C. Cerium-loaded MnOx/attapulgite catalyst for the low-temperature NH3-selective catalytic reduction. J. Ind. Eng. Chem. 2017, 49, 230– 241, DOI: 10.1016/j.jiec.2017.01.03423https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXitlOjsL8%253D&md5=4e842290402d46dc938b8a42e4ec6d70Cerium-loaded MnOx/attapulgite catalyst for the low-temperature NH3-selective catalytic reductionXie, Aijuan; Zhou, Xingmeng; Huang, Xiaoyan; Ji, Liang; Zhou, Wenting; Luo, Shiping; Yao, ChaoJournal of Industrial and Engineering Chemistry (Amsterdam, Netherlands) (2017), 49 (), 230-241CODEN: JIECFI; ISSN:1226-086X. (Elsevier B.V.)A series of MnO2/attapulgite (ATP) and n(Ce):n(Mn)/ATP (molar ratios) catalysts were prepd. and investigated for the selective catalytic redn. of NO by NH3 (NH3-SCR) at low temp. The results showed that the 7 wt % MnO2/ATP exhibited the best NOx conversion (85% at 300°C) among all MnO2/ATP catalysts of different mass ratios. The introduction of cerium enhanced the NOx conversion at low temp., and so Ce-MnOx/ATP can reach the highest NOx conversion (95% at 300°C). Meanwhile, the as-prepd. catalysts were characterized by XRD, TEM, BET, H2-TPR, NH3-TPD, and XPS. It can be deduced from TEM, XRD, and BET, MnOx nanorods in this work mainly existed in the β-MnO2, and cerium highly dispersed on the surface of ATP to form porous structure and thus improved the deNOx performance. Moreover, the study of SO2 tolerance demonstrated that cerium can effectively inhibit SO2 poison. XPS results illustrated that Ce could enhance Mn4+ content on the surface of the catalyst and thus lead to high SCR activity. Therefore Mn(1):Ce(0.25)/ATP was proved to be an excellent catalyst for NH3-SCR.
- 24Guo, S.; Shi, L. Synthesis of succinic anhydride from maleic anhydride on Ni/diatomite catalysts. Catal. Today 2013, 212, 137– 141, DOI: 10.1016/j.cattod.2012.10.00424https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs1Gkt7bL&md5=1ef4f6585eaeea664aecfa773b953881Synthesis of succinic anhydride from maleic anhydride on Ni/diatomite catalystsGuo, Shaofei; Shi, LiCatalysis Today (2013), 212 (), 137-141CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)The characteristics and catalytic properties of Ni(5%)/diatomite, Ni(5%)/γ-Al2O3, Ni(5% wt)/Bentonite clay and Ni(5%)/attapulgite clay were investigated and compared in terms of catalytic activities for liq.-phase hydrogenation of maleic anhydride (MA). The results showed that the diatomite support exhibited the highest activity and selectivity. Using Ni(7%)/diatomite catalyst, the 100% conversion of MA and 96.20% selectivity to SA were obtained for MA hydrogenation at 190°. The x-ray diffraction (x-ray diffraction) studies showed that there is only NiO on the support and no elemental nickel (Ni0) and Ni2O3 was detected in unreduced samples. X-ray diffraction and H2 temp.-programmed redn. (TPR) studies also showed that NiO species were all converted to metallic nickel (Ni0) after redn. at 350°.
- 25Anderson, J. A.; Rodrigo, M. T.; Daza, L.; Mendioroz, S. Influence of the support in the selectivity of nickel/clay catalysts for vegetable oil hydrogenation. Langmuir 1993, 9 (10), 2485– 2490, DOI: 10.1021/la00034a00125https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXmtVaisLc%253D&md5=c5e1a0dbbbd5823b9795d9ca6e4b6499Influence of the support in the selectivity of nickel/clay catalysts for vegetable oil hydrogenationAnderson, J. A.; Rodrigo, M. T.; Daza, L.; Mendioroz, S.Langmuir (1993), 9 (10), 2485-90CODEN: LANGD5; ISSN:0743-7463.Two naturally occurring clays of Spanish origin, bentonite and palygorskite, have been used as support material for nickel hydrogenation catalysts in which the active phase has been deposited by means of the pptn. method. The structural and textural characteristics of the supports have been studied by XRD, N2 adsorption/desorption, and mercury porosimetry and the acid sites detd. by thermogravimetry and IR studies of adsorbed pyridine. The Ni phases present were characterized by XRD, TEM, XPS, FTIR of adsorbed CO, and the degree of redn. detd. thermogravimetrically. XRD and TEM indicate Ni particle size to be equiv. for both supports although the detection by FTIR of a high proportion of bridging CO for the bentonite support suggests the presence of addn. small particles for this support which may be located between lamellae. These smaller particles are consistent with the more difficult redn. of Ni in this support. Although activity for the hydrogenation of sunflower oil was similar for both catalysts, significant differences regarding the selectivity have been obsd. which may be attributed to the differences in morphol. of the support materials. Mass transport limitations resulting from reaction of linoleic acid at Ni sites between lamellae of bentonite leads to consecutive hydrogenation through to stearic acid, whereas the palygorskite supported catalyst remained highly selective to oleic acid even at high conversion levels.
- 26Zecevic, J.; Vanbutsele, G.; de Jong, K. P.; Martens, J. A. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons. Nature 2015, 528 (7581), 245– 248, DOI: 10.1038/nature1617326https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitVSiu7zL&md5=ac34c2f671e3ded4954c9c6e1fea783aNanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbonsZecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.Nature (London, United Kingdom) (2015), 528 (7581), 245-248CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for >50 years the so-called intimacy criterion has dictated the max. distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometer precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as the closer the better for positioning metal and acid sites. Here the authors show for a bifunctional catalyst-comprising an intimate mixt. of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder-that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock mols. for high-quality diesel prodn. is optimized with the catalyst that contains platinum on the binder, i.e., with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon mols. that are typically derived from alternative sources, such as gas-to-liq. technol., vegetable oil or algal oil, should benefit esp. from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, the authors anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.
- 27Harmel, J.; Roberts, T.; Zhang, Z.; Sunley, G.; de Jongh, P.; de Jong, K. P. Bifunctional molybdenum oxide/acid catalysts for hydroisomerization of n-heptane. J. Catal. 2020, 390, 161– 169, DOI: 10.1016/j.jcat.2020.08.00427https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhs1yksrbP&md5=928b563a0fdadf9d85c47b2907c4331eBifunctional molybdenum oxide/acid catalysts for hydroisomerization of n-heptaneHarmel, Justine; Roberts, Tegan; Zhang, Zhaorong; Sunley, Glenn; de Jongh, Petra; de Jong, Krijn P.Journal of Catalysis (2020), 390 (), 161-169CODEN: JCTLA5; ISSN:0021-9517. (Elsevier Inc.)Numerus research studies focus on replacing scarce noble metals by nonnoble transition metals in solid catalysts. The (de)hydrogenation function in bifunctional catalysts for hydroisomerization and hydrocracking of alkanes is usually performed by a precious metal such as Pt, or a metal sulfide such as MoS2. The authors studied the possibility of replacing Pt with a nonsulfided MoOx catalyst in combination with a mesoporous solid acid for the hydroisomerization of n-heptane. MoOx particles size as well as the prepn. techniques were varied to identify the Mo active phase for (de)hydrogenation. An optimized nonprecious metal MoOx catalyst can perform similarly to its Pt counterpart in the n-heptane conversion when used in combination with a mesoporous solid acid.
- 28Vajglová, Z.; Kumar, N.; Peurla, M.; Hupa, L.; Semikin, K.; Sladkovskiy, D. A.; Murzin, D. Yu. Effect of the preparation of Pt-modified zeolite beta-bentonite extrudates on their catalytic behavior in n-hexane hydroisomerization. Ind. Eng. Chem. Res. 2019, 58 (25), 10875– 10885, DOI: 10.1021/acs.iecr.9b0193128https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtVygsLjF&md5=64efd204ca488a536c3d5dacba0ceab2Effect of the Preparation of Pt-Modified Zeolite Beta-Bentonite Extrudates on Their Catalytic Behavior in n-Hexane HydroisomerizationVajglova, Zuzana; Kumar, Narendra; Peurla, Markus; Hupa, Leena; Semikin, Kirill; Sladkovskiy, Dmitry A.; Murzin, Dmitry Yu.Industrial & Engineering Chemistry Research (2019), 58 (25), 10875-10885CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Four different types of shaped catalysts with controlled deposition of Pt and the same compn. were prepd. by extrusion of beta zeolite agglomerated with bentonite as an aluminosilicate clay binder. The catalysts were characterized using mech. strength tests; SEM for morphol.; TEM for porosity and periodicity; N physisorption for surface area, pore vol., and pore size distribution; and FTIR spectroscopy using pyridine as a probe mol. to elucidate the presence, strength, and amt. of Broensted and Lewis acid sites. Elemental anal. was carried out using energy-dispersive x-ray microanal. Activity and selectivity of catalysts in the isomerization of n-hexane were evaluated using a fixed bed reactor at 200-350°. At low temp., the performance of metal/acid bifunctional shaped catalysis was strongly affected by the metal-to-acid site ratio. This ratio and the total acidity were strongly influenced by the prepn. method of the shaped catalysts, while the textural properties were comparable. The highest conversion of n-hexane and selectivity to C6 isomers (comprising all branched isomers, such as Me pentane and dimethylbutane) was obtained with extrudates prepd. via in situ synthesis with Pt located on the zeolite. The extrudates prepd. in this way have the highest metal-to-acid site ratio and their closest proximity, albeit the lowest mech. strength.
- 29Vajglová, Z.; Simakova, I. L.; Eränen, K.; Mäki-Arvela, P.; Kumar, N.; Peurla, M.; Tolvanen, S.; Efimov, A.; Hupa, L.; Peltonen, J.; Murzin, D. Yu. The physicochemical and catalytic properties of clay extrudates in cyclization of citronellal. Appl. Catal. A: Gen. 2022, 629, 118426, DOI: 10.1016/j.apcata.2021.11842629https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisFWhtrjO&md5=bce879bef3ddafefe2961eb1490accb0The physicochemical and catalytic properties of clay extrudates in cyclization of citronellalVajglova, Zuzana; Simakova, Irina L.; Eranen, Kari; Maki-Arvela, Paivi; Kumar, Narendra; Peurla, Markus; Tolvanen, Stiina; Efimov, Alexander; Hupa, Leena; Peltonen, Jouko; Murzin, Dmitry Yu.Applied Catalysis, A: General (2022), 629 (), 118426CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Four clay materials, namely, bentonite, bleaching earth, attapulgite and sepiolite, were shaped into the cylindrical body by extrusion. Clays were characterized in depth by TEM, SEM-EDX, N2 physisorption, pyridine FTIR, pH measurements, contact angle measurements, 27Al MAS NMR, and the crush test. Catalytic properties were investigated in the citronellal cyclization as a model reaction. The reaction was performed in the trickle-bed reactor at 70°C, 10 bar of Ar with 0.086 M initial citronellal concn. in cyclohexane. The best results were obtained over attapulgite with isopulegols yield of 24% and stereoselectivity to the desired isopulegol isomer of 61%. Attapulgite had the highest meso-to-micropore vol. ratio, the highest basicity, a low Bronsted-to-Lewis acid sites ratio, and the lowest amt. of Bronsted acid sites compared to other extrudates. In addn., same clay exhibited the highest mech. strength of extrudates.
- 30Emeis, C. A. Determination of integrated molar extinction coefficients for infrared absorption bands of pyridine adsorbed on solid acid catalysts. J. Catal. 1993, 141, 347– 354, DOI: 10.1006/jcat.1993.114530https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3sXltVCisLs%253D&md5=ba711e5e8cb157ce77e04900e6fb0e35Determination of integrated molar extinction coefficients for infrared absorption bands of pyridine adsorbed on solid acid catalystsEmeis, C. A.Journal of Catalysis (1993), 141 (2), 347-54CODEN: JCTLA5; ISSN:0021-9517.Integrated molar extinction coeffs. were detd. for IR absorption bands of pyridine adsorbed on acid sites in Si/Al-based catalysts. The IR spectra of five zeolites and two amorphous silica-aluminas were recorded during quant. dosing of pyridine gas at 150°. The integrated mol. extinction coeffs. were calcd. assuming that they did not depend on the catalyst or the strength of the acid site. The resulting values were 1.67 cm/μmol for the 1545-cm-1 band characteristic of pyridine on a Broensted acid site and 2.22 cm/μmol for the 1455-cm-1 band of pyridine on a Lewis acid site. The 95% confidence limits were estd. at ±15%. Subsequent anal. of the data provided no evidence for a dependence of the integrated coeffs. on the catalyst or the strength of the site. The measurements gave indications for differences between the rates of reaction of Broensted and Lewis acid sites with pyridine.
- 31Powder Diffraction File database PDF-2; International Centre for Diffraction Data: USA, 2009.There is no corresponding record for this reference.
- 32Vajglova, Z.; Kumar, N.; Mäki-Arvela, P.; Eränen, K.; Peurla, M.; Hupa, L.; Nurmi, M.; Toivakka, M.; Murzin, D. Y. Synthesis and physicochemical characterization of shaped catalysts of β and Y zeolites for cyclization of citronellal. Ind. Eng. Chem. Res. 2019, 58 (39), 18084– 18096, DOI: 10.1021/acs.iecr.9b0282932https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhslWgtr7N&md5=15a472044778cc132d263682710f8d94Synthesis and Physicochemical Characterization of Shaped Catalysts of β and Y Zeolites for Cyclization of CitronellalVajglova, Zuzana; Kumar, Narendra; Maki-Arvela, Paivi; Eranen, Kari; Peurla, Markus; Hupa, Leena; Nurmi, Maristiina; Toivakka, Martti; Murzin, Dmitry YuIndustrial & Engineering Chemistry Research (2019), 58 (39), 18084-18096CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Continuous cyclization of citronellal over zeolite-based extrudates was performed in a trickle-bed reactor at 35-70 °C and 10 bar of argon. Catalytic results were correlated with the physicochem. properties of the shaped catalyst prepd. by extrusion of β or Y zeolites with binders. Rheol. tests were used to elucidate the flow properties of a catalytic slurry and relate them with the extrusion performance. This study revealed that application of methylcellulose and bentonite binder modified the textural and acidic properties of the final extrudates. The main product was (-)-isopulegol at all temps. with selectivity remaining quite const. with time-onstream. The results illustrated that a binder such as bentonite cannot be considered inert. The mass-transfer limitations obsd. in extrudates did not significantly influence selectivity to the desired pulegols. This study also showed that a direct transfer of the batch reactor data to industrial continuous operation in citronellal cyclization is not straightforward.
- 33Boudriche, L.; Chamayou, A.; Calvet, R.; Hamdi, B.; Balard, H. Influence of different dry milling processes on the properties of an attapulgite clay, contribution of inverse gas chromatography. Powder technology 2014, 254, 352– 363, DOI: 10.1016/j.powtec.2014.01.04133https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjtFSks7k%253D&md5=e9be15d6f44e9de2ae3b194fb49063a7Influence of different dry milling processes on the properties of attapulgitic clay, contribution of inverse gas chromatographyBoudriche, L.; Chamayou, A.; Calvet, R.; Hamdi, B.; Balard, H.Powder Technology (2014), 254 (), 352-363CODEN: POTEBX; ISSN:0032-5910. (Elsevier B.V.)The effect of dry milling processes on the surface properties of an attapulgitic clay, also called palygorskite, was investigated by carrying out expts. with different types of grinding devices. Ground products were then characterized by size measurement, SEM, X-ray diffraction, adsorption-desorption of N2 and inverse gas chromatog. at infinite diln. (IGC-ID) as well as finite concn. conditions (IGC-FC). These analyses were performed to evaluate the changes in particle size distribution, morphol., crystallinity and surface properties of attapulgite powder, resp. Among the tested dry grinding devices, grinding in an air jet mill (Alpine 50 AS) and a vibratory ball mill (Pulverisette 0) led to the most significant particle size redn. SEM photomicrographs showed that a breakage of the fibrous structure took place during dry grinding. Moreover, long grinding in Pulverisette 0 resulted in the complete destruction of fiber morphol. followed by agglomeration. XRD anal. showed that whatever the grinding process, the microstructure of the attapulgite was not affected. IGC confirmed that only grinding in Pulverisette 0 affected the surface properties notably. In this case, the most significant decreases were obsd. in the dispersive component of the surface energy (164 to 116 mJ/m2) and in the sp. surface area obtained with the octane probe (114.5 m2/g to 62.6 m2/g) by IGC-ID and IGC-FC, resp. At the same time, a modification of the distribution functions of the adsorption energies (DFAE), giving information about surface heterogeneity, was noticed.
- 34Nugraha, R. E.; Prasetyoko, D.; Bahruji, H.; Suprapto, S.; Asikin-Mijan, N.; Oetami, T. P.; Dai-Veit, N. Vo.; Taufiq-Yap, Y. H. Lewis acid Ni/Al-MCM-41 catalysts for H2-free deoxygenation of Reutealis trisperma oil to biofuels. RSC Adv. 2021, 11 (36), 21885– 21896, DOI: 10.1039/D1RA03145G34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtlKju7zI&md5=0615397f1c1f80c90ef4bed34b5c8ac7Lewis acid Ni/Al-MCM-41 catalysts for H2-free deoxygenation of Reutealis trisperma oil to biofuelsNugraha, Reva Edra; Prasetyoko, Didik; Bahruji, Hasliza; Suprapto, Suprapto; Asikin-Mijan, Nurul; Oetami, Titie Prapti; Jalil, Aishah Abdul; Vo, Dai-Viet N.; Taufiq-Yap, Yun HinRSC Advances (2021), 11 (36), 21885-21896CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)The activity of mesoporous Al-MCM-41 for deoxygenation of Reutealis trisperma oil (RTO) was enhanced via modification with NiO nanoparticles. Deoxygenation at atm. pressure and under H2 free conditions required acid catalysts to ensure the removal of the oxygenated fragments in triglycerides to form liq. hydrocarbons. NiO at different wt. loadings was impregnated onto Al-MCM-41 and the changes of Lewis/Bronsted acidity and mesoporosity of the catalysts were investigated. The activity of Al-MCM-41 was enhanced when impregnated with NiO due to the increase of Lewis acidity originating from NiO nanoparticles and the mesoporosity of Al-MCM-41. Increasing the NiO loading enhanced the Lewis acidity but not Bronsted acidity, leading to a higher conversion toward liq. hydrocarbon yield. Impregnation with 10% of NiO on Al-MCM-41 increased the conversion of RTO to hydrocarbons via the deoxygenation pathway and reduced the products from cracking reaction, consequently enhancing the green diesel (C11-C18) hydrocarbon products.
- 35Yang, L.; Huang, J.; Cen, J.; Chen, D. L.; Zeng, H.; Rui, Z.; Luque, R.; Duan, P. Lewis acid (Ni 2+, Co 2+/3+ or Zn 2+) modified electron-deficient Ir 4+ in IrO 2/CuO for promoting methane oxidation to ethanol and methanol. J. Mater. Chem. A 2021, 9 (11), 7094– 7101, DOI: 10.1039/D0TA10842A35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjtlClt7k%253D&md5=b8a1e7fe817b1c2100649008282beb87Lewis acid (Ni2+, Co2+/3+ or Zn2+) modified electron-deficient Ir4+ in IrO2/CuO for promoting methane oxidation to ethanol and methanolYang, Le; Huang, Jinxu; Cen, Jie; Chen, De-Li; Zeng, Hui; Rui, Zebao; Luque, Rafael; Duan, PeigaoJournal of Materials Chemistry A: Materials for Energy and Sustainability (2021), 9 (11), 7094-7101CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)This work delineates the first attempt to tune the product distribution between methanol and ethanol in the direct oxidn. of methane reaction by incorporating Lewis acids Ni2+, Co2+/3+ or Zn2+ into IrO2/CuO. The electrophilicity of Ir4+ and the (LAS-BAS)/LAS ratio (LAS: Lewis acid sites, BAS: Bronsted acid sites) are demonstrated to be two reactivity descriptors motivating CH4 activation and ethanol formation, resp. Electron-deficient Ir4+ motivates enriched *CH3 concn. and subsequent C-C coupling for C2H4 formation, while the Lewis acid promotes ethanol formation from C2H4 involving lattice O and H2O. The ethanol selectivity presents a quasi-linear relationship with (LAS-BAS)/LAS.
- 36Wei, Z.; Xia, T.; Ma, J.; Feng, W.; Dai, J.; Wang, Q.; Yan, P. Investigation of the lattice expansion for Ni nanoparticles. Mater. Charact. 2007, 58 (10), 1019– 1024, DOI: 10.1016/j.matchar.2006.08.00436https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpsl2ju7w%253D&md5=ff5df38b8346b66450c35ce67b090c98Investigation of the lattice expansion for Ni nanoparticlesWei, Zhiqiang; Xia, Tiandong; Ma, Jun; Feng, Wangjun; Dai, Jianfeng; Wang, Qing; Yan, PengxunMaterials Characterization (2007), 58 (10), 1019-1024CODEN: MACHEX; ISSN:1044-5803. (Elsevier B.V.)Nickel nanoparticles with various grain sizes were successfully prepd. by anodic arc discharge plasma method. The samples prepd. by this method were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the corresponding selected-area electron diffraction (SAED) to det. the crystal structure, lattice parameter, morphol. and particle size. The expt. results indicate that the crystal structure of the samples is fcc. structure as same as the bulk materials. The lattice parameters for Ni nanoparticles are always larger than the equil. values of the perfect single crystal lattice resp., the lattice parameter increase significantly with the decrease of the grain size, the lattice expansion was found, and the expansion quantity of the lattice parameter is in direct proportion to the reciprocal of grain size. The values of the unit cell vol. increase remarkably with the decrease of the grain size. The lattice expansion is the result of the interfacial energy and surface tension mutual attraction of Ni nanoparticles, this phenomenon can be explained according to the thermodn. theory.
- 37Quindimil, A.; De-La-Torre, U.; Pereda-Ayo, B.; Gonzalez-Marcos, J. A.; Gonzalez-Velasco, J. R. Ni catalysts with La as promoter supported over Y-and Beta-zeolites for CO2 methanation. Appl. Catal. B: Env. 2018, 238, 393– 403, DOI: 10.1016/j.apcatb.2018.07.03437https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtlOgs77F&md5=7bf1190b202c9aa6a53abb1d315231ceNi catalysts with La as promoter supported over Y- and BETA- zeolites for CO2 methanationQuindimil, Adrian; De-La-Torre, Unai; Pereda-Ayo, Benat; Gonzalez-Marcos, Jose A.; Gonzalez-Velasco, Juan R.Applied Catalysis, B: Environmental (2018), 238 (), 393-403CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)The hydrogenation of CO2 into methane is considered a plausible process to storage renewable energy in form of methane and reducing CO2 anthropogenic emissions. Microporous solids such as zeolites have been scarcely studied yet for this application. This study aims to evaluate and compare the catalytic performance of zeolite (Y and BETA) supported Ni catalysts for CO2 methanation. The physicochem. properties of the prepd. catalysts were characterized by XRD, BET, CO2-TPD, H2-TPR and XPS, and CO2 methanation was carried out in a tubular reactor at conditions of H2/CO2 = 4, GHSV = 10,000 h-1 and temps. from 200 to 500 C. Neutralization of both zeolites by Na+ ion exchange enhanced the CO2 conversion as weaker CO2 adsorption sites and reducibility are promoted. BETA resulted in a better support than Y zeolite due to the presence of more easily reducible Ni2+, which acts as precursor of active Ni° accessible under reaction conditions. Indeed, the surface basicity and Ni dispersion of Ni/BETA catalysts were considerably promoted by impregnation of different loads of La2O3, which increase the amt. of CO2 adsorption sites and even active hydrogenation sites resulting in a significant increase of activity and selectivity towards CH4. The optimal Ni-10%La2O3/Na-BETA formulation resulted in T50 of 320°C, CO2 conversion of 65% at 350 °C, with almost total selectivity to CH4 and maintaining stability for more than 24 h.
- 38Wang, Y.; Liang, D.; Wang, C.; Chen, M.; Tang, Z.; Hu, J.; Yang, Z.; Zhang, H.; Wang, J.; Liu, S. Influence of calcination temperature of Ni/attapulgite on hydrogen production by steam reforming ethanol. Renew. Energy 2020, 160, 597– 611, DOI: 10.1016/j.renene.2020.06.12640https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVOrtb7I&md5=88e36188daabb99f88dfa206c7f247f6Influence of calcination temperature of Ni/Attapulgite on hydrogen production by steam reforming ethanolWang, Yishuang; Liang, Defang; Wang, Chunsheng; Chen, Mingqiang; Tang, Zhiyuan; Hu, Jiaxin; Yang, Zhonglian; Zhang, Han; Wang, Jun; Liu, ShaominRenewable Energy (2020), 160 (), 597-611CODEN: RNENE3; ISSN:0960-1481. (Elsevier Ltd.)Sustainable hydrogen prodn. can be realized by steam reforming ethanol (SRE) derived from renewable biomass, but develop high-efficiency and sixpenny catalyst is a major challenge. Attapulgite-supported nickel catalyst (Ni/ATP) exhibits promising potential for SRE for hydrogen prodn. The influence of calcination temp. (CT) on the microscopic morphol. and physicochem. properties of Ni/ATP was investigated by various technologies. The results revealed that increasing CT could improve metal-support interaction (MSI) and surface Ni active species content. However, extortionate CT (>700°C) significantly led to catalyst structure collapse and crystal phase transfer accompanied with the formation of new species, which enhanced the MSI and reduced the surface Nio species content. The outcomes of SRE expts. demonstrated that Ni/ATP-C600 presented maximal activity and H2 yield due to its higher surface contents of the Nio active component and Ni/ATP-C900 exhibited unique stability owing to its stronger MSI. Hence, the coordination between active species distribution and MSI in Ni/ATP can be adjusted by CT. Addnl. coke deposits on spent Ni/ATP-C300 were identified with quite arom. species, which strongly attract to the surface of catalyst and encapsulate active site, while that on used Ni/ATP-C900 had higher degrees of graphitization, but did not affect the stability.
- 39Bertero, N. M.; Trasarti, A. F.; Apesteguía, C. R.; Marchi, A. J. Liquid-phase dehydration of 1-phenylethanol on solid acids: Influence of catalyst acidity and pore structure. Appl. Catal. A: Gen. 2013, 458, 28– 38, DOI: 10.1016/j.apcata.2013.03.01838https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXnsVGht7s%253D&md5=cffd590d7348b13f295c7210bc0a070dLiquid-phase dehydration of 1-phenylethanol on solid acids: Influence of catalyst acidity and pore structureBertero, Nicolas M.; Trasarti, Andres F.; Apesteguia, Carlos R.; Marchi, Alberto J.Applied Catalysis, A: General (2013), 458 (), 28-38CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)The liq.-phase dehydration of 1-phenylethanol (PHE) over different solid acids was studied at 363 K using cyclohexane as solvent. It was found that the catalyst activity and selectivity strongly depended on: (1) the nature, strength and d. of acid sites and (2) the textural properties of the catalyst. Catalysts contg. mainly surface Bronsted acid sites of medium-high strength, such as Amberlyst 15, HPA/SiO2, and HMOR zeolite, showed low initial styrene (STY) selectivity because the PHE dehydrated to alpha-methylbenzyl ether (AME) at higher or similar rates than to STY. Both primary products, STY and AME, were consecutively transformed to other heavy products (HP). Catalysts contg. predominantly Lewis acid sites, such as ZnO/SiO2, Al-MCM-41 and SiO2-Al2O3, selectively transformed PHE to AME. The ether can be sequentially converted to STY and HP, depending on the solid acidity. Solid acids having strong surface Lewis sites, e.g. SiO2-Al2O3, showed high dehydration rate and HP prodn. Samples contg. exclusively weak Lewis acid sites, e.g. γ-Al2O3, were not active in the PHE dehydration at 363 K. Only zeolites HZSM-5, HBEA and HY, with similar surface d. of Bronsted and Lewis acid sites, converted selectively PHE into STY, giving initial STY selectivities between 83 and 96%. However, HY zeolite was rapidly deactivated due to the blockage of its microporous structure by bulky compds. formed inside the large cages of 13 Å. Instead, on HBEA, STY was converted to HP that can diffuse through the solid microporous structure. Then, the selectivity to STY was drastically reduced with time. A const. and high STY selectivity at total PHE conversion was only obtained with HZSM-5. The pore size of this zeolite is enough to allow the diffusion and conversion of PHE into STY, but it is not adequate to form the surface intermediates leading to AME and HP. Thus, it was proved that: (1) the surface Bronsted to Lewis ratio strongly influences the initial selectivity in the liq.-phase PHE dehydration; (2) a similar Bronsted to Lewis ratio on the solid acid surface is necessary to obtain high initial selectivity to STY; and (3) the right porous structure is crucial to avoid HP prodn. and keep const. the STY selectivity at high PHE conversion. From the exptl. results obtained in this work, a mechanistic approach was proposed in order to explain the influence of both acid site nature and pore size on the selective PHE dehydration in liq. phase.
- 40Chuah, G. K.; Liu, S. H.; Jaenicke, S.; Harrison, L. J. Cyclisation of citronellal to isopulegol catalysed by hydrous zirconia and other solid acids. J. Catal. 2001, 200 (2), 352– 359, DOI: 10.1006/jcat.2001.320839https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXktVKlsLc%253D&md5=1f5d013c4df20eb3ee7585e4158cb2dfCyclization of Citronellal to Isopulegol Catalyzed by Hydrous Zirconia and Other Solid AcidsChuah, G. K.; Liu, S. H.; Jaenicke, S.; Harrison, L. J.Journal of Catalysis (2001), 200 (2), 352-359CODEN: JCTLA5; ISSN:0021-9517. (Academic Press)A review with 29 refs. The cyclization of citronellal to isopulegol is an important step in the synthesis of menthol. Several zirconia-based catalysts were evaluated for this reaction. Zirconium hydroxides and phosphated zirconia had very good activity and selectivity. Ammonia TPD and pyridine IR studies indicate the presence of strong Lewis together with weak Bronsted acid sites. Other strong acids like sulfated zirconia, Amberlyst, and Nafion were very active but the selectivity toward isopulegol was poor. They catalyzed side reactions such as dehydration, cracking, and etherification of isopulegol. Silica, with only weak Lewis acidity, showed very low activity. The presence of both Lewis and Bronsted sites is therefore essential for the reaction. A reaction mechanism is proposed where the citronellal mol. binds to a zirconium Lewis acid site via the aldehyde oxygen and the π-electrons of the double bond so that the right configuration is attained for cyclization. Subsequent protonation of the aldehyde via a neighboring Bronsted acid site initiates the cyclization to isopulegol. (c) 2001 Academic Press.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.iecr.2c02345.
Catalyst characterization: pore size distribution, XRD of extrudates. Catalytic data: selectivity to desired menthol as function of conversion, concentration of menthol vs concentration of 3,7-dimethyloctanol and their ratio vs conversion (PDF)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.