Construction of Metal/Zeolite Hybrid Nanoframe Reactors via in-Situ-Kinetics Transformations

Metal/zeolite hybrid nanoframes featuring highly accessible compartmental environments, abundant heterogeneous interfaces, and diverse chemical compositions are expected to possess significant potential for heterogeneous catalysis, yet their general synthetic methodology has not yet been established. In this study, we developed a two-step in-situ-kinetics transformation approach to prepare metal/ZSM-5 hybrid nanoframes with exceptionally open nanostructures, tunable metal compositions, and abundant accessible active sites. Initially, the process involved the formation of single-crystalline ZSM-5 nanoframes through an anisotropic etching and recrystallization kinetic transformation process. Subsequently, through an in situ reaction of the Ni2+ ions and the silica species etched from ZSM-5 nanoframes, layered nickel silicate emerged on both the inner and outer surfaces of the zeolite nanoframes. Upon reduction under a hydrogen atmosphere, well-dispersed Ni nanoparticles were produced and immobilized onto the ZSM-5 nanoframes. Strikingly, this strategy can be extended to immobilize a variety of ultrasmall monometallic and bimetallic alloy nanoparticles on zeolite nanoframes. Benefiting from the structural and compositional advantages, the resultant hybrid nanoframes with a high loading of discrete Ni nanoparticles exhibited enhanced performance in the hydrodeoxygenation of stearic acid into liquid fuels. Overall, the methodology shares fresh insights into the rational construction of intricate frame-like metal/zeolite hybrid nanoreactors for many potential catalytic applications.


Synthesis of Silicalite-1 nanocrystals (NCs).
The molar composition of the mixture was: 1 SiO2: 0.27 TPAOH: 112 H2O.Typically, 1.2 ml of TPAOH (25 wt%) was mixed with 10 ml of water, and then 1.2 ml of TEOS was added to the solution.The mixture was stirred continuously for 4 h.The obtained clear solution was transferred into a 20 ml Teflon-lined stainless steel autoclave and crystallized at 170 °C for 12 hours in a rotational oven.The white product was separated by centrifugation, washed with water and ethanol several times, dried at 60 °C in the oven overnight, and then calcinated at 550 °C for 6 h.

Synthesis of ZSM-5 nanoframes (NFs).
Briefly, 2 mg of aluminum isopropoxide was added into 10 ml of 0.22 M TPAOH solution, and then 120 mg of silicalite-1 nanocrystals was dispersed into the mixture by ultrasonication.The suspension was then transferred into an autoclave and crystallized at 170 °C for 24 h in a rotational oven.The product was separated by centrifugation, washed with water and ethanol several times, and then dried at 60 °C in the oven overnight, followed by calcination at 550 °C for 6 h.Synthesis of ZSM-5@Ni3Si2O5(OH)4 NFs.ZSM-5@Ni3Si2O5(OH)4 NFs was prepared through a simple hydrothermal process.Typically, 8.7 mg of Ni(CH3COO)2• 4H2O, 37.4 mg of NH4Cl, and 63.7mg of NH3•H 2O (28%) were added under stirring in 3.5 g of distilled water.20 mg of the as-prepared ZSM-5 NFs was then added to the above solution and ultrasonicated for 30 min to form a uniform suspension, then the mixture was heated to 100 °C for 3 h.The resulting green precipitates were collected and washed several times with distilled water and ethanol.The final products were dried at 60 °C in the oven for 4 h.

Synthesis of ZSM-5 NCs.
To synthesize ZSM-5 NCs, 1.22g of TPAOH solution (25 wt.%), 20 mg of sodium hydroxide, and 60 mg of sodium aluminate were dissolved in 4 g of deionized water.Then, 2.083 g of TEOS was added to the mixture and vigorously stirred for 6 h.Finally, hydrothermal treatment was carried out at 170 °C for 72 h under static condition.The H-type ZSM-5 NCs were prepared via an ion-exchange process.The as-prepared ZSM-5 NCs were dispersed in 100 ml of 1.0 M NH4Cl solution at 80 °C for 8 h three times.Afterward, the obtained product was washed with deionized water several times and calcined in a muffle furnace at 550 °C for 6 h.

Synthesis of ZSM-5 nanoboxes (NBs).
Briefly, 1.219 g of TPAOH solution (25 wt%), 40 mg of sodium hydroxide, and 20 mg of sodium aluminate were dissolved in 3.4 ml of water at room temperature under stirring.Then, 2.083 g of TEOS was added to the mixture and vigorously stirred for 6 h.Finally, hydrothermal treatment was carried out at 170 °C for 72 h under static condition.The H-type ZSM-5 was obtained through the same the ion-exchange and annealing process.To prepare H-type ZSM-5 NBs, 1 g of H-type ZSM-5 was dispersed in 10 ml of 0.2 M TPAOH solution.The mixture was heated in an autoclave at 170 °C under stirring for 3 d.The product was separated by centrifugation, washed with water and ethanol several times, and then dried at 60 °C in the oven overnight, followed by calcination at 550 o C for 6 h.

Synthesis of IM-Ni/ZSM-5 NFs.
In a typical synthesis, 0.1 g of Ni(NO3)2• 6H2O was dissolved in 1 g of distilled water, and then the solution was slowly dropped onto 1 g of ZSM-5 NFs with continuous stirring at ambient temperature for a total of 4 h.Afterwards, the material was firstly dried overnight at 80 o C for 12 h.Then the catalyst precursor was calcined in air (flow rate: 100 ml min -1 ) at 400 o C for 4 h and reduced under a H2 flow (flow rate: 20 ml min -1 ) at 500 o C for 5 h with a heating rate of 2 o C min -1 .S1.

Section 2. Characterizations
The powder X-ray diffraction measurements were performed on a Rigaku D-Max 2550 diffractometer by using Cu Kα radiation.Scanning electron microscopy images were measured with JEOL JSM-6700F.The transmission electron microscopy images and the elemental mappings were measured with a Tecnai F20 electron microscope.The H2-TPR measurements were measured on a Micromeritics AutoChem II 2920 instrument.Chemical compositions of samples were analyzed by inductively coupled plasma (ICP) using Perkin-Elmer Optima 3300 DV ICP instrument.Nitrogen adsorption/desorption measurements were carried out on a Micromeritics ASAP 3-flex analyzer at 77 K after the samples were degassed at 350 °C under vacuum.XPS spectra of the catalysts were performed using a Thermo ESCALAB 250 spectrometer (Thermo Scientific, NY, USA).Fourier transform infrared (FTIR) spectra were recorded on a BRUKER vertex 80v; samples before testing were pelleted with KBr powder.
Fourier transform infrared (FT-IR) spectra of pyridine (Py) and 2,6-di-tert-butyl-pyridine (DTBP) analysis were recorded on Bruker Tensor 27.All samples were prepared as a selfsupported wafer and placed inside an IR transmission cell and then pretreated under vacuum at 450 °C for 1 h followed by cooling to 150 °C.Py or DTBP was adsorbed onto the sample for 30 min at 150 °C, and the mixture was evacuated for 1 h before the spectrum was recorded.
CO pulse chemisorption was performed by a Micromeritics AutoChem 2920.Before the test, 100 mg of catalyst was activated in a flow of 100 ml min −1 10 vol% H2 in He at 500 °C for 2 h and then blew with He for 1 h.After cooling to 40 °C, the CO gas pulses (5 vol% in He) were introduced at a flow rate of 100 ml min −1 .The changes in the CO gas phase concentration were recorded by TCD.

Section 3. Catalytic tests
The deoxygenation reaction of stearic acid (SA) was carried out in a batch autoclave (CHEMN Instrument, 100 ml).In a typical run, 0.1 g of catalysts, 1 g of SA and 40 ml of dodecane were introduced into the batch autoclave.The autoclave was sealed and firstly purged with N2 (30 bar) three times to remove the residual air, followed by filling it with the reaction gas H2 (40 bar) at room temperature.The reaction was performed at 260 °C at a stirring speed of 1000 rpm.The liquid products were obtained by in-situ sampling every 20 min and analyzed by gas chromatography (GC, Agilent 7890B) equipped with HP-innowax column (30 m × 320 µm × 25 µm) and FID detector.The methyl heptadecanoate was used as a quantitative internal standard in GC measurement.The mass balance was above 98%.

Figure S23 .
Figure S23.The effects of stirring speed on the conversion of stearic acid.

Figure S24 .
Figure S24.Conversion of stearic acid as a function of time over various prepared catalysts.

Figure S25 .
Figure S25.Conversion of 1-octadecanol as a function of time over various catalysts.Reaction

a
The loading of Ni particles analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES).b The average diameter of Ni particles (dNi) measured based on TEM.c The dispersion of Ni particles (DNi) calculated based on the CO pulse chemisorption.

a
The number of Brønsted acid sites (BAS) determined by pyridine (Py) titration.b The number of external Brønsted acid sites determined by 2,6-di-tert-butylpyridine (DTBP) titration.c The fraction of external Brønsted acid sites calculated by (number of Brønsted acid sites by DTBP titration/number of Brønsted acid sites by Py titration)

Table of Contents Section 1. Materials and Methods Section 2. Characterizations Section 3. Catalytic tests Section 4. Additional figures and tables Section 1. Materials and Methods
Sinopharm Chemical Reagent Company), stearic acid.All reagents were used without further purification.Deionized (DI) water was used in all experiments.

Table S1 .
The molar composition of the initial mixtures, temperature, and reaction time for the synthesis of various ZSM-5@metal silicate NFs.

Table S2 .
Metal loading, average diameter, and dispersion of various catalysts.

Table S4 .
Comparison of normalized rates for the conversion of stearic acid and 1-octadecanol over various catalysts.