RSC Advances
·
2025
·Vol. 15
·期 12
·9467-9478
·
IF 4.6
Fuchao Li,Jianqiang Liu,Enhui Xing,Xiaoli Wei,Jianhong Gong,Yibin Luo,Xingtian Shu
A series of steam and phosphorus modified ZSM-5 samples were prepared to investigate the effect of pore structure and acid property on ethylene oligomerization. Characterization results showed that steam treatment contributed to generate mesopores with pore sizes of 2–3 nm and 10–20 nm, while progressive aggregation of phosphorus species on the exterior surface resulted in blockage of channels. Dealumination of framework aluminum led to a gradual decline in total acidity and acid strength with an increase of steam temperature or P/Al ratio. Sufficient strong acid sites and enhanced accessibility to the inner active sites were crucial factors in conversion of ethylene to liquid fuels. The steam modified sample at 700 °C (HZ-700) obtained the highest yield of liquid fuels up to 78.1%, which demonstrated an increase of 40% in comparison with the unmodified sample. Due to improved diffusional capacity originating from mesopores, HZ-700 showed a higher deactivation stability than the phosphorus modified sample at similar conversion levels. This work will provide some insight into the development of zeolite-based catalyst for ethylene oligomerization to liquid fuels.
研究领域:
催化化学
·
能源材料科学
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产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 21
·7258-7266
·
IF 4.174
Guanqun Zhang,Yaqi Fan,Ju Huang,Lijin Wang,Chengguang Yang,Meng Lyu,Haiming Liu,Yanhang Ma
The increasing demands for catalysts with improved accessibility to reactants call for a rational synthesis of nanosized zeolites. Herein we developed a facile approach for highly crystalline MFI-type (Silicalite-1 and ZSM-5) and beta zeolites with variable Si/Al ratios and high yield. This was achieved by kinetically decoupling the nucleation from the growth process of the zeolites in a highly concentrated gel system via a temperature-staged treatment. The carefully controlled low-water environment ensures only nucleation in stage I (aging), and hence the generation of abundant nuclei for the subsequent rapid crystallization within a self-confined space at stage II (growth). The method, without using expensive templates or additives, allows the syntheses of nanosized, well-isolated ZSM-5 (Si/Al = 100–∞, 36–88 nm, yield >85%) and Beta (Si/Al = 25–100, 21–66 nm, yield >95%). The ultra-small crystal size endows ZSM-5 zeolites with good catalytic activity, product selectivity and remarkably longer lifetime in methanol conversion reactions.
研究领域:
化学工程
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材料科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2024
·
IF 2.3
Zhu Mengxuan,Xu Wenqi,Wang Longyang,Wang Rui,Jiang Heng,Jin Changzi
Developing sustainable synthesis method of versatile zeolites to overcome the shortcoming of traditional process is of significant for development of green chemistry and environmentally friendly techniques. In this work, MFI zeolite (ZSM-5) was synthesized through organotemplate-, solvent- and seed-free sustainable process comprising physical grinding and quasi-solid state crystallization and utilizing commercial silica gel or Stöber colloidal SiO 2 as silica source. The key influencing factors to this sustainable synthesis process, such as starting material composition, crystallization temperature and time, had been unambiguously investigated by combining a series of characterization techniques. It is revealed that the starting material with SiO 2 /Al 2 O 3 and Na 2 O/SiO 2 at 30–40 and 0.072, respectively, is suitable to obtain zeolite product with high crystallinity. The presence of right amount of water (or alcohol) is also crucial. In addition, this green synthesis method can be extended into the fabrication of encapsulated metal-zeolite bifunctional catalyst, which is effective in hydroisomerization of n -heptane. These results are instructive for development of sustainable synthesis of aluminosilicate zeolites and derived heterogeneous catalysts. Graphical Abstract
研究领域:
催化化学
·
绿色化学
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产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2022
·Vol. 24
·期 14
·2697-2704
·
IF 3.756
Siyu Zhang,Xiaomin Zhang,Lei Dong,Shengjie Zhu,Yangyang Yuan,Lei Xu
In this work, Pt nanoparticles (NPs) were directly encapsulated into MFI-type zeolite (Pt@S-1) via a steam-assisted dry-gel conversion method. The synthesis process included the disaggregation of Pt immobilized SiO2–SH spheres and the in situ crystallization for the synthesis of Pt@S-1. The Pt NPs remained stable during the whole crystallization process and the average size of Pt NPs in the synthesized Pt@S-1 was from 1.54 to 2.34 nm. The highest encapsulation degree of Pt NPs was calculated as 93.8% and decreased slightly to 84.9% with the increase of Pt loading. Owing to the high encapsulation degree of Pt NPs in MFI crystals, the size of Pt NPs after calcination at 800 °C only grew up to 3.19 nm showing significantly high thermal stability. The uniform microporous pores of silicalite-1 zeolite as well as the small size and stable Pt NPs endow the Pt@S-1 catalyst with high activity and stability in the nitrobenzene hydrogenation reaction.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2015
·Vol. 51
·期 6
·3257-3270
·
IF 2.371
Nian Pei,Su Meihui,Yu Ting,Wang Zheng,Zhang Binxing,Shao Xiuli,Jin Xiaoyong,Jiang Nanzhe,Li Shan,Ma Qiang
A novel highly compact and b -oriented MFI-type zeolite monolayer was obtained by assembling sec -butanol-modified rounded-coffin-shaped silicalite-1 microcrystals by Langmuir–Blodgett (LB) method. The LB monolayer was subsequently tested as a seed layer for the secondary growth of uniformly b -oriented and defect-free MFI zeolite films on stainless steel substrates and platinum electrodes. Three different methods were evaluated for identifying a suitable synthesis route to suppress the undesired a -oriented twin growth during the synthesis of MFI films. The crystal intergrowth and orientation of the MFI films were characterized by scanning electron microscopy and X-ray diffraction (XRD). The crystallographic preferred orientation indices and preferred orientation coverage values calculated using the XRD data were used to quantitatively determine the preferred orientation and surface coverage of the prepared zeolite films. The experimental results confirm that the low tetrapropylammonium hydroxide (TPAOH) method is the most effective route to suppress the undesired a -oriented twin growth, when the highly b -oriented LB monolayer was used as the seed layer for the secondary growth of the b -oriented MFI film. The highly b -oriented MFI-type zeolite film-modified electrodes were further tested as the working electrodes in electrochemical experiments. Cyclic voltammetry experimental results confirmed that the b -oriented MFI films fabricated at low TPAOH concentration were defect free and possessed a distinct molecular sieving property after calcination. The LB method, a highly reproducible and controllable method for the organization of zeolite crystals, can be further applied as an effective platform for the promotion and development of zeolite-modified electrodes as selective sensors. Graphical
研究领域:
材料科学
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电化学
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纳米材料
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传感器
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薄膜制备
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晶体工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Jiali Yu,Jiahui Li,Haipeng Zhu,Gongping Liu,Wanqin Jin
Membrane technology can reduce the energy consumption of alcohol/water separation process, while the membrane performance still needs to be improved. This study reports a fluoride-mediated hydrophobic zeolite incorporated polydimethylsiloxane (PDMS) membrane for highly selective separating ethanol from aqueous solution. A fluoride-assisted synthesis strategy was proposed to achieve synergistic control over the morphology and surface chemical properties of siliceous zeolites. Comprehensive characterizations revealed that fluoride-mediated MFI zeolite (F-MFI) possessed significantly lower silanol density and superior hydrophobicity compared to conventional hydroxide-synthesized MFI zeolite (Si-MFI), thereby improving the selective permeation of ethanol over water. The optimal F-MFI nanoplates (∼150 nm thickness) with high crystallinity were uniformly incorporated into the PDMS membrane, achieving outstanding performance for separating 5 wt% ethanol/water mixture at 40 °C (total flux of 1409 g m −2 h −1 and a separation factor of 19.7—approximately twice that of the pure PDMS membrane). This work provides a high-performance ethanol-selective membrane, and also demonstrates the importance of synthesis condition on the morphology and functionality of filler and the performance of resulting mixed-matrix membrane.
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DOI
高影响因子
ACS Catalysis
·
2018
·
IF 11.384
Yuchao Chai,Sihang Liu,Zhi-Jian Zhao,Jinlong Gong,Weili Dai,Guangjun Wu,Naijia Guan,Landong Li
Metal nanoparticles encapsulated in zeolite have been recently developed as a special type of catalyst that shows significant advantages in activity, shape-selectivity, and stability over conventional supported catalysts. The selectivity modulation of encapsulated nanoparticle catalysis by the zeolite microenvironment is theoretically possible but not addressed yet. Here, we report the in situ encapsulation of sub-nanometric palladium species within MFI-type zeolites, which exhibit high activity and good stability in the hydroconversion of furfural as a model reaction of biomass upgrading. Remarkably, different products, e.g., furan, furfural alcohol, and 1,5-pentanediol, from furfural hydroconversion can be obtained when silicalite-1, Na-ZSM-5, and H-ZSM-5 are employed as hosts of palladium nanoparticles, respectively. Density functional theory calculations and spectroscopy investigations reveal that both the adsorption of furfural and the activation of hydrogen are significantly affected by the zeolite microenvironment, leading to different reaction pathways. Our work presents an elegant example of catalytic selectivity modulation of encapsulated metal nanoparticles by tuning the zeolite microenvironment.
研究领域:
催化
·
材料科学
·
化学工程
·
纳米技术
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 38
·23272-23278
·
IF 3.108
Peicheng Wang,Yang Zhao,Hongbin Zhang,Tao Yu,Yahong Zhang,Yi Tang
A series of diquaternary pyrazolium-derived organic templates (N,N′-dimethyl-N,N′-1,6-dihexylidenedipyrazolium, N,N′-diethyl-N,N′-1,6-dihexylidenedipyrazolium, N,N′-dipropyl-N,N′-1,6-dihexylidenedipyrazolium, denoted as 6C-DMP, 6C-DEP, 6C-DPP, respectively) with methyl, ethyl and propyl groups substituted on the N atom of pyrazole ring at both terminals have been used in the synthesis of high silica MTW and MFI zeolites. Through combining the characterization results, including XRD, NMR, elemental analysis, TG, XRF, FE-SEM, N2 sorption and FE-TEM, with molecular mechanics simulations to explore the location, orientation and the interaction energies of the three templates, we confirmed the state of templates in zeolite framework, carefully characterized their morphology/structure properties, and finally investigated their different spatial effects for the zeolite formation. The study found that 6C-DMP and 6C-DEP are able to produce MTW, while 6C-DPP is able to produce MFI. 6C-DMP, owing to a good match with the MTW framework and can be used to synthesize regular MTW zeolite with few defects. The MTW zeolite prepared by using 6C-DEP as a template presents more defects and irregular macromorphology due to a relatively poor match to the MTW framework. 6C-DPP can get MFI other than MTW due to a larger spatial hindrance, and it is located in the MFI framework with a special spatial orientation.
研究领域:
化学
·
材料科学
·
物理化学
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产品关联
DOI
高影响因子
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