JOURNAL OF MEMBRANE SCIENCE
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2010
·
IF 3.203
Zhou Hong,Chun Zhang,Xuehong Gu,Wanqin Jin,Nanping Xu
In this paper, we proposed a simple method with hydrolysis of silanes to heal nonzeolitic pores of pure silica MFI (silicalite) zeolite membranes. Three silane precursors, tetraethoxysilane (TEOS), tetramethoxysilane (TMOS) and dimethoxydimethylsilane (DMDS) were used for membrane modification at room temperature. The modified membranes were evaluated by the separation of p-/o-xylene mixture. It was found that the hydrolysis of silanes in nonzeolitic pores could obviously improve separation performance of the MFI zeolite membranes. The modification results of nonzeolitic pores were related to the silane precursors with different physical–chemical properties and molecular kinetic diameter. Compared with TEOS and TMOS, DMDS was more suitable as a precursor for healing nonzeolitic pores. For a zeolite membrane after DMDS modification, p-/o-xylene separation factor could be increased from 2.34 to 10.84 while p-xylene flux decreased only about 12.6%.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2022
·
IF 10.53
Li Peng,Zhengqi Wu,Boxuan Wang,Hua Liu,Chun Zhang,Xuehong Gu
Pure silica MFI (Si-MFI) zeolite membranes with desirable hydrophobicity have the potential to separate ethanol/water mixture. However, its separation performance would significantly decrease in the long-term operation due to the presence of silanol groups formed in alkaline media. In this work, silanol-free MFI zeolite membranes were prepared by the incorporation of tungsten in MFI framework. The occurrence of silanol group can be prevented by formation of W–O–Si bridges. The synthesis parameters affected the W-MFI zeolite membranes’ microstructure and separation performance. For 5 wt% ethanol solution, the W-MFI zeolite membranes prepared at optimum condition showed stable separation performance of permeation flux as 2.81 kg m −2 h −1 with separation factor as 32 over 80 h at 60 °C. The membrane was characterized by XRD , DR UV–vis, XPS and 29 Si NMR, and the results confirmed the incorporation of W and the absence of silanol groups. This research showed that W-MFI zeolite membranes are promising candidates for ethanol extraction with high stability.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2025
·
IF 3.7
Xinyi Gao,Qiancheng Zheng,Zhengbao Wang
The preparation of dispersible MFI-type zeolite nanoparticles with open micropores is challenging. Herein, a rapid and effective ultrasound-assisted liquid-phase exfoliation method along with a freeze-drying process for redispersion of calcined Silicalite-1 (S-1) zeolite nanoparticle aggregates using 3-aminopropanol as an exfoliating agent is demonstrated. The exfoliation of S-1 zeolite nanoparticles is characterized by X-ray diffraction, scanning electron microscopy and DLS particle size analysis. The effects of drying methods of as-synthesized zeolite nanoparticle suspension, zeolite contents in frozen nanoparticle suspension, exfoliating agent concentrations, and zeolite doses in ultrasonic suspension on exfoliation efficiency are systematically investigated. It is found that the S-1 zeolite nanoparticle (∼70 nm) achieves a yield up to 95 % through a 30 min ultrasonic exfoliation in a 3-aminopropanol solution along with a freeze-drying process. The proposed exfoliation mechanism involves two primary stages: guest molecule insertion followed by water expansion, both substantially enhanced by tip sonication. This work offers a comprehensive understanding of the exfoliation process, provides valuable insights into the dispersion of sintered zeolite nanoparticles.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Li Peng,Li Zhao,Guang Pan,Xuehong Gu
The separation of CO 2 from N 2 using MFI-type zeolite membranes relies on a mechanism dominated by adsorption and diffusion processes. In this investigation, we employed a tungsten (W) doping approach to elevate the CO 2 separation selectivity of MFI zeolite membranes. Isothermal adsorption assessments demonstrated an elevated heat of adsorption (Q st ) for CO 2 and a reduced pore sizes after W doping, corroborating the enhanced CO 2 /N 2 separation efficiency observed. Specifically, the W-doped MFI membrane exhibited a selectivity of 38.8 under dry conditions, a substantial improvement over the 8.7 selectivity achieved by the undoped Si-MFI membrane, while the CO 2 permeance remained comparable (3.9 × 10 -7 vs 4.5 × 10 -7 mol·m -2 ·s -1 ·Pa -1 ). Furthermore, the incorporation of tungsten curtails the formation of silanol groups by stabilizing the zeolite framework via energetically favorable W-O-Si linkages. These linkages diminish silanol-related defects, typically prone to water adsorption, thereby enhancing the membrane’s hydrophobicity. Consequently, the W-doped MFI membrane maintains a CO 2 /N 2 selectivity of 29.5 and a CO 2 permeance of 1.8 × 10 -7 mol·m -2 ·s -1 ·Pa -1 in the humid environments, outperforming most reported zeolite membranes and showing potential ability for practical post-combustion carbon capture applications.
研究领域:
材料科学
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环境工程
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
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2024
·
IF 2.5
Wu Wenhui,Zhao Kangrui,Xiao Kun
ZSM-5 is widely used in the field of catalysis due to its stability and tunability. Its acidity can be adjusted not only by varying the initial gel composition, but also by incorporating different types of template to enhance its performance. Both [Ga]-MFI and [Ga, Al]-MFI have demonstrated promising performance in the catalytic trioxane of formaldehyde synthesis. However, there is currently a paucity of research examining the influence of different templates on the catalytic performance of [Ga]-MFI and [Ga, Al]-MFI. The influence of different templates on the structure, morphology, and pore structure of the zeolite has been revealed through the application of characterisation techniques, including XRD, MAS NMR spectroscopy, ICP-OES, BET, and SEM. The impact of different templates on the acid properties of [Ga]-MFI and [Ga, Al]-MFI was assessed using NH 3 -TPD and Py-IR. The results of the experimental investigation into the catalytic performance of zeolites synthesised with larger molecular-structured templates indicate that these zeolites exhibit superior catalytic performance. Furthermore, the introduction of Na + ions has been observed to reduce the space-time yield of the products.
研究领域:
材料科学
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催化化学
✓ 已验证
DOI
高影响因子
Catalysts
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2019
·Vol. 9
·期 10
·854
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IF 3.444
Jian Li,Xiangyu Li,Derun Hua,Xinning Lu,Yujue Wang
A series of gallium-containing MFI (Ga-MFI) zeolites with varying Ga2O3/Al2O3ratios were synthesized using hydrothermal synthesis and tested as catalyst in catalytic fast pyrolysis (CFP) of beech wood for aromatic production. The results show that the incorporation of Ga slightly reduced the effective pore size of Ga-MFI zeolites compared to conventional HZSM-5 zeolites. Therefore, the Ga-MFI zeolites increased the aromatic selectivity for smaller aromatics such as benzene, toluene, andp-xylene and decreased the aromatic selectivity for bulkier ones such asm-xylene,o-xylene, and polyaromatics in CFP of beech wood relative to HSZM-5. In particular, the yield and selectivity ofp-xylene, the most desired product from CFP of biomass, increased considerably from 1.64 C% and 33.3% for conventional HZSM-5 to 2.98–3.34 C% and 72.1–79.6% for the synthesized Ga-MFI zeolites. These results suggest that slightly reducing the pore size of MFI zeolite by Ga incorporation has a beneficial effect on optimizing the aromatic selectivity toward more valuable monoaromatic products, especiallyp-xylene, during CFP of biomass.Keywords:aromatics;biomass;MFI zeolites;gallium;catalytic fast pyrolysis
研究领域:
能源化学
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材料科学
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DOI
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
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2018
·Vol. 24
·期 48
·12600-12606
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IF 5.16
Ang Li,Xue Wang,Tao Wang,Huali Liu,Tunan Gao,Meihong Fan,Qisheng Huo,Zhen-An Qiao
Graphical Filling the gaps : A topotactic synthetic methodology allows the synthesis of nanosized hierarchical MFI zeolite spheres and particles from silica spheres and tetrapropylammonium hydroxide (TPAOH; see figure). Dissolved silica species rebond around TPA + and zeolite structures are generated with defective mesoporous walls as a result of desilication of the initial silica spheres. Upon further crystal growth, zeolite nanoparticles can be obtained. Much effort has been invested in the designed synthesis of zeolites with nanosized and hierarchical structures in recent decades, on account of increasing demands in practical applications, especially catalysis. Herein, a new topotactic synthetic strategy is demonstrated to synthesize nanosized and hierarchical zeolites in a one-step procedure. By using silica spheres as the adjustable amorphous precursors and tetrapropylammonium hydroxide as a structure-directing agent, effortless control of both size and porosity can be achieved in this system with no extra templates. With a simple hydrothermal process, hierarchical zeolite spheres can be modified with acid cites (Al species incorporated in the framework). Benefitting from its mesoporosity, palladium nanoparticles are incorporated into the nanosized hierarchical zeolite, which makes the materials suitable for use in a cascade catalysis reaction of benzimidazole derivatives, including independent acid catalysis and hydrogenation sites. The nanocomposites show exceptional activity and stability in catalysis and recycling reaction. This strategy can be developed into other versatile and practicable scaffolds for advanced zeolite catalytic nanoreactor systems.
研究领域:
材料科学
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化学工程
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催化技术
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2025
·
IF 9
Hammad Saulat,Weiquan Feng,Zhongzhuang Hu,Mengxing He,Jinming Lu,Yan Zhang,Jianhua Yang,Cheng He
Separation of butane isomers holds substantial importance across various industrial sectors due to their divergent chemical characteristics and pervasive applications. Their efficient separation into high-purity iso-butane (i-C 4 ) and normal butane (n-C 4 ) allows their optimal utilization while maximizing economic benefit and minimizing waste, though their separation presents significant challenges due to their similar physicochemical properties and energy-intensive separation requirements. Polycrystalline zeolite-based membrane separation processes emerge as an energy-efficient approach for separating butane isomers by reducing the total operating energy consumption as compared to the conventional distillation process. However, the fabrication cost of polycrystalline zeolite membranes is high, predominantly dictated by the production cost of the support (≈ 50-70 %) rather than the polycrystalline zeolite layer. Herein, we report the fabrication of polycrystalline MFI membranes on inexpensive coarse macroporous α-Al 2 O 3 tube supports (symmetrical supports) with an average pore size in the range of 2 ∼ 3μm for separating butane isomers. Macroporous α-Al 2 O 3 tube supports are coated with single (sheet-like MFI crystals) and dual (sheet-like MFI crystals + MFI crystals) seed layers to achieve the desired separation performances. For coating a single seed layer, MFI nanocrystals were employed as precursors for synthesizing sheet-like MFI crystals with a high aspect ratio as compared to the conventional MFI crystals. Taking advantage of the high aspect ratio of sheet-like MFI crystals, single seed layer was fabricated on coarse macroporous α-Al 2 O 3 tube support, eliminating the time-intensive steps to reduce the support pore size and reducing the problem of pore plugging. Subsequently, a dual seed layer (sheet-like MFI crystals + MFI crystals) was also created by hot dip coating the MFI crystals on the surface of a single seed layer with the aim of fabricating a more compact, continuous, and molecular sieving polycrystalline MFI membrane with enhanced separation performance for the separation butane isomers. After hydrothermal crystallization, polycrystalline MFI membrane (M-2) fabricated on a single seed layer exhibits a separation factor and n-butane permeance of 33.80 and 2.00x10 -7 mol/m 2 .Pa.s, respectively. In contrast, the polycrystalline MFI membrane (D-3) formed on a dual seed layer demonstrates a separation factor and n-butane permanence of 40.60 and 1.47x10 -7 mol/m 2 .Pa.s, respectively. Both these membranes demonstrate good stability and reproducibility. Fabrication of polycrystalline MFI membranes on inexpensive coarse macroporous tube supports is a crucial advancement in reducing fabrication costs and facilitating industrial implementation. However, substantial potential remains for further scaling up and enhancing the separation performance of current polycrystalline MFI membranes.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2019
·
IF 1.911
Zhipeng Chen,Jiajin Huang,Qiaowen Mu,Huiyong Chen,Feng Xu,Yanxiong Fang,Baoyu Liu
The modification of pillared MFI zeolites was performed by nitridation of silica pillared MFI zeolite nanosheets under NH 3 atmosphere with different time. The resultant zeolites were characterized by a complementary combination of X-ray power diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), pyridine-IR spectroscopy and N 2 adsorption–desorption isotherms. The analyses showed that the nitridation didn't destroy the crystallinity and specific surface area of zeolites, and the acidity of zeolites can be tailored by tuning the time of nitridation, resulting in the different concentration ratios of Brønsted-to-Lewis (B/L) acid sites. Moreover, the nitrided zeolites exhibited high selectivity to 2-benzyl-1,3,5-trimethylbenzene than parent silica pillared MFI zeolite nanosheets in benzylation of mesitylene with benzyl alcohol . A balance between Brønsted acid sites and Lewis acid sites can inhibit the self-etherification of benzyl alcohol and enhance the selectivity of alkylated product. These experimental data implied that nitridation was an effective method to modulate the acidity of zeolites and the synergy between Brønsted acid sites and Lewis acid sites was a decisive factor to determine the selectivity.
研究领域:
化学工程
·
催化材料
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DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2019
·
IF 4.182
Xixi Ma,Xiaocao Wu,Jürgen Caro,Aisheng Huang
A seeding-free synthesis strategy was developed for the preparation of dense and phase-pure MFI zeolite membranes based on “like grows like” principle. Through covalent modification of the porous ceramic supports by using 1H,1H,2H,2H-perfluoroalkyltriethoxysilanes (POTS), the support surface was changed from hydrophilic to hydrophobic, which promotes the nucleation and growth of hydrophobic MFI zeolite membranes. Thin, well-intergrown and phase-pure MFI zeolite membranes, with a thickness of about 2.0–3.0 μm, can be facilely prepared on POTS-modified supports like Al 2 O 3 and TiO 2 at 175 °C for 24 h. No cracks, pinholes or other visible macroscopic defects are observed in the membrane layer. The MFI zeolite membranes were evaluated in the hydrophobic separation of 5.0 wt% ethanol/water mixture at 75 °C by pervaporation . The MFI zeolite membrane prepared on the POTS-modified TiO 2 disk shows high pervaporation separation for ethanol recovery. At 75 °C, a separation factor of 103 and total flux of 2.56 kg/m 2 h can be obtained, which is promising to extract bio-alcohols from the fermentation broth.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2025
·
IF 6.4
Jiayu Yu,Ke Du,Di Pan,He Li,Ling Ding,Wei Chen,Yahong Zhang,Yi Tang
Simplifying complex synthesis systems containing multiple species into ones with a single classical or non-classical growth path is valuable for understanding their respective mechanisms. However, most zeolite growth involves intertwined classical and non-classical mechanisms, making it crucial to distinguish and modulate their contributions in the original synthetic system. In this study, we presented a method to distinguish and directly quantify the contributions of classical and non-classical crystallization pathways in MFI zeolite synthesis, demonstrating that the dominant pathway could be shifted from non-classical to classical by varying the H2O/SiO2 and ethanol/SiO2 ratios. Our findings showed that reducing the H2O/SiO2 ratio favored the non-classical pathway, while increasing the ethanol/SiO2 ratio promoted the classical mechanism. However, these changes had minimal effect on their crystallization sequences: the non-classical pathway predominated initially, but both pathways intertwined as crystallization progressed. Notably, the shift in crystallization pathway did not significantly affect the acidic properties of the zeolites but had a direct impact on their catalytic performance. The catalytic activity of the resulting ZSM-5 zeolites in furfuryl alcohol etherification correlated with the contribution of the classical pathway, with higher contributions leading to enhanced catalytic activity. This study provides new insights into the zeolite crystallization process, offering a valuable approach for optimizing synthesis conditions and improving catalyst performance.
研究领域:
材料科学
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化学工程
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催化反应
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产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2025
·
IF 9.7
Meile Yue,Kankan Bu,Yahong,Zhang,Wei Shen,Hualong Xu,Zhen Huang
Propane dehydroaromatization (PDA) provides a promising route to produce valuable chemicals such as benzene, toluene and xylene via non-petroleum feedstocks, in which Ga-modified MFI zeolites demonstrate high activity but are susceptible to severe coke deposition. The defect-derived silanols (Si-OH) in zeolite formed during synthesis has emerged as a predominant factor, making the prolongation of the catalyst longevity a major challenge. Here, we developed a gallosilicate MFI zeolite with silanol-defect remediated (Ga-MFI-AHFS) through an ammonium hexafluorosilicate post-treatment, which exhibited an extraordinary activity and stability. Ga-MFI-AHFS exhibits a nearly unchanged propane conversion around 82.0 % with aromatics selectivity around 64.5 % compared to a 25.4 % conversion decline on the raw zeolite with defects exposed during the 20-h CO 2 assisted PDA reaction. The results of FTIR and MAS NMR showed a decreased content of silanol nests as well as the internal Si-OH groups, indicating the successful repair of silicon hydroxyl defects. The restored framework endows the Ga-MFI-AHFS zeolite with an excellent coking resistance, giving a much lower coking-rate of 5.8 × 10 −8 mol C /mol C-in-produced-Aromatics , which is one-sixth of that on Ga-MFI. This work developed a facile route to prepare Ga-MFI zeolite with suppressed silanol-defects, which could help to realize a stable dehydroaromatization of light alkanes.
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产品关联
DOI
PubMed
高影响因子
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