JOURNAL OF MEMBRANE SCIENCE
·
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
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
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
·
化学工程
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
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
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Guojun Lv,Hao Ruan,Xuyang Zou,Yan Chen,Xubin Zhang,Fumin Wang
Solvent-free synthesis method in zeolite preparation can largely decrease the generation of wastewater and improve the zeolite yield by simply grinding and hydrothermal treatment for the solid raw materials, and accordingly is considered as one of the most promisingly green and sustainable synthesis strategy for the metal-doped zeolite materials. However, there are scarcely any reports on the solvent-free synthesis and catalytic application of tungsten-doped zeolite materials. In this work, tungsten-doped MFI zeolites were prepared with solvent-free synthesis method and used as heterogeneous catalyst for cyclohexene epoxidation reaction. The synthesized tungsten-doped MFI zeolites displayed a monoclinic (P21/n) space group attributed to the successful incorporation of tungsten atom into MFI framework and meanwhile possessed an enormous number of irregular mesopores ranging from 2 nm to 50 nm. The influence of TPAOH addition amount on the mesopore structure and properties of tungsten-doped MFI zeolite was further investigated. In addition, the crystallization process of tungsten-doped MFI zeolite sample was tracked and analyzed with SEM, XRD and BET characterizations, and accordingly possible formation process for hierarchical zeolite was proposed. Furthermore, the prepared hierarchical tungsten-doped MFI zeolite displayed eminent cyclohexene epoxidation performance and re-usability for more than five times. This work provides some guidance for the solvent-free synthesis of metallosilicate zeolites, decreasing the generation of wastewater and improving the zeolite yield.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
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
·
环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Quanli Ke,Pengyun Pan,Mei Lu,Guonan Fang,Wei Zhang,Ruina Zhang,Guokai Cui,Xiaopo Niu,Feng Xiong,Ying Zhou,Bo Zhao,Hanfeng Lu
Herein, copper and manganese heteroatoms were incorporated into the siliceous MFI frameworks with high dispersity. When employed in the CO 2 /N 2 binary gas separation, a delicate trade-off for the CO 2 adsorption capacity, adsorption heat and moisture resistance could be realized on the heteroatom-incorporated MFI zeolites, especially the Cu-incorporated one. In order to confirm the role that heteroatoms played in CO 2 adsorption, the textural analyses were then conduced, which proved that the enhanced microporosity may be at the heart of the promoted CO 2 capacity. Next to that, the in situ DRIFTs spectra were continuously tracked during the dynamic adsorption process. Compared to the commercial aluminosilicate analogue, the MFI zeolites with Cu/Mn heteroatoms possesses weaker electrostatic field intensity, which in consequence resulted in their stronger moisture resistance, even in presence of humidity up to 90 RH%. As such, a bottom-up adjustment for the adsorption properties of zeolites in practical environment containing competitive moisture impurity was shown.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
·
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
·
催化化学
✓ 已验证
DOI
高影响因子
Catalysts
·
2019
·Vol. 9
·期 10
·854
·
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
·
材料科学
✓ 已验证
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Kaiwei Wang,Fumin Wang,Yi Zhai,Xubin Zhang,Mingshuai Sun,Jinjin Zhang,Xiaolu Fan,Changhao Bing
The metal species embedded in specific positions within the zeolite framework and their unique microenvironment exhibit fascinating effects on catalytic performance. Herein, we incorporated tetrahedrally coordinated Co 2+ into the framework of hollow silicate-1 zeolite and investigated the influence of halogen anions (Cl - , Br - and F - ) in the synthesized gel on the distribution of cobalt species in the channels. The addition of an appropriate amount of inorganic ammonium salts and seeds was found to be a necessary condition for cobalt incorporated into the framework. Notably, the Cl - anions present in the synthesis gel can induce more cobalt species located at the intersection cavity of silicate-1 (β-type). Comprehensive characterization results indicate that the tetrahedrally coordinated Co 2+ in the intersecting cavities of hollow zeolite appears to exhibit more efficient styrene epoxidation performance. This work presents a simple and cost-effective method to synthesize hollow cobalt-based zeolite with adjustable metal distribution in channels. By regulating the spatial distribution of cobalt species with halogens, the CS-0.1–0.5-Cl catalyst enhanced activity and selectivity in the epoxidation reaction of styrene to styrene oxide. Specifically, at a temperature of 80 °C after a reaction time of 6 h, the catalyst demonstrated a styrene oxide yield of 42.47 % and a excellent styrene oxide selectivity of 82.29 %.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
·
2018
·Vol. 24
·期 48
·12600-12606
·
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
·
化学工程
·
催化技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
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
·
化学工程
✓ 已验证
产品关联
DOI
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
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）