MICROPOROUS AND MESOPOROUS MATERIALS
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2022
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IF 5.876
Guojun Lv,Yan Chen,Xuyang Zou,Jiangzhang Wang,Tao Wang,Fumin Wang,Xubin Zhang
Simultaneous insertion of double heteroatom in the MFI framework generally gives rise to synergistic catalysis effect, however the specific origins for synergistic catalysis is still nebulous. In this study, vanadium-titanium doped MFI zeolite was synthesized via one-pot hydrothermal synthesis with the addition of (NH 4 ) 2 CO 3 and applied as heterogeneous catalyst for the synergistic catalysis of 1-hexene and cyclohexene epoxidation. Simultaneous incorporation of vanadium and titanium induced the partial charge transformation of titanium (Ⅳ) into titanium (Ⅲ), which was verified by EPR and XPS characterizations. UV-Raman and UV–Vis spectra disclosed that partial charge transformation mainly occurred for framework titanium (Ⅳ). In addition, simultaneous insertion of vanadium and titanium gave rise to more Lewis acid sites as well as larger external surface area for VTS(0.15) zeolite in comparison to VS(0.15) and TS(0.15) zeolite. The prepared VTS(0.15) zeolite presented a TOF value of 118.8 h −1 for 1-hexene epoxidation, which is 7.8 folds and 1.3 folds of VS(0.15) and TS(0.15) respectively. Partial charge transformation of framework titanium (Ⅳ) into titanium (Ⅲ), robust Lewis acid sites as large external surface area may induce the synergistic catalysis effect for VTS(0.15) zeolite in the epoxidation reactions. Moreover, the obtained VTS(0.15) zeolite particles showed good reusability for more than five cycles.
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
高影响因子
CRYSTAL GROWTH & DESIGN
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2023
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IF 3.8
Xunming Su,Zhong-Pan Hu,Jingfeng Han,Yingxu Wei,Zhongmin Liu
Developing highly efficient methods to selectively incorporate active metal sites into the zeolite framework is crucial for the large-scale utilization of metal-zeolites in various catalytic reactions including alkane conversion. Herein, ferrous gluconate is developed as an efficient metal precursor to embed Fe atoms into the MFI siliceous zeolite framework. The crystallization time and Si/Fe ratio are systematically investigated. It is revealed that the ferrous gluconate is well soluble and stable under alkaline conditions, allowing ferrous gluconate to participate in the whole crystallization course of zeolite. Multiple characterizations demonstrate that the tetrahedrally coordinated Fe atoms are selectively incorporated into the MFI siliceous zeolite framework (Fe-MFI). A catalytic test in propane dehydrogenation shows that the optimized Fe-MFI zeolite possesses high activity, propylene selectivity, and durability. This study opens an efficient strategy to incorporate isolated Fe atoms into the zeolite framework.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
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2019
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IF 3.021
Mingxue Su,Wenzhi Li,Qiaozhi Ma,Song Li,Tao Yang,Xiaomeng Dou
A water-tolerant, basic, and hierarchical MFI zeolite catalyst was synthesized and applied in the aldol condensation reaction between biomass-derived furfural and levulinic acid. The results showed that the addition of poly(diallyl dimethylammonium chloride) significantly affected the textural and acid–base properties of hierarchical zeolite, which subsequently influenced the catalytic performance of hierarchical zeolite. In the aqueous phase, potassium-modified, hierarchical MFI zeolite (K/H-MFI-n) was more active for aldol condensation between furfural and levulinic acid than the potassium-modified, conventional MFI zeolite (K/MFI). This was ascribed to higher basic sites density and improved diffusion limitation of K/H-MFI-n. A 70.6% yield of aldol condensation product was achieved with a complete conversion of furfural at 100 °C for 9 h by K/H-MFI-0.6. However, only 27.4% yield of aldol condensation product with 55.1% furfural conversion was obtained by K/MFI at the same condition. Two major isomeric aldol products, β-furfurylidenelevulinic acid and δ-furfurylidenelevulinic acid (β-FDLA and δ-FDLA), were obtained after acidification. K/H-MFI-n displayed an enhanced selectivity (54.9%) to δ-FDLA, owing to the stronger basicity of K/H-MFI-n. However, K/MFI showed a preferred selectivity to β-FDLA (42.7%), owing to the dominant Lewis acidity. Recyclability research showed that the catalytic performance of potassium-modified, hierarchical MFI zeolite was acceptable after five runs.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
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2024
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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
MICROPOROUS AND MESOPOROUS MATERIALS
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2024
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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
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
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2025
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IF 5.3
Haoyu Liu,Wei Liu,Yanlin Wang,Hong Yuan
The incorporation of mesopores into zeolite catalysts improves both reactant diffusion and the catalyst lifespan. In this study, a bolaform surfactant, C6H13–N+(CH3)2–C6H12–N+(CH3)2–C6H12–O–C6H4–O–C6H12–N+(CH3)2–C6H12–N+(CH3)2–C6H13 (BAM–6–6–6), was used to guide the synthesis of hierarchical MFI zeolite nanosheets (HMNs). The HMN pore structure and acidic sites were altered by varying the ratio of the K2SO4-derived K+ and Al sources in the initial gel. The X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, and N2 adsorption/desorption were used to characterize these materials. The HMNs each had an interconnected hierarchical pore structure which consisted of MFI and mesoporous structures and mesopore-specific surface areas as high as 353.8 m2 g–1, indicating that the BAM–6–6–6 formed lamellar micelles based on π–π stacking. Temperature-programmed NH3 desorption and 27Al magic angle spinning nuclear magnetic resonance spectroscopy revealed that the intersection cavity of the HMN structure was enriched with acidic sites. Because of the layered HMN structure, which promoted diffusion and increased resistance to carbon deposition and buildup, the catalysts possessed good catalytic activity in cracking oleic acid. For the HMN zeolite, the light-olefin yield reached 50.02% at 500 °C, outweighing that of conventional ZSM-5 (39.80%), and the initial catalytic activity was retained for up to 50 h. Furthermore, for HMN, the hard coke loss (3.8%) was less than that for CZSM-5 (9.7%).
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
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2022
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IF 13.599
Chenguang Wang,Chengyan Wen,Zheng Liang,Zhipeng Tian,Qian Jiang,Yuhe Liao,Xunzhu Jiang,Lungang Chen,Qiying Liu,Longlong Ma,Michiel Dusselier
Direct conversion of syngas to aromatics has great potential to decrease fossil fuel dependence. Here, a unique structured hybrid catalyst composed of Fe 3 O 4 nanoparticles intimately dispersed inside an acidic zeolite is developed. 1 to 4 nm sized Fe 3 O 4 nanoparticles end up evenly dispersed in an acidic and slightly mesoporous Al-ZSM-5 based on Fe 3 O 4 restructuring during co-hydrothermal synthesis using organosilane modification. A very high aromatic productivity of 214 mmol aromatics h −1 g Fe −1 can be obtained with a remarkable 62% aromatic selectivity in hydrocarbons. This catalyst has excellent sintering resistance ability and maintains stable aromatics production over 570 h. The synthetic insights that postulate a mechanism for the metastable oxide-zeolite reorganization during hydrothermal synthesis could serve as a generic route to sinter-resistant oxide-zeolite composite materials with uniform, well-dispersed oxide nanoparticles in close intimacy with - and partially confined in - a zeolite matrix.
研究领域:
催化化学
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材料科学
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2023
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IF 5.2
Xuyang Zou,Jiangzhang Wang,Guojun Lv,Tao Wang,Chaoyi Zhou,Yan Chen,Jialing Shen,Shihao Su,Zhongmin Liu
Impregnation handlement can load highly dispersed CuO nanoparticles on the Fe-MFI zeolite and effectively enhances its catalytic activity in the tetracycline degradation reactions, but encounters serious re-usability problems. In this work, Fe-MFI zeolite-encapsulated copper oxide CuO@Fe-MFI was prepared via one-step hydrothermal synthesis and utilized as heterogeneous catalyst for the removal of tetracycline. The obtained 2CuO@1Fe-MFI zeolite presented a external surface area of 270 m 2 /g, which was almost 5.5 folds of 2CuO/1Fe-MFI zeolite obtained by impregnation handlement. In addition, there may be a near-neighbor effect between encapsulated CuO and framework iron evidenced by the shifts of UV–Vis absorption bands as well as binding energies for Fe 2p and Cu 2p. At pH = 7.0, 2CuO@1Fe-MFI zeolite attained the largest tetracycline removal rate of 99.6% within 20 min at experimental conditions: [TCE] = 50 mg/L, [Catalyst] = 0.5 g/L, [PMS] = 1.0 g/L, 323 K, and the biggest degradation rate constant of 2.42 min −1 , which was almost 11.1 folds of that for 2CuO/1Fe-MFI zeolite. The large external surface area and near-neighbor effect together gave rise to the excellent tetracycline degradation performance for 2CuO@1Fe-MFI zeolite. On the same time, the obtained 2CuO@1Fe-MFI zeolite can be reused for more than five times. Quenching experiments and EPR characterizations demonstrated the reactive species for tetracycline removal over 2CuO@1Fe-MFI zeolite were •OH, SO 4 • − , •O 2 − and 1 O 2 species, and moreover 1 O 2 served as the major active species. Furthermore, possible tetracycline degradation pathways over 2CuO@1Fe-MFI zeolite were proposed.
研究领域:
环境科学
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2025
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IF 4.7
Xianglong Tan,Jianwei Zhang,Yuting Zhang,Jiahuan Du,Chun Zhang,Xuehong Gu
MFI zeolite membranes are typically synthesized with the aid of an organic template, i.e., tetrapropylammonium hydroxide (TPAOH). Consequently, it is crucial to remove the template from the membrane and simultaneously minimize non-selective defects. Ozonation at low temperature has been known as a mild detemplation to produce high-selective zeolite membranes reproducibly. However, the microstructural evolution of zeolite membrane especially template molecules during ozonation remains unclear. In this study, the microstructural evolution of the TPAOH molecule in MFI zeolite during low-temperature ozonation was investigated. The thermogravimetric analysis (TGA) and N 2 adsorption results indicate the gradual reduction in the amount of template with increasing ozonation time. The Fourier-transform infrared (FT-IR) spectroscopy, in-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and 13 C nuclear magnetic resonance (NMR) results suggest the formation of new carbon species in the final zeolite. After ozonation for 8 h, ca. 87 % in mass of the template was removed from the MFI zeolite membrane. In comparison with the MFI zeolite membranes treated with air calcination, the MFI zeolite membranes detemplated in O 3 for 8 h (MFI-O 3 _8 h) exhibited a superior separation factor of 801 in para-xylene/ortho-xylene (PX/OX) separation at 150 °C, indicating fewer defects existed in the membrane. The as-synthesized membrane exhibited good separation stability during the PX/OX separation. In addition, MFI zeolite membranes were synthesized on hollow fiber supports with a length of 40 cm. These membranes showed excellent performance for xylene isomer separation (PX/OX separation factor >90).
研究领域:
材料科学
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化学工程
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膜技术
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无机化学
✓ 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）