MICROPOROUS AND MESOPOROUS MATERIALS
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2020
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IF 4.551
Haoyang Zhang,Xiaotong Yang,Xiaojing Song,Xinyu Chang,Mingjun Jia
A series of tungsten-tin bimetallic MFI type zeolites (WSn-MFI) with different Sn and W contents were hydrothermally synthesized using tetrapropyl ammonium hydroxide (TPAOH) as a template and polypyrrolidone as a co-surfactant. Tetraethylorthosilicate (TEOS), ammonium tungstate hydrate and tin (IV) chloride pentahydrate were used as the Si, W and Sn sources, respectively. The resultant samples were characterized by various techniques, and were evaluated as catalysts for the epoxidation of cyclohexene with hydrogen peroxide. The results reveal that all the W–Sn bimetallic zeolites have the typical MFI structure, and their relative crystallinities and morphologies change somewhat with the variety of W and Sn contents. Both the isolated framework SnO 4 species and the extra-framework SnO 2 species could be detected in all WSn-MFI samples, while only trace amount of extra-framework W species are present inside the channels/cages of the bimetallic zeolites. Compared with the monometallic zeolites of W-MFI and Sn-MFI, the bimetallic WSn-MFI zeolites exhibit much higher catalytic activity for the epoxidation of cyclohexene. Of these, the sample named WSn-MFI-a could efficiently convert cyclohexene to the corresponding epoxide with a high yield of 79% under an optimized reaction condition. A synergistic effect between the W and Sn species should play critical role in improving the catalytic activity and the epoxide selectivity of the bimetallic zeolite catalysts.
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Catalysts
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2018
·Vol. 9
·期 1
·13
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IF 3.465
Jianguang Zhang,Xiangping Li,Juping Liu,Chuanbin Wang
In this paper, a comparative study of MFI zeolite derived from different silica sources is presented. Dry gel conversion (DGC) method is used to synthesize silicalite-1 and ZSM-5 with MFI structure. Two kinds of silica sources with different particle sizes are used during the synthesis of MFI zeolite. The as-prepared samples were characterized by X-ray diffraction (XRD), N2-sorption, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray fluorescence spectrometer (XRF). From the characterization results, it could be seen that the high-quality coffin-like silicalite-1 was synthesized using silica sphere with particle size of 300 nm as silica source, with crystallization time being shortened to 2 h. The schematic diagram of silicalite-1 formation using silica sources with different particle sizes is summarized. ZSM-5 was obtained by adding Al atoms to raw materials during the synthesis of MFI zeolite. The performance of aqueous phase eugenol hydrodeoxygenation over Pd/C-ZSM-5 catalyst is evaluated.Keywords:dry gel conversion;MFI zeolite;particle sizes;silica sources;hydrodeoxygenation
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FUEL
·
2018
·
IF 4.908
Wenzhi Li,Mingxue Su,Tingwei Zhang,Qiaozhi Ma,Wei Fan
Liquid fuel intermediates can be produced via aldol condensation reactions between furfural and acetone. It was found that potassium-promoted Lewis acid zeolite Sn-MFI performed superior catalytic performance for C C bond coupling by aldol condensation reactions of furfural with acetone. The presence of K in Sn-MFI catalyst improves the catalytic activity of the catalyst likely due to increased basicity. The product distribution of aldol condensation was also changed remarkably with the addition of K. Besides 4-(2-furyl)-3-buten-2-one (FAc), 1, 5-di-2-furanyl-1, 4-pentadien-3-one (F 2 Ac) was also formed in the existence of K compared with pure Sn-MFI. It was also found that the K-promoted Sn-MFI catalyst is more resistant to water and exhibits enhanced selectivity to F 2 Ac.
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RSC Advances
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2024
·Vol. 14
·期 36
·26604-26610
·
IF 3.9
Xiaodi Zhang,Xiyuan Tong,Junyang Wang,Xinyu Zhu,Zhuozhe Li,Fang Fang,Kun Qian,Yifeng E
We have prepared a highly active and stable copper-doped nickel electrocatalyst. Cu/Ni-doped MFI-type protozeolite layered nanoclusters electrodes have a large electrochemically active surface area (ECSA) and good HER activity, as well as excellent durability. The addition of Cu greatly increases hydrogen evolution reaction (HER) activity under acidic conditions. At the same time, the in situ grown Cu2+1O provides some activity, and in addition, the interface constructed between Cu and Ni further generates sufficient electrochemically active surface area. The activated Cu/Ni-doped MFI-type layered nanoclusters required only a 385 mV overpotential to generate 10 mA cm−2, demonstrating efficient and stable activity with potential practical applications.
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PubMed
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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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
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CHEMICAL ENGINEERING JOURNAL
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2026
·
IF 12.5
Jialun Shi,Yuncai Liu,Xin Pu,Xin Han,Lei Ye,Xinglong Qin,Hongbin Zhang,Jichang Liu
Atomic-Level Nb Engineering: isolated Nb sites with ~4.8 average coordination number. • Tailored Acidic Landscape and Synergistic Catalysis: medium-strength sites and balanced Lewis/Brønsted ratio selectively boosts alkylation over disproportionation, overcoming the activity-selectivity-stability trilemma. • Superior Catalytic Performance: 39.0% conversion , 58.2% durene selectivity, and 704.7 mg·g cat -1 ·h -1 space-time yield, outperforming conventional catalysts. • Structural Robustness and Practicality: excellent regenerability, structural robustness and stable framework-Nb chemical state over six reaction-regeneration cycles. The selective alkylation of 1,2,4-trimethylbenzene (pseudocumene) to durene represents a pivotal route for C 9 aromatic valorization, yet it is constrained by an inherent activity-selectivity-stability trade-off in conventional HZSM-5 catalysts. Herein, we break this limitation by engineering synergistic Brønsted and Lewis acid sites within an MFI zeolite via the atomic dispersion of low-loading niobium (Nb). A one-step hydrothermal method successfully incorporates Nb into the framework, creating isolated Nb sites with an average coordination number of ∼4.8. This unique structure generates medium-strength acidity and a balanced Brønsted-to-Lewis acid ratio, which are crucial for the selective methylation pathway. The optimized catalyst (Nb/Si ≈ 5.67‰) achieves a remarkable 1,2,4-trimethylbenzene conversion of 39.0% with 58.2% durene selectivity (98.0% among tetramethylbenzenes) and a high space-time yield of 704.7 mg·g cat −1 ·h −1 under optimal conditions (390 °C, 0.8 MPa). Comprehensive characterization and stability tests confirm the structural integrity and regenerability of the catalyst. This work demonstrates a rational design strategy for zeolite catalysts through precise heteroatom modulation, offering broad implications for aromatic upgrading and related tandem processes. Download: Download high-res image (131KB) Download: Download full-size image
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INORGANIC CHEMISTRY
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2024
·
IF 4.3
Zhe Hong,Lihua Deng,Fanglin Wang,Fangyu Zhu,Yingsen Fang,Li Song,Lei Li,Zhirong Zhu
ZSM-5 zeolites with accessible micropore architecture and tunable acid–base sites are important shape-selective catalysts. However, the presence of exposed straight channels and the external acid–base sites of conventional ZSM-5 has a negative impact on shape selectivity. Herein, we report on the direct synthesis of an intergrowth ZSM-5 zeolite mimicking the mortise–tenon joints. It can be revealed by various methods that the mortise–tenon ZSM-5 shows an inverse Al gradient from the surface to the core of the zeolite. More importantly, the sinusoidal channels predominantly opened to their external surfaces are constructed. The shape-selective capability of the ZSM-5 zeolite has been fully exploited due to the intrinsic inert external surface and unique sinusoidal channel features, thereby resulting in high styrene selectivity (>90%) and good catalytic stability (>100 h) in the toluene side-chain alkylation reaction. In addition, in situ DRIFTS confirms that this intergrowth ZSM-5 contributes to the formation of more active intermediates of HCOO* and H3CO*, which is another reason responsible for the superior performance.
研究领域:
材料科学
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催化化学
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无机合成
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JOURNAL OF CATALYSIS
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2022
·
IF 8.047
Haoyu Li,Pengfei Wu,Xianquan Li,Jifeng Pang,Shangru Zhai,Tao Zhang,Mingyuan Zheng
High-performance MFI zeolite supported nickel catalysts were prepared by the ammonia evaporation method for maleic anhydride (MA) conversion to γ-butyrolactone (GBL). According to comprehensive characterizations, the Ni catalysts possessed petal-like morphology and hierarchical structures with meso and micro pores. Nickel species were highly dispersed on the silica support and generated abundant Lewis acid sites (LAS), which effectively activated carbonyl groups in the reactant and accounted for the high activity in MA hydrogenation. Zr species hydrothermally introduced into the catalyst increased the number of LAS and decreased the apparent activation energy for the reaction. The highest GBL yield reached 95.6% over 40Ni-2Zr-MFI with the assistance of 3A zeolite to in-situ remove water byproduct. The catalyst showed reasonably good stability in five-cycle operation thanks to the strong interaction between Ni and support. The reaction route for MA hydrogenation was investigated, in which succinic anhydride (SA-A) served as the major reaction intermediate for GBL formation.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 24
·3263-3270
·
IF 3.474
He Ding,Xiuxiu Ni,Yixiao Zhang,Jingshuang Zhang,Zhouliangzi Zeng,Menglin Qi,Peng Bai,Xianghai Guo
High-aspect ratio b-oriented MFI nanosheets are synthesized by simply adding a suitable amount of graphene oxide (GO) nanosheets into a multilamellar MFI zeolite crystallization system. The GO nanosheets, serving as the building blocks for oriented attachment and in situ nucleation sites, positively induce the silicalite-1 nanosheet crystallization process and confine the over-growth of MFI crystals during the subsequent preparation. A two-dimensional (2D) induction mechanism of the GO nanosheets is discussed for the generation of the b-oriented MFI nanosheets. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), nitrogen adsorption, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA).
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CHINESE JOURNAL OF CATALYSIS
·
2025
·
IF 17.7
Neng Gong,Quanzheng Deng,Yujiao Wang,Zitao Wang,Lu Han,Peng Wu,Shun'ai Che
Designing Fischer-Tropsch synthesis (FTS) catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge. Herein, we selectively introduced Co nanoparticles (NPs) into the micropores and mesopores of an ordered mesoporous MFI zeolite (OMMZ) through impregnation, which controlled the carbon number distribution in the FTS products by tuning the position of catalytic active sites in differently sized pores. The Co precursors coordinated by acetate with a size of 9.4 × 4.2 × 2.5 Å and by 2,2 ‘ -bipyridine with a size of 9.5 × 8.7 × 7.9 Å, smaller and larger than the micropores ( ca. 5.5 Å) of MFI , made the Co species incorporated in OMMZ's micropores and mesopores, respectively. The carbon number products synthesized with the Co NPs confined in mesopores were larger than that in micropores. The high jet and diesel selectivities of 66.5% and 65.3% were achieved with Co NPs confined in micropores and mesopores of less acidic Na-type OMMZ, respectively. Gasoline and jet selectivities of 76.7% and 70.8% were achieved with Co NPs confined in micropores and mesopores of H-type OMMZ with Brönsted acid sites, respectively. A series of characterizations revealed that the selective production of diesel and jet fuels was due to the C–C cleavage suppressing of heavier hydrocarbons by the Co NPs located in mesopores.
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ENERGY & FUELS
·
2025
·
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%).
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Journal of Energy Chemistry
·
2023
·
IF 13.1
En-Hui Yuan,Yiming Niu,Xing Huang,Meng Li,Jun Bao,Yong-Hong Song,Bingsen Zhang,Zhao-Tie Liu,Marc-Georg Willinger,Zhong-Wen Liu
Oxidative dehydrogenation of propane with carbon dioxide (CO 2 -ODP) characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO 2 to valuable CO. However, the existing catalyst is limited due to the poor activity and stability, which hinders its industrialization. Herein, we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles (NPs) as bifunctional catalysts (NPs@Zn-MFI) for CO 2 -ODP. Characterization results reveal that the Zn 2+ species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt, Rh, or RhPt are highly dispersed in the zeolite crystals. The isolated Zn 2+ cations are very effective for activating the propane and the small NPs are favorable for activating the CO 2 , which synergistically promote the selective transformation of propane and CO 2 to propylene and CO. As a result, the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield, satisfactory CO 2 conversion, and long-term stability. Moreover, considering the tunable synergetic effects between the isolated cations and NPs, the developed approach offers a general guideline to design more efficient CO 2 -ODP catalysts, which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn 4+ cations for Zn 2+ cations in the MFI zeolite matrix.
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