MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Tao Jiang,Fumin Wang,Xubin Zhang,Yi Zhai,Guojun Lv,Yu Shen,Yuzhou Wu
Mesocrystal zeolite with well-defined morphology owns mesoporous channels and single crystal characteristics, which could promote diffusion efficiency, stability and catalytic activity. Thus, we performed the controllable synthesis of ZSM-5 mesocrystal without special additives and complex methods. Selected area electron diffraction (SAED) and fast Fourier transform (FFT) showed diffraction spots regardless of crystallization time, which indicated the well oriented feature of synthesized ZSM-5 zeolites. The crystallization process was further investigated. The oriented particle attachment (OPA) effectively guided the synthesis process of mesocrystals, which followed the nonclassical crystallization mechanism. The crystallinity curve exhibited valley-like shape, which manifested that the crystallization pathway went through three stages: fast precipitation, deconstruction and reorganization. The plausible formation mechanism was proposed, which might be useful for the fabrication of ZSM-5 mesocrystal. The prepared zeolites showed superior catalytic performance in aldol condensation reaction between benzaldehyde and 2-hydroxyacetophenone, obtaining 93% of the conversion.
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
CHEMISTRY-A EUROPEAN JOURNAL
·
2020
·Vol. 26
·期 28
·6147-6157
·
IF 4.857
Zhaoqi Ye,Yang Zhao,Hongbin Zhang,Yahong Zhang,Yi Tang
Graphical Seed-induced synthesis : Basic mesoporous ZSM-5 with adjustable alkaline-earth metal species have been synthesized by an acid co-hydrolysis and seed-induced method. Its mesostructure together with the high dispersity of basic guest species was realized by this non-classical crystallization process. For zeolite catalysts, the regulation of active site and pore structure plays an important role in the enhancement of their catalytic performance. In this work, a one-pot and organic template-free co-regulation route is proposed to straightforwardly synthesize basic mesoporous ZSM-5 zeolites with adjustable alkaline-earth metal species. The synthesis pathway combines two decisive strategies: 1) the seed-induced interface assembly growth method and 2) the acidic co-hydrolysis/condensation of aluminosilicate species and alkaline-earth metal (e.g., Mg, Ca, Sr, or Ba) sources. It is interesting that the mesoporous structure was self-evolved through particle-attached seed-interfacial crystallization without the assistance of any template. Meanwhile, the incorporation of alkaline-earth metals species is homogeneous and highly dispersed in the solid products during the whole crystallization process, and finally generate the superior basicity. Catalysis tests of the as-synthesized samples displayed their novel performance in the typical base reaction of Knoevenagel condensation, even for bulky substrates owing to the enhanced diffusion arising from the meso/microporous network. This finding opens new possibilities for facile, cost-effective, and environmentally friendly synthesis of mesoporous high-silica zeolites with tunable acid/base properties, and deepens our understanding of the particle-attached crystallization.
研究领域:
材料科学
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催化化学
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产品关联
DOI
PubMed
高影响因子
APPLIED CLAY SCIENCE
·
2024
·
IF 5.3
Fengya Ran,Meng He,Shiyong Sun,Rui Lv,Sen Lin,Ke Wang,Yevgeny Aleksandrovich Golubev,Olga Borisovna Kotova,Elena Leonidovna Kotova
Zeolite products synthesized from mineral materials are receiving widespread attention, while there are few reports on the introduction of heteroatom metals from minerals into zeolites. Herein, the effects of different silicon sources, hydrothermal reaction time and the amount of template on the crystallisation of Fe-ZSM-5 were investigated. The morphology and structure of ZSM-5 were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray electron spectroscopy (XPS) and scanning electron microscopy (SEM). The catalysis of 3,3′,5,5′-tetramethylbenzidine (TMB) by Fe-ZSM-5 was then carried out to evaluate its enzyme-like catalytic performance as a type of nanozyme catalyst. The results showed that Fe-ZSM-5 exhibited peroxidase-like activity, oxidizing TMB into a colored substance in the presence of hydrogen peroxide (H 2 O 2 ). Kinetic analysis implied that, compared with natural horseradish peroxidase (HRP), Fe-ZSM-5 peroxidase mimics exhibit inferior affinity and enzymatic catalytic velocity towards the TMB substrate. However, it exhibited excellent stability under extreme pH, temperature, and ionic strength conditions. This work provides a possible reference for the construction of functional nanozymes using natural mineral resources.
研究领域:
材料科学
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催化化学
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生物医学工程
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产品关联
DOI
高影响因子
Catalysts
·
2022
·Vol. 12
·期 10
·1216
·
IF 4.501
Xiaoling Zhao,Jinlong He,Jinjin Li
A method of phase-transfer water/toluene synthesis was developed to fabricate mesocrystals of Zeolite Socony Mobil-5 (ZSM-5) that contain both meso-/micropores and nanometer crystallites. The construction of a hierarchical architecture from nanozeolites via oriented attachment growth was achieved by a simple phase-transfer water/toluene synthesis by minimizing classical atom-by-atom crystallization. This opens the way to the cheap, highly efficient engineering of zeolitic morphologies. The physicochemical properties of the crystal were revealed by powder X-ray diffraction (XRD), N2physical adsorption, inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ammonia temperature-programmed desorption (NH3-TPD) and pyridine infrared spectroscopy (Py-IR), indicating that the material has a high specific surface area, mesopore volume and Lewis acid content. The hierarchical ZSM-5 exhibits a prolonged catalytic lifetime in dimethyl ether–methyl ether (DTO) conversion and enhanced selectivity for propylene owing to the enhanced structural properties. The method can be extended to the synthesis of other graded zeolites controlled by the crystallization process and produce crystals comprising traversing mesoporosity and ultrasmall crystallites that are crucial for mass transfer enhancement.Keywords:phase-transfer water/toluene synthesis;ZSM-5;hierarchical architecture;dimethyl ether–methyl ether
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Tingjun Fu,Lihan Jia,Guoqiang Hou,Zhong Li
Dealuminization over aluminium-containing ZSM-5 could create silanol nests and improve catalytic activity for alkylation of toluene with methanol. However, obviously damaged microporous structure seriously accelerated catalyst deactivation. Here, we demonstrate highly stable alkylation on ZSM-5 by deboronation treatment over boron-containing ZSM-5. 11 B MAS NMR, 1 H MAS NMR and OH-IR suggested that silanol nests with hydrogen bonds were created at the expenses of the removal of skeleton-B atoms. The formed silanol nests promote the adsorption of toluene, inhibit the methanol self-reaction and corresponding the deep alkylation process. Therefore, alkylation efficiency and toluene conversion could reach 70.8% and 33.5%, respectively. Importantly, the microporous structure of deboronized ZSM-5 was well maintained during deboronation, which determined a greatly improved catalytic stability compared with that of traditional dealuminized ZSM-5. Moreover, the deboronized ZSM-5 still presented relatively good catalytic stability under a higher methanol feedstock although the coke deposition was accelerated.
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
Journal of Water Process Engineering
·
2024
·
IF 6.3
Jing Li,Suxia Ma,Nuo Xu
The pursuit of carbon peaking and carbon neutrality goals necessitates flexible operation and deep peaking of coal-fired units, thus placing heightened demands on nitrogen oxide (NO X ) emission control. Fly ash, a solid waste rich in silicon (Si) and aluminum (Al), should be fully leveraged, and the high-value synthesis of zeolite represents a viable utilization method. In this context, fly ash-based zeolite was prepared as a catalyst to facilitate the generation of active oxides from H 2 O 2 , combined with alkali solution absorption, to achieve efficient denitrification. This approach effectively transforms ‘waste to pollution’ mitigation. The optimal synthesis conditions for FA-ZSM-5 zeolite were established using the alkali fusion hydrothermal synthesis method, with fly ash as the raw material. The specified conditions were NaOH/FA = 1.2, SiO 2 /Al 2 O 3 = 40, H 2 O/Al 2 O 3 = 1325, TPAOH/Al 2 O 3 = 10, ZSM-5-seed addition of 5 %, and a hydrothermal temperature and time of 140 °C for 24 h. Experimental parameters were meticulously investigated to ascertain their impact on nitric oxide (NO) removal efficiency. The highest removal efficiency was achieved under specific conditions: a reaction temperature of 140 °C, an H 2 O 2 concentration of 6 %, a catalyst dose of 0.3 g, an NO concentration of 600 mg/m 3 , and an SO 2 concentration of 1000 mg/m 3 . Finally, analysis of the catalytic oxidation mechanism revealed that H 2 O 2 , when catalyzed by FA-ZSM-5 zeolite, generates ·OH radicals with strong oxidizing properties, thereby facilitating the oxidative removal of NO.
研究领域:
环境科学
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材料科学
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催化化学
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产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2014
·Vol. 16
·期 5
·2580-2586
·
IF 6.852
Anqing Zheng,Zengli Zhao,Sheng Chang,Zhen Huang,Kun Zhao,Hongxiang Wu,Xiaobo Wang,Fang He,Haibin Li
We firstly propose the coupling conversion of bio-derived furans and methanol over ZSM-5 for enhancing aromatic production. The coupling conversion of bio-derived furans and methanol was conducted in a continuous fixed bed reactor. 2-Methylfuran (MF) was used as a probe molecule to identify the possible reaction pathways. The effects of the methanol to MF molar ratio, reaction temperature and weight hourly space velocity (WHSV) on the product distribution from the coupling conversion of MF and methanol were investigated. The experimental results showed that the aromatic yield from the coupling conversion of MF and methanol is about 5.2 times higher than that of the catalytic fast pyrolysis of only MF. In addition, it can also enhance the yield of olefins, the selectivity of xylenes and reduce coke formation. These results indicate that there is a significant synergistic effect between MF and methanol. The synergistic effect could be attributed to the methanol-to-olefins reactions, the Diels–Alder reactions of furans with olefins, and the alkylation reaction of benzene/toluene with methanol occurring during the coupling conversion of MF and methanol. The reaction conditions for maximizing the synergistic effect were a methanol to MF molar ratio of 2 at 550 °C. Moreover, the comparative study of the coupling conversion of different bio-derived furans (MF, 2,5-dimethylfuran (DMF), furfural (FF) and furfuryl alcohol (FA)) and methanol were also considered in this study. The coupling conversion of DMF and methanol exhibited maximum yields of aromatics, olefins and a minimum yield of coke, suggesting that DMF is the best candidate of bio-derived furans for aromatic production in the coupling conversion of bio-derived furans and methanol.
研究领域:
能源化学
·
催化反应工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Xiao-Yan Zhao,Xue-Yu Ren,Yan-Jun Wang,Jing-Pei Cao,Zi-Meng He,Nai-Yu Yao,Hong-Cun Bai,Hou-Luo Cong
Direct conversion of lignite into light aromatics via catalytic fast pyrolysis is a great challenge because of severe catalyst deactivation and low aromatics yield. The tandem catalysis (1Zn@MCM-41 and ZSM-5) system was employed to promote the conversion of thermally-derived volatiles of lignite into aromatics at 600 °C. The mesoporous Zn-incorporated MCM-41 (xZn@MCM-41) with different doping amount of Zn was prepared with a one-pot hydrothermal procedure. The structure and the dispersion of Zn species of 1Zn@MCM-41 were systematically studied with XRD, SEM, BET, NH 3 -TPD and so on. The presence of 1Zn@MCM-41 significantly expands the lifetime of the microporous ZSM-5. Meanwhile, the yield of aromatics, especially benzene, is also increased to some extent. The content of the long-chain hydrocarbons and the phenolic compounds are decreased significantly after being cracked by the mesoporous 1Zn@MCM-41. More small molecules are able to contact with the active sites located in the micropores of ZSM-5 with the presence of Zn@MCM-41. In addition, the ZSM-5 in the tandem catalysts system presents an excellent stability. Therefore, this meso -microporous tandem catalysis system promotes the preferential cracking of macromolecular compounds, the cracked small molecules generated from which then contact with ZSM-5 to produce aromatics. This work provides a new perspective for the gradient catalyzing lignite-derived volatiles over a tandem catalysis system.
研究领域:
能源化学
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2024
·
IF 2.8
Haoyu Liu,Jingye Ma,Hong Yuan,Xiang Shi
BACKGROUND A series of Pt@NZSM–5 and Pt/NZSM–5 nanosheets having different Si/Al ratios were prepared via an in situ synthesis and impregnation method, respectively, using C 22 H 45 –N + (CH 3 ) 2 –C 6 H 12 –N + (CH 3 ) 2 –C 6 H 13 (C 22–6–6 ) as the template agent. The oleic acid decarboxylation reaction was carried out using these materials under CO 2 atmosphere and the oleic acid cracking mechanism was inferred from the product distribution of the C8-C17 alkanes. RESULTS The Pt@NZSM–5 and Pt/NZSM–5 was found to comprise thinner nanosheets and exhibited strong metal–substrate interactions. Pt@NZSM–5 nanosheets with a Si/Al molar ratio of 100 had thicknesses of only 8–9 nm along with a mesopore/micropore capacity ratio of 2.7, an acid content of 11 cm 3 /g STP and a high Pt 0 /PtO x ratio. CONCLUSION The Pt@NZSM-5 and Pt/NZSM-5 nanosheets had an interconnected hierarchical system and a large number of metal active sites that facilitated the decarboxylation of oleic acid. The Pt@NZSM–5 nanosheets demonstrated excellent catalytic activity during the cracking of oleic acid under a CO 2 atmosphere, giving a yield of C8–C17 alkanes as high as 83.8% after 5 h at 320 °C. These Pt@NZSM–5 nanosheets also showed greater stability than the Pt/NZSM–5 specimens. © 2024 Society of Chemical Industry (SCI).
研究领域:
催化化学
·
能源材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Mei Ren,Jun Li,Manhong Huang,Donghui Chen,Xuelian Chen,Qi An,Songmei Sun
The escalating environmental issues resulting from waste plastic necessitate innovative decomposition methods that optimize conversion rates and product selectivity. In this study, we demonstrate that linear low-density polyethylene (LLDPE) can be effectively hydrothermolyzed into C1 − C4 compounds with a selectivity of 100 % in the presence of trace water on H-ZSM-5 catalyst under a relatively low temperature of 220 °C. Water plays a dual role here as both a solvent and a reactant. It was found the density of Brønsted acid sites is crucial for LLDPE decomposition, serving as the primary active centers for cracking LLDPE chains. In-situ EPR studies indicate a synergistic mechanism of free radical and carbenium ion pathways in LLDPE depolymerization. Density Functional Theory (DFT) simulations show that the depolymerization starts with the cleavage of a C–C bond in polyethylene, instigated by a hydrogen radical from the Brønsted acid site, leading to various intermediate stages for the formation of tert -butanol, acetone and acetic acid from two potential pathways. The presence of water is crucial in these pathways, aiding bond breakages and the creation of oxygenated products in the Brønsted acid site. This study represents a substantial leap forward in sustainable methodologies for upcycling plastic waste.
研究领域:
环境科学
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催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Jia Ding,Yuanhao Wu,Shurong Wu,Shengyu Zhou,Yulong Li,Chao Fan,Hanxiao Liu,Penghui Ren,Shengwei Deng,Jianguo Wang
The direct carbonylation of glycerol with CO 2 is an alternative route to produce high-valued glycerol carbonate, which however faces challenges like low catalytic conversion due to the thermodynamic equilibrium limitation. In this work, ZSM-5 membranes with different Si/Al molar ratios were prepared by hydrothermal method, and coupled with Ce–La–Co mixed metal oxide (CeLaCo-MMO) catalysts for enhancing the glycerol carbonylation performance by in situ water separation. The Si/Al ratio of ZSM-5 showed significant influences on the water permeance, separation selectivity, and catalytic performance for glycerol carbonylation, due to the precise concentration control of Na + gated water transport channels. The reaction-separation coupling process achieved a glycerol conversion of 40.1 %, which was about 4.5 times higher than the conventional batch reactor. The as-synthesized ZSM-5 membrane also exhibited good reusability performance in the cycling test. This work provides a new in-situ water separation strategy for boosting glycerol carbonylation performance without consuming chemical or physical dehydrating agents as compared to the investigations in the literature.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Advances in Materials Science and Engineering
·
2022
·Vol. 2022
·期 1
·7408284
·
IF 2.098
Zhenhao Wei,Yufan Ji,Yiping Huang,Jingjing Huang,Yunguo Huang,Changhai Yue,Junzhou Li,Mingwei Tang,Yunfang Liu,Hanfei Liu,Hao Zhu,Kai Zhu,Fan Yang,Xuedong Zhu
Zinc (Zn) and cerium (Ce) modified hierarchical ZSM-5 (HZ) catalysts were prepared by incipient wetness impregnation, and their catalytic performances in methanol to aromatics reaction were evaluated in a fixed-bed reactor operating at 400°C under 0.1 MPa and WHSV of 1.0 h −1 . The structure, acidity, and state of Zn species of the Zn/Ce modified HZ catalysts were investigated via several characterization techniques, including XRD, NH 3 -TPD, H 2 -TPR, nitrogen adsorption, and XPS. The results showed that the aromatization activity of 2 wt% Zn-modified HZ (2% Zn/HZ) could be significantly enhanced by loading 0.6 wt% Ce, which was mainly attributed to the increase in surface ZnOH + species. Moreover, it was found that Ce inhibited pore blockage caused by Zn. Consequently, compared to 2% Zn/HZ, 2% Zn-0.6% Ce/HZ exhibited higher aromatic selectivity and longer catalyst lifetime.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）