RSC Advances
·
2014
·Vol. 4
·期 41
·21479-21491
·
IF 3.708
Quanyi Wang,Shutao Xu,Jingrun Chen,Yingxu Wei,Jinzhe Li,Dong Fan,Zhengxi Yu,Yue Qi,Yanli He,Shuliang Xu,Cuiyu Yuan,You Zhou,Jinbang Wang,Mozhi Zhang,Baolian Su,Zhongmin Liu
In this work, two kinds of mesoporous ZSM-5 were synthesized successfully using a hydrothermal methodology by utilizing different soft templates, namely, dimethyl octadecyl [3-(trimethoxysilyl)propyl]ammonium chloride ([(CH3O)3SiC3H6N(CH3)2C18H37]Cl, TPOAC) and hexadecyl trimethyl ammonium bromide (C16H33(CH3)3NBr, CTAB). The obtained mesoporous ZSM-5 samples were compared with conventional ZSM-5, and the effects of different surfactant usages during the synthesis of mesoporous ZSM-5 on the physicochemical and catalytic properties were systematically investigated. Multiple techniques, such as XRD, SEM, N2 adsorption techniques, HP 129Xe NMR, 27Al MAS NMR, 29Si MAS NMR, and 1H MAS NMR, were employed for the characterization. Although the synthesized mesoporous ZSM-5 samples had equal surface areas, they presented different relative crystallinities, morphologies, pore-size distributions, micropore–mesopore interconnectivity, framework atom coordination states and acidities. When using these synthesized ZSM-5 samples as catalysts for methanol conversion, the mesoporous ZSM-5 templated with TPOAC exhibited an extremely long catalyst lifespan compared to conventional ZSM-5, while mesoporous ZSM-5 templated with CTAB showed no advantage in prolonging the catalyst lifetime during the reaction. The differences in the catalytic lifespan and the reduction of coke deposition were correlated to the variation of acidity and porosity with the mesopore generation in the ZSM-5 catalysts by the usage of different structure-directing agents. Compared to the mesopore structure-directing agent, CTAB, with the use of TPOAC as the template and part of the Si source, mesoporous ZSM-5 could be synthesized with good mesopore–micropore interconnectivity, which accounted for the improved catalytic performance in the reaction of methanol conversion.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
FUEL
·
2020
·
IF 5.578
Chenyao Bi,Xu Wang,Qing You,Baoyu Liu,Zhuo Li,Jianbo Zhang,Qingqing Hao,Ming Sun,Huiyong Chen,Xiaoxun Ma
Five MFI-type zeolite catalysts, which were aluminosilicate ZSM-5 (Z5), gallium-substituted silicalite-1 (Ga-S1), mesoporous ZSM-5 (MZ5), gallium-substituted mesoporous silicalite-1 (Ga-MS1) and gallium-substituted mesoporous ZSM-5 (Ga-MZ5), were hydrothermally synthesized with combined using of TPAOH and TPOAC as micropore and mesopore structure-directing agents respectively, followed by the application in the catalytic upgrading of volatiles from low-rank coal fast pyrolysis. The obtained results indicated that significant improvements with the yield of high value-added products of BTEXN (benzene, toluene, ethylbenzene, xylene and naphthalene) increased from 5.4 mg.g −1 to 11.9–26.4 mg.g −1 , as well as the content of light fractions (<300 °C) in coal tars increased from 51% to 65–88% were realized by using the representative MFI-type zeolite catalysts in contrast to non-catalyst pyrolysis. Moreover, the possible mechanism for catalytic upgrading over the best-performing catalyst of gallium-substituted mesoporous ZSM-5 (Ga-MZ5) with the highest yield of aromatics and effective reduction of phenols was proposed on the basis of systematic comparison of structural features and catalytic performances of various MFI-type zeolite catalysts and fundamental study of the synergetic effects dominated by acidity, ratio of Brønsted/Lewis acid sites, intra-/extra-framework gallium species and hierarchical meso-/microporosity.
研究领域:
能源化学
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2016
·
IF 2.101
Shunyu Han,Zheng Wang,Longyue Meng,Nanzhe Jiang
Mesoporous ZSM-5 zeolites were synthesized by using hydrophilic carbon black as a hard template. Hydrophobic carbon black was oxidized with sodium hypochlorite solution then dispersed into the synthetic precursor, and hydrothermally treated by omitting the evaporation process. The samples were characterized by SEM, TEM, XRD , nitrogen adsorption/desorption and NH 3 -TPD measurements. As a result, mesoporous ZSM-5 zeolites were obtained in the morphology of single crystal like aggregates (about ∼2 μm) with intra-mesopores in the range of 5–18 nm. Textural properties and acidity of mesoporous ZSM-5 zeolites were varied by adjusting the amount of carbon black used. In the toluene disproportionation, mesoporous ZSM-5 templated by hydrophilic carbon black showed more active in toluene conversion and more selective to the para -xylene than conventional zeolite, and even comparable to the commercial zeolite catalyst.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Catalysts
·
2024
·Vol. 14
·期 7
·397
·
IF 3.8
Yuxuan Zhang,Ruibo Wei,Lin Yang,Jinming Ge,Feiyang Hu,Tingting Zhang,Fangyin Lu,Haiwang Wang,Jian Qi
The low-temperature oxidation of methane gas in coal mine exhaust gas is important for reducing the greenhouse effect and protecting the environment. Unfortunately, the carbon–hydrogen bonds in methane molecules are highly stable, requiring higher reaction temperatures to achieve effective catalytic oxidation. However, metal oxide-based catalysts face the problem of easy sintering and the deactivation of active components at high temperatures, which is an important challenge that catalysts need to overcome in practical applications. In this work, a series of Mn-Co3O4active components were grown in situ on ZSM-5 zeolite with mesoporous pore structures treated with an alkaline solution via a hydrothermal synthesis method. Due to the presence of polyethylene glycol as a structure-directing agent, manganese can be uniformly doped into the Co3O4lattice. The large specific surface area of ZSM-5 zeolite allows the active component Mn-Co3O4to be uniformly dispersed, effectively preventing the sintering and growth of active component particles during the catalytic reaction process. It is worth mentioning that the Mn-Co3O4/meso-ZSM-5-6.67 catalyst has a methane conversion rate of up to 90% at a space velocity of 36,000 mL·g−1·h−1and a reaction temperature of 363 °C. This is mainly due to the mesoporous ZSM-5 carrier with a high specific surface area, which is conducive to the adsorption and mass transfer of reaction molecules. The active component has an abundance of oxygen vacancies, which is conducive to the activation of reaction molecules and enhances its catalytic activity, which is even higher than that of noble metal-based catalysts. The new ideas for the preparation of metal oxide-based low-temperature methane oxidation catalysts proposed in this work are expected to provide new solutions for low-temperature methane oxidation reactions and promote technological progress in related fields.
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
FUEL
·
2021
·
IF 6.609
Mingjie Liao,Xin Ning,Junwen Chen,Jiajun Zheng,Wenlin Li,Ruifeng Li
Zeolite is one kind of the solid acid catalysts for the oligomerization process but surfers from rapid deactivation. In this specific study, a series of mesoporous ZSM-5 catalysts have been synthesized and evaluated in the 1-hexene oligomerization. XRD, BET, SEM, TEM, 27 Al MAS NMR, 29 Si MAS NMR, NH 3 -TPD, Py-FTIR and TGA analysis were used to characterize the physicochemical properties of zeolites. The synthesized mesoporous zeolites were found to be more stable in the reaction and the initial activity increase significantly compared with the common ZSM-5 zeolite . Moreover, the catalytic activity of mesoporous ZSM-5 zeolite is found to be closely related to the number and the distribution of acid sites. The mesoporous ZSM-5 zeolites with the lower amount of acid sites, moderate strength of Brønsted acid sites inhibiting the cracking and coke products. High L/B ratio enhanced the dimers formation. The efficiency was further highlighted by a high space–time yield (STY) of 557 mg·g cat −1 h −1 in the average stage at 260 °C. Compared to conventional ZSM-5 catalyst, the synthesized catalyst displayed excellent resistance to coke deposit.
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
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Jiaqin He,Dongyun Chen,Najun Li,Qingfeng Xu,Hua Li,Jinghui He,Jianmei Lu
Mesoporous ZSM-5 zeolite-supported PdCu alloy nanoparticle catalysts are synthesized via a facile and environmentally friendly method. The mesoporous structure is formed through the loss of carbon black particles encapsulated by zeolite crystals during calcination. The ZSM-5-supported PdCu nanoparticles are shown to possess mesoporous structure, evenly distributed PdCu alloy nanoparticles, and excellent catalytic performance in toluene oxidation. The mesoporous structure of the ZSM-5-supported PdCu nanoparticles provides a large specific surface area and pore size, resulting in numerous accessible active sites. The alloying of Pd with Cu both increases the catalytic performance of the catalyst and lowers its cost. Overall, the catalyst with a Pd/Cu ratio of 8:2 showed the highest catalytic activity of the fabricated materials, achieving 100 % toluene conversion at 160 °C. The mechanism of toluene oxidation over these catalysts can be explained by the Mars–van Krevelen model.
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
Frontiers of Chemical Science and Engineering
·
2024
·Vol. 18
·期 8
·1-12
·
IF 4.3
Chun Weilong,Yang Chenbiao,Wang Xu,Yang Xin,Chen Huiyong
A facile synthesis of hierarchical ZSM-5 with the three-dimensionally ordered mesoporosity (3DOm ZSM-5) was achieved by solid conversion (SC) of SiO 2 colloidal crystals to high-crystalline ZSM-5. The products of 3DZ5_S/C and 3DZ5_S, which were severally transformed from the carbon-padded SiO 2 colloidal crystals and the initial SiO 2 colloidal crystals, exhibited not only a similar ordered structure and acidity but also higher crystallinity and more balanced meso-/micropore combination in comparison with 3DZ5_C obtained by the conventional confined space crystallization approach. All three synthesized 3DZ5 catalysts showed improved methanol-to-propylene performance than the commercially microporous ZSM-5 (CZ5), embodied in five times longer lifetime, higher propylene selectivity and S propylene / S ethylene ratio ( P/E ), and superior coke toleration with lower formation rate of coke ( R coke ). Moreover, the 3DZ5_S catalyst in situ converted from SiO 2 colloidal crystals presented the highest selectivities of propylene (42.51%) and light olefins (74.6%) among all three 3DZ5 catalysts. The high efficiency in synthesis and in situ utilization of SiO 2 colloidal crystals demonstrate the proposed SC strategy to be more efficiently and eco-friendly for the high-yield production of not only 3DOm ZSM-5 but also other types of hierarchical zeolites.
研究领域:
材料科学
·
催化化学
·
能源化学
✓ 已验证
DOI
高影响因子
Surfaces and Interfaces
·
2024
·
IF 5.7
Jun-Qing Ye,Pin-Xi Wang,Xin Rong,Qi-Da Ding,Jun-Feng Qian,Sheng-Chun Chen,Ming-Yang He,Qun Chen
Vinylsilane compounds are essential chemical feedstocks and intermediates in organic synthesis. A heterogeneous Cu-containing mesoporous ZSM-5 zeolite catalyst developed through an in-situ doping method can be used for preparing vinylsilane compounds via decarboxylative coupling with remarkable catalytic efficiency. The mesoporous structure along with the appropriate surface area and pore volume of the catalyst is likely to be responsible for facilitating mass transfer in the reaction process. Additionally, due to the suitable Brønsted and Lewis acid active sites, adsorption and activation of reactant molecules can be readily triggered to promote the generation of alkoxyl radicals, which is the crucial species to complete the catalytic cycle. Importantly, the transformation exhibits high efficiency, broad substrate scope, and good reusability for at least six cycles.
研究领域:
有机化学
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2019
·
IF 4.63
Tingting Zhao,Fuwei Li,Hongchang Yu,Shilei Ding,Zhixia Li,Xinyuan Huang,Xiang Li,Xiaohan Wei,Zhenlin Wang,Hongfei Lin
Conversion of biomass-derived chemicals into light olefins is a promising method to maintain sustainable development of light olefin industry. In this study, three mesoporous ZSM-5 zeolites (MZSM-5-A, MZSM-5-B and MZSM-5-C) with major pore diameter about 4.8 nm, 16 nm and 22 nm were synthesized using a hydrothermal method by utilizing different templates. The catalytic activity of catalysts was studied by catalytic cracking of ethanol and oleic acid. The influence of reaction temperature on conversion and product selectivity was investigated. The characterization of ZSM-5 samples showed that the orders of the external surface area and mesopore volume were MZSM-5-C > MZSM-5-B > MZSM-5-A > conventional HZSM-5. In ethanol to light olefin reaction, MZSM-5-C achieved the highest light olefin yield (318.3 mL g −1 ) and ethylene selectivity (42.3%) at 400 °C. In oleic acid to light olefin reaction, MZSM-5-B achieved a complete conversion of oleic acid at 500 °C, and obtained the highest light olefin selectivity (38.1%) at 550 °C. The difference may be relevant to the size and chemical structure of feedstock molecular as well as the acidity of catalysts. Regardless of ethanol or oleic acid as feedstock, introduction of mesopore in zeolites significantly enhanced the light olefin yield and selectivity.
研究领域:
化学工程
·
催化
·
材料科学
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 37
·22126-22136
·
IF 3.119
Hongchang Yu,Fuwei Li,Wen He,Caifeng Song,Yansong Zhang,Zhixia Li,Hongfei Lin
Micro–mesoporous ZSM-5 with different Si/Al ratios (MZ-X, X = 27, 80, 150) were synthesized by adding microcrystalline cellulose (MCC) as co-template into the hydrothermal synthesis process of zeolites. The resultant ZSM-5 were used for catalytic cracking of high density polyethylene (HPDE) and polypropylene. It was found that introduction of MCC significantly enhanced the formation of mesopores and strong acid sites. MZ-27 achieved the highest oil yield: 21.5% for HPDE and 32.1% for polypropylene, and the light aromatics (BTEX) selectivity therein were 87.6% and 79.7%, respectively. HZ-150 (MCC-free ZSM-5, Si/Al = 150) achieved the highest gas yield: 85.4% for HDPE and 76.7% for polypropylene, and the light olefins (C2–4) selectivity therein were 44% and 48.3%, respectively. The dense acidic sites and mesoporous structure of MZ-27 were responsible for its better activity for producing aromatic products. The moderate acidity and microporous structure of HZ-150 were helpful for producing light olefins from catalytic cracking of polyolefin plastics.
研究领域:
材料科学
·
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）