ENERGY & FUELS
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2023
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IF 5.3
Haifeng Tian,Zhiyu Chen,Xing Yang,Peng Gao,Chunxue Jiao,Fei Zha,Yue Chang,Hongshan Chen
A method for the direct synthesis of hierarchical zeolites was developed by converting precursors of zeolites and mesoporous copolymers into homogeneous gels using conventional block copolymers as scaffolds. In this method, hydrothermal synthesis is accomplished on a steam-assisted basis, and the dry gel leaves the system free of the liquid water phase, which successfully avoids phase separation between the soft stencil and the solid silica phase. The catalytic performance of hierarchical zeolites was evaluated on a fixed-bed reactor for the methanol-to-aromatics reaction. The hierarchical structure greatly enhances the catalytic activity of the probe reaction due to the increased outer surface, decreased coke formation, and diffusion resistance in the microporous network. The selectivity of BTX reached 65.8%, and there was no significant deactivation after a reaction of 107 h. The transition state and energy barrier for methanol to aromatics were obtained by the minimum energy search of the LST/QST transition state.
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高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2023
·Vol. 30
·期 32
·78988-79000
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IF 5.8
Dong Jiayu,Song Xianni,Zhang Shuchi,Tan Mengyu,Zhao Haiyan,Wu Donglei
A novel hierarchical Cu/ZSM-5 was prepared over alkaline treatment and incipient wet impregnation method for the catalytic ozonation of polyvinyl alcohol (PVA). Under the optimum preparation conditions, hierarchical Cu/ZSM-5 exhibited an excellent mineralization performance during the PVA degradation process, and the removal rate of TOC after 60 min of reaction was 47.86%, much higher than that of ozonation alone (5.40%). Its high catalytic activity could attribute to the large pore volume (0.27 cm 3 /g) and pore size (6.51 nm) which are beneficial for the distribution of loaded copper and adsorption performance for PVA. Compared to ·OH, 1 O 2 (2.66 times in 10 min) contributed more to the removal of PVA. The degradation of PVA was a combined process of direct ozone oxidation, catalytic ozonation and adsorption. With its high catalytic performance and stability, hierarchical Cu/ZSM-5 has a very broad application prospect in the process of catalytic ozonation of refractory pollutants.
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PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
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2019
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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.
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高影响因子
BIORESOURCE TECHNOLOGY
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2018
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IF 5.807
Leilei Dai,Yunpu Wang,Yuhuan Liu,Roger Ruan,Dengle Duan,Yunfeng Zhao,Zhenting Yu,Lin Jiang
Catalytic fast pyrolysis (CFP) of torrefied corn cob using Ni-modified hierarchical ZSM-5 catalyst was conducted in this study. The prepared catalysts were characterized by N 2 adsorption and desorption (N 2 -BET), X-ray diffraction (XRD), and temperature-programmed desorption of NH 3 (NH 3 -TPD). NaOH solution treatment resulted in the lower peak intensities of hierarchical ZSM-5 catalyst in the XRD patterns while Ni modification improved the catalyst framework. In addition, NaOH solution treatment created some mesopores or macropores, but the incorporation of Ni reduced BET surface area and volume of micropores. Though the addition of Ni lowered the acidity of catalyst, Ni-modified hierarchical ZSM-5 catalyst led to higher yields and of aromatic hydrocarbons. What is more, hierarchical ZSM-5 catalysts significantly improved the selectivities of mono-aromatics. Kinetic analysis shows that CFP of torrefied corn cob was second-order reaction and the addition of Ni can obtain a lower activation energy compared with hierarchical ZSM-5 catalyst.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Zhen Zhang,Jiang Wu,Bin Li,Huibin Xu,Dongjing Liu
Zeolite (ZSM-5), as a kind of carbon-free sorbent or catalyst, has been widely applied in many fields due to its big surface area, good chemical and thermal stability, and excellent adsorption performance. In this study, Mn-Fe modified ZSM-5 are synthesized via sol-gel approach and employed for elemental mercury (Hg 0 ) removal from simulated flue gas at low temperature. The results show that pure ZSM-5 shows poor mercury capture ability with Hg 0 removal efficiency of ~8.5–18.8% at 100–300 °C. Mn or Fe modification can both efficiently enhance the Hg 0 removal efficiency of the ZSM-5. The sorbent with Mn/Fe molar ratio of 1:2 exhibits the optimal mercury capture ability with the highest Hg 0 removal efficiency near 100% at temperatures of 200 and 250 °C due to the significant synergy effect between Mn 2 O 3 and Fe 2 O 3 . The presence of NO has a negligible effect on the Hg 0 removal performance of Mn/ZSM-5 and Mn1Fe2/ZSM-5, while the existence of SO 2 considerably degrades the Hg 0 capture performance of Mn/ZSM-5 owing to competing adsorption and side reactions. Fe addition can protect Mn active sites from SO 2 poisoning and thereby enhancing the SO 2 resistance of Mn/ZSM-5 to some extent.
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高影响因子
CATALYSIS COMMUNICATIONS
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2018
·
IF 3.463
Qinqin Wang,Mingyuan Zhu,Haiyang Zhang,Caixia Xu,Bin Dai,Jinli Zhang
Zr-modified ZSM-5 zeolite was successfully prepared, and Zn/Zr-ZSM-5 was employed as a catalyst for the acetylene hydration reaction. High catalytic activity, above 96% C 2 H 2 conversion, was achieved at 260 °C with a feed reactant ratio of H 2 O/C 2 H 4 = 4 and a GHSV of 90 h −1 . To understand the influence of zirconium addition in the zeolite, Fourier-transform infrared spectroscopy, X-ray diffraction, surface texture analysis (BET method), transmission electron microscopy, temperature programmed desorption of NH 3 , temperature programmed reduction by hydrogen and X-ray photoelectron spectroscopy techniques were used. The incorporation of zirconium in the zeolite enhanced Zn metal dispersion and metal–support interactions. Moreover, an enhanced concentration of weak acid sites and active catalytic sites were found to be responsible for the high catalytic activity of Zn/Zr-ZSM-5 for the acetylene hydration.
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高影响因子
JOURNAL OF CATALYSIS
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2017
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IF 6.844
Qiguang Dai,Qin Zhu,Yang Lou,Xingyi Wang
ZSM-5 zeolites (NaZSM-5, HZSM-5 and Silicalite-1) with different acid nature were synthesized and used as supports of Pd catalysts for catalytic combustion of methane. Moreover, the acid property of the as-synthesized Pd/NaZSM-5 catalyst was adjusted by a NH 4 + ion-exchange process to post-generate Brønsted acid sites and different preparation methods were investigated. The potential roles of Brønsted acid sites (anchoring Pd species or activating methane molecules) were discussed, and the experimental results indicated that the anchoring effect of Brønsted acid sites on Pd species was not directly observed. However, the acid properties of supports (the presence of Al 3+ as Lewis acid sites, especially coordinatively unsaturated Al 3+ ) were crucial for the preparation of Pd/ZSM-5 catalysts with high Pd dispersion. Additionally, although Brønsted acid sites of ZSM-5 was contributed to the activation or even cracking of long-chain alkanes (such as n -decane), the direct adsorption/dissociation of methane on Brønsted acid sites was difficult and depended more on the dispersion and particle size of PdO x . Pd/NaZSM-5 catalyst presented an outstanding durability at low-temperature (350 °C) and high-temperature (800 °C), and the high Si/Al ratio could improve the water-resistance due to its good hydrophobicity, but the reversible deactivation owing to the formation of PdO into Pd(OH) 2 under high concentration of water vapor was still unavoidable.
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高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
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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.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2016
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IF 3.349
Lulu Li,Qinglun Meng,Junjun Wen,Jingui Wang,Gaomei Tu,Chunhui Xu,Fumin Zhang,Yijun Zhong,Weidong Zhu,Qiang Xiao
Hierarchical Fe-ZSM-5 zeolites were directly synthesized from a zeolitic synthesis system in the presence of a silane coupling agent 3-glycidoxypropyltrimethoxysilane (GPTMS). The structure and morphology of the hierarchical Fe-ZSM-5 synthesized with different amount of GPTMS were characterized by XRD , SEM, TEM , and N 2 adsorption-desorption techniques. UV–vis and NH 3 -TPD were used to investigate the state of iron species and acidity, respectively. The steaming activated hierarchical Fe-ZSM-5 were used as catalysts in the direct oxidation of benzene to phenol (BTOP) with N 2 O as oxidant, showing an improved performance in terms of both activity and stability compared to Fe-ZSM-5 synthesized in the absence of GPTMS. A comparison study on the n -butane uptakes in Fe-ZSM-5 zeolites indicated the internal mass-transfer limitations of the hierarchical Fe-ZSM-5 zeolites were significantly improved.
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高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2017
·
IF 3.615
Yueyang Liu,Ming Zhao,Linjuan Cheng,Jianhua Yang,Liping Liu,Jinqu Wang,Dehong Yin,Jinming Lu,Yan Zhang
A facile one-pot method through controlled nucleation and release of reactive nutrient species by using bulk silicon dioxide as the Si source and seeds as liberated nuclei was reported for the fabrication of hierarchical ZSM-5 zeolites . This ZSM-5 aggregation (ZSM-5-B) was hierarchically constructed by many flaky ZSM-5 crystals. High methane conversion, high selectivity of aromatics and excellent anti-coking stability were achieved in the catalytic methane dehydroaromatization reaction (MDA) as a model reaction using the Mo-modified ZSM-5-B catalyst. Structure-properties relevance studies indicated the synergistic integration of the suitable acidity, higher external surface and hierarchical porosity contributed to the largely improved MDA catalytic performance. The work demonstrates a much simpler and more economical route for practical application of hierarchical zeolite.
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高影响因子
ChemCatChem
·
2016
·Vol. 8
·期 21
·3317-3322
·
IF 4.724
Ziyu Liu,Dan Wu,Shu Ren,Xinqing Chen,Minghuang Qiu,Xian Wu,Chengguang Yang,Gaofeng Zeng,Yuhan Sun
Graphical Gasoline from methanol : ZSM-5 crystals with controllable c -axis length were successfully synthesized through a one-pot solvent-free route, with urea as an additive. Catalytic tests for the methanol to gasoline (MTG) conversion showed that the prepared c -axis oriented hierarchical ZSM-5, which allow fast mass transfer, exhibited both 100 % methanol conversion and far longer lifetime (900 h) than those of ZSM-5 with conventional morphology (350 h). ZSM-5 crystals with controllable c -axis length were successfully synthesized through a one-pot solvent-free route, with urea as an additive. X-ray diffraction patterns (XRD) show that the prepared samples exhibit high crystallinity. N 2 adsorption–desorption isotherms and mercury intrusion porosimetry (MIP) analysis together with TEM observations indicate that micro-, meso-, and macropores exist in the obtained samples. Catalytic tests for the methanol to gasoline (MTG) conversion showed that the prepared c -axis oriented hierarchical ZSM-5, which allow fast mass transfer, exhibited both 100 % methanol conversion and far longer lifetime (900 h) than those of ZSM-5 with conventional morphology (350 h) in the MTG reaction. The enhanced MTG performance by the c -axis oriented zeolite under one-pot solvent-free synthesis is of great importance as it is easily scaled-up for industrial applications.
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高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Chuan Yuan,Huayan Liu,Zekai Zhang,Hanfeng Lu,Qiulian Zhu,Yinfei Chen
Various ZSM-5 zeolites modified with alkali metals (Li, Na, K, Rb, and Cs) were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid (LA) to acrylic acid (AA). The effects of cationic species on the structures and surface acid-base distributions of the ZSM-5 zeolites were investigated. The important factors that affect the catalytic performance were also identified. The modified ZSM-5 catalysts were characterized using X-ray diffraction, temperature-programmed desorptions of NH 3 and CO 2 , pyridine adsorption spectroscopy, and N 2 adsorption to determine the crystal phase structures, surface acidities and basicities, nature of acid sites, specific surface areas, and pore volumes. The results show that the acid-base sites that are adjusted by alkali-metal species, particularly weak acid-base sites, are mainly responsible for the formation of AA. The KZSM-5 catalyst, in particular, significantly improved LA conversion and AA selectivity because of the synergistic effect of weak acid-base sites. The reaction was conducted at different reaction temperatures and liquid hourly space velocities (LHSVs) to understand the catalyst selectivity for AA and trends in byproduct formation. Approximately 98% LA conversion and 77% AA selectivity were achieved using the KZSM-5 catalyst under the optimum conditions (40 wt% LA aqueous solution, 365 °C, and LHSV 2 h −1 ).
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