JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2021
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IF 5.541
Jianjun Xiao,Minjiao Yang,Qingfeng Che,Yingquan Chen,Xu Chen,Haiping Yang,Pietro Bartocci,Francesco Fantozzi,Hanping Chen
The effect of potassium in biomass on the catalytic activity of ZSM-5 zeolite in the fast pyrolysis of biomass was investigated using 2-methylfuran (2-MF) as the typical model compound. The mechanism of action of potassium was explored in detail, along with the physicochemical properties of ZSM-5, including crystallinity, pore structure, and surface acidity. The physicochemical properties of ZSM-5 deteriorated to varying degrees after being tainted with different potassium sources (KOH, K 2 CO 3 , KAc, and KCl). Compared with neutral KCl and strong alkali KOH, K 2 CO 3 , and KAc, with weaker alkalinity but larger crystal structure, exerted a larger influence on ZSM-5. Changes in ZSM-5 tainted with K 2 CO 3 were the greatest, and crystallinity, surface area, acidity, and the corresponding yields of valuable aromatic hydrocarbons and gas products, all declined significantly, compared with raw ZSM-5. When the amount of K(CO 3 2− ) on ZSM-5 was less than 0.5 wt%, only minor (<10 %) changes were observed in crystallinity and surface area, but total acidity decreased by over 30 percent. The conversion of 2-MF was increased using ZSM-5 tainted with less than 0.5 wt% K(CO 3 2- ) and less liquid oxygenated compounds and more CO 2 were produced. Appropriate total acidity, adjusted by a tiny amount of K 2 CO 3 , could promote deoxygenation to CO 2. However, the decarbonylation reaction was inhibited, causing a negative effect on monocyclic aromatic hydrocarbons, which was attributed to the large-scale loss of both acidity and physical structure of ZSM-5 caused by more than 1.0 wt% K(CO 3 2- ).
研究领域:
化学工程
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2015
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IF 3.893
Jing Xing,Liang Song,Cong Zhang,Mingdong Zhou,Li Yue,Xuebing Li
Upgrading of lignin derived bio-oil is a very promising way to relieve humankind's dependence on traditional fossil fuels. Eugenol, a model compound for lignin monomers with a methoxyl group and a hydroxyl group, was hydrodeoxygenated in aqueous phase with Pd/C as hydrogenation catalyst and ZSM-5 zeolite as hydrolysis and dehydration catalysts. The bulky lignin monomers had difficulty in accessing the acid sites of the micropores of ZSM-5 zeolite, thus we introduced mesopores via alkaline treatment under various conditions. Alkali-treated ZSM-5 zeolites showed higher conversion and hydrocarbon selectivity compared to the parent ZSM-5 zeolite. When ZSM-5 zeolite was treated at 338 K, the conversion and the hydrocarbon selectivity increased by 21% and 24%, respectively. In addition, much more weak acid sites of ZSM-5 zeolites after alkaline treatment also promoted the hydrolysis and dehydration process.
研究领域:
化学工程
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能源科学
✓ 已验证
DOI
高影响因子
Journal of Inorganic and Organometallic Polymers and Materials
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2024
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IF 3.9
Liu Hao,Wang Yanlin,Yuan Hong,Luo Wenbo
Nanoscale ZSM-5 zeolites (NZSM-5) having different crystal sizes and Si/tetrapropylammonium hydroxide (TPAOH) molar ratios were synthesized using a hydrothermal method. These materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N 2 adsorption–desorption. The results showed that each zeolite was highly crystalline regardless of the Si/TPAOH ratio and that the Brunauer–Emmett–Teller surface areas were in the range of 329−392 m 2 /g. The random aggregation of these nanoparticles resulted in the formation of numerous intergranular mesopores. These NZSM-5 zeolites were applied to the catalytic cracking of oleic acid to prepare light olefins and light aromatics using a laboratory-scale fixed bed reactor. The zeolite having a Si/TPAOH ratio of 10/5 showed the best catalytic activity and provided light olefins yield of 55% and selectivity of BTX in liquid phase products of 18%, respectively, at 500 °C. The small crystal size and abundant intergranular mesopores in this specimen resulted in shorter diffusion paths and an increase in the external specific surface area that both inhibited coke deposition and ensured accessible acid sites. Graphical Abstract
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
ENERGY & FUELS
·
2021
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IF 3.605
Hailing Sun,Liyuan Cao,Yuhao Zhang,Liang Zhao,Jinsen Gao,Chunming Xu
The effect of acid concentration and reaction temperature on the reaction of 1-hexene cracking to propylene was investigated. The catalysts with different acid concentrations were prepared by the alkali ion and phosphorus modification of ZSM-5 zeolite. It was observed that both decreasing the concentration of strong Brønsted acid sites (SBASs) and increasing reaction temperatures can enhance the selectivity and yield of propylene and hinder the formation of side products including hydrogen, C1∼C5 alkanes, aromatics, and coke. The hydrogen transfer reaction had an important effect on the selectivity of C3∼C5 olefins in the high concentration of SBASs. Besides, high temperatures intensified monomolecular reactions and hindered bimolecular or multimolecular reactions.On the basis of product distributions, possible main and side reaction routes were summarized under the real industrial reaction conditions. The conclusion was significant to optimize the catalyst design of olefin cracking or pyrolysis processes and operation conditions for increasing the yield of propylene.
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
ChemCatChem
·
2020
·Vol. 12
·期 15
·3880-3889
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IF 4.853
Xingling Zhao,Jun Xu,Yueying Chu,Guodong Qi,Qiang Wang,Wei Gao,Shenhui Li,Ningdong Feng,Feng Deng
Graphical Methane activation : Different types of Ga-CH 3 species were observed in methane activation on Ga-modified ZSM-5 zeolite, evidencing different pathways for heterolytic cleavage of C−H bond of methane. Two-dimensional solid-state NMR experiments provided detailed information on the location and local environment of the Ga-CH 3 species. Methane activation on Ga-modified ZSM-5 zeolites (Ga/ZSM-5) was studied by solid-state NMR spectroscopy. Two types of Ga species, namely highly dispersed oxides and cationic Ga species, were determined by 71 Ga QCPMG NMR. The activation of methane on Ga/ZSM-5 was explored by using 13 C and 1 H MAS NMR. Four types of Ga-CH 3 species along with Ga-OH groups were observed on Ga/ZSM-5, evidencing different pathways for heterolytic cleavage of C−H bond of methane. Two-dimensional (2D) 1 H- 1 H correlation NMR experiments provide detailed information on the location and local environment of the Ga-CH 3 species by correlating the protons in Ga-CH 3 with those in Ga-OH and other hydroxyls on zeolite. The structures of different Ga-CH 3 species were further determined by 2D 1 H- 13 C heteronuclear correlation NMR experiments, which were supported by theoretical calculations. The activation routes of C−H bond in methane were proposed on Ga/ZSM-5 zeolite.
研究领域:
化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
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2018
·Vol. 8
·期 17
·4338-4348
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IF 5.365
Xiaoli Yang,Xiong Su,Binglian Liang,Yaru Zhang,Hongmin Duan,Junguo Ma,Yanqiang Huang,Tao Zhang
The oxide–zeolite process has been attracting widespread attention due to its promising performance in syngas conversion to hydrocarbons with high selectivity and stability. Here, a composite catalyst containing Zn–Cr oxide and ZSM-5 zeolite provides a competitive option in the one-step conversion of syngas into C5+ hydrocarbons. In order to figure out the influence of the pore structure and acidity of zeolite on the oxide–zeolite process, alkali treatments on ZSM-5 are carried out. The treated ZSM-5 shows increased selectivity for gasoline fractions. With a set of structural and morphological characterization techniques, the formation of a hierarchical porous structure is demonstrated, which is favorable for the diffusion of heavy products. Furthermore, an increase in the number of Lewis acid sites, acting as the main active sites for the polymerization, cyclization and aromatization reactions, also contributes to the promotion of C5+ hydrocarbon production. It must be noted, however, that a certain amount of Brønsted acid sites is necessary for the tandem transformation of CH3OCH3 intermediates, which may further affect the CO conversion.
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2018
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IF 3.525
Wenjin Xu,Guangxu Zhang,Hanwei Chen,Guomeng Zhang,Yang Han,Yichuan Chang,Peng Gong
Two series of Mn/beta and Mn/ZSM-5 catalysts were prepared to study the influence of how different Mn precursors, introduced to the respective parent zeolites by wet impregnation, affected the selective catalytic reduction (SCR) of NO by NH 3 across a low reaction temperature window of 50–350 °C. In this study, the catalysts were characterized using N 2 adsorption/desorption, X-ray diffraction, X-ray fluorescence, H 2 temperature-programmed reduction, NH 3 temperature-programmed desorption and X-ray photoelectron spectroscopy. As the manganese chloride precursor only partially decomposed this primarily resulted in the formation of MnCl 2 in addition to the presence of low levels of crystalline Mn 3 O 4 , which resulted in poor catalytic performance. However, the manganese nitrate precursor formed crystalline MnO 2 as the major phase in addition to a minor presence of unconverted Mn-nitrate. Furthermore, manganese acetate resulted principally in a mixture of amorphous Mn 2 O 3 and MnO 2 , and crystalline Mn 3 O 4 . From all the catalysts screened, the test performance data showed Mn/beta-Ac to exhibit the highest NO conversion (97.5%) at 240 °C, which remained >90% across a temperature window of 220–350 °C. The excellent catalytic performance was ascribed to the enrichment of highly dispersed MnO x (Mn 2 O 3 and MnO 2 ) species that act as the active phase in the NH 3 -SCR process. Furthermore, together with a suitable amount of weakly acidic centers, higher concentration of surface manganese and a greater presence of surface labile oxygen groups, SCR performance was collectively enhanced at low temperature.
研究领域:
环境科学
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催化化学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
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2024
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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
✓ 已验证
DOI
高影响因子
Journal of Environmental Sciences
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2022
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IF 6.796
Chundi Zhou,Caiyun Han,Nengsheng Liu
Sulfidated nano zero-valent iron particles were immobilized on ZSM-5 zeolite (Z/S-nZVI) and used for hexavalent chromium (Cr(VI)) remediation. The performance of Z/S-nZVI improved with the increase in Cr(VI) concentration (< 60 mg/L), while the performance significantly decreased for a Cr(VI) concentration of more than 60 mg/L. The adsorption behavior for Cr(VI) was different from that reported in previous studies. The improved performance can be tailored for increasing efficiency of nano zero-valent iron (nZVI) corrosion, while the degree of corrosion of nZVI was affected by the concentration of the pollutant as discussed by kinetics, X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS) analyses. The experiments for the dissolution of ferrous ions and the dosage of adsorbent demonstrated that the critical layer in the liquid-solid system changed with the increase in the concentration of Cr(VI) (Cr(VI): Z/S-nZVI > 0.6). Moreover, the removal mechanisms of Cr(VI) were elucidated through XRD, transmission electron microscopy (TEM) and XPS techniques. This results demonstrate that the species of chromium in the critical layer changed from Cr(III) to Cr(VI) as the concentration of chromium increased from low to high. Furthermore, the critical layer was composed of Cr(VI), Fe(II), O and H elements. Additionally, the experiments of coexisting ions and aging time confirmed that Z/S-nZVI possessed high selectivity and stability to ensure efficiency and cost-effectiveness in practical applications.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS LETTERS
·
2016
·Vol. 147
·期 2
·502-508
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IF 2.294
Chen Yao,Liu Cheng-chao,Zhang Yu-hua,Zhao Yan-xi,Wei Liang,Wen Xiong,Zhao Xin,Li Jin-lin
Abstract Hierarchically ZSM-5 zeolite was prepared by alkali treatment. It was used as a support for a series of Co-based catalysts for Fischer–Tropsch synthesis with Fe, Ti, Ga or Zn as promoter. This series of catalysts were named Co/M-ZSM-5 (M = Fe, Ti, Ga or Zn). The catalysts were characterized by SEM, XRD, H 2 -TPR, and XPS, and the FTS catalytic performance of catalysts were compared. The character date revealed that the promoter changed the dispersion, reducibility and stability of Co. The addition of Zn and Ga increased the activity of catalysts, decreased the selectivity to CH 4 . The Ti promoted catalyst had the highest initial activity, but it deactivated rapidly. The suitable interaction between Co and the Fe-ZSM-5 result in the suitable dispersion and reduction. Thus Fe is the better promoter for the catalyst Co/ZSM-5. Graphical Abstract
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2020
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IF 3.99
Ji Guo,Zhongli Ji
The filtration efficiency of coalescent filter elements used in gasoline and diesel oil dehydration in refineries is unsatisfactory and not sufficient to meet downstream water-content requirements. Thus, it was necessary to improve the internal filter medium of traditional oil-water coalescent filter elements. Zeolite membrane is a kind of material with superhydrophilicity and strong adsorption for and permeability to water. In this study, ZSM-5 zeolite membrane with superhydrophilic properties was successfully prepared by an in situ hydrothermal synthesis. Two experiments with zeolite membranes were performed, including membrane filtration and membrane coalescence tests. Membrane filtration tests showed that it possessed strong adsorption for and permeability to water and that the oil-water filtration efficiency for 32 # turbine oil, kerosene, and corn oil were all >95 %. In the second part of this study, composite filtration was carried out using the membrane as well as hydrophilic glass fiber and hydrophobic polypropylene (PP) membranes. Membrane coalescence test demonstrated that, when the oil contained a phenol/water combination, the water rejection rate of the composite filtration with ABACBA (A, PP fiber; B, glass fiber; and C, molecular sieve membrane) was 90.8 %, with the downstream water content controlled within 100 mg/L and the quality factor increased from 0.18 to 0.23, relative to other systems. These experimental results showed potential for improving the current oil-water coalescent filters.
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
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
危险品化学品经营许可证（带存储）