MICROPOROUS AND MESOPOROUS MATERIALS
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2022
·
IF 5.876
Yingshu Liu,Haiyang Tao,Xiong Yang,Xiaoyong Wu,Jinjuan Li,Chuanzhao Zhang,Ralph T. Yang,Ziyi Li
Adsorption is a promising technology for capturing nitrogen oxides (NO x ) from humid flue gases , for which as the preferred NO x adsorbent, zeolite with an appropriate silica to alumina (Si/Al) ratio provides the key step for success in practical applications. In this work, the effects of Si/Al ratio, temperature, relative humidity (RH), and feed gas (NO x -H 2 O(g)–CO 2 –O 2 -N 2 ) compositions on NO x sorption behavior on HZSM-5 zeolites were systematically investigated, based on a series of characterizations, fixed-bed adsorption and temperature programmed desorption (TPD) tests. The low-silica HZSM-5(25) showed the best performance (326.6 μmol/g and 39.2 μmol/g at dry and 90%RH) as compared to others with higher Si/Al ratios at each RH, in which the roll-up effect was positively correlated with the Si/Al ratios and humidity. O 2 enhanced NO x adsorption and reached an optimal adsorption capacity at the concentration of 14%, while CO 2 had little effect on NO x adsorption. The decrease in temperature increased NO x adsorption capacity on HZSM-5(25), benefitting from NO 2 physisorption as well as satisfactory NO oxidation within the active adsorbent structure. The facile thermal desorption of NO x and significant NO–NO 2 conversion on HZSM-5(25) was exhibited by bimodal TPD peaks at 343–353K and 533–543K respective for NO and NO 2 , in contrast to those on Silicalite-1. A potential “water-resistant” strategy via the enhancement of NO x adsorption competitiveness was revealed, providing a theoretical guideline for NO x adsorbent screening in industrial 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
高影响因子
RENEWABLE ENERGY
·
2023
·
IF 8.7
Xiaohua Li,Jiayuan Sun,Shanshan Shao,Jinlong Yan,Yixi Cai
In this study, HZSM-5 was modified by green templates (cellulose, starch and glucose), the mesoporous structure was successfully introduced, and the prepared composite catalyst was used for the catalytic pyrolysis of biomass to prepare aromatics hydrocarbon. It was revealed that the additionally introduced mesopore pore size was closely related to the size of the template molecule. The formation of pore structures with larger pore sizes on the catalyst was facilitated by larger polysaccharide templates (starch and cellulose). The increase in mesopore pore size was promoted by the cellulose and starch templates, while the increase in the number of mesopores was promoted by the glucose template. The pore size of the catalyst has a great influence on selectivity of BTX. Selectivity of BTX with larger carbon numbers (xylene, trimethylbenzene) was improved by the mesoporous structure with larger pore size. Excellent catalytic performance is also shown on template modified catalysts. The maximum yield of BTX was 10.18 wt%, which was about 1.1times higher than HZSM-5. In addition, the decomposition of macromolecular substances in the pyrolysis gas was promoted by the mesoporous structure of the template-modified catalyst, and the formation of coke on the catalyst was prevented.
研究领域:
化学工程
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能源科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Nai-Yu Yao,Jing-Pei Cao,Jing-Ping Zhao,Zi-Meng He,Xiao-Bo Feng,Tian-Long Liu,Ze-Ying Wang,Xiao-Yan Zhao
A series of Zn-containing HZSM-5 (HZ5) with hierarchical pores (xZn(DS)) were obtained by adding different amounts of Zn(NO 3 ) 2 solution in a hydrothermal synthesis process. The performances of xZn(DS) in catalytic reforming of cellulose pyrolysis volatiles were investigated at 500 °C. The results showed that the addition of Zn during synthesis increased in the total pore volume of xZn(DS) and reduced the content of strong acid sites, and introduced new weak acid sites. The Zn species were highly dispersed inside the zeolite, and enhanced the accessibility of acid sites, so that the yields of light aromatic hydrocarbons and monocyclic aromatic hydrocarbons (MAHs) over 0.7Zn(DS) (The molar ratio of ZnO/Al 2 O 3 in the synthesis process of xZn(DS) was 0.7) were higher than those over S-HZ5 (Zn was not added in the synthesis process) and commercial HZ5. Compared with S-HZ5, the yield of MAHs over 0.7Zn(DS) increased from 92.8 to 114.1 mg/g and the coke yield decreased by 2.9%. The selectivity of MAHs over 0.7Zn(DS) was 87.7%, which was 5.3% higher than that over S-HZ5. Simultaneously, the increase in mesopores of xZn(DS) accelerated the mass transfer process, shortened the diffusion path and improved the anti-coking performance of the catalysts. In addition, this study also proposed a possible mechanism for the catalyst to adjust the distribution of aromatic products and provided a new idea for promoting the selective production of MAHs for the pyrolysis of cellulose.
研究领域:
能源化学
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Sciences
·
2024
·
IF 5.9
Kaini Ma,Kai Li,Ping Ning,Jiayu Feng,Jiacheng Bao,Lei Shi,Xiangyu Wang,Xin Sun
This study employed a wet impregnation method to synthesize five types of Cu/HZSM-5 adsorbents with Si/Al ratios of 25, 50, 85, 200, and 300, used for the removal of H 2 S in low-temperature, low-oxygen environments. The impact of different Si/Al ratios on the adsorption oxidative performance of Cu 30 /HZSM-5–85 adsorbents was investigated. According to the performance test results, Cu 30 /HZSM-5–85 exhibited the highest breakthrough capacity, reaching 231.75 mg H 2 S/g sorbent . Cu/HZSM-5 sorbent maintains a strong ability to remove H 2 S even under humid conditions and shows excellent water resistance. XRD , BET, and XPS results revealed that CuO is the primary active species, with Cu 30 /HZSM-5–85 having the largest surface area and highest CuO content, providing more active sites for H 2 S adsorption. H 2 -TPR and O 2 -TPD results confirmed that Cu 30 /HZSM-5–85 sorbent exhibits outstanding redox properties and oxygen storage capacity, contributing to excellent oxygen transferability in the molecular sieve adsorption-oxidation process. With notable characteristics such as a large surface area, high desulfurization efficiency, and water resistance, Cu 30 /HZSM-5–85 sorbents hold significant importance for industrial 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
APPLIED CATALYSIS A-GENERAL
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2022
·
IF 5.723
Guoqiang Hou,Tingjun Fu,Xin Li,Qian Ma,Zhong Li
HZSM-5 catalysts with abundant silanol nests were fabricated by removing framework Al, which effectively promoted the selective alkylation of toluene with methanol by inhibiting the deep alkylation of aromatics to heavy aromatics and the conversion of methanol to light hydrocarbons. Correspondingly, the alkylation efficiency reached 65.3% at a toluene conversion of 31.3% over dealuminated HZSM-5, higher than the 55.2% efficiency and 28.0% conversion of parent zeolites, respectively. In situ DRIFTS and single-factor experimental clarified that toluene adsorption was enhanced and methanol to hydrocarbons was inhibited with the presence of silanol nests. Additionally, by increasing the crystal size of HZSM-5 with silanol nests from 2 to 5 µm, para-xylene selectivity was increased from 36.1% to 65.5% because of the enhanced diffusion barrier . The finding of the positive effect of the silanol nests on toluene alkylation can provide a solid fundamental basis for the rational design of catalysts.
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
Catalysts
·
2016
·Vol. 6
·期 9
·134
·
IF 2.964
Songbai Qiu,Ying Xu,Yujing Weng,Longlong Ma,Tiejun Wang
A series of MCM-41 supported Ni catalysts with high metal dispersion was successfully synthesized by simple co-impregnation using proper ethylene glycol (EG). The acquired Ni-based catalysts performed the outstanding hydrogenolysis activity of guaiacol. The effects of the synthesis parameters including drying temperature, calcination temperature, and metal loading on the physical properties of NiO nanoparticles were investigated through the use of X-ray diffraction (XRD). The drying temperature was found to significantly influence the particle sizes of NiO supported on MCM-41, but the calcination temperature and metal loading had less influence. Interestingly, the small particle size (≤3.3 nm) and the high dispersion of NiO particles were also obtained for co-impregnation on the mixed support (MCM-41:HZSM-5 = 1:1), similar to that on the single MCM-41 support, leading to excellent hydrogenation activity at low temperature. The guaiacol conversion could reach 97.9% at 150 °C, and the catalytic activity was comparative with that of noble metal catalysts. The hydrodeoxygenation (HDO) performance was also promoted by the introduction of acidic HZSM-5 zeolite and an 84.1% yield of cyclohexane at 240 °C was achieved. These findings demonstrate potential applications for the future in promoting and improving industrial catalyst performance.
研究领域:
催化化学
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能源化学
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材料化学
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工业催化
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生物质转化
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
YiRong Yao,Bing Xing,Jianbing Chen,YanLun Ren,YuJia Ma,Ying Zhang,Li Zhang
This study proposes an advanced method to tackle CO 2 emissions by enhancing solid acid catalysts, aiming to reduce the high energy consumption and low economic efficiency typically associated with chemical absorption processes. The research involves modifying commercial HZSM-5 zeolites through Cu ion exchange, with the optimal performance observed at a Cu ion content of 2.86 % and a Cu salt concentration of 0.2 M. This modification significantly minimizes the loss of copper ions—a common issue in the impregnation method—resulting in a 76.62 % reduction in the loss of active components. To further improve CO 2 gas-liquid mass transfer, mesoporous MCM-41 zeolites were introduced. Experimental results demonstrate that, at a regeneration temperature of 86°C and a mass ratio of 2:1 for HZSM-5 to MCM-41, the combined catalyst achieves a 61.28 % reduction in relative heat duty compared to the blank sample. Moreover, the energy consumption is 12.33 % and 16.45 % lower than that of HZSM-5 and MCM-41 used individually. Characterization analysis reveals that, under comparable acidic active site densities, catalysts with superior physical pore structures exhibit enhanced catalytic performance. The introduction of mesoporous structures notably improves the bidirectional mass transfer efficiency between carbamate macromolecules and CO 2 molecules. This work successfully demonstrates the synergistic effect of combining Cu ion-modified HZSM-5 zeolites with mesoporous MCM-41, leveraging the abundant active sites of HZSM-5 while harnessing the enhanced mass transfer properties of MCM-41.
研究领域:
化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
TRANSACTIONS OF TIANJIN UNIVERSITY
·
2018
·Vol. 25
·期 2
·143-151
·
IF 0
Du Jianzeng,Li Yonghong,Miao Zhenyu
Novel Ni/ZnO – HZSM-5 adsorbents were synthesized by incipient wetness impregnation. The Ni/ZnO – HZSM-5 adsorbent can achieve deep desulfurization and olefin aromatization at the same time. Thiophene sulfur was removed from 495 to less than 10 ppm via reactive adsorption desulfurization (RADS). Olefins were also converted into aromatics. HZSM-5 did not only support adsorbents but also cooperated with active Ni sites to catalyze olefins into aromatic hydrocarbons. Aromatization of 1-pentene, 2-pentene, 2-methyl-2-butene, and 1-hexene on adsorbents was investigated. The adsorbents were characterized by the Brunauer–Emmett–Teller, X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption of ammonia and thermogravimetric analysis. The experimental results showed that strong acids on the adsorbent disappeared after HZSM-5 loaded active metal sites, and almost no coke was generated on adsorbents in RADS.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
INDUSTRIAL CROPS AND PRODUCTS
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2024
·
IF 5.6
Zhaoying Li,Langqi Shi,Daokuan Liang,Feixing Li,Lianghuan Wei,Weizun Li,Xianghao Zha
The quality of bio-oil produced from fast pyrolysis of lignocellulosic biomass needs urgent upgrading due to its undesirable characteristics. In this study, HZSM-5 modified with different alkali solutions is used to catalytic fast co-pyrolysis of cotton stalk and polypropylene, investigating pyrolysis temperatures, catalysts modified with different alkali solutions, the cotton stalk (CS) to polypropylene (PP) ratio, and the feedstock to catalyst ratio. Thermogravimetric experiments revealed that PP undergoes rapid decomposition between 408 °C and 465 °C, during which a substantial amount of hydrogen free radicals is released. These radicals subsequently react with oxygen-containing compounds emitted by carbonaceous substances CS, thereby facilitating weight loss and minimizing coke formation. The FTIR results also indicate that the presence of PP significantly increases the transmittance of O-H groups at 3600–3000 cm −1 and C-O groups at 1290–900 cm −1 compared to CS. The TPAOH-modified HZSM-5 possesses a mesoporous structure and porous channels, facilitating the completion of deoxygenation of pyrolysis vapors at the acid sites. CFP of CS over HZSM-5 modified TPAOH (1.5 mol/L) at 600 °C is carried out, resulting in the highest hydrocarbon content in the bio-oil reaching 63.3 %. Concurrently, the BTEX concentrations attain their maximum values of 6.5 %, 12.9 %, 3.4 %, and 12.6 %. In addition to the hydrocarbon pool mechanism, the Diels-Alder reaction between furan and olefin is a crucial synergistic effect for generating aromatics. Upon the addition of PP in a 1:1 ratio, the contents of BTEXs attain maximum values of 8.1 %, 15.5 %, 2.3 %, and 15.5 %. Response surface methodology (RSM) indicates that the organic alkali concentration used for catalyst modification is the most significant factor influencing aromatics generation. Overall, this study aims to improve bio-oil quality and detail the reaction mechanism.
研究领域:
能源与燃料
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Russian Journal of Physical Chemistry A
·
2024
·Vol. 98
·期 10
·2219-2232
·
IF 0.7
Guiling Wu,Zhao Wenli,Yang Xinyue,Niu Xiaopo,Guo Zhen,Liu Danni,Wang Qingfa
Abstract Producing high-density fuel of alkylated decalins from hydrodeoxygenation (HDO) of naphthalene derivatives is an environmentally friendly but still challenging method. Herein, a bifunctional Ru/HZSM-5 catalyst was fabricated by acid treatment (citric acid, oxalic acid, nitric acid) to effectively synthesize the alkylated decalins via HDO of naphthalene derivative. Acid treatment adjusted the acidic site distribution of Ru/HZSM-5. Nitric acid treatment (NA) resulted in more abundance of weak acidic sites which was beneficial for the dehydration process in HDO, and the lowest ratio of BAS/LAS to promote the hydrogenation of alkylated octalins, the rate-determining step of HDO. NA-treated Ru/HZSM-5 showed the highest HDO activity with the highest selectivity of 1,2-dimethyldecalin (74%). Besides, it also presents good HDO activity of naphthalene derivatives to produce high-density hydrocarbons. Therefore, Ru/HZ5-NA is a promising catalyst for the production of alkylated decalins and other high-value biofuels and chemicals.
研究领域:
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2021
·
IF 5.541
Xiaohua Li,Shengnan Ge,Shanshan Shao,Zhichao Lv,Xianliang Xiang,Yixi Cai
In order to promote the production of hydrocarbons in the catalytic pyrolysis of rape straw, a core-shell catalyst fabricated by external recrystallization method was employed. The composite catalyst HZSM-5@MCM-41 was prepared by varying the mass ratio of template and HZSM-5 (THR), and the effect of zeolite acidity and mesoporosity on the production of hydrocarbons was analyzed. A final pyrolysis temperature of 500 °C was suitable to obtain high yield of hydrocarbons over composite catalysts. Compared with ZSM-5 with a favorable pyrolysis temperature of 550 °C, a lower pyrolysis temperature meant a more efficient process, which may be related closely to the good diffusion of large-sized pyrolysis vapors over HZSM-5@MCM-41 catalysts. In addition, the highest yield of monocyclic aromatic hydrocarbons obtained over HZSM-5@MCM-41 with THR of 1 was 11.43 wt.%, which was boosted by 2.5 times compared with HZSM-5. A proper THR was suitable to fabricate a core-shell catalyst with excellent crystallinity, acidity and mesoporosity, and resulting in a high yield of hydrocarbons. Furthermore, the core-shell catalyst presents less formation of graphite-like coke, which indicated the easier removal of coke. Therefore, the composite HZSM-5@MCM-41 catalysts were more appropriate for upgrading of pyrolysis vapors for hydrocarbons.
研究领域:
能源与环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
·
2021
·
IF 3.995
Ruizhen Zhang,Jie Wang,Lina Han,Jiancheng Wang,Liangfu Zhao
HZSM-5 molecular sieves are efficient catalysts in the aromatization of light hydrocarbons and the fabrication of HZSM-5-based core–shell composites has become an important strategy to improve their catalytic performance due to the simultaneous modification of the acidity and pore structures in the catalyst. In this paper, HZSM-5/SAPO-5 (CSZP and CSZC) were synthesized via a two-stage crystallization process using PDDA and CTAB as modifiers of HZSM-5, respectively. The structure, acidity, and the weight of carbon deposition of the resulting molecular sieves catalysts were characterized using various methods and their catalytic behavior in isobutane aromatization investigated. The results show that CSZP exhibits a perfect core–shell structure with a uniform and thin shell composed of nano-SAPO-5, while CSZC has an irregular coat configuration with HZSM-5 covered by a rough and thick shell consisting of flaky micro-SAPO-5 crystals. The introduction of SAPO-5 via an in-situ synthesis decreases the Brønsted acidity of the catalysts to different extents and provides a large number of intergranular mesopores due to the stacking of SAPO-5 on the surface of HZSM-5, which is favorable toward improving the BTEX selectivity (benzene, toluene, ethylbenzene, and xylene) and catalytic stability over CSZP and CSZC. Meanwhile, CSZP has more competitive advantages than CSZC in promoting the mass transfer efficiency due to its significantly thinner shell than CSZC, which combined with its moderate acidity and appropriate mesopore structure result in its excellent selectivity and stability during the aromatization of isobutane.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）