Journal of Environmental Sciences
·
2024
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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
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产品关联
DOI
PubMed
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Chuanhui Zhang,He Huang,Genqin Li,Lei Wang,Liang Song,Xuebing Li
Series of 10% MnO x /HZSM-5 catalysts with different zeolitic Si/Al ratios were prepared by an incipient impregnation method and evaluated for the catalytic oxidation of toluene. Characterization results indicated that all catalysts exhibited similar textural and redox properties but variable surface acidity. Catalytic testing results showed that the catalytic activities over these catalysts followed a descending order of 10% MnO x /HZSM-5-25 > 10% MnO x /HZSM-5-50 > 10% MnO x /HZSM-5-75, where 10% MnO x /HZSM-5-25 exhibited the optimum catalytic activity and excellent catalytic durability under dry condition and good water-resistant ability under humid condition. A good linear relationship between the toluene conversion efficiency (TOF Mn ) and the total acidity over MnO x /HZSM-5 catalysts was obtained, which revealed the crucial role and promotional effect of zeolitic acidity acting as a promoter on the catalytic activity for toluene oxidation.
研究领域:
催化化学
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环境科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
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IF 13.2
Yifan Zhang,Yangyang Guo,Shanshan He,Honglin Guo,Lei Luo,Mengran Li,Tingyu Zhu,Tao Guo,Yanxi Deng
CO 2 capture from blast furnace gas is of great significance for carbon reduction. 13X zeolites are frequently employed as CO 2 adsorbents. Nevertheless, their large-scale utilisation in industrial applications is impeded by the presence of H 2 O and H 2 S in blast furnace gas. To develop CO 2 adsorbents suitable for carbon capture from blast furnace gas, a series of Faujasite (FAU) zeolites were prepared in this study by modulating Si/Al. The findings revealed that the separation coefficients of CO 2 /N 2 and CO 2 /CO increased by 72 % and 144 %, respectively, and that the H 2 O adsorption decreased by 23 % when Si/Al was increased from 1.45 to 2.93. Furthermore, breakthrough experiments demonstrated that enhancing the Si/Al ratio of FAU zeolite can effectively reduce the dynamic adsorption capacity of H 2 O and H 2 S. Physicochemical characterizations of the zeolite before and after H 2 S adsorption were performed: CO 2 and N 2 adsorption isotherms, thermogravimetry, In-situ FT-IR and XPS. The present study investigates the effect of H 2 S adsorption on zeolites with varying Si/Al ratios. When combined with DFT calculations, the results demonstrate that the elevated Si/Al ratio of the zeolite results in a significant increase in sulfur resistance and easier deposition of H 2 S in the form of sulfate on the zeolite surface. It indicates that the modulation of Si/Al ratio is an effective method to improve the water and sulfur resistance of zeolites, and provides core material support for the practical application of large-scale carbon capture technology for blast furnace gas.
研究领域:
材料科学
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环境科学
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化学工程
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产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2019
·
IF 4.888
Yiwen Jiang,Ling Zhang,Yiquan Xie,Shichao Han,Qiuyan Zhu,Xiangju Meng,Feng-Shou Xiao
A series of zeolite-supported Pt nanoparticles (Pt/NaZSM-5) have been prepared by adjusting Si/Al ratio of NaZSM-5 zeolite from 60 to pure silica. Catalytic tests in propene oxidation as an important model reaction for removal of hydrocarbons emitted from automobiles during cold-start, show that the catalytic activities significantly increase with Si/Al ratios of NaZSM-5 zeolite in these Pt/NaZSM-5 catalysts. As a typical example, Silicalite-1 supported Pt nanoparticles exhibits the highest activity, giving the 50% conversion temperature (T 50 ) and 90% conversion temperature (T 90 ) at 112 °C and 118 °C, respectively. Characterizations of these catalysts with multiple techniques show that the enhanced catalytic activities are strongly related to the zeolite Si/Al ratios of the catalysts, where an increase of zeolite Si/Al ratio is favorable for the adsorption of propene, promoting the propene oxidation. This feature might offer a good opportunity to design and prepare highly efficient heterogeneous catalysts for removal of light olefins in the future.
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2016
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IF 3.652
Jiajun Zhang,Beatriz Fidalgo,Dekui Shen,Rui Xiao,Sai Gu
This work investigated the decomposition of anisole (methoxyl-based lignin model compound) in a fluidized bed reactor over no catalysts and a series of HZSM-5 zeolite catalysts with different Si/Al atomic ratios. Transmethylation reaction was identified as the initial step of the thermal decomposition of anisole, leading to the prominent production of phenolic compounds. Methyl phenols were identified as the main products, with the yield of o -cresol being higher than that of p-cresol at the temperatures below 600° C. The transmethylation reaction over HZSM-5 zeolite catalyst was found to occur at temperatures 150° C lower than those for non-catalytic reaction, with the yield of the phenolic compounds being promoted by 2.5 times. Production of the main phenolic compounds during the catalytic decomposition of anisole was enhanced to different extents depending on the Si/Al ratio. The highest selectivity of 79 wt.% was achieved over the zeolite catalyst with a Si/Al ratio of 80. The Brønsted acid sites of the catalyst played a significant role in both the preferential formation of phenolic compounds and preservation of the methyl group.
研究领域:
催化化学
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能源化学
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DOI
高影响因子
ENERGY & FUELS
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2020
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IF 3.421
Zhiqiang Yang,Ruirui Zhang,Fei Dai,Hongguo Tang,Ruixia Liu,Suojiang Zhang
To develop catalysts with superior stability for isobutane alkylation, La3+ exchanged FAU zeolites with varying framework Si/Al ratios were investigated. Based on the reaction performed in a continuous flow stirred tank reactor, a strong linear relationship between catalyst lifetime and strong Brønsted acid concentration was observed. Catalyst lifetime was speculated to change in an M-shaped pattern with respect to the framework Si/Al ratio, which implies there were at least two extreme Si/Al ratios in terms of catalyst stability. However, their product distribution differed significantly. LaFAU with a high Si/Al ratio led to enhanced acid strength, which resulted in higher cracking, self-alkylation activity, and poor product selectivity. In determining a balance between catalyst stability and product selectivity, a Si/Al ratio of ∼1.2 was selected as the optimal value for LaFAU zeolites.
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 MOLECULAR STRUCTURE
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2025
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IF 4.7
RuoKun Jia,PengPeng Wang,XiaoHang Yang,DuMin Li,JianGuo Qiao,TianXiang Li,JiaHui Chen
The rational modulation of the Si/Al ratio within molecular sieves holds utmost significance for augmenting photocatalytic activity. In this context, g-C 3 N 4 /HBeta composite photocatalysts were synthesised via a straightforward in situ thermal polymerisation procedure employing HBeta molecular sieves possessing multiple active sites and diverse Si/Al ratios. Through the variation of Si/Al ratios, the adsorption capacity, photogenerated carrier complexation efficiency, and active site characteristics could be effectively manipulated. The catalyst with the smallest Si/Al ratio (HBeta 25 ) exhibited the highest catalytic activity, with a hydrogen production efficiency of 2.346 mmol g⁻¹. This value was 4.9 times higher than that of pure g-C 3 N 4 , and the degradation efficiency of RhB was 3 times that of pure g-C 3 N 4 . The catalytic proficiency was principally validated by employing a comprehensive suite of techniques, including XPS, BET, SEM, and NH 3 -TPD. Our results demonstrate for the first time the strong potential of zeolite Si/Al ratio to modulate the catalytic activity of photocatalysts.
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
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IF 4.1
Bihong Li,Ming Wen,Yijie Ding,Weizhong Zheng,Weizhen Sun,Ling Zhao
The acidity and pore structure of zeolite catalysts play a crucial role in the selectivity and stability of C4 alkylation due to the synergistic effect of reaction activity and diffusion. Herein, the effect of three acidic beta zeolites with different Si/Al ratios on adsorption, diffusion, and catalytic performance was studied using experiments and molecular simulations. The beta zeolite with the lower Si/Al ratio leads to the faster relative diffusion of isobutane to 1-butene and the smaller adsorption amount of alkylate products. Furthermore, the diffusion of molecules in the zigzag channel along the z direction of beta zeolites is much slower than other two directions. The experimental results indicate that lower Si/Al ratio cause the higher content of strong BAS in the zeolite, resulting in the higher hydride activity and the longer catalytic lifetime. This work provides a theoretical basis for the development of high catalytic activity zeolite catalysts.
研究领域:
化学工程
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催化
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材料科学
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分子模拟
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2024
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IF 13.3
Wei Zhou,Wenwei Zhang,Xueqin Ma,Haichen Lai,Xingguang Zhang
Metal-zeolites catalysts are of great importance in selective organic conversions. Zeolites possess features of highly-ordered porous network, adjustable acidic properties (Brønsted/Lewis), spatial nanoconfinement effects, unique shape selectivity and the strong (hydrothermal-) stability. The role of zeolite hydroxyl (z-OH) groups, such as bridging ones in Si-O(H)-Al (B acids) and terminal ones in Al-OH and Si-OH (silanols), in catalysis is an interesting topic, particularly when they are not catalytic active sites, while they affect the catalytic performances. This study comprehensively investigated series of Au/USY catalysts in the selective oxidation of benzyl alcohol to benzaldehyde and clarified the dominating contributions of Al-associated z-OH groups to affecting catalytic conversions and selectivity via altering the Si/Al ratio and reducing z-OH groups by amorphous silica species derived from diethoxydimethylsilane under high-temperature calcination. The catalysts were characterized by XRD, BET, TEM, XPS, UV/Vis, FT-IR and in-situ DRIFT to investigate crystal structures, textural properties, morphologies, size distribution, chemical state of gold, acidity, and adsorptive properties. The experimental results proved that zeolites with a higher amount of z-OH groups tuned by Si/Al ratios or by diethoxydimethylsilane silylation exhibited higher catalytic activity because of the adsorption effect. Finally, a possible mechanism was discussed based on the experimental results and literature.
研究领域:
催化
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 37
·22126-22136
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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）