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Competition between Acidic sites and hydrogenation sites in Cu/ZrO_(2) catalysts with different crystal phases for conversion of biomass-derived organics

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Green Energy & Environment 2021年第4期6卷 557-566页

作者： Yuewen Shao Tingting Wang Kai Sun Zhanming Zhang Lijun Zhang Qingyin Li Shu Zhang Guangzhi Hu Xun Hu School of Material Science and Engineering University of JinanJinan250022China College of Materials Science and Engineering Nanjing Forestry UniversityNanjing210037China Institute for Ecological Research and Pollution Control of Plateau Lakes School of Ecology and Environmental ScienceYunnan UniversityKunming 650504China

Oxides with different crystal phases can have important effects on the configuration of surface atoms,which can further affect the distribution of hydrogenation sites and Acidic sites as well as the competitions of these varied types of catalytic sites.This could be potentially used to tailor the distribution of the products.In this study,zirconium oxides with different crystal phases supported copper catalysts were prepared for the hydrogenation of the biomass-derived furfural,vanillin,etc.The results showed that both calcination temperature and Cu species affected the shift of zirconia from tetragonal phase to the monoclinic phase.Monoclinic zirconia supported copper catalyst can effectively catalyze the hydrogenation of furfural to furfuryl alcohol via hydrogenation route due to its low amount of Brønsted Acidic sites,although the surface area and the exposed metallic Cu surface area were much lower than the tetragonal zirconia supported copper catalyst.Zirconia with tetragonal or tetragonal/monoclinic phases supported copper catalysts contain abundant Acidic sites and especially the Br?nsted Acidic sites,which catalyzed mainly the conversion of furfural via the acid-catalyzed routes such as the acetalization,rather than the hydrogenation.The Acidic sites over the Cu/ZrO_(2)catalyst played more predominant roles than the hydrogenation sites in determining the conversion of the organics like furfural and vanillin.

关键词： Zirconia supported copper catalyst Crystal phase Hydrogenation Hydrogenation sites Acidic sites

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Effect of alkaline earth metal promoter on catalytic activity of MnO_(2)for the complete oxidation of toluene

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Journal of Environmental Sciences 2021年第6期33卷 102-112页

作者： Cui Dong Hui Wang Yewei Ren Zhenping Qu Key Laboratory of Industrial Ecology and Environmental Engineering School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China

Herein,Na^(+)and Ca^(2+)are introduced to MnO_(2)through cation-exchange method.The presence of Na^(+)and Ca^(2+)significantly enhance the catalytic activity of MnO_(2)in toluene oxidation.Among them,the Ca-MnO_(2)catalyst exhibits the best catalytic activity(T_(50)=194℃,T_(90)=215℃,E_a=57.2 k J/mol,reaction rate 8.40×10^(-10)mol/(sec·m^(2))at 210℃.T_(50)and T_(90):the temperature of 50%and 90%toluene conversion;E a:apparent activation energy)and possess high tolerance against 2.0 vol.%water vapor.Results reveal that the increased Acidic sites of the MnO_(2)sample can enhance the adsorption of gaseous toluene,and the mobility of oxygen species and the content of reactive oxygen species in the catalyst are significantly improved due to the formed oxygen vacancy.Thus these two factors result in excellent catalytic performance for toluene oxidation combining with the weak CO_(2)adsorption ability.

关键词： MnO_(2) Ca^(2+) Toluene oxidation Oxygen vacancy Acidic sites

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Effect of external surface of HZSM-5 zeolite on product distribution in the conversion of methanol to hydrocarbons

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Journal of Energy Chemistry 2014年第6期23卷 771-780页

作者： Junhui Li Yanan Wang Wenzhi Jia Zhiwen Xi Huanhui Chen Zhirong Zhu Zhonghua Hu Department of Chemistry Tongji University

The external surface of HZSM-5 zeolite was passivated by liquid siliceous deposition and by Acidic sites poisoning with lepidine, respectively. Then methanol-to-hydrocarbons （MTH） reaction was investigated over the above as-prepared catalysts and the dissoluble coke on these used catalysts was analyzed by GC-MS, to study the role of the external surface of HZSM-5 in the catalytic reaction. Comparison with the experi- mental results based on parent ZSM-5 showed that the product distribution of MTH reaction was obviously influenced by the external surface. Evidences were listed as follows：（1） the final product on parent HZSM-5 showed higher aromatic selectivity, lower olefin selectivity, lower ra- tio of C2/C3＋ aliphatics and higher ratio of C3/C4＋ aliphatics than the reaction mixture produced by the sole catalysis of Acidic sites in HZSM-5 channel; （2） a little of pentamethylbenzene and hexamethylbenzene in the product on parent HZSM-5, was produced via multi-methylation of methylbenzene on the external surface. The above conclusion may also be suitable for MTH reaction over other zeolites with 10-ring channel.

关键词： methanol-to-hydrocarbons product distribution HZSM-5 external surface Acidic sites

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