Steam reforming （SR） of dimethyl ether （DME） was investigated for the production of hydrogen for fuel cells. The activity of a series of solid acids for DME hydrolysis was investigated. The solid acid catalysts we...Steam reforming （SR） of dimethyl ether （DME） was investigated for the production of hydrogen for fuel cells. The activity of a series of solid acids for DME hydrolysis was investigated. The solid acid catalysts were ZSM-5 [Si/A] = 25, 38 and 50： denoted Z（Si/Al）] and acidic alumina （γ-Al2O3） with an acid strength order that was Z（25）〉Z（38）〉Z（50）〉γ-Al2O3. Stronger acidity gave higher DME hydrolysis conversion. Physical mixtures containing a CuO-ZnO-Al2O3-ZrO2 catalyst and solid acid catalyst to couple DME hydrolysis and methanol SR were used to examine the acidity effects on DME SR. DME SR activity strongly depended on the activity for DME hydrolysis. Z（25） was the best solid acid catalyst for DME, SR and gave a DME conversion〉90% IT= 240℃,n（H20）/n（DME） = 3.5, space velocity = 1179 ml.（g cat）^-1.h^-1, and P= 0.1MPa]. The influences of the reaction temperature, space velocity and feed molar ratio were studied. Hydrogen production significantly depended on temperature and space velocity. A bifunctional catalyst of CuO-ZnO-Al2O3-ZrO2 catalyst and ZSM-5 gave a high H2 production rate and CO2 selectivity.展开更多
Cu/ZnO is widely used in the hydrogenation of carbon dioxide (CO_(2)) to methanol (CH_(3)OH) to improve the lowconversion rate and selectivity generally observed. In this work, a series of In, Zr, Co, and Ni-doped CuO...Cu/ZnO is widely used in the hydrogenation of carbon dioxide (CO_(2)) to methanol (CH_(3)OH) to improve the lowconversion rate and selectivity generally observed. In this work, a series of In, Zr, Co, and Ni-doped CuO-ZnO catalysts wassynthesized via a hydrothermal method. By introducing a second metal element, the activity and dispersion of the activesites can be adjusted and the synergy between the metal and the carrier can be enhanced, forming an abundance of oxygenvacancies. Oxygen vacancies not only adsorb CO_(2) but also activate the intermediates in methanol synthesis, playing a keyrole in the entire reaction. Co3O4-CuO-ZnO had the best catalytic performance (a CO_(2) conversion rate of 9.17%;a CH_(3)OHselectivity of 92.77%). This study describes a typical strategy for multi-component doping to construct a catalyst with anabundance of oxygen vacancies, allowing more effective catalysis to synthesize CH_(3)OH from CO_(2).展开更多
The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade （99.9% pure） Zinc Oxide powder mechanochemically in acetone medium...The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade （99.9% pure） Zinc Oxide powder mechanochemically in acetone medium with various weight percentages of Copper Chloride （CulCI2.2H20） powder （1, 3, 5, 7 and 9wt.%）. The prepared materials were sintered at 1,000 ℃ for 12 h in air ambience and ball milled to ensure sufficiently fine particle size. The films were characterized by different techniques with respect to their surface morphology and compositional property by means of SEM （scanning electron microscope） and EDXA （energy dispersive x-ray analysis）. The surface morphology of the films was studied by SEM and it shows the films are porous in nature and petal-shaped grains of sizes varies from 220 nm to 250 nm were observed. The final composition of each film was determined by the EDXA analysis. The gas response of undoped ZnO and CuO doped ZnO films was studied for different gases such as CO, C12, NH3, Ethanol, H2S and LPG at operating temperature ranging from 50 ℃ to 400 ℃. The 7wt.% CuO-doped ZnO film shows good response to H2S gas （100 ppm） at 250 ℃.展开更多
Generating different types of defects in heterogeneous catalysts for synergetic promotion of the reactivity and selectivity in catalytic reactions is highly challenging due to the lack of effective theoretical guidanc...Generating different types of defects in heterogeneous catalysts for synergetic promotion of the reactivity and selectivity in catalytic reactions is highly challenging due to the lack of effective theoretical guidance.Herein,we demonstrate a facile strategy to introduce two types of defects into the CuO-ZnO model catalyst,namely oxygen vacancies(OVs)induced by H2 partial reduction and localized amorphous regions(LARs)generated via the ball milling process.Using industrially important Rochow–Müller reaction as a representative,we found OVs predominantly improved the target product selectivity of dimethyldichlorosilane,while LARs significantly increased the conversion of reactant Si.The CuO-ZnO catalyst with optimized OVs and LARs contents achieved the best catalytic property.Theoretical calculation further revealed that LARs promote the generation of the Cu3Si active phase,and OVs impact the electronic structure of the Cu3Si active phase.This work provides a new understanding of the roles of different catalyst defects and a feasible way of engineering the catalyst structure for better catalytic performances.展开更多
基金Supported by the Ministry of Science and Technology （G1999022408） and the National Natural Science Foundation of China （20773075）.
文摘Steam reforming （SR） of dimethyl ether （DME） was investigated for the production of hydrogen for fuel cells. The activity of a series of solid acids for DME hydrolysis was investigated. The solid acid catalysts were ZSM-5 [Si/A] = 25, 38 and 50： denoted Z（Si/Al）] and acidic alumina （γ-Al2O3） with an acid strength order that was Z（25）〉Z（38）〉Z（50）〉γ-Al2O3. Stronger acidity gave higher DME hydrolysis conversion. Physical mixtures containing a CuO-ZnO-Al2O3-ZrO2 catalyst and solid acid catalyst to couple DME hydrolysis and methanol SR were used to examine the acidity effects on DME SR. DME SR activity strongly depended on the activity for DME hydrolysis. Z（25） was the best solid acid catalyst for DME, SR and gave a DME conversion〉90% IT= 240℃,n（H20）/n（DME） = 3.5, space velocity = 1179 ml.（g cat）^-1.h^-1, and P= 0.1MPa]. The influences of the reaction temperature, space velocity and feed molar ratio were studied. Hydrogen production significantly depended on temperature and space velocity. A bifunctional catalyst of CuO-ZnO-Al2O3-ZrO2 catalyst and ZSM-5 gave a high H2 production rate and CO2 selectivity.
基金the National Natural Science Foundation of China(Nos.61973223,51972306)the Liao Ning Revitalization Talents Program(No.XLYC2007051)+2 种基金the Liaoning Educational Department Foundation(No.LJKMZ20220762,JYTMS20231510)the Natural Science Foundation of Liaoning Province(No.2023-MS-235,2023-MSLH-270)the Key Project in Science&Technology of SYUCT(No.2023DB005).
文摘Cu/ZnO is widely used in the hydrogenation of carbon dioxide (CO_(2)) to methanol (CH_(3)OH) to improve the lowconversion rate and selectivity generally observed. In this work, a series of In, Zr, Co, and Ni-doped CuO-ZnO catalysts wassynthesized via a hydrothermal method. By introducing a second metal element, the activity and dispersion of the activesites can be adjusted and the synergy between the metal and the carrier can be enhanced, forming an abundance of oxygenvacancies. Oxygen vacancies not only adsorb CO_(2) but also activate the intermediates in methanol synthesis, playing a keyrole in the entire reaction. Co3O4-CuO-ZnO had the best catalytic performance (a CO_(2) conversion rate of 9.17%;a CH_(3)OHselectivity of 92.77%). This study describes a typical strategy for multi-component doping to construct a catalyst with anabundance of oxygen vacancies, allowing more effective catalysis to synthesize CH_(3)OH from CO_(2).
文摘The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade （99.9% pure） Zinc Oxide powder mechanochemically in acetone medium with various weight percentages of Copper Chloride （CulCI2.2H20） powder （1, 3, 5, 7 and 9wt.%）. The prepared materials were sintered at 1,000 ℃ for 12 h in air ambience and ball milled to ensure sufficiently fine particle size. The films were characterized by different techniques with respect to their surface morphology and compositional property by means of SEM （scanning electron microscope） and EDXA （energy dispersive x-ray analysis）. The surface morphology of the films was studied by SEM and it shows the films are porous in nature and petal-shaped grains of sizes varies from 220 nm to 250 nm were observed. The final composition of each film was determined by the EDXA analysis. The gas response of undoped ZnO and CuO doped ZnO films was studied for different gases such as CO, C12, NH3, Ethanol, H2S and LPG at operating temperature ranging from 50 ℃ to 400 ℃. The 7wt.% CuO-doped ZnO film shows good response to H2S gas （100 ppm） at 250 ℃.
基金support from the National Natural Science Foundation of China(Nos.21878301 and 21978299)the Open Research Fund of State Key Laboratory of Multiphase Complex Systems(No.MPCS-2021-D-08)+4 种基金GRINM Group.Y.J.J.thanks the financial support from the Research Foundation for Advanced Talents of Beijing Technology and Business University(No.19008020159)X.L.C.thanks the financial support from the project for improving the research ability of postgraduate from Beijing Technology and Business University(No.19008022056)L.W.X.thanks the financial support from the Research Foundation for Youth Scholars of Beijing Technology and Business University(No.QNJJ2022-22)Z.Y.Z.thanks the financial support of Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion(MATEC)Guangdong Technion-Israel Institute of Technology and Guangdong Key Discipline Fund(2022)for this collaboration。
文摘Generating different types of defects in heterogeneous catalysts for synergetic promotion of the reactivity and selectivity in catalytic reactions is highly challenging due to the lack of effective theoretical guidance.Herein,we demonstrate a facile strategy to introduce two types of defects into the CuO-ZnO model catalyst,namely oxygen vacancies(OVs)induced by H2 partial reduction and localized amorphous regions(LARs)generated via the ball milling process.Using industrially important Rochow–Müller reaction as a representative,we found OVs predominantly improved the target product selectivity of dimethyldichlorosilane,while LARs significantly increased the conversion of reactant Si.The CuO-ZnO catalyst with optimized OVs and LARs contents achieved the best catalytic property.Theoretical calculation further revealed that LARs promote the generation of the Cu3Si active phase,and OVs impact the electronic structure of the Cu3Si active phase.This work provides a new understanding of the roles of different catalyst defects and a feasible way of engineering the catalyst structure for better catalytic performances.
