以尿素为沉淀剂,采用均相沉淀法成功制备了层状Cu/Zn/Al水滑石化合物.将前驱体材料经焙烧、还原后得到Cu/ZnO/Al_2O_3催化剂,并将其用于CO_2加氢合成甲醇反应.采用X射线衍射(X-ray diffraction,XRD)、热重(thermogravimetric,TG)分析、...以尿素为沉淀剂,采用均相沉淀法成功制备了层状Cu/Zn/Al水滑石化合物.将前驱体材料经焙烧、还原后得到Cu/ZnO/Al_2O_3催化剂,并将其用于CO_2加氢合成甲醇反应.采用X射线衍射(X-ray diffraction,XRD)、热重(thermogravimetric,TG)分析、扫描电镜(scanning electron microscope,SEM)、X射线荧光(X-ray fluorescence,XRF)分析、N_2吸附、H_2程序升温还原(H_2-temperature program reduction,H_2-TPR)、氧化亚氮(N_2O)反应吸附、CO_2程序升温脱附(CO_2-temperature program desorption,CO_2-TPD)技术对所制备的样品进行表征.结果表明,相对于传统共沉淀法,以尿素作为沉淀剂,通过均相沉淀法所制备的前驱体的结晶度更高、催化剂比表面积更大、金属Cu的分散度更好.另外,采用回流处理可以获得更好的效果.活性评估结果表明,O_2转化率随金属Cu比表面积的增大而增加,而甲醇选择性则与催化剂表面碱性位的分布有关.因此,采用尿素回流处理均相沉淀法制备的Cu/ZnO/Al_2O_3催化剂的甲醇收率最高.展开更多
We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the cataly...We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the catalyst for methanol steam reforming. It is shown by in situ XRD that a considerable increase in the microstrain of Cu nanocrystals could be achieved in the catalysts processed by microwave irradiation for 310 min, which correlates well with the enhanced CH3OH conversion as observed on the corresponding samples. The present work also confirms that although the high specific surface area of Cu is a prerequisite for catalytic activity, it does not account for the observed changes in activity and selectivity alone without taking bulk microstructural changes into account.展开更多
A number of nanostructured carbon materials were proposed as new effective promoters for preparing modified Cu/ZnO/Al 2O 3 catalyst system for efficient hydrogen production from methanol steam reforming. Compared to t...A number of nanostructured carbon materials were proposed as new effective promoters for preparing modified Cu/ZnO/Al 2O 3 catalyst system for efficient hydrogen production from methanol steam reforming. Compared to the catalysts modified by other type of carbon materials, the ACF-promoted catalyst prepared via carbonate-coprecipitation method exhibit the highest performance in the low-temperature steam reforming of methanol. It was suggested that the intrinsic high surface area nature of ACF material may favor the generation of modified catalysts with a high surface area and improved component dispersion, thus leading to improved performance for methanol steam reforming.展开更多
A novel coprecipitation-reduction process has been proposed for preparing highly selective Cu/ZnO/Al 2O 3 catalysts for methanol synthesis from CO 2 hydrogenation. Compared to the catalysts prepared by the conventiona...A novel coprecipitation-reduction process has been proposed for preparing highly selective Cu/ZnO/Al 2O 3 catalysts for methanol synthesis from CO 2 hydrogenation. Compared to the catalysts prepared by the conventional method, the new catalysts prepared via the new method exhibit much higher BET surface area and pore size, much smaller crystallite size and higher catalytic activity and selectivity in CO 2 hydrogenation to methanol. It is also found that the molar ratio of Cu + to Cu 0 on the surface of the catalyst obtained by coprecipitation-reduction is much higher than that on the reduced catalyst obtained by the conventional method, which could be crucial for its high activity and selectivity for catalytic hydrogenation of CO 2 to methanol.展开更多
文摘以尿素为沉淀剂,采用均相沉淀法成功制备了层状Cu/Zn/Al水滑石化合物.将前驱体材料经焙烧、还原后得到Cu/ZnO/Al_2O_3催化剂,并将其用于CO_2加氢合成甲醇反应.采用X射线衍射(X-ray diffraction,XRD)、热重(thermogravimetric,TG)分析、扫描电镜(scanning electron microscope,SEM)、X射线荧光(X-ray fluorescence,XRF)分析、N_2吸附、H_2程序升温还原(H_2-temperature program reduction,H_2-TPR)、氧化亚氮(N_2O)反应吸附、CO_2程序升温脱附(CO_2-temperature program desorption,CO_2-TPD)技术对所制备的样品进行表征.结果表明,相对于传统共沉淀法,以尿素作为沉淀剂,通过均相沉淀法所制备的前驱体的结晶度更高、催化剂比表面积更大、金属Cu的分散度更好.另外,采用回流处理可以获得更好的效果.活性评估结果表明,O_2转化率随金属Cu比表面积的增大而增加,而甲醇选择性则与催化剂表面碱性位的分布有关.因此,采用尿素回流处理均相沉淀法制备的Cu/ZnO/Al_2O_3催化剂的甲醇收率最高.
文摘We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the catalyst for methanol steam reforming. It is shown by in situ XRD that a considerable increase in the microstrain of Cu nanocrystals could be achieved in the catalysts processed by microwave irradiation for 310 min, which correlates well with the enhanced CH3OH conversion as observed on the corresponding samples. The present work also confirms that although the high specific surface area of Cu is a prerequisite for catalytic activity, it does not account for the observed changes in activity and selectivity alone without taking bulk microstructural changes into account.
文摘A number of nanostructured carbon materials were proposed as new effective promoters for preparing modified Cu/ZnO/Al 2O 3 catalyst system for efficient hydrogen production from methanol steam reforming. Compared to the catalysts modified by other type of carbon materials, the ACF-promoted catalyst prepared via carbonate-coprecipitation method exhibit the highest performance in the low-temperature steam reforming of methanol. It was suggested that the intrinsic high surface area nature of ACF material may favor the generation of modified catalysts with a high surface area and improved component dispersion, thus leading to improved performance for methanol steam reforming.
文摘A novel coprecipitation-reduction process has been proposed for preparing highly selective Cu/ZnO/Al 2O 3 catalysts for methanol synthesis from CO 2 hydrogenation. Compared to the catalysts prepared by the conventional method, the new catalysts prepared via the new method exhibit much higher BET surface area and pore size, much smaller crystallite size and higher catalytic activity and selectivity in CO 2 hydrogenation to methanol. It is also found that the molar ratio of Cu + to Cu 0 on the surface of the catalyst obtained by coprecipitation-reduction is much higher than that on the reduced catalyst obtained by the conventional method, which could be crucial for its high activity and selectivity for catalytic hydrogenation of CO 2 to methanol.
