The hollow inverse CeO2/CuO@SiO2 catalysts with different Ce/Cu mass ratios were synthesized by the two-step hydrothermal and incipient wetness impregnation methods,and characterized by multitechnique characterization...The hollow inverse CeO2/CuO@SiO2 catalysts with different Ce/Cu mass ratios were synthesized by the two-step hydrothermal and incipient wetness impregnation methods,and characterized by multitechnique characterizations,such as SEM,TEM,XRD,H2-TPR,XPS and N2 adsorption-desorption techniques.It is found that the hollow shell is composed of CuO and SiO2,and CeO2 nanoparticles are coated on the surface of CuO@SiO2 support.And the CeO2/CuO@SiO2 catalyst with the Ce/Cu mass ratios of 1:1 denoted as 1 CeO2/CuO@SiO2,which possesses a maximum amount of highly dispersed copper species and medium-sized CuO as well as the highest concentration of oxygen vacancies,exhibits the highest catalytic activity and widest full CO conversion window.The barrier effect of the SiO2 shell effectively prevents the reduction of CuO species,which broadens temperature window of CO total conversion and enhances CO2 selectivity above 155℃over the 1 CeO2/CuO@SiO2 catalyst in comparison with the CuO-CeO2 and CeO2-CuO catalysts.展开更多
XRD, Raman, TEM, and N2-adsorption were utilized to characterize CeO2/SiO2 prepared by coprecipi-tation and surfactant-assisted method. The results show that nanocrystalline CeO2 can be uniformly supported on the surf...XRD, Raman, TEM, and N2-adsorption were utilized to characterize CeO2/SiO2 prepared by coprecipi-tation and surfactant-assisted method. The results show that nanocrystalline CeO2 can be uniformly supported on the surface of SiO2 particles, when the molar ratio of Si4+/(Ce3++Si4+) is less than 35% in coprecipitation samples. At higher Si content, the surface of SiO2 can not be fully covered by CeO2. With surfactant (CTAB) added, the u-iformly supported structure can even exist when the molar ratio of Si4+/(Ce3++Si4+) is as high as 53%. It is because Ce and Si complexes can be well dispersed in precursor solution in present of CTAB. However, the uniformly supported structure can not be synthesised through surfactant-assisted approch for its hydrothermal threatment, which can easily lead to separate aggregation of nanocrystalline CeO2 and SiO2 particles.展开更多
基金Project supported by the National Natural Science Foundation of China(21466024)the Natural Science Foundation of Inner Mongolia(2018MS02020,2018BS02008)
文摘The hollow inverse CeO2/CuO@SiO2 catalysts with different Ce/Cu mass ratios were synthesized by the two-step hydrothermal and incipient wetness impregnation methods,and characterized by multitechnique characterizations,such as SEM,TEM,XRD,H2-TPR,XPS and N2 adsorption-desorption techniques.It is found that the hollow shell is composed of CuO and SiO2,and CeO2 nanoparticles are coated on the surface of CuO@SiO2 support.And the CeO2/CuO@SiO2 catalyst with the Ce/Cu mass ratios of 1:1 denoted as 1 CeO2/CuO@SiO2,which possesses a maximum amount of highly dispersed copper species and medium-sized CuO as well as the highest concentration of oxygen vacancies,exhibits the highest catalytic activity and widest full CO conversion window.The barrier effect of the SiO2 shell effectively prevents the reduction of CuO species,which broadens temperature window of CO total conversion and enhances CO2 selectivity above 155℃over the 1 CeO2/CuO@SiO2 catalyst in comparison with the CuO-CeO2 and CeO2-CuO catalysts.
基金Projects supported by National Natural Science Foundation of China(20806035)Applied Basic Research Plans Program of Yunnan Province(2007E187M)+1 种基金Scientific Research Fund of Yunnan Provincial Education Department(08C0025)Analysis and Measurement Research Fund of Kunming University of Science and Technology(2008-003)
文摘XRD, Raman, TEM, and N2-adsorption were utilized to characterize CeO2/SiO2 prepared by coprecipi-tation and surfactant-assisted method. The results show that nanocrystalline CeO2 can be uniformly supported on the surface of SiO2 particles, when the molar ratio of Si4+/(Ce3++Si4+) is less than 35% in coprecipitation samples. At higher Si content, the surface of SiO2 can not be fully covered by CeO2. With surfactant (CTAB) added, the u-iformly supported structure can even exist when the molar ratio of Si4+/(Ce3++Si4+) is as high as 53%. It is because Ce and Si complexes can be well dispersed in precursor solution in present of CTAB. However, the uniformly supported structure can not be synthesised through surfactant-assisted approch for its hydrothermal threatment, which can easily lead to separate aggregation of nanocrystalline CeO2 and SiO2 particles.
