Highly dispersed Ni-Ce-Zr mixed oxides supported on mesoporous γ-alumina (Ni-Ce-Zr/γ-MA) were prepared by a citric acid (CA)-assisted impregnation method and evaluated as catalysts for the methanation of CO2 with H2. The effects of the CA content of the reaction solution on the physicochemical properties and the catalytic performance of the Ni-Ce-Zr/γ-MA catalysts were investigated in detail. The addition of CA promoted the dispersion of the Ni-Ce-Zr oxide species on the γ-alumina surface and improved the interactions between the Ni oxide species and the support, resulting in the formation of homogeneously dispersed Ni nanoparticles in the γ-MA frameworks upon reduction with H2. The resulting Ni-Ce-Zr/γ-MA catalysts were highly active and showed almost 100% selectivity for CH4 during the methanation of CO2 at temperatures in the range of 150-400℃. Notably, the catalytic activity increased as the molar ratio of CA/(Ni+Ce+Zr) increased in the range of 0-2. This effect was most likely caused by the associated decrease in the Ni particle size and the improved electronic and structural properties of the Ni-Ce-ZrOx species. The results of a stability test for the Ni-Ce-Zr/γ-MA catalyst prepared with a CA/(Ni+Ce+Zr) molar ratio of 1.0 showed that there was only a 7% decrease in the CO2 conversion following a reaction time of 300 h at 300℃ with negligible coke deposition, indicating excellent catalytic stability and good anti-coking ability of these systems for the methanation of CO2.
Fund: 上海市教育委员会科研项目;国家重点基础研究发展规划项目（973）(2014CB643403);国家杰出青年科学基金(51225401);上海市科委基础重点项目(14JC1491400);the Innovation Program of Shanghai Municipal Education Commission;National Key Basic Research Program of China (973)(2014CB643403);National Science Fund for Distinguished Young Scholars, China(51225401);Basic Major Research Program of Science and Technology Commission Foundation of Shanghai, China(14JC1491400)
Xiu-Jing ZOU,Xue-Guang WANG
Wang-Xin NIE,Xiu-Jing ZOU,Xue-Guang WANG,Wei-Zhong DING,Xiong-Gang LU. Preparation of Highly Dispersed Ni-Ce-Zr Oxides over Mesoporous γ-Alumina and Their Catalytic Properties for CO2 Methanation. Acta Physico-Chimica Sinca, 2016, 32(11): 2803-2810.