CO2 methanation over Co[sbnd]Ni bimetal-doped ordered mesoporous Al2O3 catalysts with enhanced low-temperature activities

Abstract

The Ni based catalysts have been considered as potential candidates for the CO2 methanation owing to the low cost. However, the poor low-temperature catalytic activities limit their large-scale industrial application. In order to address this challenge, a series of CoNi bimetal doped ordered mesoporous Al2O3 materials have been designed and fabricated via the one-pot evaporation induced self-assembly strategy and employed as the catalysts for CO2 methanation. It is found that the large specific surface areas (up to 260.0 m2/g), big pore volumes (up to 0.59 cm3/g), and narrow pore size distributions of these catalysts have been successfully retained after 700 °C calcination. The Co and Ni species are homogenously distributed among the Al2O3 matrix due to the unique advantage of the one-pot synthesis strategy. The strong interaction between metal and mesoporous framework have been formed and the severely thermal sintering of the metallic CoNi active centers can be successfully inhibited during the processes of catalyst reduction and 50 h CO2 methanation reaction. More importantly, the synergistic effect between Co and Ni can greatly enhance the low-temperature catalytic activity by coordinating the activation of H2 and CO2, prominently decreasing the activation energy toward CO2 methanation. As a result, their low-temperature activities are evidently promoted. Furthermore, the effect of the Co/(Co + Ni) molar percentage ratio on the catalytic property has been also systematically investigated over these catalysts. It is found that only the catalyst with appropriate ratio (20.0%) behaves the optimum catalytic performances. Therefore, the current CoNi based ordered mesoporous materials promise potential catalysts for CO2 methanation.