Combustion-impregnation preparation of Ni/SiO2 catalyst with improved low-temperature activity for CO2 methanation

Abstract

Exploiting Ni-based catalysts with excellent low-temperature activity is significant for CO2 methanation, which is a promising route to CO2 utilization. In this work, a facile combustion-impregnation method was developed to prepare the SiO2 supported Ni catalysts. Small Ni particles (around 6 nm) and massive Ni–SiO2 interface could be obtained due to the “combustion” process. The H2-temperature programmed desorption (H2-TPD) revealed the existence of Ni–SiO2 interface and confirmed the high Ni dispersion obtained by this method, which were vital for the activation of reactant. Moreover, more medium basic sites which were beneficial for the CO2 activation could also be created. In comparison with the reference Ni/SiO2 catalyst prepared by the conventional impregnation method, much higher CO2 conversion (66.9%) and more superior selectivity to CH4 (94.1%) were achieved with the Ni/SiO2-Gly catalyst at 350 °C. Additionally, it was also found that glucose, citric acid and glycine were all effective fuels for this combustion-impregnation method, and the as-prepared catalysts all exhibited greatly improved low-temperature activity. Therefore, this work represents an important step toward developing Ni-based catalysts for CO2 methanation by a promising wide-used method.