Coal char supported Ni catalysts prepared for CO2 methanation by hydrogenation

Abstract

Catalytic CO2 methanation is a potential solution for conversion of CO2 into valuable products, and the catalyst plays a crucial role on the CO2 conversion and CH4 selectivity. However, some details involved in the CO2 methanation over the carbon supported Ni catalysts are not yet fully understood. In this work, commercial coal char (CC) supported Ni catalysts were designed and prepared by two different methods (impregnation-thermal treatment method and thermal treatment-impregnation method) for CO2 methanation. Effects of the preparation conditions (including the thermal treatment temperature and time, the mass ratio of CC:Ni and the preparation method), as well as the reaction temperature of CO2 methanation, were investigated on the catalyst morphology, reducibility, structure and catalytic performance. Fibrous Ni-CC catalyst is achieved and shows high CO2 conversion (72.9%–100%) and CH4 selectivity (>99.0%) during the 600-min methanation process. Adverse changes of the catalyst surface and textural properties, reducibility, particle size and morphology are the potential factors leading to the catalyst deactivation, and possible solutions resistant to the deactivation were analyzed and discussed. The CO2 methanation mechanism with the CO route was proposed based on the oxidation-reduction cycle of Ni in this work.