Unveiling the role of carbonaceous supports in CO₂ methanation reaction

Carbon dioxide methanation is a promising approach for CO₂ mitigation. However, the high-energy demand and substantial cost of the catalysts preclude its scaling up. Carbon-based materials can offer several advantages, such as high surface area and reasonable cost. Although many carbon materials have been reported as catalyst supports for CO₂ methanation, it is still ambiguous what the most suitable carbon support for Ni-based catalysts is. Herein, a comparative study on various carbon materials [graphite, graphene oxide (GO), biochar, activated carbon (AC), and carbon nanotubes (CNTs)] verifying the advantages of CNTs compared to other supports.The study demonstrated that Ni/CNTs offered the best catalytic performance attributed to excellent thermal stability and high surface area, in addition to their unique tubular structure that precluded agglomeration. On the other hand, Ni/graphite and Ni/rGO expressed limited catalytic reactivity, attributed to the low surface area of graphite and GO layers stacking, occured during the hydrogenation at high operating temperatures. Despite the high surface area of biochar and AC, they showed thermal instability due to their high content of amorphous carbon. This study paves the way for understanding the impact of the carbon supports on the catalytic performance, and leads to accurate evaluation of the carbon supports to select precisely which support can fit with which application, not limited to CO₂ methanation.