In situ investigation of the CO₂ methanation on carbon/ceria-supported Ni catalysts using modulation-excitation DRIFTS

The development of novel cost-efficient, high-performing catalysts for CO₂ methanation that are active at low temperatures can be optimized through the understanding of the reaction mechanism on different materials. A series of Ni-based catalysts supported on CeO₂ and carbon/CeO₂ composites was investigated, showing that Ni nanoparticles supported on a carbon/CeO₂ composite with a 50:50 weight ratio and on pure CeO₂ have excellent low-temperature activity and achieve up to 87% CO₂ conversion with full selectivity towards CH₄ at 370 °C. Importantly, meaningful insights on the reaction mechanism were gathered for the different types of materials by using the emerging ME−PSD−DRIFTS technique. The study of the rate of formation/consumption of the various intermediates showed that the CO₂ methanation reaction follows a combination of the CO and formate pathways in the case of Ni on pure CeO₂; however, in the case of Ni on the carbon/CeO₂ composite, it follows only the formate pathway.