Substituted LaNiO3 Perovskites for Efficient CO2 Methanation: Unveiling the Synergy of Basicity and Oxygen Storage

Carbon dioxide mitigation has become a challenging concern as the world increasingly focuses on carbon neutrality. Producing high hydrogen storage density materials (such as CH₄) from CO₂ using catalytic hydrogenation is widely considered an efficient and promising route to tackle the gas in substantial amounts and carbon recycling. Ni-based materials have been the focus of several implementation strategies due to their low cost, high compatibility, and high activity. Small and highly dispersed active species are coke-resistant and resistive to thermal sintering; such compositions can be easily derived from perovskite-type materials. A hydrothermal approach has been implemented to synthesize LaNiO₃ and its derivatives via A/B-site partial substitution. Glycine is used as a structure-directing agent to achieve a nanocube-type shape, and a purely polycrystalline perovskite structure is obtained in an oxygen atmosphere during calcination. The structure–activity relationship is established through various catalyst characterization techniques (XRD, TPR, CO₂-TPD, OSC, TGA, SEM, and TEM analysis). The combined effect of moderate basicity and high oxygen storage capacity helps achieve higher catalytic activity of La_0.9Sm_0.1NiO₃ for CO₂ methanation. Partial replacement of Sm in the base catalyst leads to 89% CO₂ conversion with 100% CH₄ selectivity for a long span tested up to 200 h without deactivation. The TPSR study provides evidence that the carbon dioxide activation proceeds through a dissociative mechanism as CO and O* intermediates, which is further assisted by insitu DRIFT studies.