Modified Ni-carbonate interfaces for enhanced CO₂ methanation activity: Tuned reaction pathway and reconstructed surface carbonates

A Ni/Zr-La₂O₂CO₃ catalyst with interfaces between Ni metal and Zr-modified carbonate support was used for atmospheric CO₂ methanation reaction, exhibiting 81% conversion and 99.6% CH₄ selectivity at 300 °C. The Zr⁴⁺ ions incorporated in La₂O₂CO₃ lattices properly strengthened the Ni-carbonate interaction for enhancing the Ni dispersion and hydrogen activation ability of the catalyst. The Zr-modification could also tune the surface basic property for promoting the adsorptive dissociation of CO₂. In-situ DRIFT spectra demonstrated that only the hydrogenation reaction pathway of formate intermediates was proceeded in Ni/La₂O₂CO₃-catalyzed CO₂ methanation. As a contrast, the hydrogenation pathways of CO and formate intermediates with relatively high activity were co-existed at the modified Ni-Zr-La₂O₂CO₃ interfaces. Furthermore, the isotopic data evidenced that dynamic reconstruction and interconversion of the surface carbonate species occurred in the reaction, which might contribute to the key steps of CO₂ dissociation and intermediates transformation.