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

Abstract

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.