Selective CO production from CO2 over a metal catalyst supported on perovskite oxide in the presence of excess hydrogen

Hydrogenation of carbon dioxide (CO₂) to liquid fuels via an industrial catalytic reaction is the most effective strategy for the realization of carbon neutrality. The sequential reaction system of a reverse water–gas shift (RWGS) reaction followed by Fischer–Tropsch synthesis is a promising way to achieve this; hence, the development of catalysts with high conversion efficiency and selectivity for RWGS is required. We succeeded in the conversion of CO₂ into carbon monoxide (CO) with a selectivity of 100% in the gas phase using a platinum-loaded perovskite oxide support composed of barium and zirconium, in which 10% of zirconium was substituted with yttrium (Pt/BaZr_0.9Y_0.1O_3−δ, Pt/BZY10) at 500 °C in the gas stream with H₂/CO₂ = 3. Furthermore, a ruthenium-loaded catalyst (Ru/BZY10) afforded not only CO but also methane (CH₄) as gaseous products. Kinetic analysis demonstrated that the activation energy was identical for both catalysts, and Fourier transform infrared spectroscopy clarified that the surface-adsorbed methoxy group was generated as a reaction intermediate only in the case of Ru/BZY10, which indicated the ability of the loaded metal for the dissociative adsorption of hydrogen. The present research is expected to provide a new methodology for the preparation of catalysts for the RWGS reaction and a quite important insight for the realization of carbon neutrality.