Selective hydrogenation of CO2 to methanol catalyzed by Cu supported on rod-like La2O2CO3

Abstract

Cu-based catalysts have long been applied to convert CO₂ and H₂ into methanol, and their performances are well known to be markedly influenced by the support and promoter. Herein, several Cu-based catalysts supported on lanthanum oxides were fabricated by varying the preparation methods and characterized by XRD, TEM, ICP-AES, N₂ physisorption, N₂O chemisorption, CO₂ chemisorption, XPS, and CO₂-TPD. The results showed that the as-prepared Cu supported on rod-like La₂O₂CO₃ (La₂O₂CO₃-R) exhibited the highest TOF_Cu, methanol selectivity and yields of methanol for the hydrogenation of CO₂ to methanol. Distinct from conventional promoter addition, the local formation of a new type of Cu^δ+ species at Cu/La₂O₂CO₃-R interfaces and the original adsorption performance of basic oxides are the two key factors relating to the catalytic performance. Cu supported on La₂O₂CO₃-R with a higher content of Cu^δ+ species and a stronger adsorption for CO₂ leads to superior catalytic activities. DRIFTS studies revealed that the generation of synergetic basic sites at the interfacial areas can increase the intrinsic activity of Cu-based methanol catalysts by moderately and selectively stabilizing methanol synthesis intermediates. This work provides new insights into CO₂ activation over basic oxide-supported Cu catalysts, and the identification of metal–support interactions between Cu and lanthanum oxides is beneficial for the rational design of stable Cu-based catalysts.