Methanol Synthesis Over PdIn, In2O3, and CuZn From First-Principles Microkinetics: Similarities and Differences

Methanol synthesis via catalytic CO2 hydrogenation is an important reaction where a valuable fuel and chemical is produced from a greenhouse gas. In2O3- and Pd-promoted In2O3 have experimentally shown promising activity and selectivity, although the nature of the active sites remains under debate. In this study, the kinetic behavior of potential active sites in Pd-promoted In2O3 toward methanol synthesis and the competing reverse water-gas shift reaction is assessed by exploring pristine In2O3 and a PdIn intermetallic phase by using first-principles mean-field microkinetics. The PdIn intermetallic phase is modeled with PdIn(310) and In2O3 with In2O3(110). The results are compared to Zn-decorated Cu(211), representing the commercial Cu/ZnO-based catalyst. PdIn shows better performance than both the unpromoted In2O3 and Zn-decorated Cu at conditions relevant to the industrial process. For all three systems we find that stabilization of adsorbed hydrogen enhances activity toward methanol, which provides insights for further catalyst development