Unravelling the role of metal-metal oxide interfaces of Cu/ZnO/ZrO2/Al2O3 catalyst for methanol synthesis from CO2: Insights from experiments and DFT-based microkinetic modeling

Cu/ZnO/ZrO2/Al2O3 catalysts are widely explored for CO2 conversion to methanol due to their higher activity and stability. However, mechanistic understanding of the performance of such catalysts is lacking due to ambiguity on the actual active sites. This study focuses on unraveling the nature of different interfaces on Cu/ZnO/ZrO2/Al2O3 catalyst by coupling experiments, Density Functional Theory (DFT) simulations and a DFT-based reactor scale multi-site microkinetic model. Although DFT calculations suggested the ZrO2/Cu interface to be the CO2 adsorption site, the validated microkinetic model predicted the ZnO/Cu interface to be the crucial reaction center. Reaction pathway analysis showed that methanol is produced through the formate pathway near the reactor entrance, whereas, the carboxyl pathway dominates in the latter zones, emphasizing the occurrence of both CO2 and CO hydrogenation. This deeper understanding of the reaction behavior of such multicomponent catalysts will aid in designing better catalysts and optimizing reaction conditions and systems.