CO2 hydrogenation to methanol has attracted increasing attention with the development of renewable hydrogen. Here we report an In2O3 supported Au catalyst that exhibits excellent performance for hydrogenation of CO2 selectively to methanol. In-situ characterizations using time-resolved X-ray diffraction (TR-XRD), ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), and X-ray absorption spectroscopy (XAS) confirm that a strong metal-support interaction leads to a reactive Auδ+-In2O3-x interface for activation and hydrogenation of CO2 to methanol. An effective gold-indium oxide bonding favors the dispersion of the noble metal and prevents its sintering under reaction conditions. The methanol selectivity reaches 67.8% at 300 °C with a space time yield (STY) of methanol of 0.47 gMeOH/(h gcat). The strong metal-support interaction was also confirmed theoretically by performing density functional theoretical (DFT) calculation on a Au4/In2O3 model catalyst. This interaction causes the electron redistribution at the interfacial sites and leads to a positively charged Auδ+ cluster instead of metallic Au0, consisting with the in-situ characterization results. This electron redistribution facilitates the methanol synthesis by several ways: leading to an active and positively charged Au4 cluster for H2 dissociation; providing Au-In2O3 interfacial sites for CO2 activation and intermediates to be hydrogenated to methanol; and benefiting the removal of hydroxyl to prohibit the catalyst deactivation. All these effects account for the fact that Au/In2O3 catalyst is a promising candidate for the methanol synthesis from CO2 selective hydrogenation. Our study shows that the strong Au-In2O3 interaction and the intrinsic chemical activity of In2O3 can be used to significantly improve the catalytic performance of Au catalysts, providing promising routes for the rational design and application of Au catalyst beyond CO2 hydrogenation.

Hydrogenation of CO2 to methanol on a Auδ+–In2O3–x Catalyst: Boosting conversion, selectivity, and stability through metal-support interaction

ACS Fall 2021

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