A highly active Pt/In2O3 catalyst for CO2 hydrogenation to methanol with enhanced stability

Abstract

Supported Pt catalysts have been extensively investigated for CO₂ hydrogenation with methane and CO as the principal products. In this work, a Pt/In₂O₃ catalyst prepared with decomposition precipitation was tested for CO₂ hydrogenation to methanol. The Pt/In₂O₃ catalyst exhibited a highly improved activity towards CO₂ hydrogenation, with methanol selectivity of ca. 100% at temperatures below 225 °C, 74% at 275 °C and 54% at 300 °C, respectively, compared to the pure In₂O₃ catalyst. This represents the highest methanol selectivity reported on Pt catalysts for CO₂ hydrogenation. The stability of the Pt/In₂O₃ catalyst at elevated temperatures has also been higher than that of the pure In₂O₃ catalyst, indicated by the methanol formation rate decreasing only to 95% of the initial rate after 5 h in the reaction stream and remaining largely constant thereafter. In contrast, the pure In₂O₃ catalyst loses 20% of the initial methanol formation rate after 9 h in the reaction stream. The characterization of the catalysts confirms that the Pt nanoparticles are well dispersed on In₂O₃ with a particle size below 3 nm. The strong metal–support interaction (SMSI) between Pt and In₂O₃ improves the stability of the catalyst and prevents the over-reduction of In₂O₃. The synergy between the supported Pt nanoparticles and In₂O₃ balances the hydrogen activation and the density of the surface oxygen vacancies in In₂O₃, resulting in the high activity for CO₂ hydrogenation and enhanced stability of the Pt/In₂O₃ catalyst.