CO2 hydrogenation to methanol over the copper promoted In2O3 catalyst

The metal promoted In 2 O 3 catalysts for CO 2 hydrogenation to methanol have attracted wide attention because of their high activity with high methanol selectivity. However, there was still no experimental confirmation if copper could be a good promoter for In 2 O 3 . Herein, the Cu promoted In 2 O 3 catalyst was prepared using a deposition-precipitation method. Such prepared Cu/In 2 O 3 catalyst shows significantly higher CO 2 conversion and space time yield (STY) of methanol, compared to the un-promoted In 2 O 3 catalyst. The loading of Cu facilitates the activation of both H 2 and CO 2 with the interface between the Cu cluster and defective In 2 O 3 as the active site. The Cu/In 2 O 3 catalyst takes the CO hydrogenation pathway for methanol synthesis from CO 2 hydrogenation. It exhibits a unique size effect on the CO adsorption. At temperatures below 250 °C, CO adsorption on Cu/In 2 O 3 is stronger than that on In 2 O 3 , causing higher methanol selectivity. With increasing temperatures, the Cu catalyst aggregates, which leads to the formation of weak CO adsorption site and causes a decrease in the methanol selectivity. Compared with other metal promoted In 2 O 3 catalysts, it can be concluded that the catalyst with stronger CO adsorption possesses higher methanol selectivity.