Enhanced CO2 hydrogenation to higher alcohols over K-Co promoted In2O3 catalysts

Abstract

The use of CO2 to produce higher alcohols is a promising route to reduce emissions and make a profit. However, low activity of existing catalysts is a barrier for such processes to reach the industrial level. Here we report a novel K-Co promoted In2O3 catalyst for CO2 hydrogenation to higher alcohols. The K-Co promoted In2O3 with an optimum K and Co of 2.5 and 5.0 wt% achieves a high C2+OH space time yield of 169.6 g kgcat−1h−1 with the excellent C2+OH distribution of 87.4% in the total alcohols, while a very low space time yield of C2+OH (0.4 g kgcat−1h−1) is obtained over In2O3 promoted with 5 wt% Co. Characterization results reveal that, after reduction with H2 at 380 °C for 2 h, K-O-Co species is created for K-Co promoted In2O3 (2.5 wt% K and 5 wt% Co) sample which significantly reduces a number of weak H2 adsorption and strengthens the interaction of adsorbed H compared to 5 wt% Co promoted In2O3 sample containing a mixture of Co0 and CoO. The reduction of weak H2 adsorption and the improved interaction of adsorbed H with the catalyst surface retard the hydrogenation ability, allowing the CO insertion into adsorbed CxHy species prior to its hydrogenation to form hydrocarbon, resulting in a remarkable reduction of CH4 and higher hydrocarbon, and significant improvement of higher alcohols.