Reverse water–gas shift reaction over co-precipitated Co–CeO2 catalysts: Effect of Co content on selectivity and carbon formation

Abstract

The Co–CeO2 catalysts with different cobalt contents were prepared via co-precipitation method and used for reverse water–gas shift (RWGS: CO2 + H2 → CO + H2O) reaction. Characterizations of the catalysts were conducted by XRD, TPR, TPO, TEM and SEM. The results show that highly dispersed Co3O4 interacted with CeO2 is formed in 2% Co–CeO2 catalyst, and the catalyst shows excellent RWGS catalytic performance in terms of activity, selectivity and low carbon deposition. However, in the catalysts with high Co loading amount (≥5%), bulk Co3O4 with larger particle size is formed, which leads to obviously increased carbon deposition and by-product CH4 production during the reaction. These results suggest that highly dispersed Co, reduced from highly dispersed Co3O4 on CeO2, should be the key active component for RWGS reaction; while bulk Co with large particle size should be the key active component for methanation and carbon deposition.