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

The Co-CeO2 catalysts with different cobalt contents were prepared via co-precipitation method and used for reverse water-gas shift (RWGS: CO2 + H-2 -> 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. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.