Stabilizing Co(2)C with H(2)O and K promoter for CO(2) hydrogenation to C(2+) hydrocarbons

The decomposition of cobalt carbide (Co(2)C) to metallic cobalt in CO(2) hydrogenation results in a notable drop in the selectivity of valued C(2+) products, and the stabilization of Co(2)C remains a grand challenge. Here, we report an in situ synthesized K-Co(2)C catalyst, and the selectivity of C(2+) hydrocarbons in CO(2) hydrogenation achieves 67.3% at 300°C, 3.0 MPa. Experimental and theoretical results elucidate that CoO transforms to Co(2)C in the reaction, while the stabilization of Co(2)C is dependent on the reaction atmosphere and the K promoter. During the carburization, the K promoter and H(2)O jointly assist in the formation of surface C(*) species via the carboxylate intermediate, while the adsorption of C(*) on CoO is enhanced by the K promoter. The lifetime of the K-Co(2)C is further prolonged from 35 hours to over 200 hours by co-feeding H(2)O. This work provides a fundamental understanding toward the role of H(2)O in Co(2)C chemistry, as well as the potential of extending its application in other reactions.