Unraveling the role of cobalt in the direct conversion of CO2 to high-yield liquid fuels and lube base oil

Abstract

Owing to their high CO2 methanation activity, the direct hydrogenation of CO2 to long-chain C5+ over Co-based catalysts is challenging. Here, we demonstrate a Na- and Mn-promoted, core-shell Co@CoOx/Co2C catalyst that produces a high C5+ yield of 21.1% at a CO2 conversion of 64.3% and low temperature of 270 °C. CO2 conversion and C5+ selectivity are ensured during long-term catalytic reactions up to 1425 h. C21+ selectivity increases to 14.9% with increasing time on stream. The catalyst exhibits high C5+ and C21+ selectivity, making it a promising option for producing liquid fuels and lube base oil in one-pass CO2 conversion. Direct CO2 dissociation and formate formation over the oxygen-vacant Co3O4 phase in the shell is the plausible reverse–water–gas–shift reaction mechanism. The Mn promoter facilitates the formation of the CoOx phase at the outermost surface, suppressing the direct contact between CO2 and the metallic Co core.