Highly active K-promoted Cu/β-Mo2C catalysts for reverse water gas shift reaction: Effect of potassium

• 100% CO selectivity was achieved by RWGS over the Cu/Mo 2 C-1 K catalyst at low temperatures. • The structural and electronic effects induced by K species facilitate the adsorption and activation of CO 2 . • The redox and association mechanism coexists in the RWGS reaction on the K-promoted Cu/Mo 2 C catalysts. The K-promoted Cu/β-Mo 2 C catalysts with different K loadings were prepared for the reverse water gas shift (RWGS) reaction. The results showed that the incorporation of potassium into the Cu/β-Mo 2 C catalyst significantly increased CO 2 conversion and CO selectivity at an optimal K loading. The remarkable catalytic performance of the 1K-Cu/Mo 2 C catalyst was due to the presence of highly dispersed Cu nanoparticles and the improved CO 2 activation and dissociation caused by the structural and electronic effect of potassium. The presence of K also suppresses H 2 adsorption and inhibits the methanation of CO 2 . The gas switching experiments and in-situ DRIFTS analyses suggest that both the redox and associative mechanism coexists in the RWGS reaction and that the formate species act as the intermediates in converting CO 2 to CO for the K-promoted Cu/β-Mo 2 C catalysts.