Size effect of the CoxMn1−xO precursor for Fischer–Tropsch to olefins over Co2C-based catalysts

Abstract

The size effect of the Co_xMn_1−xO precursor on the formation of Co₂C nanoprisms and the structure–performance relationship for the Fischer–Tropsch to olefins (FTO) reaction was investigated. Co_xMn_1−xO precursors with different sizes from 6.5 nm to 16.7 nm were fabricated by calcination at different temperatures. The Co_xMn_1−xO with small size possessed high concentration of oxygen vacancies, which promoted the dissociation of CO to form active C* species, and more Co₂C nanoprisms with small size could be generated. In addition, the catalytic performance also changed with the size of the precursor. The olefin formation rate significantly increased from 3.36 to 12.48 μmol g_CoxMn1−xO⁻¹ h⁻¹ as the Co_xMn_1−xO size decreased from 16.7 to 6.5 nm. This work clearly elucidates the size effect of the Co_xMn_1−xO precursor on the structure–performance relationship and may provide a practical and simple strategy to fabricate highly efficient CoMn catalysts for the FTO reaction.