Tuning interaction of surface-adsorbed species over Fe/K-Al₂O₃ modified with transition metals (Cu, Mn, V, Zn or Co) on light olefins production from CO₂ hydrogenation

The presence of transition metals (Cu, Co, Zn, Mn or V) in Fe/K-Al₂O₃, modifying the adsorption-desorption properties of CO₂ and H₂ with the catalyst surface remarkably influences the catalytic performance for CO₂ hydrogenation to light olefins. The addition of either Cu or Zn to Fe/K-Al₂O₃ significantly increases the number of weakly adsorbed H atom, yielding the high CO₂ conversion and shifting the product distribution towards longer chain hydrocarbon with a higher content of paraffins. The addition of Co to Fe/K-Al₂O₃ also enhances the CO₂ conversion but it provides the short chain hydrocarbon (C₁-C₄) and thus achieving the highest light olefins yield of 16.2%. The presence of either Mn or V inhibits the CO hydrogenation to hydrocarbon, leading to the low CO₂ conversion. The Mn promoter reduces the number of weakly adsorbed H atom, lowering the hydrogenation ability of the catalyst, resulting in the highest olefin to paraffin ratio of 7.4.