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 H-2 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 (C-1-C-4) 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.