Highly selective hydrogenation of CO2 to C5+ hydrocarbons over Fe catalysts copromoted by K with Pd

Abstract

CO2 hydrogenation to liquid fuels is significant to reduce CO2 emissions and replace fossil fuels. Herein, we reported that Fe catalysts promoted by combination of K and Pd showed a three-synergistic catalytic effect to high selectivity of C5+ hydrocarbons in CO2 hydrogenation reaction. The catalysts were prepared using an impregnation method and characterized with physical adsorption, XRD, XPS, HRTEM, H2-TPR, H2-TPD and CO2-TPD. The results indicated that K0.016Pd0.12Fe catalysts showed K-overlapped PdFe-like alloy structure which enhanced H2 activation behaviors and moderately chemisorption of CO2. K addition promoted Fe to activate carbide species while active H originated from H2 pool generated by PdFe alloy spilled to Fe species surface, consequently boosting not only conversion of CO2 to 41.8% but also selectivity of C5+ hydrocarbon to 70.6%. The maximum yield of long-chain C5+ hydrocarbon reached up to 20.0% under high space velocity 6000 mL gcat−1 h−1. These results provide a new insight to develop highly selective Fe based catalysts for long-chain hydrocarbons via CO2 hydrogenation.