The rare earth elements modified FeK/Al2O3 catalysts for direct CO2 hydrogenation to liquid hydrocarbons

The present work reports on the promoting effects of rare earth elements (La, Ce and Y) to FeK/Al 2 O 3 catalysts on liquid hydrocarbons from CO 2 hydrogenation. The addition of La, Ce and Y can both improve the selectivity of C 5+ hydrocarbons and reduce the selectivity of CH 4 . The C 5+ selectivity can enhance to about 60 % with CH 4 selectivity of around 11 % at CO 2 conversions above 20 %. N 2 adsorption–desorption, in situ XRD, H 2 –TPR, CO 2 /H 2 –TPD, HRTEM and XPS are used to characterize the FeK/Al 2 O 3 and FeK/M-Al 2 O 3 (M = La, Ce, Y) catalysts. The results show that the introduction of rare earth elements into the FeK/Al 2 O 3 catalyst obviously reduces the adsorption of H 2 , which suppresses the CH 4 formation. On the other hand, rare earth elements also promote the adsorbed CO 2 species, which leads to the enhanced liquid hydrocarbons selectivity. Finally, the tailored CO 2 /H 2 ratio of CO 2 and H 2 adsorption on the catalyst surface can influence the catalyst activity and the product selectivity evidently.