Uncovering the electronic effects of zinc on the structure of Fe5C2-ZnO catalysts for CO2 hydrogenation to linear α-olefins

Abstract The performance of Fe-based catalysts has found to be remarkably improved by the addition of ZnO in the reaction of CO2 hydrogenation to linear α-olefins (LAO). The space time yield (STY) of C4-20 α-olefins for bimetallic Fe2Zn1 is 2.4 times of the Fe alone; while a C4-20 olefins selectivity of 60.7 % with an 89.3 % LAOs/olefins ratio in C4-20 alkenes at a CO2 conversion of 43.5 % was achieved as well. Using in situ X-ray photon spectroscopy (XPS), we have proved that the chemical state of Zn varied between 0 and +2 (Znδ+), accompanying by electronic donating from ZnOx to Fe. Focusing on electronic effects, we revealed the structure evolution during the induction period. The introduction of ZnO changed the ratios of FeCx/FeOx during the reaction. This study uncovered the chemical valence of Zn for CO2 to LAOs and its effects on the structure of active sites and the performance of Fe5C2-ZnO catalysts.