Breaking the activity–selectivity trade-off of CO2 hydrogenation to light olefins

Catalytic hydrogenation of CO2 to value-added fuels and chemicals is of great importance to carbon neutrality but suffers from an activity–selectivity trade-off, leading to limited catalytic performance. Herein, the ZnFeAlO4 + SAPO-34 composite catalyst was designed, which can simultaneously achieve a CO2 conversion of 42%, a CO selectivity of 50%, and a C2–C4= selectivity of 83%, resulting in a C2–C4= yield of almost 18%. This superior catalytic performance was found to be from the presence of unconventional electron-deficient tetrahedral Fe sites and electron-enriched octahedral Zn sites in the ZnFeAlO4 spinel, which were active for the CO2 deoxygenation to CO via the reverse water gas shift reaction, and CO hydrogenation to CH3OH, respectively, leading to a route for CO2 hydrogenation to C2–C4=, where the kinetics of CO2 activation can be improved, the mass transfer of CO hydrogenation can be minimized, and the C2–C4= selectivity can be enhanced via modifying the acid density of SAPO-34. Moreover, the spinel structure of ZnFeAlO4 possessed a strong ability to stabilize the active Fe and Zn sites even at elevated temperatures, resulting in long-term stability of over 450 h for this process, exhibiting great potential for large-scale applications.