Preparation and Performances of ZIF-67-Derived FeCo Bimetallic Catalysts for CO2 Hydrogenation to Light Olefins

A novel sodium-promoted Fe-Co/NC catalyst prepared by incipient-wet-impregnation method using ZIF-67 as a support was employed to convert CO2 to light olefins through hydrogenation reaction. Properties of the synthesized catalysts calcinated at various temperatures (from 400 to 700 degrees C) were investigated by XRD, SEM, TEM and Mossbauer spectroscopy. Characterization results showed that the support could be fully converted into carbon support above 500 degrees C, which could anchor metal particles, thus resulting in a uniform dispersion of active components. Furthermore, the Fe-Co alloy was formed during N-2 calcination, and was converted into active components, such as Fe3O4, Fe5C2, and Co2C during the reaction. The reaction result indicated that FeCo/NC-600 catalyst exhibited the highest selectivity of light olefins (C-2= - C-4=, 27%) and CO2 conversion could reach around 37% when this catalyst pyrolyzed at 600 degrees C in N-2. The highest selectivity for light olefins may be related to the combination of suitable particle size and sufficient active sites of iron carbide.