Hydrogenation of carbon dioxide over alumina supported Fe-K catalysts

The hydrogenation of CO2 has been studied over Fe/alumina and Fe-K/alumina catalysts. The addition of potassium increases the chemisorption ability of CO2 but decreases that of Hz. The catalytic activity test at high pressure (20 atm) reveals that remarkably high activity and selectivity toward light olefins and C-2+ hydrocarbons can be achieved with Fe-K/alumina catalysts containing high concentration of K (K/Fe molar ratio = 0.5, 1.0). In the reaction at atmospheric pressure, the highly K-promoted catalysts give much higher CO formation rate than the unpromoted catalyst. It is deduced that the remarkable catalytic properties in the presence of K are attributable to the increase in the ability of CO2 chemisorption and the enhanced activity for CO formation, which is the preceding step of C-2+ hydrocarbon formation.