Carbon Dioxide Reduction with Hydrogen on Fe, Co Supported Alumina and Carbon Catalysts under Supercritical Conditions.

Reduction of CO with hydrogen into CO was studied for the first time on alumina-supported Co and Fe catalysts under supercritical conditions with the goal to produce either CO or CH as the target products. The extremely high selectivity towards methanation close to 100% was found for the Co/AlO catalyst, whereas the Fe/AlO system demonstrates a predominance of hydrogenation to CO with noticeable formation of ethane (up to 15%). The space-time yield can be increased by an order of magnitude by using the supercritical conditions as compared to the gas-phase reactions. Differences in the crystallographic phase features of Fe-containing catalysts cause the reverse water gas shift reaction to form carbon monoxide, whereas the reduced iron phases initiate the Fischer-Tropsch reaction to produce a mixture of hydrocarbons. Direct methanation occurs selectively on Co catalysts. No methanol formation was observed on the studied Fe- and Co-containing catalysts.