Promotion of CO2 Hydrogenation in Fixed Bed Recycle Reactors

Abstract

One of the promising technologies for the utilization of CO2 is the selective synthesis of valuable chemicals by means of catalytic hydrogenation. To control and reduce emissions of CO2, various countermeasures such as capture, storage and utilization have been proposed. One of the advanced concepts to mitigate CO2 is the catalytic conversion of CO2 into valuable chemical feedstock because it can be developed to commercial process by treating the large amount of CO2 rapidly. There have been two kinds of methods for the hydrocarbon synthesis from CO2 hydrogenation: the combination of methanol and hydrocarbon synthesis (MTG process) and the direct hydrogenation synthesis by means of the modified Fischer-Tropsch (MFT) process gained special attention as a potential way for producing liquid hydrocarbons as well as Gas-to Liquids. The catalyst system for the hydrogenation of CO2 has been developed to obtain more valuable chemical feedstock such as light and higher olefins. For the direct hydrogenation of carbon dioxide to hydrocarbons over various kinds of Fe based catalysts, K, V, Cr, Mn, and Zn promoted iron catalysts have been prepared by precipitation or impregnation method. It has been reported that Fe-K catalyst gives the relatively high CO2 conversion as well as the high selectivity of light olefin. A fixed bed recycle reactor has been employed as alternative reactor configurations to increase the CO2 conversion on conducting the direct hydrogenation of CO2 as well as fixed bed series reactors. Effects of alternative reactor configurations on the CO2 conversion and hydrocarbon selectivity for the maximum yield of olefinic liquid products have been investigated.