Promoted iron catalysts were tested for their Fischer–Tropsch (FT) activity to convert CO2/H2, CO/H2 and their mixtures to higher hydrocarbons (220 °C–300 °C, 20 bar, H2/(CO2+CO) = 3). The results show that iron-sintered catalysts are able to convert CO2 at moderate conditions to higher hydrocarbons (HCs) with a still low methane selectivity. Kinetic studies showed that CO2 is not directly converted to higher HCs but at first reduced by H2 to CO followed by FTS of CO. For a pure CO2/H2 mixture and a CO2 conversion of 10% (220 °C), the FeCuZnK catalyst has the highest C2+ selectivity (57 wtC%), the lowest methane selectivity (10 wtC%), and 32% of CO2 are converted to the intermediate CO. At 300 °C and a higher CO2 conversion of 47%, the C2+ selectivity is even 73 wtC% (methane 19 wtC%, methanol 4 wtC%, and 4 wtC% CO).
Mai et al. (Wed,) studied this question.