Formation of hydrocarbons via CO₂ hydrogenation - A thermodynamic study

The thermodynamic equilibria of the synthesis of hydrocarbons via CO₂ reduction and the Fischer-Tropsch (FT) process have been calculated minimizing the Gibbs free energy. This study reveals the theoretical optimum reaction conditions for the tandem process: CO₂ reduction followed by the FT conversion into hydrocarbons in order to (i) increase the overall CO₂ conversion (by increasing the H₂:CO₂ ratio), (ii) increase the hydrocarbon formation (increasing the H :CO ratio or addition of CO in the feed mixture) and (iii) maximize the H yield into hydrocarbons formation as opposed to water (when the reaction temperature is below 600 K or by the addition of CO in the feed mixture). In situ removal of water has no apparent effect on the overall conversion or hydrogen selectivity in the tandem system. These equilibrium calculations, in conjunction with catalysis development and reaction engineering are expected to guide the future research approach towards CO₂ utilization.