Comparative Study of Carbon Dioxide Hydrogenation to Methanol and DME

No Persian Abstract

A comparative study on the hydrogenation of carbon dioxide to methanol and dimethyl ether (DME) was performed using thermodynamic equilibrium and experimental data. The approach to equilibrium analysis of experimental data was used to compare the respective reaction rates. At lower reaction temperatures (<250°C), methanol and DME are the thermodynamically favored products while at higher temperatures CO is favored. The higher equilibrium selectivity of DME compared to methanol implies the higher potential of the former in CO2 chemical fixation. The approach to equilibrium results showed that over Cu-ZnO-ZrO2/H-ZSM5 bifunctional catalysts, the competitive reverse water gas shift (RWGS) reaction is much faster than CO2 hydrogenation to methanol and DME and equilibrates first, followed by methanol synthesis and then by DME synthesis reactions. As the catalyst exhibits a high activity in the competitive RWGS reaction, for maximizing oxygenates yield, research efforts should be directed towards optimizing both catalyst formulation and operating conditions.