Roles of Carbon Dioxide in Methanol Synthesis

The roles played by carbon dioxide in the chemistry of methanol synthesis over CuO/ZnO/A₁₂O₃ catalysts have been experimentally investigated. It was concluded based on reaction rate measurements and thermodynamic considerations, that the two reactions that best describe the chemical system of methanol synthesis are the CO₂-hydrogenation and water-gas shift reactions. It was also found experimentally that the presence of CO₂ is vital for maintaining the catalytic activity. The significance of the study is enhanced by the fact that this was the first such investigation of the global chemistry of methanol synthesis to be based on the novel liquid phase process. It was also observed that the rates of methanol synthesis attained a maximum when the concentration of carbon dioxide in the reactor feed was controlled at a certain optimal value. The optimal CO₂ content was found to be a function of the operating temperature and syngas composition. The experimental data are especially important because the apparatus and the operating conditions have been well-defined and carefully chosen to closely simulate industrial reactors