CO2 Hydrogenation to Methanol Over Cu/ZnO/Al2O3 Catalyst: Kinetic Modeling Based on Either Single- or Dual-Active Site Mechanism

CO2 hydrogenation to CH3OH via heterogeneous catalysis is one of the most promising and available approaches for mitigation of anthropogenic CO2 issues. In this work, thermodynamic equilibria of CO2 to methanol were compared with experimental results at given conditions using a commercial Cu/ZnO/Al2O3 catalyst for CO hydrogenation to methanol. It was found that, the high pressure, low temperature, and high H2/CO2 ratio are favorable to methanol synthesis from CO2. Furthermore, the kinetic data were measured with an isothermal integral reactor under temperature between 160 and 240 °C, lower than that for CO hydrogenation to methanol reaction. Based on the single-active site and dual-active site LH mechanisms, both kinetic models can achieve full illustration of the influence of the operating conditions and the mechanisms. According to comparative analysis of the error variances of model correlations and the adsorbate coverages on the active sites, the dual-site mechanism identified to be superior to the single-site one for methanol synthesis from CO2 feedstock. Overall, this paper provides fundamental understanding of the thermodynamic and kinetic aspects of a central route for CO2 Valorisation.