A robust kinetic modeling of CO2 hydrogenation to methanol over an industrial copper-zinc oxide catalyst based on a single-active site mechanism

The catalytic hydrogenation of carbon dioxide to methanol represents a promising avenue for global warming alleviation. In the present study, the kinetics of high-pressure methanol synthesis from CO2 hydrogenation over a Cu/ZnO/Al(2)O(3 )catalyst were investigated. This study focused on developing a robust kinetic model based on a competitive single-active site Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism and utilizing the model to investigate the influence of various operating conditions on the catalytic fixed -bed reactor performance, including temperature, total reactor pressure, feed composition, and gas hourly space velocity (GHSV). The model satisfied the physicochemical constraints to be thermodynamically consistent, and its prediction results of molar flow rates showed a satisfactory correlation of 99% with experimental data available in the literature. The kinetic modeling results revealed that the overall rate of methanol synthesis is inhibited by the surface concentration of formate. Furthermore, adsorbed H2 and CO2 were identified as the most abundant intermediates, constituting approximately 80% and 10% of surface coverage throughout the catalytic bed, respectively. According to the present model, relatively mild temperature and pressure ranges of 200-220degree celsius and 80-100 bar were deemed the optimal operating conditions for enhanced catalytic activity and selectivity towards methanol. These findings not only provide valuable insights into the chemical kinetics of CO2 hydrogenation to methanol but also enable reliable catalytic reactor designs.