Kinetics of Methanol Synthesis from Carbon Dioxide Hydrogenation over Copper-Zinc Oxide Catalysts

Kinetics of methanol synthesis from carbon dioxide hydrogenation is studied on two noncommercial catalysts: a copper-zinc oxide catalyst on alumina (CuZA) and a copper zinc oxide catalyst on zirconia (CuZZ). The experiments have been performed in an isothermal fixed bed reactor with a temperature range between 200 and 230 degrees C, a total pressure comprised between 50 and 80 bar, a gas hourly space velocity (GSHV) between 7800 and 23 400 h(-1) and for different hydrogen:carbon dioxide molar ratios (between 2 and 6). Unlike other works in the literature, no carbon monoxide is contained in the feed which corresponds to the conditions of some recent industrial applications, the influence of the catalyst support has been tested to improve the methanol selectivity. The experimental data were modeled using the kinetic laws and adsorption coefficients determined by Graaf et al. based on a Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism. The reactor model was based on an isothermal pseudo-homogeneous plug flow model without mass-transfer limitations. An optimization procedure was performed in order to identify new kinetic parameters. A good agreement between experimental data and modeling results was highlighted.