CO2- and CO-Conversion to Methanol over promoted CuO/ZnO-based infiltration composite catalyst spheres — Characterization, experimentals and comparative reaction kinetics

Zirconia (ZrO 2 )-, Ceria (CeO 2 )-, and Calcium (CaO) -promoted Copper oxide (CuO) Zinc oxide (ZnO) catalysts supported on γ -alumina spheres are synthesized via incipient wetness impregnation (IWI) and characterized using transmission electron microscopy (TEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and CO 2 /H 2 -TPD. Catalytic performance is evaluated for carbon oxide hydrogenation to methanol (MeOH) in mixed carbon oxide synthesis gas, examining both CO and CO 2 -conversion pathways and MeOH space–time yields (STY). Temperature- and pressure-dependent reaction equilibria for MeOH formation from CO and CO 2 , as well as the reverse water-gas shift reaction (RWGS) are investigated to demonstrate promoter effects on surface reaction mechanisms and conversion efficiency towards MeOH and H 2 O. Reaction kinetics are optimized using a previously formulated re-parametrized two-site Langmuir–Hinshelwood–Hougen–Watson (LHHW) model for each catalyst system, providing comparative kinetic parameters for the binary, ternary, quaternary, and quinary catalyst formulations. The kinetic models demonstrate good numerical agreement with experimental data for both the promoted catalysts. Although CO-rich streams produce the highest MeOH production rates in all samples, the promotion through ZrO 2 and CeO 2 significantly improved both CO and CO 2 conversion (X C ) compared to the binary CuO/ZnO catalyst formulation.