Insights into catalytic oxidation mechanism of CO over Cu catalyst: Experimental and modeling study

Cu thin films have been synthesized using a chemical vapor deposition technique for catalytic kinetic study of CO oxidation. The obtained samples are morphologically uniform and homogeneous with porous textures. Structure analysis by X-ray diffraction indicated the formation of pure Cu metal. X-ray photoelectron spectroscopy exhibited the existence of Cu in a metallic state at the surface, in addition to a minor quantity of Cu¹⁺ that could be formed during the deposition process. The catalytic performance was evaluated through CO oxidation at gas hourly space velocity (GHSV) of ∼300,000 mL·g⁻¹·h⁻¹. The results showed that the Cu catalyst is very active in CO oxidation. The CO₂ effect on the CO conversion during the catalytic reaction was investigated by using different amounts of CO₂ in the inlet gas mixtures. Moreover, density functional theory (DFT) calculations were performed to determine the adsorption and reaction energies, revealing the best results on Cu hollow active sites. The surface reaction mechanism of the catalytic oxidation of CO over Cu catalyst was developed with reasonable prediction against the measured results. The simulated results revealed a good correlation with the experimental data when Langmuir-Hinshelwood (LH) mechanism is followed. CO₂ exhibits an inhibiting effect on the catalytic oxidation of CO. Accordingly, the findings revealed that combining experimental data and theoretical calculations could allow a better understanding of the catalytic reaction mechanism, which can pave the way to investigate other catalytic reactions.