In situ FT-IR study of copper-chromium oxide catalysts in CO oxidation

Article abstract of DOI:10.1016/0304-5102(92)80237-B

CO adsorption and CO oxidation by O₂ were studied over alumina-supported copper and copper-chromium oxide from 300 to 673 K. After evacuation at room temperature, Cu⁺-CO and carbonate-like complexes were observed on copper-containing catalysts upon CO adsorption. Both the copper and the chromium oxide species were easier to reduce on CuO Cr₂O₃/Al₂O₃ compared with CuO/Al₂O₃ and Cr₂O₃/Al₂O₃ owing to the presence of a mixed oxidic phase. CO can react directly from the gas phase with oxygen at the surface under formation of a CO₂ surface species as a reaction intermediate. This indicates an Eley-Rideal mechanism. CO₂ adsorption results in bands similar to those observed upon CO and upon CO and O₂ admission. CO₂ inhibits the CO oxidation reaction in two ways - via the more weakly, reversibly bound CO₂ and via the more strongly, irreversibly held carbonates.