INFRARED STUDY OF CO ADSORPTION ON REDUCED AND OXIDIZED SILICA-SUPPORTED COPPER-CATALYSTS

FTIR spectra are reported of CO adsorbed on silica-supported copper catalysts prepared from copper(II) acetate monohydrate. Fully oxidised catalyst gave bands due to CO on CuO, isolated Cu2+ cations on silica and anion vacancy sites in CuO. The highly dispersed CuO aggregated on reduction to metal particles which gave bands due to adsorbed CO characteristic of both low-index exposed planes and stepped sites on high-index planes. Partial surface oxidation with N2O or H2O generated Cu+ adsorption sites which were slowly reduced to Cu-degrees by CO at 300 K. Surface carbonate initially formed from CO was also slowly depleted with time with the generation of CO2. The results are consistent with absorbed carbonate being an intermediate in the water-gas shift reaction of H2O and CO to H-2 and CO2.