An infrared spectroscopic study of the adsorption of carbon monoxide on silica-supported copper oxide

Abstract

Adsorption of carbon monoxide at room temperature (0.1–50 Torr) on silica-supported copper oxide was studied by infrared spectroscopy. Catalysts were prepared by deposition-precipitation or impregnation. After calcination two types of adsorbed CO were identified showing absorption bands at 2136 ± 3 and 2204 ± 1 cm−1, which are ascribed to CO adsorbed on copper(II) oxide and on isolated copper(II) ions in the silica surface, respectively. Reduction and reoxidation removed the band at 2204 cm−1 with all samples and raised the intensity of the 2136-cm−1 band with the precipitated catalysts but not with the impregnation catalyst. Evidence is brought forward that the isolated copper ions are mobilized during reduction and generate new copper (oxide) surface. The change in background transmission of the samples could be used to obtain further information about the interaction of O2 and CO with copper oxide.