Co oxidation by silver cobalt composite oxide

We report the results of our study of the catalytic oxidation of carbon mon oxide by a composite oxide catalyst containing one to one molar ratio of si lver and cobalt. XRD, XPS and TGA studies indicate that the composite oxide is not a physical mixture of silver and cobalt oxides and that silver is s tabilized in an oxide in the presence of cobalt at temperatures as high as 800 degrees C. Low temperature activity of the composite oxide compares ver y favorably to the previously studied low temperature CO oxidation catalyst s. CO oxidation activity of the catalyst is reversibly degraded below 100 d egrees C by the presence of excess CO2 and water vapor in the feed. IR spec troscopy shows that CO2 and water vapor adsorb weakly on the catalyst surfa ce and thus may physically block access to CO and oxygen. IR spectra also s howed that under reaction conditions CO does not chemisorb and at 50 degree s C or higher there are no carbonate species on the catalyst. (C) 1999 Else vier Science B.V. All rights reserved.