INFRARED STUDY OF CO ADSORPTION ON PT-RH/AL2O3 CATALYSTS

FTIR spectra are reported of CO adsorbed at 303-573 K on Pt/Al2O3, Rh/Al2O3 and Pt-Rh/Al2O3. Catalysts containing Rh were precalcined at either 673 K or 873 K before reduction in hydrogen and exposure to CO. The intensities of infrared bands due to gem-dicarbonyl and linear carbonyl species were a function of both the precalcination temperature and the temperature of contact with CO. Bridged carbonyl was also formed on both Rh and Pt. The results are discussed in terms of effects involving interactions between metal and support, interactions between Pt and Rh, structure after high-temperature calcination and structural reorganisation during contact with CO at high temperature.