INFRARED STUDY OF NO2-CO REACTIONS OVER SUPPORTED RHODIUM AND PLATINUM CATALYSTS

Infrared spectra are reported on Rh/Al2O3 exposed to nitrogen dioxide and carbon monoxide at ambient or elevated temperatures. Additional experiments involving Rh/SiO2, Rh/TiO2 and Pt/Al2O3 helped in the assignment of observed infrared bands. Dissociative adsorption of nitrogen dioxide led to RhNO and RhO or RhNO and RhNO3 species at adjacent rhodium sites and to surface Rh-N = O in a bent configuration. Surface species resulting from nitrogen dioxide and carbon monoxide coadsorption or reaction included Rh(CO)(NO), Rh(CO)(O) and Rh(CO)(NO3).