Infrared study of NO2–CO reactions over supported rhodium and platinum catalysts

Abstract

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—NO 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).