Catalytic Reduction of NO by CO over Rhodium Catalysts: 3. The Role of Surface Isocyanate Species

The formation, stability and reactivity of surface isocyanate species with CO, NO, and O2 has been examined over Rh/TiO2(W6+) catalysts, under conditions of NO reduction by CO, using FTIR and transient MS techniques. It has been found that W6+ doping of TiO2 results in stabilization of the Rh–NCO species and in expansion of the temperature window of N2O formation toward lower temperatures by ca. 50°C. Surface isocyanates react with NO to yield gas-phase N2O, thus providing an alternative route for the production of nitrous oxide.