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 O-2 has been examined over Rh/TiO2(W6+) catalysts, under condit ions 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 s pecies and in expansion of the temperature window of N2O formation toward l ower temperatures by ca. 50 degrees C. Surface isocyanates react with NO to yield gasphase N2O, thus providing an alternative route for the production of nitrous oxide. (C) 2000 Academic Press.