The mechanism and activity of SnO₂for the selective catalytic reduction of NO_χ at the atmosphere of hydrocarbons and an excess of oxygen has been studied. Temperature-programmed desorption showed that only NO was desorbed from the surface of reduc...
The mechanism and activity of SnO₂for the selective catalytic reduction of NO_χ at the atmosphere of hydrocarbons and an excess of oxygen has been studied. Temperature-programmed desorption showed that only NO was desorbed from the surface of reduced-SnO₂at 150℃ and NO₂was desorbed from the surface of oxidized-SnO₂at 200, 300, and 390 ℃, respectively. For the selective catalytic reduction of NO_χ by hydrocarbons(ethylene, propylene, and propane), however, the formation of NO₂was depressed in the NO_χ reduction temperature region. The relative intensities of NO_χ reduction appeared to be the order of ethylene>propylene≫propane under the same experimental conditions. NO_χ reduction activities had a tendency to decrease with increasing oxygen concentrations in the reaction gas compositions irrespective of hydrocarbon species our experimental conditions. It was observed that the NO_χ reduction starts with the hydrocarbon combustion. From the results, it was proposed that NO₂was reduced by activated intermediate of hydrocarbons and NO₂, formed on SnO₂.