The selective catalytic reduction of NO by propylene over Pt supported on dealuminated Y zeolite

The reactivity of Pt supported on a stable dealuminated Y zeolite (Pt/DeY) for the Selective Catalytic Reduction of NO by hydrocarbons (HC-SCR) has been investigated with a monolith sample. The results show that the Pt/DeY catalyst has substantial activity for this reaction at temperatures between 200 and 300 degrees C. Furthermore, the presence of water and sulfur dioxide, at levels similar to the ones expected in vehicle exhaust gas, does not significantly affect the performance of the catalyst, which makes it a promising candidate for further commercial development. In the same temperature range, oxygen promotes the rate of the NO reduction by assisting in the activation of the hydrocarbon. NO2 is also formed under the conditions studied as a result of the oxidation of NO. In the presence of the hydrocarbon however, it is preferentially reacting with the hydrocarbon, and reduces primarily back to NO. High selectivities were observed toward the formation of N2O which is a primary product of the hydrocarbon-SCR reaction. (C) 1997 Elsevier Science B.V.