Catalytic control of diesel engine particulate emission: Studies on model reactions over a EuroPt-1 (Pt/SiO,) catalyst

The catalytic ox&&Ion of mtnc oxide to mtrogen &oxide m the presence of sulphur dioxide over a standard Pt/S102 catalyst (EuroPt-1) was stuched The gas-phase reactions between mtnc oxide, sulphur choxlde and oxygen were found to be ms~gmficant under the expenmental conditions concerned The Pt/S102 catalyst was observed to be very actwe m catalyzing the reactions both of NO+ 0, to NO, and of SO2 + 0, to SOS In the presence of sulphur diomde, the catalytic activity for mtnc oxide oxldatlon dropped dramatically, and m contrast, the presence of mtnc oxide promoted sulphur dioxide omdatlon There IS sqmficant mfluence of NO/NO2 on sulphur dioxide oxidation, there are m&cations from temperature-programmed desorptlon and temperature-programmed reduction (TPR) that some sort of complex species (e g [N,-S,-O,] ) ICI formed on the platmum Burface Deactmatjon of the catalyst was also observed dunng the act1vlt.y te& It 1s believed that the deactlvatlon of the catalyst wan malt& caused by the budd-up of some nitrogen and sulphur compounds on the actwe sites of the platmum catalyst Another reason for the deactwatlon could be the smtermg of platmum part&s m the reaction environment Thm has been confirmed by X-ray photoelectron spectroscopy, TPR and platmum dx+ persion measurements