NO dissociation and N2 production in the presence of co-adsorbed S18O2 and D2 on Pt(3 3 2)

NO dissociation and subsequent N2 production in the presence of co-adsorbed S18O2 and D2 on the surface of stepped Pt(3 3 2) were studied using Fourier transform infra red reflection–absorption spectroscopy (FTIR-RAS) combined with thermal desorption spectroscopy (TDS). Reduction of NO by D (D2 is adsorbed dissociatively on Pt surfaces) proceeds to a limited extent, because this reaction is rate-controlled by NO dissociation and the supply of D atoms at the higher surface temperatures at which NO dissociation becomes significant (350 K and higher). NO–D reaction is suppressed in the presence of S18O2, depending significantly on the S18O2 coverage and the competition between the reactions NO–D and S18O2–D. When the supply of D2 is limited, e.g., 0.1 L in this study, the presence of S18O2 suppresses the NO–D reaction. With a sufficient supply of D2, e.g., 0.4 L and higher, D-atom competing reactions do not play a role any more because the reactions of both NO and S18O2 with D proceed only to a very limited extent. As such, generation of O atoms from S18O2 dissociation is the main reaction that leads to the suppression in NO dissociation and consequently, N2 production. also concluded that the presence of S18O2 does not seriously poison the active sites on the Pt surface, providing that there is a sufficient D supply to remove O atoms from both NO dissociation and S18O2 dissociation.