Hydrocarbon and ammonia chemistry on noble metal surfaces, catalysis on a molecular scale

The work described in this thesis concerns hydrocarbon and ammonia oxidation on single crystal surfaces of Pt, Rh and Ir. In Chapter3 the oxidation of n-butane and propene on a stepped Pt surface is discussed. In Chapter 4 benzene decomposition and oxidation on Ir(111) is discussed, and in Chapter 5 the adsorption of methane and oxygen on Rh(100) is studied. The oxidation of ammonia was studied on two different surfaces, i.e. Pt(410) and Ir(110). It was found that ammonia dissociates on Ir(110), but not on Pt(410). Radiation can induce NH3 dissociation, and the NHx chemistry could be studied in this way, even on Pt(410). The presence of Oad enhances NH3 dissociation on Pt surfaces, The reaction between NH3 and Oad already occurs around 150 K. NO formation was also found on this surface, already at low temperature. On Ir(110) the formation of NO was also found, but only at higher temperatures. A model is proposed in which the different selectivity found for Ir and Pt catalysts during ammonia oxidation is explained.LEI Universiteit Leidenthe research was financially supported by the Technology Foundation STW, applied science division of NWO and the technology programme of the Ministry of Economic Affairs, under project number UPC-5037Surfca