title: Kinetics of the sulfur oxidation on palladium: a combined in situ x-ray photoelectron spectroscopy and density-functional study.
abstract: We studied the reaction kinetics of sulfur oxidation on the Pd(100) surface by in situ high resolution x-ray photoelectron spectroscopy and ab initio density functional calculations. Isothermal oxidation experiments were performed between 400 and 500 K for small amounts (~0.02 ML) of preadsorbed sulfur, with oxygen in large excess. The main stable reaction intermediate found on the surface is SO(4), with SO(2) and SO(3) being only present in minor amounts. Density-functional calculations depict a reaction energy profile, which explains the sequential formation of SO(2), SO(3), and eventually SO(4), also highlighting that the in-plane formation of SO from S and O adatoms is the rate limiting step. From the experiments we determined the activation energy of the rate limiting step to be 85 ± 6 kJ mol(-1) by Arrhenius analysis, matching the calculated endothermicity of the SO formation.
authors.affiliation: Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Gotterbarm
authors.forename: Nicola
authors.initials: N
authors.lastname: Luckas
authors.forename: Oliver
authors.initials: O
authors.lastname: Höfert
authors.forename: Michael P A
authors.initials: MP
authors.lastname: Lorenz
authors.forename: Regine
authors.initials: R
authors.lastname: Streber
authors.forename: Christian
authors.initials: C
authors.lastname: Papp
authors.forename: Francesc
authors.initials: F
authors.lastname: Viñes
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Steinrück
authors.forename: Andreas
authors.initials: A
authors.lastname: Görling