title: SO2adsorption on silica supported iridium.
abstract: The interaction of SO2with Ir/SiO2was studied by simultaneous in situ diffuse reflectance infrared Fourier transform spectroscopy and mass spectrometry, exposing the sample to different SO2concentrations ranging from 10 to 50 ppm in the temperature interval 200-400 °C. Evidences of adsorption of sulfur species in both absence and presence of oxygen are found. For a pre-reduced sample in the absence of oxygen, SO2disproportionates such that the iridium surface is rapidly saturated with adsorbed S while minor amounts of formed SO3may adsorb on SiO2. Adding oxygen to the feed leads to the oxidation of sulfide species that either (i) desorb as SO2and/or SO3, (ii) remain at metal sites in the form of adsorbed SO2, or (iii) spillover to the oxide support and form sulfates (SO42-). Notably, significant formation of sulfates on silica is possible only in the presence of both SO2and O2, suggesting that SO2oxidation to SO3is a necessary first step in the mechanism of formation of sulfates on silica. During the formation of sulfates, a concomitant removal/rearrangement of surface silanol groups is observed. Finally, the interaction of SO2with Ir/SiO2depends primarily on the temperature and type of gas components but only to a minor extent on the inlet SO2concentration.
authors.affiliation: Department of Chemistry and Chemical Engineering and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
authors.forename: Djamela
authors.initials: D
authors.lastname: Bounechada
authors.affiliation: Department of Chemistry and Chemical Engineering and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
authors.forename: David P
authors.identifier: 0000000326651453
authors.initials: DP
authors.lastname: Anderson
authors.affiliation: Department of Chemistry and Chemical Engineering and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Skoglundh
authors.affiliation: Department of Chemistry and Chemical Engineering and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
authors.forename: Per-Anders
authors.identifier: 0000000163187966
authors.initials: PA
authors.lastname: Carlsson