Density Functional Calculations and IR Reflection Absorption Spectroscopy on the Interaction of SO2 with Oxide-Supported Pd Nanoparticles

• Published in: Journal of physical chemistry. C 2010-08, Vol.114 (32), p.13813-13824
• Main Authors: Luckas, Nicola, Viñes, Francesc, Happel, Markus, Desikusumastuti, Aine, Libuda, Jörg, Görling, Andreas
• Format: Article
• Language: English
• Subjects: C: Surfaces, Interfaces, Catalysis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp105097z

A systematic study on the interaction of sulfur dioxide (SO2) on BaO-supported Pd nanoparticles has been carried out using suitable models and state-of-the-art density functional (DF) calculations. Detailed information concerning the structure and energetics of the different conformations of adsorbed SO2 is provided as a function of coverage together with calculated infrared reflection absorption spectroscopy (IRAS) spectra. SO2 may adsorb on Pd(111) in several conformations, some active, η2-SbOa and η1-Sb, and others inactive in IRAS, η3-SaOaOa. SO2 is found to attach stronger to Pd nanoparticle edges and corners, a fact intimately related to catalyst poisoning by site blocking. On Pd nanoparticles, SO2 is found to preferably adopt adsorption conformations that depend on the specific region on the nanoparticle, thus adding site specificity to vibrational recognition. Molecular beam experiments and IRAS have been performed on a single-crystal-based Pd/BaAl2x O1+3x /NiAl(110) model NO x storage and reduction catalyst and its individual components. SO x formation on the oxide components, evolution of a SO2 multilayer, and adsorption of SO2 on BaO or Pd nanoparticles is linked to DF calculations. The effect of cation intermixing in the oxide support and overlap of absorption bands on the unequivocal discrimination of signals are discussed.