CO adsorption and decomposition on Pd/Al₂O₃ studied by time-resolved XAFS using dispersive optics

We have studied surface structural change of supported Pd metal nanoparticles caused by CO adsorption and following temperature increase by using in situ and time-resolved X- ray absorption fine structure technique with dispersive optics. CO adsorption on Pd metal nanoparticles at room temperature shows two types of adsorption behavior and the less stable CO which brings about surface expansion of Pd metal nanoparticles is desorbed just after temperature increase. Pd carbide layer is created at around 350 °C by CO decomposition, which was clearly detected by the elongation of Pd-Pd interatomic distance and the increase of Debye-Waller factor and third cumulant. (paper)