AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP1
Vacuum TPD from Traditional and Nano-fabricated Pt/Alumina Model Catalysts

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: E. Fridell, Chalmers University, Sweden
Authors: E. Fridell, Chalmers University, Sweden
T.R. Linderoth, Chalmers University, Sweden
B. Kasemo, Chalmers University, Sweden
Correspondent: Click to Email
Temperature Programmed Desorption (TPD) is a valuable method to identify adsorbed species and investigate desorption kinetics. The usual method of performing TPD for (practical) catalyst samples is in a flow reactor under inert gas flow. The interpretatio n of the resulting spectra is hampered by complications associated with thermal gradients in the samples, re-adsorption of the desorbed species, gas phase transport under viscous flow conditions, etc.To remedy these problems, we have constructed an equip m ent allowing UHV-TPD from both model samples and "real" catalysts: The samples can be pre-treated at atmospheric pressures and high temperatures in a reactor cell mounted onto a UHV system. They are then exposed to the adsorbing gas before being transla ted to a position in front of a mass spectrometer for TPD in vacuum. The catalyst washcoat is applied directly onto, e.g., a metal foil which can be cooled or heated resistively providing precise temperature control. The equipment is intended primarily fo r catalysts made by traditional wet-deposition, but also for new "nano-fabricated" samples. To produce the latter, several methods are employed, for example we use colloidal particles adsorbed onto a surface as masks for sputtering of vacuum deposited metal/oxide films. After removing the colloidals the resulting 2D model catalysts consist, e.g., of Pt particles of uniform sizes and with controlled spatial separations on an alumina surface. In this presentation the equipment will be described and results of just initiated measurements concerning CO/oxygen adsorption on Pt/alumina catalysts will be presented.