X-Ray Absorption Spectroscopic Studies of Platinum Speciation in Fresh and Road Aged Light-Duty Diesel Vehicle Emission Control Catalysts

Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK; and Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH, UK *Email: g.sankar@ucl.ac.uk The species present in a variety of fresh and road aged light-duty diesel catalysts were determined by platinum L3 edge X-ray absorption spectroscopy (XAS). It was found that it is not suffi cient to use the analysis of X-ray absorption near edge structure (XANES) alone to determine the nature of species present in fresh and road aged catalysts. Detailed analysis of the extended X-ray absorption fi ne structure (EXAFS) revealed the presence of a mixture of oxidic and metallic species in the fresh catalysts. Metallic components were predominantly found in the road aged catalysts. The present study did not fi nd any chloroplatinate species in the systems investigated.