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

The species present in a variety of fresh and road aged light-duty diesel catalysts were determined by platinum L(3) edge X-ray absorption spectroscopy (XAS). It was found that it is not sufficient 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 fine 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 find any chloroplatinate species in the systems investigated.