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Solid State Platinum Speciation from X-ray Absorption Spectroscopic Studies of Fresh and Road Aged Three Way and Diesel Vehicle Emission Control Catalysts

DOI: 10.1007/978-3-662-44559-4_19 DOI Help

Authors: Tim Hyde (Johnson Matthey) , Gopinathan Sankar (University College London)
Co-authored by industrial partner: Yes

Type: Book Chapter

State: Published (Approved)
Published: November 2014
Diamond Proposal Number(s): 5737 , 2081

Abstract: The localised Pt environments present in a variety of unused (fresh) and used (road aged) gasoline Three Way (TWC) and Light and Heavy Duty Diesel vehicle emission catalysts (VEC) from both European and North American origins were determined by platinum L3 and L2 edge X-ray absorption spectroscopy (XAS). Detailed laboratory based characterisation was also utilised to support the XAS studies. 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 Pt species present in multi component VEC’s. Detailed analysis of the Extended X-ray Absorption Fine Structure (EXAFS) at the Pt L3 and L2 edges was therefore extensively utilised and revealed the presence of mainly oxidic species in the fresh catalysts while metallic and bimetallic components were found to be the dominant species in the respective road aged catalysts. More importantly, supporting Cl K-edge X-ray absorption spectroscopy confirmed the absence of chlorine associated with platinum. Hence we dismiss the presence of environmentally significant quantities of chloroplatinate species in VEC’s based on weight-of-evidence arguments from chemical analysis, Cl K-edge XANES and analysis of Pt L3 and L2 edge EXAFS data.

Subject Areas: Environment, Chemistry, Energy

Instruments: B18-Core EXAFS

Other Facilities: APS SRC Wisconsin

Added On: 08/01/2015 18:26

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