Automotive catalytic converters lose activity whilst in service. The degree of deactivation depends upon a number of factors including contamination by residues of additives or trace elements in fuel and/or engine oil, which generally reduces the surface area of the catalyst. In this initial investigation, PIXE was used to map contaminant deposition at three points along each of the central longitudinal axis and a parallel axis located closer to the side of a single monolith. This monolith was selected because it was physically undamaged and exhibited low surface area (<2 m2 g-1) at the front and reasonable surface area (>10 m2 g-1) towards the rear. A total of 20 elements were identified. The contaminants P, K, Ca, Zn and Pb were deposited in greater concentration towards the front of the monolith on both axes. Si may also be a contaminant; it is unexpectedly deposited more uniformly along the central axis than along the parallel side axis where it appears to decrease linearly from front to rear. Degraded precision was obtained for Al and Si in samples that were heavily contaminated.
|Number of pages||6|
|Journal||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|Publication status||Published - Apr 1996|