Impact of ageing on the distribution of platinum group elements and catalyst poisoning elements in automobile catalysts

The distribution of platinum group elements (PGEs) and catalyst poisoning elements (Pb, Zn, P and S) on the surface of gasoline and diesel automobile catalysts was investigated within this study. Laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) provides both the sensitivity and the spatial resolution required for the surface analysis of sectioned automobile catalysts, and scanning along channels reveals the distribution of longitudinal changes in PGE and catalyst poisoning elements. Changes in catalyst surface features were studied for fresh catalysts and after ageing of the catalyst up to 80 000 km for both types of catalysts studied. The PGEs in the gasoline catalyst were found to decrease at the front of the catalyst after ageing, whereas the diesel catalyst presented a more constant loss along the catalyst. The fraction of poisoning elements (Pb, P and Zn for the gasoline catalyst and P and Zn for the diesel catalyst) retained by the catalyst is distributed non-uniformly over the length of the catalyst. This could indicate different ageing mechanisms for gasoline and diesel catalysts. Copyright (C) 2003 John Wiley Sons, Ltd.