Chemical Analysis of Used Three-Way Catalysts by Total Reflection X-ray Fluorescence

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Abstract
The methodology developed for evaluating, by total reflection X-ray fluorescence, the main elements in used three-way catalysts for cars after more than 59 000 km is described. The analytical method does not require chemical manipulation of the samples, is quick (30 min for sample preparation and 10 min for analysis), precise (between 1% and 10% of variation coefficient), and simple. The two catalytic monoliths contained in the cartridge of a car with more than 59 000 km have been analyzed. The mass relationships between the detected elements and Si, a component of the cordierite ceramic substrate, have been used to follow the axial and radial profiles of the elements. Information concerning the loss of active elements and the retention of contaminating elements as a consequence of the working conditions was attained by comparison between the results obtained for the used catalyst (59 000 km) with those of a fresh catalyst (0 km). The interface effect between the first and the second catalytic bricks was also studied.