Analysis and Examination of Poisons on Catalysts

The characterization of fresh and used automotive catalysts, which includes the examination of poisons accumulated in the catalysts, uses a variety of modem analytical techniques. The two principal tools, besides conventional chemical methods, are atomic absorption and, most important, X-ray fluorescence (XRF). The latter technique has been refined and adapted for the analysis of automotive catalysts to permit rapid and accurate determination of all constituents, including the inadvertent contaminants. An example of a simultaneous XRF analysis of 

X-Ray Fluorescence Analysis of 15 Components in a Catalyst Calibration Standard 

0 From Mencik et al. 12). (Reprinted with permission of Plenum Press.) 

15 elements found in an automotive catalyst is shown in Table II. The analysis was carried out by a multiple regression procedure with a minicomputer (75) to handle the large amount of data produced by the XRF spectrometer during the analysis. 

Complete characterization of poisoned catalysts, of course, requires much more than chemical analysis. For example, the interaction of poisons with catalyst constituents and with each other has been studied by X-ray diffraction and by electron microscopy, the morphology of the poison deposits by optical methods, the distribution within the catalyst pellets and washcoats by the microprobe, and the distribution of poison on the surface of the active metals by Auger spectroscopy. 

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