Analysis of Precious Metals in Automobile Catalytic Converters with the Thermo Scientic NITON

®

XL3t Series

NITON XL3 Series Handheld Analysers – Simply Superior XRF

Application

determination (R
2 ) for each element is provided in Figures 1 through 3. The R The analysis of scrap automotive catalytic converters to determine precious metal content – platinum (Pt), palladium (Pd), and rhodium (Rh) – is important to the recycling industry for assessing accurate scrap values. In 2005, we developed a special program for the analysis of automobile catalytic converters, which was based on a dual isotope Thermo Scientic NITON Edxrf using Cd 109 and Am 241 as the x-ray sources. This application study reports on data obtained with our latest instrument, the Thermo Scientic XL3t Series analyzer, on samples provided by a scrap recycling customer. With the introduction of the high-powered XL3t, it is now possible to use an x-ray tube source instrument for this analysis. Cerium (Ce) and lanthanum (La) are commonly present in the ceramic substrate of the converters and must be included in the analysis to obtain accurate results for the precious metals. The XL3’s 50kV x-ray tube source provides sufcient excitation of the 34.72 keV Ce and 33.44 keV La lines, so that accurate analysis no longer has to depend on radioisotope-based sources.
2 value is a measure of how closely the data sets correlate with each other, where a perfect correlation would have an R
2 of 1. Pd, % labPd, % readRPD 0.325 0.319 1.80.099 0.101 2.00.033 0.031 6.10.347 0.349 0.60.104 0.105 1.00.323 0.326 0.90.019 0.020 5.3 Rh, % labRh, % readRPD 0.071 0.069 2.80.023 0.024 4.30.016 0.016 0.00.072 0.072 0.00.022 0.022 0.00.067 0.069 3.00.005 0.004 20.0

Method

For the purpose of direct comparison with laboratory data, seven lab-analyzed samples were measured using an XL3t in the Industrial Bulk Mode. The samples were pulverized and loaded into standard 32 mm XRF sample cups. A total measurement time of 120 seconds was used, 60 seconds with the main lter and 60 seconds with the high lter. Pt, % labPt, % readRPD 0.125 0.121 3.20.043 0.042 2.30.020 0.017 15.00.119 0.123 3.40.039 0.038 2.60.101 0.100 1.00.014 0.019 35.7

Results

Results from the external laboratory were compared against the results from the NITON XL3t Series analyzer. The relative percent dfference (RPD) between the laboratory readings and the XRF readings for the Pd, Rh, and Pt is shown in Table 1. The coefcient of
Table 1: Comparison of lab results and NITON XRF analyzer results