Determination of platinum, palladium and rhodium in vehicle-used ternary catalyst by portable X-ray fluorescence spectrometry
XU Wen-song1, 2, YOU Jing-lin1, WANG Xiao-huan*2
1.Shanghai University, Material Science &Engineering Institute, Shanghai 200072, China;2.Oxford InstrumentShanghai Co., Ltd., IA Department, Shanghai 201102, China
Abstract:After the sample was prepared by powder sample cup method, a method for the real-time, on-line and quantitative analysis of precious metals including rhodium (Rh), palladium (Pd) and platinum (Pt) in vehicle-used ternary catalyst was established by portable X-ray fluorescence spectrometry. The effects of six different types of sample films commonly used in laboratory on the determination results were compared. The light transmittance tests showed that all the sample films reached the light transmission rate of 100% when the X-ray’s energy was higher than 5.4 keV (elements after 24Cr), but the thinner the sample films, the higher the analytical sensitivity was. Thus, Ploy-4 sample film with the thickness of 4.0 μm was selected. The interfering overlaps and correction among element spectral lines were investigated, and matrix correction was carried out by background scanning combined with α empirical coefficient method to avoid the impact of the matrix changes on the accuracy of the analytical results. The calculation method of the detection limit for X-ray fluorescence spectrometry was explored, and the detection limits for rhodium, palladium and platinum were 14.04 μg/g, 18.17 μg/g and 8.40 μg/g, respectively, which was obtained as the standard deviation of the results for multiple determination of the sample with platinum, palladium and rhodium in smaller contents. Precision test was conducted with vehicle-uesd ternary catalyst powder samples, and the relative standard deviation (RSD) was restricted within 4.0%. This method was used to determination of eight vehicle-used ternary catalyst actual samples, the results were consistent with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES), the relative error were less than 10.0%, so the method could meet the recycle requirements for vehicle-used ternary catalyst.