Direct and simultaneous determination of metal impurities in catalysts based on platinum group elements

Abstract

Production of new catalysts requires effective analytical quality control. The study of trace element composition of heterogeneous catalysts, based on C+PdO, using atomic emission spectrometry (AES) was carried out. A new method for the direct solid-state analysis by means of AES with direct current arc discharge was developed. On the basis of the qualitative analysis of elements, Al, Fe, Ni, Si and Ti have been identified, and for these elements, the quantitative method of determination has been developed. Optimization of excitation parameters and validation of the analytical method are presented. Calibration samples of the following composition were prepared: graphite powder (as a matrix), 3% of PdO and increasing contents of determined element oxides (spectrally pure). Calibrations were calculated by means of the least squares method. Working range for element impurities was from 1% to 0.0003%, and the limits of quantification — LOQ, (10-σ criterion) varied in the range from 0.002% (Ti) to 0.0038% (Si). For the control of active component, palladium was calibrated (working range — 0.01%–10.00%; LOQ −0.027%). The developed method can be used, also, for the elemental determinations of the other carbon based catalysts with the different active components (of platinum group elements).