Determination of the platinum, rhenium and chlorine contents of alumina-based catalysts by X-ray fluorescence spectrometry

Abstract

An X-ray fluorescence (XRF) method is described for the determination of the platinum, rhenium and chlorine contents of γ-alumina supported catalysts. Calibration graphs were linear in the range 0.02–0.80, 0.20–1.10 and 0.1–1.0% m/m for platinum, rhenium and chlorine, respectively. In order to determine the accuracy of the proposed method, the results obtained were compared with those given by ultraviolet–visible (UV/VIS) spectrophotometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), electrothermal atomic absorption spectrometry (ETAAS) and energy dispersive X-ray analysis (ED-SEM). Statistical analysis showed no significant errors at the 95% confidence interval for the chlorine content obtained by XRF, UV/VIS spectrophotometry and ED-SEM. The determination of platinum in monometallic catalysts was carried out by XRF and the results obtained were compared with those given by ICP-AES, ETAAS and UV/VIS spectrophotometry. Similarly, for bimetallic catalysts, the results obtained using XRF and UV/VIS spectrophotometry for the determination of platinum and rhenium were compared. Statistical evaluation showed that there was no significant bias between the analytical methods used.