Sulphur Analysis in Crude Oil and High-Sulphur Fuels

Rigaku Corporation (USA) has published a new application report demonstrating the capabilities of the Rigaku ZSX Primus II, a tube below sequential wavelength dispersive X-ray fluorescence (WDXRF) spectrometer optimised for routine analysis as performed by today’s petroleum laboratories. Rigaku Application Note XRF 5016 demonstrates quantitative analysis of high concentration sulphur in crude oil, high-sulphur diesel fuel and residual fuel oil according to ASTM D2622-10.The report includes complete information about sample preparation, method calibration and repeatability.

Crude oil is a raw material for petroleum products and typically contains sulphur in varying concentrations up to 5 wt%. Sulphur compounds in petroleum can produce various harmful effects including air pollution, metal corrosion and catalyst degradation. Sulphur concentration in crude oil and high-sulphur fuels is therefore monitored or controlled in refinery and production processes within the petroleum industry.

X-ray fluorescence (XRF) spectrometry is an effective tool for quantitative analysis of sulphur in crude oil and high-sulphur fuels including bunker fuel, due in part to its simple sample preparation requirements. In XRF analysis of oils, samples are simply poured into liquid cells; concentration of total sulphur is then obtained without complicated treatments such as digestion or dilution.

As described in the report, measurements were performed on the ZSX Primus II equipped with a 3 kW X-ray tube operating at 30 kV, 80 mA using a germanium (Ge) analysing crystal and the S4 slit, as included in the standard configuration. Standards comprised of crude oil, “Number 2 diesel fuel” and residual oil were used for calibration. Counting times were 20 seconds for peak and 10 seconds for background. Repeatability tests were carried out using a representative sample for each material.

This application note demonstrates that high concentration sulphur in crude oil and petroleum based fuels can be routinely analysed with high precision by WDXRF and that the performance of the ZSX Primus II meets the requirement of ASTM D2622-10.