A Study of Organic Sulfur Analysis in Coal Using Non-destructive Techniques

The Xinyu coal under study was received from Shanxi province, China. Raw coal and its extracted coals were investigated for distribution of various forms of organic sulfur and effects of solvent polarity on extraction organic sulfur from the coal during continuous extraction by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy combined with chemical analysis. The distribution and primary existent forms of organic sulfur in Xinyu coal is mercaptan/thioether (44.9%), thiophene (24.4%), sulfones sulfur (30.7%), and a small amount of sulfide. Carbon disulfide (CS2), dichloromethane (CH2Cl2), and propylalcohol (CH3CH2CH2OH) was applied to explore the applicability for the removal of sulfur compounds. The experimental results show that the CH3CH2CH2OH removal of mercaptan/ thioether ability (51.1% -> 35.8%) is markedly higher than others. CS2 has a higher selectivity of removing thiophene (24.4% -> 19.6%) and sulfones sulfur (30.7% -> 26.6%). CH2Cl2 has the extraction abilities for the sulfones and mercaptan, but the effect is not obvious. The results have guiding significance for the selection of the appropriate extractants using the gas chromatography technique coupled extraction to identify organic sulfur compounds species. Continuous extraction provides a way of non-destructive depth profilings with X-ray photoelectron spectroscopy, which can improve the reliability and comprehensiveness of the X-ray photoelectron spectroscopy analysis.