The evolution characteristics of organic sulfur structure in various Chinese high organic sulfur coals

Understanding the organic sulfur structure and its evolution characteristics is crucial to the desulfurization of coal, as they are the dominant factors determining the removal of organic sulfur from coal. To learn the organic sulfur structure characteristics, a series of high-organic-sulfur coals from China with different ranks were studied by coal petrology, structural chemistry, and organic geochemistry theory in this paper. Coal petrological analysis shows some of the high-organic-sulfur coals with high TPI values and low GI values indicating that they have experienced unusual conditions when the coal was forming. Through the FTIR analysis, the organic sulfur structural parameters shows the relative abundance of aliphatic sulfur (thiol, thioether and sulfone) in these coals decreased with the increasing coal rank and the relative abundance of aromatic sulfur in coal generally showed an increasing trend with increasing coalification, divided into three different evolutionary stages (0.37%-1.40%, 1.40%-1.99% and 1.99%-3.93% of R-m). Comprehensive analysis shows that EID and TPI had a significant correlation with the organic sulfur structural parameters, which means regardless of the coal rank the impact of the environment on the structure of organic sulfur is independent. These results give a new insight into organic sulfur characteristics in coal and its evolution characteristics with coal rank, which are potentially useful for the efficient remove the organic sulfur from coal.