The process of organic matter burial and coalification, which restrict the distribution of organic sulfur in macromolecular structure of coal, leads to different occurrence of organic sulfur. The genetic relationship between the compose of organic sulfur and coalification have been studied by using X-ray Photoelectron Spectroscopy (XPS) in Southern Guizhou coal of Permian Longtan Formation and the calculation method of bond dissociation enthalpies (BDE) of three type sulfur functional group. The result of BDE reflects that ph-S-ph (247.89kJ/mol) < ph-SH (312.94 KJ/mol) < thiophene (332.93 KJ/mol). Therefore, the thermal stability of C-S bond in sulfur-containing functional groups is thioether < mercaptan < thiophene. The XPS spectrum of the coal samples in the middle and lower layers of Longtan Formation shows that the sulfur-containing organic functional groups are mainly mercaptan sulfur, differed from Marine coal HNP sample that is mainly in thiophene. With the increase of 0.3% Ro, mercaptan increased as well. Combined with the calculate of BDE, it is speculated that bridge bond (thioether) would crack into edge bond (mercaptan), but sulfur atoms of mercaptan could close to carbon and generate C-S Π bond (thiophene), or C-S bond dissociate, contributing to sulfur containing gas.

Organic sulfur , Coalification, BDE, Longtan Formation