Organic sulfur compositions and distributions of tars from the pyrolysis of solvent pretreatment vitrinite of high sulfur coal

The low temperature solvent pretreated experiments of vitrinite sorted out from Permo-carboniferous high organic sulfur fine coal were performed to research the effects of solvent pretreatment on the characteristics of pyrolysis products and the composition and distribution of sulfur in the produced coal tar. Six solvents containing hot water, ethanol solution, 1, 2-propanediol solution, KOH solution, KOH-ethanol solution and KOH-1, 2-propanediol solution were employed. The results show that the solvent pretreatment method has little influence on the organic sulfur content of coal, but it results in the increase of coal tar yield and a great variation of volatiles during the pyrolysis of pretreated coals. Six types of thiophenes, containing benzothiophene, dibenzothiophene, naphthothiophene, benzo [b]naphthothiophene, dinaphthothiophene and phenanthro[9,10-b] thiophene, were detected in coal tars. The pretreatments of hot water, ethanol solution and alkaline ethanol solution show the ring opening to large aromatic structures in coal. The generation of benzothiophene, dinaphthothiophene and phenanthro[9,10-b]thiophene may be due to the ring opening effect.