Effect of solvent pretreatment on pyrolysis characteristic of high-sulfur bituminous coal.

Highlights • Oxygenated compounds could be selectively extracted by tetrahydrofuran. • Pyridine was able to selectively extract nitrogen-containing compounds. • Solvent pretreatment increased the oil yield from high-sulfur coal pyrolysis. • The relative contents of phenols from residues tar were higher than raw coal tar. • Solvent pretreatment decreased the high carbon number components in residues tar. Abstract In this study, high-sulfur bituminous coal was extracted with n-hexane, acetone, carbon disulfide, tetrahydrofuran and pyridine, respectively. The effect of solvent pretreatment on pyrolysis characteristic of high-sulfur coal was studied in a fixed-bed reactor. The heterocyclic aromatic hydrocarbons such as tetrahydrofuran and pyridine got higher extraction yields than other solvents. Oxygenated compounds could be selectively extracted by tetrahydrofuran with a maximum relative content of 9.09%, and nitrogen-containing compounds by pyridine with its content of 5.61%. However, all the solvents did not exhibit the selective extraction ability of sulfur-containing compounds. Compared with raw coal, the phenols content in pyrolysis tar from residues of pyridine and tetrahydrofuran increased significantly, and the sulfur compounds all exhibited lower content tendency. The solvent pretreatment can inhibit the radical condensation reaction effectively, and result in the reduction of high carbon number tar components, which is beneficial to the upgradation of pyrolysis tar. In addition, solvent pretreatment can be able to increase the oil yield, especially pyridine of 17.63%. [ABSTRACT FROM AUTHOR]