Chemical Structures of Polar Fraction in Wandoan Coal-derived Heavy Oil

Abstract

Hydrocracking of polar fraction (Po) isolated from Wandoan coal-derived heavy oil was carried out over a Ni-Mo/Al₂O₃ catalyst at 375°C to determine their chemical structures.
The nonpolar product (Po/NP) was separated into seven compound-type fractions by HPLC equipped with a semipreparative μBondapak-NH₂ column. Each compound-type fraction was analyz-ed by field ionization mass spectrometry (FIMS), but it was difficult to determine the skeltal structures, especially in compound-type fractions with large aromatic rings, because of many naphthenic rings. Therefore, Po/NP was dehydrogenated over a Pt/Al₂O₃ at 325°C to eliminate naphthenic rings. The dehydrogenated product (Po/NP/DH) was separated into seven compound-type fractions which were analyzed by FIMS. The skeltal structures of Po/NP/DH were shown to be polycondensed aromatic rings with molecular weights represented by 178+50n, 154+50n, 202+50n (n=0, 1, 2, 3, 4).
The skeltal structures of the original polar fraction (Po) were presumed from those of Po/NP and the removal mechanism of hetero atoms in some model compounds.