Fuel Science & Technology International, Vol.12, No.11, 1509-1538, 1994
DEASPHALTING AND CHARACTERIZATION OF A SYNCRUDE OBTAINED BY DIRECT LIQUEFACTION OF A SPANISH SUBBITUMINOUS COAL
A syncrude obtained by direct liquefaction of a Spanish subbituminous coal was deasphalted as a previous step of upgrading to get a better feedstock for further processing. Deasphalting was carried out by ultrasonic extraction with n-hexane. Raw and deasphalted coal syncrudes have been fractionated into six fractions by an extrographic procedure that utilizes six eluents of increasing polarity. Each fraction has been analyzed by FTIR, gas chromatography, GC-MS and high resolution mass spectrometry. Deasphalting removed 36 % of nitrogen, 44 % of sulphur and 47 % of oxygen. Nevertheless, the deasphalted liquids would require further removal of heteroatoms by hydroprocessing. Polynuclear aromatic compounds appeared in all extrografic fractions. Nitrogen-containing compounds have been found in the fractions III, IV and V, when polar solvents have been used. Some mixed heterocyclic compounds (N-O, N-S) have been observed in the most polar fractions (V and VI).