Chemical Composition of Coal-derived Liquid and Its Upgraded Oils

Abstract

Coal -derived liquid obtained from 150ton/day NEDOL pilot plant was upgraded over a presulfided Ni-W/Al₂O₃ catalyst under a hydrogen pressure of 12MPa. The original coal liquid and three upgraded oils were separated into several compound groups and analyzed by GC -FID/NPD, GCMS and FIMS in order to identify the molecular species in the feedstock and upgraded oils.
The coal liquid was composed of paraffins (17%), naphthenes (20%), oleffins (4%), monoaromatics (17%), polyaromatics (17%) and polar components (25%). After the upgrading over Ni-W/Al₂O₃, polyaromatics decreased to 0.7-4.7% and polar components were reduced below 0.1%, which resulted in the large increase of naphthenes and naphthenobenzenes. Basic nitrogen compounds (N: 4, 200ppm) in the coal liquid were piridines, anilines, quinolines and benzoquinolines and their hydrogenated derivatives, and nonbasic nitrogen compounds (N: 1, 400ppm) were alkylnitriles, pyrroles, indoles and carbazoles. Sterically hindered nitrogen compounds like 2, 4, 6-trimethylpyridines and 2, 6-anilines tended to remain in upgraded oils. Saturated cyclic nitrogen compounds of which molecular weights were expressed as 165+14n and 205+14n (n=0, 1, 2 …) were found to be least reactive for the denitrogenation, although their detail structure was not identified. Polyaromatic compounds which remained in upgraded oils were biphenyls and dibenzofurans due to their less reactivity and dihydrophenalene and pyrene at their hydrogenation equiribrium.