Recycle solvents used in a 150t/d NEDOL coal liquefaction pilot plant were separated into non-polar and polar component, and the non-polar component were examined by GC and GC-MS. Major compound classes in the each non-polar component were quantified, and the influences of raw coal and the concentration of coal in a feed slurry on their composition were discussed.
The influence of raw coal was appreciable in the amount of n-paraffins and polar component in the solvent. Perhydrogenated homologues of polycondensed aromatic compounds were contained in only negligible amounts. The higher concentration of coal in a feed slurry needed the larger amount of heavy distillate in the solvent and the severe hydrotreatment to enhance hydrogen donating ability of the solvent, which resulted in the increase of larger cyclic compounds with more naphthenic rings.
The fa value of each compound class was similar for all the solvents, and the average fa values were useful for the evaluation of the fa values of the recycle solvents by being combined with the compound class composition obtained from HPLC
