Liquefaction Reactivities of Three Subbituminous Coals in Tetrahydrofluoranthene as a Hydrogen Donor

Three subbituminous coals (Indiana V, Wandoan, and Wabamun coals) of different ranks were reacted in tetrahydrofluoranthene (4HFL) under variable temperature-time conditions. Indiana V (the highest rank coal in this study) gave the highest total yield of oil and asphaltene (greater than 90%) at 450 °C/30 min, whereas the other two coals of lower rank gave the highest total yield at 510 °C/2.5 min (90% and 83%, respectively). The highest oil yield was always obtained under the more severe conditions, regardless of coals. Although low concentrations of 4HFL in the solvent decreased the yield under all conditions examined, the relative decrease was greater with the high-rank coal at higher temperatures. Indiana V and Wandoan coals were almost completely liquefied to THF-soluble products under their respective optimum conditions, whereas 9% of Wabamun coal remained quinoline insoluble under all conditions tested, even though all coals contained considerable amounts of inert macerals. Inert macerals in Wabamun coal were compared microscopically to those in Indiana V and Wandoan coals, suggesting that characterization of “true inerts” in the hydrogen-transferring liquefaction should be established.