“…For instance, at 375"C, 0.3 g/cm3 water density, and a 15 min residence time, introducing the coal directly into SC water produced 75% THF solubles, whereas mixing water and coal at ambient conditions and then heating them together to supercritical conditions produced only 60% THF solubles. Similar trends for the variation in the yield of THF solubles with solvent density were also reported when SC toluene was the solvent (Deshpande et al, 1986). This group formulated a kinetic model based on the hypothesis that a part of coal dissolved instantaneously in the SCF and underwent liquefaction reactions that formed oils, asphaltenes, gases, and char.…”