Supercritical Fluids for Reaction and Extraction of Coal and Heavy Oils. Final Report, September 1, 1981-September 1, 1983

摘要

A study of supercritical extraction includes extraction/reaction of different ranks of coals using water and organic solvents under supercritical conditions, and study of solubility of mixtures of model compounds in a supercritical fluid. Emphasis has been placed on developing a fundamental understanding of supercritical phenomena and on the potential for utilizing supercritical extraction for coal conversion and coal deashing. Batch experiments in a 1 litre autoclave with different types of coals and solvents are reported. Experiments were conducted initially with glucose as the substrate to duplicate results in the literature. Systems studied are represented by various combinations of: glucose-water, German brown coal-toluene, and Bruceton bituminous coal-piperidine. The effect of time of extraction, supercritical phase density, temperature, pressure, coal rank and stirrer speed on the extent of conversion of coal to liquids and gases have been studied. The experiments lead to the following conclusions: (1) injection of coal under supercritical conditions results in better conversion and less char than when coal is present during the heat-up period; (2) THF insolubles are considerably decreased when higher supercritical phase densities are used; (3) conversions approach equilibrium with increase in reaction times to one hour; (4) experiments with various solvents indicate that a minimum temperature (about 370 exp 0 C) has to be reached to achieve appreciable conversion; (5) the acidity of the extracted product is high when water is used as the solvent and high sulfur coal as the substrate. It may be attributed to dissolved H sub 2 S. Apparently water, under supercritical conditions, is leashing out some of the inorganic material in ash; and (6) an increase in stirrer speed from 500 to 2500 rpm resulted in lower THF insolubles. Apparently, a speed of 500 rpm is insufficient to keep the coal in suspension. (ERA citation 09:000031)