This technology is available from Temarex Corporation.
Title:EXTRACTION OF ORGANIC SULFUR FROM COAL BY USE OF SUPERCRITICAL FLUIDS
Inventor(s):S. Lee, S. Kesavan, V. Parameswaran
Disclosure 89 U.S. Patent 5,080,692
Organic sulfur is removed from coal by extraction with a water/methanol/carbon dioxide mixture under supercritical conditions of temperature and pressure, i.e., at a critical temperature and pressure, respectively.The preferred solvent used for extraction has the following composition (expressed as a mole fraction);
Carbon dioxide- from 0 to 0.30 Methanol- from 0.20 to 0.70 Water- from 0.20 to 0.70
Preferably, the mole fraction carbon dioxide is at least 0.05 and the mole fraction of water is not greater than 0.65. Either fixed bed (semi-batch) or mixed reactor systems can be used.Operations may be carried out in a single stage using a solvent of constant composition, or may be carried out in plural stages in which the critical temperature of the solvent used in each stage (except the first) is higher than that used in the preceding stage.Overall molar quantities of solvent used in plural stage operations are in accordance with the mole fractions given above.A substantial amount of the total organic sulfur present is removed.
Unlike prior supercritical coal treatment techniques, this process preferentially removes a large fraction of the sulfur compound without significant loss of volatiles or other organic species.