As we all know, Sulfur is an objectionable component in some coals, and coal liquids, intended for combustion or chemical manufacturing. Although, as we've documented, Sulfur can improve the coal liquefaction process.
Should, however, Sulfur need to be reduced in coal being fed into a coal liquefaction facility, a major product, Methanol, of coal-to-liquid conversion itself can be used, in the initial processing of the raw coal, to recover much of the Sulfur that might be present, as a salable product.
Other methods of desulfurization exist and are commercially employed. But, we find this concept to be most intriguing since it might allow a more integrated design of the coal conversion plant, and actually reduces costs relative to having to add separate, auxiliary installations, such as the Klaus units we've previously reported, to recover the Sulfur.
As follows:
"Document title
Coal desulfurization with methanol/water and methanol/KOHAuthors
RATANAKANDILOK S.; NGAMPRASERTSITH S. ; PRASASSARAKICH P.;Authors Affiliation
Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330, THAILANDEAbstract
Mae Moh coal from northern Thailand was desulfurized by leaching with methanol/water and methanol/KOH in a batch reactor. The effect of methanol concentration, KOH concentration, coal particles, reaction temperature and reaction time on the removal of ash and sulfur was investigated. Depending on the desulfurization conditions, the reductions ranged from 36 to 74% in pyritic sulfur, 20 to 42% in organic sulfur and 33 to 62% in total sulfur. Methanol/KOH enhanced the desulfurization process in which the inorganic and organic sulfur were removed preferentially. KOH addition can improve the sulfur removal. The kinetics of the oxidation of pyritic sulfur was investigated for Mae Moh coal. The rate of reaction was found to be well represented by a continuous reaction model that was second order with respect to pyritic sulfur."Our supposition is that the Methanol and the Sulfur can be separated from each other subsequent to extraction, and then directed into commercial outlets. Sulfur could well be an additional profit center for a coal-to-liquid conversion facility, and thus help to improve the overall economics of CTL industry.