SUPERCRITICAL DESULFURIZATION OF HIGH RANK COAL WITH ALCOHOL WATER AND ALCOHOL/KOH/

A high rank coal with total sulfur of 4.90% was extracted employing al cohol/KOH and alcohol/water under supercritical conditions both in a s emi-continuous reactor and in a batch reactor. In the semi-continuous reactor it was found that supercritical desulphurization is mainly tak ing place within about one hour at 400 degrees C. Pretreatment of coal with KOH up to 5% concentration was favourable for sulfur removal, bu t greater KOH concentration and longer soaking time brought about the opposite results. When the ethanol concentration was 95 vol% the organ osulfur removal achieved the maximum. Ethanol/KOH solution as supercri tical solvent enhanced the desulfurization process, in which the inorg anic sulfur was removed preferentially. In the batch reactor it was fo und that there was reincorporation of both organic sulfur and inorgani c sulfur. KOH addition can improve the sulphur removal greatly. When K OH/coal ratio was greater than 0.5, the tendency for sulfur removal wa s gradually slow.