Solubilization of Coal by Reductive Alkylation Reaction -Relation Between Reaction Time of Anionization and Solubilization-

Abstract

In reductive methylation reaction of coal using molten potassium, relations between reaction time of anionization and solubilization have been studied. Three kinds of coals of different coalification degree were reacted with variable reaction times (30∼360 min) of anionization. In about 30 minutes of anionization time, 6∼7 methyl groups per 100 original carbon atoms were introduced and a remarkable increase of pentane- and benzene-soluble products were obtained. From these results, it was considered that the solubilization was caused by scission of C-O-C bonds and subsequent introduction of methyl groups in chemical unit of coal structures, and that these reactions occurred remarkably in early stage of anionization. Better yield of the soluble products was obtained from high rank coal (Kairan) than low rank coal (Yùibari and Kitadein), and some continuous increase of the yield (up to 75%) were obtained for high rank coal by the scission of remaining C-O-C bond and introduction of methyl groups, while increase of the yield after initial stage was not observed for low rank coals.
The difference of the solubilization character among various coa ls was considered to depend on amount of ether linkages, bridged structures by functional groups, size of aromatic rings, and so on, in original coal structures.