19.石炭の溶媒抽出率に及ぼす種々の塩の添加効果

抄録

The effect of addition of various salts, the anions of which were changed systematically, on the extraction of seven different kinds of coals with carbon disulfide-N-methyl-2-pyrrolidinone (CS_2-NMP) mixed solvent (1:1 by volume) was investigated. Addition of some salts considerably increased the extraction yields of some coals. For Upper Freeport coal, in particular, the addition of very small amount, 0.25mol/kg-coal of tetrabutylammoniumfluoride (TBAF) increased the extraction yield from 59 to 84%. The effect of the anion type on the extraction yield was also examined. In the case of halogenide ions, the smaller ion was added, the higher extraction yield was gained. HSAB rule (Hard and Soft Acids and Bases) was applied to explain the relationship between the extraction yield and the anion property. The fractionations of the extracts indicate that the extracts produced with the additive contain heavier and aromatic-richer constituents than that without additives. Acid-base interactions between acidic sites of the coal samples and the anions were focused and the effect of modifying of coals to the extraction yield was investigated by means of O-methylation and acid treatment.