A New Clean Coal Technology by Mild Modification at Low Temperature

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In order to develop a new pretreatment, method for producing a clean and reactive coal, we performed the following items :(1)Development of liquid phase oxidation of coal.(2)Performance of the removal of alkali metal and sulfur through the pretreatment.(3)Analysis of cross-linking reaction of pretreated coal(4)A new co-liquefaction of coal and pretreated coal.First, it was found that a part of aromatic rings were ruptured into aliphatic structures and a large amount of hydrogen was introduced in the coal through the liquid phase oxidation with HィイD22ィエD2OィイD22ィエD2. Simultaneously, a large amount of small molecule fatty acids were recovered, indicating that the oxygen removed from coal by a from of valuable chemicals. Thus pretreated coal was served to the pyrolysis and combustion, then the emission profiles of alkali metal vapor and sulfur was examined. Their amounts emitted dramatically decreased through the HィイD22ィエD2OィイD22ィエD2 oxidation.Next, we examined the reactivity of the pretreated coal. We analyzed the kinetics of the cross-linking reaction during the heating of pretreated coal. The COOH groups introduced through the pretreatment was decomposed to cross-link by 400℃, but the pretreated coal under severe condition was not cross-linked because the COOH was removed by a form of a small molecule fatty acids. Since it was also found that the pretreated coal was easily dissolved by solvent at 200℃, we present a co-liquefaction of coal and pretreated coal by utilizing this property. The liquefaction yield increased by adding the pretreated coal in place of a part of solvent.Thus it is clarified that the proposed method is effective as a pretreatment method for producing a clean and reactive coal.