EXTRACTION OF LOW-RANK COALS OXIDIZED WITH HYDROGEN-PEROXIDE IN CONVENTIONALLY USED SOLVENTS AT ROOM-TEMPERATURE

A new method was developed for extracting a great deal of brown coal i n several conventionally used solvents at room temperature. The coal w as pretreated with hydrogen peroxide in liquid phase at 60 degrees C f or 2 h to break some weak covalent bonds and to introduce oxygen funct ional groups. The pretreated coal was extracted by binary solvents of a low-molecular-weight alcohol (methanol, ethanol, 1-propanol, or 2-me thyl-1-propanol) and an aromatic compound (1-methyl-naphthalene, 2-met hylnaphthalene, m-xylene, or phenol) of different mixing ratios at roo m temperature by the conventional method. In the binary solvent of met hanol-l-methylnaphthalene consisting of 0.56-0.44 volumetric ratio, su rprisingly, 84 wt % of the pretreated coal were extracted. The pretrea ted coal was extracted by 13 wt % even in a pure methanol, but it was not extracted at all in a pure 1-methylnaphthalene. The extraction mec hanism of the oxidized coal in the binary solvent was discussed. Since l-methylnaphthalene is involved in coal-derived liquids and methanol is one of most popular solvents, the developed method will be useful f or utilizing low-rank coals efficiently.