抄録
A statistical lattice theory was applied to analyzing characteristics of chemical degradation of Morwell brown coal caused by an aqueous-phase O_2 oxidation that exclusively eliminates aromatic ring clusters. The theory predicted well the relationships among changes in the amounts of clusters, bridges and carboxyls as peripherals. A model assuming the coal as a mixture of a fully-developed Bethe pseudo-lattice and m-mers (m=1-40) quantitatively explained the increase in the fraction of DMF solubles with an extent of elimination of clusters.