The modern typical structural model of brown coal may be described by its structural parameters determined by various chemical and instrumental analyses

and the model suggested by Mr. Yang was so examined with current literature data. Higher hydrogen aromaticity

lower ring condensation index and an appropriate adjustment of the distribution of functional groups were proposed for the modification of the model. As for the mechanism of its thermodegradation

tha methoxyl group seems to be dissociated readily during the initial stage and contributes only little of methane. The role of β-scission of the substituents on the aromatic rings is emphasized since the conjugation effect due to the aromatic double bonds lowered significantly the dissociation energy of the β-bond.The methyl group on the aromatic ring tends to the cyclization rather than demethylation

so limits the formation of methane from the methyl group.However

the naphthenic ring such as in the structure of tetralin

ruptures more easily than its dehydrogenation

its potential of hydrocarbon formation must not be underestimated. The relation between the structural model and the thermo-degradation mechanism is also approached.