Structural evaluation of zao zhuang coal

The structure of Chinese bituminous Zao Zhuang coal was carefully evaluated on the basis of information from NMR, pyrolysis, ruthenium-catalyzed oxidation reaction (RICO), and single coal particle solvent swelling methods. This coal and its SRC liquefaction fractions show good coking property so that the pyrolysis is accompanied by a lot of coke, this being less useful for its structural elucidation than the case of Japanese Akabira coal. The pretreatment of this coal by the ether bond cleavage reaction can increase volatile-comprising molecules that when recognized provide valuable information on molecular constituents of the coal. SPE/MAS ¹³C NMR and CP-DD (dipolar dephasing)/MAS ¹³C NMR techniques were used to assess carbon distribution. The RICO reaction offered information regarding aliphatic functionalities and bridge types and also suggested the presence of some types of molecular units. Solvent swelling experiments implied that this coal has, on average, relatively low cross-link density and verified the structural heterogeneity of the coal. By using the data from the analytical techniques given above, a model structure of Zao Zhuang coal consisting of one MS, one PS, and two PI structures was constructed. The proposed structure is in keeping with various aspects of its reactivity.