Abstract
Coals with carbon content between 67.5 and 91.5% were treated with zinc powder, naphthalene and water at 445°C for 30-60 min under nitrogen atmosphere (initial pressure 8.0 MPa). In this reaction, hydrocracking is caused by the nascent hydrogen produced from the reaction of water and zinc (M+xH2O→MOx+xH2).
The conversion of coals with carbon content less than 90% was more than 80% and the solvent extraction yield was more than 80% for the coals between 81 and 87%C.
The reaction time (15-60min) scarcely affects the conversion and the structural parameters of the pyridine extracts of 67. 5%C coal. The results showed that the reaction was completed in 30min.
The structural indices of the pyridine extracts of reacted coals when compared with those of products obtained by other solubilization methods (alcohol-alkali treatment, quinoline extraction and mild hydrogenation) revealed that depolymerization was the main reaction, however, some dealkylation and saturation of the aromatic rings also took place in small amount. Nevertheless, it is possible to obtain the images of the unit structure of the coals used. The structural unit of the coal of 67. 5%C has one benzene ring with one naphthenic or heterocyclic ring. The coal of 72.2%C has a structural unit consisting of one naphthalene ring and one naphthenic or heterocyclic ring. The structural unit of coals with 77.9 and 81.2%C consists of one benzene or naphthalene ring with one naphthenic or heterocyclic ring. The coal of 86.6%C appears to have a structural unit including 3 or 4 aromatic rings with 1 or 2 naphthenic or heterocyclic rings. The coal of 91.5%C has a structural unit consisting of 4 or 5 aromatic rings and 1 or 2 naphthenic or heterocyclic rings.
