A MODEL STRUCTURE OF ZAO-ZHUANG BITUMINOUS COAL

A model structure of Zao Zhuang bituminous coal (Shan Tong province in China, 86.9 wt % C) based on the structural analyses and the computer simulation was constructed. The coal was extracted with pyridine or carbon disulfide-N-methyl-2-pyrrolidinone (CS2-NMP) mixed solvent, and the extracts obtained were further fractionated. The extract fractions were hydrogenated using Adkins catalyst under mild condition at 430 degrees C for 1 h. The structure of the oil (n-hexane solubles) obtained from each extract fraction was analyzed by mass spectrometry after column separation and the molecular models of the fractions including the extraction residue were constructed assuming associated structure of coal molecules. Finally, a model structure of Zao Zhuang coal which consists of a huge associate of coal molecules was constructed three-dimensionally using computer-aided molecular design (CAMD) by assuming an anisotropic model structure formed from a periodic boundary cell. Good agreement of the physical density (1.22 g/cm(3)) of the constructed model with that (1.29 g/cm(3)) observed experimentally suggests that Zao Zhuang coal has a possibility to have associated structure of coal molecules having a continuous distribution of molecular weight from the lighter fraction to the solvent-insoluble residue.