A STRUCTURAL MODEL FOR LIGNIN-DERIVED VITRINITE FROM HIGH-VOLATILE BITUMINOUS COAL (COALIFIED WOOD)

Using data from elemental analyses, solid-state C-13 NMR, and pyrolysis/gas chromatography/mass spectrometry, a structural model for coalified wood of high-volatile bituminous coal rank was constructed. Considering the fact that the vitrinite was derived from lignin, we utilized a model of lignin as a template upon which the coal structure is based. The chemical structural information derived from comparisons among coalified gymnospermous wood samples ranging in rank from subbituminous to high-volatile C bituminous coal provided the basis for constructing the model. Modifications of a previously published structural model for subbituminous coal, originally derived from the lignin template, involved condensation of phenols to diaryl ethers and cyclization of alkyl side chains to form naphthalenic structures. A computer software program was used to construct the structural model in three dimensions whereby an energy minimization program was subsequently applied to represent the structure in it lowest energy conformation.