INTRODUCTION TO THE PETROLOGY AND INFRARED-SPECTRA OF SHANXI COALS, PEOPLES-REPUBLIC-OF-CHINA

Twelve samples of coal from the three major depositional episodes which occurred on the North China Block during the Carboniferous, Permian and Jurassic Periods have been investigated. The samples varied in rank from high volatile bituminous coal to anthracite and, although the coals from the three sequences were formed from different plants under different climates, plots of random vitrinite reflectance against elemental H/C ratios were similar to those previously reported from coals deposited in Euramerica and Gondwanaland. None of the samples which have been examined contained significant quantities of liptinite; the vitrinite consisted mainly of desmocollinite. Shanxi coals resemble petrologically those from Gondwanaland. Diffuse reflectance, Fourier transform infrared (FT-i.r.) spectra of twelve samples and of their residues after pyridine extraction are presented and the chemical structures of these vitrinite-inertinite coals are shown to be very similar to those of better known bituminous coals. Increasing maturity (rank) of the coals can be attributed to increase in the geothermal temperature to which they have been subjected and is accompanied by the expected increase in aromaticity and also by an increase in the protonation of the aromatic structures. The spectra suggest that vitrinite-inertinite rich coals from many different depositional settings have similar patterns of substitution around their aromatic rings, the similarity increasing with rank. Thus the chemistry of vitrinite-rich coals appears to be controlled by the possession of common hydroaromatic structures.