~(13) C-NMR analysis on different macerals of several low-to-medium rank coals

Structure characteristics of the different macerals of 5 low-to-medium rank coals were studied by means of 13 C-NMR. The molecular structure characteristics and parameters of the macerals were discussed. The result indicates that the aromaticity of inertinite is higher than that of vitrinite. There is less aliphatic hydrocarbon in inertinite. The side chain of hydrocarbon in inertinite is shorter than that in vitrinite. With the increase of coal rank, the aromaticity of both inertinite and vitrinite increases, but the aromaticity of inertinite increases more slowly than that of vitrinite. The aromatization (not ring-condensation) is dominant in the period of coalification of low-to-medium rank, and this phenomenon is more remarkable in vitrinite than that in inertinite. Additionally, the result of 13 C-NMR also shows that the total oxygen content in inertinite is lower than that in vitrinite.