Structural characteristics and pyrolysis behaviors of huadian oil shale kerogens using solid-state 13 C NMR, Py-GCMS and TG

The chemical structure of fossil fuel has a significant effect on its pyrolysis. Present work studied the relevance of chemical structure and pyrolysis characteristics of three Huadian oil shale kerogens by using 13 C NMR, Py-GCMS and TG. 13 C NMR indicates aliphatic carbons are dominated in kerogen carbon skeleton and mainly in the form of straight methylene chains. Compared to kerogen of Dachengzi and Gonghe oil shale, kerogen of Gonglangtou oil shale has much higher branched degree of aliphatic chain, content of aromatic methyl and aromaticity. Distribution of fast pyrolysis products and thermal mass loss behaviors of kerogen are discussed with the correlation between the pyrolysis mechanism and chemical structure. The results of Py-GCMS show that main components of shale oil come from the structure of aliphatic carbons, especially methylene chains, and there is a clear correlation between content of aromatic products and aromaticity of kerogen. TG curves are fitted by a set of sub-curves which represent various types of chemical bond cleavage during pyrolysis. The fitting results indicate mass loss mainly results from cleavage of bonds related to aliphatic carbons and difference of total mass loss is due to content of aliphatic carbons. The difference of mass loss at high temperature (500–1000 °C) is related to the bond cleavage of aromatic structure.