Petrology and structural studies in liquefaction reactions of Late Permian coals from Southern China

Three coals from South China, having high contents of vitrinite, liptinite, hydrogen, volatile matter, and high H/C atomic ratios, were subjected to liquefaction in tubing-bomb microreactors at 430 degrees C for 1 h with tetralin, hydrogen, and iron sulfate catalyst. The optical characteristics of the liquefaction residues were studied by white-light and fluorescence microscopy. A comparative study on the chemical structural features of the raw coals and their respective liquefaction residues was conducted by Fourier transform infrared spectroscopy (FTIR) and flash pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The liquefaction conversions were in the range of 79.0-87.1% (daf basis) under the conditions used. The optical examination of the liquefaction residues indicated that all of the liptinite and most of the vitrinite have reacted. For Dahebian coal, the observed liquefaction conversion was greater than the total vitrinite and liptinite content, indicating that some of the inertinite macerals must have participated in the reaction. Anisotropic semicoke was observed in the residue. Both FTIR and Py-GC/MS techniques showed that aliphatic groups, oxygen-containing functional groups, alkylbenzenes, and alkylphenol have reacted in liquefaction. C-2-naphthalene and C-3-naphthalene are main constitutions in residues. (c) 2012 Elsevier Ltd. All rights reserved.