Bingbing Song, Yangyang Zhang
Sequential thermal dissolution of Naomaohu (NL) brown coal in cyclohexane, methanol, ethanol and isopropanol was conducted at 300 oC for 2 h in turn. All soluble parts (SP1-SP4) were analyzed by gas chromatography/mass spectrometer. NL was analyzed by thermogravimetric analysis (TG). Thermal dissolution residue (ER4) was analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS). As a result, NL underwent a strong bond breaking process between 400-500 oC, mainly the breakage of covalent bonds such as Calk-C, Calk-H, Cak-O and Car-N. The existence of COO species in ER4 indicated that methanol, ethanol and isopropanol might be esterified or ester-exchanged with carboxylic acid, while the reduced C-O species illustrated that the nucleophilic oxygen atom in methanol, ethanol and isopropanol attacked the carbon atom on the carbonyl group in NL. By GC/MS, compounds detected in SP1 are mainly alkanes, alkenes, and aromatics, while phenols predominant in SP2, alcohols and esters are dominant in SP3, and alkanes are mainly found in SP4. It is noteworthy that NCOCs relatively high in SP2, and SCOCs were detected only in SP2 and SP3.
Cyclohexane; Methanol; Ethanol; Isopropanol; Brown Coal