FTIR Characterization of the Residues of High-temperature Extraction and Subsequent Oxidization depolymerization of Lignite

In order to explore high-efficiency utilization approach of lignite, Xianfeng lignite was extracted by toluene/methanol (3:1) mixed solvent under 300 degrees C in an autoclave combined with high-temperature separator. Subsequently, the thermal extraction residue was oxidized by 3% hydrogen peroxide aqueous solution at room temperature. The raw coal and its residues of thermal extraction and oxidization were further extracted respectively by THF and CS2/NMP mixed solvent, and the extracts and the extraction residues were characterized by FTIR. The results indicate that thermal extraction of lignite relaxes the network structure of coal matrix by disrupture the non-covalent bond interactions. The methylene bridge bond is easy to be oxidized into carboxyl and hydroxyl functional groups. Therefore, these results are very significant for the development of high-efficiency conversion technology.