Solvent extraction and oxidation of coal under mild conditions can assist in understanding of coal chemical structure.
It can also offer a potential for conversion of coal into useful chemicals, allowing more efficient use of coal
resources. In this study, a Chinese lignite was extracted by different solvents including CS2, ethanol, and acetone.
The composition of the extracts was analyzed by GC–MS method. It was found that the CS2 extracts contained
high amounts of aliphatic hydrocarbon. The ethanol and acetone extracts mainly contained oxygen-containing
compounds. The effects of reaction temperature and residence time on coal oxidation and composition of extract
residueswere also investigated. The results showed that lignite was readily oxidized in H2O2 aqueous solution at
temperatures above 40 °C, and the oxidation behavior (oxidation rate, product distribution and yields) was
strongly temperature dependent. Oxidation of extract residues in H2O2 solution was carried out at different
temperatures. Water soluble products of oxidation were analyzed using the GC–MS. Aliphatic hydrocarbons
were present in all oxidation steps. The relative content of esters in all oxidation stepswas also high. The chemical
structure changes of coal, the extract residues, and the oxidation residueswere studied using FTIR technique. The
results indicated that the extract residues had lower intensity of aliphatic hydrogen compared to raw coal. The
aromatic carbon concentration remained relatively unchanged when oxidized at temperatures below 30 °C,
then decreased slightly with increasing the oxidation temperature.