Cluster Analysis of Soluble Organic Fractions in Two Low-Rank Coals

A brief overview of the composition and structure of soluble organic compounds as well as organic macromolecules in coal is sufficient to support the development of the coal chemical industry and realize the clean, effective, and high value-added exploitation of coal. In this study, 14 groups of extracts were analyzed by a gas chromatograph-mass spectrometer; seven stages of solvent-graded extraction were carried out on two typical low-rank coals, and the extracted substance spectrum data were processed by principal component analysis and cluster analysis to investigate the molecular makeup and structure of the soluble organic compounds in the two coals. CS2 had a better extraction effect on aromatic hydrocarbons, and methanol was better for the enrichment and separation of oxygenated compounds. Hexane and petroleum ethers have a good extraction effect for aliphatic hydrocarbons; benzene has a good effect for the extraction of nitrogenous compounds; acetone has a greater extraction rate for alcohols; tetrahydrofuran has a more obvious extraction effect for ketones; the mixed solvent of tetrahydrofuran and methanol has a greater extraction rate for esters.