Evaluation of detailed molecular structures for sequential thermal dissolution extracts of a subbituminous coal using a tandem mass spectrometric method

Abstract Comprehensive and in-depth understanding of the molecular structure of low-rank coals is the basis for clean and efficient utilization. The detailed molecular structure of sequential thermal dissolution (TD) extracts from a subbituminous coal was characterized using a high-resolution mass spectrometry run in a tandem MS method, in-source collision-activated dissociation. Cyclohexane and toluene TD extracts released compounds with less oxygen and more nitrogen atoms located on aromatic cores compared to ethanol and isopropanol TD extracts. Archipelago-structured compounds presented in asphaltenes were also observed in compounds from toluene TD extract. Principle component analysis, a multivariate statistical method, was introduced to mine molecular characteristics of the TD extracts. TD yield and relative abundance of CH class (without heteroatom) became the key point to determine the clustering pattern for whole molecules and aromatic cores, respectively.