Fine characterization of the macromolecular structure of Shanxi low-rank coal

Abstract

Due to the particular paleogeological structure of Shanxi, the macromolecular structure of Shanxi low-rank coal appears special characterizations. The combination of qualitative and quantitative methods showed that Shanxi low-rank coal was composed of amorphous carbon and ordered aromatic clusters, which was an intermediate turbostratic structure between amorphous and graphite. The molecular structure model and carbon skeleton structure model of the low-rank coal were drawn on this basis. The molecular model could simplify the molecular formula to be C205H138O27N2S, which was dominated by aromatic and aliphatic structures. The proportion of aromatic carbon in coal was 75.31%, mainly composed of 1∼2 benzene rings, and the aliphatic structure was composed of cycloalkyl and alkyl side chains. The carbon skeleton structure showed that the diameter of the aromatic layer of the coal was 1.89 nm, the interlayer spacing between crystal layers was 0.36 nm, the average number of aromatic flakes per stack was 3.78, and the value of stacking height was 1.00 nm. Supplementally, parameters such as crosslinking density (0.39) and AD/AG area ratio (0.79) also provided a deeper understanding of coal structure and laid the foundation for low-rank coal utilization.