XPS and FTIR Spectroscopy Characterization about the Structure of Coking Coal in Xinyang

Structure and occurrence recognition for primary elements in coal are the foundations to acquire coal structural parameters and it is of great significance to construct a coal structure model, study reaction characteristics of coal and rationally utilize coal resources. At present, studies on the coal structure are most targeted at coals with a low-medium metamorphic degree. In comparison, the structure of coking coal is rarely studied and no structure model has been presented for it. In this paper, FTIR was adopted to carry out spectral characterization for hydroxyl polar groups, fat composition, aromatic structure, oxygen-containing functional group and miscellaneous atomic structure in Xinyang coking coal. The results demonstrated that, on the one hand, hydroxide radical pi hydrogen bond formed by the Xinyang coking coal with pi electrons in the aromatic nucleus was a main existing form of hydroxide radical; on the other hand, polymer was a concrete embodiment of associated structures in the coal. Besides, it also indicated that contents of methyne, methyl and methylene went up successively; and, methylene and methyne had a content occupying 82. 05% in the total aliphatic hydrocarbon content in coal. The coal contained a great number of alkyl side-chains. Benzene ring-disubstitution and trisubstitution, with 86. 74% taking in the total aromatic hydrocarbon content of coal, were primary structures of them. For an oxygen-containing functional group, while hydroxide radical and carbonyl were its principal composition groups, the content of carboxyl and ether group was less than 10%. In the Xinyang coal enriched with silicon, its occurrence lies in forms of Si-O-Si and Si-O-C. The main existing form of nitrogen included pyridine, pyrrole and oxynitride and most nitrogen distributed on edges of building blocks of coal molecules. As far as organic sulfur in coal was concerned, its primary existing form was thiophenic sulfur, the content of which exceeded 60% of the total organic sulfur content, followed by those of sulphone and sulfoxide. Occurrences of mercaptan and thioether were both at a minimum level.