Study and spectroscopy characterization of carbon & oxygen structures of Gaoyang coking coal

Coal structure is an important research content of coal chemical industry.Carbon is the backbone of the coal structure.Oxygen is the most abundant heteroatom in coal.The studies on the structure of carbon and oxygen are of great significance to build macromolecular models,acknowledge the structural characteristics and reaction characteristics and then improve the comprehensive utilization level of coking coal.The basic parameters of coal structural units,such as aromatic structure,fatty structure,hydroxyl group,oxygen containing functional group structure,aromatic carbon ratio,aromatic hydrogen ratio and average structure size of aromatic nucleus in the Shanxi Gaoyang coking coal are obtained by investigating proximate,ultimate,13C Cross Polarization/Magic Angle Rotation Nuclear Magnetic Resonance (13C CP/MAS-NMR),Fourier Infrared Spectroscopy (FTIR) and X ray Photoelectron Spectroscopy (XPS).The results show that the aromatic carbon ratio of the Gaoyang coking coal is 0.73-0.77 an is 0.43.Phenyl ring penta substituted,benzene ring tetra substituted and benzene ring tri substituted are the main aromatic hydrocarbon structures in the Gaoyang coal,accounting for 41.42%,30.65% and 19.82% respectively.Methylene is the main aliphatic hydrocarbon structure in the Gaoyang coal,accounting for 41.85%,the methyl and methine content is 29.86% and 28.29%,respectively,which demonstrate that coal contains more alkyl side chains and cyclic aliphatic hydrocarbons.Carbonyl and phenolic hydroxyl groups are the most important oxygencontaining functional groups in coal.Hydrogen π bonding with π electrons on the aromatic ring accounts for 73.20% of the hydroxyl structure in coal.There are 118 aromatic carbon atoms and 25-32 aliphatic carbon atoms in the Gaoyang coking coal molecular model.Among them,the number of methyl carbons,methylene carbons,methine carbos,carbonyl groups and carboxyl groups are 7-8,9-11,6-8,and 5 respectively.At the same time,there are seven oxygen atoms,which be made up of six carbonyl groups and the phenolic hydroxyl groups,the last oxygen atom is divided with thioether,sulfone and sulfoxide.Further investigation should be made on the heteroatom structures of sulfur and nitrogen in coal and comprise more carbon atoms and oxygen atoms to build a precise macromolecular model of the Gaoyang coking coal.