STUDY ON STRUCTURAL EVOLUTION CHARACTERISTICS OF STRUCTURAL COAL MACROMOLECULAR STRUCTURE BASED ON INFRARED SPECTROSCOPY AND NUCLEAR MAGNETIC RESONANCE

摘要

To effectively study the evolution of macromolecular structure in tectonic transformation and thermal evolution in tectonic coal,this paper studies the aromatic carbon structure,fat side chain and oxygen-containing group in coal based on infrared spectroscopy and nuclear magnetic resonance experiments.Nuclear magnetic resonance was used to carry out quantitative studies on 13C spectra.The following results were obtained: as the brittle deformation increased,the length of the structural chain of the structural macromolecules increased,and the degree of branching gradually decreased.The infrared spectrum of the original structural coal and structural coal fat side chain is mainly composed of three main peaks,which are located at 2920,2855 and 2950 cm" 1 respectively,corresponding to the antisymmetric R2CH2 stretching vibration,symmetric R2CH2 stretching vibration and antisymmetric RCH3 vibration; The intensity is reduced in turn.The hydroxyl groups in the oxygen-containing groups of the coal are obviously divided into 4-6 absorption peaks in the infrared spectrum.The total absorption area of the hydroxyl groups decreases with the increase of the structural deformation.In the brittle deformation stage,the decreasing trend is more obvious; the ductile deformation stage changes.It is not large; the oxygen-containing functional group in the macromolecular structure of coal is divided into oxygen-bonded aromatic carbon and oxygen-bonded fatty carbon.From the results of nuclear magnetic resonance,the total oxygen-containing functional group has reduced absorption intensity.Moreover,under the influence of tectonic stress,it is less likely that the detached oxygen-containing functional group forms a new oxygen-bonded aromatic carbon with unstable carbon-carbon bonds or side chains in the aromatic ring.