58 / 2021-09-08 15:37:05

Spectroscopic study on molecular structure of raw coal from Daliuta coal mine

Coal molecule,FTIR,XPS,13C CP/MAS-NMR,Spectral characterization

Abstract: the molecular configuration of coal is understood from the microscopic point of view, which is conducive to the efficient application and heat treatment of coal. Daliuta(DLT) coal mine of Shendong coal group is taken as the research object. The molecular structure parameters are calculated by industrial analysis, determination of main element content, FTIR, XPS and ¹³C CP / MAS-NMR. Through the analysis of the above technical means, the molecular structure parameters are calculated, and the main elements are characterized and comprehensively analyzed by spectroscopy to clarify the molecular structure of Daliuta coal mine. The results show that naphthalene, phenanthrene or anthracene are the main condensed rings of DLT raw coal. The ratio of bridgehead carbon to marginal carbon is about 0.34, and the proportion of benzene ring tri-substitution is the largest, followed by the proportion of benzene ring tetra-substitution. The primary carbon and secondary carbon are the most in aliphatic carbon, and the amount of methyl is about half of that of methylene. The number of aliphatic carbon atoms in the side chain of molecular structure is about 2-3. For the carbon oxygen bond, the oxygen-containing saturated bonds in the form of ether, phenol alcohol and alkoxy bond are the majority, the number of which is about twice that of the oxygen-containing double bond, and the ratio of carbonyl group to carboxyl group is about 1:1. The three nitrogen atoms in the molecular structure are two pyridines and one pyrrole, and the sulfur content is too low to participate in the molecular unit simulation. The molecular formula of DLT raw coal is C₁₅₂H₁₃₇O₂₅N₃, and its molecular weight is 2403.95. There is little difference between the ¹³C-NMR simulation spectrum and the experimental spectrum in terms of peak position, intensity and trend. Moreover, the error between the structural parameters of the simulated molecules and the spectroscopic characterization parameters is small, which indicates that the molecular unit model of raw coal is in line with the reality. So that the molecular model and the test spectrum can be mapped to each other. It can provide a theoretical basis for the aggregation structure model of raw coal.