Construction And Analysis Of The Bagang Rich Coal Molecular Structure

Coal is the raw material of metallurgical coke.The quality of coal directly affect the properties of coke.However,due to the lack of clearly understanding of coal properties,the correlation between coal properties and coke quality is relatively fuzzy.At present,the properties of coal can not be well evaluated by macroscopic property analysis,microscopic component analysis at optical level,and transmission electron microscopy at nano level.Therefore,it is necessary to study the molecular structure of coal.It provides basic theories for the correct understanding of coal properties.Fat coal plays an important role in coal blending and coking.So this paper chooses Bagang fat coal（BGM）as research object,the basic properties of BGM（elemental analysis and industrial analysis）were detected,and ¹³C-NMR,FTIR,XRD and other tests were performed on the coal samples.Then the corresponding structural parameters are calculated by means of the peak fitting combination of the experimental results one by one.Based on the experimental results and the calculated structural parameters,the molecular structure unit was constructed,and Chemdraw software was used to predict ¹³C-NMR to modify the structure.The results were in good agreement with the experimental results.Finally,further calculation is carried out to determine the accuracy of the structure.The results of the paper show that the existence forms of each element in the structural unit after continuous modification and optimization:the existence forms of carbon elements are two benzene rings,one naphthalene ring,two pyrene rings,one pyridine ring and one pyrrole ring;Oxygen element exists in the form of one hydroxyl group and 1 bridged oxygen.The nitrogen element exists in pyridine ring.Sulfur exists in the form of thiophene groups.Chemdraw and Material Studio were used to calculate and modify the carbon shift with high fitting degree to the experimental.So it is the macromolecular structure unit of coal.The structural elements are calculated by first principle and molecular dynamics.After optimization,the energy changes a lot,and the structure torsion produces laminates,which tend to compact.The final model is dominated by van der waal energy.The distribution analysis shows that aromatic carbon structure is relatively stable,oxygen bridge,carbon connected with oxygen and nitrogen,aliphatic carbon,branched chain carbon and so on are relatively active,which easy to break bonds in the pyrolysis process.The frequency calculation results show that the infrared spectra fitted by the vibration intensity of each atom correspond well with the experimental spectra,which verifies the accuracy of the structure unit.By adding boundary conditions to the BGM structural unit,the density of the structural unit was calculated.the system density was 1.07 g/cm³.The macromolecular structure of coal matrix was constructed according to the elements composition and optimized,the structure parameters of microcrystalline in the macromolecular had a good correspondence with the XRD experimental results.Through the above experimental analysis and simulation calculation,the understanding of BGM coal is further deepened,which is conducive to the further use of the coal.