Macromlecular Aggregation Structure Construction And Molecular Simulation Of Tunlan2 Vitrain

Coking coal resources play an important role in China’s national economy,and are known as"grain"in the iron and steel industry.Although China’s coal resources are abundant,the quality of coking coal resources is relatively scarce.Therefore,how to make use of coking coal more efficiently and improve the conversion rate in the process of coke production is an important research subject.Coking and caking properties of coking coal are closely related to their internal macromolecular structure characteristics,In order to improve coking performance of coking coal,we must have a deep understanding of its molecular composition and internal structure characteristics.The construction of 3D molecular network structure model of coal based on computer-aided molecular design technology is an important way to study the coal structure.（1）In this paper,CS₂-NMP mixed solvent was used to carry out the extraction experiment of No.2 raw coal in Tunlan,and two components of asphaltene and residual coal were obtained.The ratio of atom of each element in the model was determined through Proximate and ultimate tests,the existing form of oxygen element and nitrogen element in the sample was determined by XPS test.According to ¹³CNMR nuclear magnetic resonance test,the X_BP of asphaltene and residue is 0.28 and 0.336 respectively.The types and quantities of aromatic structural units and aliphatic structures in the two components were obtained by the above testing methods.The initial plane structure model of asphaltene and residue is drawn by ACD/Chem Sketch software,using ACD/CNMR Predictor software to adjust the connection way between structural units,we get a molecular model of asphaltene and residue with good agreement with ¹³CNMR experimental spectra.（2）The molecular formula of asphaltene and residue is C₁₈₀H₁₅₉O₆N₃ and C₂₀₁H₁₇₅O₆N₃ respectively.The aromatic structure in the asphaltic model is dominated by naphthalene ring,which contains a small amount of benzene ring,anthracene ring and four-membered aromatic units.The existence form of oxygen atom is phenol hydroxyl,ether oxygen bond and carbonyl group,and contains a pyridine rings and two pyrrole ring.The aliphatic structure exists in the form of naphthenic hydrocarbon,methyl,methylen and so on;The aromatic structure of the residue model is dominated by the phenanthrene ring and the four-membered aromatic units,and contains a small number of benzene ring and naphthalene ring,the number is 1 and 2 respectively,and contain a phenolic hydroxyl group and five carbonyl groups,the number of pyridine rings and pyrrole rings are 2 and 1 respectively,the aliphatic hydrocarbon is mainly naphthenic hydrocarbon,and contain a small amount of methyl side chain.（3）The models were optimized by molecular mechanics and molecular dynamics,the energy-minimun configuration is obtained,Van der waals energy reduce the most,followed by the bond energy,bond torsion energy and bond angle energy has increased,The aromatic structure is bent,and the bridge bond and aliphatic hydrocarbon have been greatly torsional,the stable configuration of the residue is more regular and orderly than asphaltene.The density simulation results show that the density of the residual coal and the asphaltene molecular model is 1.34g/cm³ and 1.25 g/cm³ respectively.（4）The VAMP module is used to calculate the bond length,the bond order and charge distribution in the model,the calculation results show that the C-C bond of aliphatic hydrocarbons is longer,the bond order is smaller,and the negative charges is more,so the chemical activity is higher,in aromatic structure,the C-C bond length is shorter,the bond lorder is larger and the chemical stability is very high,the chemical stability of the aliphatic hydrocarbon linked to the benzene ring is increased.The aliphatic C atoms connected to the O atoms have more negative charges,and the C-C bond length is larger and the reactivity is enhanced.（5）The aromatic layers lamellar are arranged in an ordered degree of residue+residue>residue+asphaltene>asphaltene+asphaltene,inthestable configuration of residue+residue molecular combination,the measured aromatic layer spacing of d₀₀₂ average value were 3.61?、3.79?、4.1?respectively,basically consistent with the test results of XRD.The macromlecular aggregation structure of Tunlan No.2 was constructed by the ratio of residue and asphaltene to 3:2 according to extraction rate in extraction experiment,The Van der waals energy and the bond energy are the most important energy in the macromlecular aggregation configuration,and the hydrogen bond energy is smaller.The internal molecular arrangement of the aggregated structure is compact,and the edge parts is loosely arranged,there are not only parallel arrangement of aromatic layers,but also the vertical,and the vertical configuration is mostly distributed in the edge part,the simulated density of macromlecular aggregation structure model of.Tunlan 2 Vitrinite is 1.32 g/cm³slightly less than that of the residue model.