Structure Analysis And Molecular Model Construction Of Coal And Its Intermediate Products Derived From Coal Hydroliquefaction

Based on NaoMaoHu(NMH)Xingjiang lignite coal hydrogenation liquefaction reaction experiment,and the Nuclear Magnetic Resonance(NMR),Electron Paramagnetic Resonance(EPR)and X-ray Photoelectron Spectroscopy(XPS)analysis methods are applied to analysis intermediate carbon structure and free radicals concentration in coal hydrogenation liquefaction.It is a critical pathway to study the influence that the liquefaction reaction product structure change with temperature,and realizing the construction model of coal and its intermediate product from the view of molecular structure.Firstly,a series of model compounds are investigated to calibration and analyses Nuclear Overhauser effect(NOE)in the solid-state nuclear magnetic resonance(NMR).And establish nonlinear regression equations for aliphatic carbon and aromatic carbon.Furthermore,9,10-dimethyl anthracene model compounds was verified for the accurate equations,the results shows that 9,10dimethyl anthracene carbon structure parameter error were within 10%of measured value with the theoretical value.Ultimately,it has been established analytical methods to eliminate NOE for the quantitative analysis of solid-state 13C NMR which laid the foundation and safeguard for carbon structure analysis.Moreover,hydrogen spectrum and carbon spectrum(1H/13C NMR)are applied in analyze the intermediate structure transformation with different temperature in coal liquefaction,which is a modernization approaching to reveal the liquefaction reaction behavior from the perspective of molecular research.Between the 320℃to 450℃,coal liquefied oil has the highest aliphatic hydrocarbon at 390℃,and the content of aliphatic hydrogen and carbon has reach to 29.51%and 42.26%respectively.However,aromatic carbon contents in asphaltene increase with the temperature rises,and the content has reach to 87.27%in 450℃ in solid state NMR.Otherwise,Aliphatic and aromatic carbon are complementary relationship.The intermediate carbon structural parameters change with different temperature on hydrogenation liquefaction,and its distribution and variation closely relate to the liquefaction reaction performance.In addition,the variation of carbon structural parameters have consistent correlation with liquefaction reaction process.The concentration of free radicals change with different temperature in the liquefaction for coal liquefied oil and asphaltene investigated by EPR.It is found that the concentration of free radicals in liquefied oil increased with the rise of temperature,and the liquefied asphaltene upgrade firstly than descending latter with the rise of temperature.The liquefied oil and asphaltene variation of free radicals are positively correlated with their own production rate relations.It is means that the variation of free radicals concentration consistent with the yield of intermediate liquid production distribution and reaction behavior,which laid a further foundation for studying liquefaction mechanism.Finally,according to the results of the 13C NMR,XPS,FTIR and element analysis,the molecular model of NMH raw coal and liquefied asphaltene was constructed by ChemDraw.The results show a precisely structure parameters that NMH is given priority to with single and double aromatic rings,asphaltene contains 2-4 condensation aromatic rings.It indicated that the distribution of elements and molecular formula are consistent with ultimate analysis results by ChemDraw simulation analysis for NMH raw coal and liquefied asphaltene.And then,an complex response of molecular structure process that NMH coal molecules generated asphaltene has been simulated and deduced in briefly,which provides a theoretical basis for the study of the mechanism of coal liquefaction.