低煤级煤生烃与结构演化的耦合机理研究

Study of Coupling Mechanism between Hydrocarbon Generation and Structure Evolution in Low Rank Coal

应用傅里叶变换红外光谱(FTIR)、热解气相色谱(GC)对低煤级煤生烃过程中有机质结构演化进行表征,剖析了人工热演化过程中气态烃产率,解析了煤结构官能团的变化规律,揭示了低煤级煤生烃与结构演化的耦合机理。结果表明:煤热模拟产物主要为气态烃C1-5,甲烷生成瞬时产率包含四个峰值,低煤级煤化学结构中含氧官能团和烷基侧链随煤化程度的增高以不同的速度发生脱落,随煤级的增加,其芳构化程度增大。分别对煤结构中的脂肪烃甲基、C-O基、芳香烃芳核C-C和烷烃结构上甲基、亚甲基进行表征。存在420℃温度转折点,之前吸收峰强度逐渐减小,之后又略有增大,揭示了低煤级煤三个主要结构演化阶段煤化作用机理,提出了低煤级煤生烃结构演化模式图。

The structure evolution in the process of low rank coal hydrocarbon generation was studied using Fourier transform infrared spectroscopy and gas chromatography.Gaseous hydrocarbon yield and change law of functional groups were obtained.The results show that： the coal pyrolysis products are mainly gaseous hydrocarbon C1-5.Methane generation instantaneous yield curve contains four peak of hydrocarbon pyrolysis.Oxygen-containing functional group and alkyl side chain of low rank coal chemical structure reduced while aromatization degree increased along with coal rank.The characteristic absorption peak of coal structure of aliphatic hydrocarbons,aromatic hydrocarbon,methyl CO base CC of alkanes and aromatic structure of methyl and methylene were characterized by 2 950,2 920,2 860,1 730,1 705,1 600 and 1 380~1 460 cm-1 selected in FTIR spectra.Temperature 420 ℃ is the turning point,before the absorption peak intensity gradually decreases,and then increases slightly.Three major structural evolution stages of coalification mechanism were revealed.Finally,the low rank coal hydrocarbon structure evolution pattern was put forward.