鄂尔多斯褐煤显微组分结构与其热解特性间的关系

Relationship between the structure of macerals of Ordos lignite and its pyrolysis characteristics

采用浮沉分离法将鄂尔多斯褐煤分离成富镜质组(EL-V)和富惰质组(EL-I),通过工业分析、元素分析、X射线衍射光谱(XRD)、傅里叶变换红外光谱(FTIR)和固体核磁(13C NMR)分析了原煤及显微组分的结构和组成。采用粉-粒流化床和TG-FTIR装置分别考察了原煤及显微组分的热解特性和气态挥发物的逸出规律,进一步构建原煤及显微组分的大分子结构模型,并进行了量子化学计算,认识了化学键的断裂规律。结果表明,富镜质组的挥发分含量较高,含有丰富的烷基侧链,热失重速率最大,表明镜质组的热解反应性较强。与原煤和惰质组相比,富镜质组热解气体含量和焦油含量较高,且热解焦油含有较多的脂肪烃和轻质芳烃(TXE)。富惰质组的H/C比较低,含氧量和芳环缩合程度较高,所得热解焦油中多环芳烃和酚类物质含量较高。此外,通过TG-FTIR重点分析了CO_(2)、CO、CH_(4)、脂肪烃和芳烃的析出行为。根据煤样大分子结构中化学键的断裂和气态挥发物的逸出规律,提出了煤热解过程中可能进行的反应路线。

The Ordos lignite was separated into vitrinite-rich group(EL-V)and inertinite-rich group(EL-I)by floating-sinking separation method,and the structures and compositions of the raw coal and its maceral were analyzed by industrial analysis,elemental analysis,X-ray diffraction spectroscopy(XRD),Fourier transform infrared spectroscopy(FTIR)and solid state nuclear magnetic resonance(13C NMR).The pyrolysis characteristics and the escape pattern of gaseous volatiles of the raw coal and its maceral were investigated by powder-particle fluidized bed and TG-FTIR devices,respectively,to further construct the macromolecular structure models of the raw coal and its maceral and quantum chemical calculations were carried out to recognize the law of chemical bonds breaking.The results showed that the vitrinite-rich group had a higher content of volatiles,contained abundant alkyl side chains,and the largest heat weight loss rate,suggesting that the vitrinite-rich group was more reactive in pyrolysis.Compared with the raw coal and inertinite-rich group,the vitrinite-rich group had higher the pyrolysis gas content and tar contend,and its pyrolysis tar contained more aliphatic hydrocarbons and light aromatic hydrocarbons(TXE).The inertinite-rich group had lower H/C ratio,and higher oxygen content and aromatic ring condensation,and its pyrolysis tar contained higher PAHs and phenolics.In addition,the precipitation behaviors of CO_(2),CO,CH_(4),aliphatic hydrocarbons and aromatic hydrocarbons were analyzed by TG-FTIR.Based on the breaking of chemical bonds in the macromolecular structure of coal samples and the escape pattern of gaseous volatiles,the possible reaction routes carried out in the coal pyrolysis process were proposed.