神府东胜煤镜质组和惰质组的热化学反应差异

Thermochemical Reaction Representation of Shenfu Dongshen Inertinite and Vitrinite

神府东胜(SD)煤的液化是我国能源多元化战略的重要环节,然而由于我国西部煤种中的显微组分在液化过程中表现出的差异性,传统煤化学知识无法解释神府东胜煤惰质组(SDI)和镜质组(SDV)在液化过程中表现出有别于我国东部煤对应煤种的性质;此外,由于煤结构基础理论上的局限,镜质组和惰质组的热化学差异无法由常规热分析得到解释.为了获取神府东胜煤镜质组和惰质组在液化过程中的差异性,在建立两种煤岩显微组分平均分子模型的基础上,应用分子力学、分子动力学和量子化学对所构建分子结构模型的成键特征及其在热化学环境中的变化做了定性分析,模拟了由不同显微组分生成气、油和焦的过程.结果表明,在煤受热初始裂解释放CO2的过程中,SDI的活性高于SDV,但这一过程对SDV和SDI的大分子骨架结构基本无影响.在进一步的裂解中,根据键级分析发现,SDV的化学键发生断裂的数目远大于SDI,当SDV已基本裂解成小分子化合物时,SDI还需要进一步裂解才能形成小分子化合物,而且SDV和SDI的裂解产物存在着差别,SDV以脂肪烃和单环芳烃为主,SDI以双环芳烃为主.把量子化学计算推测的裂解小分子碎片与热重-质谱(TG-MS)实测结果进行对比,证明了理论上的裂解过程与实验结果相吻合.

Shenfu Dongsheng （SD） coal liquefaction is a critical part for the energy diversification strategy in China. However, because of the unique behavior of Chinese western coal macerals during the liquefaction process, no theory exists that explains the difference between Shenfu Dongsheng inertinite （SDI） and vitrinite （SDV） and Chinese eastern coal macerals. The different thermochemistry of inertinite and vitrinite cannot be explained by only considering the structure of these coals. To investigate the unique behavior of SDI and SDV in the liquefaction process a qualitative analysis of the characteristics and transformation of covalent bonds during pyrolysis of the ＇ average＇ molecular structure of a SD coal was performed using quantum chemistry, molecular mechanics and molecular dynamics. The formation of residual coal, pyrolyzed gases and tar during pyrolysis was simulated. Results showed that the activity of SDI was higher than that of SDV during cracking and initially CO2 was released without destroying the macromolecular structure. From a statistical analysis of bond order in the molecular model, the amount of broken covalent bonds in SDV was found to be far more than that found in SDI after pyrolysis. When SDI cracked further during pyrolysis, the extent of inertinite decomposition eventually reached the same level as that for vitrinite. There was a difference in pyrolysates from SDI and SDV and there were mainly aliphatic hydrocarbons and single-ring aromatic hydrocarbons for SDV while dual-ring aromatic hydrocarbons were dominant after SDI pyrolysis. Molecular fragments obtained from quantum chemical calculations were compared to thermal gravimetric analyzer-mass spectrometry （TG-MS） data and found to agree well.