西北侏罗纪煤镜质组与惰质组在热解和直接液化过程中的相互作用机制

The direct coal liquefaction is an important means for coal's cleaning, conversion, and high-efficient ultilzation. The maceral composition of coal is one of the significant factors affecting coal's conversions. Previous studies have suggested that there are interactions between vitrinite and inertinite in coal direct liquefaction and pyrolysis, but the mechanism of those interactions is not clear.We will take the Shendong coal and Wucaiwan coal as the objects of this research，isopycnic density gradient centrifugalization will be applied to detach vitrinite and inertinite. Two different systems are designed. By using the techniques of structural analysis and maceral analysis, we intend to determine the chemical structure, the stacking structure，and the coal petrographic properties of two systems in pyrolysis and direct liquefaction, and compare their differences. Based on the theoretical analysis of coal chemistry and coal petrology combining with molecular simulation methods, we are trying to elucidate the mechanism behind a variety of interactions between vitrinite and inertinite on the coal macromolecular structure, the aggregation structure, and the microscopic coal petrology level from the perspective of micro-mesoscopic-macro. This research will deepen the essential understanding of coal pyrolysis and direct liquefaction, and will also provide a theoretical basis for processing optimization and the improvement of conversion in coal direct liquefaction.

煤直接液化是煤炭清洁转化和高效利用的一种重要手段，煤岩显微组成是影响煤液化转化率的重要因素之一。已有研究显示，煤中镜质组与惰质组在直接液化和热解过程中存在相互作用，但是相互作用的机制尚不清楚。本项目以我国西北侏罗纪神东煤、新疆五彩湾煤为研究对象，采用等密度梯度离心分离技术获得镜质组、惰质组，在系统分析和表征显微组分的基础上，设计建立两种不同体系，利用结构分析及显微煤岩分析技术，测定两种体系在热解及直接液化中化学结构、堆垛结构和煤岩特征并比较其差异性，通过煤化学与煤岩学理论分析，结合分子模拟方法，从煤大分子水平、聚集态和显微煤岩多层次考察镜质组与惰质组的相互作用，阐明镜质组与惰质组之间在微观－介观－宏观上的相互作用机制。本项目将深化对煤热解机理和直接液化机理的本质认识，为煤直接液化煤种的选择、工艺过程优化及液化转化率的提高提供理论依据

本项目主要以五彩湾煤和补连塔煤的镜质组与惰质组为研究对象，以揭示热解和直接液化中镜质组与惰质组存在何种化学作用方式为研究目标，进行了大量实验和深入的理论分析。研究表明，两种煤的惰质组与镜质组之间在热解过程中相互作用的方式是类似的：在低温热解区间以镜质组与惰质组的烷基自由基转移为主，中温热解区间的反应较为复杂，镜质组与惰质组之间发生缩聚反应、缩合反应、芳构化反应、芳香氢化反应等，高温热解区间主要表现为镜质组与惰质组之间的多环缩合反应，只是各反应所在温度区间并不完全相同；比较两种煤的直接液化，镜质组与惰质组的相互作用的强度有所不同，但是相互作用的方式类似。相互作用的方式可以归纳为：a.镜质组产生较多的烷基自由基，其中部分自由基与惰质组大分子自由基(或芳香稠环碎片）结合，即发生烷基自由基转移反应；b.镜质组分产生的烷基自由基与惰质组芳香碎片发生取代反应；c.镜质组碎片与惰质组碎片之间发生缩聚缩合反应使芳香体系增大，且随温度升高，缩聚缩合反应加剧，残渣的石墨化度增加。上述镜质组与惰质组的相互作用方式为煤的热解和直接液化机理提供了新的认识。