全煤阶煤的正己烷分次萃取及萃取物分析

FRACTIONAL EXTRACTION WITH N-HEXANE TO ALL-RANK COAL AND ANALYSIS OF EXTRACTS

为探索煤中小分子化合物在整个煤阶中的赋存方式及溶出规律,采用正己烷溶剂对年轻褐煤至无烟煤八种煤样进行分次萃取,分析了一定时间段内各煤样萃取率的变化规律,并对各次萃取物进行GC分析.结果表明,煤中小分子化合物的三种赋存形态即游离态、微孔嵌入态及网络嵌入态,在整个煤阶中具有普遍规律性;不同煤阶煤的累积萃取率与累计萃取时间均服从对数函数关系;分次萃取率及总萃取率与碳含量均呈现"椅子"形曲线关系;正己烷可溶小分子化合物中的Ⅱ型分子最容易析出,Ⅰ型分子次之,Ⅲ型分子最难溶出,且Ⅰ型分子仅在烟煤中才有显现;煤的变质过程基本符合煤的三大变质反应过程即芳构化反应过程、裂解碎化加氢稳定反应过程和缩合反应过程的观点.

To investigate the exiting state and solubilization characteristics of small molecule compounds in the entire coal rank, eight coals ranged from young lignite to anthracite were extracted with n-hexane and sampled in batches. The change law of extraction rate in a certain period was discussed, and the extracts were analyzed with GC. The results show that the three existing forms of small molecules, free state, micropore-inbuilt state and network-inbuilt state, consist in every coal and show universal rules for the entire coal rank. The relationship between the cumulative extraction rate and cumulative extraction time of coals in different rank are subject to logarithmic function. The curve of fractionated extraction rate or the total extraction rate to carbon content represent the ＂chair＂ shape. The Ⅱ-type molecules in the n-hexane-soluble small molecule compounds are most likely to dissolve, followed by Ⅰ-type molecular, and then Ⅲ- type, especially the Ⅰ -type molecular just appear in the bituminous coal. The metamorphic reaction process basically submit to three stages, which is the aromatization process, splitting hydro- genation and stability reaction process, and the condensation reaction process.