西北侏罗纪低成熟煤中镜质组热解产物特征及地质意义

Molecular characterization of flash pyrolysates of Jurassic vitrinites in Northwest China and its geological implications

镜质组是腐殖煤中最主要的显微组分,其结构极为复杂。采用单一的实验手段,很难对镜质组结构进行深入研究。采用低温热解、高温热解及TMAH在线甲基化热解3种瞬时热解方法,对镜质组结构中吸附烃、与大分子相连的支链基团中非极性及极性组分分别进行研究。实验结果表明,吸附烃特征决定于镜质组类型及成熟度两种因素。均质镜质体吸附烃以芳烃为主,而基质镜质体吸附烃以正构脂肪烃为主。热解产物中,芳烃所占比例随基质镜质体成熟度的增加而变大;基质镜质体高温热解主要产物为正构脂肪烃,其次为芳烃和酚类,而均质镜质体高温热解主要产物为酚类,其次为芳烃,脂肪烃所占比例较小。TMAH甲基化研究表明,镜质组结构中含有丰富的脂肪酸,而脂肪酸有可能是煤成油的主要母质来源之一。镜质组不同条件下的热解产物特征说明,不同镜质组具有明显的结构差异,并对其生烃特征具有重要影响。

Vitrinite, the main maceral of humic coals, has complicated structure. And it＇s not easy to study the vitrinite structure using single method. So different kind of pyrolysis methods have been used for the purpose to reveal the structure of vitrinites. Result shows that the composition of adsorbed hydrocarbon is controlled by the type and maturity of vitrinites. Pyrolysates of telocollinite are mainly composed of aromatics while that of desmo- collinite is mainly composed of aliphatics. And it shows that the ratio of aromatics in pyrolysate raises with maturity. Experiment of flash pyrolysis of vitrinites conducted at 600 ℃ shows similar result. TMAH methylation pyrolysis of vitrinites shows that there are abundant fatty acids in the structure of vitrinites. And the fatty acid may be the precursor of coal-formed hydrocarbon.