摘要
在２００℃至４００℃高温和还原条件下分别对仙掌藻和乳节藻两种钙质藻类进行热模拟降解实验，分离获得气态和液态烃类化合物。随着热解温度升高，两种钙藻产烃气量明显上升，其中甲烷与乙烷气的增加最多，同时两种钙藻产出的乙烷与乙烯比值都有规律地增加，但仙掌藻产烃气量高于乳节藻。这表明钙质藻类可能是天然气的一种重要母质来源。虽然这两种钙藻随温度增加热解产出的可溶有机质及族组分的变化规律不明显，但它们的正烷烃分布特征具有相类似的变化。未经热解时它们都以Ｃ１７为主峰的低碳数正烷烃占优势；当热解温度从２００℃增加到４００℃时，它们都又表现出以Ｃ２５或Ｃ２３为主峰的较高碳数正烷烃占优势的分布特征。这与富含钙藻化石的沉积岩样品中正烷烃的分布特征相一致，说明Ｃ２５或Ｃ２３为主峰的较高碳数正烷烃占优势的分布特征可能是钙藻热解有机质的一种判识标志．
Gaseous and liquid hydrocarbons were isolated from two kinds of calcareous algae,Halimeda macroloba and Galaxaura oblongata,which were thermally degraded under high temperature conditions of 200-400℃. Gas chromatography analysis showed that the amounts of gaseous hydrocarbons from two calcareous algae, especially methane and ethane, increase markedly with rise in temperature,and the ethane to ethylene ratio increases regularly with rise in temperature. The production rate of gaseous hydrocarbons from Halimeda is higher than that from Galaxaura. All these indicate that calcareous algae can be an important source material for natural gases. The distribution of normal alkanes of liquid hydrocarbons from the two calcareous algae under study shows a similar pattern of changes with rise in temperature. Before thermal degradation. they are characterized by the predominance of short carbonchain normal alkanes with C17 as the main peak. However,after degradation at 200-400℃,the hydrocarbons from both calcareous algae are predominated by higher molecular weight normal alkanes with maximum at C25 or C23. The predominance of C25 normal alkane had been reported from sedimentary rocks rich in fossil calcareous algae, implying that the predominance of C25 normal alkane may be a marker of organic matter from these calcareous algae.
出处
《微体古生物学报》
CSCD
北大核心
1994年第1期109-114,共6页
Acta Micropalaeontologica Sinica
基金
国家自然科学基金
现代古生物学和地层学开放研究实验室资助课题.
关键词
钙藻
热解
气态和液态烃
calcareous algae, thermal degradation, gaseous and liquid hydrocarbons
