【作者】 彭耀丽；

【导师】 魏贤勇；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2009， 博士

【摘要】 因受本身特性的制约,褐煤迄今未得到有效利用。本课题选用我国内蒙古地区锡林浩特褐煤(XLHTL)和霍林郭勒褐煤(HLGLL)为研究对象,以丙酮作为脱水介质研究了褐煤的脱水;对褐煤进行了分析萃取,研究了褐煤中的小分子组成;在超临界条件下研究了褐煤的醇解及其反应影响因素,并对反应混合物进行了分离和分析;初步探讨了在超临界条件下甲醇自身发生的化学反应和反应机理;选取褐煤相关模型化合物研究了褐煤醇解反应的机理。以丙酮为介质,通过萃取可使XLHTL的水分由20.41%降低到3.5%左右,这样的水分完全可以满足褐煤加工利用的要求;同时,丙酮可萃取出XLHTL中部分小分子。依次用二硫化碳(CS2)、正己烷、苯、乙醚、丙酮、甲醇和四氢呋喃(THF)萃取了XLHTL和HLGLL,各级萃取率均较低,GS/MS可检测化合物少。在超临界醇-碱体系下,对XLHTL和HLGLL进行醇解,醇解得到的反应混合物用正己烷、乙醚、甲醇和THF进行分级萃取,醇解后产物总收率可达80%以上;用GC/MS分析了反应混合物的组成,检测出的化合物远比褐煤分级萃取物中检测出的多,特别是检测出了大量酚类化合物。研究了反应温度、反应时间、醇煤比、碱煤比和不同种类醇(甲醇、乙醇和异丙醇)等因素对褐煤醇解的影响,结果表明:在醇煤比10/1、碱煤比0.8/1、反应温度300 oC、反应时间2 h条件下,褐煤醇解基本彻底,其收率可达90%以上。相同条件下,研究了神府煤和童亭煤的醇解,二者的收率均低于XLHTL和HLGLL的收率。对XLHTL和HLGLL醇解得到的反应混合物进行了族组分的分离,得到了水溶性化合物、烷烃、芳烃和含杂原子化合物等族组分,用GC/MS检测了族组分的组成,分析了褐煤中烷烃、芳烃的组成和杂原子的赋存状态。在XLHTL的反应混合物中得到一个碳酸酯馏分和一个脂肪酸酯纯品。制备并表征了固体碱催化剂CaO、K2CO3/γ-Al2O3、K2CO3/γ-Al2O3-NaOH和KF/γ-Al2O3,用其催化褐煤醇解,收率分别为88.2%,64.4%,73.9%和78.3%;并对反应混合物进行了分离和分析,与前述醇-碱体系下反应混合物的组成相似。以CaO为催化剂,研究了超临界条件下甲醇自身发生的化学反应,分析了气体和液体产物的组成,初步探讨了反应机理。以二苯醚、苯基苄基醚(BPE)、苯甲醚、乙氧基萘、苯酚、间苯二酚、苯和蒽作为模型化合物,研究了褐煤超临界醇解的机理,结果表明醚键断裂是主要反应,伴随有芳环的烷基化、加氢和甲氧基化等反应。更多还原

【Abstract】 Because of limitation of their characteristic, lignites have not been effectively utilized. Xilinhaote lignite (XLHTL) and Huolinguole lignite (HLGLL) were chose in this study. The research was an approach to the dehydration of lignite taken the acetone as a dehydrated medium. The alcoholysis reaction under supercritical condition were investigated, and isolated and analyzed the reaction mixture. Based on the above, some related model compounds were chose to react in the same conditions in order to deduce the mechanism of reaction. The reactions of methanol itself in supercritical condition and reaction mechanism were studied preliminarily.Lignite can be dehydrated effectively by extraction with acetone. The moisture content of XLHTL can be reduced from 20.4% to 3.5%, which meets to the needs to lignite processing and utilization. Meanwhile, some small fractions are extracted from the lignite with acetone.The XLHTL and HLGLL were extracted with carbon disulfide (CS2), n-hexane, benzene, ether, acetone, methanol and tetrahydrofuran (THF) sequentially. The results showed that extract yield of each stage are low which is related to metamorphic grade of lignite since its free small molecules are few whereas the reticular structures of macromolecular were compact. The reaction mixtures from XLHTL and HLGLL over alcoholysis reaction under supercritical condition were extracted with n-hexane, ether, methanol and THF sequentially. The extract yield went up sharply with a total extractability of above 80%. The components of the reaction mixture were analyzed by GC/MS and the detectable compounds were far more than those of extractions of each stage from raw coal, especially, many phenols were detected. The study took some factors which can effected the reaction into consideration, such as reaction temperature, reaction time, the ratio of alcohol and coal, the ratio of alkali and coal and different kinds of higher alcohol. Under the same conditions, the study on Shenfu coal and Tongting coal alcoholysis reaction were carried, the yieds were lower than those of XLHTL and HLGLL.The reaction mixtures were separated by column chromatography so as to get detail information about the components, obtained water-soluble compounds, alkanes, arenes and heteroatomic containing compounds and so on. The separation products were analyzed by GC/MS, The occurrence of alkanes, arenes and heteroatomic containing compounds were discussed . A series of carbonic esters and one pure component which was identified to be an fatty acid ester.The solid base catalysts CaO, K2CO3/γ-Al2O3, K2CO3/γ-Al2O3-NaOH and KF/γ-Al2O3 were prepared, characterized and applied in the lignite coal alcoholysis reactions, the yields were 88.2%,64.4%,73.9%和78.3%. The reaction mixture’s component were same as those from methanol-alkali system.The reactions of methanol itself over CaO-catalyzed in supercritical condition were studied and analyzed the components of the products to deduce preliminarily the reaction mechanism. Diphenyl ether, benzyl phenyl ether (BPE), anisole, 2-ethoxynaphthalene, phenol, Resorcinol, benzene and anthracene as the model compounds were used to study the mechanism of reaction. The results show that the main reaction form is the fracture of ether linkage followed by hydrogenation, alkylation and methoxylation of aromatic ring.更多还原