【作者】 贾伟；

【导师】 凌开成；

【作者基本信息】 太原理工大学 ， 化学工艺， 2010， 硕士

【摘要】 本文选用兖州煤和神府煤为研究煤种,针对煤中小分子化合物对煤高温快速液化的影响进行了较系统的研究。首先用四氢呋喃(THF)对两种煤样进行索式抽提,分析了抽提物的组成及脱除小分子化合物过程对煤结构的影响;通过对脱除小分子化合物前后的煤样进行热重分析,探讨了煤中小分子化合物对煤热解行为的影响;并研究煤中小分子化合物对煤高温快速液化的影响。得到以下主要结论:用THF对兖州煤和神府煤进行抽提,兖州煤的抽提率为14.00%,神府煤的抽提率为10.72%。由红外光谱分析可知,两种煤中小分子化合物中含有脂肪烃、芳烃和脂肪醚等物质;与原煤相比抽余煤在大分子结构上基本没有变化,只是失去了煤网络结构中的小分子化合物。经过抽提后,两种煤孔径分布变大,比表面积变小。脱除小分子化合物前后的煤样进行热重分析显示:抽提掉小分子化合物后的抽余煤的热解速率明显低于原煤,表明煤中小分子化合物对煤的热解行为有较大的影响;两种煤的原煤和抽余煤的DTG曲线表明,抽余煤的最大失重速率的温度没有发生改变,说明抽提后未破坏煤大分子的主体结构。在选定的煤高温快速液化反应条件下,对抽提前后的煤样进行高温快速液化实验,考察小分子化合物对煤高温快速液化的影响:当用四氢呋喃作为溶剂抽提掉煤中的小分子化合物后,在氢气和四氢萘同时存在的条件下,发现抽余煤的总转化率和油产率都高于原煤,这是由于抽提过程使煤的结构疏松,桥键键能降低和煤中孔径变大,使供氢溶剂与煤接触更充分共同的结果;在液化气氛改为N2,溶剂改为萘以后,煤液化时的氢源只能来自煤本身。在这种条件下,原煤和抽余煤的总转化率都有明显下降;在液化气氛为N2,溶剂改为萘的液化条件下,所选的两种煤样原煤的转化率都明显高于抽余煤,表明煤中小分子化合物在液化过程中可以提供活性氢。所选两种煤,兖州煤的转化率明显高于神府煤,这是由于兖州煤所含的氢元素高于神府煤的结果。更多还原

【Abstract】 Taking Yanzhou coal and Shenfu coal as the research object, the effect on quick coal liquefaction at high temperature (QCLHT) of small molecular compound in coal was is systematically investigated. In order to remove small molecular compound in coal, the extraction of Yanzhou coal and Shenfu coal were preformed by using tetrahydrofuran as extraction solvent. Then, the composition of the extracts and the structure of the extracted coal were analyzed. By analyzing the TG and DTG of the raw coal and the extracted coal, the effect on the pyrolysis behavior of small molecular compound in coal was discussed. Finally, the role of small molecular compound in coal for QCLHT was deeply studied. The research mainly includes the following conclusions:The extraction experiments of Yanzhou coal and Shenfu coal shown that the extraction rate of Yanzhou coal is 14.00% and that of Shenfu coal is 10.72%. IR spectra indicates that small molecular compound in coal consists mainly of aliphatic hydrocarbon, aromatic hydrocarbon and aliphatic ether. The extraction does not change the macromolecule structure of coal and only removes small molecular compound in coal. The extraction leads to the decrease of specific surface area of Yanzhou coal and Shenfu coal and the obvious increase of pore diameter of these. TG of the raw coal and the extracted coal illustrates that the weight loss rate of the extracted coal was obviously lower than that of the raw coal. It indicates that small molecular compound in coal has greater influence on the pyrolysis behavior. In addition, DTG of the raw coal and the extracted coal also show that the temperature of the maximum weight loss rate almost does not change. This is because the extraction does not change the macromolecule structure of coal.According to previous research of our research group, the temperature of QCLHT is chose as 490℃, reaction time as 5 minutes, initial cold hydrogen or nitrogen pressure as 7.0 MPa. QCLHT of the raw coal and the extracted coal were preformed. The results show that oil yield and total conversion of the extracted coal are higher than that of the raw coal under hydrogen pressure and 1,2,3,4-tetrahydronaphthalene as hydrogen donor solvent. This is because that the extraction makes coal structure loose, the bond energy of bridge bond reduce and pore size increase. This will be in favor of the contact of hydrogen donor solvent and coal. Under nitrogen pressure and naphthalene as solvent, the hydrogen source of coal liquefaction only comes from coal itself. So, total conversion of the raw coal and the extracted coal decreased significantly. Meanwhile, the extracted coal has significantly lower total conversion than the raw coal under nitrogen pressure naphthalene as solvent. It illustrates that small molecular compound in coal is hydrogen-rich material which will give active hydrogen in the process of QCLHT. In addition, total conversion of Yanzhou coal is significantly higher than that of Shenfu coal. This is because that hydrogen content of Yanzhou coal higher than that of Shenfu coal.更多还原