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低阶煤含氧官能团的赋存状态及其脱除研究

Study on the Distribution of O-containing Functional Groups in Low Rank Coals and its Removal Methods

【作者】 周剑林

【导师】 王永刚;

【作者基本信息】 中国矿业大学(北京) , 化学工艺, 2014, 博士

【摘要】 高氧含量是低阶煤的结构特点,影响其吸水等性质。本论文采用化学分析与仪器分析相结合的方法对低阶煤中含氧官能团的赋存状态进行了系统的研究,考察了低温热解、溶剂萃取和溶胀热解三种方法脱除褐煤含氧官能团的效果。研究了含氧官能团的脱除对表面性质的影响,建立了吸水性与表面含氧官能团的数学关系,考察了含氧官能团分解过程中气体逸出规律。结果表明:低阶煤中含氧官能团主要存在形态是酸性含氧官能团,化学分析方法可以有效的定量出78%左右的含氧官能团,结合仪器分析方法对非活性醚键的测定,可以很好的解析褐煤中含氧官能团的赋存形态;褐煤的表面性质与含氧官能团之间关系紧密,最高内在水和含氧官能团以及非氧表面之间的关系符合多元一次线性方程:MHC=2.655[-COOH]+2.912[-OH]+0.209[-OCH3]-3.321Snon-O+1.341;溶剂抽提过程主要是溶剂和含氧官能团之间形成氢键取代了含氧官能团之间的氢键,从而使得酚羟基有所减少;溶胀使得煤的大分子网状结构得到拉伸,在热解过程中容易脱除;动力学关系表明,羧基比羰基的活化能要低,羧基容易分解。

【Abstract】 The high oxygen content and water content in low rank coals have importantinfluence on clean utilization process. This paper empolyed the back-titration andinstrument methods to analyse the distribution of O-containing functional groups inlignite. Using the low-temperature heat treatment, solvent extraction and swellingpyrolysis, the removal behaviour of O-containing functional groups were examinedunder these processes. And the gas evolution was examined in the low-temperatureheat treatment process. The results showed that the oxygen groups in low rank coal ismainly consists of the acidic O-containing functional groups, and the chemicalmethod can effectively quantify out around78%of the O-containing functionalgroups. Combined with the instrument method for the determination of inactive etherbond, the distribution of O-containing functional groups in low rank coal wasobtained with the combination of methods. The significant relation between thesurface properties of lignite and the content of O-containing functional groups wasfound, and the relation between the high moisture holding capacity and O-containingfunctional groups in accord with a multiple linear equation:MHC=2.655[-COOH]+2.912[-OH]+0.209[-OCH3]-3.321Snon-O+1.341. Solvent extractionprocess mainly formed hydrogen bond between solvent and the O-containingfunctional groups which take the place of the hydrogen bonding between oxygencontaining functional groups, especially decline the content of phenolic hydroxylgroups. The O-containing functional groups can be easyly removed in the process ofswelling-pyrolysis as the result of swelling stretched the coal macromolecularnetwork. Dynamics show that activation energy of carboxyl group is lower thancarbonyl during de-oxygenation.

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