【作者】 邱英华；

【导师】 王同华；

【作者基本信息】 大连理工大学 ， 化学工艺， 2005， 硕士

【摘要】 本论文首先综述了膜分离的发展状况,并着重从炭膜的分类、制备、分离机理、结构表征、应用及未来发展前景展望等六方面对炭膜进行了系统的介绍。之后,详细阐述了以聚丙烯腈为前驱体,以煤基炭管为支撑体,采用浸渍涂膜法成膜后经干燥、预氧化、炭化制备出聚丙烯腈基复合炭膜的过程。考察了成膜条件(涂膜液浓度,浸渍条件,干燥条件以及涂膜次数等)、预氧化条件、炭化条件以及添加剂对聚丙烯腈基炭膜性能的影响。同时,采用了SEM、TG、FTIR、XRD及Raman等分析手段对PAN炭膜在氩气氛围下形成过程中的复合效果、热解机理、热解反应动力学、炭结构和孔结构的形成进行了研究,并与真空氛围进行了相应的比较。 实验结果表明:通过调整实验参数能够制备出复合效果较好,膜层厚度均一,孔径分布均匀,表面光滑无缺陷的聚丙烯腈基复合炭膜。聚丙烯腈炭膜形成过程中主要经历乐了三个阶段:脱水和溶剂挥发阶段;分解阶段(发生了环化、交联、链断裂反应);深化交联阶段。在分解阶段其热解反应是分段进行的,各阶段有着各不相同的活化能和频率因子,其反应均为一级反应。随热解温度的升高,炭膜微晶结构在a轴方向得到发展,层间距不断增大,由线型有序结构转变为乱层石墨结构。通过比较聚丙烯腈在氩气和真空氛围下的热解,可以得出聚丙烯腈在真空氛围中的热解反应活化能低于氩气氛围中的活化能,说明真空氛围能够降低热解反应的温度,加速反应的进行。而且真空氛围下制备的聚丙烯腈炭膜微晶有序度高,结构缺陷和孔隙均小于氩气氛围下制备的炭膜。根据聚丙烯炭膜孔结构形成模型,可以推断出真空和惰性氛围中制备的炭膜的孔隙尺寸分别为0.71×1.23×1.28nm和0.72×1.48×1.56nm。更多还原

【Abstract】 The latest development of membrane separation, especially carbon membranes on the category, preparation, separation mechanism, application and future direction are presented in the thesis. A carbon-carbon composite membrane is prepared by pyrolysing polyacrylonitrile membrane using dip-coating method on tublar carbon support derived from coal. The experiments are carried out to investigate the effects of membrane formation conditions such as concentration of PAN solution, dip-coating parameters, drying parameters and coating numbers, preoxidation conditions, carbonization conditions and additives on the properties of PAN-based carbon membranes. The pyrolysis mechanism, the reaction kinetics, the formation of carbon and pore structure of PAN-based carbon-carbon composite membrane formed in Ar and vacuum are studied by SEM, TG, FTIR , XRD and Raman analysis and their differences are compared.The results indicate that a thin, crack-free PAN-based composite carbon membrane can be prepared by optimizing the experimental parameters. There are three stages during pyrolysis of PAN membrane. In the early stage, dehydration and solvent volatilization of PAN membrane are obvious. Three kinds of reactions such as cyclization, crosslinkling and cleavage of liner PAN chain occur in second stage. In the final stage, the cross-link degree of molecular chain increases and transforms into ladder-shaped reticular structure. The three reactions occurred in the second stage all follow the first order reaction and the corresponding parameters such as activation energy and pre-exponertial factor are different. With the increase of pyrolysis temperature, the graphitic layer planes gradually grow along a axis direction and the doo2 values increase. It indicates that PAN transits from the linear molecular structure to the turbostratic graphitic structure. By comparing the pyrolysis process of PAN in Ar with that in vacuum, it is found that the thermal activation energy in vacuum is lower than that in Ar, which indicates that the vacuum atmosphere favors the degradation reaction. Furthermore, the carbon membrane prepared in vacuum has higher order degree, lower structure defect and smaller pore than that prepared in vacuum. According to pore model, the theoretical pore sizes formed in vacuum and Ar are approximately 0.71×1.23×1.28 nm and 0.72×1.48×1.56nm, respectively.更多还原