摘要
以2,2-双[4-(4-氨基苯氧基苯基)]六氟丙烷(BDAF)为二胺单体,均苯四酸二酐(PMDA)为二酐单体,采用两步法制备了BDAF-PMDA型聚酰亚胺,进一步高温热解制备炭膜.采用红外、热重、X射线衍射分析其结构变化,并测试炭膜对纯组分及混合气体的渗透性能和分离选择性.结果表明,BDAF-PMDA型炭膜具有较高的气体渗透性,在CO2/H2体系中可优先渗透CO2.提高炭化温度,炭膜孔径减小,气体的渗透性能降低,选择性提高,并使得BDAF-PMDA型炭膜的分离机理由表面扩散为主逐渐变为表面扩散和分子筛分共同控制.
The BDAF-PMDA polyimide which synthesized with the monomer of pyromellitic acid dianhydride and 2,2-Bis [4-（4-aminophenoxy）phenyl]-hexafluoropropanane by two step method was used to prepare the carbon membrane by the pyrolysis at the high temperature. The changes of chemical structure of BDAF-PMDA polyimide during the pyrolysis and gas separation properties of derived carbon membranes were characterized by FTIR, TG, XRD, and gas permeation tests of pure and mixed gas. Results indicate that the carbon membrane prepared from the BDAF-PMDA polyimide precursor exhibits the higher gas permeability for small gas molecules, especially for CO2 which can be permeated faster than Hz in the mixture of CO2/H2. With the increase of carbonization temperature, the pore size of carbon membrane decreases. As a result, the gas permeability of the derived carbon membrane is reduced and the gas selectivity is enhanced. And the separation mechanism of BDAF-PMDA carbon membrane is changed from the surface diffusion mechanism into the coexistence of surface diffusion and molecular sieving mechanism.
出处
《膜科学与技术》
CAS
CSCD
北大核心
2012年第3期6-10,共5页
Membrane Science and Technology
基金
国家自然科学基金面上与重点项目(20776024
20976021
20836006)
国家"863"项目(2009AA03Z215)
天津工业大学中空纤维膜材料与膜过程省部共建国家重点实验室培育基地开放基金
