BPDA-ODA型聚酰亚胺基沸石杂化炭膜的制备及气体分离性能

摘要

Hybrid carbon membranes are first prepared using BPDA-ODA type polyimide and zeolites as precursors and additives,respectively.The thermal stability of the precursor was measured by thermogravimetric analysis.The microstructure,morphology and gas separation performance of resultant carbon membranes were characterized by X-ray diffraction,scanning electronic microscopy and gas permeation technique,respectively.The effects of zeolite types (ZSM-5 and 5A),zeolite dosage,carbonization temperature,and permeation-temperature and permeation-pressure were investigated on thegas separation performance of hybrid carbon membranes.The results have shown that the permeationmechanism for the four gases,H2,CO2,O2 and N2,is molecular sieving through the hybrid carbonmembranes.When the hybrid carbon membranes are prepared at the carbonization temperature of 650 ℃,both of their permeability and selectivity slightly reduce.In comparison,5A is more favorable than ZSM-5to be used as additives with the aspect to increase separation performance of resultant carbon membranes.With increasing the permeation pressure,both the permeability and selectivity increase.As thecarbonization temperature goes up from 650 ℃ to 750 ℃,the permeability of hybrid carbon membranesreduces.%以BPDA-ODA型聚酰亚胺为前躯体,沸石为掺杂剂,通过成膜和炭化等过程制备了杂化炭膜.分别采用热失重、X射线衍射、扫描电子显微镜及渗透技术研究了前躯体热稳定性,炭膜微观结构、形貌及气体分离性能.考察了ZSM-5与5A两种沸石含量、炭化温度、渗透温度及渗透压力等因素对炭膜气体分离性能的影响.结果表明:H2、CO2、O2和N24种气体主要以分子筛分机理渗透通过炭膜,实现选择性分离.在650℃炭化温度下得到杂化炭膜随沸石含量提高,气体渗透性与选择性均略降低；5A杂化炭膜的渗透性与选择性都显著高于ZSM-5杂化炭膜；随渗透压力提高,杂化炭膜的气体渗透性与选择性升高.当炭化温度从650℃升高到750℃时,杂化炭膜的渗透性降低.