采用共混法在聚酰亚胺前驱体中引入Fe3O4纳米粒子, 经高温热解炭化制备了杂化功能炭膜. 采用XRD、TEM和VSM等分析方法对所制备的功能炭膜进行表征, 并探讨了Fe3O4纳米粒子的掺杂量及炭化终温对功能炭膜气体分离性能的影响. 结果表明, Fe3O4纳米粒子在热解炭化过程中发生了物相形态的改变, 并对前驱体起到了催化石墨化的作用, 使功能炭膜具有类石墨片层和乱层炭的两种炭结构形态, 同时具有磁性. 气体渗透实验表明, 掺杂Fe3O4纳米粒子使所制备的功能炭膜具有“分子筛分”的分离特征, 提高了炭膜的气体渗透性能, 特别是对小分子气体H2的渗透性提高了61倍, H2/CO2的分离选择性也明显得到改善. Fe3O4的掺杂量和炭化终温对炭膜的气体分离性能有显著影响. Fe3O4添加量为20wt%的功能炭膜对H2、CO2、O2、N2和CH4等纯气体的渗透系数分别为15476、4385、1565、193和114Barrers [1Barrer =1×10-10cm3(STP)·cm/(cm2·s·cmHg)].
Novel functional carbon membranes for gas separation were designed and prepared by incorporating Fe3O4 nanoparticles into carbon membranes precursor polyimide. The assynthesized membranes were characterized by TEM, XRD and VSM. The effects of Fe3O4 addition and the final pyrolysis temperature on the gas permeability were investigated. The results show that Fe3O4 nanoparticles transformed into other phase morphologies are helpful to form the graphite-like layers during the pyrolysis process, which make the membrane with two types of carbon structure : amorphous carbon and graphite-like layers. All the functional carbon membranes exhibit magnetism. Single gas permeation test results show that the assynthesized membranes exhibit an outstanding molecular sieving capability together with high gas permeability. The gas permeability of H2 is 61 times higher than the pure carbon membrane and the H2/CO2 selectivity is also improved. Fe3O4 addition and the final pyrolysis temperature siginificantly impair the gas permeability. When the Fe3O4 content is 20wt%, the permeabilities of pure gas H2, CO2, O2, N2, CH4 in the functional carbon membrane are 15476, 4385, 1565, 193 and 114 Barrers (1Barrer=1×10-10 cm3 (STP) ·cm/(cm2·s·cmHg)), respecticvely. The final pyrolysis temperature also has a remarkable effect on the gas separation performance.
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