石墨烯/聚酰亚胺炭膜的制备及其气体分离性能

The preparation and gas separation performance of graphene/polyimide carbon membranes

以9,9-双(4-氨基苯基芴)(FDA)、9,9-双(3-氨基-4-羟基苯基)芴(BisAHPF)、六氟二酐(6FDA)为单体,二维片层氧化石墨烯(GO)纳米炭晶为孔尺度调节剂,采用原位合成法制备GO/聚酰亚胺聚合物,经制膜及高温炭化制备了石墨烯/聚酰亚胺气体分离炭膜。借助于FTIR、XPS、XRD、TGA、氮吸附及气体渗透等表征手段对GO及炭膜的结构与性能进行表征;探讨了GO添加量对石墨烯/聚酰亚胺炭膜的结构与性能的影响。结果表明,原位引入片状GO纳米炭晶,在改善了聚合物膜热稳定性的同时,显著提高了石墨烯/聚酰亚胺炭膜的总孔体积,特别是尺度小于0.6 nm的极微孔孔体积与数量;使石墨烯/聚酰亚胺炭膜在保持高气体渗透性条件下,明显地提高气体分离选择性;增加GO添加量,可进一步提升石墨烯/聚酰亚胺炭膜的气体分离选择性。当GO添加量为0.5 wt.%时,石墨烯/聚酰亚胺炭膜的CO2渗透系数为8760 Barrer,比纯炭膜仅降低了6%;CO2/N2、CO2/CH4分离选择性分别为52、53,分别提高32%、39%。

Graphene/polyimide carbon membranes were prepared by an in-situ polymerization method,in which the 9,9'-bis(4-aminophenyl)fluorine(FDA),9,9'-bis(3-amino-4-hydroxyphenyl)fluorine(BisAHPF)and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride(6FDA)were used as the monomers and graphene oxide(GO)as the pore size regulator.FTIR,XPS,XRD,TGA,N2 adsorption and gas permeability tests were used to characterize the microstructures and properties of GO and the graphene/polyimide carbon membranes.The effect of the GO content on the microstructure and gas separation performance of the carbon membranes were investigated.Results show that the incorporation of GO into the polyimide significantly increases the total pore volume of the carbon membranes,especially the volume of ultramicropores smaller than 0.6 nm,as well as improving the thermal stability of the membranes.Compared with the polyimide carbon membrane without GO,the graphene/polyimide carbon membranes have an obvious increase in the CO 2 selectivity with a high gas permeability and the selectivity increased with GO loading.The gas permeability of pure CO 2 for the graphene/polyimide carbon membrane with a GO loading of 0.5 wt.%is 8760 Barrer and its CO 2 selectivities against N 2(CO 2/N 2)and CH 4(CO 2/CH 4)are 52 and 53,respectively,which are 32%,and 39%higher than that of the pure carbon membrane.