非对称中空纤维负载氧化石墨烯膜的制备及气体分离性能研究

发布时间：2018-08-17 11:40

【摘要】：随着分离技术的发展,氢气的纯化日益受到人们的关注,本课题拟基于高长径比的陶瓷中空纤维负载氧化石墨烯膜以提高膜的强度和分离性能。为此,采用高强度的YSZ(8%Y_2O_3掺杂的Zr O_2)基于相转化法制备多孔中空纤维陶瓷膜,通过真空辅助的抽滤法负载超薄氧化石墨烯(Graphene oxide,GO),形成GO/YSZ复合膜,GO膜厚度大约为230nm。GO片层之间的2D纳米孔道及表面缺陷使此种膜具有了分子筛功能,20 ℃时H_2和N_2两种单组分气体的渗透能力分别为4.4×10-8和5.8×10-10mol·m~(-2)·s~(-1)·Pa-1,理想分离因数高达76,而H_2/N_2混合气的分离因数为68,这是由于组分之间相互碰撞阻碍所造成的。随着工作温度的升高,石墨烯膜层间距加大,使N_2的渗透速率增幅超过了H_2,因此H_2/N_2分离系数在100℃仅为37,但此种膜能稳定运转240h,性能无衰减。基于分子筛机理,模拟了H_2/N_2混合气分离过程中,氢气的分压、渗透量在管内的分布,结果表明,微管前端(微管进气口端),H_2渗透量和氢分压急剧增加,约5cm处变化甚微,表明微管的有效渗透区域约为5cm左右;适当增加原料气压力或降低渗透侧压力,都能增压氢气渗透量。为降低制备成本和增加GO膜与基底的结合力,又选取了含Si的Al_2O_3中空纤维膜作基底,制备GO/Si-Al_2O_3复合膜(Si掺杂Al_2O_3负载GO膜),考察了Si含量对H_2/N_2混合气体分离性能的影响。结果表明,GO/Si-Al_2O_3复合膜也具有较优异的气体选择渗透性能,20 ℃时含Si量为2wt.%的复合膜,H_2/N_2的理想选择性为50,单气体组分H_2和N_2的渗透量分别为1.2×10-7和2.4×10-8 mol·m~(-2)·s~(-1)·Pa-1,在长达240h的运转过程中无膜剥离现象出现。
[Abstract]:With the development of separation technology, more and more attention has been paid to the purification of hydrogen. In order to improve the strength and separation performance of graphene oxide membrane based on high aspect ratio ceramic hollow fiber. Therefore, porous hollow fiber ceramic membranes were prepared by high strength YSZ (8%Y_2O_3 doped Zr O 2) based on phase inversion method. The ultrathin graphene oxide (Graphene oxide go) was loaded by vacuum assisted filtration method, and the thickness of GO/YSZ composite membrane was about 2D nano-pore between 230nm.GO layers and surface defects. The membrane had two kinds of molecular sieve function, H2 and N2 at 20 鈩，

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