纤维素醋酸丁酸酯/碳纳米管混合基质膜的气体分离性能

Gas Separation Properties of Cellulose Acetate Butyrate/MWCNTs Mixed Matrix Membranes

通过溶液复合-溶液成膜的方法,制备了一系列纤维素醋酸丁酸酯（CAB）/多壁碳纳米管（MWCNTs）的新型混合基质膜.表征了CAB/MWCNTs膜材料的形貌、结构与力学性能.结果表明,MWCNTs与CAB界面未见明显缺陷存在,混合基质膜材料具有良好的力学性能.进一步考察了不同MWCNTs含量（2 wt%~30wt%）对CAB/MWCNTs混合基质膜材料的气体分离性能的影响.发现,随着混合基质膜中MWCNTs含量的增加,其对几种测试气体（O2、N2、CH4、CO和CO2）的渗透系数均明显提高,尤其是常见气体对中的＂快气＂——O2和CO2的渗透系数提高显著：当MWCNTs含量为30 wt%时,所制备的混合基质膜对O2和CO2渗透系数分别达到40.24和180.20 Barrer,比纯CAB膜分别提高了约300%和260%;同时,混合基质膜对多种气体对均表现出优异的分离效果.

A new kind of mixed matrix membranes （MMMs） with cellulose acetate butyrate （CAB） as matrix and multi-walled carbon nanotubes （MWCNTs） as fillers was prepared by solvent mixing-solution casting method. The morphology, structure and mechanical properties of CAB/MWCNTs MMMs were characterized using scanning electron microscopy （SEM） ,transmission electron microscopy （TEM） and tensile testing. The results showed that MWCNTs and CAB matrix had good interfacial adhesion. No obvious defect was observed on the fracture surface of CAB/MWCNTs MMMs. The obtained CAB/MWCNTs MMMs exhibited good mechanical properties. Furthermore, gas separation properties of the CAB/MWCNTs MMMs for O2 , N2 , CH4 , CO and CO2 were investigated. It was found that, with the increase of MWCNTs content, the permeability coefficients of CAB/MWCNTs MMMs for all test gases （ O2, N2, CH4, CO, CO2 ） were significantly improved, especially for ＂quicker gas＂-- O2 and CO2. When the content of MWCNTs was 30 wt% , the permeability of MMMs for O2 and CO,reached 40.24 and 180.20 Barrer,which compared with neat CAB membrane,increased by 300% and 260% ,respectively. Moreover, the CAB/MWCNTs MMMs showed excellent separation property for some gas pairs,such as CO2/N2 , CO2/CH4 ,CO2/CO and O2/N2. The selectivity of CO2/N2 ,CO/CH4 and CO2/CO was not sacrificed with the increase of CO2 permeability. More interestingly, with the increase of 02 permeability,the selectivity of O2/N2 also increased from 3.2 to 4.0,an increase of 25% compared with neat CAB membranes. Therefore, the present work provides a facile and effective method to prepare new kind of cellulose based MMMs with improved gas separation properties.