SEPARATION SCIENCE AND ENGINEERING Chinese Journal of Chemical Engineering, 21(4) 348—356 (2013) DOI: 10.1016/S1004-9541(13)60478-4 Ceramic Supported PDMS and PEGDA Composite Membranes for CO 2 Separation * LIU Sainan (刘赛男), LIU Gongping (刘公平), WEI Wang (卫旺), XIANGLI Fenjuan (相里粉娟) and JIN Wanqin (金万勤) ** State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China Abstract Composite membranes have attracted increasing attentions owing to their potential applications for CO 2 separation. In this work, ceramic supported polydimethylsiloxane (PDMS) and poly (ethylene glycol) diacrylate (PEGDA) composite membranes were prepared. The microstructure and physicochemical properties of the compos- ite membranes were characterized. Preparation conditions were systematically optimized. The gas separation per- formance of the as-prepared membranes was studied by pure gas and binary gas permeation measurement of CO 2 , N 2 and H 2 . Experiments showed that PDMS, as silicone rubber, exhibited larger permeance and lower separation factors. Conversely, PEGDA composite membrane presented smaller gas permeance but higher ideal selectivity for CO 2 /N 2 . Compared to the performance of those membranes using polymeric supports or freestanding membranes, the two kinds of ceramic supported composite membranes exhibited higher gas permeance and acceptable selectiv- ity. Therefore, the ceramic supported composite membrane can be expected as a candidate for CO 2 separation from light gases. Keywords polydimethylsiloxane, PEGDA, ceramic support, composite membrane, CO 2 separation 1 INTRODUCTION The separation of carbon dioxide from light gas mixtures is an important environmental and energy issue, which has attracted considerable research inter- est in recent years [1]. Compared with conventional absorption, adsorption, and cryogenic distillation tech- niques, membrane separation presents inherent ad- vantages such as high efficiency, low cost and small footprint. Thus, it is considered to be a better candi- date for the CO 2 separation [2-4]. Gas separation membranes work on the principle of selective permeation that gases are separated due to their different solubility and diffusivity in polymers. Generally, gas solubility in polymers is higher with increasing gas condensability. CO 2 typically exhibits higher solubility than light gases like hydrogen and ni- trogen since its higher condensability in polymers [5, 6]. Siloxane-based polymers are widely studied because of their low surface energy and low glass transition temperature, which sounds high flexibility and gas diffusivity [7]. Recently, polymeric materials contain- ing ether oxygen groups, such as pure poly(ethylene glycol) (PEG), PEG-containing copolymers and acry- lated PEG, have been extensively investigated in CO 2 separation fields [8-20]. Those materials containing polar moieties, ether groups, have an affinity for CO 2 for dipole-quadrupole interactions [21]. Lin and Free- man [16-18] prepared symmetric pure PEG and acry- lated PEG membranes, and those membranes exhib- ited high CO 2 /light gas selectivity. Although the gas permeation performance for various membranes mainly depends on the properties of the membrane materials, the types of membrane structure also have an influence on the membrane performance which should not be neglected. In indus- trial application, composite membranes that consist of a porous support layer with a thin dense skin layer on top are predominantly used because of their higher gas permeability and mechanical strength compared to symmetric organic membranes or inorganic membranes. To date, most of the membranes reported for CO 2 separation are porous polymeric supported or free- standing. The major drawbacks of these membranes are low mechanical, chemical and thermal stability. The stability of the composite membranes is deter- mined by not only the separation layer but also the interface between the separation and support layers. In the cases of high temperature or high pressure, poly- meric supports cannot constraint the shear stress at the interface, thus the separation layer may delaminate from the support with elapse of the operation time. However, the rigid ceramic supports can confine the polymer that penetrates into the pores, which improves the stability of the composite membrane with the con- finement effect [22]. In addition, ceramic supports can provide sufficient mechanical stiffness to support a thin selective layer even at high pressure. The low transport resistance of ceramic support could enhance the gas permeance as well. Because of the above men- tioned advantages of ceramic supports, numerous studies have been focused on the preparation of or- ganic/inorganic composite membranes [23-32], which combines the advantages of both polymeric and inor- ganic membranes. Our previous works have developed Received 2011-12-02, accepted 2012-11-04. * Supported by the National Basic Research Program of China (2009CB623406), the National Natural Science Foundation of China (20990222) and the Natural Science Foundation of Jiangsu Province (BK2009021, SBK200930313). ** To whom correspondence should be addressed. E-mail: wqjin@njut.edu.cn