International Journal of Greenhouse Gas Control 55 (2016) 195–201 Contents lists available at ScienceDirect International Journal of Greenhouse Gas Control j ourna l h o mepage: www.elsevier.com/locate/ijggc Asymmetric composite PDMS membrane contactors for desorption of CO 2 from monoethanolamine Colin A. Scholes a,∗ , Sandra E. Kentish a , Geoffrey W. Stevens a , David deMontigny b a Peter Cook Centre for CCS Research, Department of Chemical & Biomolecular Engineering, The University of Melbourne, Australia b Faculty of Engineering and Applied Science, University of Regina, Canada a r t i c l e i n f o Article history: Received 30 August 2016 Received in revised form 11 October 2016 Accepted 13 October 2016 Available online 25 October 2016 Keywords: Membrane contactor Carbon dioxide MEA Non-porous PDMS a b s t r a c t Membrane gas solvent contactors have the potential to revolutionize carbon capture, because the tech- nology combines the advantages of both membrane and solvent technologies. Here, an asymmetric composite poly dimethylsiloxane (PDMS) on porous polysulfone membrane contactor was studied for the desorption of CO 2 from loaded 30 wt% monoethanolamine (MEA) solution. Importantly, this study investigated the performance of the contactor at temperatures where the MEA solution entered the con- tactor as a liquid and as a vapor. It was found that the PDMS contactor CO 2 flux was comparable to other reported membrane contactors when the MEA solution was in the solvent phase, but when the feed was vaporized the CO 2 flux increased by an order of magnitude. Similarly, the overall mass transfer coefficient had the same behavior, in that an order of magnitude increase was obtained when the MEA solution was above the boiling temperature. The CO 2 permeability through the non-porous PDMS layer was calculated based on mass transfer correlations and the temperature trend was comparable to literature. This indi- cated that CO 2 transport through the PDMS layer was the same for the range of temperature and phase conditions studied, and that the mechanism was based on CO 2 transporting in the gas phase. Significantly high water fluxes were observed through the PDMS membrane, two orders of magnitude greater than CO 2 , which was comparable with other non-porous contactors. However, at 110 ◦ C, the H 2 O/CO 2 flux selectivity decreased to 14, indicative of the higher CO 2 flux at that temperature because of the vapor feed. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Membrane gas solvent contactors are a hybrid technology com- bining solvent absorption with membranes that enables efficient gas separation (Favre and Svendsen, 2012; Franco et al., 2008). One of the biggest advantages of membrane contactors is the high mass transfer area per unit volume, because of the highly effi- cient membrane module packing, which reduces the equipment size compared to solvent absorption (Falk-Pedersen et al., 2005; Reed et al., 1995). Membrane gas solvent contactors have been studied for carbon capture and storage (CCS), with a number of pilot plant trials reported (Herzog and Falk-Pedersen, 2000; Scholes et al., 2014b, 2012b). Critically, the majority of the membrane con- tactor research has focused on porous membranes, because the pores minimize mass transfer resistance, when gas filled, and high fluxes are possible. However, the issue of solvent wetting of the ∗ Corresponding author. E-mail address: cascho@unimelb.edu.au (C.A. Scholes). pores and solvent breakthrough into the gas phase is an ongoing problem (deMontigny et al., 2006) which has a detrimental effect on the contactor separation performance. Pore wetting can be min- imized by utilizing hydrophobic polymeric membranes, the most common being polypropylene (PP) and poly tetrafluoroethylene (PTFE) (Chun and Lee, 1997; Hoff et al., 2004; Karoor and Sirkar, 1993; Kim and Yang, 2000; Mavroudi et al., 2003; Sengupta et al., 1998; Yeon et al., 2003). The choice of solvent is also important in terms of overall mass transfer and pore wetting, the most common being amines (mostly monoethanolamine (MEA)), amino acids and NaOH because of their use in traditional solvent absorption. Asym- metric non-porous membranes have been studied as membrane contactors for CO 2 capture as an alternate approach, with varying success (Scholes et al., 2015a). For non-porous contactors the key issue relates to ensuring the non-porous layer is sufficiently thin to minimize mass transfer resistance while also being based on a high CO 2 permeance polymer (Korikov and Sirkar, 2005). As such a number of high permeable polymers have been trialled, such as polymethylpentene (PMP), Teflon AF2400 and poly (trimethylsilyl- 1-propyne) (PTMSP) on microporous PP supports with MEA solvent http://dx.doi.org/10.1016/j.ijggc.2016.10.008 1750-5836/© 2016 Elsevier Ltd. All rights reserved.