Novel CO2 capture membranes based on polymerized ionic liquids and polymeric porous supports
September 11-16, 2016
Highly CO2 selective membranes and innovative process designs for CO2 capture can compete with absorption due to relatively low energy consumption and small foot print. In this paper, novel materials poly(ionic liquids) (PILs) are combined with membrane separation for CO2 capture. Poly(ionic liquid)s are solid polymers derived from ionic liquids (ILs) that share many of their physical and chemical properties. For a variety of ILs and PILs, the CO2 sorption is significantly higher than either CH4 or N2 due to Lewis acid-base interactions between the CO2 and nitrogen-containing groups .
Our research is focused on developing composite thin film membranes (TFC) of PILs on porous polymeric supports and characterization of these. The membranes are produced and tested by SINTEF, Norway, using the PILs developed by IK4-CIDETEC, Spain, and Solvionic, France. Various families of PILs were synthesized: poly(diallyldimethylammonium) with a hydrophilic acetate anion, poly(vinylbenzylchloride) derived PILs having lithium bis (trifluoromethanesulfonyl) imide as anion or formulations containing a PIL, an ionic liquid and Zn+2 additives.
Commercially available porous supports such as polysulfone (PSf) and fluoro polymers with different porosities and pore sizes are screened in the membrane fabrication. A novel coating procedure utilizing automated ultrasonic spray coating equipment is optimized for each pair of dense, CO2 selective layer (PIL) – porous polymeric support material by using different solvents, viscosities of solution and drying protocols. We obtained defect free coatings of 0.4 to 10 micron thickness. Variations in thickness were observed due to pore penetration.
The prepared membranes are characterized by contact angle measurements, scanning electron microscopy (SEM) and mixed gas permeation (synthetic flue gas: 15% CO2 in N2-water vapors) using a state of the art gas permeation rig designed and constructed at SINTEF.
The effect of gas relative humidity, feed pressure and operating temperature on membrane separation performances is investigated and will be reported.
The gas permeation results indicate that the choice of support has significant influence on the CO2 permeance/permeability, while the selectivity remained unchanged. The selectivity is hence, mainly controlled by the properties of CO2 selective PILs top layer and not by the supports.
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Marius Sandru, Paul Inge Dahl, Edel Sheridan, Lars Erik Mollan Parnas, Sébastien Fantini, Sandrine Lois, Itxaso Azcune, Ibon Odriozola, and Germán Cabañero, "Novel CO2 capture membranes based on polymerized ionic liquids and polymeric porous supports" in "Advanced Membrane Technology VII", Isabel C. Escobar, Professor, University of Kentucky, USA Jamie Hestekin, Associate Professor, University of Arkansas, USA Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/membrane_technology_vii/26