(578d) Designing Thin–Film Composite Membranes Based on Amorphous Poly(ethylene oxide) for CO2/Gas Separation | AIChE

(578d) Designing Thin–Film Composite Membranes Based on Amorphous Poly(ethylene oxide) for CO2/Gas Separation

Authors 

Lin, H., University of Buffalo, State University of New Yor
Tran, T., University At Buffalo
Cross-linked poly(ethylene oxide) (XLPEO) is one of the leading materials for CO2 capture from pre-combustion and post-combustion processes. For example, XLPEO prepared from 80% poly(ethylene glycol) methyl ether acrylate (PEGMEA) and 20% poly(ethylene glycol) diacrylate (PEGDA) exhibit CO2 permeability of 540 Barrer, and CO2/H2 and CO2/N2 selectivity of 11 and 43. However, these XLPEOs cannot be dissolved in coating solutions, which makes it impossible to be fabricated into thin-film composite (TFC) membranes using state-of-the-art manufacturing processes. In this study, we prepare soluble, high molecular weight, and amorphous PEO via atom transfer radical polymerization (ATRP). PEOs with molecular weights from 180 kDa to 220 kDa were synthesized by adjusting the ratio of the PEGMEA and initiator (pentaerythntol tetrakis(2-bromo-isobutyrate)). All polymers are amorphous at 35 ℃ and show a similar glass transition temperature of around -66oC. Increasing the polymer molecular weight from 180 to 220 kDa decreases the CO2 permeability from 540 to 450 Barrer while retaining CO2/N2 selectivity of 43. Gas solubility is independent of the polymer molecular weight. The high molecular weight PEO was fabricated into TFC membranes by a solution casting method with a gutter layer of polydimethylsiloxane (PDMS). The gutter layer shows CO2 permeance of 5400 GPU, while the PEO-based TFC membranes exhibit CO2 permeance of 1000 to 2000 GPU with CO2/N2 selectivity of 38 to 20 at 35 oC. We will also present the mixed-gas CO2/N2 separation properties as a function of feed composition and temperature, and the performance will be compared with the leading membranes reported for carbon capture.