(573b) Thin Film Composite Membranes Based on Poly(ethylene oxide) and Uio-66-NH2 for CO2/N2 Separation | AIChE

(573b) Thin Film Composite Membranes Based on Poly(ethylene oxide) and Uio-66-NH2 for CO2/N2 Separation


Shah, C., University at Buffalo
Bui, V., University at Buffalo
Lin, H., University of Buffalo, State University of New Yor
Mixed matrix membranes have been pursued gas separations, such as post-combustion carbon capture, and a key challenge is to fabricate thin film composite (TFC) membranes containing a defect-free selective layer (< 1 µm). Herein, we successfully prepared TFC membranes using a gutter layer of polydopamine (PDA) modified polydimethylsiloxane (dPDMS). The selective layer (as thin as 200 nm) comprises bottlebrush amorphous polyethylene oxide (aPEO) and metal-organic frameworks (UiO-66-NH2). The PDA layer (<10 nm) acts as a bio-adhesive promoting the formation enables a thin and defect-free aPEO/MOFs layer via hydrogen bonding between amine in PDA and ethylene oxide. Cross-sectional SEM presents a smooth mixed matrix selective layer confirming the good compatibility between aPEO and UiO-66-NH2. For example, adding 10 mass% of UiO-66-NH2 increases CO2 permeance from 1200 to 2800 GPU and CO2/N2 selectivity from 40 to 50, presumably because the amine groups in UIO-66-NH2 improves the compatibility between the MOFs and aPEO and affinity towards CO2. Conduction of mixed-gas and long-term stability test of aPEO/UIO-66-NH2 TFC membranes show superior and stable separation performance under simulated flue gas conditions for 70 hours. Specifically, the membrane presents stable CO2 permeance of 2200 GPU and CO2/N2 selectivity of 32 under mixed gas (CO2:N2=15:85) for 20 hours. When 1.2 mol% water vapor was introduced into the system, CO2 permeance decreased to 1400 GPU, and CO2/N2 selectivity increased to 76, presumably because the water vapor swells the selective layer and amine groups facility transported the CO2 under wet conditions. After two rounds of mixed gas tests (dry-wet-dry), the membrane exhibits stable and reversible separation properties. This showcases the potential benefits of fabricating high-performance TFC membranes using UIO-66-NH2.