(726d) Few-Nanometer Organosilica Membranes for High-Temperature H2/CO2 Separation
AIChE Annual Meeting
Friday, November 20, 2020 - 8:45am to 9:00am
Traditional silica membranes exhibit excellent H2/CO2 separation properties for H2 purification and CO2 capture, but they are brittle and faced with challenges for low-cost and large-scale production. Herein, we demonstrate the fabrication of ultrathin silica layer on polymeric membranes via plasma treatment to achieve superior H2/CO2 separation properties and excellent scalability of membrane production. Specifically, silica membranes were produced by applying oxygen plasma on polydimethylsiloxane (PDMS) thin films supported by microporous polymer substrates. The plasma treatment successfully converted the PDMS surface layer to a silica ultrathin film, indicated by the formation of SiO2 as thin as 10 nm. We thoroughly investigated the silica formation mechanism and the effect of the plasma treatment conditions on physical properties and H2/CO2 separation properties of the silica membranes. With a plasma exposure time of 120 seconds, the membrane comprising 1.0 Âµm PDMS exhibits H2 permeance of 370 GPU (1 GPU = 10-6 cm3(STP)/cm3 s cmHg) and H2/CO2 selectivity of 51 at 200 ÂºC, which surpasses the Robesonâs upper bound. The membrane shows stable mixed-gas separation performance in the presence of water vapor at 200 Â°C for 47 h. When the PDMS layer thickness was decreased to 200 nm, the 120-second plasma treatment increases the H2 permeance to 930 GPU and H2/CO2 selectivity decreases to 32, which is still above the upper bound. The robust H2/CO2 separation properties coupled with the facile fabrication demonstrate the potential of these organosilica membranes for practical H2 purification and CO2 capture.