Alkaline composite inorganic membrane for high temperature carbon dioxide separation

Abstract The development of carbon dioxide separation and capture technologies is necessary to achieve a carbon-neutral society. Focusing on Direct Air Capture (DAC), a technology for the direct capture of carbon dioxide from the atmosphere. Although Li 4 SiO 4 -based membranes have been reported as a separation membrane development using alkali ceramics, the carbon dioxide desorption temperature of Li 4 SiO 4 is high, around 700°C. To use it for CO 2 methanation and methanolation reactions, it’s necessary to develop separation membranes for m-DAC using materials that can desorb CO 2 at around 300°C. This hasn’t yet been considered. Therefore, the aim of this study was to develop an effective alkaline adsorbent for CO 2 recovery that absorbs and desorbs CO 2 at around 300°C. Membranes with Na 2 CO 3 supported on an α-Al 2 O 3 substrate showed a permeability of 3.58 x 10 −10 [mol m −2 s −1 Pa −1 ] for N 2 and 3.93 x 10 −10 [mol m −2 s −1 Pa −1 ] for CO 2 after two coatings, which is selective for CO 2 . However, the membranes didn’t show CO 2 adsorption and the substrate broke after three coatings, suggesting that the α-Al 2 O 3 substrate was alkali-sensitive and that the thermal decomposition of Na 2 CO 3 wasn’t advanced.