(706c) Membrane Adsorbents Comprising Self-Assembled Inorganic Nanocages (SINCs) for Direct Air Capture | AIChE

(706c) Membrane Adsorbents Comprising Self-Assembled Inorganic Nanocages (SINCs) for Direct Air Capture


Tran, T. - Presenter, University At Buffalo
Singh, S., University at Buffalo, State University of New York
Lin, H., University of Buffalo, State University of New Yor
Grass, A., University at Buffalo
Cook, T. R., University at Buffalo, The State University of New York
There is a significant interest in solid sorbents with high CO2 sorption capacity for economically viable direct air capture (DAC) of CO2. Although current solid sorbents such as polyethylenimine (PEI)-supported silica demonstrate high CO2-sorption capacity, its kinetics is slow partially because CO2 has to diffuse into the highly filled pores. In this work, we design highly porous membrane adsorbents comprising PEI and self-assembled inorganic nanocages (SINCs) supported by porous membranes such as Solupor membrane with a porosity of 86%, a high-density polyethylene porous support. PEI is a leading amine-based material for DAC with high CO2-sorption capacity. SINCs have small sizes (< 10 nm), which obviates the need for CO2 to diffuse throughout large crystallites (such as MOFs), reducing adsorption and desorption times. Zirconium-carboxylate cages (Zr-SINCs) were synthesized and further functionalized with amines to enhance the CO2 sorption capacity. The membrane-sorbent demonstrates high PEI content up to 48 wt.% while still retain a high porosity of 75%, leading to high CO2 permeance (~80,000 GPU, 1 GPU = 10-6 cc(STP)/cm2/s/cmHg) and hence lowering pressure drop. A membrane sorbent containing 45 wt.% (PEI+SINCs) exhibits CO2 gas sorption of 0.61 mmol CO2/g sorbent at 400ppm CO2 and 25°C under dry condition. However at 30% RH, the CO2 capacity increases to 1.33 mmol CO2/g. The effect of PEI and SINCs composition in the membrane-sorbents, RH, and temperature on CO2 sorption capacity and kinetic will be discussed.