Synthesis of mechanically robust epoxy cross-linked silica aerogel membranes for CO 2 capture

Abstract

Abstract Mesoporous SiO2 aerogels are multi-functional porous materials with diverse applications. However, the fragile characteristics and low mechanical strength of mesoporous SiO2 aerogels limits their development for use in industrial applications. The mechanical strength of SiO2 aerogels can be greatly enhanced by the addition of tri-epoxy cross-linkers. Tri-epoxy cross-linked SiO2 aerogels with tri-epoxy concentrations of 7.5%, 15%, 30% and 45% were coated on macroporous Al2O3 membrane supports. The surface of the tri-epoxy cross-linked SiO2 aerogel membranes became superhydrophobic after fluoroalkylsilane (FAS) modification. Compared to native SiO2 aerogel membranes in the absence of tri-epoxy cross-linker, the pore size of the tri-epoxy cross-linked SiO2 aerogel membranes with tri-epoxy concentrations of 15% and 30% increased to approximately 6 nm, resulting in an increase in the CO2 absorption flux. The highest CO2 absorption flux of 1.4 mmol/m2s was reached for the tri-epoxy cross-linked SiO2 aerogel membrane with a tri-epoxy concentration of 15%. The durability of the as-prepared SiO2 aerogel membranes for CO2 absorption is also demonstrated in this work. Consequently, the mechanically robust tri-epoxy cross-linked SiO2 aerogel membranes have potential applications in membrane contactor systems for CO2 capture.