Aqueous aminosilane solution grafted three dimensional mesoporous silica for CO2/N2 separation

Three dimensional (3-D) mesoporous silica with large interconnecting pores are found suitable for aminosilane grafting to achieve high CO2 adsorption with higher amine loading. In the present study, cubic KIT-6 is functionalized by (3-aminopropyl)triethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine and N-1-(3-trimethoxysilylpropyle)diethylene triamine with various concentrations of water in aqueous solvent by post grafting method. The effect of water in grafting of aminosilane onto KIT-6 is analyzed by N-2 adsorption/desorption, TEM micrograph, TG analysis and CO2 adsorption. The TG analysis suggests that, surface density of aminosilane increases with increase in water concentration in grafting solvent and TEM micrograph apparently shows the more intense aminosilane on mesoscopic level. The maximum adsorption capacity is 1.60, 2.09 and 2.59 mmol CO2/g-adsorbent for WK.20AP, WK.20DA and WK.10TA, respectively at 30 degrees C and 1.0 bar. The CO2/N-2 selectivity is much higher for aqueous solution grafted adsorbent. Moreover, aqueous solution grafted adsorbents are regenerable showing stable sorption performance till 20 cycles. Thus, aqueous solution grafting is a more efficient way to graft the aminosilane on mesoporous silica as well as design CO2/N-2 selective adsorbent. (C) 2017 Elsevier Inc. All rights reserved.