Preparation and CO(2) adsorption properties of aminopropyl-functionalized mesoporous silica microspheres

Abstract

Aminopropyl-functionalized mesoporous silica microspheres (AF-MSM) were synthesized by a simple one-step modified Stöber method. Dodecylamine (DDA) was used as the catalyst for the hydrolysis and condensation of the silica source and as the molecular template to prepare the ordered mesopores. The mesoporous silica surfaces were modified to aminopropyl groups by the co-condensation of tetraethoxysilane (TEOS) with 3-aminopropyltriethoxysilane (APTES), up to a maximum of 20mol.% APTES content in the silica source. The particle size, Brunauer-Emmet-Teller (BET) specific surface area, and mesoporous regularity decreased with increasing APTES content. It is believed that this result is caused by a decreasing amount of DDA incorporated into AF-MSM with increasing APTES content. It was also confirmed that the spherical shape and the mesostructure were maintained even if 20mol.% of APTES was added to the silica source. Moreover, AF-MSM was applied to the CO(2) adsorbent. The breakthrough time of the CO(2) and CO(2) adsorption capacities increased with increasing APTES content. The adsorption capacity of CO(2) for AF-MSM, prepared at 20mol.% APTES, was 0.54mmolg(-1). Carbon dioxide adsorbed onto AF-MSM was completely desorbed by heating in a N(2) purge at 423K for 30min.