Chemical Engineering Journal, Vol.203, 36-42, 2012
The influence of secondary structure directing agents on the formation of mesoporous SBA-16 silicas
Hydrothermal syntheses of large porous SBA-16-like mesostructures were obtained, considering the effect of several secondary structure directing agents (P123, NaCl, CTMABr and butanol), on the gels containing F127 in acidic solution, with TEOS as the only silica source. These new synthesized materials have their texture and structure clearly affected by the proposed additions of these agents. The degrees of silica condensation increased from 1.68 to 2.26, as observed by solid state Si-29 NMR. Characterization by SAXS, TEM and nitrogen sorption at 77 K revealed a decrease in pore volume from 1.7 to 0.4 cm(3) g(-1) for the sample synthesized with NaCl, while the wall thickness decreased from 10.2 to 8.1 nm when CTMABr was used as secondary structuring agent. The morphologies observed for all samples were distinct, varying from plate-like until spherical and dodecahedral forms. Some morphological features were well correlated with other data, such as pore volume and surface area, measurements that have contributions from intraparticular pores. (c) 2012 Elsevier B.V. All rights reserved.