Modifying the porosity of SBA-15 silicas by post-synthesis basic treatments

作者：Escax Virginie; Delahaye Emilie; Imperor Clerc Marianne; Beaunier Patricia; Appay Marie Dominique; Davidson Anne^*

来源：Microporous and Mesoporous Materials, 2007, 102(1-3): 234-241.

DOI：10.1016/j.micromeso.2006.12.049

• silica
• multimodal porosity
• dissolution
• restructuring
• SAXS

We explore the use of using post-synthesis basic treatments under mild conditions (hot water or concentrated ammonia solutions for temperatures not exceeding 100 degrees C) in order to modify the porosity of SBA-15 silicas. Dissolution and restructuration processes occurring inside the silica walls induce a hierarchical porosity (micro, meso, macro). TEM images, N-2 sorption results and SAXS measurements show that, after calcination at 450 degrees C, the porosity is bimodal (micro/meso) due to the presence of ordered mesopores and disordered intrawall micropores. After treatment in water (22 h, 100 degrees C, the porosity becomes monomodal (meso), leading to MCM-41 analogs, in that case, disordered intrawall micropores are plugged by silicate oligomers. After treatment with ammonia (22 h, 100 degrees C) micropores are also no longer detected because all the pores are enlarged and the porosity becomes bimodal (meso/macro). Nevertheless, the overall shape of the silica grains is preserved and domains showing ordered mesochannels separated by macropores are identified on TEM images.

• 出版日期2007-5-4