Non-ionic surfactant (C13EOm, m = 6, 12 and 18) for large pore mesoporous molecular sieves preparation

Polyoxyethylene tridecylethers (C13EOm, m = 6, 12 and 18) have been used as templating agents for synthesis of large pore mesoporous materials. The ef fect of surfactant/silicium molar ratio, heating time, and temperature, and the number of oxpethylene units on the mesoporous material syntheses has b een studied in detail. Final compounds were characterized by different tech niques such as SEM, TEM and nitrogen adsorption-desorption analysis. The pr esent work shows that the surfactant/tetramethoxysilane molar ratio has a s trong effect on the pore diameter for a given surfactant. It is evidenced t hat both tetramethoxysilane (TMOS) and surfactant can play a role of swelli ng agent depending on the surfactant/TMOS molar ratio. It is also shown tha t the pore diameter depends strongly on the heating time and temperature, o xyethylene unit number and surfactant/TMOS molar ratio. All these factors c an affect jointly or separately the pore diameter of obtained materials. It is revealed that the surfactant conformation can be changed with the heati ng temperature. At higher temperature, a more extended molecular conformati on can be obtained, which leads to materials with larger pore size. (C) 200 1 Elsevier Science B.V. All rights reserved.