Comparative study of ethylene- and ethenylene-bridged periodic mesoporous organosilicas

In this paper, we report a comparative study of hexagonal structured ethylene- and ethenylene-bridged PMOs with large pores. 1,2-Bis(trietoxysilyl)ethane and 1,2-bis(trietoxysilyl)ethene were used as precursors and pluronic P123 was used as structure directing agent. The effect of butanol on the pore size distribution and the morphology of ethylene-bridged and ethenylene-bridged PMOs were investigated. This was done by first varying the butanol concentration and next, it was investigated if the acidity range to get uniform pores can be broadened with the addition of butanol. Further, the mechanical and hydrothermal stability of the PMOs were compared. The materials were characterized by N-2-physisorption, XRD, SEM and TEM. It was found that the addition of butanol has a positive influence to get more uniform pores for both PMOs. Although, the effect is much higher for ethenylene-bridged PMOs. Further, it was observed that the mechanical and hydrothermal stability are better for the ethylene-bridged PMOs than for the ethenylene-bridged PMOs. (C) 2009 Elsevier Inc. All rights reserved.