The stability of Si-MCM-48 to moisture and compression can be improved by trimethylsilylation, as a result of the increase in hydrophobicity. Moreover, the stability is retained after calcination, although the calcined material is no longer hydrophobic. This stabilizing effect was also observed for Si-MCM-41 and Ti-MCM-41.

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A titanium-containing mesoporous material with a cubic structure, Ti-MCM-48, is synthesized by a two-stage hydrolysis method using tetraethylorthosilicate and tetrabutylorthotitanate and found to be more active than Ti-MCM-41 in the epoxidation of bulky alkenes using Hz02.The recent discovery of a new family of mesoporous molecular sieves denoted M41S has received much attenti0n.I The M41S family is classified into several members: MCM-41 (hexagonal), MCM-48 (cubic) and other species. Ti-and Vsubstituted MCM-4 1 and Ti-substituted hexagonal mesoporous silica (Ti-HMS) have also been synthe~ized.~-s These Ti-and V-substituted mesoporous molecular sieves pioneered the potential for oxidization of bulky molecules which cannot enter into the micropores of zeolites such as TS-1, TS-2 and Ti-beta. MCM-48, characterized by a three-dimensional channel system, may have several advantages over MCM-41 with a onedimensional channel system when applied to catalytic reactions: for instance, the three-dimensional pore system should be more resistant to blockage by extraneous materials than the onedimensional pore system. Here we report the synthesis of Ti-MCM-48 and its use as a catalyst for epoxidation of bulky alkenes. The effects of gel composition and the gel preparation method on the structure of mesoporous materials are also reported.Mesoporous materials were synthesized under hydrothermal conditions at 373 K in a static Teflon bottle for 10 days. The