日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

A highly crystalline composite of pure-silica MSE-type precursor with organic structure-directing agent (OSDA) was synthesized by the use of dry-gel conversion (DGC) method, and the material was named YNU-2P. Time-course investigation showed that *BEA phase appears at a very early stage of the crystallization followed by the transformation to MSE phase. The presence of significant site defects in the YNU-2P caused the collapse of MSE framework during calcination. The defects were partially filled up with Si by a steaming treatment, stabilizing the MSE framework. Complete removal of the OSDA by calcination gave a microporous pure-silica material YNU-2. The remaining site defects in the YNU-2 allow the atom insertion into the framework. After optimizing the conditions for steaming and vapor-phase TiCl₄ treatments, an efficient introduction of Ti into the framework was successful to give a new microporous titanosilicate Ti-YNU-2. This material was proved to be a high-performance catalyst, exhibiting remarkably enhanced performance compared to Ti-MCM-68 that is known to show superior performance to TS-1 for phenol oxidation using H₂O₂ as an oxidant. A hypothesis explaining the reason for extremely high activity and selectivity was proposed.