MFI Titanosilicate Nanosheets with Single-Unit-Cell Thickness as an Oxidation Catalyst Using Peroxides

Titanosilicate MFI (a three-letter structural code among ∼200 zeolite framework codes) nanosheets of single-unit-cell thickness were synthesized with a diquaternary ammonium surfactant as the zeolite structure-directing agent, that is, C₁₆H₃₃–N⁺(CH₃)₂–C₆H₁₂–N⁺(CH₃)₂–C₆H₁₃. The resultant titanosilicate nanosheet possessed a large intersheet mesopore volume with high surface area due to the nanomorphic crystalline architecture as well as the isomorphically incorporated titanium species. Thus, it exhibited notable catalytic activities with high epoxide selectivity for bulky molecular epoxidation reactions using H₂O₂ or t-butyl hydroperoxide as an oxidant. In addition, the catalytic performance could be enhanced via postsynthetic fluoride treatment with NH₄F that can reduce the surface silanol groups and, hence, increase the surface hydrophobicity.