Preparation of single-site Ti-containing mesoporous silica with a nanotube architecture and its enhanced catalytic activities

Abstract

Single-site Ti-containing mesoporous silica with a nanotube architecture (Ti–MST) was successfully prepared by a solvent evaporation method through the combination of a precursor solution for the synthesis of Ti-containing mesoporous silica (Ti–MS) and carbon nanofibers (CNF) as a hard template. The nanotube architecture of the Ti–MST consisting of quite thin mesoporous silica walls was obtained by controllably coating a precursor solution on the CNF surface and then calcining to completely remove the templates, i.e., CNF and organic surfactant for the construction of the nanotube architecture and the mesoporous structure, respectively. Tetrahedrally coordinated Ti moieties (single-site Ti moieties) were also successfully incorporated within this unique mesoporous silica matrix. The construction of the nanotube architecture resulted in a significant enhancement of the catalytic activity for the epoxidation of alkenes and unsaturated fatty acid methyl ester, having relatively large molecular sizes. Such an enhancement was achieved by the advantageous structure of the nanotube architecture with mesoporous frameworks for the diffusion of substances to the catalytically active single-site Ti moieties.