Influence of silicalite-1 nanoparticle seeds on the synthesis of Ti-containing mesoporous zeolites

Abstract

Mesostructured titanosilicates (Ti-MS1) possessing zeolitic secondary building units (SBU) can be successfully assembled from Sil-1 nanoparticle seeds. The influence of Sil-1 nanoparticle seeds on the formation of Ti-containing mesoporous zeolites was investigated in detail. The samples were characterized by SEM, XRD, XRF, FT-IR, UV–vis and nitrogen physisorption. The catalytic properties of the materials were examined by phenol and benzene hydroxylation reactions. The results show the amount of Sil-1 seed in the synthesis solution has been found to play a significant role in formation of pure mesostructred materials and catalytic performance. The addition of more Sil-1 nanoparticles could result in a mixture with micro- and mesoporous phases. With the increase of Sil-1 nanoparticles, the mesopore size of Ti-MS1 zeolite becomes smaller, while the wall thickness grows thicker. These mesostructured Ti-MS1 zeolites have TS-1-like titanium species and contain more SBU fragments in the mesoporous walls, which are responsible for the better catalytic activity in hydroxylation reactions and excellent hydrothermal stability in boiling water (over 200h), as compared with conventional mesoporous Ti-MN.