Abstract: Hierarchical TS-1 zeolites were synthesized successfully by the hydrothermal method using cationic polyquaternium-7 and polyquaternium-6 as mesoporous template, respectively. The obtained samples were characterized by X-ray diffraction, UV-Visible spectroscopy, scanning electron microscopy, transmission electron microscopy, and N₂ adsorption-desorption. The catalytic performance of the materials was evaluated for the oxidation of bulky molecular benzothiophene and small molecular thiophene. The results show that the addition of polyquaternium-7 has a little effect on the crystallization, the state of titanium sites, and the crystal morphology of hierarchical TS-1. However, the crystal morphology of hierarchical TS-1 changes from small cubic crystals to large rectangular crystals with increasing content of polyquaternium-6. Hierarchical TS-1 zeolites synthesized from the two kinds of polymers possess obvious mesoporous channels. Moreover, they give much higher activity in benzothiophene oxidation than TS-1, which is attributed to the presence of additional mesopores for reducing the diffusion limitation. In addition, hierarchical TS-1 zeolites also exhibit the similar oxidative activity for thiophene to TS-1 and give the removal rate of 100% for 2 h.

Key words: polyquaternium-7, polyquaternium-6, hierarchical TS-1 zeolite, hydrothermal synthesis, benzothiophene, thiophene, oxidation