Effect of seeds on the dry-gel synthesis and catalytic performance of titanosilicalite-1

Titanosilicalite-1 (TS-1) has been synthesized successfully by a low cost dry-gel conversion method from fumed silica sources, with tetrabutylorthotitanate (TBOT) as titanium source and tetrapropylammonium hydroxide (TPAOH) as the template with the cooperative effects of active seeds. The influence of the crystal seeds on the formation of TS-1 was thoroughly investigated. Some physical and chemical properties and the structure of the product were characterized by the X-ray diffraction and scanning electron microscope techniques. The results reveal that the crystallinity, crystal size and catalytic performance of the samples are affected greatly by the addition of the seed and the nature of the seed. When mole ratio n(TPA⁺)/n(Si)=0.05, the samples exhibited about 20% conversion, which was higher than the sample (11.9% conversion) synthesized without any seed added, especially for the sample synthesized by adding the active seeds (23.6% conversion). More importantly, applying these findings will greatly reduce the cost of synthesizing TS-1 zeolite on the basis of maintaining high activity. The synergistic effect of seeds and templates was discussed.