Crystallization of titanium silicalite-1 (TS-1) from gels containing hexanediamine and tetrapropylammonium bromide

Titanium-substituted silicalite-l (TS-1) has been synthesized from gels containing hexanediamine (C6DN) and tetrapropylammonium bromide (TPABr). In this system, TPA(+) cations serve as templating agents to direct the MFI structure, and the diamine provides the alkalinity necessary for crystallization. Following this synthesis route, titanium could be incorporated in the silicalite-l framework up to a level of about 2 titanium/unit cell without formation of extralattice species. The crystal habit was unusual for TS-1 and changed with the composition of the gel. Some of the samples were found to be active in the hydroxylation of phenol with aqueous hydrogen peroxide, leading to the formation of para- and ortho-dihydroxybenzenes with a plo ratio significantly higher than that obtained over conventional TS-1 samples.