SYNTHESIS OF MFI TITANOSILICATES FROM METHYLAMINE-TPABR MEDIA

A new synthesis route for MFI-type titanosilicates (TS-1) using methyl amine along with tetrapropylammonium bromide (TPABr), silica or silico n tetrachloride and titanium tetrachloride, thus avoiding the use of c ostly TPAOH and Ti-alkoxide, has been investigated. The presence of ti tanium ions in the reaction gel slowed down the crystallization of MFI zeolites, while addition of hydrogen fluoride as a co-mineralizer int o the gel dramatically improved the crystallization kinetics. Ti was r eadily incorporated into the zeolite framework, as confirmed by IR, XR D (unit cell expansion), and UV-vis spectroscopy. Reduced initial amou nts of methylamine in the gel led to an increase of the apparent cryst allization rate of the zeolite and to a remarkable decrease of the amo unt of framework Ti, suggesting that high concentration of methylamine is needed for the Ti incorporation into the growing MFI crystallites. (C) Elsevier Science Inc. 1997.