Synthesis of TS-1 with preferably distributed Ti in depth direction of crystals

Abstract

MFI-type titanosilicate, TS-1, was synthesized by using silicalite-1 as the silica source. When the synthesis gel was highly alkaline, dissolution of silicalite-1 drastically occurred in the initial stage of synthesis and Ti species were then uniformly incorporated in the whole body of TS-1 crystals produced. On the other hand, we found that when the gel had a lower alkalinity, dissolution in the initial stage was suppressed and recrystallization occurred on the surface of parent silicalite- 1, resulting in the Ti species being dominantly distributed in the vicinity of the external surface of the remaining core. 1-Hexene oxidation was performed over TS-1. TS-1 in which Ti species were distributed near the external surface showed better catalytic performance in terms of H2 O2 efficiency.