We used silicalite-1 as silicon source and synthesized TS-1 by a desilication-recrystallization method that we propose in the study. tetrapropylammonium hydroxide (TPAOH). Partial desilication of silicalite-1 was carried out with different OH- concentrations in the synthesis gel. The OH- concentration was controlled by changing the amounts of TPAOH added. Silicalite-1 was hydrothermally obtained at 448 K for 1-48 h. Tetrabutyl orthtitanate (TBOT) was used as Ti source. In the resaltant samples, we evaluated the depth profile of Ti species, the surface Si/Ti ratio of TS-1 obtained after 48 h of crystallization by the XPS spectroscopy, suggesting that the Ti concentration was higher in the vicinity of crytal surface. The catalytic properties of of TS-1 were examined for 1-hexene epoxidation. The sample which had a higher Ti content in the vicinity of surface showed a higher product yield and H2O2 efficiency probably due to improve accessibility of substrates to the active Ti sites. Also, in these samples, we consider that undesired decomposition of H2O2 was depressed due top a low contnet of Ti inside the crystals.

Desilication-Recrystallization Method to Prepare Hollow TS-1 Catalyst by Alkali Treatment

ACS Fall 2020 Virtual Meeting

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