Investigation on Titanium Silicalite-1 Zeolite Synthesis Employing ATPAOH as an Organic Structure Directing Agent

Tetrapropylammonium hydroxide (TPAOH) as an organic structure directing agent (OSDA) is of great importance for the preparation of titanium silicalite-1 (TS-1) zeolite. In this paper, we employed a new OSDA, allyltripropylammonium hydroxide (ATPAOH), in the synthesis process and successfully synthesized ATS-1 zeolite (MFI type). Compared with traditional OSDA TPAOH, one of TPAOH's propyl groups is substituted by an allyl group, which endows ATPAOH with unique properties. On the one hand, ATPAOH accelerates the crystallization rate of titanium silicalite zeolite remarkably due to the strong interaction between Ti species and ATPAOH during the crystallization period. On the other hand, ATPAOH is beneficial for the formation of isolated 6-coordinated Ti species, thus leading to the generation of lower amount of anatase. Owing to its abundant active Ti species, ATS-1 prepared by ATPAOH as OSDA exhibits a much better catalytic performance for the cyclohexanone ammoximation reaction than TS-1 prepared by TPAOH as OSDA.