Synthesis of High-Performanced Titanium Silicalite-1 Zeolite at Very Low Usage of Tetrapropyl Ammonium Hydroxide

Abstract

A novel method for the synthesis of high-performanced titanium silicalite-1 (TS-1) zeolite at a very low usage of tetrapropylammonium hydroxide (TPAOH) was developed in this work. The method involved a temperature-programmed hydrothermal crystallization (TPHC) of a batch with a TPAOH/SiO2 molar ratio of as low as 0.05, being 5 times smaller than that employed in the conventional synthesis, in which the TPAOH was entirely provided by a TS-1 precursor sol. The characterizations of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance ultraviolet–visible spectroscopy (DR UV–vis), and scanning electron microscopy (SEM) indicated that the TS-1 synthesized via the novel method possessed a uniform crystal size of ∼0.3 μm, a very high crystallinity and a considerably large content of framework Ti (2.33 mol %). The TS-1 had been employed as the catalyst for the ammoximation of cyclohexanone, of which the influencing factors were systematically investigated. It was shown that the TS-1 synthesized via the novel method possessed a very high performance, which is even better than for those synthesized via the conventional method both in this work and in the literature work.