Characterization of Ti-ZSM-5 Prepared by Isomorphous Substitution of B-ZSM-5 with TiCl4 and Its Performance in the Hydroxylation of Phenol

Abstract

Ti-ZSM-5 has attracted much attention for its unique catalytic properties in selective oxidation. Isomorphous substitution is an alternative synthesis method to obtain Ti-ZSM-5 with low contents of extraframework Ti. However, the nature of the precursor also has a great influence on the catalytic performance of Ti-ZSM-5. In this work, two Ti-ZSM-5 samples were prepared by isomorphous substitution of precursor B-ZSM-5 zeolites with gaseous TiCl4. The effect of the nature of the B-ZSM-5 precursor obtained by different hydrothermal synthesis procedures on the catalytic performance was investigated through characterization by XRD; FT-IR, UV−vis, and UV−Raman spectroscopies; SEM; N2 adsorption; and phenol hydroxylation. The characterization results show that the two Ti-ZSM-5 samples synthesized by gas−solid isomorphous substitution of the B-ZSM-5 precursor contain very little anatase and have similar amounts of active sites. They consist of cuboidlike crystals with different sizes that are agglomerated into di...