Industrial & Engineering Chemistry Research, Vol.49, No.5, 2194-2199, 2010
Characterization of Ti-ZSM-5 Prepared by Isomorphous Substitution of B-ZSM-5 with TiCl4 and Its Performance in the Hydroxylation of Phenol
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 synthesis procedures on the catalytic performance was investigated through characterization by XRD; FT-IR, UV-vis, and UV-Raman spectroscopies; SEM: N-2 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 different sizes of spherelike particles. Phenol hydroxylation with dilute H2O2 showed that, because of the smaller crystal size of its cuboid particles, Ti-ZSM-5 synthesized with B-ZSM-5 as the precursor at lower crystallization temperature had better catalytic performance and better recyclability.