Synthesis and Catalytic Applications of Mesoporous Titanosilicates Assembled from Zeolite Precursors
Date Issued
2009
Date
2009
Author(s)
Lin, Tsung-Han
Abstract
First, cubic Pm3n SBA-1 was synthesized successfully in alkaline condition (pH=8.0~10.0) by using CTEABr as the template and Na-silicate, which is very cheap for commercial use, as the silca source. Then, Na-silicate was replaced by ZSM-5 seeds as the silica source to synthesize cubic SBA-1 and controlling the hydrothermal period of the ZSM-5 seeds was found to be essential in order to obtain crystalline ZSM-5 without observing the separation phase from the mesoporous structure. Finally, Ti-silicalite (TS-1) seeds were used as the silica precursor and CTEABr as the template to synthesize new mesostructured material labeled as TSBA-1 by co-precipitation method. The resultant materials were as characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherm, FT-IR, UV-Vis spectroscopy and XANES. The small-angle XRD patterns of the as-synthesized TSBA-1 reveled three peaks indexed as (200), (211) and (220) of the 3-D cubic Pm3n phase. Moreover, no seperated phase of ZSM-5 was observed in the high-angle region. TSBA-1 exhibited an absorption band at 550 cm-1 in the FT-IR spectrum, which is assigned to the stretching of five-membered T-O-T (T = Si or Ti) rings in ZSM-5. In UV-Vis spectra, TSBA-1 had an obvious absorption band at 220 nm, assigned to the tetrahedrally-coordinated Ti species. The materials were tested as catalysts in oxidation of 2,3,6-trimethyphenol (TMP). The optimal conversion of TMP and selectivity of TMBQ are 37.3% and 91.9% respectively.
Subjects
SBA-1
TS-1
mesoporous zeolite
Type
thesis
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