| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 96 === This investigation was prepared MCM-41 catalyst films on silicon wafer in ammonia media, using tetraethyl orthosilicate (TEOS) as a precursor and cetyltrimethylammonium bromide (CTABr) as a surfactant. Afterward, titanium dioxide was coated on the surface of MCM-41 wafer by Plasma Enhanced Chemical Vapor Deposition (PECVD) method, using titanium (IV) isopropoxide (TTIP) as a precursor. The preparative parameters in this study include annealing time, annealing temperatures, substrate temperatures, oxygen flow rate and plasma power. The prepared catalysts were characterized by X-ray powder diffraction patterns (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Electron Spectroscopy for Chemical Analysis (ESCA). Moreover, the activity of photocatalyst was established with the removal efficiency of methanol vapor.
Optimum the Anatase phase TiO2 prepared by PECVD method was obtained under annealing at 700℃ for 2 hr, substrate temperature at 500℃, 70 sccm of oxygen flow rate, and 100 W of plasma power. In addition, the Anatase-Rutile mixed phase has been synthesized under different substrate temperatures and oxygen flow rate. The particle sizes of titanium dioxide were between 30.34 nm and 59.96 nm by the calculation of Scherrer equation. The best conversion of methanol with UV-light (wavelength 254 nm and 365 nm) were respectively 48.90％ and 48.18％ by using the optimum anatase phase TiO2. While under fluorescent light irradiation, the best photo-activity was Anatase-Rutile mixed phase TiO2 with conversion of 40.03％. Furthermore, the photocatalytic degradation obeyed pseudo-first order kinetics of Langmuir-Hinshelwood equation.
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