Comparison of Photocatalytic Activity of TiO₂ Anatase Prepared by the Sol-Gel Technique and Chemical Vapour Deposition on Naphthalene in the Gas Phase

Abstract

In this study the gas phase photocatalytic oxidation of naphthalene in the presence of TiO₂-based photocatalysts prepared by chemical vapor deposition (CVD) and the sol-gel method is examined. As precursors for the photocatalyst preparation TiCl₄ was used for chemical vapor deposition (CVD), while for the sol-gel technique the precursor was titanium tetra-isopropoxide. The level of naphthalene degradation was examined with FTIR spectroscopy; the identification of the products obtained was performed by GC-MS measurements. The kinetics of the photooxidation reaction of naphthalene in excess of oxygen was investigated. It was found that the kinetics of naphthalene oxidation follow a first-order law; the rate constants were determined by means of mathematical modeling. Also, it was found that the rate limiting steps for naphthalene oxidation are diffusion of the components on the catalyst surface and transport through the films of the photocatalyst particles. The photocatalytic activity of TiO₂-based photocatalysts prepared by CVD as a gas phase method and the sol-gel technique as a liquid method are compared. The photocatalysts showed an excellent efficiency for naphthalene degradation in the presence of oxygen; a complete mineralization of the aromatic toxic compound to CO₂ and water was achieved.