The Investigation of TiO2 Photocatalysis by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy

• Main Authors: Shih-Yi Lin, 林世益
• Other Authors: Thomas C.-K. Yang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/11449491766426899120

碩士 === 國立臺北科技大學 === 化學工程系碩士班 === 90 === The investigation of heterogeneous photocatalysis over TiO2 surfaces is conducted by in situ diffuse reflectance Fourier transform spectroscopy (in situ DRIFTS). In the first part of this study, acid blue 9 (AB-9) is chosen as a model compound for kinetic and mechanistic studies of aqueous-phase photocatalysis, in which the generated OH radicals could decompose AB-9 structure completely. The photocatalytic process is carried out through the adsorption of reactants, surface reaction and desorption of products. As a result, the rate of decomposition would be affected by concentrations of dissolved oxygen, pH values and surface property of photocatalyst. The results show the rate of AB-9 decomposition in proton-rich environment is faster five times than in hydroxyl-rich. However, the identical intrinsic rates of AB-9 decomposition in various pH environments by means of DRIFTS show the decomposition rate is dominated by the mass transfer of reactants during the photocatalytic oxidation. The second part of this study is to investigate the mechanisms of adsorption and decomposition during the gaseous photocatalysis of 2-propanol and toluene by DRIFTS. According to the infrared analysis of TiO2, the adsorbed water and hydroxyl groups are bound to the surface strongly and would be replaced by 2-propanol molecules only. In addition, the non-volatile carbonyl groups are accumulated on TiO2 surface during the photocatalytic oxidation of toluene and 2-propanol, which reduce the photoactivity of catalyst by occupying the activity sites. Moreover, it can be found that increasing the humidity of reaction environment lead the alleviation of surface deactivation of catalyst for toluene and 2-propanol photooxidation.