Kinetics of Photocatalyzed Gas Reactions Using Titanium Dioxide as the Catalyst – Part I: Photocatalyzed Total Oxidation of Olefines with Oxygen

Abstract

In order to obtain a useful expression for the kinetics of the photocatalyzed total oxidation reaction of olefines with TiO 2 as the catalyst, the dependence of reaction rate on the concentration of the educt species, the absorbed irradiation intensity, the wavelength of the light and the temperature was investigated. The experiments were performed in a CSTR system. The results obtained for steady-state conditions showed that besides the photocatalytic activity, the TiO 2 powder fixed on one wall of the reactor has, in addition, a thermal activity for higher temperature. Although the reaction behavior of the system is relatively complex, it can be modeled straightforward by a concept proposing a cooperative coadsorption of oxygen and the olefine species mediated by the electron/hole pairs generated by the absorbed light on the semiconductor's surface.

Kinetics of Photocatalyzed Gas Reactions Using Titanium Dioxide as the Catalyst Part II: Photocatalyzed Total Oxidation of Alkanes with Oxygen

“…The argumentation to support this statement is equal to that presented in the previous paper [14], especially, since the adsorption coefficient of isobutane (b = 0.125 m 3 /mol) for a temperature value of 300 K is of the same order of magnitude as that for propene. However, the reaction mechanism seems to be different from that observed for the alkene species.…”

“…This finding differs from the observations described in the open literature (see, e.g., [2]) where wavelength independent Q-values are obtained. The reasons for the behavior observed in this investigation are the same as in the case of total oxidation of propene [14], i.e., the band structure of the photocatalyst anatase. As it is pointed out by Tang et.…”

“…In order to perform the experiments, the same equipment was used as in the investigation described earlier [14]. TiO 2 powder consisting of 100 % anatase (Hombifine N, Sachtleben Chemie, Duisburg, Germany) was used as the catalyst.…”

“…In a proceeding paper [14] we reported on the kinetics of photocalyzed total oxidation of olefines with oxygen and showed that the kinetics of these reactions cannot be interpreted on the basis of the concepts used to derive rate laws for reactions facilitated with classical catalysts. This contribution deals with the major influences on the reaction rate of the total oxidation of alkanes with oxygen.…”

Photocatalytic Degradation of Benzene in Air Streams in an Optical Fiber Photoreactor

“…Heterogeneous photocatalytic oxidation is a promising technology that has been investigated by many researchers for the destruction of VOCs in contaminated air streams [1][2][3][4][5]. Photocatalytic oxidation utilizes ultraviolet (UV) irradiation and has the potential to completely oxidize air contaminants at low temperature and pressure.…”