STRUCTURAL AND SURFACE CHARACTERIZATION OF THE POLYCRYSTALLINE SYSTEM CRXOY.TIO2 EMPLOYED FOR PHOTOREDUCTION OF DINITROGEN AND PHOTODEGRADATION OF PHENOL

The polycrystalline system CrxOy-TiO2, used as a catalyst for photoreactions, was studied by X-ray diffractometric method, visible-ultraviolet diffuse reflectance and infrared spectroscopic methods, surface area determination, and porosimetry to characterize its structural and surface features. Two series of catalysts were prepared by two different methods, namely by coprecipitation and by impregnation. The first series was tested as photocatalysts for the dinitrogen photoreduction in a gas-solid regime and for the phenol photodegradation in a liquid-solid regime. The results indicate that the interaction of chromium ions with OH groups modifies the surface properties of the supports and consequently influences the photocatalytic activity. The addition of Cr ions was found to accelerate the photoreduction reaction, while it is detrimental to the photodegradation of phenol. © 1992.