Studies on the catalytic properties of metal oxide thin film on the molten salt liquid film

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In some cases, the catalyst which is originally supported on the substrate becomes melting, interacts with the substrate and finally exhibit its own characteristics during the course of a chemical reaction. It is important to clarify the mechanism of the liquid film - substrate interaction from the view point of catalyst design.The surface of the catalyst and/or substrate actually does exhibit the specific characteristics of them. The purpose of this work is to clarify the interaction mechanism between the liquid film and the substrate during chemical reaction. In this respect, the metal oxide thin film has been used as a model of the substrate surface. Lewis acidic molten salt, the ZnBr_2-NaBr melts at 623K, whose acidity can be controlled by the composition and the component have been used as a material for the liquid film.Metal oxide film was prepared on the glass substrate by a reaction RF sputtering method of by an electrolytic oxidation of deposited metal thin film. The charged state of the metal oxide film obtained was determined by an streaming potential method. The measurements were performed at various solution acidity conditions.The acid-base properties of the ZnBr_2-NaBr melts at 623K were investigated on the basis of the electromotive force measurements of a zinc-zinc concentration cell. The following two chemical equilibria were postulated to describe the acid-base character of the melts:ZnBr_2 + Br^- = ZnBr_3^- K_1ZnBr_3^- + Br^- = ZnBr_4^<2-> K_2The equilibrium constants K_1 and K_2 are determined to be 5.0x10^2 and 1.0x10^2, respectively, at 623K. The acidity of ZnBr^-_NaBr melts is essentially weaker than that of bromoaluminate melts.