Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Some physico-chemical and catalytic properties of nickel oxide-vanadium pentoxide two-component catalysts were studied over the entire concentration region of the components, using the decomposition of hydrogen peroxide in aqueous solution as the test reaction. The two oxides were found to affect each other, which appeared in the dependences of the specific surface area, the V⁴⁺ ion concentration, and the catalyst activity on the system composition. At low vanadium pentoxide concentrations (up to 15 mol%) the reaction takes place on nickel oxide modified with vanadium pentoxide, whereas in the region of higher vanadium pentoxide concentrations the decomposition of the peroxide is catalyzed primarily in the homogenous phase by vanadium (V) peroxide ions; in sample with 30 mol% V₂O₅, trivalent vanadium also plays a part. With catalysts obtained by a mere mechanical mixing of the two oxides, a modified activity was observed in the region of high excess of nickel oxide. The activity of catalyst, particularly pure nickel oxide, is increased by its partial reduction and decreased by its exposition to gamma radiation if the dose is higher than 10⁵ Gy. The effects observed are interpreted in terms of the concept of bivalent catalytic centres.