Novel Chlorination of Zirconium Dioxide at Low Temperature

Low-temperature chlorination of zirconium dioxide using molybdenum pentachloride has been investigated below 773 K. The chlorination ratio was measured by chemical analysis, and the products were identified by powder X-ray diffraction. The results indicated that substitution of chlorine using molybdenum pentachloride significantly reduces the reaction temperature. Almost all the zirconium dioxide was converted to chloride in 30 minutes at 668 K when the molar ratio of molybdenum pentachloride to zirconium dioxide exceeded two. The chlorination reaction between zirconium dioxide and molybdenum pentachloride was shown to be a three-dimensional diffusion reaction satisfying the Jander equation, and the activation energy was 67 kJ/mole. Chlorination at a practical reaction rate using molybdenum pentachloride was realized at much lower reaction temperature than that using chlorine gas and carbon.