FORMATION OF PRASEODYMIUM OXIDE FROM THE THERMAL-DECOMPOSITION OF HYDRATED PRASEODYMIUM ACETATE AND OXALATE

Thermogravimetry, differential thermal analysis, infrared spectroscopy , X-ray diffractometry and surface area measurements were used to char acterize the thermal decomposition of the hydrated acetate and oxalate of praseodymium in air. Non-isothermal kinetic parameters (A, DELTAE) were determined for the thermal events monitored throughout the decom position course. The results showed that Pr(CH3COO)2.H2O became dehydr ated at 180-degrees-C, melted at 270-degrees-C and decomposed to PrO1. 833 at 575-degrees-C through intermediate oxy-carbonate compounds. In contrast, Pr2(C2O4)3.10H2O dehydrates completely in three steps by 390 -degrees-C, and then decomposes similarly to PrO1831. The oxide formed from the acetate precursor has a higher surface area (18 m2/g) than t hat obtained from the oxalate precursor (8 m2/g). The gas-phase decomp osition products identified by infrared spectroscopy are acetone, acet ic acid, carbon oxides, methane and isobutene. Some of these were init ial decomposition products, whereas others (methane and isobutene) wer e interfacial reaction products involving initial ones.