CHARACTERIZATION OF THE DECOMPOSITION COURSE OF NICKEL ACETATE TETRAHYDRATE IN AIR

Thermogravimetry, differential thermal analysis, X-ray diffractometry and infrared spectroscopy showed that Ni(CH3COO)2.4H2O decomposes comp letely at 500-degrees-C, giving rise to a mixture of Ni(o) and NiO. Th e results revealed that the compound undergoes dehydration at 160-degr ees-C and melts at 310-degrees-C. The water thus released hydrolyses s urface acetate groups, acetic acid being evolved into the gas phase. A t 330-degrees-C, the anhydrous acetate is converted into NiCO3, releas ing CH3COCH3 into the gas phase. The carbonate subsequently decomposes (at 365-degrees-C) to give NiO((s)), CO2(g) and CO((g)). On further h eating up to 373-degrees-C, a mixture of Ni(o) and NiO is formed. Othe r gas-phase products were detected at 400-degrees-C, viz. CH4 and (CH3 )2CH = CH2, which were formed in surface reactions involving initial g as-phase products. Non-isothermal kinetic parameters (A and DELTAE) we re calculated on the basis of temperature shifts experienced in the va rious decomposition processes as a function of heating rate (2-20 deg. min-1).