SPECTROTHERMAL INVESTIGATION OF THE DECOMPOSITION COURSE OF LANTHANUMACETATE HYDRATE

Thermogravimetry, differential thermal, X-ray diffraction and infrared spectroscopy analyses showed La(CH3COO)3.1.5H2O to decompose complete ly at 700-degrees-C yielding La2O3. The results revealed that the comp ound dehydrates in two steps at 130 and 180-degrees-C, and recrystalli zes at 210-degrees-C. Water thus produced hydrolyzes surface acetates (at 310-degrees-C), releasing acetic acid into the gas phase. At 334-d egrees-C, the anhydrous acetate releases gas phase CH3COCH3 to give La 2(CO3)3 residue, which decomposes to La2O2(CO3) via the intermediate L a2O(CO3)2. On further heating up to 700-degrees-C, La2O3 is formed. IR spectroscopy of the gaseous products indicated a chemical reactivity at gas/solid interfaces formed throughout the decomposition course. As a result, CH3COCH3 was involved in a surface-mediated, bimolecular re action, releasing CH4 and C4H8 (isobutene) into the gas phase. Non-iso thermal kinetic parameters, the rate constant k, frequency factor A, a nd activation energy DELTAE, were calculated on the basis of temperatu re shifts experienced in the thermal processes encountered, at various heating rates (2-20 deg.min-1).