Thermoanalytic study of some metal propionates synthesised by sol–gel route: a kinetic and thermodynamic study

Abstract The thermal decomposition reactions of lanthanum (III) and nickel (II) propionates, under different atmospheres, were studied in the temperature range of 25–800 °C using a thermogravimetry and differential thermal analysis. Thermal decomposition runs were performed under air, nitrogen and hydrogen. Solids analysis resulting from the precursors decomposition were characterised by infrared spectroscopy and X-ray diffractometry while gases were analysed using gas chromatography combined with mass spectrometry. Non-isothermal kinetic ( A and Δ E ) and thermodynamic parameters (Δ H , Δ S and Cp) for each process were determined. Under N 2 , the final products NiO and La 2 O 3 crystallised at temperatures of ≈310 and 720 °C respectively. Mixed metal carbonate–oxide phases were observed as intermediate solid products. Gas phase products included mainly CO and CO 2 with a ratio which vary with decomposition temperature and atmosphere.