Kinetics of thermal decomposition of lanthanum oxalate hydrate

Lanthanum oxalate hydrate La2(C2O4)3·10H2O, the precursor of La2O3 ultrafine powders, was prepared by impinging stream reactor method with PEG 20000 as surfactant. Thermal decomposition of La2(C2O4)3·10H2O from room temperature to 900 °C was investigated and intermediates and final solid products were characterized by FTIR and DSC-TG. Results show that the thermal decomposition process consists of five consecutive stage reactions. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods were implemented for the calculation of energy of activation (E), and the results show that E depends on α, demonstrating that the decomposition reaction process of the lanthanum oxalate is of a complex kinetic mechanism. The most probable mechanistic function, G(α)=[1−(1+α)1/3]2, and the kinetic parameters were obtained by multivariate non-linear regression analysis method. The average E-value that is compatible with the kinetic model is close to value which was obtained by FWO and KAS methods. The fitting curve matches the original TG curve very well.