Studies on the thermal decomposition kinetics and mechanism of ammonium niobium oxalate

Abstract

Ammonium niobium oxalate was prepared and characterized by elemental analysis, XRD and FTIR spectroscopy analysis, which confirmed that the molecular formula of the complex is NH4(NbO(C2O4) 2(H2O)2)(H2O)3. Dynamic TG analysis under air was used to investigate the thermal decomposition process of synthetic ammonium niobium oxalate. It shows that the thermal decomposition occurs in three stages and the corresponding apparent activation energies were calculated with the Ozawa-Flynn-Wall and the Friedman methods. The most probable kinetic models of the first two steps decomposition of the complex have been estimated by Coats-Redfern integral and the Achar-Bridly-Sharp differential methods. © 2009 Akadémiai Kiadó, Budapest, Hungary.