THE NONISOTHERMAL DECOMPOSITION OF COBALT ACETATE TETRAHYDRATE - A KINETIC AND THERMODYNAMIC STUDY

The non-isothermal decomposition of cobalt acetate tetrahydrate was studied up to 500-degrees-C by means of TG, DTG, DTA and DSC techniques in different atmospheres of N2, H-2 and in air. The complete course of the decomposition is described on the basis of six thermal events. Two intermediate compounds (i.e. acetyl cobalt acetate and cobalt acetate hydroxide) were found to participate in the decomposition reaction. IR spectroscopy, mass spectrometry and X-ray diffraction analysis were used to identify the solid products of calcination at different temperatures and in different atmospheres. CoO was identified as the final solid product in N2, and Co3O4 was produced in air. A hydrogen atmosphere, on the other hand, produces cobalt metal. Scanning electron microscopy was used to investigate the solid decomposition products at different stages of the reaction. Identification of the volatile gaseous products (in nitrogen and in oxygen) was performed using gas chromatography. The main products were: acetone, acetic acid, CO2 and acetaldehyde. The proportions of these products varied with the decomposition temperature, and the prevailing atmosphere. Kinetic parameters (e.g. E and In A) together with thermodynamic functions (e.g. DELTAH, C(p) and DELTAS) were calculated for the different decomposition steps.