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

The non-isothermal decomposition of cobalt acetate tetrahydrate was st udied 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. Tw o intermediate compounds (i.e. acetyl cobalt acetate and cobalt acetat e 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 tempe ratures and in different atmospheres. CoO was identified as the final solid product in N2, and Co3O4 was produced in air. A hydrogen atmosph ere, on the other hand, produces cobalt metal. Scanning electron micro scopy was used to investigate the solid decomposition products at diff erent stages of the reaction. Identification of the volatile gaseous p roducts (in nitrogen and in oxygen) was performed using gas chromatogr aphy. The main products were: acetone, acetic acid, CO2 and acetaldehy de. The proportions of these products varied with the decomposition te mperature, and the prevailing atmosphere. Kinetic parameters (e.g. E a nd In A) together with thermodynamic functions (e.g. DELTAH, C(p) and DELTAS) were calculated for the different decomposition steps.