Non-isothermal decomposition of rhodium acetate monohydrate - a kinetic and thermodynamic study

The non-isothermal decomposition of rhodium acetate monohydrate (Rh(CH3COO)(2). H2O) was studied on heating to the formation of rhodium metal at 400 degrees C in N-2 atmosphere using thermogravimetry (TGA), derivative thermogravimetry (DTG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). X-ray powder diffraction and IR spectroscopy were used for identification of the solid decomposition products. The variation of the rate of heating was used to calculate the activation energy (E-a) and the frequency factor (In A) for the dehydration and the decomposition processes. In addition, the enthalpy (Delta H), heat capacity (C-p) and the entropy (Delta S) changes were also calculated from the DSC measurements. The final mass loss after complete decomposition was found to increase appreciably with increasing of the heating rate. The activation energy (E-a) together with the enthalpy (Delta H) were found to be relatively small compared with those reported for some other reducible metal acetates. (C) 2000 Elsevier Science B.V. All rights reserved.