The thermal decomposition of palladium acetate.

The enthalpy of the thermal decomposition of Pd(CH3CO2)2 was determined in air, nitrogen and vacuum. Thermogravimetry, differential thermal analysis, evolved gas analysis, differential scanning calorimetry, and infrared spectroscopy were used to characterize the process and products. In vacuum the trimeric solid volatilizes completely below 200C. At atmospheric pressure the material decomposes to Pd between 200 and 300C depending on the rate of heating. The apparent activation energy for this process is about 115 +- 5kJ mol-1 and the enthalpy is 440 +- 20kJ mol-1. In the presence of oxygen, however, oxidation of the ligands leads to an overall exothermic process. The resulting Pd then slowly oxidizes to PdO, up to the decomposition temperature of the oxide near 800C. There is a slight loss of a Pd containing species, presumably owing to sublimation or gas entrainment, during the decomposition below 300C. The extent of this loss increases with increasing heating rate, approaching 10% of the total Pd at heating rates of 64C min- 1.