The Thermal Decomposition of Aluminum Sulfate and Hafnium Sulfate

Abstract

The thermal decomposition of aluminum sulfate and hafnium sulfate was studied in air by thermogravimetric analysis (TG) and in vacuum by simultaneous TG and evolved gas analysis (EGA). No SO3 was detected by the mass spectrometer. The primary products of decomposition appear to be SO and O2 for both sulfates. For aluminum I sulfate, the Arrhenius relationship shows two activation energies, whereas for hafnium sulfate there is only 'one activation energy in vacuum and two activation energies in air. X-ray data show the solid products of the reaction to be η-Al2O3 and HfO2. The diffraction pattern for Hf(SO4)2 · 4H2O is presented.