The mechanism of thermal decomposition of aluminum sulfate has been investigated in the 500–700°C temperature range using a flow reactor system with the emitted gaseous sulfur oxides collected in a Goksøyr—Ross coil and a hydrogen peroxide impinger. Sulfur trioxide (SO3) was found to be the primary sulfur oxide released during thermal decomposition (1). Less than 3% of the released sulfur oxides were sulfur dioxide (SO2), indicating that the SO3 dissociation reaction (2) is slow relative to the residence time of the SO3 in the reactor (～ 1 sec). The experimental technique should be readily adaptable to the study of the thermal decomposition of other metal sulfates.
