Kinetic and quantitative studies of the formation of SO2 from iron(II) and calcium sulfates by sequential and fractionated pyrolysis

Abstract The formation rates of sulfur dioxide were studied when iron and calcium sulfates were pyrolyzed sequentially at different temperatures in order to calculate the activation energies and frequency factors. These will be used to provide qualitative information concerning the formation of SO 2 when different coals are pyrolyzed. It is possible to calculate the pyrolysis temperature needed to degrade the salts totally in a fixed time. In practice the temperature had to be higher to obtain close to 100% conversion, probably due to effects from the platinum filament. The activation energies and frequency factors were 220 ± 5 kJ mol −1 and 10 12 s −1 for FeSO 4 · 7H 2 O and 205 ± 5 kJ mol −1 and 10 7 s −1 for CaSO 4 · 2H 2 O. The yield of sulfur dioxide at different temperatures and the influence of sample size were also studied. Fractionated pyrolyses were carried out in order to quantify the two sulfates in a blend.