Influence of temperatures and starting materials used to prepare α-Fe2O3 on its catalytic activity at the thermal decomposition of KClO4

In order to elucidate the influence of preparative history of α-Fe₂O₃ on its reactivity, the catalytic thermal decomposition of KClO₄ by α-Fe₂O₃ was studied by means of DTA and X-ray techniques. The catalysts were prepared by the calcination of three iron salts, Fe(OH)(CH₃COO)₂, FeSO₄ ? 7H₂O and Fe₂(SO₄)₃ ? αH₂O, at temperatures of 500–1200°C in air. The lower the preparation temperature of αFe₂O₃, the larger the specific surface area and reversely the smaller the crystalline size. KClO₄ without α-Fe₂O₃ was found to begin fusion and decomposition simultaneously at about 530°C. The addition of αFe₂O₃ resulted in promotion of the decomposition reaction of KClO₄; a lowering of 30–110°C in the initial decomposition temperature and a solid-phase decomposition before fusion of KClO₄. The influence of preparative history of α-Fe₂O₃ on the decomposition mainly depended on the preparation temperature rather than the starting material. The initial decomposition temperature of KClO₄ increased with an increase of the preparation temperature of α-Fe₂O₃. The effect of α-Fe₂O₃ was discussed on the basis of the charge transfer and the oxygen abstraction models.