Hydrolysis and oxidation on supported phosphate catalyst for decomposition of SF6

In order to decompose SF6, AlPO4/γ-alumina catalysts were prepared by the impregnation method and their catalytic activity for simultaneous hydrolysis and oxidation reactions was investigated in this study. SF6 can be decomposed by catalytic hydrolysis and oxidation. Alumina catalysts have high activity for the decomposition of SF6. However, γ-Al2O3 is deactivated during the hydrolysis and oxidation of SF6, due to the phase transformation of γ-alumina to α-alumina and AlF3. It was confirmed that the stability of the catalyst can be enhanced by using phosphoric acid impregnated over γ-alumina. The impregnation of phosphoric acid over γ-alumina led to the formation of AlPO4 on the surface of the catalyst. The most suitable amount of phosphoric acid on γ-alumina was 4.8 wt%. The surface area of the AlPO4/γ-alumina catalyst decreased with increasing amount of phosphoric acid impregnated over γ-alumina and the catalytic activity was also decreased due to the reduction of the surface area. The minimum space velocity should be kept below 5000 ml/gcat h in order to obtain the maximum efficiency of AlPO4/γ-alumina at 750 °C. It was concluded that AlPO4/γ-alumina can be used as a catalyst for the decomposition of SF6 by simultaneous hydrolysis and oxidation.