In the decomposition of chlorofluorocarbons (CFCs), HF produced in the decomposition reacts with and deactivates the catalyst. Metal phosphates were chosen as the catalyst from ΔG calculations. Zr-P-O and AlPO4 showed high catalytic activity for the decomposition of CCl2F2 above 350°C. The essential reaction of the decomposition is hydrolysis. On increasing the CCl2F2 concentration in the feed, the formation of CClF3 as a by-product is promoted. ALPO4 has both weak acid sites and those of intermediate strength and these acid sites may participate in the hydrolysis of CCl2F2. No reaction between AlPO4 and formed HF was observed during 1000 h reaction at 400°C, ALPO4 promises to be of practical use.
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