Decomposition of chlorofluorocarbons over metal phosphate catalysts Part I. Decomposition of CCl2F2 over metal phosphate catalysts

Abstract

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.