Catalytic decomposition of CFCs

Catalytic decomposition of CCl₂F₂ was studied over a number of single and complex metal oxides using a fixed-bed reactor. The ZrO₂-Cr₂O₃ catalyst exhibited the highest activity and CO₂ and CClF₃ were formed at 350 450°C. Selective decomposition of CCl₂F₂ into CO₂ required the presence of both oxygen and water vapor over the catalyst. Catalytic activity gradually declined with time on stream because of the fluorination of ZrO₂. Treatment of the catalyst with both oxygen and water vapor promoted the removal of fluoride ions in sub-surface layers of the catalyst, which is effective for the recovery of the activity. CCl₂F₂ was decomposed at 300-450°C over AlPO₄. No fluorination of the AlPO₄ catalyst took place after the reaction for 1000 h. CH₂FCF₃, an alternative CFC, was completely decomposed over the mixed catalyst of Ce promoted AlPO₄ and Cr₂O₃ at 400-500°C. Catalytic decomposition is a rational method for destruction of used CFCs.