Catalytic decomposition of CFCs

Abstract

Catalytic decomposition of CCI₂F₂ was studied over a number of single and complex metal oxides using a fixed-bed reactor. The ZrO₂–Cr₂O₂ catalyst exhibited the highest activity and CO₂ and CCIF₃ were formed at 350–450°C. Selective decomposition of CCI₂F₂ 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. CCI₂F₂ was decomposed at 300–450°C over AIPO₄. No fluorination of the AIPO₄ catalyst took place after the reaction for 1000 h. CH₂FCF₃, an alternative CFC, was completely decomposed over the mixed catalyst of Ce promoted AIPO₄ and Cr₂O₃ at 400–500°C. Catalytic decomposition is a rational method for destruction of used CFCs.