Development of MgO-based materials for destructive halogen absorption of chlorofluorocarbons

摘要

Destructive halogen absorption of CFC 12 by modified MgO was investigated. It was demonstrated that partially fluorination of MgO significantly enhanced CFC 12 decomposition mainly due to formation of active acidic sites on MgO and vanadium oxide deposition on MgO also enhanced CFC 12 decomposition with high selectivity to CO_2. Pathways for decomposition of CFC 12 were clearly different between two kinds of MgO-based materials: partially fluorinated MgO was capable to absorb only fluorine to form CCl_4, while vanadium oxides supported on MgO efficiently absorbed both fluorine and chlorine. The difference was considered to be brought by the ability for CCl_4 decomposition and chlorine absorption. In fact, partially fluorinated MgO exhibited low activity for CCl_4 decomposition and thus, it was essential to add transition metal oxide to achieve total decomposition of CFC 12 without halogen release.