DECOMPOSITION OF CFC113 OVER TIO2-BASED C ATALYSTS

It is becoming increasingly important to decompose chlorofluorocarbons (CFCs) which destruct ozone layer. Catalytic decomposition process is expected to be an effective method which can be operated at lower tem peratures ii catalyst of high activity and durability is developed. CF C113 decomposition activities with H2O by metal oxide catalysts were i nvestigated. Among them, TiO2 catalyst showed high activity for decomp osition. But the activity was decreased to 97% after 2 h. To maintain high activity, another metal oxide (WO3, ZrO2, Nb2O5) was added to TiO 2. High decomposition activity was kept by TiO2-WO3 catalyst for 2 h. Measurement of acid amounts for these TiO2-based catalysts showed that TiO2-WO3 catalyst has more acidity of H-0 less than or equal to-5.6 t han TiO2 does. From these results, it was assumed that acidity of H-0 less than or equal to-5.6 had durability against decomposition reactio n of CFC and it has become clear that the CFC decomposition activity i s closely related to the amount of acid sites over catalytic surface. Durability test for continuous decomposition of CFC113 over TiO2-WO3 c atalyst was carried out and the conversion of CFC113 during 100 h was above 99.5%. It was shown that TiO2-WO3 catalyst had long durability a gainst decomposition of CFC113.