Activities for the hydrolysis of CCl2F2 (CFC-12) on various metal sulfates were investigated in this study. It was found that Zr(SO4)2 exhibits a high activity for CFC-12 decomposition and a high selectivity to CO2. On the other hand, the metal sulfates Al2(SO4)3, La2(SO4)3, Ce2(SO4)3, and Cr2(SO4)3 were also active for the hydrolysis of CFC-12. However, the activities for CFC-12 decomposition of MnSO4, CoSO4, and MgSO4 were low, and decomposition of CFC-12 hardly occurred on the metal sulfates CaSO4, SrSO4, and BaSO4. Among the investigated metal sulfates, Zr(SO4)2 was the most active, and the complete decomposition of CFC-12 was achieved at 598 K. The CFC-12 decomposition rate monotonically increased with increasing CFC-12 partial pressure. On the other hand, CFC-12 conversion became highest at an oxygen content of 18.9 mol % and a H2O content of 5 mol %. Therefore, the main reaction on Zr(SO4)2 for CFC-12 decomposition into CO2 and HCl and HF is the hydrolysis reaction. The high activity to CFC-12 decomposition on Zr(SO4)2 was stably sustained over the 40-h period examined. Therefore, the metal sulfate Zr(SO4)2 is highly active for the hydrolysis of CFC-12 and has sufficient stability against fluorination and/or chlorination.
!!!All Science Journal Classification (ASJC) codes
- 化学 (全般)