Metal sulfate catalyst for CCl2F2 decomposition in the presence of H2O

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 Al-2(SO4)(3), La-2(SO4)(3), Ce-2(SO4)(3), and Cr-2(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.