Catalytic Hydrolysis of CFC-12 Over Cr203 Catalysts

The hydrolytic destruction of CF2Cl2over Cr2O3catalysts was investigated under varied reaction conditions with the CF2Cl2partial pressure in the range 0.0112-0.0224 atm., the water vapor pressure between 0.042-0.38 atm. and the reaction temperature in the range 400-475ºC. The effect of the preparation method and the modifying effect of sulfation with sulfuric acid on the catalytic behavior of Cr2O3were systematically studied. Optimum Cr2O3catalysts were obtained upon the sulfation of Cr2O3, prepared by the thermal decomposition of ammonium dichromate, with 0.20 M H2SO4solution. Reaction temperatures ≥450ºC are necessary to achieve high activities and high selectivities towards the hydrolysis reaction. Selectivities better than 90% and 100%-conversion could be obtained for dilute CF2Cl2inputs with large excess of water (PCF2Cl2= 0.0112-0.0134 atm., PH2O = 0.246 atm.). The efficiency of the process is, however, disturbed by the occurrence of kinetic oscillations that may show amplitudes as large as 50%-conversion.