Heterogeneously catalysed hydrolytic decomposition of CFCs - How to deal with CFCs still deposited in refrigerators and foams

The hydrolytic decomposition of dichlorodifluoromethane (CFC-12) on modifie d zirconium oxide surfaces and on charcoal has been studied. The reaction w as carried out under flow conditions at 450 degrees C. Complete CFC-12 conv ersion was obtained by employing a molar excess of water in the gas phase w hich depresses the formation of poisoning zirconium oxofluoride phases. The se phases are responsible for the formation of unwanted monochlorodifluorom ethane (CFC-13). The long-term stability of the catalysts was found to depe nd strongly on the CFC concentration in the gas phase. The lower the CFC co ncentration, the better the catalyst stability and catalytic activity. Pure charcoal can also be used as a catalyst for CFC hydrolysis. However, charc oal, owing to its reductive nature, may result in the formation of unwanted by-products and, thus, cannot be considered either as a serious catalyst n or as a suitable support.