CONVERSION OF CHLOROFLUOROCARBONS IN GASEOUS-MIXTURES UNDER THE ACTION OF MICROWAVE DISCHARGES

The conversion of chlorofluorocarbons (CFCs) in various gaseous mixtur es under the action of pulsed microwave discharges is studied. Particu lar attention is given to CF2Cl2 + Ar mixtures at high pressures. The efficiency with which CFCs are converted into compounds that do not de stroy atmospheric ozone is determined. The resulting products are iden tified, and the particle balance in evolving gaseous mixtures is analy zed. It is shown that the conversion of CFCs occurs mainly via chemica l reactions between vibrationally and/or electronically excited CFC mo lecules, accompanied by the production of CF3Cl and CF4 halocarbons, w hich contain a large amount of fluorine and do not weaken the ozone la yer (the fraction of CFCs that are converted into these compounds is 7 0%). Chlorine atoms released in these reactions form Cl-2 molecules. F urther on, fluorine molecules are involved in reactions resulting in t he production of silicon tetrafluoride (SiF4), which is deposited on t he walls of a glass reactor, as is molecular carbon. The volume of the region in which initial CFC molecules are destroyed is shown to be mu ch larger than the volume of the energy release region. In this case, both the instability of the discharge and its contraction play a domin ant role because the radiation emitted by a contracted dense hot plasm a excites CFC molecules in the surrounding gaseous medium. The results of our investigations show that microwave gaseous discharges are prom ising as a means of removing ozone-destroying CFCs from the atmosphere and as an efficient industrial method for converting ozone-destroying halocarbons (CFC-11 and CFC-12) into relatively harmless compounds.