Host: The Society of Chemical Engineers, Japan
Since fluorocarbons containing chlorine atoms deplete the ozone layer, the production of chlorinated fluorocarbons (CFCs) has been banned. At present, hundreds of thousands tons of CFCs are regarded as harmful wastes. To solve a problem, we are proposing a new process that these chlorinated wastes are converted into useful compounds. Decomposition occurred by just bubbling CFC12 gas into alkali-alcohol solvents under UV irradiation. The conversion of dichlorodifluoromethane (CFC12) to 1,1-difluorodimethyl ether (DDE) was carried out in methanol-NaOH solution under UV irradiation. It is a consecutive reaction in a solution through two steps: the first step is the photo-dechlorination of CFC12 to chlorodifluoromethane (HCFC22), and the second is HCFC22 to DDE. At each step, NaCl is produced. In this work, we are mainly interested in the first step of CFC12 photo-dechlorination. Concentrations of CFC12 into solution were measured with gas chromatography. Experiments at 5.0°C showed that the flow rate of the gas mixture above 2.0 l/min did not affect the reaction. This means that the reaction was rate limiting above the flow rate 2.0 l/min. The reaction rate of photo-dechlorination was found to be proportional to partial pressure of CFC12 and square root of UV light intensity. Concentration of NaOH between 1.0 and 2.0 mol/l has no effects on reaction rate.
