| abstract |
A CATALYST IS DISCLOSED FOR THE PREPARATION OF FLUORINATED HYDROCARBONS VIA FLUORINATION OF CHLOROFLUORINATION REACTIONS IN GASEOUS PHASE, THE CATALYST CONSISTING ESSENTIALLY OF ALUMINUM FLUORIDE CONTAINING MINOR, QUANTITIES OF IRON, CHROMIUM, AND PREFERABLY ALSO NICKEL COMPOUNDS, PRESENT IN QUANTITIES CORRESPONDING TO THE FOLLOWING PRECENTAGES BY WEIGHT OF THE METAL (BASED ON THE TOTAL): FROM 0.1% TO 5% OF FE, FROM 0.05% TO 8.5% AT LEAST PARTIALLY, IN THE FORM OF HALIDES, AND IN PARTICULAR FLUORIDES, OR IN THE FORM OF OXIDES OR OXY-HALIDES. THE CATALYST IS PREPARED BY ADDING IRON OR CHROMIUM COMPOUNDS, AND PREFERABLY ALSO NICKEL COMPOUNDS, IN A SUBDIVIDED FORM, TO ALUMINUM FLUORIDE OR ALUMINA, AND THEN SUBJECTING THE COMPOSITION THUS OBTAINED TO AN ACTIVATION TREATMENT BY HEATING AT A TEMPERATURE BETWEEN 300*C. AND 550*C. FOR FROM 0.5-4 HOURS IN A CURRENT OF NITROGEN OR AIR, AND THEN SUBJECTING SAID COMPOSITION TO A FLUORINATION TREATMENT BY HEATING AT 200*-500*C. IN AN HF CURRENT, SIUTABLY DILUTED WITH INERT GASES FOR THE THERMAL CONTROL OF THE REACTION, IN ORDER TO CONVERT, AT LEAST PARTIALLY, THE ALUMINA AND POSSIBLY ALSO THE OTHER METAL COMPOUNDS INTO THEIR RESPECTIVE FLUORIDE. THE CATALYST THUS OBATAINED IS IMPLOYED FOR THE FLUORINATION IN GASEOUS PHASE AT ELEVATED TEMPERATURES OF HALOGENATED ETHANES CONTAINING AT LEAST ONE CHLORINE ATOM, IN ORDER TO OBTAIN HIGH YIELDS IN FUORINATED ETHANES HAVING A HIGH DEGREE OF SYMMETRY, BY MEANS OF HF, OR FOR THE CHLOROFLUORINATION IN GASEOUS PHASE AT ELEVATED TEMPERATURES OF ETHYLENE OR PARTIALLY HALOGENATED ETHYLENES BY MEANS OF A MIXTURE OF HF+CL2, IN ORDER TO OBTAIN FLUORINATED OR CHLOROFLUORINATED ETHANES WITH A HIGH DEGREE OF SYMMETRY. |