| 摘要 |
<p>Hexafluoroacetone is prepd. continuously by gas phase fluorination of hexachloroacetone with anhydrous HF, using a catalyst comprising gamma-Al2O3 impregnated with Cr2O3, to give 1.5-4 Cr atoms/1 of Al2O3, and activated at 300-400 deg.C with a mixt. of HF and 1,1,1-trichloro-1,2,2-trifluoroethane. Fluorination is in 2 stages, the 1st involving reaction of HF and recycled prods. including chlorofluoroacetones at 330-370 deg.C and the 2nd involving reaction at 28-320 deg.C of a mixt. of gaseous effluent from the 1st stage and fresh hexachloroacetone; the molar ratio of HF fed in the 1st stage; haloacetones fed in the 2nd stage is 3-5. - Hexafluoroacetone is recovered from the gaseous effluent from the 2nd stage, and other haloacetones are recycled to the 1st stage.</p> |
