| 摘要 |
<p>Unsupported or supported chromium oxide catalyst is used in the reaction of 1,1,2-trichloro-1,2,2-trifluoroethane with hydrogen to give chlorotrifluoro ethylene (see Group IV(b)). The catalyst may be in the form of pellets and is prepared by precipitating chromium hydroxide from an aqueous solution of chromium nitrate by adding ammonium hydroxide and heating the precipitate. Supported catalysts may be prepared by soaking "Alundum" chips ("Alundum" is a Registered Trade Mark) in chromium nitrate and heating to 200 DEG C. or by precipitating chromium hydroxide on silica or calcium or magnesium fluoride and heating. Supported catalysts may contain 1-60% by weight of chromium oxide. A specified catalyst is prepared by adding a solution of potassium fluoride and potassium hydroxide to a solution of magnesium and chromium nitrates, boiling the mixture and drying the resulting precipitate at 120 DEG C. which is then granulated. Specification 698,386 is referred to.ALSO:Chloro-trifluoroethylene is made by heating a mixture of hydrogen and 1,1,2,-trichloro-1,2,2, trifluoroethane at 475-550 DEG C. in the presence of chromium oxide catalyst and in a reaction zone bounded by surfaces of alumina, porcelain, fused silica or zirconia, the mol ratio of trichloro-trifluoroethane to hydrogen being at least 1,25:1. In examples, 1,1,2 trichloro-1,2,2,-trifluoroethane is dechlorinated with hydrogen in mol ratios of (1) 2,1:1 with chromium oxide on "Alundum" (Registered Trade Mark) as catalyst in an "Alundum" tube and (2) 1,8:1 with the same catalyst and tube. Specification 698,386 is referred to.</p> |
