Method for prolonging a catalyst's life during hydrofluorination
View Patent ↗The invention provides an improved process to manufacture 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) by reacting 2-chloro-3,3,3,-trifluoropropene (HCFO-1233xf) with hydrogen fluoride, in the presence of a fluorination catalyst, where by using 2-chloro-3,3,3, -trifluoropropene (HCFO-1233xf) of high purity, the need to add an oxidizing agent (typically chlorine) to keep the catalyst active can be avoided. The HCFC-244bb is then used as an intermediate in the production of 2,3,3,3-tetrafluoropropene-1 (HFO-1234yf).
1. A process for the production of 2,3,3,3-tetrafluoropropene comprising:
(i) fluorination of a starting material comprising 1,1,2,3-tetrachloropropene and/or 1,1,1,2,3-pentachloropropane with hydrogen fluoride to produce an intermediate stream comprising 2-chloro-3,3,3-trifluoropropene and 2,3-dichloro-3,3-difluoropropene;
(ii) purifying the intermediate stream comprising 2-chloro-3,3,3-trifluoropropene to produce a feed stream comprising at least 99% by weight of 2-chloro-3,3,3-trifluoropropene based on the organics in the feed stream;
(iii) reacting the feed stream comprising at least 99% by weight of 2-chloro-3,3,3-trifluoropropene based on the organics in the feed stream with hydrogen fluoride and a fluorination catalyst in the absence of an oxidizing agent to produce 2-chloro-1,1,1,2-tetrafluoropropane; and
(iv) dehydrohalogenating the 2-chloro-1,1,1,2-tetrafluoropropane under conditions effective to produce 2,3,3,3-tetrafluoropropene.
2. The process of claim 1 wherein the feed stream is produced by a process comprising fluorinating 1,1,2,3,-tetrachloropropene and/or 1,1,1,2,3-tetrachloropropane and separating 2-chloro-3,3,3-trifluoropropene from an intermediate stream comprising 2-chloro-3,3,3-trifluoropropene and one or more impurities.
3. The process of claim 2 wherein said at least one impurity is 2,3-dichloro-3,3-trifluoropropene.
4. The process of claim 2 wherein the step of separating 2-chloro-3,3,3-trifluoropropene from one or more impurities is performed by distillation.
5. A process for producing 2,3,3,3-tetrafluoropropene comprising
(i) fluorinating 1,1,2,3,-tetrachloropropene and/or 1,1,1,2,3-tetrachloropropane to produce an intermediate stream comprising 2-chloro-3,3,3-trifluoropropene and 2,3-dichloro-3,3-difluoropropene;
(ii) separating 2-chloro-3,3,3-trifluoropropene from the intermediate stream by distillation to form a feed stream comprising at least about 99% by weight of organics of 2-chloro-3,3,3-trifluoropropene;
(iii) reacting said feed stream with hydrogen fluoride and a fluorination catalyst in the absence of an oxidizing agent to produce 2-chloro-1,1,1,2-tetrafluoropropane; and
(iv) dehydrohalogenating the 2-chloro-1,1,1,2-tetrafluoropropane under conditions effective to produce 2,3,3,3-tetrafluoropropene.