Process for recovering pentafluoroethane
| Title: | Process for recovering pentafluoroethane |
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| Patent Number: | 5,919,340 |
| Publication Date: | July 06, 1999 |
| Appl. No: | 08/776,942 |
| Application Filed: | February 14, 1997 |
| Abstract: | There is provided a process of effectively separating pentafluorethane (HFC-125) out of a mixture of HFC and chloropentafluoroethane (CFC-115). When the mixture of HFC-125 and CFC-115 is subjected to extractive distillation so as to obtain concentrated HFC-125, methanol, ethanol, butanol, propyl alcohol, pentafluoropropanol, tetrafluoropropanol or acetone is used as an extractant, whereby CFC-115 is obtained as a distillate product and a mixture of HFC-125 and the extractant is separated from HFC-125 by distilling the mixture and re-used in the extractive distillation. |
| Inventors: | Kohno, Satoru (Osaka, JPX); Shibanuma, Takashi (Osaka, JPX) |
| Assignees: | Daikin Industries Ltd. (Osaka, JPX) |
| Claim: | We claim |
| Claim: | 1. A process of recovering pentafluoroethane by subjecting a mixture comprising at least pentafluoroethane and chloropentafluoroethane to an extractive distillation step so as to obtain pentafluoroethane which does not substantially contain chloropentafluoroethane, which process is characterized by |
| Claim: | supplying the mixture to the extractive distillation step |
| Claim: | supplying, as an extractant to the extractive distillation step, nitromethane |
| Claim: | obtaining a mixture comprising pentafluoroethane and the extractant which together constitute a main component of the mixture as a bottom product from the extractive distillation step, or a mixture comprising pentafluoroethane as a main component of the mixture as a distillate product from the extractive distillation step. |
| Claim: | 2. The process according to claim 1 wherein the mixture and the extractant are mixed together, which is then supplied to the extractive distillation step. |
| Claim: | 3. The process according to claim 1 or 2 wherein a weight ratio (S/F) of the extractant (S) used in the extractive distillation step to pentafluoroethane and chloropentafluoroethane (F) which are contained in the mixture to be supplied to the extractive distillation step is in the range between 0.1 and 10. |
| Claim: | 4. The process according to claim 1 wherein pentafluoroethane is separated by distilling the mixture as the bottom product comprising pentafluoroethane and the extractant which together constitute the main component of the mixture, whereby a mixture which contains the extractant as a main component thereof is recovered and re-used in the extractive distillation step. |
| Claim: | 5. The process according to claim 1 wherein the extractant makes a relative volatility (.alpha.) between pentafluoroethane and chloropentafluoroethane not larger than one. |
| Current U.S. Class: | 203/57; 203/98; 570/178 |
| Current International Class: | B01D 334 |
| Patent References Cited: | 3101304 August 1963 Wiist 3282801 November 1966 Wiist 3689374 September 1972 Hanson 5087329 February 1992 Felix 5200431 April 1993 Dattani et al. 5470442 November 1995 Mahler et al. |
| Primary Examiner: | Dentz, Bernard |
| Assistant Examiner: | Dahlen, Garth M. |
| Attorney, Agent or Firm: | Birch, Stewart, Kolasch, & Birch, LLP |
| Accession Number: | edspgr.05919340 |
| Database: | USPTO Patent Grants |
| Language: | English |
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