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Production processes

a production process and process technology, applied in the field of production processes, can solve the problems of increasing the cost of hfc-125 production, new compounds that do not meet environmental safety requirements, and ineffective distillation of azeotropic mixtures as separation techniques

Inactive Publication Date: 2006-05-25
BRANDSTATER STEPHAN M +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides processes for the production of halogenated hydrocarbons and the purification of halogenated hydrocarbons from mixtures containing other compounds. The invention involves the use of extracting agents, such as hexafluoropropene or chlorotrifluoroethene, to purify halogenated hydrocarbons. The recovered extracting agents can be reused in other purification processes. The invention also includes the steps of adding halocarbons to the extracting agent to produce a mixture, distilling the mixture to separate the halogenated hydrocarbon, and recovering the halogenated hydrocarbon. The recovered halogenated hydrocarbon can then be used in other production processes. The invention provides efficient and effective methods for the production and purification of halogenated hydrocarbons.

Problems solved by technology

However, some of these new compounds do not meet environmental safety requirements.
CFC-115 is an undesirable compound because it contains chlorine, and, as a result, its use is highly regulated.
Regardless, a characteristic of azeotropes is that the bulk liquid composition is identical to the vapor composition in equilibrium therewith, and distillation of the azeotropic mixture is ineffective as a separation technique.
This additional separation process may add to the cost of HFC-125 production even though the extracting agent may be reused.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Screening of extracting Agents for Vapor Phase Separation of HFC-125 and CFC-115

[0025] A 50 cc stainless steel sample cylinder fitted with a pressure gauge and valve with a septum port was chilled to −78° C. and a known amount of HFC-125 and CFC-115 was charged to the cylinder. This mixture was shaken and allowed to warm to ambient temperature and the vapor phase was sampled for subsequent analysis by gas chromatography (GC).

[0026] The cylinder was then re-cooled to −78° C. and a desired amount of the chosen extraction solvent was added to the vessel. The mixture was then allowed to warm to ambient temperature, at which time, it was shaken and allowed to equilibrate for 3 to 12 hours before it was re-sampled for GC analysis.

[0027] All GC data of this and the following examples were taken by sampling a collection or storage vessel or the appropriate sample port with a 50 to 250 μL airtight syringe fitted with an on / off valve. This collected sample was injected on either an HP-5890...

example 2

Vapor Phase Separation of HFC-125 from CFC-115 Using HFP as an Extracting Agent

[0038] This procedure demonstrates the effective removal of CFC-115 from streams of the first mixture comprising HFC-125 and CFC-115, by the use of HFP as an extracting agent.

[0039] The apparatus used was a 92 in. packed, schedule 40, carbon steel distillation column fitted with a reboiler, overhead condenser, overhead reflux loop, timed take-off valves, and multiple feed points. This evacuated column was charged with 584 g of the first mixture comprising 97.928% of HFC-125 and 2.073% of CFC-115, by weight. This mixture was allowed to equilibrate at a reflux ranging from 14 to 29 cc / min. HFP was then fed into the column at an average rate of 1.98 g / min, while taking off CFC-115 and HFP at a rate of 1.75 g / min as the bottom product from the reboiler.

[0040] The operation was continued over 2348 minutes. The total amount of HFP added was 4438 g. During this time, the relative ratio of HFC-125 to CFC-115 i...

example 3

Purification of HFP

[0044] To demonstrate this process, 507 grams of a mixture containing 90.17% of HFP, 9.798% of HFC-125, and 0.025% of CFC-115 (see TABLE III) was charged to an apparatus consisting of a 92 in. packed, schedule 40, carbon steel distillation column fitted with a reboiler, overhead condenser, and overhead reflux loop. This mixture was allowed to equilibrate with a steady reflux for 224 minutes. The distillation was run at a pressure of about 122-123 psig. The boiler temperature was set at about 31.4° C., and the overhead temperature was set at about 27° C. The overhead and reboiler compositions were checked by GC analysis. The column was then equilibrated for another 100 minutes to obtain further homogeneity of the HFP in the reboiler of the column (see TABLE III). This demonstrates that the longer the distillation was run, the higher purity of HFP was obtained. This level of purity is acceptable for recycle to the HFC-125 extractive distillation system or to be use...

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Abstract

The present invention involves processes that utilize an olefinic compound, in particular, hexafluoropropene (HFP) or chlorotrifluoroethene (CFC-1113) as extracting agents in the purification of pentafluoroethane (HFC-125). These processes can utilize recovered HFP as a precursor for the production of heptafluoropropane (HFC-227) or other derivatives.

Description

FIELD OF INVENTION [0001] The present invention relates to processes for separating pentafluoroethane (CHF2-CF3, HFC-125) from a mixture comprising HFC-125 and chloropentafluoroethane (CF3-CClF2, CFC-115). The present invention further relates to the production of heptafluoropropane (CF3CHFCF3 or CF3CF2CHF2, HFC-227ea or HFC-227ca, collectively HFC-227). BACKGROUND OF THE INVENTION [0002] In the recent years, there has been an increasing concern about global warming. As a result, several chlorofluorocarbons (CFC's) that are known to have an adverse environmental impact have been removed from the marketplace. In their place, new compounds have been introduced as flooding agents, streaming agents, blowing agents, propellants, and refrigerants. However, some of these new compounds do not meet environmental safety requirements. Consequently, there is a constant need to develop fluorocarbon compounds, especially hydrofluorocarbons, which have no chlorine. Two hydrofluorocarbons that are ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01D3/34C07B61/00C07C17/087C07C17/21C07C17/383C07C17/386C07C19/08
CPCC07C17/087C07C17/21C07C17/383C07C17/386C07C19/12C07C19/08C07C21/18
Inventor BRANDSTATER, STEPHAN M.COHN, MITCHELHEDRICK, VICTORIA E.YUICHI, IIKUBO
Owner BRANDSTATER STEPHAN M