CN1266097C - Purification method of pentafluoroethane - Google Patents
Purification method of pentafluoroethane Download PDFInfo
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- CN1266097C CN1266097C CN 200410013989 CN200410013989A CN1266097C CN 1266097 C CN1266097 C CN 1266097C CN 200410013989 CN200410013989 CN 200410013989 CN 200410013989 A CN200410013989 A CN 200410013989A CN 1266097 C CN1266097 C CN 1266097C
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- compound
- extraction agent
- ethane
- purification
- pentafluorid
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Abstract
The present invention relates to a method for separating chloropentafluoroethane as an impurity in pentafluoroethane by an extraction agent to obtain high-purity pentafluoroethane, which belongs to the technical field of the purification of a chemical product. In the method, the chloropentafluoroethane as the impurity in the pentafluoroethane is separated off through extractive distillation by adopting at least one ester compound, at least one ketone compound, at least one alcohol compound and a mixture of the ester compound, the ketone compound and the alcohol compound as extraction agents, wherein a molecule of the ester compound or the ketone compound or the alcohol compound contains a halogen atom. The present invention has the advantages of high efficiency, low price of the extraction agents, easy acquirement of the extraction agents, and safe and circular use.
Description
Technical field
The present invention relates to a kind of method of purification of pentafluoride ethane, be specifically a kind ofly adopt extraction and distillation technology, in the presence of suitable extraction agent, separate impurity C2ClF5 in the pentafluoride ethane, to obtain the method for highly purified pentafluoride ethane, belong to Chemicals purification techniques field.
Background technology
Pentafluoride ethane is called for short HFC-125 or R125, is used as cooling agent, whipping agent and fire-fighting medium, has purposes widely.Owing to the specification of quality strictness (for example C2ClF5 in the pentafluoride ethane product---the content requirement that is called for short R115 is less than 0.1%) of pentafluoride ethane, therefore in preparation process, need in commercial the use through purification processes.
Industrial can be raw material with zellon, produce pentafluoride ethane with anhydrous hydrogen fluoride reaction.Its reaction formula is as follows:
Also can be with trifluorobichloroethane as raw material, with the method production of anhydrous hydrogen fluoride reaction, its reaction formula is as follows:
No matter adopt above that a kind of production method, in the product of pentafluoride ethane, can contain the C2ClF5 impurity of 0.2-2% inevitably.
Because not only boiling point is approaching for pentafluoride ethane and C2ClF5, and has azeotropism, therefore adopt conventional distillation technology to be difficult to it is separated fully.
At present, the common method that addresses this problem is an extraction fractional distillation.The key of this method is to select suitable extraction agent, promptly in the presence of suitable extraction agent impurity C2ClF5 in the pentafluoride ethane product is separated, to obtain highly purified pentafluoride ethane.For example, U.S. Pat 6307115 has been reported the method that adopts zellon to separate the purification pentafluoride ethane as extraction agent; U.S. Pat 6039845 has been reported the method that adopts the perfluor halogenated alkyl compounds to separate the purification pentafluoride ethane as extraction agent; US6179967 has then reported and has adopted boiling point to be-10-100 ℃ the ketone that only contains hydrogen, carbon atom, alkane derivatives such as ester class, ethers and alcohols---the method for separating the purification pentafluoride ethane as extraction agent as Skellysolve A, hexane, ether, acetone, ethyl acetate etc.Chinese patent CN1120828C reported with US6179967 in similar compound---with acetone, ring ethyl ketone, ethyl acetate, acetonitrile and their mixture as the sharp method of separating the purification pentafluoride ethane of extraction.Chinese patent CN1180345 discloses the method that contains the pentafluoride ethane of chloropentafluoroethane by liquid-liquid extraction or extractive distillation purification, and extraction agent uses tetrachloroethylene.
Though the method for above patent report respectively has its positive effect in industrial application, all exist some shortcomings, the extraction agent separating effect that has is not so good, and costing an arm and a leg of having is difficult to obtain, and has plenty of inflammable and explosive compound, exists serious potential safety hazard.The ketone that particularly has only hydrogen, carbon atom in the molecule that US6179967 and CN1120828C adopted, ethers, ester class, alcohol compound are as extraction agent, because the compound that these compounds all are low-flashes, very easily burn and explode, therefore need take strict security measures and security device when practical application, the result will certainly cause the increase of production cost.Therefore select some efficient, cheap being easy to get, safe and practical extraction agent still is the problem that people need solve.
Summary of the invention
The objective of the invention is: propose a kind of efficient, cheap and easy to get, and the extraction agent that can recycle safely, thus by extracting rectifying, separate the impurity C2ClF5 in the pentafluoride ethane, obtain the method for high-purity pentafluoroethane.
Understand easily, the key of extracting rectifying is to select suitable extraction agent.The extraction agent of a suitable practicality should meet following condition, can effectively improve the relative volatility of separated component, have enough chemical stabilities simultaneously, the isolating material generation chemical reaction of discord, in addition enough securities should be arranged, in industrial production, can use safely.
By further investigation, extensively select, the contriver of present patent application finds, adopts the ester class, ketone, alcohol compound and their mixture that contain halogen atom at least a molecule as extraction agent, separates impurity C2ClF5 in the pentafluoride ethane by extractive distillation.Can improve the relative volatility of pentafluoride ethane and C2ClF5 so on the one hand effectively, reach and separate purification pentafluoride ethane purpose.On the other hand since in molecule, contain halogen atom and not ester class, ketone, the ether compound of halogen atom-containing compare, its boiling point and flash-point all significantly improve, the possibility of burning and blast declines to a great extent, so can more safely be applied in the industrial production.
The above halogen-containing ester class, ketone and alcohol compound are the compounds of representing with following molecular formula:
X
nCH
3-nCO
2R X
nCH
3-nCOCH
3 X
nCH
3-nCH
2OH
Wherein X is a fluorine atom, a kind of in chlorine atom and the bromine atoms, and n is the integer of 1-3.R is a carbonatoms less than 4 alkyl group.
For the ease of analyzing, the present inventor is defined as follows C2ClF5/pentafluoride ethane relative volatility with reference to CN1098710A and CN1270156A:
In order to measure the relative volatility of each component, is 300ml with a diameter for the 50mm. volume, two ends have the stainless steel cylinder of sampling valve up and down, means as test, the extraction agent of 50ml is added in this steel cylinder, add the pentafluoride ethane product that about 100g contains 0.82% C2ClF5 again, leave standstill behind the steel cylinder that commoves, make to form in the bottle to reach balance.Detect the gas-liquid content of middle each component mutually respectively with gas-chromatography, and calculate relative volatility a value.
Table 1 listed various extraction agents under existing C2ClF5 and the relative volatility value of pentafluoride ethane, also listed the judgement criteria of the standard flash-point of various extraction agents simultaneously in this table as its security.
Table 1
| Extraction agent | Boiling point (℃) | Flash-point (℃) | Relative volatility a C2ClF5/pentafluoride ethane |
| Ethyl trichloroacetate | 160 | 65 | 3.25 |
| Methyl trichloroacetate | 152 | 72 | 3.10 |
| Trifluoroacetic Acid Ethyl Ester | 62 | -1 | 3.34 |
| Ethyl dichloroacetate | 3.46 | ||
| Ethyl chloride | 143 | 65 | 3.52 |
| Mix ester * | 3.61 | ||
| Ketone in one chlorine | 120 | 27 | 4.21 |
| Dichloro acetone | 118 | 24 | 4.40 |
| Trichloroacetone | 135 | 64 | 4.47 |
| Mix ketone * | 4.52 | ||
| Chloroethanol | 129 | 60 | 2.69 |
| Acetone ** | 51 | -17 | 3.48 |
| Ethyl acetate ** | 77 | -3 | 2.62 |
| Ethanol ** | 78 | 8 | 2.01 |
*: mixed ester is the mixture of 50% ethyl dichloroacetate and 50% ethyl trichloroacetate; Mixed ketone is the mixture of 40% Dichloro acetone and 60% trichloroacetone.
*: be the extraction agent of relevant patent report
As can be seen from the above table data, when using the ester that contains halogen atom in the molecule, ketone, alcohol compound as extraction agent, with ester, ketone, the alcohol compound of halogen atom-containing are not compared, relative volatility aR115/R125 has increase by a relatively large margin on the one hand, and this ester, ketone, alcohols chemical combination that shows these halogen atom-containings has higher effect of extracting; On the other hand, from the flash-point data as can be seen, after containing halogen atom in the molecule, its flash-point also significantly improves, the danger of its burning and blast declines to a great extent when showing halogen-containing ketone, ester, alcohol compound as extraction agent, and is therefore more safe and reliable when industrial application.
In operation, usage quantity to extraction agent does not have special requirement, but effect of extracting can improve along with the increase of extraction agent usage quantity usually, the mol ratio of general extraction agent and required separation of material is 0.2-4: 1, better be 0.5-3: 1, usually the extraction agent usage quantity is crossed low meeting influence effect of extracting, and the extraction agent consumption is crossed conference increases power consumption and running cost.
In industrial application, abstraction distillation system is made up of an extraction and fractionation tower and an extraction agent recovery tower of taking back flow condenser usually.Required in the present invention isolating C2ClF5/pentafluoride ethane mixture can add continuously from the middle part of extraction tower, extraction agent adds from the top of extraction and fractionation tower, be adjusted to certain reflux ratio, just can collect the material of enrichment C2ClF5 from the return line of reflux exchanger.Draw the material of the enrichment pentafluoride ethane that contains extraction agent from the tower still, and from the bottom adding extraction agent recovery tower of extraction agent recovery tower, collect highly purified C2ClF5 product from trim the top of column condenser return line, the extraction agent in the tower still recycles in the extraction and fractionation tower with pump delivery.
Experiment showed, repeatedly and adopt method of the present invention, the content of C2ClF5 can be less than 0.10% in the pentafluoride ethane product after extracting and separating.
Embodiment
Embodiment one
In a separation column that wire packing is housed, add the pentafluoride ethane product that contains 0.82% C2ClF5 from the tower middle part, add the extraction agent Mono Chloro acetone again from tower top, in the control tower still temperature about 45 ℃, and total reflux.Liquid level arrives a half in the tower still, collects the fraction of enrichment C2ClF5 from return line.Material in the tower still is introduced in the extraction agent recovery tower, and extraction agent reclaims Tata still temperature and is controlled at about 45 ℃.Collect the pentafluoride ethane product from the overhead condenser return line, the extraction agent in the tower still is circulated in the extraction and fractionation tower with pump, and the content that detects C2ClF5 in the pentafluoride ethane product of collecting is 0.03%.
Embodiment 2
With embodiment 1 identical operations, only change extraction agent into ethyl chloroacetate, the content of five fluorine fluoroethanes is 0.04% in the pentafluoride ethane product that obtains.
Embodiment 3
With embodiment 1 identical operations, only change extraction agent into chloroethanol, the content of C2ClF5 is 0.03% in the pentafluoride ethane product that obtains.
Embodiment 4
With embodiment 1 identical operations, only change extraction agent into Trifluoroacetic Acid Ethyl Ester, the content of C2ClF5 is 0.05% in the pentafluoride ethane product that obtains.
Embodiment 5
With embodiment 1 identical operations, only extraction agent is changed into the mixture of the trichloroacetone that contains 40% Dichloro acetone and 60%, the content of C2ClF5 is 0.02% in the pentafluoride ethane product that obtains.
Claims (6)
1. purification of ethane pentafluorid, it is characterized in that: adopt the ester class, ketone, alcohol compound and their mixture that contain halogen atom at least a molecule as extraction agent, separate impurity C2ClF5 in the pentafluoride ethane by extractive distillation.
2. according to the described purification of ethane pentafluorid of claim 1, it is characterized in that: described halogen-containing ester compound is the compound of representing with following molecular formula:
X
nCH
3-nCO
2R wherein X is a fluorine atom, a kind of in chlorine atom and the bromine atoms, and n is the integer of 1-3, R is a carbonatoms less than 4 alkyl group.
3. according to the described purification of ethane pentafluorid of claim 1, it is characterized in that: described halogen-containing ketone compounds is the compound of representing with following molecular formula:
X
nCH
3-nCOCH
3Wherein X is a fluorine atom, a kind of in chlorine atom and the bromine atoms, and n is the integer of 1-3.
4. according to the described purification of ethane pentafluorid of claim 1, it is characterized in that: described halogen-containing alcohol compound is the compound of representing with following molecular formula:
X
nCH
3-nCH
2OH wherein X is a fluorine atom, a kind of in chlorine atom and the bromine atoms, and n is the integer of 1-3.
5. according to claim 1,2,3 or 4 described purification of ethane pentafluorid, it is characterized in that: the mol ratio of described extraction agent and required separation of material is 0.2-4: 1.
6. according to claim 1,2,3 or 4 described purification of ethane pentafluorid, it is characterized in that: the mol ratio of described extraction agent and required separation of material is 0.5-3: 1.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410013989 CN1266097C (en) | 2004-02-02 | 2004-02-02 | Purification method of pentafluoroethane |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410013989 CN1266097C (en) | 2004-02-02 | 2004-02-02 | Purification method of pentafluoroethane |
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| Publication Number | Publication Date |
|---|---|
| CN1618779A CN1618779A (en) | 2005-05-25 |
| CN1266097C true CN1266097C (en) | 2006-07-26 |
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|---|---|---|---|
| CN 200410013989 Expired - Fee Related CN1266097C (en) | 2004-02-02 | 2004-02-02 | Purification method of pentafluoroethane |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109053366B (en) * | 2018-09-18 | 2019-10-11 | 福建省清流县东莹化工有限公司 | A kind of purifying process of a chloropentafluoroethane |
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