CN1086377C - Method for preparing high concentration formic acid - Google Patents
Method for preparing high concentration formic acid Download PDFInfo
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- CN1086377C CN1086377C CN99119352A CN99119352A CN1086377C CN 1086377 C CN1086377 C CN 1086377C CN 99119352 A CN99119352 A CN 99119352A CN 99119352 A CN99119352 A CN 99119352A CN 1086377 C CN1086377 C CN 1086377C
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- formic acid
- entrainer
- water
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- distillation
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Abstract
The present invention relates to an azeotropic distillation process for separating formic acid with concentration higher than 95 wt % from a formic acid solution containing 80 to 85 wt % of formic acid. The azeotropic distillation process uses an azeotropic agent which is immiscible with water and also immiscible with the formic acid. The azeofropic agent is C5-C10 alkane.
Description
The present invention relates to a kind of separation method of azeotropic mixture.Specifically, relate to a kind of employing azeotropic distillation process, from the formic acid water azeotropic mixture of 80-85 weight % concentration, preparation purity is greater than the method for 95% formic acid product.
Formic acid is one of basic Organic Chemicals, is widely used in industry such as agricultural chemicals, leather, dyestuff, medicine and rubber.Aspect medicine industry, can be used for producing medicines such as borneol, aminopyrin, caffeine, VITMAIN B1 and Sulpyrine; Aspect tanning industry, can be used for making leather and tan soft dose; Aspect rubber industry, can be used as the rubber flocculation agent; Formic acid also can be used as the printing and dyeing mordant, the staining agent of fiber and paper and treatment agent, and softening agent and animal flavoring additive are made mould inhibitor etc. with formic acid in the foodstuffs industry.
Domestic formic acid product purity is 80-85 weight % at present, water-content is 15-20 weight %, the formic acid product of 90-95 weight % seldom, and both prices differ also bigger, this is because the boiling point of formic acid is 100.5 ℃, the boiling point of water is 100 ℃, both very approaching and easy generation azeotropic mixtures; And formic acid and water are two materials that polarity is very strong, make separating and refining very difficult cause of formic acid and water mixture.Therefore how will be a job highly significant for 80-85% formic acid is purified to more than the 95 weight % industrial concentration commonly used at present.
Chinese patent CN85104491A discloses the preparation method of anhydrous methanol, and this method is in the presence of methane amide, hydrolyzing methyl manthanoate, distilled water hydrolysis products then.
Chinese patent CN1063483 discloses the method for preparing high purity formic acid.This method has adopted the additive thionyl chloride, makes itself and aqueous formic acid react dehydration, vacuum distilling then.But because technology is complicated, and needs to consume big quantity of material or reagent, so seldom adopt.
Chinese patent CN1069261A discloses a kind of method for preparing high purity formic acid.This method is that the aqueous formic acid of 80-90 weight % is refrigerated to solid, is warming up to 0-7 ℃ then, ice thaw is removed anhydrate.U.S. Pat-A4877490 and US-A4909907 etc. have introduced the method that reclaims formic acid from aqueous mixture.This method obtains by the extractive distillation with other high boiling point organic compound of carboxylic acid a great deal of, be that formic acid and extraction agent reclaim from distillation kettle liquid, water obtains from distillate, and the extraction agent that distillation is used is ethyl benzoate or glycol ether dimethyl ester or phenylformic acid diacetyl oxide etc.
Adopt expensive extraction agent to carry out extracting rectifying, produce the rectificating method of concentration formic acid and high, cost is very high.Add these extraction agents and be high boiling substance, make its recovery and reuse very difficult.And effect of extracting is also not ideal enough, so these methods are in industrial difficult realization.
Adopt the component distillation of entrainers such as propyl formate, butyl formate, make the tower still can obtain the formic acid product of 96% concentration, but these entrainers are easy to hydrolysis, promptly be subjected to thermal hydrolysis to generate formic acid and propyl alcohol or butyl ester in still-process, thereby separation can not be proceeded.
In order to overcome the above-mentioned defective of prior art, the inventor compares and repetitious experimental study multiple entrainer through long term studies, has proposed to adopt a kind of inexpensive entrainer one alkane, improve the method for formic acid concn, this method has its important practical sense industrial.
Therefore, the purpose of this invention is to provide a kind of production method of concentration formic acid and high, from the aqueous formic acid of 80-85 weight %, remove and anhydrate the formic acid product of production high density.
Above-mentioned Azotropic distillation method may further comprise the steps:
With C
5-C
10Alkane entrainer and concentration are the aqueous formic acid raw material of 80-85 weight %, add in the distillation tower together in the distillation tower center, in tower top temperature is 50-65 ℃, tower still temperature is 69-100 ℃, pressure is that entrainer concentration is to distill under the 50-70 weight % condition in normal pressure and the tower still, formed formic acid-water-entrainer ternary minimum boiling point azcotrope at cat head, its steam in condenser after condensation, layering forms oil reservoir and water layer in quantizer, oil reservoir is back in the distillation tower, water layer extraction, the water layer of extraction are concentration 〉=95% formic acid product.
The number of theoretical plate of above-mentioned azeotropic distillation column can be the 20-40 piece.
The amount of the entrainer in the above-mentioned tower still is a steady state value.
The material of the above-mentioned continuous extraction of tower still can adopt layered approach.
The mol ratio of formic acid and water can be selected (0.5-1.4) for use in the above-mentioned extraction material: 1.Above-mentioned entrainer can be selected C for use
5-C
10Alkane or C
5-C
10The mixture of alkane; Wherein preferred C
5-C
10Normal paraffin, C
5-C
10Isoparaffin, C
5-C
10The C of naphthenic hydrocarbon, replacement
5-C
10The C of branched paraffin or replacement
5-C
10At least a in the naphthenic hydrocarbon; Wherein preferred especially Skellysolve A, normal hexane, normal heptane, octane, positive nonane, n-decane, iso-pentane, isohexane, isoheptane, octane-iso, isononane, isodecane, pentamethylene, hexanaphthene, suberane, cyclooctane, cyclononane, cyclodecane, the 2-methylbutane, the 2-methyl hexane, the 2-methylpentane, the 2-methylheptane, the 3-methylpentane, the 3-methyl hexane, the 3-methylheptane, 2, the 2-dimethylbutane, 2, the 2-dimethylpentane, the 4-methylheptane, 2, the 3-dimethylpentane, 2, the 2-dimethylhexane, 2, the 4-dimethylpentane, 2, the 3-dimethylhexane, 3, the 3-dimethylpentane, 3, the 3-dimethylhexane, 3, the 4-dimethylhexane, methylcyclohexane, methylcyclopentane, the methyl suberane, 1, at least a in 1-dimethylcyclopentane or their combination.
The boiling point of formic acid is 100.5 ℃, and is very approaching with the boiling point of water, and forms azeotropic mixture, so can not separate by general distillating method.Anhydrate in order to remove from the aqueous formic acid of 80-85 weight %, the applicant finds, add C in the aqueous formic acid of 80-85 weight %
5-C
10A kind of alkane after, distill again, just water wherein can be removed, obtain the formic acid product of high density.
After alkane added stock liquid to be separated, because alkane and water and formic acid form the mixture of the minimum boiling point with same nature respectively, the boiling point of these mixtures and formic acid boiling point differed bigger, and layering after the condensation helps separating.Moreover formic acid and water all are insoluble to alkane, and it is effective especially therefore to make entrainer with it.
Employed alkane in the Azotropic distillation method of the present invention is C
5-C
10Alkane or its mixture, preferred C
7-C
9Alkane or its mixture.They can be normal paraffin such as Skellysolve A, normal hexane, normal heptane, octane, positive nonane or n-decane; Can be isoparaffin such as iso-pentane, isohexane, isoheptane, octane-iso, isononane or isodecane; They also can be naphthenic hydrocarbon such as pentamethylene, hexanaphthene, suberane, cyclooctane, cyclononane or cyclodecane etc.; They also can be the branched paraffin that replaces such as 2-methylbutane, 2-methyl hexane, 2-methylpentane, 2-methylheptane, 3-methylpentane, 3-methyl hexane, 3-methylheptane, 2,2-dimethylbutane, 2,2-dimethylpentane, 4-methylheptane, 2,3-dimethylpentane, 2,2-dimethylhexane, 2,4-dimethylpentane, 2,3-dimethylhexane, 3,3-dimethylpentane, 3,3-dimethylhexane or 3,4-dimethylhexane; Or the naphthenic hydrocarbon that replaces such as methylcyclohexane, methylcyclopentane, methyl suberane or 1,1-dimethylcyclopentane or the like.
Normal hexane and water and formic acid form binary azeotrope respectively and form boiling point and the composition that tertiary blending closes the thing that boils, and list in table one.
The azeotropic mixture that table 1 normal hexane and water, formic acid form
| Title | The azeotropic mixture boiling point (℃) | Azeotropic mixture is formed (weight %) | ||
| Normal hexane | Formic acid | Water | ||
| Hexane-water | 61.55 | 98.77 | - | 1.23 |
| Hexane-formic acid | 60.6 | 72.00 | 28.00 | - |
| Hexane-formic acid-water | 55-57 | 85-86 | 13-14 | 0.4-0.6 |
When distillation, be divided into two layers of oil reservoir and water layers behind the ternary azeotrope vapor condensation, oil reservoir is the hexane layer of insoluble formic acid and water, and water layer is formic acid and water, and wherein formic acid content is higher than 95 weight %.
Owing to have entrainer in the still, form so the material in the still is formed the azeotropic that is lower than formic acid and water.Therefore the vapor-liquid equilibrium according to this two-component system concerns, up can produce more moisture from the tower still along stripping section, therefore only in the tower still, have under the situation of entrainer existence, the formic acid concn that makes progress along tower is constantly increased, so just help obtaining the formic acid product of high density at cat head.The obvious operation with general component distillation of this component distillation operation has obvious different, because general component distillation operation is at cat head the water in the raw material to be discharged from the top quantizer, and method of the present invention is that water is discharged from the tower still.Because entrainer and formic acid and water do not dissolve each other, therefore, the discharge material for the treatment of column still can make entrainer stay in the still, and lower concentration formic acid and water are then discharged from the tower still.
Fig. 1 represents the block diagram of formic acid-entrainer (normal hexane)-water component distillation.In the drawings, I represents distillation tower, and II represents condenser, and III represents the top quantizer.
Raw material 1 and additional entrainer 2 are added in the tower by the middle part together, the entrainer that replenishes also can add from top quantizer III, the tower still adopts electrically heated, formic acid in the charging and water are gone into top layer quantizer III at formation ternary azeotrope steam under the entrainer effect and are divided into two layers after condenser II condensation, oil reservoir 3 refluxes, and water layer 4 extraction obtain the formic acid product.Water in the charging and part formic acid down in the still in the presence of entrainer, be divided into two-layerly, with water layer 5 extraction, the mol ratio of formic acid and water is (0.5-1.4) in the extraction material: 1, thus reach the purpose that removes water in the formic acid water mixture.
Compared with prior art, the present invention has the following advantages:
1. the present invention is different from general component distillation and effective according to the working method that entrainer need be arranged in the formic acid steam liquid equilibrium relationship proposition tower still.
2. the present invention adopts azeotropic distillation process, utilizes the formic acid water formation ternary minimum azeotropic mixture of entrainer to produce concentration formic acid and high from cat head, has reduced general azeotropic dehydration obtains product from the tower still method.Because the product that the tower still obtains must also will and remove high boiling impurity through the decolouring of product purification tower, thereby has saved equipment and reduced energy consumption.
3. the component distillation device that adopts of the present invention, simple in structure, technology is reasonable, is fit to very much continuous operation.
4. the entrainer price that adopts of the present invention is low, aboundresources, and it is convenient to reclaim, and is that general formic acid water component distillation institute is incomparable.
Embodiment: example 1: raw material consists of H
2O16.71% (Wt), formic acid 83.92%.Add raw material 150ml, add entrainer normal hexane 140ml, at a φ 18mm * 1500mm, the reason stage number is in the glass distillation tower at intermittence of about 30, is 55 ℃ in tower top temperature, and tower still temperature is 69 ℃; Pressure is under the normal pressure, carries out component distillation, and cat head obtains formic acid purity average out to 96.24%, and the product of 87.3ml, product yield are～70%.Example 2: raw material consists of H
2O17.53% (Wt), formic acid 82.29%.Add raw material 150ml, add entrainer normal heptane 150ml, carry out component distillation under said apparatus identical with embodiment 1 and identical condition, cat head obtains formic acid purity average out to 95.23%, and the product of 86.2ml, product yield are～70%.Example 3. raw materials consist of H
2O17.53% (Wt), formic acid 82.29%.Raw materials 20ml/h adds the entrainer hexane, and under the device and condition identical with embodiment 1, component distillation is carried out in operate continuously.Total charging capacity is 245ml, and obtaining to eject formic acid purity is 96.24%, the product of 120.6ml.Product yield is～60%.
Claims (8)
1. isolate the Azotropic distillation method of concentration for 〉=95 weight % formic acid products for one kind from concentration is the aqueous formic acid of 80-85 weight %, described Azotropic distillation method may further comprise the steps:
With C
5-C
10Alkane entrainer and concentration are the aqueous formic acid raw material of 80-85 weight %, add in the distillation tower together in the distillation tower center, in tower top temperature is 50-65 ℃, tower still temperature is 69-100 ℃, pressure is that entrainer concentration is to distill under the 50-70 weight % condition in normal pressure and the tower still, formed formic acid-water-entrainer ternary minimum boiling point azcotrope at cat head, its steam in condenser after condensation, layering forms oil reservoir and water layer in quantizer, oil reservoir is back in the distillation tower, water layer extraction, the water layer of extraction are concentration 〉=95% formic acid product.
2. method according to claim 1 is characterized in that, the number of theoretical plate of described azeotropic distillation column is the 20-40 piece.
3. method according to claim 1, the amount that it is characterized in that the entrainer in the tower still is a steady state value.
4. method according to claim 1 is characterized in that, the material of the continuous extraction of tower still adopts layered approach, and the mol ratio of formic acid and water is (0.5-1.4) in the extraction material: 1.
5. method according to claim 1 is characterized in that entrainer is C
5-C
10Alkane or C
5-C
10The mixture of alkane.
6. method according to claim 5 is characterized in that entrainer is selected from C
5-C
10Normal paraffin, C
5-C
10Isoparaffin, C
5-C
10The C of naphthenic hydrocarbon, replacement
5-C
10The C of branched paraffin or replacement
5-C
10At least a in the naphthenic hydrocarbon.
7. according to claim 5 or 6 described methods, it is characterized in that entrainer is selected from Skellysolve A, normal hexane, normal heptane, octane, positive nonane, n-decane, iso-pentane, isohexane, isoheptane, octane-iso, isononane, isodecane, pentamethylene, hexanaphthene, suberane, cyclooctane, cyclononane, cyclodecane, the 2-methylbutane, the 2-methyl hexane, the 2-methylpentane, the 2-methylheptane, the 3-methylpentane, the 3-methyl hexane, the 3-methylheptane, 2, the 2-dimethylbutane, 2, the 2-dimethylpentane, the 4-methylheptane, 2, the 3-dimethylpentane, 2, the 2-dimethylhexane, 2, the 4-dimethylpentane, 2, the 3-dimethylhexane, 3, the 3-dimethylpentane, 3, the 3-dimethylhexane, 3, the 4-dimethylhexane, methylcyclohexane, methylcyclopentane, the methyl suberane, 1, at least a in 1-dimethylcyclopentane or their combination.
8. method according to claim 1 is characterized in that the entrainer that replenishes is to add at quantizer top, top.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99119352A CN1086377C (en) | 1999-09-10 | 1999-09-10 | Method for preparing high concentration formic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99119352A CN1086377C (en) | 1999-09-10 | 1999-09-10 | Method for preparing high concentration formic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1287995A CN1287995A (en) | 2001-03-21 |
| CN1086377C true CN1086377C (en) | 2002-06-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN99119352A Expired - Fee Related CN1086377C (en) | 1999-09-10 | 1999-09-10 | Method for preparing high concentration formic acid |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102225326B (en) * | 2011-04-29 | 2012-09-05 | 张明 | Apparatus and method for formic acid production |
| CN103159629B (en) * | 2011-12-09 | 2014-09-03 | 中国科学院大连化学物理研究所 | Separation method for azeotrope of ethylene diamine and water |
| JP2016526027A (en) * | 2013-05-16 | 2016-09-01 | ディーエスエム アイピー アセッツ ビー．ブイ． | Process for separating formic acid from methyltetrahydrofuran |
| CN106748737A (en) * | 2016-11-16 | 2017-05-31 | 南京师范大学 | A kind of method of formic acid in azeotropic extraction rectifying concentration aqueous formic acid |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3718547A (en) * | 1970-11-16 | 1973-02-27 | Alcan Res & Dev | Continuous electrolytic treatment for cleaning and conditioning aluminum surfaces |
| CN1063483A (en) * | 1991-01-25 | 1992-08-12 | 北京农业大学 | The novel process of preparation anhydrous formic acid |
-
1999
- 1999-09-10 CN CN99119352A patent/CN1086377C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3718547A (en) * | 1970-11-16 | 1973-02-27 | Alcan Res & Dev | Continuous electrolytic treatment for cleaning and conditioning aluminum surfaces |
| CN1063483A (en) * | 1991-01-25 | 1992-08-12 | 北京农业大学 | The novel process of preparation anhydrous formic acid |
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| CN1287995A (en) | 2001-03-21 |
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