CN1066431C - Preparation of monochloro acetic acid - Google Patents
Preparation of monochloro acetic acid Download PDFInfo
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- CN1066431C CN1066431C CN94112764A CN94112764A CN1066431C CN 1066431 C CN1066431 C CN 1066431C CN 94112764 A CN94112764 A CN 94112764A CN 94112764 A CN94112764 A CN 94112764A CN 1066431 C CN1066431 C CN 1066431C
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Abstract
The present invention relates to a method for preparing monochloro acetic acid (MCHES) through the chlorination of acetic acid. After acetic acid is chlorinated, a coarse MCHES product is prepared. By crystallization and centrifugal separation, MCHES is separated from the crude product. The present invention has the important characteristic that the catalytic hydrogenolysis is carried out before the crystallization step.
Description
The invention belongs to the improvement of (MCHES) monochloroacetic acid technology and can be applied in the chemical industry.
MCHES is a kind of product with preciousness that preparation Walocel MT 20.000PV, various agricultural chemicals and medicine are used.
Monochloroacetic acid is by means of the indirect hydration of trieline
Liquid phase acetic acid (ES) chlorination that the method that prepare monochloroacetic acid the most close with method to be applied for comprises continuous catalysis with separate monochloroacetic acid by means of crystallization with centrifugation subsequently.Go out liquid phase (mother liquor) by crystal separation and send back to chlorination stage (2).
In currently known methods, make catalyzer with acetic anhydride during the acetic acid chlorination.The reaction of carrying out in the technology can be expressed as follows:
Deng.
Important by product is dichloroacetic acid (DCHES), and it forms when the monochloro-acetyl chloride chlorination:
CHCL
2COCL+CH
3COOH----->CHCL
2COOH+CH
3COCL
The continuous chlorination of acetic acid carries out in 100-120 ℃ in the end product medium that contains 75% (weight) MCHES (monochloroacetic acid), 18% (weight) acetic acid and 7% (weight) dichloroacetic acid.
Chlorizate is delivered to crystallisation stage at 50 ℃.Product is cooled to 20-25 ℃ carries out crystallization.The result forms the suspension that a kind of MCHES crystal forms in acetic acid and dichloroacetic acid mixture liquid.
Then, for example utilize centrifugation separate out suspended liquid.Solid is commercially available product mutually, and liquid phase then is sent to chlorination.
Fig. 1 represents the schema of known monochloroacetic acid technology.
By the explanation of known MCHES technique and flow chart as can be known, at chlorination stage mother liquor is sent back to and to have caused the accumulation of DCHES (dichloroacetic acid) in the model, this just must discharge a part of mother liquor and go to disappear and ruin. In addition, the high concentration of DCHES has also reduced the output of crystallization stage.
A shortcoming of known MCHES technique is must disappear to ruin a part of mother liquor, and this can cause high consumption of raw materials index, and owing to DCHES content in the monochloroacetic acid blank is high the production capacity of crystallization stage is reduced.
Throughput when the objective of the invention is to cut down the consumption of raw materials exponential sum raising MCHES crystallization.
The measure that reaches the purpose of putting forward is to introduce the hydrogenolysis stage of a MCHES blank behind the chlorination stage and further product is sent to crystallisation stage behind chlorination stage.
Fig. 2 represents the flow chart of proposed monochloroacetic acid technique.
Obtained result---improving crystallization stage production capacity by the exponential sum of cutting down the consumption of raw materials consists of---is guaranteed by following measures: the catalytic hydrogenolysis stage of introducing the MCHES blank behind chlorination stage can be reduced to 1-1.5% (weight) from 7% (weight) with the amount of the DCHES in the blank, disappear and ruin thereby no longer need to discharge mother liquor, that is to say and got rid of the accumulation of DCHES in the model.
In addition, under the identical prerequisite of other condition, the DCHES content in the reduction MCHES blank can cause the raising of crystallization stage production capacity.
Fig. 2 represents the MCHES preparation method's that proposed skeleton diagram.The result of resulting value of cutting down the consumption of raw materials and raising crystallisation stage throughput guarantees by the catalytic hydrogenolysis subsequent step of introducing a MCHES intermediate product behind chlorinating step, and the 1-2.5% (weight) that the DCHES amount of intermediate steps 7% (weight) can be reduced.Therefore no longer necessary discharge mother liquor disappears and ruins (having got rid of the accumulation of DCHES in feel flow draw of block).In addition, under the identical prerequisite of other condition, the DCHES content that reduces the MCHES intermediate product can cause the raising of crystallisation stage throughput.
Adopt 0.5-2% (weight) to carry the palladium gac as catalyzer.
-(replacement hydrogenation)
Describe the technical scheme that is proposed in detail with embodiment below.
Example 1 (already known processes)
In a reactor (pillar) that chuck arranged, under 110 ℃ of temperature, in liquid phase, carry out catalysis (the adding the 33.6g/n acetic anhydride) chlorination process of acetic acid with gaseous chlorine.This chlorination process carries out under the affair part of excessive 10% (mole) of chlorine.
Crystallisation stage is a volumetric apparatus, is connected with refrigerant in its chuck.In 12 hours, the MCHES blank is cooled to 20 ℃ from 50 ℃ in crystallizer.
Crystallisation process is sent to centrifugation with gained suspension after finishing.After this measure the quality of mother liquor and amount and the composition of composition and commercially available MCHES.
Can obtain the target product productive rate of raw material consumption exponential sum crystallisation stage by test-results.
Condition that test is carried out and the results are shown in the table of obtaining.
Example 2
Be similar to example 1 described method and carry out the chlorination of acetic acid.
The MCHES blank that will obtain when chlorination is sent to the catalytic hydrogenolysis stage.This process is carried out in a volumetric apparatus, and the activated-carbon catalyst that 40g is loaded with 1% (weight) palladium wherein is housed, and temperature is 140 ℃, DCHES: H
2Mol ratio is 1: 7.
Hydrogenolysis is delivered to crystallisation stage with product after the stage.Be similar to example 1 described this crystallisation process that carries out.
Obtain the productive rate of raw material consumption exponential sum crystallisation stage target product by test-results.
Condition of testing and obtained the results are shown in the table.
Institute's column data uses the hydrogenolysis method to the MCHES blank as can be known in the analytical table behind chlorination stage, can reduce the consumption index of raw material acetic acid and chlorine greatly and improve the throughput of crystallisation stage.
An important distinguishing characteristics of the monochloroacetic acid method that is proposed is to use the catalytic hydrogenolysis stage in the MCHES blank between chlorination and the crystallisation stage.
Table
Example 1 example 2 chlorination stages add CL
2G/h 331.76 331.76 adds ES (acetic acid) g/h 235.85 235.85 and obtains the MCHES blank, g/h 396.00 396.00 wherein, g/h
MCHES 297.00 297.00
DCHES 27.72 27.72
ES 71.28 71.28
The hydrogenolysis stage
Hydroformylation product solution, g/h 390.03
Wherein, g/h
MCHES 313.35
DCHES 5.40
ES 71.28
Crystallisation stage
Crystallization raw material, g/ operate 396.0 390.03
Wherein, g/ operation
MCHES 297.00 313.25
DCHES 27.72 5.40
ES 71.28 71.28
Obtain:
Mother liquor, g/ operates 196.00 149.24
Wherein, g/ operation
MCHES 99.00 74.56
DCHES 26.72 4.40
ES 70.28 70.28
Commercially available MCHES, g/ operates 200.00 240.79
Wherein, g/ operation
MCHES 198.00 238.39
DCHES 1.00 1.20
ES 1.00 1.20
Consume index
1/ ton of MCHES of ton
Acetic acid 1.18 0.98
Chlorine 1.66 1.38
Crystallizing power, g/ operates 200.00 240.79
The shortcoming of this method is that carried palladium catalyst consumes high (per 1 ton of product consumes the 1.5kg catalyzer) and the selectivity of the MCHES of pollution purification thus and this method is low.The high like this consumption that is loaded with the activated-carbon catalyst of 2% (weight) palladium can be explained by with the hydrogen blistering reactor time in the loss of catalyzer: catalyzer is caught by air-flow, by the phase mutual friction between the granules of catalyst and after this taken away by reaction mixture in reaction process and cause loss.The reason that process choice is low may be interpreted as: when carrying out hydrogenolysis according to currently known methods, not only regenerate DCHES, and generate MCHES:
The objective of the invention is to be reduced in consumption and raising process choice with catalyzer in the process of hydrogenolysis purification MCHES.
The measure of implementing this purpose is to carry out hydrogenolysis technology in an equipment that is provided with gas lifter.Gas lifter is a pipe, and there is a hydrogen inlet its underpart, and is a mixing tank, forms the gas-liquid mixture of hydrogen and MCHES within it.Because gas-liquid mixture proportion is low, it is by rising in the pipe and taking away MCHES from reactor lower part.Carry out the separation of gas-liquid mixture in the pipe exit.The hydrogen that wherein has neither part nor lot in reaction is discharged by reactor with waste gas, and MCHES Returning reactor top.Between the upper and lower of the pipe (airlift) that hydrogen enters, hydrogenolysis catalyst is housed in the reactor.The effect that airlift produces has guaranteed reaction mass top-down cyclic motion in reactor volume; This catalyst layer is pressed into support grid by reacting material flow as a result.The hydrogen that hydrogenolysis process dissolves in reaction mixture when consuming by airlift carries out.In order to understand the technique scheme that is proposed better, referring to the hydrogenolysis device principle schematic that is used for MCHES of Fig. 3.
By hydrogen inlet is got rid of outside catalyst layer, received positive effect, promptly reduce catalyst consumption and improved selectivity.
With embodiment the technical scheme that is proposed is described below.
Example 1.
At volume is to add 30g in the reactor of 150ml to be loaded with activated-carbon catalyst of 1% (weight) palladium and the MCHES blank that 120g contains 8.6% (weight) DCHES.After reaction mass is heated to 140 ℃, add hydrogen with the speed of 6L/h.
Stop hydrogen supply after 6 hours.The DCHES content heart in the reactant is low, and acetic acid content is 2.8% (weight) to 1.18% (weight), and every 1kg reaction mixture consumes the 1.5g catalyzer.
Example 2.
At volume is to add 30g in the reactor of 150ml to be loaded with activated-carbon catalyst of 1% (weight) palladium and the MCHES blank that 120g contains 8.6% (weight) DCHES.After reactant is heated to 140 ℃, add hydrogen with the speed of 9L/h.
Stop hydrogenation after 6 a small amount of.DCHES content in the reaction mixture is reduced to 1.08% (weight), and acetic acid content is 3.7% (weight), and the catalyst consumption amount of every 1kg reaction mixture is 1.65g.
Example 3
At volume is to add 30g in the reactor of 150ml to be loaded with activated-carbon catalyst of 1% (weight) palladium and the MCHES blank that 120g contains 8.6% (weight) DCHES.After reactant was heated to 140 ℃, to air-lift unit system hydrogen supply, this air-lift unit system was a pipe (similar to the above) that passes catalyst layer with the speed of 6l/h.
Stop hydrogen supply after 6 hours.DHCES content in the reactant is reduced to 1.02% (weight), and acetic acid content is 1.56% (weight), and the catalyst consumption amount of every 1kg reaction mixture is 0.05g.
Example 4
At volume is to add 45g in the reactor of 150ml to be loaded with activated-carbon catalyst of 1% (weight) palladium and the MCHES blank that 120g contains 8.6% (weight) DCHES.After reaction mixture is heated to 140 ℃, with the speed of 6l/h to air-lift unit system hydrogen supply.
Stop hydrogen supply after 6 hours.DCHES content in the reactant is reduced to 0.95% (weight), and acetic acid content is 1.64% (weight), and the catalyzer consumption of every 1kg reaction mixture is 0.4g.
Example 5
At volume is to add 45g in the reactor of 1501m to be loaded with activated-carbon catalyst of 1% (weight) palladium and the MCHES blank that 120g contains 8.6% (weight) DCHES.After reactant is heated to 140 ℃, with the speed of 9l/h to air-lift unit system hydrogen supply.
Stop hydrogen supply after 6 hours.DCHES content in the reactant is reduced to 0.92% (weight), and acetic acid content is 1.62% (weight), and the catalyst consumption amount of every 1kg reaction mixture is 0.05g.
An important particular feature of the method that proposes is to implement this method and hydrogen that all need are sent in this airlift with airlift.The result who uses airlift gets rid of the adding of hydrogen outside catalyst zone, and this has just been avoided the wearing and tearing of catalyzer and has reduced its consumption, and has improved the quality of finished product product.Also improved process choice in addition: quite the MCHES of small number becomes acetic acid.
The foregoing description shows, keeping highly purified product to remove under the situation of DCHES, the method for the purification MCHES that is proposed can obviously reduce the consumption of the catalyzer that contains precious metal palladium, has improved quality product by reducing granules of catalyst, at last, also improved selectivity of product.
In order to use airlift, also can in being housed, the equipment of fixed bed catalyst implement this hydrogenolysis technology in the film-wise operation mode, infeed its upper side with MCHES blank spray catalyst layer and with hydrogen.Here the adding speed of supposing mentioned MCHES blank must be 4.9 * 10
-2-1.24m/s.
The process flow sheet of this method is shown below.See also Fig. 4
The positively effect of institute's extracting method is to reduce catalyst consumption, and this can be owing to the technology of removing DCHES (dichloroacetic acid) impurity purification MCHES in the film-wise operation mode in equipment realizes that the similar of equipment is in a fractionation apparatus that filler is housed; The gac that for example is loaded with 1% palladium with carried palladium catalyst is made filler.This also helps hydrogen is infeeded its upper side.Add reactant like this and avoided the motion of granules of catalyst, thereby avoided its friction and damage.
Suppose 4.9 * 10
-2The necessity that-1.24m/s feeding speed is implemented the MCHES purifying method down is, when feeding speed is lower than 4.9 * 10
-2Will not have mobile MCHES film on some catalyzer during m/s, thereby the violent phase hydrogenolysis process that MCHES becomes acetic acid will take place on these catalyzer, that is to say the selectivity that can reduce technology.
If under greater than the MCHES speed of 1.24m/s, implement this method, on catalyst surface, will form convection flow, the result can reduce the blank purification degree.
With embodiment proposed invention is described below.
Example 1 (known method)
The 80g that packs in a vertical tubular equipment is loaded with activated-carbon catalyst of 1% (weight) palladium and the MCHES blank that 332g (210ml) contains 8.6% (weight) DCHES.After reactant is heated to 140 ℃, provide hydrogen with the speed of 6l/h.
Stop hydrogen supply after 6 hours.DCHES content in the reactant is reduced to 1.18% (weight), and acetic acid (ES) content is 2.8% (weight), and the catalyst consumption amount of every 1kg reaction mixture is 1.5g.
Example 2
In a vertical cartridge reactor with variable-diameter, add the activated-carbon catalyst that 80g is loaded with 1% (weight) palladium, and distribute equably with the superincumbent reactor of the speed of 35ml/h part and to contain the MCHES blank of 8.6% (weight) DCHES, simultaneously with the speed hydrogen supply of 6.6L/h.This process is carried out under 140 ℃.
Condition and resulting result that test is carried out all list in the table.Table
In listed MCHES feeding speed scope, can't see the consumption of palladium catalyst as can be known by institute's column data in the table.Therefore reached the target of minimizing catalyst consumption amount of the present invention.
In the MCHES feed rate is 4.9 * 10
-2During to 1.24m/s, the concentration of DCHES and acetic acid is lower than currently known methods.
When speed surpassed 1.24m/s, DCHES concentration was higher than currently known methods; And when speed was lower than 0.049m/s, acetate concentration was higher than currently known methods.
As a result, be 4.9 * 10 at MCHES blank feed speed
-2In-1.24m/s the scope, reached the target that the present invention improves process choice.
An important feature of the MCHES method of purification of (providing) that proposes is---in being housed, the equipment of fixed bed catalyst implements hydrogenolysis process in the film-wise operation mode, and processing condition are with MCHES blank spray quinoline catalyst layer and at its upper side hydrogen supply.Wherein the feeding speed of MCHES blank is 4.9 * 10
-2-1.24m/s.
Claims (5)
1. the method for preparing monochloroacetic acid (MCHES) by the acetic acid chlorination, wherein produce a kind of MCHES crude product, isolate MCHES by crystallization and centrifugation from this crude product, it is characterized in that, before crystallization, carry out a kind of catalytic hydrogenolysis, wherein with carrying the palladium carbon compositing catalyst, its palladium concentration is 0.5 to 2% (weight), and hydrogenolysis is carried out in an airlift.
2. according to the method for claim 1, it is characterized in that the mol ratio DCHES when regulating hydrogenolysis: H
2=1: 7.
3. according to the method for claim 1, it is characterized in that hydrogenolysis is carried out under 125 to 140 ℃ of temperature.
4. according to the method one of in the claim 1 to 3, it is characterized in that hydrogenolysis is carried out in the fixed bed catalyst of film-wise operation.
5. according to the method for claim 4, it is characterized in that the feed speed of MCHES crude product was 0.05 to 1.24m/ second.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94112764A CN1066431C (en) | 1994-12-05 | 1994-12-05 | Preparation of monochloro acetic acid |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94112764A CN1066431C (en) | 1994-12-05 | 1994-12-05 | Preparation of monochloro acetic acid |
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| CN1124243A CN1124243A (en) | 1996-06-12 |
| CN1066431C true CN1066431C (en) | 2001-05-30 |
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| CN94112764A Expired - Fee Related CN1066431C (en) | 1994-12-05 | 1994-12-05 | Preparation of monochloro acetic acid |
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| CN102001930B (en) * | 2010-10-15 | 2014-08-27 | 中国天辰工程有限公司 | Method for purifying chloroacetic acid by catalytic hydrogenolysis in chloroacetic acid production and application thereof |
| CN104326897A (en) * | 2014-11-21 | 2015-02-04 | 河北科技大学 | Continuous crystallization method of chloroacetic acid |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1063677A (en) * | 1991-01-31 | 1992-08-19 | 翟超进 | Produce the method for Monochloro Acetic Acid |
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1994
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1063677A (en) * | 1991-01-31 | 1992-08-19 | 翟超进 | Produce the method for Monochloro Acetic Acid |
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