CN100427453C - Process for synthesizing ethyl lactate by catalytic rectifying method - Google Patents
Process for synthesizing ethyl lactate by catalytic rectifying method Download PDFInfo
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- CN100427453C CN100427453C CNB2004100573245A CN200410057324A CN100427453C CN 100427453 C CN100427453 C CN 100427453C CN B2004100573245 A CNB2004100573245 A CN B2004100573245A CN 200410057324 A CN200410057324 A CN 200410057324A CN 100427453 C CN100427453 C CN 100427453C
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Abstract
The present invention relates to a novel technology for synthesizing ethyl lactate by a catalytic rectifying method, which belongs to the field for synthesizing and refining an organic solvent. In order to solve the problems of low ethyl lactate yield, complicated technological line, etc. existing in the existing ethyl lactate production technology, the present invention discloses a new technology which comprises the following steps: firstly, lactic acid and alcohol are catalyzed by a strong-acid ion exchange resin catalyst in a catalyzing section of a catalytic rectifying tower to generate ethyl lactate; the alcohol and generated water in the reaction solution are vaporized to enter a rectifying section of the catalytic rectifying tower to be enriched when the esterification reaction is carried out simultaneously; after the alcohol and the water are condensed in a condenser, one part returns to a feed liquid intermediate storage tank, and the other part flows back to the catalytic rectifying tower. The lactic acid and the ethyl lactate which are hard to volatilize, the water and the unreacted alcohol pass through a stripping section of the catalytic rectifying tower to enter a column reactor reboiler; then, column reactor products of the catalytic rectifying tower are led to a flash tower; impurities in the column reactor products are removed by a flash process to obtain the food-grade ethyl lactate product.
Description
Technical field
The present invention relates to a kind of method of production ethyl lactate, belong to the synthetic and field of refinement of organic solvent.
Background technology
The molecular formula of ethyl lactate is C
5H
10O
3, fusing point-26 ℃, 154.5 ℃ of boiling points.Chemical property is more active, and is water-soluble.Ethyl lactate is a kind of excellent solvent, and people are used to prepare all kinds of high-grade paint and oil field pipe and clean usually used as the solvent of nitrocotton, acetate fiber and olivet etc.; He still is a kind of important flavouring agent, has aroma type fragrance, is used to modulate various drinks and food flavour; Be used as the lubricant of slugging in this external pharmaceutical industry, pharmaceutical intermediate; Be used as flavouring agent in the fodder industry, important intermediate of synthetic fragrant oxygen propionic acid class weedicide or the like, ethyl lactate has purposes very widely in industry.
The synthetic esterification process that adopts usually of ethyl lactate is promptly reacted dehydration by lactic acid and ethanol and is generated ester in the presence of bronsted acid catalyst, be refined into food grade products by underpressure distillation again.Ethyl lactate owing to its in industry widely purposes enjoy people to pay attention to.China begins to produce ethyl lactate from the eighties, but production level is relatively backward, and the lactic acid transformation efficiency is lower than 80%.The subject matter that the ethyl lactate production technique exists has following 2 points:
[1] in order to obtain higher lactic acid transformation efficiency, must constantly remove the water that generates in the esterification, molecular balance is constantly broken.Traditional method uses deleterious benzene, toluene etc. as the band aqua.
[2] used catalyzer also is the important factor that influences the lactic acid transformation efficiency in the esterification.The industrial vitriol oil commonly used is made catalyzer, but the reaction times is longer, and serious to equipment corrosion, technical process is long, and aftertreatment is numerous and diverse, easily pollutes.And sulfuric acid can impel lactic acid that intermolecular and intramolecular dehydration reaction, condensation reaction, cyclization and side reaction such as partially carbonized take place, so the product color and luster is bad, and productive rate is lower.
Summary of the invention
Have in the existing ethyl lactate production technique in order to solve that the ethyl lactate yield is low, operational path problem such as complexity comparatively, the invention provides the new technology for producing ethyl lactate that catalytic esterification rectifying and flash vaporization process are coupled,
In addition, in order to solve traditional process equipment investment problem of higher, the present invention also is coupled esterification and rectifying, has set up one and has overlapped the device that catalytic distillation prepares ethyl lactate, and total system can be moved under stable condition, realizes serialization production.This has just improved the yield of ethyl lactate widely, catalytic distillation Synthesis of ethyl lactate step lactic acid transformation efficiency reaches 86.4%, the total recovery that finally obtains the food grade ethyl lactate is up to 78.9%, simultaneously also reduce the expense of facility investment and saved energy consumption, made whole technological process become simple and economical.
Catalytic rectification process Synthesis of ethyl lactate novel process provided by the invention is characterized in that this technology comprises the steps:
At first, lactic acid and ethanol are generated ethyl lactate by the strongly acidic ion-exchange resin catalyst catalyzed reaction in the catalytic section of catalytic rectifying tower; Carry out the while in above-mentioned esterification, the ethanol in the reaction soln and the water of generation are vaporized the rectifying section enrichment that enters catalytic rectifying tower; The second alcohol and water is after condenser condenses, and a part is returned in the feed liquid relay tank, and another part passes back into catalytic rectifying tower; Difficult evaporable lactic acid, ethyl lactate, and the stripping section of water and a small amount of unreacted ethanol process catalytic rectifying tower enters tower still reboiler; With this understanding, ethyl lactate is a primary product, and side reaction is suppressed greatly.
Then, with the tower still product feeding flashing tower of catalytic rectifying tower, the impurity in flash vaporization process removal tower still product obtains food grade ethyl lactate product.
Ethyl lactate processing condition (feed stream ratio, reflux ratio, produced quantity, flashing pressure, flash vaporization point) all can produce certain influence to the quality and the yield of ethyl lactate product.Under given catalytic rectifying tower configuration, have only the suitable reflux ratio of selection to match and just can obtain esterification yield preferably with the charging molar ratio of alcohol to acid.Flash vaporization process can fine removal ethyl lactate product under appropriate vacuum degree and vaporization temperature in the higher impurity such as ethanol of volatility, this moment, the yield of ethyl lactate was the highest, color and luster is best.
By exploitation and optimization to ethyl lactate new synthetic process system, we have used the strongly acidic ion-exchange resin catalyst of efficient, economy, environment-friendly type, in esterification, do not introduce the band aqua, and solved the alcoholic acid recovery well, utilize problem again.By to the ethyl lactate new synthetic process, lactic acid transformation efficiency and ethyl lactate yield have been improved widely, reduced the ethyl lactate production cost, waste quantity has been reduced to approaches zero, the safest on the match operation, the requirement of the most rational green chemical industry technology economically.
Description of drawings
Fig. 1 is the process flow diagram of catalytic rectification process Synthesis of ethyl lactate.
Fig. 2 is the device detail drawing of catalytic distillation reactive moieties.
Embodiment
Specify the present invention below in conjunction with accompanying drawing.
As shown in Figure 1, catalytic rectification process Synthesis of ethyl lactate novel process provided by the invention, comprise the steps: at first, lactic acid feed stream 1 and ethanol feed stream 2 are generated ethyl lactate by the strongly acidic ion-exchange resin catalyst catalyzed reaction in the catalytic section of catalytic rectifying tower 200; Carry out the while in above-mentioned esterification, the ethanol in the reaction soln and the water of generation are vaporized the rectifying section enrichment that enters catalytic rectifying tower; The second alcohol and water is after condenser condenses, and a part is that catalytic distillation cat head distillate 3 returns in the feed liquid relay tank 100 and mixes, mixed solution 5 input catalytic rectifying towers 200, and another part passes back into catalytic rectifying tower; Difficult evaporable lactic acid, ethyl lactate, and the stripping section of water and a small amount of unreacted ethanol process catalytic rectifying tower enters tower still reboiler; Then, with the tower still product 4 feeding flashing towers 300 of catalytic rectifying tower, the impurity 6 in flash vaporization process removal tower still product obtains food grade ethyl lactate product 7.
As shown in Figure 2, make feed liquid ethanol relay tank 100 and lactic acid storage tank 9 with the many mouthfuls of glass flask of volume 2000ml; Catalytic rectifying tower is a packing tower, diameter 0.027m, and the segmentation assembling glass column of high 1.40-1.50m, design has the vacuum jacket thermal insulation layer; Filler adopts ceramic Raschig to encircle (a4 * 4 * 1mm, b3 * 3 * 1mm).Catalytic rectifying tower is divided into three parts: rectifying section 20, catalytic section 21 and stripping section 22.Whole catalytic rectifying tower all has the heat tape parcel, in order to the compensation thermosteresis.Connect tower still reboiler 15 below the catalytic rectifying tower, tower still reboiler uses the four-hole boiling flask of 2000ml, and the heating jacket 19 with a power-adjustable heats it simultaneously.The catalytic rectifying tower top connects condenser 14, and installs magneton and the digital reflux ratio controller that shows that distributes with the high-speed double electromagnet phlegma additional.Whole catalytic rectifying tower also is equipped with Temperature Feedback controller 17.Three transferpumps, promptly lactic acid transferpump 10, ethanol transferpump 11, tower still extraction pump 16 are used for realizing quantitatively input and extraction material.Also comprise surge tank 12 in the total system, product stock jar 18, and some thermowell.U-shaped pipe differential manometer is installed is used for measuring rectifying column pressure drop distribution situation.
Add earlier the 400ml deionized water in the tower still reboiler, and add a certain amount of zeolite and prevent bumping; In the feed liquid relay tank, add 250ml ethanol (95～99.5%); In lactic acid feed liquid storage tank, add 500ml food grade lactic acid (concentration is 80～90%).By regulating the rotating speed of lactic acid transferpump 10 and ethanol transferpump 11, keep certain reaction thing molar ratio (ethanol: lactic acid=3: 1～5: 1).The employed strongly acidic ion-exchange resin catalyst of the present invention's esterification in catalytic rectifying tower can be the Dowex 50 and the Amberlyst 15 of the U.S., can also be the D001 highly acidic resin of China and the catalyzer that D002 highly acidic resin etc. similarly has identical function.
Open electrically heated cover heating tower still reboiler earlier, boiling back water vapor enters in the catalytic rectifying tower, purges catalytic rectifying tower 10 minutes.Start lactic acid transferpump 10 then, ethanol transferpump 11 makes lactic acid, ethanol with molar ratio charging in 3: 1～5: 1, is the heating startup procedure from heating beginning by the time condensation reflux liquid occurs.When picking up counting appears in phegma, move 3～4 hours, it is stable that the state of catalytic rectifying tower can reach.Reach stable after, the catalytic section feeding temperature of catalytic rectifying tower is 84～88 ℃, the optimum temperuture of described tower still reboiler is 80～90 ℃, the condensing reflux optimum temperuture of described condenser is 70～75 ℃.
The topmost operational condition of flashing tower comprises service temperature and operation pressure.Along with the raising of vaporization temperature, content of ethyl lactate is reduced to below the 55wt% gradually in the debris; Steaming in the liquid content of ethyl lactate increases, and steams and only contain ethanol, ethyl lactate and water in the liquid, does not contain lactic acid.This is because the boiling point of mixture significantly reduces under vacuum, and the volatility of lactic acid is significantly less than ethanol and ethyl ester, therefore, at pressure is 0.05～0.2atm, when flash vaporization point is 50～70 ℃, and can be with lactic acid, ethyl lactate relative higher material ethanol, water sepn with volatility, the yield of ethyl lactate product is up to 95.45%, and it is big more that volatility differs, for example lactic acid and ethanol, and separating effect is just good more.The optimum operation condition of flashing tower is: tower is pressed 0.1atm, 61 ℃ of tower temperature.The yield of ethyl lactate can reach 97.75% in this step flash vaporization process.
Embodiment 1:
The project organization parameter of catalytic rectifying tower is shown in table 1,2.Add earlier deionized water in the tower still reboiler, and add a certain amount of zeolite and prevent bumping.The heating tower of elder generation still reboiler, boiling back water vapor enters in the catalytic rectifying tower, purges rectifying tower 10min.Start lactic acid transferpump and ethanol transferpump then, regulate the rotating speed of feed liquid two transferpumps, keeping molar ratio of alcohol to acid is 5: 1.Use the D002 highly acidic resin.Reaction ethanol inlet amount 20kg/h, reflux ratio is 4: 1, cat head produced quantity 20kg/h.When picking up counting appears in phegma, move 5～6 hours, it is stable that the state of catalytic rectifying tower can reach.The yield of esterification reaches 86.42% under this condition, far above other traditional technologys.Cat head, tower still product composition are listed in table 3.
Table 1 rectifying section and stripping section parameter
| Rectifying section | Stripping section | |
| The tower diameter | 0.27m | 0.27 |
| Stage number | ||
| 3 | 3 | |
| Distance between plates | 1.33m | 1.5m |
| Useful area | 0.034m 2 | 0.034m 2 |
| The downtake area | 0.009543m 2 | 0.009543m 2 |
| The weir is long | 0.04m | 0.04m |
| Height of weir | 0.09m | 0.09m |
Table 2 catalytic section pad parameter
| The tower diameter | 0.27m |
| Packing height | 6m |
| The packing ratio surface-area | 600m -1 |
| Filler size | a-4×4×1b-3×3×1mm |
| Voidage | 0.65 |
| Critical surface tension | 0.0061N/m |
| Packing factor | 5249.34 |
| Specified size | 0.003m |
| Tamped density | 75.684Kg·m -3 |
| Catalyst porosity | 0.45 |
| The catalyzer exchange capacity | 4.54Meq(H +)/g |
Table 3 catalytic distillation cat head, tower still product are formed
The operational condition of flashing tower is: tower is pressed 0.1atm, 61 ℃ of tower temperature.The yield of ethyl lactate reaches 97.75% in the flash vaporization process.Flash distillation cat head, still product composition are listed in table 4.
Table 4 flash distillation cat head, tower still product are formed
Embodiment 2:
Catalytic rectifying tower configuration and operational circumstances are with embodiment 1.Reaction ethanol inlet amount 25kg/h, molar ratio of alcohol to acid is 3: 1, reflux ratio is 4: 1, cat head produced quantity 20kg/h.The yield of esterification reaches 85.78% under this condition.Cat head and tower bottom flow fluid are formed the results are shown in table 5.
Table 5 catalytic distillation cat head, tower still product are formed
Embodiment 3:
The catalytic rectifying tower configuring condition is with embodiment 1.Catalytic rectifying tower is operated under different reflux ratios (R=2,3) condition, reaction ethanol inlet amount 20kg/h, and molar ratio of alcohol to acid is 5: 1, cat head produced quantity 20kg/h.Cat head and tower bottom flow fluid are formed the results are shown in table 6.
Table 6 catalytic distillation cat head, tower still product are formed
The ratio of the cat head extraction light constituent that the reflux ratio increase causes also increases, so the each several part temperature of tower reduces gradually with the reflux ratio increase.In the experimental temperature scope, separation is a principal element, and temperature is less to the catalytic efficiency influence.So, help improving in the overhead product content of ethyl lactate in the alcoholic acid content and tower still product in the raising (2～4) of certain scope internal reflux ratio.
Claims (6)
1. catalytic rectification process Synthesis of ethyl lactate technology is characterized in that, this technology comprises the steps:
At first, lactic acid and ethanol are generated ethyl lactate by the strongly acidic ion-exchange resin catalyst catalyzed reaction in the catalytic section of catalytic rectifying tower; Carry out the while in above-mentioned esterification, the ethanol in the reaction soln and the water of generation are vaporized the rectifying section enrichment that enters catalytic rectifying tower; The second alcohol and water is after condenser condenses, and a part is returned in the feed liquid relay tank, and another part passes back into catalytic rectifying tower; Difficult evaporable lactic acid, ethyl lactate, and the stripping section of water and a small amount of unreacted ethanol process catalytic rectifying tower enters tower still reboiler;
Then, with the tower still product feeding flashing tower of catalytic rectifying tower, the impurity in flash vaporization process removal tower still product obtains food grade ethyl lactate product.
2. according to the described ethyl lactate production technique of claim 1, it is characterized in that: concentration of lactic acid is 80～90% in the reaction raw materials, and ethanol is 95～99.5%.
3. according to the described ethyl lactate production technique of claim 1, it is characterized in that: in esterification, the mol ratio of ethanol and lactic acid is 3: 1～5: 1, and the scope of reflux ratio is 2～4.
4. according to the described ethyl lactate production technique of claim 1, it is characterized in that: the catalytic section feeding temperature of described catalytic rectifying tower is 84～88 ℃, and the temperature of described tower still reboiler is 80～90 ℃, and the condensing reflux temperature of described condenser is 70～75 ℃.
5. according to the described ethyl lactate production technique of claim 1, it is characterized in that: the operational condition of flashing tower is: pressure 0.05～0.2atm, 50～70 ℃ of temperature.
6. according to the described ethyl lactate production technique of claim 1, it is characterized in that: described catalytic rectifying tower is a packing tower, and employed filler is the ceramic raschig rings filler.
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| CNB2004100573245A CN100427453C (en) | 2004-08-27 | 2004-08-27 | Process for synthesizing ethyl lactate by catalytic rectifying method |
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| CNB2004100573245A CN100427453C (en) | 2004-08-27 | 2004-08-27 | Process for synthesizing ethyl lactate by catalytic rectifying method |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102320969A (en) * | 2011-06-10 | 2012-01-18 | 天津大学 | System and method for rectifying and purifying food grade ethyl lactate into electronic grade ethyl lactate |
| EP2842932A4 (en) | 2012-04-27 | 2015-12-23 | Xiaogan Esun New Material Co Ltd | Method for continuously producing high-content high-optical-purity lactate |
| CN104610055A (en) * | 2015-01-04 | 2015-05-13 | 烟台大学 | Preparation method for synthesizing propyl acetate by catalytic rectifying process |
| CN107032984A (en) * | 2016-02-03 | 2017-08-11 | 天津中福工程技术有限公司 | A kind of method that continuous catalyzing rectifying prepares ethyl lactate |
| CN109942358A (en) * | 2019-04-16 | 2019-06-28 | 营创三征(营口)精细化工有限公司 | A kind of solid acid catalysis low-boiling point alcohol continuous esterification technique |
| CN110698340A (en) * | 2019-10-21 | 2020-01-17 | 天津大学 | Process method for producing ethyl lactate by reactive distillation dividing wall tower technology |
| CN111943849B (en) * | 2020-08-15 | 2023-08-29 | 天津大学 | Efficient energy-saving ethyl lactate reactive distillation production method and device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6664413B1 (en) * | 1998-11-19 | 2003-12-16 | A. E. Staley Manufacturing Co. | Process for production of esters |
| WO2004052825A2 (en) * | 2002-12-05 | 2004-06-24 | Arkema | Continuous ethyl lactate preparation method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6664413B1 (en) * | 1998-11-19 | 2003-12-16 | A. E. Staley Manufacturing Co. | Process for production of esters |
| WO2004052825A2 (en) * | 2002-12-05 | 2004-06-24 | Arkema | Continuous ethyl lactate preparation method |
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