WO2020029114A1 - 一种提纯脱氢乙酸的方法 - Google Patents

一种提纯脱氢乙酸的方法 Download PDF

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WO2020029114A1
WO2020029114A1 PCT/CN2018/099342 CN2018099342W WO2020029114A1 WO 2020029114 A1 WO2020029114 A1 WO 2020029114A1 CN 2018099342 W CN2018099342 W CN 2018099342W WO 2020029114 A1 WO2020029114 A1 WO 2020029114A1
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melt
dehydroacetic acid
crystallizer
crystal layer
solution
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PCT/CN2018/099342
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French (fr)
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许卫东
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南通奥凯生物技术开发有限公司
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Priority to PCT/CN2018/099342 priority Critical patent/WO2020029114A1/zh
Publication of WO2020029114A1 publication Critical patent/WO2020029114A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D309/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings
    • C07D309/34—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
    • C07D309/36—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with oxygen atoms directly attached to ring carbon atoms
    • C07D309/38—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with oxygen atoms directly attached to ring carbon atoms one oxygen atom in position 2 or 4, e.g. pyrones

Definitions

  • the invention relates to a method for purifying dehydroacetic acid, in particular to a method for purifying dehydroacetic acid by a melt crystallizer.
  • Dehydroacetic acid is a broad-spectrum feed preservative that inhibits the growth of mold, yeast, and bacteria.
  • the bacteriostatic effect is basically not affected by pH, but the antiseptic effect is the best under neutral conditions. It is also used as a food preservative.
  • the domestic regulations can be used for the preservation of fermented bean curd, pickles and orange sauce. The maximum use amount is 0.3g / kg.
  • dehydroacetic acid is an organic synthesis intermediate and toughening agent. Sexual food preservatives. Since it was discovered to be antibacterial in 1940, it has received the attention of many countries and has been allowed to be used for food preservation.
  • dehydroacetic acid is allowed to be used in cheese, butter, margarine, refreshing drinks, fermented milk and lactic acid bacteria drinks, soy sauce, fillings, and the like.
  • sodium dehydroacetate is generally used as a food additive.
  • the product is also used in daily cosmetics, fiber products, medicine (such as the treatment of ringworm), and the preservation of dental materials.
  • the equipment for large-scale production of dehydroacetic acid at home and abroad is a general enamel reaction kettle.
  • the mature process is roughly as follows: that is, the toluene and diketene are subjected to a condensation reaction under the action of a catalyst, and then the enamel kettle is cooled to crystallize, dehydrate, Finished products such as drying and packaging are obtained.
  • the cooling temperature of the enamel kettle and the jacket is not well controlled, the materials are easy to stick, the yield is not high, the purity is greatly affected, and the appearance is very poor. Therefore, the existing technology and equipment for such dehydroacetic acid need to be improved.
  • the technical problem to be solved by the present invention is to provide a method for purifying dehydroacetic acid by a melt crystallizer, which has good parallel reaction selectivity and safety, reduces cost and equipment investment, is environmentally friendly, reduces energy consumption, and has sorbic acid.
  • the product has high purity and stable quality, thereby overcoming the deficiencies in the prior art.
  • the technical solution adopted by the present invention is: a method for purifying dehydroacetic acid, and its innovation lies in: using a melt crystallizer to purify dehydroacetic acid;
  • Crystallization Frozen brine is first introduced into the bottom of the outer jacket of the melt crystallizer.
  • the frozen brine flows uniformly as a falling film on the outer wall of the melt crystallizer, and then the condensed dehydroacetic acid solution is put into the melt crystallizer.
  • the hydroacetic acid solution flows under the falling film on the inner wall of the melt crystallizer, gradually cools and crystallizes, and a uniform crystal layer gradually grows on the heat transfer surface.
  • the concentration of the crystal layer is higher than the concentration of the melt crystallizer solution, and impurities gradually accumulate in the solution. ;
  • the invention adopts a melt crystallizer to realize the separation and purification of substances by utilizing the difference in freezing points between the separated substances, and to control the mass transfer by adjusting the transmission of energy, thereby achieving the effect of improving the crystallization efficiency and the purity of the crystalline finished product; the parallel reaction selectivity is improved;
  • control input through the melt crystallizer to maintain the optimal concentration of crystallization.
  • Low-temperature operation can improve system safety; an appropriate amount of Compressing the air causes the solution to form a bubble-like flow rise in the crystal tube, causing turbulence of the melt and enhancing mass and heat transfer performance.
  • the step (1) is specifically: firstly passing frozen brine through the bottom of the outer jacket of the melt crystallizer, the frozen brine flows uniformly in a falling film on the outer wall of the melt crystallizer, and then the condensed dehydroacetic acid solution is put into Into the crystallizer, at the same time, pass compressed air into the dehydroacetic acid solution at a speed of 4 to 7 m 3 / min through the air duct of the crystallizer, so that a bubble-like flow bubble rises in the crystallizer, causing turbulence of the melt.
  • the dehydroacetic acid solution flows down the inner wall of the melt crystallizer and gradually cools down to crystallize, and a uniform crystal layer is gradually grown on the heat exchange surface.
  • the concentration of the crystal layer is higher than that of the melt crystallizer.
  • impurities are gradually enriched in the solution.
  • the step (2) is specifically: after controlling the passage time of the frozen brine for 30 to 40 minutes, stopping the feeding, and switching the warm water tank to partially melt the crystal layer, the water temperature of the warm water tank is 88 to 92 ° C, and the warm water passage time It is 15 to 40 minutes; then the low-melting-point impurities in the crystal layer are melted and eliminated by switching the hot water tank, and the crystal is further purified.
  • the water temperature of the hot water tank is 90 to 94 ° C, and the hot water passing time is 28 to 32 minutes.
  • the melting crystallizer is a vertical tube heat exchanger type falling film melt crystallization.
  • the present invention has the advantages that the process for purifying sorbic acid by the above-mentioned melting crystallizer is simple, has good parallel reaction selectivity and safety, and adopts a falling film form and low-temperature operation, and the energy per unit of product output Consumption is greatly reduced, and it has good economics.
  • the crystal forms a crystal layer on the heat transfer surface instead of being suspended in the liquid. This avoids blockage of equipment and pipes, reduces the occurrence of production failures, and reduces Cost and equipment investment; there are almost no "three wastes" in the production process, and it is environmentally friendly.
  • the sorbic acid product produced by using the melt crystallizer has high purity and stable quality. Increasing the number of operating stages can increase the purity infinitely, and the impurity content in the product can be changed from percentage content to ppm content, thereby overcoming the deficiencies in the prior art. .
  • the process of purifying dehydroacetic acid by melting crystallizer is as follows:
  • Crystallization firstly pass -8 ° C calcium chloride solution into the bottom of the outer jacket of the melt crystallizer, and the calcium chloride solution flows uniformly in a falling film on the outer wall of the melt crystallizer, and then put the condensed dehydroacetic acid solution into Into the crystallizer, at the same time, the compressed air is passed into the dehydroacetic acid solution at a speed of 4m 3 / min through the melter air duct, so that a bubble-like bubble rises in the crystallizer, causing turbulence of the melt, Enhance the mass and heat transfer performance.
  • the dehydroacetic acid solution will gradually cool down and crystallize under the falling film flow on the inner wall of the crystallizer, and a uniform crystal layer will gradually grow on the heat exchange surface.
  • the concentration of the crystal layer is higher than that of the solution in the molten crystallizer. Concentration, impurities are gradually enriched in the solution;
  • the process of purifying dehydroacetic acid by melting crystallizer is as follows:
  • Crystallization firstly pass -6 ° C sodium chloride solution into the bottom of the outer jacket of the melt crystallizer, and the sodium chloride solution flows uniformly in a falling film on the outer wall of the crystallizer, and then put the condensed dehydroacetic acid solution into the In the melt crystallizer, at the same time, compressed air is passed into the dehydroacetic acid solution at a speed of 5 m 3 / min through the melt crystallizer air duct, so that a bubble-like flow bubble rises in the crystal tube, causing turbulence of the melt and strengthening.
  • the dehydroacetic acid solution is gradually cooled and crystallized under the falling film flow on the inner wall of the crystallizer, and a uniform crystal layer is gradually grown on the heat exchange surface.
  • the concentration of the crystal layer is higher than the concentration of the mixture solution, and the impurities gradually Enriched in the mixture solution;
  • the process of purifying dehydroacetic acid by melting crystallizer is as follows:
  • the crystallization process of dehydroacetic acid becomes easier to control, with less impurities and higher purity of the finished product, which can generally reach more than 99.8%. It is white and bright, and the crystal is good.
  • the presence of impurities in the finished product of dehydroacetic acid is not or is greatly reduced, which effectively improves its antiseptic performance, reduces the amount of preservatives in food, and effectively improves food safety.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

本发明公开了利用熔融结晶制备高纯度的脱氢乙酸的生产工艺，其包括如下步骤：先在熔融结晶器外夹套底部通入冷冻盐水，冷冻盐水均匀的在结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，脱氢乙酸溶液在结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶体层，晶体层的浓度高于混合物溶液的浓度，杂质逐步富集于混合物溶液中；然后通过换热器调节热水温度对晶体层进行部分熔化操作，即发汗过程，使晶体层中夹杂的低熔点杂质部分熔化排除，以进一步提纯晶体。本发明工艺简单，设备结构紧凑，采用降膜形式，降低能量，同时降低了成本和设备投资；利用该熔融结晶器生产出的产品纯度高。

Description

一种提纯脱氢乙酸的方法 技术领域
本发明涉及一种脱氢乙酸的提纯方法，尤其是一种熔融结晶器提纯脱氢乙酸的方法。
背景技术
脱氢乙酸是一种广谱性的饲料防腐剂，能抑制霉菌、酵母和细菌的生长。抑菌作用基本不受PH的影响，但中性条件下防腐效果最好。也用作食品防腐剂，国内规定可用于腐乳、酱菜和原汁橘酱的防腐，最大使用量0.3g/kg，同时脱氢乙酸又是一种有机合成中间体、增韧剂，也是广谱性的食品防腐剂。自1940年发现其有抗菌性以来，先后得到许多国家的重视，并陆续得到用于食品防腐的允许。脱氢乙酸作为食品添加剂，允许用于干酪、黄油、人造奶油、清凉饮料、发酵乳及乳酸菌的饮料、豆酱、馅类等。作为食品添加剂一般使用脱氢乙酸钠。该品还用于日用化妆品、纤维制品、医药(如癣症的治疗)，以及齿科材料的防腐。目前国内外规模化生产脱氢乙酸的设备为一般的搪瓷反应釜，其成熟工艺的工序大致如下：即取甲苯与双乙烯酮在催化剂的作用下，发生缩合反应，再经搪瓷釜冷却结晶、脱水、干燥、包装等工序获得成品，然而由于搪瓷釜加套冷却温度不好控制，容易使物料发黏，成品率不高，纯度也大大受到影响，外观很次。故现有的这种脱氢乙酸的工艺及设备有待改进。
发明内容
本发明要解决的技术问题是提供一种熔融结晶器提纯脱氢乙酸的方法，具有良好的平行反应选择性和安全性，降低了成本和设备投资；对环境友好，降低能耗，且山梨酸产品纯度高、品质稳定，从而克服了现有技术中的不足。
为解决上述技术问题，本发明采用的技术方案为：一种提纯脱氢乙酸的方法，其创新点在于：采用熔融结晶器提纯脱氢乙酸；
(1)结晶：先在熔融结晶器外夹套底部通入冷冻盐水，冷冻盐水均匀的在熔融结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，脱氢乙酸溶液在熔融结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶体层，晶体层的浓度高于熔融结晶器溶液的浓度，杂质逐步富集于溶液中；
(2)发汗、熔化：冷冻盐水通入30～40min后，停止供料，通过换热器调节热水温度对晶体层进行部分熔化操作，使晶体层中夹杂的低熔点杂质部分排除，进一步提纯晶体。
本发明采用熔融结晶器利用分离物质之间凝固点的不同而实现物质分离和提纯，通过调节能量的传输控制传质，从而达到提高结晶效率和结晶成品的纯度的效果；提高了平行反应选择性；对于使用溶剂的重结晶会引起爆炸、燃烧等不安全因素的体系，通过熔融结晶器控制输入，维持结晶的最佳浓度，低温操作可提高系统安全性；在结晶器上部导气管通入适量的压缩空气，使溶液在结晶管内形成弹状流气泡上升，造成熔体的湍动，增强传质和传热性能。
进一步地，所述步骤(1)具体为：先在熔融结晶器外夹套底部通入冷冻盐水，冷冻盐水均匀的在熔融结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，同时通过熔融结晶器导气管以4～7m 3/min的速度向脱氢乙酸溶液内通入压缩空气，使之在结晶管内形成弹状流气泡上升，造成熔体的湍动，增强传质和传热性能，脱氢乙酸溶液在熔融结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶体层，晶体层的浓度高于熔融结晶器内溶液的浓度，杂质逐步富集于溶液中。
进一步的，所述步骤(2)具体为：控制冷冻盐水通入时间30～40min后，停止供料，切换温水罐对晶体层进行部分熔化，温水罐水温为88～92℃，温水通入时间为15～40min；然后通过切换热水罐使晶体层中夹杂的低熔点杂质熔化排除，进一步提纯晶体，热水罐水温为90～94℃，热水通入时间为28～32min。
进一步地，所述熔融结晶器为一种立式列管换热器式的降膜熔融结晶。
与现有技术相比，本发明的优点在于：通过上述熔融结晶器提纯山梨酸的工艺简单，其具有良好的平行反应选择性和安全性，采用降膜形式和低温操作，单位产量产品的能量消耗大幅度降低，有较好的经济性，同时该工艺过程晶体是在传热表面形成晶体层，而不是悬浮在液体中，这样避免了设备和管道的堵塞，减少了生产故障的发生，降低了成本和设备投资；生产过程中几乎没有“三废”，对环境友好，与使用溶剂的重结晶相比，不需要干燥以脱除溶剂，能耗仅为精馏的 10％～30％，且利用该熔融结晶器生产出的山梨酸产品纯度高、品质稳定，增加操作级数可使纯度无限提高，可以使产品中杂质含量从百分含量至ppm含量，从而克服了现有技术中的不足。
具体实施方式
下面结合具体实施例对本发明的技术方案作详细说明。
实施例1
熔融结晶器提纯脱氢乙酸的工艺如下：
(1)结晶：先在熔融结晶器外夹套底部通入-8℃氯化钙溶液，氯化钙溶液均匀的在熔融结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，同时通过熔融结晶器导气管以4m 3/min的速度向脱氢乙酸溶液内通入压缩空气，使之在结晶管内形成弹状流气泡上升，造成熔体的湍动，增强传质和传热性能，脱氢乙酸溶液在结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶层，晶体层的浓度高于熔融结晶器内溶液的浓度，杂质逐步富集于溶液中；
(2)发汗、熔化：控制氯化钙溶液通入时间30min后，停止供料，切换温水罐对晶体层进行部分熔化，温水罐水温为88℃，温水通入时间为15min；然后切换热水罐使晶体层中夹杂的低熔点杂质熔化排除，进一步提纯晶体，热水罐水温为90℃，热水通入时间为28min，得到脱氢乙酸的纯度为99.87％。
实施例2
熔融结晶器提纯脱氢乙酸的工艺如下：
(1)结晶：先在熔融结晶器外夹套底部通入-6℃氯化钠溶液，氯化钠溶液均匀的在结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，同时通过熔融结晶器导气管以5m 3/min的速度向脱氢乙酸溶液内通入压缩空气，使之在结晶管内形成弹状流气泡上升，造成熔体的湍动，增强传质和传热性能，脱氢乙酸溶液在结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶层，晶体层的浓度高于混合物溶液的浓度，杂质逐步富集于混合物溶液中；
(2)发汗、熔化：控制氯化钠溶液通入时间35min后，停止供料，切换温水罐对晶体层进行部分熔化，温水罐水温为90℃，温水通入时间为30min；然后切换热水罐使晶体层中夹杂的低熔点杂质熔化排除，进一步提纯晶体，热水罐水温为90℃，热水通入时间为30min，得到脱氢乙酸的纯度为99.93％。
实施例3
熔融结晶器提纯脱氢乙酸的工艺如下：
(1)结晶：先在熔融结晶器外夹套底部通入-2℃的氯化钙溶液，氯化钙溶液均匀的在熔融结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，同时通过熔融结晶器导气管以7m 3/min的速度向脱氢乙酸溶液内通入压缩空气，使之在结晶管内形成弹状流气泡上升，造成熔体的湍动，增强传质和传热性能，脱氢乙酸溶液在结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶层，晶体层的浓度高于熔融结晶器内的溶液的浓度，杂 质逐步富集于溶液中；
(2)发汗、熔化：控制氯化钙溶液通入时间40min后，停止供料，切换温水罐对晶体层进行部分熔化，温水罐水温为92℃，温水通入时间为40min；然后切换热水罐使晶体层中夹杂的低熔点杂质熔化排除，进一步提纯晶体，热水罐水温为94℃，热水通入时间为32min，得到脱氢乙酸的纯度为99.87％。
对比例1
(1)将缩合好的脱氢乙酸溶液打入结晶釜中，往结晶釜夹套通0～-5℃冷冻盐水，待釜内温降至15～25℃时，则关闭冷冻盐水阀门，停止降温，加入1kg的脱氢乙酸轻粉晶种。
(2)晶种加入20～25min后，开启冷冻盐水气动阀门，继续降温，到0～10℃停止降温，准备放料，离心脱水、烘干，得到脱氢乙酸的纯度为99.81％。
通过采用一种类似于立式列管换热器的降膜熔融结晶器后，脱氢乙酸的结晶过程变得更容易控制，杂质少，成品的纯度较高，一般可达到99.8％以上，外观较白且亮，晶体好。通过该工艺的改进，脱氢乙酸成品中没有或者大大减少了杂质的存在，有效的提高了其防腐性能，降低了食品中防腐剂的用量，有效的提高了食品安全。
需要指出的是，上述较佳实施例仅为说明本发明的技术构思及特点，其目的在于让熟悉此项技术的人士能够了解本发明的内容并据以实施，并不能以此限制本发明的保护范围。凡根据本发明精神实质所作的等效变化或修饰，都应涵盖在本发明的保护范围之内。

Claims (5)

  1. 一种提纯脱氢乙酸的方法，其特征在于：采用熔融结晶器提纯脱氢乙酸，具体步骤为：
    (1)结晶步骤：先在熔融结晶器外夹套底部通入冷冻盐水，冷冻盐水均匀的在熔融结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，脱氢乙酸溶液在熔融结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶体层，晶体层的浓度高于熔融结晶器溶液的浓度，杂质逐步富集于溶液中；
    (2)发汗、熔化：冷冻盐水通入30～40min后，停止供料，通过换热器调节热水温度对晶体层进行部分熔化操作，使晶体层中夹杂的低熔点杂质部分排除，进一步提纯晶体。
  2. 根据权利要求1所述一种提纯脱氢乙酸的方法，其特征在于：所述结晶步骤具体为：先在熔融结晶器外夹套底部通入冷冻盐水，温度为-10℃～-2℃，冷冻盐水均匀的在熔融结晶器外壁呈降膜流动，然后将缩合好的脱氢乙酸溶液投入到熔融结晶器内，同时通过熔融结晶器导气管以4～7m 3/min的速度向脱氢乙酸溶液内通入压缩空气，使之在结晶管内形成气泡上升，造成熔体的湍动，增强传质和传热性能，脱氢乙酸溶液在熔融结晶器内壁降膜流下，逐步冷却而结晶，在换热面上逐步生长出均匀的晶体层，晶体层的浓度高于熔融结晶器内溶液的浓度，杂质逐步富集于溶液中。
  3. 根据权利要求1所述一种提纯脱氢乙酸的方法，其特征在于：所述发汗、熔化步骤：控制冷冻盐水通入时间30～40min后，停止供 料，切换温水罐对晶体层进行部分熔化，温水罐水温为88～92℃，温水通入时间为15～40min；然后通过切换热水罐使晶体层中夹杂的低熔点杂质熔化排除，进一步提纯晶体，热水罐水温为90～94℃，热水通入时间为28～32min。
  4. 根据权利要求1或2所述一种提纯脱氢乙酸的方法，其特征在于：所述冷冻盐水为氯化钙溶液或氯化钠溶液。
  5. 根据权利要求1至2任一项所述一种提纯脱氢乙酸的方法，其特征在于：所述熔融结晶器为一种立式列管换热器式的降膜熔融结晶。
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CN103694210A (zh) * 2014-01-13 2014-04-02 南通奥凯生物技术开发有限公司 一种提纯脱氢乙酸的方法

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CN1050829A (zh) * 1990-11-29 1991-04-24 天津大学 参数泵分步结晶法及pfc结晶器
CN103694210A (zh) * 2014-01-13 2014-04-02 南通奥凯生物技术开发有限公司 一种提纯脱氢乙酸的方法

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