Continuous esterification method of ethyl lactate

Abstract

The invention discloses an ethyl lactate continuous esterification method which comprises the following steps: S1, feeding: sucking ethanol, lactic acid and a novel catalyst into a reaction kettle by utilizing vacuum; s2, heating and stirring: heating the materials in the reaction kettle to 105-115 DEG C by using steam with esterification safety; s3, continuous batching: performing proportioning in a batching tank according to a ratio of lactic acid to ethanol of 1: 1.5 to obtain a batching liquid; s4, dropwise adding: dropwise adding the ingredient liquid by using a centrifugal pump according to a set speed; s5, continuously dropwise adding, carrying out continuous esterification in the reaction kettle under the negative pressure of which the vacuum degree is higher than 0.06 MPa, and continuously discharging; and S6, carrying out primary concentration and secondary concentration and distillation, and rectifying to obtain a finished product. The steps of burdening according to a new proportion, increasing the height of a tower section, performing negative pressure esterification, controlling the temperature and the vacuum degree and the like are utilized for operation, so that the process has the advantages of simple esterification process, good water carrying effect, good separation effect, large discharge quantity and the like.

Description

Technical Field

[0001] The invention relates to the technical field of ethyl lactate production, in particular to a continuous esterification method of ethyl lactate. Background Art

[0002] Ethyl lactate, also known as α-hydroxypropionic acid ethyl ester, is a colorless transparent liquid with a soft fruity aroma, a boiling point of 154°C, a relative density (25 / 25°C) of 1.030, a refractive index (20°C) of 1.4124, and is completely miscible with water and partially decomposed, and is easily soluble in alcohols, ethers, ketones and esters. It is widely used in industries such as flavors, food, brewing, and solvents.

[0003] In the production process of ethyl lactate, the traditional method of producing ethyl lactate is to use lactic acid and ethanol as raw materials and concentrated sulfuric acid as catalyst for esterification reaction. The original ethyl lactate production process has the following disadvantages: the original process has a 1:1 ratio of ingredients, which cannot completely remove the water produced in the esterification process; the 5-meter tower section has poor separation of lactic acid, ethanol, and esterified semi-finished ethyl lactate, and the quality is unstable; the atmospheric pressure esterification has a long time to produce the semi-finished ethyl lactate esterified liquid, and the amount of material discharged is small, which limits the quality and quantity of the semi-finished ethyl lactate esterified liquid, and the equipment utilization rate is low.

[0004] In summary, in the process of producing ethyl lactate, the original esterification reaction has the disadvantages of unsatisfactory water-carrying effect, poor separation effect, long esterification time, small amount of discharge, high labor intensity of workers, low equipment utilization, low output, large quality fluctuation, many by-products and high production cost. Therefore, this application proposes a continuous esterification method for ethyl lactate. Summary of the invention

[0005] The invention provides a method for continuous esterification of ethyl lactate, and develops a technology for continuous esterification of ethyl lactate with simple process, good water carrying effect, good separation effect, short time for producing esterification liquid semi-finished product ethyl lactate, large amount of produced material, improved product quality and quantity, high equipment utilization rate, practical, convenient and fast.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for continuous esterification of ethyl lactate comprises the following steps:

[0008] Step S1: feeding materials, ethanol, lactic acid and novel catalyst are sucked into the reaction kettle by vacuum;

[0009] Step S2: heating and stirring, using steam with esterification safety to heat the materials in the reactor to 105-115°C;

[0010] Step S3: continuously batching, in a batching tank, mixing lactic acid: ethanol in a ratio of 1:1.5 to obtain a batching liquid, and stirring the batching liquid with a stirrer;

[0011] Step S4: adding dropwise, using a centrifugal pump to add the batching liquid at a set speed;

[0012] Step S5: continuously adding dropwise, with the vacuum degree in the reactor being higher than 0.06 MPa, to perform continuous esterification and continuous discharge;

[0013] Step S6: Enter the first concentration, and then distill the finished product after the second concentration and distillation.

[0014] As a further improvement of the present technical solution: the ethanol is anhydrous ethanol.

[0015] As a further improvement of the technical solution: the height of the esterification tower section of the reactor is 8 meters.

[0016] As a further improvement of the present technical solution: in step S4, the speed at which the centrifugal pump drips the dosing liquid is 500 L / h.

[0017] As a further improvement of the technical solution: the novel catalyst is a strong acid cation exchange resin catalyst.

[0018] As a further improvement of the technical solution: the catalyst is a Lewis acid or a tin salt.

[0019] As a further improvement of the technical solution: the reactor is a packed tower.

[0020] As a further improvement of the technical solution: the packing used is stainless steel random packing or structured packing.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention utilizes new proportioning and batching, increases the height of the tower section, negative pressure esterification, controls the temperature and vacuum degree and other steps for operation, so that the process has the advantages of simple esterification process, good water carrying effect, good separation effect, short time for producing esterification liquid semi-finished product ethyl lactate, large amount of produced material and the like, and also has the advantages of improved product quality and quantity, high equipment utilization rate and convenient and quick manufacturing.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 The present invention provides a structural schematic diagram of a continuous esterification method for ethyl lactate. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0028] See also Figure 1 In an embodiment of the present invention, a method for continuous esterification of ethyl lactate comprises the following steps:

[0029] Step S1: feeding, ethanol, lactic acid, and the new catalyst are sucked into a reactor by vacuum, wherein the height of the esterification tower section of the reactor is 8 meters, the reactor is a packed tower, the packing used is a stainless steel random packing or a structured packing, the ethanol is anhydrous ethanol, and the new catalyst is a strong acid cation exchange resin catalyst, specifically a Lewis acid or a tin salt;

[0030] Step S2: heating and stirring, using steam with esterification safety to heat the materials in the reactor to 105-115°C;

[0031] Step S3: continuously batching, in a batching tank, mixing lactic acid: ethanol in a ratio of 1:1.5 to obtain a batching liquid, and stirring the batching liquid with a stirrer;

[0032] Step S4: dripping, using a centrifugal pump to drip the batching liquid at a set speed, wherein the speed of the centrifugal pump to drip the batching liquid is 500L / h;

[0033] Step S5: continuously adding dropwise, with the vacuum degree in the reactor being higher than 0.06 MPa, to perform continuous esterification and continuous discharge;

[0034] Step S6: Enter the first concentration, and then distill the finished product after the second concentration and distillation.

[0035] The working principle of the present invention is:

[0036] By adjusting the feed ratio to lactic acid: ethanol = 1:1.5, and increasing the height of the esterification tower section to 8 meters, using negative pressure esterification with a vacuum degree higher than 0.06MPa, and using continuous batching, continuous feeding, negative pressure continuous esterification, and continuous discharging operating procedures, the separation effect is improved, the discharge flow rate is accelerated, the production capacity is increased, the quality and quantity of the product are improved, and the production cost is reduced.

[0037] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A method for continuous esterification of ethyl lactate, characterized in that: The following steps are involved: Step S1: feeding materials, ethanol, lactic acid and novel catalyst are sucked into the reaction kettle by vacuum; Step S2: heating and stirring, using steam with esterification safety to heat the materials in the reactor to 105-115°C; Step S3: continuously batching, in a batching tank, mixing lactic acid: ethanol in a ratio of 1:1.5 to obtain a batching liquid, and stirring the batching liquid with a stirrer; Step S4: adding dropwise, using a centrifugal pump to add the batching liquid at a set speed; Step S5: continuously adding dropwise, with the vacuum degree in the reactor being higher than 0.06 MPa, to perform continuous esterification and continuous discharge; Step S6: Enter the first concentration, and then distill the finished product after the second concentration and distillation.

2. A method for continuous esterification of ethyl lactate according to claim 1, characterized in that: The ethanol is anhydrous ethanol.

3. A method for continuous esterification of ethyl lactate according to claim 2, characterized in that: The height of the esterification tower section of the reactor is 8 meters.

4. A method for continuous esterification of ethyl lactate according to claim 3, characterized in that: In step S4, the speed of dripping the batching liquid by the centrifugal pump is 500 L / h.

5. A method for continuous esterification of ethyl lactate according to claim 4, characterized in that: The novel catalyst is a strong acid cation exchange resin catalyst.

6. A method for continuous esterification of ethyl lactate according to claim 5, characterized in that: The catalyst is Lewis acid or tin salt.

7. A method for continuous esterification of ethyl lactate according to claim 6, characterized in that: The reactor is a packed tower.

8. A method for continuous esterification of ethyl lactate according to claim 7, characterized in that: The packing used is stainless steel random packing or structured packing.

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