Continuous production process of cationic etherifying agent

Abstract

The invention relates to the technical field of organic chemical synthesis, and discloses a continuous production process of a cationic etherifying agent, which comprises the following steps: taking trimethylamine hydrochloride and epoxy chloropropane as raw materials; the method comprises the following six steps: raw material pretreatment, premixing, continuous reaction, continuous separation, refining and product storage: mixing and dissolving trimethylamine hydrochloride and a solvent, preparing a catalyst solution, uniformly mixing the three materials through a static mixer, feeding into a multi-stage tubular reactor, and carrying out segmented temperature control continuous reaction, and performing flash evaporation solvent removal and rectification on the reaction product to obtain a crude product, and performing ion exchange impurity removal and reduced pressure distillation refining to finally obtain a high-purity product. The method solves the problems of low yield and more byproducts in the traditional process, and is suitable for industrial large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic chemical synthesis, in particular to a continuous production process of cationic etherification agent. BACKGROUND

[0002] Cationic etherification agent is an important fine chemical intermediate, which is widely used in cellulose modification, starch grafting, water treatment agent synthesis, surfactant preparation and other fields. Among them, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, as the most representative cationic etherification agent, has an irreplaceable role in papermaking, textile, oil exploitation and other industries due to its high reactivity and good modification effect.

[0003] At present, the industrial production of cationic etherification agent mostly adopts batch process, which uses epichlorohydrin and trimethylamine hydrochloride as raw materials to prepare by addition reaction in the presence of solvent. The existing batch process has the following shortcomings: first, the material mixing is uneven during the reaction, and the local concentration is too high, which can easily lead to the occurrence of side reactions, generating harmful by-products such as 1,3-dichloro-2-propanol, which not only reduces the yield and purity of the target product, but also increases the difficulty of subsequent separation and purification; second, the reaction temperature is difficult to control accurately, and the exothermic reaction can easily cause a sharp rise in temperature, which poses a safety hazard, and temperature fluctuations can further affect the quality stability of the product; third, the production cycle is long, and each batch needs to go through multiple links such as feeding, reaction, discharging and cleaning, which results in low equipment utilization and cannot meet the needs of large-scale industrial production; fourth, the quality of different batches of products is greatly different due to batch operation, which cannot guarantee the uniformity of the product and affects the use effect of downstream users.

[0004] In order to solve the above-mentioned defects of batch process, the development of continuous production process has become a hot spot in the industry. In some existing continuous production attempts, there are problems such as insufficient material contact, low reaction conversion rate, serious equipment blockage and high energy consumption in subsequent separation. For example, when using a tubular reactor for continuous reaction, the material layering and poor mixing effect are easy to occur due to the large difference in viscosity of raw materials, which leads to incomplete reaction; while using a stirred continuous reactor, the product is attached to the wall of the reactor, which is difficult to clean. Therefore, it is urgent to develop a continuous production process of cationic etherification agent with uniform material mixing, high reaction efficiency, stable product quality, low energy consumption and easy industrialization. SUMMARY

[0005] (I) Technical problems solved In view of the shortcomings of the prior art, the present application provides a continuous production process of cationic etherification agent, which improves the yield and purity of the target product, reduces the content of by-products, and at the same time improves the production efficiency and ensures the stability of product quality.

[0006] (II) Technical solutions To achieve the above object, the application provides the following technical scheme: a continuous production process of cation etherifying agent, which is prepared by using epichlorohydrin and trimethylamine hydrochloride as raw materials, under the action of solvent and catalyst, through the whole process of continuous operation of pre-mixing, continuous reaction, continuous separation and refining, and specifically includes the following steps: (1) raw material pretreatment: stirring and dissolving trimethylamine hydrochloride and solvent according to a mass ratio of 1:1.5-3.0 at 30-50 DEG C to obtain a trimethylamine hydrochloride solution; preparing a catalyst solution with a mass concentration of 0.5-2.0% for standby; the catalyst is a quaternary ammonium salt catalyst; (2) pre-mixing: continuously feeding the trimethylamine hydrochloride solution, the catalyst solution and epichlorohydrin into a static mixer through a metering pump, controlling the molar ratio of trimethylamine hydrochloride to epichlorohydrin to be 1:1.05-1.2, the mixing temperature to be 20-35 DEG C, and the material residence time to be 3-10 min, so as to realize efficient and uniform mixing of the materials; (3) continuous reaction: continuously feeding the pre-mixed material into a multi-stage tubular reactor in series, the reactor is divided into a front section, a middle section and a rear section, the temperatures of the sections are 40-50 DEG C, 55-65 DEG C and 45-55 DEG C respectively, the pressure is 0.1-0.3 MPa, and the total residence time is 15-30 min; during the reaction process, the temperature is adjusted in real time through the constant-temperature medium in the reactor jacket to ensure that the reaction proceeds smoothly; (4) continuous separation: the reacted material is separated through a flash separation device and a rectifying column in sequence, the flash separation conditions are a vacuum degree of-0.06 to-0.08 MPa and a temperature of 60-80 DEG C, the rectifying conditions are normal pressure and a column top temperature of 85-105 DEG C, and the crude product is obtained; the solvent removed through flash separation is recovered through condensation and then returned to the dissolving tank for recycling; (5) refining: the crude product is impurity-removed through an ion exchange column and then distilled under reduced pressure, the conditions are a vacuum degree of-0.09 to-0.095 MPa and a temperature of 110-130 DEG C, and the cation etherifying agent product with a purity of ≥98.5% is obtained; (6) product storage: after the refined product is cooled to room temperature, it is stored under nitrogen protection, and the storage tank is protected by nitrogen to prevent the product from being hygroscopic and oxidized.

[0007] In the step (1), the solvent is one or more of deionized water, methanol and ethanol; Further, in the step (1), the quaternary ammonium salt catalyst is one of tetramethylammonium chloride and tetraethylammonium bromide.

[0008] Further, in the step (2), the static mixer is SK type or SX type, which is internally provided with 5-10 mixing elements, and the material flow rate is 0.5-2.0 m / s, so as to ensure that the material produces strong shearing, stirring and diffusion effects in the mixer to realize uniform mixing.

[0009] Further, in the step (2), the amount of catalyst solution added is 0.1-0.5% of the mass of trimethylamine hydrochloride.

[0010] Further, in the step (3), the number of stages of the multi-stage tubular reactor is 3-5, the inner diameter of the tube is 20-50 mm, and the inner wall of the tube is provided with spiral guide vanes to enhance the degree of turbulent flow of the material and improve the reaction efficiency.

[0011] Further, in the step (4), the rectifying column is a packed column, the packing is a Pall ring or a stepped ring, the height of the packing layer is 3-6 m, and the reflux ratio is 1:0.5-1.5 to improve the efficiency and purity of solvent separation.

[0012] Further, in the step (5), the ion exchange column is filled with strong acid cation exchange resin and strong base anion exchange resin, the filling volume ratio is 1:1-2, and the material residence time is 2-5 min.

[0013] (Three) Beneficial technical effects The present application realizes the uniform mixing and smooth reaction of the material by optimizing the type of mixing element, the structure of the reactor and the reaction parameters, effectively reduces the side reactions caused by excessive local concentration and temperature fluctuations, and improves the yield of the target product to more than 95%, the content of the by-product 1,3-dichloro-2-propanol is less than 0.1%, and the purity of the product is ≥98.5%. The present application realizes the continuous operation of the whole process from raw material pretreatment to product storage, cancels the feeding, discharging, cleaning and other links in the batch process, shortens the production cycle, significantly improves the production efficiency and reduces the labor cost. The present application recovers the solvent by combining flash separation with rectification separation, the solvent recovery rate is ≥90%, and the recovered solvent can be recycled, which reduces the solvent consumption and production cost; at the same time, the combination process of ion exchange impurity removal and vacuum rectification refining effectively removes impurities and ensures the stability of product quality. The process parameters such as temperature and pressure of the present application are easy to control accurately, the reaction process is smooth, there is no obvious exothermic surge phenomenon, and the safety is high; and the equipment structure is simple, easy to maintain and industrialize, and has good industrial application prospect. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely, obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0015] Target product yield test: weight method combined with high performance liquid chromatography quantitative analysis, by detecting the actual mass of the product after refining and the ratio of the theoretical yield to calculate the yield.

[0016] By-product content test: qualitative and quantitative analysis of by-product 1,3-dichloro-2-propanol by gas chromatography-mass spectrometry, and quantitative analysis based on characteristic ion peak area.

[0017] Product purity test: the content of cationic active component in the product is determined by potentiometric titration, combined with HPLC purity correction, and the product purity is comprehensively determined.

[0018] Solvent recovery rate test: the recovery rate is calculated by weighing the mass of the recovered solvent and the total mass of the input solvent, and the recovered solvent is counted as effective recovery after purity detection.

[0019] Production cycle test: record the continuous running time from the beginning of raw material pretreatment to the completion of product storage, excluding equipment cleaning and maintenance time.

[0020] Embodiments 1-3 and comparative examples 1-2 of the present application, wherein the amount of trimethylamine hydrochloride in step (1) raw material pretreatment is 10 g.

[0021] Example 1 A continuous production process of a cationic etherifying agent, characterized in that, with epichlorohydrin and trimethylamine hydrochloride as raw materials, under the action of a solvent and a catalyst, a whole-process continuous operation of pre-mixing, continuous reaction, continuous separation and refining is carried out, which specifically includes the following steps: (1) Raw material pretreatment: trimethylamine hydrochloride and solvent are dissolved by stirring at 30℃ in a mass ratio of 1:1.5 to obtain a trimethylamine hydrochloride solution; a catalyst solution with a mass concentration of 0.5% is prepared for standby; the catalyst is tetramethylammonium chloride, and the solvent is deionized water; (2) Pre-mixing: trimethylamine hydrochloride solution, catalyst solution and epichlorohydrin are continuously fed into a static mixer through a metering pump, the molar ratio of trimethylamine hydrochloride to epichlorohydrin is controlled to be 1:1.05, the amount of catalyst solution added is 0.1% of the mass of trimethylamine hydrochloride, the mixing temperature is 20℃, and the material residence time is 3min; in step (2), the static mixer is SK type, which is internally provided with 5 mixing elements, and the material flow rate is 0.5m / s (3) Continuous reaction: the pre-mixed material is continuously fed into a multi-stage tubular reactor in series, the reactor is divided into front, middle and rear sections, the temperatures of each section are 40℃, 55℃ and 45℃ respectively, the pressure is 0.1MPa, and the total residence time is 15min; the multi-stage tubular reactor has 3 sections, the inner diameter of the pipe is 20mm, and the inner wall of the pipe is provided with spiral guide vanes; (4) Continuous separation: the reacted material is separated by a flash separator and a rectifying column in sequence, the flash separation condition is vacuum degree -0.06 MPa and temperature 60 ℃, the rectifying condition is normal pressure and column top temperature 85 ℃, and a crude product is obtained; in the step (4), the rectifying column is a packed column, the packing is ladder ring, the packing layer height is 3 m, and the reflux ratio is 1:0.5; (5) Refining: the crude product is impurity-removed by an ion exchange column, and then is distilled under reduced pressure, the condition is vacuum degree -0.09 MPa and temperature 110 ℃, and a cation etherifying agent product with purity ≥98.5% is obtained; (6) Product storage: the refined product is stored under nitrogen protection after being cooled to room temperature.

[0022] In the step (5), the ion exchange column is filled with strong acid cation exchange resin and strong base anion exchange resin, the filling volume ratio is 1:1, and the material residence time is 2 min.

[0023] The detection result is that the yield of the target product (3-chloro-2-hydroxypropyl trimethyl ammonium chloride) is 95.2%, the content of the by-product 1,3-dichloro-2-propanol is 0.08%, the product purity is 98.6%, the solvent recovery rate is 90.5%, and the single batch production cycle is 2.5 h.

[0024] Example 2 (1) Raw material pretreatment: triethylamine hydrochloride and a solvent are dissolved at 50 ℃ under stirring according to a mass ratio of 1:3.0, and a triethylamine hydrochloride solution is obtained; a catalyst solution with a mass concentration of 2.0% is prepared and reserved; the catalyst is tetraethylammonium bromide; and the solvent is methanol; (2) Pre-mixing: the triethylamine hydrochloride solution, the catalyst solution and epichlorohydrin are continuously fed into a static mixer by a metering pump, the molar ratio of triethylamine hydrochloride to epichlorohydrin is controlled to be 1:1.2, the catalyst solution is added in an amount of 0.5% of the mass of triethylamine hydrochloride, the mixing temperature is 35 ℃, and the material residence time is 10 min; in the step (2), the static mixer is an SX type, which is internally provided with 7 mixing elements, and the material flow rate is 2.0 m / s (3) Continuous reaction: the pre-mixed material is continuously fed into a multi-stage tubular reactor in series, the reactor is divided into a front section, a middle section and a rear section, the temperatures of the sections are 50 ℃, 65 ℃ and 55 ℃ respectively, the pressure is 0.3 MPa, and the total residence time is 30 min; the multi-stage tubular reactor has 5 stages, the inner diameter of the tube is 50 mm, and the inner wall of the tube is provided with spiral guide vanes.

[0025] (4) Continuous separation: the reacted material is separated by a flash separator and a rectifying column in sequence, the flash separation condition is vacuum degree -0.08 MPa and temperature 80 ℃, the rectifying condition is normal pressure and column top temperature 105 ℃, and a crude product is obtained; the rectifying column is a packed column, the packing is Bauer ring, the packing layer height is 6 m, and the reflux ratio is 1:1.5 (5) Purification: the crude product was purified by ion exchange column, and then was distilled under reduced pressure, with vacuum degree of -0.095 MPa and temperature of 130°C, to obtain cationic etherifying agent product with purity of ≥98.5%; (6) Product storage: the purified product was cooled to room temperature, and was stored under nitrogen protection.

[0026] In step (5), the ion exchange column was filled with strong acid cation exchange resin and strong base anion exchange resin, with volume ratio of 1:2, and the material residence time was 5 min.

[0027] The detection results were as follows: the yield of target product (3-chloro-2-hydroxypropyl trimethyl ammonium chloride) was 96.5%, the content of by-product 1,3-dichloro-2-propanol was 0.06%, the product purity was 99.1%, the solvent recovery rate was 92.3%, and the single batch production cycle was 2.3 h.

[0028] Example 3 (1) Raw material pretreatment: trimethylamine hydrochloride and solvent were stirred and dissolved at 40°C according to mass ratio of 1:1.8, to obtain trimethylamine hydrochloride solution; a catalyst solution with mass concentration of 1.2% was prepared and was ready for use; the catalyst was tetramethylammonium chloride; and the solvent was methanol; (2) Premixing: the trimethylamine hydrochloride solution, catalyst solution and epichlorohydrin were continuously fed into a static mixer through metering pumps, with molar ratio of trimethylamine hydrochloride to epichlorohydrin of 1:1.13, catalyst solution addition amount of 0.3% of the mass of trimethylamine hydrochloride, mixing temperature of 25°C, and material residence time of 6 min; in step (2), the static mixer was SK type, with 6 mixing elements inside, and the material flow rate was 1.2 m / s (3) Continuous reaction: the premixed material was continuously fed into a multi-stage tubular reactor in series, with the reactor divided into front section, middle section and rear section, with temperatures of 45°C, 60°C and 50°C respectively, pressure of 0.2 MPa, and total residence time of 22 min; the multi-stage tubular reactor had 3 stages, with inner diameter of 30 mm, and spiral guide vanes arranged on the inner wall; (4) Continuous separation: the reacted material was separated in sequence through a flash separator and a rectifying column, with flash conditions of vacuum degree of -0.07 MPa and temperature of 70°C, and rectifying conditions of normal pressure and column top temperature of 95°C, to obtain crude product; the rectifying column was a packed column, with stepped ring as packing, packing layer height of 4 m, and reflux ratio of 1:1.2; (5) Purification: the crude product was purified by ion exchange column, and then was distilled under reduced pressure, with vacuum degree of -0.09 MPa and temperature of 120°C, to obtain cationic etherifying agent product with purity of ≥98.5%; (6) Product storage: the purified product was cooled to room temperature, and was stored under nitrogen protection.

[0029] In step (5), the ion exchange column is filled with strong acid cation exchange resin and strong base anion exchange resin, the filling volume ratio is 1:1.5, and the material residence time is 2.5 min.

[0030] The detection result is as follows: the yield of the target product (3-chloro-2-hydroxypropyl trimethyl ammonium chloride) is 96.1%, the content of the by-product 1,3-dichloro-2-propanol is 0.05%, the product purity is 99.0%, the solvent recovery rate is 93.1%, and the single batch production cycle is 2.2 h.

[0031] Comparative Example 1 (traditional batch process, corresponding to the reference condition of Example 3) Raw material preparation: 10 g of trimethylamine hydrochloride (consistent with the amount of raw material of Example 3) and 18 g of methanol (mass ratio 1:1.8, same as the solvent ratio of Example 3) are put into a 100 mL batch three-necked reaction kettle, 0.03 g of solid tetramethylammonium chloride catalyst (consistent with the amount of catalyst of Example 3, accounting for 0.3% of the mass of trimethylamine hydrochloride) is directly added without preparing a catalyst solution; the molar ratio of epichlorohydrin to trimethylamine hydrochloride is 1:1.13 (same as the molar ratio of Example 3).

[0032] Batch reaction: start the stirring of the reaction kettle (speed 300 r / min), after warming up to 25℃, slowly add epichlorohydrin (addition time 1 h), after the addition is completed, control the reaction temperature at 50℃ (no staged temperature control), and react for 60 min under normal pressure (the total reaction time is 2.7 times of that of Example 3); Separation and purification: after the reaction is completed, stand for 1 h, directly remove the solvent by normal pressure rectification, the rectification tower is a packed tower (the packing is ladder ring, the layer height is 4 m, the reflux ratio is 1:1.2, which is consistent with the rectification parameters of Example 3), and the tower top temperature is 95℃; the crude product is not removed by ion exchange column, but directly distilled under reduced pressure at a vacuum degree of -0.09 MPa and a temperature of 120℃ to obtain the product.

[0033] Product storage: after natural cooling to room temperature, store in a sealed bottle (without nitrogen protection).

[0034] The detection result is as follows: the yield of the target product (3-chloro-2-hydroxypropyl trimethyl ammonium chloride) is 87.6%, the content of the by-product 1,3-dichloro-2-propanol is 0.48%, the product purity is 95.3%, the solvent recovery rate is 74.8%, and the single batch production cycle is 8.8 h.

[0035] Comparative Example 2 The difference between this comparative example and Example 3 is that, In step (3), the premixed raw materials were directly pumped into a single-stage tubular reactor (without helical guide vanes, tube inner diameter 30 mm) by a metering pump, the reaction temperature was controlled at 50℃ (constant temperature), the pressure was 0.2 MPa, and the residence time of the material was 22 min; In step (5), the crude product was directly subjected to vacuum distillation (vacuum degree -0.09 MPa, temperature 120℃) without ion exchange column impurity removal, The other steps were consistent with those in Example 3.

[0036] The detection results were as follows: the yield of the target product was 92.5%, the content of the by-product 1,3-dichloro-2-propanol was 0.27%, the purity of the product was 96.3%, the solvent recovery rate was 91.0%, and the single-batch production cycle was 3.1 h.

[0037] It should be noted that, in this document, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or apparatus that comprises a list of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0038] The above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0039] Those skilled in the art should understand that the above only describes several specific embodiments of the present application, rather than all embodiments.

Claims

1. A continuous production process of a cationic etherifying agent, characterized by, The application relates to a continuous operation process for preparing a cationic etherification agent by using epichlorohydrin and trimethylamine hydrochloride as raw materials, under the action of a solvent and a catalyst, through the following steps of pre-mixing, continuous reaction, continuous separation and refining. (1) raw material pretreatment: stirring and dissolving trimethylamine hydrochloride and a solvent according to a mass ratio of 1:1.5-3.0 at 30-50 DEG C to obtain a trimethylamine hydrochloride solution; preparing a catalyst solution with a mass concentration of 0.5-2.0% for standby; the catalyst is a quaternary ammonium salt catalyst; (2) pre-mixing: continuously feeding the trimethylamine hydrochloride solution, the catalyst solution and epichlorohydrin into a static mixer through metering pumps, controlling the molar ratio of trimethylamine hydrochloride to epichlorohydrin to be 1:1.05-1.2, the mixing temperature to be 20-35 DEG C and the material residence time to be 3-10 min; (3) continuous reaction: continuously feeding the pre-mixed material into a multi-stage tubular reactor in series, the reactor is divided into a front section, a middle section and a rear section, the temperatures of the sections are 40-50 DEG C, 55-65 DEG C and 45-55 DEG C respectively, the pressure is 0.1-0.3 MPa, and the total residence time is 15-30 min; (4) continuous separation: sequentially separating the reacted material through a flash separation device and a rectifying tower, the flash separation conditions are a vacuum degree of-0.06 to-0.08 MPa and a temperature of 60-80 DEG C, the rectifying conditions are normal pressure and a tower top temperature of 85-105 DEG C, and a crude product is obtained; (5) refining: removing impurities from the crude product through an ion exchange column, and then performing vacuum distillation under the conditions of a vacuum degree of-0.09 to-0.095 MPa and a temperature of 110-130 DEG C, so as to obtain a cationic etherification agent product with a purity of greater than or equal to 98.5%; (6) product storage: storing the refined product under nitrogen protection after cooling to room temperature. In the step (1), the solvent is one or a mixture of more than one of deionized water, methanol and ethanol; In the step (1), the quaternary ammonium salt catalyst is one of tetramethylammonium chloride and tetraethylammonium bromide.

2. The continuous production process of cationic etherified agent according to claim 1, characterized in that, In the step (2), the static mixer is an SK type or an SX type, is internally provided with 5-10 mixing elements, and the material flow speed is 0.5-2.0 m / s.

3. The continuous production process of cationic etherified agent according to claim 1, characterized in that, In the step (2), the catalyst solution is added in an amount of 0.1-0.5% of the mass of the trimethylamine hydrochloride.

4. The continuous production process of cationic etherifying agent according to claim 1, characterized in that, In the step (3), the multi-stage tubular reactor has 3-5 stages, the inner diameter of the tube is 20-50 mm, and the inner wall of the tube is provided with spiral guide vanes.

5. The continuous production process of cationic etherified agent according to claim 1, characterized by, In the step (4), the rectifying tower is a packed tower, the packing is a Pall ring or a stepped ring, the packing layer is 3-6 m high, and the reflux ratio is 1:0.5-1.

5.

6. The continuous production process of cationic etherified agent according to claim 1, characterized by, In the step (5), the ion exchange column is filled with strong acid cation exchange resin and strong base anion exchange resin, the filling volume ratio is 1:1-2, and the material residence time is 2-5 min.