Method for synthesizing high-purity odorless cationic etherifying agent by microchannel reactor

Abstract

The invention provides a method for synthesizing a high-purity odorless cationic etherifying agent by a microchannel reactor, which comprises the following steps: trimethylamine and hydrochloric acid react in a reaction module 1 of the microchannel reactor to obtain an intermediate trimethylamine hydrochloride, and the intermediate is connected with a feed port of a reaction module 2 through a discharge port of the reaction module 1; enabling the intermediate and epoxy chloropropane to react in a reaction module 2 under the condition of an acid catalyst to obtain a cationic etherifying agent crude product, and performing post-treatment to obtain the high-purity odorless cationic etherifying agent. The microchannel reactor is adopted, the pH regulator is added, the reaction yield is increased, free trimethylamine is eliminated, the high-quality odorless cationic etherifying agent is synthesized, the production cost is saved, generation of by-products and industrial wastewater is reduced, and compared with a traditional process, the method has the advantages of being high in conversion rate, low in energy consumption and the like.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of cationic etherifying agents, in particular to a method for synthesizing a high-purity odorless cationic etherifying agent by using a microchannel reactor. Background Art

[0002] Cationic etherifying agents are widely used in the fine chemical industry and are multifunctional chemical products. Two commercially available products are available: a solid and an aqueous solution. The aqueous solution is a colorless, transparent liquid, typically 69% aqueous at room temperature. Under alkaline conditions, this product rapidly converts to a highly reactive epoxidized structure, allowing it to readily react with compounds containing active hydrogen to yield multifunctional chemicals containing quaternary ammonium groups.

[0003] Cationic etherifying agents are widely used in the papermaking, daily chemical, petroleum, and water treatment industries. They are used as etherifying agents for cationic starch, cationic polysaccharides, and modified guar gum. They are used in the preparation of cationic starch, cationic polyacrylamide, electroplating additives, textile printing and dyeing auxiliaries, antistatic agents, and papermaking auxiliaries. They can also be used as cationic surfactants, water treatment flocculants, and in the textile, conductive coating, electroplating, and cosmetics industries.

[0004] Existing technologies, such as those in Chinese patents CN107353213A, CN107349869A, and CN205556516U, all utilize a kettle-type reactor for synthesis, involving a series of steps, including preparation of trimethylamine hydrochloride, low-temperature addition of epichlorohydrin, room-temperature reaction, and product purification. While these processes are mature, the products suffer from a strong ammonia odor, hindering their expansion into a wider range of applications.

[0005] Therefore, developing a synthesis method for high-purity and odorless cationic etherifying agents and further improving product quality have become powerful means to expand the scale of product application, enhance product competitiveness, improve production efficiency, and expand market share. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for synthesizing a high-purity odorless cationic etherifying agent using a microchannel reactor, thereby achieving continuous and efficient synthesis reaction, shortening reaction time, improving reaction yield and product purity, improving the working environment, and saving production costs, thereby solving the above-mentioned technical problems existing in the prior art.

[0007] The present invention is achieved by adopting the following technical solutions:

[0008] A method for synthesizing a high-purity, odorless cationic etherifying agent in a microchannel reactor comprises the following steps: trimethylamine and hydrochloric acid react in a reaction module 1 of a microchannel reactor to obtain an intermediate trimethylamine hydrochloride; the intermediate is connected to a feed port of a reaction module 2 via a discharge port of the reaction module 1; the intermediate reacts with epichlorohydrin in the reaction module 2 under acidic catalyst conditions to obtain a crude cationic etherifying agent product; and the high-purity, odorless cationic etherifying agent is obtained through post-processing.

[0009] As a preferred technical solution, the above-mentioned synthesis method specifically comprises the following steps:

[0010] S1, trimethylamine and hydrochloric acid are simultaneously pumped into the reaction module 1 of the microchannel reactor through a gas flow meter and a metering pump;

[0011] S2. In reaction module 1, the pH value is adjusted to 7-10, the reaction temperature is adjusted to 10-70°C by the temperature control system, and the residence time is 0.5-2.0 min;

[0012] S3, the trimethylamine hydrochloride generated in the reaction module 1 is pumped into the reaction module 2, and at the same time, the epichlorohydrin and the acidic catalyst are pumped into the reaction module 2 respectively through metering pumps;

[0013] S4, in reaction module 2, the reaction temperature is adjusted to 5-50°C by the temperature control system, and the reaction residence time is 0.5-3min;

[0014] S5. The crude cationic etherifying agent synthesized in reaction module 2 is introduced into an adjustment device, a pH regulator is added to eliminate free trimethylamine and the pH value is adjusted, and the product is purified by distillation to obtain the high-purity odorless cationic etherifying agent.

[0015] In step S2, the raw material ratio is adjusted to obtain a suitable pH value, preferably between 7.5 and 9. The preferred reaction temperature is 10-50°C.

[0016] Furthermore, the molar ratio of trimethylamine hydrochloride to epichlorohydrin is 1:0.95-1.1. The preferred molar ratio is trimethylamine hydrochloride:epichlorohydrin=1:1-1.05.

[0017] The microstructure within a microchannel reactor gives it an extremely large specific surface area, potentially hundreds or even thousands of times that of a stirred tank. This provides excellent heat and mass transfer capabilities, enabling instantaneous, uniform mixing of materials and efficient heat transfer. Therefore, many reactions impossible in conventional reactors can now be performed in a microreactor. The inventors have discovered that synthesizing a cationic etherifying agent in a microchannel reactor using a two-step process—namely, in the first step, trimethylamine and hydrochloric acid are mixed in the microchannel reactor to produce trimethylamine hydrochloride, and in the second step, trimethylamine hydrochloride is reacted with epichlorohydrin in the presence of an acid catalyst to produce the cationic etherifying agent—can surprisingly significantly reduce the content of inorganic impurities. Based on these findings, the inventors completed the present invention.

[0018] The acidic catalyst is selected from at least one of dilute hydrochloric acid, dilute sulfuric acid and dilute nitric acid; the amount of the acidic catalyst added is 0.7-1.5% of the total mass of trimethylamine hydrochloride and epichlorohydrin.

[0019] The pH adjuster is not particularly limited, and can be any organic or inorganic acid commonly used in the art that does not affect the etherification effect, such as, but not limited to, hydrochloric acid, boric acid, and citric acid.

[0020] The microchannel reactor is made of quartz glass, borosilicate glass, silicon carbide or RPTFE.

[0021] The inner diameter of the pipeline of the microchannel reactor is 10 μm-200 μm.

[0022] Compared with traditional chemical equipment, microchannel reactors have a large specific surface area and sufficient contact area between the fluid and the wall, so the heat exchange efficiency and reaction rate are significantly improved.

[0023] Compared with the traditional kettle process, the present invention improves the reaction yield by adopting a microchannel reactor and adding a pH regulator, while eliminating free trimethylamine to synthesize a high-quality odorless cationic etherifying agent, thereby saving production costs and reducing the generation of by-products and industrial wastewater. The microchannel reactor can be intelligently remotely controlled, and the reaction process has good sealing performance, which reduces environmental pollution caused by the escape of raw materials during the feeding process. The product produced by the method of the present invention has a purity of greater than 99% and a reaction yield of greater than 99%. Compared with the traditional process, it has the advantages of high conversion rate, low energy consumption, and the like. DETAILED DESCRIPTION

[0024] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are provided for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0025] The instruments or raw materials in the present invention without indicating the manufacturer are all conventional commercial instruments or raw materials.

[0026] Unless otherwise mentioned, the detection indicators involved in the embodiments of the present invention are detected using conventional detection methods in the art.

[0027] Example 1

[0028] Step 1) 1.18 kg of trimethylamine and 2.36 kg of hydrochloric acid were simultaneously pumped into the microchannel reactor reaction module 1 through the gas flow meter 1 and the metering pump 2 respectively;

[0029] Step 2) In reaction module 1, the pH value of the material is adjusted to 7.5 by adjusting the raw material ratio, the reaction temperature is adjusted to 50°C by the temperature control system, and the residence time is maintained at 0.5 min;

[0030] Step 3) The trimethylamine hydrochloride generated in the reaction module 1 is pumped into the reaction module 2, and at the same time, 2.05 kg of epichlorohydrin and 1.5% dilute hydrochloric acid of the total mass of the raw materials are pumped into the reaction module 2 through metering pumps 3 and 4 respectively;

[0031] Step 4) In the reaction module 2, the reaction temperature was adjusted to 50° C. by the temperature control system, and the reaction residence time was 0.5 min;

[0032] Step 5) The crude cationic etherifying agent synthesized in the reaction module 2 is introduced into the adjustment device, and boric acid is added to eliminate free trimethylamine while adjusting the pH to 6.4. The product is purified by distillation and the effective content is adjusted to obtain a high-quality odorless cationic etherifying agent product.

[0033] The microchannel reactor is made of quartz glass, and the inner diameter of the microchannel reactor is 10 μm.

[0034] Example 2

[0035] Step 1) 1.20 kg of trimethylamine and 2.36 kg of hydrochloric acid were simultaneously pumped into the microchannel reactor reaction module 1 through the gas flow meter 1 and the metering pump 2 respectively;

[0036] Step 2) In reaction module 1, the raw material ratio is adjusted to a pH of 9.0, the reaction temperature is adjusted to 30° C. by the temperature control system, and the residence time is maintained at 1 min;

[0037] Step 3) The trimethylamine hydrochloride generated in reaction module 1 is pumped into reaction module 2, and at the same time, 1.77 kg of epichlorohydrin and 1.0% dilute sulfuric acid of the total mass of the raw materials are pumped into reaction module 2 through metering pump 3 and metering pump 4 respectively;

[0038] Step 4) In the reaction module 2, the reaction temperature is adjusted to 30°C by the temperature control system, and the reaction residence time is 2 minutes;

[0039] Step 5) The crude cationic etherifying agent synthesized in the reaction module 2 is introduced into the adjustment device, citric acid is added to eliminate free trimethylamine, and the pH is adjusted to 6.7. The product is purified by distillation and the effective content is adjusted to obtain a high-quality odorless cationic etherifying agent product.

[0040] The microchannel reactor is made of high borosilicate glass, and the inner diameter of the microchannel reactor is 100 μm.

[0041] Example 3

[0042] Step 1) 1.19 kg of trimethylamine and 2.36 kg of hydrochloric acid were simultaneously pumped into the microchannel reactor reaction module 1 through the gas flow meter 1 and the metering pump 2 respectively;

[0043] Step 2) In reaction module 1, the pH value of the material is adjusted to 8.0 by adjusting the raw material ratio, the reaction temperature is adjusted to 10°C by the temperature control system, and the residence time is maintained at 2 minutes;

[0044] Step 3) The trimethylamine hydrochloride generated in reaction module 1 is pumped into reaction module 2, and at the same time, 1.96 kg of epichlorohydrin and 0.7% dilute nitric acid of the total mass of the raw materials are pumped into reaction module 2 through metering pump 3 and metering pump 4 respectively;

[0045] Step 4) In the reaction module 2, the reaction temperature is adjusted to 10°C by the temperature control system, and the reaction residence time is 2 minutes;

[0046] Step 5) The crude cationic etherifying agent synthesized in the reaction module 2 is introduced into the adjustment device, citric acid is added to eliminate free trimethylamine, and the pH is adjusted to 6.5. The product is purified by distillation and the effective content is adjusted to obtain a high-quality odorless cationic etherifying agent product.

[0047] The material of the microchannel reactor is RPTFE; the inner diameter of the pipeline of the microchannel reactor is 50 μm.

[0048] Example 4

[0049] Step 1) 1.18 kg of trimethylamine and 2.36 kg of hydrochloric acid were simultaneously pumped into the microchannel reactor reaction module 1 through the gas flow meter 1 and the metering pump 2 respectively;

[0050] Step 2) In reaction module 1, the pH value of the material is adjusted to 7.5 by adjusting the raw material ratio, and the reaction temperature is adjusted to 40°C by the temperature control system, and the residence time is maintained at 1 min;

[0051] Step 3) The trimethylamine hydrochloride generated in reaction module 1 is pumped into reaction module 2, and at the same time, 1.86 kg of epichlorohydrin and 1.2% dilute hydrochloric acid of the total mass of the raw materials are pumped into reaction module 2 through metering pump 3 and metering pump 4 respectively;

[0052] Step 4) In the reaction module 2, the reaction temperature was adjusted to 15°C by the temperature control system, and the reaction residence time was 1.5 min;

[0053] Step 5) The crude cationic etherifying agent synthesized in the reaction module 2 is introduced into the adjustment device, citric acid is added to eliminate free trimethylamine, and the pH is adjusted to 6.2. The product is purified by distillation and the effective content is adjusted to obtain a high-quality odorless cationic etherifying agent product.

[0054] The material of the microchannel reactor is silicon carbide; the inner diameter of the pipeline of the microchannel reactor is 200 μm.

[0055] Example 5

[0056] Step 1) 1.18 kg of trimethylamine and 2.36 kg of hydrochloric acid were simultaneously pumped into the microchannel reactor reaction module 1 through the gas flow meter 1 and the metering pump 2 respectively;

[0057] Step 2) In reaction module 1, the pH value of the material is adjusted to 7.5 by adjusting the raw material ratio, and the reaction temperature is adjusted to 40°C by the temperature control system, and the residence time is maintained at 1 min;

[0058] Step 3) The trimethylamine hydrochloride generated in reaction module 1 is pumped into reaction module 2, and at the same time, 1.81 kg of epichlorohydrin and 1.2% dilute hydrochloric acid of the total mass of the raw materials are pumped into reaction module 2 through metering pump 3 and metering pump 4 respectively;

[0059] Step 4) In the reaction module 2, the reaction temperature is adjusted to 5°C by the temperature control system, and the reaction residence time is 3 minutes;

[0060] Step 5) The crude cationic etherifying agent synthesized in the reaction module 2 is introduced into the adjustment device, citric acid is added to eliminate free trimethylamine, and the pH is adjusted to 6.5. The product is purified by distillation and the effective content is adjusted to obtain a high-quality odorless cationic etherifying agent product.

[0061] The material of the microchannel reactor is silicon carbide; the inner diameter of the pipeline of the microchannel reactor is 100 μm.

[0062] Comparative Example

[0063] (1) 350 g of 31% hydrochloric acid was pumped into a reactor, stirring was started, and 180 g of trimethylamine was slowly introduced over 3 hours, maintaining the temperature at 40° C. During the reaction, the reaction was continued at room temperature for 60 minutes after all the trimethylamine was added to the reactor.

[0064] (2) Maintaining the temperature at 15°C, start the metering pump and add 280 g of epichlorohydrin dropwise to the reactor over 4 hours. Two hours after the start of the addition, add an acidic catalyst (1.2% by weight of the total weight of the raw materials) and adjust the pH to 9 to maintain a rapid reaction environment.

[0065] (3) After the addition of epichlorohydrin is completed, the temperature is raised to 40°C and the reaction is continued at this temperature for 2 hours.

[0066] (4) The crude cationic etherifying agent product is introduced into an adjusting device, citric acid is added to eliminate free trimethylamine, and the pH is adjusted to 6.5. The product is purified by distillation and the effective content is adjusted to obtain a cationic etherifying agent product.

[0067] The following tests were performed on the samples of each embodiment and comparative example:

[0068] 1. Effective content detection: The effective content is detected by hydrochloric acid back titration method.

[0069] 2. Detection of inorganic impurity content: Detection is carried out through gas chromatography and ion chromatography.

[0070] 3. pH value detection: Use Leiji PHS-2F pH meter.

[0071] The test results are shown in Table 1.

[0072] Table 1 Sample test data

[0073]

[0074] It can be seen from the test results that the product obtained by the method of the present invention has a low total content of inorganic impurities.

[0075] Those skilled in the art will appreciate that the above embodiments are intended to be illustrative only and are not intended to limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and illustrated in the embodiments. Any variations or modifications may be made to the embodiments of the present invention without departing from the principles described.

Claims

1. A method for synthesizing a high-purity, tasteless cationic etherifying agent using a microchannel reactor, characterized in that: The method comprises the following steps: trimethylamine and hydrochloric acid react in a reaction module 1 of a microchannel reactor to obtain an intermediate trimethylamine hydrochloride; the intermediate is connected to a feed port of a reaction module 2 through a discharge port of the reaction module 1; the intermediate reacts with epichlorohydrin in the reaction module 2 under an acidic catalyst condition to obtain a crude cationic etherifying agent product; and the high-purity odorless cationic etherifying agent is obtained through post-treatment.

2. The method according to claim 1, characterized in that The specific steps include: S1, pumping trimethylamine and hydrochloric acid into the reaction module 1 of the microchannel reactor simultaneously through a gas flow meter and a metering pump; S2, in reaction module 1, the pH value is adjusted to 7-10, the reaction temperature is adjusted to 10-70°C by the temperature control system, and the residence time is 0.5-2.0min; S3, pumping the trimethylamine hydrochloride generated in reaction module 1 into reaction module 2, and simultaneously pumping epichlorohydrin and the acidic catalyst into reaction module 2 through metering pumps respectively; S4, in reaction module 2, the reaction temperature is adjusted to 5-50°C by the temperature control system, and the reaction residence time is 0.5-3min; S5. The crude product of the cationic etherifying agent synthesized in the reaction module 2 is introduced into the adjusting device, a pH adjusting agent is added to eliminate free trimethylamine and the pH value is adjusted at the same time, and the product is purified by distillation to obtain the high-purity odorless cationic etherifying agent.

3. The method according to claim 1, characterized in that In step S2, the pH value of the material is adjusted to be between 7.5 and 9 by adjusting the raw material ratio; and the reaction temperature is 10-50°C.

4. The method according to claim 1, characterized in that The molar ratio of trimethylamine hydrochloride to epichlorohydrin is 1:1-1.

05.

5. The method according to claim 1, characterized in that The molar ratio of trimethylamine hydrochloride to epichlorohydrin is 1:0.95-1.

1.

6. The method according to claim 1, characterized in that The acidic catalyst is selected from at least one of dilute hydrochloric acid, dilute sulfuric acid and dilute nitric acid, and its addition amount is 0.7-1.5% of the total mass of trimethylamine hydrochloride and epichlorohydrin.

7. The method according to claim 1, characterized in that The pH adjuster is selected from at least one of hydrochloric acid, boric acid or citric acid.

8. The method according to claim 1, characterized in that The microchannel reactor is made of quartz glass, high borosilicate glass, silicon carbide or RPTFE.

9. The method according to claim 1, characterized in that The inner diameter of the pipeline of the microchannel reactor is 10 μm-200 μm.

Images