Preparation method and system of antioxidant TMQ

Abstract

This invention relates to the field of rubber additives and discloses a method and system for preparing antioxidant TMQ. The method includes: (1) reacting aniline with acetone in the presence of a hydrochloric acid catalyst to obtain a TMQ condensation solution; (2) separating the obtained TMQ condensation solution to obtain light and heavy components, while controlling the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components; (3) filtering the obtained heavy components, the obtained filtrate being the TMQ reaction solution, and the obtained filter cake being returned to the condensation reaction in step (1); (4) adding liquid alkali to the obtained TMQ reaction solution for neutralization, and distilling the obtained oil phase to obtain antioxidant TMQ. By separating the light and heavy components in the TMQ condensation reaction solution and controlling the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components, the hydrochloric acid catalyst is easily filtered and separated from the heavy components, thereby allowing a large amount of hydrochloric acid to be reused in the catalytic reaction.

Description

Technical Field

[0001] This invention relates to the field of rubber additives, and more specifically to a method and system for preparing an antioxidant TMQ. Background Technology

[0002] Antioxidant TMQ, also known as antioxidant RD, is a collective term for the di, tri, and tetrapolymers of 2,2,4-trimethyl-1,2-dihydroquinoline. It is primarily used as an antioxidant in rubber and rubber products, suitable for natural rubber, synthetic rubber, and latex. It strongly inhibits the catalytic oxidation of harmful metal ions such as copper and manganese, exhibits good compatibility with rubber, low volatility, minimal blooming, and high resistance to extraction. It is widely used in the domestic and international rubber processing industry; it is required in ordinary tires, radial tires, and other rubber products to achieve better protective performance.

[0003] The general process for producing antioxidant TMQ is as follows: aniline is dehydrated with hydrochloric acid to obtain aniline hydrochloride; aniline hydrochloride and acetone undergo a polycondensation reaction to obtain TMQ polycondensation solution; the polycondensation solution is neutralized with liquid alkali and dehydrated; then the oil phase is distilled and granulated to obtain the finished TMQ product.

[0004] CN108003095A discloses several commonly used production methods for TMQ: 1) Batch reactor method: Aniline and catalyst are added to the reactor at once, while acetone is fed continuously dropwise. The reaction time is generally 2-7 hours. Under atmospheric pressure, the reaction temperature is controlled at 90-150℃. Acetone is directly separated and recovered through a fractionation column on the reactor and then reused in the raw material storage tank. 2) Continuous tower method: Aniline and catalyst titanate are continuously fed from the top of the tower. Acetone is vaporized and fed from the bottom of the tower in the gas phase, and the reaction proceeds continuously in the tower. Under atmospheric pressure, the reaction temperature is controlled at 90-150℃. The residence time of the materials in the tower is 3-7 hours. Acetone and water produced during the reaction are distilled off simultaneously, and then acetone is directly separated and recovered through a fractionation column. Meanwhile, the antioxidant TMQ polycondensation reaction liquid generated in the reaction flows continuously into the receiving tank at the bottom of the tower. The TMQ condensation solution in the reactor or receiving tank is neutralized with liquid alkali, allowed to stand and separate into layers, and the oil phase is distilled under a vacuum of -0.098 MPa and a controlled temperature of 180-260℃. After cooling, the residue is granulated to obtain the finished antioxidant TMQ product.

[0005] CN103539962A discloses a method for preparing the low-amine rubber antioxidant TMQ. Aniline and hydrochloric acid are added to a reactor, stirred, and heated to 130°C for 30 minutes. The amount of hydrochloric acid used is 6-10% of the weight of aniline. 2,2,4-trimethyl-1,2-dihydroquinoline monomer is added to the reactor in an amount of 70-80% of the aniline mass. Acetone is continuously added dropwise at a temperature controlled at 120-125°C, with a mass ratio of aniline to acetone of 1:1-4. The addition time and temperature are controlled. After the addition is complete, the temperature is maintained at 140°C for 4 hours. Heating is stopped, and an aqueous sodium hydroxide solution is added and stirred for 30 minutes. After neutralization, the pH value is controlled at 11, and the mixture is allowed to stand for 60 minutes. The aqueous phase is separated to obtain the organic phase. The monomer is removed by distillation under vacuum to obtain the antioxidant TMQ product.

[0006] Because the environmentally friendly processes using molecular sieves and solid acids are not yet mature, they suffer from problems such as unstable operation and high costs. Currently, the main production method for the antioxidant TMQ at home and abroad is to use hydrochloric acid as a catalyst to carry out the polycondensation reaction of aniline and acetone. Its main advantages are simple synthesis method, short process, and mature technology. The disadvantage is that the hydrochloric acid catalyst cannot be reused, requiring a large amount of liquid alkali for neutralization, resulting in high-salt wastewater with a salt (sodium chloride) content as high as 10-18% and containing a large amount of organic matter. High-salt wastewater cannot be used directly, is difficult to treat or has poor economic efficiency, thus causing environmental problems. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of existing technologies, such as the inability to reuse hydrochloric acid catalysts, the need for large amounts of liquid alkali neutralization, and the generation of high-salt wastewater containing large amounts of organic matter, and to provide a method and system for preparing the antioxidant TMQ.

[0008] To achieve the above objectives, a first aspect of the present invention provides a method for preparing an antioxidant TMQ, wherein the method includes:

[0009] (1) In the presence of hydrochloric acid catalyst, aniline and acetone were subjected to polycondensation reaction to obtain TMQ polycondensation solution;

[0010] (2) The obtained TMQ condensation liquid is separated to obtain light components and heavy components respectively, while controlling the molar ratio of aniline to hydrochloric acid catalyst in the heavy components;

[0011] (3) The obtained heavy components are filtered, and the filtrate is the TMQ reaction solution. The filter cake is returned to the polycondensation reaction in step (1).

[0012] (4) The obtained TMQ reaction solution is neutralized by adding liquid alkali, and the resulting oil phase is distilled to obtain the antioxidant TMQ.

[0013] A second aspect of the present invention provides a system for preparing an antioxidant TMQ, wherein the system comprises: a polycondensation reaction device and a separation device connected in sequence; a filtration device and a recovery device connected to the separation device; a neutralization device connected to the filtration device; and a distillation device connected to the neutralization device; wherein the filtration device and the recovery device are each connected to the polycondensation reaction device.

[0014] Through the above technical solution, this invention separates the light and heavy components in the TMQ polycondensation reaction solution. During the separation process, the molar amount of aniline in the heavy components is controlled, facilitating the filtration and separation of the hydrochloric acid catalyst from the heavy components. This allows a large amount of hydrochloric acid to be reused in the catalytic reaction, eliminating the need for extensive liquid alkali neutralization and reducing high-salt wastewater volume by over 97%. The TMQ finished product contains more than 50% di, tri, and tetramers of the effective component 2,2,4-trimethyl-1,2-dihydroquinoline, less than 0.5% of the harmful component IBA (isopropyl diphenylamine), and has a softening point of 86-97℃. Therefore, in subsequent continuous production processes, the amount of high-salt wastewater generated by acid-base neutralization is reduced by more than 97%, making it a green and environmentally friendly synthesis process. Attached Figure Description

[0015] Figure 1 This invention provides a preparation system for the antioxidant TMQ.

[0016] Explanation of reference numerals in the attached figures

[0017] 1. Polycondensation reactor; 2. Separation unit; 3. Recovery unit; 4. Filtration unit; 5. Neutralization unit; 6. Distillation unit Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] The first aspect of this invention provides a method for preparing the antioxidant TMQ, wherein the method includes:

[0020] (1) In the presence of hydrochloric acid catalyst, aniline and acetone were subjected to polycondensation reaction to obtain TMQ polycondensation solution;

[0021] (2) The obtained TMQ condensation liquid is separated to obtain light components and heavy components respectively, while controlling the molar ratio of aniline to hydrochloric acid catalyst in the heavy components;

[0022] (3) The obtained heavy components are filtered, and the filtrate is the TMQ reaction solution. The filter cake is returned to the polycondensation reaction in step (1).

[0023] (4) The obtained TMQ reaction solution is neutralized by adding liquid alkali, and the resulting oil phase is distilled to obtain the antioxidant TMQ.

[0024] In this invention, the light and heavy components in the TMQ polycondensation reaction liquid are separated. During the separation process, the molar ratio of aniline to the hydrochloric acid catalyst in the heavy component is controlled to be 0.3-2:1, so that a large amount of organic hydrochloride enters the heavy component and precipitates out. Then, the filter cake is filtered and the filtration conditions are controlled. The resulting filter cake contains a large amount of organic hydrochloride, which can be directly recycled to the polycondensation reaction in step (1). Thus, a large amount of hydrochloric acid is recycled to the catalytic reaction, without the need for a large amount of liquid alkali to neutralize it, reducing the amount of high-salt wastewater by more than 97%.

[0025] In some specific embodiments of the present invention, in step (1), the molar ratio of aniline, acetone and hydrochloric acid catalyst is 1:1.5-10:0.05-0.5.

[0026] In some specific embodiments of the present invention, in step (1), the polycondensation reaction time is 0.001-10h, and the polycondensation reaction temperature is 90-200℃.

[0027] In some specific embodiments of the present invention, in step (2), the separation is selected from distillation, rectification or fractional distillation.

[0028] In some specific embodiments of the present invention, in step (2), the light component contains 10-40 wt% acetone, 10-40 wt% water, 5-20 wt% aniline, and 0-30 wt% other impurities. By controlling the separation and purification conditions of the light component, the aniline and acetone are separated to the greatest extent, thereby returning the aniline and acetone to the polycondensation reaction and realizing the recycling of raw materials.

[0029] In some specific embodiments of the present invention, the light component is separated and purified and then returned as a recycled raw material to the polycondensation reaction in step (1).

[0030] In some specific embodiments of the present invention, the separation and purification of the light components includes: first, controlling the separation conditions to be at atmospheric pressure and a gas phase temperature of 0-120°C, separating and recovering acetone and a small amount of impurities (amines, water, isopropylidene acetone); then, controlling the separation conditions to be at atmospheric pressure or reduced pressure, with a gas phase temperature of 121-220°C under atmospheric pressure and 0-90°C under reduced pressure (1-200 Pa), separating and recovering aniline and a small amount of impurities (acetone, water, 2,2,4-trimethyl-1,2-dihydroquinoline and dimers and polymers, isopropyl diphenylamine, etc.), and returning the obtained acetone and aniline as raw materials to the polycondensation reaction. The separation and purification conditions of the light components described in the present invention can separate and return the acetone and aniline remaining from the polycondensation reaction to the reaction, thereby achieving the recycling of raw materials and reducing waste.

[0031] In some specific embodiments of the present invention, the separation and purification of the heavy components includes: the separation conditions are atmospheric pressure or reduced pressure; under atmospheric pressure, the gas phase temperature is 0-220°C, and the heavy components are separated; under reduced pressure conditions of 1-500 Pa, the gas phase temperature is 0-90°C, and the heavy components are separated.

[0032] In some specific embodiments of the present invention, in step (2), the separation process conditions are controlled. The separation conditions are atmospheric pressure or reduced pressure. Under atmospheric pressure, the gas phase temperature is 0-220°C, and heavy components are separated. Under reduced pressure, the gas phase temperature is 0-90°C, and heavy components are separated. At the same time, the aniline content in the heavy components is detected, and the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components is controlled to be 0.3-2:1, for example, 0.5:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.8:1, and any value in any range of any two values, preferably 0.9-1.1:1. By controlling the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components, within this range, organic compounds such as aniline and hydrochloric acid form salts. The hydrochloric acid has the lowest solubility in the system and is most easily separated from the heavy components by filtration. This allows more salt to be stored in the filter cake and returned to the polycondensation reaction. At the same time, the resulting TMQ reaction solution contains fewer salts, greatly reducing the amount of neutralizing alkali required, thereby significantly reducing the amount of saline wastewater.

[0033] In some specific embodiments of the present invention, the recombinant component contains 5-20 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 20-60 wt% of TMQ, 0.5-10 wt% of aniline, 0.5-2 wt% of isopropyl diphenylamine, 1-10 wt% of aniline hydrochloride, 0.5-2 wt% of isopropyl diphenylamine hydrochloride, 0.5-5 wt% of a pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 0.1-2 wt% of a hexamer, and 0-30 wt% of other impurities. The other impurities may be one or more of the following structural formulas: When the content of the heavy components is controlled within the above range, the amount of organic hydrochloride formed is the largest, and the hydrochloric acid is most easily filtered and separated from the heavy components, so that more salt is returned to the polycondensation reaction in the filter cake after filtration.

[0034] In some specific embodiments of the present invention, in step (3), the filtration temperature is 80-150°C. By controlling the above filtration temperature, the solubility of the crystals is reduced and the solidification and clogging of the system by the TMQ reaction solution can be prevented can be prevented. Filtration using a filter with a pore size of 1-5 micrometers can control the size of the crystals.

[0035] In some specific embodiments of the present invention, in step (3), the filter cake contains aniline hydrochloride, 2,2,4-trimethyl-1,2-dihydroquinoline hydrochloride, TMQ hydrochloride, and propyl diphenylamine hydrochloride. By controlling the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components, within this range, organic compounds such as aniline and hydrochloric acid form salts, resulting in the lowest solubility of hydrochloric acid in the system, making it easiest to filter and separate from the heavy components. This allows more salt to be retained in the filter cake through filtration and returned to the polycondensation reaction.

[0036] In some specific embodiments of the present invention, in step (3), preferably, the filter cake is added to hydrochloric acid and then returned to the polycondensation reaction, wherein the amount of hydrochloric acid added satisfies the requirement in step (1) that the molar ratio of aniline, acetone, and hydrochloric acid catalyst is 1:1.5-10:0.05-0.5. Alternatively, the filter cake can be returned to the polycondensation reaction without adding hydrochloric acid.

[0037] In some specific embodiments of the present invention, in step (3), the TMQ reaction solution contains: 5-25 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 20-65 wt% of TMQ, 0.01-15 wt% of aniline, 0.01-2.5 wt% of isopropyl diphenylamine, 0.01-2 wt% of aniline hydrochloride, 0-0.5 wt% of isopropyl diphenylamine hydrochloride, 0.5-8 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 0.1-4 wt% of the hexamer, and 0-30 wt% of other impurities. As can be seen from the above components, the amount of organic hydrochloride in the obtained TMQ reaction solution is relatively small after filtration. By controlling the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components, most of the salt is retained in the filter cake after filtration and returned to the polycondensation reaction, thus achieving the recycling of hydrochloric acid.

[0038] In some specific embodiments of the present invention, in step (4), the alkali is selected from at least one of sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

[0039] In some specific embodiments of the present invention, in step (4), the pH of the product obtained by neutralization is 8-12.

[0040] In some specific embodiments of the present invention, in step (4), the weight ratio of the liquid alkali to the TMQ reaction solution is 0.0001-0.001:1, ensuring that the molar ratio of the added liquid alkali to the residual hydrochloric acid in the TMQ reaction solution is 1.05-1.2:1, and adjusting the pH of the solution to alkaline.

[0041] In some specific embodiments of the present invention, based on the total amount of the antioxidant TMQ, the content of antioxidant TMQ is 45-65 wt%, wherein the content of the dimer of 2,2,4-trimethyl-1,2-dihydroquinoline is 25-40 wt%, and the content of isopropyl diphenylamine is 0-0.5 wt%. According to the national standard GB / T8826-2019 for TMQ, the content of antioxidant TMQ is required to be greater than 40 wt%. The antioxidant TMQ obtained by the present invention meets the requirements, and at the same time realizes the recycling of aniline, acetone and hydrochloric acid, and greatly reduces the amount of liquid alkali required for neutralization, thus realizing a green and environmentally friendly synthesis process.

[0042] In some specific embodiments of the present invention, the softening point of the antioxidant TMQ is 86-97°C.

[0043] A second aspect of the present invention provides a preparation system for the antioxidant TMQ, such as... Figure 1As shown, the system includes: a polycondensation reaction device 1 and a separation device 2 connected in sequence; a filtration device 4 and a recovery device 3 connected to the separation device 2; a neutralization device 5 connected to the filtration device 4; and a distillation device 6 connected to the neutralization device 5; wherein the filtration device 4 and the recovery device 3 are each connected to the polycondensation reaction device 1.

[0044] According to the present invention, the polycondensation reactor 1 is used for polycondensation reaction of aniline and acetone to obtain TMQ polycondensation liquid. The TMQ polycondensation liquid enters the separation device 2, which separates the components to obtain light components and heavy components. The heavy components enter the filtration device 4 to filter the obtained heavy components. The obtained filtrate is TMQ reaction liquid, which enters the neutralization device 5 for liquid alkali neutralization to obtain an oil phase, which enters the distillation device 6 for distillation to obtain the antioxidant TMQ. The filter cake obtained by the filtration device 4 is returned to the polycondensation reactor 1. The light components obtained by the separation device 2 enter the recovery device 3 to recover acetone and aniline. The recovered acetone and aniline are returned to the polycondensation reactor 1.

[0045] The present invention will be described in detail below through embodiments.

[0046] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0047] Example 1

[0048] (1) Add 620g of aniline and 48.8g of 30wt% hydrochloric acid to a 2000mL reactor equipped with a thermometer and a condenser. Stir at 110℃ for 3 hours to remove water from the hydrochloric acid. Then, under stirring at 110℃ for 5 hours, add 848g of acetone dropwise while reacting to remove the water generated in the reaction. Maintain the reaction for 0.5h after the addition is complete to obtain the TMQ polycondensation reaction solution.

[0049] (2) The obtained TMQ polycondensation reaction liquid was distilled to obtain light components (acetone 35.4%, water 26.5%, aniline 18.4%, other impurities 19.7%) and heavy components (aniline content of 5.2 wt%, the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components was controlled to be 1.06:1). The light components were separated and recovered to obtain recovered acetone (at atmospheric pressure, the fraction collected at a gas phase temperature of 0-120℃) and recovered aniline (100 Pa, the fraction collected at a gas phase temperature of 0-90℃). The heavy component contains: 16.4 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline and 44.5 wt% of TMQ, 5.2 wt% of aniline, 0.7 wt% of isopropyl diphenylamine, 6.83 wt% of aniline hydrochloride, 0.5 wt% of isopropyl diphenylamine hydrochloride, 2.5 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.1 wt% of the hexamer, and 22.17 wt% of other impurities.

[0050] (3) The obtained heavy components were filtered at 120°C through a filter with a pore size of 1 μm. The filtrate yielded a TMQ reaction solution (the TMQ reaction solution contained: 17.9 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 49.2 wt% of TMQ, 0.1 wt% of aniline, 0.1 wt% of isopropyl diphenylamine, 0.03 wt% of aniline hydrochloride, 0.01 wt% of isopropyl diphenylamine hydrochloride, 2.7 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.2 wt% of the hexamer, and 28.76 wt% of other impurities). The filter cake yielded 59.3 g of catalyst containing hydrochloric acid (of which the equivalent hydrogen chloride content was 14.35 g, the molar ratio of aniline to hydrogen chloride was 1.05:1, and the remainder was TMQ components). The obtained filter cake was returned to the polycondensation reaction in step (1).

[0051] (4) The obtained TMQ reaction solution was neutralized at 90°C with 2g of 16wt% sodium hydroxide solution, the pH value was 12, water was separated, and oil phase was distilled to obtain antioxidant TMQ.

[0052] According to the national standard test, the content of antioxidant TMQ is 58.34 wt%, of which the content of 2,2,4-trimethyl-1,2-dihydroquinoline dimer is 29.40 wt%, the content of isopropyl diphenylamine is 0.2 wt%, and the softening point is 89℃, which meets the requirements of the national standard GB / T8826-2019 for TMQ.

[0053] Example 2

[0054] (1) Add 620g of aniline and 48.8g of 30wt% hydrochloric acid to a 2000mL reactor equipped with a thermometer and a condenser. Stir at 110℃ for 3 hours to remove water from the hydrochloric acid. Then, under stirring at 110℃, add 780g of acetone dropwise over 6 hours while reacting to remove the water generated in the reaction. Maintain the reaction for 0.5h after the addition is complete to obtain the TMQ polycondensation reaction solution.

[0055] (2) The obtained TMQ polycondensation reaction solution was distilled to obtain a light component (acetone 39.5%, water 22.1%, aniline 15.2%, other impurities 23.2%) and a heavy component (aniline content 5wt%, the molar ratio of aniline to the hydrochloric acid catalyst in the heavy component is 0.95:1). The light component was further separated and recovered to obtain recovered acetone (at atmospheric pressure, collection gas phase temperature 0-120℃ fraction) and recovered aniline (100Pa, collection gas phase temperature 0- (90°C fraction). The heavy component contains: 17.7 wt% 2,2,4-trimethyl-1,2-dihydroquinoline, 46.3 wt% TMQ, 5 wt% aniline, 1.7 wt% isopropyl diphenylamine, 7.0 wt% aniline hydrochloride, 1.9 wt% isopropyl diphenylamine hydrochloride, 3.4 wt% pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.6 wt% hexamer, and 15.4 wt% other impurities.

[0056] (3) The obtained heavy components were filtered at 120°C through a filter with a pore size of 1 μm. The filtrate yielded a TMQ reaction solution (the TMQ reaction solution contained: 19.3 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 50.7 wt% of TMQ, 0.02 wt% of aniline, 1.3 wt% of isopropyl diphenylamine, 0.05 wt% of aniline hydrochloride, 0.1 wt% of isopropyl diphenylamine hydrochloride, 3.5 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.6 wt% of the hexamer, and 23.43 wt% of other impurities). The filter cake yielded 59.5 g of catalyst containing hydrochloric acid (of which the equivalent hydrogen chloride content was 14.25 g, the molar ratio of aniline to hydrogen chloride was 0.95:1, and the remainder was TMQ components). The obtained filter cake was returned to the polycondensation reaction in step (1).

[0057] (4) The obtained TMQ reaction solution was neutralized at 90°C with 3g of 16wt% sodium hydroxide solution, the pH value was 12, water was separated, and oil phase was distilled to obtain antioxidant TMQ.

[0058] According to the national standard test, the content of antioxidant TMQ is 64.25 wt%, of which the content of 2,2,4-trimethyl-1,2-dihydroquinoline dimer is 31.82 wt%, the content of isopropyl diphenylamine is 0.2 wt%, and the softening point is 86℃, which meets the requirements of the national standard GB / T8826-2019 for TMQ.

[0059] Example 3

[0060] (1) Add 620g of aniline and 48.8g of 30wt% hydrochloric acid to a 2000mL reactor equipped with a thermometer and a condenser. Stir at 110℃ for 3 hours to remove water from the hydrochloric acid. Then, under stirring at 110℃, add 1000g of acetone dropwise over 7 hours while reacting to remove the water generated in the reaction. Maintain the reaction for 0.5h after the addition is complete to obtain the TMQ polycondensation reaction solution.

[0061] (2) The obtained TMQ polycondensation reaction solution was distilled to obtain a light component (acetone 54.5%, water 18.2%, aniline 12.1%, other impurities 15.2%) and a heavy component (aniline content 6.3 wt%, the molar ratio of aniline to the hydrochloric acid catalyst in the heavy component was 1.1:1). The light component was separated and recovered to obtain recovered acetone (at atmospheric pressure, collection gas phase temperature 0-100℃) and recovered aniline (200 Pa, collection gas phase temperature 0-8℃). (8°C fraction). The heavy fraction contains: 16.6 wt% 2,2,4-trimethyl-1,2-dihydroquinoline, 44.2 wt% TMQ, 6.3 wt% aniline, 1.5 wt% isopropyl diphenylamine, 8.0 wt% aniline hydrochloride, 0.6 wt% isopropyl diphenylamine hydrochloride, 4.1 wt% pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.9 wt% hexamer, and 16.8 wt% other impurities.

[0062] (3) The obtained heavy components were filtered at 120°C through a 3 μm pore size filter to obtain a TMQ reaction solution (the TMQ reaction solution contained: 18.4 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline and 49.5 wt% of TMQ, 0.5 wt% of aniline, 1.7 wt% of isopropyl diphenylamine, 0.02 wt% of aniline hydrochloride, 0.1 wt% of isopropyl diphenylamine hydrochloride, 2.3 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.0 wt% of the hexamer, and 26.48 wt% of other impurities). The filter cake yielded 62.2 g of catalyst containing hydrochloric acid (of which the equivalent hydrogen chloride content was 14.45 g, the molar ratio of aniline to hydrogen chloride was 1.1:1, and the remainder was TMQ components). The obtained filter cake was returned to the polycondensation reaction in step (1).

[0063] (4) The obtained TMQ reaction solution was neutralized at 90°C with 2g of 16wt% sodium hydroxide solution, the pH value was 12, water was separated, and oil phase was distilled to obtain antioxidant TMQ.

[0064] According to the national standard test, the content of antioxidant TMQ is 60.73 wt%, of which the content of 2,2,4-trimethyl-1,2-dihydroquinoline dimer is 31.42 wt%, the content of isopropyl diphenylamine is 0.1 wt%, and the softening point is 97℃, which meets the requirements of the national standard GB / T8826-2019 for TMQ.

[0065] Example 4

[0066] (1) Add 620g of aniline and 48.8g of 30wt% hydrochloric acid to a 2000mL reactor equipped with a thermometer and a condenser. Stir at 110℃ for 3 hours to remove water from the hydrochloric acid. Then, under stirring at 110℃ for 5 hours, add 848g of acetone dropwise while reacting to remove the water generated in the reaction. Maintain the reaction for 0.5h after the addition is complete to obtain the TMQ polycondensation reaction solution.

[0067] (2) The obtained TMQ polycondensation reaction liquid was distilled to obtain light components (acetone 45.1%, water 24.5%, aniline 15.4%, other impurities 15%) and heavy components (aniline content 7.2wt%, the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components is 2.2:1). The light components were separated and recovered to obtain recovered acetone (at atmospheric pressure, the fraction collected at a gas phase temperature of 0-80℃) and recovered aniline (200Pa, the fraction collected at a gas phase temperature of 0-70℃). The heavy component contains: 16.1 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline and 43.7 wt% TMQ, 7.2 wt% aniline, 1.4 wt% isopropyl diphenylamine, 4.6 wt% aniline hydrochloride, 0.5 wt% isopropyl diphenylamine hydrochloride, 3.1 wt% pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.7 wt% hexamer, and 21.7 wt% other impurities.

[0068] (3) The obtained heavy components were filtered at 120°C through a 5 μm pore size filter to obtain a TMQ reaction solution (the TMQ reaction solution contained: 17.2 wt% 2,2,4-trimethyl-1,2-dihydroquinoline, 46.6 wt% TMQ, 3.6 wt% aniline, 1.1 wt% isopropyl diphenylamine, 0.5 wt% aniline hydrochloride, 0.2 wt% isopropyl diphenylamine hydrochloride, 3.3 wt% pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.8 wt% hexamer, and 63.8 wt% other impurities). 52 g of catalyst containing hydrochloric acid was obtained from the filter cake (of which the equivalent hydrogen chloride content was 12.1 g, the molar ratio of aniline to hydrogen chloride was 1.2:1, and the remainder was TMQ components). The obtained filter cake was returned to the polycondensation reaction in step (1), and 2.0 g of hydrochloric acid was added.

[0069] (4) The obtained TMQ reaction solution was neutralized at 90°C with 4g of 16wt% sodium hydroxide solution, the pH value was 13, water was separated, and oil phase was distilled to obtain antioxidant TMQ.

[0070] According to the national standard test, the content of antioxidant TMQ is 56.63 wt%, of which the content of 2,2,4-trimethyl-1,2-dihydroquinoline dimer is 30.21 wt%, the content of isopropyl diphenylamine is 0.1 wt%, and the softening point is 92℃, which meets the requirements of the national standard GB / T8826-2019 for TMQ.

[0071] Example 5

[0072] (1) Add 620g of aniline and 52.5g of 30wt% hydrochloric acid to a 2000ml reactor equipped with a thermometer and a condenser. Stir at 110℃ for 3 hours to remove water from the hydrochloric acid. Then, under stirring at 110℃ for 5 hours, add 848g of acetone dropwise while reacting to remove the water generated in the reaction. Maintain the reaction for 0.5h after the addition is complete to obtain the TMQ polycondensation reaction solution.

[0073] (2) The obtained TMQ polycondensation reaction liquid was distilled to obtain light components (acetone 51.2%, water 20.3%, aniline 11.3%, other impurities 17.2%) and heavy components (aniline content of 3.4 wt%, the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components is 0.7:1). The light components were separated and recovered to obtain recovered acetone (at atmospheric pressure, the fraction collected at a gas phase temperature of 0-100℃) and recovered aniline (80 Pa, the fraction collected at a gas phase temperature of 0-80℃). The heavy component contains: 17.9 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 42.2 wt% of TMQ, 3.4 wt% of aniline, 1.6 wt% of isopropyl diphenylamine, 4.7 wt% of aniline hydrochloride, 1.9 wt% of isopropyl diphenylamine hydrochloride, 2.4 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.1 wt% of the hexamer, and 24.8 wt% of other impurities.

[0074] (3) The obtained heavy components were filtered at 120°C through a filter with a pore size of 2 μm, and the filtrate was used to obtain TMQ reaction solution (the TMQ reaction solution contained: 19.7 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 46.5 wt% of TMQ, 0.1 wt% of aniline, 1.1 wt% of isopropyl diphenylamine, 0.1 wt% of aniline hydrochloride, 0.2 wt% of isopropyl diphenylamine hydrochloride, 2.6 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 1.2 wt% of the hexamer, and 28.5 wt% of other impurities). The filter cake yielded 53.3g of catalyst containing hydrochloric acid (of which the equivalent hydrogen chloride content was 13.55g, the molar ratio of aniline to hydrogen chloride was 0.9:1, and the remainder was TMQ component). The resulting filter cake was returned to the polycondensation reaction in step (1), and 2.0g of hydrochloric acid was added.

[0075] (4) The obtained TMQ reaction solution was neutralized at 90°C with 8g of 16wt% potassium hydroxide solution, the pH value was 13, water was separated, and oil phase was distilled to obtain antioxidant TMQ.

[0076] According to the national standard test, the content of antioxidant TMQ is 57.31 wt%, of which the content of 2,2,4-trimethyl-1,2-dihydroquinoline dimer is 28.70 wt%, the content of isopropyl diphenylamine is 0.1 wt%, and the softening point is 91℃, which meets the requirements of the national standard GB / T8826-2019 for TMQ.

[0077] Comparative Example 1

[0078] 620 g of aniline and 48.8 g of 30 wt% hydrochloric acid were added to a 2000 mL reactor equipped with a thermometer and condenser. The mixture was stirred at 120 °C for 3 hours to remove water from the hydrochloric acid. Then, under stirring at 110 °C, 848 g of acetone was added dropwise over 5 hours, removing water generated during the reaction. The mixture was maintained for 0.5 hours after the addition was complete to obtain the TMQ polycondensation reaction solution. The solution was neutralized at 90 °C with 120 g of 16 wt% sodium hydroxide solution to a pH of 11. Water was removed, and the oil phase was distilled to obtain TMQ. Testing using the national standard method showed that the product contained 29.45 wt% 2,2,4-trimethyl-1,2-dihydroquinoline dimer, 57.89 wt% TMQ, and 0.2 wt% isopropyl diphenylamine. The softening point was 89 °C, meeting the requirements of the national standard GB / T8826-2019 for TMQ.

[0079] Through the preparation methods of the antioxidant TMQ in the above embodiments and comparative examples, in Examples 1-3, the method of the present invention separates the polycondensation liquid and controls the separation conditions, retains the hydrochloric acid catalyst in the polycondensation system and causes it to precipitate, then filters and recovers it, thereby realizing the recycling of the hydrochloric acid catalyst. Compared with the traditional direct neutralization process, the use of alkali in the neutralization process is greatly reduced, using only 2-3g of 16wt% sodium hydroxide for neutralization. The amount of liquid alkali required for neutralization is reduced, and the corresponding amount of saline wastewater generated is also greatly reduced. Compared with Comparative Example 1 (using 8g of 16wt% potassium hydroxide solution for neutralization), it can reduce by 97%. More than % of saline wastewater is generated; after separation of the polycondensation liquid in Examples 4 and 5, the molar ratio of aniline to hydrochloric acid in the heavy components is controlled at 2.2:1 and 0.7:1, respectively. The separation effect of hydrochloric acid catalyst is worse than that in Examples 1-3, and the amount of neutralizing alkali solution used is increased, using 4-8g of 16wt% sodium hydroxide for neutralization; without separation of the light and heavy components of the polycondensation liquid and without controlling the molar ratio of aniline to hydrochloric acid catalyst in the heavy components (Comparative Example 1), a large amount of alkali is required to neutralize the hydrochloric acid in the polycondensation reaction process, using 120g of 16wt% sodium hydroxide for neutralization, and a large amount of saline wastewater is generated at the same time.

[0080] Meanwhile, the method of the present invention separates the polycondensation liquid and controls the separation conditions, retaining the hydrochloric acid catalyst in the polycondensation system and causing it to precipitate, then filtering and recovering it, thereby realizing the recycling of the hydrochloric acid catalyst. In Examples 1-3, the hydrogen chloride content in the filter cake reached 14.25-14.45g, while the addition of 48.8g of 30wt% hydrochloric acid resulted in 14.64g, basically achieving a recycling rate of 97.3-98.7% for the hydrochloric acid. Examples 4-5 achieved a recycling rate of 82.7-86% for the hydrochloric acid, while the comparative examples did not achieve hydrochloric acid recycling. The present invention realizes a green and environmentally friendly synthesis process.

[0081] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for producing an antioxidant TMQ, characterized by, The method includes: (1) In the presence of hydrochloric acid catalyst, aniline and acetone were subjected to polycondensation reaction to obtain TMQ polycondensation solution; (2) The obtained TMQ condensation liquid is separated to obtain light components and heavy components respectively, while controlling the molar ratio of aniline to the hydrochloric acid catalyst in the heavy components; (3) The obtained heavy components are filtered, and the filtrate is the TMQ reaction solution. The filter cake is returned to the polycondensation reaction in step (1). (4) The obtained TMQ reaction solution was neutralized by adding liquid alkali, and the resulting oil phase was distilled to obtain the antioxidant TMQ; In step (2), the molar ratio of aniline to hydrochloric acid catalyst in the heavy component is 0.3-2:1; In step (3), the filtration temperature is 80-150℃; In step (2), the light component contains 10-40 wt% acetone, 10-40 wt% water, 5-20 wt% aniline, and 0-30 wt% other impurities; In step (2), the heavy component contains 5-20 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 20-60 wt% of TMQ, 0.5-10 wt% of aniline, 0.5-2 wt% of isopropyl diphenylamine, 1-10 wt% of aniline hydrochloride, 0.5-2 wt% of isopropyl diphenylamine hydrochloride, 0.5-5 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 0.1-2 wt% of the hexamer, and 0-30 wt% of other impurities; In step (3), the TMQ reaction solution contains: 5-25 wt% of 2,2,4-trimethyl-1,2-dihydroquinoline, 20-65 wt% of TMQ, 0.01-15 wt% of aniline, 0.01-2.5 wt% of isopropyl diphenylamine, 0.01-2 wt% of aniline hydrochloride, 0-0.5 wt% of isopropyl diphenylamine hydrochloride, 0.5-8 wt% of the pentamer of 2,2,4-trimethyl-1,2-dihydroquinoline, 0.1-4 wt% of the hexamer, and 0-30 wt% of other impurities; Based on the total amount of the antioxidant TMQ, the content of TMQ in the antioxidant TMQ is 45-65 wt%, of which the content of the dimer of 2,2,4-trimethyl-1,2-dihydroquinoline is 25-40 wt%, and the content of isopropyl diphenylamine is 0-0.5 wt%.

2. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of aniline, acetone and hydrochloric acid catalyst is 1:1.5-10:0.05-0.

5.

3. The preparation method according to claim 1, characterized in that, In step (1), the polycondensation reaction takes 0.001-10 hours and the polycondensation reaction takes 90-200°C.

4. The preparation method according to any one of claims 1-3, characterized in that, In step (2), the separation is selected from distillation, rectification or fractional distillation.

5. The preparation method according to claim 1, characterized in that, The separation and purification of the light components includes: first, controlling the separation conditions to be at atmospheric pressure and the gas phase temperature to be 0-120℃, and separating and recovering acetone; then controlling the separation conditions to be at atmospheric pressure or reduced pressure, and separating and recovering aniline, wherein, under atmospheric pressure conditions, the gas phase temperature is 121-220℃, and under reduced pressure conditions of 1-200Pa, the gas phase temperature is 0-90℃.

6. The preparation method according to claim 5, characterized in that, The light components, after being separated and refined, are returned as recycled raw materials to the polycondensation reaction in step (1).

7. The preparation method according to any one of claims 1-3, characterized in that, In step (2), the molar ratio of aniline to hydrochloric acid catalyst in the heavy component is 0.9-1.1:

1.

8. The preparation method according to any one of claims 1-3, characterized in that, In step (3), the separation and purification of the heavy components includes: the separation conditions are atmospheric pressure or reduced pressure; wherein, under atmospheric pressure, the gas phase temperature is 0-220℃, and the heavy components are separated; under reduced pressure conditions of 1-500Pa, the gas phase temperature is 0-90℃, and the heavy components are separated.

9. The preparation method according to claim 1, characterized in that, In step (4), the liquid alkali is selected from at least one of sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

10. The preparation method according to claim 9, characterized in that, In step (4), the pH of the product obtained by neutralization is 8-12.

11. The preparation method according to any one of claims 1-3, characterized in that, In step (4), the weight ratio of the liquid alkali to the TMQ reaction solution is 0.0001-0.001:

1.

12. The preparation method according to claim 1, characterized in that, The softening point of the antioxidant TMQ is 86-97℃.

13. The preparation method according to any one of claims 1-3, characterized in that, The method is carried out in a preparation system for antioxidant TMQ, which includes: a polycondensation reaction device and a separation device connected in sequence; a filtration device and a recovery device connected to the separation device; a neutralization device connected to the filtration device; and a distillation device connected to the neutralization device; wherein the filtration device and the recovery device are each connected to the polycondensation reaction device.

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