Microwave continuous reaction device

Abstract

The utility model discloses a microwave continuous reaction device, and belongs to the technical field of 2, 3, 5-trimethylhydroquinone diester synthesis equipment.The microwave continuous reaction device comprises a reactor, a feeding and discharging mechanism and a temperature control mechanism are arranged on the reactor, and the reactor comprises a microwave assembly; the microwave electric field can activate chemical reagent performance, increase molecular activity and improve energy efficiency; compared with a traditional kettle type reactor, the microwave reactor is beneficial to rapidly and uniformly heating organic matters, so that the reaction can be rapidly carried out at a lower temperature, the acidity requirement is reduced, and the equipment investment and energy consumption are greatly reduced; the device can inhibit the generation of by-products while achieving high conversion rate of the reaction, improves the reaction selectivity and the product yield, shortens the reaction time, and is beneficial to large-scale application.

Description

Technical Field

[0001] This application belongs to the technical field of 2,3,5-trimethylhydroquinone diester synthesis equipment, and in particular relates to a microwave continuous reaction device. Background Technology

[0002] 2,3,5-Trimethylhydroquinone diester (TMHQ DA) is an important raw material for the synthesis of vitamin E and vitamin E esters. Vitamin E is an essential nutrient for the human body and plays an important role in improving immunity and delaying aging. The artificial synthesis of vitamin E has always been an important field of chemical research and production. Therefore, the high-selectivity and high-yield synthesis of TMHQ DA is of great significance.

[0003] Currently, there are many methods for synthesizing 2,3,5-trimethylhydroquinone diester. Through research and production practice, the synthesis of TMHQ DA by isophorone oxidation, namely 2,6,6-trimethylcyclohexyl-2-ene-1,4-dione (oxoisophorone, KIP), and acylating agent in the presence of a protic acid in a catalytic amount, has made great progress.

[0004] CN101607896A reports the use of acidic ionic liquids as catalysts to catalyze the reaction of KIP with acid anhydrides to prepare 2,3,5-trimethylhydroquinone diester. However, the conversion rate is only 38%, the selectivity is 93%, and the single-pass yield is low. This invention suffers from high solvent consumption, expensive ionic liquids, high temperatures, and numerous side reactions. The compound cannot be easily separated and purified, making industrial production difficult. Patent CN115260029A utilizes a bubble column reactor to produce 2,3,5-trimethylhydroquinone diester. It employs the gradient distribution of the solid acid catalyst content and pressure on the sieve plate to regulate the temperature gradient within the column, creating an "inverse" distribution with the feed concentration gradient on the sieve plate. This suppresses side reactions such as 2,4,5-trimethylhydroquinone diester and 3,4,5-trimethylhydroquinone diester. Product formation: This method involves high temperatures, making it difficult to accurately control the temperature of the reactor's outer jacket and cooling coils in large-scale industrial production, thus hindering precise control of the reactor's internal temperature and timely removal of reaction heat. Patent CN108047042A utilizes hypergravity technology to enhance mass transfer efficiency, thereby reducing the formation of the byproduct 3,4,5-trimethylhydroquinone diester to obtain high-purity 2,3,5-trimethylhydroquinone diester. This method further improves the yield of KIP by reacting the reaction liquid. However, the unreacted KIP remaining from the first step is difficult to react in the second step (except in internal circulation hypergravity reactors) to form 2,3,5-trimethylhydroquinone diester. Hypergravity environments can easily cause wear and tear on solid catalysts, resulting in catalyst loss and reduced catalytic efficiency.

[0005] The above-mentioned isophorone oxidation method for synthesizing vitamin E acetate has the following shortcomings: the reaction temperature for synthesizing 2,3,5-trimethylhydroquinone diester using isophorone oxidation is generally between 40-130℃; the amount of the byproduct 3,4,5-trimethylhydroquinone diester varies depending on the type and amount of catalyst and reaction conditions; high temperatures can shift the reaction towards the formation of the byproduct 3,4,5-trimethylhydroquinone diester, resulting in low purity of the main product, poor reaction selectivity, and low product yield; low temperatures significantly reduce side reactions, but the reaction time... Furthermore, the production process is relatively long, with a long production cycle and high costs. The byproduct 3,4,5-trimethylhydroquinone diester is similar in properties to the main product as an isomer, making post-processing of the product difficult and hindering the effective production of high-purity 2,3,5-trimethylhydroquinone diester, thus increasing post-processing costs. While the selectivity of the reaction can be controlled by screening and modifying the catalyst system and by applying chemical process intensification technology to change the mass and heat transfer of the reaction, these methods are often accompanied by catalyst loss and failure, and the operating conditions are difficult to achieve industrially. Summary of the Invention

[0006] The purpose of this application is to provide a microwave continuous reaction apparatus to solve the technical problems of low selectivity, low yield, low purity, and complex post-processing in existing methods for synthesizing 2,3,5-trimethylhydroquinone diester.

[0007] To achieve the above objectives, the technical solution adopted in this application is: a microwave continuous reaction device, including a reactor, wherein the reactor is provided with a feeding and discharging mechanism and a temperature control mechanism, and the reactor includes a microwave component.

[0008] In one embodiment,

[0009] The reactor also includes a metal shell, in the middle of which is a swirling tubular reactor.

[0010] In one embodiment,

[0011] The microwave component includes a microwave radiator, one end of which is equipped with a microwave generator, and the microwave radiator is inserted into the bottom of the metal casing.

[0012] In one embodiment,

[0013] The feeding and discharging mechanism includes a static mixer and a gyratory tubular preheater arranged in parallel with the gyratory tubular reactor.

[0014] In one embodiment,

[0015] One end of both the cyclone tubular reactor and the cyclone tubular preheater passes through the metal shell and is connected to the static mixer, while the other end of the static mixer is connected to the first feed pipe.

[0016] In one embodiment,

[0017] The other end of the gyratory tubular reactor is connected to a discharge pipe, and the other end of the gyratory tubular preheater is connected to a second feed pipe.

[0018] In one embodiment,

[0019] Both the second feed pipe and the discharge pipe pass through the metal casing.

[0020] In one embodiment,

[0021] The first feed pipe, the second feed pipe, and the discharge pipe are all equipped with flow control valves.

[0022] In one embodiment,

[0023] The temperature control mechanism includes a temperature control tube that is connected to both sides of the metal casing. The temperature control tube is equipped with a temperature control system, and the temperature control tube and the metal casing are equipped with a wave-absorbing medium.

[0024] This application provides a microwave continuous reaction apparatus. The microwave reactor controls the reaction temperature at 50°C for the synthesis of 2,3,5-trimethylhydroquinone diester via isophorone oxidation. Utilizing the advantages of a microchannel reaction and the strong penetrating power and uniform radiation of a U-shaped microwave radiator, this apparatus avoids the reaction from shifting towards the formation of the byproduct 3,4,5-trimethylhydroquinone diester due to high temperatures, thus reducing side reactions. The microwave electric field activates molecular activity, ensuring the reaction proceeds rapidly at low temperatures until completion, eliminating any "tailing" of the reaction rate. This guarantees high conversion rates while particularly suppressing the formation of byproducts such as 3,4,5-trimethylhydroquinone diester, improving reaction selectivity. Simultaneously, it reduces the amount of acidic catalyst required and the acidity requirement, significantly reducing equipment investment and energy consumption. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of this device.

[0027] Explanation of symbols in the diagram:

[0028] 1. Metal shell; 2. Rotary tubular reactor; 3. Rotary tubular preheater; 4. Microwave radiator; 5. Microwave generator; 6. Static mixer; 7. Flow control valve; 8. First feed pipe; 9. Second feed pipe; 10. Discharge pipe; 11. Temperature control system; 12. Microwave absorbing medium; 13. Temperature control tube. Detailed Implementation

[0029] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0030] In one embodiment, a microwave continuous reaction apparatus includes a reactor, which is equipped with a feeding / discharging mechanism and a temperature control mechanism. The reactor includes a microwave component. Figure 1 As shown, the reactor also includes a metal shell 1, with a gyratory tubular reactor 2 located in the middle of the metal shell 1; the microwave assembly includes a microwave radiator 4, which is U-shaped; a microwave generator 5 is located at one end of the microwave radiator 4, which is inserted into the bottom of the metal shell 2; the feeding and discharging mechanism includes a static mixer 6, and also includes a gyratory tubular preheater 3 arranged parallel to the gyratory tubular reactor 2, with one end of both the gyratory tubular reactor 2 and the gyratory tubular preheater 3 passing through the metal shell 1 and communicating with the static mixer 6. The other end of the static mixer 6 is connected to the first feed pipe 8, the other end of the cyclone tubular reactor 2 is connected to the discharge pipe 10, and the other end of the cyclone tubular preheater 3 is connected to the second feed pipe 9. The second feed pipe 9 and the discharge pipe 10 both pass through the metal shell 1. The first feed pipe 8, the second feed pipe 9 and the discharge pipe 10 are all equipped with flow control valves 7. The temperature control mechanism includes a temperature control pipe 13 connected to both sides of the metal shell 1. The temperature control pipe 13 is equipped with a temperature control system 11. The temperature control pipe 13 and the metal shell 1 are equipped with a wave-absorbing medium 12.

[0031] Specifically, the reactor provides the site for the microwave reaction, the feeding and discharging mechanism handles feeding and discharging, and the temperature control mechanism controls the temperature inside the reactor. A metal casing 1 encloses the gyratory tubular reactor 2 and the microwave radiator 4, allowing the reaction to occur simultaneously within a closed space while a microwave electric field is generated. The gyratory tubular reactor 2 and the gyratory tubular preheater 3 are suspended inside the metal casing 1, above the microwave radiator 4. Both the gyratory tubular reactor 2 and the gyratory tubular preheater 3 are made of non-absorbing materials. The microwave generator 5 transmits the generated microwaves to the microwave radiator. Device 4; the first feed pipe 8 and the second feed pipe 9 are used for feeding materials, the discharge pipe 10 is used for collecting the system after the reaction, the flow control valve 7 is used for opening and closing the pipeline; the static mixer 6 is used for mixing the substances delivered from each pipeline; the temperature control system 11 is used to control the specific temperature required for the reaction, and the two ends of the temperature control pipe 13 are respectively connected to both sides of the metal shell 1 to form a loop. The temperature control pipe 13 is used to circulate and transport the microwave absorbing medium 12. The microwave absorbing medium 12 is used to absorb the microwave energy generated by the microwave radiator 4, and the temperature inside the metal shell 1 is controlled by the microwave absorbing medium 12.

[0032] The above details the specific structure of this device; the following, in conjunction with... Figure 1 The working principle of the aforementioned microwave continuous reaction device is described below:

[0033] The raw materials and catalyst used in the reaction enter the static mixer 6 through the first feed pipe 8. The acylating agent needs to be heated in the gyroscopic tubular preheater 3 through the second feed pipe 9 before entering the static mixer 6. The raw materials, catalyst and acylating agent are fully mixed in the static mixer 6 and then enter the gyroscopic tubular reactor 2. The microwave generator 5 and the temperature control system 11 are turned on. The material in the gyroscopic tubular reactor 2 is irradiated by the microwave radiator 4, so that the material receives microwave radiation to catalyze the reaction during the flow process. The temperature control pipe 13, together with the temperature control system 11, helps to maintain the reaction temperature in the metal shell 1. The reaction liquid of the system that has passed through the gyroscopic tubular reactor 2 is discharged from the discharge pipe 10.

[0034] A microwave continuous reaction apparatus is used. By applying a microwave electric field to the organic synthesis raw materials, the synthesis reaction is carried out at a set temperature and a set residence time. After the reaction product enters the next process stage for separation and purification, the acylating agent and light acid components in the reaction mixture are recovered by vacuum distillation. The crude oil is crystallized and washed to separate the target product from the remaining small amount of hydroquinone diester derivative, so as to obtain a relatively pure 2,3,5-trimethylhydroquinone diester product.

[0035] This application provides a microwave continuous reaction device, including a reactor equipped with an inlet / outlet mechanism and a temperature control mechanism. The reactor includes a microwave component; the microwave electric field generated by the microwave component can activate the properties of chemical reagents, increase molecular activity, and improve energy efficiency. Compared with traditional batch reactors, microwave reactors are advantageous for rapid and uniform heating of organic matter. The use of suspended, swirling reaction microchannels and U-shaped microwave radiators avoids penetration depth limitations and wall adhesion phenomena. The gaps between reaction tubes facilitate microwave resonance and penetration through the tube walls to reach the reaction medium. The swirling, suspended arrangement and U-shaped microwave radiators enhance the uniformity of the microwave electric field, i.e., uniform heating. Uniformity effectively avoids localized "hot spots" and "cold spots" during material heating, enabling the reaction to proceed rapidly at lower temperatures. This prevents the reaction from being deflected towards the formation of byproducts due to high temperatures, and reduces the amount of acidic catalyst and acid requirements, significantly lowering equipment investment and energy consumption. The microwave-absorbing medium removes reaction heat promptly through external circulation, better controlling the reaction temperature and shortening solvent preheating time. While achieving high conversion rates, this device can suppress the formation of byproducts such as 3,4,5-trimethylhydroquinone diester, improving reaction selectivity and product yield, shortening reaction time, and reducing post-processing costs, which is beneficial for large-scale applications.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0037] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A microwave continuous reaction apparatus, characterized in that, The reactor includes a feed and discharge mechanism and a temperature control mechanism, and a microwave component. The reactor also includes a metal shell, in which a vortex tubular reactor is located. The microwave component includes a microwave radiator, one end of which is equipped with a microwave generator. The microwave radiator is inserted into the bottom of the metal casing and is U-shaped. The feeding and discharging mechanism includes a static mixer and a gyratory tubular preheater arranged in parallel with the gyratory tubular reactor. The temperature control mechanism includes a temperature control tube that communicates with both sides of the metal casing. The temperature control tube is equipped with a temperature control system, and the temperature control tube and the metal casing are equipped with a wave-absorbing medium.

2. The microwave continuous reaction apparatus according to claim 1, characterized in that, One end of both the cyclone tubular reactor and the cyclone tubular preheater passes through the metal shell and is connected to the static mixer, while the other end of the static mixer is connected to the first feed pipe.

3. The microwave continuous reaction apparatus according to claim 2, characterized in that, The other end of the gyratory tubular reactor is connected to a discharge pipe, and the other end of the gyratory tubular preheater is connected to a second feed pipe.

4. A microwave continuous reaction apparatus according to claim 3, characterized in that, Both the second feed pipe and the discharge pipe pass through the metal casing.

5. A microwave continuous reaction apparatus according to claim 3, characterized in that, The first feed pipe, the second feed pipe, and the discharge pipe are all equipped with flow control valves.

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