Reaction system and reaction method

Abstract

The present application relates to the chemical industry field, disclose a kind of reaction system and reaction method, reaction system includes the reaction kettle, rectifying column, cooler, liquid separator tank and product tank connected in sequence, reaction kettle includes closed kettle body, kettle body has reaction zone, the blocking plate is arranged in the kettle body of upper portion of this reaction zone, the gas hole for gas passing is opened in the blocking plate, product tank is installed with local liquid level display meter, the reaction kettle in the reaction system provided by the present application is closed kettle body, it is favorable to improve the security of reaction, and kettle body is equipped with blocking plate, when reaction raw material sublimes, it is condensed into snowflake when ascending to kettle upper portion region, the raw material condensed after sublimation can be blocked by blocking plate, avoid its plugging kettle top pipeline, simultaneously gas phase can be exported in time by rectifying column, cooler, liquid separator tank and stored in product tank, by real-time acquisition the amount of liquid phase product in product tank, conversion rate can be calculated and obtained.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically to a reaction system and reaction method. Background Technology

[0002] Reactors are commonly used reactors in the chemical industry, used for various processes such as stirring, mixing, and reaction. In the production of chemical products, reactors are used to control parameters such as reaction time, temperature, and pressure, as well as to mix reactants and promote the reaction process. They can also be used to dissolve solid reactants, increasing the reaction rate. Reactors can be used for various types of reactions, including the synthesis of organic compounds, catalytic reactions, and polymerization reactions, and are widely used in petrochemical, pharmaceutical, metallurgical, food processing, and environmental protection industries. In the lubricating oil field, reactors are used in the synthesis of ester oils, the formulation of lubricating greases, and the reaction synthesis of various additives.

[0003] However, due to the special properties of the raw materials in some chemical products, there is a phenomenon of sublimation of the raw materials during the reaction process. The sublimated raw materials condense and crystallize at the top of the reactor, blocking the pipeline. In addition, the reaction products are volatile and toxic gas phases. Using traditional atmospheric pressure reactors will result in many production safety hazards such as dust pollution in chemical production workshops and the emission of toxic and harmful gases.

[0004] Currently, existing technologies have developed various types of reactors with different structures to meet the requirements of high-efficiency reactions, targeting different reaction characteristics. CN218189561U discloses a reactor for producing lubricating oil additives, and CN217031903U discloses a reactor condensation reflux device, but neither of them is suitable for reactions involving the sublimation of raw materials and gaseous products. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of pipeline blockage and the presence of toxic substances in the gas phase caused by the sublimation of raw materials and the gas phase reaction of products in the existing technology. This invention provides a reaction system and reaction method in which the reaction vessel is a closed vessel with a baffle plate inside to block the raw materials after sublimation and condensation, thus preventing the top of the vessel from blocking the pipeline. At the same time, the produced gas phase can be processed in a timely manner to obtain the liquid product. The conversion rate can be obtained by measuring the amount of liquid product in real time.

[0006] To achieve the above objectives, a first aspect of the present invention provides a reaction system comprising a reaction vessel, a distillation column, a cooler, a separator, and a product tank connected in sequence;

[0007] The reactor includes a closed vessel body with a reaction zone inside. A baffle plate is installed in the upper part of the vessel body above the reaction zone. The baffle plate has vent holes for gas to pass through. A local liquid level indicator is installed on the product tank.

[0008] Using the above technical solution, the reaction vessel in this system is a closed vessel, which helps improve the safety of the reaction. A baffle plate is installed inside the vessel; when the reactants sublimate and rise to the upper part of the vessel, they condense into snowflake-like shapes. The baffle plate prevents the condensed reactants from clogging the pipes at the top of the vessel. Simultaneously, the produced gaseous phase can be promptly stored in a product tank via a distillation column, cooler, and separator. By real-time monitoring of the liquid product in the product tank, the conversion rate can be calculated. Furthermore, the very small amount of sublimated reactants present in the gaseous product is removed in the distillation column, ensuring that the final discharged gas is environmentally friendly and safe. The reaction system provided by this invention is highly suitable for reactions involving reactants with sublimation properties and producing gaseous products.

[0009] A second aspect of the present invention provides a reaction method based on the reaction system provided in the first aspect of the present invention, wherein reactants are fed into a reaction vessel for reaction, the gaseous phase to be treated generated by the reaction is introduced into the bottom of a distillation column, and a liquid phase is introduced at the top of the column. The gaseous product gas at the top of the distillation column is cooled by a cooler and separated by a separator before entering a product tank to obtain a liquid product. The amount of the liquid product in the product tank is read by a local level gauge, and the conversion rate is obtained based on the amount of the liquid product. The conversion rate is calculated as follows:

[0010] Conversion rate = Actual amount of liquid product in the product tank / Theoretical amount of liquid product × 100%.

[0011] A closed reactor refers to a reactor that remains sealed during the reaction. The reactor in this system is a sealed vessel, which improves reaction safety. A baffle plate inside the reactor prevents the condensed raw materials after sublimation from clogging the pipes. It also reduces problems such as low reaction yield and dust pollution caused by excessive sublimation of raw materials. Furthermore, the produced gaseous phase can be promptly stored in a product tank via a distillation column, cooler, and separator. The conversion rate can be calculated by real-time monitoring of the liquid product in the product tank.

[0012] The reaction method provided by this invention is very suitable for reactions in which the raw materials have sublimation properties and produce gaseous products, and the conversion rate of each batch of products can be monitored in real time. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the reaction system;

[0014] Figure 2This is a schematic diagram of the reactor structure.

[0015] Explanation of reference numerals in the attached figures

[0016] 1-Reaction vessel; 101-Vessel body; 102-Reaction zone; 103-Baffle plate; 104-Storage tank; 105-Spray pipe; 106-Agitator; 107-Pressure gauge; 108-Balance pipe; 2-Distillation column; 2a-Distillation column gas inlet; 2b-Distillation column liquid inlet; 3-Cooler; 4-Separating tank; 5-Product tank; 6-Local level indicator; 7-Vacuum buffer tank; 8-Vacuum pump; 9-Gas washing bottle; 10-Tail gas gauge. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0018] In the description of this application, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0020] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0021] The first aspect of the present invention provides a reaction system comprising a reaction vessel, a distillation column, a cooler, a separator, and a product tank connected in sequence;

[0022] The reactor includes a closed vessel body with a reaction zone inside. A baffle plate is installed in the upper part of the vessel body above the reaction zone. The baffle plate has vent holes for gas to pass through. A local liquid level indicator is installed on the product tank.

[0023] The sealed reactor body enhances reaction safety. For reactions involving raw material sublimation and gaseous products, the baffle plate prevents the condensed raw material from clogging the pipes. Simultaneously, the produced gaseous phase is promptly stored in the product tank via a distillation column, cooler, and separator. By monitoring the amount of liquid product in the product tank in real time, the conversion rate can be calculated. Furthermore, the very small amount of sublimated raw material present in the gaseous product is removed in the distillation column and discharged from the bottom of the reactor into other processing units, ensuring the final discharged gas is environmentally friendly and safe. The reaction system provided by this invention is highly suitable for reactions involving raw materials with sublimation properties and producing gaseous products.

[0024] In some embodiments, preferably, the reactor is connected to a material flushing structure, the inlet of which is connected to the cooler, and the outlet of which is located inside the reactor above the baffle plate. With this design, when a large amount of raw material condenses on the baffle plate, the material flushing structure can flush the raw material back into the reaction zone, which helps improve the utilization rate of raw materials and increase yield.

[0025] In some embodiments, preferably, the material flushing structure includes a storage tank, the inlet of which is connected to the liquid product outlet of the cooler, and the outlet of the storage tank is connected to a spray pipe for spraying the baffle plate. A portion of the liquid product cooled by the cooler can be returned to the reactor to flush away condensed raw materials. The outlet of the spray pipe can also be fitted with a spray head to facilitate more uniform liquid spraying.

[0026] The reactor can also be connected to a pressure gauge for easy pressure control. A level gauge can be installed on the storage tank to facilitate real-time monitoring of the liquid volume. The storage tank and the reactor can also be balanced by a balancing pipe.

[0027] In some embodiments, preferably, the reaction system further includes a vacuum buffer tank connected to the separatory tank, and the vacuum buffer tank is connected to a vacuum pump. With this structure, when the distillation column operates under negative pressure, the non-condensable tail gas can be extracted by the vacuum pump. Combined with the vacuum buffer tank, a pressure gradient can be formed, causing the non-condensable tail gas to condense into a liquid product as it flows along the pressure gradient and enter the separatory tank.

[0028] In some embodiments, preferably, the reaction system further includes a gas washing bottle and a tail gas meter, with the separating tank connected in sequence to the gas washing bottle and the tail gas meter. With this structure, when the distillation column operates under positive pressure, the non-condensable gases mixed in the separating tank are discharged after passing through the gas washing bottle and the tail gas meter, or enter other processing steps. The tail gas meter facilitates the acquisition of the discharged tail gas volume.

[0029] In some embodiments, preferably, the reaction vessel is equipped with a stirrer, and the baffle plate is mounted on the rotating shaft of the stirrer. The baffle plate is a 40-60 mesh porous plate, and the holes on it form the vent holes. The stirrer is located below the baffle plate, and the rotation speed of the stirrer during the reaction is generally 20-100 r / min.

[0030] In some embodiments, preferably, the baffle plate is generally installed at one-third of the depth inside the reactor. The reaction zone typically occupies about 80% of the reactor volume, and installing the baffle plate at one-third of the depth helps to prevent the raw materials from condensing after sublimation.

[0031] In some embodiments, preferably, the reactor further includes a shell fitted over the reactor body, with a heat-conducting space formed between the shell and the reactor body. This heat-conducting space is used to fill a heat-conducting medium. The heat-conducting space is generally connected to a feeding pipe, and the heat-conducting medium is typically heat-conducting oil. A heating coil may also be installed inside the space to facilitate control of the reaction temperature within the reactor.

[0032] A material handling pipe can also be connected to the bottom of the reactor for easy material handling.

[0033] A second aspect of the present invention provides a reaction method based on the reaction system provided in the first aspect of the present invention, wherein reactants are fed into a reaction vessel for reaction, the gaseous phase to be treated generated by the reaction is introduced into the bottom of a distillation column, and a liquid phase is introduced at the top of the column. The gaseous product gas at the top of the distillation column is cooled by a cooler and separated by a separator before entering a product tank to obtain a liquid product. The amount of the liquid product in the product tank is read by a local level gauge, and the conversion rate is obtained based on the amount of the liquid product. The conversion rate is calculated as follows:

[0034] Conversion rate = Actual amount of liquid product in the product tank / Theoretical amount of liquid product × 100%.

[0035] In some implementations, preferably, the reaction is considered complete when the conversion rate is not less than 95%. When the conversion rate is ≥95% or 97%, the reaction is considered relatively complete.

[0036] In some embodiments, preferably, the reaction raw materials include dimethyl terephthalate and octadecylamine, which are added to the reaction vessel in a molar ratio of 1:4-6 for an aminolysis reaction to obtain octadecylamide and methanol. During the reaction, dimethyl terephthalate has a melting point of 140°C and is prone to sublimation, producing flocculent matter. The reaction between dimethyl terephthalate and octadecylamine generates gaseous methanol. The obtained octadecylamide is an important intermediate in the synthesis of amide thickeners.

[0037] In some embodiments, preferably, the reaction pressure of the reactor is 0.4-0.6 MPa, and the reaction temperature is 100-200°C. The reaction pressure of the reactor can be any value between any two of 0.4 MPa, 0.5 MPa, and 0.6 MPa, and the reaction temperature can be any value between any two of 100°C, 120°C, 150°C, 180°C, and 200°C.

[0038] In some embodiments, preferably, the temperature of the distillation column is 100-130°C. The operating temperature of the distillation column can be any value between any two of 100°C, 110°C, 120°C, and 130°C.

[0039] In some embodiments, preferably, the pressure of the distillation column is 0-0.3 MPa. The operating pressure of the distillation column can be any value between any two of 0 MPa, 0.1 MPa, 0.2 MPa, and 0.3 MPa.

[0040] In some embodiments, preferably, the pressure of the distillation column is between -0.05 MPa and -0.15 MPa. The operating pressure of the distillation column can be any value between any two of -0.05 MPa, -0.1 MPa, -0.12 MPa, and -0.15 MPa.

[0041] In some embodiments, preferably, the liquid phase introduced at the top of the distillation column can be water, typically at 25°C. The pipeline connecting the reactor and the distillation column can be covered with an insulation layer to maintain the temperature of the gaseous product at approximately 230°C. The gaseous product generally also contains trace amounts of raw materials. The distillation column allows these trace amounts of raw materials to enter the liquid phase for subsequent processing, or, if necessary, return them to the reactor. The gas-liquid volume ratio of the gaseous product entering the distillation column from the reactor to the liquid phase is 1.25-1.5:1. The pressure drop inside the distillation column is controlled to not exceed 5-10 kPa.

[0042] The cooler uses water cooling, and the temperature of the liquid product obtained after cooling is 30-50℃.

[0043] The present invention will be further illustrated below through examples and comparative examples.

[0044] The following embodiments are all based on the reaction system described below, and the specific structure of the reaction system is as follows:

[0045] like Figure 1 and 2 As shown, the reaction system includes a reaction vessel 1, a distillation column 2, a cooler 3, a separator 4, and a product tank 5 connected in sequence.

[0046] The reactor 1 includes a closed reactor body 101, which has a reaction zone 102. A baffle plate 103 is provided in the reactor body 101 above the reaction zone 102. The baffle plate 103 has vent holes for gas to pass through. A local liquid level indicator 6 is installed on the product tank 5.

[0047] The reactor 1 is equipped with a stirrer 106, and a baffle plate 103 is installed on the rotating shaft of the stirrer 106. As the shaft rotates, the raw materials and gases that sublimate during the reaction are mainly concentrated in the vicinity of the rotating shaft. Therefore, installing the baffle plate 103 on the rotating shaft is beneficial to improving the interception efficiency. The baffle plate 103 is a 40-60 mesh stainless steel porous plate, and the holes on it form the gas pores. There is a certain gap between the edge of the baffle plate 103 and the inner wall of the reactor body 101 to facilitate rotation. From the top of the reactor to the bottom, the baffle plate 103 is usually installed at 1 / 3 of the height of the reactor body 101. The reactor body 101 is also connected to a pressure gauge 107, and a material sampling pipe is also connected to its bottom.

[0048] The reactor 1 is connected to a material flushing structure. The inlet of the material flushing structure is connected to the cooler 3, and the outlet of the material flushing structure is located inside the reactor above the baffle plate 103.

[0049] Specifically, the material flushing structure includes a storage tank 104, the inlet of which is connected to the liquid product outlet of the cooler 3. A spray pipe 105 is connected to the outlet of the storage tank 104 for spraying the baffle plate 103. A spray head is installed at the outlet of the spray pipe 105. The storage tank 104 is also connected to a level gauge. The top of the storage tank 104 is connected to the top of the vessel body 101 via a balance pipe 108 to balance the air pressure between them, facilitating liquid spraying. A control valve can be installed on the spray pipe 105 to control the spraying time.

[0050] The reactor 1 also includes a shell 109 sleeved outside the reactor body 101. A heat-conducting space 110 is formed between the shell 109 and the reactor body 101. The heat-conducting space 110 is connected to a feeding pipe for easy filling of heat-conducting medium, and a heating coil is also provided inside it. The heat-conducting space 110 is used for filling heat-conducting medium.

[0051] from Figure 1 It can also be seen that the gas phase outlet at the top of the vessel body 101 is connected to the distillation column inlet 2a at the bottom of the distillation column 2, and the pipeline connecting the two is covered with a heat insulation layer. The top of the distillation column 2 has a distillation column liquid inlet 2b, and the column is filled with metal stainless steel packing, specifically triangular spiral packing. The top of the distillation column 2 is connected to the top of the cooler 3, and the liquid phase product outlet at the bottom of the cooler 3 is connected to the separator 4 and the liquid inlet of the material flushing structure through pipelines.

[0052] In some embodiments, the reaction system further includes a vacuum buffer tank 7, which is connected to the top of the separatory tank 4 via a pipe. The vacuum buffer tank 7 is connected to a vacuum pump 8, which is activated when the operating pressure of the distillation column 2 is negative.

[0053] In some embodiments, the reaction system further includes a gas washing bottle 9 and a tail gas meter 10, with the gas washing bottle 9 and the tail gas meter 10 connected sequentially to the top of the separator 4. This structure is activated when the operating pressure of the distillation column 2 is positive.

[0054] Taking a 50-mesh screen as an example, the specific implementation process is as follows.

[0055] Example 1

[0056] Dimethyl terephthalate and octadecylamine were subjected to an aminolysis reaction in the reactor 1 at a molar ratio of 1:4.5 to obtain octadecylamine and methanol. The reaction temperature was controlled at 150°C and the reaction pressure was controlled at 0.5 MPa by adding heat transfer oil into the heat transfer space 110 and using heating coils.

[0057] As the reaction proceeds, some of the raw material, dimethyl terephthalate, undergoes a sublimation reaction. As the product gaseous methanol rises, most of the dimethyl terephthalate condenses into snowflake-like solids after reaching a certain level and is blocked by the baffle plate 103. A very small amount of dimethyl terephthalate remains in the gaseous phase and continues to rise through the pores along with the methanol. Periodically (e.g., every 1 hour), the raw material condensed on the baffle plate 103 is flushed by the material flushing structure, allowing it to return to the reaction zone 102 to participate in the reaction.

[0058] The gaseous phase (including dimethyl phthalate and methanol) generated during the reaction in the reactor 1 is introduced into the reboiler of the distillation column 2, and a liquid phase (water at 25°C) is introduced at the top of the column. Inside the distillation column 2, the gaseous phase and the liquid phase are in countercurrent contact. The temperature of the distillation column is controlled at 120°C, the pressure at 0.1 MPa, the pressure drop not exceeding 8 kPa, and the gas-liquid volume ratio at 1.35:1. A very small portion of the raw material present in the gaseous phase dissolves in the liquid phase and is discharged through the reboiler of the distillation column 2 into other processing units. The gaseous product gas at the top of the distillation column 2 (mainly...) After being cooled to 40°C by cooler 3, most of the liquid methanol enters the separator 4, while a small portion is stored in storage tank 104 through the inlet of the material flushing structure for later use. Gas generated in separator 4 is discharged sequentially through gas washing bottle 9 and exhaust gas gauge 10. The liquid methanol in separator 4 enters product tank 5 via pipeline to obtain liquid product. The yield of liquid product in product tank 5 is obtained by the local level indicator. The conversion rate is obtained based on the amount of liquid product, and the conversion rate is calculated as follows:

[0059] Conversion rate = Actual amount of liquid product in the product tank / Theoretical amount of liquid product × 100%. The reaction ends when the conversion rate reaches 95%.

[0060] Using the above control method, the yield of the product octadecylamide was 80%.

[0061] Example 2

[0062] The reaction was carried out in accordance with Example 1, except that the molar ratio of dimethyl terephthalate to octadecylamine was 1:5.5, the reaction temperature was 180°C, and the pressure was 0.6 MPa.

[0063] The gas in the separator 4 is not discharged through the gas washing bottle 9 and the tail gas meter 10, but is instead evacuated by the vacuum pump 8 to control the pressure of the distillation column 2 to -0.1 MPa, and a pressure gradient is formed through the vacuum buffer tank 7, so that the gas phase flows with the pressure gradient.

[0064] The reaction ends when the amount of liquid product obtained through product tank 5 reaches 97% of the theoretical amount.

[0065] Using the above control method, the yield of the product octadecylamide was 82%.

[0066] The method provided by this invention allows for real-time monitoring of the conversion rate, which is beneficial for effectively improving the product yield and safety. The product yield of the method provided by this invention is as high as 80% or more. However, when the reaction is carried out directly in a traditional open reactor (the reaction conditions are the same as in Example 1, but without the baffle plate, material flushing structure and real-time monitoring structure for liquid phase product conversion of this invention), the conversion rate of methanol cannot be monitored in real time, and the reaction yield is only 68%.

[0067] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; 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. For example, the lifting structure can be changed to other mechanical lifting structures, including the combination of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, 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 reaction system, characterized in that, The reaction system includes a reaction vessel, a distillation column, a cooler, a separator, and a product tank connected in sequence. The reactor includes a closed vessel body with a reaction zone inside. A baffle plate is installed in the upper part of the vessel body above the reaction zone. The baffle plate has vent holes for gas to pass through. A local liquid level indicator is installed on the product tank.

2. The reaction system according to claim 1, wherein, The reactor is connected to a material flushing structure, the inlet of which is connected to the cooler, and the outlet of which is located inside the reactor above the baffle plate.

3. The reaction system according to claim 2, wherein, The material flushing structure includes a liquid storage tank, the inlet of which is connected to the liquid phase product outlet of the cooler, and the outlet of which is connected to a spray pipe for spraying the baffle plate.

4. The reaction system according to any one of claims 1-3, wherein, The reaction system further includes: a vacuum buffer tank, which is connected to the separating tank, and the vacuum buffer tank is connected to a vacuum pump; Alternatively, the reaction system may further include a gas washing bottle and a tail gas meter, with the gas washing bottle and tail gas meter connected in sequence to the separating tank.

5. The reaction system according to any one of claims 1-4, wherein, The reactor is equipped with a stirrer, and the baffle plate is installed on the rotating shaft of the stirrer. The baffle plate is a 40-60 mesh porous plate, and the holes on it form the air pores.

6. The reaction system according to any one of claims 1-5, wherein, The reactor also includes a shell fitted over the reactor body, and a heat-conducting space is formed between the shell and the reactor body. The heat-conducting space is used to fill the heat-conducting medium.

7. A reaction method based on the reaction system according to any one of claims 1-6, characterized in that, The reactants are fed into the reactor for reaction. The resulting gaseous phase is then introduced into the bottom of a distillation column, and a liquid phase is introduced at the top of the column. The gaseous product gas at the top of the distillation column is cooled by a cooler and separated by a separator before entering the product tank to obtain the liquid product. The amount of the liquid product in the product tank is read by a local level gauge, and the conversion rate is obtained based on the amount of liquid product. The conversion rate is calculated as follows: Conversion rate = Actual amount of liquid product in the product tank / Theoretical amount of liquid product × 100%; Preferably, the reaction is considered complete when the conversion rate is not less than 95%.

8. The reaction method according to claim 7, wherein, The reaction raw materials include dimethyl terephthalate and octadecylamine, which are added to the reaction vessel in a molar ratio of 1:4-6 to carry out an aminolysis reaction to obtain octadecylamine and methanol.

9. The reaction method according to claim 7 or 8, wherein, The reaction pressure in the reactor is 0.4-0.6 MPa, and the reaction temperature is 100-200℃.

10. The reaction method according to claim 7 or 8, wherein, The temperature of the distillation column is 100-130℃; And / or, the pressure of the distillation column is 0-0.3 MPa or -0.05 MPa to -0.15 MPa.

Images