A method for producing 4,4'-biphenyl diphenol by efficient debutylation

Abstract

The present application relates to the technical field of high-end fine chemicals preparation, and in particular to a method for producing 4,4'-biphenyldiphenol by efficient debutylation. The method is as follows: the material of the debutylation reaction is added to a reaction distillation kettle, and the temperature and pressure in the kettle are set; as the reaction proceeds, the gas phase at the top of the reaction distillation kettle enters the reaction distillation section; it is condensed and sent to the recovery unit of isobutylene for separation and purification; the reaction time is 3-5h; after the reaction is completed, crude 4,4'-biphenyldiphenol is discharged from the bottom of the reaction distillation kettle. The present application adopts a reaction distillation method, and the isobutylene produced in the reaction process is removed in time under the working condition that nitrogen is not passed, so as to improve the conversion rate of the reaction, improve the rate of the reaction, reduce the reaction time, reduce the material loss caused by the entrainment of excessive mist, so as to improve the purity and batch production capacity of the product 4,4'-biphenyldiphenol.

Description

Technical Field

[0001] The present application relates to the technical field of preparation of high-end fine chemicals, and in particular to a method for producing 4,4'-biphenol by efficient debutylation. Background Art

[0002] 4,4'-Bis(4,4'-dihydroxybiphenyl, p-hydroxybiphenol, hereinafter referred to as LBP) is a key basic monomer for the synthesis of polyphenylene sulfone (PPSU). PPSU has the characteristics of being able to absorb huge impacts without cracking or breaking when continuously exposed to humid and high temperature environments. It has become an ideal high-end material for medical devices and is mainly used in surgical instruments, dental instruments, medical equipment housings, etc. The commercialized products include Radel® and Acudel® of Solvay in the United States and Ultrason® P of BASF in Germany.

[0003] At the same time, 4,4'-biphenyldiphenol is also a key basic raw material for electronic-grade thermotropic liquid crystal polymers (TLCP). Since TLCP is a polymer with the highest strength and modulus, it has a very small linear expansion coefficient, outstanding heat resistance and stability, excellent radiation resistance, weathering resistance, flame retardancy and chemical corrosion resistance, and microwave transparency and optical, electrical, magnetic and separation functions. Therefore, TLCP has become an indispensable key raw material for strategic emerging industries such as electronic communications, aerospace, and national defense and military. According to data, the application of TLCP in the electronic and consumer electronics industries accounts for about 82%.

[0004] At present, there are mainly the following methods for preparing 4,4'-biphenyl diphenol: benzidine method, biphenyl sulfonation alkali fusion method, biphenyl halogenation high-pressure hydrolysis method and phenol method.

[0005] Among them, the phenol method is the mainstream process route in the world. The specific process mainly includes: under the action of a catalyst, phenol and isobutylene generate 2,6-di-tert-butylphenol (alkylation unit). The latter is coupled to 3,3',5,5'-tetra-tert-butyl-4,4'-biphenylphenol and over-oxidation products (oxidation coupling units) under the action of oxygen. Finally, isobutylene is released under the action of a catalyst to obtain a 4,4'-biphenylphenol product (debutylation unit). The chemical equation is as follows.

[0006]

[0007] Among them, the core of this process is the debutylation of 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to obtain 4,4'-biphenol. The above reaction process is analyzed from a thermodynamic point of view as a reversible reaction subject to thermodynamic equilibrium. As the number of de-tert-butyl groups increases, the reversible reaction makes it difficult to effectively control the reaction, resulting in a product yield of about 80%. The above reversible reaction subject to thermodynamic equilibrium is specifically shown below, with the diagrams showing the process of removing one butyl group, removing two butyl groups, removing three butyl groups, and removing four butyl groups.

[0008]

[0009] At present, although it has been reported that increasing the reaction temperature and extending the reaction time can promote the reversible reaction in the desired direction, increasing the reaction temperature will greatly increase the by-products, making it difficult to significantly improve the purity of the product, and the maximum yield is only 85-90%. Therefore, it is necessary to develop a high-efficiency and high-conversion de-tert-butylation reaction technology.

[0010] Currently, most methods adopt the method of blowing nitrogen into the reaction system to increase the amount of inert components in the system to reduce the system partial pressure of isobutylene and increase the rate of the reaction in the positive direction. However, this method has the following defects: first, a large amount of nitrogen blowing will form excessive mist entrainment, resulting in difficulty in isobutylene recovery and waste of resources; second, isobutylene dissolved in the solvent is easy to form dimers, trimers and other polyisobutylenes under high temperature and acidic conditions, resulting in difficulty in solvent circulation and separation. Summary of the invention

[0011] The present application provides a method for producing 4,4'-biphenol by efficient debutylation. The present application adopts a reactive distillation method to timely remove isobutylene produced during the reaction without nitrogen gas, so as to improve the reaction conversion rate, increase the reaction rate, reduce the reaction time, and reduce the material loss caused by excessive mist entrainment, so as to improve the purity and batch production capacity of the product 4,4'-biphenol.

[0012] The present application changes the current situation in which the debutylation process in the traditional reaction system is slow, i.e., the reaction rate is slow and there are relatively more incomplete debutylation products in the reaction product, reduces the waste of resources caused by material loss during the isobutylene recovery process, reduces the content of isobutylene dissolved in the reaction system, and avoids the formation of polymer isobutylene under high temperature and acidic conditions, which in turn causes the problem of reduced product purity and difficulty in solvent circulation and separation.

[0013] The present application provides a method for producing 4,4'-biphenol by efficient debutylation, which adopts the following technical scheme:

[0014] A method for producing 4,4'-biphenyl diphenol by efficient debutylation, wherein the process of producing 4,4'-biphenyl diphenol by debutylation of 3,3',5,5'-tetra-tert-butyl-4,4'-biphenyl diphenol is completed in a reactive distillation system;

[0015] The reaction distillation system comprises a reaction distillation kettle for completing a debutylation reaction, a reaction distillation section connected to the top of the reaction distillation kettle, a condenser and a reflux tank connected in sequence to the top of the reaction distillation section; the reaction distillation kettle, the reaction distillation section, the condenser and the reflux tank are connected by pipelines;

[0016] The materials for the debutylation reaction include 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol, a solvent and a catalyst;

[0017] The method specifically comprises the following steps:

[0018] Add the debutylation reaction material into the reaction distillation kettle, set the temperature in the reaction distillation kettle to 180-220° C., and the pressure in the kettle to normal pressure-0.4 MPaG;

[0019] As the reaction proceeds, the gas phase at the top of the reaction distillation kettle enters the reaction distillation section to separate isobutylene from the solvent; after the gas phase at the top of the reaction distillation section is condensed multiple times, a portion of the condensate flows back into the reaction distillation section and returns to the reaction distillation kettle through the bottom of the reaction distillation section, and the other portion is sent to the isobutylene recovery unit for separation and purification;

[0020] The reaction time is 3-5 hours; after the reaction is completed, crude 4,4'-biphenol is discharged from the bottom of the reaction distillation kettle.

[0021] Optionally, the pressure in the kettle is 0.1-0.3 MPaG.

[0022] In a specific embodiment, the pressure in the autoclave is 0.1 MPaG, 0.2 MPaG, 0.3 MPaG, or 0.4 MPaG.

[0023] In some specific embodiments, the pressure in the kettle is 0.1-0.2 MPaG, 0.2-0.3 MPaG, 0.2-0.4 MPaG, or 0.3-0.4 MPaG.

[0024] Optionally, the temperature in the kettle is 190-215°C.

[0025] In a specific embodiment, the temperature in the kettle is 180°C, 190°C, 205°C, 215°C, or 220°C.

[0026] In some specific embodiments, the temperature in the kettle is 180-190°C, 180-205°C, 180-215°C, 190-205°C, 190-215°C, 190-220°C, 205-215°C, 205-220°C, 215-220°C.

[0027] Optionally, the solvent includes any one or more of m-xylene, p-xylene, ethylbenzene, o-xylene, benzene, toluene, and isopropanol.

[0028] Optionally, the solvent is m-xylene.

[0029] Optionally, the catalyst includes any one or more of p-toluenesulfonic acid, dodecylbenzenesulfonic acid, pyrrolidonesulfonate ionic liquid, and phosphotungstic acid heteropoly acid.

[0030] Optionally, the catalyst is dodecylbenzenesulfonic acid.

[0031] Optionally, the feed weight ratio of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to the solvent is 1:(1-5).

[0032] Optionally, the feed weight ratio of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenyl diphenol to the solvent is 1:2.

[0033] In a specific embodiment, the feed weight ratio of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to the solvent is 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, or 1:5.

[0034] In some specific embodiments, the feed weight ratio of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to the solvent is 1:(1-1.5), 1:(1-2), 1:(1-2.5), 1:(1-3), 1:(1-4), 1:(1.5-2), 1:(1.5-2.5), 1:(1.5-3), 1:(1.5-4), 1:(1.5-5), 1:(2-2.5), 1:(2-3), 1:(2-4), 1:(2-5), 1:(2.5-3), 1:(2.5-4), 1:(2.5-5), 1:(3-4), 1:(3-5), 1:(4-5).

[0035] Optionally, the catalyst is added in an amount of 1-5 wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol.

[0036] Optionally, the catalyst is added in an amount of 2 wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol.

[0037] In a specific embodiment, the added amount of the catalyst is 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, or 5 wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol.

[0038] In some specific embodiments, the added amount of the catalyst is 1-2wt.%, 1-3wt.%, 1-4wt.%, 2-3wt.%, 2-4wt.%, 2-5wt.%, 3-4wt.%, 3-5wt.%, 4-5wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol.

[0039] Optionally, the crude 4,4'-biphenol is subjected to a separation and purification process to obtain high-purity 4,4'-biphenol.

[0040] Optionally, the separation and purification process includes centrifugal filtration, activated carbon decolorization, recrystallization and drying.

[0041] Optionally, the recovery unit includes alkaline washing desulfurization and distillation purification; the recovery unit obtains 99.9wt.% high-purity isobutylene after separation and purification.

[0042] Optionally, the condensate temperature of the gas phase at the top of the reaction distillation section is 5-50°C.

[0043] Optionally, the mass reflux ratio of the reaction distillation section is controlled at (0.1-5):1.

[0044] In summary, the present application includes at least one of the following beneficial technical effects:

[0045] The present application adopts a reactive distillation method to timely remove isobutylene produced during the reaction process without introducing nitrogen, so as to improve the reaction conversion rate, increase the reaction rate, reduce the reaction time, and reduce the material loss caused by excessive mist entrainment, so as to improve the purity of the product 4,4'-biphenol and the batch production capacity.

[0046] The present application changes the current situation in which the debutylation process in the traditional reaction system is slow, i.e., the reaction rate is slow and there are relatively more incomplete debutylation products in the reaction product, reduces the waste of resources caused by material loss during the isobutylene recovery process, reduces the content of isobutylene dissolved in the reaction system, and avoids the formation of polymer isobutylene under high temperature and acidic conditions, which in turn causes the problem of reduced product purity and difficulty in solvent circulation and separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The invention discloses a reactive distillation system used in the method for producing 4,4'-biphenol by efficient debutylation of the present application.

[0048] Figure 2 This is the reaction system used in the comparative example.

[0049] Figure numerals: 1. Reaction distillation kettle; 2. Reaction distillation section; 3. Condenser; 4. Reflux tank; 5. Pipeline. DETAILED DESCRIPTION

[0050] Before describing the embodiments of the present application in detail, it should be understood that the terms used herein are only used for the purpose of describing specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by ordinary technicians in the field to which the terms belong.

[0051] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0052] The endpoints and any values ​​of the ranges disclosed in this application 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0053] In the present application, the terms "comprise" or "include" are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0054] The present application provides a method for producing 4,4'-biphenyl diphenol by efficient debutylation. The method completes the process of producing 4,4'-biphenyl diphenol by debutylation of 3,3',5,5'-tetra-tert-butyl-4,4'-biphenyl diphenol in a reactive distillation system.

[0055] The reaction distillation system includes a reaction distillation kettle for completing the debutylation reaction, a reaction distillation section connected to the top of the reaction distillation kettle, a condenser and a reflux tank connected to the top of the reaction distillation section in sequence. The reaction distillation kettle, the reaction distillation section, the condenser and the reflux tank are connected by pipelines.

[0056] The materials for the debutylation reaction include 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol, a solvent and a catalyst;

[0057] The above method specifically comprises the following steps:

[0058] Add the materials of debutylation reaction into the reaction distillation kettle, set the temperature of the reaction distillation kettle to 180-220°C, and the pressure of the kettle to normal pressure-0.4MPaG;

[0059] As the reaction proceeds, the gas phase at the top of the reaction distillation kettle enters the reaction distillation section to separate isobutylene from the solvent; after the gas phase at the top of the reaction distillation section is condensed multiple times, a part of the condensate flows back to the reaction distillation section and returns to the reaction distillation kettle through the bottom of the reaction distillation section, and the other part is sent to the isobutylene recovery unit for separation and purification;

[0060] The reaction time is 3-5 hours; after the reaction is completed, crude 4,4'-biphenol is discharged from the bottom of the reaction distillation kettle.

[0061] The solvent includes any one or more of m-xylene, p-xylene, ethylbenzene, o-xylene, benzene, toluene and isopropanol.

[0062] The catalyst includes any one or more of p-toluenesulfonic acid, dodecylbenzenesulfonic acid, pyrrolidonesulfonate ionic liquid, and phosphotungstic acid heteropoly acid.

[0063] The feed weight ratio of 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to the solvent is 1:(1-5).

[0064] Wherein, the added amount of the catalyst is 1-5 wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol.

[0065] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The embodiments described below are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0066] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0067] Unless otherwise specified, all concentrations used are weight percentages, and the standard atmospheric pressure is 100 kPa.

[0068] The present application is further described in detail below in conjunction with the embodiments and test results. Example Example 1

[0069] This embodiment provides a reactive distillation system.

[0070] like Figure 1 As shown, the reaction distillation system includes a reaction distillation kettle 1, a reaction distillation section 2, a condenser 3 and a reflux tank 4.

[0071] The top of the reaction distillation kettle 1 is connected to the middle of the reaction distillation section 2 through a pipeline 5, and the bottom of the reaction distillation section 2 is connected to the top of the reaction distillation kettle 1 through a pipeline 5. The top of the reaction distillation section 2 is sequentially connected with a condenser 3 and a reflux tank 4. In this embodiment, the number of condensers 3 is 2. The bottom of the reflux tank 4 is connected to the top of the reaction distillation section 2 through a pipeline 5. In addition, the reflux tank 4 is also connected to the recovery unit of isobutylene.

[0072] The reaction distillation kettle 1 is used to complete the debutylation reaction. During use, the material for the debutylation reaction is placed in the reaction distillation kettle 1, and the temperature and pressure in the kettle are set to carry out the debutylation reaction. A jacket is provided on the outside of the reaction distillation kettle 1, and the temperature of the material in the kettle is controlled by adding heat transfer oil to the jacket.

[0073] As the reaction proceeds, the gas phase at the top of the reaction distillation kettle 1 enters the reaction distillation section 2 to separate isobutylene from the solvent. After the gas phase at the top of the reaction distillation section 2 is condensed multiple times, a portion of the condensate flows back to the reaction distillation section 2 and returns to the reaction distillation kettle 1 through the bottom of the reaction distillation section 2, and the other portion is sent to the isobutylene recovery unit for separation and purification.

[0074] After the reaction is completed, crude 4,4'-biphenol is discharged from the bottom of the reaction distillation reactor 1. The crude 4,4'-biphenol is subjected to separation and purification processes such as centrifugal filtration, activated carbon decolorization, recrystallization, and drying to obtain high-purity 4,4'-biphenol. Example 2

[0075] This embodiment provides a method for producing 4,4'-biphenyldiphenol by efficient debutylation. The reactive distillation system used in the method is the reactive distillation system provided in Example 1.

[0076] The above specifically includes the following steps:

[0077] (1) Add 5000 kg of 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol (tetra-tert-butylphenol in Table 1), 7500 kg of m-xylene (solvent) and 100 kg of p-toluenesulfonic acid (catalyst) into the reaction distillation reactor 1. After sufficient stirring, introduce heat transfer oil into the jacket of the reaction distillation reactor 1 and gradually increase the temperature of the materials in the reaction distillation reactor 1 to 205°C.

[0078] (2) As the reaction proceeds, the gas phase in the reaction distillation reactor 1 enters the reaction distillation section 2, and the pressure in the reaction distillation reactor 1 is controlled to be maintained at 0.2 MPaG. At this time, the gas phase temperature at the top of the reaction distillation section 2 is 53.0°C, and the liquid phase temperature is 24.7°C after multi-stage condensation and cooling of the gas phase. The mass reflux ratio of the reaction distillation section 2 is 3:1.

[0079] (3) The material reacts in the reaction distillation reactor 1 for 3.5 hours, and the reaction is completed. At this time, 2098.1 kg of isobutylene is recovered by separation and purification in the isobutylene recovery unit.

[0080] Crude 4,4'-biphenol was discharged from the bottom of the reaction distillation kettle. After subsequent separation and purification steps such as centrifugal filtration, activated carbon decolorization, recrystallization, and drying, 1988.6 kg of high-purity 4,4'-biphenol was obtained (Note: steps such as centrifugal filtration and recrystallization will cause a loss of about 5% in product yield, and the following examples are all carried out in the same purification method).

[0081] According to liquid chromatography analysis, the purity of the obtained 4,4'-biphenyl diphenol was 99.8wt.%, and the calculated mass yield was 40.50% (theoretical mass yield was 45.35%). The purity of the recovered isobutylene was 97.9wt.%, and the calculated mass yield was 41.92% (theoretical mass yield was 54.66%).

[0082] Example 3-17

[0083] Examples 3-17 respectively provide a method for producing 4,4'-biphenol by efficient debutylation.

[0084] The differences between the above embodiment and embodiment 2 are as shown in Table 1, and the rest are consistent with embodiment 2.

[0085] The differences of Examples 2-17 are as follows:

[0086] The difference between Examples 2-4 is the temperature inside the reaction distillation reactor 1.

[0087] The difference between Example 5-7 and Example 2 is: the pressure inside the reaction distillation reactor 1.

[0088] The difference between Example 8-10 and Example 2 is: the amount of solvent m-xylene used.

[0089] The difference between Example 11-12 and Example 2 is: the type of solvent.

[0090] The difference between Example 13-14 and Example 2 is: the amount of the catalyst p-toluenesulfonic acid used.

[0091] The difference between Examples 15-17 and Example 2 is the type of catalyst.

[0092] The reaction parameters and product information of the above examples are specifically shown in Table 1.

[0093] Table 1 Reaction parameters and product information of the examples

[0094]

[0095] As shown in Table 1, by comparing the reaction time and product quality yield of Examples 2-4, it can be seen that as the reaction temperature increases, it is beneficial to improve the product quality yield, that is, to improve the conversion rate of the reaction, while shortening the reaction time.

[0096] By comparing the reaction time and product quality yield of Example 2 and Examples 5-7, it can be seen that reducing the pressure of the reaction distillation reactor 1 can significantly increase the reaction rate, thereby shortening the time required for the reaction. However, due to the limitation of the cooling medium in the condenser 3, a certain degree of isobutylene loss is caused.

[0097] By comparing the products of Example 2 and Examples 8-10, it can be seen that the amount of solvent used has no significant effect on the overall reaction rate and product quality, but when the solvent is less (such as Example 10), the reaction distillation reactor 1 has a serious blockage problem, that is, it is impossible to form a flowable slurry.

[0098] By comparing the products of Example 2 and Examples 11-12, it can be seen that the different solvent types will affect the reaction rate to a certain extent, but the overall impact is not large. By comparing the products of Example 2 and Examples 13-14, it can be seen that the amount of catalyst used will affect the product quality yield and reaction time. Further comparison of the products of Example 2 and Example 14 shows that the amount of catalyst used is from 100kg to 250kg, and the yield of the product 4,4-biphenyldiphenol is not much different. It can be seen that when a certain amount is reached, the improvement in reaction performance is not obvious.

[0099] By comparing the products of Example 2 and Examples 15-17, it can be seen that the type of catalyst has a certain influence on the mass yield of 4,4'-biphenol, and dodecylbenzenesulfonic acid is the preferred catalyst. Comparative Example

[0100] This comparative example provides a method for carrying out a debutylation reaction using a stirred reactor with cooling and reflux. The reaction system used is as follows: Figure 2 shown.

[0101] The process is as follows:

[0102] Add 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol, 7500kg of m-xylene (solvent), and 100kg of p-toluenesulfonic acid (catalyst) into the reactor. After sufficient stirring, introduce heat transfer oil into the reactor jacket and gradually increase the temperature of the materials in the reactor to 205°C. Continue to introduce nitrogen (20Nm 3 / h) for stripping, and the cooling reflux temperature was controlled to be not less than 80°C. The reaction materials reacted in the reactor for 6.5h, and the reaction was completed.

[0103] At this time, 1158.2 kg of isobutylene was recovered through separation and purification by the isobutylene recovery unit. Crude 4,4'-biphenol was discharged from the bottom of the reactor, and after subsequent separation and purification steps such as centrifugal filtration, activated carbon decolorization, recrystallization, and drying, 1641.7 kg of 4,4'-biphenol was obtained.

[0104] According to liquid chromatography analysis, the purity of the obtained 4,4'-biphenyl diphenol was 98.8wt.%, and the calculated mass yield was 33.10% (theoretical mass yield was 45.35%). The purity of the recovered isobutylene was 91.8wt.%, and the calculated mass yield was 21.26% (theoretical mass yield was 54.66%).

[0105] It can be clearly found from the comparative examples that in the reaction system using non-reactive distillation, the purity and yield of the obtained product 4,4'-biphenol are reduced to a certain extent. The main reason is that the isobutylene converted by the reaction is dissolved in the solvent and refluxed into the reactor after cooling, resulting in the inability to extract the isobutylene in time, resulting in a decrease in the conversion rate, that is, a decrease in the yield. The semi-debutylation product that has not reacted completely affects the purity of the product. Nitrogen stripping leads to a decrease in the partial pressure of isobutylene. At this time, even if cooling at a lower temperature, it will cause excessive mist entrainment, resulting in a significant decrease in the isobutylene yield. As for the decrease in the purity of isobutylene, it is mainly because the dimerization and trimer of isobutylene under acidic conditions are blown out with nitrogen, which affects the purity of isobutylene.

[0106] From the above, it can be seen that the present application couples the reaction system and the distillation separation to achieve the separation of the solvent and isobutylene during the reaction process, and removes the isobutylene in the system in time, thereby increasing the reaction rate and shortening the traditional kettle reaction time.

[0107] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing 4,4'-biphenol by efficient debutylation, characterized in that: The process of debutylating 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to produce 4,4'-biphenol is completed in a reactive distillation system; The reaction distillation system comprises a reaction distillation kettle (1) for completing a debutylation reaction, a reaction distillation section (2) connected to the top of the reaction distillation kettle (1), a condenser (3) connected to the top of the reaction distillation section (2) in sequence, and a reflux tank (4); the reaction distillation kettle (1), the reaction distillation section (2), the condenser (3) and the reflux tank (4) are connected via a pipeline (5); The materials for the debutylation reaction include 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol, a solvent and a catalyst; the feed weight ratio of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol to the solvent is 1:(1-2.5); the added amount of the catalyst is 2-5wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol; The solvent is selected from any one or more of m-xylene and p-xylene; The catalyst is selected from any one or more of p-toluenesulfonic acid, dodecylbenzenesulfonic acid, pyrrolidonesulfonate ionic liquid, and phosphotungstic acid heteropoly acid; The method specifically comprises the following steps: Adding the debutylation reaction material into the reaction distillation kettle (1), setting the temperature inside the reaction distillation kettle (1) to 205-215° C. and the pressure inside the kettle to 0.1-0.3 MPaG; As the reaction proceeds, the gas phase at the top of the reaction distillation kettle (1) enters the reaction distillation section (2) to separate isobutylene from the solvent; after the gas phase at the top of the reaction distillation section (2) is condensed multiple times, a portion of the condensate flows back into the reaction distillation section (2) and returns to the reaction distillation kettle (1) through the bottom of the reaction distillation section (2), and the other portion is sent to the isobutylene recovery unit for separation and purification; The reaction time is 3-3.5 hours. After the reaction is completed, crude 4,4'-biphenol is discharged from the bottom of the reaction distillation reactor (1).

2. The method according to claim 1, characterized in that The feed weight ratio of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenyl diphenol to the solvent is 1:

2.

3. The method according to claim 1, characterized in that The added amount of the catalyst is 2 wt.% of the 3,3',5,5'-tetra-tert-butyl-4,4'-biphenol.

4. The method according to claim 1, characterized in that The crude 4,4'-biphenol is subjected to a separation and purification process to obtain high-purity 4,4'-biphenol; the separation and purification process includes centrifugal filtration, activated carbon decolorization, recrystallization, and drying.

5. The method according to claim 1, characterized in that The recovery unit includes alkaline washing desulfurization and distillation purification; the recovery unit obtains 99.9wt.% high-purity isobutylene after separation and purification.

6. The method according to claim 1, characterized in that The condensate temperature of the top gas phase of the reaction distillation section (2) is 5-50° C.; the mass reflux ratio of the reaction distillation section (2) is controlled at (0.1-5):1.

Images