Preparation method of isobutylbenzene

Abstract

The invention provides a preparation method of isobutylbenzene, which comprises the following steps: under a gas-solid reaction condition, in the presence of a catalyst, gas-phase toluene, propylene and hydrogen are subjected to a contact reaction in a microchannel reactor, and active components of the catalyst comprise alkali metal and Cu. According to the method disclosed by the invention, the reaction can be carried out under a gas-solid contact reaction condition, so that the catalyst does not need to be separated from a reaction product, and the reaction product does not need to be separated after the catalyst is inactivated by water or methanol (because the reaction speed of water or alcohol and alkali metal is high, a large amount of heat is released, and a fire risk is caused, and the risk is very high); therefore, the risk of the method is greatly reduced; the method provided by the invention can be used for reacting under a relatively low pressure condition, and the pressure is greatly reduced compared with the pressure (2-4Mpa) required by the traditional kettle reaction.

Description

Technical Field

[0001] This invention relates to a method for preparing isobutylene. Background Technology

[0002] Isobutylbezene (IBB) is a major intermediate in the synthesis of ibuprofen (Profe or Brufen), a human drug used for its anti-inflammatory, antipyretic, and analgesic effects. Ibuprofen, as an anti-inflammatory, antipyretic, and analgesic, can treat rheumatoid arthritis, osteoarthritis, toothache, neuralgia, etc., and also has good efficacy in treating inflammation, fever, and pain after gynecological and obstetric surgeries, with few adverse reactions and allowing for long-term use. Currently, other commonly used antipyretic and analgesic drugs have many problems. For example, some domestically produced oral acetaminophen preparations are unstable and not very effective for high fever, with a short duration of antipyretic action; aspirin and its compound preparations have significant side effects on the digestive and hematopoietic systems and may cause Reye's syndrome in children. Therefore, ibuprofen has a very broad market application prospect.

[0003] In the numerous synthetic routes for ibuprofen, almost all require the intermediate isobutylbenzene. To date, there are more than a dozen synthetic routes for isobutylbenzene, but most are laboratory preparation methods; some, while industrially feasible, suffer from difficulties in obtaining the necessary raw materials. Existing synthetic processes for isobutylbenzene primarily involve the side-chain alkylation reaction of toluene and propylene under alkali metal catalysis.

[0004] In 1950, scientists such as Pines first proposed the side-chain alkylation reaction of alkyl aromatic hydrocarbons with small molecule olefins catalyzed by a strong base. The strong base catalyst consists of an alkali metal or alkali metal hydride and a promoter. The promoter can be an aromatic hydrocarbon, phenyl cyanide, pyridine, or chloroalkanes, etc. Its main function is to induce the alkali metal or its oxide to form an organometallic compound, which then attacks the alkylbenzene. Currently, in industry, isobutylene is mainly synthesized from toluene and propylene in the presence of an alkali metal potassium-sodium catalyst. Because this method uses a potassium-sodium catalyst, the catalyst needs to be deactivated with water or alcohol during the synthesis process, posing a high safety risk. Furthermore, industrially, isobutylene is generally synthesized using a batch reactor, which cannot achieve continuous production. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a method for preparing isobutylene. The method described in this invention can effectively reduce safety risks, achieve continuous synthesis of isobutylene, and obtain high conversion rates and selectivity under low-pressure conditions.

[0006] To achieve the aforementioned objective, the present invention provides a method for preparing isobutylene, the method comprising: under gas-solid reaction conditions, in the presence of a catalyst, contacting and reacting gaseous toluene, propylene and hydrogen in a microchannel reactor, wherein the active component of the catalyst comprises an alkali metal and Cu.

[0007] The method of the present invention can carry out the reaction under gas-solid contact reaction conditions, thereby eliminating the need to separate the catalyst from the reaction products. This eliminates the need to deactivate the catalyst with water or methanol before separating the reaction products (since water or alcohol reacts rapidly with alkali metals, releasing a large amount of heat, posing a significant fire risk). Therefore, the method of the present invention greatly reduces the risk. Furthermore, the method of the present invention can react under lower pressure conditions, which is significantly lower than the pressure required for traditional batch reactions (2-4 MPa).

[0008] The method of the present invention solves the shortcomings of the prior art, such as the inability to produce isobutylene continuously and the high safety risks, by realizing continuous production and reducing safety risks through a microchannel fixed-bed reaction process. Detailed Implementation

[0009] 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.

[0010] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims in the appendix.

[0011] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0012] When this specification uses the prefixes "known to those skilled in the art," "prior art," or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those conventionally used in the art at the time the invention was proposed, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0013] It should be noted that the two or more aspects (or embodiments) disclosed in the context of this specification can be arbitrarily combined with each other, and the resulting technical solutions (such as methods or systems) are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0014] As previously stated, this invention provides a method for preparing isobutylene, comprising: reacting gaseous toluene, propylene, and hydrogen in a microchannel reactor under gas-solid reaction conditions in the presence of a catalyst, wherein the active component of the catalyst includes an alkali metal and Cu. The method of this invention enables the reaction to proceed under gas-solid contact reaction conditions, thereby eliminating the need to separate the catalyst from the reaction products. This eliminates the need to deactivate the catalyst with water or methanol before separating the reaction products (as water or alcohols react rapidly with alkali metals, releasing a large amount of heat and posing a significant fire risk). Therefore, the method of this invention significantly reduces the risk.

[0015] In this invention, the purpose of the invention can be achieved as long as it is carried out in a microchannel reactor. There are no special requirements for the specific microchannel reactor. For example, a microchannel reactor with an inner diameter of 2 to 5 mm can be used.

[0016] In this invention, the active components of the catalyst include alkali metals and Cu to achieve the purpose of this invention. The following is an illustrative description, but it does not limit the scope of this invention.

[0017] According to a preferred embodiment of the present invention, the content of the alkali metal is 0.1-20 wt% based on the total weight of the catalyst, preferably 14-18 wt%; the aforementioned preferred alkali metal content can ensure the safe and low-pressure operation of the method of the present invention.

[0018] According to a preferred embodiment of the present invention, the copper content is 0.1 to 15 wt%, preferably 0.5 to 10 wt%; the aforementioned preferred alkali metal content can ensure the safe and low-pressure operation of the method of the present invention.

[0019] There are no special requirements for the type of alkali metal in this invention. The following is an illustrative description, but it does not limit the scope of this invention.

[0020] According to a preferred embodiment of the present invention, the alkali metal is selected from Na and / or K; preferably, the alkali metal includes K and Na. The simultaneous use of K and Na enables higher conversion and selectivity under lower pressure conditions.

[0021] There are no special requirements for the content of alkali metals in this invention. The following is an illustrative description, but it does not limit the scope of this invention.

[0022] According to a preferred embodiment of the present invention, the weight ratio of sodium to potassium is (0.01–10):1, preferably (0.1–5):1. Using the aforementioned preferred sodium to potassium weight ratio enables higher conversion rates and selectivity under lower pressure conditions.

[0023] According to a preferred embodiment of the present invention, the sodium content is 0.5–10 wt% and the potassium content is 3–15 wt% based on the total weight of the catalyst. Using the aforementioned preferred sodium and potassium content enables higher conversion rates and selectivity to be obtained under lower pressure conditions.

[0024] The catalyst of the present invention can achieve the purpose of the present invention as long as it has the above-mentioned active components. There are no special requirements for its specific composition. For example, it may contain a support. The following is an example description, but it does not limit the scope of the present invention.

[0025] According to a preferred embodiment of the present invention, the catalyst is a supported catalyst, the catalyst comprising a support and the active component supported on the support.

[0026] In this invention, the range of selectable carriers is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. Preferably, the carrier is selected from one or more of alumina, silica, X-zeolite, and Y-zeolite; more preferably, it is one or more of alumina and X-zeolite; even more preferably, it is γ-alumina and X-zeolite, and even more preferably, it is X-zeolite. Using the aforementioned preferred carriers, higher conversion rates and selectivity can be obtained under lower pressure conditions.

[0027] In this invention, there are no special requirements for the specific particle size of the carrier. The carrier can be selected reasonably according to the requirements of the reactor. For example, carrier particles with a particle size of 500-1000μm can be selected.

[0028] The catalyst of the present invention can achieve the purpose of the present invention as long as it has the above-mentioned composition. There are no special requirements for its preparation method. The following is an illustrative description, but it does not limit the scope of the present invention.

[0029] This invention provides a method for preparing the catalyst described herein, the method comprising:

[0030] (1) The copper source is impregnated with the support, and the resulting solid is dried, calcined and reduced to obtain the catalyst precursor.

[0031] (2) Under vacuum conditions, the alkali metal is melted and mixed with the catalyst precursor.

[0032] In this invention, the mixing process has no special requirements; for example, it can be stirred.

[0033] In this invention, the carrier is dried as needed, for example, the carrier is dried at 200-300°C for 2-5 hours before use.

[0034] The types of carriers described in this invention have been described in detail above and will not be repeated here.

[0035] In this invention, there are no special requirements for the type of copper source; for example, it can be a water-soluble copper salt.

[0036] In this invention, there are no special requirements for the melting conditions, as long as it is possible to form an alkali metal molten state. The following is an illustrative description, but it does not limit the scope of the invention.

[0037] According to a preferred embodiment of the present invention, in step (2), the melting conditions include a temperature of 120-250°C, such as 140°C, 160°C, 180°C, 200°C, etc. The embodiments are provided as examples, but do not limit the scope of the invention.

[0038] In this invention, there are no special requirements for the melting time of the alkali metal; it is selected and determined based on the melting temperature. The melting time can be 0.5-5 hours, for example, 1 hour, 2 hours, 3 hours, or 4 hours. The embodiments are provided for illustrative purposes only and do not limit the scope of the invention.

[0039] To achieve good melt mixing, the melting is preferably carried out under dynamic conditions.

[0040] In specific melting operations, alkali metals can generally be added to a sealed container, the container is evacuated, and then heated to 120–250°C and maintained for 0.5–5 hours while being stirred.

[0041] In this invention, there are no special requirements for the immersion contact conditions in step (1). General load contact immersion conditions are applicable to this invention, such as equal volume immersion.

[0042] In this invention, there are no special requirements for the drying, calcination and reduction conditions in step (1). The following is an illustrative description, but it does not limit the scope of this invention.

[0043] According to one embodiment of the present invention, the drying temperature is, for example, 100–150°C, such as 100°C, 120°C, or 140°C. The drying time has no special requirements, but is, for example, 10–16 hours, such as 10 hours, 12 hours, 14 hours, or 16 hours. The embodiments are provided as examples and are not intended to limit the scope of the invention.

[0044] According to one embodiment of the present invention, the calcination temperature is, for example, 450–650°C, such as 500°C, 550°C, 600°C, or 650°C. The calcination time has no special requirements, but is, for example, 3–8 hours, such as 4 hours, 5 hours, 6 hours, or 7 hours. The embodiments are provided for illustrative purposes only and do not limit the scope of the invention.

[0045] According to one embodiment of the present invention, the reduction conditions include, for example, reduction in a hydrogen atmosphere at a reduction temperature of 150–300°C, such as 180°C, 250°C, or 280°C. The reduction time is not particularly required, but is for example 3–8 hours, such as 4 hours, 5 hours, 6 hours, or 7 hours. These embodiments are provided as examples and are not intended to limit the scope of the invention.

[0046] In this invention, there are no special requirements for the conditions of the contact reaction, and the range of optional amounts of each raw material in the contact reaction process is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention.

[0047] According to a preferred embodiment of the present invention, the molar ratio of toluene to propylene is (0.05–2.5):1, preferably (0.3–2.0):1, for example 0.5:1; 0.8:1; 1:1; 1.5:1; 1.8:1. The embodiments are provided for illustrative purposes only and do not limit the scope of the invention.

[0048] According to a preferred embodiment of the present invention, the molar ratio of toluene to hydrogen is (10-3):1, for example, 8:1; 7:1; 7:1; 5:1; 4:1. The examples are illustrative but do not limit the scope of the invention.

[0049] According to a preferred embodiment of the present invention, the contact is carried out under anhydrous and oxygen-free conditions.

[0050] According to a preferred embodiment of the present invention, the toluene weight hourly space velocity (WHSV) is 0.1–3.5 h⁻¹. -1 Preferably, it is 0.2 to 2.5 hours. -1 For example, 0.4h -1 0.5h -1 0.8h -1 1h -1 1.6h -1 1.8h -1 2.0h -1 2.3h -1 The embodiments are provided by way of example and are not intended to limit the scope of the invention.

[0051] The operating conditions for the contact reaction in this invention are not particularly required. This invention can be carried out at relatively low pressures. According to a preferred embodiment of this invention, the pressure of the contact reaction is 0.1 MPa to 1.0 MPa, preferably 0.1 to 0.8 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, or 0.7 MPa. The embodiments are provided for illustrative purposes only and do not limit the scope of the invention.

[0052] In this invention, there are no special requirements for the contact temperature; for example, the temperature is 150–300°C, preferably 170–250°C, such as 180°C, 200°C, 220°C, or 240°C. The embodiments are provided as examples, but do not limit the scope of the invention.

[0053] The present invention will be described in detail below through embodiments. In the following embodiments,

[0054] 1. Raw materials

[0055] The alumina is from Sasol GmbH, Germany, and is PURAL 200.

[0056] The silicon dioxide is from L044740500G of China National Pharmaceutical Group Chemical Reagent Company.

[0057] X molecular sieve is from Tianjin Nanhua Catalyst Co., Ltd., with a silicon-to-aluminum molar ratio of 2.5.

[0058] The Y molecular sieve was sourced from Tianjin Nanhua Catalyst Co., Ltd., with a silicon-to-aluminum molar ratio of 6.0.

[0059] The alkali metals are from China National Pharmaceutical Group Chemical Reagent Company.

[0060] Toluene comes from China National Pharmaceutical Group Chemical Reagent Company.

[0061] The propylene comes from Shanghai Weichuang Standard Gas Analysis Technology Co., Ltd.

[0062] The rest are all commercially available materials with no special requirements.

[0063] 2. Calculation method

[0064] The conversion rate of toluene is calculated as follows:

[0065] Toluene conversion rate = (moles of toluene converted / moles of toluene fed) * 100%;

[0066] The selectivity of isobutylene is calculated as follows:

[0067] Isobutylbenzene selectivity = (moles of isobutylbenzene generated / moles of toluene converted) * 100%.

[0068] Example 1

[0069] Catalyst preparation:

[0070] Alumina powder was compressed into tablets and pulverized into particles with a diameter of 500–1000 μm, and then dried at 250 °C for 3 h.

[0071] Alumina was impregnated with an equal volume of copper chloride aqueous solution and dried at 120°C for 12 hours; then calcined at 500°C for 5 hours, and then reduced at 250°C for 7 hours under a hydrogen atmosphere to obtain the catalyst precursor.

[0072] The above catalyst precursor was placed in a stainless steel reactor and mixed with the molten alkali metal required in Table 1. The catalyst composition is shown in Table 1.

[0073] Synthesis of isobutylene:

[0074] The catalyst obtained above was loaded into a microchannel reactor containing 10 channels, each with an inner diameter of 3 mm, in a nitrogen-protected glove box. The microchannel reactor was then transferred to a reaction apparatus under sealed conditions. In the reaction apparatus, toluene was heated and vaporized, then mixed with propylene and hydrogen, and introduced into the microchannel reactor for reaction. The toluene space velocity during the reaction was 2 h⁻¹. -1 The molar ratio of toluene to propylene was 1:1.2, the molar ratio of toluene to hydrogen was 5:1, the reaction temperature was 200℃, and the reaction pressure was 0.5MPa. The results are listed in Table 1.

[0075] Example 2

[0076] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0077] Example 3

[0078] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0079] Example 4

[0080] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0081] Example 5

[0082] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0083] Example 6

[0084] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0085] Example 7

[0086] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0087] Example 8

[0088] Unlike Example 1, the catalyst composition is different, and the pressure conditions and results are shown in Table 1. The conditions not shown are the same as those in Example 1.

[0089] Example 9

[0090] Unlike Example 1, the catalyst is different, and the pressure conditions and results are detailed in Table 1. Conditions not shown are the same as in Example 1.

[0091] Table 1

[0092]

[0093]

[0094] 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 preparing isobutylene, characterized in that, The method includes: under gas-solid reaction conditions, in the presence of a catalyst, contacting gaseous toluene, propylene and hydrogen in a microchannel reactor, wherein the active component of the catalyst includes alkali metal and Cu.

2. The preparation method according to claim 1, wherein, The inner diameter of the microchannel reactor is 2–5 mm.

3. The preparation method according to claim 1 or 2, wherein, Based on the total weight of the catalyst, The alkali metal content is 0.1–20 wt%, preferably 14–18 wt%; and / or The copper content is 0.1–15 wt%, preferably 0.5–10 wt%.

4. The preparation method according to any one of claims 1-3, wherein, The alkali metal is selected from Na and / or K; preferably, the alkali metal includes K and Na; More preferably, The weight ratio of sodium to potassium is (0.01–10):1, preferably (0.1–5):1; and / or The total weight of the catalyst is 0.5–10 wt% sodium and 3–15 wt% potassium.

5. The preparation method according to any one of claims 1-4, wherein, The catalyst is a supported catalyst, which includes a support and the active component supported on the support.

6. The preparation method according to claim 5, wherein, The support is selected from one or more of alumina, silica, X-zeolite, and Y-zeolite; preferably one or more of alumina and X-zeolite; more preferably one or more of γ-alumina and X-zeolite; and / or The particle size of the carrier is 500-1000 μm.

7. The preparation method according to any one of claims 1-6, wherein, The method for preparing the catalyst includes: (1) The copper source is impregnated with the support, and the resulting solid is dried, calcined and reduced to obtain the catalyst precursor. (2) Under vacuum conditions, the alkali metal is melted and mixed with the catalyst precursor.

8. The preparation method according to claim 7, wherein, In step (1), The drying temperature is 100–150°C; and / or The roasting temperature is 450–650℃; and / or The reduction conditions include reduction in a hydrogen atmosphere at a temperature of 150–300°C.

9. The preparation method according to any one of claims 1-8, wherein, The conditions for the contact reaction include: The molar ratio of toluene to propylene is (0.05–2.5):1, preferably (0.3–2.0):1; The molar ratio of toluene to hydrogen is (10–3):1; The contact was carried out under anhydrous and oxygen-free conditions; and / or The weight hourly space velocity (WHSV) of toluene is 0.1–3.5 h⁻¹. -1 Preferably, it is 0.2 to 2.5 hours. -1 .

10. The preparation method according to any one of claims 1-9, wherein, The conditions for the contact reaction include: The temperature is 150–300℃, preferably 170–250℃; and / or The pressure is 0.1 MPa to 1.0 MPa, preferably 0.2 to 0.8 MPa.

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