Method for preparing 4-hexen-3-one by using aluminum chloride ionic liquid combined with high gravity reactor

Abstract

The application discloses a method for preparing 4-hexen-3-one by using an aluminum chloride ionic liquid combined with a high gravity reactor, and belongs to the technical field of compound preparation. The method comprises the following steps: adding dichloromethane and an aluminum chloride ionic liquid into a storage tank, stirring and cooling; pumping propionyl chloride into a high gravity reactor, introducing propylene gas, and controlling the reaction temperature; after the reaction is completed, the reaction liquid is separated into layers, and the ionic liquid layer is separated out and recycled; the dichloromethane layer is washed by a sodium carbonate aqueous solution, and then is transferred to a rectifying column; dichloromethane is recovered by normal pressure distillation, and 4-hexen-3-one products are collected by reduced pressure distillation. Compared with the prior art, the application significantly improves the yield of 4-hexen-3-one by optimizing the catalyst system and the reaction conditions, and the catalyst system of the application shows a relatively low activity decline rate in multiple cycles, thereby reducing the production cost and environmental pollution, and having a good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compound preparation, in particular to a method for preparing 4-hexen-3-one by using aluminum chloride ionic liquid combined with a high gravity reactor. BACKGROUND

[0002] 4-hexen-3-one is an important organic compound, widely used in the fields of medicine, perfume and chemical industry. The traditional method for preparing 4-hexen-3-one usually adopts Friedel-Crafts acylation reaction. Although this method can effectively synthesize the target product, it has some limitations in actual production. For example, the catalyst used in the traditional method (such as aluminum chloride) is difficult to recover and reuse after the reaction, leading to waste of catalyst and environmental pollution problems. In addition, the reaction conditions are relatively harsh, requiring high temperature and pressure, which not only increases energy consumption, but also may cause side reactions, reducing the yield and purity of the target product.

[0003] In recent years, with the gradual penetration of the concepts of green chemistry and sustainable development, developing efficient and environmentally friendly methods for preparing 4-hexen-3-one has become an important research direction in the field of chemical industry. Ionic liquids, as a new type of green solvent and catalyst carrier, have shown great application potential in organic synthesis due to their low volatility, high thermal stability and designability. However, the existing ionic liquid catalysts still have problems of insufficient activity and stability in the preparation of 4-hexen-3-one, limiting their application in industrial production.

[0004] In recent years, high gravity reactors as a new type of efficient reaction equipment have gradually attracted attention. It generates a high gravity field by high-speed rotation, significantly enhancing mass transfer and mixing effect, and can realize efficient chemical reaction under low temperature and low pressure conditions. Compared with traditional reactors, high gravity reactors have the advantages of high mass transfer efficiency, mild reaction conditions, compact equipment, high safety, etc., and are particularly suitable for organic synthesis reactions that require efficient mass transfer and mixing.

[0005] Chinese patent application publication No. CN 117105756 A discloses a method for preparing 4-hexen-3-one. Propionyl chloride and propylene are subjected to Friedel-Crafts reaction in the presence of a catalyst, and then base hydrolysis is carried out using triethylamine, to finally obtain 4-hexen-3-one. This method uses propionyl chloride as raw material, and there are no difficult by-products in the production process. Triethylamine can be recycled and reused, thereby significantly reducing material cost and processing cost, and the production operation is simple, the equipment demand is small, and the yield is high, which is suitable for large-scale production of 4-hexen-3-one. However, the use of triethylamine as a base hydrolysis reagent in this method may introduce impurities during the reaction, affecting the purity of the product, and the reusability is low. SUMMARY

[0006] To address the shortcomings of existing technologies, this invention aims to provide a method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor. This method improves reaction efficiency and selectivity by optimizing the catalyst system and reaction conditions, while simultaneously reducing production costs and environmental pollution, providing an efficient and environmentally friendly solution for the industrial production of 4-hexen-3-one.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor includes the following steps:

[0009] Step 1: Add dichloromethane solvent and aluminum trichloride ionic liquid to the storage tank, stir evenly, cool down and keep at a low temperature before adding to the hypergravity reactor;

[0010] Step 2: Pump propionyl chloride into the centrifugal reactor and control the reaction temperature and rotation speed;

[0011] Step 3: Introduce propylene gas into the reactor and maintain the reaction temperature;

[0012] Step 4: After the reaction is complete, the reaction solution is transferred to a layering vessel and allowed to stand for layering to separate the ionic liquid layer and the dichloromethane layer. The ionic liquid layer is then recycled.

[0013] Step 5: Wash the dichloromethane layer with sodium carbonate aqueous solution, let it stand and separate into layers, discard the water layer, and repeat the washing process.

[0014] Step 6: Transfer the washed dichloromethane bed to a distillation column, first recover dichloromethane by atmospheric distillation, and then perform vacuum distillation to collect the 4-hexen-3-one product.

[0015] Preferably, the method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a centrifugal reactor is as follows, in parts by weight:

[0016] Step 1: Add 200-300 parts of dichloromethane solvent and 10-20 parts of aluminum trichloride ionic liquid to the storage tank, stir evenly, lower the temperature of the mixture to 0-5℃, and keep this temperature before adding it to the hypergravity reactor.

[0017] Step 2: Prepare propionyl chloride in another storage tank, and use a metering pump to pump propionyl chloride into the hypergravity reactor at a flow rate of 0.1~0.5L / min. At the same time, control the temperature of the hypergravity reactor at 0~5℃ and the rotation speed at 300~800rpm.

[0018] Step 3: Introduce propylene gas into the supergravity reactor at a flow rate of 0.1-1 L / min and maintain the reaction temperature at 0-5℃.

[0019] Step 4: After the reaction is complete, transfer the reaction solution to a layered reactor, let it stand to separate the ionic liquid layer and the dichloromethane layer, and recover and reuse the ionic liquid layer.

[0020] Step 5: Transfer the dichloromethane layer to the washing equipment, wash it with sodium carbonate aqueous solution, stir evenly, let it stand to separate into layers, discard the water layer, wash the dichloromethane layer with water again, repeat the above operation, and discard the water layer.

[0021] Step 6: Transfer the washed dichloromethane layer to a distillation column, first heat it up for atmospheric distillation to recover dichloromethane, and then perform vacuum distillation to collect the 4-hexen-3-one product.

[0022] The volume ratio of the dichloromethane layer to the sodium carbonate aqueous solution is 1:0.5~2.

[0023] The temperature for atmospheric distillation is 40~50℃.

[0024] The temperature of the vacuum distillation is less than 100°C.

[0025] The aluminum trichloride ionic liquid is at least one of triethylamine hydrochloride-aluminum trichloride ionic liquid and composite aluminum trichloride ionic liquid.

[0026] The preparation method of the triethylamine hydrochloride-aluminum trichloride ionic liquid is as follows, in parts by weight:

[0027] In a sealed three-necked flask, after replacing the air with nitrogen, stir at a speed of 300-500 rpm, and add 80-120 parts of triethylamine hydrochloride and 10-30 parts of anhydrous aluminum trichloride in sequence. Then raise the temperature to 80-95°C and continue the reaction at the same stirring speed until the reaction solution turns light brown. After the reaction is completed, cool to room temperature to obtain triethylamine hydrochloride-aluminum trichloride ionic liquid.

[0028] The preparation method of the composite aluminum trichloride ionic liquid includes the following steps:

[0029] S1. Add rare earth metal nitrates and water to a stirrer, then add molecular sieve ZSM-5, place the mixture in a water bath and stir to evaporate, then dry in an oven, and finally heat in a muffle furnace to obtain the pretreated product.

[0030] S2. Mix transition metal nitrate, anhydrous aluminum trichloride and dichloromethane, add the pretreated material, stir evenly to obtain composite aluminum trichloride ionic liquid.

[0031] Preferably, the preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0032] S1. Add 5-10 parts of rare earth metal nitrate and 100-150 parts of water to a stirrer with a stirring speed of 300-500 rpm, then add 20-40 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 70-80℃ and stir to evaporate. Continue stirring for 5-10 hours, then place the mixture in an oven at 80-95℃ to dry overnight. Transfer the dried sample to a muffle furnace and heat it to 400-600℃ at a heating rate of 10-20℃ / min. Hold this temperature for 1-5 hours to obtain the pretreated product.

[0033] S2. Weigh 1-3 parts of transition metal nitrate, 2-5 parts of anhydrous aluminum trichloride and 50-70 parts of dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 400-700 rpm and stir for 0.5-1 hour. Add 20-40 parts of the pretreated material prepared in step S1 and continue stirring for 1-3 hours to obtain composite aluminum trichloride ionic liquid.

[0034] The rare earth metal nitrate is at least one of lanthanum nitrate and cerium nitrate.

[0035] The transition metal nitrate is at least one of nickel nitrate, chromium nitrate, and cobalt nitrate.

[0036] In the preparation method of the composite aluminum trichloride ionic liquid of the present invention, the roles of each substance are as follows:

[0037] Rare earth metal nitrates, as active components, provide additional active sites, enhancing the activity and selectivity of the catalyst. Rare earth metals possess unique electronic structures that enable them to more effectively activate reactants during the reaction process, promoting Friedel-Crafts acylation reactions.

[0038] Using molecular sieve ZSM-5 as a support provides high specific surface area and good thermal stability, enhancing the dispersibility and stability of the catalyst.

[0039] Water is used as a solvent to dissolve rare earth metal nitrates, which facilitates mixing with molecular sieve ZSM-5.

[0040] Transition metal nitrates, as active components, provide additional active sites, enhancing the activity and stability of the catalyst.

[0041] Anhydrous aluminum trichloride serves as the primary Lewis acid catalyst, providing acidic centers to facilitate the Friedel-Crafts acylation reaction.

[0042] Dichloromethane is used as a solvent to dissolve transition metal nitrates and anhydrous aluminum trichloride, facilitating mixing and dispersion.

[0043] In this invention, the various substances work synergistically to form a composite aluminum trichloride ionic liquid catalyst with high activity, high selectivity, and good stability. Rare earth metals and transition metals provide additional active sites, molecular sieve ZSM-5 provides high specific surface area and thermal stability, while anhydrous aluminum trichloride, as the main Lewis acid catalyst, promotes the Friedel-Crafts acylation reaction. The synergistic effect of these components significantly improves the synthesis efficiency of 4-hexen-3-one and the catalyst's lifetime.

[0044] Compared with existing technologies, it has the following advantages:

[0045] 1) This invention achieves a high-yield synthesis of 4-hexen-3-one by optimizing reaction conditions and catalyst system. Using the method of this invention, the yield of 4-hexen-3-one is significantly higher than that of existing technologies. Furthermore, by precisely controlling the reaction conditions, this invention can effectively reduce the occurrence of side reactions and improve the selectivity of the target product.

[0046] 2) The aluminum trichloride ionic liquid catalyst used in this invention exhibits high activity and good stability. In particular, the performance of the catalyst is further enhanced by introducing rare earth metals and transition metals in the preparation of the composite aluminum trichloride ionic liquid. Furthermore, the ionic liquid layer can be recovered and reused after the reaction, reducing the amount of catalyst used, lowering production costs, and reducing waste emissions, thus demonstrating good environmental friendliness.

[0047] 3) This invention combines the efficient mass transfer and mixing characteristics of a hypergravity reactor, significantly improving reaction efficiency and stability. The hypergravity reactor enables highly efficient Friedel-Crafts acylation reactions at low temperatures, reducing energy consumption while improving reaction safety and controllability. Furthermore, by optimizing reaction conditions and the catalyst system, this invention exhibits a low activity degradation rate during multiple cycles, further enhancing the process's economics and sustainability. Detailed Implementation

[0048] Main source of materials:

[0049] Molecular sieve ZSM-5, product number: DZ-3, silicon-to-aluminum ratio: 40, Shandong Dengzhuo Chemical Co., Ltd.

[0050] All other raw materials used in the embodiments and comparative examples of this invention are commercially available products.

[0051] The design concept of this invention lies in developing an efficient and stable method for preparing 4-hexen-3-one by combining the technical advantages of aluminum trichloride ionic liquid and a hypergravity reactor. Utilizing the high activity and recyclability of the aluminum trichloride ionic liquid, and the efficient mass transfer and mixing environment provided by the hypergravity reactor, the efficiency and selectivity of the Friedel-Crafts acylation reaction are significantly improved, thereby achieving a high-yield synthesis of 4-hexen-3-one. Simultaneously, by optimizing the catalyst composition and reaction conditions, the stability and economy of the reaction are further enhanced, providing a feasible solution for the industrial production of 4-hexen-3-one.

[0052] Example 1

[0053] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is as follows, in parts by weight:

[0054] Step 1: Add 250 parts of dichloromethane solvent and 15 parts of triethylamine hydrochloride-aluminum trichloride ionic liquid to the storage tank, stir evenly, lower the temperature of the mixture to 3°C, and keep this temperature before adding it to the hypergravity reactor.

[0055] Step 2: Prepare propionyl chloride in another storage tank, and use a metering pump to pump propionyl chloride into the hypergravity reactor at a flow rate of 0.3 L / min. At the same time, control the temperature of the hypergravity reactor at 3℃ and the rotation speed at 500 rpm.

[0056] Step 3: Introduce propylene gas into the supergravity reactor at a flow rate of 0.8 L / min and maintain the reaction temperature at 3°C;

[0057] Step 4: After the reaction is complete, transfer the reaction solution to a layered reactor, let it stand to separate the ionic liquid layer and the dichloromethane layer, and recover and reuse the ionic liquid layer.

[0058] Step 5: Transfer the dichloromethane layer to the washing equipment and wash it with a 10wt% sodium carbonate aqueous solution at a volume ratio of 1:1 for dichloromethane layer to sodium carbonate aqueous solution. After stirring evenly, let it stand to separate into layers, discard the water layer, wash the dichloromethane layer with water again, repeat the above operation, and discard the water layer.

[0059] Step 6: Transfer the washed dichloromethane layer to a distillation column, first heat it to 45°C for atmospheric distillation to recover dichloromethane. After distillation, perform vacuum distillation, controlling the temperature at 80°C, and collect the 4-hexen-3-one product.

[0060] The preparation method of the triethylamine hydrochloride-aluminum trichloride ionic liquid is as follows, in parts by weight:

[0061] In a sealed three-necked flask, after replacing the air with nitrogen, the mixture was stirred at 400 rpm, and 100 parts of triethylamine hydrochloride and 20 parts of anhydrous aluminum trichloride were added sequentially. The temperature was then raised to 90°C, and the reaction was continued at the same stirring speed until the reaction solution turned light brown. After the reaction was completed, the mixture was cooled to room temperature to obtain a triethylamine hydrochloride-aluminum trichloride ionic liquid.

[0062] Example 2

[0063] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is the same as in Example 1, except that the triethylamine hydrochloride-aluminum trichloride ionic liquid is replaced with a composite aluminum trichloride ionic liquid.

[0064] The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0065] S1. Add 8 parts of cerium nitrate and 130 parts of water to a stirrer with a stirring speed of 400 rpm, followed by 30 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 75°C and stir to evaporate for 8 hours. Then place the mixture in an oven at 90°C and dry overnight. Transfer the dried sample to a muffle furnace and heat it to 500°C at a heating rate of 15°C / min. Hold the temperature at this temperature for 3 hours to obtain the pretreated product.

[0066] S2. Weigh 2 parts of chromium nitrate, 4 parts of anhydrous aluminum trichloride and 60 parts of dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 600 rpm and stir for 0.8 hours. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain composite aluminum trichloride ionic liquid.

[0067] Example 3

[0068] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is the same as in Example 2, except that the preparation method of the composite aluminum trichloride ionic liquid is different.

[0069] The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0070] S1. Add 8 parts of lanthanum nitrate and 130 parts of water to a stirrer with a stirring speed of 400 rpm, followed by 30 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 75°C and stir to evaporate for 8 hours. Then place the mixture in an oven at 90°C and dry overnight. Transfer the dried sample to a muffle furnace and heat it to 500°C at a heating rate of 15°C / min. Hold it at this temperature for 3 hours to obtain the pretreated material.

[0071] S2. Weigh 2 parts of chromium nitrate, 4 parts of anhydrous aluminum trichloride and 60 parts of dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 600 rpm and stir for 0.8 hours. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain composite aluminum trichloride ionic liquid.

[0072] Example 4

[0073] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is the same as in Example 2, except that the preparation method of the composite aluminum trichloride ionic liquid is different.

[0074] The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0075] S1. Add 8 parts of cerium nitrate and 130 parts of water to a stirrer with a stirring speed of 400 rpm, followed by 30 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 75°C and stir to evaporate for 8 hours. Then place the mixture in an oven at 90°C and dry overnight. Transfer the dried sample to a muffle furnace and heat it to 500°C at a heating rate of 15°C / min. Hold the temperature at this temperature for 3 hours to obtain the pretreated product.

[0076] S2. Weigh 2 parts nickel nitrate, 4 parts anhydrous aluminum trichloride and 60 parts dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 600 rpm and stir for 0.8 hours. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain composite aluminum trichloride ionic liquid.

[0077] Example 5

[0078] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is the same as in Example 2, except that the preparation method of the composite aluminum trichloride ionic liquid is different.

[0079] The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0080] S1. Add 8 parts of cerium nitrate and 130 parts of water to a stirrer with a stirring speed of 400 rpm, followed by 30 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 75°C and stir to evaporate for 8 hours. Then place the mixture in an oven at 90°C and dry overnight. Transfer the dried sample to a muffle furnace and heat it to 500°C at a heating rate of 15°C / min. Hold the temperature at this temperature for 3 hours to obtain the pretreated product.

[0081] S2. Weigh 2 parts cobalt nitrate, 4 parts anhydrous aluminum trichloride and 60 parts dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 600 rpm and stir for 0.8 hours. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain composite aluminum trichloride ionic liquid.

[0082] Comparative Example 1

[0083] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is the same as in Example 2, except that the preparation method of the composite aluminum trichloride ionic liquid is different.

[0084] The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0085] S1. Add 8 parts of ytterbium nitrate and 130 parts of water to a stirrer with a stirring speed of 400 rpm, followed by 30 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 75°C and stir to evaporate for 8 hours. Then place the mixture in an oven at 90°C and dry overnight. Transfer the dried sample to a muffle furnace and heat it to 500°C at a heating rate of 15°C / min. Hold it at this temperature for 3 hours to obtain the pretreated product.

[0086] S2. Weigh 2 parts of chromium nitrate, 4 parts of anhydrous aluminum trichloride and 60 parts of dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 600 rpm and stir for 0.8 hours. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain composite aluminum trichloride ionic liquid.

[0087] Comparative Example 2

[0088] A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor is the same as in Example 2, except that the preparation method of the composite aluminum trichloride ionic liquid is different.

[0089] The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight:

[0090] S1. Add 8 parts of cerium nitrate and 130 parts of water to a stirrer with a stirring speed of 400 rpm, followed by 30 parts of molecular sieve ZSM-5. Place the mixture in a water bath at 75°C and stir to evaporate for 8 hours. Then place the mixture in an oven at 90°C and dry overnight. Transfer the dried sample to a muffle furnace and heat it to 500°C at a heating rate of 15°C / min. Hold the temperature at this temperature for 3 hours to obtain the pretreated product.

[0091] S2. Weigh 2 parts copper nitrate, 4 parts anhydrous aluminum trichloride and 60 parts dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 600 rpm and stir for 0.8 hours. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain composite aluminum trichloride ionic liquid.

[0092] Test Example 1

[0093] Yield of 4-hexen-3-one was tested:

[0094] After the reaction was complete, the 4-hexen-3-one product collected in the distillation column was weighed and its mass was recorded. The theoretical yield was calculated based on the initial molar amount of the reactant propionyl chloride. The yield calculation formula is: Yield (%) = (Actual yield / Theoretical yield) × 100. Propionyl chloride, under the catalysis of a catalyst, undergoes a Friedel-Crafts acylation reaction with propylene gas to produce 4-hexen-3-one. The test results are shown in Table 1.

[0095] Table 1

[0096] Experimental protocol Yield (%) Example 1 96.4 Example 2 98.2 Example 3 97.5 Example 4 97.6 Example 5 98.1 Comparative Example 1 97.1 Comparative Example 2 97.3

[0097] Test Example 2

[0098] Stability test:

[0099] To evaluate the stability and reusability of the aluminum trichloride ionic liquid catalysts prepared in the embodiments and comparative examples of this invention during multiple cycles, the ionic liquid layer was separated from the reaction system and recovered after each reaction. The recovered ionic liquid was then reintroduced under the same reaction conditions for the next reaction. The change in activity of the ionic liquid during the 10 cycles was analyzed by recording the conversion rate of the reaction after 10 cycles. Generally, if the yield of the ionic liquid remains at a high level (e.g., not less than 90%) after 10 cycles, the ionic liquid can be considered to have good stability and reusability. The test results are shown in Table 2.

[0100] Table 2

[0101] Experimental protocol Yield (%) Drop (%) Example 1 87.4 9.34 Example 2 92.5 5.80 Example 3 90.1 7.59 Example 4 89.4 8.40 Example 5 95.3 2.85 Comparative Example 1 89.2 8.14 Comparative Example 2 88.9 8.63

[0102] As can be seen from the data of Test Example 1, the method of preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor in Example 2 has the highest yield, and the aluminum trichloride ionic liquid catalyst prepared in Example 2 has good stability.

[0103] In this invention, the aluminum trichloride ionic liquid prepared using cerium nitrate in Example 2 exhibited the highest yield and higher stability in the preparation of 4-hexen-3-one. This is likely because cerium nitrate can form a more stable composite structure with the molecular sieve ZSM-5 during preparation, thus providing more uniform and more active catalytic sites in subsequent reactions. Furthermore, cerium, as a rare earth element, possesses a unique electronic structure and redox properties, enabling it to more effectively activate propylene gas and propionyl chloride during the reaction, promoting the Friedel-Crafts acylation reaction. Simultaneously, it exhibits a low rate of activity degradation during repeated cycles. In contrast, while lanthanum nitrate and ytterbium nitrate also possess certain catalytic properties, they are slightly inferior in terms of activity and stability, which may be related to their electronic structure and the way they interact with the molecular sieve.

[0104] In the experimental design of this invention, the aluminum trichloride ionic liquid prepared from chromium nitrate used in Example 2 exhibited better catalytic efficiency and stability. This is mainly attributed to the unique chemical properties of chromium ions, which can efficiently promote the activation of propylene and propionyl chloride in the reaction system, thereby accelerating the Friedel-Crafts acylation reaction. Simultaneously, the synergistic effect between chromium ions and the ZSM-5 molecular sieve allows the catalyst to maintain relatively stable activity during repeated use, which is reflected in a low activity decay rate in stability tests. In contrast, although nickel nitrate and copper nitrate can also form composite structures with ZSM-5 molecular sieve, they exhibit slightly weaker catalytic activity and stability, which may be related to the chemical properties of nickel and copper ions and their interaction mechanism with the molecular sieve.

[0105] In this invention, the aluminum trichloride ionic liquid prepared using cobalt nitrate in Example 5 exhibited superior stability in the preparation of 4-hexen-3-one. The properties of cobalt ions make them more stable under the high shear stress conditions of a hypergravity reactor, reducing catalyst agglomeration and deactivation. Simultaneously, the interaction between cobalt ions and the ZSM-5 molecular sieve helps form more stable active sites, which maintain high activity during repeated use, resulting in a lower activity decline rate in stability tests. In contrast, while chromium nitrate exhibits high catalytic efficiency, its stability is slightly lower during repeated use, which may be related to the stability of chromium ions under high shear stress and its interaction with the molecular sieve.

Claims

1. A method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a centrifugal reactor, characterized in that, Includes the following steps: Step 1: Add dichloromethane solvent and aluminum trichloride ionic liquid to the storage tank, stir evenly, cool down and keep at a low temperature before adding to the hypergravity reactor; Step 2: Pump propionyl chloride into the centrifugal reactor and control the reaction temperature and rotation speed; Step 3: Introduce propylene gas into the reactor and maintain the reaction temperature; Step 4: After the reaction is complete, the reaction solution is transferred to a layering vessel and allowed to stand for layering to separate the ionic liquid layer and the dichloromethane layer. The ionic liquid layer is then recycled. Step 5: Wash the dichloromethane layer with sodium carbonate aqueous solution, let it stand and separate into layers, discard the water layer, and repeat the washing process. Step 6: Transfer the washed dichloromethane bed to a distillation column, first recover dichloromethane by atmospheric distillation, and then perform vacuum distillation to collect the 4-hexen-3-one product; The aluminum trichloride ionic liquid is a composite aluminum trichloride ionic liquid; The preparation method of the composite aluminum trichloride ionic liquid is as follows, in parts by weight: S1. Add 5-10 parts of rare earth metal nitrate and 100-150 parts of water to a stirrer with a stirring speed of 300-500 rpm, then add 20-40 parts of molecular sieve ZSM-5, place the mixture in a water bath at 70-80℃ and stir to evaporate, continue stirring for 5-10 hours, and then place the mixture in an oven at 80-95℃ to dry overnight. The dried sample is transferred to a muffle furnace and heated to 400-600°C at a heating rate of 10-20°C / min, and held at this temperature for 1-5 hours to obtain the pretreated sample. S2. Weigh 1-3 parts of transition metal nitrate, 2-5 parts of anhydrous aluminum trichloride and 50-70 parts of dichloromethane, mix them and put them into a stirrer. Control the stirring speed to 400-700 rpm and stir for 0.5-1 hour. Add 20-40 parts of the pretreated material prepared in step S1 and continue stirring for 1-3 hours to obtain composite aluminum trichloride ionic liquid. The rare earth metal nitrate is cerium nitrate; The transition metal nitrate is at least one of chromium nitrate and cobalt nitrate.

2. The method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor as described in claim 1, characterized in that, The method is as follows, by weight: Step 1: Add 200-300 parts of dichloromethane solvent and 10-20 parts of aluminum trichloride ionic liquid to the storage tank, stir evenly, lower the temperature of the mixture to 0-5℃, and keep this temperature before adding it to the hypergravity reactor. Step 2: Prepare propionyl chloride in another storage tank, and use a metering pump to pump propionyl chloride into the hypergravity reactor at a flow rate of 0.1~0.5L / min. At the same time, control the temperature of the hypergravity reactor at 0~5℃ and the rotation speed at 300~800rpm. Step 3: Introduce propylene gas into the supergravity reactor at a flow rate of 0.1-1 L / min and maintain the reaction temperature at 0-5℃. Step 4: After the reaction is complete, transfer the reaction solution to a layered reactor, let it stand to separate the ionic liquid layer and the dichloromethane layer, and recover and reuse the ionic liquid layer. Step 5: Transfer the dichloromethane layer to the washing equipment, wash it with sodium carbonate aqueous solution, stir evenly, let it stand to separate into layers, discard the water layer, wash the dichloromethane layer with water again, repeat the above operation, and discard the water layer. Step 6: Transfer the washed dichloromethane layer to a distillation column, first heat it up for atmospheric distillation to recover dichloromethane, and then perform vacuum distillation to collect the 4-hexen-3-one product.

3. The method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor as described in claim 1 or 2, characterized in that, The volume ratio of the dichloromethane layer to the sodium carbonate aqueous solution is 1:0.5~2.

4. The method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor as described in claim 1 or 2, characterized in that, The temperature for atmospheric distillation is 40~50℃.

5. The method for preparing 4-hexen-3-one using aluminum trichloride ionic liquid combined with a supergravity reactor as described in claim 1 or 2, characterized in that, The temperature of the vacuum distillation is less than 100°C.