Method for preparing 4-hexene-3-ketone by using aluminum trichloride ionic liquid in combination with supergravity reactor

Abstract

The invention discloses a method for preparing 4-hexene-3-ketone by using an aluminum trichloride ionic liquid in combination with a supergravity reactor, and belongs to the technical field of compound preparation, and the method comprises the following steps: adding dichloromethane and the aluminum trichloride ionic liquid into a storage tank, stirring and cooling; pumping propionyl chloride into the supergravity reactor, introducing propylene gas, and controlling the reaction temperature; after the reaction is completed, layering the reaction liquid, and separating out an ionic liquid layer for recycling; and washing a dichloromethane material layer with a sodium carbonate aqueous solution, transferring the washed dichloromethane material layer to a rectifying tower, carrying out normal pressure distillation to recover dichloromethane, and carrying out reduced pressure distillation to collect a 4-hexene-3-ketone product. Compared with the prior art, the method has the advantages that the yield of 4-hexene-3-ketone is remarkably increased by optimizing the catalyst system and the reaction conditions, and the catalyst system shows a relatively low activity decline rate in repeated recycling, so that the production cost and the environmental pollution are reduced, and the method has a good industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of compound preparation, and particularly relates to a method for preparing 4-hexen-3-one by using aluminum chloride ionic liquid combined with a high-gravity reactor. Background Art

[0002] 4-Hexen-3-one is an important organic compound, which is widely used in the fields of medicine, spices and chemical industry. The traditional method for preparing 4-hexen-3-one usually adopts the Friedel-Crafts acylation reaction. Although this method can effectively synthesize the target product, there are 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, resulting in waste of the 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 concepts of green chemistry and sustainable development gradually taking root in people's hearts, developing an efficient and environmentally friendly method for preparing 4-hexen-3-one has become an important research direction in the chemical industry. As a new type of green solvent and catalyst carrier, ionic liquids have shown great application potential in organic synthesis due to their advantages such as low volatility, high thermal stability and designability. However, existing ionic liquid catalysts still have problems of insufficient activity and stability when preparing 4-hexen-3-one, which limits their application in industrial production.

[0004] In recent years, as a new type of efficient reaction equipment, high-gravity reactors have gradually attracted attention. It generates a high-gravity field through high-speed rotation, significantly enhancing mass transfer and mixing effects, and can achieve efficient chemical reactions 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. By carrying out a Friedel-Crafts reaction between propionyl chloride and propylene under the action of a catalyst, and then carrying out alkali hydrolysis with triethylamine, 4-hexen-3-one is finally obtained. This method uses propionyl chloride as a raw material, there are no difficult-to-treat by-products in the production process, and triethylamine can be recycled and reused, thus significantly reducing the material cost and treatment cost. The production operation is simple, the equipment requirements are few, and the yield is relatively high, which is suitable for the large-scale production of 4-hexen-3-one. However, using triethylamine as an alkali hydrolysis reagent in this method may introduce impurities during the reaction, affecting the purity of the product, and its reusability is relatively low. Summary of the Invention

[0006] To solve the deficiencies in the prior art, the present invention aims to provide a method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high-gravity reactor. This method optimizes the catalyst system and reaction conditions, improves the reaction efficiency and selectivity, while 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 invention objective, the present invention adopts the following technical solutions:

[0008] A method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high-gravity reactor, comprising the following steps:

[0009] Step 1: Add dichloromethane solvent and aluminum trichloride ionic liquid to a storage tank, stir evenly, cool down and keep at a low temperature, then add it to the high-gravity reactor;

[0010] Step 2: Pump propionyl chloride into the high-gravity 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 completed, transfer the reaction solution to a separation kettle for static separation to separate the ionic liquid layer and the dichloromethane material layer, and recycle the ionic liquid layer;

[0013] Step 5: Wash the dichloromethane material layer with an aqueous sodium carbonate solution, discard the water layer after static separation, and repeat the washing;

[0014] Step 6: Transfer the washed dichloromethane material layer to a distillation column, first distill and recover dichloromethane under normal pressure, and then carry out vacuum distillation to collect the 4-hexen-3-one product.

[0015] Preferably, the method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high-gravity 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 a storage tank, stir evenly, lower the temperature of the mixture to 0-5°C, and keep this temperature and add it to the high-gravity reactor;

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

[0018] Step 3: Introduce propylene gas into the high-gravity reactor, control the flow rate at 0.1-1 L / min, and keep the reaction temperature at 0-5°C;

[0019] Step 4: After the reaction is completed, transfer the reaction solution to a separation kettle, let it stand for separation to obtain an ionic liquid layer and a dichloromethane material layer. The ionic liquid layer is recycled for reuse.

[0020] Step 5: Transfer the dichloromethane material layer to a washing device, wash it with an aqueous sodium carbonate solution, stir evenly and then let it stand for separation, discard the aqueous layer, wash the dichloromethane material layer with water again, repeat the above operation, and discard the aqueous layer.

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

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

[0023] The temperature of the atmospheric distillation is 40 - 50 °C.

[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, by weight:

[0027] In a sealed three-necked flask, after replacing the air with nitrogen, stir at a speed of 300 - 500 revolutions per minute, 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 shows a light brown color. After the reaction is completed, cool it to room temperature to obtain the 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 nitrate and water to a stirrer, then add molecular sieve ZSM-5. Place the mixture in a water bath and stir to evaporate, then dry it in an oven, and finally heat-treat it in a muffle furnace to obtain a pretreatment product.

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

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

[0032] S1. Add 5 - 10 parts of rare earth metal nitrate and 100 - 150 parts of water into a stirrer with a stirring speed of 300 - 500 revolutions per minute. Then add 20 - 40 parts of molecular sieve ZSM - 5. Place the mixture in a water bath at 70 - 80 °C and stir to evaporate. Keep stirring for 5 - 10 hours, and then place the mixture in an oven at 80 - 95 °C to dry overnight. Transfer the dried sample to a muffle furnace, heat it at a heating rate of 10 - 20 °C per minute to 400 - 600 °C, and maintain this temperature for 1 - 5 hours to obtain a 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. After mixing, put them into a stirrer, control the stirring speed at 400 - 700 revolutions per minute, stir for 0.5 - 1 hour, add 20 - 40 parts of the pretreated product prepared in step S1, and continue to stir for 1 - 3 hours to obtain a 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 functions of each substance are as follows:

[0037] The rare earth metal nitrate serves as an active component, providing additional active sites, enhancing the activity and selectivity of the catalyst. The rare earth metal has a unique electronic structure, which can more effectively activate reactants during the reaction process and promote the progress of the Friedel - Crafts acylation reaction.

[0038] The molecular sieve ZSM - 5 serves as a carrier, providing a high specific surface area and good thermal stability, enhancing the dispersibility and stability of the catalyst.

[0039] Water serves as a solvent, used to dissolve the rare earth metal nitrate, facilitating the mixing with molecular sieve ZSM - 5.

[0040] The transition metal nitrate serves as an active component, providing additional active sites, enhancing the activity and stability of the catalyst.

[0041] Anhydrous aluminum trichloride serves as the main Lewis acid catalyst, providing acidic centers to promote the progress of the Friedel - Crafts acylation reaction.

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

[0043] In the present invention, various substances through synergistic effects 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, zeolite ZSM-5 provides a high specific surface area and thermal stability, and anhydrous aluminum trichloride, as the main Lewis acid catalyst, promotes the progress of the Friedel-Crafts acylation reaction. The synergistic effects of these components significantly improve the synthesis efficiency of 4-hexen-3-one and the service life of the catalyst.

[0044] Compared with the prior art, it has the following beneficial effects:

[0045] 1) By optimizing the reaction conditions and catalyst system, the present invention realizes the high-yield synthesis of 4-hexen-3-one. Using the method of the present invention, the yield of 4-hexen-3-one is significantly higher than the yield level in the prior art. At the same time, by precisely controlling the reaction conditions, the present 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 the present invention has high activity and good stability. Especially in the preparation of the composite aluminum trichloride ionic liquid, the performance of the catalyst is further enhanced by introducing rare earth metals and transition metals. In addition, the ionic liquid layer can be recycled and reused after the reaction, reducing the amount of catalyst used, lowering the production cost, and at the same time reducing the emission of waste, showing good environmental friendliness.

[0047] 3) By combining the high-efficiency mass transfer and mixing characteristics of a rotating packed bed reactor, the present invention significantly improves the reaction efficiency and stability. The rotating packed bed reactor can achieve efficient Friedel-Crafts acylation reaction at low temperature, reducing energy consumption, while improving the safety and controllability of the reaction. In addition, by optimizing the reaction conditions and catalyst system, the present invention shows a low activity decline rate in multiple recycling uses, further improving the economy and sustainability of the process. Specific Embodiments

[0048] Main sources of substances:

[0049] Zeolite ZSM-5, product number: DZ-3, silica-alumina ratio: 40, Shandong Dengzhuo Chemical Co., Ltd.

[0050] The rest of the raw materials in the examples and comparative examples of the present invention are all commercially available products.

[0051] The design concept of the present invention is to develop an efficient and stable method for preparing 4-hexen-3-one by combining the technical advantages of aluminum trichloride ionic liquid and a high-gravity reactor. By utilizing the high activity and recyclability of the aluminum trichloride ionic liquid, as well as the efficient mass transfer and mixing environment provided by the high-gravity 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. At the same time, by optimizing the composition of the catalyst and the 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 by combining aluminum trichloride ionic liquid with a high-gravity 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 a storage tank, stir evenly, cool the mixed solution to 3°C, and keep this temperature and add it to the high-gravity reactor.

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

[0056] Step 3: Introduce propylene gas into the high-gravity reactor, control the flow rate at 0.8 L / min, and keep the reaction temperature at 3°C.

[0057] Step 4: After the reaction is completed, transfer the reaction solution to a separation kettle, let it stand for separation, separate the ionic liquid layer and the dichloromethane material layer, and recycle the ionic liquid layer.

[0058] Step 5: Transfer the dichloromethane material layer to a washing device, wash it with a 10 wt% aqueous sodium carbonate solution, wash it according to the volume ratio of dichloromethane material layer to aqueous sodium carbonate solution of 1:1, stir evenly and then let it stand for separation, discard the water layer, wash the dichloromethane material layer with water again, repeat the above operation, and discard the water layer.

[0059] Step 6: Transfer the washed dichloromethane material layer to a distillation column, first heat it to 45°C for atmospheric distillation to recover dichloromethane. After the distillation is completed, then carry out vacuum distillation, control 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, 100 parts of triethylamine hydrochloride and 20 parts of anhydrous aluminum chloride were added in sequence with stirring at 400 rpm. The temperature was then raised to 90°C. At the same stirring speed, the reaction was continued until the reaction liquid turned light brown. After the reaction was completed, the flask was cooled to room temperature to obtain a triethylamine hydrochloride-aluminum chloride ionic liquid.

[0062] Example 2

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

[0064] The preparation method of the composite aluminum chloride 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 at a stirring speed of 400 rpm, then add 30 parts of molecular sieve ZSM-5, place the mixture in a water bath at 75°C for stirring and evaporation, continue stirring for 8 hours, and then place the mixture in an oven at 90°C for drying overnight; transfer the dried sample to a muffle furnace, heat to 500°C at a heating rate of 15°C / min, and maintain at this temperature for 3 hours to obtain a pretreated material;

[0066] S2. Weigh 2 parts of chromium nitrate, 4 parts of anhydrous aluminum chloride 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 hour. Add 30 parts of the pretreated material prepared in step S1 and continue stirring for 2 hours to obtain a composite aluminum chloride ionic liquid.

[0067] Example 3

[0068] A method for preparing 4-hexen-3-one using aluminum chloride ionic liquid in combination with a high gravity reactor is the same as that in Example 2, the only difference being the preparation method of the composite aluminum chloride ionic liquid.

[0069] The preparation method of the composite aluminum chloride 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 at a stirring speed of 400 rpm, then add 30 parts of molecular sieve ZSM-5, place the mixture in a water bath at 75°C and stir for evaporation, continue stirring for 8 hours, and then place the mixture in an oven at 90°C and dry overnight; transfer the dried sample to a muffle furnace, heat to 500°C at a heating rate of 15°C / min, and maintain at this temperature for 3 hours to obtain a pretreated material;

[0071] S2. Weigh 2 parts of chromium nitrate, 4 parts of anhydrous aluminum trichloride, and 60 parts of dichloromethane. After mixing, put them into a stirrer, control the stirring speed at 600 revolutions per minute, stir for 0.8 hours, add 30 parts of the pretreatment product prepared in step S1, and continue stirring for 2 hours to obtain the composite aluminum trichloride ionic liquid.

[0072] Example 4

[0073] A method for preparing 4-hexen-3-one by using an aluminum trichloride ionic liquid combined with a rotating packed bed is the same as that in Example 2, and the only difference is the preparation method of the composite aluminum trichloride ionic liquid.

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

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

[0076] S2. Weigh 2 parts of nickel nitrate, 4 parts of anhydrous aluminum trichloride, and 60 parts of dichloromethane. After mixing, put them into a stirrer, control the stirring speed at 600 revolutions per minute, stir for 0.8 hours, add 30 parts of the pretreatment product prepared in step S1, and continue stirring for 2 hours to obtain the composite aluminum trichloride ionic liquid.

[0077] Example 5

[0078] A method for preparing 4-hexen-3-one by using an aluminum trichloride ionic liquid combined with a rotating packed bed is the same as that in Example 2, and the only difference is the preparation method of the composite aluminum trichloride ionic liquid.

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

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

[0081] S2. Weigh 2 parts of cobalt nitrate, 4 parts of anhydrous aluminum trichloride, and 60 parts of dichloromethane. After mixing, put them into a stirrer, control the stirring speed at 600 revolutions per minute, stir for 0.8 hours, add 30 parts of the pretreatment product prepared in step S1, and continue stirring for 2 hours to obtain the composite aluminum trichloride ionic liquid.

[0082] Comparative Example 1

[0083] A method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid combined with a rotating packed bed is the same as that in Example 2, and the only difference is the preparation method of the composite aluminum trichloride ionic liquid.

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

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

[0086] S2. Weigh 2 parts of chromium nitrate, 4 parts of anhydrous aluminum trichloride, and 60 parts of dichloromethane. After mixing, put them into a stirrer, control the stirring speed at 600 revolutions per minute, stir for 0.8 hours, add 30 parts of the pretreatment product prepared in step S1, and continue stirring for 2 hours to obtain the composite aluminum trichloride ionic liquid.

[0087] Comparative Example 2

[0088] A method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid combined with a rotating packed bed is the same as that in Example 2, and the only difference is the preparation method of the composite aluminum trichloride ionic liquid.

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

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

[0091] S2. Weigh 2 parts of copper nitrate, 4 parts of anhydrous aluminum trichloride, and 60 parts of dichloromethane. After mixing, put them into a stirrer, control the stirring speed at 600 revolutions per minute, stir for 0.8 hours, add 30 parts of the pretreatment product prepared in step S1, and continue stirring for 2 hours to obtain a composite aluminum trichloride ionic liquid.

[0092] Test Example 1

[0093] Test the yield of 4-hexen-3-one:

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

[0095] Table 1

[0096] Experimental Scheme 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 catalyst prepared in the examples and comparative examples of the present invention during multiple cycles of use, after each reaction is completed, separate and recover the ionic liquid layer from the reaction system, and then put the recovered ionic liquid back into the same reaction conditions for the next reaction. By recording the conversion rate of the reaction after 10 cycles of use, analyze the change in the activity of the ionic liquid during 10 cycles of use. Generally, if the yield can still be maintained at a relatively high level (such as the yield is not less than 90%) after 10 cycles of reaction, it can be considered that the ionic liquid has good stability and reusability. The test results are shown in Table 2.

[0100] Table 2

[0101] Experimental Scheme Yield (%) Decrease Rate (%) 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] It can be seen from the data in Test Example 1 that the yield of the method for preparing 4-hexen-3-one using the aluminum trichloride ionic liquid combined with a rotating packed bed in Example 2 is the highest, and the stability of the aluminum trichloride ionic liquid catalyst prepared in Example 2 in Test Example 2 is relatively good.

[0103] In the present invention, the aluminum trichloride ionic liquid prepared with cerium nitrate in Example 2 exhibits the highest yield and relatively high stability during the preparation of 4-hexen-3-one. This may be because cerium nitrate can form a more stable composite structure with zeolite ZSM-5 during the preparation process, thereby providing more uniform and highly active catalytic sites in subsequent reactions. In addition, as a rare earth element, cerium has a unique electronic structure and redox properties, which can more effectively activate propylene gas and propionyl chloride during the reaction process, promoting the progress of the Friedel-Crafts acylation reaction. At the same time, it shows a relatively low activity decline rate during multiple recycling uses. In contrast, although lanthanum nitrate and ytterbium nitrate also have certain catalytic properties, they are slightly inferior in terms of activity and stability, which may be related to their electronic structures and the interaction modes with zeolites.

[0104] In the experimental design of the present invention, the aluminum trichloride ionic liquid prepared with chromium nitrate in Example 2 exhibits 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 progress of the Friedel-Crafts acylation reaction. At the same time, the synergistic effect between chromium ions and zeolite ZSM-5 enables the catalyst to maintain relatively stable activity during repeated use, which is manifested as a lower activity decay rate in the stability test. In contrast, although nickel nitrate and copper nitrate can also form composite structures with zeolite ZSM-5, they show slightly weaker catalytic activity and stability, which may be related to the chemical properties of nickel and copper ions and their interaction mechanisms with zeolites.

[0105] In the present invention, the aluminum trichloride ionic liquid prepared with cobalt nitrate in Example 5 exhibits relatively excellent stability when preparing 4-hexen-3-one. The characteristics of cobalt ions make it more stable under the high shear force conditions of the rotating packed bed reactor, reducing catalyst agglomeration and deactivation phenomena. At the same time, the interaction between cobalt ions and zeolite ZSM-5 helps to form more stable active sites, which can maintain high activity during multiple recycling uses, thus showing a lower activity decline rate in the stability test. In contrast, although chromium nitrate has high catalytic performance, its stability during repeated use is slightly lower, which may be related to the stability of chromium ions in a high shear force environment and its interaction mode with zeolites.

Claims

1. A method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high-gravity reactor, characterized in that It includes the following steps: Step 1: Add dichloromethane solvent and aluminum trichloride ionic liquid into a storage tank, stir evenly, cool down and add it to a high gravity reactor while maintaining a low temperature; Step 2: Pump propionyl chloride into the high gravity 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 completed, transfer the reaction solution to a separation kettle for static separation to separate the ionic liquid layer and the dichloromethane material layer, and recycle the ionic liquid layer; Step 5: Wash the dichloromethane material layer with an aqueous sodium carbonate solution, let it stand for separation, discard the water layer, and repeat the washing; Step 6: Transfer the washed dichloromethane material layer to a distillation column, first distill at atmospheric pressure to recover dichloromethane, and then perform vacuum distillation to collect 4-hexen-3-one product; The aluminum trichloride ionic liquid is at least one of triethylamine hydrochloride-aluminum trichloride ionic liquid and composite aluminum trichloride ionic liquid; The preparation method of the composite aluminum trichloride ionic liquid includes the following steps: S1: Add rare earth metal nitrate and water into a stirrer, then add molecular sieve ZSM-5, place the mixture in a water bath for stirring and evaporation, then dry it in an oven, and finally heat-treat it in a muffle furnace to obtain a pretreated product; S2: Mix transition metal nitrate, anhydrous aluminum trichloride and dichloromethane, add the pretreated product, and stir evenly to obtain a composite aluminum trichloride ionic liquid.

2. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid combined with a rotating packed bed reactor according to claim 1, wherein 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 into a storage tank, stir evenly, cool the mixed solution to 0 - 5°C, and add it to a high gravity reactor while maintaining this temperature; Step 2: Prepare propionyl chloride in another storage tank, use a metering pump to pump propionyl chloride into the high gravity reactor at a flow rate of 0.1 - 0.5 L / min. At the same time, control the temperature of the high gravity reactor at 0 - 5°C and the rotation speed at 300 - 800 rpm; Step 3: Introduce propylene gas into the high gravity reactor, control the flow rate at 0.1 - 1 L / min, and maintain the reaction temperature at 0 - 5°C; Step 4: After the reaction is completed, transfer the reaction solution to a separation kettle, let it stand for separation, separate the ionic liquid layer and the dichloromethane material layer, and recycle the ionic liquid layer; Step 5: Transfer the dichloromethane material layer to a washing device, wash it with an aqueous sodium carbonate solution, stir evenly, let it stand for separation, discard the water layer, wash the dichloromethane material layer with water again, repeat the above operation, and discard the water layer; Step 6: Transfer the washed dichloromethane material layer to a distillation column, first heat up for atmospheric distillation to recover dichloromethane. After the distillation is completed, then perform vacuum distillation to collect 4-hexen-3-one product.

3. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high-gravity reactor according to claim 1 or 2, characterized in that, The volume ratio of the dichloromethane material layer to the aqueous sodium carbonate solution is 1:0.5 - 2.

4. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid combined with a rotating packed bed reactor according to claim 1 or 2, characterized in that, The temperature of the atmospheric distillation is 40 - 50°C.

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

6. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high gravity reactor according to claim 1, wherein The preparation method of the triethylamine hydrochloride-aluminum trichloride ionic liquid is as follows, by weight: In a sealed three-necked flask, after replacing the air with nitrogen, 80-120 parts of triethylamine hydrochloride and 10-30 parts of anhydrous aluminum chloride are added in sequence with stirring at a speed of 300-500 rpm. The temperature is then raised to 80-95°C. At the same stirring speed, the reaction is continued until the reaction liquid turns light brown. After the reaction is completed, it is cooled to room temperature to obtain a triethylamine hydrochloride-aluminum chloride ionic liquid.

7. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a rotating packed bed reactor according to claim 1, wherein, The preparation method of the composite aluminum chloride 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 at 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°C, stir and evaporate, continue stirring for 5-10 hours, and then place the mixture in an oven at 80-95°C to dry overnight; The dried sample is transferred to a muffle furnace, heated to 400-600°C at a heating rate of 10-20°C / min, and maintained at this temperature for 1-5 hours to obtain a pretreated product; S2. Weigh 1 to 3 parts of a transition metal nitrate, 2 to 5 parts of anhydrous aluminum chloride, and 50 to 70 parts of dichloromethane, mix them, and put them into a stirrer. Control the stirring speed to 400 to 700 rpm and stir for 0.5 to 1 hour. Add 20 to 40 parts of the pretreated material prepared in step S1 and continue stirring for 1 to 3 hours to obtain a composite aluminum chloride ionic liquid.

8. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid in combination with a high-gravity reactor according to claim 7, wherein The rare earth metal nitrate is at least one of lanthanum nitrate and cerium nitrate.

9. The method for preparing 4-hexen-3-one by using aluminum trichloride ionic liquid combined with a high-gravity reactor according to claim 7, wherein The transition metal nitrate is at least one of nickel nitrate, chromium nitrate and cobalt nitrate.