A method for preparing linear dimers of α-methylstyrene

Abstract

The present invention belongs to the technical field of α-methylstyrene organic synthesis, and in particular relates to a method for preparing α-methylstyrene linear dimer, which comprises the following steps: Select clean and pollution-free coconut shells, wash them and place them in a room temperature condition for drying; Put the dried coconut shells into a carbonization furnace for high-temperature carbonization treatment; Activate the carbonized coconut shell charcoal with steam at high temperature to complete the preparation of the carrier, the preparation of the supported heteropolyacid and the synthesis of AMS linear dimer. The present invention loads the heteropolyacid onto the coconut shell activated carbon with developed pores, good adsorption performance, economy and durability, increases the contact area between the catalyst and the raw materials, improves the catalytic efficiency, facilitates separation from the system, realizes the efficient and circular utilization of resources, and at the same time adopts a segmented drying method in the preparation process, which can effectively maintain the stability of the catalyst structure and provide guarantee for subsequent preparation.

Description

Technical Field

[0001] The present invention relates to the technical field of α-methylstyrene organic synthesis, and specifically to a method for preparing α-methylstyrene linear dimer. Background Art

[0002] α-Methylstyrene (AMS) is one of the by-products in the industrial production of phenol and acetone by the cumene process. As an important chemical product, it is widely used in the fields of synthetic polymers and fragrances. α-Methylstyrene will undergo a polymerization reaction under acidic or heating conditions to form AMS dimers, including AMS linear dimer and AMS cyclic dimer. There are mainly two structures of AMS linear dimer, including 2,4-diphenyl-4-methyl-1-pentene and 2,4-diphenyl-4-methyl-2-pentene, which are colorless or light yellow viscous liquids, soluble in organic solvents such as acetone, benzene and toluene, and insoluble in water. It is widely used in polymer synthesis and processing, lubricating oil modification, etc. The present invention mainly elaborates on a synthesis method of AMS linear dimer.

[0003] The key factor in the synthesis of AMS linear dimer is the selection of the catalyst. Currently, most of the reported literature uses inorganic acids such as sulfuric acid and phosphoric acid, organic acids such as methanesulfonic acid and adipic acid, ionic liquids, heteropolyacids, activated clay, strongly acidic cation exchange resins and other acidic catalysts, all used with solvents, and the catalyst is difficult to recycle. These synthesis methods have problems such as low conversion rate, poor selectivity, complex post-treatment and environmental pollution.

[0004] It should be noted that the above content belongs to the technical cognition scope of the inventor and does not necessarily constitute the prior art. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a method for preparing α-methylstyrene linear dimer, which solves the existing problems.

[0006] To achieve the above object, the present invention provides the following technical solution: A method for preparing α-methylstyrene linear dimer, comprising the following steps:

[0007] Step 1: Preparation of coconut shell activated carbon carrier;

[0008] Select clean and pollution-free coconut shells, wash them and dry them at room temperature. Put the dried coconut shells into a carbonization furnace and carry out high-temperature carbonization treatment at 600 - 900 °C. Activate the carbonized coconut shell charcoal with steam at 800 - 1000 °C to remove small-molecule substances on the carbon surface and form a pore structure. After the activation treatment, carry out a grinding operation, sieve it through a 20 - 40 mesh sieve, place it in a container, take 100 - 500 ml of deionized water and treat it at 80 - 100 °C for 1 - 2 hours, and then dry it in a constant-temperature drying oven at 100 - 130 °C to obtain a coconut shell activated carbon carrier.

[0009] Step Two: Preparation of the supported heteropolyacid catalyst;

[0010] Weigh 100 - 500 ml of solvent and add it to a container. Slowly add 1 - 10 g of heteropolyacid into it and stir it at a rate of 300 - 500 rpm with an external magnetic stirring device until the heteropolyacid is completely dissolved. At the same time, slowly heat it to 40 - 60 °C and control the concentration of the heteropolyacid aqueous solution to be 0.1% - 20%. Weigh 500 - 600 g of coconut shell activated carbon and add it to another container. Slowly add the heteropolyacid aqueous solution, stir, filter the precipitate, and carry out segmented drying in an electrothermal blast drying oven: first dry it at 40 - 60 °C for 1 - 1.5 hours, then raise the temperature to 100 °C and thoroughly dry it. Finally, calcine the dried sample in a muffle furnace at 200 - 400 °C for 1 - 6 hours to obtain the supported heteropolyacid catalyst.

[0011] Step Three: Synthesis of α-methylstyrene linear dimer;

[0012] Add a certain amount of α-methylstyrene to a reaction kettle equipped with a thermometer, a condenser and a stirrer and stir it. Then slowly add the supported heteropolyacid catalyst with a mass ratio of 5% - 30% to the system. Raise the water bath temperature to 25 - 60 °C and stir and react for 3 - 24 hours. After the reaction is completed, cool the reaction solution to room temperature and filter out the catalyst. Carry out vacuum distillation on the reaction solution to obtain α-methylstyrene linear dimer.

[0013] In some of the embodiments, the solvent described in Step Two is one of deionized water and absolute ethanol, and the heteropolyacid is phosphotungstic acid.

[0014] Compared with the prior art, the present invention provides a method for preparing α-methylstyrene linear dimer, which has the following beneficial effects:

[0015] The method for preparing α-methylstyrene linear dimer loads heteropolyacid onto coconut shell activated carbon with well-developed pores, good adsorption performance, economy and durability, increases the contact area between the catalyst and the raw materials, improves the catalytic efficiency, is convenient for separation from the system, realizes the efficient and cyclic utilization of resources, conforms to the concept of green chemical industry, has a wide application prospect, and at the same time adopts a segmented drying method during the preparation process, which can effectively maintain the stability of the catalyst structure and provide guarantee for subsequent preparation. Detailed implementation mode

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] It should be understood that the step numbers used in the text are only for convenient description and do not limit the execution order of the steps.

[0018] It should be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0019] The terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0020] The term "and / or" refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0021] Example 1:

[0022] A method for preparing α-methylstyrene linear dimer includes the following steps:

[0023] Step 1: Select clean and pollution-free coconut shells, wash them and dry them at room temperature.

[0024] Step 2: Put the dried coconut shells into a carbonization furnace for high-temperature carbonization treatment.

[0025] The temperature of the high-temperature carbonization treatment is specifically 650 degrees Celsius.

[0026] Step 3: Activate the carbonized coconut shell charcoal with steam at high temperature.

[0027] During the activation process, the temperature needs to be controlled at 800 degrees Celsius to remove small molecule substances on the carbon surface, thereby forming voids;

[0028] Step Four: After the activation treatment, perform a grinding operation, place it in a container, take a certain amount of deionized water and treat it at a specific temperature, and then place it in a constant temperature drying oven to dry, obtaining a coconut shell activated carbon carrier;

[0029] After the grinding operation, sieve through a 20-mesh sieve. The treatment temperature needs to be controlled at 100 degrees Celsius, and the time is controlled at 1 hour. The internal temperature of the constant temperature drying oven is controlled at 100 degrees Celsius;

[0030] Step Five: Weigh 300 g of deionized water and add it to a container. Slowly add 3 g of phosphotungstic acid to it and stir with an external magnetic stirring device until the phosphotungstic acid is completely dissolved. At the same time, use a pH meter to monitor the acidity and alkalinity of the solution to complete the preparation of the phosphotungstic acid aqueous solution. During this process, slowly heat it;

[0031] The stirring rate of the external magnetic stirring device is 350 rpm, and the temperature is slowly increased to 45 degrees Celsius during the stirring process;

[0032] Step Six: Weigh 30 g of coconut shell activated carbon and add it to another container. Slowly add the phosphotungstic acid aqueous solution, stir for 8 h, then precipitate and filter. Dry it in a segmented manner in an electrothermal blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported phosphotungstic acid catalyst;

[0033] The specific steps of the segmented drying are as follows: Dry at 40 degrees Celsius for 1.5 hours, then raise the temperature to 100 degrees Celsius for thorough drying operation. Place the dried sample in a muffle furnace for calcination, and the internal temperature needs to be controlled at 300 degrees Celsius for a duration of 2 hours.

[0034] Example 2:

[0035] A method for preparing α-methylstyrene linear dimer, comprising the following steps:

[0036] Step One: Select clean and pollution-free coconut shells, wash them and place them at room temperature for drying;

[0037] Step Two: Put the dried coconut shells into a carbonization furnace for high-temperature carbonization treatment;

[0038] The specific temperature of the high-temperature carbonization treatment is 650 degrees Celsius;

[0039] Step Three: Activate the carbonized coconut shell charcoal with steam at high temperature;

[0040] During the activation process, the temperature needs to be controlled at 800 degrees Celsius to remove small molecule substances on the carbon surface and form pores accordingly.

[0041] Step 4: After the activation treatment, perform a grinding operation, place it in a container, take a certain amount of deionized water to treat at a specific temperature, and then place it in a constant temperature drying oven to dry, obtaining a coconut shell activated carbon carrier.

[0042] After the grinding operation, sieve through a 20-mesh sieve. The treatment temperature needs to be controlled at 100 degrees Celsius, and the time is controlled at 1 hour. The internal temperature of the constant temperature drying oven is controlled at 100 degrees Celsius.

[0043] Step 5: Weigh 100 g of deionized water and add it to a container. Slowly add 1 g of silicotungstic acid to it, stir with an external magnetic stirring device until the silicotungstic acid is completely dissolved. At the same time, use a pH meter to monitor the acidity and alkalinity of the solution to complete the preparation of the silicotungstic acid aqueous solution. During this process, perform slow heating.

[0044] The stirring rate of the external magnetic stirring device is 300 rpm, and the temperature is slowly increased to 45 degrees Celsius during the stirring process.

[0045] Step 6: Weigh 10 g of coconut shell activated carbon and add it to another container. Slowly add the silicotungstic acid aqueous solution, stir for 8 h, then precipitate and filter. Perform segmented drying in an electrothermal blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported silicotungstic acid catalyst.

[0046] The specific steps of segmented drying are as follows: Dry at 45 degrees Celsius for 1.5 hours, then raise the temperature to 80 degrees Celsius for thorough drying. Place the dried sample in a muffle furnace for calcination, and the internal temperature needs to be controlled at 350 degrees Celsius for 3 hours.

[0047] Example 3:

[0048] A method for preparing α-methylstyrene linear dimer, comprising the following steps:

[0049] Step 1: Select clean and pollution-free coconut shells, wash them and place them to dry at room temperature.

[0050] Step 2: Put the dried coconut shells into a carbonization furnace for high-temperature carbonization treatment.

[0051] The specific temperature of the high-temperature carbonization treatment is 650 degrees Celsius.

[0052] Step 3: Activate the carbonized coconut shell carbon with steam at high temperature.

[0053] During the activation process, the temperature needs to be controlled at 800 degrees Celsius to remove small molecule substances on the carbon surface and form pores accordingly.

[0054] Step 4: After the activation treatment, perform a grinding operation, place it in a container, take a certain amount of deionized water and treat it at a specific temperature, and then dry it in a constant temperature drying oven to obtain a coconut shell activated carbon carrier;

[0055] After the grinding operation, sieve it through a 20-mesh sieve. The treatment temperature needs to be controlled at 100 °C, and the time is controlled at 1 hour. The internal temperature of the constant temperature drying oven is controlled at 100 °C;

[0056] Step 5: Weigh 200 g of anhydrous ethanol and add it to a container. Slowly add 2 g of phosphomolybdic acid to it, stir it with an external magnetic stirring device until the phosphomolybdic acid is completely dissolved, and at the same time use a pH meter to monitor the acidity and alkalinity of the solution to complete the preparation of the phosphomolybdic acid aqueous solution. During this process, slowly heat it;

[0057] The stirring rate of the external magnetic stirring device is 350 rpm, and the temperature is slowly increased to 45 °C during the stirring process;

[0058] Step 6: Weigh 20 g of coconut shell activated carbon and add it to another container. Slowly add the phosphomolybdic acid aqueous solution, stir for 12 h, then filter the precipitate by suction, perform segmented drying in an electrothermal blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported phosphomolybdic acid catalyst;

[0059] The specific steps of segmented drying are as follows: dry at 45 °C for 1.5 hours, then raise the temperature to 60 °C for thorough drying operation. The dried sample is placed in a muffle furnace for calcination, and the internal temperature needs to be controlled at 200 °C for a duration of 2 hours.

[0060] Example 4:

[0061] A method for preparing α-methylstyrene linear dimer, comprising the following steps:

[0062] Step 1: Select clean and pollution-free coconut shells, wash them and dry them at room temperature;

[0063] Step 2: Put the dried coconut shells into a carbonization furnace for high-temperature carbonization treatment;

[0064] The specific temperature of the high-temperature carbonization treatment is 650 °C;

[0065] Step 3: Activate the carbonized coconut shell charcoal with steam at high temperature;

[0066] During the activation treatment, the temperature needs to be controlled at 800 °C to remove small molecular substances on the carbon surface to form pores;

[0067] Step 4: After the activation treatment, perform a grinding operation, place it in a container, take a certain amount of deionized water to treat it at a specific temperature, and then dry it in a constant temperature drying oven to obtain a coconut shell activated carbon carrier;

[0068] After the grinding operation, sieve it through a 20-mesh sieve. The treatment temperature needs to be controlled at 100 °C, and the time is controlled at 1 hour. The internal temperature of the constant temperature drying oven is controlled at 100 °C;

[0069] Step 5: Weigh 100 g of deionized water and add it to a container. Slowly add 1 g of silicomolybdic acid to it, stir it with an external magnetic stirring device until the silicomolybdic acid is completely dissolved. At the same time, use a pH meter to monitor the acidity and alkalinity of the solution to complete the preparation of the silicomolybdic acid aqueous solution. During this process, slowly heat it;

[0070] The stirring rate of the external magnetic stirring device is 350 rpm, and the temperature is slowly increased to 45 °C during the stirring process;

[0071] Step 6: Weigh 10 g of coconut shell activated carbon and add it to another container. Slowly add the silicomolybdic acid aqueous solution, stir for 5 h, then filter the precipitate by suction, perform segmented drying in an electrothermal blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported heteropolyacid catalyst;

[0072] The specific steps of segmented drying are as follows: dry it at 45 °C for 1.5 hours, then raise the temperature to 100 °C for thorough drying operation. Place the dried sample in a muffle furnace for calcination, and the internal temperature needs to be controlled at 350 °C for 3 hours.

[0073] Experimental group 1:

[0074] Add a certain amount of AMS to a four-necked jacketed reactor equipped with a thermometer, a condenser, and a stirrer, start stirring, and then add 15% of the supported heteropolyacid catalysts in Examples 1-4 to the system. Raise the water bath temperature to 40 °C and stir and react for 12 hours;

[0075] Verify the catalytic activities of the above four groups of supported heteropolyacid catalysts. Select the detection methods for the conversion rate of AMS and the selectivities of 2,4-diphenyl-4-methyl-1-pentene and 2,4-diphenyl-4-methyl-2-pentene. The experimental measurement results are shown in Table 1:

[0076] Table 1 Experimental measurement results

[0077]

[0078] Experimental group 2:

[0079] At a reaction temperature of 40 °C and a reaction time of 12 h, the addition amounts of the supported heteropolyacid in Example 1 were tested. The addition amounts of the catalyst were 1%, 5%, 10%, 15%, 20%, and 25%. The experimental results are shown in Table 2:

[0080] Table 2 Experimental determination results

[0081]

[0082] Experimental group 3:

[0083] The recycled catalyst was used to complete the catalyst recycling experiment under the conditions of experimental group 1. The experimental results are shown in Table 3:

[0084] Table 3 Experimental determination results

[0085]

[0086] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and reference can be made to the corresponding part of the method embodiment for the relevant content.

[0087] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing linear dimers of α-methylstyrene, characterized in that, It includes the following steps: Step 1: Preparation of coconut shell activated carbon support; Select clean and pollution-free coconut shells, wash them and dry them at room temperature; put the dried coconut shells into a carbonization furnace and carry out high-temperature carbonization treatment at 600-900 °C; carry out activation treatment on the carbonized coconut shell charcoal with steam at 800-1000 °C to remove small molecule substances on the carbon surface and form a pore structure; carry out grinding operation after activation treatment, sieve with a 20-40 mesh sieve, place it in a container, take 100-500 ml of deionized water and treat it at 80-100 °C for 1-2 hours, and then dry it in a constant temperature drying oven at 100-130 °C to obtain the coconut shell activated carbon support; Step 2: Preparation of supported heteropolyacid catalyst; Weigh 100-500 ml of solvent and add it to a container, slowly add 1-10 g of heteropolyacid into it, stir with an external magnetic stirring device at a rate of 300-500 rpm until the heteropolyacid is completely dissolved, and at the same time slowly heat it to 40-60 °C to control the concentration of the heteropolyacid aqueous solution to be 0.1%-20%; weigh 500-600 g of coconut shell activated carbon and add it to another container, slowly add the heteropolyacid aqueous solution, stir, precipitate and filter, and carry out segmented drying in an electric heating blast drying oven: first dry it at 40-60 °C for 1-1.5 hours, then raise the temperature to 100 °C to completely dry it, and finally calcine the dried sample in a muffle furnace at 200-400 °C for 1-6 hours to obtain the supported heteropolyacid catalyst; Step 3: Synthesis of α-methylstyrene linear dimer; Add a certain amount of α-methylstyrene to a reaction kettle equipped with a thermometer, a condenser and a stirrer and stir, and then slowly add a supported heteropolyacid catalyst with a mass ratio of 5%-30% to the system; raise the water bath temperature to 25-60 °C, stir and react for 3-24 hours, after the reaction is completed, cool the reaction solution to room temperature, and filter out the catalyst; carry out vacuum rectification on the reaction solution to obtain α-methylstyrene linear dimer.

2. The method for preparing α-methylstyrene linear dimer according to claim 1, wherein: The solvent described in Step 2 is one of deionized water and absolute ethanol, and the heteropolyacid is phosphotungstic acid.

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