Method for preparing alpha-methylstyrene linear dimer

Abstract

The invention belongs to the technical field of organic synthesis of alpha-methylstyrene, and particularly relates to a method for preparing an alpha-methylstyrene linear dimer, which comprises the following steps: selecting clean and pollution-free coconut shell, washing, and drying at room temperature; putting the dried coconut shells into a carbonization furnace, and carrying out high-temperature carbonization treatment; and carrying out activating treatment on the carbonized coconut shell charcoal through steam at a high temperature so as to complete the preparation of the carrier, the preparation of the supported heteropolyacid and the synthesis of the AMS linear dimer. According to the invention, heteropolyacid is loaded on coconut shell activated carbon with developed pores, good adsorption performance, economy and durability, the contact area of the catalyst and raw materials is increased, the catalytic efficiency is improved, separation from a system is facilitated, and efficient and cyclic utilization of resources is realized; the stability of the catalyst structure can be effectively maintained, and a guarantee is provided for subsequent preparation.

Description

Technical Field

[0001] The invention relates to the technical field of alpha-methylstyrene organic synthesis, in particular to a method for preparing alpha-methylstyrene linear dimer. Background Art

[0002] α-Methylstyrene (AMS) is one of the byproducts of the industrial production of phenol and acetone using the cumene method. As an important chemical product, it is widely used in the fields of synthetic polymer materials and fragrances. α-Methylstyrene undergoes polymerization reaction under acidic or heating conditions to generate AMS dimers, including AMS linear dimers and AMS cyclic dimers. AMS linear dimers mainly have two structures, 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, lubricant modification, etc. The present invention mainly describes a method for synthesizing AMS linear dimers.

[0003] The key factor in the synthesis of AMS linear dimers is the selection of catalysts. Currently, most of the literature reports the use of inorganic acids such as sulfuric acid and phosphoric acid, organic acids such as methanesulfonic acid and adipic acid, ionic liquids, heteropoly acids, activated clay, strong acid cation exchange resins and other acidic catalysts, all of which are used in combination with solvents, and the catalysts are difficult to recycle. These synthesis methods have problems such as low conversion rate, poor selectivity, complex post-processing and environmental pollution.

[0004] It should be noted that the above contents belong to the technical knowledge of the inventor and do not necessarily constitute prior art. Summary of the invention

[0005] In view of 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: Step 1: Select clean and uncontaminated coconut shells, wash them and dry them at room temperature; Step 2: Put the dried coconut shell into the carbonization furnace for high-temperature carbonization treatment; Step 3: Activate the carbonized coconut shell charcoal by steam at high temperature; Step 4: After the activation treatment, the coconut shell activated carbon carrier is obtained by grinding the coconut shell activated carbon carrier, placing the coconut shell activated carbon carrier in a container, taking a certain amount of deionized water and treating the coconut shell activated carbon carrier at a specific temperature, and then drying the coconut shell activated carbon carrier in a constant temperature drying oven. Step 5: Weigh an appropriate amount of solvent and add it into a container, slowly add a certain amount of heteropoly acid thereto, stir by an external magnetic stirring device until the heteropoly acid is completely dissolved, and use a pH meter to monitor the pH of the solution to complete the preparation of the heteropoly acid aqueous solution, and slowly heat it during this process; Step 6: Weigh a certain amount of coconut shell activated carbon and add it to another container, slowly add the heteropoly acid aqueous solution, stir and then filter the precipitate, dry it in an electric blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported heteropoly acid catalyst; Step 7: Add a certain amount of α-methylstyrene into the reaction kettle and stir, then slowly add 5%-30% of the supported heteropoly acid catalyst into the system; Step 8: Raise the water bath temperature while stirring. After the stirring is completed, cool the reaction solution to room temperature and filter out the catalyst. Step nine: distill the reaction solution under reduced pressure to obtain the product.

[0007] In some of the embodiments, the high temperature carbonization treatment temperature needs to be controlled at 600-900 degrees Celsius.

[0008] In some of the embodiments, the temperature during the activation treatment needs to be controlled at 800-1000 degrees Celsius to remove small molecules on the surface of the carbon, thereby forming pores.

[0009] In some of the embodiments, after the grinding operation is completed, a 20-40 mesh sieve needs to be used for screening, the processing temperature needs to be controlled at 80-100 degrees Celsius, and the time is controlled at 1-2 hours, and the internal temperature of the constant temperature drying oven is controlled at 100-130 degrees Celsius.

[0010] In some of the embodiments, the solvent is selected from one of deionized water and anhydrous ethanol, the heteropolyacid is selected from one of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid and silicomolybdic acid, the stirring rate of the external magnetic stirring equipment needs to be controlled at 300-500rpm, and the temperature is slowly increased to 40-60 degrees Celsius during the stirring process, and the concentration of the prepared heteropolyacid aqueous solution is controlled at 0.1%-20%.

[0011] In some of the embodiments, the specific steps of the segmented drying are: drying at 40-60 degrees Celsius for 1-1.5 hours, then raising the temperature to 100 degrees Celsius for thorough drying, and the dried sample is calcined in a muffle furnace, the internal temperature of which needs to be controlled at 200-400 degrees Celsius for 1-6 hours.

[0012] In some of the embodiments, the reactor is equipped with a thermometer, a condenser and a stirrer.

[0013] In some embodiments, the water bath temperature needs to be raised to 25-60 degrees Celsius, and the stirring reaction time is 3-24 hours.

[0014] Compared with the prior art, the present invention provides a method for preparing α-methylstyrene linear dimer, which has the following beneficial effects: The method for preparing linear dimer of alpha-methylstyrene loads heteropoly acid onto coconut shell activated carbon which has developed pores, good adsorption performance, and is economical and durable, thereby increasing the contact area between the catalyst and the raw material, improving the catalytic efficiency, facilitating separation from the system, achieving efficient and cyclic utilization of resources, conforming to the concept of green chemical industry, and having broad application prospects. Meanwhile, a segmented drying method is adopted in the preparation process, which can effectively maintain the stability of the catalyst structure and provide guarantee for subsequent preparation. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] It should be understood that the step numbers used in this article are only for the convenience of description and are not intended to limit the order in which the steps are executed.

[0017] It should be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0018] The terms “include” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0019] The term "and / or" means and includes any and all possible combinations of one or more of the associated listed items.

[0020] Embodiment 1: A method for preparing alpha-methylstyrene linear dimer comprises the following steps: Step 1: Select clean and uncontaminated coconut shells, wash them and dry them at room temperature; Step 2: Put the dried coconut shell into the carbonization furnace for high-temperature carbonization treatment; The high temperature carbonization treatment temperature is specifically 650 degrees Celsius; Step 3: Activate the carbonized coconut shell charcoal by steam at high temperature; The temperature during the activation process needs to be controlled at 800 degrees Celsius to remove small molecules on the surface of the carbon, thereby forming voids; Step 4: After the activation treatment, the coconut shell activated carbon carrier is obtained by grinding the coconut shell activated carbon carrier, placing the coconut shell activated carbon carrier in a container, taking a certain amount of deionized water and treating the coconut shell activated carbon carrier at a specific temperature, and then drying the coconut shell activated carbon carrier in a constant temperature drying oven. After the grinding operation is completed, it is sieved through a 20-mesh sieve. The processing temperature needs to be controlled at 100 degrees Celsius, and the time is controlled within 1 hour. The temperature inside the constant temperature drying oven is controlled at 100 degrees Celsius; Step 5: Weigh 300g of deionized water into a container, slowly add 3g of phosphotungstic acid thereto, stir with an external magnetic stirring device until the phosphotungstic acid is completely dissolved, and use a pH meter to monitor the pH of the solution to complete the preparation of the phosphotungstic acid aqueous solution, and slowly heat it during this process; The stirring rate of the external magnetic stirring device was 350 rpm, and the temperature was slowly increased to 45 degrees Celsius during the stirring process; Step 6: Weigh 30g of coconut shell activated carbon and add it to another container, slowly add phosphotungstic acid aqueous solution, stir for 8h, filter the precipitate, dry it in an electric blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported phosphotungstic acid catalyst; The specific steps of segmented drying are: drying at 40 degrees Celsius for 1.5 hours, then raising the temperature to 100 degrees Celsius for thorough drying, and calcining the dried sample in a muffle furnace, the internal temperature of which needs to be controlled at 300 degrees Celsius for 2 hours.

[0021] Embodiment 2: A method for preparing alpha-methylstyrene linear dimer comprises the following steps: Step 1: Select clean and uncontaminated coconut shells, wash them and dry them at room temperature; Step 2: Put the dried coconut shell into the carbonization furnace for high-temperature carbonization treatment; The high temperature carbonization treatment temperature is specifically 650 degrees Celsius; Step 3: Activate the carbonized coconut shell charcoal by steam at high temperature; The temperature during the activation process needs to be controlled at 800 degrees Celsius to remove small molecules on the surface of the carbon to form pores; Step 4: After the activation treatment, the coconut shell activated carbon carrier is obtained by grinding the coconut shell activated carbon carrier, placing the coconut shell activated carbon carrier in a container, taking a certain amount of deionized water and treating the coconut shell activated carbon carrier at a specific temperature, and then drying the coconut shell activated carbon carrier in a constant temperature drying oven. After the grinding operation is completed, it is sieved through a 20-mesh sieve. The processing temperature needs to be controlled at 100 degrees Celsius, and the time is controlled within 1 hour. The temperature inside the constant temperature drying oven is controlled at 100 degrees Celsius; Step 5: Weigh 100g of deionized water and add it into a container, slowly add 1g of silicotungstic acid into it, stir it with an external magnetic stirring device until the silicotungstic acid is completely dissolved, and use a pH meter to monitor the pH of the solution to complete the preparation of the silicotungstic acid aqueous solution, and slowly heat it during this process; The stirring rate of the external magnetic stirring device was 300 rpm, and the temperature was slowly increased to 45 degrees Celsius during the stirring process; Step 6: Weigh 10g of coconut shell activated carbon and add it to another container, slowly add silicotungstic acid aqueous solution, stir for 8h, filter the precipitate, dry it in an electric blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported silicotungstic acid catalyst; The specific steps of segmented drying are: drying at 45 degrees Celsius for 1.5 hours, then raising the temperature to 80 degrees Celsius for thorough drying, and calcining the dried sample in a muffle furnace, the internal temperature of which needs to be controlled at 350 degrees Celsius for 3 hours.

[0022] Embodiment 3: A method for preparing alpha-methylstyrene linear dimer comprises the following steps: Step 1: Select clean and uncontaminated coconut shells, wash them and dry them at room temperature; Step 2: Put the dried coconut shell into the carbonization furnace for high-temperature carbonization treatment; The high temperature carbonization treatment temperature is specifically 650 degrees Celsius; Step 3: Activate the carbonized coconut shell charcoal by steam at high temperature; The temperature during the activation process needs to be controlled at 800 degrees Celsius to remove small molecules on the surface of the carbon to form pores; Step 4: After the activation treatment, the coconut shell activated carbon carrier is obtained by grinding the coconut shell activated carbon carrier, placing the coconut shell activated carbon carrier in a container, taking a certain amount of deionized water and treating the coconut shell activated carbon carrier at a specific temperature, and then drying the coconut shell activated carbon carrier in a constant temperature drying oven. After the grinding operation is completed, it is sieved through a 20-mesh sieve. The processing temperature needs to be controlled at 100 degrees Celsius, and the time is controlled within 1 hour. The temperature inside the constant temperature drying oven is controlled at 100 degrees Celsius; Step 5: Weigh 200g of anhydrous ethanol and add it into a container, slowly add 2g of phosphomolybdic acid thereto, stir by an external magnetic stirring device until the phosphomolybdic acid is completely dissolved, and use a pH meter to monitor the pH of the solution to complete the preparation of the phosphomolybdic acid aqueous solution, and slowly heat it during this process; The stirring rate of the external magnetic stirring device was 350 rpm, and the temperature was slowly increased to 45 degrees Celsius during the stirring process; Step 6: Weigh 20 g of coconut shell activated carbon and add it to another container, slowly add phosphomolybdic acid aqueous solution, stir for 12 hours, filter the precipitate, dry it in an electric blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported phosphomolybdic acid catalyst; The specific steps of segmented drying are: drying at 45 degrees Celsius for 1.5 hours, then raising the temperature to 60 degrees Celsius for thorough drying, and calcining the dried sample in a muffle furnace, the internal temperature of which needs to be controlled at 200 degrees Celsius for 2 hours.

[0023] Embodiment 4: A method for preparing alpha-methylstyrene linear dimer comprises the following steps: Step 1: Select clean and uncontaminated coconut shells, wash them and dry them at room temperature; Step 2: Put the dried coconut shell into the carbonization furnace for high-temperature carbonization treatment; The high temperature carbonization treatment temperature is specifically 650 degrees Celsius; Step 3: Activate the carbonized coconut shell charcoal by steam at high temperature; The temperature during the activation process needs to be controlled at 800 degrees Celsius to remove small molecules on the surface of the carbon to form pores; Step 4: After the activation treatment, the coconut shell activated carbon carrier is obtained by grinding the coconut shell activated carbon carrier, placing the coconut shell activated carbon carrier in a container, taking a certain amount of deionized water and treating the coconut shell activated carbon carrier at a specific temperature, and then drying the coconut shell activated carbon carrier in a constant temperature drying oven. After the grinding operation is completed, it is sieved through a 20-mesh sieve. The processing temperature needs to be controlled at 100 degrees Celsius, and the time is controlled within 1 hour. The temperature inside the constant temperature drying oven is controlled at 100 degrees Celsius; Step 5: Weigh 100g of deionized water into a container, slowly add 1g of silicomolybdic acid thereto, stir with an external magnetic stirring device until the silicomolybdic acid is completely dissolved, and use a pH meter to monitor the pH of the solution to complete the preparation of the silicomolybdic acid aqueous solution, and slowly heat it during this process; The stirring rate of the external magnetic stirring device was 350 rpm, and the temperature was slowly increased to 45 degrees Celsius during the stirring process; Step 6: Weigh 10 g of coconut shell activated carbon and add it to another container, slowly add silicomolybdic acid aqueous solution, stir for 5 hours, filter the precipitate, dry it in an electric blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported heteropolyacid catalyst; The specific steps of segmented drying are: drying at 45 degrees Celsius for 1.5 hours, then raising the temperature to 100 degrees Celsius for thorough drying, and calcining the dried sample in a muffle furnace, the internal temperature of which needs to be controlled at 350 degrees Celsius for 3 hours.

[0024] Experimental Group 1: A certain amount of AMS was added to a four-mouth jacketed reactor equipped with a thermometer, a condenser, and a stirrer, and stirring was started. Then, 15% of the supported heteropolyacid catalysts in Examples 1-4 were added to the system, and the water bath temperature was raised to 40 degrees Celsius, and the reaction was stirred for 12 hours; The catalytic activities of the above four groups of supported heteropolyacid catalysts were verified by using the detection methods of AMS conversion rate and 2,4-diphenyl-4-methyl-1-pentene selectivity and 2,4-diphenyl-4-methyl-2-pentene selectivity. The experimental results are shown in Table 1: Table 1 Experimental results

[0025] Experimental Group 2: At a reaction temperature of 40° C. and a reaction time of 12 h, the addition amount of the supported heteropoly acid in Example 1 was tested, and the addition amount of the catalyst was 1%, 5%, 10%, 15%, 20%, and 25%. The experimental results are shown in Table 2: Table 2 Experimental results

[0026] Experimental Group 3: The catalyst recovered by filtration was subjected to the catalyst recycling experiment under the conditions of experimental group 1. The experimental results are shown in Table 3: Table 3 Experimental results

[0027] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and 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 the relevant parts can be referred to the partial description of the method embodiment.

[0028] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, 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 α-methylstyrene linear dimer, characterized in that: The steps include: Step 1: Select clean and uncontaminated coconut shells, wash them and dry them at room temperature; Step 2: Put the dried coconut shell into the carbonization furnace for high-temperature carbonization treatment; Step 3: Activate the carbonized coconut shell charcoal by steam at high temperature; Step 4: After activation, grind the mixture, place it in a container, take 100-500 ml of deionized water and treat it at 40-60°C, then place it in a constant temperature drying oven for drying to obtain a coconut shell activated carbon carrier; Step 5: Weigh 100-500 ml of solvent into a container, slowly add 1-10 g of heteropoly acid thereto, stir with an external magnetic stirring device until the heteropoly acid is completely dissolved, and use a pH meter to monitor the pH of the solution to complete the preparation of the heteropoly acid aqueous solution, and slowly heat during this process; Step 6: Weigh 500-600g of coconut shell activated carbon into another container, slowly add the heteropoly acid aqueous solution, stir, precipitate and filter, dry in an electric blast drying oven, and then calcine the dried sample in a muffle furnace to obtain a supported heteropoly acid catalyst; Step 7: Add a certain amount of α-methylstyrene into the reaction kettle and stir, then slowly add 5%-30% of the supported heteropoly acid catalyst into the system; Step 8: Raise the water bath temperature while stirring. After the stirring is completed, cool the reaction solution to room temperature and filter out the catalyst. Step nine: distill the reaction solution under reduced pressure to obtain the product.

2. A method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: The high temperature carbonization treatment temperature in step 2 needs to be controlled at 600-900 degrees Celsius.

3. A method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: During the activation treatment process described in step 3, the temperature needs to be controlled at 800-1000 degrees Celsius to remove small molecules on the surface of the carbon, thereby forming voids.

4. A method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: After the grinding operation in step 4 is completed, a 20-40 mesh sieve needs to be selected for sieving, the processing temperature needs to be controlled at 80-100 degrees Celsius, and the time is controlled at 1-2 hours, and the internal temperature of the constant temperature drying oven is controlled at 100-130 degrees Celsius.

5. The method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: In step 5, the solvent is selected from one of deionized water and anhydrous ethanol, the heteropoly acid is selected from one of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid and silicomolybdic acid, the stirring rate of the external magnetic stirring equipment needs to be controlled at 300-500rpm, and the temperature is slowly increased to 40-60 degrees Celsius during the stirring process, and the concentration of the prepared heteropoly acid aqueous solution is controlled at 0.1%-20%.

6. A method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: The specific steps of the segmented drying described in step six are: drying at 40-60 degrees Celsius for 1-1.5 hours, then raising the temperature to 100 degrees Celsius for thorough drying. The dried sample is placed in a muffle furnace for calcination, and the internal temperature needs to be controlled at 200-400 degrees Celsius for 1-6 hours.

7. A method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: The reactor described in step seven is equipped with a thermometer, a condenser and a stirrer.

8. A method for preparing α-methylstyrene linear dimer according to claim 1, characterized in that: In step eight, the water bath temperature needs to be raised to 25-60 degrees Celsius, and the stirring reaction time is 3-24 hours.

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