Hydrophobic heterogeneous polymerization ionic liquid catalyst as well as preparation method and application thereof
By preparing a hydrophobic heterogeneous polymeric ionic liquid catalyst, the problems of catalyst corrosion on equipment and difficulty in reusing were solved, and the efficient and stable synthesis of methacrolein from formaldehyde and propionaldehyde was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEBEI UNIV OF SCI & TECH
- Filing Date
- 2024-11-18
- Publication Date
- 2026-05-19
AI Technical Summary
Existing catalysts for the preparation of methacrolein from formaldehyde and propionaldehyde suffer from equipment corrosion problems, are difficult to reuse, have unstable catalytic performance, and require harsh reaction conditions.
The hydrophobic heterogeneous polymeric ionic liquid catalyst is used to form active secondary amine groups through the preparation process, avoiding equipment corrosion. It also forms a solid catalyst through a multi-step reaction, which is easy to separate and recycle.
The method achieves highly efficient catalytic synthesis of methacrolein from formaldehyde and propionaldehyde. The catalyst exhibits good stability, can be recycled, and reduces costs.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention relates to the chemical industry and discloses a hydrophobic heterogeneous polymerization ionic liquid catalyst, its preparation method and application, wherein an active secondary amine group is formed during the catalyst preparation process and is not easily lost. Background Technology
[0002] Methacrolein, an important chemical raw material, can be oxidized and esterified to obtain methacrylic acid (MAA) and methyl methacrylate (MMA). MMA is commonly used as a monomer in the polymerization of polymethyl methacrylate (PMMA), which is known as "plexiglass" due to its excellent transparency (light transmittance above 90%) and stability. It also possesses advantages such as ease of processing and dyeing, making it widely used in construction, aerospace, and chemical industries. Therefore, the production of methacrolein is of great importance. CN101074192A describes a method for preparing methacrolein by adding 37% hydrochloric acid to diethylamine to prepare a diethylamine hydrochloride solution with a pH of 5-8, achieving a conversion rate of 96.9%. However, this catalyst is homogeneous and cannot be reused, and the hydrochloric acid is corrosive to equipment. CN101316809A discloses a method for preparing unsaturated aldehydes, using secondary amines and protic acids with 4-20 carbon atoms or their salts as catalysts for the intermolecular condensation reaction of aldehyde compounds. However, this catalyst is homogeneous and difficult to separate and recover. Liu et al. copolymerized divinylbenzene with sodium p-styrene sulfonate under solvothermal conditions. By adjusting the content of hydrophilic and hydrophobic groups during the reaction, they obtained a series of mesoporous polymer solid acid catalysts with different hydrophobic group contents. The hydrophobic effect was determined by measuring the contact angle. These catalysts were applied to reactions involving cyclohexyl acetate and 1-butyl acetate, with selectivity exceeding 95% in all cases. Luo et al. prepared a heterogeneous catalyst using trans-4-hydroxy-L-proline and acryloyl chloride. Under this catalyst, the conversion rate of propionaldehyde was 73.3%, and the yield of methacrolein was 62.8%. The catalytic performance did not significantly decrease after five cycles, but the yield was relatively low. US2639295 discloses a catalyst formed from organic amines and inorganic acids for the aldol condensation reaction; however, this catalyst requires high reaction temperatures, long reaction times, and significant equipment damage. Therefore, it is essential to develop a catalyst with high catalytic activity, high stability, and good hydrophobicity for the synthesis of methacrolein from formaldehyde and propionaldehyde. Summary of the Invention
[0003] To address the aforementioned problems in the preparation of methacrolein from formaldehyde and propionaldehyde in existing technologies, this invention provides a method for preparing and applying a hydrophobic heterogeneous polymerization ionic liquid catalyst. The heterogeneous polymerization ionic liquid catalyst provided by this invention is in solid form and can be used as a catalyst for the preparation of methacrolein. It not only avoids the equipment corrosion problems associated with traditional catalysts, but also allows for recycling, effectively reducing costs and demonstrating high practical value.
[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: A hydrophobic heterogeneous polymerization ionic liquid catalyst 1, characterized in that the structure of the polymerization ionic liquid catalyst is as shown in the attached formula. Figure 1 As shown: Compared to existing catalysts, the polymeric ionic liquid heterogeneous catalyst provided by this invention exhibits high catalytic activity and selectivity for the aldol condensation of formaldehyde and propionaldehyde to prepare methacrolein. Compared to traditional homogeneous catalysts, the polymeric ionic liquid heterogeneous catalyst prepared by this invention is less corrosive to equipment and is easy to separate and recover from the reaction system. The polymeric ionic liquid heterogeneous catalyst of this invention has excellent thermal and catalytic stability during the aldol condensation of formaldehyde and propionaldehyde to prepare methacrolein.
[0005] Secondly, the present invention also provides a method for preparing a hydrophobic heterogeneous polymerization ionic liquid catalyst, comprising the following steps: Step a: A tertiary amine compound protected by a BOC group, an acyl chloride substance with an unsaturated group, a basic substance, and a solvent are added to a flask and reacted at a certain temperature for a certain time to obtain a tertiary amine compound containing a BOC group. The preparation process and the compound structure are shown in the attached figure. Figure 2 As shown; Step b: The product shown in the above steps, i.e., the tertiary amine compound protected by BOC groups, is mixed with an unsaturated acid and a hydrophobic crosslinking agent, and 0.20 g of azobisisobutyronitrile is added. The mixture is reacted at a certain temperature for a certain time to obtain a polymer containing tertiary amines protected by BOC groups, hydrophobic groups, and acidic groups. The preparation process and compound structure are shown in the attached figure. Figure 3 As shown; Step c: Add the product shown in the above steps to an acidic substance and react at a certain temperature for a period of time to remove the BOC group. After the reaction is complete, separate the solid substance, and after washing and drying, obtain formula (I, Appendix). Figure 1 As shown in the figure, a polymeric ionic liquid catalyst possessing both secondary amines and carboxylic acids.
[0006] Furthermore, in step a, the tertiary amine compound protected by the BOC group is at least one of N-BOC-methylethanolamine or N-BOC-diethanolamine.
[0007] Furthermore, in step a, the acyl chloride compound having an unsaturated group is at least one of acryloyl chloride or methacryloyl chloride.
[0008] Furthermore, in step a, the molar ratio of acyl chlorides containing unsaturated groups to tertiary amines and bases protected by BOC groups is (1~5):(1~2):(1~3).
[0009] Furthermore, in step a, the alkaline substance is at least one of N,N-diisopropylethylamine, triethylamine, potassium carbonate or cesium carbonate, or propylamine.
[0010] Furthermore, in step a, the solvent is at least one of toluene, ethanol, diethyl ether, and chloroform.
[0011] Furthermore, in step a, the reaction temperature is between 0 and 40°C.
[0012] Furthermore, in step b, the unsaturated acid is at least one of oleic acid, linolenic acid, acrylic acid, and methacrylic acid.
[0013] Furthermore, in step b, the hydrophobic crosslinking agent is at least one of divinylbenzene, ethylene glycol dimethacrylate, or diallyl terephthalate.
[0014] Furthermore, in step b, the reaction temperature is between 50 and 100°C.
[0015] Furthermore, in step b, the reaction time is between 0.5 and 2 hours.
[0016] Furthermore, in step c, the acidic substance is at least one of hydrochloric acid, formic acid, p-toluenesulfonic acid, and trifluoroacetic acid.
[0017] Furthermore, in step c, the reaction temperature is between 10 and 70°C.
[0018] Furthermore, in step c, the reaction temperature is between 10 and 24 hours.
[0019] Furthermore, in step c, the molar ratio of the product to the acid is (1~2):(1~10). Thirdly, the present invention also provides a hydrophobic heterogeneous polymerization ionic liquid catalyst for the preparation of methacrolein from formaldehyde and propionaldehyde.
[0020] Fourthly, the present invention also provides a catalyst for the preparation of methacrolein from formaldehyde and propionaldehyde, comprising the above-mentioned hydrophobic heterogeneous polymerization ionic liquid catalyst.
[0021] Fifthly, the present invention also provides a method for preparing methacrolein from formaldehyde and propionaldehyde, comprising the following steps: taking 0.30g of the heterogeneous polymerization ionic liquid catalyst of claim 1 and adding it to a three-necked flask, simultaneously adding 0.01mol of formaldehyde and 0.01mol of propionaldehyde, and adding 5g of solvent, and stirring at 60°C for 1h to obtain the product.
[0022] The hydrophobic heterogeneous polymerization ionic liquid catalyst provided by this invention not only avoids the problem of equipment corrosion caused by traditional catalysts, but also can be recycled, effectively reducing costs and having high practical value. Attached Figure Description
[0023] Figure 1 The structural formula of the polymer ionic liquid catalyst Figure 2 Reaction route diagram for the preparation of polymerizable functional group monomers Figure 3 Reaction route diagram for polymer ionic liquid catalysts Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0025] To better illustrate the present invention, further examples are provided below. Example
[0026] This invention provides a benzocrown ether-based polymeric ionic liquid, the preparation method of which includes the following steps: Step a: Add 30 mL of ethanol and 3.00 g of potassium carbonate to a three-necked flask, then add 10.00 g of N-Boc-methylethanolamine and 6.00 g of methacryloyl chloride at room temperature. Stir the mixture at room temperature for 1.5 h. After the reaction is complete, filter the solution and collect it in a beaker to obtain the attached... Figure 2 The product shown.
[0027] Step b: Transfer the solution obtained above to a three-necked flask, and add 14.00 g of oleic acid, 3.25 g of divinylbenzene, and 0.20 g of AIBN. React at 100 °C for 1.2 h to obtain a yellow solid. Wash the solid and dry it to obtain the attached... Figure 3 The product shown is a pale yellow solid.
[0028] Step c: Place the pale yellow solid obtained above into a single-necked flask, add 2.50 g formic acid and 30 ml ethanol to the flask, and stir at room temperature for 12 h. After the reaction is complete, filter and dry to obtain a white solid product, as shown in the attached formula. Figure 1 The shown is a hydrophobic heterogeneous polymeric ionic liquid catalyst.
[0029] Implementation Case 2 Step a: Add 30 mL of toluene and 10.00 g of N-Boc diethanolamine to a three-necked flask, and then add 7.00 g of triethylamine and 6.00 g of acryloyl chloride under ice bath conditions. Stir the mixture at room temperature for 1.7 h. After the reaction is complete, filter the solution and collect it in a beaker to obtain the product shown in the attached formula. Figure 2 The product shown.
[0030] Step b: Transfer the solution obtained above to a three-necked flask, and add 5.00 g of methacrylic acid, 5.00 g of ethylene glycol dimethacrylate, and 0.20 g of AIBN. React at 80 °C for 1 h to obtain a solid. Wash the solid and dry it to obtain the attached... Figure 3 The product shown is a pale yellow solid.
[0031] Step c: Place the obtained yellow solid into a single-necked flask, add 1.43 g of trifluoroacetic acid and 30 ml of ethanol, and stir at room temperature for 12 h. After the reaction is complete, filter and dry to obtain a yellow solid product, namely... Figure 1 The shown is a hydrophobic heterogeneous polymeric ionic liquid catalyst.
[0032] Implementation Case 3 Step a: Add 30 mL of diethyl ether and 7.00 g of N-Boc-N-methylethanolamine to a three-necked flask, and then add 3.00 g of propylamine and 6.00 g of methacrylamide chloride at 40 °C. Stir the mixture at room temperature for 1 h. After the reaction is complete, filter the solution and collect it in a beaker to obtain the product shown in the attached formula. Figure 2 The product shown.
[0033] Step b: Transfer the solution obtained above to a three-necked flask, and add 14.00 g of linolenic acid, 6.00 g of diallyl terephthalate, and 0.20 g of AIBN. React at 65°C for 1.3 h to obtain a solid. Wash the solid and dry it to obtain the formula. Figure 3 The product shown is a pale yellow solid.
[0034] Step c: Place the obtained yellow solid into a single-necked flask, add 9.00 g of p-toluenesulfonic acid and 30 ml of ethanol, and stir at room temperature for 12 h. After the reaction is complete, filter and dry to obtain a yellow solid product, namely... Figure 1 The shown is a hydrophobic heterogeneous polymeric ionic liquid catalyst.
[0035] Comparison Example Step a: Add 25 mL of diethyl ether and 4.00 g of N-Boc-methylethanolamine to a three-necked flask, and then add 3.00 g of propylamine and 6.00 g of methacrylamide chloride at 40 °C. Stir the mixture at room temperature for 1 h. After the reaction is complete, filter the solution and collect it in a beaker to obtain the product shown in the attached formula. Figure 2 The product shown.
[0036] Step b: Transfer the solution obtained above to a three-necked flask, and add 14.00 g of linolenic acid, 2.00 g of N,N-methylenebisacrylamide, and 0.20 g of AIBN. React at 65 °C for 1.3 h to obtain a solid. Wash the solid and dry it to obtain the formula. Figure 3 The product shown is a pale yellow solid.
[0037] Step c: Place the obtained yellow solid into a single-necked flask, add 9.00 g of p-toluenesulfonic acid and 30 ml of ethanol, and stir at room temperature for 12 h. After the reaction is complete, filter and dry to obtain a yellow solid product, namely... Figure 1 The shown is a hydrophobic heterogeneous polymeric ionic liquid catalyst.
[0038] The hydrophobic heterogeneous polymerization ionic liquid catalysts prepared in Examples 1 to 3 and the control example were used to prepare methacrolein by simulating formaldehyde and propionaldehyde, and their catalytic performance was tested.
[0039] (1) Conversion and selectivity of methacrolein under catalyst 1 conditions 0.01 mol propionaldehyde and 0.01 mol formaldehyde were placed in a three-necked flask, and 0.30 g of the polymeric ionic liquid heterogeneous catalyst prepared in the examples and control examples and 5.00 g of ethanol were added. The reaction was carried out at 60 °C for 1 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried, and the propionaldehyde conversion, methacrolein selectivity and yield were measured.
[0040] Conversion and selectivity of different catalysts catalyst Conversion rate % Yield % Selectivity% Catalyst 1 99.18 98.06 98.87 Catalyst 2 94.96 91.02 95.85 Catalyst 3 90.84 87.02 95.80 Comparison Example 80.71 72.23 89.49 Conversion rate of propionaldehyde % = (Mass of propionaldehyde before reaction - Mass of propionaldehyde after reaction) / Mass of propionaldehyde before reaction 100% of the mass of aldehyde; The yield percentage of methacrolein is calculated as follows: (mass of methacrolein actually synthesized / mass of methacrolein theoretically synthesizable from all raw materials) × 100%. Selectivity of methacrolein (%) = (Yield of methacrolein (%) / Conversion rate of propionaldehyde (%)) * 100% (2) Analysis of the catalytic effect of different catalysts Based on the data above, when using hydrophobic heterogeneous polymeric ionic liquid catalyst 1, the conversion rate of propionaldehyde is 99.18%, the selectivity of methacrolein is 98.87%, and the yield of methacrolein is 98.06%. When using hydrophobic heterogeneous polymeric ionic liquid catalysts 2, 3, and 4, the conversion rate of propionaldehyde is all below 95%, and the selectivity and yield of methacrolein are both lower than those of catalyst 1. Therefore, under the same conditions, catalyst 1 has a relatively better catalytic effect compared to the other three catalysts.
[0041] Therefore, it can be seen that the hydrophobic heterogeneous polymerization ionic liquid catalyst 1 prepared by the present invention is more conducive to product formation, and its catalytic effect is the best compared with catalysts 2, 3 and 4.
[0042] Recovery method: After the hydrophobic heterogeneous polymeric ionic liquid catalyst has completed the reaction, it is poured out of the product solution and filtered, then washed with ethanol and water 3-5 times. Finally, the washed catalyst is placed in a vacuum drying oven for drying, so that it can be reused next time.
[0043] Reuse: 0.30 g of the prepared heterogeneous polymeric ionic liquid catalyst was added to a three-necked flask, along with 0.01 mol of propionaldehyde, 0.01 mol of formaldehyde, and 5.00 g of ethanol. The reaction was carried out at 60 °C for 1 h. After the reaction was completed, the mixture was cooled to room temperature. The above recovery method was repeated for the next recycling. The yield data after 5 reuses are shown in the table below. Table 2. Yields after reuse of different catalysts frequency 1 2 3 4 5 Catalyst 1 98.06 98.02 97.98 97.92 97.85 Catalyst 2 91.02 91.01 90.97 90.94 90.86 Catalyst 3 87.02 86.97 86.91 86.86 86.77 Comparison Example 72.23 71.89 71.86 71.78 71.74 According to the data in the table above, the yield of the heterogeneous polymerization ionic liquid catalyst remains essentially unchanged after five consecutive reuses. This indicates that the heterogeneous polymerization ionic liquid catalyst has good reusability.
[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A hydrophobic heterogeneous polymerization ionic liquid catalyst 1, characterized in that, The structure of the polymeric ionic liquid is shown in Figure 1.
2. A method for preparing the hydrophobic heterogeneous polymerization ionic liquid catalyst as described in claim 1, characterized in that, Includes the following steps: Step a: Add a tertiary amine compound protected by a BOC group, an acyl chloride substance with an unsaturated group, a basic substance and 20 ml of solvent to a flask, and react at a certain temperature for a certain time to obtain a tertiary amine compound protected by a BOC group. The preparation process and the compound structure are shown in Figure 2. Step b: The product shown in the above steps, namely the tertiary amine compound protected by BOC groups, is mixed with an unsaturated acid and a hydrophobic crosslinking agent, and 0.20 g of azobisisobutyronitrile is added. The mixture is reacted at a certain temperature for a certain time to obtain a polymer containing tertiary amines protected by BOC groups, hydrophobic groups, and acidic groups. The preparation process and compound structure are shown in Figure 3. Step c: Add the product shown in the above steps to an acidic substance and react at a certain temperature for a period of time to remove the BOC group. After the reaction is completed, separate the solid substance, and after washing and drying, obtain the polymeric ionic liquid catalyst with both secondary amine and carboxylic acid as shown in formula (Ⅰ).
3. The method for preparing the hydrophobic heterogeneous polymerization ionic liquid catalyst as described in claim 2, characterized in that, In step a, the tertiary amine compound protected by the BOC group is at least one of N-BOC-methylethanolamine or N-BOC-diethanolamine; and / or; In step a, the acyl chloride compound having an unsaturated group is at least one of acryloyl chloride or methacryloyl chloride; and / or; In step a, the molar ratio of the acyl chloride containing unsaturated groups to the tertiary amine compound protected by BOC groups and the base is (1~5):(1~2):(1~3); and / or In step a, the alkaline substance is at least one of N,N-diisopropylethylamine, triethylamine, potassium carbonate or cesium carbonate, and propylamine; and / or; In step a, the solvent is at least one of toluene, ethanol, diethyl ether, and chloroform; and / or; In step a, the reaction temperature is between 0 and 40°C.
4. The method for preparing the hydrophobic heterogeneous polymerization ionic liquid catalyst as described in claim 2, characterized in that, The unsaturated acid mentioned in step b is at least one of oleic acid, linolenic acid, acrylic acid, and methacrylic acid; and / or; The hydrophobic crosslinking agent mentioned in step b is at least one of divinylbenzene, ethylene glycol dimethacrylate, or diallyl terephthalate; and / or; The molar ratio of the tertiary amine compound protected by the BOC group to the unsaturated acid and the hydrophobic crosslinking agent described in step b is (1~5):(1~10):(1~2). The reaction temperature described in step b is between 50 and 100°C. The reaction time described in step b is between 0.5 and 2 hours.
5. The method for preparing the hydrophobic heterogeneous polymerization ionic liquid catalyst as described in claim 2, characterized in that, In step c, the acid is at least one of hydrochloric acid, formic acid, p-toluenesulfonic acid, and trifluoroacetic acid; and / or; The reaction temperature described in step c is between 10 and 70°C. The reaction temperature described in step c is between 10 and 24 hours. In step c, the molar ratio of the product to the acidic substance is (1~2):(1~10).