A nano-silica supported metal complex catalyst, a preparation method and application thereof
By preparing metal complex catalysts supported on nano-silica, the problem of difficult separation and recovery of homogeneous catalysts was solved, achieving efficient catalysis and easy separation of copolymerization of olefins and polar monomers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2024-07-23
- Publication Date
- 2026-05-29
AI Technical Summary
Existing homogeneous catalysts are difficult to separate and recover during the copolymerization of olefins and polar monomers, resulting in difficulties in reuse and catalyst residues in the reaction products, which increases the difficulty of purification.
A metal complex catalyst supported on nano-silica was prepared by surface modification with silane coupling agent and Schiff base bidentate ligand modification, resulting in a heterogeneous catalyst that is easy to separate. The ligands were fixed by chemical bonding, and the number of metal active centers and coordination environment were adjusted.
It achieves efficient separation and recovery of catalysts, improves catalytic efficiency, simplifies product purification process, and is suitable for copolymerization of olefins and polar monomers.
Smart Images
Figure CN118930701B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of copolymerization of olefins and polar monomers, and specifically to a nano-silica supported metal complex catalyst, its preparation method, and its application. Background Technology
[0002] Polyolefin materials are ubiquitous in daily life, being the most produced and widely used polymeric materials. However, one of their biggest drawbacks is their non-polar nature. Introducing polar functional groups into the non-polar backbone of polyolefins can improve their compatibility with polar materials and significantly enhance their various properties. Therefore, researchers hope to copolymerize olefins with polar monomers to obtain high-performance functionalized olefins. Catalysts play a crucial role in the copolymerization of olefins and polar monomers, and with the development of science and technology, catalysts for the synthesis of polyolefin materials are also evolving.
[0003] Among them, pre-transition metal catalysts are easily poisoned and deactivated by polar groups due to the high oxyphilicity of their metal centers. In contrast, post-transition metal catalysts have the advantages of weak oxyphilicity and high tolerance to polar groups, which is beneficial for the copolymerization of olefins and polar monomers. Most research on post-transition metal catalysts in the past two decades has focused on homogeneous catalytic systems, mainly because homogeneous catalysts have high reactivity and selectivity. However, they are difficult to separate and recover from the reaction system after use, hindering reuse, and catalyst residues remain in the reaction products, increasing the difficulty of purification. Therefore, developing a heterogeneous catalyst that is easy to separate, recyclable, and has high catalytic efficiency has important theoretical and practical significance. Summary of the Invention
[0004] The purpose of this invention is to provide a nano-silica supported metal complex catalyst, its preparation method and application, wherein the nano-silica supported metal complex catalyst is used to catalyze the polymerization of olefins and polar monomers.
[0005] In one aspect of the invention, a nano-silica-supported metal complex catalyst is provided. According to an embodiment of the invention, its structural formula is as follows:
[0006]
[0007] In the formula, M = Pd, Fe, or Co.
[0008] In another aspect of the present invention, a method for preparing a nano-silica-supported metal complex catalyst is provided. According to an embodiment of the present invention, the method includes the following steps: surface modification of nano-silica using a silane coupling agent to amination its surface; preparation of a Schiff base bidentate ligand with a carboxyl end group; condensation of the modified nano-silica with the Schiff base bidentate ligand to obtain surface-modified nano-silica; and reaction of the surface-modified nano-silica with a metal complex to obtain a nano-silica-supported metal complex catalyst.
[0009] In addition, the preparation method of the nano-silica supported metal complex catalyst according to the above embodiments of the present invention may also have the following additional technical features:
[0010] In some embodiments of the present invention, the method specifically includes the following steps: (1) Synthesis of ligands and activation of terminal carboxyl groups: Under a nitrogen atmosphere, the first reagent, glacial acetic acid, anhydrous ethanol and p-aminobenzoic acid are heated and stirred, filtered under reduced pressure, washed with anhydrous ethanol to remove excess raw materials, recrystallized with methanol and petroleum ether, allowed to stand at low temperature, and the solvent of recrystallization is removed under vacuum to obtain a powder product; the powder product is added to dry dichloromethane and a catalytic equivalent of dimethylformamide, the reaction mixture obtained after the reaction is cooled, the second reagent is slowly added, stirred, and the solvent is removed by rotary evaporation to obtain products with activated terminal carboxyl groups, wherein the first reagent is pyridine-2-carboxaldehyde, thiophene-2-carboxaldehyde or furfural, and the second reagent is oxalyl chloride;
[0011] The general synthetic formula for the above reaction is as follows:
[0012]
[0013] (2) Synthesis of Schiff base ligands supported on nano-silica: under a nitrogen atmosphere, the third reagent, deionized water and anhydrous ethanol were stirred and hydrolyzed, and then nano-silica was added and sonicated and heated and stirred; after the reaction was completed, the product was washed and dried to obtain a white powder product. The white powder product, dichloromethane, 4-dimethylaminopyridine and triethylamine were mixed, and then the product with terminal carboxyl group activation was slowly added at low temperature. The reaction was stirred at room temperature, and after washing, filtration and drying, the immobilized ligand was obtained. The third reagent was 3-aminopropyltriethoxysilane.
[0014] (3) Synthesis of nano-silica supported metal complex catalyst: Under a nitrogen atmosphere, anhydrous ethanol and a fourth reagent are added to the supported ligand, and the mixture is placed in an oil bath and stirred under reflux. After washing, filtering and drying, the nano-silica supported metal complex catalyst is obtained. The fourth reagent is any one or two of PdCl2, FeCl2 and CoCl2.
[0015] In some embodiments of the present invention, in step (1), the molar ratio of the first reagent to p-aminobenzoic acid is 1.1 to 1.2:1; and the molar ratio of the second reagent to the powder product is 1.1 to 1.3:1.
[0016] In some embodiments of the present invention, in step (1), the heating and stirring is carried out by reflux stirring in an oil bath for 8-12 hours, and the temperature of the oil bath is 76-80°C.
[0017] In some embodiments of the present invention, in step (2), the mass ratio of the third reagent to deionized water and anhydrous ethanol is 2:10:80-88; the molar ratio of the third reagent to the hydroxyl groups on the surface of nano-silica is 1.1-1.2:1.
[0018] In some embodiments of the present invention, in step (2), heating and stirring are carried out in an oil bath at a temperature of 76-80°C.
[0019] In some embodiments of the present invention, in step (3), the molar ratio of the fourth reagent to the supported ligand is 1:1.1 to 1.2. The oil bath temperature is 76 to 80°C, and the reaction time is 12 to 15 hours.
[0020] In some embodiments of the present invention, in step (3), the temperature of the oil bath is 76-80°C and the reaction time is 12-15h.
[0021] In another aspect of the invention, the application of nano-silica-supported metal complex catalysts is proposed. According to embodiments of the invention, the nano-silica-supported metal complex catalyst is used to catalyze the polymerization of olefins with polar monomers.
[0022] In addition, the application of the nano-silica supported metal complex catalyst according to the above embodiments of the present invention may also have the following additional technical features:
[0023] In some embodiments of the present invention, the polar monomers include 6-chloro-1-hexene, methyl 10-undecenoate, and 10-undeceno-1-ol.
[0024] Compared with the prior art, the beneficial effects of the present invention are:
[0025] (1) The catalyst synthesis steps in this invention are relatively simple, the raw materials used are inexpensive and easy to obtain, the reaction conditions are relatively mild, and the product yield is relatively high.
[0026] (2) In this invention, bidentate ligands of N^N, N^O and N^S frameworks are fixed on nano silica support by chemical bonding; the number of metal active centers can be adjusted by controlling the loading of ligands on the support; supported catalysts with different metal centers can be obtained by changing the molar ratio of different metal chlorides; different coordination environments can be achieved by regulating the surface structure of the support, thereby optimizing the catalytic performance of the catalyst.
[0027] (3) Dispersing metal complexes on the surface of nano-silica support improves the catalytic efficiency per unit mass of catalyst. The nano-silica support, Schiff base ligand, and co-catalyst interact with each other, thus affecting the activity and stability of the catalyst. In this invention, the catalyst can be easily recovered through precipitation, filtration, and other operations after the polymerization reaction, making full use of the easy separation characteristics of the catalyst in the multiphase system to achieve multiphase separation. Attached Figure Description
[0028] Figure 1 This is the 1H NMR spectrum of the pyridine-2-carboxaldehyde condensate p-aminobenzoic acid Schiff base ligand in Example 1 of the present invention;
[0029] Figure 2 This is the 1H NMR spectrum of the thiophene-2-carboxaldehyde condensate p-aminobenzoic acid Schiff base ligand in Example 2 of the present invention;
[0030] Figure 3 This is the general formula for the synthesis of nano-silica supported metal complex catalysts in Examples 1-3 of the present invention, where M = Pd. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0032] Example 1
[0033] A method for preparing a nano-silica supported metal complex catalyst includes the following steps:
[0034] (1) Weigh 1.37 g (10 mmol) of p-aminobenzoic acid into a 250 mL round-bottom flask. Under nitrogen protection, add 60 mL of anhydrous ethanol, 0.1 mL of glacial acetic acid, and 1.17 g (11 mmol) of pyridine-2-carboxaldehyde in sequence. Place the double-necked flask in an oil bath and reflux at 80 °C for 8 h. A yellow solid precipitates in the solution. After vacuum filtration, wash several times with anhydrous ethanol. After removing the solvent under vacuum, gently heat the solid and dissolve it in a small amount of methanol. Add petroleum ether dropwise, and a yellow powder precipitates. Place the flask in a refrigerator at 0 °C and let it stand for 4 h. Remove the solvent under vacuum. The solvent was removed to obtain 1.76 g of pyridine-2-carboxaldehyde p-aminobenzoic acid Schiff base ligand as a yellow powder, with a yield of 77.9%. 1.13 g (5 mmol) of pyridine-2-carboxaldehyde p-aminobenzoic acid Schiff base ligand was weighed into a 100 mL double-necked flask, and 40 mL of dry DCM and 0.1 mL of DMF were added. The mixture was cooled to 0 °C, and 0.83 g (6.5 mmol) of oxaloyl chloride was slowly added and stirred at room temperature for 5 h. The solvent was removed by rotary evaporation at 25 °C to obtain pyridine-2-carboxaldehyde p-aminobenzoic acid chloride.
[0035] (2) Under a nitrogen atmosphere, KH550 (2.00 g, 9 mmol) was weighed into a 250 mL round-bottom flask, and deionized water (10.00 g) and anhydrous ethanol (88.00 g) were added. The mixture was stirred for 15 min for hydrolysis. Then, nano-silica (1.00 g, with a hydroxyl content of about 8 mmol) was added and sonicated for 30 min. The mixture was then placed in an oil bath and heated and stirred at 80 °C for 24 h. After the reaction was completed, the mixture was washed several times by centrifugation with anhydrous ethanol and water, and dried under vacuum at 60 °C for 12 h to obtain 1.4 g of white powder, which was denoted as KH550-SiO2. Weigh 1.3 g of KH550-SiO2 into a 100 mL round-bottom flask. Under a nitrogen atmosphere, add 20 mL of dichloromethane, 0.56 g (5.5 mmol) of triethylamine, and 0.61 g (5 mmol) of DMAP. Slowly add 1.22 g (5 mmol) of pyridine-2-carboxaldehyde acetal of p-aminobenzoyl chloride and stir at room temperature for 20 h. After washing and drying, obtain the first supported ligand.
[0036] (3) Weigh 1.00 g of the supported ligand and place it in a 100 mL double-necked flask. Add 30 mL of anhydrous ethanol and 177 mg, 1 mmol of PdCl2. Stir at room temperature for 12 h, then stop the reaction. Filter and dry to obtain the nano-silica-supported N^N framework metal complex catalyst. The general formula for synthesis is as follows: Figure 3 As shown, the catalyst structure is as follows:
[0037]
[0038] Example 2
[0039] A method for preparing a nano-silica supported metal complex catalyst includes the following steps:
[0040] (1) Weigh 1.37 g (10 mmol) of p-aminobenzoic acid into a 250 mL round-bottom flask. Under nitrogen protection, add 60 mL of anhydrous ethanol, 0.1 mL of glacial acetic acid, and 1.23 g (11 mmol) of thiophene-2-carboxaldehyde in sequence. Place the double-necked flask in an oil bath and reflux at 80 °C for 8 h. A brown solid precipitates in the solution. After vacuum filtration, wash several times with anhydrous ethanol. After removing the solvent under vacuum, gently heat the solid and dissolve it in a small amount of methanol. Add petroleum ether dropwise, and a brown powder precipitates. Place the flask in a refrigerator. After standing at 0℃ and removing the solvent under vacuum, 1.88 g of brown powder thiophene-2-carboxaldehyde acetal p-aminobenzoic acid Schiff base ligand was obtained, with a yield of 81.4%. 1.15 g (5 mmol) of the Schiff base ligand was weighed into a 100 mL double-necked flask, and 40 mL of dry DCM and 0.1 mL of DMF were added. The mixture was cooled to 0℃, and 0.83 g (6.5 mmol) of oxaloyl chloride was slowly added and stirred at room temperature for 5 h. The solvent was removed by rotary evaporation at 25℃ to obtain the carboxyl-terminated activated Schiff base ligand.
[0041] (2) The preparation method of KH550-SiO2 is the same as in Example 1. Weigh 1.3 g of KH550-SiO2 into a 100 mL round-bottom flask, add dichloromethane (20 mL), triethylamine (0.56 g, 5.5 mmol), and DMAP (0.61 g, 5 mmol) under a nitrogen atmosphere, and slowly add thiophene-2-carboxaldehyde acetal p-aminobenzoyl chloride (1.25 g, 5 mmol) and stir at room temperature for 20 h; after washing and drying, the supported ligand II is obtained.
[0042] (3) Weigh 1.00 g of the supported ligand II into a 100 mL double-necked flask, add 30 mL of anhydrous ethanol and 127 mg (1 mmol) of FeCl2, stir at room temperature for 12 h, then stop the reaction. After filtration and drying, the nano-silica-supported N^S framework metal complex catalyst is obtained. The general synthetic formula is as follows: Figure 3 As shown, the catalyst structure is as follows:
[0043]
[0044] Example 3
[0045] A method for preparing a nano-silica supported metal complex catalyst includes the following steps:
[0046] (1) Weigh p-aminobenzoic acid (1.37 g, 10 mmol) into a 250 mL round-bottom flask. Under nitrogen protection, add anhydrous ethanol (60 mL), glacial acetic acid (0.1 mL), and furfural (1.06 g, 11 mmol) in sequence. Place the double-necked flask in an oil bath and reflux at 80 °C for 8 h. After vacuum filtration, remove the solvent by rotary evaporation. Separate the solution by neutral alumina column chromatography to obtain a yellow liquid. After drying, obtain furfural condensed p-aminobenzoic acid Schiff base ligand. Weigh the Schiff base ligand (1.07 g, 5 mmol) into a 100 mL double-necked flask. Add dry DCM (40 mL) and DMF (0.1 mL). Cool the mixture to 0 °C. Slowly add oxaloyl chloride (0.83 g, 6.5 mmol) and stir at room temperature for 5 h. Remove the solvent by rotary evaporation at 25 °C to obtain the Schiff base ligand with terminal carboxyl group activation.
[0047] (2) The preparation method of KH550-SiO2 is the same as in Example 1. KH550-SiO2 (1.3 g) was weighed into a 100 mL round-bottom flask. Under a nitrogen atmosphere, dichloromethane (20 mL), triethylamine (0.56 g, 5.5 mmol), and DMAP (0.61 g, 5 mmol) were added. Furfural-p-aminobenzoyl chloride (1.17 g, 5 mmol) was then slowly added, and the mixture was stirred at room temperature for 20 h. After washing and drying, the supported ligand II was obtained.
[0048] (3) Weigh 1.00 g of the supported ligand II into a 100 mL double-necked flask, add 30 mL of anhydrous ethanol and 238 mg (1 mmol) of CoCl2·6H2O, stir at room temperature for 12 h, then stop the reaction. After filtration and drying, the nano-silica-supported N^O framework metal complex catalyst is obtained. The general synthetic formula is as follows: Figure 3 As shown, the catalyst structure is as follows:
[0049]
[0050] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.
Claims
1. A nano-silica supported metal complex catalyst, characterized in that, Its structural formula is: In the formula, M = Pd, Fe, or Co, and the M in the structure of the nano-silica supported metal complex catalyst is coordinated with the heteroatom in R.
2. A method for preparing the nano-silica supported metal complex catalyst according to claim 1, characterized in that, Includes the following steps: The surface of nano-silica was modified by using a silane coupling agent to make its surface amino; a Schiff base bidentate ligand with a carboxyl end group was prepared; the modified nano-silica was condensed with the Schiff base bidentate ligand to obtain surface-modified nano-silica; the surface-modified nano-silica was reacted with a metal complex to obtain a nano-silica supported metal complex catalyst.
3. The method for preparing a nano-silica-supported metal complex catalyst according to claim 2, characterized in that, Specifically, the following steps are included: (1) Synthesis of ligands and activation of terminal carboxyl groups: Under a nitrogen atmosphere, the first reagent, glacial acetic acid, anhydrous ethanol and p-aminobenzoic acid were heated and stirred. After vacuum filtration, excess raw materials were washed with anhydrous ethanol. The mixture was recrystallized with methanol and petroleum ether, allowed to stand at 0 degrees, and the solvent for recrystallization was removed under vacuum to obtain a powder product. The powder product was added to dry dichloromethane and a catalytic equivalent of dimethylformamide. The reaction mixture was cooled and the second reagent was slowly added. The mixture was stirred and the solvent was removed by rotary evaporation to obtain products with activated terminal carboxyl groups. The first reagent was pyridine-2-carboxaldehyde, thiophene-2-carboxaldehyde or furfural, and the second reagent was oxalyl chloride. (2) Synthesis of Schiff base ligands supported on nano-silica: under a nitrogen atmosphere, the third reagent, deionized water and anhydrous ethanol were stirred and hydrolyzed, and then nano-silica was added and sonicated and heated and stirred; after the reaction was completed, the product was washed and dried to obtain a white powder product. The white powder product, dichloromethane, 4-dimethylaminopyridine and triethylamine were mixed, and then the product with terminal carboxyl group activation was slowly added. The reaction was stirred at room temperature, and after washing, filtration and drying, the immobilized ligand was obtained. The third reagent was 3-aminopropyltriethoxysilane. (3) Synthesis of nano-silica supported metal complex catalyst: Under a nitrogen atmosphere, anhydrous ethanol and a fourth reagent are added to the solid ligand, and the mixture is placed in an oil bath and stirred under reflux. After washing, filtering and drying, the nano-silica supported metal complex catalyst is obtained. The fourth reagent is any one or two of PdCl2, FeCl2 and CoCl2.
4. The method for preparing a nano-silica supported metal complex catalyst according to claim 3, characterized in that: In step (1), the molar ratio of the first reagent to p-aminobenzoic acid is 1.1 to 1.2:1; the molar ratio of the second reagent to the powder product is 1.1 to 1.3:
1.
5. The method for preparing a nano-silica supported metal complex catalyst according to claim 3, characterized in that: In step (1), the heating and stirring is carried out by reflux stirring in an oil bath for 8-12 hours, and the temperature of the oil bath is 76-80℃.
6. The method for preparing a nano-silica supported metal complex catalyst according to claim 3, characterized in that: In step (2), the mass ratio of the third reagent to deionized water and anhydrous ethanol is 2:10:80-88; the molar ratio of the third reagent to the hydroxyl groups on the surface of nano-silica is 1.1-1.2:
1.
7. The method for preparing a nano-silica supported metal complex catalyst according to claim 3, characterized in that: In step (2), heating and stirring are carried out in an oil bath at a temperature of 76-80°C.
8. The method for preparing a nano-silica supported metal complex catalyst according to claim 3, characterized in that: In step (3), the molar ratio of the fourth reagent to the supported ligand is 1:1.1 to 1.2, the oil bath temperature is 76 to 80°C, and the reaction time is 12 to 15 h.
9. The application of the nano-silica supported metal complex catalyst according to claim 1, characterized in that: The nano-silica supported metal complex catalyst is used to catalyze the polymerization of olefins and polar monomers.
10. The application of the nano-silica supported metal complex catalyst according to claim 9, characterized in that: The polar monomers include those selected from 6-chloro-1-hexene, methyl 10-undecenoate, and 10-undeceno-1-ol.