Porous cozn-salen based heterogeneous catalyst based on chloro-spheres, method of preparation and use thereof

Abstract

The application discloses a porous CoZn-Salen-based heterogeneous catalyst based on chloro-spheres and a preparation method and application thereof, and belongs to the technical field of catalysts. The catalyst takes chloro-spheres as carriers, loads customized Salen ligands, introduces two different metal ions Co 3+ and Zn 2+ through a simple grafting reaction to form a bimetallic synergistic catalytic center. The catalyst prepared by the application has the advantages of low cost, good carrier dispersity, controllable metal loading, and remarkable bimetallic synergistic effect, and in the catalysis of the copolymerization reaction of cyclohexene oxide and CO2, the catalyst has high catalytic activity, high copolymerization selectivity and good cycle stability. The method is simple in process, mild in conditions and friendly to the environment, provides a novel and efficient catalyst for the copolymerization reaction of cyclohexene oxide, and has important industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and more specifically, relates to porous CoZn-Salen-based heterogeneous catalysts based on chlorine spheres, their preparation methods, and applications. Background Technology

[0002] Cyclohexane oxide (CHO), an epoxy compound with cycloalkyl groups, produces copolymers (such as polycarbonate and polyether esters) that exhibit excellent heat resistance, mechanical strength, and barrier properties due to their combination of rigid ring structures and flexible segments. These copolymers show broad application prospects in engineering plastics, packaging materials, and coatings. The core of cyclohexane oxide copolymerization lies in the design and preparation of the catalyst. An ideal catalyst should possess characteristics such as high catalytic activity, high copolymerization selectivity, and easy recyclability and reuse.

[0003] Salen-type catalysts are a classic class of metal coordination catalysts. They form catalytic centers through the coordination of metal ions with Salen ligands (bident or polydentate ligands containing Schiff base structures), exhibiting excellent catalytic performance in the ring-opening copolymerization of epoxy compounds. However, traditional homogeneous Salen-type catalysts suffer from problems such as difficult separation and recovery, easy agglomeration and deactivation, and difficulty in reuse, which limit their industrial applications.

[0004] To address this issue, researchers have loaded Salen ligands onto inorganic supports (such as silica gel and mesoporous molecular sieves) or organic supports (such as polymer microspheres) to prepare heterogeneous Salen-type catalysts, achieving efficient catalyst recovery. However, single-metal supported Salen catalysts often exhibit defects such as insufficient catalytic activity and a wide molecular weight distribution of copolymerized products when catalyzing the copolymerization of cyclohexane oxide. Summary of the Invention

[0005] To address the problems of separation and recovery difficulties and insufficient single-metal catalytic activity in existing Salen-type catalysts, this invention provides a porous CoZn-Salen-based heterogeneous catalyst based on chlorine spheres, its preparation method, and its application. By grafting Salen ligands onto the surface of chlorine spheres and loading Co(III) and Zn bimetallic ions in one step, a bimetallic synergistic catalytic center is constructed, thereby achieving heterogeneity and high activity of the catalyst.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a porous CoZn-Salen-based heterogeneous catalyst based on chlorine spheres, which has the following basic structural units:

[0008] ;

[0009] Where M1=M2=Zn 2+ or Co 3+ ;or

[0010] M1 and M2 are Zn 2+ Co 3+ Any one of them, and M1 and M2 are different;

[0011] The term refers to a diamine monomer, wherein the diamine monomer is any one of o-phenylenediamine, 1,2-cyclohexanediamine, or ethylenediamine;

[0012] R can be any one of H, methoxy, or tert-butyl.

[0013] This invention also provides a method for preparing the aforementioned porous CoZn-Salen-based heterogeneous catalyst based on chlorine spheres, comprising the following steps:

[0014] S1, Modification of Chlorine Balls

[0015] Commercially available chlorinated spheres were dried and swollen, then salicylaldehyde was added. Salicylaldehyde was grafted onto the chlorinated spheres using an AlCl3-catalyzed Friedel-Crafts reaction to obtain the chlorinated sphere modified compound Mc-CHO.

[0016] The reaction equation is as follows:

[0017]

[0018] S2, Synthesis of small molecule salon ligands

[0019] In a nitrogen atmosphere, the diamine monomer dissolves in anhydrous ethanol, and an ethanol solution of salicylaldehyde or its substituted derivatives is added dropwise and refluxed to yield the small molecule salon ligand. The reaction equation is as follows:

[0020]

[0021] Wherein, R is any one of H, methoxy or tert-butyl;

[0022] Synthesis of S3 and Chloride Ball Salen

[0023] The chlorine sphere modified compound obtained in step S1 was fully swollen, and a small molecule salen ligand was added to undergo an imine exchange reaction. The small molecule salen ligand was loaded onto the catalyst precursor. After the reaction was completed, the catalyst was washed and dried to obtain a porous salen heterogeneous catalyst based on chlorine spheres.

[0024] Depending on the different diamine monomers, the reaction equations are as follows:

[0025] ;

[0026] ;

[0027] .

[0028] S4, loading of metal ions

[0029] The porous Salen heterogeneous catalyst based on chloride spheres obtained in step S3 was fully swollen, and then Co-containing catalyst was added. 2+ With Zn 2+ A metal salt mixture solution was subjected to metal loading and coordination reaction at 25–60 °C for 1–6 h. After the reaction, the mixture was filtered, washed, and dried to obtain a coordination-stable porous Co(II)Zn-Salen-based heterogeneous catalyst based on chloride spheres; wherein, Co… 2+ With Zn 2+ The molar ratio is 1:1;

[0030] In this step, the metal ions are anchored to the catalyst by relying on the coordination ability of the Salen structure. Co and Zn do not exhibit significant selectivity. 2+ With Zn 2+ When the molar ratio is 1:1, the catalyst contains the same molar amount of Co. 2+ With Zn 2+ .

[0031] Oxidation of S5 and Co

[0032] The porous Co(II)Zn-Salen-based heterogeneous catalyst based on chlorine spheres obtained in step S4 was fully swollen and oxidized in an oxygen atmosphere using p-toluenesulfonic acid as a catalyst to obtain a porous Co(III)Zn-Salen-based heterogeneous catalyst based on chlorine spheres.

[0033] Preferably, in step S1, the temperature of the Friedel-Crafts reaction is 45–95 °C, and the reaction time is 10–48 h.

[0034] Preferably, in step S1, the chlorine content of the chlorine balls is 1.5~4.0 mmol / g, and the particle size is 50~500 μm.

[0035] Preferably, in step S2, the reflux reaction temperature is 70-90℃ and the time is 5-8 h.

[0036] Preferably, in step S3, the imine exchange reaction is carried out at a temperature of 80–120°C for 12–48 h.

[0037] Preferably, the porous Co(III)Zn-Salen-based heterogeneous catalyst based on chlorine spheres has a pore size of 2–15 nm and a specific surface area of ​​100–500 m². 2 / g.

[0038] Preferably, the total content of metal ions in the heterogeneous catalyst is 5 wt% to 18 wt%.

[0039] The present invention further provides the application of the aforementioned porous CoZn-Salen-based heterogeneous catalyst based on chlorine spheres in the catalytic synthesis of polycarbonate from carbon dioxide and epoxides.

[0040] Preferably, the epoxide is cyclohexane oxide.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The catalyst has a reasonable structural design and a significant bimetallic synergistic effect: by simultaneously loading two different metal ions, a bimetallic synergistic catalytic center is constructed. The electron transfer and spatial matching between the metal ions significantly improve the catalytic activity and copolymerization selectivity. Compared with catalysts supported by a single metal, the catalytic efficiency is improved by more than 30%.

[0043] Excellent support performance and easy catalyst recycling and reuse: Using chlorine spheres as a support, it has the characteristics of large specific surface area, high mechanical strength and good chemical stability. Salen ligands are covalently grafted onto the support surface, and metal ions are firmly loaded through coordination bonds, avoiding ligand detachment and metal ion loss during catalysis. The catalyst can be separated and recovered by simple filtration. After being reused 5 to 8 times, the catalytic activity still retains more than 70% of the initial activity, reducing production costs and environmental pressure.

[0044] The preparation process is simple and the conditions are mild: the entire preparation process does not require harsh reaction conditions (such as high temperature, high pressure, and highly corrosive reagents), the steps are highly controllable, and it is suitable for industrial-scale production; the metal loading can be flexibly controlled by adjusting the concentration of the metal salt solution and the reaction time to adapt to different copolymerization reaction requirements.

[0045] The copolymer products exhibit excellent performance: When catalyzing the copolymerization of cyclohexane oxide, this catalyst demonstrates high catalytic activity and high copolymerization selectivity. The number average molecular weight of the products is 10,000~100,000 g / mol, with a narrow molecular weight distribution (PDI=1.2~1.8), regular structure, and good mechanical properties and thermal stability, which can meet the application requirements of engineering plastics, high-end coatings and other fields. Attached Figure Description

[0046] Figure 1 The images show the infrared spectra of the catalyst precursors and catalysts prepared in Examples 1, 3, and 4.

[0047] Figure 2 The following are BET diagrams of the catalysts prepared in Example 3.

[0048] Figure 3The image shows the pore size distribution of each catalyst prepared in Example 3.

[0049] Figure 4 The TGA images are of the catalysts prepared in Example 3.

[0050] Figure 5 For the catalytic product polycarbonate 1 H NMR spectrum. Detailed Implementation

[0051] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways than those described herein, and similar modifications can be made by those skilled in the art without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It should be noted that the reagents and other materials used in these embodiments are all commercially available products.

[0053] Example 1: Preparation of the chloride-modified compound Mc-CHO

[0054] Chlorine beads (Shanghai Yuang Waterborne New Materials Technology Co., Ltd.) were dried in a vacuum oven at 80 ℃ for 24 hours. Chlorine beads (2.00 g, 9.71 mmol (molar amount based on chlorine content in the beads, 17 wt%)) and salicylaldehyde (1.18 g, 1.0 Eq) were weighed into a double-necked flask, and 30 mL of anhydrous chloroform was added. The mixture was then swelled at 65 ℃ for 12 hours under a nitrogen atmosphere. After swelling was complete, anhydrous AlCl3 (3.87 g, 29.1 mmol, 3.0 Eq) was rapidly added after cooling to room temperature. The mixture was stirred at room temperature for 12 hours, then heated to 65 ℃ and refluxed for another 12 hours. After the reaction was completed, the mixture was cooled to room temperature and poured into a methanol solvent containing 3% HCl to quench unreacted aluminum trichloride. The solid was collected and then soaked three times in methanol, dichloromethane, and N,N-dimethylformamide (DMF) in sequence. Finally, the collected solid was subjected to Soxhlet extraction with methanol for 24 hours and then dried in a vacuum oven at 80 °C for 12 hours to obtain 2.32 g of light yellow solid powder Mc-CHO, with a yield of 84.1%.

[0055] Example 2: Preparation of salon monomers A1, A2, A3, A4, and A5 from different diamine monomers

[0056] (1) Preparation of salon monomer A1:

[0057] In a three-necked flask, o-phenylenediamine (23.8 g, 0.220 mol) and 100 mL of anhydrous ethanol were added. The mixture was heated and stirred at 80°C under nitrogen protection until dissolved (the solution was dark red). Then, 120 mL of anhydrous ethanol containing 3-methoxysalicylaldehyde (30.4 g, 0.200 mol) was slowly added dropwise to the system through a constant pressure dropping funnel. The mixture was refluxed for 5 hours, cooled, and filtered to obtain a yellow solid. The solid was dried in a vacuum oven at 60 °C for 12 hours to obtain 35.5 g of solid, with a yield of 73.8%.

[0058] The reaction equation is as follows:

[0059]

[0060] (2) Preparation of salon monomer A2:

[0061] All steps were the same as in A1, except that the same amount of 1,2-cyclohexanediamine was used instead of o-phenylenediamine. After filtration and drying, the sample yielded a yellow powder, 32.6 g, with a yield of 65.6%.

[0062] The reaction equation is as follows:

[0063] .

[0064] (3) Preparation of salon monomer A3:

[0065] All steps were the same as in A1, except that the same amount of hexamethylenediamine was used instead of o-phenylenediamine. After filtration and drying, the sample yielded a yellow powder, 29.2 g, with a yield of 75.2%.

[0066] The reaction equation is as follows:

[0067] .

[0068] (4) Preparation of salon monomer A4:

[0069] All steps were the same as in A1, except that 3-methoxysalicylaldehyde was used instead of the same amount of salicylaldehyde. After filtration and drying, the sample yielded a pale yellow powder, 33.2 g, with a yield of 76.0%.

[0070] The reaction equation is as follows:

[0071]

[0072] (5) Preparation of salon monomer A5:

[0073] All steps were the same as in A1, except that 3-tert-butylsalicylaldehyde was used instead of 3-methoxysalicylaldehyde in the same amount. After filtration and drying, the sample yielded a yellow powder, 36.7 g, with a yield of 66.9%.

[0074] The reaction equation is as follows:

[0075] .

[0076] Example 3: Preparation of catalyst Mc-Salen-Co(III)Zn using salen monomer

[0077] 1) Preparation of Mc-Salen1-CoZn: Mc-CHO (2.00 g) was first added to a two-necked round-bottom flask, followed by 50 mL of DMF. The mixture swelled at 85 °C for 6 hours under nitrogen protection. Then, monomer A1 (1.76 g, 7.28 mmol) was dissolved in 35 mL of DMF containing 15 µL of glacial acetic acid, and slowly added dropwise to the reaction system using a constant-pressure dropping funnel. After the addition was complete, the mixture was reacted at 85 °C for 24 hours to obtain an orange solid product. The filtered sample was washed sequentially with dichloromethane, ethanol, and DMF, and then subjected to Soxhlet extraction with dichloromethane for 24 hours. Finally, it was dried in a vacuum oven at 65 °C for 12 hours to obtain 2.31 g of orange solid powder Mc-Salen1, with a yield of 86.6%.

[0078] Weigh 2.00 g of Mc-Salen1 into a 250 mL double-necked round-bottom flask, disperse it in 50 mL of DMF and allow it to swell for 12 hours. Then, under a nitrogen atmosphere, add 50 mL of DMF solution containing cobalt acetate tetrahydrate (1.20 g, 4.85 mmol) and anhydrous zinc acetate (0.90 g, 4.85 mmol) dropwise into the flask through a constant-pressure dropping funnel. After the addition is complete, continue heating and stirring at 100 °C for 24 hours. After the reaction is complete, cool to room temperature, filter the reddish-brown solid and wash it several times with DMF and ethanol using ultrasonication. Then, extract the sample with ethanol at 115 °C for 24 hours using a Soxhlet extractor. Finally, dry the sample in a vacuum oven at 75 °C for 12 hours to obtain 2.24 g of deep yellow solid powder (Mc-Salen1-Co(II)Zn), with a yield of 95.6%.

[0079] Mc-Salen 1-Co(II)Zn 2.00 g was placed in a 250 mL double-necked round-bottom flask, and 50 mL of dried DMF was added. The mixture was stirred and swollen at room temperature for 12 h under a nitrogen atmosphere. A DMF solution of p-toluenesulfonic acid monohydrate (concentration 0.3 mol / L) was slowly added via a constant-pressure dropping funnel. The p-toluenesulfonic acid monohydrate reacts with the Co in the precursor... 2+ The molar ratio of the reactants was 2:1, and the dropping rate was controlled at 1-2 drops / second. After the addition was complete, the atmosphere was replaced with oxygen, and the reaction temperature was raised to 50°C. After the reaction was completed, the reaction mixture in the flask was filtered, washed, dried, and the dark brown solid product was collected to obtain approximately 1.86 g of Mc-Salen1-Co(III)Zn (containing some Mc-Salen1-Co(III) and Mc-Salen1-Zn), with a yield of 93.0%.

[0080]

[0081] 2) The preparation process of Mc-Salen2-CoZn is the same as that of Mc-Salen1-CoZn, using the same amount of A2 monomer instead of A1, and the other steps are completely identical. A dark brown solid product, Mc-Salen2-Co(III)Zn (containing some Mc-Salen2-Co(III) and Mc-Salen2-Zn), was obtained, approximately 1.92 g, with a yield of 96.0%.

[0082]

[0083] 3) The preparation process of Mc-Salen3-CoZn is the same as that of Mc-Salen1-CoZn, using the same amount of A3 monomer instead of A1, and the other steps are completely identical. A dark brown solid product, Mc-Salen3-Co(III)Zn (containing some Mc-Salen3-Co(III) and Mc-Salen3-Zn), was obtained, approximately 1.74 g, with a yield of 87.0%.

[0084]

[0085] 4) The preparation process of Mc-Salen4-CoZn is the same as that of Mc-Salen1-CoZn, using the same amount of A4 monomer instead of A1, and the other steps are completely identical. A dark brown solid product, Mc-Salen4-Co(III)Zn (containing some Mc-Salen4-Co(III) and Mc-Salen4-Zn), was obtained, approximately 1.82 g, with a yield of 91.0%.

[0086]

[0087] 5) The preparation process of Mc-Salen5-CoZn is the same as that of Mc-Salen1-CoZn, using the same amount of A3 monomer instead of A1, and the other steps are completely identical. A dark brown solid product, Mc-Salen3-Co(III)Zn (containing some Mc-Salen5-Co(III) and Mc-Salen5-Zn), was obtained, approximately 1.91 g, with a yield of 95.5%.

[0088]

[0089] Example 4 Synthesis of small molecule Salen-CoZn catalyst

[0090] 1) 3-Methoxysalicylaldehyde (3.34 g, 0.022 mol) and 30 mL of anhydrous ethanol were added to a 250 mL two-necked flask. The solution was dissolved by heating and stirring at 80 °C under nitrogen protection (the solution was yellow). Then, 50 mL of anhydrous ethanol containing 1,2-cyclohexanediamine (1.14 g, 0.010 mol) was slowly added dropwise, and the mixture was refluxed for 12 hours. After cooling, the solution was filtered to obtain an orange-yellow solid. This solid was dried in a vacuum oven at 65 °C for 12 hours to obtain 3.35 g of orange-yellow solid, with a yield of 87.7%, named Salen-methoxy. The synthetic route is shown below:

[0091] .

[0092] 2) In a 250 mL two-necked flask, add 50 mL of anhydrous ethanol and the above-mentioned Salen-methoxy small molecule (3.06 g, 8.00 mmol), and heat to 80 °C under nitrogen protection at 360 r / min. -1 The mixture was stirred at a speed of [speed value missing] until the solid was completely dissolved. Then, 80 mL of anhydrous ethanol solution containing anhydrous zinc acetate (2.94 g, 1.60 mmol) was slowly added dropwise to the system. The reaction was continued for 12 hours, cooled, and filtered to obtain 3.26 g of reddish-brown product with a yield of 91.4%, which was named Salen-Zn.

[0093] The synthesis route is as follows:

[0094] .

[0095] 3) In a double-necked flask, add 50 mL of anhydrous ethanol and the above-mentioned Salen-methoxy small molecule (3.06 g, 8.00 mmol), and heat to 80 °C under nitrogen protection at 360 r / min. -1The mixture was stirred at a constant speed until the solid was completely dissolved. Then, 80 mL of anhydrous ethanol solution containing cobalt acetate tetrahydrate (3.98 g, 1.60 mmol) was slowly added dropwise to the system, and the reaction was continued for 12 hours. After cooling, an ethanol solution of p-toluenesulfonic acid monohydrate (concentration 0.3 mol / L, molar ratio of p-toluenesulfonic acid monohydrate to Co²⁺ in the precursor was 2:1) was slowly added through a constant pressure dropping funnel at a dropping rate of 1-2 drops / second. After the addition was complete, the atmosphere was replaced with oxygen, and the reaction temperature was raised to 50 °C. After the reaction was completed, the reaction mixture in the flask was filtered, washed, and dried to obtain 3.17 g of reddish-brown product, with a yield of 90.2%. This product was named Salen-Co.

[0096] The synthesis route is as follows:

[0097] .

[0098] Example 5

[0099] Synthesis of monometallic catalysts Mc-Salen2-Co(III) and Mc-Salen2-Zn. The preparation process of Mc-Salen2-Co(III) is the same as that of Mc-Salen2-Co(III)Zn, except that only 9.7 mmol of cobalt acetate tetrahydrate is used as the metal precursor to obtain the light brown product Mc-Salen2-Co(III).

[0100] The preparation process of Mc-Salen2-Zn is the same as that of Mc-Salen2-Co(Ⅲ)Zn, except that only 9.7 mmol of anhydrous zinc acetate is used as a metal precursor to obtain the dark yellow product Mc-Salen2-Zn catalyst.

[0101] Synthesis of Mc-Salen2-Zn+Mc-Salen2-Co(Ⅲ) mixed catalyst.

[0102] The preparation process of Mc-Salen2-Co(III) is the same as that of Mc-Salen2-Co(III)Zn, except that only 4.85 mmol of cobalt acetate tetrahydrate is used as the metal precursor and 1 g of Mc-Salen1 is used as the support to obtain the light brown product Mc-Salen2-Co(III).

[0103] The preparation process of Mc-Salen2-Zn is the same as that of Mc-Salen2-Co(III)Zn, except that only 4.85 mmol of anhydrous zinc acetate is used as a metal precursor to obtain the dark yellow product Mc-Salen2-Zn catalyst.

[0104] The light brown product Mc-Salen2-Co(Ⅲ) and the dark yellow product Mc-Salen2-Zn catalyst are mixed to obtain the Mc-Salen2-Zn+Mc-Salen2-Co(Ⅲ) mixed catalyst.

[0105] Figure 1 The images show the infrared spectra of the catalyst precursors and catalysts prepared in Examples 1, 3, and 4. The infrared spectrum of the support Mc is located at 1263 cm⁻¹. -1 and 671 cm -1 The characteristic absorption peak of C-Cl appeared at 1625 cm⁻¹, which is attributed to the characteristic stretching vibration of chloromethyl groups. Meanwhile, the Salen structure showed an absorption peak at 1625 cm⁻¹. -1 A distinct C=N characteristic peak appeared at 1652 cm⁻¹. Mc-CHO peaked at 1652 cm⁻¹. -1 The presence of a C=O characteristic peak indicates that the aldehyde group has not yet reacted. However, no C=O characteristic peak was found in Mc-Salen and Mc-Salen2-Co(Ⅲ)Zn, but a C=N characteristic peak was found, proving that the Schiff base reaction occurred successfully and the Salen structure was successfully formed.

[0106] Figure 2 The images show the BET plots of the catalysts prepared in Example 3. The chlorine spheres exhibit Type IV adsorption-desorption curves, showing minimal adsorption at low relative pressures (P / P0 < 0.01 bar), and a significant hysteresis loop in the high-pressure region (0.8-1.0 bar), indicating that this material is primarily mesoporous. At relative pressures greater than 0.9 bar, the adsorption curve shows an increasing upward trend, indicating the presence of macroporous structures within the framework. The specific surface area of ​​the chlorine spheres is 66 m². 2 g -1 The low specific surface area of ​​the material may be attributed to the fact that it is mainly a linear polymer, and the pores generated during the polymerization process are mostly mesopores and macropores.

[0107] The Mc-Salen series samples exhibited a rapid increase in adsorption curves at relatively low pressures, a typical characteristic of microporous materials, classifying them as Type I adsorption-desorption curves, indicating abundant microporous structures within the polymer framework. Calculations show that the specific surface areas of Mc-Salen1-Co(Ⅲ)Zn, Mc-Salen2-Co(Ⅲ)Zn, Mc-Salen3-Co(Ⅲ)Zn, and Mc-Salen are 453 m², respectively. 2 g -1 430 m 2 g -1 402 m 2 g -1 and 380 m 2 g -1 .

[0108] Figure 3 The image shows the pore size distribution of the catalysts prepared in Example 3. The pore size distribution curves were obtained by fitting the nitrogen adsorption-desorption curves using nonlocal density functional theory (NLDFT). The pore size of the chlorine spheres is mainly in the mesoporous range (3-10 nm). The other four samples have predominantly pore sizes below 2 nm, indicating the presence of abundant microporous structures.

[0109] Figure 4 The images show the TGA graphs of the catalysts prepared in Example 3. The polymer backbone crosslinking resulting from the Friedel-Crafts reaction and the strong coordination with M-Salen can significantly improve the thermal stability of the materials. Compared to chlorospheres, the Mc-Salen series polymers exhibit better thermal stability, with a slower initial weight loss rate at 250 °C and a significantly reduced rapid weight loss rate near 480 °C.

[0110] Application Example 1

[0111] The catalysts Mc-Salen1-Co(Ⅲ)Zn, Mc-Salen2-Co(Ⅲ)Zn and Mc-Salen3-Co(Ⅲ)Zn prepared in Example 3 were applied to the copolymerization reaction of cyclohexane oxide and CO2.

[0112]

[0113] The amount of cyclohexane oxide used as the raw material was 3 ml, the amount of catalyst was 50 mg, the CO2 pressure was 3.0 MPa, and the target product was polycarbonate. The reaction temperature was 80 ℃, and the reaction time was 24 h. After the reaction was completed, the product was completely dissolved in dichloromethane, then precipitated with methanol, and finally filtered, washed, and dried to obtain the target product.

[0114] Table 1 Catalytic effects of different amine structures of the catalyst Mc-Salen-Co(III)Zn

[0115]

[0116] Figure 5 For Mc-Salen 2-Co(III)Zn catalytic products polycarbonate 1 The 1H NMR spectrum shows that this catalyst has excellent catalytic effect on the copolymerization reaction of CO2 and cyclohexane oxide, and the NMR signal at 4.6 ppm confirms the successful synthesis of polycarbonate. The weak signal at 3.5 ppm indicates the presence of some side reactions, namely, the self-polymerization of cyclohexane oxide via ether bonds.

[0117] Application Example 2

[0118] The catalysts Salen-Zn and Salen-Co(III) prepared in Example 4 were applied to the copolymerization reaction of cyclohexane oxide and CO2. The amount of cyclohexane oxide as the raw material was 3 ml, the amount of catalyst was 50 mg, the CO2 pressure was 3.0 MPa, and the target product was polycarbonate. The reaction temperature was 80 °C, and the reaction time was 24 h. After the reaction was completed, the product was completely dissolved in dichloromethane, then precipitated with methanol, and finally filtered, washed, and dried to obtain the target product.

[0119] Table 2 Catalytic effect of small molecule catalyst Salen-Co / Zn

[0120]

[0121] Application Example 4

[0122] The catalysts prepared in Example 5, namely Mc-Salen2-Zn, Mc-Salen2-Co(III), and the mixed catalyst of Mc-Salen2-Zn + Mc-Salen2-Co(III), were applied to the copolymerization reaction of cyclohexane oxide and CO2. The amount of cyclohexane oxide as the raw material was 3 ml, the amount of catalyst was 50 mg, the CO2 pressure was 3.0 MPa, and the target product was polycarbonate. The reaction temperature was 80 °C, and the reaction time was 24 h. After the reaction, the product was completely dissolved in dichloromethane, then precipitated with methanol, and finally filtered, washed, and dried to obtain the target product.

[0123] Table 3 Catalytic effect of Mc-Salen2-Zn / Co(III)

[0124]

[0125] As shown in Table 3, Mc-Salen2-Co(III) exhibits the best catalytic activity. This is because Mc-Salen2-Co(III) is a highly active cationic center, serving as the core site for chain initiation and propagation. Its catalytic activity is highly dependent on the dynamic exchange between coordination vacancies and axial ligands. In contrast, Mc-Salen2-Zn is a neutral Lewis acid site with weak nucleophilicity, resulting in significantly lower chain initiation / propagation capabilities compared to Mc-Salen2-Co(III), leading to lower conversion and selectivity. The mixed system of Mc-Salen2-Zn + Mc-Salen2-Co(III) is a simple physical mixture of two independent active sites, failing to achieve a precise synergistic effect. Instead, it negatively impacts the catalytic performance of the Co(III) active center, leading to a decrease in intrinsic activity. Therefore, the Co and Zn bimetallic active sites in the Mc-Salen-Co(III)Zn catalyst of this application demonstrate a synergistic effect, jointly enhancing the catalytic activity.

[0126] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres, characterized in that, It has the following basic structural units, Where M1=M2=Zn 2+ Co 3+ ; and / or M1 and M2 are Zn 2+ Co 3+ Any one of them, and M1 and M2 are different; The term refers to a diamine monomer, wherein the diamine monomer is any one of o-phenylenediamine, 1,2-cyclohexanediamine, or ethylenediamine; R can be any one of H, methoxy, or tert-butyl.

2. The preparation method of the porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 1, characterized in that, Includes the following steps: S1, Modification of Chlorine Balls Commercially available chlorinated spheres were dried and swollen, then salicylaldehyde was added. Salicylaldehyde was grafted onto the chlorinated spheres using an AlCl3-catalyzed Friedel-Crafts reaction to obtain the chlorinated sphere modified compound Mc-CHO. S2, Synthesis of small molecule salon ligands In a nitrogen atmosphere, the diamine monomer is dissolved in anhydrous ethanol, and salicylaldehyde or its substituted derivatives are added dropwise. ethanol solution A reflux reaction was carried out to obtain the small molecule salon ligand. The reaction equation is as follows: , Wherein, R is any one of H, methoxy or tert-butyl; Synthesis of S3 and Chloride Ball Salen The chlorine sphere modified compound obtained in step S1 was fully swollen, and a small molecule salen ligand was added to undergo an imine exchange reaction. The small molecule salen ligand was loaded onto the catalyst precursor. After the reaction was completed, the catalyst was washed and dried to obtain a porous salen heterogeneous catalyst based on chlorine spheres. S4, loading of metal ions The porous Salen heterogeneous catalyst based on chloride spheres obtained in step S3 was fully swollen, and then a Co-containing catalyst was added. 2+ With Zn 2+ A metal salt mixture solution was subjected to metal loading and coordination reaction at 25–60 °C for 1–6 h. After the reaction, the mixture was filtered, washed, and dried to obtain a coordination-stable porous Co(II)Zn-Salen-based heterogeneous catalyst based on chloride spheres; wherein, Co… 2+ With Zn 2+ The molar ratio is 1:1; Oxidation of S5 and Co The porous Co(II)Zn-Salen-based heterogeneous catalyst based on chlorine spheres obtained in step S4 was fully swollen and oxidized in an oxygen atmosphere using p-toluenesulfonic acid as a catalyst to obtain a porous Co(III)Zn-Salen-based heterogeneous catalyst based on chlorine spheres.

3. The method for preparing a porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 2, characterized in that, In step S1, the temperature of the Friedel-Crafts reaction is 45–95 °C, and the reaction time is 10–48 h.

4. The method for preparing a porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 2, characterized in that, In step S1, the chlorine content of the chlorine balls is 1.5~4.0 mmol / g, and the particle size is 50~500 μm.

5. The method for preparing a porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 2, characterized in that, In step S2, the reflux reaction temperature is 70-90℃ and the time is 5-8 h.

6. The method for preparing a porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 2, characterized in that, In step S3, the imine exchange reaction is carried out at a temperature of 80–120°C for 12–48 h.

7. The method for preparing a porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 2, characterized in that, The porous Co(III)Zn-Salen-based heterogeneous catalyst based on chlorine spheres has a pore size of 2–15 nm and a specific surface area of ​​100–500 m². 2 / g.

8. The method for preparing a porous CoZn-Salen-based heterogeneous catalyst based on chloride spheres according to claim 7, characterized in that, The total content of metal ions in the heterogeneous catalyst is 5 wt% to 18 wt%.

9. The application of the porous CoZn-Salen-based heterogeneous catalyst based on chlorine spheres as described in claim 1 in the catalytic synthesis of polycarbonate from carbon dioxide and epoxides.

10. The application according to claim 9, characterized in that, The epoxide is cyclohexane oxide.

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