A porphyrin-triazine framework-supported nanosilver catalyst and its preparation method and application

Abstract

The invention discloses a porphyrinyl triazine framework-supported nano-silver catalyst and its preparation method and application. 5,10,15,20-tetrakis (4-aminophenyl) porphyrin and cyanuric chloride are used as raw materials. The porphyrinyl triazine framework is synthesized by reflux stirring reaction for 72h under alkaline conditions. The framework is then stirred with a tetrahydrofuran solution of tetrafluoroborate at room temperature and in the dark for 1h, heated to 80 DEG C and stirred for 24h. After filtration, solvent washing and vacuum drying, the porphyrinyl triazine framework-supported nano-silver catalyst is obtained. The preparation process of the present invention is simple, the catalyst yield and purity are high, the obtained porphyrin porous polymer-supported nano-silver catalyst is under solvent-free conditions, with 1,8-diazacyclo [5,4,0] undecene-7 as a co-catalyst, and efficiently and selectively catalyzes CO2 and propargyl alcohol derivatives to convert into α-alkylene cyclic carbonates, and the catalyst recovery and regeneration process is simple and has good reusability. It belongs to the field of heterogeneous catalyst technology.

Description

Technical Field

[0001] The invention belongs to the technical field of heterogeneous catalysts, and particularly relates to a preparation method of a porphyrinyl triazine framework-supported nanosilver catalyst and an application of the catalyst in catalyzing the synthesis of α-alkylene cyclic carbonates from carbon dioxide and a propargyl alcohol compound. Background Art

[0002] The continuous depletion of fossil energy has led to rising levels of carbon dioxide (CO2) in the air, triggering a series of ecological and environmental crises. Currently, carbon capture, utilization, and storage (CCUS) is an important means to effectively alleviate environmental and energy shortage issues. From the perspective of green and sustainable development, rationally designed process technologies can be used to catalytically convert CO2 into high-value-added chemicals, thereby generating high-value-added chemical raw materials and energy resources. Among the many reactions involving CO2, the carboxyl cyclization reaction of CO2 with propargyl alcohol derivatives to synthesize α-alkylene cyclic carbonates is an environmentally friendly and carbon-neutral method with 100% atom economy (Green Chem., 2021, 23, 9334). More importantly, α-alkylene cyclic carbonates have broad application prospects in new materials and fine chemicals, serving as polar aprotic solvents, monomers for the synthesis of polycarbonates and polyurethanes, and intermediates in organic synthesis (Catalysts, 2022, 12, 73; Angew. Chem. Int. Ed. 2022, e202114817).

[0003] For the carboxyl cyclization reaction of CO2 and propargyl alcohol derivatives, researchers have developed many catalysts, including metal (Cu, Co, Zn, Ag, Ru)-based catalysts, ionic liquid catalysts and organic catalysts (ChemSusChem, 2021, 14, 2367; ACS Appl. Mater. Interfaces, 2021, 13, 45558). In general, silver-based catalysts have been widely studied in the past few years and have shown good catalytic performance. For example, Wang and colleagues reported an alkaline ionic liquid / AgOAc system to synthesize α-alkylene cyclic carbonates from CO2 at normal pressure. Since the alkaline ionic liquid has the dual role of absorbent and activator, excellent yields were obtained (Chem. Commun., 2016, 52, 7830). However, most of these existing catalytic systems are homogeneous catalytic systems. Obviously, from the perspective of separation and recovery, silver-based heterogeneous catalysts have greater industrial application value. It is generally believed that the mechanism of nanosilver catalysis of this reaction is similar to that of Ag. +The catalytic mechanism is similar. Therefore, heterogeneous catalytic systems based on nanosilver have attracted widespread research interest in recent years (Inorg.Chem., 2020, 59, 9765; ACSSustainable Chem.Eng., 2020, 8, 7051-7058). However, due to its high surface energy, nanosilver usually has inherent insufficient thermodynamic stability, which makes it easy to aggregate and then lose activity in the catalytic reaction. At this time, a suitable carrier not only plays an important role in enhancing the stability of the catalyst and improving the catalytic performance, but also facilitates the recovery of the catalyst.

[0004] Porous organic polymers (POPs) have attracted considerable attention as an ideal heterogeneous catalytic platform due to their unique structural and functional advantages (Green Chem. Eng., 2022, 3, 96). Importantly, the abundant nanopores and CO2-philic heteroatoms in the polymer network can promote the enrichment of CO2, playing a key role in promoting its activation and conversion under mild conditions (Curr. Opin. Green Sustain. Chem., 2020, 26, 100365).

[0005] In addition, the micro-mesoporous structure is conducive to promoting the diffusion of reactants in the internal pores. For example, Han et al. reported a biomass-based porous organic polymer (GA-azo-POP)-supported AgNPs catalyst (Ag / GA-azo-POP, as shown in the figure below). When 1,8-diazabicyclo[5.4.0]undec-7-ene was used as a co-catalyst, the use of Ag was very low (0.14 mol%). It can effectively catalyze the carboxylation of CO2 (Green Chem., 2018, 20, 4655). Li reported a bifunctional urea conjugated porous polymer (UCPP)-supported nanosilver catalyst, which can smoothly catalyze the reaction of CO2 with propargyl alcohol to synthesize the corresponding cyclic carbonate at room temperature (Dalton. Trans., 2020, 49, 13052). Recently, our research group developed a nanosilver-supported tubular porous porphyrin network catalyst (Ag@NT-PPN). Porphyrin has been shown to effectively chelate and stabilize nanosilver. The catalyst also exhibited excellent catalytic activity, product selectivity, substrate scalability, and reusability in the reaction of CO₂ with propargyl alcohol to produce α-alkylene cyclic carbonates (Asian J. Org. Chem., 2022, 11, e202200194). However, the synthesis of Ag@NT-PPN is complex, and the porphyrin-based polymer support cannot be synthesized in a single step. Furthermore, the preparation of the porphyrin-based polymer support requires a large amount of anhydrous ferric chloride as a catalyst, and strong acid is required during the demetallation process. These findings provide a valuable reference for the subsequent development of heterogeneous catalytic materials with similar structural and functional characteristics.

[0006] Therefore, developing a greener and simpler synthetic strategy to prepare porphyrin porous polymer-supported nanosilver catalysts that can be used to efficiently and stably catalyze CO2 carboxylation reactions still has great basic research significance and application value. Summary of the Invention

[0007] The first object of the present invention is to provide a porphyrin-triazine framework-loaded nanosilver catalyst, which has a porphyrin, secondary amine and triazine structure, can play a good chelating and stabilizing role on nanosilver, and can play a good selective adsorption and enrichment role on CO2 during the catalytic process, thereby improving the catalytic efficiency.

[0008] The second object of the present invention is to provide a method for preparing the above catalyst, which has a simple preparation process, readily available raw materials, high yield and purity, and all reaction solvents can be recovered.

[0009] The third object of the present invention is to provide the above-mentioned catalyst for catalyzing the reaction of CO2 and propargyl alcohol to prepare α-alkylene cyclic carbonate. The reaction does not require the addition of solvent and can be carried out efficiently and selectively at room temperature and pressure.

[0010] To this end, the first technical solution provided by the present invention is as follows:

[0011] A porphyrinyl triazine framework-supported nanosilver catalyst, the structural formula of which is shown in formula (I):

[0012]

[0013] The second technical solution provided by the present invention is a method for preparing a porphyrinyl triazine framework-supported nanosilver catalyst. The method uses 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and cyanuric chloride as raw materials, synthesizes a porphyrinyl triazine framework under alkaline conditions, reacts with a tetrahydrofuran solution of silver tetrafluoroborate under dark conditions, and then filters, washes with a solvent multiple times, and vacuum-dries to obtain the porphyrinyl triazine framework-supported nanosilver catalyst.

[0014] The specific steps include:

[0015] (1) 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and cyanuric chloride in a molar ratio of 1:1 to 3 were added to a round-bottom flask containing a solvent, and the solvent and acid binding agent were continuously added. After stirring at room temperature for 0.5 h, the mixture was heated to reflux and reacted for 72 h. The resulting precipitate was filtered and washed, and then vacuum-dried at 100° C. for 12 h to obtain a porphyrin-based triazine framework containing a secondary amino group.

[0016] (2) Add silver tetrafluoroborate in tetrahydrofuran to a round-bottom flask and stir evenly at room temperature to obtain a tetrahydrofuran solution containing silver nitrate. Then add the porphyrinyl triazine framework containing a secondary amino group obtained in step 1) to the round-bottom flask. Stir in the dark at room temperature for 1 hour, continue heating to 80°C, react for 24 hours, filter, wash with the solvent several times, and vacuum dry at 100°C for 12 hours to obtain a porphyrinyl triazine framework-supported nanosilver catalyst.

[0017] Furthermore, the solvent in step 1) is any one of tetrahydrofuran, 1,2-dioxane, N,N-dimethylformamide, and dimethyl sulfoxide;

[0018] Furthermore, the acid-binding agent in step 1) is intended to provide alkaline reaction conditions to remove HCl generated during the reaction, thereby promoting the polymerization reaction, and is any one of potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, triethylamine, and N,N-diisopropylethylamine;

[0019] Furthermore, the amount of the acid binding agent in step 1) is 2.5 to 7.5 times the amount of cyanuric chloride;

[0020] Furthermore, in step 1), the washing is performed by combining filtration and Soxhlet extraction, wherein the filtration and washing solvents are 50 to 150 mL of methanol, N,N-dimethylformamide, tetrahydrofuran, and dichloromethane, respectively, and the Soxhlet extraction uses 300 mL of tetrahydrofuran as the solvent, and the extraction time is 24 hours;

[0021] Furthermore, in step 2), the mass ratio of the porphyrinyl triazine framework to silver tetrafluoroborate is 100:2-10;

[0022] Furthermore, the concentration of the silver nitrate tetrahydrofuran solution in step 2) is 1 to 5 mg / 10 mL;

[0023] The third technical solution of the present invention is the use of a porphyrinyl triazine framework-supported nanosilver catalyst in the catalytic synthesis of α-alkylene cyclic carbonates from CO2 and propargyl alcohol compounds.

[0024] The method for synthesizing an α-alkylene cyclic carbonate by catalyzing a reaction of CO2 and a propargyl alcohol compound using a porphyrinyl triazine framework-supported nanosilver catalyst comprises the following steps in sequence: without adding any solvent, a certain volume concentration of CO2 and 1 mmol of propargyl alcohol having a structural formula as described in formula (II) are reacted under a certain temperature and pressure with constant stirring for 5 to 48 hours in the presence of the porphyrinyl triazine framework-supported nanosilver catalyst and a certain amount of 1,8-diazacyclo[5,4,0]undecene-7 as a co-catalyst to obtain an α-alkylene cyclic carbonate having a structural formula as described in formula (III);

[0025] In the above steps, the CO2 with a certain volume concentration is 15 to 100% CO2, and the CO2 with a concentration lower than 100% is obtained by mixing any inert gas selected from nitrogen, helium, neon or argon into the CO2 gas;

[0026] The epoxide in the above steps has a structural formula as shown in formula (II):

[0027]

[0028] The α-alkylene cyclic carbonate described in the above steps has a structural formula as shown in formula (III):

[0029]

[0030] The amount of 1,8-diazacyclo[5,4,0]undecene-7 in the above step is 0.5 to 2.5 mmol, preferably 1 mmol;

[0031] In the above steps, the amount of the porphyrinyl triazine framework-supported nanosilver catalyst is 5 to 50 mg, preferably, the amount of the catalyst c is 20 mg;

[0032] The pressure in the above steps is 0.1-5.0 MPa, and preferably, the reaction pressure is 1.0 MPa;

[0033] The reaction temperature in the above steps is 25-80°C, preferably 40°C;

[0034] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0035] 1. The preparation method of the porphyrinyl triazine framework-supported nanosilver catalyst provided by the present invention is simple, the raw materials are readily available, the yield and purity are high, all the reaction solvents can be recycled, and the obtained catalyst is stable to air and water.

[0036] 2. The porphyrin-triazine framework-loaded nanosilver catalyst prepared by the present invention has porphyrin, triazine and secondary amine structures, which can play a good chelating and stabilizing role on nanosilver, and can play a good selective adsorption and enrichment role on CO2 during the catalytic process, thereby improving the catalytic efficiency; in particular, when low-concentration CO2 is used as a raw material, it can smoothly convert it into cyclic carbonate, which can effectively reduce the energy consumption generated in the process of obtaining pure CO2, and realize the coupling of CO2 selective capture and catalytic conversion.

[0037] 3. The porphyrinyl triazine framework-supported nanosilver catalyst provided by the present invention is used to catalyze the reaction of CO2 and propargyl alcohol to prepare α-alkylene cyclic carbonate. The reaction does not require the addition of solvent and can be carried out efficiently and selectively at room temperature and pressure. The catalyst recovery and regeneration process is simple and has good reusability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 TEM image of the porphyrin-triazine framework-supported nanosilver catalyst provided in Example 1;

[0039] Figure 2 XPS graph of the porphyrin-triazine framework-supported nanosilver catalyst provided in Example 1

[0040] Figure 3 α-alkylene cyclic carbonate (2a) synthesized in Example 2 1 HNMR spectrum;

[0041] Figure 4 α-alkylene cyclic carbonate (2b) synthesized in Example 3 1 H NMR spectrum;

[0042] Figure 5 α-alkylene cyclic carbonate (2c) synthesized in Example 4 1 HNMR spectrum;

[0043] Figure 6 α-alkylene cyclic carbonate (2d) synthesized in Example 5 1 H NMR spectrum;

[0044] Figure 7 α-alkylene cyclic carbonate (2e) synthesized in Example 6 1 HNMR spectrum;

[0045] Figure 8 α-alkylene cyclic carbonate (2f) synthesized in Example 7 1 H NMR spectrum;

[0046] Figure 9 α-Alkylene cyclic carbonate synthesized in Example 8 (2 g) 1 H NMR spectrum. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below by way of examples. However, these examples are for illustrative purposes only and should not be construed as limiting the present invention in any way.

[0048] Example 1

[0049] This embodiment provides a porphyrinyl triazine framework-supported nanosilver catalyst, which is prepared by the following steps:

[0050] 1) Synthesis of porphyrin-triazine framework

[0051] To a 150 mL round-bottom flask, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (1 mmol, 0.674 g), cyanuric chloride (2 mmol, 0.369 g), 60 mL of tetrahydrofuran, and potassium carbonate (4 mmol, 0.553 g) were added. The mixture was stirred at room temperature for 0.5 h and then refluxed in a 70°C reaction bath for 72 h. The resulting precipitate was washed three times with methanol (60 mL), ethyl N,N-dimethylformamide (100 mL), tetrahydrofuran (60 mL), and dichloromethane (60 mL). The precipitate was then purified by Soxhlet extraction with 300 mL of tetrahydrofuran for 24 h. The resulting solid was dried under vacuum at 100°C for 24 h to yield 0.866 g of the porphyrinyl triazine framework.

[0052] 2) Preparation of porphyrin-triazine framework-supported nanosilver catalyst

[0053] Add 15 mg of silver tetrafluoroborate to a 100 mL volumetric flask and add tetrahydrofuran to the mark to obtain a tetrahydrofuran solution with a silver tetrafluoroborate concentration of 1.5 mg / 10 mL. Set aside. Add 500 mg of the porphyrinyl triazine framework prepared in Example 1 to a 100 mL round-bottom flask and dropwise add the silver tetrafluoroborate tetrahydrofuran solution over 1 hour in the dark at room temperature. Continue heating to 80°C and react for 24 hours. After filtration, wash with the solvent several times, and vacuum dry at 100°C for 24 hours, 0.479 g of the porphyrinyl triazine framework-supported nanosilver catalyst is obtained. TEM images are available at: Figure 1 ; XPS spectrum reference Figure 2 .

[0054] Example 2 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1a

[0055] At room temperature, 20 mg of porphyrinyl triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of propargyl alcohol 1a were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.0 MPa. The reactor was placed in a 40°C constant temperature stirrer and stirred for 12 hours. After the reaction was completed, the unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the conversion rate was calculated to be 96.9%, the selectivity was 98.1%, and the α-alkylene cyclic carbonate 2a was 98.1%. 1 HNMR Reference Figure 3 .

[0056] Example 3 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1b

[0057] At room temperature, 20 mg of porphyrinyl triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of propargyl alcohol 1b were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.0 MPa. The reactor was placed in a 40°C constant temperature stirrer and stirred for 16 hours. After the reaction was completed, the unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the conversion rate was calculated to be 96.7%, the selectivity was 97.8%, and the α-alkylene cyclic carbonate 2b was 96.7%. 1 HNMR Reference Figure 4 .

[0058] Example 4 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1c

[0059] At room temperature, 20 mg of porphyrinyl triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of propargyl alcohol 1c were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.0 MPa. The reactor was placed in a 40 ° C constant temperature stirrer and stirred for 24 hours. After the reaction was completed, the unreacted CO2 was slowly released. Subsequently, 5 mL of ethyl acetate was added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the conversion rate was calculated to be 95.6%, the selectivity was 98.5%, and the α-alkylene cyclic carbonate 2c was 98.5%. 1 HNMR Reference Figure 5 .

[0060] Example 5 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1d

[0061] At room temperature, 20 mg of porphyrinyl triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of propargyl alcohol 1d were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.0 MPa. The reactor was placed in a 40°C constant temperature stirrer and stirred for 16 hours. After the reaction was completed, the unreacted CO2 was slowly released. Subsequently, 5 mL of ethyl acetate was added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the conversion rate was calculated to be 95.0%, the selectivity was 98.9%, and the α-alkylene cyclic carbonate 2d was 98.9%. 1 HNMR Reference Figure 6 .

[0062] Example 6 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1e

[0063] At room temperature, 20 mg of porphyrinyl triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of propargyl alcohol 1e were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.0 MPa. The reactor was placed in a 40°C constant temperature stirrer and stirred for 24 hours. After the reaction was completed, the unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the conversion rate was calculated to be 96.1%, the selectivity was 99.1%, and the α-alkylene cyclic carbonate 2e was 99.1%. 1 HNMR Reference Figure 7 .

[0064] Example 7 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1f

[0065] At room temperature, 20 mg of porphyrin-based triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of propargyl alcohol 1f were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.0 MPa. The reactor was placed in a 40°C constant temperature stirrer and stirred for 24 hours. After the reaction was completed, the unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the conversion rate was calculated to be 95.3%, the selectivity was 98.8%, and the α-alkylene cyclic carbonate 2f was 98.8%. 1 HNMR Reference Figure 8 .

[0066] Example 8 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1f

[0067] Under room temperature, 20 mg of porphyrin-based triazine framework-loaded nanosilver catalyst, 1 mmol of 1,8-diazacyclo[5,4,0]undecene-7 and 1 mmol of 1 g of propargyl alcohol were added to a 10 mL stainless steel reactor. After the reactor was sealed, CO2 gas was repeatedly and slowly filled and discharged 3 times. Then CO2 was added to stabilize the pressure at 1.5 MPa. The reactor was placed in a 40°C constant temperature stirrer and stirred for 24 hours. After the reaction was completed, the unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor and the solid catalyst was separated by centrifugation. An appropriate amount of supernatant was taken for gas chromatography analysis, and the calculated conversion rate was 95.3%, the selectivity was 98.8%, and 2 g of α-alkylene cyclic carbonate was 1.5%. 1 HNMR Reference Figure 9 .

[0068] Example 9 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1a

[0069] At room temperature, a 10 mL stainless steel reactor was charged with 20 mg of a porphyrinyl triazine framework-supported nanosilver catalyst, 0.5 mmol of 1,8-diazacyclo[5,4,0]undecene-7, and 1 mmol of propargyl alcohol 1a. The reactor was sealed and slowly filled and de-filled with CO2 three times. CO2 was then added to stabilize the pressure at 1.0 MPa. The reactor was stirred in a 40°C thermostatic stirrer for 12 h. Upon completion of the reaction, unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor, and the solid catalyst was separated by centrifugation. An appropriate amount of the supernatant was analyzed by gas chromatography, yielding a conversion of 67.6% and a selectivity of 98.6% for product 2a.

[0070] Example 10 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1a

[0071] At room temperature, a 10 mL stainless steel reactor was charged with 20 mg of a porphyrinyl triazine framework-supported nanosilver catalyst, 1.0 mmol of 1,8-diazacyclo[5,4,0]undecene-7, and 1 mmol of propargyl alcohol 1a. The reactor was sealed and slowly filled and deflated three times with a mixture of 15% CO₂ and 85% N₂ by volume. The mixture was then added to stabilize the pressure at 2.0 MPa. The reactor was stirred in a 30°C thermostatic stirrer for 12 h. Upon completion of the reaction, unreacted CO₂ was slowly released. 5 mL of ethyl acetate was then added to the reactor, and the solid catalyst was separated by centrifugation. An appropriate amount of the supernatant was analyzed by gas chromatography, yielding a conversion of 87.2% and a selectivity of 95.2% for product 2a.

[0072] Example 11 Catalyst catalyzes the carboxyl cyclization reaction of CO2 with propargyl alcohol 1a

[0073] At room temperature, a 10 mL stainless steel reactor was charged with 20 mg of a porphyrinyl triazine framework-supported nanosilver catalyst, 1.0 mmol of 1,8-diazacyclo[5,4,0]undecene-7, and 1 mmol of propargyl alcohol 1a. The reactor was sealed and slowly filled and de-filled with CO2 three times. CO2 was then added to stabilize the pressure at 0.5 MPa. The reactor was stirred in a 30°C thermostatic stirrer for 12 h. Upon completion of the reaction, unreacted CO2 was slowly released. 5 mL of ethyl acetate was then added to the reactor, and the solid catalyst was separated by centrifugation. An appropriate amount of the supernatant was analyzed by gas chromatography, yielding a conversion of 78.6% and a selectivity of 98.5% for product 2a.

Claims

1. A porphyrinyl triazine framework-supported nanosilver catalyst, characterized in that: Its structural formula is shown in formula (I): ； Formula (I).

2. The method for preparing the porphyrinyl triazine framework-supported nanosilver catalyst according to claim 1, wherein: The method includes the following steps in sequence: 1) Add 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and cyanuric chloride in a molar ratio of 1:1-2 to a round-bottom flask containing solvent. Continue adding solvent and acid-binding agent. Stir at room temperature for 0.5 h, then heat to reflux and react for 72 h. Filter and wash the resulting precipitate, then vacuum dry at 100°C for 12 h to obtain a porphyrin-based triazine framework containing a secondary amino group. 2) Adding silver tetrafluoroborate in tetrahydrofuran to a round-bottom flask and stirring evenly at room temperature to obtain a tetrahydrofuran solution containing silver tetrafluoroborate, then adding the porphyrinyl triazine framework containing a secondary amino group obtained in step 1) to the round-bottom flask, stirring in the dark at room temperature for 1 hour, then heating to 80°C, reacting for 24 hours, filtering, washing with solvent multiple times, and vacuum drying at 100°C for 12 hours to obtain a porphyrinyl triazine framework-supported nanosilver catalyst; Step 2) The mass ratio of the porphyrinyl triazine framework to silver tetrafluoroborate is 100:2-10.

3. The method for preparing a porphyrinyl triazine framework-supported nanosilver catalyst according to claim 2, wherein: Step 1) The solvent is any one of tetrahydrofuran, 1,2-dioxane, N,N-dimethylformamide, and dimethyl sulfoxide.

4. The method for preparing a porphyrinyl triazine framework-supported nanosilver catalyst according to claim 2, wherein: Step 1) The acid binding agent is any one of potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, triethylamine, and N,N-diisopropylethylamine.

5. The method for preparing a porphyrinyl triazine framework-supported nanosilver catalyst according to claim 2, wherein: In step 1), the amount of the acid binding agent is 2.5 to 7.5 times the amount of cyanuric chloride.

6. The method for preparing the porphyrinyl triazine framework-supported nanosilver catalyst according to claim 2, wherein: Step 1) The washing method is a combination of filtration washing and Soxhlet extraction. The solvents for filtration washing are 50 to 150 mL of methanol, N,N-dimethylformamide, tetrahydrofuran and dichloromethane, respectively. The Soxhlet extraction uses 300 mL of tetrahydrofuran as the solvent, and the extraction time is 24 hours.

7. The method for preparing a porphyrinyl triazine framework-supported nanosilver catalyst according to claim 2, wherein: Step 2) The concentration of the silver tetrafluoroborate tetrahydrofuran solution is 1-5 mg / mL.

8. The porphyrinyl triazine framework-supported nanosilver catalyst according to claim 1 is used to catalyze the cycloaddition reaction of a propargyl alcohol compound with CO2 to produce an α-alkylene cyclic carbonate.

9. A method for preparing α-alkylene cyclic carbonate by catalyzing a cycloaddition reaction between a propargyl alcohol compound and CO2 using a porphyrinyl triazine framework-supported nanosilver catalyst, characterized in that: The method comprises the following steps in sequence: without adding any solvent, reacting CO2 with a volume concentration of 15 to 100% and 1 mmol of a propargyl alcohol derivative 1a-1g of the structural formula as described in formula (II) in the presence of 20 mg of a porphyrinyl triazine framework-supported nanosilver catalyst and 0.5 to 2.5 mmol of 1,8-diazacyclo[5,4,0]undecene-7 as a co-catalyst at a pressure of 0.1 to 5.0 MPa and a reaction temperature of 25 to 80° C., with constant stirring for 5 to 48 hours to obtain an α-alkylene cyclic carbonate 2a-2g of the structural formula as described in formula (III); Wherein: the propargyl alcohol derivative has the structural formula shown in formula (II): Formula (II) The α-alkylene cyclic carbonate has a structural formula as shown in formula (III): Formula (III).

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