Zinc-based MOF material catalyst and preparation method thereof

Abstract

The invention provides a zinc-based MOF material catalyst and a preparation method thereof, and the zinc-based MOF material catalyst is mainly prepared from the following raw materials: an organic monomer a, a zinc salt, an organic monomer b, a solvent and a metal salt, the organic monomer a is selected from at least one of imidazole nitrogen heterocyclic ligands with carboxylic acid functional groups; the organic monomer b is selected from at least one of difunctional ligands containing amino groups and carboxylic acid groups. The zinc-based MOF material has better carbon dioxide adsorption performance through the synergistic effect of the metal salt and the ligand, can efficiently catalyze the cycloaddition reaction of carbon dioxide and propargyl alcohol as a catalyst under mild conditions, and solves the problems of yield and purity of reaction products.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthetic chemical materials, and in particular to a zinc-based MOF material catalyst and a preparation method thereof. Background Art

[0002] With the rapid development of industrialization, the greenhouse effect and climate change caused by excessive carbon dioxide emissions have become global environmental challenges. Developing technologies for carbon dioxide resource utilization is one of the effective ways to mitigate the continued increase in its concentration. Carbon dioxide, as a non-toxic, renewable C1 carbon source, can be synthesized into high-value-added chemicals and fuels through chemical conversion. Among them, α-alkylene cyclic carbonates synthesized from propargyl alcohol and carbon dioxide have attracted widespread attention in recent years due to their potential application value in natural product synthesis, polymer material preparation, and the polyurethane industry. Traditional synthesis routes for such compounds often rely on homogeneous catalytic systems, but such catalysts generally suffer from problems such as difficult product separation and low catalyst recovery, which limits their industrial application.

[0003] Heterogeneous catalysts are considered as alternatives due to their easy separation and reusability. Among them, metal-organic framework materials have shown significant potential in the field of catalysis due to their advantages such as adjustable pore structure and diverse functional modification. In the cycloaddition reaction of carbon dioxide and propargyl alcohol, the catalyst must have the dual functions of activating alkynes and capturing / activating carbon dioxide. However, existing heterogeneous catalytic systems still face technical bottlenecks such as harsh reaction conditions (such as high temperature and pressure) and insufficient catalytic efficiency. There is an urgent need to develop new catalytic materials with both high activity and stability to promote the industrialization of this reaction.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The first purpose of the present invention is to provide a zinc-based MOF material catalyst, which is constructed by specific ligand design and metal node assembly and has better carbon dioxide adsorption.

[0006] The second purpose of the present invention is to provide a method for preparing the above-mentioned zinc-based MOF material catalyst. This method realizes ligand assembly and functional modification under controllable conditions through solvent thermal synthesis combined with a post-modification strategy. The steps are simple and suitable for large-scale production.

[0007] The third purpose of the present invention is to provide an application of a zinc-based MOF material catalyst, wherein the zinc-based MOF material is used as a heterogeneous catalyst to catalyze the cycloaddition reaction of carbon dioxide and propargyl alcohol, and has the characteristics of high efficiency conversion, easy recovery, mild reaction conditions, etc.; it simultaneously solves the dual needs of environmental governance and high-value chemical production.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: A zinc-based MOF material catalyst is mainly prepared from the following raw materials: organic monomer a, zinc salt, organic monomer b, solvent and metal salt; The organic monomer a is selected from at least one imidazole nitrogen heterocyclic ligand having a carboxylic acid functional group; the organic monomer b is selected from at least one bifunctional ligand containing an amino group and a carboxylic acid group.

[0009] Furthermore, the organic monomer a is any one of ‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride and ‌1,3-bis(4-carboxylic acid phenyl)imidazolium bromide; Preferably, the organic monomer a is ‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride.

[0010] Further, the organic monomer b is at least one of 2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 2',3'-diamino[1,1':4',1"-terphenyl]-4,4"-dicarboxylic acid, and 2-amino[1,1'-biphenyl]-4,4'-dicarboxylic acid; Preferably, the organic monomer b is a combination of 2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid and 2-amino[1,1'-biphenyl]-4,4'-dicarboxylic acid, with a molar ratio of 1:1.

[0011] Furthermore, the metal salt is any one of CuCl, PbCl2, and Ag2O; Preferably, the metal salt is CuCl.

[0012] In this material, the carboxylic acid groups of organic monomers a and b coordinate with the zinc ion to form a stable three-dimensional framework, providing abundant active sites and enhancing substrate adsorption. Furthermore, organic monomer a provides Lewis acidic sites, while the amino group of organic monomer b acts as a Lewis base site, jointly promoting the catalytic reaction. During the synthesis process, the metal salt acts as a precursor to the metal carbene, undergoing deprotonation with organic monomer a and coordinating to form a metal carbene. The metal carbene sites form a bimetallic synergistic catalytic system with the zinc nodes, significantly improving reaction rate and selectivity. Furthermore, the use of zinc salts can effectively reduce catalyst costs by replacing precious metal catalysts.

[0013] Specifically, the solvent is either DMF (N,N-dimethylformamide) or methanol. DMF effectively dissolves organic monomers a and b, along with the zinc salt, promoting uniform coordination and improving MOF crystallinity and structural integrity. Methanol is used for metal salt loading and post-processing. The precise division of labor between DMF and methanol optimizes the synthesis efficiency, structural properties, and catalytic activity of the zinc-based MOF catalyst, making it suitable for green catalysis.

[0014] Furthermore, the molar ratio of the zinc salt to the organic monomer a is (2:1) to (8:1); Preferably, the molar ratio of the zinc salt to the organic monomer a is 4:1.

[0015] Furthermore, the molar ratio of the organic monomer b to the substance comprising the zinc salt and the organic monomer a is (2:1) to (10:1); Preferably, the molar ratio of the organic monomer b to the substance comprising the zinc salt and the organic monomer a is 2.5:1.

[0016] Furthermore, the molar ratio of the metal salt to the substance comprising the organic monomer b, the zinc salt, and the organic monomer a is (1:1) to (10:1); Preferably, the molar ratio of the metal salt to the substance comprising the organic monomer b, the zinc salt, and the organic monomer a is 5:1.

[0017] Specifically, the present invention achieves synergy between material structure and catalytic performance through the ratio of the various components of the zinc-based MOF catalyst. The optimal ratio of zinc salt to organic monomer a avoids both framework collapse caused by too low a zinc content and pore blockage caused by an excessively high ratio, achieving a balance between framework stability and active site density. A 4:1 ratio achieves optimal coordination between zinc nodes and organic monomer a. Controlling the molar ratio of organic monomer b to the initial reactants (zinc salt + organic monomer a) within the aforementioned range modulates the pore microenvironment, achieving optimal coverage of amino group modifications and enhancing carbon dioxide adsorption capacity. A 2.5:1 ratio achieves an optimal balance between the amount of amino groups introduced, ensuring sufficient carbon dioxide adsorption sites while preventing pore blockage caused by excessive amino groups. The introduction ratio of metal salts can achieve a better distribution of catalytic active sites, ensure the uniform dispersion of carbene sites, and avoid the occurrence of deactivation problems caused by aggregation of active sites; when a ratio of 5:1 is selected, the loading amount of metal carbene is optimized, and by constructing a bimetallic active center, the reaction energy barrier is significantly reduced, achieving an atomic utilization rate close to 100%.

[0018] The present invention also provides a method for preparing a zinc-based MOF material catalyst, comprising the following steps: adding the organic monomer a into the solvent and mixing them to form a first mixed solution; Adding the zinc salt to the first mixed solution and heating the mixture to react to obtain the NHC-MOF material; adding the organic monomer b into another solvent and mixing them to form a second mixed solution; Adding the second mixed solution to the NHC-MOF material for stirring, soaking and washing; After the stirring, soaking and washing, a solid product is obtained, and the solid product is vacuum-dried to obtain an NH2-MOF material; Selecting a metal salt and dissolving it in the solvent to form a third mixed solution; adding the NH2-MOF material to the third mixed solution to react and obtain a mixture; The mixture is reacted under the protection of nitrogen, and after the reaction, centrifugal separation, washing, and vacuum drying are performed to obtain the product.

[0019] Furthermore, in the step of adding the zinc salt to the first mixed solution for heating reaction to obtain the NHC-MOF material, the heating reaction adopts a hot solvent method; the heating reaction is carried out at a temperature of 100-150° C. and the time is controlled to be 40-60 hours; The second mixed solution is added to the NHC-MOF material for stirring, soaking and washing, wherein the stirring temperature is controlled at 20-50° C., the stirring time is controlled at 5-20 hours, the soaking time is controlled at 5-10 hours, and the washing times are 2-3 times; In the step of adding the NH2-MOF material to the third mixed solution for reaction, the reaction temperature is controlled to be 40-80° C., and the reaction time is controlled to be 0.5-2 h.

[0020] In the present invention, by limiting and regulating various operating parameters in the preparation method, the quality of the prepared catalyst is improved, so that it is not affected by external factors and decomposed and deteriorated, ensuring that the catalyst still maintains excellent catalytic effect during use.

[0021] The present invention also provides an application of a zinc-based MOF material catalyst, and an application of the zinc-based MOF material catalyst prepared by the method in a carboxylation reaction.

[0022] Specifically, the zinc-based MOF catalyst provided by this invention exhibits excellent catalytic performance in carboxylation reactions. Through the synergistic effect of amino modification and metal carbene, the catalyst can efficiently catalyze the carboxylation cyclization reaction of carbon dioxide with propargyl alcohol under mild conditions, significantly improving the yield of α-alkylene cyclic carbonates.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The zinc-based MOF catalyst provided by the present invention, through amino modification and the introduction of a metal carbene, constructs a bifunctional active center with both Lewis basicity and Lewis acidity, thereby achieving an efficient carboxylation and cyclization reaction of carbon dioxide with propargyl alcohol under mild conditions. The introduction of the amino group significantly improves the material's adsorption capacity for carbon dioxide, while the metal carbene, through its strong electron-donating effect, increases the electronegativity of the hydroxyl oxygen atom, making proton removal easier. This catalytic mechanism milders the reaction conditions and improves product yield.

[0024] Another major advantage of the catalyst lies in its structural tunability and high specific surface area. The MOF framework itself has a rich porous structure and adjustable pore size, and amino modification further optimizes the exposure of its internal adsorption sites, further enhancing its carbon dioxide capture capacity. Compared to traditional precious metal catalysts, the present invention uses zinc-based materials instead of precious metal catalysts, reducing costs. Furthermore, it exhibits excellent catalytic activity and selectivity in cyclization reactions, enabling the efficient synthesis of α-alkylene cyclic carbonates.

[0025] Compared to traditional homogeneous catalysts, the heterogeneous nature of the zinc-based MOF material catalyst of the present invention not only solves the problem of difficult product separation and enables recycling through simple steps; it also reduces the reaction temperature, allowing for multiple recycling and achieving higher catalytic activity, making the entire catalytic process more energy-efficient. From the perspective of environmental protection and economic benefits, the mild conditions of the catalytic reaction significantly reduce energy consumption and equipment requirements. At the same time, by utilizing carbon dioxide as a resource, greenhouse gas emissions can be reduced, providing an efficient and sustainable solution for the high-value-added conversion of carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a graph of the CO2 (carbon dioxide) adsorption capacity of the material provided by the present invention; the square broken line in the figure represents the NHC-MOF material, and the circular broken line represents the NH2-MOF material; Figure 2 The XRD patterns of the zinc-based MOF material catalyst and other MOF materials in the embodiment of the present invention; the curves in the figure are respectively the zinc-based MOF material catalyst provided by the present invention, NH2-MOF material, and ordinary zinc-based MOF material from top to bottom; Figure 3 A graph showing the results of the carboxylation cyclization of CO2 and propargyl alcohol catalyzed by the zinc-based MOF material catalyst provided in Example 2 of the present invention and a conventional zinc-based MOF material as a catalyst; the broken lines in the figure, from top to bottom, are the zinc-based MOF material of the present invention (light color) and the conventional zinc-based MOF material (dark color); Figure 4 This is a diagram showing the effect of the catalytic cycle of the zinc-based MOF material catalyst provided in Example 2 of the present invention; the black bars represent the conversion rate (Conversion), and the white bars represent the selectivity (Selectivity); Figure 5 is an SEM image of the zinc-based MOF material catalyst and other MOF materials in Example 2 of the present invention; Figure 5-(a) is an ordinary zinc-based MOF material, Figure 5-(b) is an NH2-MOF material, Figure 5-(c) is the NH2-MOF material provided by the present invention, and Figure 5-(d) is the zinc-based MOF material catalyst provided by the present invention after the catalytic reaction is completed and recovered. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0029] Example 1 The specific preparation process of this embodiment is carried out according to the following steps: 173.0 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride, 0.50 mmol) was weighed and dissolved in 10 ml of DMF solvent to obtain a first mixed solution.

[0030] 595.0 mg of zinc nitrate hexahydrate (2.00 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 120°C for 48 hours, with a heating rate of 30°C / h. After the heating reaction was completed, the temperature was cooled at 5°C / h to 25°C to obtain the NHC-MOF material.

[0031] 29.6 mg of organic monomer b {(2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 16.7 mg, 0.05 mmol) and (2-amino[1,1'-biphenyl]-4,4'-dicarboxylic acid, 12.9 mg, 0.05 mmol)} was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0032] 200.0 mg of NHC-MOF material (0.04 mmol) was weighed and added to the second mixed solution, and stirred at 25°C for 12 h to obtain a substance; after soaking and washing with fresh DMF solvent three times, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0033] 5.0 mg of CuCl (0.05 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0034] Nitrogen was introduced into the mixture, and after stirring at 60°C under a nitrogen atmosphere for 30 minutes, the mixture was cooled to 25°C; then centrifuged, washed with fresh methanol solvent, and dried in vacuo at 80°C to obtain the product.

[0035] Example 2 The specific preparation process of this embodiment is carried out according to the following steps: 173.0 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride, 0.50 mmol) was weighed and dissolved in 10 ml of DMF solvent to obtain a first mixed solution.

[0036] 595.0 mg of zinc nitrate hexahydrate (2.00 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 120° C. and heated for 48 hours at a heating rate of 30° C. / h. After the heating reaction was completed, the temperature was cooled by 5° C. / h to 25° C. to obtain the NHC-MOF material.

[0037] 33.0 mg of organic monomer b (2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 0.10 mmol) was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0038] 200.0 mg of NHC-MOF material (0.04 mmol) was weighed and added to the second mixed solution, and stirred at 25°C for 12 h to obtain a substance; after soaking and washing with fresh DMF solvent three times, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0039] 5.0 mg of CuCl (0.05 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0040] Nitrogen was introduced into the mixture, and after stirring at 60°C under a nitrogen atmosphere for 30 minutes, the mixture was cooled to 25°C; then centrifuged, washed with fresh methanol solvent, and dried in vacuo at 80°C to obtain the product.

[0041] Example 3 The specific preparation process of this embodiment is carried out according to the following steps: 173 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride, 0.5 mmol) was weighed and dissolved in 10 ml of DMF solvent to obtain a first mixed solution.

[0042] 595 mg of zinc nitrate hexahydrate (2.0 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 120°C for 48 hours, with a heating rate of 30°C / h. After the heating reaction was completed, the temperature was cooled by 5°C / h to 25°C to obtain the NHC-MOF material.

[0043] 35 mg of organic monomer b (2',3'-diamino[1,1':4',1"-terphenyl]-4,4"-dicarboxylic acid, 0.1 mmol) was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0044] 200 mg of NHC-MOF material (0.04 mmol) was weighed and added to the second mixed solution, and stirred at 25°C for 12 h to obtain a substance; after soaking and washing with fresh DMF solvent three times, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0045] 5 mg of CuCl (0.05 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0046] Nitrogen was introduced into the mixture, and after stirring at 60°C under a nitrogen atmosphere for 30 minutes, the mixture was cooled to 25°C; then centrifuged, washed with fresh methanol solvent, and dried in vacuo at 80°C to obtain the product.

[0047] Example 4 The specific preparation process of this embodiment is carried out according to the following steps: 173.0 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride, 0.50 mmol) was weighed and dissolved in 10 ml of DMF solvent to obtain a first mixed solution.

[0048] 595.0 mg of zinc nitrate hexahydrate (2.00 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 120° C. and heated for 48 hours at a heating rate of 30° C. / h. After the heating reaction was completed, the temperature was cooled by 5° C. / h to 25° C. to obtain the NHC-MOF material.

[0049] 33.0 mg of organic monomer b (2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 0.10 mmol) was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0050] 200 mg of NHC-MOF material (0.04 mmol) was weighed and added to the second mixed solution, and stirred at 25°C for 12 h to obtain a substance; after soaking and washing with fresh DMF solvent three times, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0051] 13.9 mg of PbCl2 (0.05 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0052] Nitrogen was introduced into the mixture, and after stirring at 60°C under a nitrogen atmosphere for 30 minutes, the mixture was cooled to 25°C; then centrifuged, washed with fresh methanol solvent, and dried in vacuo at 80°C to obtain the product.

[0053] Example 5 The specific preparation process of this embodiment is carried out according to the following steps: 195.0 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium bromide, 0.50 mmol) was weighed and added into 10 ml of DMF solvent for dissolution to obtain a first mixed solution.

[0054] 595.0 mg of zinc nitrate hexahydrate (2.00 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 120° C. and heated for 48 hours at a heating rate of 30° C. / h. After the heating reaction was completed, the temperature was cooled by 5° C. / h to 25° C. to obtain the NHC-MOF material.

[0055] 33.0 mg of organic monomer b (2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 0.10 mmol) was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0056] 200 mg of NHC-MOF material (0.04 mmol) was weighed and added to the second mixed solution, and stirred at 25°C for 12 h to obtain a substance; after soaking and washing with fresh DMF solvent three times, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0057] 5.0 mg of CuCl (0.05 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0058] Nitrogen was introduced into the mixture, and after stirring at 60°C under a nitrogen atmosphere for 30 minutes, the mixture was cooled to 25°C; then centrifuged, washed with fresh methanol solvent, and dried in vacuo at 80°C to obtain the product.

[0059] Example 6 86.5 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride, 0.25 mmol) was weighed and added into 10 ml of DMF solvent for dissolution to obtain a first mixed solution.

[0060] 595 mg of zinc nitrate hexahydrate (2.0 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 150°C for 48 hours, with a heating rate of 30°C / h. After the heating reaction was completed, the temperature was cooled by 5°C / h to 25°C to obtain the NHC-MOF material.

[0061] 33.0 mg of organic monomer b (2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 0.10 mmol) was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0062] 50.0 mg of NHC-MOF material (0.01 mmol) was weighed and added to the second mixed solution, and stirred at 20°C for 9 h to obtain a substance; after soaking and washing with fresh DMF solvent twice, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0063] 10.0 mg of CuCl (0.10 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0064] Example 7 The specific preparation process of this embodiment is carried out according to the following steps: 195.0 mg of organic monomer a (‌1,3-bis(4-carboxylic acid phenyl)imidazolium bromide, 0.50 mmol) was weighed and added into 10 ml of DMF solvent for dissolution to obtain a first mixed solution.

[0065] 297.0 mg of zinc nitrate hexahydrate (1.00 mmol) was weighed and added to the first mixed solution for a heating reaction. The heating reaction temperature was controlled at 120°C for 55 hours, with a heating rate of 30°C / h. After the heating reaction was completed, the temperature was cooled by 5°C / h to 25°C to obtain the NHC-MOF material.

[0066] 20.6 mg of organic monomer b (2-amino[1,1'-biphenyl]-4,4'-dicarboxylic acid, 0.08 mmol) was weighed and added to another 10 ml of DMF solvent for dissolution to obtain a second mixed solution.

[0067] 200 mg of NHC-MOF material (0.04 mmol) was weighed and added to the second mixed solution, and stirred at 29°C for 16 h to obtain the substance; after soaking and washing with fresh DMF solvent three times, it was vacuum-dried at 120°C for 12 h to obtain NH2-MOF material.

[0068] 11.6 mg of Ag2O (0.05 mmol) was weighed and dissolved in 10 mL of dry methanol to obtain a third mixed solution, and 48.8 mg of NH2-MOF material (0.01 mmol) was weighed and added to the third mixed solution to react to obtain a mixture.

[0069] Nitrogen was introduced into the mixture, and after stirring at 60°C under a nitrogen atmosphere for 30 minutes, the mixture was cooled to 25°C; then centrifuged, washed with fresh methanol solvent, and dried in vacuo at 80°C to obtain the product.

[0070] Example 8 The specific implementation method is consistent with Example 1, except that the molar ratio of the selected combination of organic monomers b is changed to 1:5.

[0071] Example 9 The specific implementation method is consistent with Example 1, except that the molar ratio of the metal salt to the NH2-MOF material is changed to 0.8:1.

[0072] Example 10 The specific implementation method is consistent with Example 1, except that the molar ratio of the metal salt to the NH2-MOF material is changed to 1:4.

[0073] Example 11 The specific implementation method is consistent with Example 2, except that the molar ratio of the organic monomer b to the NHC-MOF material is changed to 14:1.

[0074] Example 12 The specific implementation method is consistent with Example 2, except that the molar ratio of the organic monomer b to the NHC-MOF material is changed to 1:1.

[0075] Example 13 The specific implementation method is consistent with Example 2, except that the molar ratio of zinc salt to organic monomer a is changed to 12:1.

[0076] Example 14 The specific implementation method is consistent with Example 2, except that the molar ratio of zinc salt to organic monomer a is changed to 1:1.

[0077] Experimental Example 1 The catalytic performance of the zinc-based MOF material catalyst prepared in the examples of the present invention and the material prepared in the comparative examples was measured in relevant reactions. The experimental results are shown in Table 1.

[0078] The specific experimental steps are: Weigh 20 mg of the finished product provided in the experimental example using a scale and transfer it to a dry reaction bottle (glass container flask). Then, add 84 mg of 2-methyl-3-butyn-2-ol, 76 mg of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), and 2 mL of acetonitrile to the reaction bottle in sequence. Then, introduce carbon dioxide into the reaction bottle from the neck of the reaction bottle, maintain ventilation for 5 minutes, and then close the outlet valve. Repeat the replacement process three times to completely remove the air in the reaction bottle; reconnect the pre-filled carbon dioxide balloon to the air inlet system, keep the carbon dioxide flowing, and transfer the reaction system to a constant temperature oil bath and raise the temperature to 40°C; after the reaction is completed, analyze it.

[0079] Table 1: Experimental results

[0080] From the above, it can be seen that in the process of the zinc-based MOF material catalyst prepared by the present invention, the molar ratio between the raw materials and between the process products and the raw materials is very important. The strong power supply effect of the metal carbene and the synergistic ability of the amino group to capture carbon dioxide can significantly improve the reaction rate and conversion rate of carbon dioxide and propargyl alcohol carboxylation cyclization. Excessive or insufficient metal salts and amino groups will destroy this synergistic effect, affecting the use effect of the zinc-based MOF material catalyst prepared by the present invention. At the same time, the conversion rates of Examples 1-7 are all higher than 95%, which illustrates that the synergistic effect of the amino group and the metal carbene is that the zinc-based MOF material catalyst prepared by the present invention has an efficient effect, significantly enhancing carbon dioxide adsorption and activation capabilities.

[0081] It can be seen from Experimental Examples 1-8 that different amino ligands were used in the selection of organic monomer b, and the results showed that the conversion rate was higher than 96%. Among them, the combination of Example 1 had a catalytic effect of 99.0%. It is shown that the combined use of the amino ligands of the present invention can improve the conversion rate of carbon dioxide; the larger triphenyl ligand can promote the diffusion of reactants, while the biphenyl ligand can significantly increase the density of carbon dioxide adsorption sites. The 1:1 combination optimizes the catalytic performance through complementarity and active site synergy. At the same time, it can also form a stable structure with the organic monomer a, making the pore distribution more uniform, further enhancing the adsorption of carbon dioxide, and improving the adsorption performance of the zinc-based MOF material catalyst of the present invention for carbon dioxide.

[0082] The selection of metal carbene has a significant regulatory effect on catalytic performance. Example 4 replaces CuCl with PbCl2, then drops to a conversion rate of 97.2%, while Example 7 adopts Ag2O when the conversion rate drops to 96.7%. It can be seen that the optimal choice in the present invention is CuCl. By Examples 9 and 10, it can be seen that too much or too little metal salt will cause imbalance, and too much or too little metal salt will cause the synergistic effect of electronic effect and pore structure to be destroyed, affecting the catalytic performance to carbon dioxide. For zinc salts and organic monomers. By Example 2, compared with Example 13 and 14, it can be seen that excessive or too little zinc salt will gather or the synthesized NHC-MOF material framework will collapse. For the introduction ratio of organic monomer b, Example 2, Example 11, 12 can be learned that when the organic monomer b ratio exceeds the ratio range, the adsorption capacity of carbon dioxide and the balance of the catalyst will have a destructive effect. Although a high ratio will increase the amount of carbon dioxide adsorbed, the excess amino groups will occupy space, resulting in a reduction in the number of carbene sites, which greatly reduces the catalytic effect; while a low ratio will weaken the ability to adsorb carbon dioxide due to insufficient amino groups. Although the density of carbene sites is sufficient, the overall catalytic performance is still limited.

[0083] Specifically, by adjusting the ratio of ligand to metal salt, Examples 8-14 revealed that when the ratio of zinc salt to organic monomer a was unbalanced, the molar ratio of organic monomer b to NHC-MOF material deviated from the optimal range, or the ratio of metal salt to NH2-MOF material exceeded the matching range, catalytic performance decreased dramatically. This suggests that excessive metal ions can disrupt coordination equilibrium, while insufficient ligands can compromise framework integrity and lead to its collapse.

[0084] Experimental Example 2 The carbon dioxide adsorption performance of the materials prepared in Example 2 of the present invention was tested. The specific results are shown in Table 1. Figure 1 The figure shows a line graph of the carbon dioxide adsorption capacity of NHC-MOF and NH2-MOF materials over time. As can be seen, during the initial adsorption phase, the carbon dioxide adsorption capacity of both materials increases rapidly, indicating that both materials can rapidly adsorb carbon dioxide for a period of time. However, over time, the adsorption rate of the NHC-MOF material gradually slows. Furthermore, at the same time point, the carbon dioxide adsorption capacity of the NH2-MOF material is generally higher than that of the NHC-MOF material, indicating that the NH2-MOF material has stronger carbon dioxide adsorption performance.

[0085] Experimental Example 3 The crystal structure characteristics of the zinc-based MOF material catalyst prepared in Example 2 of the present invention were compared with those of ordinary zinc-based MOF materials. The specific results are shown in Table 1. Figure 2As shown in the figure, the curves in the figure, from top to bottom, represent the zinc-based MOF material of the present invention, the NH2-MOF material, and a conventional zinc-based MOF material. As can be seen from the figure, the XRD patterns of the three materials exhibit different diffraction peak positions and intensities, indicating significant differences in their crystal structures, indicating that the modification significantly altered the crystal structure characteristics of the materials.

[0086] Experimental Example 4 The catalytic performance of the zinc-based MOF material catalyst prepared in Example 2 of the present invention and the ordinary zinc-based MOF material catalyst in the reaction were tested, and the catalytic stability of the recovered zinc-based MOF material catalyst was measured multiple times. The relevant SEM images (Figure 5) are also given. For specific results, refer to Figure 3-4 shown.

[0087] in Figure 3 The chart shows how the conversion rate changes with reaction time during the catalytic carboxylation and cyclization reaction of carbon dioxide and propargyl alcohol. It shows that the conversion rate of the zinc-based MOF material catalyst of the present invention rises rapidly in the initial reaction phase, reaching nearly 100% in around 5 hours and remaining stable. In contrast, the conversion rate of conventional zinc-based MOF materials remains relatively low throughout the 10-hour reaction time, with almost no significant increase. The reaction activity of the zinc-based MOF material catalyst of the present invention is significantly higher than that of conventional zinc-based MOF materials. The slope of the curve indicates that the zinc-based MOF material catalyst of the present invention significantly increases conversion rate within a short period of time, demonstrating its rapid reaction rate and ability to convert a large amount of reactants into products in a relatively short period of time. In contrast, conventional zinc-based MOF materials have an extremely slow reaction rate, making it virtually impossible to drive the reaction forward. This indicates that the modified zinc-based MOF material catalyst of the present invention exhibits significantly improved reaction performance, making it more conducive to promoting the relevant reaction.

[0088] in Figure 4 The bar graph shows the conversion rate and selection of the zinc-based MOF material catalyst of the present invention at different times during the carboxylation cyclization reaction process; Figure 3 The zinc-based MOF material catalyst of the present invention is recovered by centrifugation in the mixture solution after the reaction. After recovery, it is soaked and washed with acetonitrile three times and then vacuum dried. The dried zinc-based MOF material catalyst is subjected to multiple activation reaction catalytic cycles.

[0089] As can be seen from the figure, during the 1-4 catalytic cycles, the conversion rate of the zinc-based MOF material catalyst always remained at a high level close to 100%, with almost no fluctuation. This clearly shows that as the number of catalytic cycles increases, the zinc-based MOF material's ability to promote the conversion of reactants into products is stable and efficient, and it can continuously ensure the smooth conversion of a large number of reactants, reflecting its good stability in the conversion of reactants in the catalytic reaction. Its selectivity has remained stable at around 70% throughout the multiple catalytic cycles. This shows that the zinc-based MOF material catalyst has a stable preference for generating the target product during multiple catalytic cycles, and the proportion of the target product generated does not significantly change due to changes in the number of cycles, demonstrating reliable stability in the selectivity of the target product generation. The overall performance fully demonstrates that the zinc-based MOF material catalyst has excellent catalytic cycle stability over multiple catalytic cycles. Neither the ability to promote the reaction nor the selectivity for the generation of the target product changes significantly with the increase in the number of cycles, which strongly demonstrates the stable and reliable performance of the product provided by the present invention in the catalytic reaction, and that it can continue to exert a stable catalytic effect over multiple cyclic reactions.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zinc-based MOF material catalyst, characterized in that: It is mainly prepared from the following raw materials: organic monomer a, zinc salt, organic monomer b, solvent and metal salt; The organic monomer a is selected from at least one imidazole nitrogen heterocyclic ligand having a carboxylic acid functional group; the organic monomer b is selected from at least one bifunctional ligand containing an amino group and a carboxylic acid group.

2. The zinc-based MOF material catalyst according to claim 1, characterized in that The organic monomer a is any one of ‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride and ‌1,3-bis(4-carboxylic acid phenyl)imidazolium bromide; Preferably, the organic monomer a is ‌1,3-bis(4-carboxylic acid phenyl)imidazolium chloride.

3. The zinc-based MOF material catalyst according to claim 1, characterized in that The organic monomer b is at least one of 2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid, 2',3'-diamino[1,1':4',1"-terphenyl]-4,4"-dicarboxylic acid, and 2-amino[1,1'-biphenyl]-4,4'-dicarboxylic acid; Preferably, the organic monomer b is a combination of 2'-amino-[1,1',4',1"-triphenyl]-4,4"-dicarboxylic acid and 2-amino[1,1'-biphenyl]-4,4'-dicarboxylic acid, with a molar ratio of 1:

1.

4. The zinc-based MOF material catalyst according to claim 1, characterized in that The metal salt is any one of CuCl, PbCl2, and Ag2O; Preferably, the metal salt is CuCl.

5. The zinc-based MOF material catalyst according to claim 1, characterized in that The molar ratio of the zinc salt to the organic monomer a is (2:1) to (8:1); Preferably, the molar ratio of the zinc salt to the organic monomer is 4:

1.

6. The zinc-based MOF material catalyst according to claim 1, characterized in that The molar ratio of the organic monomer b to the substance comprising the zinc salt and the organic monomer a is (2:1) to (10:1); Preferably, the molar ratio of the organic monomer b to the substance comprising the zinc salt and the organic monomer a is 2.5:

1.

7. The zinc-based MOF material catalyst according to claim 1, characterized in that The molar ratio of the metal salt to the substance comprising the organic monomer b, the zinc salt, and the organic monomer a is (1:1) to (10:1); Preferably, the molar ratio of the metal salt to the substance comprising the organic monomer b, the zinc salt, and the organic monomer a is 5:

1.

8. A method for preparing a zinc-based MOF material catalyst according to any one of claims 1 to 7, characterized in that: The steps include: adding the organic monomer a into the solvent and mixing them to form a first mixed solution; Adding the zinc salt to the first mixed solution and heating the mixture to react to obtain the NHC-MOF material; adding the organic monomer b into another solvent and mixing them to form a second mixed solution; Adding the second mixed solution to the NHC-MOF material for stirring, soaking and washing; After the stirring, soaking and washing, a solid product is obtained, and the solid product is vacuum-dried to obtain an NH2-MOF material; Selecting a metal salt and dissolving it in the solvent to form a third mixed solution; adding the NH2-MOF material to the third mixed solution to react and obtain a mixture; The mixture is reacted under the protection of nitrogen, and after the reaction, centrifugal separation, washing, and vacuum drying are performed to obtain the product.

9. The method for preparing the zinc-based MOF material catalyst according to claim 8, characterized in that: In the step of adding the zinc salt to the first mixed solution for heating reaction to obtain the NHC-MOF material, the heating reaction adopts a hot solvent method; the heating reaction is carried out at a temperature of 100-150° C. and the time is controlled to be 40-60 hours; The second mixed solution is added to the NHC-MOF material for stirring, soaking and washing, wherein the stirring temperature is controlled at 20-50° C., the stirring time is controlled at 5-20 hours, the soaking time is controlled at 5-10 hours, and the washing times are 2-3 times; In the step of adding the NH2-MOF material to the third mixed solution for reaction, the reaction temperature is controlled to be 40-80° C., and the reaction time is controlled to be 0.5-2 h.

10. An application of a zinc-based MOF material catalyst, characterized in that: Use of the zinc-based MOF material catalyst prepared by the method according to any one of claims 8 to 9 in a carboxylation reaction.

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