Cerium and zirconium double-metal porphyrin-based MOF (Metal Organic Framework) catalyst as well as preparation method and application thereof

Abstract

The invention provides a cerium and zirconium double-metal porphyrin-based MOF (Metal Organic Framework) catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalyst preparation. In the cerium and zirconium bimetallic porphyrin-based MOF catalyst, cerium ions (Ce < 3 + >) are doped in MOF-525, and Zr < 4 + > is partially replaced by Ce < 3 + >; due to the introduction of Ce < 3 + >, additional acid sites can be introduced into MOF-525, and the acid sites are beneficial to promoting a carbon dioxide conversion reaction; in addition, by adjusting the doping amount of cerium, optimizing the acid distribution of the catalyst and improving the reaction rate and selectivity, the reaction for directly synthesizing dimethyl carbonate from carbon dioxide and methanol is facilitated, and the method has good practicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and in particular relates to a cerium and zirconium bimetallic porphyrin-based MOF catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon dioxide (CO2) produced by fossil fuel combustion contributes to the greenhouse effect, significantly impacting the environment. From an energy utilization perspective, CO2, a non-toxic, inexpensive, and urgently needed carbon source, is a crucial carbon source in C1 chemistry. Converting CO2 into high-value-added organic chemical intermediates meets the requirements of environmentally friendly and cost-effective industrialization. The conversion of CO2 into dimethyl carbonate (DMC) is a key synthetic route.

[0003] DMC is an environmentally friendly, green organic chemical. Due to its excellent biodegradability and chemical structure, it is widely used as a methylation and carbonylation reagent, as well as a raw material for the production of polycarbonate. Furthermore, DMC can be used as a gasoline additive and an electrolyte solution for lithium-ion batteries. Current industrial DMC synthesis methods are hampered by high raw material toxicity, high production costs, and complex byproducts. Therefore, the direct method for preparing DMC using CO2 and methanol offers great potential for application. Both the raw materials and products of this direct method are non-toxic, with the only byproduct being environmentally friendly water. This process offers extremely high atom utilization, aligning with the principles of green chemistry. However, this reaction is subject to thermodynamic constraints, preventing it from proceeding spontaneously, and CO2 activation is difficult. Therefore, the design and development of efficient catalysts to reduce the reaction energy barrier has become a key focus of researchers.

[0004] Metal-organic frameworks (MOFs) are a class of crystalline porous materials composed of various organic ligands and metal ions or metal clusters. They have large specific surface area, highly developed porosity, good thermal stability, and tunable metal centers and organic ligands, and have broad application prospects in heterogeneous catalysis. Therefore, a MOF catalyst can be developed for the direct synthesis of dimethyl carbonate from carbon dioxide and methanol. Summary of the Invention

[0005] In view of some deficiencies in the prior art, the present invention provides a cerium-zirconium bimetallic porphyrin-based MOF catalyst and its preparation method and application; in the cerium-zirconium bimetallic porphyrin-based MOF catalyst of the present invention, MOF-525 is doped with cerium ions (Ce 3+ ), using Ce 3+ Partial replacement of Zr 4+ ions; Ce 3+The introduction can introduce additional acidic sites in MOF-525, and these acidic sites contribute to promoting the carbon dioxide conversion reaction; the present invention also optimizes the acidic distribution of the catalyst by adjusting the doping amount of cerium, improves the reaction rate and selectivity, which is beneficial to the direct synthesis of dimethyl carbonate from carbon dioxide and methanol, and has good practicability.

[0006] In order to achieve the above technical purpose, the present invention adopts the following technical means: The present invention first provides a cerium and zirconium bimetallic porphyrin-based MOF catalyst, and the cerium and zirconium bimetallic porphyrin-based MOF catalyst replaces part of the Zr 4+ metal nodes in MOF-525 with Ce 3+ metal ions, and the Ce 3+ and Zr 4+ metal ions are uniformly distributed in the framework structure of the MOF material; the cerium and zirconium bimetallic porphyrin-based MOF catalyst presents a uniform porous structure, and the particle size range is 500 nm - 1 μm; the cerium and zirconium bimetallic porphyrin-based MOF catalyst has a ftw micro-topological structure, which presents a relatively regular regular hexahedron shape.

[0007] The present invention also provides a preparation method of the above-mentioned cerium and zirconium bimetallic porphyrin-based MOF catalyst, and the preparation method includes: Dissolve soluble zirconium salt and soluble cerium salt in a polar amide solvent, then add meso-tetrakis(4-carboxyphenyl)porphyrin (H2TCPP) thereto, stir until completely dissolved, then add the regulator acetic acid, and stir and mix evenly to obtain a mixed solution; perform a heating-condensation reflux reaction on the mixed solution, and after the reaction is completed, wash, centrifuge, and dry to obtain the cerium and zirconium bimetallic porphyrin-based MOF catalyst.

[0008] Preferably, the soluble zirconium salt includes any one of ZrOCl2·8H2O, ZrCl4 or Zr(NO3)4·5H2O; The soluble cerium salt includes any one of Ce(NO3)3·6H2O and CeCl3; The polar amide solvent includes any one of N,N-dimethylformamide, N,N-diethylformamide or N,N-dimethylacetamide.

[0009] Preferably, the soluble zirconium salt is ZrOCl2·8H2O; The soluble cerium salt is Ce(NO3)3·6H2O; The polar amide solvent is N,N-dimethylformamide.

[0010] Preferably, the molar ratio of the total amount of the soluble zirconium salt and the soluble cerium salt to meso-tetrakis(4-carboxyphenyl)porphyrin is 15:1 to 13:2; wherein, the molar ratio of the soluble zirconium salt to the soluble cerium salt is 19:1 to 1:1.

[0011] Preferably, the molar ratio of the total amount of the soluble zirconium salt and the soluble cerium salt to meso-tetrakis(4-carboxyphenyl)porphyrin is 12:1; The molar ratio of the soluble zirconium salt to the soluble cerium salt is 9:1 to 7:3, preferably 4:1.

[0012] Preferably, the addition amount of the acetic acid is: 7 - 50 mL of acetic acid is added to every 100 mL of the reaction solution; preferably, the addition amount of acetic acid is 8 mL of acetic acid added to every 100 mL of the reaction solution.

[0013] Preferably, the conditions of the heating-condensation reflux reaction are to react at 100 - 160 °C for 10 - 24 h.

[0014] Preferably, the conditions of the heating-condensation reflux reaction are to react at 120 °C for 10 h.

[0015] The present invention also provides an application of the above cerium, zirconium bimetallic porphyrin-based MOF catalyst in the direct synthesis of dimethyl carbonate from carbon dioxide and methanol.

[0016] Preferably, the application includes: Putting methanol, a dehydrating agent, carbon dioxide and the above cerium, zirconium bimetallic porphyrin-based MOF catalyst into a high-pressure reaction kettle, heating and reacting under stirring conditions, and after the reaction is completed, dimethyl carbonate is obtained.

[0017] Preferably, the conditions of the heating reaction are 100 - 160 °C, preferably 140 °C.

[0018] Preferably, the dehydrating agent includes one of trimethyl orthoformate, 2-cyanopyridine, and anhydrous calcium chloride; preferably trimethyl orthoformate.

[0019] Catalytic mechanism for the direct synthesis of dimethyl carbonate from carbon dioxide and methanol: CO2 + CH3OH → DMC + H2O Catalysis is carried out relying on the acid-base sites of the catalyst. Methanol is activated into a methyl group and a methoxy group at the acidic and basic sites respectively. Carbon dioxide adsorbed on the basic center reacts with the methoxy group to form a methoxy bicarbonate anion, and then the methoxy bicarbonate anion further reacts with the methyl oxonium ion to generate dimethyl carbonate.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The zirconium-based MOF material MOF-525 of the present invention is composed of Zr6 clusters as metal nodes and meso-tetra(4-carboxyphenyl)porphyrin as ligands. Then, part of the Zr 4+ metal ions are replaced with Ce 3+ metal ions to prepare the cerium-zirconium bimetallic porphyrin-based MOF catalyst. This replacement method enables the Ce 3+ and Zr 4+ metal ions to be evenly distributed in the framework structure of the MOF material, forming uniformly dispersed active sites. These active sites are directly exposed to the pores and surface of the MOF, without the need for additional carrier support, thus ensuring the high activity and reaction efficiency of the catalyst. Microscopically, the catalyst exhibits a uniform porous structure, with good reactant diffusion performance and mass transfer efficiency. The particle size range of the catalyst is 500 nm - 1 μm. In addition, the catalyst has a rich pore structure, mainly mesopores, and these pore structures help to increase the specific surface area and reaction activity of the catalyst.

[0021] (2) In the cerium-zirconium bimetallic porphyrin-based MOF catalyst of the present invention, the zirconium-based MOF material has rich acid-base sites, a large specific surface area (2736.22 m 2 ·g -1 ) and a relatively appropriate pore size (20 Å) and a regular structure (ftw); cerium is a rare earth element with a unique electronic structure and catalytic properties, capable of providing multiple oxidation states, thus playing an important role in catalytic reactions. Cerium doping can introduce additional acidic sites in MOF-525, and these acidic sites help to promote the carbon dioxide conversion reaction. In addition, by adjusting the doping amount of cerium in the present invention, the acidic distribution of the catalyst can be optimized, the reaction rate and selectivity can be improved, and the redox properties of cerium can promote the transfer of electrons and the formation of reaction intermediates, which is crucial for the kinetic process of catalytic reactions. The 20 Å pore size of the catalyst is beneficial to the diffusion of reactants and products, reducing the mass transfer resistance and further enhancing the catalytic performance. The regular ftw topological structure helps to maintain the stability of the catalyst and provides an ordered channel for reactants, promoting the progress of the reaction.

[0022] (3) In the catalyst of the present invention, the doping amount range of cerium is 0 - 2% (Atomic Fraction). Although the doping amount is low, the catalytic performance of the catalyst is significantly improved, and at the same time, it exhibits excellent stability. This low-doping design not only optimizes the acidic site distribution of the catalyst but also enhances the stability of the catalyst through the following mechanism: Uniformly distributed active sites: Cerium ions are uniformly distributed in the MOF framework, avoiding structural defects or aggregation phenomena that may be caused by high doping levels. This uniformly distributed active sites helps to maintain the structural integrity of the catalyst, thereby improving its stability during the reaction process.

[0023] Anti-coking effect of low doping amount: Cerium ions with low doping amount show good anti-coking ability during the reaction process. Coking is one of the common reasons for catalyst deactivation, and the design of low doping amount effectively reduces the formation of coke, thereby extending the service life of the catalyst.

[0024] Economic benefits and practicality: The low doping amount not only improves the performance of the catalyst, but also significantly reduces the preparation cost, making it more economical and practical in actual applications.

[0025] (4) During the preparation process of the catalyst of the present invention, acetic acid is used as an acidic regulator, which can significantly affect the crystallization process and final morphology of MOF. In the reaction system, acetic acid competes for coordination with carboxyl ligands. Adding an appropriate amount of acetic acid during the preparation of zirconium-based MOF is beneficial to the formation of its regular structure, making the catalyst of the present invention form a regular hexahedron structure. The addition amount of acetic acid is positively correlated with the particle size of the cerium-zirconium bimetallic porphyrin-based MOF catalyst. An appropriate amount of acetic acid can slow down the crystallization rate, allowing the crystals to have enough time to grow, thus forming larger particle sizes. On the contrary, less acetic acid will lead to an accelerated crystallization rate and form smaller particle sizes, because too low acetic acid concentration cannot effectively regulate the acidity and crystallization kinetics of the solution, resulting in incomplete crystal growth or irregular morphology.

[0026] (5) Compared with the prior art, the cerium-zirconium bimetallic porphyrin-based MOF catalyst of the present invention shows a significant improvement in catalytic performance and the yield of DMC (dimethyl carbonate): In the reaction of directly synthesizing DMC from carbon dioxide and methanol, the DMC yield of the catalyst of the present invention is 1.11 times higher than that of the undoped catalyst, and the yield is significantly improved; during 3 cycles of use, the activity decay rate of the catalyst of the present invention is less than 5%, showing good stability and reusability. It can be seen that the catalyst of the present invention is superior to the prior art in terms of catalytic performance and DMC yield, and has significant practicality and economy. Description of the Drawings

[0027] Figure 1 It is the topological structure diagram of MOF-525.

[0028] Figure 2 It is the SEM image of MOF-525.

[0029] Figure 3Scanning electron microscopy (SEM) images of MOF-525 (a) and its doped and modified Ce-MOF-525-X (b-f).

[0030] Figure 4 SEM image of a cerium and zirconium bimetallic porphyrin-based MOF catalyst with a cerium content of 20%.

[0031] Figure 5 XRD patterns of cerium and zirconium bimetallic porphyrin-based MOF catalysts with different cerium contents. Detailed implementation manners

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] Example 1: Preparation of cerium and zirconium bimetallic porphyrin-based MOF catalyst At room temperature, 625 mg of ZrOCl2·8H2O and 13.35 mg of Ce(NO3)3·6H2O were dissolved in 100 mL of DMF, then 125 mg of H2TCPP was added thereto, stirred until completely dissolved, and then 8 mL of acetic acid was added and stirred evenly to obtain a mixed solution. The mixed solution was heated and refluxed at 120 °C for 24 h. After the reaction, it was washed, centrifuged, and dried to obtain a cerium and zirconium bimetallic porphyrin-based MOF catalyst with a cerium content of 5%, denoted as MOF-525-0.05.

[0034] Combined Figure 1 and Figure 2 It can be seen that the cerium and zirconium bimetallic porphyrin-based MOF catalyst has a ftw microscopic topological structure (as shown in Figure 1 ), presenting a relatively regular regular hexahedron shape (as shown in Figure 2 ). Microscopically, the cerium and zirconium bimetallic porphyrin-based MOF catalyst presents a uniform porous structure, having good reactant diffusion performance and mass transfer efficiency; the particle size range of the cerium and zirconium bimetallic porphyrin-based MOF catalyst is 500 nm - 1 μm. In addition, it can be seen from the figure that the cerium and zirconium bimetallic porphyrin-based MOF catalyst has a rich pore structure, mainly mesopores, and these pore structures help to increase the specific surface area and reaction activity of the catalyst.

[0035] Example 2: Preparation of cerium and zirconium bimetallic porphyrin-based MOF catalyst 600 mg of ZrOCl2·8H2O and 26.70 mg of Ce(NO3)3·6H2O were dissolved in 100 mL of DMF at room temperature, and then 125 mg of H2TCPP was added thereto and stirred until completely dissolved. Then, 8 mL of acetic acid was added and stirred to obtain a mixed solution. The mixed solution was heated at 120 °C and refluxed under condensation for 24 h. After the reaction, the mixture was washed, centrifuged, and dried to obtain a cerium and zirconium bimetallic porphyrin-based MOF catalyst with a cerium content of 10%, which was recorded as MOF-525-0.1.

[0036] Figure 3 Scanning electron microscope (SEM) images of MOF-525 (a) and its doped modified Ce-MOF-525-X (bf). As can be seen from the figure, the undoped MOF-525 presents a regular cubic structure, while the doped Ce-MOF-525-X shows different morphological characteristics. When the cerium doping ratio is low (X=0.05, 0.1, 0.2), Ce-MOF-525-0.05, Ce-MOF-525-0.1, and Ce-MOF-525-0.2 still maintain the main morphology of the cube, but compared with the original MOF-525, their surfaces appear to be concave inward, and the degree of concavity gradually increases with the increase of the doping ratio. When the doping ratio reaches X=0.2, the surface of the cube begins to show slightly rough features, which may be due to the Ce 3+ The introduction of Ce resulted in some defects in the crystal structure. However, when the doping ratio was further increased (X>0.2), the catalyst particles could not maintain a regular and symmetrical cubic structure, and obvious deformation, wrinkling and breakage occurred. This change may be related to the large amount of Ce 3+ Replace the original Zr 4+ The results show that the proportion of distorted metal clusters in the particles increases significantly, thus destroying the overall stability of the crystal. This phenomenon shows that the regulation of the doping ratio plays an important role in maintaining the morphology and structural integrity of the material.

[0037] Example 3: Preparation of Cerium and Zirconium Bimetallic Porphyrin-Based MOF Catalyst 587.5 mg of ZrOCl2·8H2O and 40.05 mg of Ce(NO3)3·6H2O were dissolved in 100 mL of DMF at room temperature, and then 125 mg of H2TCPP was added thereto and stirred until completely dissolved. Then, 8 mL of acetic acid was added and stirred to obtain a mixed solution. The mixed solution was heated at 120 °C and refluxed for 24 h. After the reaction, it was washed, centrifuged, and dried to obtain a cerium and zirconium bimetallic porphyrin-based MOF catalyst with a cerium content of 20%, which was recorded as MOF-525-0.2.

[0038] Figure 4 This is the SEM image of the cerium-zirconium bimetallic porphyrin-based MOF catalyst with 20% cerium content. It can be seen from the figure that for the MOF-525 material doped with a certain amount of cerium element, there are inward depressions on the surface, and the edges of some crystal particles have become more irregular. These observations are consistent with the SEM image analysis.

[0039] Example 4: Preparation of Cerium-Zirconium Bimetallic Porphyrin-Based MOF Catalyst At room temperature, 575 mg of ZrOCl2·8H2O and 53.40 mg of Ce(NO3)3·6H2O were dissolved in 100 mL of DMF. Then, 125 mg of H2TCPP was added thereto and stirred until completely dissolved. Subsequently, 8 mL of acetic acid was added and stirred evenly to obtain a mixed solution. The mixed solution was heated and refluxed at 120 °C for 24 h. After the reaction, it was washed, centrifuged, and dried to obtain a cerium-zirconium bimetallic porphyrin-based MOF catalyst with 30% cerium content, denoted as MOF-525-0.3.

[0040] Example 5: Preparation of Cerium-Zirconium Bimetallic Porphyrin-Based MOF Catalyst At room temperature, 562.5 mg of ZrOCl2·8H2O and 66.75 mg of Ce(NO3)3·6H2O were dissolved in 100 mL of DMF. Then, 125 mg of H2TCPP was added thereto and stirred until completely dissolved. Subsequently, 8 mL of acetic acid was added and stirred evenly to obtain a mixed solution. The mixed solution was heated and refluxed at 120 °C for 24 h. After the reaction, it was washed, centrifuged, and dried to obtain a cerium-zirconium bimetallic porphyrin-based MOF catalyst with 40% cerium content, denoted as MOF-525-0.4.

[0041] Figure 5 This is the XRD pattern of the cerium-zirconium bimetallic porphyrin-based MOF catalysts with different cerium contents. It can be seen from the figure that obvious diffraction peaks appeared at 2θ = 4.4°, 6.3°, and 7.7° for both MOF-525 and MOF-525 doped with cerium element, which are attributed to the (100), (110), and (200) crystal planes respectively. Although cerium element was introduced, the framework structure of MOF-525 did not change significantly, indicating that MOF-525 has good crystallization performance and structural stability. The positions of the diffraction peaks remained basically unchanged, indicating that the doping of cerium element did not cause a phase change in the crystal structure.

[0042] Table 1. Specific Surface Areas of Cerium-Zirconium Bimetallic Porphyrin-Based MOF Catalysts with 0%, 5%, 10%, 20%, 30%, and 40% Cerium Contents Table 1 shows the specific surface areas of cerium-zirconium bimetallic porphyrin-based MOF catalysts with cerium contents of 0%, 5%, 10%, 20%, 30%, and 40%. It can be seen from Table 1 that as the cerium content increases, the specific surface area of the catalyst shows a trend of first increasing and then decreasing. When the cerium content increases from 0% to 10%, the specific surface area of the catalyst increases from 2736.22 m 2 / g to 2821.75 m 2 / g. This may be because the introduction of cerium increases the pore structure of the catalyst, thereby increasing the specific surface area. When the cerium content continues to increase to 20%, the specific surface area reaches a maximum of 3207.34 m 2 / g. As the cerium content further increases to 40%, the specific surface area gradually decreases to 2109.35 m 2 / g. This may be because too high a cerium content leads to partial collapse of the pore structure of the catalyst or destruction of the crystal structure, thereby reducing the specific surface area.

[0043] In a 100 mL stainless steel autoclave, 18 mL of methanol, 3.5 mL of dehydrating agent, and 0.1 g of catalyst were added. Then, the gas in the autoclave was replaced with carbon dioxide at 0.2 MPa, the pressure was increased to 7 MPa, and the reaction was carried out at 140 °C for 4 h. After that, analysis was performed by gas chromatography to obtain the yield and formation rate of dimethyl carbonate. The analysis results are shown in Table 2.

[0044] Table 2. Yield and formation rate of dimethyl carbonate catalyzed by different catalysts Table 2 shows the yield and formation rate of dimethyl carbonate catalyzed by different catalysts. It can be seen from the table that as the cerium content increases, the yield and formation rate of dimethyl carbonate (DMC) show a trend of first increasing and then decreasing. When the cerium content increases from 0% to 20%, the yield of DMC increases from 1.23% to 2.72%. This indicates that within a certain range, the doping of cerium can improve the activity of the catalyst. However, when the cerium content further increases to 30% and 40%, the yield and formation rate of DMC decrease. The DMC yields are 2.33% and 2.27% respectively. This may be because too high a cerium content leads to instability of the catalyst structure or reduction of active sites, thereby affecting the catalytic performance. These results show that the cerium content has a significant impact on the performance of the catalyst, and the optimal catalytic effect needs to be obtained by optimizing the doping amount of cerium.

[0045] In summary, the cerium-zirconium bimetallic porphyrin-based MOF catalyst of the present invention adjusts the doping amount of cerium, optimizes the acidic distribution of the catalyst, improves the reaction rate and selectivity, is beneficial to the direct synthesis of dimethyl carbonate from carbon dioxide and methanol, and has good practicality.

[0046] The described embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Without departing from the essential content of the present invention, any obvious improvements, substitutions or variations that those skilled in the art can make all fall within the protection scope of the present invention.

Claims

1. A cerium and zirconium bimetallic porphyrin-based MOF catalyst, characterized in that, The cerium and zirconium bimetallic porphyrin-based MOF catalyst converts part of the Zr in MOF-525 into 4+ Metal ions replaced by Ce 3+ Metal ions, the Ce 3+ and Zr 4+ The metal ions are evenly distributed in the framework structure of the MOF material; the cerium and zirconium bimetallic porphyrin-based MOF catalyst presents a uniform porous structure with a particle size range of 500 nm-1 μm; the cerium and zirconium bimetallic porphyrin-based MOF catalyst has a ftw microscopic topological structure, which presents a relatively regular hexahedron shape.

2. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 1, characterized in that, The preparation method includes: Dissolve soluble zirconium salt and soluble cerium salt in a polar amide solvent, then add meso-tetrakis(4-carboxyphenyl)porphyrin thereto, stir until completely dissolved, then add the regulator acetic acid, stir and mix evenly to obtain a mixed solution; carry out a heating-condensation reflux reaction on the mixed solution, and after the reaction is completed, wash, centrifuge, and dry to obtain the cerium-zirconium bimetallic porphyrin-based MOF catalyst.

3. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 2, characterized in that, The soluble zirconium salt includes any one of ZrOCl₂·8H₂O, ZrCl₄, or Zr(NO₃)₄·5H₂O; The soluble cerium salt includes one of Ce(NO₃)₃·6H₂O and CeCl₃; The polar amide solvent includes one of N,N-dimethylformamide, N,N-diethylformamide, or N,N-dimethylacetamide.

4. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 3, characterized in that, The soluble zirconium salt is ZrOCl₂·8H₂O; The soluble cerium salt is Ce(NO₃)₃·6H₂O; The polar amide solvent is N,N-dimethylformamide.

5. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 2, characterized in that, The molar ratio of the total amount of the soluble zirconium salt and the soluble cerium salt to meso-tetrakis(4-carboxyphenyl)porphyrin is 15:1 to 13:2; wherein, the molar ratio of the soluble zirconium salt to the soluble cerium salt is 19:1 to 1:

1.

6. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 5, characterized in that, The molar ratio of the total amount of the soluble zirconium salt and the soluble cerium salt to meso-tetrakis(4-carboxyphenyl)porphyrin is 12:1; The molar ratio of the soluble zirconium salt to the soluble cerium salt is 9:1 to 7:

3.

7. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 2, characterized in that, The addition amount of the acetic acid is: adding 7 - 50 mL of acetic acid to every 100 mL of the reaction solution; The conditions for the heating-condensation reflux reaction are to react at 100 - 160 °C for 10 - 24 h.

8. The preparation method of the cerium and zirconium bimetallic porphyrin-based MOF catalyst according to claim 7, characterized in that, The addition amount of the acetic acid is: adding 8 mL of acetic acid to every 100 mL of the reaction solution; The conditions for the heating-condensation reflux reaction are to react at 120 °C for 10 h.

9. Use of the cerium-zirconium bimetallic porphyrin-based MOF catalyst according to claim 1 in the direct synthesis of dimethyl carbonate from carbon dioxide and methanol.

10. The application according to claim 9, characterized in that, The use includes: Put methanol, a dehydrating agent, carbon dioxide, and the above-mentioned cerium-zirconium bimetallic porphyrin-based MOF catalyst into a high-pressure reaction kettle, heat and react under stirring conditions, and after the reaction is completed, obtain dimethyl carbonate.

Images