Indium-based metal organic framework material with carbon dioxide adsorption and catalytic conversion performance as well as preparation method and application of indium-based metal organic framework material

Abstract

The invention relates to a preparation method of an indium-based metal organic framework material based on a viologen carboxylic acid ligand and oxalate and application of the indium-based metal organic framework material in the aspects of carbon dioxide adsorption and catalytic conversion. The target product indium-based metal organic framework material is a crystalline porous material with a special pore channel structure and a pore channel environment obtained through solvothermal synthesis. The target product has good stability and can adsorb carbon dioxide gas; the reaction of carbon dioxide and epoxide can be catalyzed under a certain condition, and the carbon dioxide is converted into cyclic carbonate. The synthesis method of the target product is simple and low in cost, and has certain application value in the directions of carbon dioxide adsorption, catalytic conversion and the like.

Description

Technical Field

[0001] The invention relates to a preparation method of an indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate radicals, and its application in carbon dioxide adsorption and catalytic conversion. Background Art

[0002] Metal-organic frameworks (MOFs) are porous materials composed of inorganic nodes and organic ligands connected by coordination bonds, forming an extended structure with a well-defined porosity, which brings excellent functions and performance. MOFs are organic-inorganic hybrid materials, which are different from inorganic porous materials and general organic complexes; they have both the rigidity of inorganic materials and the flexibility of organic materials, which makes them present great development potential and attractive development prospects in modern materials research. MOFs have attracted great interest in gas storage and separation, molecular sensing, optoelectronic materials, drug carriers, catalysis and other fields due to their unique advantages such as rich pore structure and high specific surface area, structural adjustability and easy functionalization. Among them, the diversity of organic ligands in size, shape and metal binding chemistry provides opportunities for designing MOF framework structures with target pore geometries and enables pores to be modified by functional groups. Combining various functions within a MOF framework has been envisioned as a method to produce MOFs in adsorption and catalytic processes. Mixing multiple functionalized linkers to produce MOF frameworks with specific structures and pore environments is called multivariate MOFs. However, through the rational design of ligands and the selection of metal ions, supplemented by special structural units (including oxalate, etc.), it is possible to customize the topological structure, pore environment and adsorption catalytic performance of MOFs. The selection of viologen carboxylic acid ligands, supplemented by oxalate, can be used to synthesize metal organic framework materials with specific structures and pore environments.

[0003] Climate change is one of the top ten environmental issues in the world. Studies have shown that climate change is caused by human activities, and its driving factor is greenhouse gases, especially the emission of carbon dioxide, which has a warming effect of 63%. In recent years, my country has proposed to develop a low-carbon economy and achieve the goal of "carbon peak and carbon neutrality". Therefore, it is of great significance to accurately grasp the characteristics of my country's carbon emissions and take targeted measures to reduce carbon emissions and carbon dioxide adsorption and catalytic conversion. Carbon capture technology is one of the important strategies to achieve carbon dioxide adsorption and catalytic conversion. Although the use of renewable energy is accelerating, fossil fuels are still expected to supply most of the global energy in the next few decades. Carbon capture technology can convert carbon dioxide into downstream chemicals; it can help reduce carbon dioxide emissions, adsorb carbon dioxide gas, mitigate climate change, and convert the emitted carbon dioxide gas into downstream chemicals by catalytic conversion, achieving the dual goals of environmental protection and economic benefits. It is of great theoretical and practical significance to synthesize metal organic framework materials with specific structures and pore environments to achieve carbon dioxide adsorption and catalytic conversion. Summary of the invention

[0004] The purpose of the present invention is to provide a novel indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate with good stability, and its preparation method and application in the direction of carbon dioxide adsorption and catalytic conversion.

[0005] To achieve the above-mentioned purpose, the technical solution of the present invention is as follows:

[0006] The preparation method of an indium-based metal organic framework material based on a viologen carboxylic acid ligand and an oxalate radical comprises: reacting a viologen carboxylic acid ligand 1,1'-bis(4-carboxyphenyl)(4,4'-bipyridine) dichloride H 2 bcbp·2Cl, indium nitrate and potassium oxalate were added to a mixed solution consisting of deionized water, acetonitrile and concentrated nitric acid, stirred for 20 minutes, and then transferred to a polytetrafluoroethylene reactor and heated for a period of time to obtain colorless flaky crystals, which are indium-based metal organic framework materials based on viologen carboxylic acid ligands and oxalate. Its molecular formula is [In 2 (bcbp)(μ 2 -C 2 O 4 ) 3 ]n·2nH 2 O.

[0007] Furthermore, the molar ratio of the viologen carboxylic acid ligand, indium nitrate and potassium oxalate is 3:5:12.

[0008] Furthermore, the volume ratio of the deionized water, acetonitrile and concentrated nitric acid is 2:4:1.

[0009] Furthermore, the heating temperature is 120° C. and the reaction time is 5 days.

[0010] The present invention also provides an indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate radicals prepared by the above-mentioned synthesis method; the crystal structure of the indium-based metal organic framework material is characterized by crystallization in the monoclinic C2 / c space group.

[0011] The present invention also provides the application of the indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate in the adsorption and catalytic conversion of carbon dioxide.

[0012] Furthermore, the target indium-based metal-organic framework material has a good adsorption effect on carbon dioxide.

[0013] Furthermore, the target indium-based metal-organic framework material can catalyze the reaction of adsorbed carbon dioxide with co-reactants to convert it into downstream chemical products such as cyclic carbonates.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate radicals of the present invention has a novel structural feature and pore environment, has good stability, and can be stored in the air for a long time;

[0016] The synthesis method of the present invention is simple and fast, low in cost, high in yield, high in repeatability, and easy to mass produce and popularize;

[0017] An example of an indium-based metal-organic framework material based on viologen carboxylic acid ligands and oxalate groups of the present invention has a three-dimensional framework structure, which has quadrilateral pores, and the pore walls are alternately constructed by pyridinium on positively charged viologen carboxylic acids and negatively charged oxalate groups; the target indium-based metal-organic framework material has a good adsorption effect on carbon dioxide; and can catalyze the adsorbed carbon dioxide to react with co-reactants to convert it into a downstream chemical product cyclic carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention has been generally described above, and the following drawings are used to illustrate specific embodiments of the present invention.

[0019] Figure 1 Shown is a diagram of the electrically neutral honeycomb hcb layer structure in the target indium-based metal-organic framework;

[0020] Figure 2 Shown is a three-dimensional crystal structure diagram of the target indium-based metal-organic framework (observed from the c-axis);

[0021] Figure 3 Shown is the three-dimensional 6 5 .8 Topological structure;

[0022] Figure 4Shown is the PXRD characterization pattern of the target indium-based metal-organic framework;

[0023] Figure 5 Shown is a thermal stability characterization profile of the target indium-based metal-organic framework;

[0024] Figure 6 Shown is the CO2 adsorption isotherm of the target indium-based metal-organic framework at 273K;

[0025] Figure 7 Shown is the catalytic conversion effect of the target indium-based metal-organic framework on carbon dioxide; DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1 Preparation method of target indium-based metal-organic framework material

[0028] Weigh the viologen carboxylic acid ligand 1,1'-bis(4-carboxyphenyl)(4,4'-bipyridyl) dichloride H 2 bcbp·2Cl (0.03mmol), indium nitrate (0.05mmol) and potassium oxalate (0.12mmol) were added to a mixture of deionized water (1mL), acetonitrile (2mL) and concentrated nitric acid (0.5mL), stirred for 20 minutes, transferred to a polytetrafluoroethylene reactor, heated to 120°C and reacted for 5 days to obtain colorless flaky crystals, which are indium-based metal organic framework materials based on viologen carboxylic acid ligands and oxalate, and the molecular formula is [In 2 (bcbp)(μ 2 -C 2 O 4 ) 3 ]n·2nH 2 O.

[0029] Example 2 Structural Characterization of Target Indium-Based Metal-Organic Framework Material

[0030] The crystal structure of the target indium-based metal-organic framework material was analyzed by X-ray single crystal diffraction data. The results showed that the target indium-based metal-organic framework material crystallized in the monoclinic C2 / c space group; its asymmetric unit consists of a crystallographically independent In 3+ ions, half of the bcbp ligand located at the inversion center, three and a half oxalate groups, and one lattice water molecule. 3+The ion has a 7-coordinate geometry, and the adjacent In 3+ The ions are connected by chelated oxalate to form an electrically neutral honeycomb HCB layer ( Figure 1 ); the hcb layers extend in the ac plane and are arranged in parallel along the b axis in an -AB- mode, with an interlayer spacing of The adjacent HCB layers are further supported by the BcBP ligands to form a three-dimensional framework structure ( Figure 2 ). The target indium-based metal-organic framework has a quadrilateral pore structure along the c-axis, and its pore wall is constructed alternately by pyridinium on the positively charged viologen carboxylic acid and negatively charged oxalate. 3+ The ion center is regarded as a 4-connected tetrahedral node, and the bcbp ligand and oxalate are regarded as 2-connected linkers. The structural network of the target indium-based metal-organic framework material can be simplified to a 6-c single node. 5 .8 Topology ( Figure 3 ). X-ray powder diffraction data show that the theoretical and experimental data of the target indium-based metal organic framework material are consistent ( Figure 4 ), indicating that the target material has good sample purity and crystallinity.

[0031] Example 3 Thermal stability of target indium-based metal-organic framework materials

[0032] The thermal stability of the target indium-based metal-organic framework material is characterized by heating the sample to 600°C in a nitrogen environment using a thermogravimetric analyzer, and judging its stable temperature range by the weight loss of the sample during heating. Figure 5 As shown, the skeleton structure of the target material can be stable up to 325°C; after that, the main framework structure of the target material begins to collapse.

[0033] Example 4 Adsorption performance of target indium-based metal-organic framework materials for carbon dioxide

[0034] The target indium-based metal organic framework material exhibits good carbon dioxide adsorption performance, and its adsorption capacity for carbon dioxide is 1.05mmol at 273K and 1 atmosphere. . g -1 ( Figure 6 ); attributed to the pore structure of the target material and the pore environment containing pyridinium.

[0035] Example 5: Conversion performance of target indium-based metal organic framework materials to carbon dioxide

[0036] 1mmol of the ground target indium-based metal organic framework material was used as a reaction catalyst to catalyze the conversion of carbon dioxide at 60°C. 2mmol of epibromopropane and 1bar of carbon dioxide were selected as reactants and reacted at 60°C for 36 hours. The products were determined by nuclear magnetic resonance hydrogen spectrum, and the yields of cyclic carbonates reached 96% ( Figure 7 ); indicating that the target indium-based metal organic framework material has a good cycloaddition catalytic effect on the catalytic conversion reaction of carbon dioxide. At the same time, as a comparison catalyst (potassium oxalate and viologen carboxylic acid ligand H 2 bcbp·2Cl), under the same conditions, the yields of the catalytic conversion reaction of carbon dioxide were 17% and 25%, respectively. The catalytic conversion rate of the target indium-based metal-organic framework material, under the same conditions, also far exceeds the catalytic conversion rate of alkaline catalysts (potassium carbonate, n-butyl potassium and potassium hydroxide).

Claims

1. A method for preparing an indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate, characterized in that: include: The viologen carboxylic acid ligand 1,1'-bis(4-carboxyphenyl)(4,4'-bipyridine) dichloride H2bcbp·2Cl, indium nitrate and potassium oxalate are added to a mixed solution consisting of deionized water, acetonitrile and concentrated nitric acid, stirred for 20 minutes, transferred to a polytetrafluoroethylene reactor, heated to 120°C and reacted continuously for 5 days to obtain colorless flaky crystals, which are indium-based metal-organic framework materials based on viologen carboxylic acid ligands and oxalate, and have a molecular formula of [In2(bcbp)(μ2-C2O4)3]n·2nH2O; wherein the molar ratio of the viologen carboxylic acid ligand, indium nitrate and potassium oxalate is 3:5:12; and the volume ratio of the deionized water, acetonitrile and concentrated nitric acid is 2:4:

1.

2. The indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate as claimed in claim 1, crystallized in the monoclinic C2 / c space group; X-ray single crystal diffraction data show that its asymmetric unit consists of a crystallographically independent In 3+ ion, half of the bcbp ligand located at the inversion center, three and a half oxalate radicals and one lattice water molecule; In 3+ The ion has a 7-coordinate geometry, and the adjacent In 3+ The ions are connected by chelated oxalate to form electrically neutral honeycomb hcb layers; the hcb layers extend in the ac plane and are arranged in parallel along the b axis in an -AB- pattern with an interlayer spacing of The adjacent hcb layers are further supported by the bcbp ligands to form a three-dimensional framework structure. The target indium-based metal-organic framework has a quadrilateral pore structure along the c-axis, and its pore walls are alternately constructed by pyridinium on the positively charged viologen carboxylic acid and negatively charged oxalate. Topologically, In 3+ The ion center is regarded as a 4-connected tetrahedral node, and the bcbp ligand and oxalate are regarded as 2-connected linkers. The structural network of the target indium-based metal-organic framework material can be simplified to a 6-c single node. 5 .8Topological structure.

3. The indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate as described in claim 2 has good thermal stability; thermogravimetric data show that its skeleton structure can be stabilized to 325°C.

4. Application of the stable indium-based metal organic framework material based on viologen carboxylic acid ligands and oxalate as described in claim 3 in the adsorption and catalytic conversion of carbon dioxide.

5. The use according to claim 4, characterized in that: The target viologen carboxylic acid ligand and indium-based metal organic framework material with oxalate has a good adsorption effect on carbon dioxide. Its adsorption capacity for carbon dioxide at 273K and 1 atmosphere is 1.05mmol. . g -1 ; and under certain conditions, carbon dioxide can be catalytically converted into cyclic carbonates.

6. The use according to claim 5, characterized in that: 1mmol of the target indium-based metal-organic framework material was used as a reaction catalyst to achieve catalytic conversion of carbon dioxide at 60°C; the reactant epibromohydrin reacted with carbon dioxide for 36 hours, and the catalytic conversion yield could reach 96%. This catalytic conversion rate far exceeded the catalytic conversion rates of the reference catalyst (potassium oxalate and viologen carboxylic acid ligand H2bcbp·2Cl) and alkaline catalysts (potassium carbonate, n-butyl potassium and potassium hydroxide) under the same conditions, indicating that the target indium-based metal-organic framework material has a good catalytic conversion effect on carbon dioxide.

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