Nickel-based metal organic framework material, preparation method thereof and application of nickel-based metal organic framework material in simultaneous capture of N2O and CO2

Abstract

The application relates to the technical field of metal-organic coordination polymer crystalline material, in particular to a nickel-based metal-organic framework material, a preparation method thereof and application of the nickel-based metal-organic framework material in simultaneous capture of N2O and CO2, the chemical molecular formula of which is C 12 H 18 N4NiO6, an organic ligand 1H-pyrazole-4-carboxylic acid is used, and after degassing, a structural transformation occurs, and the chemical molecular formula of the transformed product is C8H6N4NiO4. The nickel-based metal-organic framework material has application potential in simultaneous capture of N2O and CO2.

Description

Technical Field

[0001] This invention relates to the field of metal-organic coordination polymer crystalline materials technology, specifically to a nickel-based metal-organic framework material, its preparation method, and its application in simultaneously capturing N2O and CO2. Background Technology

[0002] Excessive greenhouse gas emissions have had a severe impact on the global climate, causing issues such as sea-level decline, pests and diseases, and desertification. CO2 is the most significant greenhouse gas, while CH4, N2O, and fluorine-containing gases are collectively known as non-CO2 greenhouse gases. Although their concentrations are low, their greenhouse effect is extremely high; N2O's greenhouse effect is 273 times that of CO2. The tail gas emissions from the industrial synthesis of adipic acid are the largest industrial source of N2O, with a main composition of N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4). Currently, the main methods for treating the tail gas from adipic acid synthesis are thermal decomposition and catalytic decomposition. However, thermal decomposition technology is energy-intensive and produces additional CO2 gas, while catalytic decomposition technology has a short catalyst lifespan, requiring frequent catalyst replacement and incurring high costs. Adsorption separation is relatively energy-efficient and economical. Metal-organic frameworks (MOFs) are a novel type of crystalline porous functional material, consisting of a porous network framework structure formed by metal / metal cluster nodes and organic ligands based on coordination bonds. Due to their diverse structures, tunable size, and large specific surface area, MOFs have been used as physical adsorbents in various adsorption and separation systems, such as ethylene purification from ethane / ethylene and acetylene / ethylene, and propane / propylene. Preliminary explorations have also been made in the purification and separation of non-carbon dioxide greenhouse gases, such as CH4 / N2, N2O / N2, N2O / CO2, and SF6 / N2. However, no studies have yet investigated the simultaneous capture of two greenhouse gases in the same system. Simultaneously achieving both N2O adsorption and low-pressure CO2 adsorption is crucial for the simultaneous capture of N2O and CO2 in N2O / N2 / CO2 / O2 systems, and currently, no adsorbent has been found that can simultaneously meet both conditions. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a nickel-based metal-organic framework material, its preparation method, and its application in simultaneously capturing N2O and CO2.

[0004] This invention is achieved through the following technical solution:

[0005] A nickel-based metal-organic framework material with the chemical formula C 12 H 18 N4NiO6 uses 1H-pyrazole-4-carboxylic acid as its organic ligand, with the following structure:

[0006] ;

[0007] The nickel-based metal-organic framework material undergoes a structural transformation after degassing, and the chemical formula of the transformed material is C8H6N4NiO4.

[0008] Furthermore, prior to degassing, the nickel-based metal-organic framework material has a two-dimensional framework structure; after degassing, the nickel-based metal-organic framework material has a three-dimensional framework structure.

[0009] Furthermore, from the perspective of framework connection and construction, the crystal structure of the nickel-based metal-organic framework material before degassing belongs to the monoclinic crystal system, with the space group as follows: P twenty one / c The unit cell parameters are: a=7.4193Å, b=8.3916Å, c=13.0641Å, α=90°, β=102.254°, γ=90°;

[0010] The crystal structure of the degassed nickel-based metal-organic framework belongs to the monoclinic crystal system, with space group 1. P21 / n, The unit cell parameters are: a = 5.0836(7) Å, b = 8.2916(11) Å, c = 12.4737(15) Å. α =90°, β =91.158(13)°, γ =90°.

[0011] Furthermore, in the two-dimensional framework structure, the Ni atom is six-coordinated, with four oxygen atoms and two nitrogen atoms coordinated. The two nitrogen atoms are coordinated from two different 1H-pyrazole-4-carboxylic acid ligands, the two oxygen atoms are coordinated from the carboxyl groups of two different 1H-pyrazole-4-carboxylic acid ligands, and the remaining two oxygen atoms are coordinated from two ethanol molecules.

[0012] In the two-dimensional framework structure, the Ni-O bond length of the Ni atom and the O atom on the carboxyl group of the ligand is 2.043 Å, the Ni-O bond length of the Ni atom with the hydroxyl oxygen in ethanol is 2.099 Å, and the Ni-N bond length of the Ni-N bond with the pyrazole nitrogen in the ligand is 2.068 Å.

[0013] Each 1H-pyrazole-4-carboxylic acid ligand has one nitrogen atom coordinated to one Ni atom, and one carboxyl oxygen atom coordinated to the adjacent Ni atom. That is, adjacent Ni atoms are connected by bridging ligands.

[0014] The two-dimensional framework structure has rhomboid channels with a side length of 7.6 Å, in which coordinated ethanol guest molecules are distributed.

[0015] Furthermore, in the three-dimensional framework structure of the degassed nickel-based metal-organic framework material,

[0016] The Ni atom is six-coordinated, with four oxygen atoms and two nitrogen atoms coordinated. The four oxygen atoms are from the carboxyl groups of four different ligands, and the two nitrogen atoms are from the pyrazole nitrogen in two ligands. The Ni-O bond lengths between the Ni atom and the carboxyl oxygen in the ligands are 2.166 Å and 2.080 Å, respectively, and the Ni-N bond length between the Ni atom and the pyrazole nitrogen in the ligands is 2.068 Å.

[0017] Each 1H-pyrazole-4-carboxylic acid ligand has two oxygen atoms in its carboxyl group coordinated to two Ni atoms, and a nitrogen atom coordinated to another Ni atom.

[0018] Adjacent nickel atoms are bridged by the two oxygen atoms of the carboxyl groups of two 1H-pyrazole-4-carboxylic acid ligands to form a one-dimensional chain structural unit, and the one-dimensional chains are connected by 1H-pyrazole-4-carboxylic acid ligands to form a three-dimensional framework structure.

[0019] The three-dimensional frame structure has rhomboid channels with a side length of 7.8 Å.

[0020] The present invention also provides a method for preparing the nickel-based metal-organic framework material, comprising the following steps:

[0021] Under sealed conditions, 1H-pyrazole-4-carboxylic acid and nickel nitrate hexahydrate were added to ethanol, and a solvothermal reaction was carried out to obtain crystalline C of nickel-based metal-organic framework materials. 12 H 18 N4NiO6.

[0022] Furthermore, the molar ratio of 1H-pyrazole-4-carboxylic acid to nickel nitrate hexahydrate is 1:(1~2), and each 0.06 mmol of 1H-pyrazole-4-carboxylic acid corresponds to 1 mL~3 mL of ethanol. The solvothermal reaction temperature is 60-80℃, and the reaction time is 8-48 hours.

[0023] Furthermore, the crystals of the nickel-based metal-organic framework material are further... 12 H4N4NiO4 was washed by immersion in dichloromethane to perform solvent exchange, and then degassed under vacuum to obtain the converted crystalline material C8H6N4NiO4.

[0024] The present invention also provides the application of the nickel-based metal-organic framework material in the simultaneous capture of N2O and CO2.

[0025] The beneficial technical effects of the present invention are as follows: The present invention utilizes the shortest pyrazole carboxylic acid organic ligand 1H-pyrazole-4-carboxylic acid to construct two crystal materials. The crystal material without degassing has a two-dimensional framework structure, while the crystal material after degassing has a three-dimensional framework structure. The three-dimensional framework structure has a large cubic cage, which can be used for gas adsorption and separation.

[0026] The nickel-based metal-organic framework material obtained by this invention has a high adsorption capacity for nitrous oxide and carbon dioxide, and the framework has a strong interaction with both molecules. In particular, it has a high adsorption capacity for CO2 in the low-pressure region, and can simultaneously capture N2O and CO2. Therefore, it can be used for the treatment of tail gas from the industrial synthesis of adipic acid. Attached Figure Description

[0027] Figure 1 The diagram shows the coordination environment of nickel in the two-dimensional framework structure of the nickel-based metal-organic framework materials obtained in Examples 1-3.

[0028] Figure 2 The diagram shows the coordination environment of nickel in the three-dimensional framework structure of the nickel-based metal-organic framework materials obtained in Examples 1-3 after degassing.

[0029] Figure 3 The diagram shows the two-dimensional framework structure of the nickel-based metal-organic framework materials obtained in Examples 1-3.

[0030] Figure 4 The image shows the three-dimensional framework structure of the nickel-based metal-organic framework materials obtained in Examples 1-3 after degassing.

[0031] Figure 5 This is the adsorption isotherm of nickel-based metal-organic framework materials for nitrous oxide, carbon dioxide, and nitrogen.

[0032] Figure 6 The adsorption isotherms of nickel-based metal-organic framework materials for acetylene, ethylene, and ethane are shown.

[0033] Figure 7 The dynamic penetration curve of nickel-based metal-organic framework materials for CO2 / N2 (96 / 4) is shown.

[0034] Figure 8 The dynamic penetration curve of nickel-based metal-organic framework materials for N2O / N2 (50 / 50) is shown.

[0035] Figure 9 The dynamic penetration curves of nickel-based metal-organic framework materials for N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4) are shown.

[0036] Figure 10 The dynamic penetration curves of nickel-based metal-organic framework materials for N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4) after 5 cycles are shown.

[0037] Figure 11 The dynamic penetration curves of nickel-based metal-organic framework materials for N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4) under RH=40% conditions are shown.

[0038] Figure 12 The dynamic penetration curves of the nickel-based metal-organic framework material for N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4) after 5 cycles under RH=40% conditions.

[0039] Figure 13 This is a diagram illustrating the interaction mechanism between nickel-based metal-organic frameworks and N2O.

[0040] Figure 14 This is a diagram illustrating the interaction mechanism between nickel-based metal-organic frameworks and CO2. Detailed Implementation

[0041] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0042] Example 1

[0043] Weigh 0.06 mmol of ligand 1H-pyrazole-4-carboxylic acid and 0.12 mmol of Ni(NO3)2·6H2O into a 4 mL glass vial, add 3 mL of ethanol, seal the vial, and sonicate it at room temperature for 5 minutes. After sealing, place the vial in an 80 °C oven for 8 hours. After the reaction, turn off the oven and allow it to cool to room temperature. Filter and collect the solid particles obtained in the vial, then wash them sequentially with ethanol (5 mL × 3), followed by immersion in dichloromethane. Microscopic observation revealed pale green cubic crystals (C1). 12 H 18 (N4NiO6), (yield: 64%, based on ligand).

[0044] Example 2

[0045] Weigh 0.06 mmol of ligand 1H-pyrazole-4-carboxylic acid and 0.09 mmol of Ni(NO3)2·6H2O into a 4 mL glass vial, add 2 mL of ethanol, seal the vial, and sonicate at room temperature for 5 minutes. After sealing, place the vial in a 60 °C oven for 48 hours. After the reaction, turn off the oven and allow it to cool to room temperature. Filter and collect the solid particles obtained in the vial, then wash them sequentially with ethanol (5 mL × 3), followed by immersion in dichloromethane. Microscopic observation revealed pale green cubic crystals (C...). 12 H 18 (N4NiO6), (yield: 70%, based on ligand).

[0046] Example 3

[0047] Weigh 0.06 mmol of ligand 1H-pyrazole-4-carboxylic acid and 0.06 mmol of Ni(NO3)2·6H2O into a 4 mL glass vial, add 1 mL of ethanol, seal the vial, and sonicate it at room temperature for 5 minutes. After sealing, place the vial in a 70 °C oven for 24 hours. After the reaction, turn off the oven and allow it to cool to room temperature. Filter and collect the solid particles obtained in the vial, then wash them sequentially with ethanol (5 mL × 3), followed by immersion in dichloromethane. Microscopic observation revealed pale green cubic crystals (C1). 12 H 18 (N4NiO6), (yield: 59%, based on ligand).

[0048] The test results of the products obtained in the above embodiments are the same. The products obtained in the above embodiments are soaked in dichloromethane for solvent exchange, and then degassed under vacuum to obtain the converted crystal material C8H6N4NiO4.

[0049] (1) Determination of crystal structure:

[0050] Selected crystals of appropriate size were used, and data were collected at room temperature using an Agilent Technologies SuperNova X-ray single-crystal diffractometer. Data collection was performed using Cu-Kα (λ = 1.54178 Å) target rays monochromated with a graphite monochromator. The crystal structure was obtained by direct analysis using the Olex2 program. Crystallographic data obtained before and after degassing are shown in Tables 1 and 2.

[0051] Table 1. Crystallographic data of metal-organic framework materials (before degassing)

[0052]

[0053] Table 2. Crystallographic data of metal-organic framework materials (after degassing)

[0054]

[0055] The crystal structure diagrams obtained in Examples 1-3 are as follows: Figure 1 and 3As shown, the inorganic nodes in the two-dimensional framework structure are mononuclear nickel atoms, with the Ni atoms being six-coordinated, coordinating four oxygen atoms and two nitrogen atoms. The two nitrogen atoms are from two different 1H-pyrazole-4-carboxylic acid ligands, and the two oxygen atoms are from the carboxyl groups of two different 1H-pyrazole-4-carboxylic acid ligands. The remaining two oxygen atoms are from two ethanol molecules. Each 1H-pyrazole-4-carboxylic acid ligand has one nitrogen atom and one Ni atom coordinated, and one oxygen atom of the carboxyl group coordinated with an adjacent Ni atom, meaning that adjacent Ni atoms are connected by bridging ligands. The two-dimensional framework structure has rhomboid channels with a side length of 7.6 Å, within which coordinated ethanol guest molecules are distributed.

[0056] The crystal structure after degassing is as follows Figure 2 and Figure 4 As shown, in the three-dimensional framework structure of the degassed nickel-based metal-organic framework material, the Ni atom is six-coordinated, with four oxygen atoms and two nitrogen atoms coordinated. The four coordinated oxygen atoms come from the carboxyl groups of four different ligands, and the two coordinated nitrogen atoms come from the pyrazole nitrogen in two ligands. The two oxygen atoms of the carboxyl group of each 1H-pyrazole-4-carboxylic acid ligand are coordinated with two Ni atoms, and the nitrogen atom is coordinated with another Ni atom. Adjacent nickel atoms are bridged by the two oxygen atoms of the carboxyl groups of two 1H-pyrazole-4-carboxylic acid ligands to form one-dimensional chain structural units. The one-dimensional chains are connected by 1H-pyrazole-4-carboxylic acid ligands to form a three-dimensional framework structure. The three-dimensional framework structure has rhomboid channels with a side length of 7.8 Å.

[0057] Example 4

[0058] The adsorption isotherms of nitrous oxide, carbon dioxide, nitrogen, acetylene, ethylene, and ethane were tested on the degassed metal-organic framework material. The results are as follows: Figure 5 and Figure 6 As shown in the figure, the maximum adsorption capacities of this material for N2O and CO2 at 298 K are 78.8 cmg and 78.8 cmg, respectively. -1 74.3 cmg -1 This indicates that the material has a high adsorption capacity for both gases, and both gases exhibit extremely strong interactions with the framework, specifically demonstrating a very steep adsorption trend in the low-pressure region. Therefore, this material has the potential to simultaneously capture N2O and CO2 from adipic acid tail gas.

[0059] Example 5 Penetration Test

[0060] The degassed crystalline material sample was packed into a quartz glass column, and penetration tests were performed using CO2 / N2 (4 / 96) and N2O / N2 (50 / 50), respectively. The results are as follows. Figure 7 and Figure 8As shown, this demonstrates the excellent separation effect of the material on CO2 / N2 and N2O / N2.

[0061] Example 6: Exhaust Gas Simulation Experiment

[0062] The degassed crystalline material sample was packed into a quartz glass column. A penetration test was performed using a mixed gas of N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4). The results are as follows. Figure 9 As shown, this indicates that the material can simultaneously capture N2O and CO2 with this composition. Furthermore, its separation performance did not decrease after five rounds of testing. Figure 10 .

[0063] To more realistically simulate the actual exhaust gas environment, the dynamic separation performance of the four components N2O / N2 / CO2 / O2 (48 / 44 / 4 / 4) was tested under RH=40% conditions. The results are as follows: Figure 11 Under RH=40% conditions, this material can still simultaneously capture N2O and CO2. Furthermore, its separation performance remained unchanged after five rounds of testing. Figure 12 .

[0064] Example 7: Loaded Single Crystal Testing and Mechanism Analysis

[0065] To more clearly analyze the adsorption mechanism, we conducted single-crystal X-ray diffraction tests on N2O and CO2-loaded single crystals. The analysis revealed multiple CH···N and CH···O interactions between the framework and N2O, and multiple CH···O interactions with CO2. Furthermore, the appropriate pore size exerted a strong confinement effect on N2O and CO2. (See...) Figure 13 , Figure 14 .

Claims

1. A nickel-based metal-organic framework material, characterized in that: The chemical formula is C 12 H 18 N4NiO6 uses 1H-pyrazole-4-carboxylic acid as its organic ligand, with the following structure: ； The nickel-based metal-organic framework material undergoes a structural transformation after degassing, and the chemical formula of the transformed material is C8H6N4NiO4. From the perspective of framework connection and construction, the crystal structure of nickel-based metal-organic framework materials before degassing belongs to the monoclinic crystal system, with the space group as follows: P twenty one / c The unit cell parameters are: a=7.4193Å, b=8.3916Å, c=13.0641Å, α=90°, β=102.254°, γ=90°; The crystal structure of the degassed nickel-based metal-organic framework belongs to the monoclinic crystal system, with space group 1. P21 / n, The unit cell parameters are: a = 5.0836(7) Å, b = 8.2916(11) Å, c = 12.4737(15) Å. α =90°, β =91.158(13)°, γ =90°; The preparation method of the nickel-based metal-organic framework material includes the following steps: under sealed conditions, 1H-pyrazole-4-carboxylic acid and nickel nitrate hexahydrate are added to ethanol, and the nickel-based metal-organic framework material crystal C is obtained through a solvothermal reaction. 12 H 18 N4NiO6; The molar ratio of 1H-pyrazole-4-carboxylic acid to nickel nitrate hexahydrate is 1:(1~2), and each 0.06 mmol of 1H-pyrazole-4-carboxylic acid corresponds to 1 mL~3 mL of ethanol. The solvothermal reaction temperature is 60-80℃, and the reaction time is 8-48 hours.

2. The nickel-based metal-organic framework material according to claim 1, characterized in that: Before degassing, the nickel-based metal-organic framework material has a two-dimensional framework structure; after degassing, the nickel-based metal-organic framework material has a three-dimensional framework structure.

3. The nickel-based metal-organic framework material according to claim 2, characterized in that: In the two-dimensional framework structure, the Ni atom is six-coordinated, with four oxygen atoms and two nitrogen atoms coordinated. The two nitrogen atoms are from two different 1H-pyrazole-4-carboxylic acid ligands, the two oxygen atoms are from the carboxyl groups of two different 1H-pyrazole-4-carboxylic acid ligands, and the remaining two oxygen atoms are from two ethanol molecules. In the two-dimensional framework structure, the Ni-O bond length of the Ni atom and the O atom on the carboxyl group of the ligand is 2.043 Å, the Ni-O bond length of the Ni atom with the hydroxyl oxygen in ethanol is 2.099 Å, and the Ni-N bond length of the Ni-N bond with the pyrazole nitrogen in the ligand is 2.068 Å. Each 1H-pyrazole-4-carboxylic acid ligand has one nitrogen atom coordinated to one Ni atom, and one carboxyl oxygen atom coordinated to the adjacent Ni atom, meaning that adjacent Ni atoms are connected by bridging ligands. The two-dimensional framework structure has rhomboid channels with a side length of 7.6 Å, in which coordinated ethanol guest molecules are distributed.

4. The nickel-based metal-organic framework material according to claim 2, characterized in that: In the three-dimensional framework structure of the degassed nickel-based metal-organic framework material, the Ni atom is six-coordinated, with four oxygen atoms and two nitrogen atoms coordinated. The four coordinated oxygen atoms come from the carboxyl groups of four different ligands, and the two coordinated nitrogen atoms come from the pyrazole nitrogen in two ligands. The Ni-O bond lengths between the Ni atom and the carboxyl oxygen in the ligand are 2.166 Å and 2.080 Å, respectively, and the Ni-N bond length between the Ni atom and the pyrazole nitrogen in the ligand is 2.068 Å. Each 1H-pyrazole-4-carboxylic acid ligand has two oxygen atoms in its carboxyl group coordinated to two Ni atoms, and a nitrogen atom coordinated to another Ni atom. Adjacent nickel atoms are bridged by the two oxygen atoms of the carboxyl groups of two 1H-pyrazole-4-carboxylic acid ligands to form a one-dimensional chain structural unit, and the one-dimensional chains are connected by 1H-pyrazole-4-carboxylic acid ligands to form a three-dimensional framework structure. The three-dimensional frame structure has rhomboid channels with a side length of 7.8 Å.

5. The nickel-based metal-organic framework material according to claim 1, characterized in that: The crystal C of the nickel-based metal-organic framework material 12 H4N4NiO4 was washed by immersion in dichloromethane to perform solvent exchange, and then degassed under vacuum to obtain the converted crystalline material C8H6N4NiO4.

6. The application of a nickel-based metal-organic framework material as described in any one of claims 1-5 in the simultaneous capture of N2O and CO2.

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