Metal organic framework for removing butadiene in 1-butene as well as preparation method and application of metal organic framework

Abstract

The invention belongs to the technical field of adsorption separation materials, and particularly relates to a metal organic framework for removing butadiene in 1-butene as well as a preparation method and application of the metal organic framework. The metal organic framework is characterized in that metal ions in metal salt are respectively coordinated with oxygen atoms of two carboxylic acid organic ligands and nitrogen atoms on two nitrogen-containing organic ligands to form tetrahedral coordination; the metal ions in the two parallel tetrahedral ligands are bridged through single-bond oxygen atoms on the carboxylic acid organic ligands to construct a one-dimensional chain; two adjacent one-dimensional chains are coordinated through four nitrogen-containing organic ligands and are further connected to obtain the metal organic framework with a three-position network structure. The metal organic framework has extremely high adsorption capacity on butadiene under low pressure and prevents 1-butene molecules from entering in the whole pressure range, so that impurity removal of butadiene in 1-butene is realized.

Description

Technical Field

[0001] This invention belongs to the field of adsorption separation materials technology, specifically relating to a metal-organic framework for removing butadiene from 1-butene. Background Technology

[0002] 1-Butene is a crucial comonomer and chemical feedstock in the petrochemical and polymer industries, primarily used in the synthesis of poly(linear low-density polyethylene) and high-density polyethylene. However, industrially produced 1-butene typically originates from the C4 hydrocarbon fraction of fluidized bed catalytic cracking products, with a 1-butene content of approximately 10% and the presence of 0.5% butadiene impurities in the mixed components. The presence of butadiene impurities not only prevents the 1-butene comonomer from meeting quality specifications but also affects the molecular chain structure and regularity of the copolymer, thereby impairing product performance. Therefore, removing butadiene from 1-butene is crucial for achieving polymer-grade products. Due to their very similar physicochemical properties—1-butene has a boiling point of -6.1°C, while butadiene has a boiling point of -4.4°C—and their similar kinetic diameters, removing butadiene from 1-butene is extremely challenging.

[0003] Currently, the industrial use of modified palladium-based noble metal catalysts for selective hydrogenation has drawbacks. High loading of the modifier reduces the dispersion of the noble metal, leading to a decrease or uneven distribution of its active sites. Furthermore, high-temperature treatment can cause over-hydrogenation to generate butane, or the isomerization products of 1-butene, such as cis-2-butene or trans-2-butene, which can also cause hydrogenation of some 1-butene. In addition to generating 1-butene, 2-butene may also be generated, resulting in an impure final product. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a metal-organic framework, its preparation method and application, which solves the technical problem of impure products when using catalysts to remove butadiene from 1-butene in the above-mentioned background art.

[0005] The present invention adopts the following technical solution: A metal-organic framework is provided, wherein a metal ion from a metal salt is coordinated with two carboxylic acid organic ligands and two nitrogen-containing organic ligands to form tetrahedral coordination. The carboxylic acid organic ligands coordinate with the metal ion through oxygen atoms, and the nitrogen-containing organic ligands coordinate with the metal ion through nitrogen atoms. The metal ion is bridged with the single-bonded oxygen atoms on the carboxylic acid organic ligands to construct a one-dimensional chain structure. Four adjacent one-dimensional chain structures are coordinated and connected through nitrogen-containing organic ligands to obtain a metal-organic framework with a three-dimensional network structure.

[0006] Preferably, the metal-organic framework has a pore size of 0.3~2.0 nm and a pore volume of 0.1~0.8 cm³. 3 / g, porosity 20~35%, specific surface area 200~800m² 2 / g.

[0007] Preferably, the anion in the metal salt is any one of nitrate, halide, perchlorate, carbonate, sulfate, fluoroborate, and acetate; the carboxylic acid organic ligand is a tetradentate carboxylic acid organic ligand; and the nitrogen-containing organic ligand is a tetradentate imidazole ligand.

[0008] Preferably, the tetradentate carboxylic acid organic ligand is 1,4,5,8-naphthalenetetracarboxylic acid or 1,4,5,8-naphthalenetetracarboxylic anhydride.

[0009] Preferably, the tetradentate imidazole ligand is 1,2,4,5-tetra(1H-imidazol-1-yl)benzene.

[0010] A method for preparing a metal-organic framework includes the following steps: A metal-organic framework is obtained by mixing a metal salt, a carboxylic acid organic ligand, and a nitrogen-containing organic ligand, adding the mixture to a solution, heating, filtering, and activating the mixture; the solution consists of an organic solvent and water.

[0011] Preferably, the ratio of the metal salt, carboxylic acid organic ligand, nitrogen-containing organic ligand, and the mixed solution is 1 mmol: 0.1 mmol to 10 mmol: 0.1 mmol to 10 mmol: 30 mL to 200 mL; the heating temperature is 60 to 240 °C for 48 to 90 h; and the activation temperature is 80 to 150 °C for 8 to 16 h. Preferably, the organic solvent is any one of methanol, N,N-dimethylformamide, acetonitrile, and isopropanol.

[0012] Preferably, the volume ratio of the organic solvent to water is 1~99:99~1.

[0013] Preferably, the metal-organic framework is used for the removal of butadiene from 1-butene.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) In this invention, the metal-organic framework is obtained by coordinating metal ions in the metal salt with carboxylic acid organic ligands and nitrogen-containing organic ligands respectively to obtain tetrahedral coordination. Then, the metal ions in the parallel tetrahedral coordination are bridged by carboxylic acid organic ligands to obtain one-dimensional chains. The two one-dimensional chains are further connected by four nitrogen-containing organic ligands to obtain a metal-organic framework with a three-dimensional network structure. The metal-organic framework has a "small window-large cavity" structure that matches the butadiene molecule, realizing size exclusion for 1-butene, while being compatible with the high adsorption capacity of butadiene under low pressure. The pore size of the metal-organic framework is 0.3~2.0 nm. For example, the metal-organic framework channel constructed in this invention has a window structure that excludes 1-butene molecules, making it difficult for 1-butene molecules to pass through and thus repelling them. The window size is extremely well matched with the butadiene molecules, allowing them to enter smoothly. At the same time, the cavity structure formed by the constructed metal-organic framework is extremely well matched with the size and shape of the butadiene molecules. Therefore, it is possible to achieve efficient sieving and separation of butadiene molecules and 1-butene molecules.

[0015] (2) In this invention, 1,4,5,8-naphthoic acid, which has strong symmetry, is used as an organic ligand to coordinate with metal ion nodes in the architecture, exhibiting a distorted tetrahedral coordination geometry. Furthermore, it self-assembles and assembles to form a PTS topological ultraporous metal-organic framework adsorbent with adaptable pores for guest molecules. This type of metal-organic framework material has suitable pore sizes, enabling it to exhibit efficient sieving between butadiene and 1-butene through size effects, achieving the goal of separating and producing high-purity 1-butene from a mixture of butadiene and 1-butene in one step.

[0016] (3) The metal-organic framework of the present invention has a diverse structure and a highly tunable pore system, which can be used as an adsorbent for the industrially challenging removal of butadiene from 1-butene.

[0017] (4) This invention is the first to remove butadiene from 1-butene by metal-organic framework adsorption separation technology, and obtain high-purity 1-butene to meet downstream demand. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the crystal structure of the metal-organic framework in Embodiment 1 of the present invention, wherein (a) represents the tetrahedral coordination mode of the metal Zn ion; (b) represents the pores formed as observed from the front view; (c) represents the one-dimensional chain structure formed by the metal ion and the tetradentate nitrogen-containing ligand; (d) represents the one-dimensional chain structure formed by the metal ion and the tetradentate carboxylic acid ligand; (e) shows a one-dimensional through-hole; (f) represents the formation of a continuous "small window-large cavity" pore structure; and (g) represents the use of metal ions, organic nitrogen-containing ligands, and carboxylic acid ligands.

[0019] Figure 2 This is an SEM image of the metal-organic framework in Embodiment 1 of the present invention.

[0020] Figure 3 The results are X-ray diffraction results of the metal-organic framework in Example 1 of this invention; where Activated represents the activated sample; As-synthesized represents the synthesized sample; Simulated represents crystal simulation.

[0021] Figure 4 The results of the thermogravimetric curve test of the metal-organic framework in Example 1 of the present invention are shown.

[0022] Figure 5 This is the 195K CO2 adsorption isotherm of the metal-organic framework in Example 1 of the present invention; where Absolute Pressure represents relative pressure; Quantity Adsorbed represents the amount of adsorption; and Bet surface area represents the specific surface area. Figure 6 The results are X-ray diffraction experiments of the metal-organic framework in Example 1 of this invention after immersion in different organic solvents and exposure to air.

[0023] Figure 7 This is the adsorption isotherm of butadiene and 1-butene by the metal-organic framework in Example 1 of the present invention at 298 K, where Gas uptake represents the amount of gas adsorbed.

[0024] Figure 8 This is a cycle diagram of butadiene adsorption on a metal-organic framework at 298K in Example 1 of the present invention.

[0025] Figure 9 This is the kinetic adsorption curve of the metal-organic framework in Example 1 of the present invention, showing the change of adsorption amount of butadiene and 1-butene with time and pressure at 298K.

[0026] Figure 10 The diagram shows the dynamic breakthrough curve of a 1-butene / butadiene mixed gas component passed through dry nitrogen at a fixed flow rate of 0.5 mL / min under 298 K in the metal-organic framework separation method of Example 1 of the present invention; where C / C0 represents the ratio of the concentration changing with time to the equilibrium concentration.

[0027] Figure 11 The dynamic breakthrough curves of dry nitrogen gas passing through a 1-butene / butadiene mixed gas component at different flow rates under 298K conditions are shown in Embodiment 1 of the present invention for the separation method of 1-butene by a metal-organic framework.

[0028] Figure 12The figure shows the dynamic breakthrough cycle curves of five passes of dry nitrogen gas through a 1-butene / butadiene mixed gas component at a fixed flow rate of 0.5 mL / min under 298 K conditions in the metal-organic framework separation method of 1-butene in Example 1 of the present invention.

[0029] Figure 13 This is a simplified topological diagram of the metal-organic framework material of the present invention. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents, etc. used are all commercially available products in the art or prepared by conventional methods in the art.

[0031] The following technical terms are explained: XRD stands for X-ray diffraction; BET stands for specific surface area; DMF stands for N,N-dimethylformamide.

[0032] Example 1 A metal-organic framework (MOF) for removing butadiene from 1-butene is described, wherein zinc ions from zinc nitrate are coordinated with oxygen atoms of two 1,4,5,8-naphthoic acid atoms and nitrogen atoms of two 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes, forming distorted ZnN₂O₂ tetrahedra. The zinc ions in the two adjacent tetrahedra are bridged by single-bonded oxygen atoms on the 1,4,5,8-naphthoic acid atoms, constructing a one-dimensional chain structure. Adjacent one-dimensional chain structures are coordinated and connected by four 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes, resulting in a MOF with a three-dimensional network structure. Figure 1 The diagram shown is a schematic representation of the crystal structure of the metal-organic framework of this invention.

[0033] The metal-organic framework has a pore size of 0.71 nm and a pore volume of 0.28 cm³. 3 / g, porosity 19.4%, specific surface area 429.6m² 2 / g.

[0034] The above-mentioned method for preparing metal-organic frameworks includes the following steps: 0.2 mmol of zinc nitrate hexahydrate, 0.2 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.2 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 3 mL of N,N-dimethylformamide and 3 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h and sealed in a polytetrafluoroethylene-lined reactor. The reactor was then placed in an oven at 140 °C for 3 days. After washing three times by vacuum filtration with DMF and methanol solutions, the mixture was dried at 60 °C and subjected to solvent exchange with anhydrous methanol for 3 days. Finally, the mixture was activated at 120 °C under vacuum for 10 h to obtain a metal-organic framework.

[0035] Example 2 A metal-organic framework for removing butadiene from 1-butene is disclosed, wherein copper ions from copper perchlorate are coordinated with oxygen atoms of two 1,4,5,8-naphthoic acid atoms and nitrogen atoms of two 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to form distorted ZnN2O2 tetrahedral coordinations; zinc ions in the two juxtaposed tetrahedral coordinations are bridged by single-bonded oxygen atoms of 1,4,5,8-naphthoic acid atoms to construct a one-dimensional chain structure; two adjacent one-dimensional chain structures are coordinated and connected by four 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to obtain a metal-organic framework with a three-dimensional network structure.

[0036] The metal-organic framework has a pore size of 0.67 nm and a pore volume of 0.27 cm³. 3 / g, porosity 30.2%, specific surface area 419.6m² 2 / g.

[0037] The above-mentioned method for preparing metal-organic frameworks includes the following steps: 0.2 mmol of copper perchlorate, 0.2 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.2 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 3 mL of N,N-dimethylformamide and 3 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h, sealed in a polytetrafluoroethylene-lined reactor, and then placed in an oven at 140 °C for 3 days. After filtration and washing, the mixture was dried at 60 °C, and the solvent was exchanged in methanol solution for 3 days. Finally, the mixture was activated at 120 °C under vacuum for 10 h to obtain a metal-organic framework.

[0038] Example 3 A metal-organic framework for removing butadiene from 1-butene is disclosed, wherein cobalt ions from cobalt sulfate are coordinated with oxygen atoms of two 1,4,5,8-naphthoic acid atoms and nitrogen atoms of two 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to form distorted ZnN2O2 tetrahedral coordinations; zinc ions in the two juxtaposed tetrahedral coordinations are bridged by single-bonded oxygen atoms of 1,4,5,8-naphthoic acid atoms to construct a one-dimensional chain structure; two adjacent one-dimensional chain structures are coordinated and connected by four 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to obtain a metal-organic framework with a three-dimensional network structure.

[0039] The metal-organic framework has a pore size of 0.61 nm and a pore volume of 0.25 cm³. 3 / g, porosity 25.6%, specific surface area 412.6m² 2 / g.

[0040] The above-mentioned method for preparing metal-organic frameworks includes the following steps: 0.2 mmol of cobalt sulfate, 0.2 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.2 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 3 mL of N,N-dimethylformamide and 3 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h, sealed in a polytetrafluoroethylene-lined reactor, and then placed in an oven at 140 °C for 3 days. After filtration and washing, the mixture was dried at 60 °C, and the solvent was exchanged in methanol solution for 3 days. Finally, the mixture was activated at 120 °C under vacuum for 10 h to obtain a metal-organic framework.

[0041] Example 4 A metal-organic framework for removing butadiene from 1-butene is disclosed, wherein nickel ions from nickel nitrate are coordinated with oxygen atoms of two 1,4,5,8-naphthoic acid atoms and nitrogen atoms of two 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to form distorted ZnN2O2 tetrahedral coordinations; zinc ions in the two juxtaposed tetrahedral coordinations are bridged by single-bonded oxygen atoms of 1,4,5,8-naphthoic acid atoms to construct a one-dimensional chain structure; two adjacent one-dimensional chain structures are coordinated and connected by four 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to obtain a metal-organic framework with a three-dimensional network structure.

[0042] The metal-organic framework has a pore size of 0.56 nm and a pore volume of 0.23 cm³. 3 / g, porosity 33.6%, specific surface area 415.4m² 2 / g.

[0043] The above-mentioned method for preparing metal-organic frameworks includes the following steps: 0.2 mmol of nickel nitrate, 0.2 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.2 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 3 mL of N,N-dimethylformamide and 3 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h, sealed in a polytetrafluoroethylene-lined reactor, and then placed in an oven at 140 °C for 3 days. After filtration and washing, the mixture was dried at 60 °C, and the solvent was exchanged in methanol solution for 3 days. Finally, the mixture was activated at 120 °C under vacuum for 10 h to obtain a metal-organic framework.

[0044] Example 5 A metal-organic framework for removing butadiene from 1-butene is disclosed, wherein cadmium ions from cadmium nitrate are coordinated with oxygen atoms of two 1,4,5,8-naphthoic acid and nitrogen atoms of two 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to form distorted ZnN2O2 tetrahedral coordinations; zinc ions in the two juxtaposed tetrahedral coordinations are bridged by single-bonded oxygen atoms of 1,4,5,8-naphthoic acid to construct a one-dimensional chain structure; two adjacent one-dimensional chain structures are coordinated and connected by four 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to obtain a metal-organic framework with a three-dimensional network structure.

[0045] The metal-organic framework has a pore size of 0.59 nm and a pore volume of 0.24 cm³. 3 / g, porosity 28.5%, specific surface area 431.6m² 2 / g.

[0046] The above-mentioned method for preparing metal-organic frameworks includes the following steps: 0.2 mmol of cadmium nitrate, 0.2 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.2 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 3 mL of N,N-dimethylformamide and 3 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h, sealed in a polytetrafluoroethylene-lined reactor, and then placed in an oven at 140 °C for 3 days. After filtration and washing, the mixture was dried at 60 °C, and the solvent was exchanged in methanol solution for 3 days. Finally, the mixture was activated at 120 °C under vacuum for 10 h to obtain a metal-organic framework.

[0047] Example 6 A metal-organic framework for removing butadiene from 1-butene is disclosed, wherein manganese ions from manganese acetate are coordinated with oxygen atoms of two 1,4,5,8-naphthoic acid atoms and nitrogen atoms of two 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to form distorted ZnN2O2 tetrahedral coordinations; zinc ions in the two juxtaposed tetrahedral coordinations are bridged by single-bonded oxygen atoms of 1,4,5,8-naphthoic acid atoms to construct a one-dimensional chain structure; two adjacent one-dimensional chain structures are coordinated and connected by four 1,2,4,5-tetra(1H-imidazol-1-yl)benzenes to obtain a metal-organic framework with a three-dimensional network structure.

[0048] The metal-organic framework has a pore size of 0.68 nm and a pore volume of 0.22 cm³. 3 / g, porosity 26.8%, specific surface area 413.6m² 2 / g.

[0049] The above-mentioned method for preparing metal-organic frameworks includes the following steps: 0.2 mmol of manganese acetate, 0.2 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.2 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 3 mL of N,N-dimethylformamide and 3 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h, sealed in a polytetrafluoroethylene-lined reactor, and then placed in an oven at 140 °C for 3 days. After filtration and washing, the mixture was dried at 60 °C, and the solvent was exchanged in methanol solution for 3 days. Finally, the mixture was activated at 120 °C under vacuum for 10 h to obtain a metal-organic framework.

[0050] Example 7 A method for preparing a metal-organic framework includes the following steps: 1 mmol of zinc nitrate hexahydrate, 0.1 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 0.1 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 15 mL of N,N-dimethylformamide and 15 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h and sealed in a polytetrafluoroethylene-lined reactor. The reactor was then placed in an oven at 60 °C and reacted for 90 h. After washing three times by vacuum filtration with DMF and methanol solutions, the mixture was dried at 60 °C and subjected to solvent exchange with anhydrous methanol for 3 days. Finally, the mixture was activated at 80 °C under vacuum for 16 h to obtain a metal-organic framework.

[0051] Example 8 A method for preparing a metal-organic framework includes the following steps: 1 mmol of zinc nitrate hexahydrate, 10 mmol of 1,2,4,5-tetra(1H-imidazol-1-yl)benzene, and 10 mmol of 1,4,5,8-naphthalenetetracarboxylic acid in a molar ratio of 1:1:1 were dissolved in a mixed solution of 100 mL of N,N-dimethylformamide and 100 mL of H2O in a volume ratio of 1:1. The mixture was sonicated for 0.45 h and sealed in a polytetrafluoroethylene-lined reactor. The reactor was then placed in an oven at 240 °C and reacted for 48 h. After three separate filtrations and washings with DMF and methanol solutions, the mixture was dried at 60 °C and subjected to solvent exchange with anhydrous methanol for 3 days. Finally, the mixture was activated under vacuum at 150 °C for 8 h to obtain a metal-organic framework.

[0052] Examples 1 through 8 all yielded metal-organic frameworks with comparable results. The following experiments were conducted using the metal-organic framework prepared in Example 1 as an example: Experiment 1: Observation of metal-organic frameworks using scanning electron microscopy (SEM) The metal-organic framework in Example 1 of this invention was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 2 As shown in the figure, its shape is blocky.

[0053] Experiment 2 X-ray Diffraction Experiment The XRD diffraction peaks and simulated XRD peak values ​​of the metal-organic framework in Example 1 were detected using an X-ray diffractometer. Figure 3 The results show that its XRD diffraction peaks are in complete agreement with the simulated XRD peaks, confirming its high phase purity.

[0054] Experiment 3 Thermogravimetric curve test experiment Thermogravimetric analysis (TGA) was used to detect the thermogravimetric curves of the metal-organic framework in Example 1. Figure 4 Thermogravimetric analysis confirmed its excellent thermal stability, with its structure collapsing at approximately 375°C. The amount of guest molecules removed during activation was 14%.

[0055] Experiment 4 Specific Surface Area Test The 195 K CO2 adsorption isotherm of the metal-organic framework in Example 1 was determined using an ASAP 2460 physical adsorption analyzer. Figure 5 As shown, by introducing CO2 at 195K, its specific surface area (BET) was tested and found to be 429 m². 2 / g, with a pore size distribution of 7.1Å.

[0056] Experiment 5 X-ray diffraction experiments of metal-organic frameworks treated under different conditions X-ray diffraction was used to examine the X-ray diffraction patterns of the metal-organic framework in Example 1 after immersion in different organic solvents and exposure to air. For example... Figure 6As shown, the metal-organic framework of the present invention has excellent crystallinity and phase purity; after being exposed to air for 7 days, the position and intensity of its X-ray diffraction peaks did not change significantly, further confirming that it has good chemical and water stability.

[0057] Experiment 6: Single-component gas adsorption isotherm test experiment The adsorption isotherms of butadiene and 1-butene for the metal-organic framework in Example 1 at 298 K were detected using a 3FLXE physical gas adsorption analyzer. Figure 7 As shown, under 298K conditions, the material synthesized in Example 1 adsorbed 1.44 mmol / g and 0.08 mmol / g of butadiene and 1-butene, respectively.

[0058] Experiment 7 Adsorption Cycle Experiment The adsorption cycle performance of the metal-organic framework for butadiene at 298 K in Example 1 was tested using a 3FLXE physical gas adsorption analyzer. Figure 8 As shown, after five adsorption cycles, its performance remained essentially unchanged, confirming its excellent cycle stability.

[0059] Experiment 8: Dynamic Curve Testing The kinetic adsorption curves of butadiene and 1-butene adsorption amounts in the metal-organic framework of Example 1 at 298 K were analyzed using a smart gravimetric analyzer to determine their effects on time and pressure. Figure 9 As shown, when the equilibrium pressure is 1000 mbar, butadiene reaches adsorption equilibrium in a very short time, acetylene reaches equilibrium in 4 minutes, while 1-butene hardly adsorbs anything.

[0060] Experiment 9 Penetration Experiment The metal-organic framework mixture of 1-butene and butadiene from Example 1 was separated using gas chromatography. Dry nitrogen gas was passed through the gas mixture containing 1-butene / butadiene at a fixed flow rate of 0.5 mL / min at 298 K, and its dynamic breakthrough curve was determined. Figure 10 As shown, at 298 K and 1 bar, a 1-butene / butadiene mixture with a volume ratio of 95.24 / 4.76 flowed through a fixed-bed adsorption column packed with metal-organic framework material at a fixed flow rate of 0.5 mL / min. The 1-butene component preferentially penetrated the bed, and ultra-high purity 1-butene gas (>99.999%) and high purity 1-butene gas (>99.988%) were obtained at the tail end of the adsorption column.

[0061] Experiment 10: Penetration Experiment with Different Flow Velocities The metal-organic framework mixture of 1-butene and butadiene from Example 1 was separated using gas chromatography. Dry nitrogen gas was passed through the 1-butene / butadiene mixture at three different constant flow rates of 0.5 mL / min, 1.0 mL / min, and 1.5 mL / min at 298 K, and its dynamic breakthrough curve was determined. Figure 11 As shown, 1-butene and butadiene have a distinct separation range, exhibiting excellent separation performance at three flow rates of 0.5 mL / min, 1.0 mL / min, and 1.5 mL / min.

[0062] Experiment 11: Penetration Cycle Experiment The metal-organic framework of Example 1, containing a mixture of 1-butene and butadiene, was subjected to five breakthrough cycles using gas chromatography. Dry nitrogen gas was passed through the gas mixture containing 1-butene / butadiene at a constant flow rate of 0.5 mL / min at 298 K, and its dynamic breakthrough curve was determined. Figure 12 As shown, five dynamic breakthrough cycle experiments confirmed its excellent cycle stability.

[0063] Simplified topological diagrams of the metal-organic framework materials in Examples 1-6 are shown below. Figure 13 As shown, yellow represents Zn-N node connections, and blue represents CN node connections.

[0064] Application Example 1 The application of the metal-organic framework obtained in Example 1 in the removal of butadiene from 1-butene is described in the following process: 1-Butene and butadiene gases were mixed and introduced into an adsorption bed packed with metal-organic framework material at a set flow rate using nitrogen as the carrier gas. After butadiene breakthrough during a dynamic breakthrough experiment, equilibrium was reached, yielding 1-butene fractions with purities exceeding 99.999% and 99.988% in one step. The volume ratio of 1-butene to butadiene was 1:10. The adsorption temperature was -50°C, and the adsorption pressure was atmospheric pressure.

[0065] Application Example 2 The application of the metal-organic framework obtained in Example 1 in the removal of butadiene from 1-butene is described in the following process: 1-Butene and butadiene gases were mixed and introduced into an adsorption bed packed with metal-organic framework material at a set flow rate using nitrogen as the carrier gas. After butadiene breakthrough during a dynamic breakthrough experiment, equilibrium was reached, yielding 1-butene fractions with purities exceeding 99.999% and 99.988% in one step. The volume ratio of 1-butene to butadiene was 100:1. The adsorption temperature was 100℃, and the adsorption pressure was 10 bar.

[0066] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A metal-organic framework for removing butadiene from 1-butene, characterized in that, The metal-organic framework is formed by coordinating metal ions from a metal salt with two carboxylic acid organic ligands and two nitrogen-containing organic ligands to form tetrahedral coordination. The carboxylic acid organic ligands coordinate with the metal ions through oxygen atoms, and the nitrogen-containing organic ligands coordinate with the metal ions through nitrogen atoms. The metal ions are bridged with single-bonded oxygen atoms on the carboxylic acid organic ligands to construct a one-dimensional chain structure. Four adjacent one-dimensional chain structures are then coordinated and connected through nitrogen-containing organic ligands to obtain a metal-organic framework with a three-dimensional network structure. The pore size of the metal-organic framework is 0.3~2.0 nm.

2. The metal-organic framework according to claim 1, characterized in that, The pore size of the metal-organic framework is 0.1~0.8 cm³. 3 / g, porosity 20~35%, specific surface area 200~800m² 2 / g.

3. The metal-organic framework according to claim 1, characterized in that, The anion in the metal salt is any one of nitrate, halide, perchlorate, carbonate, sulfate, fluoroborate, and acetate; the metal ion in the metal salt includes dimethyl metal cations. The carboxylic acid organic ligand is a tetradentate carboxylic acid organic ligand; The nitrogen-containing organic ligand is a tetradentate imidazole ligand.

4. The metal-organic framework according to claim 3, characterized in that, The tetradentate carboxylic acid organic ligand is 1,4,5,8-naphthalenetetracarboxylic acid or 1,4,5,8-naphthalenetetracarboxylic anhydride. The tetradentate imidazole ligand is 1,2,4,5-tetra(1H-imidazol-1-yl)benzene.

5. A method for preparing the metal-organic framework according to claim 1, characterized in that, Includes the following steps: Metal salts, carboxylic acid organic ligands, and nitrogen-containing organic ligands are mixed, added to a mixture, heated, filtered, and activated to obtain a metal-organic framework; the ratio of the metal salt, carboxylic acid organic ligands, nitrogen-containing organic ligands, and the mixture is 1 mmol: 0.1 mmol to 10 mmol: 0.1 mmol to 10 mmol: 30 mL to 200 mL. The mixture consists of an organic solvent and water.

6. The preparation method according to claim 5, characterized in that, The filtered material is dried and solvent-exchanged before being activated.

7. The preparation method according to claim 5, characterized in that, The heating temperature is 60~240℃ for 48~90h; the activation temperature is 80~150℃ for 8~16h.

8. The preparation method according to claim 5, characterized in that, The organic solvent is any one of methanol, N,N-dimethylformamide, acetonitrile, and isopropanol.

9. The preparation method according to claim 5, characterized in that, The volume ratio of the organic solvent to water is 1~99:99~1.

10. An application of the metal-organic framework of claim 1 in the removal of butadiene from 1-butene.

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