Acetate-bridged bent-core tri-core-based mg-mof and preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN UNVERSITY OF ARTS & SCI
- Filing Date
- 2026-03-11
- Publication Date
- 2026-05-29
Smart Images
Figure CN122103602A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas adsorption and separation technology, specifically to an acetic acid-linked bendable trinuclear cluster Mg-MOF, its preparation method, and its application. Background Technology
[0002] Separating acetylene (C2H2) and carbon dioxide (CO2) is a key challenge in natural gas purification, acetylene production (such as the calcium carbide process or hydrocarbon cracking), and industrial waste gas treatment. The core difficulty lies in the high similarity of their physical properties (similar molecular sizes and boiling / sublimation points), leading to low efficiency or extremely high energy consumption in traditional separation technologies based on size sieving or volatility differences (such as conventional distillation, physical adsorption, and ordinary membrane separation), making it difficult to achieve selective separation economically and efficiently.
[0003] Current mainstream technologies primarily utilize the differences in chemical properties between the two. For example, chemical absorption methods (such as amine solutions) can selectively remove CO2, but they face risks of solvent degradation and acetylene loss. Cryogenic separation, while theoretically feasible, lacks economic viability due to its ultra-low operating temperature and enormous energy consumption. Metal-Organic Frameworks (MOFs), with their high specific surface area, tunable pore structure, and high designability, have become a research hotspot in gas separation. However, most existing MOFs suffer from the difficulty of balancing gas adsorption capacity and separation ratio. Therefore, developing separation materials and processes that combine high capacity, high selectivity, low energy consumption, and long-term stability remains a bottleneck that urgently needs to be overcome in this field. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides an acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF, its preparation method, and its applications. The acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF of this invention belongs to the monoclinic crystal system, and its chemical formula is: C 44 H 29 Mg3O 16 P2, space group C2 / c, cell parameters: a=24.586(3)Å, b=15.2058(19)Å, c=24.410(4)Å, α=90°, β=117.603(4)°, γ=90°, V=8087(2)Å 3Z=4, F(000)=1948.0. It is prepared by solvothermal reaction using soluble magnesium salt as magnesium source and H3PTO as organic ligand. The acetic acid-linked bendable trinuclear cluster Mg-MOF of the present invention, its preparation method and application have excellent stability and high selectivity. It not only solves the problems of short lifespan and reduced separation efficiency caused by structural instability of existing metal-organic framework materials in practical applications, but also achieves a breakthrough separation selectivity for acetylene and carbon dioxide mixtures through the synergistic CH···π and CH···O dual interaction mechanism (theoretically calculated selective separation ratio of equimolar amounts of C2H2 and CO2 mixture is 2.65), providing an innovative material with both high stability and high separation efficiency for industrial acetylene purification.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to provide an acetic acid-linked, bend-shaped, trinuclear cluster-based Mg-MOF, belonging to the monoclinic crystal system, with the chemical formula: C 44 H 29 Mg3O 16 P2, space group C2 / c, cell parameters: a=24.586(3)Å, b=15.2058(19)Å, c=24.410(4)Å, α=90°, β=117.603(4)°, γ=90°, V=8087(2)Å 3 Z=4, F(000)=1948.0.
[0006] Preferably, the BET specific surface area of the acetic acid-linked bendable trinuclear cluster-based Mg-MOF is 992.1 cm². 2 / g, actual pore volume is 0.52cm³ 3 / g.
[0007] A second objective of this invention is to provide a method for preparing the above-mentioned acetic acid-linked bendable trinuclear cluster-based Mg-MOF, comprising the following steps: S1. N,N-Dimethylformamide, acetonitrile, and acetic acid are mixed to obtain a mixed solvent. N,N-Dimethylformamide is the main solvent, which can provide solubility and a stable reaction environment with a high boiling point. Acetonitrile is used as an auxiliary solvent to reduce the competitive coordination effect of DMF and adjust the solvent properties. Acetic acid can affect the formation of MOF crystal structure, mainly by providing a specific coordination environment to control the morphology or structure of the crystal.
[0008] S2. Phosphorus trioxide and soluble magnesium salt are dissolved together in a mixed solvent and subjected to a solvothermal reaction. During the solvothermal reaction, phosphorus trioxide becomes a strong Lewis base after the removal of a proton, while magnesium ions become Lewis acids. Under solvothermal conditions, the two can form coordinate bonds and form a 3D framework material through the difference in ligand geometry, resulting in acetic acid-linked bent-angle trinuclear cluster Mg-MOF.
[0009] Preferably, the molar ratio of tris(p-carboxyphenyl)phosphine oxide to soluble magnesium salt is 0.2:1.
[0010] Preferably, the volume ratio of N,N-dimethylformamide, acetonitrile, and acetic acid is 2:2:0.5.
[0011] Preferably, the solvothermal reaction conditions are: reacting at 120°C for 3 to 4 days.
[0012] A third objective of this invention is to provide the application of the aforementioned acetic acid-linked bendable trinuclear cluster Mg-MOF in the preparation of acetylene adsorption and separation agents.
[0013] Preferably, acetic acid-linked bendable trinuclear cluster Mg-MOF is used for the adsorption and separation of a mixture of acetylene and carbon dioxide.
[0014] Preferably, the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF is activated before adsorbing and separating the mixed gas of acetylene and carbon dioxide. The activation process is as follows: the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF is immersed in acetonitrile, and the acetonitrile is replaced every 12 hours. After 4 days of continuous replacement, it is placed in a vacuum at 60℃~80℃ for 10h~12h to obtain activated acetic acid-linked bend-shaped trinuclear cluster Mg-MOF.
[0015] Preferably, activated acetic acid-linked bend-shaped trinuclear cluster Mg-MOF selectively adsorbs acetylene from a mixture of acetylene and carbon dioxide.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a method for preparing acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF. This material belongs to the monoclinic crystal system and has the chemical formula: C 44 H 29 Mg3O 16 P2; Space group C2 / c, cell parameters: a=24.586(3)Å, b=15.2058(19)Å, c=24.410(4)Å, α=90°, β=117.603(4)°, γ=90°, V=8087(2)Å 3Z=4, F(000)=1948.0. The acetic acid-linked bend-shaped trinuclear cluster Mg-MOF of the present invention exhibits excellent stability and high selectivity. This is because the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF has a pore structure and functional groups with highly efficient C2H2 adsorption bonding sites, achieving efficient separation of acetylene and carbon dioxide, and providing a better solution in this field.
[0017] This invention introduces a P=O functional group and abundant benzene rings onto the tris(p-carboxyphenyl)phosphine oxide organic ligand, enabling the π electrons on the acetylene molecule and the benzene ring of the ligand to form a CH···π interaction, while forming a CH···O interaction with the oxygen atom in the P=O functional group. The two mutually promote and synergistically enhance the selectivity of C2H2 molecules, achieving efficient separation of C2H2 and CO2 mixed gases. This provides a new approach for the separation of C2H2 and CO2 mixed gases and has great application potential in the industrial application of acetylene purification.
[0018] 2. This invention provides a method for preparing an acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF. N,N-dimethylformamide, acetonitrile, and acetic acid are mixed to obtain a mixed solvent. Phosphine trioxide and a soluble magnesium salt are dissolved together in the mixed solvent, and a solvothermal reaction is carried out to obtain the acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF. The inorganic secondary building unit of this acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF is a bend-shaped trinuclear cluster: three Mg... 2+ All are six-coordinate octahedral configurations, in which each Mg 2+ The surrounding structure consists of four oxygen atoms from the tri(p-carboxyphenyl)phosphine oxide ligand, terminally coordinated water molecules, and two carboxyl oxygen atoms from acetic acid acting as μ2-O bonds connecting three Mg atoms. 2+ And forming a curved trinuclear cluster, such as Figure 1 The left figure shows the framework constructed in this way. The pores are non-uniform in polarity and have an electrostatic potential gradient, which gives it high density and specific orientation of action sites. This provides a good pore size and pore chemical environment for the adsorption and separation of gas molecules, and offers a new approach for the separation of mixed gases such as C2H2 and CO2. Attached Figure Description
[0019] Figure 1 This is a crystal structure diagram of the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF of Example 1.
[0020] Figure 2 The image shows the PXRD pattern of the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF in Example 1.
[0021] Figure 3The adsorption isotherms of acetylene and carbon dioxide by the acetic acid-linked bendable trinuclear cluster Mg-MOF in Example 1 at different temperatures are shown.
[0022] Figure 4 The N2 adsorption-desorption isotherm and pore size distribution of the acetic acid-linked bendable trinuclear cluster Mg-MOF at 77 K are shown in Example 1. Figure 4 The illustration in the figure is a pore size distribution diagram.
[0023] Figure 5 The graph shows the IAST separation coefficients of acetylene / carbon dioxide at different molar ratios for the acetic acid-linked bent-angle trinuclear cluster Mg-MOF in Example 1 at 298 K.
[0024] Figure 6 The image shows the dynamic breakthrough curve of the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF in Example 1.
[0025] Figure 7 This is an adsorption pyrogram of acetylene and carbon dioxide in an acetic acid-linked bendable trinuclear cluster Mg-MOF as described in Example 1. Detailed Implementation
[0026] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.
[0027] It should be noted that the technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased commercially or prepared by existing methods. Among them, tris(p-carboxyphenyl)phosphine oxide is abbreviated as H3PTO; N,N-dimethylformamide is DMF; acetonitrile is CH3CN; and acetic acid is HAc.
[0028] To address the problem that most existing metal-organic framework materials suffer from poor stability and are difficult to use in practical applications, this invention provides an acetic acid-linked, bend-angled, trinuclear cluster-based Mg-MOF. This material belongs to the monoclinic crystal system and has the chemical formula: C 44 H 29 Mg3O 16P2; space group C2 / c, cell parameters: a=24.586(3)Å, b=15.2058(19)Å, c=24.410(4)Å, α=90°, β=117.603(4)°, γ=90°, V=8087(2)Å 3 Z=4, F(000)=1948.0. The acetic acid-linked bend-angled trinuclear cluster-based Mg-MOF of the present invention exhibits excellent stability. Its unique framework structure can effectively resist stress changes during the adsorption-desorption process, significantly improving the service life of the material in practical applications. More importantly, this acetic acid-linked bend-angled trinuclear cluster-based Mg-MOF achieves strong specific adsorption of acetylene gas through a synergistic CH···π (provided by ligand-rich benzene rings) and CH···O (provided by ligand P=O functional groups) dual interaction mechanism, thus exhibiting breakthrough high selectivity in the separation of acetylene and carbon dioxide mixtures. This overcomes the technical defects of existing metal-organic framework materials, such as poor structural stability leading to short lifespan, decreased separation efficiency, and insufficient selectivity in the separation of acetylene and carbon dioxide.
[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the following detailed description will be provided in conjunction with specific embodiments.
[0030] Example 1 A method for preparing an acetic acid-linked bendable trinuclear cluster-based Mg-MOF includes the following steps: S1. Mix 2 mL of DMF, 2 mL of CH3CN and 0.5 mL of HAc to obtain a mixed solvent.
[0031] S2. According to the molar ratio of H3PTO to magnesium nitrate hexahydrate of 0.2:1, 26 mg of magnesium nitrate hexahydrate and 9 mg of H3PTO were weighed and dissolved in a mixed solvent. After complete dissolution, the solution was transferred to a stainless steel reactor lined with polytetrafluoroethylene (PTFE). The reactor was then placed in an oven at 120°C for 4 days. After the reaction was completed, the solution was cooled to room temperature. After filtration and washing, acetic acid-linked bend-shaped trinuclear cluster Mg-MOF was obtained, abbreviated as Mg-MOF. Its crystal structure is as follows: Figure 1 As shown in Table 1, the crystallographic parameters are presented in the table.
[0032] Example 2 A method for preparing an acetic acid-linked bendable trinuclear cluster-based Mg-MOF is the same as that in Example 1, except that the volume ratio of DMF, CH3CN, and HAc is changed from 2:2:0.5 to 2:2:0.6, and includes the following steps: S1. Mix 2 mL of DMF, 2 mL of CH3CN and 0.6 mL of HAc to obtain a mixed solvent.
[0033] S2. Dissolve 26 mg of magnesium nitrate hexahydrate and 9 mg of H3PTO in a mixed solvent. After complete dissolution, transfer the solution to a stainless steel reactor lined with polytetrafluoroethylene. Then, place the reactor in an oven at 120°C for 4 days. After the reaction is completed, cool the solution to room temperature. After filtration and washing, obtain acetic acid-linked bend-shaped trinuclear cluster Mg-MOF, abbreviated as Mg-MOF.
[0034] Example 3 A method for preparing an acetic acid-linked bendable trinuclear cluster-based Mg-MOF is identical to that in Example 1, except that the molar ratio of H3PTO to magnesium nitrate hexahydrate is changed from 0.2:1 to 0.2:1.3, and includes the following steps: S1. Mix 2 mL of DMF, 2 mL of CH3CN and 0.5 mL of HAc to obtain a mixed solvent.
[0035] S2. According to the molar ratio of H3PTO to magnesium nitrate hexahydrate of 0.2:1.3, 33.3 mg of magnesium nitrate hexahydrate and 9 mg of H3PTO were dissolved in a mixed solvent. After complete dissolution, the solution was transferred to a stainless steel reactor lined with polytetrafluoroethylene and then placed in an oven at 120°C for 4 days. After the reaction was completed, the solution was cooled to room temperature. After filtration and washing, acetic acid-linked bend-shaped trinuclear cluster Mg-MOF was obtained, abbreviated as Mg-MOF.
[0036] Example 4 A method for preparing an acetic acid-linked bendable trinuclear cluster-based Mg-MOF is the same as that in Example 1, except that the solvothermal conditions are changed from 120°C to 130°C and the time is changed from 4 days to 3 days. The method includes the following steps: S1. Mix 2 mL of DMF, 2 mL of CH3CN and 0.5 mL of HAc to obtain a mixed solvent.
[0037] S2. Dissolve 26 mg of magnesium nitrate hexahydrate and 9 mg of H3PTO in a mixed solvent. After complete dissolution, transfer the solution to a stainless steel reactor lined with polytetrafluoroethylene. Then, place the reactor in an oven at 130°C for 3 days. After the reaction is completed, cool the solution to room temperature. After filtration and washing, obtain acetic acid-linked bend-shaped trinuclear cluster Mg-MOF, abbreviated as Mg-MOF.
[0038] Table 1 shows the crystallographic parameters of the acetic acid-linked bendable trinuclear cluster-based Mg-MOF prepared in Example 1. application: The acetic acid-linked bendable trinuclear cluster Mg-MOF of Example 1 of this invention was soaked in acetonitrile solvent for 4 days, with the acetonitrile being replaced every 12 hours; then, vacuum was applied at 60°C for 10 hours to remove the solvent from the crystal channels, yielding activated acetic acid-linked bendable trinuclear cluster Mg-MOF; the adsorption and separation performance of the activated acetic acid-linked bendable trinuclear cluster Mg-MOF was tested. a. PXRD characterization The acetic acid-linked bendable trinuclear cluster-based Mg-MOF powder prepared in Example 1 was characterized by PXRD, and the results are as follows: Figure 2 As shown. According to Figure 2 The results show that the powder XRD pattern of the acetic acid-linked bend-angled trinuclear cluster-based Mg-MOF prepared in this invention matches well with the diffraction peak positions of the PXRD pattern obtained from single-crystal structure simulation, indicating that the acetic acid-linked bend-angled trinuclear cluster-based Mg-MOF prepared in this invention are all pure phases.
[0039] b. Single-component gas adsorption isotherm test The acetic acid-linked bendable trinuclear cluster Mg-MOF prepared in Example 1 possesses permanent channels and a stable structure. Isothermal adsorption tests of acetylene and carbon dioxide were performed on the activated acetic acid-linked bendable trinuclear cluster Mg-MOF from Example 1 at different temperatures. The results are as follows: Figure 3 As shown. According to Figure 3 It can be seen that the acetic acid-linked bendable trinuclear cluster Mg-MOF of the present invention exhibits an acetylene adsorption capacity of 130.5 cm⁻¹ under conditions of 298 K and 1 bar. 3 / g, the carbon dioxide adsorption capacity is 53.5cm. 3 / g, the acetic acid-linked bent-angled trinuclear cluster Mg-MOF of the present invention has a higher adsorption capacity for acetylene than for carbon dioxide, proving that the activated acetic acid-linked bent-angled trinuclear cluster Mg-MOF preferentially adsorbs acetylene.
[0040] c. Pore characterization Approximately 100 mg of the acetic acid-linked bendable trinuclear cluster-based Mg-MOF prepared in Example 1 was prepared and degassed under vacuum at 333 K for 10 h. The N2 adsorption isotherm at 77 K was obtained using a 3-Flex surface area and pore size analyzer (the purity of the N2 used was 99.999%). The pore size of both compounds was analyzed using the HKD model, yielding a pore size of 0.65 nm. Figure 4 As shown.
[0041] d. Calculation of the separation selectivity of the gas mixture The separation selectivity of an acetic acid-linked bendable trinuclear cluster-based Mg-MOF for a C2H2 and CO2 mixture was calculated using the Ideal Adsorption Solution Theory (IAST). The separation was conducted at 298 K and 1 bar, investigating the separation performance of the acetic acid-linked bendable trinuclear cluster-based Mg-MOF for a C2H2 and CO2 mixture with molar ratios of C2H2 to CO2 of 30:70, 50:50, and 70:30. Figure 5 The results showed that the selectivity of the acetic acid-linked bend-angled trinuclear cluster Mg-MOF to the above three groups of mixed gases was 2.77, 2.65 and 2.56, respectively.
[0042] e. Adsorption heat test Using the single-component gas adsorption isotherms measured at 273K, 283K, and 298K and the virial equation: ........................e3.
[0043] in, P This represents the pressure of a gas, measured in Pa. N This indicates the amount of gas adsorbed per unit mass or unit area. T It is thermodynamic temperature, with units of K and a. i and b i It is the virial coefficient.
[0044] ...................e4.
[0045] in, Qst This is the heat of adsorption, expressed in kJ / mol. R is the ideal gas constant.
[0046] The adsorption heat of the acetic acid-linked bendable trinuclear cluster Mg-MOF in Example 1 was calculated, as follows: Figure 7 As shown in the figure. The results indicate that at zero loading, the heat of adsorption of C2H2 is 26.6 kJ / mol, which is higher than that of CO2 (21.8 kJ / mol), indicating that the interaction between C2H2 and the acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF framework is stronger than that between C2H2 and CO2.
[0047] f. Dynamic Penetration Test 0.56 g of the acetic acid-linked bendable trinuclear cluster-based Mg-MOF from Example 1 was compressed into a tablet and placed in a dynamic permeation apparatus. It was then activated at 333 K for 10 h while the adsorption bed was purged with helium (He, ≥99.999%) at a rate of 20 mL / min. After the bed temperature was lowered to 298 K, a mixed gas C2H2 / CO2 (50:50, v / v) was introduced (flow rate: 2 mL / min). The separation performance of the acetic acid-linked bendable trinuclear cluster-based Mg-MOF was evaluated by detecting the elution time interval of the two gases. The detected data were used to plot... Figure 6 The results showed that the acetic acid-linked bendable trinuclear cluster Mg-MOF of Example 1 had excellent separation performance.
[0048] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. An acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF, characterized in that, Acetic acid-linked bend-shaped trinuclear cluster-based Mg-MOF belongs to the monoclinic crystal system, and its chemical formula is: C 44 H 29 Mg3O 16 P2, space group C2 / c, cell parameters: a=24.586(3)Å, b=15.2058(19)Å, c=24.410(4)Å, α=90°, β=117.603(4)°, γ=90°, V=8087(2)Å 3 Z=4, F(000)=1948.
0.
2. A method for preparing the acetic acid-linked bendable trinuclear cluster-based Mg-MOF according to claim 1, characterized in that, Includes the following steps: N,N-dimethylformamide, acetonitrile, and acetic acid are mixed to obtain a mixed solvent; Phosphorus trioxide (p-carboxyphenyl) and a soluble magnesium salt were dissolved together in a mixed solvent and subjected to a solvothermal reaction to obtain acetic acid-linked bend-shaped trinuclear cluster Mg-MOF.
3. The method for preparing acetic acid-linked bendable trinuclear cluster-based Mg-MOF according to claim 2, characterized in that, The molar ratio of tris(p-carboxyphenyl)phosphine oxide to soluble magnesium salt is 0.2:1~1.
3.
4. The method for preparing acetic acid-linked bendable trinuclear cluster-based Mg-MOF according to claim 2, characterized in that, The volume ratio of N,N-dimethylformamide, acetonitrile, and acetic acid is 2:2:0.5~0.
6.
5. The method for preparing acetic acid-linked bendable trinuclear cluster-based Mg-MOF according to claim 2, characterized in that, The conditions for the solvothermal reaction are: react at 120℃~130℃ for 3~4 days.
6. The application of the acetic acid-linked bendable trinuclear cluster Mg-MOF of claim 1 in the preparation of an acetylene adsorption and separation agent.
7. The application according to claim 6, characterized in that, Acetic acid-linked bendable trinuclear cluster Mg-MOFs are used for the adsorption and separation of mixed gases of acetylene and carbon dioxide.
8. The application according to claim 7, characterized in that, Before adsorbing and separating a mixture of acetylene and carbon dioxide, the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF underwent an activation treatment. The activation treatment was performed by immersing the acetic acid-linked bend-shaped trinuclear cluster Mg-MOF in acetonitrile, replacing the acetonitrile every 12 hours for 4 consecutive days, and then placing it under vacuum at 60℃~80℃ for 10~12 hours to obtain activated acetic acid-linked bend-shaped trinuclear cluster Mg-MOF.
9. The application according to claim 8, characterized in that, Activated acetic acid-linked bendable trinuclear cluster Mg-MOF selectively adsorbs acetylene from a mixture of acetylene and carbon dioxide.