An ultra-microporous porous coordination polymer, a preparation method thereof and application thereof in adsorptive separation of carbon dioxide

Abstract

This invention provides an ultramicroporous porous coordination polymer, its preparation method, and its application in the adsorption and separation of carbon dioxide, relating to the field of novel materials for gas-phase adsorption and separation. The material is named TCE-NH2ipa, with the chemical formula [Co2(bpt)2(NH2ipa)2]. n In this method, Co represents the metal center cobalt, bpt represents the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, and NH2ipa represents the organic ligand 3-aminoisophthalic acid. The method involves fully dissolving bpt, NH2ipa, and Co(NO3)2·6H2O, transferring the solution to a pressure-resistant sealed container, and heating it for reaction. After the reaction is complete, solvent exchange and heating activation steps are performed to finally obtain a homogeneous powdered material. The TCE-NH2ipa material of this invention exhibits good adsorption capacity for carbon dioxide, hardly adsorbs nitrogen at room temperature and pressure, and can selectively adsorb carbon dioxide in an acetylene / carbon dioxide mixture, demonstrating excellent selectivity and scalability.

Description

Technical Field

[0001] This invention relates to the field of novel materials for gas-phase adsorption and separation, and in particular to an ultramicroporous porous coordination polymer, its preparation method, and its application in the adsorption and separation of carbon dioxide. Background Technology

[0002] Porous coordination polymer materials are a class of crystalline porous materials in which metal ions and organic ligands form a periodic network structure through self-assembly. They have attracted attention since the 1990s and have been widely used in many fields such as gas adsorption and separation, synthetic catalysis, and sensing of environmental pollutants.

[0003] Since the selective adsorption performance of the porous coordination polymer material HKUST-1 for carbon dioxide was first reported in 2002, with in-depth research and development in the structural design and precise molecular recognition of porous coordination polymers, many porous coordination polymer materials with excellent gas separation performance are being gradually developed. Domestic and international researchers have conducted extensive research and reviews on the application of porous coordination polymer materials in carbon dioxide adsorption and separation. Firstly, porous coordination polymer materials can utilize the molecular sieve mechanism to construct precise pore sizes for the size separation of carbon dioxide and other gases. For example, the porous coordination polymer material Qc-5-Cu prepared by Professor Chen Kaijie et al. of Northwestern Polytechnical University has a pore size of 3.3 Å, achieving precise sieving of carbon dioxide from larger gases such as nitrogen and methane. In terms of kinetic and thermodynamic separation, the molecular recognition mechanisms that have been identified include: unsaturated metal coordination sites can be introduced into porous coordination polymers to interact with carbon dioxide and achieve capture; a wide variety of organic ligands in porous coordination polymers can be separated from the mixed system through various interaction mechanisms such as acid-base interactions, electrostatic interactions, hydrogen bonds, and π-π interactions by pre-designed or post-modified methods. In recent years, inspired by the precise molecular recognition functions of biomolecules with high structural freedom (such as proteins), flexible porous coordination polymers exhibiting guest molecule adsorption responses that trigger changes in the host structure have attracted great attention from researchers and become a major research hotspot in the field of molecular recognition and separation. Utilizing the "breathing" effect of the flexible framework of soft-porous materials can achieve unique molecular recognition and separation performance, achieving higher working capacity, separation performance, and easier regeneration compared to rigid porous structures. For example, the flexible porous coordination polymer material MUF-15-OMe only exhibits "open-door" adsorption behavior for carbon dioxide, while showing no adsorption response for nitrogen, thus achieving highly selective carbon dioxide / nitrogen separation. However, most existing porous coordination polymers have ligands that are not sourced in a green manner, their separation performance is difficult to control, and they are not effective at selectively adsorbing carbon dioxide in a mixture of carbon dioxide and acetylene. Therefore, there is a need to develop green, ultramicroporous coordination polymer materials for selective carbon dioxide adsorption. To address these problems, this invention is proposed. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention provides an ultramicroporous coordination polymer, its preparation method, and its application in the adsorption and separation of carbon dioxide. The amino-functionalized ultramicroporous coordination polymer material prepared by this invention exhibits high adsorption capacity for carbon dioxide, moderate adsorption capacity for acetylene, and extremely low adsorption capacity for nitrogen. It also possesses good selectivity and scalability, enabling lower-cost carbon dioxide separation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A microporous coordination polymer with the molecular formula C 40 H 23 Co2N 12 O8, with the chemical formula [Co2(bpt)2(NH2ipa)2] n It is named TCE-NH2ipa, where Co represents the metal center cobalt, and bpt represents the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, with the structural formula as follows: NH2ipa represents the organic ligand 3-aminoisophthalic acid, with the structural formula as follows: , where n indicates that the coordination polymer has an infinitely extended periodic framework structure.

[0006] Preferably, the TCE-NH2ipa is a prismatic single crystal with space group [missing information]. Cc The unit cell parameters are a = 16.16 Å, b = 11.80 Å, c = 24.38 Å, α = 90°, β = 96.822°, γ = 90°, and the unit cell volume is 4615.49 Å. 3 .

[0007] Preferably, in the crystal structure of TCE-NH2ipa, each cobalt atom is a deformed octahedron with six coordinates, where four oxygen atoms and two nitrogen atoms occupy the six vertices of the octahedron, and a [Co2] metal cluster is formed under the carboxyl bridging of the carboxylic acid ligand.

[0008] Preferably, the porous coordination polymer material has twisted microporous periodic three-dimensional channels, exhibiting the characteristics of narrow pore windows and large pore cavities. The pore window size at the narrowest point of the TCE-NH2ipa channel is 3.4 Å × 4.0 Å, which belongs to the ultramicroporous structure, and the pore window size is highly matched with the molecular size of CO2.

[0009] The present invention also provides a method for preparing the aforementioned porous coordination polymer material, comprising the following steps: S1: Dissolve the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine and the organic ligand 3-aminoisophthalic acid in an organic solvent by stirring, and then add cobalt nitrate hexahydrate to dissolve, to obtain a mixed solution; S2: Transfer the mixed solution obtained in step S1 to a pressure-resistant sealed container, heat to 80~100℃, and react for 24~48 h; S3: After the reaction is complete, wait for the reaction solution to cool to room temperature, filter to obtain a uniform powder material, and use a low-boiling-point solvent for solvent exchange treatment to obtain the solvent-exchanged material. S4: Dry the material obtained after solvent exchange in step S3 to completely remove the solvent molecules in the pores, and obtain the porous coordination polymer material TCE-NH2ipa.

[0010] Preferably, the molar ratio of the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, 3-aminoisophthalic acid and cobalt nitrate hexahydrate in step S1 is 1:(1~2):(1~2).

[0011] Preferably, the organic solvent in step S1 is composed of methanol and N,N-dimethylformamide, and the volume ratio of methanol to N,N-dimethylformamide is 1:0.5~2.

[0012] Preferably, the low-boiling-point solvent used in step S3 is methanol, ethanol, dichloromethane or acetone, the exchange treatment time is not less than 3 days, and the number of solvent changes is not less than 4 times.

[0013] Preferably, the drying temperature in step S4 is 120~150℃ and the drying time is 24~48 h.

[0014] The present invention also provides the application of the above-mentioned porous coordination polymer material in the adsorption and separation of carbon dioxide.

[0015] Beneficial effects of the present invention (1) The porous coordination polymer material TCE-NH2ipa obtained in this invention has a periodic three-dimensional small-pore-large-cavity structure, with the small pores having a cross-sectional area of ​​3.4 Å × 4.0 Å. This pore size is at the ultramicroporous level, and the pore surface is distributed with oxygen atom interaction sites, amino groups, and sp... 2 Hybridized nitrogen atoms. Confining the interaction site within ultramicropores maximizes host-guest interactions, thereby promoting carbon dioxide adsorption.

[0016] (2) This invention provides a new method for selective adsorption of carbon dioxide based on porous coordination polymer materials. The novel ultra-microporous porous coordination polymer material used in this method has a special pore structure, and its adsorption capacity for carbon dioxide is higher than that for acetylene, while its adsorption capacity for nitrogen is extremely low, thereby achieving efficient separation of the above three gases.

[0017] (3) In the porous coordination polymer material obtained by the present invention, cobalt is saturated and therefore there are no open metal sites. The thermal decomposition temperature is as high as 450℃, and it has good thermal stability.

[0018] (4) Compared with conventional porous adsorbents, the porous coordination polymer material used in this invention has the advantages of high adsorption capacity, high adsorption selectivity, low material cost, and green material source. The material is simple and safe to prepare, with high yield and basically no by-products.

[0019] (5) The separation method provided by this invention has advantages over traditional distillation methods, such as mild operating conditions, low energy consumption, and small equipment investment. Therefore, this invention is expected to bring economic benefits to relevant petrochemical enterprises. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention and the solutions of the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The image of TCE-NH2ipa obtained in Example 1 under an optical microscope; Figure 2 This is a schematic diagram of the spatial structure of TCE-NH2ipa obtained in Example 1 (along the unit cell). c Views observed from the axis angle); Figure 3 The results of X-ray powder diffraction experiments on TCE-NH2ipa obtained in Example 1 are shown below. Figure 4 The thermogravimetric curve of TCE-NH2ipa obtained in Example 1; Figure 5 The adsorption isotherms of TCE-NH2ipa synthesized and activated in Example 1 for carbon dioxide and acetylene at 25°C are shown. Figure 6 This is a comparison diagram of the selectivity of TCE-NH2ipa and the non-amino-functionalized isomorphic porous coordination polymer (named TCE-ipa) for carbon dioxide and acetylene in Example 1. Detailed Implementation

[0022] A microporous coordination polymer with the chemical formula [Co2(bpt)2(NH2ipa)2] n It is named TCE-NH2ipa, where Co represents the metal center cobalt, and bpt represents the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, with the structural formula as follows. NH2ipa represents the organic ligand 3-aminoisophthalic acid, with the structural formula as follows: , where n indicates that the coordination polymer has an infinitely extended periodic framework structure.

[0023] According to the present invention, the TCE-NH2ipa is a prismatic single crystal with the molecular formula C. 40 H 23 Co2N 12 SCXRD analysis was performed on O8, and the results showed that TCE-NH2ipa is a monoclinic crystal system with space group O8. Cc The unit cell parameters are a = 16.16 Å, b = 11.80 Å, c = 24.38 Å, α = 90°, β = 96.822°, γ = 90°, and the unit cell volume is 4615.49 Å. 3 In the crystal structure of TCE-NH2ipa, each cobalt atom is a deformed octahedron with six coordinates, where four oxygen atoms and two nitrogen atoms occupy the six vertices of the octahedron, and form a [Co2] metal cluster under the carboxyl bridging of the carboxylic acid ligand.

[0024] The porous coordination polymer material has twisted microporous periodic three-dimensional channels, exhibiting the characteristics of narrow pore windows and large pore cavities. The narrowest pore window size of TCE-NH2ipa is 3.4 Å × 4.0 Å, which belongs to the ultramicroporous structure, and the pore window size is highly matched with the molecular size of CO2.

[0025] The present invention also provides a method for preparing the aforementioned porous coordination polymer material, comprising the following steps: S1: Dissolve the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine and the organic ligand 3-aminoisophthalic acid (NH2ipa) in an organic solvent, preferably methanol and N,N-dimethylformamide, with a volume ratio of methanol to N,N-dimethylformamide of 1:(0.5~2). Then add cobalt nitrate hexahydrate (Co(NO3)2·6H2O), and stir or use ultrasonic oscillation to fully dissolve it to obtain a mixed solution. The molar ratio of the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, 3-aminoisophthalic acid, and Co(NO3)2·6H2O is preferably 1:(1~2):(1~2), more preferably 1:1:1. S2: Transfer the mixed solution obtained in S1 to a pressure-resistant sealed container, heat it to 80~100℃, and react for 24~48h; the sealed container is preferably a sealed glass reaction bottle with a polytetrafluoroethylene gasket or a reaction vessel with a polytetrafluoroethylene liner. S3: After the reaction is completed, the reaction solution is cooled to room temperature and filtered to obtain a uniform powder material. The powder material is then subjected to solvent exchange treatment using a low-boiling-point solvent to obtain the solvent-exchanged material. The low-boiling-point solvent is preferably methanol, ethanol, dichloromethane or acetone. The exchange treatment time is preferably not less than 3 days and the number of solvent changes is preferably not less than 4 times. S4: The material obtained after solvent exchange in S3 is filtered and dried. The drying is preferably carried out under vacuum at 120~150℃ for 24~48 h to completely remove the solvent molecules in the pores and obtain the activated porous coordination polymer material TCE-NH2ipa.

[0026] According to the present invention, the filtration process described in steps S3 and S4 is performed using a filtration device or a Buchner funnel equipped with an organic phase filter membrane or filter paper with a pore size of 0.2~5 μm.

[0027] The present invention also provides the application of the above-mentioned porous coordination polymer material in the adsorption and separation of carbon dioxide.

[0028] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. 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.

[0029] Example 1 66 mg (0.3 mmol) of 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine ligand, 54 mg (0.3 mmol) of 3-aminoisophthalic acid ligand, and 87 mg (0.3 mmol) of cobalt nitrate hexahydrate were added to 30 mL of a 1:1 mixture of methanol and N,N-dimethylformamide. The mixture was sonicated for 15 min until the solid was completely dissolved, and then further dissolved by sonication. The resulting solution was transferred to a 50 mL transparent screw-top glass bottle and placed in an oven at 80 °C for 24 h. After cooling to room temperature, the solution was filtered using a glass frit filter equipped with an organic phase filter membrane with a pore size of 0.22 μm to obtain pink TCE-NH2ipa single crystals. Figure 1 After exchanging the product in anhydrous methanol for three days, the resulting product was vacuum dried at 150°C for 24 h to obtain fully activated [(Co2(bpt)2(NH2ipa)2] n It is named TCE-NH2ipa, and the crystals are activated / ground to form a powder material.

[0030] The spatial structure of the prepared TCE-NH2ipa is as follows Figure 2 As shown; X-ray powder diffraction was used to analyze the material, and the results were consistent with the powder diffraction obtained from analytical structure simulation. Figure 3 Thermogravimetric curves of the material before and after vacuum drying ( ). Figure 4 This indicates that the material is fully activated, and also demonstrates that the material's thermal stability reaches over 400℃.

[0031] The adsorption capacity of activated TCE-NH2ipa for CO2 and C2H2 was measured at 25℃. TCE-NH2ipa showed a higher carbon dioxide adsorption capacity at room temperature, such as... Figure 5 As shown, 25 cm can be achieved at 0.15 bar. 3 / g, 36cm at 0.5 bar 3 / g, reaching 42 cm at 1 bar 3 / g. At the same time, it has a certain acetylene adsorption capacity at room temperature, such as... Figure 5 As shown, it is 19 cm at 0.15 bar. 3 / g, at 0.5 bar, is 30 cm. 3 / g, 36 cm at 1 bar 3 / g. This indicates that it exhibits a relatively rare selectivity for carbon dioxide in a carbon dioxide / acetylene mixture (e.g., Figure 5Simultaneously, its adsorption capacity for nitrogen at 77 K was measured, and the results showed that its absolute adsorption capacity was less than 2 mL. Due to the small adsorption capacity, the adsorption isotherm was inaccurate, and therefore the results are not presented. The above demonstrates that TCE-NH2ipa has good carbon dioxide adsorption selectivity, and compared with the non-amino-functionalized isomorphic porous coordination polymer (named TCE-ipa), it exhibits reversed carbon dioxide / acetylene selectivity, which can be described by ideal solution theory selectivity. Figure 6 ) The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0032] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A microporous coordination polymer, characterized in that, Its molecular formula is C 40 H 23 Co2N 12 O8, with the chemical formula [Co2(bpt)2(NH2ipa)2] n It is named TCE-NH2ipa, where Co represents the metal center cobalt, and bpt represents the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, with the structural formula as follows. NH2ipa represents the organic ligand 3-aminoisophthalic acid, with the structural formula as follows: , where n indicates that the coordination polymer has an infinitely extended periodic framework structure.

2. The ultraporous coordination polymer according to claim 1, characterized in that, The TCE-NH2ipa mentioned above is a prismatic single crystal with space group [missing information]. Cc The unit cell parameters are a = 16.16 Å, b = 11.80 Å, c = 24.38 Å, α = 90°, β = 96.822°, γ = 90°, and the unit cell volume is 4615.49 Å. 3 .

3. The ultraporous coordination polymer according to claim 1, characterized in that, In the crystal structure of TCE-NH2ipa, each cobalt atom is a six-coordinate deformed octahedron, with four oxygen atoms and two nitrogen atoms occupying the six vertices of the octahedron, forming a [Co2] metal cluster under the carboxyl bridging of the carboxylic acid ligand.

4. The ultraporous coordination polymer according to claim 1, characterized in that, The porous coordination polymer material has twisted microporous periodic three-dimensional channels, exhibiting the characteristics of narrow pore windows and large pore cavities. The narrowest pore window size of TCE-NH2ipa is 3.4 Å × 4.0 Å, which belongs to the ultramicroporous structure, and the pore window size is highly matched with the molecular size of CO2.

5. The method for preparing a porous coordination polymer material according to claim 1, characterized in that, Includes the following steps: S1: Dissolve the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine and the organic ligand 3-aminoisophthalic acid in an organic solvent by stirring, and then add cobalt nitrate hexahydrate to dissolve, to obtain a mixed solution; S2: Transfer the mixed solution obtained in step S1 to a pressure-resistant sealed container, heat to 80~100℃, and react for 24~48h; S3: After the reaction is complete, wait for the reaction solution to cool to room temperature, filter to obtain a uniform powder material, and use a low-boiling-point solvent for solvent exchange treatment to obtain the solvent-exchanged material. S4: Dry the material obtained after solvent exchange in step S3 to completely remove the solvent molecules in the pores and obtain the porous coordination polymer material TCE-NH2ipa.

6. The method for preparing a porous coordination polymer material according to claim 5, characterized in that, The molar ratio of the organic ligand 4-(3-pyridin-4-yl-1H-1,2,4-triazol-5-yl)pyridine, 3-aminoisophthalic acid and cobalt nitrate hexahydrate in step S1 is 1:(1~2):(1~2).

7. The method for preparing a porous coordination polymer material according to claim 5, characterized in that, The organic solvent in step S1 is composed of methanol and N,N-dimethylformamide, and the volume ratio of methanol to N,N-dimethylformamide is 1:0.5~2.

8. The method for preparing a porous coordination polymer material according to claim 5, characterized in that, The low-boiling-point solvent used in step S3 is methanol, ethanol, dichloromethane or acetone, the exchange treatment time is not less than 3 days, and the number of solvent changes is not less than 4 times.

9. The method for preparing a porous coordination polymer material according to claim 5, characterized in that, The drying temperature described in S4 is 120~150℃, and the drying time is 24~48 h.

10. The application of the porous coordination polymer material according to claim 1 in the adsorption and separation of carbon dioxide.

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