Porous coordination polymers with interpenetrating frameworks, methods of preparation and applications in ethane / ethylene separations at high temperatures

Abstract

The present application relates to a kind of porous coordination polymers with interpenetrating framework, preparation method and application in ethane / ethylene high temperature separation, belong to coordination chemistry material technical field.Porous coordination polymers are Cu-based coordination polymers, its chemical formula is [Cu2 (BDC) 2L2] n (solvent) x , belong to C2 / c space group, L2 is 4,6-di (1H-1,2,4-triazole-1-yl) pyrimidine-2-amine, NH2 Group is again with adjacent framework forms single hydrogen bond;It is obtained by adding regulating ligand during solvothermal reaction of ligand and metal salt.The present application proposes a new method to regulate temperature-dependent dynamic characteristics in hydrogen-bonded interpenetrating framework, with the weakening of hydrogen bond, porous coordination polymers with one-dimensional narrow-neck channel exhibit promising structural response to ethane / ethylene at high temperature, so that it shows significant ability to directly obtain polymerization grade ethylene.

Description

Technical Field

[0001] This invention relates to a porous coordination polymer with an interpenetrating framework, its preparation method, and its application in the separation of ethane / ethylene at high temperatures, belonging to the field of coordination chemistry materials technology. Background Technology

[0002] With the increasing demand for polymer-grade ethylene (C2H4), the urgency of efficiently removing ethane (C2H6) from cracked gases downstream is becoming increasingly apparent. Currently, C2H6 removal is mainly achieved through cryogenic distillation, a process that is energy-intensive and produces high carbon emissions. Adsorption separation technology, due to its use of porous materials to selectively capture gases (non-patent literature 1), offers significantly improved energy efficiency and is considered an alternative or transitional technology. Therefore, the selection or construction of suitable porous materials has attracted widespread attention.

[0003] As a crystalline material, porous coordination polymers (PCPs) exhibit direct and convenient characteristics in pore regulation and functionalization, enabling them to achieve good separation performance (Non-Patent Literature 2), especially compared to materials such as zeolites, activated carbon, and even covalent organic frameworks (COFs). Considering the slightly higher polarizability of C2H6 and the slightly larger quadrupole moment of C2H4, the design principles of PCPs can be divided into two categories: C2H6-selective materials and C2H4-selective materials. In terms of the purity of the obtained C2H4 and system energy consumption, C2H6 selective capture is more attractive. To achieve this goal, various strategies have been developed in rigid PCPs, such as the hierarchical nature of supramolecular interactions, molecular docking, synergistic adsorbent separation techniques, and interconnected cage structures. However, in reality, either the selectivity is slightly improved but the capacity is reduced, or the storage capacity is increased but the capacity ratio is only slightly greater than 1. In addition, these thermodynamically dominated processes exhibit poor or no separation performance at high temperatures, which means a sharp decline in energy efficiency.

[0004] As a subclass of porous coordination polymers (PCPs), soft frameworks exhibit diverse responses to guest molecules and are therefore considered promising platforms for separating C2H6 / C2H4 (Non-Patent Literature 3). Furthermore, the temperature-dependent kinetics of these frameworks may create opportunities for selective adsorption at high temperatures. Currently, the typical flexibility properties of these frameworks, such as gating opening, breathing effects, ligand twisting / rotation, and node variations, generally require strong external stimuli or result in significant pore expansion, making it very difficult to achieve preferred C2H6 capture, especially in the presence of C2H4.

[0005] Non-patent literature 1: KZ Su, WJ Wang, SF Du, CQ Ji, DQ Yuan, Nat. Commun. 2021, 12, 3703.

[0006] Non-patent literature 2: ZQ Zhang, SB Peh, YX Wang, CJ Kang, WDFan, D. Zhao, Angew. Chem. Int. Ed. 2020, 59, 18927-18932.

[0007] Non-patent literature 3: VI Nikolayenko, DC Castell, D. Sensharma, M.Shivanna, L. Loots, KA Forrest, CJ Solanilla-Salinas, KI Otake, S.Kitagawa, LJ Barbour, B. Space, MJ Zaworotko, Nat. Chem. 2023, 15, 542-549. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to regulate the temperature-dependent dynamic characteristics of hydrogen-bonded interpenetrating frameworks, exhibiting structural dynamics under the influence of C2H6 and C2H4, and demonstrating the ability to produce polymer-grade C2H4 at high temperatures.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A porous coordination polymer with an interpenetrating framework is disclosed. The porous coordination polymer is a Cu-based coordination polymer with the chemical formula [Cu₂(BDC)₂L₂]. n (solvent) x L2 is 4,6-bis(1H-1,2,4-triazol-1-yl)pyrimidine-2-amine (L2), n is the number of repeating units, and it belongs to the C2 / c space group. In the repeating unit, four Cu2(COO)4 nodes and four BDC links form a square grid layer. The two vertices of the Cu2(COO)4 nodes coordinate with the N atoms of the triazolyl group in L2 to construct a three-dimensional columnar pcu framework. The NH2 group forms a single hydrogen bond with the adjacent framework.

[0011] The above-mentioned porous coordination polymer is prepared by a solvothermal reaction of ligands, regulating ligands and metal salts.

[0012] Preferably, the molar ratio of the aforementioned ligand, metal salt and regulating ligand is 1:1.5~2:2.5~3.

[0013] Preferably, the aforementioned ligand is obtained by reacting 2-amino-4,6-dichloropyrimidine, 1,2,4-triazole, a base, and a catalyst in an organic solvent.

[0014] Preferably, the aforementioned base is potassium hydroxide or sodium hydroxide, the catalyst is tetrabutylammonium bromide, the organic solvent is acetonitrile, and the molar ratio of 2-amino-4,6-dichloropyrimidine, 1,2,4-triazole, base and catalyst is 1:2~3:2~3:0.1~0.5.

[0015] Preferably, the aforementioned metal salt is Cu(NO3)2•2H2O, and the regulating ligand is terephthalic acid.

[0016] Preferably, the solvent used in the reaction is a mixed solution of DMF and water in a volume ratio of 0.5~2:0.2~1.5.

[0017] Preferably, the reaction conditions are 80~100 °C for 24~72 h.

[0018] After the above reaction is completed, the resulting porous coordination polymer is immersed in methanol for activation treatment.

[0019] The porous coordination polymer obtained by the above-mentioned regulation method.

[0020] Applications of the above-mentioned porous coordination polymers in the separation of C2H6 and C2H4 at high temperatures.

[0021] The advantages of this invention are: it proposes a novel method to regulate the temperature-dependent dynamic properties of hydrogen-bonded interpenetrating frameworks. As hydrogen bonds weaken, NTU-101-NH2 with a one-dimensional narrow-necked channel exhibits a promising structural response to C2H6 and C2H4 at 328 K, demonstrating a significant ability to directly obtain polymer-grade C2H4 with stable separation performance; NTU-101-NH2 can be prepared on a large scale by stirring the corresponding reagents in solution for a short time. Attached Figure Description

[0022] Figure 1 Schematic diagram of dynamic regulation within a hydrogen bond interpenetrating framework used for reverse C2H6 / C2H4 separation.

[0023] Figure 2 Structures of two porous coordination polymers (PCPs): raw material (a), views of interlaced PCU frameworks (b and e), views of hydrogen bonds formed between adjacent frameworks (c and f), and views of narrow neck portions in NTU-101 and NTU-101-NH2 (d and g), with a probe radius of 1.4 Å used when calculating the inner surface;

[0024] Figure 3Powder X-ray diffraction (PXRD) patterns of NTU-101 (a) and NTU-101-NH2 (b), and adsorption isotherms of N2 (77 K, c) and CO2 (195 K, d) for the two porous coordination polymers (PCPs);

[0025] Figure 4 : Adsorption isotherms of C2H6 and C2H4 for NTU-101 (a, c) and NTU-101-NH2 (b, d), respectively; differences in the adsorption capacity of C2H6 and C2H4 of NTU-101 and NTU-101-NH2 at 50 kPa with temperature (e); comparison of adsorption capacity with other materials at 298 K and 50 kPa (f), α: 293 K, β: 296 K, δ: 273 K, ε: 293 K, η: 328 K;

[0026] Figure 5 In-situ PXRD patterns of NTU-101 (293 K) and NTU-101-NH2 (328 K) at different C2H6 or C2H4 pressures (a); in-situ infrared spectra of NTU-101 (b, 293 K) and NTU-101-NH2 (c, 328 K) at 1 bar C2H6 or C2H4; the upper panel shows the difference spectrum obtained by comparing the spectrum of gas-loaded PCPs (porous coordination polymers) with the spectrum after activation. The region beyond the scale bar is due to strong absorption in the gas phase. The lower panel shows the PCPs spectrum with KBr as a reference. The black, orange, and green dashed lines highlight the changes in the triazole ring, pyrimidine ring, and benzene ring modes, respectively. Symbols and abbreviations: ν = stretching, δ = in-plane deformation, γ = out-of-plane deformation, Ƭ = torsion, as = asymmetric, s = symmetric, ph = phenyl, tz = triazole, py = pyrimidine;

[0027] Figure 6 NTU-101 (a) and NTU-101-NH2 (b) for C2H6 / C2H4 (1 / 1, v / v, 2 mL·min) -1 Experimental breakthrough curves of mixed gases; comparison of C2H4 yields of NTU series materials with other reference materials (c); cyclic breakthrough separation performance of NTU-101 and NTU-101-NH2 (d); large-scale synthesis of NTU-101-NH2 (e) and C2H4 adsorption isotherm (f). Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] Synthesis of porous coordination polymer NTU-101-NH2:

[0031] (1) Synthesis of ligand 4,6-bis(1H-1,2,4-triazol-1-yl)pyrimidine-2-amine (L2)

[0032] 2-Amino-4,6-dichloropyrimidine (8.2 g, 50.01 mmol), 1,2,4-triazole (8.29 g, 120.14 mmol), potassium hydroxide (6.73 g, 120.17 mmol), and tetrabutylammonium bromide (1.61 g, 11.36 mmol) were added to a 250 mL round-bottom flask containing acetonitrile (150 mL). The mixture was refluxed in an oil bath for 24 hours, during which a large amount of white precipitate was formed. After cooling, the product was collected by filtration, washed three times with acetonitrile, and then washed three times with water. After drying under vacuum at 50 °C, a white solid L2 was given (yield: ~89%). ¹H-NMR (DMSO-d6) of L2: δ = 7.31 (¹H, s), 7.63 (²H, s), 8.43 (²H, s), 9.27 (²H, s).

[0033] (2) Synthesis of NTU-101-NH2

[0034] L2 (5 mg, 0.022 mmol), Cu(NO3)2•2H2O (10 mg, 0.039 mmol), and terephthalic acid H2BDC (10 mg, 0.06 mmol) were dissolved in a DMF / H2O mixture (3 mL, 1 / 1, v / v). The solution was then sealed in a 10 mL glass bottle and reacted at 90 °C for 2 days. After cooling, green blocky crystals were obtained and washed three times with fresh DMF (yield based on L2: ~42%).

[0035] Example 2

[0036] Synthesis of porous coordination polymer NTU-101:

[0037] (1) Synthesis of ligand 4,6-bis(1H-1,2,4-triazol-1-yl)pyrimidine (L1)

[0038] 4,6-Dichloropyrimidine (7.45 g, 50.01 mmol), 1,2,4-triazole (8.29 g, 120.14 mmol), potassium hydroxide (6.73 g, 120.17 mmol), and tetrabutylammonium bromide (1.61 g, 11.36 mmol) were added to a 250 mL round-bottom flask containing acetonitrile (150 mL). The mixture was refluxed in an oil bath for 24 hours, during which a large amount of white precipitate was formed. After cooling, the product was collected by filtration, washed three times with acetonitrile, and then washed three times with water. After drying under vacuum at 50 °C, a white solid L1 was given (yield: ~92%). ¹H-NMR (DMSO-d6) of L1: δ = 8.13 (¹H, s), 8.48 (²H, s), 9.27 (¹H, s), 8.62 (²H, s).

[0039] (2) Synthesis of NTU-101

[0040] L1 (5 mg, 0.023 mmol), Cu(NO3)2•2H2O (10 mg, 0.039 mmol), and terephthalic acid (H2BDC, 10 mg, 0.06 mmol) were dissolved in a mixed solution of N,N'-dimethylformamide (DMF) / H2O (3 mL, 1 / 1, v / v). The solution was then sealed in a 10 mL glass bottle and reacted at 90 °C for 2 days. After cooling, green blocky crystals were obtained and washed three times with fresh DMF (yield based on L1: ~50%).

[0041] Example 3

[0042] Activation of porous coordination polymers:

[0043] Prior to adsorption measurements, the synthesized porous coordination polymer sample was immersed in dry methanol for three days to remove non-volatile solvents. The extract was decanted every 8 hours and replaced with fresh methanol. The solvent-exchanged sample was then heated in a dynamic high-vacuum environment at 373 K for 20 hours to obtain a fully activated sample.

[0044] Structural and property analysis of porous coordination polymers:

[0045] (1) Structure of porous coordination polymers

[0046] Copper nitrate reacted with 4,6-bis(1H-1,2,4-triazol-1-yl)pyrimidine (L1) in a solvothermal reaction to form bulk crystals. Figure 2 Single-crystal X-ray diffraction analysis indicates that the crystal belongs to the C2 / c space group and has the chemical formula [Cu2(BDC)2L1]. n (solvent) x(NTU-101). The asymmetric unit contains two Cu. 2+ Ion, one ligand (L1), and two BDCs 2- Anion. Two Cu atoms 2+ Ions and BDC 2- The four carboxylate groups of the anion form classic paddlewheel-shaped Cu2(COO)4 nodes. These four Cu2(COO)4 nodes and four BDC connectors further form a square grid layer (sql layer). The two vertices of the Cu2(COO)4 nodes coordinate with the N atom of the triazole group in L1, constructing a three-dimensional columnar PCu framework. Figure 2 (b)). Due to the presence of significant nanocavities (7.0 × 7.0 × 10.0 ų) within this single framework, the two identical networks interpenetrate. However, the pyrimidine sites in L1 determine the degree of displacement of the interpenetrating framework (3.3 Å, 4.6 Å, and 5.8 Å along axes a, b, and c, respectively), and through multiple hydrogen bonds ( Figure 2 (c) are interconnected. Furthermore, the prominent pyrimidine ring in L1 blocks the availability of the channel in the other two directions, forming a one-dimensional zigzag channel. The wide aperture of this channel is 11.9 Å, but the narrow neck formed by adjacent BDC units is only 3.1 Å. Figure 2 (d) Based on the above structural features, NTU-101 is likely an ideal candidate material for separating ethane (C2H6) and ethylene (C2H4), as its narrow neck is slightly smaller than the molecular size of these two gases. Furthermore, the host-guest interaction strength can be tuned by temperature to help overcome the frame displacement energy barrier related to the neck size.

[0047] To ensure optimal ethane (C2H6) adsorption performance and enrich the material platform, ligand L1 was replaced with L2 during the synthesis of the new crystal (NTU-101-NH2), introducing amino (-NH2) supramolecular sites into the NTU-101 framework. The ligand-node connection mode and interpenetration characteristics of NTU-101-NH2 are identical to those of NTU-101. However, the degree of framework displacement differs from the previous structure (3.3 Å vs 3.5 Å, 4.6 Å vs 4.0 Å, and 5.8 Å vs 3.3 Å along axes a, b, and c, respectively). Compared to the three hydrogen bonds between the pyrimidine and BDC units in NTU-101, the introduced NH2 group forms a single hydrogen bond with the adjacent framework in NTU-101-NH2. Figure 2 (e)-(f)). Furthermore, the size of the narrow neck is slightly increased (3.9 Å vs 3.1 Å), more closely resembling the molecular size of the two gases ( Figure 2(g). Therefore, considering the reduced number of hydrogen bonds, the increased neck size, and the potential interaction sites, NTU-101-NH2 may be a more effective candidate material for separating C2H6 / C2H4.

[0048] (2) PXRD patterns of porous coordination polymers

[0049] The phase purity of the two synthesized crystals was confirmed by comparing their powder X-ray diffraction (PXRD) patterns with simulated data. However, some diffraction peaks shifted slightly to higher angles after activation. Figure 3 (a)-(b)), this is due to the shrinkage of the pore system caused by the removal of guest molecules during activation. Thermogravimetric analysis (TGA) showed that the sample weight of the two porous coordination polymers (PCPs) gradually decreased before 325°C, followed by rapid weight loss, indicating complete material decomposition. For the activated sample, a clear plateau indicates that the sample was fully activated.

[0050] The permanent porosity of the two PCPs was investigated by N2 (77 K) and CO2 (195 K) adsorption tests. Figure 3 (c)-(d)). Both exhibit type I N2 adsorption isotherms, with maximum N2 adsorption capacities of approximately 180 cm⁻¹ for NTU-101. 3 ·g -1 and NTU-101-NH2 approximately 183 cm 3 ·g -1 However, their CO2 adsorption behaviors differ. NTU-101 exhibits structural dynamics at P / P0 = 0.05, while NTU-101-NH2 shows three steps of CO2 adsorption (P / P0 = 0.01, 0.02, and 0.20), reflecting the latter's higher sensitivity to structural dynamics. These results are consistent with the reduction in interframework hydrogen bonds in NTU-101-NH2.

[0051] (3) Temperature dependence test of porous coordination polymers

[0052] Given the excellent pore systems of the two porous coordination polymers, single-component adsorption isotherms of C2H6 and C2H4 were collected. Figure 4 Both PCPs exhibit temperature-dependent gated adsorption behavior for C2H6 and C2H4. Within the temperature range of 288–303 K, NTU-101 shows a stepwise adsorption behavior for both C2H6 and C2H4. Figure 4(a)-(b)). At the same temperature, the gating pressure triggered by C2H6 is lower than that of C2H4; for example, at 293 K, the adsorption gating pressures for C2H6 and C2H4 are 36 kPa and 57 kPa, respectively. However, as the temperature increases, no gating phenomenon is observed, which is attributed to insufficient stimulation of neck expansion by gas molecules at higher temperatures. In stark contrast, NTU-101-NH2 exhibits unprecedented adsorption behavior for C2H6 and C2H4: gating of both gases occurs over a wide temperature range of at least 288–333 K, and C2H6 preferentially triggers gating ( Figure 4 (c)-(d)). This result indicates that direct adsorption and separation of C2H4 from C2H6 / C2H4 mixtures at higher temperatures is highly feasible.

[0053] To assess separation potential, the difference in gas adsorption capacity at 50 kPa was chosen as the evaluation metric because an equimolar mixture (total pressure: 100 kPa) typically exists downstream of the pyrolysis gas. Figure 4 As shown in (e), NTU-101 exhibits the greatest difference in adsorption capacity between C2H6 and C2H4 at 288 K, reaching 30.1 cm⁻¹. 3 ·g -1 The value decreases slightly to 27.8 cm at 293 K. 3 ·g -1 The adsorption capacity subsequently decreased significantly above 298 K. From an energy efficiency perspective, 293 K is considered the optimal temperature for separating C2H6 / C2H4 using NTU-101. For NTU-101-NH2, the adsorption capacity of C2H6 and C2H4 showed little difference at lower temperatures, but increased significantly at 323 K (24.9 cm⁻¹). 3 ·g -1 And it reaches its highest value (25.9 cm) at 328 K. 3 ·g -1 The K value then decreases at 333 K. Therefore, NTU-101-NH2 has significant potential for separating C2H6 / C2H4 at higher temperatures.

[0054] (4) In-situ PXRD and in-situ infrared (IR) spectroscopy measurements of porous coordination polymers

[0055] To verify the structural dynamics, in-situ PXRD patterns of NTU-101-NH2 were collected at 293 K and 328 K, respectively. Figure 5(a)). With increasing C2H6 pressure, the [1 2 1] crystal plane peak of NTU-101 shifts to a lower angle at 40 kPa, while a similar phenomenon occurs in C2H4 at 60 kPa. Similarly, for NTU-101-NH2, at 328 K, the [0 2 1] crystal plane peak of C2H6 at 40 kPa and C2H4 at 70 kPa also shifts to a lower angle. These results further confirm that C2H6 induces structural dynamics changes earlier than C2H4 in both PCPs. Further structural analysis shows that the shift of the [1 21] crystal plane of NTU-101 and the [0 2 1] crystal plane of NTU-101-NH2 to a lower angle corresponds to the closure of the interpenetrating framework, resulting in the expansion of the channel neck. The reduced number of hydrogen bonds between interpenetrating frameworks in NTU-101-NH2 results in a relatively low energy barrier for its structural dynamics, allowing for fine optimization of the adsorption temperatures of C2H6 and C2H4 over a wider and higher temperature range.

[0056] In-situ infrared (IR) spectroscopy measurements were performed on NTU-101 (293 K) and NTU-101-NH2 (328 K), with loading of C2H6 and C2H4 monitored, respectively. Both gases were loaded at 1 bar, a condition that triggers structural expansion. Vibrational bands observed on the PCPs were characterized by comparison of the spectra of pure H2BDC, L1, and L2 ligands, and reference to previous spectroscopic studies of H2BDC, triazoles, and pyrimidine compounds. Upon loading of C2H6 or C2H4, most PCP bands exhibited a significant change in intensity, as indicated by the gain characteristics in the difference spectrum. This suggests that structural expansion leads to stronger vibrational motions, particularly modes associated with phenyl, triazole, and pyrimidine ring deformation / torsion, and CH deformation.

[0057] In contractile structures, these modes may be more restricted. Close examination of the modes involving CN stretching on the triazole / pyrimidine ring by L1 and L2 linkers reveals a slight redshift, indicating CN bond elongation. Furthermore, v from the BDC linker... as A redshift was also observed in the (COO) mode, indicating the elongation of the Cu-OC bond. Figure 5 (b)). BDC at 1017 cm -1 The δ(CH) mode at this location is sensitive to structural opening / closing, showing a blue shift to 1022 cm⁻¹. -1 This is a typical value in open MIL structures, further demonstrating the expansion of the narrow neck defined by the CH group of the BDC linker. Gas adsorption data show that amination of the pyrimidine ring on the linker strongly affects gas absorption. Figure 4Therefore, it can be inferred that the guest C2H6 or C2H4 primarily interacts with the pyrimidine group. Notably, this inference is directly supported by the following observation: after C2H6 enters the NTU-101 structure, the 1063 cm⁻¹ region involving CH deformation on the pyrimidine ring... -1 The band ratio involves the 985 cm of CH deformation on the triazole ring. -1 The band is subject to greater perturbation (i.e., redshift). When C2H6 or C2H4 is loaded into the NTU-101-NH2 structure, v as,s The perturbations in the (NH2) mode further confirm this. Figure 5 (c)).

[0058] (5) Test of C2H6 / C2H4 separation performance of porous coordination polymers

[0059] A breakthrough experiment was performed to verify the separation performance of NTU-101 (293 K) and NTU-101-NH2 (328 K). The activated sample was loaded into the column and purged with He until the detection signal disappeared. Then, C2H6 / C2H4 (1 / 1, v / v, 2 mL·min) was used. -1 A gas mixture was introduced into the sample bed. In the case of the NTU-101, high-purity C2H4 first penetrated the sample bed, with a separation interval of 5.7 min·g. -1 ( Figure 6 (a) In contrast, NTU-101-NH2 not only showed a clear separation curve, but also a prolonged separation time, up to 9.5 min·g. -1 ( Figure 6 (b) Based on the flow rate and separation interval, the yield of high-purity C2H4 from NTU-101-NH2 was calculated to be 15.7 mL·g. -1 The separation yield is higher than that of the benchmark material (even at lower temperatures). Figure 6 (c)). To explore the effect of gas ratios, feed gases of 1 / 9 and 1 / 15 C2H6 / C2H4 (v / v, 2 mL·min) were also used. -1 Penetration experiments were conducted. In all cases, C2H4 eluted before C2H6. However, as the partial pressure of C2H6 became insufficient to induce a gradual absorption shift in the interpenetrating framework, the separation interval shortened. Furthermore, neither material showed a loss of retention time, indicating stable separation capabilities. Figure 6 (d)

Claims

1. A porous coordination polymer with an interpenetrating framework, characterized in that, The porous coordination polymer is a Cu-based coordination polymer with the chemical formula [Cu₂(BDC)₂L₂]. n (solvent) x BDC 2- The terephthalate ion is L2, which is 4,6-bis(1H-1,2,4-triazol-1-yl)pyrimidin-2-amine, where n is the number of repeating units and it belongs to the C2 / c space group; within the repeating unit, two Cu... 2+ Ions and BDC 2- The four carboxylate groups of the anion form paddlewheel-shaped Cu2(COO)4 nodes. The four Cu2(COO)4 nodes and the four BDC links form a square grid layer. The two vertices of the Cu2(COO)4 nodes coordinate with the N atom of the triazole group in L2 to construct a three-dimensional columnar pcu framework. The NH2 group then forms a single hydrogen bond with the adjacent framework.

2. The method for preparing the porous coordination polymer with interpenetrating framework as described in claim 1, characterized in that, It is obtained through a solvothermal reaction of ligand L2, ligand terephthalic acid, and metal salt.

3. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 2, characterized in that, The molar ratio of the ligand, metal salt and regulating ligand is 1:1.5~2:2.5~3.

4. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 2, characterized in that, The ligand is obtained by reacting 2-amino-4,6-dichloropyrimidine, 1,2,4-triazole, a base, and a catalyst in an organic solvent.

5. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 4, characterized in that, The base is potassium hydroxide or sodium hydroxide, the catalyst is tetrabutylammonium bromide, the organic solvent is acetonitrile, and the molar ratio of 2-amino-4,6-dichloropyrimidine, 1,2,4-triazole, base and catalyst is 1:2~3:2~3:0.1~0.

5.

6. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 2, characterized in that, The metal salt is Cu(NO3)2•2H2O, and the regulating ligand is terephthalic acid.

7. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 2, characterized in that, The solvent used in the reaction is a mixed solution of DMF and water in a volume ratio of 0.5~2:0.2~1.

5.

8. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 2, characterized in that, The reaction conditions are 80-100℃ for 24-72 h.

9. The method for preparing a porous coordination polymer with an interpenetrating framework according to claim 2, characterized in that, After the reaction was completed, the resulting porous coordination polymer was immersed in methanol for activation treatment.

10. The application of the porous coordination polymer with interpenetrating framework as described in claim 1, characterized in that, Used to separate C2H6 and C2H4.

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