A supramolecular material with high adsorption and separation capacity of benzene and a preparation method and application thereof

Abstract

The application discloses a supramolecular material with high-efficiency adsorption and separation capacity for benzene, and a preparation method and application thereof, and the preparation process of the supramolecular material comprises the following steps: three ligands L-H, L-OCH3 and L-F are synthesized, and then are assembled with metal Zn (II) to synthesize novel metal-organic supramolecular cages T-H, T-OCH3 and T-F. The supramolecular cages exhibit unique selective adsorption characteristics for benzene molecules, and provide a novel solution for effective separation of benzene in a mixed system. The application not only opens up a brand-new path for designing benzene adsorption materials with high performance and high selectivity, but also plays a role in the high-efficiency separation of benzene and cyclohexane in the industrial chemical field, thereby improving production efficiency, and contributes important strength to promoting the progress and sustainable development of related industries.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of supramolecular materials, in particular to a supramolecular material with high adsorption and separation capacity for benzene and a preparation method and application thereof. BACKGROUND

[0002] Benzene, as a core raw material in the production of nylon, synthetic rubber, pesticides and medicines, its hydrogenated derivative cyclohexane is a key cornerstone for the production of nylon fibers. However, the traditional benzene separation process not only has huge energy consumption, but also has significant carbon footprint, which will cause impact on the environment. More worrying is that benzene, as a member of volatile organic compounds, has been classified as a human carcinogen, and its safe handling is particularly important. In the past research, porous materials and non-porous adaptive crystals have shown potential for effective capture and separation of benzene, but the complexity of operation and handling difficulty in practical application limits their widespread promotion. For a long time, non-porous amorphous solids have been marginalized due to their inferior performance compared to porous adsorbents, which greatly hinders their practical application in this field.

[0003] Metal-organic cages (MOCs) as a class of adsorbents with clear shape and size have shown great potential in the field of benzene adsorption. However, MOCs still face many challenges in practical application, such as limited adsorption capacity due to low combination rate, and easy to dissociate under high temperature or low concentration conditions, which seriously restricts their widespread application. In recent years, non-porous amorphous metal-organic supramolecular materials as a new type of adsorbent have gradually attracted attention. Their unique rigidity and multi-aromatic structure can form stable non-covalent bonds with benzene, such as [C-H··π] interactions and [π··π] stacking, providing strong driving force for efficient adsorption and separation of benzene. In addition, their internal cavities and cracks and channel structures provide more possibilities for the accommodation of guest molecules, further enhancing their adsorption performance. However, the non-porous amorphous metal-organic supramolecular materials with high adsorption capacity and high selectivity are still in the early stage of research and development, and their potential in practical application needs to be further explored.

[0004] Compared with traditional benzene purification technology, adsorption method has shown significant advantages in the capture and separation of benzene in mixtures due to its simplicity, speed, low energy consumption, safety and stability, and environmental protection. Therefore, the development and application of non-porous amorphous metal-organic cage materials with high adsorption capacity and high selectivity not only can break through the limitations of traditional benzene separation technology, but also can provide new possibilities for realizing environmentally friendly and efficient benzene separation and recovery. SUMMARY

[0005] In view of the problems in the prior art, the present application aims to provide a supramolecular material with high adsorption and separation capacity for benzene, a preparation method and application thereof in adsorption and separation of benzene, which uses new components, ratios and processes to prepare the supramolecular material T-H, T-OCH3 and T-F containing unsubstituted tpy-Zn 2+ -tpy groups, methoxy-modified tpy-Zn 2+ -tpy groups and fluorine-modified tpy-Zn 2+ The supramolecular material T-H, T-OCH3 and T-F containing unsubstituted tpy-Zn

[0006] The object of the present application is achieved by adopting the following technical solutions:

[0007] In a first aspect, the present application provides a supramolecular material with high adsorption and separation capacity for benzene, wherein the unit structure of the supramolecular material is shown in formula (I), formula (II) and formula (III):

[0008]

[0009] In a second aspect, the present application provides a preparation method of a supramolecular material with high adsorption and separation capacity for benzene, comprising the following steps:

[0010] (1) preparing three tripyridine metal organic ligands shown in formula (IV) to formula (VI):

[0011]

[0012] (2) adding a solvent to each of the three ligands prepared in step (1), dissolving, then adding a metal salt solution dropwise, heating and reacting, adding an anion replacement agent after the reaction is completed, and filtering to obtain a precipitate, thereby assembling and synthesizing the supramolecular material T-H, T-OCH3 and T-F containing unsubstituted tpy-Zn 2+ -tpy groups, methoxy-modified tpy-Zn 2+ -tpy groups and fluorine-modified tpy-Zn 2+ -tpy groups.

[0013] Preferably, the tripyridine metal organic ligand obtained in step (1) is a tri-arm tripyridine ligand, which has a unique geometric angle and configuration and can spontaneously assemble into a structure with precise, ordered and unique structure with metal Zn ions in a solution system.

[0014] Preferably, in step (2), the anion replacement agent is ammonium hexafluorophosphate. The anion introduced in the assembly process, such as nitrate or bis-trifluoromethanesulfonimide, is replaced by the anion replacement agent. Under the action of ammonium hexafluorophosphate, the supramolecular material can be better precipitated from the solvent, which is beneficial to the separation and purification of the subsequent precipitate.

[0015] Preferably, in step (2), the solvent is at least one of alcohol, chloroform, and ether.

[0016] More preferably, in step (2), the solvent is a mixture of alcohol and chloroform.

[0017] More preferably, in step (2), the solvent is a mixture of methanol and chloroform, and the volume ratio of methanol to chloroform is 2:1. The mixture of methanol and chloroform plays an important role in the formation of the supramolecular material. The trispyridine ligand has good solubility in the mixture of chloroform and methanol, and the generated supramolecular material can also be well dissolved in acetonitrile.

[0018] Preferably, in step (2), the heating reaction temperature is 40-70℃, and the reaction time is 5-10h.

[0019] More preferably, in step (2), the heating reaction temperature is 45-55℃, and the reaction time is 6-10h.

[0020] In a third aspect, the present application provides a supramolecular material with high adsorption and separation capacity for benzene, which is a supramolecular cage containing tpy-Zn 2+ The supramolecular cage containing tpy-Zn 2+ -tpy group can selectively adsorb and separate benzene in a mixed phase under an equimolar benzene and cyclohexane atmosphere.

[0021] Preferably, the tpy in the tpy-Zn 2+ -tpy group is unsubstituted, methoxy-substituted, and fluorine-substituted.

[0022] Preferably, the supramolecular material containing tpy-Zn 2+ -tpy group is T-H (formula (IV)), T-OCH3 (formula (V)), and T-F (formula (VI)).

[0023] Preferably, the application of the supramolecular material as an adsorption and separation of benzene and cyclohexane is that the supramolecular material can selectively adsorb and separate benzene in a mixed phase under an equimolar benzene and cyclohexane atmosphere.

[0024] Preferably, the supramolecular material can form non-covalent bonds with benzene, such as [C-H··π] interaction and [π··π] stacking, as the driving force for adsorption and separation.

[0025] Preferably, the supramolecular material has a high benzene adsorption capacity at 298K in a powder state, for example, the benzene adsorption capacity of the supramolecular material TF is 110cm 3 / g, supramolecular material TH: 120cm 3 / g, supramolecular material T-OCH3: 70cm 3 / g.

[0026] Preferably, the supramolecular material will not be completely released during the desorption process even under reduced pressure, and will still contain about 40 cm 3 / g of benzene, which shows that the storage of benzene in the supramolecular material is particularly stable.

[0027] Preferably, the powders of the supramolecular material TF and the supramolecular material TH have high selectivity when separating a benzene / cyclohexane mixture in a gas phase. The purity of the supramolecular material TF can reach 99.5%, and the purity of the supramolecular material TH can reach 93.83%.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention first provides an unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ The application of supramolecular materials TH, T-OCH3, and TF containing -tpy groups as adsorbents for efficient adsorption and separation of benzene, as well as the use of three differently modified ligands to coordinate with transition metal Zn to obtain unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ The preparation method of supramolecular materials TH, T-OCH3, and TF containing -tpy groups is discussed. Secondly, supramolecular materials can form non-covalent bonds such as [CH··π] interactions and [π··π] stacking with aromatic structures such as benzene, which serve as the driving force for adsorption and separation. These supramolecular materials have shown strong targeting in the adsorption and storage of benzene. Among them, the highest adsorption capacity of metal cage TH for benzene can reach 120cm 3 / g. It supplements the vacant state of the currently non-porous amorphous metal-organic cage with high adsorption capacity and selectivity, and realizes the efficient adsorption separation of benzene and cyclohexane.

[0030] 2. The present invention provides three kinds of unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+- tpy groups and fluorine-modified tpy-Zn 2+ The method of the supramolecular material T-H, T-OCH3, and T-F is constructed by self-assembly of modified different groups of terpyridine organic ligands and transition metal Zn through coordination bonds, and the structure is stable.

[0031] 3. The three supramolecular materials provided by the application, the adsorption and separation effects of the supramolecular materials containing different groups on benzene and cyclohexane are studied, and the excellent benzene adsorption capacity of the supramolecular material T-H is further highlighted.

[0032] 4. The supramolecular materials T-F and T-H provided by the application have high selectivity in separating benzene / cyclohexane mixtures in the gas phase. After separation, the purity of benzene reaches 99.5% and 93.83%, respectively, which provides a new idea for designing benzene adsorbents with high performance and high selectivity.

[0033] 5. The preparation method of the supramolecular material provided by the application is simple, and the reaction conditions are mild, which is conducive to large-scale industrial production. The desired supramolecular material can be assembled and synthesized by the reaction of a specific ligand with a metal salt solution and then adding an anion displacer.

[0034] 6. The supramolecular material provided by the application not only opens up a new path for designing high-performance and high-selectivity benzene adsorption materials, but also plays a role in the efficient separation of benzene and cyclohexane in the industrial chemical field, thereby improving production efficiency, and contributes important strength to the progress and sustainable development of related industries. BRIEF DESCRIPTION OF DRAWINGS

[0035] The application is further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the application. For ordinary skilled persons in the art, other drawings can be obtained without creative labor on the basis of the following drawings.

[0036] Figure 1 The flowchart for preparing the ligand L-OCH3 of the application;

[0037] Figure 2 The flowchart for preparing the ligand L-F of the application example 3;

[0038] Figure 3 The ESI-MS and TWIM-MS spectra of the supramolecular T-OCH3 of the application example 2;

[0039] Figure 4 The one-dimensional nuclear magnetic spectrum of the intermediate during the preparation of the ligand L-F of the application example 3;

[0040] Figure 5One-dimensional nuclear magnetic spectrum of the ligand L-F prepared for the present application embodiment 3;

[0041] Figure 6 One-dimensional nuclear magnetic spectrum of the supramolecular material T-F prepared for the present application embodiment 3;

[0042] Figure 7 ESI-MS and TWIM-MS spectra of the supramolecular T-F prepared for the present application embodiment 3;

[0043] Figure 8 Nitrogen adsorption-desorption spectra of the supramolecular T-H, T-OCH3 and T-F prepared for the present application embodiment 4;

[0044] Figure 9 XRD spectra of the supramolecular T-H, T-OCH3 and T-F prepared for the present application embodiment 4;

[0045] Figure 10 Adsorption-desorption spectra of benzene and cyclohexane of the supramolecular T-H, T-OCH3 and T-F prepared for the present application embodiments 1-3;

[0046] Figure 11 One-dimensional nuclear magnetic spectrum of the adsorption of benzene and cyclohexane of the supramolecular T-H, T-OCH3 and T-F prepared for the present application embodiments 1-3;

[0047] Figure 12 Adsorption amount change over time of the eutectic mixture steam of benzene and cyclohexane of the supramolecular T-H, T-OCH3 and T-F prepared for the present application embodiments 1-3;

[0048] Figure 13 Relative absorption amount of benzene and cyclohexane adsorbed in the material for 6 hours calculated by headspace gas chromatography of the supramolecular material T-H, T-OCH3 and T-F prepared for the present application embodiments 1-3

[0049] Figure 14 Cyclic test of benzene adsorption of the supramolecular material T-H prepared for the present application embodiment 1;

[0050] Figure 15 Cyclic test of benzene adsorption of the supramolecular material T-F prepared for the present application embodiment 3;

[0051] Figure 16 Crystal structure obtained in benzene and force analysis with benzene of the supramolecular material T-OCH3 and T-F prepared for the present application embodiments 2-3;

[0052] Figure 17 Crystal structure obtained in benzene and force analysis with benzene of the supramolecular material T-H prepared for the present application embodiment 1.

[0053] Figure 18 Adsorption of benzene on the supramolecular materials T-H, T-OCH3 or T-F prepared in Examples 1-3 of the present application. DETAILED DESCRIPTION

[0054] The technical solutions of the present application are described below by means of specific examples. It should be understood that the one or more method steps mentioned in the present application do not exclude the presence of other method steps before and after the mentioned combination steps or the insertion of other method steps between the explicitly mentioned steps; it should also be understood that the examples are only used to illustrate the present application and are not used to limit the scope of the present application. Moreover, unless otherwise specified, the numbering of the method steps is only a convenient tool for identifying the method steps and is not intended to limit the arrangement order of the method steps or to limit the scope of the present application, and the change or adjustment of the relative relationship, without substantial change of the technical content, is also considered as the scope of the present application.

[0055] In order to better understand the above technical solutions, the exemplary embodiments of the present application are described in more detail below. Although exemplary embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0056] The present application is further described below in conjunction with the following examples.

[0057] The three supramolecular materials T-H, T-OCH3 and T-F provided by the embodiments of the present application contain unsubstituted tpy-Zn 2+ tpy-Zn 2 + tpy-Zn 2+ The application of the three supramolecular materials T-H, T-OCH3 and T-F containing unsubstituted tpy-Zn 2+ tpy-Zn 2+ tpy-Zn 2+ tpy-Zn The three supramolecular materials T-H, T-OCH3 and T-F containing unsubstituted tpy-Zn

[0058]

[0059] The three supramolecular materials T-H, T-OCH3 and T-F containing unsubstituted tpy-Zn 2+- tpy group, methoxy modified tpy-Zn 2+ - tpy group and fluorine modified tpy-Zn 2+ - Supramolecular materials of tpy group, T-H, T-OCH3, T-F, the preparation methods are shown in Examples 1-3 respectively, wherein the synthesis method of ligand L-H and L-OCH3 is similar, the patent has been applied, L-F is described in Example 3. The combination of the above-mentioned materials and the following materials can form a supramolecular material with the following structure: Figures 1-17 The technical solutions of the present application are further described in combination with a plurality of specific embodiments.

[0060] Example 1:

[0061]

[0062] The preparation method of supramolecular T-H includes:

[0063] The ligand L-H (12 mg, 9.7 μmol) was dissolved in CHCl3(6 mL), MeOH (6 mL) was added, the solution was heated to 60°C, and Zn(NO3)2·6H2O (4.33 mg, 14.5 μmol) MeOH solution (1 mg / mL) was added without precipitate, and stirred at 55°C for 6 h. After the reaction was completed, it was cooled to room temperature, and anion exchange was carried out by adding 10 times excess NH4PF6 to form a precipitate, and stirred for 30 min. After the conversion was completed, the solution was transferred to a 15 mL centrifuge tube for centrifugation, the solid was retained and the supernatant was discarded, distilled water and a small amount of MeOH were added, the mixture was shaken thoroughly and centrifuged again, the above operation was repeated for 3 times, and the solid was vacuum dried to obtain the product (16.00 mg, 98.0%).

[0064] ESI-TOF (m / z): 864.53 [M-7PF6 - ] 7+ (calcd m / z: 1029.26), 1264.69 [M-5PF6 - ] 6+ (calcd m / z: 1264.69), 1616.35 [M-4PF6 - ] 5+ (calcd m / z: 1616.35), 2203.47 [M-3PF6 - ] 4+ (calcd m / z: 2203.47); - 3+ (calcd m / z: 2203.47); 1 H NMR (500 MHz, CD3OD) δ 8.87 (s, 18H, Tpy-H 3’5’ ​), 8.48 (d, J = 8.0 Hz, 18H, Tpy-H b ), 8.31 (d, J = 8.0 Hz, 18H, Tpy-H 3 ,3” ), 7.85 (t, 18H, Tpy-H 4,4” ), 7.77 (d, J = 8.0 Hz, 18H, Tpy-H a ), 7.69 (d, J = 5.0 Hz, 18H, Tpy-H 6,6” ), 7.55 (d, J = 8.0 Hz, 9H, Ph-H c ), 7.43 - 7.39 (m, 18H, Ph-H d,e ), 7.33 (d, J = 8.5 Hz, 9H, Ph-H f ), 7.17 - 7.13 (m, 18H, Tpy-H 5,5” ), 7.04 (s, 9H, Ph-H g )

[0065] Example 2:

[0066]

[0067] The method for preparing the supramolecular T-OCH3comprises:

[0068] The ligand L-OCH3(12 mg, 9.1 μmol) was dissolved in CHCl3(6 mL), MeOH (6 mL) was added, the solution was heated to 60 °C, and Zn(NO3)2·6H2O (4.06 mg, 13.6 μmol) in MeOH (12 mL) was added without precipitation, stirred for 8 hours, and then cooled to room temperature. Anion exchange was performed by adding a 10-fold excess of NH4PF6, and the precipitate was washed with water and methanol and centrifuged three times, and dried in a vacuum drying oven to obtain a solid product (12.5 mg, 95.2%).

[0069] ESI-TOF (m / z): 913.03 [M-7PF6 - ] 7+ (calcd m / z: 913.03), 1089.35 [M-6PF6 - ] 6+ (calcd m / z: 1089.35), 1336.21 [M-5PF6 - ] 5+ (calcd m / z: 1336.21), 1706.52 [M-4PF6 - ] 4+(calcd m / z: 1706.52), 2323.69 [M-3PF6 - ] 3+ (calcd m / z: 2323.69); 1 H NMR (500 MHz, CD3OD, 300 K, ppm) δ 8.9 (s, 24H, tpy-H 3’,5’ ), 8.50-8.48 (d, 24H, Ph-H a ), 8.36-8.34 (d, 24H, tpy-H 3 ,3” ), 7.89-7.86 (t, 24H, tpy-H 4,4” ), 7.79-7.77 (d, 24H, Ph-H b ), 7.27-7.25 (d, 12H, tpy-H 6 ,6” ), 7.19-7.17 (t, 24H, Ph-H d ), 7.07-7.06 (d, 12H, Ph-H 5,5” ), 7.01-6.99 (d, 24H, Ph-H c ), 6.91 (s, 24H, Ph-H c ), 3.82 (s, 36H, Ph-H f ).

[0070] Example 3:

[0071] The method for preparing the supramolecular T-F includes:

[0072] (1) Synthesis of intermediate 1:

[0073]

[0074] In a three-necked round bottom flask was added 2-bromo-5-fluoroacetophenone (1.00 g, 4.60 mmol) followed by dropwise addition of triflic acid (0.041 mL, 0.460 mmol) to the well stirred solution. The reaction was heated to 140 °C under a nitrogen atmosphere and stirred for 6 h. The black mixture was cooled to ambient temperature, quenched with water (20 mL) and the mixture extracted with CH2Cl2(3 x 20 mL). The combined organic layers were washed with brine (20 mL), dried over MgSO4, filtered and concentrated. The residue was purified by column chromatography on silica gel (n-hexane / ethyl acetate, 95:5) to give intermediate 1 as a yellow solid (0.50 g, 55%).

[0075] 1H NMR (500 MHz, CDC13) δ 7.65 (d, J = 5.0 Hz, 1H, Ph-H d ), 7.49 (s, 1H, Ph-H a ), 7.19 (d, J = 9.0 Hz, 1H, Ph-H d ), 6.98 (t, J = 8.0 Hz, 1H, Ph-H c ).

[0076] (2) Synthesis of Ligand L-F:

[0077]

[0078] A round bottom flask was charged with intermediate 1 (504 mg, 1.05 mmol) and p-phenylboronic acid terpyridine (1.59 g, 4.50 mmol), Pd(PPh3)2Cl2(123.3 mg, 0.15 mmol) and Na2C03(810 mg, 9.0 mmol), followed by 75 mL of toluene, 20 mL of water and 15 mL of t-butanol. The mixture was stirred at 85 °C for 3 days. After cooling to room temperature, the mixture was extracted with CH2Cl2and saturated brine and rotoevaporated, the red solid mixture was purified by dry column chromatography (silica gel) with CH2Cl2and recrystallized with CH3OH to give 932 mg of white solid product Ligand L-F (yield 73%). 1 H NMR (500 MHz, CDC13) δ 8.78 (s, 2H, tpy-H 3’,5’ ), 8.60 (d, J = 8.0 Hz, 2H, tpy-H 6.6” ), 8.54 (d, J = 5.0 Hz, 2H, tpy-H 3,3” ), 8.05 (d, J = 8.0 Hz, 2H, Ph-H a ), 7.80 (t, J = 8.0 Hz, 2H, tpy-H 4,4” ), 7.35 - 7.31 (m, 1H, Ph-H c ), 7.25 - 7.21 (m, 4H, tpy-H 5,5” , Ph-H b ), 6.96 (t, J = 9.5 Hz, 1H, Ph-H d ), 6.84 (s, 1H, Ph-H e ), 6.54 (d, J = 9.5 Hz, 1H, Ph-H f ).

[0079] (3) Synthesis of Supramolecule T-F:

[0080]

[0081] The ligand L-F (12 mg, 9.4 μmol) was dissolved in CHCl3(6 mL), MeOH (6 mL) was added, the solution was heated to 60 °C, and a 10-fold excess of NH4PF6was added for anion exchange. The precipitate was washed with water and methanol three times by centrifugation and oven dried in a vacuum oven to give the solid product (15.68 mg, 97.0 %). ESI-TOF (m / z): 892.37 [M-7PF6 - ] 7+ (calcd m / z: 892.37), 1065.27 [M-6PF6 - ] 6+ (calcd m / z: 1065.27), 1307.33 [M-5PF6 - ] 5+ (calcd m / z: 1307.33), 1670.41 [M-4PF6 - ] 4+ (calcd m / z: 1670.41), 2275.55 [M-3PF6 - ] 3+ (calcd m / z: 2275.55); 1 H NMR (500 MHz, CD3OD, 300 K, ppm) δ 8.88 (s, 2H, tpy-H 3’,5’ ), 8.49 (d, 2H, J = 9.0 Hz, tpy-H 3,3” ), 8.33 (d, 2H, J = 8.0 Hz, Ph-H a ), 7.86 (t, 2H, J = 8.0 Hz, tpy-H 4,4” ), 7.72 (d, 1H, J = 10.0 Hz, Ph-H e ), 7.68 (d, 2H, J = 6.0 Hz, tpy-H 6,6” ), 7.59 - 7.54 (m, 1H, Ph-H d ), 7.21 - 7.13 (m, 4H, tpy-H 5,5” , Ph-H b ), 7.11 (d, J = 8.7 Hz, Ph-H d ), 7.07 (s)

[0082] Experimental Example 4

[0083] The properties and applications of the supramolecular materials prepared in Examples 1-3 were tested and verified:

[0084] (1) Porosity, crystallinity, thermal stability and hydrophobicity of supramolecular materials:

[0085] Nitrogen adsorption studies were performed at 77 K to evaluate the porosity of the synthesized samples after evacuation at 120 °C under high vacuum for 24 h. A typical type III isotherm was obtained, and a low apparent Brunauer-Emmett-Teller surface area (SBET) of 13.98 m 2 / g(TF),11.49m 2 / g(TH) and 25.74m 2 / g(T-OCH3), indicating that there are no pores in the MOCs solid. Next, the solid samples of these supramolecular materials were subjected to powder X-ray diffraction (PXRD) analysis, and the results showed only a weak broadening signal, indicating that they have amorphous properties. In addition, the contact angle test also showed that the supramolecular materials have good hydrophobicity ( Figure 8 , Figure 9 ).

[0086] (2) Adsorption of benzene and cyclohexane

[0087] The specific adsorption and storage capacity of benzene and cyclohexane can be quantitatively analyzed by adsorption and desorption tests. At 298K saturated vapor pressure, the adsorption gravity values ​​of TF, TH and T-OCH3 for benzene are 110cm 3 / g、120cm 3 / g、70cm 3 / g. From Figure 10 It can be clearly seen that the adsorption capacity of the three for benzene is much greater than that for cyclohexane. The adsorption capacity of TF and TH for benzene is close to that of Carboxen1000 (a commercial carbon molecular sieve used for separating light hydrocarbons in gas chromatography columns and sampling volatile organic compounds in air analysis). This also shows that these supramolecular materials can be used as an adsorption material for both at standard temperature and pressure. And because they show a stronger storage capacity for benzene, this material is expected to play a role in the application of separating benzene and cyclohexane ( Figure 10 ).

[0088] In addition, the adsorption and storage capacity of benzene and cyclohexane at room temperature and pressure were investigated. The specific operation was as follows: 10 mg of sample was accurately weighed, ground in a mortar and evenly spread on the bottom of a 1.5 mL vial. The sample was activated under vacuum at 180 ° C for 6 hours to remove impurities in the adsorbent and make the adsorbent surface more active. After the activation was completed, 2 mL of cyclohexane and 1.86 mL of benzene (the amount of substance was 1:1) were added to a 20 mL large bottle, and the 1.5 mL vial containing the adsorbent sample after activation was placed in a 20 mL large bottle for 4 hours of adsorption. Through nuclear 1 HNMR characterizes the selective adsorption performance of the adsorbent for benzene. As can be seen from the figure, the nuclear magnetic resonance of MOCs before adsorption only has the peak of the metal organic cage itself, at 7.33ppm (benzene in CD3OD solvent). 1 HNMR peak position) and 1.45 ppm (cyclohexane in CD3OD solvent 1 There are no peaks at the HNMR peak position, and after adsorption, obvious peaks can be observed at 1.45ppm and 7.33ppm, indicating that the supramolecular material can be used as an adsorbent to capture both volatile organic compounds ( Figure 11 ). 1 HNMR experiments show that the adsorbent has the ability to capture both benzene and cyclohexane, but its storage capacity for benzene is stronger than that for cyclohexane, and it can be used as an adsorbent for selective adsorption and separation of benzene.

[0089] Further time-dependent solid-benzene vapor adsorption experiments were conducted. The adsorption saturation of the three supramolecular materials was reached at approximately 4.5 hours. The amount of benzene adsorbed can be calculated based on the integral ratio of the supramolecular material to the benzene molecule. Figure 12 As shown, when the saturation point is reached, the number of benzene molecules adsorbed by each supramolecular material is 27 (TF), 26 (TH) and 15 (T-OCH3), respectively.

[0090] (3) Separation of benzene and cyclohexane

[0091] GC experiments are mainly used to separate and quantitatively analyze complex mixtures of multiple components. The headspace injection method is used to test the sample. 20 mg of the sample after adsorption and desorption at room temperature and pressure is placed at the bottom of a 20 mL crimp-top headspace injection bottle. The sample is heated at 100 ° C for 10 minutes in the injector, and 1 mL of the headspace sample is set. The GC operation is: the oven is programmed to start at 50 ° C and the temperature is set at 10 ° C min -1 The internal temperature was raised to 200°C; the injection temperature was 250°C; the detector temperature was 280°C; the nitrogen, air, and supply flow rates were 35, 350, and 35 mL / min, respectively. -1 , helium (carrier gas) flow rate is 3.0 mL min -1The samples were injected in splitless mode (30:1). The results of the high performance gas chromatography (GC) experiments on benzene and cyclohexane were as follows: Figure 13 As shown in the figure, the integration with benzene (peak position: 6.18) and cyclohexane (peak position: 6.68) shows that the adsorbent has a stronger adsorption capacity for benzene, and the adsorption storage capacity of benzene accounts for 99.5%, 99.83% and 66.34% of the total, respectively, which is in good agreement with the adsorption isotherm ( Figure 13 In addition, after 5 cycles, the adsorption capacity of benzene by supramolecular materials TF and TH can still be maintained at a high level, which shows that the supramolecular material has a stable structure and can be used as a good adsorption material ( Figure 14 , Figure 15 ).

[0092] (4) Investigation of the binding sites of adsorbed benzene molecules in supramolecular materials

[0093] In order to understand the high adsorption performance and selectivity of supramolecular materials for benzene, the single crystal structures of benzene@TF, benzene@TH and benzene@T-OCH3 cocrystals were determined. The structural analysis of benzene@TF, benzene@TH and benzene@T-OCH3 showed completely different frameworks. In the benzene@TF framework, the benzene molecules cannot compete with the negatively charged PF6-s and interact with T-Fs through multiple CH...F hydrogen bonds and electrostatic interactions. In addition, various non-covalent interactions are formed, including π-π stacking (average ), CH---π interaction and CH-F hydrogen bonds ( As shown in the figure), TH forms a compact layered structure with negligible intermolecular channels, where two adjacent THs adopt a "head-to-head" mode. The adsorbed benzene molecules are trapped in the molecular gaps, and the main driving force comes from π-π stacking (average ) and CH---π interactions As for T-OCH3, only CH-π interactions were detected between the adsorbed benzene molecules and MOC, which reasonably explains the poor benzene adsorption capacity and separation selectivity of T-OCH3 ( Figure 16 , Figure 17 ).

[0094] The present invention first provides the application of three supramolecular materials TH, T-OCH3, and TF, which respectively contain unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+The tpy group is an adsorbent for efficient adsorption and separation of benzene. The application also introduces a method for preparing these supramolecular materials, i.e. by using three different modified ligands to coordinate with transition metal Zn to obtain T-H, T-OCH3 and T-F containing corresponding groups. In addition, these supramolecular materials can form non-covalent bonds with benzene, such as [C-H···π] interaction and [π···π] stacking, which are the main driving force for their adsorption and separation. In terms of benzene adsorption and storage, these supramolecular materials show strong specificity, especially the metal cage T-H, which has a maximum adsorption capacity of benzene of 120 cm 3 / g. The application fills the gap of non-porous amorphous metal-organic cages with high adsorption capacity and selectivity, and provides a new solution for efficient adsorption and separation of benzene and cyclohexane.

[0095] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0096] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. An application of a supramolecular material for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: The unit structure of the supramolecular material is shown in formula (I) and formula (II): 。 2. Use of a supramolecular material according to claim 1 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: The preparation method of the supramolecular material comprises the following steps: (1) Preparation of terpyridine metal organic ligands as shown in formula (IV) and formula (VI): ； (2) adding a solvent to the two ligands prepared in step (1) respectively to dissolve them, then dropping a metal salt solution and heating to react. After the reaction is completed, adding an anion displacer and filtering to obtain a precipitate, which can be assembled and synthesized to obtain supramolecular materials represented by formula (I) and formula (II).

3. Use of a supramolecular material according to claim 2 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: In step (2), the anion displacer is ammonium hexafluorophosphate.

4. Use of a supramolecular material according to claim 2 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: In step (2), the solvent is at least one of alcohol, chloroform and ether.

5. Use of a supramolecular material according to claim 4 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: In step (2), the solvent is a mixed solution of methanol and chloroform, wherein the volume ratio of methanol to chloroform is 2:

1.

6. Use of a supramolecular material according to claim 2 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: In step (2), the heating reaction temperature is 40-70°C, and the reaction time is 5-10 h.

7. Use of a supramolecular material according to claim 2 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: In step (2), the heating reaction temperature is 45-55°C, and the reaction time is 6-10 h.

8. Use of a supramolecular material according to claim 1 for selective adsorption and separation of benzene under equimolar conditions of benzene and cyclohexane, characterized in that: The adsorption capacity of the supramolecular material for benzene in powder state at 298 K is as follows: The benzene adsorption capacity of the supramolecular material shown in formula (II) is 110 cm 3 / g, the benzene adsorption capacity of the supramolecular material represented by formula (I) is 120cm 3 / g.

Images