Use of an ethyl pillar[5]arene-based co-crystal material in visualizing the adsorptive separation of a mixture of n-pentane and isoprene

Abstract

This invention discloses the application of a eutectic material based on ethyl column[5] aromatics in the visual adsorption separation of a mixture of n-pentane and isoprene. The macrocyclic eutectic material formed by ethyl column[5] aromatics and 3,5-dinitrobenzonitrile is used to selectively adsorb and separate n-pentane from a mixture of n-pentane and isoprene. During the adsorption and separation of n-pentane and isoprene, a visual color change is observed. The separation process does not require distillation, has low energy consumption, and is fast. The visible color change phenomenon during the adsorption of n-pentane provides visual monitoring of the separation process. Furthermore, the eutectic material used has high stability, can be recycled, and has stable separation performance.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials, and more specifically, to the application of a eutectic material based on ethyl column[5] aromatics in the visual adsorption separation of a mixture of n-pentane and isoprene. Background Technology

[0002] n-Pentane (n-PT) and isoprene (iso-PE) are two industrially valuable components in the C5 fraction of petrochemicals. n-Pentane is widely used in electronic component cleaning and cosmetics manufacturing, while isoprene, as a key monomer in the synthesis of isoprene rubber, resins, and various fine chemicals, holds an irreplaceable position in the polymer industry. In industrial production, both are typically derived from the C5 fraction, a byproduct of naphtha cracking to produce ethylene. Therefore, the resulting n-Pentane product often contains small amounts of isoprene, requiring deep purification to meet the purity requirements for industrial applications. However, due to the extremely close boiling points of n-Pentane (36.1℃) and isoprene (34.1℃) and their similar molecular structures, traditional distillation techniques are inefficient and energy-intensive in separating them.

[0003] Currently, industrial separation still relies heavily on complex processes such as extractive distillation and azeotropic distillation, which suffer from long processes and high operating costs. To overcome these technical bottlenecks, adsorption separation is considered a promising energy-saving alternative. Existing technologies have attempted to use porous adsorbents such as zeolite molecular sieves and metal-organic frameworks (MOFs) for the separation of C5 alkane / olefin mixtures, but challenges such as poor material stability, insufficient selectivity, or poor recyclability are still prevalent. More importantly, these methods are often difficult to monitor visually during the separation process. Therefore, developing a novel separation method that combines high selectivity, good stability, low energy consumption, and the ability to visualize and monitor the process is of significant practical importance for promoting the high-value utilization of C5 resources.

[0004] Patent CN1709842A discloses a method for separating and cracking C5 using a coupled azeotropic superdistillation and extractive distillation. This method first obtains isoprene and n-pentane azeotropes through azeotropic superdistillation, then separates them using extractive distillation. This process design alleviates solvent toxicity and polymerization inhibition problems to some extent, but the process is complex, involving multiple distillation operations, relying on a large energy input to achieve component separation, resulting in high energy costs. Patent CN102452888A discloses a method for purifying 1-hexene from Fischer-Tropsch synthetic oils. This method obtains the final product through a multi-step series operation of "fraction cutting - extractive distillation for deoxygenation - secondary extractive distillation for alkane and alkene separation - reactive distillation for tertiary olefin removal - liquid-liquid extraction for alcohol removal - precision distillation." Although the process design is systematic, its core shortcomings lie in the lengthy process, numerous operating units, and high dependence on energy-intensive separation technologies such as extractive distillation and precision distillation, leading to high overall energy consumption and operating costs. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects of the existing technology, especially the defects of existing n-pentane and isoprene separation technology such as high energy consumption, complex process, slow adsorption kinetics and inability to monitor adsorption state in real time. It provides an application of ethyl column [5] aromatic eutectic material in the visual adsorption separation of n-pentane and isoprene mixture. The macrocyclic eutectic material formed by ethyl column [5] aromatic and 3,5-dinitrobenzonitrile is used to selectively adsorb and separate n-pentane from the n-pentane and isoprene mixture. It can overcome the high energy consumption problem of traditional distillation and extractive distillation, as well as the disadvantages of poor selectivity and slow kinetics of existing adsorbents.

[0006] This invention further utilizes the visible color change of the macrocyclic eutectic material during the adsorption of n-pentane, providing a direct and rapid process indicator for the separation process. This characteristic allows operators to determine the adsorption progress and adsorption saturation point without relying on complex analytical equipment, thus achieving visualization of the separation process.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] Application of a co-crystal material based on ethyl column[5] aromatics in the visual adsorption separation of a mixture of n-pentane and isoprene, wherein the co-crystal material is a macrocyclic co-crystal material formed by a combination of an electron donor and an electron acceptor; the electron donor is ethyl column[5] aromatics; and the electron acceptor is 3,5-dinitrobenzonitrile; The structural formula of the ethyl columnar aromatic hydrocarbon [5] is as follows: ; The structural formula of the 3,5-dinitrobenzonitrile is: .

[0009] Optionally, the application includes: placing the eutectic material in a mixture of n-pentane and isoprene to selectively adsorb n-pentane, with a visible color change accompanying the adsorption and separation of n-pentane and isoprene, thereby achieving the separation of n-pentane and isoprene.

[0010] Optionally, the temperature for selective adsorption of n-pentane is 25°C.

[0011] Optionally, the mixture of n-pentane and isoprene is a mixed vapor of n-pentane and isoprene or a mixed solution of n-pentane and isoprene.

[0012] Optionally, the volume ratio of n-pentane to isoprene in the mixture of n-pentane and isoprene is 1:1.

[0013] Optionally, the application further includes: after selective adsorption of n-pentane, removing the mixture of n-pentane and isoprene from the surface of the eutectic material by vacuum heating; the vacuum heating temperature is 40°C.

[0014] Optionally, the application further includes: removing the n-pentane adsorbed and complexed by the eutectic material by vacuum heating desorption to regenerate the eutectic material; the temperature of the vacuum heating desorption is 70°C.

[0015] Optionally, the eutectic material is a monoclinic crystal system with space group P21 / c.

[0016] Optionally, the preparation method of the eutectic material includes: dissolving ethyl columnar aromatic hydrocarbon [5] and 3,5-dinitrobenzonitrile in dichloromethane solution, and evaporating and activating under vacuum to obtain the eutectic material.

[0017] Optionally, the preparation method includes: dissolving 30 mg of ethyl columnar aromatic hydrocarbon [5] and 14 mg of 3,5-dinitrobenzonitrile in 2 ml of dichloromethane solution at room temperature, and slowly evaporating at room temperature for 3 days, then filtering and collecting the precipitated red crystals, and obtaining pink eutectic material after vacuum activation.

[0018] Optionally, the vacuum activation temperature is 70°C; the vacuum activation time is 12 hours.

[0019] Based on the difference in molecular size between n-pentane and isoprene, the macrocyclic eutectic material formed by ethyl columnar aromatic hydrocarbons [5] and 3,5-dinitrobenzonitrile can form a host-guest complex with n-pentane in a stoichiometric ratio of 1:1. This host-guest complex gradually de-complexes upon heating, releasing the adsorbed n-pentane. Moreover, the macrocyclic eutectic material remains stable at 100°C, can be reused after the desorption process is completed, and its selectivity does not decrease.

[0020] Implementing the embodiments of the present invention will have the following beneficial effects: This invention uses a macrocyclic eutectic material formed by ethyl columnar aromatics [5] and 3,5-dinitrobenzonitrile to separate n-pentane with a purity of 99.05% from a mixture of n-pentane and isoprene, accompanied by a color change. Compared with the prior art, the separation process of this invention is simple to operate and has low equipment requirements; the separation process does not require distillation, has low energy consumption, and is fast; the visible color change that occurs when n-pentane is adsorbed provides visual monitoring of the separation process; the eutectic material used has high stability, can be recycled, and the separation effect will not decrease. Attached Figure Description

[0021] Figure 1 The 1H NMR spectrum of the ethyl columnar aromatic hydrocarbon obtained in Example 1 of this invention [5].

[0022] Figure 2 The above is the 1H NMR spectrum of the macrocyclic eutectic obtained in Example 1 of this invention.

[0023] Figure 3 This is a thermogravimetric curve of the macrocyclic eutectic obtained in Example 1 of the present invention.

[0024] Figure 4 The 1H NMR spectrum of the macrocyclic eutectic obtained by adsorbing n-pentane alone in Example 2 of this invention.

[0025] Figure 5 The 1H NMR spectrum of the macrocyclic eutectic obtained by adsorbing isoprene alone in Example 2 of this invention.

[0026] Figure 6 The 1H NMR spectrum of the macrocyclic eutectic obtained by adsorbing a mixture of n-pentane and isoprene vapors in Example 3 of this invention.

[0027] Figure 7 The PXRD data for the macrocyclic eutectic material of this invention after adsorption of a mixed vapor of n-pentane and isoprene are shown in the figures.

[0028] Figure 8 The headspace gas chromatography of the macrocyclic eutectic material of this invention after adsorption of a mixed vapor of n-pentane and isoprene is shown in the embodiment of the invention.

[0029] Figure 9 This is a schematic diagram illustrating the color changes of the macrocyclic eutectic material adsorbing n-pentane, isoprene, and a mixture of n-pentane and isoprene vapors, as described in an embodiment of the present invention.

[0030] Figure 10 The diagram shows the cyclic performance of the macrocyclic eutectic material of this invention for the adsorption of mixed vapors of n-pentane and isoprene. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0032] The inventors have conducted in-depth research on the selective adsorption separation of n-pentane and isoprene, and found that due to the small difference in boiling points between n-pentane and isoprene, a large amount of energy is consumed during azeotropic distillation and extractive distillation. The adsorbents reported for hydrocarbon separation (such as zeolite molecular sieves, metal-organic frameworks, etc.) often face problems such as insufficient adsorption selectivity, small difference in boiling points between n-pentane and isoprene, slow adsorption kinetics, and poor stability when applied to the n-pentane / isoprene system. Moreover, existing adsorbents generally lack intuitive indication functions during the adsorption process, and cannot achieve visualization of the adsorption process.

[0033] Therefore, the present invention obtained by the inventors based on these insights is as follows.

[0034] This invention discloses the application of a eutectic material based on ethyl columnar[5] aromatics in the visual adsorption separation of a mixture of n-pentane and isoprene. The eutectic material is a macrocyclic eutectic material formed by a combination of an electron donor and an electron acceptor; the electron donor is ethyl columnar[5] aromatics; and the electron acceptor is 3,5-dinitrobenzonitrile. The structural formula of the ethyl columnar aromatic hydrocarbon [5] is as follows: ; The structural formula of 3,5-dinitrobenzonitrile is: .

[0035] In one specific embodiment, the application includes: placing a eutectic material in a mixture of n-pentane and isoprene to selectively adsorb n-pentane, with a visible color change accompanying the adsorption and separation of n-pentane and isoprene, thereby achieving the separation of n-pentane and isoprene.

[0036] Specifically, during the adsorption process, the eutectic material undergoes a change in crystal form. Due to multiple non-covalent interactions, the n-pentane in the mixture forms a host-guest complex with the eutectic material, and the stoichiometric ratio of this host-guest complex is 1:1.

[0037] In one specific embodiment, the visual color change is specifically a change from pink to yellow.

[0038] In one specific embodiment, the temperature for selective adsorption of n-pentane is 25°C.

[0039] In one specific embodiment, the mixture of n-pentane and isoprene is a mixed vapor of n-pentane and isoprene or a mixed solution of n-pentane and isoprene.

[0040] In one specific embodiment, the volume ratio of n-pentane to isoprene in the mixture of n-pentane and isoprene is 1:1.

[0041] In one specific embodiment, the mixture of n-pentane and isoprene may be an azeotropic mixture of n-pentane and isoprene.

[0042] In one specific embodiment, the application further includes: after selective adsorption of n-pentane is completed, vacuum heating is used to remove the mixture of n-pentane and isoprene from the surface of the eutectic material.

[0043] In one specific embodiment, the vacuum heating temperature is 40°C. The host-guest complex formed at 40°C remains stable, while the surface mixture can be gradually removed, further improving the purity of the adsorbed and separated n-pentane.

[0044] In one specific embodiment, the vacuum heating time can be adjusted according to the sample volume.

[0045] In one specific embodiment, the application further includes: removing the n-pentane adsorbed and complexed by the eutectic material by vacuum heating desorption, thereby regenerating the eutectic material.

[0046] In one specific embodiment, the vacuum heating desorption temperature is 70°C. At this temperature, the formed host-guest complex is unstable, and the adsorbed n-pentane molecules are gradually released, while the macrocyclic eutectic material is stable, undergoing only a change in crystal form during desorption. After desorption, the eutectic material is regenerated and can be used again for the adsorption and separation of mixtures of n-pentane and isoprene for the next cycle.

[0047] In one specific embodiment, the vacuum heating desorption time can be adjusted according to the sample volume.

[0048] In one specific embodiment, the eutectic material is a monoclinic crystal system with space group P21 / c.

[0049] In one specific embodiment, the preparation method of the eutectic material includes: dissolving ethyl columnar aromatic hydrocarbon [5] and 3,5-dinitrobenzonitrile in dichloromethane solution, and evaporating and activating under vacuum to obtain the eutectic material.

[0050] In one specific embodiment, the preparation method includes: dissolving 30 mg of ethyl columnar aromatic hydrocarbon[5] and 14 mg of 3,5-dinitrobenzonitrile in 2 ml of dichloromethane solution at room temperature, and slowly evaporating at room temperature for 3 days, filtering and collecting the precipitated red crystals, and then activating them under vacuum to obtain pink eutectic material.

[0051] In one specific embodiment, the vacuum activation temperature is 70°C; the vacuum activation time is 12 hours.

[0052] The following are specific embodiments. Example 1 Ethyl columnar aromatic hydrocarbon [5] was prepared according to step (1) of Example 1 of patent CN120817848A and is denoted as EtP5.

[0053] Preparation of macrocyclic eutectic material based on ethyl columnar[5] aromatics: 30 mg of ethyl columnar[5] aromatics and 14 mg of 3,5-dinitrobenzonitrile were dissolved in 2 ml of dichloromethane solution at room temperature and slowly evaporated at room temperature for 3 days. The precipitated red crystals were collected by filtration and activated under vacuum at 70°C for 12 h to obtain pink eutectic material, denoted as EtP5-DNB.

[0054] The structural formula of ethyl columnar aromatic hydrocarbons [5] is: ; The structural formula of 3,5-dinitrobenzonitrile is: .

[0055] The characterization data of the product prepared in this embodiment are as follows: EtP5, 1 H NMR (400 MHz, CDCl3, 298 K, ppm) δ 6.72 (s, 10H), 3.85-3.77 (m, 30H), 1.25 (t, 30H).

[0056] EtP5-DNB, 1 H NMR (400 MHz, CDCl3, 298 K, ppm) δ 9.28 (s, 2H), 8.84 (d,4H), 6.72 (s, 10H), 3.85-3.76 (m, 30H), 1.26 (t, 30H).

[0057] Powder X-ray diffraction (PXRD) results are as follows Figure 7 As shown, the macrocyclic eutectic material formed by the obtained ethyl columnar aromatic hydrocarbon [5] and 3,5-dinitrobenzonitrile has good crystallinity.

[0058] Example 2 Adsorption of macrocyclic eutectic materials for n-pentane or isoprene alone: ​​Take two 20 mL culture bottles, add 1 mL of n-pentane and 1 mL of isoprene to each, and name them as follows: n -PT@EtP5-DNB and iso-PE@EtP5-DNB. Take 20 mg of the macrocyclic eutectic material prepared in Example 1 and place it in two 5 mL open-top culture bottles. Place the two 5 mL open-top culture bottles in two 20 mL culture bottles. Seal the 20 mL culture bottles and place them in a 25 °C water bath for 10 min. The color of the eutectic material placed in n-pentane vapor changes from pink to yellow, while the eutectic material placed in isoprene vapor does not change color. The macrocyclic eutectic material adsorbed with n-pentane is heated under vacuum at 40 °C to remove the adsorbed n-pentane.

[0059] The characterization data of the product prepared in this embodiment are as follows: n -PT@EtP5-DNB, 1 H NMR (400 MHz, CDCl3, 298 K, ppm) δ 9.27 (t, 2H), 8.84(d, 4H), 6.72 (s, 10H), 3.85-3.76 (m, 30H), 1.32-1.29 (m, 6H), 1.26 (t, 30H),0.88 (t, 6H).

[0060] iso -PE@EtP5-DNB, 1 H NMR (400 MHz, CDCl3, 298 K, ppm) δ 9.27 (t, 2H), 8.84 (d, 4H), 6.71 (s, 10H), 3.85-3.76 (m, 30H), 1.26 (t, 30H).

[0061] 1 1H NMR results showed that the macrocyclic eutectic material had a significant adsorption effect on n-pentane, but no adsorption effect on isoprene.

[0062] PXRD test results are as follows Figure 7 As shown, compared to the PXRD spectrum of the initially activated macrocyclic eutectic material, the PXRD spectrum of the macrocyclic eutectic material placed in n-pentane vapor for a period of time changed, indicating that its unit cell parameters had changed, meaning that n-pentane had been adsorbed into the eutectic material; the spectrum of the macrocyclic eutectic material placed in isoprene vapor for a period of time changed very little, indicating that its unit cell parameters hardly changed, meaning that the macrocyclic eutectic material has no adsorption capacity for isoprene.

[0063] Example 3 Macrocyclic eutectic materials for 1:1 ratio of n-pentane and isoprene v : vAdsorption of mixed vapors: Take a 20 mL culture bottle, add 1 mL of n-pentane and 1 mL of isoprene, and name it... n -PT / iso -PE@EtP5-DNB. Take 20 mg of the macrocyclic eutectic material prepared in Example 1 and place it in a 5 mL open-top culture bottle. Place the open-top 5 mL culture bottle in the above 20 mL culture bottle and seal the 20 mL culture bottle. Place it in a 25 ℃ water bath for 10 min. The color of the eutectic material changes from pink to yellow. Heat the adsorbed macrocyclic eutectic material under vacuum at 40 ℃ to remove the adsorbed n-pentane.

[0064] The characterization data of the product prepared in this embodiment are as follows: n -PT / iso -PE@EtP5-DNB, 1 H NMR (400 MHz, CDCl3, 298 K, ppm) δ 9.27 (t,2H), 8.84 (d, 4H), 6.72 (s, 10H), 3.85-3.76 (m, 30H), 1.32-1.28 (m, 6H), 1.25(t, 30H), 0.88 (t, 6H).

[0065] exist 1 The H NMR spectrum only showed the signal of hydrogen atoms corresponding to n-pentane, indicating that the macrocyclic eutectic material can selectively adsorb n-pentane from the mixture of n-pentane and isoprene.

[0066] PXRD test results are as follows Figure 7 As shown, compared with the PXRD spectrum of the initially activated macrocyclic eutectic material, the PXRD spectrum of the macrocyclic eutectic material placed in the mixture of n-pentane and isoprene for a period of time changed, and the spectrum change was very similar to the PXRD spectrum of the macrocyclic eutectic material adsorbing n-pentane vapor alone. This indicates that the macrocyclic eutectic material can selectively adsorb n-pentane from the mixture of n-pentane and isoprene.

[0067] The results of headspace gas chromatography are as follows Figure 8 As shown, the results indicate that the macrocyclic eutectic material can selectively adsorb n-pentane with a selectivity of 99.05%.

[0068] Example 4 Regeneration of macrocyclic eutectic material: 20 mg of macrocyclic eutectic material saturated with n-pentane adsorbed was heated in a vacuum oven at 70 °C for 2 h to obtain regenerated macrocyclic eutectic material. 20 mg of the regenerated macrocyclic eutectic material was then repeated in Example 3. Figure 9 As shown, its selectivity did not decrease after being used 5 times.

[0069] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An application of a eutectic material based on ethyl column[5] aromatics in the visual adsorption separation of a mixture of n-pentane and isoprene, characterized in that, The eutectic material is a macrocyclic eutectic material formed by a combination of electron donor and electron acceptor; The electron donor is an ethyl columnar[5] aromatic hydrocarbon; the electron acceptor is 3,5-dinitrobenzonitrile; The structural formula of the ethyl columnar aromatic hydrocarbon [5] is as follows: 。 2. The application according to claim 1, characterized in that, The application includes: placing the eutectic material in a mixture of n-pentane and isoprene to selectively adsorb n-pentane, with a visible color change accompanying the adsorption and separation of n-pentane and isoprene, thereby achieving the separation of n-pentane and isoprene.

3. The application according to claim 2, characterized in that, The temperature at which n-pentane is selectively adsorbed is 25°C; The mixture of n-pentane and isoprene is a mixed vapor of n-pentane and isoprene or a mixed solution of n-pentane and isoprene; The volume ratio of n-pentane to isoprene in the mixture of n-pentane and isoprene is 1:

1.

4. The application according to claim 1, characterized in that, The application also includes: after selective adsorption of n-pentane, removing the mixture of n-pentane and isoprene from the surface of the eutectic material by vacuum heating; the vacuum heating temperature is 40°C.

5. The application according to claim 1, characterized in that, The application also includes: removing the n-pentane adsorbed and complexed by the eutectic material by vacuum heating desorption, thereby regenerating the eutectic material; the temperature of the vacuum heating desorption is 70°C.

6. The application according to claim 1, characterized in that, The eutectic material is a monoclinic crystal system with space group P21 / c.

7. The application according to claim 1, characterized in that, The preparation method of the eutectic material includes: dissolving ethyl columnar aromatic hydrocarbon [5] and 3,5-dinitrobenzonitrile in dichloromethane solution, and evaporating and activating under vacuum to obtain the eutectic material.

8. The application according to claim 7, characterized in that, The preparation method includes: dissolving 30 mg of ethyl columnar aromatic hydrocarbon [5] and 14 mg of 3,5-dinitrobenzonitrile in 2 ml of dichloromethane solution at room temperature, and slowly evaporating at room temperature for 3 days, then filtering and collecting the precipitated crystals and activating them under vacuum to obtain the eutectic material.

9. The application according to claim 7, characterized in that, The vacuum activation temperature is 70°C; the vacuum activation time is 12 hours.

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