A porous organic cage containing disulfide and hydrophobic bifunctional sites, preparation method thereof, and application in ethylene-ethane separation

Abstract

The present invention discloses a porous organic cage containing disulfide and hydrophobic bifunctional sites, a preparation method thereof, and an application in ethylene-ethane separation. This invention proposes for the first time to combine disulfide bonds with hydrophobic ligands to construct a porous organic cage with a variety of pore sizes for one-step purification of ethylene from an ethane-ethylene mixed gas. The introduction of disulfide bonds into the material enhances the weak interactions between organic cages, and these weak interactions effectively prevent the mutual blocking of pores between organic cages. The weak interactions between disulfide bonds and hydrophobic groups also make the resulting material present a variety of pore sizes, and these pores of different sizes have the ability to preferentially adsorb ethane. The invention uses 4,4'-diaminodiphenyl disulfide, tetraaldehyde intercyclic cup [4] aromatic hydrocarbons, organic solvents, etc. to obtain a porous organic cage with a variety of pore sizes. The resulting material has good thermal stability and can achieve preferential adsorption of ethane from an ethane-ethylene mixed gas to purify ethylene in one step.

Description

Technical Field

[0001] The present invention relates to the field of organic porous materials, and in particular to a porous organic cage containing a disulfide and hydrophobic bifunctional site, a preparation method thereof, and an application thereof in ethylene-ethane separation, especially in preferentially adsorbing ethane to purify ethylene in one step. Background Art

[0002] Separating olefins from alkanes is an important precursor step for industrial polymer manufacturing and is one of the chemical separation methods that has changed the world. Olefins are considered important industrial chemicals, and ethylene is one of the most important olefins, with annual production reaching 200 million tons in 2023. As an important raw material for the plastics industry, the purity of ethylene needs to reach more than 99.5%.

[0003] At present, in industry, ethylene and ethane are usually separated by steam cracking, which requires low temperature (-25℃) and high pressure (23Bar) conditions, resulting in a large amount of energy consumption. However, the energy consumption of ethylene purification can be reduced by 0.3-1.5GJ through non-thermal separation of adsorbents. Therefore, some porous materials, such as resins, activated carbons (ACs), zeolites, metal organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen bonded organic frameworks (HOFs), porous aromatic frameworks (PAFs) and porous organic cages (POCs) have been developed. However, most materials use ethylene adsorbed from ethane and ethylene mixed gas, and then desorb ethylene from the adsorbent to prepare high-purity ethylene. Although ethylene gas with a purity of 99.5% can be obtained by this method, the ethane gas in the ethane and ethylene mixed gas will be trapped in the gaps of the powder. Therefore, the trapped ethane gas molecules will inevitably be released during the desorption of ethylene. This undoubtedly increases the difficulty of the purification process.

[0004] Porous organic cages are hollow zero-dimensional cage-like molecular materials. They have attracted widespread attention in many fields due to their easy dissolution and film formation, and their pores are easy to functionalize. Flexible porous organic cage molecules can have both functionality and crystallinity, so researchers can more effectively explore the intrinsic relationship between structure and function, which makes porous organic cages stand out among porous materials. However, due to the lack of well-designed porous organic cage molecules, when they are stacked to form porous organic cage materials, they block each other's pores and collapse, making the design and synthesis of porous organic cages a difficult problem. How to prepare porous organic cages with good pore structure, high specific surface area and ethane selectivity is a challenging technical problem. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a porous organic cage material that can purify ethylene from ethane and ethylene mixed gas in one step. The present invention proposes for the first time to use disulfide bonds and hydrophobic groups as synergistic sites to construct pores of different sizes in the porous organic cage to solve the current problems of high energy consumption, cumbersome steps, low efficiency, and complex material synthesis in ethane and ethylene separation.

[0006] One of the purposes of the present invention is to provide a porous organic cage material, the synthesis path of which is as follows:

[0007]

[0008] Its structural formula is shown in formula (I).

[0009]

[0010] The BET specific surface area of ​​FPOC-10S is 1000m 2 g -1 The specific preparation steps are as follows:

[0011] Under heating conditions, 4,4'-diaminodiphenyl disulfide, tetraaldehyde inter-cyclocalix[4]arene and a reaction solvent are added to a reaction container, the mixed solution is mixed, the container is sealed and placed in an oven to react for a period of time, and the obtained precipitate is filtered, washed with a solvent, and dried to obtain the product FPOC-10S.

[0012] In the above preparation method, the molar ratio of 4,4'-diaminodiphenyl disulfide to tetraaldehyde intercyclic calix[4]arene is 4:1 to 1:1, preferably 2.5:1 to 1.5:1.

[0013] In the above preparation method, the reaction solvent is selected from one or more of toluene, N,N-dimethylformamide, m-xylene, o-xylene, p-xylene, and mesitylene.

[0014] In the above preparation method, the molar ratio of the ligand to the solvent is preferably: tetraaldehyde intercyclic calix[4]arene: 4,4'-diaminodiphenyl disulfide: solvent = 1: 1-3: 1.2-3,

[0015] In the above preparation method, the heating condition temperature is 80-150°C; the reaction time is 8-48h, preferably 12-24h.

[0016] In the above preparation method, the solvent required for the solvent washing is selected from one of methanol, ethanol, acetonitrile, petroleum ether, acetone, and dioxane, preferably methanol or ethanol.

[0017] In the above preparation method, the reaction container includes but is not limited to a glass bottle, a round-bottom flask or a pressure bottle.

[0018] In the above preparation method, the drying temperature is 50 to 150° C., and the drying time is 1 to 48 hours, preferably 12 to 24 hours.

[0019] The second object of the present invention is to provide a porous organic cage material with various pore sizes constructed by disulfide bond-containing amino ligands and hydrophobic group-containing aldehyde ligands for ethane-ethylene separation, specifically to purify ethylene in one step from an ethane-ethylene mixed gas by preferentially adsorbing ethane.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the present invention discloses a porous organic cage material with various pore sizes constructed by a disulfide bond-containing amino ligand and a hydrophobic group-containing aldehyde ligand for one-step purification of ethylene from an ethane-ethylene mixed gas. Compared with the reported ethylene purification adsorption materials, the porous organic cage designed in the present invention has various pore sizes to capture ethane, simple synthesis, good thermal stability, good hydrophobicity, simple ethylene purification process, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the PXRD pattern of FPOC-10S;

[0022] Figure 2 is the crystal structure of FPOC-10S observed along the a-axis;

[0023] Figure 3 is the nitrogen adsorption graph of FPOC-10S;

[0024] Figure 4 is the thermogravimetric image of FPOC-10S;

[0025] Figure 5 is the PXRD pattern of FPOC-10S at different temperatures;

[0026] Figure 6 This is the infrared spectrum of FPOC-10S;

[0027] Figure 7 This is the single component adsorption diagram of ethane and ethylene at 273K of FPOC-10S;

[0028] Figure 8 It is the penetration curve of FPOC-10S at 273K; DETAILED DESCRIPTION

[0029] The present invention will be described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are designated for further explanation of the present invention and are not to be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] Tetraaldehyde intercyclic calix[4]arene was synthesized according to the following route. The specific synthesis method is referenced to the literature J.Org.Chem.2013,78,11597-11601.

[0032]

[0033] 20 mg (0.047 mmol) of tetraaldehyde intercyclic calix[4]arene, 11.7 mg (0.094 mmol) of 4,4'-diaminodiphenyl disulfide and 6 ml of toluene were added to a 20 ml glass vial and the plastic cap was tightened. After ultrasonication for 0.5 h, the sealed glass vial was placed in a 100 ° C oven for reaction for 24 h. The obtained product was filtered and then solvent exchanged with methanol. After solvent exchange, the solid was filtered to obtain a solid, which was dried in a 100 ° C oven for 12 h to obtain the product FPOC-10S.

[0034] Figure 1 This is the PXRD pattern corresponding to the product FPOC-10S in Example 1. It can be seen from the figure that the prepared porous organic cage FPOC-10S has good crystallinity, and the PXRD pattern obtained in the experiment has a good correspondence with the XRD pattern obtained by analytical single crystal simulation. The results show that a porous organic cage FPOC-10S with good crystallinity can be prepared under this condition.

[0035] Figure 2 This is the single crystal structure corresponding to the product FPOC-10S of Example 1. It can be seen from the figure that FPOC-10S was successfully synthesized and the cage-like molecules were stacked to form two mutually penetrating pore structures.

[0036] Figure 3 The nitrogen adsorption diagram of the product FPOC-10S in Example 1 is shown in FIG. 1. As can be seen from the figure, FPOC-10S has a higher BET specific surface area (S BET =1016m 2 g -1 ). The above results also prove that the porous organic cage material can be prepared by a simple solvothermal method and obtain good performance, without the need for complex equipment and operations such as reactors, pyrex tubes and vacuum pumping required for the traditional solvothermal preparation of MOFs and POPs. And there is no need for the solvothermal / volatilization method required for the preparation of traditional POCs, which requires several weeks of evaporation to obtain the product (J.Am.Chem.Soc.2020,142,18060-18072), which greatly improves the preparation efficiency. The simple preparation method is conducive to promoting the practical application of this material.

[0037] Figure 4This is the thermogravimetric diagram corresponding to the product FPOC-10S of Example 1. It can be seen from the figure that FPOC-10S has excellent thermal stability and the thermal stability can reach 300°C.

[0038] Figure 5 This is the PXRD pattern of the product FPOC-10S in Example 1 at 30-150°C. The PXRD pattern of FPOC-10S does not change at different temperatures, indicating that the porous organic cage material can maintain its crystal structure at different temperatures.

[0039] Figure 6 This is the infrared spectrum corresponding to the product FPOC-10S in Example 1.

[0040] Table 1 is the structural crystal data table corresponding to the product FPOC-10S of Example 1.

[0041] Table 1

[0042]

[0043]

[0044] Embodiment 2:

[0045] Single component gas adsorption-desorption experiment

[0046] In order to test the adsorption and separation performance of the porous organic cage material synthesized in Example 1, single-component adsorption experiments of ethane and ethylene were carried out at 273K using the porous organic cage material in Example 1 as an adsorbent. 100 mg of the adsorbent was taken and the adsorption was set to 273K. The results are as follows: Figure 7 As shown. According to the test, at 273K and 1 bar, the adsorption capacity of ethane reaches 91.3cm 3 / g, and the adsorption capacity of ethylene is 75.6cm 3 / g is lower than the adsorption capacity of ethane by FPOC-10S under the same conditions, indicating that FPOC-10S is a porous organic cage material that preferentially adsorbs ethane.

[0047] Embodiment 3:

[0048] Through-column adsorption-desorption experiment

[0049] In order to test the actual separation effect of the porous organic cage material on ethane and ethylene, the above-mentioned Example 1 was used to synthesize

[0050] The adsorbent was used to conduct a breakthrough test of ethane and ethylene mixed gas. In this example, the ethane and ethylene mixed gas was adsorbed and separated, with a volume ratio of ethane / ethylene of 50:50 and a breakthrough temperature of 0°C. About 1g of FPOC-10S was placed in a quartz tube (6mm in diameter) to form a fixed bed. First, before the breakthrough test, the adsorbent bed was placed in a 10cm2 quartz tube at 100°C. 3 min -1 Helium

[0051] After cooling to 0°C, the gas flow was converted to the desired gas mixture at a specific flow rate. Here, a breakthrough experiment was performed with a binary (C2H6:C2H4=1:1) mixture at 0°C and 1 atm. The outlet gas composition was continuously monitored by a mass spectrometer (BSD-Mass), and the test curve was obtained by the software, see Figure 8 After testing, ethylene first penetrated this sample, indicating that FPOC-10S can purify ethylene in one step.

[0052] Embodiment 4:

[0053] 200 mg (0.47 mmol) of tetraaldehyde intercyclic calix[4]arene, 117 mg (0.94 mmol) of 4,4'-diaminodiphenyl disulfide and 60 ml of toluene were added to a 150 ml pressure bottle and the pressure bottle was sealed. After ultrasonic treatment for 1 hour, the sealed pressure bottle was placed in a 100°C oven for reaction for 24 hours. The obtained product was filtered and then solvent exchanged with methanol. After solvent exchange, a solid was obtained by filtration, and the solid was dried in a 100°C oven for 12 hours to obtain the product FPOC-10S.

[0054] Embodiment 5:

[0055] 2g (4.7mmol) of tetraaldehyde intercyclic calix[4]arene, 1.17g (9.4mmol) of 4,4'-diaminodiphenyl disulfide and 200ml of DMF (N,N-dimethylformamide) were added to a 350ml pressure bottle and the pressure bottle was sealed. After ultrasonic treatment for 1h, the sealed pressure bottle was placed in a 100℃ oven for reaction for 48h. The obtained product was filtered and then solvent exchanged with acetone. After solvent exchange, a solid was obtained by filtration, and the solid was dried in an 80℃ oven for 8h to obtain the product FPOC-10S.

[0056] Embodiment 6:

[0057] 1 g (4.7 mmol) of tetraaldehyde intercyclic calix[4]arene, 1.17 g (9.4 mmol) of 4,4'-diaminodiphenyl disulfide and 200 ml of toluene were added to a 350 ml pressure bottle and the pressure bottle was sealed. After ultrasonic treatment for 1 hour, the sealed pressure bottle was placed in a 120°C oven for reaction for 48 hours. The obtained product was filtered and then solvent exchanged with acetonitrile. After solvent exchange, a solid was obtained by filtration, and the solid was dried in a 90°C oven for 8 hours to obtain the product FPOC-10S.

[0058] Embodiment 7:

[0059] 400 mg (0.94 mmol) of tetraaldehyde intercyclic calix[4]arene, 292.5 mg (1.175 mmol) of 4,4'-diaminodiphenyl disulfide and 90 ml of toluene were added to a 150 ml pressure bottle and the pressure bottle was sealed. After ultrasonication for 0.5 h, the sealed pressure bottle was placed in a 120°C oven for reaction for 48 h. The obtained product was filtered and then solvent exchanged with ethanol. After solvent exchange, a solid was obtained by filtration, and the solid was dried in an 80°C oven for 12 h to obtain the product FPOC-10S.

[0060] The present invention designs and synthesizes a porous organic cage material with pores of various sizes. Compared with the reported ethane and ethylene separation materials, the porous organic cage material can achieve one-step purification of ethylene by preferentially adsorbing ethane. It also has the advantages of easy synthesis and good thermal stability. The porous organic cage material with pores of various sizes constructed by a disulfide bond amino ligand and a hydrophobic group-containing aldehyde ligand designed by the present invention has good application potential for ethane and ethylene separation.

Claims

1. A method for preparing a porous organic cage containing disulfide and hydrophobic bifunctional sites, wherein the synthesis steps are as follows: The structural formula of the product FPOC-10S is shown in formula (I).

2. The method for preparing a porous organic cage according to claim 1, characterized in that The following steps are involved: Under heating conditions, 4,4'-diaminodiphenyl disulfide, tetraaldehyde inter-cyclocalix[4]arene and a reaction solvent are added to a reaction container, the mixed solution is mixed evenly, the container is sealed and placed in an oven to react for a period of time, and the obtained precipitate is filtered, washed with a solvent, and dried to obtain the product FPOC-10S.

3. The method for preparing a porous organic cage according to claim 2, characterized in that: The molar ratio of tetraaldehyde intercyclic calix[4]arene, 4,4'-diaminodiphenyl disulfide and solvent is 1:1-5:1.2-5.

4. The method for preparing a porous organic cage according to claim 2, characterized in that: The reaction solvent includes, but is not limited to, one or more of toluene, N,N-dimethylformamide, m-xylene, o-xylene, p-xylene, and mesitylene.

5. The method for preparing a porous organic cage according to claim 2, characterized in that: The heating condition temperature is 80-150° C. and the reaction time is 8-48 hours.

6. The method for preparing a porous organic cage according to claim 2, characterized in that: The solvent required for the solvent washing includes, but is not limited to, one of methanol, ethanol, acetonitrile, petroleum ether, acetone, and dioxane.

7. The method for preparing a porous organic cage according to claim 2, characterized in that: The reaction container includes, but is not limited to, a glass bottle, a round-bottom flask or a pressure bottle.

8. The method for preparing a porous organic cage according to claim 2, characterized in that: The drying temperature is 50 to 150° C., and the drying time is 1 to 48 hours.

9. Use of the porous organic cage containing disulfide and hydrophobic bifunctional sites obtained by the method of any one of claims 1 to 8, characterized in that: Used for separation of ethane and ethylene, specifically, to purify ethylene from ethane and ethylene mixed gas in one step.

10. The use of the porous organic cage according to claim 9, characterized in that: After the ethane and ethylene mixed gas is adsorbed and separated, the porous organic cage material can be used again after activation. The specific steps of activation are: drying the adsorbed porous organic cage material at 50-150° C. for 0.5 h.

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