A method of adsorptive separation of propylene and propane

Abstract

The present application relates to a kind of methods for adsorbing and separating propylene and propane, which includes the adsorption separation of propylene and propane with metal organic framework, wherein the metal organic framework material is formed by the coordination assembly of divalent metal ion, malic acid and pillar supporting ligand.The metal organic framework material involved in the present application is stable in structure and performance, has high adsorption capacity for propylene, can realize the efficient thermodynamic-kinetic synergistic separation of propylene and propane, and the adsorption performance remains the original effect after repeated adsorption-regeneration multiple times.The performance in the adsorption separation of propylene and propane is far superior to most solid adsorbents.

Description

Technical Field

[0001] This invention relates to the field of adsorption separation materials technology, and specifically to a method for adsorbing and separating propylene and propane. Technical Background

[0002] Propylene is an important chemical raw material in the petrochemical industry and a basic raw material for the three major synthetic materials (plastics, synthetic fibers, and synthetic rubber). In recent years, global consumption and demand for propylene have been increasing year by year. However, the propylene production process involves a large amount of propane impurities, and removing propane impurities from propylene is a key step in obtaining high-purity propylene. Propylene and propane have boiling points that differ by only 5.3 K and a relative volatility of only 1.14; therefore, the traditional distillation separation process currently relied upon requires a large number of theoretical plates and consumes a lot of energy.

[0003] Adsorption separation technology has low equipment requirements, does not involve phase change, and achieves gas separation through contact between the adsorbent and the mixed gas, making it more energy-efficient and effective. However, propylene and propane have extremely similar structures, sizes, polarizabilities, and molecular polarities, and most adsorbent materials generally exhibit low adsorption separation selectivity.

[0004] Cadiau et al. invented a pillared metal-organic framework material, NbOFFIVE-1-Ni, to achieve molecular sieve separation of propylene and propane (Science, 2016, 353(6295):137.). Although their separation selectivity is high, their slow diffusion rate limits their practical application potential. Chinese invention patent CN111747818A discloses a modified molecular sieve using imidazole compounds to achieve the adsorption separation of propylene and propane. However, this material requires ion exchange followed by post-modification, making the preparation process cumbersome. It also exhibits low selectivity for propylene and propane and a low adsorption capacity for propylene. The adsorption capacities of the metal-organic framework material Cu-BTC for propylene and propane are 7.7 mmol / g and 7.1 mmol / g, respectively, with an adsorption capacity ratio of only 1.08, indicating poor separation selectivity (Micropor. Mesopor. Mat., 2008, 151, 585.). Jing Li et al. applied the imidazole-based metal-organic framework material ZIF-8 to the adsorption and separation of propylene and propane (J. Am. Chem. Soc., 2009, 131, 10368–10369). This material exhibited a kinetic selectivity for propylene and propane exceeding 100, but its adsorption capacity for propylene and propane was almost equal, indicating poor thermodynamic selectivity, which limited its separation efficiency. Therefore, developing more stable adsorbent materials that possess both thermodynamic and kinetic selectivity for propylene and propane is more promising for industrial applications. Summary of the Invention

[0005] To address the shortcomings in this field, the present invention provides a method for adsorption separation of propylene and propane. This method simultaneously employs metal-organic framework materials based on R-malic acid (also known as D-malic acid) and S-malic acid (also known as L-malic acid), particularly racemic malic acid, to achieve efficient thermodynamic-kinetic synergistic separation of propylene and propane.

[0006] Specifically, the present invention provides a method for adsorption separation of propylene and propane, the method comprising contacting a mixed gas containing propylene and propane with a metal-organic framework material for adsorption separation, wherein the organic ligands of the metal-organic framework material include R-malic acid and S-malic acid.

[0007] In some embodiments, the molar ratio of R-malic acid to S-malic acid is (20-80):(80-20), preferably (40-60):(60-40), and more preferably 50:50. In some specific embodiments, the molar ratio of R-malic acid to S-malic acid is 20:80, 30:70, 40:60, 55:45, 50:50, 45:55, 60:40, 70:30, 80:20, or any value between them.

[0008] In some embodiments, the organic ligand of the metal-organic framework material is selected from racemic malic acid (also known as RS-malic acid or DL-malic acid).

[0009] In some embodiments, the metal ions of the metal-organic framework material are selected from divalent metal ions, preferably one or more of nickel ions and cobalt ions.

[0010] In some embodiments, the pillar-supporting ligand of the metal-organic framework material is selected from one or more of 4,4-bipyridine, 1,2-di(4-pyridyl)ethylene or meso-α,β-di(4-pyridyl)ethylene glycol, preferably selected from 4,4'-bipyridine.

[0011] In this invention, the metal-organic framework material is formed by coordination assembly of divalent metal ions, malic acid, and pillared ligands, wherein the malic acid includes both R-malic acid and S-malic acid.

[0012] In some embodiments, the microporosity of the metal-organic framework material is >95%, more preferably 100%.

[0013] In some embodiments, the pore size of the metal-organic framework material is Preferred

[0014] In some embodiments, the pore volume of the metal-organic framework material is 0.10-0.20 cm³. 3 / g, preferably 0.12-0.18cm 3 / g.

[0015] In some embodiments, the metal-organic framework material has a specific surface area of ​​250 m². 2 / g-600m 2 / g, preferably 250m 2 / g-500m 2 / g.

[0016] In some embodiments, the metal-organic framework material has a shape including one or more of spherical, cubic, granular, or membrane forms.

[0017] In some embodiments, the metal-organic framework material is prepared by a method comprising the steps of subjecting a mixture of malic acid, a metal inorganic salt, and a pillared ligand to a hydrothermal reaction in a solvent.

[0018] In some embodiments, the metal-organic framework material is prepared by a method comprising the following steps:

[0019] S1: Dissolve the organic ligand, metal salt and pillared ligand in a methanol-water mixture to obtain a solution;

[0020] S2: React the solution under high temperature conditions to obtain reaction crystals;

[0021] S3: Purify and dry the reaction crystals to obtain the metal-organic framework material.

[0022] In some embodiments, the inorganic metal salt is selected from one or more of the following metal ions: chloride, nitrate, acetate, carbonate, sulfate, or perchlorate, preferably acetate; preferably, the metal ion is selected from divalent metal ions, and more preferably from one or more of nickel and cobalt ions.

[0023] In some embodiments, the solvent comprises an organic solvent and water, wherein the organic solvent is selected from one or more of methanol, ethanol, acetonitrile, acetone, N,N-dimethylformamide or N,N-dimethylacetamide, preferably methanol.

[0024] In some embodiments, the molar ratio of malic acid to the metal inorganic salt and pillared ligand is (1-3):(1-3):1, preferably (1.5-2.5):(1.5-2.5):1. In some specific embodiments, the molar ratio of malic acid to the metal inorganic salt and pillared ligand is 2:2:1.

[0025] In some embodiments, the volume ratio of the organic solvent to water in the solvent is 1:(0.1-5), preferably 1:(1-2). In some embodiments, the volume ratio of the organic solvent to water in the solvent is 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, or any value between them.

[0026] In some embodiments, the temperature of the hydrothermal reaction is 100°C to 180°C, preferably 140°C to 170°C. In some specific embodiments, the temperature of the hydrothermal reaction is 100°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, or any value between them.

[0027] In some embodiments, the hydrothermal reaction time is from 12 hours to 96 hours, preferably from 48 hours to 72 hours. In some specific embodiments, the hydrothermal reaction time is 12 hours, 24 hours, 36 hours, 48 ​​hours, 60 hours, 72 hours, 84 hours, 96 hours, or any value between them.

[0028] In some embodiments, the method further includes washing and / or drying the products of the hydrothermal reaction.

[0029] In some embodiments, the washing includes washing with water and anhydrous ethanol in sequence.

[0030] In some embodiments, the drying temperature is between 30°C and 120°C. In some specific embodiments, the hydrothermal reaction temperature is 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any value between them.

[0031] In some embodiments, the drying time is 6 to 24 hours. In some specific embodiments, the drying time is 6 hours, 10 hours, 14 hours, 18 hours, 22 hours, 24 hours, or any value between them.

[0032] In some embodiments, the adsorption separation temperature is from -5°C to 50°C. In some embodiments, the adsorption separation temperature is -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and any value between them. In some embodiments, the adsorption separation temperature is from 10°C to 30°C.

[0033] In some embodiments, the total pressure of the mixture containing propylene and propane in the adsorption separation is from 100 kPa to 5000 kPa. In some embodiments, the total pressure of the mixture containing propylene and propane in the adsorption separation is from 100 kPa to 3000 kPa. In some embodiments, the total pressure of the mixture in the adsorption separation is from 100 kPa to 1000 kPa. In some embodiments, the total pressure of the mixture is 200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa, 700 kPa, 800 kPa, 900 kPa, and any value between them.

[0034] In some embodiments, the adsorption separation is carried out in a fixed-bed temperature swing or pressure swing adsorption device or a simulated moving-bed adsorption device.

[0035] The metal-organic framework material of this invention is prepared by using inexpensive and readily available malic acid as the organic ligand, which undergoes a hydrothermal reaction with a series of metal inorganic salts and pillared ligands. The raw materials used in the preparation are inexpensive, the synthesis conditions are mild, the operation is simple, post-processing is easy, and the material synthesis cost is low. In the method of this invention, the metal-organic framework material exhibits high adsorption and separation selectivity for propylene-propane mixtures, and the material structure and adsorption performance are stable, with good water stability, showing promising prospects for industrial application.

[0036] The metal-organic framework material used in this invention can be regenerated after adsorption saturation by heating to 50-150°C under an inert atmosphere such as vacuum or nitrogen for 2-10 hours. Excessive temperature or time will damage the adsorbent structure; excessively low temperature or short time will prevent the complete removal of residual adsorbate.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] The malic acid and pillared ligands used in the preparation of the metal-organic framework materials involved in this invention are widely available and inexpensive. The preparation method of the metal-organic framework materials involved in this invention is simple, and the structures and properties are stable. They exhibit high adsorption capacity for propylene and can achieve highly efficient thermodynamic-kinetic synergistic separation of propylene and propane. Furthermore, the adsorption performance remains unchanged after repeated adsorption-regeneration cycles. Their performance in the adsorption and separation of propylene and propane is far superior to most solid adsorbents. Attached Figure Description

[0039] Figure 1 A schematic diagram illustrating the adsorption principle of propylene and propane by the metal-organic framework material of the present invention is shown.

[0040] Figure 2The adsorption isotherms of propylene and propane by the metal-organic framework material in Example 1 are shown.

[0041] Figure 3 The kinetic adsorption curves of propylene and propane for the metal-organic framework material in Example 1 are shown.

[0042] Figure 4 The fixed-bed breakthrough curves of the metal-organic framework material in Example 1 for a propylene and propane mixture (50 / 50, volume ratio) are shown.

[0043] Figure 5 The fixed-bed breakthrough curves of the metal-organic framework material in Example 1 for a mixture of propylene and propane (95 / 5, volume ratio) are shown. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure.

[0045] According to the present invention, the method for adsorption separation of propylene and propane includes adsorption separation of propylene and propane using a metal-organic framework material based on R-malic acid and S-malic acid. The metal-organic framework material is formed by coordination assembly of divalent metal ions, malic acid, and pillared ligands, wherein the malic acid includes both R-malic acid and S-malic acid. If the malic acid contains only R-malic acid or S-malic acid, effective separation of propylene and propane cannot be achieved. See [link to previous section]. Figure 1 .

[0046] In this invention, the metal-organic framework material is prepared by a method comprising the following steps: dissolving a metal inorganic salt (also known as a metal salt or inorganic salt), a malic acid organic ligand, and a pillared ligand in a molar ratio of (1-3):(1-3):1, for example, 2:2:1, in a methanol / water (volume ratio 1 / 1) mixture; stirring to dissolve the solution; and then placing the solution into an atmospheric or high-pressure reactor for hydrothermal reaction; wherein the inorganic salt is a chloride, nitrate, acetate, carbonate, sulfate, or perchlorate of a metal ion; the pillared ligand is 4,4'-bipyridine, pyrazine, or other organic molecules with dual coordination sites; the metal ion is zinc, iron, cobalt, nickel, copper, manganese, calcium, or magnesium ions; the hydrothermal reaction temperature is 100-180℃, and the reaction time is 12-96 h; after the hydrothermal reaction, the material is washed sequentially with deionized water and anhydrous ethanol, and then vacuum dried to obtain the final product; the vacuum drying temperature is 30-120℃, and the drying time is 6-24 h.

[0047] The present invention will be further illustrated below by means of embodiments. However, it should be noted that the scope of protection of the present invention is not limited by these embodiments, but is determined by the claims.

[0048] It should be noted that the two or more aspects (or embodiments) disclosed in the context of this specification can be arbitrarily combined with each other, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0049] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0050] Example 1

[0051] 2.0 mmol nickel acetate tetrahydrate, 2.0 mmol RS-malic acid (racemic malic acid), and 1.0 mmol 4,4'-bipyridine were dissolved in 20 mL of a methanol / water mixture (2 / 1 v / v). The mixture was stirred thoroughly and placed in a 50 mL hydrothermal reactor, which was then heated to 160 °C for 72 hours. After the reaction was complete, the reactor was cooled, and the resulting solid was washed repeatedly with deionized water and anhydrous ethanol to obtain the purified metal-organic framework material. The pore size of this material is [insert pore size here]. The pore volume is 0.13 cm. 3 / g, BET specific surface area is 380m² 2 / g, with a microporosity of 100%. The purified adsorbent was degassed under vacuum at 120℃ for 24 hours to obtain a solvent-free adsorbent, which was then subjected to gas adsorption.

[0052] To test the adsorption performance of the metal-organic framework material prepared in this embodiment, single-component adsorption experiments of propylene and propane were conducted using the aforementioned metal-organic framework material as an adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The adsorption isotherm is shown below. Figure 2 As shown, the results indicate that, at 25 °C and 1 bar, the adsorption capacity of propylene reached 1.92 mmol / g, while the adsorption capacity of propane was 1.21 mmol / g. The Henry coefficient selectivity reached 5.86.

[0053] To test the kinetic adsorption performance of the metal-organic framework material prepared in this embodiment for propylene and propane, single-component kinetic adsorption experiments were conducted using the aforementioned metal-organic framework material as the adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The kinetic adsorption curves are shown below. Figure 3As shown, the results indicate that, at 25℃ and 100 kPa, propylene reaches adsorption equilibrium in 50 minutes, while propane reaches adsorption equilibrium in 4500 minutes. Calculations based on the diffusion coefficient show that the adsorbent exhibits a high kinetic adsorption selectivity of 114.2 for propylene and propane. Its combined thermodynamic-kinetic selectivity (the product of the square root of the Henry coefficient and the kinetic selectivity) is 62.6.

[0054] To test the actual performance of the organometallic material prepared in this embodiment for separating a propylene and propane mixture, a breakthrough experiment was conducted using the synthesized organometallic material as an adsorbent. In this embodiment, the propylene and propane mixture was adsorbed and separated at a breakthrough temperature of 25°C, a pressure of 0.1 MPa, and a packing mass of 2.5 g. The fixed-bed breakthrough curve for the propylene and propane mixture (50 / 50, volume ratio) is shown below. Figure 4 As shown, the fixed-bed breakthrough curve for a propylene and propane mixture (95 / 5, volume ratio) is as follows. Figure 5 As shown, the results indicate that when the volume ratio of propylene to propane is 50:50 and the mixed gas flow rate is 2.0 mL / min, propane begins to permeate after 15 minutes, while propylene begins to permeate after 55 minutes, with a saturated adsorption capacity of propylene as high as 1.53 mmol / g. When the volume ratio of propylene to propane is 95:5 and the mixed gas flow rate is 2.0 mL / min, propane can permeate after 40 minutes, while propylene begins to permeate after 46 minutes, with a saturated adsorption capacity of propylene as high as 0.82 mmol / g.

[0055] Example 2

[0056] 2.0 mmol cobalt acetate tetrahydrate, 2.0 mmol RS-malic acid (racemic malic acid), and 1.0 mmol 4,4'-bipyridine were dissolved in 20 mL of a methanol / water mixture (2 / 1 v / v). The mixture was stirred thoroughly and placed in a 50 mL hydrothermal reactor, which was then heated to 160 °C and reacted for 72 hours. After the reaction was complete, the reactor was cooled, and the resulting solid was washed repeatedly with deionized water and anhydrous ethanol to obtain the purified metal-organic framework material. The pore size of this material is [insert pore size here]. The pore volume is 0.12 cm. 3 / g, BET specific surface area is 336m² 2 / g, with a microporosity of 100%. The purified adsorbent was degassed under vacuum at 120℃ for 24 hours to obtain a solvent-free adsorbent, which was then subjected to gas adsorption.

[0057] To test the adsorption performance of the metal-organic framework material prepared in this embodiment, single-component adsorption experiments of propylene and propane were conducted using the aforementioned metal-organic framework material as an adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The results showed that at 25 °C and 1 bar, the adsorption capacity of propylene reached 1.70 mmol / g, while the adsorption capacity of propane was 1.20 mmol / g. The Henry selectivity reached 4.5.

[0058] To test the kinetic adsorption performance of the metal-organic framework material prepared in this embodiment for propylene and propane, single-component kinetic adsorption experiments were conducted using the aforementioned metal-organic framework material as the adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The tests showed that at 25 °C and 100 kPa, propylene reached adsorption equilibrium in 20 minutes, while propane reached adsorption equilibrium in 4000 minutes. Based on diffusion coefficient calculations, the kinetic adsorption selectivity of this adsorbent for propylene and propane was as high as 113.4. Its combined thermodynamic-kinetic selectivity (the product of the square root of the Henry coefficient and the kinetic selectivity) was 47.9.

[0059] To test the actual effect of the organometallic material prepared in this embodiment on the separation of a propylene and propane mixture, a breakthrough experiment was conducted using the synthesized organometallic material as an adsorbent. In this embodiment, a propylene-propane mixture was adsorbed and separated at a volume ratio of 50:50, a breakthrough temperature of 25°C, a pressure of 0.1 MPa, and a packing mass of 2.5 g. The tests showed that when the propylene-propane volume ratio was 50:50 and the mixed gas flow rate was 2.0 mL / min, propane began to penetrate after 20 minutes, while propylene only began to penetrate after 50 minutes, with a saturated adsorption capacity of propylene as high as 1.33 mmol / g. When the propylene-propane volume ratio was 95:5 and the mixed gas flow rate was 2.0 mL / min, propane could penetrate after 39 minutes, while propylene only began to penetrate after 44 minutes, with a saturated adsorption capacity of propylene as high as 0.68 mmol / g.

[0060] Comparative Example 1

[0061] 2.4 mmol nickel acetate tetrahydrate, 3 mmol R-malic acid, and 1.2 mmol 4,4'-bipyridine were dissolved in 4 mL of a methanol / water mixture (1 / 1 v / v). The mixture was stirred thoroughly and placed in a 25 mL hydrothermal reactor, which was then heated to 150 °C for 48 hours. After the reaction was complete, the reactor was cooled, and the resulting solid was washed repeatedly with deionized water and anhydrous ethanol to obtain a purified metal-organic framework material. The pore size of this material is [insert pore size here]. The pore volume is 0.12 cm. 3 / g, BET specific surface area is 269m² 2 / g, with a microporosity of 100%. The purified adsorbent was degassed under vacuum at 120℃ for 24 hours to obtain a solvent-free adsorbent, which was then subjected to gas adsorption.

[0062] To test the adsorption performance of the metal-organic framework material prepared in this embodiment, single-component adsorption experiments of propylene and propane were conducted using the aforementioned metal-organic framework material as an adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The results showed that at 25 °C and 1 bar, the adsorption capacity of propylene reached 2.02 mmol / g, while the adsorption capacity of propane was 1.92 mmol / g. The Henry selectivity was only 1.1.

[0063] To test the kinetic adsorption performance of the metal-organic framework material prepared in this embodiment for propylene and propane, single-component kinetic adsorption experiments were conducted using the aforementioned metal-organic framework material as the adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The tests showed that at 25 °C and 100 kPa, propylene reached adsorption equilibrium in 2.8 minutes, and propane reached adsorption equilibrium in 3 minutes. Based on diffusion coefficient calculations, the kinetic adsorption selectivity of this adsorbent for propylene and propane was only 1.04. Its combined thermodynamic-kinetic selectivity (the product of the square root of the Henry coefficient and the kinetic selectivity) was 1.08.

[0064] To test the actual performance of the organometallic material prepared in this embodiment for separating a propylene and propane mixture, a breakthrough experiment was conducted using the synthesized organometallic material as an adsorbent. In this embodiment, the propylene and propane mixture was adsorbed and separated at a breakthrough temperature of 25°C, a pressure of 0.1 MPa, and a packing mass of 2.5 g. The test showed that when the volume ratio of propylene to propane was 50:50 and the mixed gas flow rate was 2.0 mL / min, propane and propylene broke through almost simultaneously within 60 minutes, indicating that the material has almost no practical separation performance for the propylene and propane mixture.

[0065] Comparative Example 2

[0066] 2.4 mmol nickel acetate tetrahydrate, 3 mmol S-malic acid, and 1.2 mmol 4,4'-bipyridine were dissolved in 4 mL of a methanol / water mixture (1 / 1 v / v). The mixture was stirred thoroughly and placed in a 25 mL hydrothermal reactor, which was then heated to 150 °C for 48 hours. After the reaction was complete, the reactor was cooled, and the resulting solid was washed repeatedly with deionized water and anhydrous ethanol to obtain a purified metal-organic framework material. The pore size of this material is [insert pore size here]. The pore volume is 0.12 cm. 3 / g, BET specific surface area is 267m² 2 / g, with a microporosity of 100%. The purified adsorbent was degassed under vacuum at 120℃ for 24 hours to obtain a solvent-free adsorbent, which was then subjected to gas adsorption.

[0067] To test the adsorption performance of the metal-organic framework material prepared in this embodiment, single-component adsorption experiments of propylene and propane were conducted using the aforementioned metal-organic framework material as an adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The results showed that at 25 °C and 1 bar, the adsorption capacity of propylene reached 2.01 mmol / g, while the adsorption capacity of propane was 1.92 mmol / g. The Henry selectivity was only 1.1.

[0068] To test the kinetic adsorption performance of the metal-organic framework material prepared in this embodiment for propylene and propane, single-component kinetic adsorption experiments were conducted using the aforementioned metal-organic framework material as the adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The tests showed that at 25 °C and 100 kPa, propylene reached adsorption equilibrium in 2.9 minutes, and propane reached adsorption equilibrium in 3 minutes. Based on diffusion coefficient calculations, the kinetic adsorption selectivity of this adsorbent for propylene and propane was only 1.03. Its combined thermodynamic-kinetic selectivity (the product of the square root of the Henry coefficient and the kinetic selectivity) was 1.07.

[0069] To test the actual performance of the organometallic material prepared in this embodiment for separating a propylene and propane mixture, a breakthrough experiment was conducted using the synthesized organometallic material as an adsorbent. In this embodiment, the propylene and propane mixture was adsorbed and separated at a breakthrough temperature of 25°C, a pressure of 0.1 MPa, and a packing mass of 2.5 g. The test showed that when the volume ratio of propylene to propane was 50:50 and the mixed gas flow rate was 2.0 mL / min, propane and propylene broke through almost simultaneously within 60 minutes, indicating that the material has almost no practical separation performance for the propylene and propane mixture.

[0070] Comparative Example 3

[0071] 2.4 mmol of cobalt acetate tetrahydrate, 3 mmol of R-malic acid, and 1.2 mmol of 4,4'-bipyridine were dissolved in 4 mL of a methanol / water mixture (1 / 1 v / v). The mixture was stirred thoroughly and placed in a 25 mL hydrothermal reactor, which was then heated to 150 °C for 48 hours. After the reaction was complete, the reactor was cooled, and the resulting solid was washed repeatedly with deionized water and anhydrous ethanol to obtain the purified metal-organic framework material. The pore size of this material is [insert pore size here]. The pore volume is 0.12 cm. 3 / g, BET specific surface area is 248m² 2 / g, with a microporosity of 100%. The purified adsorbent was degassed under vacuum at 120℃ for 24 hours to obtain a solvent-free adsorbent, which was then subjected to gas adsorption.

[0072] To test the adsorption performance of the metal-organic framework material prepared in this embodiment, single-component adsorption experiments of propylene and propane were conducted using the aforementioned metal-organic framework material as an adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The results showed that at 25 °C and 1 bar, the adsorption capacity of propylene reached 1.92 mmol / g, while the adsorption capacity of propane was 1.87 mmol / g. The Henry selectivity was only 1.1.

[0073] To test the kinetic adsorption performance of the metal-organic framework material prepared in this embodiment for propylene and propane, single-component kinetic adsorption experiments were conducted using the aforementioned metal-organic framework material as the adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The tests showed that at 25 °C and 100 kPa, propylene reached adsorption equilibrium in 3 minutes, and propane reached adsorption equilibrium in 3.3 minutes. Based on diffusion coefficient calculations, the kinetic adsorption selectivity of this adsorbent for propylene and propane was only 1.06. Its combined thermodynamic-kinetic selectivity (the product of the square root of the Henry coefficient and the kinetic selectivity) was 1.11.

[0074] To test the actual performance of the organometallic material prepared in this embodiment for separating a propylene and propane mixture, a breakthrough experiment was conducted using the synthesized organometallic material as an adsorbent. In this embodiment, the propylene and propane mixture was adsorbed and separated at a breakthrough temperature of 25°C, a pressure of 0.1 MPa, and a packing mass of 2.5 g. The test showed that when the volume ratio of propylene to propane was 50:50 and the mixed gas flow rate was 2.0 mL / min, propane and propylene broke through almost simultaneously within 58 minutes, indicating that the material has almost no practical separation performance for the propylene and propane mixture.

[0075] Comparative Example 4

[0076] 2.4 mmol of cobalt acetate tetrahydrate, 3 mmol of S-malic acid, and 1.2 mmol of 4,4'-bipyridine were dissolved in 4 mL of a methanol / water mixture (1 / 1 v / v). The mixture was stirred thoroughly and placed in a 25 mL hydrothermal reactor, which was then heated to 150 °C for 48 hours. After the reaction was complete, the reactor was cooled, and the resulting solid was washed repeatedly with deionized water and anhydrous ethanol to obtain a purified metal-organic framework material. The pore size of this material is [insert pore size here]. The pore volume is 0.12 cm. 3 / g, BET specific surface area is 251m² 2 / g, with a microporosity of 100%. The purified adsorbent was degassed under vacuum at 120℃ for 24 hours to obtain a solvent-free adsorbent, which was then subjected to gas adsorption.

[0077] To test the adsorption performance of the metal-organic framework material prepared in this embodiment, single-component adsorption experiments of propylene and propane were conducted using the aforementioned metal-organic framework material as an adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The results showed that at 25 °C and 1 bar, the adsorption capacity of propylene reached 1.91 mmol / g, while the adsorption capacity of propane was 1.88 mmol / g. The Henry selectivity was only 1.1.

[0078] To test the kinetic adsorption performance of the metal-organic framework material prepared in this embodiment for propylene and propane, single-component kinetic adsorption experiments were conducted using the aforementioned metal-organic framework material as the adsorbent. 100 mg of adsorbent was used, and the adsorption temperature was set to 25 °C. The tests showed that at 25 °C and 100 kPa, propylene reached adsorption equilibrium in 2.9 minutes, and propane reached adsorption equilibrium in 3.2 minutes. Based on diffusion coefficient calculations, the kinetic adsorption selectivity of this adsorbent for propylene and propane was only 1.05. Its combined thermodynamic-kinetic selectivity (the product of the square root of the Henry coefficient and the kinetic selectivity) was 1.1.

[0079] To test the actual performance of the organometallic material prepared in this embodiment for separating a propylene and propane mixture, a breakthrough experiment was conducted using the synthesized organometallic material as an adsorbent. In this embodiment, the propylene and propane mixture was adsorbed and separated at a breakthrough temperature of 25°C, a pressure of 0.1 MPa, and a packing mass of 2.5 g. The test showed that when the volume ratio of propylene to propane was 50:50 and the mixed gas flow rate was 2.0 mL / min, propane and propylene broke through almost simultaneously within 58 minutes, indicating that the material has almost no practical separation performance for the propylene and propane mixture.

[0080] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for adsorption separation of propylene and propane, comprising contacting a mixed gas containing propylene and propane with a metal-organic framework material for adsorption separation. in, The organic ligands of the metal-organic framework material include R-malic acid and S-malic acid, the metal ions of the metal-organic framework material are selected from one or more of nickel ions and cobalt ions, and the pillar-supporting ligands of the metal-organic framework material are selected from one or more of 4,4'-bipyridine or 1,2-di(4-pyridyl)ethylene, meso-α,β-di(4-pyridyl)ethylene glycol.

2. The method according to claim 1, characterized in that, The molar ratio of R-malic acid to S-malic acid is (20-80):(80-20).

3. The method according to claim 1, characterized in that, The molar ratio of R-malic acid to S-malic acid is (40-60):(60-40).

4. The method according to claim 1, characterized in that, The molar ratio of R-malic acid to S-malic acid is 50:

50.

5. The method according to claim 1, characterized in that, The organic ligands of the metal-organic framework material are selected from racemic malic acid.

6. The method according to claim 1, characterized in that, The metal-organic framework material contains nickel or cobalt ions; and / or The pillar ligand of the metal-organic framework material is 4,4'-bipyridine.

7. The method according to claim 1, characterized in that, The microporosity of the metal-organic framework material is >95%; and / or The metal-organic framework material has a pore size of 4.6 Å-5.3 Å; and / or The pore volume of the metal-organic framework material is 0.10-0.20 cm³. 3 / g; and / or The specific surface area of ​​the metal-organic framework material is 250 m². 2 / g-600m 2 / g; and / or The shape of the metal-organic framework material includes one or more of the following: spherical, cubic, granular, or membrane-like.

8. The method according to claim 7, characterized in that, The metal-organic framework material has a microporosity of 100%; and / or the pore size of the metal-organic framework material is 4.5 Å-5.3 Å; and / or the pore volume of the metal-organic framework material is 0.12-0.18 cm³. 3 / g; and / or the specific surface area of ​​the metal-organic framework material is 250m². 2 / g-500m 2 / g.

9. The method according to any one of claims 1-8, characterized in that, The metal-organic framework material is prepared by a method comprising the following steps: hydrothermal reaction of malic acid, a metal inorganic salt and a pillared ligand in a solvent.

10. The method according to claim 9, characterized in that, The inorganic metal salt is selected from one or more of the following: chloride, nitrate, acetate, carbonate, sulfate, or perchlorate salts of metal ions; and / or The solvent comprises an organic solvent and water, wherein the organic solvent is selected from one or more of methanol, ethanol, acetonitrile, acetone, N,N-dimethylformamide or N,N-dimethylacetamide.

11. The method according to claim 10, characterized in that, The organic solvent is methanol.

12. The method according to claim 9, characterized in that, The inorganic metal salt is selected from acetates; and / or the solvent comprises an organic solvent and water, wherein the organic solvent is selected from one or more of methanol, ethanol, acetonitrile, acetone, N,N-dimethylformamide, or N,N-dimethylacetamide.

13. The method according to claim 9, characterized in that, The molar ratio of malic acid to metal inorganic salt and pillared ligand is (1-3):(1-3):1; and / or the volume ratio of organic solvent to water in the solvent is 1:(0.1-5).

14. The method according to claim 13, characterized in that, The molar ratio of malic acid to metal inorganic salt and pillared ligand is (1.5-2.5):(1.5-2.5):

1.

15. The method according to claim 9, characterized in that, The hydrothermal reaction temperature is 100°C to 180°C; and / or the hydrothermal reaction time is 12 hours to 96 hours.

16. The method according to claim 9, characterized in that, The hydrothermal reaction temperature is 140°C to 170°C; and / or the hydrothermal reaction time is 48 hours to 72 hours.

17. The method according to claim 9, characterized in that, The method further includes washing and / or drying the products of the hydrothermal reaction.

18. The method according to claim 17, characterized in that, The washing process includes washing with water and ethanol in sequence; the drying temperature is 30°C to 120°C; and the drying time is 6 hours to 24 hours.

19. The method according to any one of claims 1-8, characterized in that, The adsorption separation temperature is -5°C to 50°C; and / or the total pressure of the mixed gas containing propylene and propane in the adsorption separation is 100 kPa to 5000 kPa; and / or the adsorption separation is carried out in a fixed-bed temperature swing adsorption device or a pressure swing adsorption device or a simulated moving bed adsorption device.

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