A method for promoting adsorption separation of ethane / ethylene by visible light irradiation using a "porphyrin metal organic two-dimensional framework-porous carbon" composite material

Abstract

The application discloses a method for promoting adsorption and separation of ethane / ethylene by visible light irradiation through a "porphyrin metal organic two-dimensional framework-porous carbon" composite material, which utilizes light irradiation to induce and change the electron density distribution of the adsorption site, forming a new ethane selective adsorption site different from the ground state, and the adsorption and separation effect of ethane / ethylene is significantly improved. The method of the application uses the "porphyrin metal organic two-dimensional framework-porous carbon" composite material as an ethane / ethylene adsorbent, and synchronously irradiates the composite material in the ethane / ethylene adsorption process with light. The light irradiation induces excitation of the composite material, changes the electron density distribution near the adsorption site, forms a new ethane selective adsorption site different from the ground state, makes the adsorption activity of the composite material break away from the limitation of the ground state and be in a long-life stable excited state, and improves the adsorption capacity of the "porphyrin metal organic two-dimensional framework-porous carbon" composite material for ethane and the adsorption selectivity of ethane / ethylene.

Description

Technical Field

[0001] This invention relates to a method for promoting the adsorption and separation of ethane / ethylene using light irradiation, and more specifically to a method for promoting the adsorption and separation of ethane / ethylene using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material under visible light irradiation. Background Technology

[0002] Ethylene, a crucial raw material in the petrochemical industry, is typically produced through ethane cracking. Due to the low relative volatility of ethane / ethylene (only 1.2), separating ethane / ethylene to produce polymer-grade ethylene with a purity of 99.99% remains one of the most challenging chemical separation tasks. Traditional cryogenic ethane / ethylene separation processes are usually conducted under extreme conditions of -90 to -15°C and 0.7 to 2.8 MPa, with distillation columns often exceeding 100 trays, making it a high-energy-consuming process. Adsorption separation, as an energy-efficient separation process, has attracted widespread attention, and various adsorbents are being explored. For ethane / ethylene separation, common adsorbents fall into two main categories: ethylene-selective adsorbents and ethane-selective adsorbents. The active C=C bond of ethylene molecules and their smaller molecular size compared to ethane facilitate the design of ethylene-selective adsorbents. Therefore, based on mechanisms such as π-complexation, molecular sieving, and kinetic sieving, a series of adsorbents with high ethylene selectivity have been successfully prepared, with ethylene selectivity for ethane typically reaching tens or even hundreds. However, the impurity component in the cracked gas mixture is ethane rather than ethylene. Therefore, developing adsorption separation processes with lower energy consumption and selective ethane adsorption has broader application prospects. Currently, preparing ethane adsorbents with high adsorption capacity and high selectivity remains a challenge. Even with some unconventional strategies for designing ethane adsorbents, such as post-synthesis masking, pore adjustment, and pore volume segmentation, the ethylene selectivity of most ethane adsorbents still does not exceed 2.0. This significantly limits the development of ethane / ethylene adsorption separation processes.

[0003] The aforementioned post-synthesis masking method, pore adjustment method, and pore volume segmentation method essentially employ chemical means to modify and modulate the adsorbent. These methods are highly dependent on the properties of the adsorbent matrix material, while the adsorption performance (adsorption capacity and selectivity) of the adsorbent ultimately depends on the characteristics of the adsorption sites. Besides using chemical means to modify and modulate the adsorption sites, utilizing excited states to alter the charge density distribution of the adsorption sites is another potential method for modulating adsorption site performance. Metalloporphyrins are widely found in nature and organisms, such as cytochromes, heme, and chlorophyll. They are easily excited by visible light and exhibit high photoelectric conversion efficiency. Therefore, in current technologies, porphyrins are generally widely used in fields requiring dynamic photoelectric conversion, such as photosensitizers, photocatalysis, and biocatalysis. No technological solutions have considered utilizing the static excited state of porphyrins. Carbon materials, due to their high specific surface area and abundant tunable pores, are generally widely used in various catalytic and adsorption fields. However, no technological solutions have explicitly explored their adsorption application potential based on their microscopic electronic properties, and the adsorption and separation performance of various carbon materials for ethane / ethylene is generally poor. Carbon materials possess a large number of conjugated electrons, and their electron density distribution changes significantly once excited. Utilizing the characteristics of both porphyrin metal-organic two-dimensional frameworks and porous carbon, it is possible to develop an adsorbent that uses light to generate a stable excited state, thereby altering the characteristics of its adsorption sites and exhibiting better selective adsorption of ethane. Currently, there are no reported technical solutions for improving the adsorption and separation of ethane / ethylene by preparing composite materials from porphyrin metal-organic two-dimensional frameworks and porous carbon, using light irradiation as an inducing factor. The technical solution of this application will provide a new and effective process for the adsorption and separation of ethane / ethylene. Summary of the Invention

[0004] The purpose of this invention is to overcome the bottleneck of traditional ethane selective adsorbent design and preparation methods limited by chemical modification, or to solve the problem of difficulty in improving the selectivity of ethane / ethylene adsorption and separation. This invention provides a method for promoting the adsorption and separation of ethane / ethylene using a porphyrin metal-organic two-dimensional framework-porous carbon composite material (hereinafter referred to as TM-PC) under visible light irradiation. This method utilizes light irradiation to induce a long-lived stable excited state in TM-PC, altering the electron density distribution of its adsorption sites and forming novel ethane-selective adsorption sites different from the ground state. Under light irradiation, compared with ethylene adsorption, TM-PC exhibits a larger adsorption capacity and stronger adsorption selectivity for ethane, significantly improving the ethane / ethylene adsorption and separation effect.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention utilizes a method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material. The "porphyrin metal-organic two-dimensional framework-porous carbon" composite material is used as an ethane / ethylene adsorbent. The composite material undergoing ethane / ethylene adsorption is synchronously irradiated with light. This light irradiation induces photo-induced excitation of the composite material, altering the electron density distribution near its adsorption sites and forming novel ethane-selective adsorption sites different from the ground state. This allows the adsorption activity to escape the ground state limitation and enter a long-lived, stable excited state, thereby improving the adsorption capacity of the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material for ethane and its adsorption selectivity for ethane / ethylene.

[0007] The method for promoting the adsorption and separation of ethane / ethylene by light irradiation using the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material described above in this invention has the following further technical solution: the light irradiation wavelength is 350-800 nm; and in a further technical solution, the light irradiation wavelength is 400-600 nm.

[0008] The present invention discloses a method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material. The preparation method of the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material includes the following steps: preparing a porphyrin metal-organic two-dimensional framework material TM via a hydrothermal method using TCPP as a ligand and M as a complexation node; and then preparing the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material via a hydrothermal method using TM as a photosensitizer and PC as a carrier. Here, TCPP is meso-tetra(4-carboxyphenyl)porphyrin, M represents a transition metal ion, and PC is a porous carbon material. A further technical solution is that the transition metal ion is copper, iron, or nickel ion; and the porous carbon material is microporous carbon or hierarchical porous carbon.

[0009] The method for promoting the adsorption and separation of ethane / ethylene by light irradiation using the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material described above in this invention can be further described as follows: The preparation method of the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material includes the following steps:

[0010] S1: Add TCPP, transition metal salt and N,N-dimethylformamide to a flask, and dissolve by sonication to obtain a mixed solution;

[0011] S2: Place the mixed solution under an inert atmosphere and reflux at 80-120℃ for 5-8 hours;

[0012] S3: After the hydrothermal reaction is completed and the temperature is lowered to room temperature, deionized water is added to precipitate the product. The product is then separated from the liquid phase by centrifugation. After washing with water and anhydrous ethanol 3-5 times in sequence, the product is dried under vacuum at 80-120℃ to obtain the purified crystalline product TM.

[0013] S4: Add PC, TM and N,N-dimethylformamide to a flask, and sonicate to dissolve to obtain a mixed system;

[0014] S5: Place the mixed solution under an inert atmosphere and reflux at 80-120℃ for 6-9 hours;

[0015] S6: After the hydrothermal reaction is completed, it is frozen in liquid nitrogen for 30 minutes and then freeze-dried in a freeze-drying oven to obtain the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] This invention uses porphyrin-organic metal-organic two-dimensional framework (TM-PC) composite material as the adsorbent, and utilizes the porphyrin-organic two-dimensional framework (TM) as a photosensitizer. Its interaction with the carbonaceous support PC generates a long-lived excited state. During the selective adsorption and separation of ethane / ethylene by TM-PC, visible light irradiation induces steady-state excitation, altering the electron density distribution of the TM-PC adsorption sites and forming novel adsorption sites different from the ground state. Not only does the photothermal effect not lead to a decrease in the adsorption capacity of TM-PC for ethane or a reduction in the adsorption selectivity of ethane for ethylene, but it also significantly improves both adsorption capacity for ethane and adsorption selectivity for ethylene compared to the no-light condition, achieving photo-induced adsorption activity modulation without chemical intervention. Characterization results from X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and N2 adsorption-desorption showed that TM exhibits good dispersibility on PC, and that TM-PC possesses good thermal stability and high specific surface area. UV-Vis absorption spectroscopy indicated that the material has excellent UV-Vis light absorption characteristics. Phosphorescence emission spectroscopy and phosphorescence emission attenuation detection demonstrated that the material exhibits long-lived excited-state characteristics. Applying TM-PC to the static adsorption of ethane / ethylene revealed that irradiation with visible light during the adsorption process significantly improved both the adsorption performance for ethane and the adsorption selectivity for ethylene. The corresponding ethane / ethylene adsorption selectivity increased from 1.5 in the dark environment to 4.8 under 420 nm illumination.

[0018] In summary, this invention overcomes the problem of difficulty in improving the selectivity of ethane / ethylene adsorption separation, and the bottleneck that the design and preparation of ethane selective adsorbents can only rely on chemical modification methods. Instead, it utilizes the excited state of the material itself to change its adsorption activity for ethane, and provides a method for promoting the adsorption separation of ethane / ethylene by using light irradiation. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention are clearly and completely described through the following examples, but should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples.

[0020] Examples 1-3: Preparation of TM-PC(S) adsorbents using microporous carbon PC(S) as a support

[0021] S1: Take three 100mL flasks, numbered 1#, 2#, and 3#, and add 0.50g of TCPP and 40mL of N,N-dimethylformamide to each flask. Add 1.50g of CuCl2·2H2O to flask 1#, 1.75g ​​of FeCl2·4H2O to flask 2#, and 2.10g of NiCl2·6H2O to flask 3#, and dissolve by sonication.

[0022] S2: Place the mixed solution in the three flasks under an inert atmosphere and reflux and stir at 80, 100, and 120°C for 8 hours, 6.5 hours, and 5 hours, respectively;

[0023] S3: After the hydrothermal reaction was completed and the temperature was lowered to room temperature, deionized water was added to three flasks to precipitate the product. The product was then separated from the liquid phase by centrifugation. The product was then washed by centrifugation with water and anhydrous ethanol for 3, 4, and 5 times respectively, and then dried under vacuum at 80, 100, and 120°C respectively. Crystallized products of TM were obtained from flasks #1, #2, and #3 respectively: TM(Cu), TM(Fe), and TM(Ni).

[0024] S4: Take three 100mL flasks, labeled 1-1#, 2-1#, and 3-1#. Add 0.05g of TM(Cu) to flask 1-1#, 0.05g of TM(Fe) to flask 2-1#, and 0.05g of TM(Ni) to flask 3-1#. Add 0.10g of microporous carbon powder PC(S) and 30mL of N,N-dimethylformamide to each flask, and dissolve by sonication to obtain three mixed systems.

[0025] S5: Place the three mixtures under an inert atmosphere and reflux at 80, 100, and 120°C for 9 h, 7.5 h, and 6 h, respectively;

[0026] S6: After the hydrothermal reaction was completed, the mixtures in the three flasks were frozen in liquid nitrogen for 30 minutes, and then freeze-dried in a freeze-drying oven. Three types of TM-PC(S) materials were obtained from flasks 1-1#, 2-1#, and 3-1#, respectively: TM(Cu)-PC(S), TM(Fe)-PC(S), and TM(Ni)-PC(S). The performance indicators of the adsorbents were tested as follows:

[0027] Performance indicators of adsorbents prepared in Examples 1-3

[0028] (1) Characterization of TM(Cu)-PC(S), TM(Fe)-PC(S), and TM(Ni)-PC(S) by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy showed that the samples had good morphology and that TM(Cu), TM(Fe), and TM(Ni) were uniformly dispersed on PC(S). Thermogravimetric analysis showed that all materials only exhibited significant weight loss above 400℃, proving their good thermal stability. The Brunauer-Emmett-Teller specific surface areas of TM(Cu)-PC(S), TM(Fe)-PC(S), and TM(Ni)-PC(S) were 790 m², respectively. 2 g -1 780m 2 g -1 and 750m 2 g -1 The pore volumes are 0.59 cm³. 3 g -1 0.55cm 3 g -1 and 0.52cm 3 g -1 All of them possess high specific surface area and pore volume. The results of UV-Vis absorption spectroscopy indicate that TM(Cu)-PC(S), TM(Fe)-PC(S), and TM(Ni)-PC(S) all exhibit strong absorption in the 350–800 nm range.

[0029] (2) Solid phosphorescence radiation detection proves that TM(Cu)-PC(S), TM(Fe)-PC(S) and TM(Ni)-PC(S) all have obvious phosphorescence radiation, proving that they have high abundance of excited states with corresponding energies. Moreover, the effective phosphorescence emission time of TM(Cu)-PC(S), TM(Fe)-PC(S) and TM(Ni)-PC(S), i.e. the statistical lifetime of the corresponding excited state, is as long as 50μs, 45μs and 41μs, respectively, which fully meets the time scale requirements for molecular adsorption to reach microscopic equilibrium state.

[0030] Example 4: Preparation of TM(Cu)-PC(H) adsorbent using hierarchical porous carbon PC(H) as support

[0031] S1: Take a 100mL flask, add 0.50g TCPP and 40mL N,N-dimethylformamide, and add 1.50g CuCl2·2H2O to the flask, and dissolve by sonication;

[0032] S2: Place the mixed solution in the flask under an inert atmosphere and reflux at 100°C for 7 hours;

[0033] S3: After the hydrothermal reaction is completed and the temperature is lowered to room temperature, deionized water is added to the flask to precipitate the product. The product is then separated from the liquid phase by centrifugation. After washing with water and anhydrous ethanol five times in sequence by centrifugation, the product is dried under vacuum at 100°C to obtain the crystalline product TM(Cu).

[0034] S4: Take a 100mL flask, add 0.10g of hierarchical porous carbon powder PC(H), 0.05g of TM(Cu) and 30mL of N,N-dimethylformamide, and dissolve by sonication to obtain a mixed system;

[0035] S5: Place the mixture under an inert atmosphere and reflux at 100°C for 8 hours;

[0036] S6: After the hydrothermal reaction was completed, the mixture was frozen in liquid nitrogen for 30 minutes, and then freeze-dried in a freeze-vacuum drying oven to obtain the material TM(Cu)-PC(H). The performance indicators of the adsorbent were tested as follows:

[0037] Performance indicators of the adsorbent prepared in Example 4

[0038] (1) Characterization of TM(Cu)-PC(H) by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy showed that the sample had good morphology and TM(Cu) was uniformly dispersed on PC(H). Thermogravimetric analysis showed that the material only experienced significant weight loss above 450℃, proving its good thermal stability. The Brunauer-Emmett-Teller specific surface area of ​​TM(Cu)-PC(H) was 520 m². 2 g -1 The pore volume is 0.74 cm³. 3 g -1 It possesses a high specific surface area and pore volume. The results of UV-Vis absorption spectroscopy indicate that TM(Cu)-PC(H) exhibits strong absorption in the 350–800 nm range.

[0039] (2) Solid phosphorescence radiation detection proves that TM(Cu)-PC(H) has obvious phosphorescence emission, which proves that it has a high abundance of excited states with corresponding energies. Moreover, the effective phosphorescence emission time of TM(Cu)-PC(H), that is, the statistical lifetime of the corresponding excited state, is as long as 47 μs, which fully meets the time scale requirement for molecular adsorption to reach microscopic equilibrium.

[0040] Example 5: Application of 420nm Visible Light to Enhance the Adsorption and Separation Performance of TM(Cu)-PC(S) Ethane / Ethylene

[0041] S1: The adsorption isotherm of ethane / ethylene with adsorbent TM(Cu)-PC(S) at 0℃ was determined using a Micromeritics ASAP 2020 gas adsorption analyzer. The static volumetric method was used, and the test environment was dark, with an adsorption pressure of 0–1 bar. Before the test, the sample was pretreated under vacuum at 80℃ for 4 hours. The test temperature was maintained at 0℃ using an ice-water bath to obtain the ethane / ethylene adsorption data under 0℃ and light-free conditions.

[0042] S2: After the no-light test is completed, the sample is pretreated again under vacuum at 80°C for 4 hours.

[0043] S3: Uses a CEL-HXUV300 xenon lamp with a specific wavelength filter as the light source to provide 420nm illumination.

[0044] S4: Place the light source 20cm away from the adsorbent sample cell and simultaneously irradiate the adsorbent during the ethane / ethylene adsorption process. Other experimental conditions are the same as in the dark experiment. Obtain the ethane / ethylene adsorption data of the sample under 420nm light at 0℃.

[0045] S5: The above pretreatment and adsorption test were performed 6 times under both dark and light conditions to investigate the cyclicity of the method.

[0046] 420nm visible light gain effect of ethane / ethylene adsorption performance

[0047] (1) The ethane / ethylene adsorption test of adsorbent TM(Cu)-PC(S) under darkness and 420nm light showed that 420nm light had a selective gain effect on adsorbent TM(Cu)-PC(S) and no photothermal desorption phenomenon was observed.

[0048] (2) At 0℃ and 1 bar, the ethane adsorption capacity of adsorbent TM(Cu)-PC(S) under darkness and 420 nm light illumination was 1.80 mmol g. -1 and 2.21 mmol g -1 The adsorption capacity was increased by 23%; the ethylene adsorption capacity of adsorbent TM(Cu)-PC(S) under darkness and 420nm light was 1.75 mmol g. -1 and 1.91 mmol g -1 The adsorption capacity increased by only 9%; the corresponding ethane / ethylene adsorption selectivity increased from 1.1 in the dark environment to 2.0 under 420nm light.

[0049] (3) In subsequent ethane / ethylene cyclic adsorption experiments under darkness and 420nm light, no decrease in adsorption capacity was observed, and the 420nm light irradiation had a very stable effect on the adsorption performance of ethane / ethylene.

[0050] Example 6: Application of 520nm Visible Light to Enhance the Adsorption and Separation Performance of TM(Cu)-PC(S) Ethane / Ethylene

[0051] S1: The adsorption equilibrium isotherm of ethane / ethylene with adsorbent TM(Cu)-PC(S) at 0℃ was determined using a Micromeritics ASAP 2020 gas adsorption analyzer. The static volumetric method was employed in a dark environment with an adsorption pressure of 0–1 bar. Before testing, the sample was pretreated under vacuum at 80℃ for 4 hours. The test temperature was maintained at 0℃ using an ice-water bath to obtain ethane / ethylene adsorption data under 0℃ and light-free conditions.

[0052] S2: After the no-light test is completed, the sample is pretreated again under vacuum at 80°C for 4 hours.

[0053] S3: Uses a CEL-HXUV300 xenon lamp with a specific wavelength filter as the light source to provide 520nm illumination.

[0054] S4: Place the light source 20cm away from the adsorbent sample cell and simultaneously irradiate the adsorbent during the ethane / ethylene adsorption process. Other experimental conditions are the same as in the dark experiment. Obtain the ethane / ethylene adsorption data of the sample under 520nm light at 0℃.

[0055] S5: The above pretreatment and adsorption test were performed 6 times under both dark and light conditions to investigate the cyclicity of the method.

[0056] 520nm UV-Vis gain effect of ethane / ethylene adsorption performance

[0057] (1) The ethane / ethylene adsorption test of adsorbent TM(Cu)-PC(S) under darkness and 520nm light showed that 520nm light had a selective gain effect on adsorbent TM(Cu)-PC(S) and no photothermal desorption phenomenon was observed.

[0058] (2) At 0℃ and 1 bar, the ethane adsorption capacity of adsorbent TM(Cu)-PC(S) under darkness and 520 nm light illumination was 1.80 mmol g. -1 and 2.18 mmol g -1 The adsorption capacity was increased by 21%; the ethylene adsorption capacity of adsorbent TM(Cu)-PC(S) under darkness and 520nm light was 1.75 mmol g. -1and 1.81 mmol g -1 The adsorption capacity increased by only 3%; the corresponding ethane / ethylene adsorption selectivity increased from 1.1 in the dark environment to 1.8 under 520nm light.

[0059] (3) In subsequent ethane / ethylene cyclic adsorption experiments under darkness and 520nm light, no decrease in adsorption capacity was observed, and the 520nm light irradiation had a very stable effect on the adsorption performance of ethane / ethylene.

[0060] Example 7: Application of 420nm Visible Light to Enhance the Adsorption and Separation Performance of TM(Cu)-PC(H) Ethane / Ethylene

[0061] S1: The adsorption equilibrium isotherm of ethane / ethylene with adsorbent TM(Cu)-PC(H) at 0℃ was determined using a Micromeritics ASAP 2020 gas adsorption analyzer. The static volumetric method was used, and the test environment was dark, with an adsorption pressure of 0–1 bar. Before the test, the sample was pretreated under vacuum at 80℃ for 4 hours. The test temperature was maintained at 0℃ using an ice-water bath to obtain ethane / ethylene adsorption data under 0℃ and light-free conditions.

[0062] S2: After the no-light test is completed, the sample is pretreated again under vacuum at 80℃ for 4 hours;

[0063] S3: Uses a CEL-HXUV300 xenon lamp with a specific wavelength filter as the light source to provide 420nm illumination;

[0064] S4: Place the light source 20cm away from the adsorbent sample cell and simultaneously irradiate the adsorbent during the ethane / ethylene adsorption process. Other experimental conditions are the same as in the dark experiment. Obtain the ethane / ethylene adsorption data of the sample under 420nm light at 0℃.

[0065] S5: The above pretreatment and adsorption test were performed 6 times under both dark and light conditions to investigate the cyclicity of the method.

[0066] Gain effect of 420nm UV-Vis light on ethane / ethylene adsorption performance

[0067] (1) The ethane / ethylene adsorption test of adsorbent TM(Cu)-PC(H) under darkness and 420nm light showed that 420nm light had a selective gain effect on adsorbent TM(Cu)-PC(H) and no photothermal desorption phenomenon was observed.

[0068] (2) At 0℃ and 1 bar, the ethane adsorption capacity of adsorbent TM(Cu)-PC(H) under darkness and 420 nm light illumination was 2.06 mmol g. -1and 2.62 mmol g -1 The adsorption capacity was increased by 27%; the ethylene adsorption capacity of adsorbent TM(Cu)-PC(H) under darkness and 420nm light was 1.67 mmol g. -1 and 1.70 mmol g -1 The adsorption capacity increased by only 2%; the corresponding ethane / ethylene adsorption selectivity increased from 1.5 in the dark environment to 4.8 under 420nm light.

[0069] (3) In subsequent ethane / ethylene cyclic adsorption experiments under darkness and 420nm light, no decrease in adsorption capacity was observed, and the 420nm light irradiation had a very stable effect on the adsorption performance of ethane / ethylene.

[0070] Example 8: Application of 420nm Visible Light to Enhance the Adsorption and Separation Performance of TM(Fe)-PC(H) Ethane / Ethylene

[0071] S1: The adsorption equilibrium isotherm of ethane / ethylene with adsorbent TM(Fe)-PC(H) at 0℃ was determined using a Micromeritics ASAP 2020 gas adsorption analyzer. The static volumetric method was used, and the test environment was dark, with an adsorption pressure of 0–1 bar. Before the test, the sample was pretreated under vacuum at 80℃ for 4 hours. The test temperature was maintained at 0℃ using an ice-water bath to obtain ethane / ethylene adsorption data under 0℃ and light-free conditions.

[0072] S2: After the no-light test is completed, the sample is pretreated again under vacuum at 80℃ for 4 hours;

[0073] S3: Uses a CEL-HXUV300 xenon lamp with a specific wavelength filter as the light source to provide 420nm illumination;

[0074] S4: Place the light source 20cm away from the adsorbent sample cell and simultaneously irradiate the adsorbent during the ethane / ethylene adsorption process. Other experimental conditions are the same as in the dark experiment. Obtain the ethane / ethylene adsorption data of the sample under 420nm light at 0℃.

[0075] S5: The above pretreatment and adsorption test were performed 6 times under both dark and light conditions to investigate the cyclicity of the method.

[0076] Gain effect of 420nm UV-Vis light on ethane / ethylene adsorption performance

[0077] (1) The ethane / ethylene adsorption test of adsorbent TM(Fe)-PC(H) under darkness and 420nm light showed that 420nm light had a selective gain effect on adsorbent TM(Fe)-PC(H) and no photothermal desorption phenomenon was observed.

[0078] (2) At 0℃ and 1 bar, the ethane adsorption capacity of adsorbent TM(Fe)-PC(H) under darkness and 420 nm light illumination was 2.70 mmol g. -1 and 3.50 mmol g -1 The adsorption capacity was increased by 30%; the ethylene adsorption capacity of adsorbent TM(Fe)-PC(H) under darkness and 420nm light was 2.50 mmol g. -1 and 2.56 mmol g -1 The adsorption capacity increased by only 2%; the corresponding ethane / ethylene adsorption selectivity increased from 1.2 in the dark environment to 3.5 under 420nm light.

[0079] (3) In subsequent ethane / ethylene cyclic adsorption experiments under darkness and 420nm light, no decrease in adsorption capacity was observed, and the 420nm light irradiation had a very stable effect on the adsorption performance of ethane / ethylene.

[0080] Example 9: Application of 420nm Visible Light to Enhance the Adsorption and Separation Performance of TM(Ni)-PC(H) Ethane / Ethylene

[0081] S1: The adsorption equilibrium isotherm of ethane / ethylene with adsorbent TM(Ni)-PC(H) at 0℃ was determined using a Micromeritics ASAP 2020 gas adsorption analyzer. The static volumetric method was used, and the test environment was dark, with an adsorption pressure of 0–1 bar. Before the test, the sample was pretreated under vacuum at 80℃ for 4 hours. The test temperature was maintained at 0℃ using an ice-water bath to obtain ethane / ethylene adsorption data under 0℃ and light-free conditions.

[0082] S2: After the no-light test is completed, the sample is pretreated again under vacuum at 80℃ for 4 hours;

[0083] S3: Uses a CEL-HXUV300 xenon lamp with a specific wavelength filter as the light source to provide 420nm illumination;

[0084] S4: Place the light source 20cm away from the adsorbent sample cell and simultaneously irradiate the adsorbent during the ethane / ethylene adsorption process. Other experimental conditions are the same as in the dark experiment. Obtain the ethane / ethylene adsorption data of the sample under 420nm light at 0℃.

[0085] S5: The above pretreatment and adsorption test were performed 6 times under both dark and light conditions to investigate the cyclicity of the method.

[0086] Gain effect of 420nm UV-Vis light on ethane / ethylene adsorption performance

[0087] (1) The ethane / ethylene adsorption test of the adsorbent TM(Ni)-PC(H) under darkness and 420nm light showed that 420nm light had a selective gain effect on the adsorbent TM(Ni)-PC(H) and no photothermal desorption phenomenon was observed.

[0088] (2) At 0℃ and 1 bar, the ethane adsorption capacity of the adsorbent TM(Ni)-PC(H) under darkness and 420 nm light illumination was 2.51 mmol g. -1 and 2.91 mmol g -1 The adsorption capacity was increased by 16%; the ethylene adsorption capacity of adsorbent TM(Ni)-PC(H) under darkness and 420nm light was 2.16 mmol g, respectively. -1 and 2.20 mmol g -1 The adsorption capacity increased by only 2%; the corresponding ethane / ethylene adsorption selectivity increased from 1.1 in the dark environment to 2.7 under 420nm light.

[0089] (3) In subsequent ethane / ethylene cyclic adsorption experiments under darkness and 420nm light, no decrease in adsorption capacity was observed, and the 420nm light irradiation had a very stable effect on the adsorption performance of ethane / ethylene.

Claims

1. A method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material, characterized in that, Using a porphyrin-metal-organic two-dimensional framework-porous carbon composite material as an ethane / ethylene adsorbent, the porphyrin-metal-organic two-dimensional framework-porous carbon composite material undergoing ethane / ethylene adsorption was photo-induced excited by light irradiation. This light irradiation altered the electron density distribution near the adsorption sites, forming novel ethane-selective adsorption sites different from the ground state. This allowed the adsorption activity to escape the ground state limitation and enter a long-lived, stable excited state, thus enhancing the adsorption of ethane by the porphyrin-metal-organic two-dimensional framework-porous carbon composite material. The adsorption capacity and ethane / ethylene adsorption selectivity; the preparation method of the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material includes the following steps: using TCPP as a ligand and M as a complexing node, a porphyrin metal-organic two-dimensional framework material TM is prepared by hydrothermal method; then, using TM as a photosensitizer and PC as a carrier, the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material is prepared by hydrothermal method, wherein TCPP is medium-tetra(4-carboxyphenyl)porphyrin, M represents a transition metal ion, and PC is a porous carbon material; the transition metal ion is copper, iron, or nickel ion.

2. The method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material according to claim 1, characterized in that, The wavelength of the illumination is 350~800 nm.

3. The method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material according to claim 2, characterized in that... The wavelength of the illumination is 400~600 nm.

4. The method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material according to claim 3, characterized in that... The porous carbon material is microporous carbon or hierarchical porous carbon.

5. The method for promoting the adsorption and separation of ethane / ethylene by light irradiation using a "porphyrin metal-organic two-dimensional framework-porous carbon" composite material according to claim 3, characterized in that... The preparation method of the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material includes the following steps: S1: Add TCPP, transition metal salt and N,N-dimethylformamide to a flask, and dissolve by sonication to obtain a mixed solution; S2: Place the mixed solution under an inert atmosphere and reflux at 80-120℃ for 5-8 hours; S3: After the hydrothermal reaction is completed and the temperature is lowered to room temperature, deionized water is added to precipitate the product. The product is then separated from the liquid phase by centrifugation. After washing with water and anhydrous ethanol 3-5 times in sequence, the product is dried under vacuum at 80-120℃ to obtain the purified crystalline product TM. S4: Add PC, TM and N,N-dimethylformamide to a flask, and sonicate to dissolve to obtain a mixed system; S5: Place the mixed solution under an inert atmosphere and reflux at 80-120℃ for 6-9 hours; S6: After the hydrothermal reaction is completed, it is frozen in liquid nitrogen for 30 minutes and then freeze-dried in a freeze-drying oven to obtain the "porphyrin metal-organic two-dimensional framework-porous carbon" composite material.