An organometallic framework material, a preparation method thereof, and a method for separating and purifying ethylene

Abstract

The application discloses an organic metal framework material and a preparation method and a separation and purification method of the organic metal framework material. 112 H 67 N 24 O 32 Zn 10 The organic metal framework material is a compound synthesized by taking 1,2,4-triazole and 1,4-naphthalene dicarboxylic acid as organic bidentate ligands and a divalent zinc ion as a metal node. The novel compound HIAM-210 synthesized by the application can be used as an adsorbent to preferentially adsorb C2H2 and C2H6 from C2 ternary mixed gas, so as to achieve the ability of one-step purification of C2H4, and is expected to replace the current high-energy-consumption ethylene purification mode and has great application potential in the industrial application of adsorption separation of low-carbon hydrocarbon gas.

Description

Technical Field

[0001] The present invention mainly relates to the field of separation and purification, and in particular to an organic metal framework material and a preparation method thereof, and a method for separating, purifying and preparing ethylene. Background Art

[0002] Ethylene has a wide range of uses, including the production of chemicals such as polyethylene, ethylene glycol, styrene, ethylene oxide, ethylene propylene rubber, and polyvinyl chloride. Currently, ethylene is typically produced through the cracking of naphtha or ethane, with the product gas inevitably containing ethane (C2H6) and acetylene (C2H2) as byproducts. Downstream products require very high ethylene purity, such as polyethylene, which requires an ethylene purity of at least 99.9%. Therefore, removing ethane and acetylene from the cracked gas is an essential technical step in the ethylene production process. However, due to the similar physicochemical properties of the three C2 components, their separation is extremely challenging. In current separation processes, the acetylene in the cracked gas must first be removed through catalytic hydrogenation or solvent extraction, followed by cryogenic distillation using extremely low temperatures and a high number of plates to separate ethane and ethylene. The entire purification process is complex and energy-intensive, necessitating the development of a simpler, more energy-efficient ethylene purification and separation method.

[0003] Compared to traditional heat-driven cryogenic distillation separation technology, adsorption separation technology operates at temperatures and pressures close to room temperature and atmospheric pressure, requiring less energy. Furthermore, it offers low investment costs, flexible operation, and the ability to automate operations. These advantages, such as low cost and energy consumption, make it highly competitive. The key challenge lies in the development of highly efficient porous adsorbents, and metal-organic frameworks (MOFs) hold broad application prospects in the field of gas adsorption separation.

[0004] Although several MOFs have been developed to separate ethylene from binary C2H2 / C2H4 or C2H6 / C2H4 mixtures, few adsorbents have been reported that can purify ethylene from C2 ternary gas mixtures in one step. The main reason is that the quadrupole moment and kinetic diameter of C2H4 (1.5×10 -26 esu cm 2 and ) between C2H2(7.2×10 -26 esu cm 2 and ) and C2H6(0.65×10 -26 esu cm 2 and This special physicochemical property makes it impossible for most MOFs to produce C2H4 from C2 ternary gas mixtures in one step, whether through molecular sieving or thermodynamic separation. Summary of the Invention

[0005] The purpose of the present invention is to provide an organic metal framework material to solve the problem that existing MOF adsorbents cannot produce C2H4 from C2 ternary mixed gas in one step.

[0006] In order to achieve the above object, the present invention provides an organic metal framework material having the molecular formula C 112 H 67 N 24 O 32 Zn 10 It is a compound synthesized with 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid as organic double ligands and divalent zinc ion as metal node.

[0007] Furthermore, the asymmetric unit of the molecular structure of the organic metal framework material contains ten independent Zn(II) metal centers coordinated in three ways; among them, the coordination number of Zn1, Zn3, Zn4, Zn7, Zn8 and Zn9 is 4, and they are coordinated with two O atoms from 1,4-naphthalene dicarboxylic acid and two N atoms from 1,2,4-triazole, respectively; the coordination number of Zn2 and Zn6 is 6, and they are coordinated with two O atoms from 1,4-naphthalene dicarboxylic acid and four N atoms from 1,2,4-triazole, respectively; the coordination number of Zn5 and Zn10 is 5, and they are coordinated with three O atoms from 1,4-naphthalene dicarboxylic acid and two N atoms from 1,2,4-triazole, respectively.

[0008] Furthermore, the coordination environment of the molecules of the organic metal framework material is Figure 1 ; The molecular structure of the organic metal framework material is Figure 2 .

[0009] Furthermore, the organic metal framework material is a microporous material with a pore diameter of 0.41 nm.

[0010] Furthermore, the organic metal framework material is a crystalline material, and its crystallographic parameters are shown in Table 1 below.

[0011] In some embodiments, the organic metal framework material is synthesized in a solvent-thermal environment using 1,2,4-triazole and 1,4-naphthalene dicarboxylic acid as organic double ligands and zinc nitrate hexahydrate as a metal source; the organic metal framework material is a compound obtained by dissolving zinc nitrate hexahydrate, 1,2,4-triazole, and 1,4-naphthalene dicarboxylic acid in a solvent to obtain a mixture solution, reacting the mixture at 130-180°C, and then filtering, washing, and activating the mixture.

[0012] The present invention provides a method for preparing an organic metal framework material, comprising the following steps:

[0013] Step 1: dissolving zinc nitrate hexahydrate, 1,2,4-triazole, and 1,4-naphthalenedicarboxylic acid in a solvent to obtain a mixture solution;

[0014] Step 2: The mixed solution is subjected to a synthesis reaction at 130-180° C.; the synthesized product is an organic metal framework material.

[0015] Preferably, in the step one, the molar ratio of zinc nitrate hexahydrate, 1,2,4-triazole and 1,4-naphthalene dicarboxylic acid is 0.5:0.5~1.5:0.5~1.5; in the step one, the solvent is a mixed solvent prepared by DMF or DEF and water in a volume ratio of 0.5~3:4; in the step one, the ratio of zinc nitrate hexahydrate to the solvent is 3~8mL of solvent per 1mmol of Zn(NO3)3·6H2O; the step two also includes a post-treatment process of filtering and washing the synthesized product; the preparation method also includes a step three: activating the product of step two at 80-120°C, and the obtained product is an adsorbent material.

[0016] The present invention provides a method for separating, purifying and preparing ethylene, comprising the following steps:

[0017] Step 1: loading the organometallic framework material as an adsorbent into the adsorption column;

[0018] Step 2: The ternary mixed gas containing acetylene, ethane and ethylene is passed through an adsorption column for separation and purification. The adsorbent selectively adsorbs acetylene and ethane in the mixed gas to obtain olefin products.

[0019] Preferably, the adsorption temperature is 0-40° C., and the adsorption pressure is 0-3 bar; the desorption temperature is 50-100° C., and the desorption pressure is 0.01-1.0 bar.

[0020] The beneficial effects of the present invention are:

[0021] This invention synthesizes a novel organometallic framework material, HIAM-210. This compound provides a suitable pore size and pore chemical environment for the adsorption and separation of C2 molecules, generating stronger interactions with C2H2 and C2H6. This allows for the preferential adsorption of C2H2 and C2H6 from a C2 ternary gas mixture, resulting in a single-step purification of C2H4. By employing adsorption separation, ethylene can be separated and purified from a ternary gas mixture of acetylene, ethylene, and ethane in a single step, simplifying the existing ethylene purification process while reducing energy consumption.

[0022] The above technical features, as well as other features, objectives and advantages of the technical solution of the present invention will be described in conjunction with various embodiments of the present invention and the accompanying drawings. However, the disclosed illustrative embodiments are only examples and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the molecular coordination environment of HIAM-210 synthesized in the present invention.

[0024] Figure 2 It is a schematic diagram of the molecular structure of HIAM-210 synthesized by the present invention.

[0025] Figure 3 This is the X-ray diffraction pattern of HIAM-210 synthesized in Example 1 of the present invention. Figure 3 It can be seen that the powder X-ray diffraction of the synthesized sample is highly consistent with the simulation pattern, proving that the synthesized sample has high purity.

[0026] Figure 4 The adsorption-desorption isotherm and pore size distribution of HIAM-210 synthesized in Example 1 of the present invention under N2 77K environment. Figure 4 It can be seen that HIAM-210 material is a microporous material with a pore size concentrated at 0.41 nm.

[0027] Figure 5 The adsorption isotherms of HIAM-210 synthesized in Example 1 of the present invention for acetylene, ethane and ethylene at room temperature are as follows: Figure 5 It can be seen that the adsorption capacity of HIAM-210 material is acetylene > ethane > ethylene, which proves that the material has preferential adsorption of acetylene and ethane.

[0028] Figure 6 The selectivity of HIAM-210 to acetylene / ethylene and ethane / ethylene in the first embodiment of the present invention is shown in FIG. Figure 6 It can be seen that both reached 2.0 at 1 bar, proving that the HIAM-210 material has good selectivity for acetylene / ethylene and ethane / ethylene.

[0029] Figure 7 The dynamic penetration curves of the first and second application examples of the present invention are shown in FIG. 1 , where (a) is the dynamic penetration curve corresponding to the first application example and (b) is the dynamic penetration curve corresponding to the second application example. Figure 7 It can be seen that ethylene passes through the adsorption column before ethane and acetylene, and ethylene with a purity greater than 99.9% is detected at the outlet of the adsorption column, proving that the HIAM-210 material can achieve one-step separation of the three-component mixed gas. DETAILED DESCRIPTION

[0030] The drawings and the following description of certain embodiments of the present invention are not intended to limit the present invention to these embodiments, but are provided to enable any person skilled in the art to make and use the present invention.

[0031] The experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials described, unless otherwise specified, can be obtained from commercial channels.

[0032] The endpoints and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0033] The present invention synthesized a new metal organic framework material (MOFs), named HIAM-210 (Hoffman Institute of Advanced Material)-210, whose molecular formula is C 112 H 67 N 24 O 32 Zn 10 .

[0034] The coordination environment of the compound HIAM-210 is as follows Figure 1 , molecular structure such as Figure 2 Figure. As shown in the figure, the asymmetric unit of the compound's molecular structure contains ten independent Zn(II) metal centers coordinated in three ways. Among them, Zn1, Zn3, Zn4, Zn7, Zn8, and Zn9 have a coordination number of 4, and are coordinated to two O atoms from 1,4-naphthalenedicarboxylic acid and two N atoms from 1,2,4-triazole, respectively; Zn2 and Zn6 have a coordination number of 6, and are coordinated to two O atoms from 1,4-naphthalenedicarboxylic acid and four N atoms from 1,2,4-triazole, respectively; Zn5 and Zn10 have a coordination number of 5, and are coordinated to three O atoms from 1,4-naphthalenedicarboxylic acid and two N atoms from 1,2,4-triazole, respectively.

[0035] The organic metal framework material is a microporous material with a pore size concentrated at 0.41 nm (refer to Figure 4 ).

[0036] The organic metal framework material is a crystalline material, and its crystallographic parameters are shown in Table 1:

[0037] Table 1 shows the crystallographic parameters of the organic metal framework material HIAM-210 of the present invention

[0038]

[0039] The metal organic framework material (MOFs) HIAM-210 of the present invention provides a suitable pore size and pore chemical environment for the adsorption and separation of C2 molecules, and can generate a stronger interaction force with C2H2 and C2H6, thereby achieving the preferential adsorption of C2H2 and C2H6 from the C2 ternary mixed gas to achieve the ability to purify C2H4 in one step.

[0040] The organometallic framework material HIAM-210 of the present invention is a compound synthesized using 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid as organic dual ligands and divalent zinc ions as metal nodes. Specifically, the organometallic framework material is generated by reacting 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid as organic dual ligands and zinc nitrate hexahydrate as a metal source under a solvent-thermal environment. The specific reaction conditions are as follows:

[0041] A certain proportion of zinc nitrate hexahydrate, 1,2,4-triazole, and 1,4-naphthalenedicarboxylic acid are dissolved in a certain amount of solvent and completely dissolved. The mixed solution is then transferred to a reactor and placed in an oven for a certain period of time, for example, at a reaction temperature of 130-180°C, preferably 150°C. Yellow powder crystals are obtained by filtration and washed with DMF and water. Finally, the crystals are activated in a dynamic vacuum at a certain temperature, for example, at an activation temperature of 80-120°C, preferably 110°C, for 12 hours to remove the solvent from the crystal pores, thereby obtaining the activated compound HIAM-210.

[0042] In some embodiments, the molar ratio of zinc nitrate hexahydrate, 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid is 0.5:0.5-1.5:0.5-1.5, preferably, the ratio is 1:1:1.

[0043] In some embodiments, the solvent for dissolving the reactants is a mixed solvent of DMF or DEF and water in a volume ratio of 0.5 to 3:4, preferably, the ratio is 1:4.

[0044] In some embodiments, when dissolving the reactants, the ratio of zinc nitrate hexahydrate to solvent is such that 3 to 8 mL of solvent is required for every 1 mmol of Zn(NO 3 ) 3 ·6H 2 O. Preferably, the amount of solvent added is 5 mL.

[0045] The present invention also provides a method for separating and purifying high-purity ethylene using the above-mentioned MOFs as adsorbents, wherein HIAM-210 is used as an adsorbent to selectively adsorb acetylene and ethane, and high-purity ethylene is obtained by one-step separation and purification from the C2 three-component gas.

[0046] The method for preparing high-purity ethylene by separating and purifying HIAM-210 as an adsorbent comprises the following steps:

[0047] Step 1: The synthesized MOFs material HIAM-210 is loaded into the adsorption equipment as an adsorbent;

[0048] Step 2: The ternary mixed gas containing acetylene, ethane and ethylene is passed through the adsorption equipment for separation and purification. The HIAM-210 adsorbent will selectively adsorb the acetylene and ethane in the mixed gas to obtain high-purity olefin products.

[0049] In some embodiments, the separation and purification method can be one or more combinations of adsorption methods such as fixed-bed pressure swing adsorption, temperature swing adsorption, or low-pressure adsorption desorption. The specific process is as follows:

[0050] At the set adsorption temperature and pressure, the mixed gas enters a fixed bed filled with HIAM-210 adsorbent at a set flow rate. Ethylene preferentially penetrates the bed and is directly obtained from the adsorption column outlet. Ethane and acetylene gases are enriched in the adsorption bed. After ethylene penetrates, the bed is regenerated by desorption and the next cycle begins.

[0051] The adsorption temperature is 0-40° C., the adsorption pressure is 0-3 bar, the desorption temperature is 50-100° C., and the desorption pressure is 0.01-1.0 bar.

[0052] Synthesis Reaction Example 1

[0053] Zn(NO₃)₃·6H₂O (0.1 mmol), 1,2,4-triazole (0.1 mmol), and 1,4-naphthalenedicarboxylic acid (0.1 mmol) were dissolved in a DMF / H₂O mixture (DMF / H₂O volume ratio of 1 / 4, 5 mL). The mixture was then transferred to a Teflon-lined reactor and placed in a 150°C oven for two days. The product was filtered, washed five times with fresh DMF and water, and finally solvent-exchanged ten times with methanol. The resulting crystalline powder was vacuum-dried at 110°C for 5 hours to yield the activated adsorbent HIAM-210.

[0054] Synthesis Reaction Example 2

[0055] Zn(NO₃)₃·6H₂O (0.1 mmol), 1,2,4-triazole (0.1 mmol), and 1,4-naphthalenedicarboxylic acid (0.1 mmol) were dissolved in a 5 mL mixture of DMF and water (DMF:water ratio = 1 / 4 by volume). The mixture was then transferred to a Teflon-lined reactor and placed in a 150°C oven for 2 days. The product was filtered, washed five times with fresh DMF and water, and then solvent-exchanged 10 times with methanol. The resulting crystalline powder was vacuum-dried at 110°C for 5 hours to yield the activated adsorbent HIAM-210.

[0056] Synthesis Reaction Example 3

[0057] Zn(NO₃)₃·6H₂O (0.1 mmol), 1,2,4-triazole (0.1 mmol), and 1,4-naphthalenedicarboxylic acid (0.2 mmol) were dissolved in a 5 mL DMF / water mixture (DMF / water, 2 / 3 by volume). The mixture was then transferred to a Teflon-lined reactor and placed in a 140°C oven for two days. The product was filtered, washed five times with fresh DMF and water, and then solvent-exchanged ten times with methanol. The resulting crystalline powder was vacuum-dried at 120°C for five hours to yield the activated adsorbent HIAM-210.

[0058] Application Example 1

[0059] The HIAM-210 material obtained in Synthesis Reaction Example 1 was loaded into a fixed-bed adsorption column (inner diameter 5 mm, volume 2 mL). A three-component gas containing acetylene / ethane / ethylene (molar ratio of 1 / 1 / 1) was passed through the adsorption column at a flow rate of 1.0 mL / min at 25° C. and a back pressure of 1 bar. High-purity ethylene gas (>99.9%) was obtained at the end of the adsorption column. Adsorption was stopped when the adsorption column was completely penetrated. The adsorption column was purged with nitrogen at 100° C. for cyclic regeneration. Alternatively, desorption and regeneration were performed using a vacuum pump at room temperature with a vacuum degree of 0.05 bar.

[0060] Application Example 2

[0061] The HIAM-210 material obtained in Synthesis Reaction Example 1 was loaded into a fixed-bed adsorption column (inner diameter 5 mm, volume 2 mL). A three-component gas containing acetylene / ethane / ethylene (molar ratio of 1 / 9 / 90) was passed through the adsorption column at a flow rate of 1.0 mL / min at 25° C. and a back pressure of 1 bar. High-purity ethylene gas (>99.9%) was obtained at the end of the adsorption column. Adsorption was stopped when the adsorption column was completely penetrated. The adsorption column was purged with nitrogen at 100° C. to achieve cyclic regeneration. Alternatively, desorption and regeneration were performed using a vacuum pump at room temperature with a vacuum degree of 0.05 bar.

[0062] The X-ray diffraction pattern of the adsorbent HIAM-210 material obtained in the above-mentioned synthesis reaction example 1 is as follows: Figure 3 ,Depend on Figure 3 It can be seen that the powder X-ray diffraction of the synthesized HIAM-210 sample is highly consistent with the simulated pattern, and the results prove that the synthesized HIAM-210 sample has a high purity. The same conclusion can be drawn from Examples 2 and 3 of the synthetic reaction.

[0063] The adsorption and desorption isotherms and pore size distribution of the adsorbent HIAM-210 material obtained in the above synthesis example 1 under N2 and 77K environment are shown in the figure below: Figure 4 .Depend on Figure 4 It can be seen that the adsorbent HIAM-210 material is a microporous material with a pore size concentrated at 0.41 nm. The same conclusion can be drawn from the second and third synthetic reaction examples.

[0064] The adsorption isotherms of the adsorbent HIAM-210 material obtained in the above-mentioned synthesis example 1 for acetylene, ethane and ethylene gases at room temperature are as follows: Figure 5 ,Depend on Figure 5 It can be seen that the adsorbent HIAM-210 material exhibits an adsorption capacity of acetylene > ethane > ethylene, and the results prove that the material preferentially adsorbs acetylene and ethane. The same conclusion can be drawn from Synthesis Reaction Examples 2 and 3.

[0065] The selectivity of the adsorbent HIAM-210 material obtained in the above-mentioned synthesis example 1 to the mixed gas containing acetylene / ethylene and the mixed gas containing ethane / ethylene is shown in FIG. Figure 6 .Depend on Figure 6 It can be seen that both reached 2.0 at 1 bar, and the results proved that the HIAM-210 material has good selectivity for acetylene / ethylene and ethane / ethylene.

[0066] The dynamic penetration curves of the above application examples 1 and 2 are as follows: Figure 7 As shown, (a) is the dynamic penetration curve of application example 1, and (b) is the dynamic penetration curve of application example 2. Figure 7 It can be seen that ethylene exits the adsorption column before ethane and acetylene. Ethylene with a purity greater than 99.9% was detected at the outlet of the adsorption column. This result proves that the adsorbent HIAM-210 material of the present invention can achieve a one-step separation of the acetylene / ethane / ethylene three-component gas mixture.

[0067] The new compound HIAM-210 synthesized in the present invention can be used as an adsorbent to preferentially adsorb C2H2 and C2H6 from a C2 ternary gas mixture to achieve the ability to purify C2H4 in one step (the purity of the obtained C2H4 is greater than 99.9%). It is expected to replace the current high-energy consumption ethylene purification method and has great application potential in the industrial application of adsorption separation of low-carbon hydrocarbon gases.

[0068] As used in the specification and claims, the singular forms "a," "an," and "the" include both singular and plural references unless the context clearly dictates otherwise. The claims and specification may sometimes include terms such as "a plurality," "one or more," or "at least one." However, the absence of these terms does not imply, and should not be construed to indicate, that a plurality is not included.

[0069] It should be understood that the examples listed here and the figures shown are only for illustration and not for limitation.

Claims

1. An organic metal framework material, characterized in that The organic metal framework material has the molecular formula C 112 H 67 N 24 O 32 Zn 10 , is a compound synthesized with 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid as organic double ligands and divalent zinc ion as metal node; The organic metal framework material has an asymmetric unit in its molecular structure comprising ten independent Zn(II) metal centers coordinated in three ways; wherein the coordination number of Zn1, Zn3, Zn4, Zn7, Zn8 and Zn9 is 4, and they are coordinated with two O atoms from 1,4-naphthalene dicarboxylic acid and two N atoms from 1,2,4-triazole, respectively; the coordination number of Zn2 and Zn6 is 6, and they are coordinated with two O atoms from 1,4-naphthalene dicarboxylic acid and four N atoms from 1,2,4-triazole, respectively; the coordination number of Zn5 and Zn10 is 5, and they are coordinated with three O atoms from 1,4-naphthalene dicarboxylic acid and two N atoms from 1,2,4-triazole, respectively; The organic metal framework material has a monoclinic crystal system, a space group of Pm, and unit cell parameters of: α=90°, β=110.269(4)°, γ=90°.

2. The organic metal framework material according to claim 1, characterized in that The organic metal framework material is a microporous material with a pore diameter of 0.41 nm.

3. The organic metal framework material according to claim 1, characterized in that The organic metal framework material is synthesized in a solvent-thermal environment using 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid as organic double ligands and zinc nitrate hexahydrate as a metal source; The organic metal framework material is a compound obtained by dissolving zinc nitrate hexahydrate, 1,2,4-triazole and 1,4-naphthalenedicarboxylic acid in a solvent to obtain a mixture solution, performing a synthesis reaction at 130-180° C., and then filtering, washing and activating the mixture solution.

4. A method for preparing an organic metal framework material, comprising the following steps: Step 1: dissolving zinc nitrate hexahydrate, 1,2,4-triazole, and 1,4-naphthalenedicarboxylic acid in a solvent to obtain a mixture solution; Step 2: The mixed solution is subjected to a synthesis reaction at 130-180° C.; the synthesized product is the organic metal framework material according to any one of claims 1-3.

5. The preparation method according to claim 4, wherein In the step 1, the molar ratio of zinc nitrate hexahydrate, 1,2,4-triazole and 1,4-naphthalene dicarboxylic acid is 0.5:0.5-1.5:0.5-1.5; In the step 1, the solvent is a mixed solvent of DMF or DEF and water, wherein the volume ratio of DMF or DEF to water is 0.5 to 3:4; In the step 1, the ratio of zinc nitrate hexahydrate to the solvent is 3 to 8 mL of solvent per 1 mmol of Zn(NO3)3·6H2O; The step 2 also includes a post-processing process of filtering and washing the synthesized product; The preparation method further comprises a third step: activating the product of the second step at 80-120° C., and the obtained product is an adsorbent material.

6. A method for separating, purifying and preparing ethylene, comprising the following steps: Step 1: loading the organic metal framework material according to any one of claims 1 to 3 into an adsorption column as an adsorbent; Step 2: The ternary mixed gas containing acetylene, ethane and ethylene is passed through an adsorption column for separation and purification. The adsorbent selectively adsorbs acetylene and ethane in the mixed gas to obtain olefin products.

7. The method according to claim 6, wherein The adsorption temperature is 0-40°C and the adsorption pressure is 0-3 bar; The desorption temperature is 50-100°C, and the desorption pressure is 0.01-1.0 bar.

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