Preparation method of shape memory hydrogel / MOFs composite material for adsorbing and separating SF6 / N2

Abstract

The invention discloses a preparation method of a shape memory hydrogel / MOFs composite material for adsorbing and separating SF6 / N2, and relates to a preparation method of a shape memory hydrogel / MOFs composite material. According to the invention, MOFs and shape SMH are introduced into the field of gas adsorption, a method for combining SMH and MOFs materials is creatively provided by utilizing interaction among SF6, metal ions and organic ligands and pore channels dynamically recovered by shape memory hydrogel, and a novel SMH composite MOFs material which dynamically adapts to SF6 / N2 mixed gas separation and solves the problem of layered MOFs stacking is prepared. Through the flexible network coating and stress buffering effects of the memory SMH, the bottleneck of insufficient mechanical stability and cycle life of MOFs is overcome, and the long-term separation performance is guaranteed. In addition, SMH provides an attachment frame for MOFs, and the problem that the adsorption capacity is reduced due to stacking of MOFs materials is solved.

Description

Technical Field

[0001] The present invention relates to a preparation method of a shape memory hydrogel / MOFs composite material. Background Art

[0002] Sulfur hexafluoride (SF6) is widely used in fields such as high-voltage electrical equipment, semiconductor manufacturing, and medical imaging due to its excellent chemical stability, insulation performance, and arc extinguishing ability. However, SF6 is one of the most potent greenhouse gases, with a global warming potential (GWP) 23,900 times that of CO2, and it can persist in the atmosphere for up to 3200 years, posing a serious threat to climate change. To balance economic and environmental requirements, the industrial sector often uses SF6 / N2 mixed gas (SF6 content ≤ 10%) to replace pure SF6, but the subsequent separation and recovery of the mixed gas remain a key challenge in reducing environmental hazards.

[0003] Current mainstream SF6 / N2 separation technologies such as cryogenic distillation, catalytic decomposition, and membrane separation generally have defects such as high energy consumption, complex operation, or high equipment costs. In contrast, adsorption separation technologies based on porous adsorbents have attracted much attention due to their simple operation and high energy efficiency. However, traditional adsorbents (such as zeolites and activated carbon) are limited by their disordered pore structures and surface chemical inertness, showing problems such as low SF6 adsorption capacity, poor selectivity, and insufficient regeneration efficiency under actual working conditions, and are difficult to meet industrial-level separation requirements. Metal-organic framework (MOFs) materials provide a new direction for breaking through the above bottlenecks due to their customizable crystal structures, high specific surface areas, and precisely controllable pore characteristics. By regulating the pore size and surface chemical microenvironment of MOFs, their specific recognition ability for SF6 molecules can be optimized, while considering both adsorption capacity and selectivity. However, existing MOF-based adsorbents still face two major challenges: (1) The rigid MOF pores cannot dynamically adapt to the complex working conditions required for SF6 / N2 mixed gas separation. The brittle framework of MOFs is prone to structural collapse or inactivation of active sites during multiple adsorption-regeneration cycles, resulting in a continuous decline in adsorption capacity and selectivity; (2) Layered MOF materials are prone to stacking problems, leading to the occlusion of adsorption sites and a reduction in the adsorption amount. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2.

[0005] The present invention introduces MOFs and shape memory hydrogels (SMH) into the field of gas adsorption. By utilizing the interactions between SF6 and metal ions and organic ligands, as well as the dynamically restored pores of SMH, a method of combining SMH with MOF materials is creatively proposed to prepare a novel SMH composite MOF material that can dynamically adapt to the separation of SF6 / N2 mixed gases and solve the problem of stacking of layered MOFs.

[0006] A preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 is specifically completed according to the following steps:

[0007] I. Preparation of SMH precursor solution:

[0008] Dissolve N-isopropylacrylamide in deionized water, disperse it by ultrasonic wave, then add [3-(methacrylamido)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt and N,N'-methylenebisacrylamide, stir until evenly mixed, and then add ammonium persulfate, and continue to disperse by ultrasonic wave to obtain the SMH precursor solution;

[0009] II. Preparation of SMH / MOFs composite solution:

[0010] ①. Dissolve 1,3,5-benzenetricarboxylic acid in the SMH precursor solution to obtain solution A;

[0011] ②. Dissolve Cu(NO3)2·3H2O in the SMH precursor solution to obtain solution B;

[0012] ③. Mix solution A and solution B, stir for a period of time to obtain the SMH / MOFs composite solution;

[0013] III. Preparation of SMH / MOFs composite material:

[0014] Transfer the SMH / MOFs composite solution to a polytetrafluoroethylene mold, cover it with a glass plate to prevent water evaporation, and carry out a free radical polymerization reaction under constant temperature conditions to form a three-dimensional network structure hydrogel; immerse the three-dimensional network structure hydrogel in deionized water for cleaning, and after cleaning, seal it with plastic wrap and store it for a period of time to maintain its moisture content and structural stability, so as to obtain a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2.

[0015] The principle of the present invention:

[0016] SMH is a type of stimulus-responsive hydrogel with programmable shape memory effect. Under the action of one or more stimuli, the reversible cross-linking network in the hydrogel cross-linking structure undergoes morphological changes, and the temporary shape of the hydrogel is fixed. However, when the external stimulus is removed or changed, the temporary shape will return to the permanent shape, which provides an attachment substrate for MOFs, ensures the adsorption environment of MOFs, and utilizes the dynamic response characteristics of SMH and the high specific surface area of MOFs to synergistically improve the SF6 adsorption capacity, selectivity and cycle stability, and solves the problem that the brittle framework of MOFs is prone to structural collapse or inactivation of active sites during multiple adsorption-regeneration cycles.

[0017] Meanwhile, MOFs are loaded on the SMH three-dimensional network matrix by in-situ growth method. During the gelation process, metal ions are uniformly anchored between polymer chains, and then organic ligands are precisely assembled through coordination reaction to form a composite structure with both the flexible network of SMH and the rigid pores of MOFs, which solves the problem of easy stacking of layered MOFs materials and improves the adsorption capacity.

[0018] Advantages of the present invention:

[0019] The brittle framework of MOFs is prone to structural collapse or inactivation of active sites during multiple adsorption-regeneration cycles, resulting in continuous attenuation of adsorption capacity and selectivity. Through the flexible network coating and stress buffering effect of memory-type SMH, the present invention overcomes the bottleneck of insufficient mechanical stability and cycle life of MOFs and ensures long-term separation performance. In addition, SMH provides an attachment framework for MOFs, thus exposing more adsorption sites and solving the problem of reduced adsorption amount due to stacking of MOFs materials. Description of the drawings

[0020] Figure 1 Adsorption performance diagram of shape memory hydrogel / MOFs composites for adsorbing and separating SF6 / N2 prepared by changing the dosage of H3BTC in Examples 1, 6-9;

[0021] Figure 2 SF6 adsorption amount and selectivity diagram of shape memory hydrogel / MOFs composites for adsorbing and separating SF6 / N2 prepared in Example 2 after 10 cycles;

[0022] Figure 3 Infrared curve diagram of shape memory hydrogel / MOFs composites for adsorbing and separating SF6 / N2 prepared in Example 2. Detailed implementation manners

[0023] The following chemicals were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (analytical pure with a purity of 99%): N-isopropylacrylamide (113.16, abbreviated as NIPAM), [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt (292.39, abbreviated as SSP), N,N'-methylenebisacrylamide (154.17, abbreviated as MBAA), ammonium persulfate (abbreviated as APS), 1,3,5-benzenetricarboxylic acid (abbreviated as H3BTC), copper nitrate trihydrate (abbreviated as Cu(NO3)2·3H2O).

[0024] Specific Embodiment 1: A preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 is specifically completed according to the following steps:

[0025] I. Preparation of SMH precursor solution:

[0026] Dissolve N-isopropylacrylamide in deionized water, ultrasonically disperse it, then add [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt and N,N'-methylenebisacrylamide, stir until evenly mixed, and then add ammonium persulfate, and continue ultrasonic dispersion to obtain the SMH precursor solution;

[0027] II. Preparation of SMH / MOFs composite solution:

[0028] ①. Dissolve 1,3,5-benzenetricarboxylic acid in the SMH precursor solution to obtain solution A;

[0029] ②. Dissolve Cu(NO3)2·3H2O in the SMH precursor solution to obtain solution B;

[0030] ③. Mix solution A and solution B, stir for a period of time to obtain the SMH / MOFs composite solution;

[0031] III. Preparation of SMH / MOFs composite material:

[0032] Transfer the SMH / MOFs composite solution to a polytetrafluoroethylene mold, cover it with a glass plate to prevent water evaporation, and carry out a free radical polymerization reaction under constant temperature conditions to form a three-dimensional network structure hydrogel; immerse the three-dimensional network structure hydrogel in deionized water for cleaning, and after cleaning, seal it with plastic wrap and store it for a period of time to maintain its moisture content and structural stability, so as to obtain a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2.

[0033] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that in Step 1, the molar ratio of N-isopropylacrylamide to the volume of deionized water is (0.03 mol to 0.2 mol): 100 mL. Other steps are the same as those in Specific Embodiment 1.

[0034] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that in Step 1, the molar ratio of [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt to the volume of deionized water is (0.03 mol to 0.2 mol): 100 mL. Other steps are the same as those in Specific Embodiment 1 or 2.

[0035] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that in Step 1, the mass ratio of N,N'-methylenebisacrylamide to the volume of deionized water is (0.1 g to 0.3 g): 100 mL. Other steps are the same as those in Specific Embodiments 1 to 3.

[0036] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that in Step 1, the mass ratio of ammonium persulfate to the volume of deionized water is (0.2 g to 0.4 g): 100 mL; the ultrasonic time in Step 1 is 20 min to 40 min. Other steps are the same as those in Specific Embodiments 1 to 4.

[0037] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that in Step 2①, the molar ratio of 1,3,5-benzenetricarboxylic acid to the volume of the SMH precursor solution is (0.5 mmol to 2.5 mmol): 50 mL. Other steps are the same as those in Specific Embodiments 1 to 5.

[0038] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that in Step 2②, the molar ratio of Cu(NO3)2·3H2O to the volume of the SMH precursor solution is (2.5 mmol to 3.5 mmol): 50 mL. Other steps are the same as those in Specific Embodiments 1 to 6.

[0039] Specific Embodiment 8: The difference between this embodiment and any one of Specific Embodiments 1 to 7 is that in Step 2③, the volume ratio of Solution A to Solution B is 1:1; the stirring speed in Step 2③ is 500 rpm to 1000 rpm, and the stirring time is 20 min to 40 min. Other steps are the same as those in Specific Embodiments 1 to 7.

[0040] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is that the temperature of the radical polymerization reaction in Step 3 is 80°C to 85°C, and the time is 10 h to 12 h. Other steps are the same as those in Embodiments 1 to 8.

[0041] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is that in Step 3, the three-dimensional network structure hydrogel is immersed in deionized water at 5°C for 5 min to 10 min, and after washing, it is sealed with plastic wrap and stored for 20 h to 24 h to maintain its moisture content and structural stability. Other steps are the same as those in Embodiments 1 to 9.

[0042] The following examples are used to verify the beneficial effects of the present invention:

[0043] Examples 1 to 5 are to change the molar ratio of NIPAM:SSP in Step 1 to determine the best anti-mechanical stretching effect, and Examples 6 to 10 are to change the amount of substance of H3BTC in Step 2 to determine the best effect.

[0044] Example 1: A preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 is specifically completed according to the following steps:

[0045] I. Preparation of SMH precursor solution:

[0046] Dissolve 0.05 mol of N-isopropylacrylamide (NIPAM) in 100 mL of deionized water, ultrasonically disperse for 30 min, then add 0.05 mol of [3-(methacrylamido)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt (SSP) and 0.2 g of N,N'-methylenebisacrylamide (MBAA), stir until evenly mixed, and then add 0.3 g of ammonium persulfate (APS), and continue to ultrasonically disperse for 30 min to obtain the SMH precursor solution;

[0047] II. Preparation of SMH / MOFs composite solution:

[0048] ①. Dissolve 2 mmol of 1,3,5-benzenetricarboxylic acid (H3BTC) in 50 mL of the SMH precursor solution to obtain Solution A;

[0049] ②. Dissolve 3 mmol of Cu(NO3)2·3H2O in 50 mL of the SMH precursor solution to obtain Solution B;

[0050] ③. Mix Solution A and Solution B, stir for a period of time to obtain the SMH / MOFs composite solution;

[0051] The volume ratio of Solution A and Solution B in Step ②③ is 1:1;

[0052] In step ②③, the stirring speed is 500 rpm and the stirring time is 30 min;

[0053] III. Preparation of SMH / MOFs composite material:

[0054] Transfer the SMH / MOFs composite solution into a polytetrafluoroethylene mold, cover it with a glass plate to prevent water evaporation, and carry out free radical polymerization reaction at 80 °C for 12 h under constant temperature conditions to form a three-dimensional network structure hydrogel; Immerse the three-dimensional network structure hydrogel in deionized water at 5 °C for 5 min, and after washing, seal it with plastic wrap and store it for 24 h to maintain its moisture content and structural stability, so as to obtain a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2.

[0055] Example 2: The difference between this example and Example 1 is that in step one, 0.1 mol of N-isopropylacrylamide (NIPAM) is dissolved in 100 mL of deionized water. Other steps and parameters are the same as those in Example 1.

[0056] Example 3: The difference between this example and Example 1 is that in step one, 0.1 mol of [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt (SSP) is added. Other steps and parameters are the same as those in Example 1.

[0057] Example 4: The difference between this example and Example 1 is that in step one, 0.1 mol of N-isopropylacrylamide (NIPAM) is dissolved in 100 mL of deionized water, ultrasonically dispersed for 30 min, and then 0.15 mol of [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt (SSP) is added. Other steps and parameters are the same as those in Example 1.

[0058] Example 5: The difference between this example and Example 1 is that in step one, 0.15 mol of N-isopropylacrylamide (NIPAM) is dissolved in 100 mL of deionized water, ultrasonically dispersed for 30 min, and then 0.15 mol of [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt (SSP) is added. Other steps and parameters are the same as those in Example 1.

[0059] Example 6: The difference between this example and Example 1 is that in step ① of step two, 0.5 mmol of 1,3,5-benzenetricarboxylic acid (H3BTC) is dissolved in 50 mL of SMH precursor solution to obtain solution A. Other steps and parameters are the same as those in Example 1.

[0060] Example 7: The difference between this example and Example 1 is that in step 2①, 1 mmol of 1,3,5-benzenetricarboxylic acid (H3BTC) is dissolved in 50 mL of the SMH precursor solution to obtain solution A. Other steps and parameters are the same as those in Example 1.

[0061] Example 8: The difference between this example and Example 1 is that in step 2①, 1.5 mmol of 1,3,5-benzenetricarboxylic acid (H3BTC) is dissolved in 50 mL of the SMH precursor solution to obtain solution A. Other steps and parameters are the same as those in Example 1.

[0062] Example 9: The difference between this example and Example 1 is that in step 2①, 2.5 mmol of 1,3,5-benzenetricarboxylic acid (H3BTC) is dissolved in 50 mL of the SMH precursor solution to obtain solution A. Other steps and parameters are the same as those in Example 1.

[0063] Table 1 shows the tensile strength table of the shape memory hydrogel / MOFs composite materials prepared by changing the molar ratio of NIPAM:SSP in steps 1 of Examples 1 to 5 for the adsorption and separation of SF6 / N2.

[0064] Specific method: The shape memory hydrogel / MOFs composite material for the adsorption and separation of SF6 / N2 is made into a sample of 100 mm×2 mm×2 mm at room temperature. A force of 5 kPa Newton is applied using a tensiometer, and the strain rate of the material (NIPAM:SSP = 1:1, 2:1, 1:2, 2:3, 3:2) is recorded. The stopwatch is used to record the minimum time required to fix the temporary shape and restore the permanent shape. The tensile force is continuously applied, and the maximum tensile force at break is recorded and named the fracture strain force.

[0065] Strain rate η = σ elongation / σ original length × 100%

[0066] From the data in Table 1, it can be seen that when the molar ratio of NIPAM to SSP is 2:1, the hydrophobic NIPAM monomer in the system dominates, and the hydrogel exhibits relatively high mechanical strength (fracture stress 8 kPa) and low ductility (strain 178%). As the proportion of NIPAM decreases (such as NIPAM:SSP = 1:2), the fracture stress drops significantly to 4.7 kPa. This phenomenon is attributed to the chain segment aggregation effect of the hydrophobic groups (isopropyl groups): when the NIPAM content increases, dense physical cross-linking networks are formed between the hydrophobic chain segments, restricting the molecular chain slip and increasing the cross-linking density, thereby enhancing the material strength but reducing the ductility; conversely, the decrease in the proportion of NIPAM leads to a decrease in the density of hydrophobic cross-linking points and an increase in the network flexibility, showing a synergistic effect of strength attenuation and enhanced ductility.

[0067] Table 1

[0068]

[0069] Figure 1 Adsorption performance diagram of shape memory hydrogel / MOFs composites for SF6 / N2 adsorption separation prepared by changing the dosage of H3BTC in Examples 1, 6-9;

[0070] Specific method: Take 1.25 g of shape memory hydrogel / MOFs composites for SF6 / N2 adsorption separation, degas at 393 K for 12 h, and use a Quantachrome Autosorb-IQ instrument to measure the adsorption isotherm of SF6 at 298 K to obtain the SF6 adsorption capacity at 1 bar.

[0071] Figure 1 The amount of substance of H3BTC is 0.5 mmol for Example 6, 1 mmol for Example 7, 1.5 mmol for Example 8, 2 mmol for Example 1, and 2.5 mmol for Example 9;

[0072] From Figure 1 it can be seen that when the amount of substance of H3BTC is 2 mmol, the adsorption capacity of the material is the highest (125 cm 3 g -1 ), at this time, the formation of MOFs with Cu 2+ reaches the best ratio, and the adsorption capacity no longer increases at 2.5 mmol.

[0073] Figure 2 SF6 adsorption capacity and selectivity diagram of shape memory hydrogel / MOFs composites for SF6 / N2 adsorption separation prepared in Example 2 after 10 cycles;

[0074] Specific method: After completing one adsorption experiment, immediately conduct a desorption experiment, and start the next single-component adsorption experiment of SF6 and N2 without activation. The IAST selectivity is calculated based on the single-component adsorption capacities of SF6 and N2. The selectivity S i / j Formula: where q i and q j represent the adsorption capacities of components i and j in the adsorption phase respectively; y i and y j represent the corresponding mole fractions in the gas phase respectively. Industrially, it is default that y i and y j are 10% and 90%.

[0075] From Figure 2 it can be seen that after 10 cycles, the adsorption capacity of the material only decreases by 2% and hardly changes, while the selectivity does not decrease, proving that the material has good cycle stability and can be applied to actual industrial adsorption.

[0076] Figure 3 Infrared curve of the shape memory hydrogel / MOFs composite material prepared for Example 2 for the adsorption and separation of SF6 / N2;

[0077] The infrared FT-IR data was measured on a Nicolet 6700 infrared spectrometer.

[0078] It can be seen from Figure 3 that the main peak at 1625 cm -1 is the stretching vibration of the NIPAM amide C=O. The peak at 1157 cm -1 is the absorption peak of the ester group -C(=C)-O on the SSP, and the peak at 1037 cm -1 is the absorption peak of the C-N stretching vibration on the SSP. The above peaks indicate the successful synthesis of the material.

Claims

1. A preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2, characterized in that The preparation method is specifically completed according to the following steps: I. Preparation of SMH precursor solution: Dissolve N-isopropylacrylamide in deionized water, disperse it by ultrasonic wave, then add [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt and N,N'-methylenebisacrylamide, stir until evenly mixed, and then add ammonium persulfate, and continue to disperse by ultrasonic wave to obtain the SMH precursor solution; II. Preparation of SMH / MOFs composite solution: ①. Dissolve 1,3,5-benzenetricarboxylic acid in the SMH precursor solution to obtain solution A; ②. Dissolve Cu(NO3)2·3H2O in the SMH precursor solution to obtain solution B; ③. Mix solution A and solution B, stir for a period of time to obtain the SMH / MOFs composite solution; III. Preparation of SMH / MOFs composite material: Transfer the SMH / MOFs composite solution to a polytetrafluoroethylene mold, cover it with a glass plate to prevent water evaporation, and carry out a free radical polymerization reaction under constant temperature conditions to form a three-dimensional network structure hydrogel; Immerse the three-dimensional network structure hydrogel in deionized water for cleaning, and after cleaning, seal it with plastic wrap and store it for a period of time to maintain its moisture content and structural stability, so as to obtain a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2.

2. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step I, the molar ratio of N-isopropylacrylamide to the volume of deionized water is (0.03 mol - 0.2 mol): 100 mL.

3. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step I, the molar ratio of [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide inner salt to the volume of deionized water is (0.03 mol - 0.2 mol): 100 mL.

4. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step I, the mass ratio of N,N'-methylenebisacrylamide to the volume of deionized water is (0.1 g - 0.3 g): 100 mL.

5. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step I, the mass ratio of ammonium persulfate to the volume of deionized water is (0.2 g - 0.4 g): 100 mL; The time of ultrasonic wave in step I is 20 min - 40 min.

6. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step II①, the molar ratio of 1,3,5-benzenetricarboxylic acid to the volume of the SMH precursor solution is (0.5 mmol - 2.5 mmol): 50 mL.

7. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step II②, the molar ratio of Cu(NO3)2·3H2O to the volume of the SMH precursor solution is (2.5 mmol - 3.5 mmol): 50 mL.

8. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, wherein In step II③, the volume ratio of solution A to solution B is 1:1; The stirring speed in step II③ is 500 rpm - 1000 rpm, and the stirring time is 20 min - 40 min.

9. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, wherein In step III, the temperature of the free radical polymerization reaction is 80 °C - 85 °C, and the time is 10 h - 12 h.

10. The preparation method of a shape memory hydrogel / MOFs composite material for adsorptive separation of SF6 / N2 according to claim 1, characterized in that In step III, immerse the three-dimensional network structure hydrogel in deionized water at 5 °C for cleaning for 5 min - 10 min, and after cleaning, seal it with plastic wrap and store it for 20 h - 24 h to maintain its moisture content and structural stability.

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