MOF (Metal Organic Framework) porous solution for storing gas through adsorption-hydration coupling, preparation method of MOF porous solution and method for storing gas through adsorption-hydration coupling

Abstract

The invention discloses an MOF (Metal Organic Framework) porous solution for storing gas through adsorption-hydration coupling, a preparation method of the MOF porous solution and a method for storing gas through adsorption-hydration coupling. The MOF porous solution comprises modified MOF powder and water, and the modified MOF powder is dispersed in the water to form a stable dispersion liquid; the modified MOF powder comprises MOF and a hydrophilic dynamic accelerant, and the hydrophilic dynamic accelerant is modified on the outer surface of the MOF, so that the inner cavity of the modified MOF powder is hydrophobic, and the outer surface of the modified MOF powder is hydrophilic; in the MOF porous solution, the concentration of the MOF is 1 to 3 weight percent, and the concentration of the hydrophilic dynamic accelerant is 1000 to 6000 ppm. The preparation method has the advantages of low cost, high dispersity and capabilities of breaking through storage capacity limitation and improving hydrate generation dynamics performance, mass transfer hindrance can be broken through while adsorption and hydrate coupled gas storage are realized, and the storage speed and reserve of gas are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrate gas storage, and in particular to a MOF porous solution for adsorption-hydration coupled gas storage, a preparation method thereof, and an adsorption-hydration coupled gas storage method. Background Art

[0002] The existing natural gas hydrate (NGH) gas storage technology is regarded as an important storage method for green transition energy due to its safety and environmental protection characteristics. However, the traditional hydrate method has two major bottlenecks: first, the storage capacity is limited, and the theoretical methane storage capacity is only 150-170V / V, which is difficult to meet industrial needs; second, the mass transfer barrier is serious, the hydrate formation rate in the static system is low, and additional energy input (such as stirring and bubbling) is required, which increases the cost. Most of the current research adopts the adsorption-hydration coupling gas storage technology based on porous materials, among which the porous materials are represented by metal-organic framework compounds (Metal-Organic Framework, MOF), but due to the high filling cost of MOF and the significant adsorption thermal effect, its large-scale application is limited; in addition, in the traditional method, MOF has poor dispersion in the liquid phase, resulting in low mass transfer efficiency, so the adsorption-hydration coupling gas storage technology still needs to be continuously improved.

[0003] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0004] The invention provides a MOF porous solution for adsorption-hydration coupled storage of gas, a preparation method thereof and a method for adsorption-hydration coupled storage of gas.

[0005] The present invention adopts the following technical solution: In a first aspect, a MOF porous solution for adsorption-hydration coupled gas storage is provided, which comprises a modified MOF powder and water, wherein the modified MOF powder is dispersed in the water to form a stable dispersion; the modified MOF powder comprises MOF and a hydrophilic kinetic promoter, wherein the hydrophilic kinetic promoter is modified on the outer surface of the MOF, so that the inner cavity of the modified MOF powder is hydrophobic and the outer surface is hydrophilic; in the MOF porous solution, the concentration of MOF is 1-3wt%, and the concentration of the hydrophilic kinetic promoter is 1000-6000ppm.

[0006] Preferably, the MOF is at least one of ZIF-8 and ZIF-67.

[0007] Preferably, the hydrophilic kinetic promoter is at least one of SDS, amino acid and SDBS.

[0008] Preferably, the MOF is ZIF-8, and the hydrophilic kinetic promoter is SDS; in the MOF porous solution, the concentration of MOF is 3wt%, and the concentration of the hydrophilic kinetic promoter is 4500ppm.

[0009] Preferably, the inner cavity of the modified MOF powder is a microporous structure with a pore size of less than 2 nm; the specific surface area of ​​the MOF is greater than 1000 m 2 / g; the absolute value of the Zeta potential of the MOF porous solution is ≥10mV.

[0010] In a second aspect, a method for preparing the MOF porous solution according to the first aspect is provided, comprising the following steps: (1) mixing the hydrophilic kinetic promoter and the raw material for preparing the MOF in a predetermined ratio, centrifuging, drying, vacuum activating, and grinding to obtain the modified MOF powder; (2) adding the modified MOF powder into water, subjecting it to ultrasonic treatment for a predetermined time, and then stirring it at room temperature to form a stable dispersion to obtain the MOF porous solution; Alternatively, the steps include: A. adding the hydrophilic kinetic promoter and the MOF into water in a predetermined ratio to prepare a solution; B. The solution obtained in step A is subjected to ultrasonic treatment for a predetermined time and then stirred at room temperature to form a stable dispersion to obtain the MOF porous solution.

[0011] Preferably, the ultrasonic time in step (2) or step B is 30-60 min.

[0012] In a third aspect, a method for storing gas by adsorption-hydration coupling of the MOF porous solution according to the first aspect is provided, comprising the following steps: (a) injecting the MOF porous solution into a high-pressure reactor and precooling it to a predetermined temperature; (b) According to a predetermined gas-liquid volume ratio, the gas is precooled to the same temperature as the MOF porous solution in the high-pressure reactor, and then injected into the high-pressure reactor to a predetermined pressure to complete the adsorption-hydration coupled storage of the gas under static conditions (without stirring).

[0013] Preferably, the gas-liquid volume ratio in step (b) is in the range of 1:1 to 6:1; and the predetermined pressure in step (b) is 6-10 MPa.

[0014] Preferably, the gas is methane, the MOF in the MOF porous solution is ZIF-8, the hydrophilic kinetic promoter is SDS, the concentration of MOF is 3wt%, the concentration of the hydrophilic kinetic promoter is 4500ppm, the predetermined temperature in step (a) is 275.15K; and the gas-liquid volume ratio in step (b) is 5:1.

[0015] The beneficial effects of the present invention include: the MOF porous solution of the present invention is a stable dispersion, the MOF surface is modified by a hydrophilic kinetic promoter, a "hydrophilic outer shell-hydrophobic inner pore" dual-functional structure is constructed, the contradiction between MOF dispersibility and adsorption capacity is solved, and the problems of weak methane hydrate generation kinetics, less methane solid content, and material waste in the prior art are solved. Specifically, the modified MOF powder in the MOF porous solution has the characteristics of coexistence of a hydrophilic outer surface and a hydrophobic inner pore. Under static conditions, the MOF porous solution can enhance mass transfer by adsorbing gas and promote rapid nucleation of gas hydrates, thereby having excellent gas adsorption performance. Therefore, the MOF porous solution of the present invention not only accelerates the kinetic generation of gas hydrates, improves the overall adsorption and hydrate generation kinetics, increases the theoretical reserves of gas hydrates, but also realizes static and efficient storage, does not require additional mechanical energy consumption, can spontaneously adsorb gas, and generate hydrates, realizes high-density solid-state storage of gas, and reduces the amount of material used, improves the economic efficiency of the application of the method, limits the diffusion of chemical substances, and reduces the environmental impact of the use of promoters. In general, the present invention has the advantages of low cost, high dispersibility, the ability to break through storage capacity limitations and improve the kinetics of hydrate formation. It can achieve adsorption and hydrate coupled gas storage while breaking mass transfer barriers and increasing gas storage speed and reserves. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1(a), FIG1(b) and FIG1(c) are respectively the SEM image, TEM image, pore size distribution image and N2 adsorption-desorption curve of the modified MOF powder in Example 1 of the present invention; FIG. 1( d ) and FIG. 1( e ) are N 2 adsorption-desorption curves of the MOF before modification and the MOF after modification in Example 1 of the present invention, respectively; Figure 2 The comparison results of the MOF porous solution and the MOF slurry in Example 1 of the present invention are shown; Figure 3 Density characterization results of MOF porous solutions with different concentrations; Figure 4 This is a graph of the cyclic gas storage performance of the MOF porous solution in an experiment of the present invention in which a MOF porous solution with a MOF concentration of 1wt% and a SDS concentration of 1000ppm is used to store methane by adsorption-hydration coupling; Figure 5It is a comparison chart of the reserves of SDS solution, MOF slurry and MOF porous solution in the embodiment; Figure 6 Zeta potential detection results of MOF porous solutions with different concentrations before and after hydrate formation. DETAILED DESCRIPTION

[0017] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention. In the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0018] A specific embodiment of the present invention provides a MOF porous solution for adsorption-hydration coupled storage of gas, which includes modified MOF powder and water, wherein the modified MOF powder is dispersed in the water to form a stable dispersion; the modified MOF powder includes MOF and a hydrophilic kinetic promoter, wherein the hydrophilic kinetic promoter is modified on the outer surface of the MOF, so that the inner cavity of the modified MOF powder is hydrophobic and the outer surface is hydrophilic; in the MOF porous solution, the concentration of MOF is 1-3wt%, and the concentration of the hydrophilic kinetic promoter is 1000-6000ppm.

[0019] In the above technical scheme, MOF has a large internal adsorption space and adsorption sites, and its inner cavity is hydrophobic to avoid the invasion of water molecules. The outer surface of MOF is modified with a hydrophilic kinetic promoter to be hydrophilic and has good compatibility with water, so that the modified MOF powder can be evenly dispersed in water. The above concentration of MOF and hydrophilic kinetic promoter can ensure the dispersion stability of MOF particles in water to form a stable dispersion (the density of the dispersion is greater than the density of water), thereby ensuring that the MOF porous solution has a large gas adsorption capacity in the aqueous phase to increase the gas reserve through adsorption, and also acts as a kinetic promoter of gas hydrates to promote the formation of gas hydrates. When used for adsorption-hydration coupled storage of gas, the storage rate and reserve of gas are improved.

[0020] In the above technical scheme, the hydrophilic outer surface of the modified MOF particles coexists with the hydrophobic inner pores. Under static conditions, the MOF porous solution can enhance mass transfer by adsorbing gas and promote the rapid nucleation of gas hydrates, thereby having excellent gas adsorption performance.

[0021] In some embodiments, the MOF is at least one of ZIF-8 (the coordination metal is zinc and the ligand is 2-methylimidazole) and ZIF-67 (the coordination metal is cobalt and the ligand is 2-methylimidazole).

[0022] In some embodiments, the hydrophilic kinetic promoter is at least one of SDS (sodium dodecyl sulfate), amino acid, and SDBS (sodium dodecylbenzene sulfonate).

[0023] In some embodiments, the MOF is ZIF-8, and the hydrophilic kinetic promoter is SDS; in the MOF porous solution, the concentration of MOF is 3 wt %, and the concentration of the hydrophilic kinetic promoter is 4500 ppm.

[0024] In some embodiments, the inner cavity of the modified MOF powder is a microporous structure with a pore size of less than 2 nm; the specific surface area of ​​the MOF is greater than 1000 m 2 / g, after MOF is modified by hydrophilic kinetic promoter, the specific surface area will decrease.

[0025] In some embodiments, the stable dispersion satisfies: the absolute value of the Zeta potential of the MOF porous solution is ≥10 mV, and more preferably, the MOF porous solution does not show visible coagulation or suspension after being left to stand for 24 hours.

[0026] The specific embodiment of the present invention also provides a method for preparing the MOF porous solution, which comprises the following steps: (1) The hydrophilic kinetic promoter and the raw materials for preparing the MOF are stirred in a predetermined ratio, centrifuged, dried, vacuum activated, and ground to obtain the modified MOF powder; for example, taking ZIF-8 as the MOF, the hydrophilic kinetic promoter, 2-methylimidazole, and zinc nitrate hexahydrate are stirred in a certain ratio, centrifuged, dried, vacuum activated (such as activated in a vacuum oven at 120 degrees for at least 12 hours), and ground to obtain the modified MOF powder, that is, on the basis of the MOF preparation method known in the art, the hydrophilic kinetic promoter is added to prepare the modified MOF powder. In this process (1), the hydrophilic kinetic promoter is modified on the outer surface of the MOF.

[0027] (2) adding the modified MOF powder into water, subjecting it to ultrasonic treatment for a predetermined time, and then stirring it at room temperature to form a stable dispersion to obtain the MOF porous solution; in this process (2), the modified MOF powder is uniformly dispersed in water.

[0028] Alternatively, the steps include: A. adding the hydrophilic kinetic promoter and the MOF into water in a predetermined ratio to prepare a solution; B. The solution obtained in step A is subjected to ultrasonic treatment for a predetermined time and then stirred at room temperature to form a stable dispersion to obtain the MOF porous solution. In this process B, the hydrophilic kinetic promoter is modified on the outer surface of the MOF and then uniformly dispersed in water.

[0029] In some embodiments, the ultrasonic time in step (2) or step B is 30-60 min. Under this ultrasonic time, it is ensured that the MOF porous solution is a stable dispersion rather than a slurry, suspension, suspension slurry, etc.

[0030] In some embodiments, after sonication, the solution is stirred in a water bath at room temperature (295-299 K) until the Zeta potential of the solution meets a predetermined requirement (preferably the absolute value of the Zeta potential is ≥10 mV), for example, stirring for 30 minutes.

[0031] The specific embodiment of the present invention also provides a method for storing gas based on the adsorption-hydration coupling of the MOF porous solution, comprising the following steps: (a) injecting the MOF porous solution into a high-pressure reactor and precooling it to a predetermined temperature; (b) According to a predetermined gas-liquid volume ratio, the gas is precooled to the same temperature as the MOF porous solution in the high-pressure reactor, and then injected into the high-pressure reactor to a predetermined pressure, and the gas adsorption-hydration coupled storage is completed under static conditions. Among them, a fixed-pressure storage test experiment can be carried out, in which methane is injected to a predetermined pressure at one time, and then stored for a predetermined time (such as 24 hours) under static conditions; a variable-pressure storage test experiment can also be carried out, in which the injection of methane is gradual, and 0.5MPa to 1MPa of methane is injected into the storage tank every 30 minutes or more until the pressure reaches the predetermined pressure, and then stored for a predetermined time (such as 24 hours) under static conditions.

[0032] In some embodiments, the gas-liquid volume ratio in step (b) is in the range of 1:1 to 6:1; and the predetermined pressure in step (b) is 6-10 MPa.

[0033] In some embodiments, the gas is methane, the MOF in the MOF porous solution is ZIF-8, the hydrophilic kinetic promoter is SDS, the concentration of MOF is 3wt%, the concentration of the hydrophilic kinetic promoter is 4500ppm, the predetermined temperature in step (a) is 275.15K; and the gas-liquid volume ratio in step (b) is 5:1.

[0034] The specific embodiments of the present invention are further described below.

[0035] Example 1

[0036] The preparation method of MOF porous solution comprises the following steps: (1) According to the MOF porous solution, the concentration of MOF is 3wt%, the concentration of SDS is 4500ppm, SDS, zinc nitrate hexahydrate, and 2-methylimidazole are stirred, centrifuged, dried, vacuum activated, and ground to obtain a modified MOF powder, which is represented by ZIF-8@SDS. As shown in Figures 1(a), 1(b), and 1(c), they are the SEM image, TEM image, and pore size distribution image of the modified MOF powder, respectively. As shown in Figures 1(d) and 1(e), they are the N2 adsorption and desorption curves of the MOF before and after modification, respectively. It can be seen that the measured specific surface area of ​​the MOF (ZIF-8) before modification is 1483m 2 / g, and the specific surface area of ​​the modified MOF (ZIF-8@SDS) is 245m 2 / g.

[0037] (2) The modified MOF powder was added to water and subjected to ultrasound for 30 minutes, followed by stirring at room temperature for 30 minutes to form a stable dispersion to obtain the MOF porous solution. The MOF porous solution had a Zeta potential (measured by a Zetasizer Nano ZS90 instrument) of -40 mV and a liquid density of 1.004 g / ml.

[0038] In order to illustrate that the MOF porous solution of the present invention is a stable dispersion, as a comparison, the present invention also configures a MOF slurry (i.e., ZIF-8 is directly dispersed in water, and the concentration of ZIF-8 is 3wt%), such as Figure 2 As shown, it is the comparison result of the MOF porous solution of the present invention and the MOF slurry. It can be seen that in the MOF porous solution of the present invention, the particles are evenly dispersed and have good dispersibility, forming a stable dispersion liquid, while in the MOF slurry, it can be clearly seen that the particles in the solution are unevenly dispersed, with more obvious particle suspension in the upper layer of the solution and more obvious particle coagulation in the lower layer.

[0039] In some other embodiments, the difference from Example 1 is that the concentrations of MOF and SDS in the MOF porous solution are different, and the obtained modified MOF powders are represented as ZIF-8@SDSw1 (MOF is 0.5wt%, SDS is 1000ppm), ZIF-8@SDSw2 (MOF is 1wt%, SDS is 1000ppm), ZIF-8@SDSw3 (MOF is 1.5wt%, SDS is 1000ppm), respectively. Figure 3 As shown, the density characterization results of the MOF porous solutions obtained using these modified MOF powders are shown, indicating that the density of the MOF porous solutions of the present invention is greater than that of water.

[0040] Example 2

[0041] This embodiment provides a method for storing methane by adsorption-hydration coupling of the MOF porous solution according to embodiment 1, comprising the following steps: (a) The MOF porous solution of Example 1 is injected into a high-pressure reactor and precooled to 275.15K; wherein the high-pressure reactor adopts a double-layer stainless steel storage tank, an appropriate amount of the MOF porous solution of Example 1 is injected into the inner layer, and the outer layer is a vacuum insulation layer with a design pressure of 10MPa. The double-layer stainless steel storage tank is equipped with a temperature control module, a temperature sensor, a pressure sensor and a visual monitoring device, etc., and the temperature in the high-pressure reactor is maintained at 275.15K by the temperature control module.

[0042] (b) According to the gas-liquid volume ratio of 5:1, methane gas is injected into the buffer tank and precooled to 275.15K. The precooled methane is then injected from the buffer tank into the high-pressure reactor to a pressure of 7.2MPa. In this example, a variable pressure reserve test is performed. The injection of methane is gradual. 0.5MPa to 1MPa of methane is injected into the storage tank every 30 minutes or more until the pressure reaches 7.5MPa. The methane is then stored under static conditions for 24 hours to complete the adsorption-hydration coupled storage of methane. In this example, the purity of the methane gas is greater than 99%.

[0043] When conducting the above storage experiment, real-time monitoring can be carried out through temperature sensors, pressure sensors and visualization equipment to determine the pressure and temperature changes before methane hydrate formation, monitor the formation location and spatial growth mode of methane hydrate, and calculate the methane adsorption-hydration coupled reserves of the final MOF porous solution (in this case, the methane reserves are 206.3V / V), providing directional guidance for subsequent gas injection.

[0044] After the storage is completed, if the remaining MOF porous solution in the high-pressure reactor shows visible particle aggregation or suspension, it means that the dispersibility is reduced, or the dispersibility is tested by Zeta potential (which can be measured by Zetasizer Nano ZS90 instrument). If the dispersibility is reduced (for example, the absolute value of Zeta potential is less than 10mV), the solution is ultrasonically treated again for a predetermined time and then stirred and dispersed at room temperature before a methane storage experiment is performed. If the dispersibility is good (for example, the absolute value of Zeta potential is not less than 10mV), the methane storage experiment is directly performed. In this way, the MOF porous solution can be recycled.

[0045] In an experiment of methane storage by adsorption-hydration coupling using a MOF porous solution with a MOF concentration of 1 wt% and a SDS concentration of 1000 ppm, the MOF porous solution was recycled three times for gas storage, such as Figure 4 As shown, it is a cyclic gas storage performance diagram of the MOF porous solution. The capacity retention rate of the MOF porous solution after three cycles is greater than 90%.

[0046] As a comparison, the present invention also uses SDS solution, MOF slurry (i.e., slurry formed by directly dispersing ZIF-8 in water (e.g., Figure 2 The methane storage experiment in steps (a)-(b) of Example 2 was carried out, and the storage capacity of the MOF porous solution was compared with that of Example 1. Figure 5 As shown, it can be seen that the methane storage capacity of the MOF porous solution of the present invention is significantly greater than the methane storage capacity of the two comparative solutions.

[0047] like Figure 6 As shown, the Zeta potential detection results (measured by ZetasizerNano ZS90 instrument) of MOF porous solutions with different concentrations (expressed in the figure as: SDS concentration + SDS@ MOF concentration + MOF, such as 1000ppmSDS@ 1.0wt%MOF) before and after hydrate formation are shown. This figure shows that the dispersion stability of the particles of the MOF porous solution of the present invention is not degraded after recycling.

[0048] When used for methane storage and transportation, the pressure changes can be monitored during the above storage process. During transportation, the pressure regulating valve is used to maintain about 7.0 MPa. After arriving at the destination, the methane is gradually released through the pressure reducing valve, and the methane adsorbed in the MOF inner pores is simultaneously desorbed to achieve continuous gas supply.

[0049] Traditional natural gas storage and transportation relies on compressed natural gas (CNG, pressure 20MPa) or liquefied natural gas (LNG, -162℃ low temperature), but there are problems such as high energy consumption and great safety hazards. In this embodiment, MOF porous solution adsorption-hydration coupling storage of methane achieves a high methane storage capacity (in this example, the storage capacity of methane is 206.3V / V, which exceeds the theoretical limit of traditional hydrates (about 170V / V) by 21.5%, breaking through the theoretical upper limit of gas storage), no low temperature requirements, and the risk of tank leakage is reduced by 90%, reducing the cost of material use, reducing the transportation cost by 40% compared with LNG, and reducing equipment investment by 30%. Therefore, this embodiment has the following advantages: (1) Through the adsorption-hydration synergistic effect of MOF porous solution, the methane storage capacity reaches 206.3V / V (the upper limit of traditional hydrates is 170V / V), an increase of 21.5%, breaking through the theoretical upper limit of gas storage.

[0050] (2) It has ultra-fast gas storage dynamics and zero induction time: hydrate nucleation has almost no delay under static conditions, and major storage is completed within 5 minutes.

[0051] (3) Achieve high hydrate conversion rate, with a storage rate of 0.231 V / V·min (conventional SDS solution is only 0.103 V / V·min), low energy consumption and high stability, and no need for mechanical stirring: spontaneous mass transfer driven by MOF dispersion and adsorption reduces energy consumption by more than 50%.

[0052] (4) Excellent cycle performance: The capacity retention rate is >90% after 3 cycles, and the Zeta potential test shows that the particle dispersion stability has not degraded.

[0053] The present invention realizes high-density methane storage under mild conditions through MOF porous solution. The dual-functional design of the hydrophilic outer shell and the hydrophobic inner pore of the MOF porous solution makes the MOF evenly dispersed in the liquid phase, avoiding the agglomeration problem of traditional MOF caused by hydrophobicity. In a static system, the MOF inner pores adsorb methane to form a local high-concentration gas source, breaking through the mass transfer limitation of the gas-liquid interface, and increasing the methane dissolution rate by more than 50%. The methane adsorbed in the MOF inner pores is gradually released through the concentration gradient, providing a stable gas source for the continuous growth of hydrates, which is a new solution for natural gas storage and transportation. The MOF porous solution preparation process of the present invention is simple, does not require complex equipment, achieves cost savings, and is expected to be industrially applied.

[0054] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A MOF porous solution for adsorption-hydration coupled gas storage, characterized in that: It includes modified MOF powder and water, wherein the modified MOF powder is dispersed in the water to form a stable dispersion; the modified MOF powder includes MOF and a hydrophilic kinetic promoter, and the hydrophilic kinetic promoter is modified on the outer surface of the MOF, so that the inner cavity of the modified MOF powder is hydrophobic and the outer surface is hydrophilic; in the MOF porous solution, the concentration of MOF is 1-3wt%, and the concentration of the hydrophilic kinetic promoter is 1000-6000ppm.

2. The MOF porous solution according to claim 1, characterized in that The MOF is at least one of ZIF-8 and ZIF-67.

3. The MOF porous solution according to claim 1, characterized in that The hydrophilic kinetic promoter is at least one of SDS, amino acid and SDBS.

4. The MOF porous solution according to claim 1, characterized in that: The MOF is ZIF-8, and the hydrophilic kinetic promoter is SDS; in the MOF porous solution, the concentration of MOF is 3wt%, and the concentration of the hydrophilic kinetic promoter is 4500ppm.

5. The MOF porous solution according to claim 1, characterized in that: The inner cavity of the modified MOF powder is a microporous structure with a pore size of less than 2nm; the specific surface area of ​​the MOF is greater than 1000m 2 / g; the absolute value of the Zeta potential of the MOF porous solution is ≥10mV.

6. A method for preparing the MOF porous solution according to any one of claims 1 to 5, characterized in that: The steps include: (1) mixing the hydrophilic kinetic promoter and the raw material for preparing the MOF in a predetermined ratio, centrifuging, drying, vacuum activating, and grinding to obtain the modified MOF powder; (2) adding the modified MOF powder into water, subjecting it to ultrasonic treatment for a predetermined time, and then stirring it at room temperature to form a stable dispersion to obtain the MOF porous solution; Alternatively, the steps include: A. adding the hydrophilic kinetic promoter and the MOF into water in a predetermined ratio to prepare a solution; B. The solution obtained in step A is subjected to ultrasonic treatment for a predetermined time and then stirred at room temperature to form a stable dispersion to obtain the MOF porous solution.

7. The preparation method according to claim 6, characterized in that: The ultrasonic time in step (2) or step B is 30-60 min.

8. A method for storing gas by adsorption-hydration coupling of the MOF porous solution according to any one of claims 1 to 5, characterized in that: The steps include: (a) injecting the MOF porous solution according to any one of claims 1 to 5 into a high-pressure reactor and precooling it to a predetermined temperature; (b) According to a predetermined gas-liquid volume ratio, the gas is precooled to the same temperature as the MOF porous solution in the high-pressure reactor, and then injected into the high-pressure reactor to a predetermined pressure to complete the adsorption-hydration coupled storage of the gas under static conditions.

9. The method according to claim 8, characterized in that The gas-liquid volume ratio in step (b) is in the range of 1:1 to 6:1; the predetermined pressure in step (b) is 6-10 MPa.

10. The method according to claim 8, characterized in that The gas is methane, and the MOF porous solution is the MOF porous solution described in claim 4; the predetermined temperature in step (a) is 275.15 K; and the gas-liquid volume ratio in step (b) is 5:1.

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