A high-density, clean and low-carbon storage method for marine natural gas using offshore wind power

Abstract

The present invention discloses a high-density, clean and low-carbon storage method for marine natural gas using offshore wind power, which uses nanoporous media to absorb moisture in high-humidity air in the sea area and reacts with methane at low temperature to form methane-doped methane hydrate, and uses a temperature oscillation method to convert the associated conventional methane hydrate into methane-doped methane hydrate; the theoretical maximum gas storage volume ratio of methane-doped methane hydrate reaches 1107 v / v, breaking through the maximum gas storage volume ratio of 164 v / v of the conventional hydrate method; methane is stored by using methane-doped methane hydrate, realizing high-density storage of marine natural gas; offshore wind power is used for refrigeration electricity in the synthesis process, which is clean and environmentally friendly; the method of the present invention realizes clean, low-carbon and high-density storage of marine natural gas, and the coordinated development of wind energy renewable energy and marine natural gas, thereby promoting high-quality development of the marine economy.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas hydrates, and in particular relates to a high-density, clean and low-carbon storage method for marine natural gas using offshore wind power. Background Art

[0002] The promotion and application of marine natural gas requires the support of efficient and clean storage technology. The natural gas hydrate method has a higher gas storage capacity than compressed natural gas and liquefied natural gas. Taking advantage of the flexible storage characteristics of hydrates, natural gas is converted into natural gas hydrates, and natural gas molecules are enclosed in cage-type crystals for storage and transportation. Hydrate storage of natural gas has the characteristics of high-density gas storage. The maximum gas storage volume ratio of the hydrate method is 164 v / v, that is, 1 volume of conventional sI type methane hydrate releases 164 volumes of methane gas at normal temperature and pressure. To break through the maximum gas storage volume ratio of 164 v / v, it is necessary to find cage-type crystals with new structures and innovate gas storage materials.

[0003] Developing marine energy is an important means to ensure energy security. While developing conventional marine natural gas, we should actively develop multi-energy comprehensive utilization technology in offshore wind power areas to achieve coordinated development of wind energy renewable energy and marine natural gas. We should use marine wind power to help develop new high-density, clean and low-carbon storage of marine natural gas. Summary of the invention

[0004] The present invention provides a high-density, clean and low-carbon storage method for marine natural gas using offshore wind power. Nanoporous media is used to absorb moisture in high-humidity air at sea and react with methane in the marine natural gas at low temperature to form methane-doped methane hydrates. The temperature oscillation method is further used to convert the associated conventional methane hydrates into methane-doped methane hydrates, thereby achieving high-density storage of marine natural gas and solving the problem of low maximum gas storage volume ratio of conventional hydrate methods in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for high-density, clean and low-carbon storage of marine natural gas using offshore wind power comprises the following steps:

[0007] (1) Using nanoporous media to absorb moisture in high-humidity air to obtain water-containing nanoporous media;

[0008] (2) Place the water-containing nanoporous medium in step (1) into a reaction vessel and pre-cool to -15 o C~-10 o C, and then inject the pre-cooled to -15 o C~-10 oC of methane gas, synthesize methane-doped methane hydrate and associated conventional methane hydrate at an initial pressure of 4-8 MPa, and the pressure after the synthesis is below 2 MPa; the associated conventional methane hydrate is converted into methane-doped methane hydrate by temperature oscillation; the synthesized methane-doped methane hydrate is frozen and stored.

[0009] In the latest research, it was found that at low temperatures, the OH bonds of water molecules that construct the methane hydrate cage in the nano-confined porous medium are broken, and the hydrogen atoms form protons and move rapidly, resulting in vacancy defects of the cage-type crystal water molecules. Methane molecules occupy the vacancies of water molecules, forming a crystal structure of methane molecules doped with methane hydrate cages. In methane-doped methane hydrates, methane molecules are both guest molecules and part of the main molecules. At room temperature, methane-doped methane hydrates decompose, and the main methane molecules and guest methane molecules together form methane gas.

[0010] In a conventional sI methane hydrate unit cell, 46 water molecules form 8 hydrate cages (2 5 12 Cage, 6 5 12 6 2 The ratio of water molecules to methane molecules is 46:8, that is, one unit cell (containing 46 water molecules) can store up to 8 methane molecules. If a sI-type methane-doped methane hydrate unit cell contains one doped methane molecule, then in the unit cell, the ratio of water to methane is (46-1):(8+1)=45:9, that is, one unit cell (containing 45 water molecules) can store up to 9 methane molecules. If a unit cell contains one 6-doped methane molecule, then in the unit cell, the ratio of water to methane is (46-6):(8+6)=40:14. That is, one unit cell (containing 40 water molecules) can store up to 14 methane molecules. The maximum number of methane molecules that can be stored in a unit cell of sI-type methane-doped methane hydrate is shown in Table 1. The use of cage-type crystals of methane-doped methane hydrate to store methane easily breaks through the maximum volume ratio of 164 V / V of conventional hydrate method for gas storage.

[0011] Table 1 Unit cell gas storage volume ratio of a sI type methane-doped methane hydrate

[0012]

[0013] Methane occupies vacancies in hydrate cages at low temperatures and participates in the construction of cages, greatly improving the ability of hydrate crystal cells to store methane. Theoretical calculations show that the theoretical maximum gas storage volume ratio of methane-doped methane hydrates reaches 1107 v / v, surpassing the maximum gas storage volume ratio of 164 v / v of conventional hydrate methods. Using methane-doped methane hydrates to store methane can achieve high-density storage of natural gas.

[0014] Preferably, in step (2), the temperature oscillation range is 0 o C~-25o C, the initial pressure range of the temperature oscillation is 4-8 MPa, and the temperature oscillation specifically includes the following steps: setting the initial temperature of the reaction container to -15 o C~-10 o C, then cooled to -25 o C, and maintain the temperature for 2 to 4 hours after it stabilizes, so that the conventional methane hydrate is converted into methane-doped methane hydrate; the reaction vessel is heated to 0 o C, and maintain the temperature for 2 to 4 hours after it stabilizes to partially decompose the conventional methane hydrate; repeat the heating and cooling steps until the pressure in the reaction vessel no longer decreases.

[0015] Furthermore, the cooling or heating rate during the temperature oscillation is 2~5 o C / min; repeat the heating and cooling steps until the pressure in the reaction vessel drops below 2 MPa and no longer decreases, and the reaction is completed.

[0016] Preferably, in step (2), the synthesized methane-doped methane hydrate is heated at -25 to -30 o C. Store frozen at a pressure below 2 MPa and transport in cans.

[0017] Preferably, in step (2), the reaction vessel is a stainless steel reactor, and the temperature of the stainless steel reactor is adjusted using a water bath.

[0018] Preferably, in step (1), the nanoporous medium is column chromatography silica gel or three-dimensional porous graphene oxide.

[0019] Preferably, in step (1), when the moisture content of the nanoporous medium reaches 100% as detected by infrared spectroscopy, the water adsorption is stopped.

[0020] Preferably, in step (2), the synthesized methane-doped methane hydrate decomposes methane gas at room temperature, and water remains in the nanoporous medium and is repeatedly used to synthesize methane-doped methane hydrate.

[0021] Thermodynamic temperature and pressure are key factors in controlling the formation of methane-doped methane hydrate. Under the low-temperature nanosystem, the distance between the oxygen atoms of adjacent water molecules is shortened, causing the hydrogen atoms in the water molecules to break away from the oxygen atoms to form high-speed moving protons. The lower the temperature, the more obvious this effect is; thereby, the more water molecule vacancies in the methane hydrate cage are obtained. The higher the methane gas pressure during the hydrate formation process, the more free methane molecules there are after the hydrate is formed, the more free methane molecules occupy the water molecule vacancies, the higher the doping rate of the hydrate cage, and the higher the gas storage rate increased by doping. Appropriate synthesis temperature and pressure are required to obtain methane-doped methane hydrates with a high gas storage rate. The present invention uses a temperature oscillation method to convert conventional methane hydrates into methane-doped methane hydrates, and the oscillation temperature range is 0o C to -25 o C, synthesis pressure range 4~8MPa.

[0022] Preferably, in step (2), the electricity used by the pre-cooling refrigeration equipment is offshore wind power.

[0023] Preferably, the nanoporous medium absorbs moisture from high humidity air at sea, and the methane gas comes from marine natural gas.

[0024] my country's offshore wind power is developing rapidly. The integration of offshore wind power and high-density marine natural gas storage is expected to become an important model for the long-term sustainable development of the offshore wind power industry, with good prospects for promotion and application. The low-temperature refrigeration electricity for synthesizing methane doped with methane hydrate uses offshore wind power. The marine environment is characterized by high humidity, and the water formed by methane doped with methane hydrate uses nanoporous media to absorb moisture in the high-humidity air at sea to obtain nano water, effectively obtaining offshore fresh water resources.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The present invention utilizes the unique characteristics of water OH bonds breaking at low temperatures in a nanoscale confined space to form vacancy defects of water molecules in hydrate cages and methane molecules doped with methane hydrates, and proposes a method for storing and transporting marine natural gas using a new high-quality, energy-saving, safe and efficient methane-doped methane hydrate; compared with the conventional hydrate method for storing methane in the prior art, the maximum theoretical methane storage volume ratio of methane-doped methane hydrate reaches 1107 v / v, breaking through the maximum gas storage ratio limit of 164 v / v of the conventional hydrate method for storing methane.

[0027] 2. The present invention utilizes a temperature oscillation method to convert the associated conventional methane hydrate into methane-doped methane hydrate. The initial temperature of the temperature oscillation is controlled at -15 o C~-10 o C. Initial pressure range 4~8MPa, temperature oscillation range 0 o C~-25 o C. A series of conditions such as the pressure being below 2 MPa when the synthesis is completed cause the OH bonds of the water molecules in the hydrate cage to break at low temperatures to form water molecule vacancy defects. After the synthesis of conventional methane hydrate, the free methane molecules enter the water molecule vacancies to form methane-doped methane hydrate.

[0028] 3. The present invention adopts clean and low-carbon wind power refrigeration for pre-cooling synthesis, which is green and environmentally friendly, and the water can be recycled without considering water recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a flow chart of a method for storing natural gas by using methane doped with methane hydrate.

[0030] Figure 2 Schematic diagram of an experimental device for synthesizing methane-doped methane hydrate according to the present invention;

[0031] Explanation of the accompanying reference numerals: 1. Data acquisition system; 2. Buffer tank; 3. Stainless steel pipeline; 4. Air bath; 5. Pressure sensor; 6. Temperature sensor; 7. Insulation cotton; 8. Vacuum pump; 9. Stainless steel reactor; 10. Water bath. DETAILED DESCRIPTION

[0032] It will be appreciated by those skilled in the art that the disclosed techniques in the following examples represent techniques that the inventors have found to work well in the practice of the present invention. However, many changes may be made in the disclosed specific embodiments, and still the same or similar results may be obtained without departing from the spirit and scope of the present invention. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0033] Specific implementation methods

[0034] The flow chart of the method for storing natural gas by using methane doped with methane hydrate of the present invention is as follows Figure 1 The schematic diagram of the experimental device for synthesizing methane doped with methane hydrate is shown in Figure 2 As shown, further described by a specific embodiment, the following steps are included:

[0035] 1) High humidity air from the sea is introduced into the nanoporous medium to obtain a water-containing nanoporous medium. When the moisture content reaches 100% using infrared spectroscopy, the introduction of the wet air from the sea is stopped;

[0036] 2) Place the nanoporous medium with a water content of 100% in step 1) into the stainless steel reactor 9, start the vacuum pump 8 to extract the air in the stainless steel reactor 9 and the stainless steel pipeline 3, and adjust the temperature of the water bath 10 to precool the nanoporous medium to -15 o C~-10 o C, and at the same time adjust the air bath 4 to precool the methane gas in the buffer tank 2 to -15 o C~-10 o C, pre-cooling electricity is all offshore wind power, the pressure of the stainless steel reactor 9 and the buffer tank 2 are both within 15MPa, and the temperature control range of the water bath 10 is -30 o C~50 o C, temperature control rate range 0.2-10 o C / min, air bath 4 temperature control range -20 o C~50 oC; the stainless steel pipe 3 connecting the water bath 10 and the air bath 4 is insulated with 3 mm thick rubber-plastic insulation cotton 7, and the electrical signals of the pressure sensor 5 and the temperature sensor 6 are read by the data acquisition system 1 to realize the monitoring and adjustment of the pressure and temperature in the stainless steel reactor 9 and the buffer tank 2;

[0037] 3) Adjust the temperature of the water bath 10 to keep the stainless steel reactor 9 at -15 o C~-10 o C, the methane gas pre-cooled in step 2) is introduced into the reactor, the initial pressure in the reactor reaches 4-8 MPa, the methane-doped methane hydrate is synthesized, and conventional methane hydrate is produced, and the pressure in the stainless steel reactor 9 decreases during the synthesis process;

[0038] 4) The conventional methane hydrate generated in step 3) is converted into methane-doped methane hydrate by temperature oscillation method, and the temperature oscillation range is -25 o C~0 o C, the initial pressure range of the reactor is 4-8 MPa, and the specific steps are: set the initial temperature of the stainless steel reactor 9 to -15 o C~-10 o C, then 2~5 o C / min rate to reduce the temperature of water bath 10, so that the temperature of stainless steel reactor 9 drops to -25 o C and stay for 2-4 hours, the conventional methane hydrate is converted into methane-doped methane hydrate, and the pressure in the stainless steel reactor 9 is further reduced; o C / min rate to raise the temperature of the water bath 10 so that the temperature of the stainless steel reactor 9 rises to 0 o C and stay for 2-4 hours, the conventional methane hydrate is partially decomposed; repeat the above heating and cooling steps until the pressure in the stainless steel reactor 9 drops below 2MPa and no longer decreases, and the synthesis is completed;

[0039] 5) The synthesized samples were heated at -25 to -30 o C is frozen and loaded into storage tanks for storage and transportation; at room temperature, methane-doped methane hydrate and part of the undoped conventional methane hydrate decompose into methane gas.

[0040] Example 1

[0041] Using anhydrous column chromatography silica gel (pore size of about 16 nm, particle size of 0.1~0.45mm), high-humidity air and methane gas as experimental materials, the above steps were used to carry out natural gas hydrate storage and transportation test experiments, including the synthesis, storage and decomposition of methane gas from methane-doped methane hydrate samples.

[0042] 1. Synthesis of methane-doped methane hydrate: expose anhydrous column chromatography silica gel to high humidity air at sea, without stirring, and let it stand for 2 days to ensure that the pores of the column chromatography silica gel fully absorb moisture in the air. After the moisture content reaches 100% by infrared spectroscopy, it no longer absorbs moisture; put the column chromatography silica gel with a moisture content of 100% into a stainless steel reactor 9, start the vacuum pump 8, extract the air in the stainless steel reactor 9 and the stainless steel pipeline 3, and adjust the temperature of the water bath 10 to precool the column chromatography silica gel to -15 o C, and at the same time adjust the temperature of the air bath 4 to precool the methane gas in the buffer tank 2 to -15 o C, pre-cooling electricity is all offshore wind power; adjust the temperature of the water bath 10 to keep the stainless steel reactor 9 at -15 o C, inject pre-cooled methane gas into the kettle, the initial pressure in the kettle is 6 MPa, close the stop valve of the stainless steel reactor 9, start to synthesize methane-doped methane hydrate, and produce conventional methane hydrate, and the synthesis is completed within a few hours; connect the stainless steel pipeline 3 outside the water bath 10 and the air bath 4, and use 3mm thick rubber and plastic insulation cotton 7 for insulation; read the electrical signals of the pressure sensor 5 and the temperature sensor 6 through the data acquisition system 1 to realize the monitoring and adjustment of the pressure and temperature in the stainless steel reactor 9 and the buffer tank 2;

[0043] 2. Converting conventional methane hydrate into methane-doped methane hydrate: Set the initial temperature of the stainless steel reactor 9 to -15 o C, the initial pressure in the kettle is 6 MPa, and the o C / min rate to reduce the temperature of water bath 10, so that the temperature of stainless steel reactor 9 drops to -25 o C for 2 hours, the conventional methane hydrate is converted into methane-doped methane hydrate; then o C / min rate to raise the temperature of water bath 10 so that the temperature of stainless steel reactor 9 rises to 0 o C for 2 hours, the conventional methane hydrate is partially decomposed, and the above-mentioned heating and cooling steps are repeated until the pressure in the stainless steel reactor 9 is lower than 2 MPa and does not drop any more;

[0044] 3. Decomposition of methane-doped methane hydrate: close the water bath 10, slowly raise the temperature of the stainless steel reactor 9 to room temperature, decompose the methane-doped methane hydrate and part of the undoped conventional methane hydrate in the pores of the column chromatography silica gel to form methane gas and water, and the methane gas overflows from the pores of the column chromatography silica gel, and the water stays in the pores of the column chromatography silica gel, which can be repeatedly used to synthesize methane-doped methane hydrate.

[0045] Example 2

[0046] The thickness is 0.55~1.2 nm, the diameter is 0.5~3 μm, and the specific surface area is 200~480 m 2 / g, pore volume 1.3 cm 3 / g of three-dimensional porous graphene oxide, high-humidity air and methane gas were used as experimental materials, and the above steps were used to carry out natural gas hydrate storage and transportation test experiments, including the synthesis, storage and decomposition of methane gas from methane-doped methane hydrate samples.

[0047] 1. Synthesis of methane-doped methane hydrate: Since three-dimensional porous graphene oxide easily absorbs moisture in high-humidity air, the three-dimensional porous graphene oxide is placed in high-humidity air for 2 days to allow the pores of the three-dimensional porous graphene oxide to fully absorb moisture in the high-humidity air; the three-dimensional porous graphene oxide with a moisture content of 100% is placed in a stainless steel reactor 9, and the vacuum pump 8 is started to extract the air in the stainless steel reactor 9 and the stainless steel pipeline 3, and the temperature of the water bath 10 is adjusted to pre-cool the three-dimensional porous graphene oxide to -15 o C, and at the same time adjust the air bath 4 to precool the methane gas in the buffer tank 2 to -15 o C, pre-cooling electricity is all offshore wind power; a water bath 10 is used to keep the temperature of the stainless steel reactor 9 at -15 o C, inject pre-cooled methane gas into the kettle, the initial pressure in the kettle is 4 MPa, close the stop valve of the stainless steel reactor 9, and the conventional methane hydrate and methane-doped methane hydrate in the pores of the three-dimensional porous graphene oxide are synthesized within a few hours; connect the stainless steel pipeline 3 outside the water bath 10 and the air bath 4, use 3mm thick rubber and plastic insulation cotton 7 for insulation, and read the electrical signals of the pressure sensor 5 and the temperature sensor 6 through the data acquisition system 1 to realize the monitoring and adjustment of the pressure and temperature in the stainless steel reactor 9 and the buffer tank 2;

[0048] 2. Converting conventional methane hydrate into methane-doped methane hydrate: Set the initial temperature of the stainless steel reactor 9 to -10 o C, the initial pressure in the kettle is 4 MPa, and the o C / min rate to reduce the temperature of water bath 10, so that the temperature of stainless steel reactor 9 drops to -25 o C for 2 hours, the conventional methane hydrate is converted into methane-doped methane hydrate; then o C / min rate to raise the temperature of water bath 10 so that the temperature of stainless steel reactor 9 rises to 0 o C for 2 hours, the conventional methane hydrate is partially decomposed, and the above-mentioned heating and cooling steps are repeated until the pressure in the stainless steel reactor 9 is lower than 2 MPa and does not drop any more;

[0049] 3. Decomposition of methane-doped methane hydrate: close the water bath 10, slowly raise the temperature of the stainless steel reactor 9 to room temperature, and decompose the methane-doped methane hydrate and some undoped conventional methane hydrate in the pores of the three-dimensional porous graphene oxide in the reactor to form methane gas and water. The methane gas overflows from the pores of the graphene oxide, and the water stays in the pores of the graphene oxide, which can be repeatedly used to synthesize methane-doped methane hydrate.

[0050] Example 3

[0051] The thickness is 0.55~1.2 nm, the diameter is 0.5~3 μm, and the specific surface area is 200~480 m 2 / g, pore volume 1.3 cm 3 / g of three-dimensional porous graphene oxide, high-humidity air and methane gas were used as experimental materials, and the above steps were used to carry out natural gas hydrate storage and transportation test experiments, including the synthesis, storage and decomposition of methane gas from methane-doped methane hydrate samples.

[0052] 1. Synthesis of methane-doped methane hydrate: Since three-dimensional porous graphene oxide is very easy to absorb moisture in high-humidity air, the three-dimensional porous graphene oxide is placed in high-humidity air for 2 days to allow the pores of the three-dimensional porous graphene oxide to fully absorb the moisture in the high-humidity air; the three-dimensional porous graphene oxide with a moisture content of 100% is placed in a stainless steel reactor 9, and the vacuum pump 8 is started to remove the air in the stainless steel reactor 9 and the stainless steel pipeline 3 by vacuuming, and the temperature of the water bath 10 is adjusted to pre-cool the three-dimensional porous graphene oxide to -10 o C, and at the same time adjust the air bath 4 to precool the methane gas in the buffer tank 2 to -10 o C, pre-cooling electricity is all offshore wind power; a water bath 10 is used to keep the temperature of the stainless steel reactor 9 at -10 o C, inject pre-cooled methane gas into the kettle, the initial pressure in the kettle is 8 MPa, close the stop valve of the stainless steel reactor 9, and the conventional methane hydrate and methane-doped methane hydrate in the pores of the three-dimensional porous graphene oxide are synthesized within a few hours; connect the stainless steel pipeline 3 outside the water bath 10 and the air bath 4, use 3mm thick rubber and plastic insulation cotton 7 for insulation, and read the electrical signals of the pressure sensor 5 and the temperature sensor 6 through the data acquisition system 1 to realize the monitoring and adjustment of the pressure and temperature in the stainless steel reactor 9 and the buffer tank 2;

[0053] 2. Converting conventional methane hydrate into methane-doped methane hydrate: Set the initial temperature of the stainless steel reactor 9 to -10 o C, the initial pressure in the kettle is 8 MPa, and the o C / min rate to reduce the temperature of water bath 10, so that the temperature of stainless steel reactor 9 drops to -25 oC for 4 hours, the conventional methane hydrate is converted into methane-doped methane hydrate; then o C / min rate to raise the temperature of water bath 10 so that the temperature of stainless steel reactor 9 rises to 0 o C for 4 hours, the conventional methane hydrate is partially decomposed, and the above-mentioned heating and cooling steps are repeated until the pressure in the stainless steel reactor 9 is lower than 2 MPa and does not drop any more;

[0054] 3. Decomposition of methane-doped methane hydrate: close the water bath 10, slowly raise the temperature of the stainless steel reactor 9 to room temperature, and decompose the methane-doped methane hydrate and some undoped conventional methane hydrate in the pores of the three-dimensional porous graphene oxide in the reactor to form methane gas and water. The methane gas overflows from the pores of the graphene oxide, and the water stays in the pores of the graphene oxide, which can be repeatedly used to synthesize methane-doped methane hydrate.

[0055] The above detailed description is a specific description of a feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the patent protection scope of this case.

Claims

1. A high-density, clean and low-carbon storage method for marine natural gas using offshore wind power, characterized in that: The following steps are involved: (1) Using nanoporous media to absorb moisture from high humidity air at sea to obtain water-containing nanoporous media; (2) Place the water-containing nanoporous medium in step (1) into a reaction vessel and pre-cool to -15 o C~-10 o C, and then inject the pre-cooled to -15 o C~-10 o C of methane gas, the methane gas comes from marine natural gas, the pre-cooling refrigeration equipment uses offshore wind power, and methane-doped methane hydrate is synthesized at an initial pressure of 4-8 MPa and associated conventional methane hydrate, and the synthesis pressure is below 2 MPa; the associated conventional methane hydrate is converted into methane-doped methane hydrate by temperature oscillation, and the range of the temperature oscillation is 0 o C~-25 o C, the initial pressure of the temperature oscillation is 4~8 MPa, specifically including the following steps: setting the initial temperature of the reaction vessel to -15 o C~-10 o C, then cooled to -25 o C, and maintain the temperature for 2 to 4 hours after stabilization, so that the conventional methane hydrate is converted into methane-doped methane hydrate, and the temperature of the reaction vessel is raised to 0 o C, and maintain the temperature for 2 to 4 hours after it stabilizes to partially decompose the conventional methane hydrate, and repeat the steps of heating and cooling until the pressure in the reaction vessel no longer decreases; the synthesized methane-doped methane hydrate is stored in a frozen state.

2. The method according to claim 1, characterized in that In step (2), the cooling or heating rate during the temperature oscillation is 2 to 5 o C / min; repeat the heating and cooling steps until the pressure in the reaction vessel drops below 2 MPa and no longer decreases, and the reaction is completed.

3. The method according to claim 1, characterized in that: In step (2), the synthesized methane doped with methane hydrate is heated to -25 to -30 o C. Store frozen at a pressure below 2 MPa and transport in cans.

4. The method according to claim 1, 2 or 3, characterized in that: In step (2), the reaction vessel is a stainless steel reactor, and the temperature of the stainless steel reactor is adjusted by a water bath.

5. The method according to claim 1, 2 or 3, characterized in that: In step (1), the nanoporous medium is column chromatography silica gel or three-dimensional porous graphene oxide.

6. The method according to claim 1, 2 or 3, characterized in that: In step (1), when the moisture content of the nanoporous medium reaches 100% as detected by infrared spectroscopy, the water adsorption is stopped.

7. The method according to claim 1, 2 or 3, characterized in that: In step (2), the synthesized methane-doped methane hydrate decomposes methane gas at room temperature, and water remains in the nanoporous medium and is repeatedly used to synthesize methane-doped methane hydrate.

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