A hydrate formation promoter, a method for preparing the same, and an application thereof

Abstract

The present application relates to gas hydrate formation and carbon dioxide capture and storage technology field, specifically relates to a kind of hydrate formation accelerant and its preparation method and application, the hydrate formation accelerant is composed of water and L-methionine modified multi-walled carbon nanotube dispersed in water, by washing and drying after acid treatment multi-walled carbon nanotube, add L-methionine, sufficient ultrasonic oscillation, room temperature is fully stirred and adsorbed, again purification and drying, obtain L-methionine modified multi-walled carbon nanotube, again it is dispersed in water, and is configured into.In the application of carbon dioxide hydrate synthesis, using the hydrate formation accelerant, improve hydrate gas consumption while significantly improving hydrate initial formation rate, significantly shorten the overall time of hydrate formation, realize the efficient capture and storage of carbon dioxide, provide broad prospects for the practical application of hydrate technology capture, store carbon dioxide.

Description

Technical Field

[0001] This invention relates to the fields of gas hydrate formation and carbon dioxide capture and storage technology, specifically to a hydrate formation promoter, its preparation method, and its application. Background Technology

[0002] The adverse atmospheric effects of excessive greenhouse gases produced by fossil fuel combustion have spurred in-depth research into clean energy and carbon capture technologies. Global warming caused by greenhouse gases such as carbon dioxide is a significant problem facing humanity, yet fossil fuels still dominate global energy use. Therefore, carbon capture technology is one of the most promising options for reducing carbon dioxide emissions.

[0003] With increasing attention to the greenhouse effect, hydrate capture technology is playing an increasingly important role in carbon dioxide capture and storage. The hydrate CO2 capture method refers to the formation of a special envelope compound from CO2 and water under certain temperature and pressure conditions. Compared with other technologies, using hydrates to capture and store CO2 has advantages such as high separation efficiency (especially in cases of complex compositions), environmental friendliness, and low cost. However, the application of hydrate technology is limited due to the slow formation rate of natural gas hydrates. Currently, CO2 hydrate capture and utilization technologies are still in the laboratory research stage both domestically and internationally. To accelerate hydrate formation, increase the hydrate generation rate, and expand storage capacity, scholars worldwide are constantly exploring optimal methods by adding single or compound promoters. However, different promoters have different promoting effects and cost issues. Therefore, exploring composite additives to compensate for the shortcomings of single additives and developing new green promoters that combine thermodynamic and kinetic advantages is urgently needed. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a hydrate formation promoter, its preparation method and application, which utilizes multi-walled carbon nanotubes and L-methionine to reduce the induction time of hydrate formation and promote hydrate formation, thus solving the problems of slow hydrate formation rate, low gas consumption and long overall hydrate formation time.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a hydrate formation promoter, which is composed of water and L-methionine-modified multi-walled carbon nanotubes dispersed in water, wherein the mass fraction of L-methionine-modified multi-walled carbon nanotubes is 0.0895% to 0.3220%, and the balance is water;

[0007] The L-methionine-modified multi-walled carbon nanotubes were prepared by the following method: after washing and drying the acid-treated multi-walled carbon nanotubes, they were dispersed in phosphate buffer, L-methionine was added, and the mixture was subjected to ultrasonic oscillation, stirred and adsorbed at room temperature, and then purified and dried to obtain L-methionine-modified multi-walled carbon nanotubes, wherein the mass ratio of L-methionine to acid-treated multi-walled carbon nanotubes was 9.259:1.

[0008] Preferably, the multi-walled carbon nanotubes have a purity >95wt%, a diameter distribution between 3 and 15 nm, a length of 3 to 12 μm, and a specific surface area >233 m². 2 / g.

[0009] Preferably, the mass fraction of the L-methionine-modified multi-walled carbon nanotubes is 0.1520% to 0.1970%.

[0010] This invention also provides a method for preparing a hydrate formation promoter, comprising the following steps:

[0011] (1) Weigh out multi-walled carbon nanotubes and immerse them in a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic oscillation and dispersion for 6 hours, wash them with distilled water until neutral and then vacuum dry them.

[0012] (2) The acid-treated multi-walled carbon nanotubes in step (1) were dispersed in a 0.1% phosphate buffer solution, L-methionine was added, and the mixture was ultrasonically vibrated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0013] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was washed and filtered continuously with deionized water and finally dried to obtain L-methionine-modified multi-walled carbon nanotubes.

[0014] (4) The L-methionine-modified multi-walled carbon nanotubes prepared in step (3) are ultrasonically dispersed in high-purity water to obtain a gas hydrate generation promoter. The prepared solution is then encapsulated for later use.

[0015] In the above method for preparing gas hydrate formation promoter, step (2) employs stirring and ultrasonic oscillation to achieve better dispersion of multi-walled carbon nanotubes in the solution.

[0016] Preferably, the mixture after ultrasonic oscillation in step (2) is filtered by membrane micropore vacuum filtration.

[0017] The present invention also provides an application of a hydrate formation promoter in the synthesis of carbon dioxide hydrate. The application steps are as follows: injecting the hydrate formation promoter into a reaction vessel at a temperature of 273.95 to 288.15 K, injecting CO2 gas into the vessel until the pressure is 3.0 to 4.0 MPa, turning on magnetic stirring to carry out the reaction, and finally obtaining a solid hydrate with high gas storage density.

[0018] Preferably, the magnetic stirring rate is 600 r / min, and the reaction time is 6–10 h. Compared with the prior art, the solution provided by this invention has the following beneficial effects:

[0019] (1) The hydrate formation promoter provided by the present invention utilizes the good heat transfer capacity of multi-walled carbon nanotubes and the high specific surface area to provide more nucleation sites for hydrate nucleation, reduce the induction time of hydrate formation process and promote hydrate formation; at the same time, the addition of green and non-toxic L-methionine promoter to the system further increases the gas consumption and the initial gas consumption rate of hydrate, strengthens the mass and heat transfer process of hydrate, which is conducive to heterogeneous nucleation of hydrate and can shorten the overall time of hydrate formation.

[0020] (2) The hydrate formation promoter used in this invention has a small amount of promoter used in promoting hydrate formation, is green and environmentally friendly, economical and efficient, and does not produce foam during decomposition, and can be recycled.

[0021] (3) The hydrate formation promoter used in this invention can significantly improve the initial hydrate formation rate while shortening the induction time of hydrate formation and increasing the gas consumption of hydrate.

[0022] Among them, multi-walled carbon nanotubes have good heat transfer capabilities, which can promote and enhance heat transfer, reduce the inhibitory effect of L-methionine system on ice crystals during cooling, improve mass transfer efficiency, and promote hydrate formation from a kinetic perspective. Attached Figure Description

[0023] Figure 1 The infrared spectra of the hydrate formation promoters prepared in Examples 2, 5 and Comparative Example 2 of the present invention are shown. Detailed Implementation

[0024] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments; however, the embodiments of the present invention are not limited thereto.

[0025] Example 1

[0026] In this embodiment, 0.0625% L-methionine by mass was used as a kinetic promoter.

[0027] Weigh 0.04375 g of L-methionine using an electronic balance. Add L-methionine to 69.95625 g of high-purity water and stir thoroughly to obtain a gas hydrate formation promoter. Package the prepared solution for later use.

[0028] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel, which was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 27.33 minutes, hydrate crystal nuclei were observed in the viewing window.

[0029] Example 2

[0030] In this embodiment, 0.1250% L-methionine by mass was used as a kinetic promoter.

[0031] Weigh 0.0875 g of L-methionine using an electronic balance. Add L-methionine to 69.9125 g of high-purity water and stir thoroughly to obtain a gas hydrate formation promoter. Package the prepared solution for later use.

[0032] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel, which was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 22.67 min, hydrate crystal nuclei were observed in the viewing window.

[0033] Example 3

[0034] In this embodiment, 0.2500% L-methionine by mass was used as a kinetic promoter.

[0035] Weigh 0.175 g of L-methionine using an electronic balance. Add L-methionine to 69.825 g of high-purity water and stir thoroughly to obtain a gas hydrate formation promoter. Package the prepared solution for later use.

[0036] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel, which was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 29.00 min, hydrate crystal nuclei were observed in the viewing window.

[0037] Example 4

[0038] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0039] (1) Weigh 0.0270 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0040] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was ultrasonically vibrated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0041] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained.

[0042] (4) Weigh 0.1064g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.8936g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0043] Application Experiment:

[0044] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath, and the data acquisition system and the cryogenic bath were turned on. Temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize the pressure to 3.50 MPa. Magnetic stirring was then started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 19.67 min, hydrate crystal nuclei were observed in the viewing window.

[0045] Example 5

[0046] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0047] (1) Weigh 0.0450 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0048] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was sonicated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0049] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained, and a portion of the solid was used for characterization and analysis.

[0050] (4) Weigh 0.119g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.881g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0051] Application Experiment:

[0052] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath, and the data acquisition system and the cryogenic bath were turned on. Temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize the pressure to 3.50 MPa. Magnetic stirring was then started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 12.00 min, hydrate crystal nuclei were observed in the viewing window.

[0053] Example 6

[0054] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0055] (1) Weigh 0.0720 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0056] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was sonicated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0057] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained.

[0058] (4) Weigh 0.1379g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.8621g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0059] Application Experiment:

[0060] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath, and the data acquisition system and the cryogenic bath were turned on. Temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize the pressure to 3.50 MPa. Magnetic stirring was then started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 15.00 min, hydrate crystal nuclei were observed in the viewing window.

[0061] Example 7

[0062] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0063] (1) Weigh 0.0450 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0064] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was sonicated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0065] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained.

[0066] (4) Weigh 0.119g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.881g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0067] Application Experiment:

[0068] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 4.00 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 26.00 min, hydrate crystal nuclei were observed in the viewing window.

[0069] Example 8

[0070] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0071] (1) Weigh 0.0450 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h before removing it.

[0072] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was sonicated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0073] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained.

[0074] (4) Weigh 0.119g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.881g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0075] Application Experiment:

[0076] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.00 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 136.00 min, hydrate crystal nuclei were observed in the viewing window.

[0077] Example 9

[0078] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0079] (1) Weigh 0.0450 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0080] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was sonicated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0081] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained.

[0082] (4) Weigh 0.119g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.881g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0083] Application Experiment:

[0084] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 273.55 K, causing hydrate formation. After 96.00 min, hydrate crystal nuclei were observed in the viewing window.

[0085] Example 10

[0086] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0087] (1) Weigh 0.0450 g of multi-walled carbon nanotubes and 0.1250 g of L-methionine using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0088] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-methionine was added, and the mixture was sonicated for 30 min and stirred at room temperature for 24 h to obtain a mixed solution.

[0089] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water. Finally, after drying, L-methionine-modified multi-walled carbon nanotubes were obtained.

[0090] (4) Weigh 0.119g of the L-methionine-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.881g of high-purity water, and disperse them by ultrasonication for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0091] Application Experiment:

[0092] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 275.75 K, causing hydrate formation. After 156.00 min, hydrate crystal nuclei were observed in the viewing window.

[0093] Comparative Example 1

[0094] This comparative example does not use an accelerator for carbon dioxide capture and storage.

[0095] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol reagent, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of pure aqueous solution was injected into the reaction vessel. The reaction vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. When the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 82.00 min, hydrate crystal nuclei were observed in the viewing window.

[0096] Comparative Example 2

[0097] This comparative example uses 0.0450% by mass of multi-walled carbon nanotubes as a kinetic promoter.

[0098] 0.0315 g of multi-walled carbon nanotubes and 69.9685 g of high-purity water were weighed using an electronic balance. The multi-walled carbon nanotubes were dispersed in the high-purity water and ultrasonically dispersed for 30 min to obtain a gas hydrate formation promoter. The prepared solution was then packaged for later use.

[0099] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, causing hydrate formation. After 8.67 minutes, hydrate crystal nuclei were observed in the viewing window.

[0100] Comparative Example 3

[0101] This embodiment provides a hydrate formation promoter, the preparation process of which is as follows:

[0102] (1) Weigh 0.0450 g of multi-walled carbon nanotubes and 0.1250 g of L-tryptophan using an electronic balance. Soak the multi-walled carbon nanotubes in 70 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1. After ultrasonic dispersion for 6 h, wash with distilled water until neutral. Place the black product in a vacuum drying oven and dry at 60 °C for 24 h.

[0103] (2) The acid-treated multi-walled carbon nanotubes were dispersed in 70 mL of 0.1% phosphate buffer, L-tryptophan was added, the mixture was sonicated for 30 min, and stirred at room temperature for 24 h to obtain a mixed solution.

[0104] (3) The mixed solution was allowed to stand and separate into layers. The upper layer was centrifuged at 500 rpm for 30 min. The precipitate was continuously washed and filtered with deionized water and finally dried to obtain L-tryptophan-modified multi-walled carbon nanotubes.

[0105] (4) Weigh 0.119g of the L-tryptophan-modified multi-walled carbon nanotubes prepared in step (3), add them to 69.881g of high-purity water, and ultrasonically disperse them for 20min to obtain a gas hydrate generation promoter. Then, encapsulate the prepared solution for later use.

[0106] Application Experiment:

[0107] This application experiment was conducted in a 250 mL reaction vessel, using carbon dioxide as the gas. Before the experiment, the reaction vessel was repeatedly cleaned at least three times with deionized water and ethanol, and then purged with gas to remove excess gas. A leak test was performed using soapy water; the absence of bubbles indicated good airtightness. Then, 70 g of the prepared solution was injected into the reaction vessel. The vessel was then immersed in a cryogenic bath. Afterward, the data acquisition system and the cryogenic bath were turned on, and temperature and pressure changes were recorded at 2-second intervals. When the temperature inside the vessel reached 288.15 K, CO2 gas was injected to pressurize to 3.50 MPa, and then magnetic stirring was started at 600 r / min. Once the gas reached dissolution equilibrium, the temperature inside the reaction vessel decreased at a rate of 0.15 K / min to the set temperature of 274.95 K, inducing hydrate formation. After 25.00 min, hydrate crystal nuclei were observed in the viewing window. Table 1 shows the induction time t for all experiments. in Cumulative gas consumption G sum The gas consumption rate N in the first 20 minutes after the large-scale formation of hydrates 10 N 20 The time required to reach 90% of the total gas consumption (t) 90 )

[0108]

[0109] As shown in Table 1 for Examples 1, 2, and 3, Example 2 showed better results than Examples 1 and 3 in terms of hydrate induction time, cumulative gas consumption, and gas consumption rate in the first 20 minutes after the large-scale formation of hydrates. This indicates that Example 2 has a better promoting effect. Therefore, the corresponding L-methionine concentration from Example 2 was selected for subsequent experiments. A comparison between Example 5 and Comparative Example 3 shows that the L-methionine-modified multi-walled carbon nanotube solution is superior to the L-tryptophan-modified multi-walled carbon nanotube solution in terms of shortening hydrate induction time, increasing gas consumption, accelerating the formation rate, and shortening the overall time for hydrate formation. Comparing Examples 4, 5, and 6 with Examples 1, 2, and 3 and Comparative Examples 1 and 2, it can be seen that under the same pressure and supercooling conditions, using L-methionine-modified multi-walled carbon nanotube solution as a hydrate formation promoter can effectively improve the carbon dioxide hydrate formation kinetics and promote carbon dioxide hydrate formation. Under these conditions, the hydrate formation induction time is 12.00–19.67 min, which is 76.01%–85.37% shorter than that of pure water; the hydrate formation rate is 250.00–337.50% higher than that of pure water, significantly shortening the induction time of the carbon dioxide hydrate formation process, effectively increasing the cumulative gas consumption and gas consumption rate, and shortening the time to t. 90 .

[0110] As shown in Examples 5, 7, and 8, insufficient driving pressure slows down hydrate nucleation. With increasing pressure, the maximum increase in carbon dioxide hydrate consumption is 31.93%, but excessively high pressure also prolongs hydrate induction time. Examples 5, 9, and 10 show that increased supercooling provides a greater internal driving force for hydrate formation, promoting its development. Under the same experimental conditions, at 274.95 K, the hydrate formation induction time was shortened by 700% and 1200% compared to 273.55 K and 275.75 K, respectively. Therefore, selecting appropriate pressure and temperature for the experiment is crucial.

[0111] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A hydrate formation promoter, characterized by, L-methionine modified multi-walled carbon nanotubes and water, wherein the mass fraction of the L-methionine modified multi-walled carbon nanotubes is 0.0895% to 0.3220%, and the balance is water; The L-methionine modified multi-walled carbon nanotubes are prepared by the following method: after washing and drying, the acid-treated multi-walled carbon nanotubes are dispersed in a phosphate buffer solution, L-methionine is added, and the mixture is fully ultrasonically oscillated, fully stirred at room temperature, and then purified and dried to obtain the L-methionine modified multi-walled carbon nanotubes, wherein the mass ratio of L-methionine to the acid-treated multi-walled carbon nanotubes is 9.259:

1.

2. The hydrate formation promoter according to claim 1, characterized in that, Purity of multi-walled carbon nanotubes > 95 wt%, diameter between 3 and 15 nm, length 3 to 12 μm, specific surface area > 233 m 2 / g.

3. The hydrate formation promoter of claim 1, wherein The mass fraction of the L-methionine modified multi-walled carbon nanotubes is 0.1520% to 0.1970%.

4. A process for the preparation of a hydrate formation promoter according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: (1) multi-walled carbon nanotubes are weighed and soaked in a mixed acid of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, ultrasonically oscillated and dispersed for 6 hours, then washed with distilled water until neutral, and vacuum dried; (2) the acid-treated multi-walled carbon nanotubes of step (1) are dispersed in a 0.1% mass fraction phosphate buffer solution, L-methionine is added, ultrasonically oscillated for 30 minutes, and stirred at room temperature for 24 hours to obtain a mixed solution; (3) the mixed solution is allowed to stand and separate into layers, the upper layer liquid after separation is centrifuged at 500 rpm for 30 minutes, the precipitate is continuously washed and filtered with deionized water, and finally dried to obtain L-methionine modified multi-walled carbon nanotubes; (4) the L-methionine modified multi-walled carbon nanotubes prepared in step (3) are ultrasonically dispersed in high-purity water to obtain a gas hydrate formation promoter, and the prepared solution is packaged for use.

5. The use of the hydrate formation promoter of any one of claims 1-3 or prepared by the method of claim 4 in the synthesis of carbon dioxide hydrate. The application step is: the hydrate formation promoter is injected into a reaction kettle, the temperature is 273.95-288.15 K, CO2 gas is injected into the kettle until the pressure is 3.0-4.0 MPa, magnetic stirring is started to carry out the reaction, and finally high-gas-storage-density solid hydrate is obtained.

6. Use of a hydrate formation promoter according to claim 5, characterized in that The magnetic stirring rate is 600 r / min, and the reaction time is 6-10 hours.

7. Use of a hydrate formation promoter according to claim 6, characterized in that ​

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