KR101360738B1 - A gas hydrate promotor and a method of promoting gas hydrate formation - Google Patents

Abstract

The present invention relates to ionic liquid compounds capable of promoting the production of gas hydrates. The compounds of the present invention are economical because they can convert more gases into gas hydrates in the shortest time under the same temperature and pressure, thereby significantly reducing the cost of producing gas hydrates.

Description

A gas hydrate promotor and a method of promoting gas hydrate formation

The present invention relates to a gas hydrate production promoter and a method for promoting gas hydrate production.

Gas hydrates are a type of inclusion compound and are generally It refers to stable crystals formed by physically bonding gas molecules of low molecular weight, such as methane, carbon dioxide, nitrogen, and natural gas, in a cavity formed of water molecules under high pressure and low temperature conditions. More than 100 objects are currently hydrated by trapping gas molecules, which are hydrate formers or object molecules, within the solid phase lattice of water molecules, which are host molecules that hydrogen bond at low and high pressures. It is known to form

The gas hydrate is generally formed in an atmosphere of low temperature and high pressure, and small gas molecules such as methane, ethane, propane, and carbon dioxide are physically bonded to empty spaces in the lattice structure, and then directly into water and gas at room temperature and normal pressure. Are separated. Since a large amount of gas can be stored in such a gas hydrate lattice, natural gas hydrate present in nature is currently receiving great attention as an energy source, and many studies have been conducted as a means of transporting and storing gas.

In order to use gas hydrate as a means of transport and storage of gas, it must be possible to produce gas hydrates quickly and effectively. In other words, the gas hydrate manufacturing method that satisfies a certain level of low temperature and high pressure conditions and shows a high production rate and a high gas collection amount can suppress the excessive cost in the transportation and storage of gas through the gas hydrate, thereby securing economic efficiency. You can make a big contribution.

For high gas capture and high production rate in the manufacture of gas hydrates The use of materials, ie additives, which can promote the formation of gas hydrates has been attempted. However, the materials used in the prior art have a problem in that the gas storage efficiency is significantly lowered or the time required to reach the desired gas storage capacity instead of lowering the hydrate formation temperature or pressure during gas hydrate formation.

Therefore, there will be a need for the development of gas hydrate production accelerators that can form many gas hydrates in a short time or can form gas hydrates containing more gases.

KR 10-2010-0061000 KR 10-2010-0096210

Hydrate phase equilibria of the guest mixtures containing CO2, N2 and tetrahydrofuran (Fluid Phase Equilibria 185 (2001), 101-109)

It is an object of the present invention to provide an accelerator which can effectively improve the production of gas hydrates.

Another object of the present invention is to provide a method capable of effectively improving gas hydrate production.

The present invention relates to a gas hydrate production accelerator comprising a compound represented by the following formula (1).

[Formula 1]

In Formula 1,

R ₁ and R ₂ are independently straight or branched C ₁ to C ₃ alkyl or straight or branched C ₁ to C ₃ hydroxy alkyl.

The compound represented by Chemical Formula 1 of the present invention includes a morpholium including a substituent in N as a cation, and includes Cl ⁻ as an anion.

In the present invention, the gas hydrate production accelerator means a compound capable of converting the gas hydrate of a large amount of gas at the same time by increasing the production rate of the gas hydrate, preferably increasing the initial gas hydrate production rate rapidly It means a compound that can be.

In the present invention, the gas hydrate production accelerator means a compound capable of increasing the gas storage capacity contained in the pupil of the gas hydrate.

When the gas hydrate of the present invention is used with an accelerator, a larger volume of gas can be obtained in the form stored in the gas hydrate at the same pressure and temperature. That is, the gas hydrate promoter of the present invention can generate a large amount of gas hydrate within a short time under the temperature and pressure conditions inducing gas hydrate production, and at the same time obtain a high gas collection amount per gas hydrate of one molecule. therefore, Gas hydrate formation accelerator of the compound represented by the formula (1) of the present invention can significantly improve the productivity of the manufacturing process It is very efficient economically.

The compound represented by Chemical Formula 1 of the present invention may be N-hydroxyethyl-N-methylmorpholinium chloride represented by the following Chemical Formula 2.

(2)

When using the compound represented by the formula (1) of the present invention it is possible to significantly increase the amount of the maximum gas stored as a gas hydrate under the same pressure and temperature. That is, when the compound represented by Chemical Formula 1 is added, the amount of gas stored as gas hydrate at least about 1.5 times, preferably at least about 3 times, or at least 4 times is higher than that of the gas hydrate without adding the compound. Can be increased.

For example, N-hydroxyethyl-N-methylmorpholinium chloride in the compound represented by Chemical Formula 1 may effectively increase the maximum amount of gas stored in the gas hydride.

In addition, the compound represented by Chemical Formula 1 of the present invention may convert gas into gas hydrate in a short time. That is, when the compound represented by Chemical Formula 1 is added when the gas hydrate is formed, the rate at which gas is collected into the gas hydrate may be increased rapidly as compared with the case where the gas hydrate is not added. For example, N-hydroxyethyl-N-methylmorpholinium chloride in the compound represented by Formula 1 may initially significantly increase the rate at which gas is converted to gas hydride.

The compound represented by Formula 1 of the present invention may promote the production of gas hydrates of various gases. For example, the gas may be a low molecular weight hydrocarbon such as methane, ethane, propane, butane or pentane, nitric acid, carbon dioxide, natural gas or mixtures thereof, preferably methane or natural gas.

The present invention provides a method for promoting gas hydrate production using a compound represented by the following formula (1).

[Formula 1]

In Formula 1,

R ₁ and R ₂ are independently straight or branched C ₁ to C ₃ alkyl or straight or branched C ₁ to C ₃ hydroxy alkyl.

The compound represented by Chemical Formula 1 of the present invention may be N-hydroxyethyl-N-methylmorpholinium chloride represented by the following Chemical Formula 2.

(2)

According to an embodiment of the present invention, the gas hydrate may be generated by adjusting the temperature and pressure of the aqueous solution including water, gas, and the compound represented by Chemical Formula 1.

When the mixture of the compound represented by Formula 1, water, and gas is maintained at an appropriate temperature and pressure according to the type of gas, more gas is hydrated in a shorter time than the case in which the compound represented by Formula 1 is not included. Can be converted to That is, under an aqueous solution containing the compound of Formula 1, gas hydrate may be generated more quickly, and a larger amount of gas may be stored in the gas hydrate at a higher speed.

In order to promote the production of methane hydrate, the temperature and pressure of the aqueous solution containing methane, water and the compound represented by the formula (1) may be set to the temperature and pressure at which the methane hydrate can be produced, respectively. For example, after the aqueous solution is prepared by adding the compound represented by Chemical Formula 1 to water, a gas containing methane is injected into the aqueous solution, and the methane hydrate is set to a temperature and a pressure at which methane hydrate can be produced. Can be generated.

When the compound represented by Chemical Formula 1 is added, at least 1.5 times, preferably 4 times or more, of methane may be converted into methane hydrate at the same time as compared with the case where the compound represented by Chemical Formula 1 is not added. That is, more methane can be converted to methane hydrate in less time under the same temperature and pressure.

The compound represented by Formula 1 may be included in 2 to 50,000ppm with respect to water, preferably 5 to 20,000ppm, more preferably 5 to 2,000ppm.

In the gas hydrate manufacturing method of the method of the present invention, in addition to the gas hydrate production accelerator represented by the formula (1), other gas hydrate production accelerators may be further used. For example, a gas hydrate generation promoter that can be used with the gas hydrate generation promoter represented by Formula 1 is alkylpolyglucoside (APG) sodium dodecyl benzene sulfonate (SDBS), potassium oxalate monohydrate (POM), linear alkyl benzene sulfonate (LABS) CTAB (Cationic Surfactant Cetyl Trimethyl Ammonium Bromide), Butanesulfonic Acid Sodium Salt (CH ₃ (CH ₂ ) ₃ SO ₃ Na), 1-octadecanesulfonic acid sodium salt (CH ₃ (CH ₂ ) 17SO ₃ Na), Gemini surfactant or these It may be a mixture of.

In the production method of the present invention, the compound represented by Formula 1 may be used to promote the generation of gas hydrates of various gases. For example, the gas may be a low molecular weight hydrocarbon such as methane, ethane, propane, butane or pentane, nitric acid, carbon dioxide, natural gas or mixtures thereof, preferably methane or natural gas.

The compounds of the present invention can promote the production of gas hydrates and convert more gases to gas hydrates at a faster time under the same temperature and pressure. In addition, the same level of effect can be expected at low concentrations compared to conventional accelerators, and when introduced at a similar concentration, it shows a significantly lower induction time. As a result, the gas can be stored in the gas hydrate with high efficiency even if the temperature and pressure to form the gas hydrate can be maintained for a small time, thereby significantly reducing the time and cost for producing the gas hydrate.

1 is a diagram showing N-hydroxyethyl-N-methylmorpholinium chloride ¹ H-NMR data.
Figure 2 shows the amount of gas converted to gas hydrate over time under the compounds of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

In addition, the reagents and solvents mentioned below were purchased from Sigma-Aldrich Korea, unless otherwise specified, and the ¹ H-NMR data was measured by Bruker's Avance 400FT-NMR (400 MHz).

Example: Preparation of N-hydroxyethyl-N-methylmorpholinium chloride

In a nitrogen atmosphere, 200 mL of acetonitrile (Junsei, Japan) and 49.6 mL (0.5 mol) of 1-methylmorpholinium (Fluka) were mixed. 36.5 mL (0.55 mol) of 2-chloroethanol (Adrich) was added dropwise to the mixture. The solution was stirred under 75 ± 5 ° C. atmospheric nitrogen atmosphere for about 48 hours and then stored at 4 ° C. for 12 hours to form crystals. After removing the supernatant, it was dried using a vacuum rotary evaporator at 0.2 atmosphere of about 35 ℃ ± 5 ℃ for 12 hours to remove the solvent from the crystal. To remove impurities, the dried crystals were dissolved in 100 mL of acetone and stirred at 1 atmosphere of 25 ° C. for 30 minutes. After storage at 4 ° C. for 12 hours to form crystals again, the supernatant was removed, and dried using vacuum rotary evaporator at 0.2 at about 35 ° C. for 12 hours. Dissolution in acetone, crystal formation and drying using a vacuum rotary evaporator were carried out three more times to give N-hydroxyethyl-N-methylmorpholinium chloride in a yield of 60% by weight. NMR data of the N-hydroxyethyl-N-methylmorpholinium chloride is shown in FIG. 1.

¹ H-NMR (400 MHz, DMSO): 3.28 (s, 3H), 3.49-3.60 (m, 4H), 3.65-3.67 (t, 2H), 3.85 (s, 2H), 3.92-3.94 (t, 4H) , 5.773 (s, 1H)

Experimental Example 1 Measurement of Gas Hydrate Production with Time

1. Preparation of experimental device

A high pressure reactor having an internal volume of about 350 cc made of 316 stainless steel was prepared. The high pressure reactor was placed in a water bath equipped with an external cooler to control the temperature. A sapphire observation window is positioned on the upper part of the high pressure reactor to check whether the hydrate is formed therein, and a pressure transducer and a thermocouple are installed to measure the temperature and pressure inside the high pressure reactor. The pressure inside the reactor was controlled by supplying gas from the outside through a mass flow controller. When the gas hydrate is formed, the internal pressure is lowered and an additional amount of gas consumed by the gas hydrate is injected through the mass flow regulator to maintain the pressure constant. The amount was used to calculate the amount of gas trapped in gas hydrate form.

2. Gas hydrate production

An aqueous solution was prepared by adding compound N-hydroxyethyl-N-methylmorpholinium chloride prepared in Example to 90 g of water. The aqueous solution was placed in a high pressure reactor and the high pressure reactor was sealed. The air remaining in the high pressure reactor was removed and methane gas was injected to adjust the pressure and temperature inside the high pressure reactor to 70 atm and 1 ° C. When methane hydrate starts to form, the pressure inside the high pressure reactor is reduced because methane is trapped in the hydrate, and the methane hydrate is continuously discharged through a mass flow controller to maintain a constant pressure of 70 atm. Gas was injected. The experiment was stopped when a constant pressure was maintained even without injecting the gas.

The N-hydroxyethyl-N-methylmorpholinium chloride was added to 20ppm, 50ppm, 100ppm, 500ppm, 1,000ppm, 5,000ppm and 20,000ppm with respect to 90g of water, respectively, and the N-hydroxy The experiment was performed without adding ethyl-N-methylmorpholinium chloride.

N-hydroxyethyl-N-methylmorpholinium chloride is shown in Figure 2 above the cumulative amount of gas injected through the mass flow controller at each dose.

As can be seen in FIG. 2, when the N-hydroxyethyl-N-methylmorpholinium chloride is added, the amount of gas injected from the outside increases with time, and thus N-hydroxyethyl-N More methane was trapped in the hydrates when methylmorpholinium chloride was administered. Specifically, even when a very small amount of 20 ppm of N-hydroxyethyl-N-methylmorpholinium chloride was added, about the same time as compared to the case where N-hydroxyethyl-N-methylmorpholinium chloride was not added N-hydroxyethyl-N-methylmorpholinium chloride when more than twice as much methane was converted to methane hydrate form and N-hydroxyethyl-N-methylmorpholinium chloride was added at a concentration of 1000 ppm At about the same time, more than five times as much methane was converted to the methane hydrate form compared to the case where no addition was made.

From this, it was found that a large amount of methane was trapped in the hydrate at the same time by the addition of N-hydroxyethyl-N-methylmorpholinium chloride.

Experimental Example 2 Induction Time of Gas Hydrate Generation Measure

1. Preparation of experimental device

A system including the same high pressure reactor and water bath as that used in Experimental Example 1 was prepared.

2. Measurement of induction time of methane hydrate formation

An aqueous solution containing the compound N-hydroxyethyl-N-methylmorpholinium chloride prepared in Example in 90 g of water was prepared. The aqueous solution was placed in a high pressure reactor and the high pressure reactor was sealed. The air remaining in the high pressure reactor was removed and methane gas was injected to adjust the pressure inside the high pressure reactor to 70 atm.

After the high pressure reactor was placed in a temperature control tank, the pressure and temperature inside the high pressure reactor were measured in real time using a pressure gauge and a thermometer connected to the high pressure reactor.

After setting the temperature of the high-pressure reactor to 0.5 ℃, the solution was maintained at a constant temperature and the rotation speed of the stirrer was fixed to 400 RPM so that the N-hydroxyethyl-N-methylmorpholinium chloride can be uniformly mixed The solution was continuously mixed by operating the stirrer.

Confirmed while continuously measuring the pressure and temperature inside the autoclave in rapid temperature rise and the pressure drop point and time by measuring the time of this time from the time of stirrer rotation starts it takes to start the methane hydrate is generated, the generated induction time ( induction time) was measured.

The N-hydroxyethyl-N-methylmorpholinium chloride was added to 20ppm, 50ppm, 100ppm, 500ppm, 1,000ppm, 5,000ppm, 10,000ppm and 20,000ppm with respect to 90g of water, and the experiment was performed. Table 1 shows.

In addition, the same experiment was conducted for an aqueous solution containing 20 ppm, 100 ppm, 200 ppm, 500 ppm, 1,000 ppm, 10,000 ppm, and 20,000 ppm of sodium dodecyl sulfage (SDS), which is conventionally known as a hydrate generation promoter. The time at which methane hydrate was produced was measured and the results are shown in Table 1 below.

[Table 1]

As can be seen in Table 1, the compounds according to the present invention had earlier or similar times when methane hydrates began to be produced compared to SDS.

As can be seen in the above experiments, the compounds of the present invention were able to convert more gases into gas hydrates in a faster time, and the time it took for gas hydrates to start to be produced was faster than that of the conventional gas hydrate production accelerator SDS. .

From this it can be seen that the compounds according to the present invention are excellent gas hydrate production promoters.

Claims (9)

Gas hydrate production accelerator comprising a compound represented by the formula (1).
[Chemical Formula 1]

In Formula 1,
R ₁ and R ₂ are independently straight or branched C ₁ to C ₃ alkyl or straight or branched C ₁ to C ₃ hydroxy alkyl. According to claim 1, wherein the compound represented by the formula (1)
A gas hydrate production promoter that is N-hydroxyethyl-N-methylmorpholinium chloride. The gas hydrate formation promoter of claim 1, wherein the gas is methane or natural gas. A method for promoting the production of gas hydrates using a compound represented by the following formula (1).
[Chemical Formula 1]

In Formula 1,
R ₁ and R ₂ are independently straight or branched C ₁ to C ₃ alkyl or straight or branched C ₁ to C ₃ hydroxy alkyl. The method of claim 4, wherein the compound represented by Chemical Formula 1 is N-hydroxyethyl-N-methylmorpholinium chloride. The method of claim 4, wherein the gas is methane or natural gas. 5. The method of claim 4,
Preparing an aqueous solution including the compound represented by Chemical Formula 1, water, and gas; And
Forming a gas hydrate in said aqueous solution. The method of claim 7, wherein preparing the aqueous solution,
Adding a compound represented by Chemical Formula 1 to water; And
Injecting a gas into water containing the compound represented by the formula (1) comprising the step of promoting gas hydrate production. 8. The method of claim 7, wherein the gas hydrate formation promoter is added to the water at a rate of 5 ppm to 2,000 ppm.

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