KR102489316B1 - Thermodynamic promoter for clathrate hydrate and clathrate hydrate including the same - Google Patents

Abstract

The present application relates to a clathrate hydrate, including a thermodynamic promoter for clathrate hydrate and a thermodynamic promoter for the clathrate hydrate.

Description

Thermodynamic promoter for clathrate hydrate and clathrate hydrate containing the same

The present application relates to a clathrate hydrate, including a thermodynamic promoter for clathrate hydrate and a thermodynamic promoter for the clathrate hydrate.

Consisting of a hydrogen-bonded water framework and guest molecules, clathrate hydrates are a well-known type of inclusion compound consisting mainly of corresponding water molecules and gas molecules as host and guest components. )to be. Clathrate hydrate is a clathrate compound formed by surrounding small gas molecules such as CH ₄ and CO ₂ with water molecules through hydrogen bonds. Since clathrate hydrates of the common type are composed primarily of water, CH ₄ /H ₂ /natural gas storage, CO ₂ capture and storage, gas separation, desalination, air conditioning, and sustainable use, including the use of functional materials, Various potentials for hydrate-based technologies have long been proposed.

Due to the low thermodynamic stability of the clathrate hydrate material itself, a solution capable of storing the energy gas in a low-pressure environment at a temperature near room temperature is essential. The only way to increase thermodynamic stability is to add a small amount of an additive called a promoter, and a promoter that can increase thermodynamic stability is called a thermodynamic promoter.

To date, various co-guest materials have been widely evaluated as promoters to improve the formation conditions or kinetics of gas hydrates. Among many conventional promoters, tetrahydrofuran (THF) and cyclopentane (CP) have (1) a strong ability to raise the dissociation temperature by about 20 K at a given pressure, and (2) even in the absence of a gaseous component. It has attracted particular interest due to its advantages including its ability to form sII structures, (3) the relatively low reactivity and high stability of the compound itself, and (4) its relatively good accessibility.

There are three typical structures of gas clathrate hydrates: sI, sII, and sH. Pure methane clathrate hydrate has a sI structure and can store 180 cm ³ of methane per 1 cm ³ of clathrate hydrate (180 v/v). In most cases, introduction of a promoter improves thermodynamic stability, but reduces the theoretical storage capacity by 15% to 30% because the structure of CH ₄ hydrate (sI) undergoes a phase change to sII or sH. When THF or CP is added, the sII structure is changed, and the large cage (hereinafter "sII-L") of the two types of cages is occupied, and methane gas is small cage (hereinafter "sII"). -S") can only enter the cage. Therefore, the gas storage capacity inevitably decreases. Assuming that methane molecules enter all sII-S cages, the theoretical gas storage capacity is 110 v/v. However, when THF or CP was added, the actual gas storage was found to be up to 70 v/v, which is because some sII-S cages are empty without methane molecules.

The figure below is the lattice structure of sII hydrate formed upon addition of a promoter:

.

.

Guest molecules added artificially are referred to as large guest molecules (LGM) or large molecule guest substances (LMGS) because they are larger in size than gaseous guest compounds (energy gases). An important objective of using LGMs, especially in the engineering and industrial applications of hydrates, is to minimize the total amount of energy consumed when using hydrates by enhancing the conditions for gas hydrate formation and preservation.

In terms of guest distribution, most sII gas hydrates containing LGMs are classified as “double” hydrates, since the large (sII-L) and small (sII-S) cages are mainly occupied by LGMs and gas components, respectively. do. On the other hand, sII hydrates that are gas-free and stabilized with only the LGM component are classified as “simple” hydrates, and the LGMs are simply referred to as “simple sII formers” or “simple formers”. In general, gas hydrates containing simple sII formers exhibit much higher levels of thermodynamic stability compared to those formed with conventional LGMs. For example, under a pressure of about 40 bar, the dissociation temperature of furan + CH ₄ (~295 K), or tetrahydrofuran (THF) + CH ₄ (~297 K) is pyrrolidine + CH ₄ hydrate (~287 K). K) is significantly higher than As another example, at about 80 bar, the stable region of 1,3-dioxane + CH ₄ hydrate (~ 297 K) is larger than that of cyclohexane (CH) + CH ₄ hydrate (~ 290 K). In addition, simple hydrates of LGMs are expected to have a variety of applications because they do not require pressurized gas and have excellent guest configuration flexibility (i.e., tuning).

Numerous LGMs have been proposed over nearly a century, but few of them have been found to be simple sII formers, except for halogenated organics such as chlorofluorocarbons (CFCs). Since the simple hydrate structure of tetrahydropyran (THP) was reported through single crystal diffraction, no new simple sII former has been found.

[Non-Patent Document] J. Chem. Eng. Data 2002, 47, 313-315 (2001.12.19)

The present application intends to provide a clathrate hydrate comprising a thermodynamic promoter for clathrate hydrate and a thermodynamic promoter for the clathrate hydrate.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

A first aspect of the present application is a compound represented by Formula 1, 1,2,3,4-diepoxybutane, 1,2-epoxycyclopentane, 1,3-epoxycyclopentane, 2,3-epoxy For clathrate hydrates comprising at least one compound selected from tetrahydrofuran, 3,4-epoxytetrahydrofuran, 1,2-epoxycyclohexane, 1,3-epoxycyclohexane and 1,4-epoxycyclohexane A thermodynamic promoter is provided:

[Formula 1]

;

;

In Formula 1, R ¹ _, R ² _, R ³ _, and R ⁴ are each independently hydrogen or a C _1-4 linear or branched alkyl group, and the C _1-4 linear Or the branched alkyl group is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl or tert-butyl, provided that R Except that ¹ _, R ² _, R ³ _, and R ⁴ are simultaneously hydrogen.

A second aspect of the present application provides a clathrate hydrate comprising a thermodynamic promoter for clathrate hydrate according to the first aspect of the present application.

A third aspect of the present application provides a gas capture method comprising using a clathrate hydrate comprising a thermodynamic promoter for clathrate hydrate according to the first aspect of the present application.

According to the embodiments of the present application, the thermodynamic stability and storage capacity of the clathrate hydrate may be improved by using the novel thermodynamic promoter for the clathrate hydrate.

According to the embodiments of the present application, the gas such as CH ₄ , H ₂ , N ₂ , or CO ₂ is included in the lattice made of water molecules of the clathrate hydrate, and the gas can be stored at room temperature and low pressure without special cooling. .

According to embodiments herein, the clathrate hydrate may be used for hydrate-based energy storage.

According to embodiments of the present application, the clathrate hydrate has a low vapor pressure of about 1 kPa to about 10 kPa (about 0.01 atm to about 0.1 atm) at a temperature of about 15 ° C to about 30 ° C, so it can be used repeatedly.

According to embodiments of the present application, the storage capacity of the clathrate hydrate is about 70% or more of the theoretical gas storage capacity.

According to embodiments of the present application, when using ECP (epoxycyclopentane), ETHF (epoxytetrahydrofuran), 14ECH (1,4-epoxycyclohexane), and 12ECH (1,2-epoxycyclohexane) promoters, the dissociation temperature of CH ₄ hydrate is improved has the effect of In particular, 14ECH exhibits a dissociation temperature close to that of conventional CP and THF, and ECP can act as a strong promoter showing a significantly higher dissociation temperature than conventional CP and THF. Specifically, for example, the promotion effect may increase in the order of ETHF < 12ECH < 14ECH < THF/CP < ECP.

According to embodiments herein, compared to conventional CP hydrate and THF hydrate, which exhibit toxicity, ECP, ETHF, 14ECH, and 12ECH clathrate hydrate are less toxic and have a higher flash point, making them physically safer and more environmentally friendly.

According to embodiments of the present application, when using ECP, ETHF, 14ECH, and 12ECH clathrate hydrates, they have excellent gas absorption conditions compared to conventional CP hydrates and THF hydrates.

According to the embodiments of the present application, when using ECP, ETHF, 14ECH, and 12ECH clathrate hydrates, thermodynamic stability and storage capacity are excellent compared to conventional CP hydrates and THF hydrates.

According to the embodiments of the present application, when using ECP, ETHF, 14ECH, and 12ECH clathrate hydrate, it exhibits an excellent promotion effect compared to conventional CP hydrate and THF hydrate.

1 is a graph showing high-resolution powder diffraction (HRPD) patterns of (a) ECP + CH ₄ and (b) ECP + H ₂ hydrate (at 150 K) in one embodiment of the present application.
Figure 2 shows the equilibrium PT conditions of (a) CH ₄ hydrate and (b) H ₂ hydrate containing THF, CP and ECP, respectively, according to the stoichiometric composition (X _LGM = 0.056) in one embodiment of the present application. is the graph shown.
Figure 3, in one embodiment of the present application, (a) THF molecule, (b) CP molecule, and (c) showing the geometric structure of the ECP molecule.
4 shows Raman spectra of (a) ECP + CH ₄ hydrate and (b) ECP + H ₂ hydrate measured at 123 K and atmospheric pressure, respectively, according to an embodiment of the present application.
5 shows (a) solid-state ¹³ C NMR of ECP + CH ₄ hydrate and (b) ¹ H NMR (at 210 K) of ECP + H ₂ hydrate, according to an example of the present disclosure.
Figure 6, in one embodiment of the present application, ECP + H ₂ O hydrate measured at 150 K shows the HRPD pattern.
7 shows (a) lattice parameter and (b) normalized lattice parameter (the lattice parameter at 150 K is set to a ₀ ) according to temperature in the case of ECP + H ₂ O hydrate in one embodiment of the present application. ) is a graph showing
8 shows a full range ¹³ C NMR spectrum of ECP + CH ₄ hydrate measured at 210 K in one embodiment of the present application.
9 shows a PT trajectory measured by a formation/dissociation process of ECP + CH ₄ hydrate in an embodiment of the present disclosure.
10 is a schematic diagram of a hydrate-based energy storage (HBES) using an ECP in one embodiment of the present disclosure.
Figure 11, in one embodiment of the present application, shows the equilibrium PT conditions (X _LGM = 0.0556) of CH ₄ hydrate including various promoters.
12 shows optimized geometries of (a) ETHF, (b) 14ECH, (c) 12ECH, (d) THF and (e) CH in one embodiment of the present application.
13 shows HRPD and powder X-ray diffraction (PXRD) patterns of (a) ETHF, (b) 14ECH, and (c) 12ECH + CH ₄ hydrate in one embodiment of the present application.
14 shows (a) solid-state ¹³ C NMR and (b) Raman spectrum of ETHF, 14ECH and 12ECH + CH ₄ hydrate according to an example of the present application.
15 shows the equilibrium PT conditions (X _LGM = 0.0556) of N ₂ hydrate including various promoters in one embodiment of the present application.
16 shows a Raman spectrum of LGM + N ₂ hydrate measured at 123 K according to an embodiment of the present disclosure.
17 shows a PXRD pattern of 14ECH + H ₂ O hydrate (no gas) at 150 K according to an embodiment of the present disclosure.
18 shows (a) ¹³ C NMR peak and (b) COC vibrational band of 14ECH molecule in one embodiment of the present application.
19 shows several major phase transitions induced by temperature at atmospheric pressure in an embodiment of the present application.
20 shows the PT trajectory measured by the formation and dissociation process of 14ECH + CH ₄ hydrate in one embodiment of the present application.

Hereinafter, embodiments of the present application will be described in detail so that those skilled in the art can easily practice with reference to the accompanying drawings. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. And in order to clearly describe the present application in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is said to be “connected” to another part, this includes not only the case of being “directly connected” but also the case of being “electrically connected” with another element in between. do.

Throughout the present specification, when a member is said to be located “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

Throughout the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated. As used throughout this specification, the terms "about", "substantially", and the like, are used at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and do not convey the understanding of this application. Accurate or absolute figures are used to help prevent exploitation by unscrupulous infringers of the disclosed disclosure. The term "step of (doing)" or "step of" as used throughout the present specification does not mean "step for".

Throughout this specification, the term “combination(s) of these” included in the expression of the Markush form means a mixture or combination of one or more selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of the above components.

Throughout this specification, reference to “A and/or B” means “A or B, or A and B”.

Hereinafter, embodiments and embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the present disclosure may not be limited to these embodiments and examples and drawings.

A first aspect of the present application is a compound represented by Formula 1, 1,2,3,4-diepoxybutane, 1,2-epoxycyclopentane, 1,3-epoxycyclopentane, 2,3-epoxy For clathrate hydrates comprising at least one compound selected from tetrahydrofuran, 3,4-epoxytetrahydrofuran, 1,2-epoxycyclohexane, 1,3-epoxycyclohexane and 1,4-epoxycyclohexane A thermodynamic promoter is provided:

[Formula 1]

;

;

R ¹ _, R ² _, R ³ _, and R ⁴ are each independently hydrogen or a C _1-4 linear or branched alkyl group, and the C _1-4 linear or branched alkyl group (Alkyl) group is selected from methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group or tert-butyl group, provided that R ¹ _, R ² _, Except where R ³ _, and R ⁴ are both hydrogen.

In one embodiment of the present application, the compound is 1,2-epoxybutane, 2,3-epoxybutane, 1,2-epoxy-2-methylpropane, 3,3-dimethyl-1,2-epoxybutane, 1 ,2,3,4-diepoxybutane, 1,2-epoxycyclopentane, 1,3-epoxycyclopentane, 2,3-epoxytetrahydrofuran, 3,4-epoxytetrahydrofuran, 1,2 - It may include one or more compounds selected from epoxycyclohexane, 1,3-epoxycyclohexane, and 1,4-epoxycyclohexane, but is not limited thereto. In one embodiment of the present application, the compound is 1,2-epoxybutane, 2,3-epoxybutane, 1,2-epoxy-2-methylpropane, 3,3-dimethyl-1,2-epoxybutane, 1 At least one selected from 2,3,4-diepoxybutane, 1,2-epoxycyclopentane, 3,4-epoxytetrahydrofuran, 1,2-epoxycyclohexane, and 1,4-epoxycyclohexane It may contain compounds.

In one embodiment of the present application, the thermodynamic promoter for the clathrate hydrate may be a simple hydrate forming promoter, but is not limited thereto.

Here, a hydrate containing one type of guest molecule is called a simple hydrate. As shown in the left figure below, a promoter capable of producing sII hydrate without gas molecules is referred to as a simple hydrate promoter. A hydrate containing two types of guest molecules is called a double hydrate, and as shown in the right figure below, the promoter molecule occupies the sII-L cage and the gas molecule occupies the sII-S cage. This type of promoter cannot make hydrates without a gas molecule.

In one embodiment of the present application, the compound corresponding to the thermodynamic promoter for the clathrate hydrate may be a large guest molecule occupying a large cage (sII-L), but is not limited thereto.

A second aspect of the present application provides a clathrate hydrate comprising a thermodynamic promoter for clathrate hydrate according to the first aspect of the present application.

In one embodiment of the present application, the clathrate hydrate may be reusable, but is not limited thereto.

In one embodiment of the present application, the clathrate hydrate may be formed at a temperature of about 15 ° C to about 30 ° C and a pressure of about 20 to about 90 atm. In one embodiment of the present application, the formation temperature of the clathrate hydrate is about 15 ° C to about 30 ° C, about 15 ° C to about 25 ° C, about 17 ° C to about 27 ° C, about 17 ° C to about 25 ° C, about 20 °C to about 27 °C, or about 20 °C to about 25 °C, but is not limited thereto. In one embodiment of the present application, the formation pressure of the clathrate hydrate is about 20 atm to about 90 atm, about 20 atm to about 80 atm, about 20 atm to about 70 atm, about 20 atm to about 60 atm, about 20 atm It may be from about 50 atm to about 50 atm, from about 20 to about 40 atm, or from about 20 to about 30 atm, but is not limited thereto.

In one embodiment of the present application, the clathrate hydrate has a low vapor pressure of about 1 kPa to about 10 kPa (about 0.01 atm to about 0.1 atm) at a temperature of about 15 ° C to about 30 ° C. However, it is not limited thereto.

In one embodiment of the present application, the clathrate hydrate may be used for hydrate-based energy storage, but is not limited thereto.

In one embodiment of the present application, gas may be collected in a lattice composed of water molecules of the clathrate hydrate, but is not limited thereto.

In one embodiment of the present application, the thermodynamic stability and storage capacity of the clathrate hydrate may be improved by using a novel thermodynamic promoter for the clathrate hydrate.

In one embodiment of the present application, the clathrate hydrate may be used for hydrate-based energy storage.

A third aspect of the present application provides a gas collection method comprising collecting gas using a clathrate hydrate comprising a thermodynamic promoter for clathrate hydrate according to the first aspect of the present application.

In one embodiment of the present application, the gas collected by the gas collecting method may be CH ₄ , H ₂ , N ₂ , or CO ₂ , but is not limited thereto.

According to the embodiments of the present application, the gas such as CH ₄ , H ₂ , N ₂ , or CO ₂ is included in the lattice made of water molecules of the clathrate hydrate, and the gas can be stored at room temperature and low pressure without special cooling. .

In one embodiment of the present application, the gas may be collected in the clathrate hydrate at a temperature of about 15 ° C to about 30 ° C and a pressure of about 20 to about 90 atm. In one embodiment of the present application, the gas is about 15 ℃ to about 30 ℃, about 15 ℃ to about 25 ℃, about 17 ℃ to about 27 ℃, about 17 ℃ to about 25 ℃, about 20 ℃ to about 27 ℃ , Or it may be collected in the clathrate hydrate at a temperature of about 20 ° C to about 25 ° C, but is not limited thereto. In one embodiment of the present application, the gas is about 20 to about 90 atm, about 20 to about 80 atm, about 20 to about 70 atm, about 20 to about 60 atm, about 20 to about 50 atm , It may be collected in the clathrate hydrate at about 20 atm to about 40 atm, or about 20 atm to about 30 atm, but is not limited thereto.

In one embodiment of the present application, CH ₄ is stored at a pressure of about 50 bar to about 70 bar, H ₂ is at a pressure of about 80 bar to about 100 bar, and N ₂ is stored at a pressure of about 60 bar to about 100 bar. It may be, but is not limited thereto. In one embodiment of the present application, CH ₄ is about 50 bar to about 70 bar, about 50 bar to about 68 bar, about 50 bar to about 66 bar, about 52 bar to about 70 bar, about 52 bar to about 68 bar , It may be stored at a pressure of about 52 bar to about 66 bar, about 54 bar to about 70 bar, about 54 bar to about 68 bar, or about 54 bar to about 66 bar, but is not limited thereto. Specifically, CH ₄ is most preferably stored at a moderate pressure of 55 bar to about 65 bar. In one embodiment of the present application, H ₂ is about 80 bar to about 100 bar, about 80 bar to about 98 bar, about 80 bar to about 96 bar, about 82 bar to about 100 bar, about 82 bar to about 98 bar , It may be stored at a pressure of about 82 bar to about 96 bar, about 84 bar to about 100 bar, about 84 bar to about 98 bar, about 84 bar to about 96 bar, but is not limited thereto. Specifically, H ₂ is most preferably stored at a pressure of 85 bar to about 95 bar. In one embodiment of the present application, N ₂ is about 60 bar to about 100 bar, about 60 bar to about 95 bar, about 60 bar to about 90 bar, about 60 bar to about 85 bar, about 60 bar to about 80 bar , It may be stored at a pressure of about 65 bar to about 100 bar, about 65 bar to about 95 bar, about 65 bar to about 90 bar, about 65 bar to about 85 bar, or about 65 bar to about 80 bar, It is not limited thereto.

In one embodiment of the present application, the storage capacity of the gas may be about 70% or more of the theoretical gas storage capacity, but is not limited thereto. In one embodiment of the present application, the storage capacity of the gas may be about 70% or more, about 80% or more, about 90% or more, about 95% or more, or about 99% or more of the theoretical gas storage capacity, but is limited thereto. it is not going to be

The experimental maximum storage capacity of CH ₄ when using THF and CP of the prior art is about 66% of the theoretical storage capacity, which corresponds to 70 v/v. The hydrogen storage in THF + H ₂ or CP + H ₂ clathrate hydrates is even lower, with an experimental maximum of only about 50% of the theoretical storage, ie about 50 v/v.

In one embodiment of the present application, the gas may be stored up to about 100 v / v, but is not limited thereto.

In one embodiment of the present application, additional cooling may not be required to collect the gas, but is not limited thereto.

All conventional clathrate hydrates have different conditions for making the clathrate hydrate (forming conditions) and dissociating conditions (equilibrium conditions). Since the temperature at which clathrate hydrates are formed (formation temperature) is much lower than the temperature at which they dissociate (equilibrium temperature), there is a disadvantage in that cooling to a temperature much lower than the equilibrium temperature is required to form hydrates.

In one embodiment of the present application, the gas collecting method may additionally include at least one of collecting, storing, transporting, or dissociating the gas, but is not limited thereto.

According to embodiments of the present application, when using the ECP, ETHF, 14ECH, and 12ECH promoters, the dissociation temperature of CH ₄ hydrate is improved. In particular, 14ECH exhibits a dissociation temperature close to that of conventional CP and THF, and ECP can act as a strong promoter showing a significantly higher dissociation temperature than conventional CP and THF. Specifically, for example, the promotion effect may increase in the order of ETHF < 12ECH < 14ECH < THF/CP < ECP.

In one embodiment of the present application, compared to conventional CP hydrate and THF hydrate, which exhibit toxicity, ECP, ETHF, 14ECH, and 12ECH clathrate hydrate are physically safer and more environmentally friendly due to their low toxicity and high flash point.

In one embodiment of the present application, when using ECP, ETHF, 14ECH, and 12ECH clathrate hydrates, they have excellent gas absorption conditions compared to conventional CP hydrates and THF hydrates.

In one embodiment of the present application, when using ECP, ETHF, 14ECH, and 12ECH clathrate hydrate, thermodynamic stability and storage capacity are excellent compared to conventional CP hydrate and THF hydrate.

In one embodiment of the present application, when using ECP, ETHF, 14ECH, and 12ECH clathrate hydrate, it exhibits an excellent promotion effect compared to conventional CP hydrate and THF hydrate.

Hereinafter, the present invention will be described in more detail through examples of the present application, but the following examples are only exemplified to aid understanding of the present application, and the content of the present application is not limited to the following examples.

[Example]

[matter]

H ₂ O (LC-MS grade, Merck), 6-oxabicyclo[3.1.0]hexane; C ₅ H ₈ O = 1,2-epoxycyclopentane, ECP ;epoxycyclopentane)(97%, Alfa Aesar), 3,6-dioxabicyclo[3.1.0]hexane C ₄ H ₆ O ₂ = 3,4-epoxytetra Hydrofuran, ETHF; epoxytetrahydrofuran) (97%, Tokyo Chemical Industry), 7-oxabicyclo[2.2.1]heptane; C ₆ H ₁₀ O = 1,4-epoxycyclo Hexane, 14ECH; 1,4-epoxycyclohexane) (98%, Alfa Aesar), and 7-oxabicyclo[4.1.0]heptane; C ₆ H ₁₀ O = 1,2 -Epoxycyclohexane, 12ECH; 1,2-epoxycyclohexane) (98%, Tokyo Chemical Industry) was used as received. High-purity CH ₄ (99.95%), H ₂ (99.9%) and N ₂ (99.99%) were supplied by Daesung Industrial Gas Corp.

Example 1

<Synthesis and characterization of hydrate containing 1,2-epoxycyclopentane (ECP; epoxycyclopentane) as a promoter>

Compared to the stoichiometric composition (X _ECP = 0.0556), a slight excess of ECP (about 5%) was mixed with water. When CH ₄ or H ₂ is injected into water to which 5.6 mol% of ECP has been added, it is converted into solid clathrate hydrate.

Then, the mixture was charged into a high-pressure resistance cell (V ~ 100 mL) and pressurized with CH ₄ at 65 bar or H ₂ at 90 bar at room temperature. In each case the cell was gradually cooled from 303 K at a rate of -1 K·h ⁻¹ while maintaining stirring at 200±10 rpm. The reactor was cooled to a sufficiently low temperature of about 263 K to obtain a fully converted solid hydrate phase sample. A solid sample was quickly obtained and immersed in liquid nitrogen. Finally, it was ground into a fine powder (d < 200 μm) for subsequent spectroscopic analysis.

Synchrotron high-resolution powder diffraction (HRPD) patterns were measured with beam-line 9B at the Pohang Accelerator Laboratory to elucidate the crystal structure. Each pattern was measured in the 2θ range from 5.0° to 126.0° (step width = 0.01° and scan time = 0.7 s/scan) using a single wavelength of 1.5216 Å. At a measurement temperature of 150 K and a measurement time of about 50 minutes, the hydrate samples did not dissociate. Then, the measured points (red dots) were matched with full-profile calculations using the FullProf program. The resulting function (black curve) and χ values are shown in FIG. 1 .

1 is a graph showing HRPD patterns of (a) ECP + CH ₄ and (b) ECP + H ₂ hydrate (at 150 K). According to Fig. 1a (HRPD analysis), the structure of ECP + CH ₄ hydrate was clearly confirmed to be of the sII(Fd-3m) type with lattice parameter a = 17.2557 Å, which is similar to that of CP + CH ₄ hydrate (17.23 Å at 133 K). similar to that The amount of hexagonal ice (Ih) from unreacted ECP was negligible. The structure of ECP+H ₂ hydrate (FIG. 1b) was also found to be of type sII with lattice parameter a = 17.2360 Å.

Next, both solid-state NMR and Raman experiments were performed to monitor the molecular behavior of the guest components. The solid-state NMR experiments were performed using a Bruker 400 MHz Avance II solid-state NMR at the Korea Basic Science Institute. In the ¹³ C MAS NMR analysis (hpdec), a Larmor frequency of 100.4 MHz, a pulse length (p1) of 1.6 μs, and a repetition delay time (d1) of 3 seconds were used. In ^{the 1} H MAS NMR analysis (1 pulse), a radio frequency of 400 MHz, a pulse length (p1) of 1.5 μs and a repetition delay time (d1) of 5 seconds were used. The static ¹³ C and ¹ H signals of tetramethylsilane were set to 0 ppm at room temperature. All samples were measured at 210 K at a magic-angle spinning (MAS) speed of 5 kHz.

The vibrational frequencies of the guest molecules were studied with a high-resolution Raman instrument (Horiba Jobin Yvon LabRam HR Evolution). A 50 mW 532 nm laser was used as an excitation source. All Raman spectra were obtained at 123 K using a low temperature Linkam accessory.

To measure the promotion performance of ECP, the equilibrium PT condition of the ECP + H ₂ O + (CH ₄ or H ₂ ) system at a constant mole fraction in the liquid state (X _ECP = 0.0556 and water) was measured. The mixture was filled in a high-pressure resistance cell (V ~ 100 mL) and pressurized with CH ₄ or H ₂ at an appropriate pressure at room temperature. In each case the cell was gradually cooled from 303 K at a rate of -1 K·h ⁻¹ while maintaining stirring at 200±10 rpm. After cooling the reactor to a sufficiently low temperature of about 263 K, it was reheated more slowly to 310 K (at a rate of 0.3 K·h ⁻¹ ). By introducing ECP, the dissociation conditions of the CH ₄ hydrate rapidly rose to higher temperatures at a given pressure (Table 1).

Table 1 shows the equilibrium PT conditions of CH ₄ hydrate containing promoters (X _promoter = 0.0556).

ECP CP THF THF (this work) T(K) P (bar) T(K) P (bar) T(K) P (bar) T(K) P (bar) 297.0 22.1 294.3 21.6 293.1 21.2 296.0 31.7 301.4 43.1 297.3 35.7 297.0 37.3 399.6 54.1 303.1 57.2 299.6 51.2 300.1 60.2 301.8 78.1 303.8 64.6 301.7 67.0 302.3 81.3 305.8 83.7 303.0 86.1

In order to verify the accuracy of the experiment, several equilibrium points of the already well-known THF + CH ₄ system were additionally measured, and the results agreed very well with the reported values.

), THF(◇), ECP + CH₄(

) 하이드레이트의 평형 조건을 나타내었다. 주어진 압력(동일 압력)에서, ECP + CH₄ 하이드레이는 단순 CH₄ 하이드레이트에 비해 약 23 K 높은 평형 온도를 나타내었다. 상기 ECP + CH₄ 하이드레이트의 모든 해리 온도는 각각 CP + CH₄ 하이드레이트 및 THF + CH₄ 하이드레이트의 해리 온도보다 각각 적어도 3 K 및 4 K 더 높은 것으로 또한 밝혀졌다. 이러한 온도 상승은 297 K에서 약 15 bar, 303 K에서 29 bar의 감소와 같은 현저한 압력 감소와 동등하다. 또한, THF + CH₄ 하이드레이트 및 CP + CH₄ 하이드레이트와는 달리, ECP + CH₄ 하이드레이트는 적절한 압력, 약 60 bar에서 30℃(303 K)까지 해리되지 않기 때문에 상온에서 에너지 가스를 저장 또는 운반할 수 있다.2 is a graph showing the equilibrium PT conditions of (a) CH ₄ hydrate and (b) H ₂ hydrate containing THF, CP and ECP, respectively, according to their stoichiometric composition (X _LGM = 0.056). 2a shows simple CH ₄ (●), THF + CH ₄ (◆), CP + CH ₄ (

), THF(◇), ECP + CH ₄ (

) represents the equilibrium condition of the hydrate. At a given pressure (same pressure), ECP + CH ₄ hydrate exhibited about 23 K higher equilibrium temperature than simple CH ₄ hydrate. It has also been found that all dissociation temperatures of the ECP + CH ₄ hydrates are at least 3 K and 4 K higher than those of CP + CH ₄ hydrate and THF + CH ₄ hydrate, respectively. This temperature rise is equivalent to a significant pressure drop, such as a drop of about 15 bar at 297 K and 29 bar at 303 K. Also, unlike THF + CH ₄ hydrate and CP + CH ₄ hydrate, ECP + CH ₄ hydrate does not dissociate until 30 °C (303 K) at moderate pressure, about 60 bar, so it can store or transport energy gas at room temperature. can

At the same temperature, since the pressure required for hydrate formation can be lowered by 20 bar to 30 bar, energy and cost required for storing energy in hydrates can be significantly reduced.

Specifically, in FIG. 2, when the temperature reaches about 25° C. (298 K) by slowly cooling after injecting CH ₄ , ECP + CH ₄ hydrate is obtained while the ECP + H ₂ O mixture absorbs CH ₄ (solid As gas is absorbed into the structure, the pressure drops rapidly). When the solid hydrate is formed and heated again slowly, the condition in which the hydrate dissociates, that is, the equilibrium condition can be measured. In FIG. 2, a gas was injected and tested at a high temperature of about 32°C. However, considering that the room temperature is 20°C to 25°C, hydrates are generated simply by injecting CH ₄ gas at an appropriate pressure. That is, since energy gas can be stored without a cooling process, a very economical process can be implemented.

) 및 ECP + H₂(

)하이드레이트의 평형 조건을 나타내었다. CH₄ 하이드레이트 시스템과 유사하게, ECP는 또한 H₂ 하이드레이트에 대해 가장 강력한 촉진 효과를 발휘하였다. ECP + H₂ 하이드레이트의 모든 해리 온도는 CP + H₂ 및 THF + H₂ 하이드레이트의 해리 온도보다 각각 적어도 2 K 및 4 K 더 높았다. 후자의 두 가지가 가장 강력한 프로모터로 알려졌기 때문에, ECP의 촉진 성능이 THF와 CP의 촉진 성능보다 현저하게 우수하다는 것은 놀라운 일이다.2b, THF + H ₂ (◆), CP + H ₂ (

) and ECP + H ₂ (

) shows the equilibrium condition of the hydrate. Similar to the CH ₄ hydrate system, ECP also exerted the strongest promoting effect on H ₂ hydrate. All dissociation temperatures of ECP + H ₂ hydrates were at least 2 K and 4 K higher than those of CP + H ₂ and THF + H ₂ hydrates, respectively. It is surprising that the promotion performance of ECP is significantly better than that of THF and CP, as the latter two are known to be the strongest promoters.

Table 2 shows the equilibrium PT conditions for H ₂ hydrate containing promoters (X _promoter = 0.0556).

ECP CP THF T(K) P (bar) T(K) P (bar) T(K) P (bar) 282.5 26.6 280.7 27.0 278.2 21.3 283.6 48.3 281.6 49.4 279.2 48.7 284.3 68.2 282.4 70.0 280.1 83.0 284.9 84.0 283.1 90.4 280.8 113 285.5 107.5 283.7 111

3 shows the geometry of (a) a THF molecule, (b) a CP molecule, and (c) an ECP molecule, and the longest center-to-center distance between each atom type is It is expressed in angstroms. The geometric structures and center-to-center distances of the three compounds THF, CP, and ECP were obtained through B3LYP (6-31G ++ d, p) calculations. The dimensions of THF and CP were consistent with the reported values. Since the size and shape of ECP is similar to that of THF or CP, it can be expected that ECP will form sII hydrates, neither sI nor sH types.

Solid-state ¹³ C NMR and Raman spectroscopy were used to cross-check structures and monitor CH ₄ guest molecules. 4 shows Raman spectra of (a) ECP + CH ₄ hydrate and (b) ECP + H ₂ hydrate measured at 123 K and atmospheric pressure, respectively. As shown in Fig. 4a, the peak at 2911.6 cm ^-1 clearly indicates that CH ₄ molecules are accommodated in the sII-S cage. Other peaks near 2855 cm ⁻¹ , 2925 cm ⁻¹ , and 2975 cm ⁻¹ are attributed to some CH vibrations of the ECP molecule. As shown in Figure 4b, typical peaks of H ₂ molecules in the sII-S cage were detected between 4110 cm ^-1 and 4130 cm ^-1 , and the two peaks near 4115 cm ^-1 and 4127 cm ^-1 are H ₂ molecules. It is due to the ortho-para transition of

5 shows (a) solid-state ¹³ C NMR of ECP + CH ₄ hydrate and (b) ¹ H NMR (at 210 K) of ECP + H ₂ hydrate. As shown in Fig. 5a, a clear peak was detected at δ = -4.60 ppm, corresponding to the CH ₄ molecules trapped in small (5 ¹² ) cages. Other peaks at about -4.3 ppm, -6.7 ppm and -8.3 ppm typical of CH ₄ molecules trapped in the sI-S, sI-L and sII-L cages, respectively, were not detected. The solid-state ¹ H NMR results also clearly indicate H ₂ enclathration in ECP + H ₂ hydrate ( FIG. 5B ). The moderately broad peak centered at 4.1 ppm is attributed to the H ₂ molecules trapped in the sII-S cage, which is in excellent agreement with previously reported results. Corresponding vibrational bands near 2912 cm ⁻¹ and 4125 cm ⁻¹ due to CH ₄ molecules and H ₂ molecules accommodated in the sII-S cage were also clearly found in the Raman spectrum (FIG. 4). Summarizing the results of HRPD, NMR, and Raman investigations, energy gases are easily stored in small cages, while the ECP molecules occupy large cages.

및 단일 H₂ 점유율을 가정하였으며, 또한 용량을 다른 방식으로 추가 교차 점검하였다. ECP + H₂O의 화학량론적 혼합물을 박막 형태(t ~ 0.2 mm)의 액체 질소로 ??칭하였다. 고체 샘플을 미세 분말(d ~ 200 μm)로 분쇄한 후, 243 K에서 ~ 100 bar의 H₂로 가압하였다. 4 일 후, 저장된 H₂의 부피를 측정하기 위해 상기 샘플을 용융시키고 방출되는 가스의 부피를 측정하였다. 평균 93 cm³의 H₂(STP)가 1 g의 ECP + H₂ 하이드레이트 샘플에 저장되어, 13 H₂ · 8 ECP · 136 H₂O 및

을 나타내었다.In Figure 5b, the peaks are (1) a slightly broad peak centered around 4.1 ppm, (2) four sharp peaks ranging from 3.5 ppm to 1.0 ppm, and (3) three of the broadest background peaks centered around 2 ppm. The peaks can be classified into groups. (1) The first peak is due to H ₂ molecules trapped in the sII-S cage, which is in excellent agreement with previously reported results. (2) Considering only the Lewis structure, since three different types of hydrogen atoms exist in the ECP molecule in a ratio of 2:4:2, three peaks with an area ratio of 2:4:2 can be expected. However, the rather complex patterns observed in the second set of four peaks may arise due to combinations of peaks from several conformers or enantiomers of ECP. (3) Therefore, the remaining third peak would have arisen from the water framework. Despite this somewhat uncertain aspect, it is certain that H ₂ molecules are trapped in the sII-S cage. Here, the H ₂ dose was determined by the same method as reported by Strobel et al. The relative area between peak (1) and the four peaks of set (2) is about 1:3, indicating an H ₂ occupancy of about 0.67. However, H ₂ molecules exist in the form of ortho-isomers and para-isomers, of which only the former can be observed by ¹ H NMR. Therefore, considering that the ratio of ortho-H ₂ to para-H ₂ is about 3:1 at a temperature higher than 200 K, the actual H ₂ occupancy is about 0.9. in a small cage

and a single H ₂ occupancy were assumed, and the capacities were further cross-checked in different ways. A stoichiometric mixture of ECP + H ₂ O was quenched with liquid nitrogen in the form of a thin film (t ~ 0.2 mm). The solid sample was ground into a fine powder (d ~ 200 μm) and then pressurized with ~ 100 bar of H ₂ at 243 K. After 4 days, the sample was melted and the volume of gas released was measured to determine the volume of H ₂ stored. An average of 93 cm ³ of H ₂ (STP) was stored in 1 g of ECP + H ₂ hydrate sample, resulting in 13 H ₂ 8 ECP 136 H ₂ O and

showed

The storage capacity of H ₂ (13 H ₂ 8 ECP 136 H ₂ O) of at least 0.8 wt % was clearly established by the above-described measurements. This is a clearly higher capacity compared to the capacity of THF + H ₂ hydrate formed under similar pressure (~100 bar).

In order to find the reason for the significantly better performance than the existing promoters, a sample composed of only ECP and H ₂ O was investigated. The liquid mixture of ECP + H ₂ O was cooled slowly at room temperature under continuous stirring to prepare a sufficiently homogeneous solid sample. The HRPD pattern (FIG. 6) clearly indicated that ECP + H ₂ O formed sII hydrate even in the absence of an external gas component. The lattice constant was determined to be 17.2380 Å at 150 K. This value is almost equal to the lattice constant of ECP + H ₂ but slightly smaller than that of ECP + CH ₄ hydrate.

ECP + H₂ 하이드레이트(17.2360 Å)의 순서이다. 기체가 없는 ECP 하이드레이트는 추가 CH₄ 분자가 그것의 내부로 수용될 때 약간 팽창하는 것으로 보인다. 그러나, H₂ 하이드레이트의 경우, H₂의 분자 크기가 CH₄의 분자 크기보다 훨씬 작다는 것을 고려하면, H₂ 포집(enclathration)에 따른 격자 팽창은 발생하지 않은 것으로 나타났다.6 shows the HRPD pattern of ECP + H ₂ O hydrate measured at 150 K. The lattice constant is ECP + CH ₄ hydrate (17.2558 Å) > ECP + H ₂ O hydrate (17.2380 Å)

The sequence is ECP + H ₂ hydrate (17.2360 Å). Gasless ECP hydrate appears to expand slightly as additional CH ₄ molecules are admitted into it. However, in the case of H ₂ hydrate, considering that the molecular size of H ₂ is much smaller than that of CH ₄ , lattice expansion due to H ₂ enclavement did not occur.

In addition, considering that the lattice constant of the ECP + H ₂ O hydrate is between the lattice constant of THF + H ₂ O (17.1740 Å) hydrate and CP + H ₂ O (17.2464 Å) hydrate, the effective size of the ECP molecule is It was also assumed to be between the effective sizes of THF and CP molecules.

According to additional HRPD measurements (FIG. 7), it was found that the gas-free ECP hydrate dissociated at a certain temperature below 280 K. These temperatures are close to the melting points of gaseous THF (~ 277 K) and CP (~ 280 K) hydrates. Therefore, although the dissociation temperature of gasless ECP hydrate is not particularly high compared to that of gasless THF and CP hydrates, it can be concluded that the ability of ECP to stabilize the sII structure plays a key role in the significant promoting effect.

7 is a graph showing (a) a lattice parameter and (b) a normalized lattice parameter (the lattice parameter at 150 K is set to a ₀ ) according to temperature in the case of ECP + H ₂ O hydrate. The sII lattice expanded gradually with a nearly constant linear expansion coefficient of 5.8 Х 10 ^-5 , in good agreement with the results reported in several studies. Finally, the lattice parameter at 270 K becomes about 0.7% larger than that at 150 K. However, it can be seen that clear patterns representing the sII structure collapse when the sample is heated to 280 K. Therefore, it was concluded that solid ECP hydrate dissociates at a specific temperature below 280 K.

In addition, certain unique characteristics of the ECP hydrate system are presented, especially three factors that are important for the application: (1) storage capacity, (2) gas absorption conditions, and (3) reusability and safety. As many researchers have clearly demonstrated, the occupancy of each guest and the composition of the hydrate can be determined by integrating and comparing the NMR peak areas of individual guest constituents.

Figure 8 shows the full range ¹³ C NMR spectrum of ECP + CH ₄ hydrate measured at 210 K, and no signal was detected at -8.3 ppm (black arrow) due to CH ₄ in the sII-L cage (Fig. 7a Reference).

)로 완전히 채워져 있다고 가정하면, sII-S 케이지에서 CH₄의 점유율은 [01] 하기와 같이 계산할 수 있다.In addition to the CH ₄ peak at -4.60 ppm, three main peaks due to ECP molecules were detected. From downfield to upfield, the peaks at +55.52 ppm, +27.28 ppm and +18.34 ppm correspond to the α carbon, β carbon and γ carbon of the ECP molecule, respectively. The actual area ratio was measured to be about 1.5 : 1.8 : 1.0, which is somewhat different from the expected ideal ratio of 2 : 2 : 1 based on the number of carbons of each type. Many researchers have already presented methods to obtain the cage occupancy and determine the composition of the hydrate by integrating the areas of the ¹³ C NMR peaks of different guests. However, recent studies have reported that functional groups can affect neighboring carbons (particularly the α carbon) in an unexplained way, reducing the NMR intensity slightly. Therefore, we used the peak of the γ carbon in this study, which is the carbon furthest from the oxygen atom, and obtained the molar ratio between ECP and CH ₄ . A large cage is suitable for ECP or CH ₄ (

), the occupancy of CH ₄ in the sII-S cage [01] can be calculated as follows.

임을 알 수 있었다. 따라서 본원에 사용된 형성 조건 하에서, 상기 ECP + CH₄ 하이드레이트의 전체 조성은 14 CH_{4 ·} 8 ECP _· 136 H₂O 임을 의미한다. 상기 CH₄ 함량은 STP에서 약 100 cm³ CH₄/cm³ 하이드레이트, 또는 6.7 wt%와 동등하다. 상기 CH₄ 저장 용량은 다른 CH₄ 하이드레이트의 저장 용량보다 상당히 높다. 예를 들어, Seo et al.은 THF의 화학량론적 농도에서 THF + CH₄ 하이드레이트의 CH₄ 점유율은 0.37이라고 보고하였다. 보다 최근의 연구에 따르면 THF 하이드레이트에서 메탄 흡수(uptake)는 약 0.07 mol CH₄/mol H₂O이고, 이는 CH₄ 점유율이 0.60임을 뜻한다. CP + CH₄ 하이드레이트의 경우, Lv et al.은 0.2 내지 0.4 범위의

값을 보고한 반면, Lee et al.은 0.60의 훨씬 더 높은 값을 제안하였다 (표 3 참조). 하지만 ECP + CH₄ 하이드레이트의 저장 용량에는 훨씬 미치지 못한다.where A is the relative area of each type of carbon and N _EC is the corresponding number of carbons. According to the relative area value,

was found to be Thus, under the formation conditions used herein _, the overall composition of the ECP + CH ₄ hydrate is 14 CH ₄ 8 ECP 136 H ₂ O. The CH ₄ content is equivalent to about 100 cm ³ CH ₄ /cm ³ hydrate at STP, or 6.7 wt %. The CH ₄ storage capacity is significantly higher than that of other CH ₄ hydrates. For example, Seo et al. reported that the CH ₄ occupancy of THF + CH ₄ hydrate at the stoichiometric concentration of THF was 0.37. A more recent study showed that the methane uptake in THF hydrate is about 0.07 mol CH ₄ /mol H ₂ O, which implies a CH ₄ occupancy of 0.60. For CP + CH ₄ hydrate, Lv et al. ranged from 0.2 to 0.4.

While reporting a value, Lee et al. suggested a much higher value of 0.60 (see Table 3). However, it falls far short of the storage capacity of ECP + CH ₄ hydrate.

Table 3 shows the CH ₄ occupancy, composition, and CH ₄ content of THF, CP or ECP + CH ₄ hydrate.

ECP + CH ₄ THF + CH ₄ CP + CH ₄

0.87 0.37 0.60 0.30 0.60 x CH ₄ 8 _LGM 136 H ₂ O ^a 13.9 5.9 9.5 4.8 9.6 mmol CH ₄ / mol H ₂ O 102 43 70 35 71

^a LMG: large guest molecules

As summarized in Table 3, the reported CH ₄ content is approximately 70 cm ³ CH ₄ /cm ³ hydrate for THF + CH ₄ hydrate and CP+CH ₄ hydrate, equivalent to 10 CH ₄ 8 (THF/CP ) did not exceed 136 H ₂ O. Accordingly, it should be noted that the ECP + CH ₄ hydrate contains at least 1.5 times more CH ₄ gas than conventional THF + CH ₄ hydrates and CP + CH ₄ hydrates.

In addition, it was observed that the gas absorption process occurred at a much higher temperature than other CH4 hydrates by adding ECP. When slowly cooling a pressurized liquid mixture, theoretically, hydrates should begin to form immediately after passing the dissociation temperature of the hydrates, i.e., a rapid pressure drop should occur. However, in general, the decrease in pressure almost always occurs well below the dissociation temperature, which appears to be primarily driven by some kinetic constraints. As a result, the additional time, energy, and cost requirements for additional cooling and mixing processes would be significant, especially in large-scale applications.

FIG. 9 shows PT traces (25.3° C., 60 bar, CH ₄ uptake) measured by the formation/dissociation process of ECP + CH ₄ hydrate. The pressure started to drop rapidly at 298.4 K and was not significantly different from the dissociation temperature of 303.8 K (30.7 °C, 64.6 bar, dissociation). Conversely, the starting point (286.4 K, 51.0 bar) was obtained compared to the equilibrium point (299.5 K, 54.0 bar) for the THF + CH ₄ + H ₂ O system. Thus, it should be noted that the introduction of ECP allows the formation of ECP + CH ₄ hydrate at room temperature without further cooling even at moderate pressure levels which are not very high. This means that the hydrate is formed simply by injecting CH ₄ gas at an appropriate pressure, given that the room temperature is about 20°C. That is, since energy gas can be stored without a cooling process, a very economical process can be expected.

The chemical substance ECP shows suitable properties in terms of reusability and safety, so more sustainable applications can be expected.

Table 4 shows the physical properties and safety data of THF, CP and ECP ^a .

P ^sat (kPa) ^a T _b ( ^o C) T _f ( ^o C) ρ (g/ml) ^a Hazard statements THF 19.3 66 -21 0.880 H225, H302, H319, H335, H336, H351 CP 36 50 -7 (-20) 0.745 H225, H304, H315, H319, H335 ^c , H336, H412 ECP 6.0 102 10 0.964 H225, H315, H319, H335

^a Value at 293 K.

Since the P ^sat value of THF or CP is significantly higher than the vapor pressure of water (2.3 kPa at 293 K), the amount of THF or CP that is inevitably released in the process of releasing the stored gas cannot be ignored. Considering this, since ECP is much less volatile than THF or CP, higher reusability can be expected from the ECP hydrate system. On the other hand, the flash point of ECP is much higher than that of THF and that of CP. In addition, ECP does not appear to exhibit significant toxicity such as H315 in THF (suspected to cause cancer) and H412 in CP (long-term harmful effects to aquatic life). Therefore, it is also expected that a physically safer and more environmentally friendly process can be realized through ECP.

So far, for HBES purposes, novel clathrate hydrates containing ECP have been investigated (FIG. 10). 10 shows a schematic diagram of HBES using ECP. The T and P values shown in FIG. 10 were based on CH ₄ storage.

Compared to conventional hydrates, the ECP hydrate exhibits several outstanding characteristics: (1) significantly improved thermodynamic stability, (2) significantly improved storage capacity, (3) facilitated gas absorption conditions, and ( 4) Better sustainability. Because of these promising capabilities, we emphasize that a sustainable HBES technology can be realized using the proposed ECP hydrate system. As this study mainly focused on fundamental properties related to structure, thermodynamic conditions, and storage capacity, future work in industrial applications will include the kinetics of formation/dissociation, stability and reusability of ECPs, optimization of conditions, and related areas. Further research including various industrial key points including The inventors further believe that the findings and results of the present invention will be of great interest to researchers in the scientific and engineering fields, and suggest a breakthrough in hydrate-based technology.

Example 2

<3,4-epoxytetrahydrofuran (ETHF; epoxytetrahydrofuran), 1,4-epoxycyclohexane (14ECH; 1,4-epoxycyclohexane) and 1,2-epoxycyclohexane (12ECH; 1,2-epoxycyclohexane), respectively Synthesis and characterization of hydrate containing as a promoter>

Same as Example 1, except that CH ₄ was supplied to the vessel until the initial pressure reached between 60 bar and 65 bar at room temperature (N ₂ hydrate samples were produced by supplying N ₂ from 80 bar to 90 bar). The experiment was conducted in this way.

To identify crystal structures, synchrotron high-resolution powder diffraction (HRPD) and powder X-ray diffraction (PXRD) were first used. According to this result, all CH ₄ hydrates formed by ETHF, 14ECH, and 12ECH were confirmed to be sII(Fd3-m) hydrates with corresponding lattice parameters of 17.195 Å, 17.330 Å and 17.382 Å, respectively. In addition, solid-state ¹³ C NMR and Raman spectra clearly demonstrated that CH ₄ molecules are accommodated in the sII-S cage.

For ETHF and 12ECH hydrates, HRPD patterns were obtained with a single wavelength of 1.5216 Å and recorded in the 2θ range from 5.0° to 126.0° (step width = 0.01° and scan time = 0.7s/scan).

For 14ECH and CH hydrates, the PXRD patterns were obtained by Rigaku D/MAX using a Cu radiation source with a wavelength of 1.54180 Å (Kα ₁ = 1.54056 Å and Kα ₂ = 1.54439 Å) and an output of 8 kW (40 kV and 200 mA). It was acquired with the -2500 instrument and recorded in the 2θ range from 5.0° to 55.0° (step width = 0.02° and scan time = 1 sec/scan). All measurement temperatures were maintained at 150 K and no dissociation of the samples was detected. Crystal structures and corresponding lattice parameters were determined using FullProf and Checkcell programs.

Next, in the same manner as in Example 1, solid-state NMR and Raman experiments were all performed to monitor the molecular behavior of the guest constituents.

To investigate the thermal properties of the hydrates, phase changes with temperature were measured using a differential scanning calorimeter (DSC) instrument (NETZSCH DSC 200 F3 Maia). While submerged in liquid nitrogen, a small piece (approximately 3 mg to 5 mg) of each sample was loaded into an aluminum pan. The fan was then mounted on a sample stage pre-cooled to 173 K. After 10 minutes of isothermal time at 173 K and atmospheric pressure, the sample was slowly heated at a constant rate of 3 K/min to reach 298 K. During the entire measurement period, the sample stage was purged with nitrogen gas to prevent moisture.

In addition, the equilibrium PT condition of the CH ₄ (or N ₂ ) hydrate system containing three LGMs was measured. Each liquid mixture (total mass approximately 7 g) consists of a stoichiometric composition of LGM and the balance of water (balanced water), is filled in a high-pressure resistance cell (V ~ 100 ml), and contains various CH ₄ or N ₂ at room temperature. Pressurized under pressure. The samples were continuously cooled to 260 K (at a rate of -1K·h ⁻¹ ) to form a solid hydrate phase. Then, it was heated more slowly to 310 K (at a rate of 0.3 K·h ⁻¹ ). The agitation rate was maintained at 200 ± 10 RPM during the entire hysteresis process. To confirm the accuracy of the measurements, several equilibrium points of simple CH ₄ and THF + CH ₄ hydrate were further measured. It was confirmed that the present inventors' measurements were in excellent agreement with the reported values (see Adisasmito et al. 1991, Fig. 11).

Figure 11 shows the equilibrium PT conditions (X _LGM = 0.0556) of CH ₄ hydrate with various promoters. In order to clearly compare the degree of promotion, FIG. 11 also shows the equilibrium conditions of CH ₄ hydrates including CH (moderately strong promoter) and THF (particularly strong promoter). Comparing promoters of similar molecular structures, the promotional effect of ETHF (black open square) is much weaker than that of THF (Lee et al. 2012 and the same study). On the other hand, 12ECH and 14ECH + CH ₄ hydrates (blue and red hexagons, respectively) exhibited higher dissociation temperatures compared to CH + CH ₄ hydrates (Sun et al. 2002). Moreover, the thermodynamic stability of 14ECH + CH ₄ hydrate was found to be similar to that of THF + CH ₄ hydrate. Since THF is known as one of the strongest promoters, the promotional effect of 14ECH is as strong as that of THF.

The geometries and center-to-center distances of the five molecules ETHF, 14ECH, 12ECH, THF and CH are illustrated in FIG. 12 . 12 shows the optimized geometries of (a) ETHF, (b) 14ECH, (c) 12ECH, (d) THF and (e) CH, and the longest center-to-centre distance between atoms of each type is Angstroms ( angstroms). The molecular geometries were optimized through 6-31G++ (d, p)/B3LYP calculations using the Gaussian 03 program (Frisch et al. 2004). The magnitude of THF was in good agreement with the reported values (Takeya et al. 2018). There are two types of COC bonds: epoxide rings and 5-membered rings. In the epoxide ring, ETHF and 12ECH both exhibited similar CO bond lengths of 1.44 Å and CO bond angles of 61.5°. However, the five-membered rings of ETHF and 14ECH exhibited somewhat different geometries. The CO bond length and COC bond angle of ETHF are 1.43 Å and 110°, respectively, almost identical to those of THF. However, the COC bond angle of 14ECH was found to be 96.6°, resulting in a slightly smaller C...C distance of 2.16 Å compared to that of ETHF (2.35 Å). As a result, the 6-membered ring of 14ECH is more distorted and slightly smaller than that of 12ECH. Considering that the sizes of ETHF, 14ECH and 12ECH are similar to those of THF and CH, it can be expected that the three LGMs form sII hydrates.

Table 5 shows the Miller indices of the CH + CH ₄ hydrates shown in FIG. 12 .

peaks h k l d _hkl 8.76 111 10.092 14.33 202 6.180 16.82 311 5.270 17.58 222 5.046 20.32 004 4.370 22.17 313 4.010 24.96 224 3.568 26.50 333 3.364 28.89 404 3.090 30.25 513 2.955 30.69 424 2.913 32.39 602 2.764 33.62 335 2.666 34.02 622 2.635 35.58 444 2.523 36.72 515 2.448 38.54 426 2.336 39.60 355 2.276 41.32 008 2.185 42.32 337 2.136 42.65 644 2.120 43.95 228 2.060 44.91 555 2.018 45.22 626 2.005 46.46 048 1.954 47.38 357 1.919 47.68 248 1.907 49.76 913 1.832 52.06 755 1.757 54.28 737 1.690 54.56 666 1.682

13 shows the HRPD and PXRD patterns of (a) ETHF, (b) 14ECH, and (c) 12ECH + CH ₄ hydrates, and Table ₆ shows the corresponding Miller index was shown. The structures of ETHF, 14ECH, and 12ECH + CH ₄ hydrates were clearly identified as sII(Fd-3m) type with lattice parameters of 17.195 Å, 17.330 Å and 17.382 Å, respectively. These lattice parameters correspond to unit cell volumes of 5083.8 Å ³ , 5204.7 Å ³ and 5251.89 Å ³ . The amount of hexagonal ice (Ih) or CH ₄ hydrate (sI) due to LGM exclusion was minimal or negligible. Also the powder diffraction pattern of CH + CH ₄ hydrate was measured and a lattice parameter of a = 17.480 Å was obtained. The lattice parameter of THF + CH ₄ hydrate was previously reported as a = 17.224 Å (Lee et al. 2012). Thus, the unit cell size is in the order of ETHF < THF < 14ECH < 12ECH < CH + CH ₄ hydrate. Thus, it can be concluded that the effective van der Waals volume of the group > CH-O-CH < is slightly smaller than that of the -CH ₂ -CH ₂ - group.

Table 6 shows the Miller indices of the three hydrates shown in FIG. 13.

ETHF + CH ₄ 14 ECH + CH ₄ 12 ECH + CH ₄ peak h k l d _hkl peak h k l d _hkl peak h k l d _hkl 8.79 111 9.928 8.84 111 10.006 8.696 111 10.0355 14.38 202 6.079 14.46 202 6.127 14.223 202 6.1455 17.63 222 4.964 16.97 311 5.225 16.694 113 5.2409 20.39 400 4.299 17.73 222 5.003 17.442 222 5.0177 22.24 133 3.945 20.50 400 4.333 20.166 400 4.3455 25.04 422 3.510 22.36 313 3.976 21.997 133 3.9877 26.58 333 3.309 25.17 422 3.538 24.764 422 3.5481 28.99 404 3.040 26.73 333 3.335 26.292 333 3.3452 30.35 513 2.907 29.15 404 3.064 28.671 404 3.0727 30.79 424 2.866 30.52 513 2.929 30.015 513 2.9381 32.50 602 2.719 30.96 424 2.888 30.451 424 2.897 33.73 335 2.622 32.68 602 2.740 32.141 206 2.7483 34.13 226 2.592 33.92 335 2.643 33.359 533 2.6507 35.70 444 2.482 34.32 622 2.613 35.305 444 2.5089 36.84 515 2.408 35.90 444 2.501 36.429 515 2.434 39.74 355 2.239 37.05 515 2.427 38.239 426 2.3228 41.46 800 2.149 38.89 426 2.316 39.291 355 2.2629 42.47 337 2.101 39.96 355 2.256 40.994 800 2.1727 44.10 822 2.026 41.69 800 2.166 41.988 733 2.1235 45.06 555 1.986 42.71 337 2.117 42.315 446 2.1079 46.63 408 1.923 43.04 644 2.102 43.603 822 2.0485 47.54 537 1.887 44.35 822 2.042 44.55 555 2.0071 47.85 248 1.876 45.32 555 2.001 44.862 266 1.9938 52.24 755 1.728 45.64 626 1.988 46.094 408 1.9434 54.48 737 1.662 46.89 408 1.938 47.001 537 1.9079 54.5 66 1.655 47.82 537 1.902 47.301 248 1.8965 48.12 824 1.891 48.484 646 1.8529 49.33 646 1.847 51.634 755 1.747 50.22 913 1.817 53.841 737 1.6804 51.68 844 1.769 54.112 666 1.6726 52.54 755 1.742 53.96 268 1.699 54.79 737 1.675

Solid-state ¹³ C NMR and Raman spectroscopy were used to cross-check the structure and monitor CH ₄ guest molecules.

14 shows (a) solid-state ¹³ C NMR and (b) Raman spectra of ETHF, 14ECH and 12ECH + CH ₄ hydrate according to one embodiment of the present application. As can be seen in Figure 14a, a single clear peak was detected at δ = -4.5 ppm to -4.8 ppm for all CH ₄ hydrates, corresponding to CH ₄ molecules trapped in small (5 ¹² ) cages. No different peaks were detected for ETHF and 14ECH + CH ₄ hydrates in the upfield region. Additional signals at -4.3 ppm, -6.7 ppm and -8.3 ppm typical of CH ₄ molecules trapped in sI-S, sI-L and sII-L cages (Yeon et al. 2006), respectively, for 12ECH + CH ₄ Although observed, these peaks are very small compared to the main peak around -4.8 ppm.

The same interpretation can be made through the Raman spectrum of FIG. 14b: the CH stretching vibration band near 2911 cm ⁻¹ representing CH ₄ molecules in small cages was clearly observed in all samples, whereas in ECH + CH ₄ hydrate A weak signal was additionally detected near 2902 cm ^-1 (sI-L or sII-L) only for Summarizing the results of HRPD, ¹³ C NMR and Raman investigations, all LGMs can easily form “double” sII hydrates with CH ₄ , of which the large and small cages mainly contain LGM and CH ₄ molecules, respectively. occupy In addition, the ¹³ C NMR peaks found at -4.47 ppm (ETHF), -4.72 ppm (ECH) and -4.80 ppm (ECH), even though the type of trapping cage is the same (sII-S), the CH in the larger cage ₄ molecules show more masked chemical shifts. This is not a huge difference: however, the trend is clear enough that one can roughly estimate which hydrate has the larger lattice parameter by comparing NMR peaks without precise crystallographic analysis.

Next, equilibrium PT conditions of three CH ₄ hydrate systems at a constant mole fraction of the liquid phase (X _LGM = 0.0556) were measured and the results are listed in Table 1. By introducing each LGM, the thermodynamic regime of CH ₄ hydrate is extended to significantly higher temperature and lower pressure levels. At a given pressure, the dissociation temperature of simple CH ₄ hydrate (Adisasmito et al. 1991 and supra) increased by about 9 K, 12 K and 18 K due to the addition of ETHF, 12ECH and 14ECH, respectively. In particular, 14ECH + CH ₄ hydrate did not dissociate even at a moderate pressure of about 60 bar, up to room temperature (298 K).

In addition, the equilibrium conditions of three LGM + N ₂ hydrates were investigated and the results are listed in Table 7. The addition of LGMs markedly improved the dissociation conditions of simple N ₂ hydrate (van Cleeff and Diepen 1960) at higher temperatures and lower pressure levels. All promoters tend to be identical to the CH ₄ hydrate system in their degree of promotion (FIG. 15). 15 shows equilibrium PT conditions (X _LGM = 0.0556) of N ₂ hydrate with various promoters.

Table 7 shows the equilibrium PT conditions of CH ₄ hydrate containing three promoters.

ETHF 14ECH 12ECH T(K) P (bar) T(K) P (bar) T(K) P (bar) 282.0 20.3 292.1 23.5 284.2 19.1 286.2 37.1 295.6 40.9 289.1 39.4 289.7 62.7 298.8 63.5 292.4 60.9 291.7 80.5 300.6 82.4 295.1 85.0

Table 8 shows the equilibrium PT conditions of N ₂ hydrate containing three promoters.

ETHF 14ECH 12ECH T(K) P (bar) T(K) P (bar) T(K) P (bar) 279.3 68.6 278.4 30.8 279.2 49.3 281.2 90.2 286.9 56.2 281.5 69.3 282.7 110.1 289.5 80.2 283.0 84.1 291.2 102.4 284.5 106.5

Equilibrium PT data for CH + N ₂ and THF + N ₂ hydrates are from Richon and Mohammadi (2011) and Seo et al. (2001). In order to confirm whether N ₂ is trapped in the solid hydrate state, the present inventors used Raman spectroscopy.

In FIG. 16, the peak near 2324 cm ⁻¹ indicates that all LGM + N ₂ hydrates were clearly formed. Thus, it can be concluded that the three novel LGMs serve as promoters for gas hydrates of both spherical and cylindrical types of gas molecules. 16 shows a Raman spectrum of LGM+N ₂ hydrate measured at 123 K.

To find clues to understand the strong promotion of 14ECH, samples consisting only of H ₂ O and LGMs were investigated. Each liquid mixture of LGM + H ₂ O was cooled slowly from room temperature under continuous stirring to prepare sufficiently homogeneous solid samples. According to crystallographic analysis, no hydrate state was observed in the solid samples of ETHF + H ₂ O and 12ECH + H ₂ O. On the other hand, through PXRD patterns (FIG. 17 and Table 9), it was clearly demonstrated that 14ECH + H ₂ O forms simple sII hydrate even in the absence of additional gaseous components. The lattice parameter was determined to be 17.333 Å at 150 K, almost identical to that of 14ECH + CH ₄ hydrate. Trapping CH molecules _in the sII-S cages appears to have little effect on the lattice size. 17 shows the PXRD pattern of 14ECH + H ₂ O hydrate (no gas) at 150 K.

Table 9 shows the Miller index of the simple 14ECH hydrate shown in FIG. 17 .

peaks h k l d _hkl 8.84 111 10.007 14.45 202 6.128 16.97 311 5.226 17.73 222 5.004 20.50 004 4.333 22.36 133 3.977 25.17 422 3.538 26.72 333 3.336 29.14 404 3.064 30.51 315 2.930 30.95 424 2.889 32.67 602 2.741 33.91 335 2.643 35.89 444 2.502 37.04 515 2.427 38.88 426 2.316 39.95 355 2.257 41.69 008 2.167 42.70 337 2.118 43.03 644 2.102 44.34 822 2.043 45.31 555 2.001 46.88 048 1.938 47.81 357 1.903 49.32 466 1.848 50.21 913 1.817 51.67 844 1.769 52.53 557 1.742

To clearly monitor the 14ECH molecules involved in the sII phase, ¹³ C NMR and Raman spectra were analyzed in detail. The ¹³ C NMR peaks of 14ECH molecules are shown in FIG. 18A. 18 shows (a) ¹³ C NMR peak and (b) COC vibrational band of 14ECH molecule. For 14ECH + CH ₄ hydrate (blue), it was clearly found that the alpha carbon of 14ECH exhibited two separate peaks at 75.3 ppm and 75.9 ppm. The fine peak at 75.9 ppm is due to the 14ECH being excluded from the hydrate phase, since we introduced a slight excess (~5%) of 14ECH relative to the stoichiometric composition. As a result, it can be seen that the main peak at 75.3 ppm, which is also observed in the simple hydrate of 14ECH, originates from the 14ECH molecules trapped in the sII-L cage. In addition, the Raman spectrum was investigated in detail, focusing on the vibrational band of the 14ECH molecule. In Fig. 18b, several peaks around 850 cm ^-1 to 1000 cm ^-1 are due to symmetric stretching vibrations of the COC group (Socrates 2001). However, compared to the band of simple 14ECH (red), the band of 14ECH included in the sII phase appeared clearly at higher wavenumbers. When a free 14ECH molecule is trapped in the sII-L cage, the COC bond contracts slightly, increasing the force constant of the vibration. Shorter bond lengths also increase the electron density around the alpha carbon, providing more shielding states. Until now, most researchers have used spectroscopic approaches only to monitor gaseous guest components. However, the results of this study also convincingly demonstrated that NMR and Raman spectra are useful in determining the behavior of LGMs.

In addition, the temperature of the 14ECH hydrate system where the major phase transition occurs was identified by differential scanning calorimeter (DSC) measurements.

19 shows several major phase transitions induced by temperature at atmospheric pressure. 19a, four points ① to ④ show the corresponding 273 K, 270 K, 277 K and 285 K, and small peaks that can be attributed to 14ECP + air hydrate (impurity) are marked with asterisks (*) For clarity, the y axis is shown on the same scale. The fundamental heat flow measured in mW·mg ⁻¹ was normalized to moles of H ₂ O (black, blue and red). For simple 14ECH, the heat flow was normalized to moles of 14ECH (magenta).

As can be seen in Figure 19a, simple 14ECH hydrate begins to dissociate at 270 K and completely dissociates at 278 K. For the 14ECH + CH ₄ hydrate samples, mainly two phase transitions were observed. (1) Dissociation of a small amount of 14ECH simple hydrate that did not react with gaseous CH ₄ (point ②); and (2) dissociation of 14ECH + CH ₄ hydrate induced by outgassing (point ③). Eventually, 14ECH + CH ₄ hydrate completely decays at about 285 K (point ④). On the other hand, the temperature-induced pattern of simple 14ECH is quite complex and we cannot determine the corresponding phase transition at the present stage. However, the phase transition induced by simple 14ECH was not observed in either 14ECH + CH ₄ hydrate or 14ECH simple hydrate. This provides another clear evidence for the complete entrapment of 14ECH molecules in both simple hydrates and CH ₄ hydrates. In addition, it can be concluded that simple 14ECH hydrate dissociates in the range of 270 K to 278 K, whereas 14ECH + CH ₄ hydrate dissociates in the range of 277 K to 285 K at atmospheric pressure.

19B shows the corresponding 273 K, 255 K, 271 K, 277 K, and 263 K for the five points ① to ⑤ at which the phase transition begins to occur. Heat flow was normalized to moles of H ₂ O. In FIG. 19B, the start and finish temperatures of gas hydrate dissociation are in the order of ETHF + CH ₄ < 12ECH + CH ₄ < 14ECH + CH ₄ . This is completely consistent with the results of phase equilibrium shown in Fig. 11 above.

So far, we have demonstrated that 14ECH acts as a simple sII former and appears to play an important role in its outstanding promotional effect. Among the numerous LGMs proposed over the decades, simple hydrate formers are very rare, except for CFCs. Additionally, tetrahydropyran (THP) with a van der Waals diameter of 6.95 Å (Udachin et al. 2002) has been recorded as the largest simple sII former. However, according to our calculations, 14ECH with the longest end-to-end distance of 7.10 Å is larger than THP [since van der Waals radii are not included in Fig. 1.09 Å and 1.56 Å should be added (Rowland and Taylor, 1996)]. This is also supported by the fact that the lattice parameter of 14ECH + H ₂ O hydrate is somewhat larger than that of THP + H ₂ O hydrate (a = 17.289 Å at 153 K) (Takeya et al. 2018). It is considered the first discovery of a simple sII former.

It was also noted that addition of 14ECH resulted in rapid CH ₄ absorption at significantly higher temperatures. 20 shows the PT traces measured by the formation and dissociation process of 14ECH + CH ₄ hydrate. In FIG. 20, (1) When the gas injection was completed, the temperature inside the container increased to 20°C due to adiabatic compression. ② Within 10 minutes, the vessel was returned to normal temperature (17.5° C.) and CH ₄ absorption started at the same time. ③ After 40 minutes, the container was immersed in an ethanol bath. ④ The vessel was cooled at a rate of -20 K/hr. ⑤ The vessel was heated at a rate of +0.3 K/hr. ⑥ Hydrate was completely dissociated at 25.7 ℃ and 63.5 bar.

20, it was clearly observed that the pressure started to drop rapidly at room temperature to form a hydrate phase. The high temperature of gas absorption can also be attributed to 14ECH's ability to stabilize simple hydrates. When the mixture of LGM + H ₂ O is pressurized with the desired gas, theoretically the hydrate should form just below the equilibrium temperature. However, in most cases, due to reaction kinetic limitations, the system must be cooled well below the equilibrium temperature to initiate gas uptake. Thus, industrial applications require sufficiently high forming temperatures as the additional time, energy and cost requirements for additional cooling and mixing processes become significant. Because the kinetic results are highly dependent on the wide variety of conditions under which the hydrates are formed, including cell size, initial amounts of liquid and gas, contact area, agitation rate, and cooling rate, etc., various studies are needed to investigate the detailed kinetic behavior. should be performed additionally. However, at the present stage, it is still noteworthy that 14ECH + CH ₄ hydrate can be formed at room temperature at moderate pressure levels.

In conclusion, CH ₄ hydrates including three novel LGMs, ETHF, 14ECH and 12ECH, were synthesized and characterized. According to the crystallographic and spectroscopic results, all hydrates were identified as sII(Fd-3m) double hydrates, and among them, LGMs and gas molecules predominately occupied the large and small cages, respectively. The thermodynamic stability of each LGM+CH ₄ (and N ₂ ) hydrate is significantly improved compared to simple CH ₄ (and N ₂ ) hydrate. In particular, 14ECH exhibited several unique characteristics compared to the other two promoters. First, based on clear evidence from PXRD, NMR, Raman and DSC analyses, 14ECH was found to be a simple sII former with the largest size found so far. Second, 14ECH showed an excellent promotion effect comparable to THF, which is currently considered as the strongest promoter. Besides thermodynamic stability, the 14ECH + CH ₄ hydrate exhibits sufficiently high formation temperatures that little additional cooling is required. Considering these promising functions, the inventors believe that the 14ECH hydrate system can be used to promote hydrate-based technology. However, since this study mainly focused on basic characterization of the structure and stability of materials, for industrial applications, gas storage capacity, kinetics of gas uptake/release process, stability of the promoter itself, condition optimization and related areas. A number of key engineering points should be studied in future work, including Finally, we emphasize that the LGMs introduced here have great potential to act as an alternative to existing promoters and can be widely used in engineering and scientific research fields. The inventors also believe that the findings and results reported herein expand the basics of clathrate hydrates, particularly with respect to functional ice materials.

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application.

Claims (11)

1,2,3,4-diepoxybutane, 1,2-epoxycyclopentane, 1,3-epoxycyclopentane, 2,3-epoxytetrahydrofuran, 3,4-epoxytetrahydrofuran, 1, Including one or more compounds selected from 2-epoxycyclohexane, 1,3-epoxycyclohexane and 1,4-epoxycyclohexane, or containing a compound represented by Formula 1 together with the above compound,
Thermodynamic promoter for clathrate hydrate:
[Formula 1]

;
In Formula 1,
R ¹ _, R ² _, R ³ _, and R ⁴ are each independently hydrogen or a C _1-4 linear or branched alkyl group,
The C _1-4 linear or branched alkyl group is a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, an iso-butyl group, or a tert-butyl group. is chosen,
However, R ¹ , R ² , R ³ , and R ⁴ are simultaneously hydrogen.
According to claim 1,
The compound represented by Formula 1 is one selected from 1,2-epoxybutane, 2,3-epoxybutane, 1,2-epoxy-2-methylpropane, and 3,3-dimethyl-1,2-epoxybutane. A thermodynamic promoter for clathrate hydrate comprising the above compounds.
According to claim 1,
The thermodynamic promoter for the clathrate hydrate is a simple hydrate-forming promoter, a thermodynamic promoter for the clathrate hydrate.
Comprising a thermodynamic promoter for clathrate hydrate according to any one of claims 1 to 3,
clathrate hydrate.
According to claim 4,
The clathrate hydrate is reusable, clathrate hydrate.
According to claim 4,
The clathrate hydrate is formed at a temperature of 15 ° C. to 30 ° C. and a pressure of 20 to 90 atm.
Collecting gas using a clathrate hydrate comprising the thermodynamic promoter for the clathrate hydrate according to any one of claims 1 to 3,
gas collection method.
According to claim 7,
The gas collected by the gas collection method is CH ₄ , H ₂ , N ₂ , or CO ₂ ,
gas collection method.
According to claim 7,
The gas is collected in the clathrate hydrate at a temperature of 15 ° C to 30 ° C and a pressure of 20 to 90 atm,
gas collection method.
According to claim 7,
The gas storage capacity is 70% or more of the theoretical gas storage capacity.
According to claim 7,
The gas collection method further comprises at least one of collecting, storing, transporting, or dissociating the gas.

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