KR101522382B1 - Carbon dioxide absorber for making high-efficient carbon dioxide hydrate at atmospheric pressure and manufacturind method thereof - Google Patents

Abstract

The present invention relates to a carbon dioxide absorbent for manufacturing a high-efficient carbon dioxide hydrate at atmospheric pressure, and a manufacturing method thereof, and more specifically, to a carbon dioxide absorbent for manufacturing a high-efficient carbon dioxide hydrate at atmospheric pressure, which has effects of reducing greenhouse gas by collecting CO_2 discharged from exhaust gas after combustion as well as of saving energy due to storing and transporting CO_2, and applying a cooling system in a combined heat and power system, and can significantly reduce energy costs since equilibrium pressure of the gas hydrate can be decreased to atmospheric pressure and can reduce the power of a compressor, and to a manufacturing method thereof. The carbon dioxide absorbent for manufacturing a high-efficient carbon dioxide hydrate at atmospheric pressure comprises tetrahydrofuran (THF), nanoparticles, a surfactant, and water.

Description

TECHNICAL FIELD [0001] The present invention relates to a carbon dioxide absorbent capable of producing high-efficiency carbon dioxide hydrate at normal pressure and a method of producing the same. BACKGROUND ART [0002]

The present invention is to recover, and more particularly, CO ₂ coming out from the exhaust gas after combustion relates to a method for producing that can be produced the carbon dioxide hydrate with high efficiency at ambient pressure carbon dioxide absorber and it, as well as a greenhouse gas reduction CO ₂ storage and It has energy saving effect by application of cooling system in transportation, heat merging power generation, and it can reduce the equilibrium pressure of gas hydrate to atmospheric pressure, so it can reduce the power of compressor. Therefore, high efficiency carbon dioxide hydrate A carbon dioxide absorbent which can be produced at normal pressure, and a method for producing the carbon dioxide absorbent.

In general, oil is the main source of energy for human beings. Many of these uses of oil have caused serious problems due to the emission of air pollutants and global warming due to the greenhouse effect. The Kyoto Protocol was adopted in 1997 to regulate the emission of carbon dioxide, the main cause of global warming. The Kyoto Protocol was officially in effect on February 16, 2005, and Korea will be included in the regulated countries in 2013. Therefore, efforts to reduce carbon dioxide are urgently needed, and it is urgent to develop various technologies for this purpose.

Various technologies for appropriately separating and / or collecting carbon dioxide have been developed in accordance with such circumstances. Methods for separating carbon dioxide (CO ₂ ) from exhaust gases and natural gas from chemical plants, power plants, and large boilers are the absorption, adsorption, separation membrane, and deep-sea cooling methods.

When the concentration of carbon dioxide emitted is low, the absorption method and the adsorption method are frequently used. Such an absorption method or an adsorption method is widely used because it can selectively remove only some gases that are absorbed or adsorbed well by an absorbent or an adsorbent. However, the adsorbent and the adsorbent are chemically deformed during the separation process and periodic replacement is required. Therefore, when a solid adsorbent is used, it is advantageous to apply only when the change period of the adsorbent is long, because the chemical modification of the adsorbent is small. On the other hand, since the absorption method uses a liquid absorbent, it is easy to replace the absorbent, It is widely used for purification of exhaust gas and gas separation, but there is a drawback that the absorbent is chemically or thermally deformed.

In addition, the development of techniques for separating and / or collecting carbon dioxide using polymer membranes is actively under way, but the existing polymer membranes are in the form of upper bound, which is a graph showing the correlation between the permeability and selectivity reported by Robeson in 2008 Permeability and selectivity. That is, when the transmittance increases, the selectivity decreases or vice versa.

On the other hand, the CO ₂ recovering technique using a gas hydrate in a number of methods for CO ₂ recovery as above. The characteristic of CO ₂ recovery using gas hydrate is that it is an eco-friendly method which does not cause corrosion problem, which is a disadvantage of wet process using amine series, and it is less expensive than CO ₂ capture method by chemical absorption method, It is easy to store and store, and the method of regenerating is easy. Therefore, this technique can be very advantageously applied not only to the recovery of CO ₂ but also to transportation and storage.

However, since the gas hydrate used in such a technique is formed at a high pressure and a low temperature, there is a problem that a large amount of energy, effort, and expensive materials are required to maintain the environment of high pressure and low temperature, which is a general formation atmosphere of gas hydrate, In order to absorb the released CO ₂ into the gas hydrate, it is necessary to lower the pressure of the gas hydrate generated at the high pressure to the atmospheric pressure.

Therefore, a gas hydrate that can be produced at normal pressure to absorb carbon dioxide is required. However, gas hydrate prepared at normal pressure requires a method of producing gas hydrate for absorbing more carbon dioxide because the water absorption rate is low.

The present invention is one made in view the above problems, the object of the present invention to recover the CO ₂ coming out from the exhaust gas after combustion, reducing greenhouse gas emissions as well as CO ₂ air conditioning system in the storage and transportation, combined heat and power generation The carbon dioxide absorbent capable of producing a high-efficiency carbon dioxide hydrate at a normal pressure, which can reduce the energy cost of the compressor by reducing the equilibrium pressure of the gas hydrate to atmospheric pressure by reducing the power of the compressor, And a method for manufacturing the same.

These and other objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof.

This object is achieved by a carbon dioxide absorbent capable of producing high-efficiency carbon dioxide hydrate at normal pressure, characterized by comprising tetrahydrofuran (THF), nanoparticles, surfactants and water.

The nanoparticles may be silica or alumina having a size of less than 100 nanometers.

Preferably, the surfactant is sodium dodecyl sulfate (SDS).

More preferably, the nanoparticles are alumina and the surfactant is sodium dodecyl sulfate.

Preferably, the THF is 5 to 20% by weight of the total weight of the absorbent.

Preferably, the nanoparticles are present in an amount of 0.01 to 1% by weight based on the total weight of the sorbent.

Preferably, the surfactant is 0.01 to 10% by weight of the total weight of the absorbent.

Preferably, it further comprises at least one additive selected from the group consisting of polyethylene glycol (PEG), Silwet l-77, zeolite, cerium oxide (CeO ₂ ) and methanol (CH ₃ OH).

The above object can also be achieved by a method for producing a carbon dioxide absorbent comprising the steps of adding tetrahydrofuran (THF) and a surfactant to water and stirring to prepare a mixture, and adding a nanoparticle to the mixture and stirring to prepare a carbon dioxide absorbent Wherein the carbon dioxide absorbent is a carbon dioxide absorbent which is capable of producing carbon dioxide hydrate of high efficiency at normal pressure.

The first step is characterized by further adding at least one additive selected from the group consisting of polyethylene glycol (PEG), Silwet l-77, zeolite, cerium oxide (CeO ₂ ) and methanol (CH ₃ OH).

According to the present invention, it is possible to recover CO ₂ coming from the exhaust gas after combustion and to reduce the greenhouse gas, CO ₂ storage and transportation, energy saving effect by application of the cooling system in the thermal combined power generation, It is possible to reduce the power of the compressor because it can be lowered to the atmospheric pressure, so that the energy cost can be remarkably reduced.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view illustrating a process for producing carbon dioxide hydrate using a carbon dioxide absorbent capable of producing high-efficiency carbon dioxide hydrate at normal pressure according to an embodiment of the present invention. FIG.
2 is a view showing an apparatus for producing a gas hydrate according to an embodiment of the present invention.
3 is a graph showing the amount of gas hydrate produced according to the additive.
4 is a graph showing the amount of gas hydrate produced according to THF concentration.
FIG. 5 is a graph showing the amount of gas hydrate produced by addition of Al ₂ O _{3 to} SDS.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It will be apparent to those skilled in the art that these embodiments are provided by way of illustration only for the purpose of more particularly illustrating the present invention and that the scope of the present invention is not limited by these embodiments .

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

Unless otherwise stated, all percentages, parts, and percentages are by weight. It will also be understood that when an amount, concentration, or other value or parameter is given in any one of a range, a preferred range, or a list of preferred upper limits and preferred lower limits, it is understood that any upper limit range, It should be understood that specifically all ranges formed from any pair of range limits or desirable values are to be understood. Where a range of numerical values is referred to in this specification, unless otherwise stated, the range is intended to include all the integers and fractions within the endpoint and its range. The scope of the present invention is not intended to be limited to the specific values that are mentioned when defining the scope.

When the term "about" is used to describe the endpoint of a value or range, it is to be understood that the present disclosure encompasses the particular value or endpoint mentioned.

As used herein, the terms "comprise," "include," "including," "including," "containing," " Having ", " having ", " having ", or any other variation thereof, are intended to cover an inclusion not exclusive. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to such elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus It is possible. Also, unless explicitly stated to the contrary, "or" does not mean " comprehensive " or " exclusive "

Where an applicant defines an invention or portion thereof in an open term such as "comprising ", it should be readily understood that the description should be interpreted as describing the invention using the term" consisting essentially & do.

The carbon dioxide absorbent capable of producing high-efficiency carbon dioxide hydrate at normal pressure according to one embodiment of the present invention is characterized by containing tetrahydrofuran (THF), nanoparticles, a surfactant and water. Carbon dioxide hydrate is produced by reacting carbon dioxide gas with an absorbent comprising water.

Tetrahydrofuran (THF) and surfactants function to produce carbon dioxide hydrate at normal pressure by lowering the equilibrium pressure of gas hydrate.

The crystal structure of the gas hydrate is composed of polyhedral cavities formed by water molecules composed of hydrogen bonds. The body-centered cubic structure I (sI) , A diamond cubic structure II (II) and a hexagonal structure H (sH). sI and sII are determined by the size of the object molecule. As the amount of THF increases, the structure of the gas hydrate changes from SI to S-II, and the SI structure reduces the amount of carbon dioxide captured because the lattice structure that captures CO ₂ is smaller than that of the S-II structure. The THF is preferably 5 to 20 wt% of the total weight of the absorbent. If the THF content is less than 5 wt%, it is difficult to produce carbon dioxide hydrate at normal pressure. If the THF content is more than 20 wt%, the process point of the hydrate changes, and the hydrate is present in a solid phase instead of a liquid phase (slurry) It is because it will block. If the pipe is blocked, there is a problem in that it is difficult to transport it for future cooling system application.

The surfactant is preferably sodium dodecyl sulfate (SDS), but is not limited thereto. The concentration of such a surfactant is preferably 0.01 to 10% by weight based on the total weight of the absorbent. As the concentration of the surfactant increases, the anion is adsorbed on the surface of the hydrate particles due to the SDS monomer. Such a phenomenon causes a significant increase in the negative charge on the slip surface of the interface, resulting in an increase in the production rate of carbon dioxide hydrate. If the concentration exceeds 10% by weight, if the adsorption at the interface becomes excessively large, the adsorption of CO ₂ is hindered. On the other hand, if the concentration of the surfactant is less than 0.01% by weight, it is not possible to achieve the desired purpose of adding a surfactant.

In addition, nanoparticles, such as silica (SiO ₂₎ or alumina in the case of (Al ₂ O _3), but can increase the carbon dioxide hydrate generation rate due to absorption to some extent the concentration of, excessive adsorption to form a film on the surface of CO ₂ is the carbon dioxide It is preferable that the content of the nanoparticles is 0.1 to 1% by weight based on the total weight of the absorbent, since it may interfere with trapping into the hydrate lattice space. Also for the same reason, the size of the alumina nanoparticles is preferably less than 100 nanometers. That is, when the size of the nanoparticles is larger than this, CO ₂ may be prevented from being trapped in the carbon dioxide hydrate lattice space.

Carbon dioxide absorbent capable of producing carbon dioxide hydrate with high efficiency at ambient pressure according to the present invention, at least one additive of the polyethylene glycol (PEG), Silwet l-77 , zeolite, ceria (CeO _2), and methanol (CH ₃ OH) . Silwet L-77, for example, can lower the equilibrium pressure of hydrates and allow hydrates to be produced at atmospheric pressure. Polyethylene glycol and methanol are also used to increase the yield of gas hydrate with high solubility of carbon dioxide in water It is possible.

It is apparent from FIG. 1 that a process for producing carbon dioxide hydrate using a carbon dioxide absorbent capable of producing a high-efficiency carbon dioxide hydrate at an atmospheric pressure according to an embodiment of the present invention is shown in FIG. 1, wherein the high-efficiency carbon dioxide hydrate A method for producing a carbon dioxide absorbent which can be produced includes a first step of adding tetrahydrofuran (THF) and a surfactant to water and stirring to prepare a mixture, a step of adding nanoparticles to the mixture and stirring the mixture to prepare a carbon dioxide absorbent And a second step.

The first step and / or the second step may further include an ultrasonic pulverizing step. That is, the stirred mixture of the first stage may be subjected to ultrasonic pulverization and / or the stirred carbon dioxide absorbent of the second stage may be ultrasonically pulverized.

Stirring in the first and second steps is to stir the aqueous solution using a rod or a stirring rod or the like so that the mixed materials are mixed well and can effectively absorb carbon dioxide. In addition, ultrasonic waves can be used to better mix the materials mixed using the magnet. If the ultrasonic wave is used, the temperature of the fluid is increased. Therefore, it is preferable to cool the water by using cooling water so that the temperature is not significantly heated. Preferably the time of use of the ultrasonic mill is from 30 minutes to 3 hours. Particularly, when the nanoparticles are added for a short period of time, the size of the particles in the nanofluid increases, causing problems in dispersion stability. However, since the particle size can be maintained at a constant particle size over 80 minutes, Preferably less than 3 hours.

Carbon dioxide hydrate is prepared by reacting the carbon dioxide absorbent prepared above with carbon dioxide gas. The prepared carbon dioxide absorbent is preferably put in a test section and then continuously mixed using an overhead stirrer. This treatment shortens the production and production time of carbon dioxide hydrate. The stirring speed of the overhead stirrer in the stirring process may be 100 to 600 rpm.

Hereinafter, the structure and effect of the present invention will be described in more detail with reference to examples and comparative examples. However, this embodiment is intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

[Example 1]

To 1600 g of distilled water, THF was added so as to be 10 wt% of THF, and then SDS was further added so as to be 0.1 wt% of SDS. Then, the mixture was stirred for about 100 minutes using a stirrer to prepare a carbon dioxide absorbent.

[Example 2]

A carbon dioxide absorbent was prepared in the same manner as in Example 1, except that the THF was 20% by weight.

[Example 3]

To 1600 g of distilled water was added THF so as to be 10 wt% of THF, and then PEG was added to 10 wt% of PEG. Then, the mixture was stirred for about 100 minutes using a stirrer to prepare a carbon dioxide absorbent.

[Example 4]

To 1600 g of distilled water, THF was added so as to be 10 wt% of THF, and then SDS was further added so as to be 0.1 wt% of SDS. Then, the mixture was stirred for about 100 minutes using a stirrer, and then alumina was added to 0.1% by weight of alumina. The mixture was stirred for about 100 minutes using a stirrer and an ultrasonic mill to prepare a carbon dioxide absorbent.

[Comparative Example 1]

1600g A carbon dioxide absorbent was prepared in the same manner as in Example 1 except that the distillated water contained only 10% by weight of THF in Comparative Example 1.

[Comparative Example 2]

A carbon dioxide absorbent was prepared in the same manner as in Example 1, except that 0.1 wt% of silica was added instead of 0.1 wt% of SDS.

[Comparative Example 3]

A carbon dioxide absorbent was prepared in the same manner as in Example 1, except that 0.1 wt% of zeolite was added instead of 0.1 wt% of SDS.

[Comparative Example 4]

A carbon dioxide absorbent was prepared in the same manner as in Example 1, except that 0.1 wt% of alumina was added instead of 0.1 wt% of SDS.

[Comparative Example 5]

A carbon dioxide absorbent was prepared in the same manner as in Example 1, except that 0.1 wt% of cerium oxide was added instead of 0.1 wt% of SDS.

Using the carbon dioxide absorbent according to Examples 1 to 4 and Comparative Examples 1 to 5, the amount of carbon dioxide consumed was measured by the following experimental example, and the results are shown in FIGS. 3 to 5.

[Experimental Example]

The carbon dioxide absorbent prepared above was injected with CO ₂ gas and mixed through an overhead stirrer. The mixture was then cooled to 10 ° C and saturated. The temperature of the mixture was then lowered to 0 ° C and the hydrate was formed. In the case of Examples 1 and 3, the same experiment was carried out for 13 hours.

A method for producing CO ₂ hydrate is illustrated in FIG. 2, which is a drawing of a gas hydrate generating apparatus according to an embodiment of the present invention. In Fig. 2, a solid line indicates a piping, and a broken line indicates a wiring. On the other hand, Fig. 2 is similar to the production apparatus shown in Japanese Patent Application Laid-Open No. 10-2012-0023912, so that the components not described here can be based on the above-mentioned patent documents.

carbon dioxide The hydrate is generated in a reactor equipped with an overhead stirrer 13, and a sight glass is installed to confirm generation of carbon dioxide hydrate. The regulator 2 is for maintaining a constant CO ₂ injection pressure into the reactor. An actuator valve (4) is provided for opening and closing the gas tank (1) to which gas is supplied and the pressure of the reactor. In addition, a relief valve 6, a check valve 12 and a needle valve (left lower end 11) are provided for preventing the backflow of gas and controlling the flow rate, and the gas consumption is measured through the flow meter 11. An RTD (7) and a pressure gauge (8, accuracy within 0.008%) are used for the reactor and piping, and an overhead stirrer (13) is used for agitation of the carbon dioxide hydrate. The temperature of the reactor is maintained using an external constant temperature water bath and an internal constant temperature water bath, and all measured values are collected by the data collection unit 18. In this experiment, the pressure was set to normal pressure, the temperature of the constant temperature bath was 0 ° C, and the speed of the overhead stirrer (13) was 200 rpm. The flow rate of CO ₂ was 200 ccm.

Prior to this experiment, the inside of the reactor is made into a vacuum state, and then the absorbent is injected. By using an agitator, it is possible to effectively mix the absorbent and the gas to shorten the reaction time. The control program opens and closes the two actuator valves (4 and valves under the vacuum gauge). When the pressure in the reservoir and the reactor becomes a certain pressure, the valve opens and CO ₂ is supplied to the reactor. At this time, the pressure in the reactor is reduced as the absorption takes place in the reactor. When the pressure in the reactor becomes lower than the experimental pressure, the valve is opened and the amount of gas entering the reactor is measured by the flow meter.

FIG. 3 is a graph showing the amount of gas hydrate produced according to the additive, FIG. 4 is a graph showing the amount of gas hydrate produced according to THF concentration, and FIG. 5 is a graph showing the amount of gas hydrate produced by addition of Al ₂ O _{3 to} SDS to be.

As can be seen from FIG. 3, it was confirmed that the water and zeolite (Comparative Example 3), silica (Comparative Example 2), alumina (Comparative Example 4) and cerium oxide (Comparative Example 1) (Example 1) or water, and THF and PEG (Example 3) are used together with water, THF and the case of using only one of them, that is, the production rate of carbon dioxide hydrate is increased . Particularly, it can be confirmed that consumption of carbon dioxide is increased by using water, THF and SDS (Example 1) together.

Also, as can be seen from FIG. 4, it can be seen that the amount of carbon dioxide hydrate is the largest when THF in the absorbent according to an embodiment of the present invention is 20 wt% of the total weight of the absorbent (Example 2).

Also, as can be seen from FIG. 5, it can be seen that the production rate of carbon dioxide hydrate is the greatest in the case of the absorbent according to Example 4 of the present invention, compared to only using water, THF and SDS (Example 1).

As described above, the conventional gas hydrate is a hydrate generated at a high pressure, which eventually necessitates a high-pressure compression. However, according to one aspect of the present invention, THF is added to reduce the generation pressure and SDS and Al ₂ O ₃ was added to increase the production rate, and it can be confirmed that it can be used as an absorbent for application to a cooling system in the future.

It is to be understood that the present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

1: gas tank 2: regulator
3: Air compressor 4: Actuator valve
5: Supply Vesure 6: Relief Valve
7: Temperature sensor 8: Pressure sensor
9: Pressure gauge 10: Vacuum gauge
11: Flow meter 12: Check valve
13: overhead stirrer 14: internal temperature controller
15: impeller 16: test part
17: external temperature control device 18: data collection device
19: Computer

Claims (10)

A carbon dioxide absorbent capable of producing high-efficiency carbon dioxide hydrate at normal pressure, characterized by comprising tetrahydrofuran (THF), nanoparticles, a surfactant and water. The method according to claim 1,
Characterized in that the nanoparticles have a size of less than 100 nanometers as silica or alumina and can produce carbon dioxide hydrate at high pressure at normal pressure. The method according to claim 1,
Wherein the surfactant is sodium dodecyl sulfate (SDS). A carbon dioxide absorbent capable of producing high-efficiency carbon dioxide hydrate at normal pressure. The method according to claim 1,
Wherein the nanoparticle is alumina and the surfactant is sodium dodecyl sulfate. 2. A carbon dioxide absorbent according to claim 1, wherein the carbon dioxide hydrate is carbon dioxide hydrate. The method according to claim 1,
Wherein the THF is from 5 to 20% by weight of the total weight of the absorbent, wherein the carbon dioxide hydrate is capable of producing high-efficiency carbon dioxide hydrate at normal pressure. The method according to claim 1,
Wherein the nanoparticles are 0.01 to 1% by weight of the total weight of the absorbent. The carbon dioxide absorbent is capable of producing high-efficiency carbon dioxide hydrate at normal pressure. The method according to claim 1,
Wherein the surfactant is 0.01 to 10% by weight based on the total weight of the absorbent, wherein the carbon dioxide hydrate can be produced at atmospheric pressure. 8. The method according to any one of claims 1 to 7,
Characterized in that it further comprises at least one additive selected from the group consisting of polyethylene glycol (PEG), Silwet l-77, zeolite, cerium oxide (CeO ₂ ) and methanol (CH ₃ OH). Carbon dioxide absorbent. A first step of adding tetrahydrofuran (THF) and a surfactant to water and stirring to prepare a mixture; and
And a second step of adding a nanoparticle to the mixture and stirring the carbon nanofibers to produce a carbon dioxide absorbent. The method of producing a carbon dioxide absorbent according to claim 1, wherein the carbon dioxide hydrate is carbon dioxide. 10. The method of claim 9,
The first step is a polyethylene glycol (PEG), Silwet l-77 , zeolite, ceria (CeO _2), and methanol (CH ₃ OH) of at least one high efficiency of carbon dioxide hydrate, which is characterized by further adding additives A method for producing a carbon dioxide absorbent which can be produced at normal pressure.

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