KR102329667B1 - Absorbent for separating carbon dioxide, method and appratus for separating carbon dioxide using the same - Google Patents

Abstract

The present invention relates to an absorbent for carbon dioxide separation containing an amino acid salt and a piperazine derivative, and a membrane contactor for carbon dioxide separation using the same. An economical carbon dioxide capture facility can be constructed by increasing the amount of carbon dioxide that can be removed per cycle while maintaining a similar carbon dioxide (CO _{2 ) absorption rate.}

Description

Absorbent for carbon dioxide separation, carbon dioxide separation method and separation device using the same

The present invention increases the amount of carbon dioxide that can be removed per cycle while maintaining a _{similar or superior carbon dioxide (CO 2} ) absorption rate compared to MEA, which is a commercially available material, through a mixed composition of an amino acid salt and a piperazine derivative, and the scale of the _{CO 2 collection facility} It relates to an absorbent for carbon dioxide separation that can reduce the amount of carbon dioxide and constitute an economical carbon dioxide capture facility, and a carbon dioxide separation method and separation device using the same.

Global warming, climate change, and abnormal climate are continuously aggravating due to the increase in the concentration of greenhouse gases in the atmosphere. Carbon dioxide, a representative greenhouse gas, is generated in large quantities in thermal power plants, steel mills, and chemical plants. If no technical measures are taken, it is predicted that by 2050, carbon dioxide will be emitted at a level of 62 Gton, and humankind will reach a point where global warming cannot be reversed.

Carbon dioxide capture and storage technology (CCS) is a promising solution as a short-term solution, but it has the disadvantage of large scale and high operating cost. In particular, in the case of existing thermal power plants, which are the main culprits of global warming, there is a practical difficulty in installing commercialized large-scale CCS facilities such as the amine absorption method because there is no spare site despite the remaining lifespan of several decades. Therefore, a membrane contactor technology that can reduce the facility volume to 1/10 level compared to the existing absorption tower can be an alternative, but membrane pore wetting due to long-term use and high absorbent renewable energy becoming a stumbling block.

As an absorbent in the existing membrane contactor process, an alkanolamine-based absorbent used in the existing amine absorption method is often used. For example, there are monoethanolamine (MEA), diethanolamine (DEA), 2-amino-2-methyl-1-propanol (AMP), and the like. There is a problem that causes a membrane pore-wetting phenomenon that inhibits operation.

As an alternative to this, the membrane itself may be made of PTFE (polytetrafluoroethylene) or PDMS (polydimethylsiloxane), which are materials having high hydrophobicity, but in this case, the cost of the membrane itself becomes very high. In addition, even if an expensive, highly hydrophobic membrane is used, there is a difficulty in commercialization due to the high operating cost (OPEX) due to the high renewable energy of the absorbent itself.

The present invention is to solve the problems of the prior art as described above, and an object of the present invention is to minimize the pore wetting of the membrane by increasing the surface tension while performing carbon dioxide removal more efficiently compared to the conventional absorbent when applied to a membrane contactor. It is to provide an absorbent for carbon dioxide separation that can be applied to a membrane contactor that can be used.

Another object of the present invention is to provide a method for separating carbon dioxide using the absorbent for separating carbon dioxide as described above.

Another object of the present invention is to provide a carbon dioxide separation apparatus for performing the carbon dioxide separation method as described above.

One aspect of the present invention for achieving the above object relates to an absorbent for carbon dioxide separation comprising an amino acid salt (A), a piperazine derivative (B) and water (C).

In the absorbent for carbon dioxide separation according to an embodiment of the present invention, the piperazine derivative may have a steric hindrance structure.

In addition, the piperazine derivative is 1- (2-hydroxyethyl) piperazine (1- (2-hydroxyethyl) piperazine), N- (2-aminoethyl) piperazine (N- (2-aminoethyl) piperazine), And cis-2,6-dimethylpiperazine (cis-2,6-dimethylpiperazine) may be at least one selected from.

In addition, the piperazine derivative may be a compound according to Structural Formula 1 below.

[Structural Formula 1]

In Structural Formula 1,

R ¹ is a C1-C6 alkyl group,

R ² is a C1-C6 alkyl group.

In addition, the amino acid salt may be a salt of at least one selected from potassium hydroxide, sodium hydroxide and lithium hydroxide and an amino acid.

In addition, the amino acid may be at least one selected from glycine, alanine, serine, cysteine, taurine, arginine gamma aminobutyrate, and histidine.

In addition, the amino acid may be serine.

In addition, the ratio (M1:M2) of the molar concentration (M1) of the piperazine derivative to the molar concentration (M2) of the amino acid salt may be 1:0.01 to 1:10.

In addition, the absorbent has a weight% concentration (((A+B)/(A+B+C))x100) of the total (A+B) of the amino acid salt (A) and the piperazine derivative (B) of 5 to 70 % by weight.

Also, the surface tension of the absorbent may have a value greater than 70 mN/m at 25°C.

Another aspect of the present invention includes the steps of preparing a final absorbent in which CO _{2 is absorbed by contacting carbon dioxide (CO 2} ) with the absorbent according to the present invention as described above, and _{(b) a portion of CO 2 in the final absorbent.} or as to separate all of the steps of manufacturing the recycled absorber, (c) in step, and (d) the saturated absorbent which is contacted with a gas mixture containing the said recirculating absorbent CO ₂ producing a saturation absorber of CO ₂ is reabsorbed It relates to a method for separating carbon dioxide from a mixed gas comprising the steps of separating _{CO 2 and regenerating a saturated absorbent.}

In the method for separating carbon dioxide from a mixed gas according to an embodiment of the present invention, the step (a) is (a-1) carbon dioxide (CO ₂ ) or _{a mixture of CO 2} and an inert gas in contact with an absorbent to CO ₂ It may include the steps of preparing a pretreated absorbent by absorbing and (a-2) _{separating a portion of CO 2} from the pretreated absorbent to prepare a final absorbent.

In addition, the step (a) may be a step of preparing a final absorbent in which _{carbon dioxide (CO 2} ) or _{a mixture of CO 2} and an inert gas is brought into contact with the absorbent to _{dissolve the CO 2 and remove the sediment or solid particles.}

Another aspect of the present invention is an absorbent treatment tower for preparing a final absorbent in which CO _{2 is absorbed by contacting carbon dioxide (CO 2} ) with the absorbent according to the present invention as described above, and the final absorbent from the absorbent treatment tower. A recirculation absorbent is prepared by receiving a supply and _{separating a part or all of CO 2} from the final absorbent, or a regeneration tower that receives a saturated absorbent from the absorption tower _{to separate CO 2} and regenerates the saturated absorbent, and the recycle absorbent from the regeneration tower supply is received on the carbon dioxide separation unit for separating carbon dioxide from mixed gas containing an absorber which is brought into contact with the recirculating absorbent with a gas mixture containing the CO ₂ absorbed material to CO ₂ in the recirculating absorber production of the saturated absorbent .

In the carbon dioxide separator for separating carbon dioxide from the mixed gas according to an embodiment of the present invention, the carbon dioxide separator lowers the temperature of the recycle absorbent discharged from the regeneration tower and supplied to the absorption tower or from the absorption tower It may further include a heat exchanger for increasing the temperature of the saturated absorbent discharged and supplied to the regeneration tower.

In addition, the carbon dioxide separation device may include a concentration meter for measuring _{the CO 2 concentration of the absorbent in the absorbent treatment tower.}

In addition, the carbon dioxide separation device may include a concentration meter for measuring _{the CO 2 concentration of the exhaust gas of the regeneration tower.}

In addition, the carbon dioxide separation device may include a concentration meter for measuring _{the CO 2 concentration of the exhaust gas of the absorption tower.}

The absorbent for carbon dioxide separation according to the present invention, through a mixed composition of an amino acid salt and a piperazine derivative, maintains a similar carbon dioxide absorption rate compared to 30 wt% MEA, a commercially available material, while increasing the amount of carbon dioxide that can be removed per cycle by 38% can have

In addition, through the application of the membrane contactor of the absorbent, the size of the process can be remarkably reduced compared to the conventional packed tower process for separating carbon dioxide, and energy consumed for the regeneration of the absorbent can be significantly reduced.

In addition, the absorbent for carbon dioxide separation according to the present invention can be widely used in the separation of greenhouse gases in the exhaust gas of power plants, the purification of natural gas, the recycling of biogas, and the like.

1 is a schematic diagram schematically showing a carbon dioxide separation device of the present invention.
2 is a photograph of a membrane contactor used as an absorption tower in the carbon dioxide separation device of the present invention.
3 shows the change in the amount of _{CO 2} absorbed with time of the absorbents of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-4.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Also, terms including an ordinal number such as first, second, etc. to be used below may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

In addition, when it is mentioned that a component is "on another component", "formed on another component" or "stacked on another component," it is directly applied to the front or one surface on the surface of the other component. It may be attached and formed or stacked, but it will be understood that other components may be further present in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail. However, this is provided as an example, and the present invention is not limited thereto, and the present invention is only defined by the scope of the claims to be described later.

Hereinafter, the absorbent for carbon dioxide separation of the present invention will be described.

The absorbent for carbon dioxide separation of the present invention includes an amino acid salt (A), a piperazine derivative (B), and water (C).

In the present invention, the piperazine derivative may have a steric hindrance structure.

In the present invention, the piperazine derivative is 1- (2-hydroxyethyl) piperazine (1- (2-hydroxyethyl) piperazine), N- (2-aminoethyl) piperazine (N- (2-aminoethyl) piperazine) and cis-2,6-dimethylpiperazine.

Here, the piperazine derivative may be a compound according to Structural Formula 1 below.

[Structural Formula 1]

In Structural Formula 1,

R ¹ is a C1-C6 alkyl group,

R ² is a C1-C6 alkyl group.

As a specific example, the C1-C6 alkyl group is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, an ethenyl group, a propenyl group, a butenyl group, a cyclopropyl group , a cyclobutyl group, a cyclopentyl group, or a cyclohexyl group, preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, or a hexyl group and more preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group.

In the present invention, the amino acid salt may be a salt of one or more selected from potassium hydroxide, sodium hydroxide and lithium hydroxide and an amino acid.

In the present invention, the amino acid may be one or more selected from glycine, alanine, serine, cysteine, taurine, arginine gamma aminobutyrate, and histidine, preferably serine.

In the present invention, the ratio (M1:M2) of the molar concentration (M1) of the piperazine derivative to the molar concentration (M2) of the amino acid or amino acid salt is preferably 1:0.01 to 1:10, more preferably 1:0.01 to 1:1, even more preferably 1:0.01 to 1:0.4. If the ratio (M1:M2) of the molar concentration (M1) of the piperazine derivative to the molar concentration (M2) of the amino acid or amino acid salt is less than 1:0.01, the concentration of the amino acid or amino acid salt is too low and the effect of increasing the surface tension of the absorbent is insignificant. It is undesirable, and when it exceeds 1:10, it becomes impossible to manufacture an absorbent due to the solubility limit of amino acids or amino acid salts, which is not preferable.

In addition, the weight% concentration (((A+B)/(A+B+C))x100) of the sum (A+B) of the amino acid salt (A) and the piperazine derivative (B) is 5 to 70 wt% Phosphorus is preferable, more preferably 20 to 50% by weight, and still more preferably 30 to 45% by weight.

The absorbent according to the present invention having the above composition has a surface tension of greater than 70 mN/m at 25°C.

The absorbent for carbon dioxide separation according to the present invention increases the surface tension of the absorbent solution itself by mixing an amino acid salt and a piperazine derivative as described above, and the piperazine derivative has a sterically hindered structure having a high absorption rate and removal rate. Stable operability can be secured by reducing membrane pore wetting of the contactor, and the effect of reducing operating costs by lowering the absorbent renewable energy can be achieved at the same time. In addition, by reducing the size of the existing packing tower or membrane contactor, it is possible to reduce the investment cost and construct an economical carbon dioxide collection facility.

Hereinafter, a method for separating carbon dioxide from the mixed gas of the present invention will be described.

Step (a): Preparation of final absorbent

Carbon dioxide (CO ₂ ) is brought into contact with the absorbent to prepare a final absorbent in which _{CO 2 is absorbed.}

In step (a), carbon dioxide (CO ₂ ) or _{a mixture of CO 2} and an inert gas is contacted with _{an absorbent to absorb CO 2} to prepare a pretreated absorbent, or a portion of CO ₂ is separated from the pretreated absorbent to obtain a final absorbent can be manufactured.

In addition, in step (a), carbon dioxide (CO ₂ ) or _{a mixture of CO 2} and an inert gas is brought into contact with the absorbent to _{dissolve CO 2} to prepare a final absorbent from which precipitates or solid particles are removed.

Step (b): Preparation of recirculating absorbent

A recycle absorbent may be prepared by separating some or all of _{CO 2} from the final absorbent.

Step (c): preparing a saturated absorbent

Contacting said recirculating absorbent with a gas mixture containing the CO ₂ can be manufactured according to the CO ₂ absorber saturated the reuptake.

step (d) CO ₂ isolate and regenerate the saturated absorbent

CO ₂ may be separated from the saturated absorbent and the saturated absorbent may be regenerated.

Next, the carbon dioxide separation device 10 of the present invention will be described with reference to FIG. 1 .

The carbon dioxide separation device 10 of the present invention may include an absorbent treatment tower 100 .

In the absorbent treatment tower 100 , carbon dioxide (CO ₂ ) or _{a mixture (Fa) of CO 2} and an inert gas is contacted with the absorbent (Fb) to prepare a final absorbent (Fc) in which _{CO 2 is absorbed.}

The carbon dioxide separation device 10 of the present invention may include a regeneration tower 200 .

In the regeneration tower 200, the final absorbent (Fc) is supplied from the absorbent treatment tower 100, and _{a part or all of CO 2} is separated from the final absorbent (Fc) to prepare a recycle absorbent (F4). have.

Alternatively, in the regeneration tower 200, the saturated absorbent (F2) may be supplied from the absorption tower 300 _{to separate CO 2} and regenerate the saturated absorbent.

The carbon dioxide separator 10 of the present invention may include an absorption tower 300 .

Being supplied to the recirculating absorber (F4) from the regeneration column (200), is contacted with a gas mixture (F1) contained the recycled CO ₂ absorbent can be recycled for re-absorption of CO ₂ absorber (F4). The mixed gas F1 may be a waste gas containing _{CO 2} generated from a steel mill, a thermal power plant, a landfill gas, and the like.

The carbon dioxide separator 10 of the present invention may further include a heat exchanger 500 .

In the heat exchanger 500 , the temperature of the recirculation absorbent F4 discharged from the regeneration tower 200 and supplied to the absorption tower 300 may be lowered. Alternatively, in the heat exchanger 500 , the temperature of the saturated final absorbent F2 discharged from the absorption tower 300 and supplied to the regeneration tower 200 may be increased.

In addition, the carbon dioxide separation device 10 may include a concentration meter 210 on the absorbent treatment tower 100 for measuring _{the CO 2 concentration of the absorbent in the absorbent treatment tower 100 .}

In addition, the carbon dioxide separation device 10 may include a concentration meter on the regeneration tower 200 for measuring _{the CO 2 concentration of the exhaust gas of the regeneration tower 200 .}

In addition, the carbon dioxide separator 10 may include a concentration meter 270 on the absorption tower 300 for measuring _{the CO 2 concentration of the exhaust gas of the absorption tower 300 .}

[ Example ]

Hereinafter, the present invention will be described in more detail by way of examples. However, this is for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example 1: Preparation of absorbent

Example One- 1: 2.5M N-(2- aminoethyl ) piperazine + 1.0 M potassium serinate

KOH of the same molar number as serine was added to an aqueous solution in which water and serine were mixed, and after sufficient stirring, N-(2-aminoethyl)piperazine was additionally added, followed by stirring until the suspended matter was no longer visible or the layer separation disappeared. A mixed absorbent for carbon dioxide separation was prepared by adding water so that the final amount was 600 ml to make N-(2-aminoethyl)piperazine 2.5M and potassium serinate 1.0M.

Example One- 2: 2.5M 1-(2-hydroxyethyl) piperazine + 1.0 M potassium serinate

An absorbent was prepared in the same manner as in Example 1-1, except that 1-(2-hydroxyethyl)piperazine was used instead of N-(2-aminoethyl)piperazine.

Example One- 3: 2.5 M cis-2,6- dimethylpiperazine + 1.0 M potassium serinate

An absorbent was prepared in the same manner as in Example 1, except that cis-2,6-dimethylpiperazine was used instead of N-(2-aminoethyl)piperazine.

comparative example One- 1: 2.5 M N-(2- aminoethyl ) piperazine

A mixed absorbent for carbon dioxide separation was prepared by mixing water and N-(2-aminoethyl)piperazine, adding water to make a final amount of 600ml, and making N-(2-aminoethyl)piperazine 2.5M.

comparative example One- 2: 2.5 M 1-(2-hydroxyethyl) piperazine

An absorbent was prepared in the same manner as in Comparative Example 1-1, except that 1-(2-hydroxyethyl)piperazine was used instead of N-(2-aminoethyl)piperazine.

comparative example One- 3: 1.0 M cis-2,6- dimethylpiperazine

An absorbent was prepared in the same manner as in Comparative Example 1-1, except that 1-(2-hydroxyethyl)piperazine was used instead of N-(2-aminoethyl)piperazine.

comparative example One- 4: 30 wt% (=5.0 M) MEA

Water was added to monoethylolamine, followed by stirring. A mixed absorbent for carbon dioxide separation was prepared by adding water so that the final amount was 600 ml so that the concentration of monoethanolamine was 5.0 M.

Example 2: Separation of carbon dioxide using absorbent

Example 2-1: Example CO using absorbent of 1-1 ₂ separation

Preparation of pretreatment absorbents

Referring to FIG. 1, 5L of the absorbent (Fb) of Example 1-1 was prepared at a concentration of 2.5 M piperazine (PZ) and 1.0 M potassium serinate (K-Ser) at room temperature, and the absorbent treatment tower 100 at 40° C. was injected into Since amino acids are cationized in aqueous solution when amino acids are added, equimolar KOH was slowly added to neutralize the cationized amino acids to neutralize them.

_{A mixture (Fa) having a volume ratio of CO 2} :N ₂ =15%:85% was prepared using a mass flow controller, and _{a flow rate of CO 2} was bubbled into the absorbent at 10 L/min and injected. The concentration of _{CO 2} discharged from the rear end of the absorbent treatment tower 100 was measured using a real-time gas analyzer 210 . If the concentration of CO ₂ to reach the 14.8% was prepared in the pre-absorber and terminate the CO ₂ absorption.

Preparation of the final absorbent

In order to prepare the remaining pretreatment absorbent produced in the treatment tower 100 as the final absorbent, the temperature of the treatment tower is raised to 80° C. ₂ was removed. _{When the concentration of CO 2} measured by the real-time gas analyzer 210 reached 1%, the stripping reaction was terminated to prepare the final absorbent (Fc) prepared for input into the actual process.

CO ₂ reabsorption

CO ₂ stripping and finally the final absorber (Fc) obtained after after introduced into regeneration column heat exchanger (500) passes through after the temperature has been around 60 ℃ circulated in CO ₂ absorber 300 of 40 ℃ CO ₂ uptake was executed. This recycle absorbent (F4) can be said to be the absorbent (F4) in the _{actual CO 2 separation process.}

The _{recirculating absorbent (F4) prepared for CO 2} reabsorption was injected into the lumen side of the hollow fiber membrane contactor which is the absorption tower 300 shown in FIG. 2 at a flow rate of 62 ml/min. By volume by _{CO 2: N 2 = 15%} : injecting a gas mixture (F1) of 85% to shell side of the absorber 300 in CO ₂ flow rate based on 36 ml / min was carried out by the CO ₂ absorbing material.

CO ₂ separation

Referring to FIG. 1 , the CO ₂ saturated absorbent F2 passed through the heat exchanger 500 and then heated to 120° C. in the regeneration tower 200 to _{separate CO 2} due to thermal energy and regenerate the absorbent. The recirculated absorbent (F4) from which CO ₂ was separated and regenerated was introduced to the top of the absorption tower after passing through the heat exchanger 500 again.

Example 2-2: Example CO2 separation using absorbent of 1-2

Carbon dioxide was separated in the same manner as in Example 1-1, except that the absorbent of Example 1-2 was used instead of the absorbent of Example 1-1 in the preparation of the pretreatment absorbent.

Example 2-3: Example CO2 separation using absorbents of 1-3

Carbon dioxide was separated in the same manner as in Example 1-1, except that the absorbent of Example 1-3 was used instead of the absorbent of Example 1-1 in the preparation of the pretreatment absorbent.

comparative example 2-1: comparative example 1-4 absorbent used CO ₂ separation

Carbon dioxide was separated in the same manner as in Example 1-1, except that the absorbent of Comparative Example 1-4 was used instead of the absorbent of Example 1-1 in the preparation of the pretreatment absorbent.

test example

test example 1: Carbon dioxide absorption by absorbent/ removal Characterization

For CO ₂ absorption, a pyrex glass reactor was maintained at a temperature of 40 using a water bath, and a water cooling device (water circulation of 4) was installed at the top of the reactor to prevent evaporation loss of the absorbent. Silica gel impingers were installed at the rear end of the gas mixer and the reactor to prevent moisture from entering the gas analyzer. The CO2 analyzer used Multi-Gas Analyzer (model: Multi Master).

_{A mixed gas having a volume ratio of CO 2} :N2=15%:85% was prepared using a mass flow controller, and the mixture was injected by bubbling into the absorbents prepared in Examples and Comparative Examples at a total flow rate of 2000 ml/min.

_{When the concentration of CO 2} discharged from the rear end using a real-time gas analyzer reached 14.8%, the absorption was terminated, the inside of the reactor was quickly purged with nitrogen, and the reactor was put into a constant temperature water bath of 80 to proceed with _{the CO 2 stripping reaction.} Only N2 of the same flow rate as the N2 flow rate during the absorption reaction was injected, and when the CO ₂ concentration of the exhaust gas reached 0.3%, the stripping reaction was terminated.

At this time, by applying the CO ₂ concentration and the CO ₂ flow rate of the gas over the absorbent confiscated such as state equation written as a 30-second intervals was calculated and the CO ₂ absorption rate CO ₂ absorption amount (CO ₂ loading).

The test results are shown in Table 1 and FIG. 3 below.

Absorbent composition Max. CO ₂ loading(mol/L) Lean CO ₂ loading(mol/L) Cyclic capacity Example 1-1
2.5M N-(2-Aminoethyl)PZ + 1.0M K-Ser 3.516 2.133 1.383 Example 1-2
2.5 M 1-(2-hydroxyethyl)PZ + 1.0M K-Ser 2.290 1.020 1.270 Example 1-3 2.5 M cis-2,6-dimethylpiperazine + 1.0M K-Ser 3.022 1.305 1.672 comparative example 1-1 2.5M N-(2-Aminoethyl)PZ 2.846 1.580 1.266 comparative example 1-2 2.5 M 1-(2-hydroxyethyl)PZ 1.656 0.599 1.056 comparative example 1-3 1.0 M cis-2,6-dimethylpiperazine 1.054 0.411 0.643 comparative example 1-4 30% MEA 3.131 1.830 1.301

Referring to Table 1 and FIG. 3, in the case of 2-aminoethyl piperazine and 2-Hydxoryethyl piperazine, CO ₂ loading (Max CO ₂ loading) and absorption rate were dramatically increased _{during absorption through the addition of potassium serinate, and CO 2 per cycle} It can be seen that the removal amount, cyclic capacity, increased by 10-20%.

In addition, in the case of cis-2,6-dimethyl piperazine, when used alone, at a concentration of 1.0 M or higher, the experiment could not be continued, such _{as the CO 2} injection part was blocked due to the sediment generated during _{CO 2 absorption.} It was confirmed that stable operation was possible because precipitation did not occur even if it was prepared up to M concentration _{and absorbed CO 2 .} This means that the added potassium serinate has the effect of increasing solubility.

Analyzing the test results as described above, the addition of a small amount of amino acid salt (eg potassium serinate) has _{the effect of 1) increasing the absorption rate and CO 2} absorption capacity, and 2) reacting with _{CO 2} when the PZ derivative is used at a high concentration. It can be seen that there is an effect of enabling stable operation by preventing precipitation that may occur.

test example 2: CO ₂ Removal rate

The absorbent was prepared by calculating the amount of absorbent required for the membrane contactor test for _{CO 2 reabsorption.} The specifications of the membrane contactor for testing the performance of the absorbent are shown in Table 1, and the photograph of the membrane contactor is shown in FIG. _{The CO 2} removal rate 5 minutes after reaching stabilization from the time when the recycle absorbent is introduced into the absorption tower was calculated by Equation 1 below and shown in Table 2.

Calculation 1

CO ₂ Removal Rate (%)= ((C ₁ -C ₂ )/C ₁ )x100

In Equation 1, C _{1 is the concentration of CO 2} in the mixed gas introduced into the shell side of the membrane contactor, and C ₂ is the concentration _{of CO 2} in the exhaust gas discharged from the membrane contactor.

Kinds value Outer diameter of hollow fiber (μm) 840 Fiber inner diameter (μm) 600 Hollow fiber porosity (%) 67 Hollow fiber length (mm) 270 Number of fibers 100 Average pore size (μm) 0.15 Module packing density (%) 45

Absorbent composition CO ₂ Removal Rate (%) Example 2-1
2.5M N-(2-Aminoethyl)PZ + 1.0M K-Ser - Example 2-2
2.5 M 1-(2-hydroxyethyl)PZ + 1.0M K-Ser - Example 2-3 2.5 M cis-2,6-dimethylpiperazine + 1.0M K-Ser - comparative example 2-1 30% MEA (5.0M) 81.8

test example 3: Comparison of surface tension by absorbent

The surface tension of the absorbents prepared according to Examples 1 to 3 and Comparative Examples 1 to 4 was measured at 25° C. using the maximum bubble pressure measurement method (BP2, Kruss) and summarized in Table 4 below.

Absorbent composition Surface tension (mN/m) Example 1-1 2.5M N-(2-Aminoethyl)PZ + 1.0M K-Ser 73.8 Example 1-2 2.5 M 1-(2-hydroxyethyl)PZ + 1.0M K-Ser 74.0 Example 1-3 2.5 M cis-2,6-dimethylpiperazine + 1.0M K-Ser 73.6 comparative example 1-4 30% MEA 68.1

As can be seen from Table 4, in the case of the absorbent according to the present invention, it can be confirmed that the surface tension is significantly higher than that of the conventional absorbent. be able to

Although preferred embodiments of the present invention have been described above, those of ordinary skill in the art can add, change, delete or The present invention may be variously modified and changed by addition, etc., and this will also be included within the scope of the present invention. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form. The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (18)

amino acid salt (A);
piperazine derivatives (B); and
water (C): comprising;
The piperazine derivative has a steric hindrance structure,
The piperazine derivative is 1- (2-hydroxyethyl) piperazine (1- (2-hydroxyethyl) piperazine), N- (2-aminoethyl) piperazine (N- (2-aminoethyl) piperazine), and cis -2,6-dimethylpiperazine (cis-2,6-dimethylpiperazine) is at least one selected from,
The amino acid salt is a salt of potassium hydroxide and serine,
The ratio (M1:M2) of the molar concentration (M1) of the piperazine derivative to the molar concentration (M2) of the amino acid salt is 1:0.01 to 1:10, the absorbent for separating carbon dioxide. delete delete According to claim 1,
Absorbent for carbon dioxide separation, characterized in that the piperazine derivative is a compound according to Structural Formula 1 below:
[Structural Formula 1]

In Structural Formula 1,
R ¹ is a C1-C6 alkyl group,
R ² is a C1-C6 alkyl group. delete delete delete delete According to claim 1,
The absorbent has a weight% concentration (((A+B)/(A+B+C))x100) of 5 to 70% by weight of the total (A+B) of the amino acid salt (A) and the piperazine derivative (B) Absorbent for carbon dioxide separation, characterized in that. According to claim 1,
The absorbent for carbon dioxide separation, characterized in that the surface tension of the absorbent has a value greater than 70 mN/m at 25°C. (a) preparing a final absorbent in which _{CO 2} is absorbed by contacting carbon dioxide (CO ₂ ) with the absorbent according to claim 1;
(b) preparing a recycled absorbent by separating some or all of _{CO 2} from the final absorbent;
(c) contacting said recirculating absorbent with a gas mixture containing the CO ₂ producing a saturated CO ₂ absorbent of the absorbing material; and
(d) _{separating CO 2} from the saturated absorbent and regenerating the saturated absorbent;
The absorbent according to claim 1
amino acid salt (A);
piperazine derivatives (B); and
water (C): comprising;
The piperazine derivative has a steric hindrance structure,
The piperazine derivative is 1- (2-hydroxyethyl) piperazine (1- (2-hydroxyethyl) piperazine), N- (2-aminoethyl) piperazine (N- (2-aminoethyl) piperazine), and cis -2,6-dimethylpiperazine (cis-2,6-dimethylpiperazine) is at least one selected from,
The amino acid salt is a salt of potassium hydroxide and serine,
A method for separating carbon dioxide from a mixed gas, wherein the ratio (M1:M2) of the molar concentration (M1) of the piperazine derivative to the molar concentration (M2) of the amino acid salt is 1:0.01 to 1:10. 12. The method of claim 11,
Step (a) is
(a-1) _{contacting carbon dioxide (CO 2} ) or _{a mixture of CO 2} and an inert gas with an absorbent _{to absorb CO 2} to prepare a pretreated absorbent; and
(a-2) preparing a final absorbent by separating a portion of _{CO 2 from the pretreated absorbent;} 12. The method of claim 11,
Step (a) is carbon dioxide (CO ₂ ) or _{a mixture of CO 2} and an inert gas in contact with an absorbent to _{dissolve CO 2} to prepare a final absorbent from which precipitates or solid particles are removed. How to separate. an absorbent treatment tower for preparing a final absorbent in which CO _{2 is absorbed by contacting carbon dioxide (CO 2} ) with the absorbent according to claim 1;
Regeneration of receiving the final absorbent from the absorbent treatment tower _{and separating some or all of CO 2} from the final absorbent to prepare a recycle absorbent, or receiving a saturated absorbent from the absorption tower _{to separate CO 2} and regenerate the saturated absorbent tower; and
Being supplied to the recirculated absorbent from the regeneration column, contacting said recirculating absorbent with a gas mixture containing the CO ₂ absorbed by the material recycled to the CO ₂ absorber absorber for preparing the saturated absorbent; including,
The absorbent according to claim 1
amino acid salt (A);
piperazine derivatives (B); and
water (C): comprising;
The piperazine derivative has a steric hindrance structure,
The piperazine derivative is 1- (2-hydroxyethyl) piperazine (1- (2-hydroxyethyl) piperazine), N- (2-aminoethyl) piperazine (N- (2-aminoethyl) piperazine), and cis -2,6-dimethylpiperazine (cis-2,6-dimethylpiperazine) is at least one selected from,
The amino acid salt is a salt of potassium hydroxide and serine,
A carbon dioxide separation device for separating carbon dioxide from a mixed gas, wherein the ratio (M1:M2) of the molar concentration (M1) of the piperazine derivative to the molar concentration (M2) of the amino acid salt is 1:0.01 to 1:10. 15. The method of claim 14,
The carbon dioxide separator
Carbon dioxide, characterized in that it further comprises a heat exchanger for lowering the temperature of the recycle absorbent discharged from the regeneration tower and supplied to the absorption tower or to increase the temperature of the saturated absorbent discharged from the absorption tower and supplied to the regeneration tower separation device. 15. The method of claim 14,
Carbon dioxide separation device, characterized in that the carbon dioxide separation device comprises a concentration measuring device for measuring _{the CO 2} concentration of the absorbent in the absorbent treatment tower. 15. The method of claim 14,
Carbon dioxide separation device, characterized in that the carbon dioxide separation device comprises a concentration measuring device for measuring _{the CO 2} concentration of the exhaust gas of the regeneration tower. 15. The method of claim 14,
Carbon dioxide separation device, characterized in that the carbon dioxide separation device comprises a concentration measuring device for measuring _{the CO 2} concentration of the exhaust gas of the absorption tower.

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