KR20210097297A - Adsorbent including a polyvinylidene fluoride based activated carbon, method of preparing the same, and adsorption method of methane or carbon dioxide using the same - Google Patents

Abstract

One embodiment of the present invention provides a method for manufacturing an adsorbent including activated carbon based on methane and/or polyvinylidene fluoride, including the steps of: a) filling a boat with a PVdF-based polymer and putting it into a kiln; b) forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted by heating the filled boat in a CO_2 flow atmosphere; c) maintaining the formed PVdF-based polymer film at a reaction temperature of 600 to 900 deg. C for 1 to 3 hours to activate the same; and d) recovering activated carbon by lowering the temperature at a rate of greater than 1 deg. C and less than 5 deg. C/min.

Description

Adsorbent containing polyvinylidene fluoride-based activated carbon, manufacturing method thereof, and adsorption method of methane or carbon dioxide by the same SAME}

The present invention relates to a carbon dioxide adsorbent comprising polyvinylidene fluoride-based activated carbon, a method for preparing the same, and a method for adsorbing carbon dioxide by the same.

Carbon dioxide, one of the representative greenhouse gases, is rapidly increasing as its purification capacity is weakened due to deforestation, etc., which is accelerating in recent years, and the use of fossil fuels increases due to industrial development. In response to this situation, studies for removing carbon dioxide are being actively conducted.

Methods for removing carbon dioxide are largely absorption, membrane separation and adsorption. Absorption has the advantage that it can be separated from the solution by lowering the pressure without additional thermal energy, but there is a problem that high pressure is required during supply and there is a risk of corrosion in the regeneration step. There is this. Membrane separation is easy to operate continuously and consumes less energy, but has disadvantages in that it requires a compression process and high facility and operating costs. Adsorption has the advantage of low energy consumption in the collection process, reuse without additional polluting by-products, and economical due to the low cost of the adsorbent, but it has a disadvantage in that selective separation is difficult.

Adsorption of carbon dioxide is a commercially available adsorbent, such as zeolite, carbon nanofiber (CNF), activated carbon, and the like.

Zeolite is a crystalline material with a uniformly sized micropore structure, and shows a difference in _{CO 2 adsorption capacity depending on the micropore and crystal structure. Although it shows high CO 2} adsorption capacity at low pressure compared to activated carbon, it has a fatal disadvantage in that it shows a rapid decrease in adsorption capacity in a moisture atmosphere due to its hydrophilic nature.

Unlike activated carbon, carbon nanofibers have the advantage that they can be molded because polymer-based raw materials are produced through electrospinning. Since the diameter and size of the fiber varies depending on various variables such as the voltage applied when spinning the nanofiber, the flow rate of the polymer mixture, humidity, and temperature, if it is carbonized, it can be manufactured into a desired shape, but the manufacturing process is complicated. There are disadvantages.

Activated carbon has a high ratio of mesopores and micropores, so it is easily used as an adsorbent in various fields. Raw materials for activated carbon include polyacrylonitirle (PAN), polyimide (PI), polyvinyl alcohol (PVA), phenolic resin, polymethylmethacrylate (PMMA), A polymer such as polyvinylidene fluoride (PVDF) is used. _{CO 2} adsorption studies on activated carbon are being actively conducted as shown in Table 1 below, but the CO ₂ adsorption performance has not been improved enough to be commercially applied.

As the specific surface area of the activated carbon adsorbent increases, the pore volume also increases proportionally, and when such activated carbon surface properties are implemented, the CO ₂ adsorption performance may be improved. Typically, the pore structure of a porous adsorbent such as activated carbon is formed into macro pores (50 nm~), meso pores (2-50 nm), micro pores (~ 2 nm), etc., CO ₂ has a kinetic diameter Considering that it is about 0.34 nm, it is known that the higher the ratio of micropores (1 nm or less, specifically 0.5 to 0.9 nm) structure among the micropores of the adsorbent, the higher the CO _{2 adsorption performance.} That is, since the micropore structure is _{closely related to the CO 2} adsorption performance, the carbonization of the raw material promotes the formation of micropores (pore generation) while preventing the increase in the size of the micropores (pore enlargement), thereby adsorbing _{CO 2 performance} can be improved

On the other hand, PVdF-based polymer as a raw material for activated carbon is known to be activated during carbonization in an inert atmosphere at high temperature to produce activated carbon having a porous structure with a high micropore ratio. As the (fluorine) atoms are removed, micropores are formed based on the removed F atoms, and at the same time, activated carbon having a porous structure is obtained through a series of processes in which the size of the pores is increased (pore enlargement). At this time, the carbonization temperature is S.-M. Hong et al. / Carbon 99 (2016) 354e360, Porous carbon based on polyvinylidene fluoride: Enhancement of CO ₂ adsorption by physical activation (hereinafter, “non-patent document 1”) may be 450 ~ 1,000 ° C. In particular, in FIG. 1 of the present specification Graph of PVdF weight change according to the described carbonization temperature Referring to 1., it can be seen that the weight of PVdF is reduced and a porous structure is formed due to the activation of activated carbon at 450°C. On the other hand, when carbonization is carried out at a temperature exceeding 800 °C, the weight change of PVdF occurs rapidly, and carbon loss occurs beyond the porous structure due to the removal of fluorine (F). can be known

carbonization temperature
(℃) specific surface area
(m ² /g) total pore volume
(cm ³ /g) micropore volume
(cm ³ /g) Micropore volume (cm ³ /g)
(pore size: ~0.7 nm) 700 1023 0.414 0.403 0.247 750 1179 0.500 0.461 0.258 800 1479 0.622 0.585 0.261 850 1735 0.820 0.659 0.232 900 2307 1.158 0.880 0.200 950 2750 1.465 1.042 0.139

Referring to Table 2, the specific surface area and total pore volume of the obtained activated carbon have a tendency to increase in proportion to the temperature range (700 to 950° C.) during carbonization, but specifically, as the carbonization temperature increases to 700 to 800° C., the fine pores as the formation of a carbide during the temperature increase, while being maximized to 800 ~ 950 ℃ micropores are bar to the formation of one or more reduced about to 1nm micropores increased, PVdF carbonization in order to produce the activated carbon is CO ₂ adsorption performance of the optimized It can be understood that the temperature is preferably in the range of 800°C, preferably in the range of 750-850°C. That is, according to this prior art (Non-Patent Document 1), when the _{carbonization process is performed in a temperature range of 750 to 850° C. in an inert CO 2} atmosphere, the ratio of micropores among all pores of the prepared activated carbon can be increased, and CO ₂ It can be appreciated that adsorption performance can be improved. However, since the activated carbon adsorbent provided in the prior art (Non-Patent Document 1) still _{has insufficient CO 2} adsorption performance, there is room for improvement of the carbonization process of PVdF and the pore structure of activated carbon.

In the present invention, i) the molecular surface behavior of activated carbon is changed according to the thickness of the molten PVdF-based polymer sample, and ii) micropores are formed by varying the lowering rate when cooling to room temperature after the carbonization reaction performed at 800°C is completed. It was analyzed that it was formed densely with this high volume.

Accordingly, it is possible to provide an activated carbon adsorbent having _{significantly improved CO 2} adsorption performance and a densely formed micropore structure compared to the prior art.

One embodiment comprises the steps of: a) filling a boat with a PVdF-based polymer and inputting it into a kiln; b) heating the filled boat in a CO ₂ flow atmosphere to form a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted; c) maintaining the formed PVdF-based polymer film at a reaction temperature of 600 to 900° C. for 1 to 3 hours to activate (activation); And d) recovering the activated carbon by lowering the temperature at a rate of more than 1°C and less than 5°C/min; provides a method for producing an adsorbent comprising activated carbon based on polyvinylidene fluoride.

The PVdF-based polymer may contain 78 mol% or more of a vinylidene fluoride monomer based on the total number of moles of the monomer.

The PVdF-based polymer is polyvinylidene fluoride (poly(vinylidene fluoride)), poly(vinylidene fluoride-co-hexafluoropropylene) (poly(vinylidene fluoride-co-hexafluoropropylene)), poly(vinylidene fluoride) -co-tetrafluoroethylene) (poly(vinylidene fluoride-co-tetrafluoroethylene)), poly(vinylidenefluoride-co-trifluoroethylene) (poly(vinylidenefluoride-co-trifluoroethylene)) and perfluoropolymers ( It may be one or two or more selected from the group consisting of perfluoropolymers).

In step b), the temperature may be raised from room temperature to 600 to 900° C. at a rate of 1 to 10° C./min.

Another embodiment is the adsorbent prepared by the above method, with a specific surface area of 1,250 to 2,000 m ² /g, a total pore volume of 0.6 to 0.9 cm ³ /g, a micropore volume of 0.6 to 0.8 cm ³ /g, and a micropore volume of 0.30 to An adsorbent comprising activated carbon based on polyvinylidene fluoride of 0.35 cm ^{3 /g is provided.}

Another embodiment provides an adsorbent comprising polyvinylidene fluoride-based activated carbon, which is an adsorbent prepared by the above method, characterized in that it has micropores satisfying the following relation (1).

[Relational Expression 1]

(V ₁ -V ₂ )/V ₂ ≥ 0.1

(In Relation 1, V ₁ ^{is the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted (cm 3 /g), and V ₂ is the PVdF ^{It refers to the micropore volume (cm 3} /g) of an adsorbent containing activated carbon obtained by forming a film having a thickness of 0.12 cm or more in which the polymer is melted.)

Another embodiment provides an adsorbent comprising polyvinylidene fluoride-based activated carbon, which is an adsorbent prepared by the above method, characterized in that it has carbon dioxide adsorption performance satisfying Equation 2 below.

[Relational Expression 2]

(A ₁ -A ₂ )/A ₂ ≥ 0.2

(In the above relation 1, A ₁ is the oxygen dioxide adsorption performance (mmol/g, 25 ℃, atmospheric pressure) of the adsorbent containing activated carbon obtained by forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted, A ₂ means the oxygen dioxide adsorption performance (mmol/g, 25 ℃, atmospheric pressure) of an adsorbent containing activated carbon obtained by forming a film having a thickness of 0.12 cm or more in which the PVdF-based polymer is melted.)

Another embodiment provides an adsorbent comprising polyvinylidene fluoride-based activated carbon, which is an adsorbent prepared by the above method, characterized in that it has micropores satisfying Equation 3 below.

[Relational Expression 3]

(V ₁ -V ₂ )/V ₂ ≥ 0.1

(In Relational Equation 3, V ₁ ^{is the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by setting the heating rate of the kiln to more than 1° C. and less than 5° C./min _{, and V 2} is the ^{It means the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by setting the heating rate to 5° C./min or more.)

Another embodiment provides an adsorbent comprising polyvinylidene fluoride-based activated carbon, which is an adsorbent prepared by the above method, characterized in that it has carbon dioxide adsorption performance satisfying Equation 4 below.

[Relational Expression 4]

(A ₁ -A ₂ )/A ₂ ≥ 0.2

(In relation 4, A ₁ is the oxygen dioxide adsorption performance (mmol/g, 25° C., atmospheric pressure) of the adsorbent containing activated carbon obtained by setting the heating rate of the kiln to more than 1° C. and less than 5° C./min, and A ₂ means the oxygen dioxide adsorption performance (mmol/g, 25°C, atmospheric pressure) of an adsorbent containing activated carbon obtained by setting the heating rate of the kiln to 5°C/min or more.)

The adsorbent may be used for adsorbing carbon dioxide and/or methane.

The adsorbent may have a content of element F by X-ray photoelectron spectroscopy (XPS) of 10 atomic% or less.

Another embodiment provides a methane adsorption method, characterized in that the adsorption reaction is performed using the adsorbent in an atmospheric pressure (760 mmHg) gas atmosphere containing a partial pressure _{of CH 4} of 100% by volume or less _{and N 2 as the balance.} .

Another embodiment provides a carbon dioxide adsorption method, characterized in that the adsorption reaction is performed using the adsorbent in an atmospheric pressure (760 mmHg) gas atmosphere containing a partial pressure _{of CO 2} of 100% by volume or less _{and N 2 as the balance.} .

The adsorption reaction may be carried out in a temperature range of 0 to 30 °C.

In the present invention, by adjusting the thickness of the film formed in the molten state of the PVdF-based polymer as a raw material of activated carbon to 0.03 to 0.10 cm, the micropore structure of activated carbon can be densely formed with a high volume.

In addition, by controlling the rate of cooling to room temperature after activation of the PVdF-based polymer to be more than 1°C and less than 5°C/min, the micropore structure of activated carbon can be improved to a high level.

1 is a graph showing the weight change of PVdF according to the carbonization temperature.
_{Figure 2a is a graph showing the CO 2} adsorption performance of the activated carbon prepared in Example 1-1, Comparative Example 1-1 and Comparative Example 1-2.
_{Figure 2b is a graph showing the CH 4} adsorption performance of the activated carbon prepared in Example 1-1, Comparative Example 1-1 and Comparative Example 1-2.
_{Figure 3a is a graph showing the CO 2} adsorption performance of the activated carbon prepared in Comparative Examples 2-1, 2-2 and Example 1-1.
_{Figure 3b is a graph showing the CH 4} adsorption performance of the activated carbon prepared in Comparative Examples 2-1, 2-2 and Example 1-1.
4 is a graph showing the correlation between the micropore volume of activated carbon and the CO ₂ , CH _{4 adsorption capacity.}

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Detailed contents for carrying out the present invention will be described in detail with reference to the accompanying drawings below. Regardless of the drawings, like reference numbers refer to like elements, and "and/or" includes each and every combination of one or more of the recited items.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings commonly understood by those of ordinary skill in the art to which the present invention belongs. When a part "includes" a certain component throughout the specification, this means that other components may be further included, rather than excluding other components, unless otherwise stated. The singular also includes the plural, unless the phrase specifically states otherwise.

In the present specification, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, this includes not only the case where the other part is “directly on” but also the case where there is another part in between. do.

Hereinafter, a method for preparing an adsorbent including polyvinylidene fluoride-based activated carbon according to an embodiment of the present invention will be described. The method for producing the activated carbon comprises the steps of: a) filling a boat with a PVdF-based polymer and putting it into a kiln; b) heating the filled boat in a CO ₂ flow atmosphere to form a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted; c) maintaining the formed PVdF-based polymer film at a reaction temperature of 600 to 900° C. for 1 to 3 hours to activate (activation); and d) recovering the activated carbon by lowering the temperature at a rate of greater than 1°C and less than 5°C/min.

In step a), the boat is not particularly limited, but a ceramic boat may be used, and a PVdF-based polymer in the boat is melted in the kiln of step b) and a film having a thickness of 0.03 to 0.10 nm It can be charged to an amount that forms

The PVdF-based polymer preferably contains 78 mol% or more, preferably 78-99.5 mol%, more preferably 78-82 mol% of vinylidene fluoride monomer with respect to the total number of moles of the monomer. In step b), the fluorine (F) group contained in the PVdF-based polymer is removed to form micropores. Since it can be formed in a thin film, the total volume of micropores increases, which is preferable for improving _{the CO 2 adsorption performance.} On the other hand, when the vinylidene fluoride monomer is included in less than 78 mol% in the PVdF-based polymer, it is difficult to promote the formation of micropores in activated carbon. Since the reaction of merging to increase the micropore size (pore enlargement) is promoted, the formation of micropores (pore generation) may be reduced and the size of the pores may be increased.

The PVdF-based polymer is polyvinylidene fluoride (poly(vinylidene fluoride)), poly(vinylidene fluoride-co-hexafluoropropylene) (poly(vinylidene fluoride-co-hexafluoropropylene)), poly(vinylidene fluoride) -co-tetrafluoroethylene) (poly(vinylidene fluoride-co-tetrafluoroethylene)), poly(vinylidenefluoride-co-trifluoroethylene) (poly(vinylidenefluoride-co-trifluoroethylene)) and perfluoropolymers ( It may be one or two or more selected from the group consisting of perfluoropolymers, and may be a copolymer (co-polymer) in which different monomers included in the polymer are continuously combined, or a mixture thereof.

When the weight average molecular weight of the PVdF-based polymer is 180,000 to 550,000, preferably 180,000 to 500,000, 200,000 to 400,000, more preferably 200,000 to 300,000, the micropores in the activating step in the activating step of the present invention are high distribution and It is good to form in volume, and then, when the activated carbon is recovered by lowering the temperature at a rate of more than 1°C and less than 5°C/min, it is preferable that the formed micropores do not easily collapse.

In step b), the polymer is carbonized to form a carbon adsorbent as follows. 1) As the temperature gradually rises above the melting point of the polymer, the solid polymer sample has fluidity and is melted to change into a form having a certain thickness (0.03 to 0.1 cm) according to the present invention, 2) gradually As the temperature rises, the fluorine (F) group contained in the PVdF-based polymer is removed to form micropores. At this time, in order for the fluorine that has fallen out from the backbone of the PVdF polymer to escape smoothly, it must be moved through diffusion inside the polymer in the molten state. It was possible to analyze the phenomenon that diffusion was not easy compared to the thickness. Accordingly, there is a problem in that the pore properties of the carbon-based adsorbents are different from each other depending on the location where the molten PVdF-based polymer is distributed in the thickness direction in the kiln when the polymer is carbonized. In addition, as described later, if the temperature is rapidly lowered after carbonization, the formed pore structure may be collapsed and micropores may not be well formed.

More specifically, if the thickness of the film formed in the molten state of the PVdF polymer is less than 0.03 cm, it is difficult to achieve economical material synthesis because a very large-scale furnace is required to produce a large amount of carbonized polymer-based carbon adsorbent, On the other hand, if it exceeds 0.10 cm, it is difficult to control the size of specific micropores in the carbon dioxide atmosphere provided by the present invention. Specifically, PVdF polymer is selected and the CO ₂ flow of gas when, while changes in the liquid phase at a temperature of the melting point or more and to form a film having a uniform thickness in a ceramic boat temperature is gradually go up to fluorine gas with a fluorine functional group contained in PVdF, etc. get out together At this time, the generated fluorine gas, etc., is formed inside the liquid film and is transferred by diffusion in the opposite direction to gravity by the transfer phenomenon to escape from the liquid/gas phase to the gas phase. As the carbonization weight increases, the liquid thickness increases. becomes thicker and the diffusion distance increases. Accordingly, as the carbonization process is further delayed, it is difficult to sufficiently form micropores.

Meanwhile, since the standard of the sample content may vary depending on the size of the carbonization kiln, it is preferable to set the thickness of the film formed in the molten state while the polymer is carbonized as the sample content standard.

On the other hand, the state in which the PVdF-based polymer is melted to form a film means the state in which the PVdF-based polymer is completely melted at a temperature above the melting point. It may mean a melted molten state.

In the step c), the PVdF-based polymer film formed in a CO ₂ atmosphere in a kiln at a reaction temperature of 600 ~ 900 ℃, preferably 700 ~ 900 ℃, more preferably 750 ~ 850 ℃ 1-3 hours, preferably 1.5 ~ 3 Time, 1.5 to 2.5 hours, more preferably, 2 to 2.5 hours to activate (activation, carbonization).

Then, after carbonization of the PVdF-based polymer film is completed at the reaction temperature, when the final activated carbon is prepared by lowering the temperature at a rate of more than 1 ° C and less than 5 ° C / min, a microstructure of activated carbon remarkably improved compared to the prior art can be formed. . Preferably, the temperature may be lowered at a rate of 1.5 to 4.5° C./min, preferably 2 to 4° C./min, more preferably 2.5 to 3.5° C./min, or 3° C./min. When the cooling rate is 1°C/min or less, it is a condition that is difficult to apply realistically, and since the exposure time to relatively high temperature is increased, carbon loss occurs and the structure collapses, so the specific surface area and total pore volume may deteriorate. Not desirable. If it is 5° C./min or more, it is disadvantageous because the micropore structure formed during carbonization during the supercooling process may collapse or be damaged. In addition, if the cooling rate is not set after the completion of the carbonization reaction (convection cooling), the cooling rate is very high immediately after the reaction is completed, and the decrease in the cooling rate thereafter is small. In this case, it is not preferable because damage to the micropore structure due to supercooling occurs immediately after completion of the reaction. In particular, according to the manufacturing method of the present invention, since the micropores are formed in a very high volume and ratio as described above by preparing the PVdF-based polymer in an amount that forms a specific film thickness based on the molten state during carbonization, It is very important to prevent not only the collapse and damage of the formed micropore structure, but also the increase in the size of the formed micropores and the formation of micropores and macropores due to bonding between micropores. Therefore, by controlling the heating rate within the above numerical range, it is possible to manufacture an activated carbon adsorbent having a _{significantly improved CO 2} and/or CH _{4 adsorption performance and a dense micropore structure compared to the prior art.}

On the other hand, in step c), before carbonizing the PVdF-based polymer film at the reaction temperature, the molten PVdF-based polymer film is heated to 700-900°C at 1-10°C/min, preferably at 1-8°C/min, better may be to increase the temperature to the reaction temperature (activation temperature) at a rate of 1 ~ 5 ℃ / min or 2 ~ 4 ℃ / min. When the temperature is raised to the reaction temperature at a rate within the range, it is possible to form an improved microstructure of activated carbon compared to the prior art. When the room temperature rate is less than 1 ℃ / min, the room temperature time is significantly increased, and the amount of CO ₂ gas required is a condition that makes it difficult to economically synthesize the material. On the other hand, if it exceeds 10 ℃ / min, the temperature is rapidly increased Therefore, it is not preferable because the PVdF-based polymer cannot completely melt near the melting point and overflow to the outside of the ceramic boat filled with the sample due to the boiling effect.

Another embodiment of the present invention provides an adsorbent comprising the polyvinylidene fluoride-based activated carbon according to the embodiment.

The adsorbent has a specific surface area of 1,250 to 2,000 m ² /g, a total pore volume of 0.6 to 0.9 cm ³ /g, a micropore volume of 0.6 to 0.8 cm ³ /g, and a micropore volume of 0.30 to 0.35 cm ³ /g. .

Specifically, the adsorbent has a specific surface area of 1,300 to 2,000 m ² /g, 1,350 to 2,000 m ² /g, 1,400 to 2,000 m ² /g, 1,450 to 2,000 m ² /g, 1,500 to 2,000 m ² /g, or 1,550 to 2,000 m ² /g.

Specifically, the adsorbent has a total pore volume of 0.61 to 0.9 cm ³ /g, 0.63 to 0.9 cm ³ /g, 0.65 to 0.9 cm ³ /g or 0.70 to 0.9 cm ³ /g, and a micropore volume of 0.61 to 0.8 cm ³ /g , 0.64 to 0.8 cm ³ /g, 0.65 to 0.8 cm ³ /g, 0.7 to 0.8 cm ³ /g or 0.75 to 0.8 cm ³ /g, micropore volume 0.30 to 0.35 cm ³ /g, 0.31 to 0.35 cm ³ / g or 0.32 to 0.35 cm ³ /g.

One embodiment of the present invention, the adsorbent prepared by the above method, characterized in that it has micropores satisfying the following relational expression (1).

[Relational Expression 1]

(V ₁ -V ₂ )/V ₂ ≥ 0.1

(In Relation 1, V ₁ ^{is the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted (cm 3 /g), and V ₂ is the PVdF ^{It refers to the micropore volume (cm 3} /g) of an adsorbent containing activated carbon obtained by forming a film having a thickness of 0.12 cm or more in which the polymer is melted.)

Relation 1 above is preferably (V ₁ -V ₂ )/V ₂ ≥ 0.15, more preferably (V ₁ -V ₂ )/V ₂ ≥ 0.2, most preferably (V ₁ -V ₂ )/V ₂ ≥ 0.3 can be displayed as

One embodiment of the present invention, the adsorbent prepared by the above method, characterized in that it has micropores satisfying the following relational expression (2).

[Relational Expression 2]

(A ₁ -A ₂ )/A ₂ ≥ 0.2

(In the above relation 2, A ₁ is the oxygen dioxide adsorption performance (mmol/g, 25 ℃, atmospheric pressure) of the adsorbent containing activated carbon obtained by forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted, A ₂ means the oxygen dioxide adsorption performance (mmol/g, 25 ℃, atmospheric pressure) of an adsorbent containing activated carbon obtained by forming a film having a thickness of 0.12 cm or more in which the PVdF-based polymer is melted.)

Relation 2 may be preferably expressed as (A ₁ -A ₂ )/A ₂ ≥ 0.25, and more preferably (A ₁ -A ₂ )/A ₂ ≥ 0.3.

One embodiment of the present invention is an adsorbent prepared by the above method, characterized in that it has micropores satisfying the following relation (3).

[Relational Expression 3]

(V ₁ -V ₂ )/V ₂ ≥ 0.1

(In Relational Equation 3, V ₁ ^{is the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by setting the heating rate of the kiln to more than 1° C. and less than 5° C./min _{, and V 2} is the ^{It means the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by setting the heating rate to 5° C./min or more.)

Relation 3 above is preferably (V ₁ -V ₂ )/V ₂ ≥ 0.15, more preferably (V ₁ -V ₂ )/V ₂ ≥ 0.2, most preferably (V ₁ -V ₂ )/V ₂ ≥ 0.3 can be displayed as

One embodiment of the present invention, the adsorbent prepared by the above method, characterized in that it has micropores satisfying the following relational expression (4).

[Relational Expression 4]

(A ₁ -A ₂ )/A ₂ ≥ 0.2

(In relation 4, A ₁ is the oxygen dioxide adsorption performance (mmol/g, 25° C., atmospheric pressure) of the adsorbent containing activated carbon obtained by setting the heating rate of the kiln to more than 1° C. and less than 5° C./min, and A ₂ means the oxygen dioxide adsorption performance (mmol/g, 25°C, atmospheric pressure) of an adsorbent containing activated carbon obtained by setting the heating rate of the kiln to 5°C/min or more.)

Relation 4 may be preferably expressed as (A ₁ -A ₂ )/A ₂ ≥ 0.25, and more preferably (A ₁ -A ₂ )/A ₂ ≥ 0.3.

In the activated carbon, the content of F element remaining in the activated carbon after the carbonization process of the PVdF-based polymer of the raw material is completed may be 10 atomic% or less, preferably 0.5-10 atomic%, 0.5-5 atomic%, 0.5-3 atomic %, more preferably 0.5 to 1.5 atomic %. The content of the element F remaining in the activated carbon can be viewed as an indicator for confirming the degree of polymer carbonization progress, and as the content of the remaining element F approaches 0.5 atomic%, the molecular surface behavior of the activated carbon can be improved, and the present invention According to the method for producing activated carbon, the specific surface area and total pore volume of the activated carbon are rapidly increased, and the volume of micropores is significantly increased compared to the prior art, so that the CO ₂ adsorption performance can be very good. However, when the content of the element F remaining in the activated carbon is too small, it may not be good for maintaining the micropores formed in the activated carbon as carbon loss occurs.

Meanwhile, the content of element F remaining in the activated carbon may be measured by X-ray photoelectron spectroscopy (XPS), but the present invention is not limited thereto.

The adsorbent may be used for adsorbing carbon dioxide and/or methane.

One embodiment of the present invention provides a carbon dioxide adsorption method using the adsorbent. The carbon dioxide adsorption method is characterized in that carbon dioxide is adsorbed using the adsorbent in a gas atmosphere reactor containing 100 vol% or less of CO ₂ and an inert gas, for example, N _{2 as the balance.}

One embodiment of the present invention provides a methane adsorption method using the adsorbent. The methane adsorption method is characterized in that methane is adsorbed using the adsorbent in a gas atmosphere reactor containing 100% by volume or less of methane and an inert gas, for example, N _{2 as the balance.}

The adsorption reaction of methane or carbon dioxide may be carried out in a temperature range of 0 to 30 °C, for example, 15 to 30 °C, 20 to 30 °C, 25 to 30 °C or 25 °C.

Hereinafter, preferred examples and comparative examples of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited thereto.

Example

[Examples 1-1 to 1-3, and Comparative Examples 1-1 to 1-3]

* Changes in the surface pore structure of activated carbon according to the film thickness of the molten PVdF-based polymer sample, and CO ₂ and CH ₄ Adsorption performance evaluation

(1) PVdF-based polymer (product name: Dyneon ^TM Fluoroplastic 6108/0001, manufacturer: 3M, Mw: 244,000) was filled in a ceramic boat and put into the kiln, and then the temperature was raised from room temperature to 800°C in carbon dioxide atmosphere at 3°C/min. After raising the furnace temperature at a rate, it was maintained for 2 hours and then cooled to a range of 100 to 120 °C at a lowering rate of 3 °C/min to obtain activated carbon.

The film thickness of the molten PVdF sample used in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3, the specific surface area of the prepared activated carbon, total pore volume, micropore volume, and micropore volume Table 3 below.

Film thickness
(cm) low speed
(°C/min) specific surface area
(m ² /g) total pore volume
(cm ³ /g) micropore volume
(cm ³ /g) micropore volume
(size: 0.5~0.9 nm)
(cm ³ /g) Example 1-1 0.06 3 1600 0.77 0.76 0.35 Example 1-2 0.072 3 1420 0.66 0.65 0.32 Examples 1-3 0.09 3 1304 0.61 0.61 0.30 Comparative Example 1-1 0.125 3 1209 0.56 0.55 0.26 Comparative Example 1-2 0.188 3 1193 0.55 0.55 0.26 Comparative Example 1-3 0.28 3 1154 0.51 0.38 0.25

Referring to Table 3, when the thickness of the film formed in the molten state of the PVdF-based polymer sample decreases in the range of 0.30 cm or less, as described above, the specific surface area and the total pore volume are in inverse proportion to 1,150 to 1,600. m ² /g and 0.51 to 0.77 cm ³ /g increased, and it was confirmed that the formation and distribution of micropores and micropores were improved. In particular, the activated carbon prepared in Examples 1-1 to 1-3 has a specific surface area in the ^{range of 1,250 to 2,000 m 2} /g, a total pore volume in the range of 0.60 to 0.90 cm ³ /g, and a micropore volume in the range of 0.60 to 0.80 cm ³ /g. , and a micropore volume of 0.30 to 0.35 ^{cm 3} /g is formed to correspond to the present invention, and it can be seen that the adsorption capacity of _{CO 2} and CH _{4 can be further improved.} (2) Using the prepared activated carbon as an adsorbent _{, the CO 2} and CH _{4 adsorption performance was evaluated under 25° C. temperature conditions and atmospheric pressure (CO 2} or CH ₄ change in the range of 0-100 vol%), and the results are shown in FIG. 2a and 2b.

Referring to FIGS. 2a and 2b, the adsorbent of Example 1-1 has very good adsorption performance of adsorbing about 4.8 mmol/g carbon dioxide or 2.2 mmol/g methane at _{25° C. and atmospheric pressure (CO 2} or CH _{4 100% by volume)} However, in the case of the comparative example, the performance was significantly deteriorated by adsorbing 3.4 mmol/g carbon dioxide or 1.7 to 1.9 mmol/g methane. These results are analyzed because the activated carbon of the present invention has a remarkably improved micropore (0.6-0.9 nm size) structure.

[Examples 2-1 and 2-2, Comparative Examples 2-1 and 2-2]

* Analysis of the surface pore structure of activated carbon according to the change in the heating rate of the kiln, and CO ₂ Adsorption capacity evaluation

(1) Activated carbon was obtained in the same manner as in Example 1-1, except that the cooling rate during cooling was set as shown in Table 4 below.

Table 4 shows the specific surface area, total pore volume, micropore volume, and micropore volume of the prepared activated carbon.

Film thickness
(cm) low speed
(°C/min) specific surface area
(m ² /g) total pore volume
(cm ³ /g) micropore volume
(cm ³ /g) micropore volume
(size: 0.5~0.9 nm)
(cm ³ /g) Comparative Example 2-1 0.06 One 1111 0.53 0.38 0.26 Example 2-1 0.06 2 1428 0.70 0.69 0.31 Example 1-1 0.06 3 1600 0.77 0.76 0.35 Example 2-2 0.06 4 1209 0.69 0.67 0.30 Comparative Example 2-2 0.06 5 1152 0.51 0.38 0.26 Comparative Example 2-3 0.06 5~10 (Convection cooling) 1085 0.45 0.35 0.24

Referring to Table 4, as described above, after carbonization of PVdF is completed, the activated carbon produced at a heating rate of more than 1°C and less than 5°C/min of the kiln has a specific surface area of 1,250 to 2,000 m ² /g, a total pore volume 0.60 ~ 0.90cm is formed of a ³ / g range, a micro pore volume of 0.60 ~ 0.80cm ³ / g range, and the fine pore volume of 0.30 ~ 0.35cm ³ / g range it can be seen that this corresponds to the present invention. In particular, it can be seen that when the heating rate is adjusted to 3°C/min, which is the most desirable range, the formation and distribution of micropores are remarkably improved, thereby increasing the micropore volume and micropore volume, thereby adsorbing _{CO 2} and CH ₄ (2) Using the prepared activated carbon as an adsorbent, evaluate the _{CO 2} and CH _{4 adsorption performance under 25°C temperature conditions and atmospheric pressure (CO 2} or CH ₄ changes in the range of 0-100 vol%) and the results are shown in FIGS. 3a and 3b.

Referring to FIGS. 3a and 3b, the adsorbent of Example 1-1 has very good adsorption performance of adsorbing about 4.8 mmol/g carbon dioxide or 2.2 mmol/g methane at _{25° C. and atmospheric pressure (CO 2} or CH _{4 100% by volume)} However, in the case of Comparative Example, the performance was significantly deteriorated by adsorbing 3.6 to 3.8 mmol/g carbon dioxide or 1.7 to 1.9 mmol/g methane. In the case of an embodiment of the present invention, it is meaningful in that it is a very high number compared with the previously reported results. In addition, this result is analyzed to be because, in the case of the activated carbon of the present invention, the micropore structure formed during activation (carbonization) was well maintained without collapse when the activated PVdF-based polymer was cooled to room temperature.

* Analysis of the surface pore structure of activated carbon according to the change in the heating rate of the kiln, and CO ₂ Adsorption capacity evaluation

_{On the other hand, the increase in the CO 2} , CH ₄ adsorption capacity according to the increase in the micropore volume of the activated carbon was evaluated and shown in FIG. 4 .

Referring to FIG. 4 , it can be seen that the relationship between micropores and adsorption capacity has a linear relationship as expected. In particular, it can be seen that even when the volume of micropores (V _N ) is slightly increased, the carbon dioxide and methane adsorption capacity (CO ₂ , CH ₄ adsorption uptake) has a very high slope and rapidly increases.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains will appreciate the technical spirit of the present invention. However, it will be understood that the invention may be embodied in other specific forms without changing essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (14)

a) filling a boat with a PVdF-based polymer and inputting it into a kiln;
b) heating the filled boat in a CO ₂ flow atmosphere to form a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted;
c) maintaining the formed PVdF-based polymer film at a reaction temperature of 600 to 900° C. for 1 to 3 hours to activate (activation); and
d) recovering the activated carbon by lowering the temperature at a rate of more than 1°C and less than 5°C/min; In claim 1,
The PVdF-based polymer is a method of manufacturing an adsorbent comprising a polyvinylidene fluoride-based activated carbon, characterized in that it contains 78 mol% or more of a vinylidene fluoride monomer with respect to the total number of moles of the monomer. In claim 1,
The PVdF-based polymer is polyvinylidene fluoride (poly(vinylidene fluoride)), poly(vinylidene fluoride-co-hexafluoropropylene) (poly(vinylidene fluoride-co-hexafluoropropylene)), poly(vinylidene fluoride) -co-tetrafluoroethylene) (poly(vinylidene fluoride-co-tetrafluoroethylene)), poly(vinylidenefluoride-co-trifluoroethylene) (poly(vinylidenefluoride-co-trifluoroethylene)) and perfluoropolymers ( A method for producing an adsorbent comprising one or two or more polyvinylidene fluoride-based activated carbons selected from the group consisting of perfluoropolymers). In claim 1,
The step b) is a method for producing an adsorbent comprising a polyvinylidene fluoride-based activated carbon to which the temperature is raised from room temperature to 600 ~ 900 ℃ at a rate of 1 ~ 10 ℃ / min. An adsorbent prepared by the method of claim 1, with a specific surface area of 1,250 to 2,000 m ² /g, a total pore volume of 0.6 to 0.9 cm ³ /g, a micropore volume of 0.6 to 0.8 cm ³ /g, and a micropore volume of 0.30 to 0.35 cm ³ Adsorbent comprising activated carbon based on polyvinylidene fluoride in /g. As an adsorbent prepared by the method of claim 1, an adsorbent comprising polyvinylidene fluoride-based activated carbon, characterized in that it has micropores satisfying the following relation (1).
[Relational Expression 1]
(V ₁ -V ₂ )/V ₂ ≥ 0.1
(In Relation 1, V ₁ ^{is the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted (cm 3 /g), and V ₂ is the PVdF ^{It refers to the micropore volume (cm 3} /g) of an adsorbent containing activated carbon obtained by forming a film having a thickness of 0.12 cm or more in which the polymer is melted.) [Claim 6] The adsorbent comprising activated carbon based on polyvinylidene fluoride according to claim 5, characterized in that it has carbon dioxide adsorption performance satisfying the following relation (2).
[Relational Expression 2]
(A ₁ -A ₂ )/A ₂ ≥ 0.15
(In the above relation 1, A ₁ is the oxygen dioxide adsorption performance (mmol/g, 25 ℃, atmospheric pressure) of the adsorbent containing activated carbon obtained by forming a film having a thickness of 0.03 to 0.10 cm in which the PVdF-based polymer is melted, A ₂ means the oxygen dioxide adsorption performance (mmol/g, 25 ℃, atmospheric pressure) of an adsorbent containing activated carbon obtained by forming a film having a thickness of 0.12 cm or more in which the PVdF-based polymer is melted.) [Claim 6] The adsorbent comprising activated carbon based on polyvinylidene fluoride according to claim 5, characterized in that it has micropores satisfying the following relation (3).
[Relational Expression 3]
(V ₁ -V ₂ )/V ₂ ≥ 0.1
(In Relational Equation 3, V ₁ ^{is the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by setting the heating rate of the kiln to more than 1° C. and less than 5° C./min _{, and V 2} is the ^{It means the micropore volume (cm 3} /g) of the adsorbent containing activated carbon obtained by setting the heating rate to 5° C./min or more.) [Claim 6] The adsorbent comprising activated carbon based on polyvinylidene fluoride according to claim 5, characterized in that it has a carbon dioxide adsorption performance satisfying the following relation (4).
[Relational Expression 4]
(A ₁ -A ₂ )/A ₂ ≥ 0.15
(In relation 4, A ₁ is the oxygen dioxide adsorption performance (mmol/g, 25° C., atmospheric pressure) of the adsorbent containing activated carbon obtained by setting the heating rate of the kiln to more than 1° C. and less than 5° C./min, and A ₂ means the oxygen dioxide adsorption performance (mmol/g, 25°C, atmospheric pressure) of an adsorbent containing activated carbon obtained by setting the heating rate of the kiln to 5°C/min or more.) In claim 5,
The adsorbent is an adsorbent comprising a polyvinylidene fluoride-based activated carbon used for adsorbing carbon dioxide and/or methane. In claim 5,
The adsorbent comprises a polyvinylidene fluoride-based activated carbon having an element F content of 10 atomic% or less by X-ray photoelectron spectroscopy (XPS). An adsorption method for methane, characterized in that the adsorption reaction is performed using the adsorbent of claim 5 in an atmospheric pressure (760 mmHg) gas atmosphere containing 100% by volume or less of CH ₄ and the balance N _{2 .} A method of adsorption of carbon dioxide, characterized in that the adsorption reaction is performed using the adsorbent of claim 5 in a gas atmosphere at atmospheric pressure (760 mmHg) containing 100% by volume or less of CO ₂ and N _{2 as the balance.} 14. In claim 12 or 13,
The adsorption reaction is methane or carbon dioxide adsorption method, characterized in that carried out in a temperature range of 0 ~ 30 ℃.

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