KR102132779B1 - Adsorbent for carbon dioxide, method preparing the same and capure module for carbon dioxide - Google Patents

Abstract

A divalent first metal (M ¹ ) and a trivalent second metal (M ² ) and an element (A) having an electronegativity of about 2.0 to about 4.0, and a composite metal oxide having an amorphous structure Carbon dioxide adsorbents are provided. In addition, a method for manufacturing the carbon dioxide adsorbent and a carbon dioxide capture module including the carbon dioxide adsorbent are provided.

Description

A carbon dioxide adsorbent, a manufacturing method thereof, and a carbon dioxide capture module including the same {ADSORBENT FOR CARBON DIOXIDE, METHOD PREPARING THE SAME AND CAPURE MODULE FOR CARBON DIOXIDE}

The present invention relates to a carbon dioxide adsorbent, a manufacturing method thereof, and a carbon dioxide capture module including the same.

It is known that the release of carbon dioxide into the atmosphere has the most serious effect on global warming due to the increased use of fossil fuels. For removing carbon dioxide from flue gas generated from combustion of fossil fuels, syngas generated from coal gasification, and fuel gas generated from reforming natural gas Research is ongoing.

Wet chemical absorption, dry chemical absorption, adsorption, membrane separation and the like are known as methods for removing carbon dioxide from flue gas. In order to capture carbon dioxide from a large-scale flue gas, an adsorbent having excellent adsorption performance is urgently required.

The adsorbents developed to date include low temperature (0°C to room temperature), such as MOF (Metal Organic Framework)/ZIF (Zeolitic-Imidazolate Framework), zeolite, and carbon, and medium temperatures such as hydrotalcite (about 150 to about 150) 400°C) and high temperature (about 500°C or higher) adsorbents for metal oxides. In the case of these adsorbents, since the adsorption process must be performed by lowering or raising the temperature of the exhaust gas that is burned and discharged, there is a problem in that the process is complicated and costs are added. Therefore, it can be said that it is urgent to develop a high-performance adsorbent having excellent adsorption performance between about 150 to about 400°C, which is the temperature range of the actual exhaust gas.

One embodiment of the present invention is to provide a carbon dioxide adsorbent that is excellent in adsorption performance and excellent in thermal stability, capable of high temperature operation.

Another embodiment of the present invention is to provide a method for manufacturing the carbon dioxide adsorbent and a carbon dioxide capture module including the carbon dioxide adsorbent.

One embodiment of the present invention includes a divalent first metal (M ¹ ) and a trivalent second metal (M ² ) and an element (A) having an electronegativity of about 2.0 to about 4.0, and an amorphous structure. Eggplant provides a carbon dioxide adsorbent comprising a complex metal oxide.

The composite metal oxide may be represented by Formula 1 below.

[Formula 1]

[M ¹ _{1 - x} M ² _x A _y ]O _a

In Formula 1, M ¹ is a divalent first metal, M ² is a trivalent second metal, A is an element having an electronegativity of about 2.0 to about 4.0, x is 0.2 to 0.4, and y is 0.3 to 3 And a is the number M ¹ , M ² , and A need to balance the charge with oxygen.

The divalent first metal (M ¹ ) may be selected from alkaline earth metals, transition metals, and combinations thereof. Specifically, magnesium (Mg), calcium (Ca), strontium (Sr), nickel (Ni), and manganese ( Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), beryllium (Be), and combinations thereof. The trivalent second metal (M ² ) may be selected from Group 13 elements of the IUPAC periodic table, transition metals, and combinations thereof, specifically aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe) ), cobalt (Co), lanthanum (La), cerium (Ce), gallium (Ga), indium (In), vanadium (V), and combinations thereof.

The first metal (M ¹ ) and the second metal (M ² ) may be present such that M ¹ /M ² has a molar ratio of about 1.5/1 to about 4/1.

The element (A) having an electronegativity of about 2.0 to about 4.0 may be selected from phosphorus (P), boron (B), fluorine (F), sulfur (S), and chlorine (Cl) and combinations thereof. . The electronegativity of the element (A) may be specifically in the range of about 2.2 to 4.0.

The carbon dioxide adsorbent may further include at least one selected from alkali metal and alkali metal oxides present on the surface of the composite metal oxide.

In another embodiment, comprising a bivalent first metal (M ¹ ) and a trivalent second metal (M ² ) and a composite metal oxide having an electronegativity of 2.0 to 4.0 and having an amorphous structure (A) A method for producing a carbon dioxide adsorbent is provided, the method comprising: dissolving a salt of a divalent metal and a salt of a trivalent metal in water to obtain a mixed aqueous solution; Adjusting the pH of the mixed aqueous solution to basic to precipitate a complex metal hydroxide; Separating the composite metal hydroxide; Mixing the composite metal hydroxide with an aqueous solution of a salt containing an element having an electronegativity of about 2.0 to about 4.0 to obtain a mixture; Adjusting the pH of the mixture to 7 or less and stirring to form an ion-exchanged composite metal hydroxide; Separating the ion-exchanged composite metal hydroxide; And firing the ion-exchanged composite metal hydroxide to obtain a composite metal oxide, wherein the anion of the salt of the divalent metal and the salt of the trivalent metal does not include a carbonate anion.

The salt of the divalent metal is a first metal selected from alkaline earth metals, transition metals, and combinations thereof, specifically magnesium (Mg), calcium (Ca), strontium (Sr), nickel (Ni), and manganese (Mn). , Iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), beryllium (Be) and nitrates, acetates and hydrates (hydrates) containing the first metal selected from combinations thereof Can be selected.

The salt of the trivalent metal is a second metal selected from Group 13 elements of the IUPAC Periodic Table, transition metals and combinations thereof, specifically aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), Nitrates, acetates and their hydrates comprising a second metal selected from cobalt (Co), lanthanum (La), cerium (Ce), gallium (Ga), indium (In), vanadium (V) and combinations thereof Can be selected from.

The pH of the mixed aqueous solution can be adjusted from about 9 to about 12.

The method may further include aging the composite metal hydroxide by stirring at a temperature of 60° C. or less.

The method may further include drying the composite metal hydroxide under a temperature of 60° C. or less and a pressure below atmospheric pressure.

The ion-exchanged composite metal hydroxide may be represented by Formula 2 below.

[Formula 2]

[M ¹ _{1 -x} M ² _x (OH) ₂ ] ^x+ [((( A ¹ ) _y (A ² ) _z (A ³ ) _1-yz ) ^n- _x/n ] ^x -mH ₂ O

In Chemical Formula 2, M ¹ is a divalent first metal, M ² is a trivalent second metal, A ¹ is an anion of a salt of the divalent metal, A ² is an anion of a salt of the trivalent metal, A ³ Is an anion of a salt containing an element having an electronegativity of about 2.0 to about 4.0, and x, y and z are each in a range of about 0.2 to about 0.4, where y+z is less than 1 and n is ion exchanged. The anion (A ³ ) and the anion of the divalent metal salt and the anion of the trivalent metal salt (A ¹ and A ² ) are determined according to the valence, and m ranges from about 0 to about 8.

The divalent salt of the anion (A ¹⁾ and the salt anion of a trivalent metal of the metal (A ²⁾ is a nitric acid ion, each independently (NO ₃ ^-), acetate ion (CH ₃ COO ^-) and may be selected in a combination thereof have.

Salt anion is phosphate ions in which the electronegativity is containing from about 2.0 to about 4.0, the element (PO ₄ ^{3 -),} boric acid ion (BO _{³ 3} ^-), sulfate ion (SO ₄ ^{2 -),} hydrogen peroxide sulfate ions (S ^₂ O _{8 2} ^-), hydrochloric acid ion (Cl ^-), chlorate ion (ClO ₄ ^-), hydrofluoric acid ions (F ^- may be selected from a), and combinations thereof.

In addition, the cation of the salt containing the element having an electronegativity of about 2.0 to about 4.0 may be selected from K ⁺ , Ca ^{2 +} , NH ₄ ⁺ , Na ⁺ and combinations thereof.

Specifically, the salt containing the element having an electronegativity of about 2.0 to about 4.0 is KH ₂ PO ₄ , K ₂ HPO ₄ , CaHPO ₄ , (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ HPO ₄ , KH ₂ BO ₃ , K ₂ HBO ₃ , CaHBO ₃ , (NH ₄ )H ₂ BO ₃ , (NH ₄ ) ₂ HBO ₃ , NaH ₂ BO ₃ , Na ₂ HBO ₃ , K ₂ SO ₄ , KHSO ₄ , CaSO ₄ , (NH ₄ ) ₂ SO ₄ , (NH ₄ )HSO ₄ , Na ₂ SO ₄ , NaHSO ₄ , K ₂ S ₂ O ₈ , (NH ₄ ) ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ , KCl, CaCl ₂ , NH ₄ Cl, NaCl, KClO ₄ , NH ₄ ClO ₄ , NaClO ₄ , KF, KHF ₂ , CaF ₂ , NH ₄ F, NH ₄ HF ₂ , NaF, NaHF ₂ And combinations thereof.

The pH of the mixture can be adjusted in the range of about 3 to about 6.

The firing may be carried out at a temperature of about 200 ℃ to about 700 ℃.

Another embodiment of the present invention provides a carbon dioxide capture module comprising the carbon dioxide adsorbent.

The carbon dioxide adsorbent has excellent carbon dioxide capture capacity and high temperature operation. Due to its high carbon dioxide adsorption performance, it can be useful not only for adsorption of carbon dioxide generated in combustion, but also for adsorption of pre-combustion carbon dioxide.

1 is a flow chart showing a manufacturing process of a carbon dioxide adsorbent according to an embodiment of the present invention.
2 is a view showing the results of X-ray diffraction analysis of the composite metal oxide according to Example 1 and Comparative Example 1 and Comparative Example 2.
3 is a view showing the results of X-ray diffraction (XRD) analysis of Mg ₄ Al ₂ (OH) ₁₂ (CO ₃ )·4H ₂ O used in Comparative Example 2.
4 is a view showing the results of an isothermal cycle carbon dioxide adsorption experiment performed on the composite metal oxide of Example 2 and the composite metal oxide of Comparative Example 2.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and the ordinary skill in the art to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. Thus, in some implementations, well-known techniques are not specifically described to avoid obscuring the present invention. Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings commonly understood by a person having ordinary skill in the art to which the present invention pertains. In addition, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively, unless specifically defined. When a part of the specification "includes" a certain component, this means that other components may be further included instead of excluding other components, unless otherwise stated.

As used herein, “combination of these” may mean a mixture, laminate, complex compound, reactant, alloy, or the like.

The carbon dioxide adsorbent according to an embodiment of the present invention includes a divalent first metal (M ¹ ) and a trivalent second metal (M ² ) and an element (A) having an electronegativity of about 2.0 to about 4.0 and is amorphous ( amorphous) composite metal oxide.

The composite metal oxide may be represented by Formula 1 below.

[Formula 1]

[M ¹ _{1 - x} M ² _x A _y ]O _a

In Formula 1, M ¹ is a divalent first metal, M ² is a trivalent second metal, A is an element having an electronegativity of about 2.0 to about 4.0, x is 0.2 to 0.4, and y is 0.3 to 3 And a is the number M ¹ , M ² , and A need to balance the charge with oxygen. For example, a can range from 2.5 to 6.

The composite metal oxide is a composite containing a divalent first metal (M ¹ ) and a trivalent second metal (M ² ) and an element (A) having an electronegativity of about 2.0 to about 4.0, but not containing a carbonate anion. It may be a calcined product of a metal hydroxide.

The divalent first metal (M ¹ ) may be selected from alkaline earth metals, transition metals, and combinations thereof. Specifically, magnesium (Mg), calcium (Ca), strontium (Sr), nickel (Ni), and manganese ( Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), beryllium (Be), and combinations thereof.

The trivalent second metal (M ² ) may be selected from Group 13 elements of the IUPAC periodic table, transition metals, and combinations thereof, specifically aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe) ), cobalt (Co), lanthanum (La), cerium (Ce), gallium (Ga), indium (In), vanadium (V), and combinations thereof. The trivalent second metal (M ² ) may serve to make a passage that facilitates charge transfer to the first metal.

The first metal M ¹ and the second metal M ² may be different from each other.

In the composite oxide, the first metal (M ¹ ) and the second metal (M ² ) may be present such that M ¹ /M ² has a molar ratio of 1.5/1 to 4/1. It is not intended to be bound by a specific theory, but when the first metal is present in a higher molar ratio than the second metal, the basic properties of the first metal are greatly affected, so that it has a higher level of adsorption capacity of acid gas (such as CO ₂ ). Can.

The element (A) having an electronegativity of about 2.0 to about 4.0 may be selected from phosphorus (P), boron (B), fluorine (F), sulfur (S), chlorine (Cl), and combinations thereof. When the element (A) is introduced into the composite metal oxide, polarity on the surface may be increased to improve the adsorption performance of carbon dioxide.

The electronegativity of the element (A) may specifically range from about 2.2 to about 4.0, and more specifically from about 3.0 to about 4.0. The element (A) having the electronegativity in the above range may impart polarity to the composite metal oxide.

In the composite metal oxide, the content of the element (A) in which the electronegativity is about 2.0 to about 4.0 is a metal (total amount of the divalent first metal (M ¹ ) and the trivalent second metal (M ² )) It may range from about 0.3 mole to 3 moles, specifically about 0.5 to about 2.5 moles per mole. When the content of the element (A) is within the above range, sufficient polarity may be imparted to the composite metal oxide.

The composite metal oxide has an amorphous structure showing a broad peak in XRD diffraction analysis. When having such an amorphous structure, the composite metal oxide may have a large specific surface area of, for example, about 20 m ² /g to about 100 m ² /g, and thus may exhibit improved carbon dioxide adsorption performance .

The carbon dioxide adsorbent may further include at least one selected from alkali metal and alkali metal oxides present on the surface of the composite metal oxide. The alkali metal or alkali metal oxide may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the composite metal oxide. When the alkali metal or alkali metal oxide is included in the above range, the basic properties of the carbon dioxide adsorbent become stronger, thereby improving the adsorption performance of carbon dioxide .

According to another embodiment of the present invention, a complex metal having an amorphous structure and comprising a divalent first metal (M ¹ ) and a trivalent second metal (M ² ) and an element (A) having an electronegativity of 2.0 to 4.0 A method for preparing a carbon dioxide adsorbent containing an oxide is provided, wherein the method comprises: dissolving a salt of a divalent metal and a salt of a trivalent metal in water to obtain a mixed aqueous solution; Adjusting the pH of the mixed aqueous solution to basic to precipitate a complex metal hydroxide; Separating the composite metal hydroxide; Mixing the composite metal hydroxide with an aqueous solution of a salt containing an element having an electronegativity of about 2.0 to about 4.0 to obtain a mixture; Adjusting the pH of the mixture to 7 or less and stirring to form an ion-exchanged composite metal hydroxide; Separating the ion-exchanged composite metal hydroxide; And firing the ion-exchanged composite metal hydroxide to obtain a composite metal oxide, wherein the salt of the divalent metal and the salt of the trivalent metal do not contain carbonate anions.

The salt of the divalent metal is magnesium (Mg), calcium (Ca), strontium (Sr), nickel (Ni), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn) ), beryllium (Be), and nitrates, acetates, and hydrates thereof including the first metal (M ¹ ) selected from combinations thereof.

The salt of the trivalent metal is aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), lanthanum (La), cerium (Ce), gallium (Ga), indium (In ), vanadium (V), and nitrates, acetates, and hydrates comprising a second metal selected from combinations thereof.

The mixed aqueous solution may not substantially contain carbonate anions. For example, the water used in preparing the mixed aqueous solution may be decarbonated water without dissolved carbon dioxide.

The pH of the mixed aqueous solution can be adjusted in the range of about 9 to about 12. In order to adjust the pH of the mixed aqueous solution to basic, an inorganic base (eg, an aqueous solution of an inorganic base compound) can be used. Specific examples of the inorganic base include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; Alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; Ammonium hydroxide; ammonia; Or a combination of these may be used, but is not limited thereto. When the pH of the mixed aqueous solution is adjusted to basic, the complex metal hydroxide precipitates.

The composite metal hydroxide may be aged by stirring at a temperature of 100° C. or less, specifically 15° C. to 60° C., and more specifically 20° C. to 55° C. The aging time is not particularly limited and can be appropriately selected. For example, the aging can be performed for 12 hours or more.

The composite metal hydroxide is separated from the aqueous solution. Separation is not particularly limited, and may be performed through centrifugation, simple filtration, and the like. The separated composite metal hydroxide may be dried under atmospheric pressure (1.013 bar) or less at a temperature of 80° C. or less, specifically 60° C. or less, more specifically 40° C. or less, and more specifically 35° C. For example, the separated composite metal hydroxide can be dried (eg, in a vacuum oven) under reduced pressure at a temperature of 35° C. or less. For example, the separated composite metal hydroxide is freeze-dried at a low temperature of less than or equal to 77 Kelvin (K) using 0% or less, specifically -10°C or less, more specifically -20°C or less, such as liquid nitrogen ( freeze-drying). In the case of freeze drying, the surface area of the composite metal oxide prepared therefrom increases, and the carbon dioxide adsorption capacity can be improved.

The composite metal hydroxide is mixed with an aqueous solution of a salt containing an element having an electronegativity of about 2.0 to about 4.0 to obtain a mixture, and the pH of the mixture is adjusted to 7 or less and stirred. In this way, a portion of the anion (A ¹ ) of the salt of the divalent metal and the anion (A ² ) of the salt of the trivalent metal in the composite metal hydroxide is anion of a salt containing an element having an electronegativity of about 2.0 to about 4.0 It can be ion-exchanged with (A ³ ) to form an ion-exchanged composite metal hydroxide.

The ion-exchanged composite metal hydroxide may be represented by Formula 2 below.

[Formula 2]

[M ¹ _{1 -x} M ² _x (OH) ₂ ] ^x+ [((( A ¹ ) _y (A ² ) _z (A ³ ) _1-yz ) ^n- _x/n ] ^x -mH ₂ O

In Chemical Formula 2, M ¹ is a divalent first metal, M ² is a trivalent second metal, A ¹ is an anion of a salt of the divalent metal, A ² is an anion of a salt of the trivalent metal, and A ³ is Anions of salts containing elements with an electronegativity of from about 2.0 to about 4.0, x, y and z in the range of 0.2 to 0.4, y+z less than 1, and n being an ion exchanged anion (A ³ ) And the salt of the divalent metal and the anion (A ¹ and A ² ) of the salt of the trivalent metal, m ranges from about 0 to about 8.

The divalent metal salt of the anion (A ¹⁾ and the salt anion of a trivalent metal (A ²⁾ is a nitrate ion (NO ₃ ^-) are each independently ^- may be in acid or acetic acid ion (CH ₃ COO).

The electronegativity of the anion salt containing from about 2.0 to about 4.0 of an element is the phosphate ion (PO ₄ ^{3 -),} boric acid ion (BO _{³ 3} ^-), sulfate ion (SO ₄ ^-2), peroxide sulfate ions (S ^₂ O _{8 2} ^-), hydrochloric acid ion (Cl ^-), chlorate ion (ClO ₄ ^-), hydrofluoric acid ions (F ^- may be selected from a), and combinations thereof.

In addition, the cation of the salt containing the element having an electronegativity of about 2.0 to about 4.0 may be selected from K ⁺ , Ca ^{2 +} , NH ₄ ⁺ , Na ⁺ and combinations thereof.

Specifically, the salt containing the element having an electronegativity of about 2.0 to about 4.0 is KH ₂ PO ₄ , K ₂ HPO ₄ , CaHPO ₄ , (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ HPO ₄ , KH ₂ BO ₃ , K ₂ HBO ₃ , CaHBO ₃ , (NH ₄ )H ₂ BO ₃ , (NH ₄ ) ₂ HBO ₃ , NaH ₂ BO ₃ , Na ₂ HBO ₃ , K ₂ SO ₄ , KHSO ₄ , CaSO ₄ , (NH ₄ ) ₂ SO ₄ , (NH ₄ )HSO ₄ , Na ₂ SO ₄ , NaHSO ₄ , K ₂ S ₂ O ₈ , (NH ₄ ) ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ , KCl, CaCl ₂ , NH ₄ Cl, NaCl, KClO ₄ , NH ₄ ClO ₄ , NaClO ₄ , KF, KHF ₂ , CaF ₂ , NH ₄ F, NH ₄ HF ₂ , NaF, NaHF ₂ And combinations thereof.

In one embodiment of the present invention, since the salt of the divalent metal and the salt of the trivalent metal do not contain carbonate anions as anions (A ¹ and A ² ), the composite metal hydroxide is a hydrotal having a generally known layered structure. Unlike the site, it does not contain carbonate anions (CO ₃ ^-2 ). That is, the second a nitrate ion (NO ₃ ^-) contained in the salt and the salt of the trivalent metal of the metal, acetate ion (CH ₃ COO ^-) anion-containing and the like of elements electronegativity of about 2.0 to about 4.0 and It can be easily ion exchanged.

For ion exchange, the pH of the mixture can be adjusted to acidic conditions. Specifically, the pH of the mixture may be 7 or less, for example in the range of about 3 to about 6. A weakly acidic compound can be used to adjust the pH of the mixture to the above range. Specific examples of the weakly acidic compound include, but are not limited to, acetic acid, formic acid, phosphoric acid, oxalic acid, and salts thereof. When a salt capable of forming an acidic aqueous solution such as KH ₂ PO _{4 is used} as a salt containing an element having an electronegativity of about 2.0 to about 4.0, a separate acidic compound is used to adjust the pH of the mixture to the above range. May not be used.

The ion exchanged composite metal hydroxide is separated from the mixture. After separation, the ion-exchanged composite metal hydroxide may optionally undergo a water washing step, and is dried at atmospheric pressure or lower at a temperature of 80° C. or less, specifically 60° C. or less, and more specifically 40° C. or less Can be. For example, the separated composite metal hydroxide can be dried (eg, in a vacuum oven) under reduced pressure at a temperature of 35° C. or less. In another example, the isolated composite metal hydroxide is frozen at a temperature of 0° C. or less, specifically −10° C. or less, more specifically −20° C. or less, such as 77 Kelvin (K) temperature or lower using liquid nitrogen. It can be freeze-drying.

The ion-exchanged composite metal hydroxide, optionally washed and/or dried, is fired to become a composite metal oxide. The firing may be carried out at a temperature of about 200 °C to about 700 °C, specifically about 300 °C to about 500 °C, more specifically about 400 °C to about 500 °C. The firing can be carried out in an air atmosphere or an oxygen-containing atmosphere. The firing time is not particularly limited, and may be, for example, in the range of about 1 hour to about 20 hours. The composite metal oxide having an amorphous structure excellent in carbon dioxide adsorption performance can be obtained by the firing.

Another embodiment of the present invention is to provide a carbon dioxide capture module comprising the carbon dioxide adsorbent. The carbon dioxide adsorbent may be used by filling a column or the like, and is not particularly limited.

Hereinafter, specific embodiments of the present invention are presented. However, the examples described below are only for specifically illustrating or describing the present invention, and the present invention is not limited thereto.

Example

[Production of Complex Metal Oxide]

Example One

Aqueous aluminum nitrate (Al(NO ₃ ) ₃ ·9H ₂ O) and magnesium nitrate (Mg(NO ₃ ) ₂ ·6H ₂ O) are mixed with 200 ml of water to prepare an aqueous solution. Here, the amount of the precursor is adjusted so that the molar ratio of Mg and Al is 3:1. NaOH was dissolved in water to prepare 100 ml of a 1M NaOH aqueous solution. A NaOH aqueous solution is added to the aqueous solution to precipitate a complex metal hydroxide of Mg and Al. The pH of the complex metal hydroxide during precipitation is set at about 9.5 to 10.5. The obtained composite metal hydroxide is aged through strong stirring at room temperature (25°C) for 24 hours. Thereafter, the composite metal hydroxide is filtered by centrifugation (8000 RPM, 10 minutes) and washed with water. This process is repeated three more times. The separated composite metal hydroxide is dried in a vacuum oven at room temperature (25°C) to obtain a composite metal hydroxide in powder form. 1 g of the composite metal hydroxide powder was added to 200 ml of a 0.1 M KH ₂ PO ₄ aqueous solution and vigorously stirred for 24 hours to perform ion exchange to obtain ion-exchanged composite metal hydroxide. The pH at ion exchange is 4.5. The ion-exchanged composite metal hydroxide is separated by filtration, washed, and dried in a vacuum oven at room temperature (25°C). The dried powder is fired at 400° C. for 5 hours in an air atmosphere to obtain a composite metal oxide. For all the water used here, decarbonated and distilled water is used to remove dissolved CO ₂ by bubbling nitrogen.

Example 2

Example 1 and except that the composite metal hydroxide separated after three or more washings was freeze-dried using liquid nitrogen at a temperature of 77 Kelvin (K) and a pressure of 0.1 bar to obtain a composite metal hydroxide in powder form. A composite metal oxide is prepared in the same way.

Comparative example One

Aqueous aluminum nitrate (Al(NO ₃ ) ₃ ·9H ₂ O) and magnesium nitrate (Mg(NO ₃ ) ₂ ·6H ₂ O) are mixed with 200 ml of water to prepare an aqueous solution. Here, the amount of the precursor is adjusted so that the molar ratio of Mg and Al is 3:1. NaOH was dissolved in water to prepare 100 ml of a 1M NaOH aqueous solution. A NaOH aqueous solution is added to the aqueous solution to precipitate a complex metal hydroxide. The pH of the complex metal hydroxide during precipitation is set at about 9.5 to 10.5. The obtained composite metal hydroxide is aged through strong stirring at room temperature (25°C) for 24 hours. Thereafter, the composite metal hydroxide is filtered by centrifugation (8000 RPM, 10 minutes) and washed with water. This process is repeated three more times. The separated composite metal hydroxide is freeze-dried by using liquid nitrogen at 77 Kelvin (K) temperature and a pressure of 0.1 bar to freeze-dry to obtain a composite metal hydroxide in powder form. The composite metal hydroxide is fired at 400° C. for 5 hours in an air atmosphere to prepare a composite metal oxide.

Comparative example 2

Mg ₄ Al ₂ (OH) ₁₂ (CO ₃ )·4H ₂ O, a composite metal hydroxide containing carbonate salt, is heat treated in an air atmosphere for 5 hours to prepare a composite metal oxide.

Comparative example 3

Aqueous aluminum nitrate (Al(NO ₃ ) ₃ ·9H ₂ O) and magnesium nitrate (Mg(NO ₃ ) ₂ ·6H ₂ O) are mixed with 200 ml of water to prepare an aqueous solution. Here, the amount of the precursor is adjusted so that the molar ratio of Mg and Al is 3:1. NaOH was dissolved in water to prepare 100 ml of a 1M NaOH aqueous solution. A NaOH aqueous solution is added to the aqueous solution to precipitate a complex metal hydroxide. The pH of the complex metal hydroxide during precipitation is set at about 9.5 to 10.5. The obtained composite metal hydroxide is aged through strong stirring at room temperature (25°C) for 24 hours. Thereafter, the composite metal hydroxide is filtered by centrifugation (8000 RPM, 10 minutes) and washed with water. This process is repeated 3 times. The separated composite metal hydroxide is lyophilized using liquid nitrogen at a temperature of 77 Kelvin (K) and a pressure of 0.1 bar to obtain a composite metal hydroxide in powder form. 1 g of the composite metal hydroxide powder was added to 200 ml of 0.1 MK ₂ HPO ₄ aqueous solution and vigorously stirred for 24 hours to perform ion exchange to obtain ion-exchanged composite metal hydroxide. The pH at ion exchange is 9.1. The ion-exchanged composite metal hydroxide is separated by filtration, washed, and dried in a vacuum oven at room temperature (25°C). The dried powder is fired at 400° C. for 5 hours in an air atmosphere to obtain a composite metal oxide. For all the water used here, decarbonated and distilled water is used to remove dissolved CO ₂ by bubbling nitrogen.

[Characteristic analysis of complex metal oxides]

Crystallinity analysis

X-ray diffraction (XRD) analysis of the composite metal oxides prepared in Examples 1 and 2 and Comparative Examples 1 to 3 is performed. X-ray diffraction analysis was performed at a scan rate of 0.2 degrees per second using a Cu Kα ray (equipment: Philips X'pert X-ray diffractometer) operated at 40 kV and 40 mA. As a result, it was confirmed that the composite metal oxides of Examples 1 and 2 were amorphous, and the composite metal oxides of Comparative Examples 1 to 3 were crystalline. For example, FIG. 2 is a view showing the results of the composite metal oxides of Example 1 and Comparative Example 1 and Comparative Example 2. The composite metal oxides of Comparative Example 1 and Comparative Example 2 are MgO phase (indicated by s in Fig. 2) and MgAl ₂ O ₄ While the peak of the crystalline phase of the phase (denoted by p in FIG. 2) is shown, it can be seen that the composite metal oxide according to Example 1 has an amorphous structure. In addition, the results of X-ray diffraction (XRD) analysis of Mg ₄ Al ₂ (OH) ₁₂ (CO ₃ )·4H ₂ O used in Comparative Example 2 are shown in FIG. 3. From FIG. 3, the crystalline peak of Mg ₄ Al ₂ (OH) ₁₂ (CO ₃ )·4H ₂ O is also observed in the X-ray diffraction spectrum of the composite metal oxide according to Comparative Example 2, and thus Mg ₄ Al ₂ (OH) _It can be seen that the crystalline structure of ₁₂ (CO ₃ )·4H ₂ O remains undisintegrated even after firing.

Specific surface area Measure

The surface area of the composite metal oxides of Examples 1 and 2 and Comparative Examples 1 to 3 is measured through nitrogen adsorption/desorption isothermal reaction using Bell Japan's Bell SorpMax instrument, and summarized in Table 1 below.

Determination of metal and phosphorus content in composite metal oxides

20 mg of the complex metal oxides of Examples 1 and 2 and Comparative Examples 1 to 3 were prepared by adding 1 ml of hydrochloric acid, 0.1 ml of nitric acid, and 10 ml of deionized water. Take 1 ml each from the above solution, put it in a 10 ml tube or flask, and dilute 10 times with 2% HCl to prepare a sample solution. Mg, Al, and P content in the composite metal oxide were analyzed using the sample solution and an inductively coupled plasma atomic emission spectrometer (ICP-AES) (equipment: Shimadzu ICPS-8100 sequential spectrometer). The results are summarized in Table 1 below.

Mg (wt.%) Al (wt.%) Mg/Al (atomic ratio) P (wt.%) BET surface area (m ² /g) Example 1 25.0 9.8 2.83 15.9 34 Example 2 15.4 7.8 2.20 22.1 73 Comparative Example 1 34.4 13.9 2.75 - 210 Comparative Example 2 31.9 12.4 2.86 - 42 Comparative Example 3 29.6 12.1 2.72 6.3 61

From Table 1, it can be seen that in the case of Example 1, Example 2, and Comparative Example 3, P forms a complex metal oxide with Mg and Al.

[Co2 adsorption experiment using complex metal oxide]

carbon dioxide Adsorption capacity test

The composite metal oxides according to Examples 1 and 2 and Comparative Examples 1 to 3 were each filled in a quartz column by 0.25 g, and then post-combustion through the column (10% by volume) CO ₂ /90% by volume N ₂ The mixed gas composition and the pre-combustion 40 vol% CO ₂ /60 vol% H ₂ mixed gas composition are flowed at a rate of 200 ml/min at a temperature of 200° C. and a pressure of 1 bar. From the adsorption experiment, CO ₂ adsorption capacity of the composite metal oxides of Examples 1 and 2 and Comparative Examples 1 to 3 was measured, and the results are summarized in Table 2 below. Adsorption capacity is determined according to the following equation:

Adsorption capacity (mmol/g or wt%) = CO ₂ content (mmol or g)/ adsorbent weight (g)

In Table 1 below, “total CO ₂ adsorption capacity” is the total amount of CO ₂ adsorbed per gram of adsorbent during the CO ₂ adsorption capacity experiment (mmol or g), and “90% BT adsorption capacity” (ie 90% breakthrough adsorption capacity )) is a total amount of adsorption of CO ₂ until on the breakthrough curve (breakthrough curve) adsorbent per 1g of 10% of the CO ₂ content of the initial CO ₂ is no longer be adsorbed to be detected in real time.

Gas composition and adsorption capacity Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 10CO ₂ /90N ₂ Total CO2 adsorption capacity
(mmol/g) 2.57
(11.3 wt.%) 3.07
(13.51 wt.%) 1.07
(4.71 wt.%) 1.08
(4.75 wt.%) 1.24
(5.46 wt.%) BT 90% adsorption capacity
(mmol/g) 2.36
(10.38 wt.%) 2.73
(12.01 wt.%) 0.81
(3.56 wt.%) 0.77
(3.39 wt.%) 1.01
(4.44 wt.%) 40CO ₂ /60H ₂ Total CO2 adsorption capacity
(mmol/g) 5.18
(22.79 wt.%) 7.00
(30.8 wt.%) 3.41
(15.0 wt.%) 3.30
(14.52 wt.%) 3.59
(15.80 wt.%) BT 90% adsorption capacity
(mmol/g) 4.30
(18.92 wt.%) 5.82
(25.61 wt.%) 2.91
(12.80 wt.%) 2.70
(11.88 wt.%) 3.07
(13.51 wt.%)

From the results of Table 2, it can be seen that the composite metal oxides of Examples 1 and 2 show a higher level of carbon dioxide adsorption performance than the composite metal oxides of Comparative Examples 1 to 3.

Evaluation of adsorption performance according to temperature

The composite metal oxide of Example 2 was filled in a quartz column and then subjected to carbon dioxide adsorption experiments at temperatures of 200° C., 300° C., 400° C., and 500° C. under the following conditions, and total carbon dioxide from the resulting breakthrough curve. The adsorption capacity and 90% BT adsorption capacity are calculated and summarized in Table 3 below:

Composition of the inlet gas stream: 40% CO ₂ + 60% H ₂

Total flow rate: 200ml/min

Weight of the filled composite metal oxide: 0.25 g

Pressure: 1 bar

Temperature Total carbon dioxide adsorption capacity (mmol/g) 90% BT adsorption capacity (mmol/g) 200℃ 7.00
(30.8 wt.%) 5.82
(25.6 wt.%) 300℃ 7.82
(34.4 wt.%) 6.70
(29.5 wt.%) 400℃ 9.30
(40.9 wt.%) 7.91
(34.8 wt.%) 500℃ 6.11
(26.9 wt.%) 4.77
(21.0 wt.%)

From the results of Table 3, it can be seen that the composite metal oxide of Example 2 has a high level of adsorption capacity at a temperature of 200°C to 500°C.

Durability test of composite metal oxide (isothermal circulation test)

The composite metal oxides of Example 2 and Comparative Example 2 were filled in a quartz column, and a carbon dioxide adsorption performance experiment (isothermal regeneration test) was performed for 100 cycles under the following conditions to observe changes in carbon dioxide adsorption capacity, and the results are shown in FIG. 5. Indicates:

Composition of the inlet gas stream: 40% CO ₂ + 60% H ₂

Total flow rate: 200ml/min

Weight of the filled composite metal oxide: 0.25 g

Temperature and pressure: 200℃, 1bar

From the results of FIG. 5, it can be seen that the composite metal oxide of Example 3 maintains an adsorption capacity of 25 wt% or more for up to 100 cycles, and there is no substantial change in adsorption capacity. On the other hand, it can be seen that the composite metal oxide of Comparative Example 2 exhibits an adsorption capacity of about 10 wt% and a significant decrease in adsorption capacity.

Although preferred embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

Claims (26)

delete delete delete delete delete delete delete delete delete delete delete To prepare a carbon dioxide adsorbent comprising a complex metal oxide having an amorphous structure and containing a divalent first metal (M ¹ ) and a trivalent second metal (M ² ) and an element (A) having an electronegativity of 2.0 to 4.0 As a method,
Dissolving a salt of a divalent metal and a salt of a trivalent metal in water to obtain a mixed aqueous solution; Adjusting the pH of the mixed aqueous solution to basic to precipitate a complex metal hydroxide; Separating the composite metal hydroxide; Mixing the composite metal hydroxide with an aqueous solution of a salt containing an element having an electronegativity of about 2.0 to about 4.0 to obtain a mixture; Adjusting the pH of the mixture to 7 or less and stirring to form an ion-exchanged composite metal hydroxide; Separating the ion-exchanged composite metal hydroxide; And firing the ion-exchanged composite metal hydroxide to obtain a composite metal oxide, wherein the salt of the divalent metal and the salt of the trivalent metal do not contain carbonate anions. The method of claim 12,
The salt of the divalent metal is a method for producing a carbon dioxide adsorbent selected from nitrates, acetates and hydrates of the first metal selected from alkaline earth metals, transition metals, and combinations thereof. The method of claim 13,
The salt of the divalent metal is magnesium (Mg), calcium (Ca), strontium (Sr), nickel (Ni), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn) ), beryllium (Be), and a method for producing a carbon dioxide adsorbent selected from nitrates, acetates, and hydrates comprising the first metal selected from combinations thereof. The method of claim 12,
The salt of the trivalent metal is a carbon dioxide adsorbent selected from nitrates, acetates and hydrates thereof, which is different from the first metal, and includes a second metal selected from Group 13 elements of the IUPAC periodic table, transition metals, and combinations thereof. Method of manufacturing. The method of claim 15,
The salt of the trivalent metal is aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), lanthanum (La), cerium (Ce), gallium (Ga), indium (In) ), a method for producing a carbon dioxide adsorbent selected from nitrates, acetates and hydrates comprising a second metal selected from vanadium (V) and combinations thereof. The method of claim 12,
The method of preparing a carbon dioxide adsorbent whose pH of the mixed aqueous solution is adjusted to 9 to 12. The method of claim 12,
The method further comprises the step of aging the composite metal hydroxide with stirring at a temperature of 60° C. or less to produce a carbon dioxide adsorbent. The method of claim 12,
The method further comprises the step of drying the composite metal hydroxide under a temperature of 60° C. or less and a pressure of atmospheric pressure or less. The method of claim 12,
The ion-exchanged composite metal hydroxide is a method for preparing a carbon dioxide adsorbent represented by the following Chemical Formula 2:
[Formula 2]
[M ¹ _{1 -x} M ² _x (OH) ₂ ] ^x+ [((( A ¹ ) _y (A ² ) _z (A ³ ) _1-yz ) ^n- _x/n ] ^x -mH ₂ O
In Formula 2, M ¹ is a divalent first metal, M ² is a trivalent second metal, A ¹ is an anion of the salt of the divalent metal, A ² is an anion of the salt of the trivalent metal, and A ³ is The electronegativity is an anion of a salt containing an element of about 2.0 to about 4.0, x, y and z are respectively in the range of about 0.2 to about 0.4, y + z is less than 1, n is an ion exchanged anion It is determined according to the valence of (A ³ ) and the anion of the divalent metal salt and the anion (A ¹ and A ² ) of the trivalent metal salt, and m ranges from about 0 to about 8. The method of claim 12,
The divalent salt of the anion of the metal (A ²⁾ and the salt anion of a trivalent metal (A ³⁾ is nitrate ion are each independently (NO ₃ ^-) acetate ions (CH ₃ COO ^-) and the carbon dioxide adsorbent is selected from a combination of Method of manufacturing. The method of claim 12,
Salt anions which the electronegativity contains 2.0 to 4.0 in an element is the phosphate ion (PO ₄ ^{3 -),} boric acid ion (BO _{³ 3} ^-), sulfate ion (SO ₄ ^{2 -),} peroxide sulfuric acid ion (S ₂ O ^{₈₂ -),} a hydrochloric acid ion (Cl ^-), chlorate ion (ClO ₄ ^-), hydrofluoric acid ions (F ^-) and the method for producing a carbon dioxide adsorbent is selected from a combination of the two. The method of claim 12,
The method for producing a carbon dioxide adsorbent containing a cation in the salt containing the element having an electronegativity of 2.0 to 4.0 is K ⁺ , Ca ^{2 +} , NH ₄ ⁺ , Na ⁺ and combinations thereof. The method of claim 12,
A method of preparing a carbon dioxide adsorbent to maintain the pH of the mixture at 3 to 6 to form the ion-exchanged composite metal hydroxide. The method of claim 12,
The firing method of the carbon dioxide adsorbent is carried out at a temperature of 200 ℃ to 700 ℃. delete

Images