Mesoporous cellular foam impregnated with iron-substituted heteropolyacid, preparation method therefor, and carbon dioxide separation method using same

Abstract

Disclosed is a novel adsorbent having excellent adsorption durability and high adsorption efficiency while having improved durability, thereby improving a carbon dioxide (CO2) separation process. A mesoporous cellular foam impregnated with an iron (Fe)-substituted heteropolyacid includes a mesoporous cellular foam support and an Fe-substituted heteropolyacid, and the mesoporous cellular foam impregnated with an Fe-substituted heteropolyacid has superior CO2 adsorption performance and exhibits excellent reproduction performance even after CO2 adsorption and desorption are performed several times through temperature changes, thereby enabling efficient and economical CO2 separation.

Claims

1. A mesoporous cellular foam impregnated with an iron-substituted heteropolyacid, the mesoporous cellular foam comprising: a mesoporous cellular foam support; and an iron-substituted heteropolyacid.

2. The mesoporous cellular foam of claim 1, wherein a weight of the iron-substituted heteropolyacid is about 50% to about 90% of a weight of the mesoporous cellular foam support.

3. The mesoporous cellular foam of claim 1, wherein a weight of the iron-substituted heteropolyacid is about 70% of a weight of the mesoporous cellular foam support.

4. The mesoporous cellular foam of claim 1, wherein a molar ratio of ammonium (NH.sub.4) to silicon (Si) in the mesoporous cellular foam support is 6:1.

5. The mesoporous cellular foam of claim 1, wherein the molecular formula of the iron-substituted heteropolyacid is Fe.sub.2.0SiW.sub.12O.sub.40.

6. A method of preparing a mesoporous cellular foam impregnated with an iron-substituted heteropolyacid, the method comprising: providing distilled water; dissolving 0.1 g of iron-substituted heteropolyacid (Fe-HPA) per 10 ml of the distilled water to prepare an aqueous solution; adding a mesoporous cellular foam support having a weight of a larger value than that of the iron-substituted heteropolyacid in the aqueous solution; stirring the aqueous solution to which the support is added; and drying the stirred aqueous solution at a temperature in a range of about 90° C. to about 110° C. for about 9 hours to about 11 hours.

7. The method of claim 6, wherein a weight of the iron-substituted heteropolyacid is about 50% to about 90% of a weight of the mesoporous cellular foam support.

8. The method of claim 6, wherein a weight of the iron-substituted heteropolyacid is about 70% of the mesoporous cellular foam support.

9. A method of separating carbon dioxide by using a mesoporous cellular foam impregnated with an iron-substituted heteropolyacid, the method comprising: adsorbing carbon dioxide by contacting a carbon dioxide-mixed gas with the mesoporous cellular foam of claim 1 at a temperature in a range of about 25° C. to about 75° C.; and desorbing carbon dioxide by placing the mesoporous cellular foam impregnated with an iron-substituted heteropolyacid which adsorbed carbon dioxide at a temperature in a range of about 100° C. to about 120° C.

10. The method of claim 9, wherein the adsorbing carbon dioxide is performed at 50° C.

11. The method of claim 9, wherein the desorbing carbon dioxide is performed at 110° C.

12. The method of claim 9, wherein a weight of the iron-substituted heteropolyacid of the mesporous cellular foam is about 50% to about 90% of a weight of the mesoporous cellular foam support of the mesporous cellular foam.

13. The method of claim 9, wherein a weight of the iron-substituted heteropolyacid of the mesporous cellular foam is about 70% of a weight of the mesoporous cellular foam support of the mesporous cellular foam.

14. The method of claim 9, wherein a molar ratio of ammonium (NH.sub.4) to silicon (Si) in the mesoporous cellular foam support of the mesporous cellular foam is 6:1.

15. The method of claim 9, wherein the molecular formula of the iron-substituted heteropolyacid of the mesporous cellular foam is Fe.sub.2.0SiW.sub.12O.sub.40.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a process of an iron-substituted heteropolyacid being impregnated into a mesoporous cellular foam support;

(2) FIG. 2 is a graph of 50 wt % Fe-HPA-MCFs showing carbon dioxide adsorption at 25° C., 50° C., and 75° C. and carbon dioxide adsorption and desorption at 110° C.;

(3) FIG. 3 is a graph of 70 wt % Fe-HPA-MCFs showing carbon dioxide adsorption at 25° C., 50° C., and 75° C. and carbon dioxide adsorption and desorption at 110° C.;

(4) FIG. 4 is a graph of 90 wt % Fe-HPA-MCFs showing carbon dioxide adsorption at 25° C., 50° C., and 75° C. and carbon dioxide adsorption and desorption at 110° C.; and

(5) FIG. 5 shows carbon dioxide adsorption performance of 70 wt % Fe-HPA-MCFs observed at 25° C. while repeating 10 cycles of adsorption and desorption.

EMBODIMENTS

(6) Hereinafter, the inventive concept will be described in detail by explaining embodiments of the inventive concept with reference to the attached drawings. In the description of the embodiments, certain detailed explanations of related art are omitted when it is deemed that they may unnecessarily obscure the essence of the invention.

(7) According to an embodiment of the present invention, a mesoporous cellular foam with large pores is impregnated with an iron-substituted heteropolyacid that has a chemical absorptivity with respect to carbon dioxide so that the two materials compensate adsorbing abilities to maximize carbon dioxide adsorbing ability.

(8) FIG. 1 illustrates a process of an iron-substituted heteropolyacid (hereinafter, also referred to as “Fe-HPA”) being impregnated into a mesoporous cellular foam (hereinafter, also referred to as “MCF”) support, and thus provides an iron-substituted heteropolyacid impregnated mesoporous cellular foam (hereinafter, also referred to as “Fe-HPA-MCF”). The process will be described as follows.

(9) MCF Support (MCFs) Synthesis

(10) In one embodiment of the present invention, a solution was prepared by dissolving 2.0 g of poly(ethylene glycol)-blockpoly(propyleneglycol)-blockpoly(ethyleneglycol)(P123) in 75 ml of hydrochloric acid (HCl) at a concentration of 1.6 M at room temperature. 5.0 g of 1,3,5-trimethyl benzene (TMB) and 46 mg of ammonium fluoride (NH.sub.4F) were added to the solution, and the solution was rapidly stirred at 40° C. for 2 hours. After stirring, 4.4 g of tetra ethyl ortho silicate (TEOS) was added thereto and stirred for 24 hours. Then, the milky mixture was placed in a pressurized reactor, and a temperature therein was maintained at 100° C. for 24 hours. The synthesized resultant was filtered and dried at room temperature for 48 hours. The dried sample was sintered in the air at 550° C. for 6 hours, a template of the sample was then removed, and the sintered sample was used as MCFs. A molar ratio of ammonium (NH.sub.4) and silicon (Si) of the synthesized MCFs was 6:1.

(11) Synthesis of Iron (Fe)-Substituted Heteropolyacid (HPA) (Fe-HPA)

(12) In one embodiment of the present invention, 0.18 g of barium hydroxide (Ba(OH).sub.2.8H.sub.2O) was added to an aqueous solution prepared by dissolving 2.0 g of silicotungsticacid (H.sub.4SiM.sub.2O.sub.40) in 5 ml of distilled water. Then, 0.16 g of iron sulfate (FeSO.sub.4.7H.sub.2O) was added to remove barium (Ba) in the form of barium sulfate (BaSO.sub.4) and substituted with iron. Then the solution was evaporated by using nitrogen bubbling that penetrated through the solution to extract an iron-substituted heteropolyacid (Fe-HPA, Fe.sub.2.0SiW.sub.12O.sub.40), which is a composite.

(13) Synthesis of Fe-HPA-MCFs.

(14) A predetermined amount of the iron-substituted heteropolyacid (Fe-HPA) extracted from the process was dissolved in distilled water, and an amount of MCFs at a weight that is higher than a weight of the iron-substituted heteropolyacid was added thereto. In one embodiment of the present invention, a weight ratio of the iron-substituted heteropolyacid (Fe-HPA) to MCFs was 0.5. Also, in some embodiments of the present invention, the weight ratio of the iron-substituted heteropolyacid to MCFs may be 0.7 or 0.9. A slurry formed by the reaction was stirred and dried. In one embodiment of the present invention, after 1 hour of stirring the slurry, the resultant was dried at a temperature of 100° C. for 10 hours in an oven.

Example 1. 50 wt % Fe-HPA-MCFs

(15) 0.5 g of the iron-substituted heteropolyacid (Fe-HPA) extracted from the process was dissolved in 50 ml of distilled water, and 1.0 g of MCFs was added thereto. A slurry formed by the reaction was stirred for 1 hour, and dried at a temperature of 100° C. for 10 hours in an oven. The resultant was referred to as 50 wt % Fe-HPA-MCFs.

(16) Adsorption performance of the 50 wt % Fe-HPA-MCFs was measured at a temperature of 25° C., 50° C., or 75° C., and desorption performance of the 50 wt % Fe-HPA-MCFs was measured at a temperature of 110° C. The adsorption-desorption measurement was performed by using a heat-weight analyzer N-1000, where the adsorption was performed in the atmosphere at a temperature of 25° C., 50° C., or 75° C. using high purity carbon dioxide (15.1%), and the desorption was performed while flowing nitrogen gas at a temperature of 110° C. A continuous carbon dioxide adsorption-desorption profile was obtained by automatic alternation of heating, cooling, and carbon dioxide (15.1%) and nitrogen (N.sub.2).

(17) FIG. 2 is a graph of 50 wt % Fe-HPA-MCFs showing carbon dioxide adsorption at 25° C., 50° C., and 75° C. and carbon dioxide adsorption and desorption at 110° C. When a weight of the sample in the initial state is 100 wt %, the weight of the sample decreases as a nitrogen gas is flowed thereto for 200 minutes at 110° C., and this is because water molecules and moisture adsorbed in the sample evaporate. After decreasing a temperature of the sample for about 20 minutes, when carbon dioxide gas is flowed thereto, a weight of the sample increases, but after about 180 minutes, an increase of the weight of the sample reaches its saturation value, and this denotes that an absorption amount of carbon dioxide of the sample has increased and saturated. When nitrogen gas is flowed to the carbon dioxide-saturated 50 wt % Fe-HPA-MCFs and maintained at 110° C. for 2 hours, a weight of the sample decreases again, and this is a process when the adsorbed carbon dioxide starts to desorb. The carbon dioxide-desorbed 50 wt % Fe-HPA-MCFs is again cooled to a temperature of 50° C. in a carbon dioxide atmosphere and maintained for 2 hours so that carbon dioxide to adsorb, and thus a weight of the sample increases. Subsequently, carbon dioxide is desorbed from the sample by maintaining a temperature at 110° C. for 2 hours in a nitrogen atmosphere, and then a temperature was maintained at 75° C. for 2 hours in a carbon dioxide atmosphere.

(18) As a result, it may be known that an adsorption amount of carbon dioxide decreases as a temperature increases from 25° C. to 50° C. and to 75° C., and the adsorption amount of carbon dioxide was constantly the lowest value at 110° C. Therefore, 50 wt % Fe-HPA-MCFs may be used as an absorbent for separating carbon dioxide that adsorbs carbon dioxide at a low temperature between 25° C. and 75° C. at which an adsorption amount is a certain value or higher and that desorbs carbon dioxide at a high temperature of 110° C.

(19) An amount of carbon dioxide adsorbed by the 50 wt % Fe-HPA-MCFs was 99.3 mg at 25° C., 76.4 mg at 50° C., and 52.2 mg at 75° C. per 1 g of Fe-HPA-MCFs.

Example 2. 70 wt % Fe-HPA-MCFs

(20) 0.7 g of the iron-substituted heteropolyacid (Fe-HPA) was dissolved in 70 ml of distilled water, and 1.0 g of MCFs was added thereto. A slurry formed by the reaction was stirred for 1 hour, and dried at a temperature of 100° C. for 10 hours in an oven. The resultant was referred to as 70 wt % Fe-HPA-MCFs.

(21) Adsorption performance of the 70 wt % Fe-HPA-MCFs was measured at a temperature of 25° C., 50° C., or 75° C., and desorption performance of the 70 wt % Fe-HPA-MCFs was measured at a temperature of 110° C. The adsorption-desorption measurement was performed by using a heat-weight analyzer N-1000, available from SCINO, where the adsorption was performed in the atmosphere at a temperature of 25° C., 50° C., or 75° C. using high purity carbon dioxide (15.1%), and the desorption was performed while flowing nitrogen gas at a temperature of 110° C. A continuous carbon dioxide adsorption-desorption profile was obtained by automatic alternation of heating, cooling, and carbon dioxide (15.1%) and nitrogen (N.sub.2).

(22) Adsorption performance of the 70 wt % Fe-HPA-MCFs was measured at a temperature of 25° C., 50° C., or 75° C., and desorption performance of the 70 wt % Fe-HPA-MCFs was measured at a temperature of 110° C. FIG. 3 is a graph of 70 wt % Fe-HPA-MCFs showing carbon dioxide adsorption at 25° C., 50° C., and 75° C. and carbon dioxide adsorption and desorption at 110° C. When a weight of the sample in the initial state is 100 wt %, the weight of the sample decreases as a nitrogen gas is flowed thereto for 200 minutes at 110° C., and this is because water molecules and moisture adsorbed in the sample evaporate. After decreasing a temperature of the sample for about 20 minutes, when carbon dioxide gas is flowed thereto, a weight of the sample increases, but after about 180 minutes, an increase of the weight of the sample reaches its saturation value, and this denotes that an absorption amount of carbon dioxide of the sample has increased and saturated. When nitrogen gas is flowed to the carbon dioxide-saturated 70 wt % Fe-HPA-MCFs and maintained at 110° C. for 2 hours, a weight of the sample decreases again, and this is a process when the adsorbed carbon dioxide starts to desorb. The carbon dioxide-desorbed 70 wt % Fe-HPA-MCFs is again cooled to a temperature of 50° C. in a carbon dioxide atmosphere and maintained for 2 hours so that carbon dioxide to adsorb, and thus a weight of the sample increases. Subsequently, carbon dioxide is desorbed from the sample by maintaining a temperature at 110° C. for 2 hours in a nitrogen atmosphere, and then a temperature was maintained at 75° C. for 2 hours in a carbon dioxide atmosphere.

(23) As a result, it may be known that an adsorption amount of carbon dioxide decreases as a temperature increases from 25° C. to 50° C. and to 75° C., and the adsorption amount of carbon dioxide was constantly the lowest value at 110° C. Therefore, 70 wt % Fe-HPA-MCFs may be used as an absorbent for separating carbon dioxide that adsorbs carbon dioxide at a low temperature between 25° C. and 75° C. at which an adsorption amount is a certain value or higher and that desorbs carbon dioxide at a high temperature of 110° C.

(24) An amount of carbon dioxide adsorbed by the 70 wt % Fe-HPA-MCFs was 111.8 mg at 25° C., 77.9 mg at 50° C., and 55.5 mg at 75° C. per 1 g of Fe-HPA-MCFs.

Example 3. 90 wt % Fe-HPA-MCFs

(25) 0.9 g of the iron-substituted heteropolyacid (Fe-HPA) was dissolved in 90 ml of distilled water, and 1.0 g of MCFs was added thereto. A slurry formed by the reaction was stirred for 1 hour, and dried at a temperature of 100° C. for 10 hours in an oven. The resultant was referred to as 90 wt % Fe-HPA-MCFs.

(26) Adsorption performance of the 90 wt % Fe-HPA-MCFs was measured at a temperature of 25° C., 50° C., or 75° C., and desorption performance of the 70 wt % Fe-HPA-MCFs was measured at a temperature of 110° C. The adsorption-desorption measurement was performed by using a heat-weight analyzer N-1000, available from SCINO, where the adsorption was performed in the atmosphere at a temperature of 25° C., 50° C., or 75° C. using high purity carbon dioxide (15.1%), and the desorption was performed while flowing nitrogen gas at a temperature of 110° C. A continuous carbon dioxide adsorption-desorption profile was obtained by automatic alternation of heating, cooling, and carbon dioxide (15.1%) and nitrogen (N.sub.2).

(27) FIG. 4 is a graph of 90 wt % Fe-HPA-MCFs showing carbon dioxide adsorption at 25° C., 50° C., and 75° C. and carbon dioxide adsorption and desorption at 110° C. When a weight of the sample in the initial state is 100 wt %, the weight of the sample decreases as a nitrogen gas is flowed thereto for 200 minutes at 110° C., and this is because water molecules and moisture adsorbed in the sample evaporate. After decreasing a temperature of the sample for about 20 minutes, when carbon dioxide gas is flowed thereto, a weight of the sample increases, but after about 180 minutes, an increase of the weight of the sample reaches its saturation value, and this denotes that an absorption amount of carbon dioxide of the sample has increased and saturated. When nitrogen gas is flowed to the carbon dioxide-saturated 90 wt % Fe-HPA-MCFs and maintained at 110° C. for 2 hours, a weight of the sample decreases again, and this is a process when the adsorbed carbon dioxide starts to desorb. The carbon dioxide-desorbed 90 wt % Fe-HPA-MCFs is again cooled to a temperature of 50° C. in a carbon dioxide atmosphere and maintained for 2 hours so that carbon dioxide to adsorb, and thus a weight of the sample increases. Subsequently, carbon dioxide is desorbed from the sample by maintaining a temperature at 110° C. for 2 hours in a nitrogen atmosphere, and then a temperature was maintained at 75° C. for 2 hours in a carbon dioxide atmosphere.

(28) As a result, it may be known that an adsorption amount of carbon dioxide decreases as a temperature increases from 25° C. to 50° C. and to 75° C., and the adsorption amount of carbon dioxide was constantly the lowest value at 110° C. Therefore, 90 wt % Fe-HPA-MCFs may be used as an absorbent for separating carbon dioxide that adsorbs carbon dioxide at a low temperature between 25° C. and 75° C. at which an adsorption amount is a certain value or higher and that desorbs carbon dioxide at a high temperature of 110° C.

(29) An amount of carbon dioxide adsorbed by the 90 wt % Fe-HPA-MCFs was 112 mg at 25° C., 78.8 mg at 50° C., and 55.9 mg at 75° C. per 1 g of Fe-HPA-MCFs.

(30) In this regard, it was confirmed that when a weight ratio of Fe-HPA in a Fe-HPA-MCFs composition increases, an adsorption amount increases, and as a temperature decreases, an adsorption amount increases. That is, a process that adsorbs carbon dioxide at a temperature of 25° C. and desorbs carbon dioxide at a temperature of 110° C. is relatively efficient.

Example 4. Regenerating Performance of 70 wt % Fe-HPA-MCFs

(31) FIG. 5 shows an adsorption amount of carbon dioxide according to the cycle number of carbon dioxide adsorption and desorption by using 70 wt % Fe-HPA-MCFs. 10 cycles of adsorbing carbon dioxide at 25° C. and desorbing carbon dioxide at 110° C. were performed, and the adsorption ability of the absorbent, 70 wt % Fe-HPA-MCFs, almost did not change, and thus regenerating performance of the absorbent was confirmed excellent.

(32) Although the mesoporous cellular foam impregnated with an iron-substituted heteropolyacid may have different carbon dioxide adsorbing ability according to its composition ratio and temperature, a carbon dioxide adsorption performance of the mesoporous cellular foam impregnated with an iron-substituted heteropolyacid in general is excellent within an adsorption temperature range of about 25° C. to about 75° C., and a carbon dioxide desorption performance of the mesoporous cellular foam at 110° C. is the same with the initial state, which showed excellent regenerating ability, and thus proved performance to be used as an excellent novel carbon dioxide adsorbent.

(33) It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.

(34) While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.