KR102002640B1 - Manufacturing method of mesoporous silica materials as CO2 adsorbent with inroduction of Amin functional group - Google Patents

Abstract

(A) forming polystyrene as a core material by adding styrene as a precursor and AIBA as a thermal initiator to a solvent in which distilled water and acetone are mixed at a predetermined ratio; (b) adding polystyrene formed in step (a) to a mixed solution of distilled water and ethanol at a predetermined ratio, adding cetyltrimethylammonium chloride (CTACl) as a cationic surfactant and tetraethylorthosilicate (TEOS) as a precursor, Adding ammonia water to the stirred solution, and then calcining the mixture at a predetermined temperature for a predetermined time to form a mesoporous hollow silica material; And (c) introducing an amine functional group into the mesoporous hollow silica material formed in step (b) by adding a predetermined amine-based precursor through impregnation and stirring the mixture for a predetermined time, followed by drying at a predetermined temperature and at a predetermined temperature A method for producing a mesoporous hollow silica material can be provided.
Thus, the present invention permits the introduction of amine-based functional groups into the mesoporous hollow silica material to significantly increase the adsorption of carbon dioxide over the pure mesoporous hollow silica material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a mesoporous hollow silica material having improved adsorption efficiency of carbon dioxide by introducing an amine functional group into a mesoporous hollow silica material,

The present invention relates to a method for preparing a mesoporous hollow silica material, and more particularly, to a method for preparing a mesoporous silica material which improves the adsorption rate of carbon dioxide by introducing an amine functional group.

Mesoporous materials refer to materials having pore sizes ranging from 2 to 50 nm in the porous material having nanometer-sized pores according to the definition of IUPAC (International Union of Pure and Applied Chemistry). Materials with smaller pores less than 2 nm are referred to as microporous materials, and those with pore sizes greater than 50 nm are classified as macroporous materials.

Porous materials with nanometer-sized pores can be used as a host or chromatographic separation of organic polymers when forming organic / inorganic composites, adsorption of toxic substances in air and water, and morphological selective catalysts of large organic polymers Much research has been done because of potential applicability.

Among them, the mesoporous hollow silica nanomaterial is a composite structure of mesoporous silica and hollow silica, the interior is empty, and the shell silica material is a mesoporous structure. The method of synthesizing mesoporous hollow silica nanomaterials is a method of forming internal core material, coating a surfactant and silica particles thereon, forming a core-shell structure, and then removing the organic material .

In particular, carbon dioxide (C0 ₂₎ In the case of gas absorption, the C0 ₂ gas, as well as the type and the amount of the functional group capable of trapping a structure capable of containing C0 ₂ gas and the specific surface area and a large amount of functional groups that can access important factor . Accordingly, there is a need for a process for synthesizing mesoporous hollow silica materials that have a larger specific surface area and capable of introducing a large amount of functional groups through a hollow structure, and for easily introducing functional groups thereto.

Korean Patent Publication No. 10-2011-0033575 (published on Mar. 31, 2011) Korean Patent Publication No. 10-2011-0085363 (published on July 27, 2011)

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned needs, and it is an object of the present invention to provide a mesoporous hollow silica nanomaterial which is capable of synthesizing a mesoporous hollow silica nanomaterial and introducing an amine- The present invention also provides a method for producing a mesoporous hollow silica material.

To this end, a method for preparing a mesoporous hollow silica material having amine functional groups according to the present invention comprises: (a) adding styrene as a precursor and AIBA as a thermal initiator to a solvent in which distilled water and acetone are mixed at a predetermined ratio, Forming polystyrene as a material; (b) adding polystyrene formed in step (a) to a mixed solution of distilled water and ethanol at a predetermined ratio, adding cetyltrimethylammonium chloride (CTACl) as a cationic surfactant and tetraethylorthosilicate (TEOS) as a precursor, Adding ammonia water to the stirred solution, and then calcining the mixture at a predetermined temperature for a predetermined time to form a mesoporous hollow silica material; And (c) introducing an amine functional group into the mesoporous hollow silica material formed in step (b) by adding a predetermined amine-based precursor through impregnation and stirring the mixture for a predetermined time, followed by drying at a predetermined temperature and at a predetermined temperature can do.

Preferably, in step (a), the distilled water and acetone may be mixed in a volume ratio of 3: 0.5 to 2.

Preferably, 1 to 20 ml of the above-mentioned styrene is added to 1 L of the mixed solvent, and the AIBA is added in accordance with the molar ratio of the styrene to the AIBA, and the molar ratio is styrene: AIBA = 1: 0.1 to 0.3 Lt; / RTI >

Preferably, in step (b), the distilled water and ethanol may be mixed in a volume ratio of 1: 1 to 3: 1.

In step (b), 10 to 50 ml of the CTACl may be added to 1 L of the mixed solvent, and then 10 to 50 ml of the TEOS may be added.

Preferably, in step (b), the ammonia water may be added to adjust the pH to 8-10.

Preferably, the synthesized material is dried at a temperature in the range of 70 to 90 ° C. and in a range of 15 to 24 hours in the pre-stage of the formation of the core material in the step (a) and in the pre-stage of the firing step in the step (b) And a thermal reaction step for heating the reaction mixture.

Preferably, in the step (b), the firing process may be performed at 600 ° C for 5 hours.

Preferably, the amine group precursor in the step (c)

(2-ethylhexyl) amine, ethylamine, hydrzine, (3-methylpentyl) amine, melamine, ethylenediamine, 3,5-diamino-1,2,4-triazole, adenine 5-aminotetrazine, triethylenetetramine, 3pycolylamine, monoethanolamine, 5- (4-carboxybenzoylamino) -isophthalic acid, N, N-diethylaminoethylamine, 3-aminopropyltrimethoxysilane, ethylenediamine, (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, poly- (L-lysine), 1,8-diazabicyclo- [5,4,0] -undec-7-ene, dodecylamine, Bis [(triethoxysilyl) propyl N, N'-N-carboxyanhydride (NCA) of L-amine, 1,2-bis (4-pyridylmethylene) hydrazine , And L-arginine may be selected.

Preferably, in step (c), the amine-based precursor is added in accordance with the weight ratio of the mesoporous hollow silica particulate material formed in step (b), and the weight ratio of the mesoporous hollow silica material: amine-based precursor = 1: 0.1 to 1.5, and by increasing the weight ratio within the above range, the amount of carbon dioxide adsorbed can be increased.

Preferably, the amine-based precursor is added in accordance with the weight ratio of the mesoporous hollow silica particles formed in the step (b), and the mixture is stirred at room temperature for 1 hour.

Preferably, after the stirring, the solvent may be removed through a vacuum concentrator, followed by drying at 80 to 100 ° C for 2 hours.

Preferably, in the step (c), the mesoporous hollow silica material formed in the step (b) is added according to the weight ratio of ethanol, and the weight ratio of the mesoporous hollow silica material: ethanol is 1: 100-150 Lt; / RTI >

Preferably, the pore structure of the mesoporous hollow silica material may form a hexagonal structure.

Conventional mesoporous hollow silica materials are also used as carbon dioxide adsorbents, but they have a disadvantage of low carbon dioxide adsorption performance.

On the other hand, the present invention is advantageous in that the adsorption performance can be increased by introducing amine functional groups chemically adsorbing carbon dioxide into the synthesized mesoporous hollow silica nanomaterial.

1 is a schematic view of a mesoporous hollow silica material according to a preferred embodiment of the present invention,
Figure 2 shows the mechanism of the adsorption of carbon dioxide on the amine functional groups in Figure 1,
FIG. 3 is a flow chart showing a more detailed process for producing a mesoporous hollow silica material into which an amine functional group is introduced according to a preferred embodiment of the present invention.
Figure 4 is a TEM image of a mesoporous hollow silica material according to a preferred embodiment of the present invention,
5 is a graph showing XRD results of a mesoporous hollow silica material according to a preferred embodiment of the present invention,
6 is a graph showing N ₂ -sorption analysis results of pure mesoporous hollow silica nanomaterials,
7 is a graph showing the results of measurement of carbon dioxide adsorption of a mesoporous hollow silica material into which an amine functional group is introduced.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish it, will be described with reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. The embodiments are provided so that those skilled in the art can easily carry out the technical idea of the present invention to those skilled in the art.

In the drawings, embodiments of the present invention are not limited to the specific forms shown and are exaggerated for clarity. Also, the same reference numerals denote the same components throughout the specification.

The singular forms herein include plural forms unless the context clearly dictates otherwise. Also, components, steps, operations and elements referred to in the specification as " comprises "or" comprising " refer to the presence or addition of one or more other components, steps, operations, elements, and / or devices.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing synthesis and amine impregnation of a mesoporous hollow silica material according to a preferred embodiment of the present invention. FIG. 2 is a view showing a mechanism of adsorption of carbon dioxide by amine functional groups in FIG. 1, and FIG. A process for producing mesoporous hollow silica materials into which an amine functional group is introduced according to an exemplary embodiment of the present invention.

1 to 3, a method for preparing a mesoporous hollow silica material having an amine functional group according to the present invention comprises the steps of: (a) mixing a mixture of distilled water and acetone in a predetermined ratio to prepare a precursor, To form polystyrene as a core material; (b) adding polystyrene formed in step (a) to a mixed solution of distilled water and ethanol at a predetermined ratio, adding cetyltrimethylammonium chloride (CTACl) as a cationic surfactant and tetraethylorthosilicate (TEOS) as a precursor, Adding ammonia water to the stirred solution, and then calcining the mixture at a predetermined temperature for a predetermined time to form a mesoporous hollow silica material; And (c) introducing an amine functional group into the mesoporous hollow silica material formed in step (b) by adding a predetermined amine-based precursor through impregnation and stirring the mixture for a predetermined time, followed by drying at a predetermined temperature and at a predetermined temperature can do.

Referring to FIG. 3, the process of synthesizing the mesoporous hollow silica nanomaterial according to a preferred embodiment of the present invention will be described in more detail as follows.

First, in the present invention, as shown in FIG. 3 (a), polystyrene (PS) used as a core material was synthesized to synthesize a mesoporous hollow silica material.

At this time, when the process of synthesizing polystyrene (PS) is described, distilled water (H ₂ O) and acetone are mixed at a volume ratio of 3: 0.5 to 2. To 1 liter of the mixed solvent, 1 to 20 ml of styrene, which is a precursor of polystyrene (PS), and 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AIBA) as a thermal initiator are added and stirred. At this time, the thermal initiator AIBA is added in accordance with the molar ratio of styrene, that is, it is preferable to add it in the range of 1: 0.1 to 0.3 mol of styrene: AIBA. Thus, the structure can be formed into a spherical shape having a uniform size without breaking. Then, the core material, polystyrene (PS), is synthesized by reacting at 70 to 90 ° C, preferably at 80 ° C, for 15 to 24 hours.

Next, referring to FIG. 3 (b), the core material polystyrene is removed to synthesize a mesoporous hollow silica material.

First, H ₂ O and ethanol (EtOH) were mixed at a constant volume ratio. The volume ratio of water to ethanol was 1: 1 to 3, and the mixture was mixed with 1 L of polystyrene PS). Next, 10 to 50 ml of cetyltrimethylammonium chloride (CTACl) as a cationic surfactant is added, and then 10 to 50 ml of tetraethylorthosilicate (TEOS) as a silica precursor is added and stirred. Thus, the structure can be formed into a spherical shape having a uniform size without breaking.

Then, ammonia water (NH ₄ OH) is added to the stirred solution to adjust the pH of the stirred solution to 8 to 10, and then the reaction is carried out at 70 to 90 ° C., preferably at 80 ° C. for 15 to 24 hours, And a core-shell shape in which a silica shell is placed on the core. At this time, TEOS is a silica precursor and forms a shell in polystyrene. CTACl serves as a support for pores formed in the shell, and ammonia water plays a role of controlling the pH of the stirred solution to 8 to 10 . In this case, the CTACl solution and the TEOS solution are added at a volume ratio of 1: 1, and an appropriate amount of ammonia water is added so that the pH of the stirred solution is set to 8 to 10.

The thus synthesized material is subjected to filtration, washing and drying, and then calcined at a high temperature, preferably at 600 ° C., to obtain a synthetic mesoporous hollow silica material (hollow silica spheres). At this time, if the sintering process is performed at a high temperature, the pores formed in the silica shell can be easily penetrated, and as a result, the removal of the internal materials can be facilitated.

Next, referring to FIG. 3C, the process of introducing an amine-based functional group into the mesoporous hollow silica material synthesized through FIG. 3B by impregnation will be described below.

First, referring to FIG. 2, the carbon dioxide adsorption mechanism of the amine-based functional group will be described below. That is, generally synthesized mesoporous hollow silica material is used as a solid adsorbent, but adsorbent alone exhibits low carbon dioxide adsorption performance. Accordingly, in order to overcome such a problem, introduction of an amine-based functional group capable of chemically adsorbing carbon dioxide can increase carbon dioxide adsorption performance.

In the case of the amine-based functional group, as shown in FIG. 2, when carbon dioxide is encountered, carbamate is formed and adsorbed. When water is present, hydrogen carbonate salt is formed to adsorb carbon dioxide. That is, the amine functional group has moisture stability that is pointed out as a disadvantage of conventional MOFs.

Next, the introduction process of the amine-based functional group through impregnation is as follows.

The amine-based functional group is simply impregnated and the mesoporous hollow silica material is dispersed in ethanol at a weight ratio of mesoporous hollow silica material: ethanol = 1: 100-150.

Then, the amine-based precursor is added to the mesoporous hollow silica material at a ratio by mass to mass ratio of mesoporous hollow silica material: amine precursor = 1: 0.1 to 1.5, and the mixture is stirred at room temperature for about 1 hour. After stirring, the ethanol solvent is removed through a vacuum concentrator and dried at 80 to 100 ° C for about 2 hours to obtain an adsorbent material.

Examples of the amine precursor added to the reaction include polyethylenimine, tetraethylenepentamine, 2-methylbutyl amine, Tris (2-ethylhexyl) amine, ethyl amine, hydrzine, (3-methylpentyl) amine, melamine, ethylenediamine, diamino-1,2,4-triazole, adenine, 2-amino-1,4-benzenedicarboxylic acid, isopropanolamine, 3-aminopropyltrimethoxysilane, ethylenediamine, traethylenepentamine, aziridine, 5-aminotetrazine, triethylenetetramine, 3pycolylamine, monoethanolamine, 5- 4-carboxybenzoylamino) -isophthalic acid, N, N'aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, poly- (L-lysine), 1,8-diazabicyclo- [5,4,0] amine, N'N'N'-N-carboxyanhydride (NCA) of L-amine, triethoxysilylpropyl] ethylenediamine, tri- (2-aminoethyl) 1,2-bis (4-pyridylmethylene) hydrazine, L-arginine, and the like. At this time, it is advantageous that the amine functional group is contained in the hollow structure as much as possible, and the present invention uses tetraethylenepentamine.

When the ratio of amine functional groups is more than 1.5, the adsorption efficiency of carbon dioxide is decreased because it blocks the micropores of the mesoporous hollow silica material as the adsorbent. Also, if the ratio is less than 0.1, the amount of amine functional groups in the adsorbent becomes insufficient and the efficiency of carbon dioxide becomes low. Therefore, it is necessary to impregnate the adsorbent and amine functional groups at a suitable mass ratio.

For example, the mesoporous hollow silica material and the amine-based precursor increase the specific surface area of the mesoporous silica material by increasing the weight ratio of the amine-based precursor in the range of 1: 0.1 to 1.5, preferably in the range of 0.5 to 1.5 M . For example, in the case of the mesoporous hollow silica material into which the amine functional group is introduced, the adsorption amount of carbon dioxide is 8.7434 mmol / g, 12.1638 mmol / g, and 11.9824 mmol / g, Performance can be confirmed.

Results analysis

FIGS. 4 and 5 are graphs showing TEM and XRD results of a mesoporous hollow silica material in a preferred embodiment of the present invention. FIG.

FIG. 4 is a TEM photograph of the synthesized mesoporous hollow silica material. TEM images of mesoporous hollow silica nanomaterials show that the inside and the pores are relatively transparent, thereby forming a hollow shape with smooth polystyrene removal .

FIG. 5 is a graph showing the meso pore structure of the synthesized mesoporous hollow silica nanomaterial through low angle XRD. As a result, d (100), which is the main peak of silica, appears at about 2.2 ^o Ordered peaks were observed at around 4.5 ^o , confirming that the pore structure of the shell forming the shell had a hexagonal structure.

In addition, N ₂ -sorption was used to measure the specific surface area and pore size and volume of the mesoporous hollow silica material to which the amine functional group was introduced. From the BET relationship, The surface area is determined, and the size and volume of the pores are obtained from the BJH relation.

FIG. 6 is a graph showing the results of N ₂ -sorption analysis of pure mesoporous hollow silica nanomaterials, and FIG. 7 is a graph showing the measurement results of adsorption of carbon dioxide on the mesoporous hollow silica material into which amine functional groups are introduced.

Referring to FIG. 6, the overall adsorption / desorption curve is of the type IV and the hysteresis loop is of the H2 type. As a result of calculation of the specific surface area of the material through BET, the pure mesoporous hollow silica nanomaterial has a high specific surface area of 1341 m 2 / g, which results in high specific surface area through removal of core and mesoporous organic substances Can be confirmed indirectly. Further, it can be confirmed that the specific surface area is greatly reduced after the amine functional group is supported, which can confirm that the amine functional group is sufficiently immersed in the mesopores.

[Table 1] describes the specific surface area, pore volume, and pore size of the mesoporous hollow silica material and the mesoporous hollow silica material after the amine loading. As the amount of the amine functional group increases, the specific surface area It can be seen that the pore volume is reduced. Here, only the difference in the volume of the pores is shown because the result of the pore size distribution of the BJH method differs only in the pore volume because it neglects micropores, that is, pores having a pore size of 2 nm or less .

Sample name Specific surface area (BET)
(M < 2 > / g) Pore volume
(cc / g) Pore size
(nm) Mesoporous hollow silica
1341 0.450 3.828 Mesoporous hollow silica +
Amine 0.5 98 0.161 3.815 Mesoporous hollow silica + amine 1.0 50 0.104 3.036 Mesoporous hollow silica +
Amine 1.5 24 0.049 3.395

As shown in Table 1, the results of evaluating the carbon dioxide adsorption performance of the mesoporous hollow silica material introduced for each concentration of amine functional groups are shown in Fig. The measurement conditions of the gas flow system are as follows. In other words,

① Test method: Calculate the amount of carbon dioxide adsorbed by GC after collecting gas passing through specimen by flowing standard gas mixed with carbon dioxide

② Test equipment: hp 6890a gc, agilent

③ Gas concentration: N ₂ 70% + CO ₂ 30%

④ Flow rate: 5 ml / min

⑤ Measurement time: 60 min

Referring to Table 1 and FIG. 7, the mesoporous hollow silica having no amine functional group was measured to have an adsorption amount of carbon dioxide of 3.0446 mmol / g, which is a high specific surface area of the adsorbent itself, , The maximum carbon dioxide adsorption performance can be confirmed at 1.0 with increasing concentrations of amine functional groups from 0.5 to 1.0 and 1.5, respectively. The adsorption amounts of carbon dioxide are 8.7434 mmol / g, 12.1638 mmol / g and 11.9824 mmol / The concentration of the amine functional group introduced can be confirmed.

Thus, the present invention is superior to the pure mesoporous hollow silica adsorbent in that the mesoporous hollow silica adsorbent to which the amine functional group is introduced is excellent in adsorption ability.

While the invention has been shown and described with respect to the specific embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Anyone with it will know easily.

Claims (14)

(a) forming polystyrene as a core material by adding styrene as a precursor and AIBA as a thermal initiator to a solvent in which distilled water and acetone are mixed at a predetermined ratio;
(b) adding polystyrene formed in step (a) to a mixed solution of distilled water and ethanol at a predetermined ratio, adding cetyltrimethylammonium chloride (CTACl) as a cationic surfactant and tetraethylorthosilicate (TEOS) as a precursor, Adding ammonia water to the stirred solution, and then calcining the mixture at a predetermined temperature for a predetermined time to form a mesoporous hollow silica material; And
(c) introducing an amine functional group into the mesoporous hollow silica material formed in step (b) by adding a predetermined amine precursor through impregnation, stirring the mixture for a predetermined time, and drying the mesoporous hollow silica material for a predetermined time and at a predetermined temperature; ,
In the step (c)
Tetraethylenepentamine as the amine precursor is added in accordance with the weight ratio of the mesoporous hollow silica particulate material formed in the step (b)
Wherein the weight ratio is in the range of mesoporous hollow silica material: tetraethylenepentamine = 1: 0.5 ~ 1.5, and the weight ratio is increased within the range to increase the amount of carbon dioxide adsorbed. The method according to claim 1,
In the step (a)
Wherein the distilled water and acetone are mixed in a volume ratio of 3: 0.5 to 2. 3. The method of claim 2,
1 to 20 ml of the above-mentioned styrene and AIBA were added to 1 L of the mixed solvent,
The AIBA is added in accordance with the molar ratio of the styrene,
Wherein the molar ratio is in the range of styrene: AIBA = 1: 0.1 to 0.3. The method according to claim 1,
In the step (b)
Wherein the distilled water and ethanol are mixed in a volume ratio of 1: 1 to 3: 1. The method according to claim 1,
In the step (b)
10 to 50 ml of the CTACl is added to 1 L of the mixed solvent, and then 10 to 50 ml of the TEOS is added. The method according to claim 1,
In the step (b)
Wherein the aqueous ammonia solution is added to adjust the pH to 8-10. The method according to claim 1,
In the step (a), the core material, polystyrene, is synthesized by adding the AIBA and drying at a temperature of 70 to 90 ° C and a range of 15 hours to 24 hours to prepare a mesoporous hollow silica material Way. The method according to claim 1,
Wherein the calcining step is performed at 600 ° C for 5 hours in the step (b). The method according to claim 1,
Wherein the amine-based precursor is added in accordance with the weight ratio of the mesoporous hollow silica particulate material formed in the step (b), and the mixture is stirred at room temperature for 1 hour. 10. The method of claim 9,
Wherein the solvent is removed through a vacuum concentrator after the stirring, and then dried at 80 to 100 ° C for 2 hours. The method according to claim 1,
In the step (c)
The mesoporous hollow silica material formed in the step (b) is added according to the weight ratio of ethanol,
Wherein the weight ratio is in the range of mesoporous hollow silica material: ethanol = 1: 100-150. The method according to claim 1,
Wherein the pore structure of the mesoporous hollow silica material forms a hexagonal structure. delete delete

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