KR20160001279A - Hollow porous carbon particles and their synthetic method - Google Patents

Abstract

The present invention relates to hollow and porous carbon particles having low density, large specific surface area, and micro-sized pores. The hollow and porous carbon particles having excellent dispersibility and dispersion stability with great absorption can be widely used for catalysts; adsorbents; sensors; electrode materials; separation and purification material; and hydrogen and drug carriers. In addition, a manufacturing method of the hollow and porous carbon particles according to the present invention has excellent efficiency of processing by manufacturing the carbon particles through a single-step heat treatment of core-shell precursor particles having polymer particles as cores, and metal-organic frameworks as shells.

Description

[0001] Hollow porous carbon particles and their synthetic methods [0002]

More particularly, the present invention relates to a hollow porous carbon particle which has a large surface area, is excellent in dispersion degree and dispersion stability and can be utilized for catalyst, gas storage, separation, and optical use, ≪ / RTI >

Porous carbon particles are attracting attention as interesting materials that can be used in various fields including adsorbents, catalysts, hydrogen storage materials, drug delivery systems, and separation systems.

Conventionally, the use of precursors has been proposed for producing the porous carbon particles. Recently, as a precursor, a method based on metal-organic frameworks (MOFs) has been used to produce porous carbon particles having high surface area and porosity The particles can be efficiently produced and thus attracting much attention.

For example, Korean Patent Registration No. 10-0644501 discloses a method for producing a hollow porous structure (carbon-aluminosilicate composite structure) having a wide specific surface area and multiple pores, There is a problem that the BET surface area is small, the pore size is large, and the manufacturing process is complicated.

In addition, porous carbon is prepared by using MOF-5 as a precursor and heat treatment thereof (Non-Patent Document 1). ZIF-8 particles having mesopores and macropores are ultrasonicated and carbonized to form micro-, mesopores and macropores (Non-Patent Document 2) is known. However, all of these methods relate to methods for producing bulk carbonaceous materials having mesopores, and there is a need to develop hollow carbon particles that are uniform and have good dispersion.

(Non-Patent Document 1) B. Liu, et. al., J. Am. Chem. Soc., 2008, 130, 5390-5391 (Non-Patent Document 2) A. J. Amali, et al., Chem. Commun., 2014, 50, 1519-1522

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method for manufacturing a hollow porous carbon particle by heat treatment under nitrogen of a core-shell type organic-metal skeleton.

The present invention also provides a microporous membrane having micropores having excellent dispersing ability and dispersion stability To provide hollow porous carbon particles.

In order to accomplish the above object, the present invention provides a method for producing hollow porous carbon particles comprising the steps of:

(I) preparing a reaction mixture by mixing a zinc metal and a 2-methylimidazole precursor solution capable of forming an organic-metal skeletal shell in a polymer core particle surface-treated with a carboxyl group,

(II) subjecting the reaction mixture to ultrasonic reaction to produce core-shell precursor particles which form the core of the organic-metal skeleton as a core by using the polymer particles as a core, followed by centrifugation,

III) heat-treating the core-shell precursor particles under nitrogen to prepare hollow porous carbon particles.

According to one embodiment of the present invention, the polymer particles are selected from the group consisting of polystyrene, polyolefin, polyvinyl acetate, polyvinyl alcohol, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polyalkyl (meth) , And the organic-metal skeleton may include a zeolite imidazolate skeleton.

According to one embodiment of the present invention, the step I) to step II) are repeated one to four times or more times, by replacing the polymer particles of the step I) with the core-shell precursor particles of the step II) , Thereby adjusting the thickness of the shell.

Also, the step (III) may be heat treated at 1000 ° C., and the step (I) may be performed through ultrasonic dispersion.

In addition, the present invention relates to a spherical hollow; And a microporous porous shell made of carbon, wherein the shell has a plurality of nanograins bonded to each other to form a porous network.

According to an embodiment of the present invention, the diameter of the hollow porous carbon particles may be 0.7 to 1 占 퐉, the thickness of the shell may be 40 to 150 nm, and the nanograin may have a diameter of 50 to 100 nm .

The hollow porous carbon particles according to the present invention may have a BET surface area of 1100 to 1800 m < 2 > / g.

The hollow porous carbon particles according to the present invention can be used as a medium capable of adsorbing and storing gas. According to an embodiment of the present invention, when the carbon dioxide relative pressure at a temperature of 195 K is less than 1.0 P / P _O < 1.0) The adsorption amount of carbon dioxide may be 310 to 430 cm 3 / g.

The present invention also relates to a gas storage body comprising the hollow porous carbon particles, wherein the gas storage body contains at least one gas selected from hydrogen, nitrogen, oxygen, carbon dioxide, methane, ethane, natural gas, acetic acid, LPG, Wherein the gas storage body is a gas storage body.

The hollow porous carbon particles according to the present invention are characterized by having a low density, a wide specific surface area, and a micro pore. The hollow porous carbon particles according to the present invention are excellent in dispersing ability and dispersion stability and excellent in adsorbing ability and can be used for catalysts, adsorbents, Or as a storage medium for hydrogen and drugs. The method for producing hollow porous carbon particles according to the present invention can be manufactured through a single step heat treatment process using core particles of core-shell precursor particles having a polymer particle as a core and an organo-metallic skeleton as a shell , And the process efficiency is excellent.

FIG. 1 is a view showing a process for producing hollow porous carbon particles according to the present invention.
Fig. 2 (a) shows pure polystyrene particles, Fig. 2 (b) shows the polystyrene @ ZIF-8 precursor particles of Example 1 before heat treatment, Fig. 2 (c) shows hollow porous carbon particles (HPC- FIG. 2E shows the hollow porous carbon particles (HPC-3) prepared from Example 2, FIG. 2F shows the polystyrene @ ZIF-8 precursor particles of Example 3 before the heat treatment And FIG. 2G is a scanning electron microscope (SEM) and a transmission electron microscope (TEM) photograph of the hollow porous carbon particles (HPC-4) prepared in Example 3.
FIG. 3A is a high magnification SEM photograph of HPC-2, FIG. 3B is HPC-3, and FIG. 3C is a high magnification SEM photograph of HPC-4.
4A is a high-resolution TEM image of HPC-2, FIG. 4B is HPC-3, and FIG. 4C is a high resolution TEM image of HPC-4.
FIG. 5 is a graph showing the results of thermogravimetric analysis (TGA) under nitrogen of polystyrene @ ZIF-8, polystyrene particles and ZIF-8 nanoparticles, which are precursor particles of HPC-3.
Fig. 6 is a photograph showing the dispersion stability of HPC-3 and PC-1 immediately after mixing and after being completely precipitated.
FIG. 7A is a cross-sectional view of the polystyrene ZF-8 precursor particle of Example 2, FIG. 7C is a cross-sectional view taken along the line A-A of FIG. FIG. 8B is a graph showing the results of elemental analysis (EDX) of each of HPC-4, wherein the image interpolated in the graph is a transmission electron microscope (STEM) photograph of each sample .
Figure 11 is a known ZIF-8 simulation pattern and a PXRD pattern of polystyrene &lt; RTI ID = 0.0 &gt; @ ZIF-8 &lt; / RTI &gt; precursor particles.
12 is a PXRD pattern of HPC-2, HPC-3 and HPC-4.
Figures 13a-c are Raman spectra for HPC-2, HPC-3 and HPC-4, respectively.
14 is a SEM and TEM photographs of ZIF-8 (a) and PC-1 (b).
15A is the N ₂ adsorptive isotherms of HPC-2, HPC-3, HPC-4 and PC-1 and FIG. 15B is the sorption isotherms of HPC-2, HPC-3, HPC-4 and PC- CO ₂ adsorption / desorption isotherms, and the interpolated graph in FIG. 15A shows the pore size distribution curve of HPC-2.
16A is a graph showing adsorption / separation performance with respect to methylene blue (MB) of PC-1 over time, and HPC-3 and FIG.
16C is a graph and a photograph comparing adsorption / separation performance of MBC of HPC-3 and PC-1 with time.
17A to 17D are graphs showing the pore sizes of the HPC-2, HPC-3, HPC-4 and PC-1 according to the NLDFT (Nonlocal Density Function Theory) method.
18 is a HPC-2, HPC-3, HPC-4 and PC-1 in CO ₂ adsorption-desorption isotherms (sorption isotherms) at 298 K.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for easily and easily producing hollow porous carbon particles using a core-shell type organic-metal skeleton including a polymer core and an organic-metal skeleton formed on the polymer core, .

(I) preparing a reaction mixture by mixing a zinc metal and a 2-methylimidazole precursor solution capable of forming an organic-metal skeletal shell in a polymer core particle surface-treated with a carboxyl group,

(II) subjecting the reaction mixture to ultrasonic reaction to produce core-shell precursor particles which form the core of the organic-metal skeleton as a core by using the polymer particles as a core, followed by centrifugation,

III) heat-treating the core-shell organic-metal skeleton in nitrogen to produce hollow porous carbon particles.

More specifically, first, a reaction mixture is prepared by mixing a zinc metal and a 2-methylimidazole precursor solution capable of forming an organo-metallic skeletal shell in a polymer core particle surface-treated with a carboxyl group, A shell composed of an organic-metal skeleton is grown on the surface of the polymer particle.

The polymer particles may be selected from the group consisting of polystyrene, polyolefin, polyvinyl acetate, polyvinyl alcohol, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polyalkyl (meth) acrylate and copolymers thereof It may be at least one selected.

The organic-metal skeleton may include at least one selected from the group consisting of zinc, cobalt, manganese, magnesium, iron, copper, aluminum and chromium.

Although the organic-metal skeleton is not limited to the zeolite imidazolyl skeleton, the zeolite imidazolate skeleton preferably contains zinc, and ZIF-8 is used in the embodiment of the present invention.

The organic solution may optionally be polar or nonpolar. N-alkanes such as pentane, hexane, benzene, toluene, xylene, chlorobenzene, nitrobenzene, cyanobenzene, aniline, naphthalene, naphtha, n-alcohols such as methanol, ethanol, n-propanol, isopropanol , Acetone, 1,3-dichloroethane, dichloromethane, methylene chloride, chloroform, carbon tetrachloride, tetrahydrofuran, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, dimethylacetamide, diethylformamide, thiophene , Pyridine, ethanolamine, triethylamine, ethylenediamine, ethylether, acetonitrile, dimethylsulfoxide, and the like. That is, the solvent can be easily determined based on the starting reactants.

In order to uniformly grow the organic-metal skeleton on the polymer particle core, the step (I) is most preferably carried out at 70 ° C. This process is also carried out for 15 minutes.

In addition, the step (I) may be performed using ultrasound dispersion to thoroughly mix all the components, and the polymer particles are used as a core to form the organo-metallic skeleton as a shell through an ultrasonic reaction to form core- .

The reaction mixture is then centrifuged to obtain the core-shell precursor particles produced in the process. This process separates the core-shell precursor particles desired in the present invention from by-products of the pure nano-sized organo-metallic skeleton by the density difference. At this time, the core-shell precursor particles are characterized by using the polymer particles as a core and the organo-metallic skeleton as a shell.

Typically, the secondary growth and the tertiary growth of the organic-metal skeleton on the existing organic-metal skeleton as well as the primary growth of the organic-metal skeleton on the surface of the polymer particle are accompanied by the formation of carboxylate groups and metal ions &Lt; / RTI &gt;

The metal-ligand coordination interaction across the particle surface induces uniform growth of the organo-metallic skeleton and leads to the formation of a uniform organic-metal skeleton layer on the core surface.

The step of repeating the above steps (I) to (II) by replacing the polymer particles of the step (I) with the core-shell organic-metal skeleton of the step (II) is repeated one to four times to form the core- The thickness of the shell of the metal skeleton can be increased. In other words, the thickness of the shell can be controlled to be about 75 to 270 nm by controlling the number of repetitions of the above steps.

Finally, the core-shell precursor particles are heat-treated under nitrogen to produce hollow porous carbon particles. More specifically, the core-shell precursor particles are heat-treated at a temperature of 1000 ° C to remove polymer core particles from the core-shell precursor particles, and the organic-metal skeleton is converted into a carbon material to form a hollow structure Porous carbon particles can be produced.

This process is a single step heat treatment process, and the atmosphere in which the heat treatment is performed is preferably a nitrogen gas.

The heat treatment step is performed at a temperature of 1000 ° C. If the heat treatment temperature is lower than 1000 ° C, zinc metal as an organic-metal skeleton is detected in a considerable amount. If the temperature exceeds 1000 ° C., the core-shell precursor particles may be excessively fired and the structure may be deformed or damaged.

The method of producing hollow porous carbon particles according to the present invention can easily and easily produce hollow porous carbon particles having a complicated structure through well-designed core-shell particles as a precursor material through a single step heat treatment process. In addition, the thickness of the shell of the core-shell particles, that is, the shell thickness of the hollow porous carbon particles, can be controlled by controlling the repetition frequency of the organic-metal skeletal growth process in the above-described manufacturing method.

The hollow porous carbon particles prepared by the above-described method are synthesized to have a uniform particle diameter and a shell thickness, and have a large surface area and excellent porosity, as well as gases such as carbon dioxide and nitrogen and organic substances such as methylene blue The adsorption capacity of the adsorbent is excellent.

Another aspect of the present invention is to provide a porous porous carbon nanotube having a microporous porous shell of spherical hollow and carbon, wherein the nanoparticles are bonded to each other to form a porous network. Particle.

At this time, the diameter of the nano-grains may be 50 to 100 nm, and the diameter of the hollow porous carbon particles may be uniformly set to 0.7 to 1 占 퐉.

Also, the thickness of the shell may be 40 to 150 nm, which can be controlled by adjusting the number of repetitions of the growth process, that is, the shell thickness of the core-shell precursor particles in the manufacturing process.

In addition, the micro pore diameter of the shell is 0.6 to 1.2 nm and is well dispersed in the shell, which is significantly smaller than that of conventional hollow porous carbon particles having mesopores or macropores. The hollow porous carbon particles have micropores, so that carbon dioxide or nitrogen such as nitrogen and organic materials such as methylene blue can be adsorbed in a short time.

The hollow porous carbon particles may be in the range of 1100 to 1800 m &lt; 2 &gt; / g, which is a relatively high value of the BET surface area, by maintaining the dispersed state without agglomeration or bonding among the particles in solution.

In addition, the hollow porous carbon particles have a considerably high surface-to-volume ratio with respect to volume. Due to the above-mentioned characteristics, the hollow porous carbon particles have an adsorption amount of carbon dioxide of 310 to 430 cm 3 / g when the carbon dioxide relative pressure is less than 1.0 at a temperature of 195 K (P / PO <1.0).

In addition, the hollow porous carbon particles have a wide surface area, a low density, a long dispersibility in a solution for a long time, and a small pore size and a uniform pore size. Therefore, It is also excellent in adsorbability against organic materials.

Accordingly, the hollow porous carbon particles according to the present invention can be utilized in various applications such as adsorbents, drug carriers, and catalysts.

Particularly, the hollow porous carbon particles according to the present invention can store or adsorb at least one gas selected from hydrogen, nitrogen, oxygen, carbon dioxide, methane, ethane, natural gas, acetic acid, LPG, It can be applied as sieve.

Hereinafter, the present invention will be described in more detail with reference to examples, but the scope and content of the present invention can not be construed to be limited or limited by the following examples and the like. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It would be natural to belong to the scope of the right.

Example  One

A ZIF-8 precursor solution was prepared by dissolving 664 mg (8.1 mmol) of 2-methylimidazole and 240 mg (0.81 mmol) of Zn (NO ₃ ) ₂ .6H ₂ O in 32 mL of methanol.

120 mg of carbocylic acid-terminated silica surface-treated with a carboxyl group and the ZIF-8 precursor solution were mixed in an oil bath at 70 ° C and reacted using an ultrasonic disperser for 15 minutes.

Then, the polystyrene @ ZIF-8 core-shell precursor particles precipitated by centrifugal separation were washed several times with methanol through re-dispersion and centrifugation cycles. In the final step, pure nano-sized ZIF-8 particles Lt; RTI ID = 0.0 &gt; ZIF-8 &lt; / RTI &gt; core-shell precursor particles. The growth process was repeated twice.

As a final step, polystyrene @ ZIF-8 core-shell precursor particles were heat-treated in a tube furnace at 1000 DEG C for 5 hours under a nitrogen atmosphere to prepare hollow porous carbon particles (hereinafter also referred to as HPC-2). At this time, the temperature was raised at a rate of 5 DEG C / min.

Example  2. HPC -3

Hollow porous carbon particles (hereinafter also referred to as HPC-3) were prepared in the same manner as in Example 1, except that the growth process was repeated three times.

Example  3. HPC -4

Hollow porous carbon particles (hereinafter, also referred to as HPC-4) were prepared in the same manner as in Example 1, except that the growth process was repeated four times.

Comparative Example  One. PC -One

Porous carbon particles were prepared by heat treating ZIF-8 precursor particles, which are not polystyrene @ ZIF-8 core-shell precursors, as in the examples according to the present invention (hereinafter also referred to as PC-1).

Comparative Example  2. HPC -2/800

Hollow porous carbon particles were prepared in the same manner as in Example 1 except that the particles were heat-treated at 800 ° C (hereinafter also referred to as 'HPC-2/800').

Comparative Example  3. HPC -2/900

Hollow porous carbon particles were prepared in the same manner as in Example 1 except that the particles were heat-treated at 900 ° C (hereinafter also referred to as 'HPC-2/900').

FIG. 2 (c) shows the polystyrene @ ZIF-8 precursor particles of Example 1 before heat treatment, FIG. 2 (c) shows HPC-2 prepared from Example 1, ZF-8 precursor particles, FIG. 2E shows HPC-3 prepared from Example 2, FIG. 2F shows polystyrene @ ZIF-8 precursor particles of Example 3 before heat treatment, FIG. 2G shows HPC-4 prepared from Example 3 (SEM) and transmission electron microscope (TEM) photographs, respectively.

As shown in Figs. 2A to 2G, HPC-2, HPC-3 and HPC-4 were all spherical in shape, highly uniformly dispersed, and uniform particle diameter and shell thickness were produced.

Further, the present invention is characterized in that the polystyrene core particles are removed from the precursor particles by heat treatment of the polystyrene @ ZIF-8 precursor particles at a high temperature (1000 캜), and the ZIF-8 shell is converted into a carbon material, . It can be seen from this spherical precursor particles that spherical hollow porous carbon particles are produced without any structural deformation, breakage and loss, despite the high temperature heat treatment process.

In addition, HPC-2, HPC-3 and HPC-4 increased in diameter as the number of repetition of the growth process was increased to 0.72 ± 0.01, 0.82 ± 0.01 and 0.97 ± 0.02 μm, respectively.

On the contrary, the diameters of the polystyrene @ ZIF-8 core-shell precursor particles of Examples 1, 2 and 3 before heat treatment were 1.04, 1.20 and 1.43 μm, respectively, which were smaller than HPC-2, HPC-3 and HPC- It was big. This shows that the heat treatment shrinks the particles.

The shell thicknesses of HPC-2, HPC-3 and HPC-4 were 49 ± 6, 92 ± 8 and 144 ± 9 nm, respectively, and the polystyrene @ ZIF-8 core- It can be confirmed that the shell precursor particle has a shell thickness of about 60%.

3C is a high-magnification SEM photograph of each of the HPC-2, HPC-3 and HPC-4 shells, respectively. FIG. Nm or less).

4A is a high-resolution TEM image of each of HPC-2, HPC-3, and HPC-4. FIG. 4C is a high-resolution TEM image of each of the HPC-2, HPC-3 and HPC-4 shells. Respectively.

From the above results, when the carbon material is prepared through the step of heat treating the precursor of the macro-sized organo-metallic skeleton, the precursor is shrunk unevenly and a large number of cracks are present on the surface of the carbon material.

On the other hand, even when the hollow porous carbon particles (HPC-2, HPC-3 and HPC-4) according to the present invention are produced through a heat treatment at a high temperature, the polystyrene @ ZIF-8 precursor particles of the core- So that it is manufactured without cracking, destruction and damage. This is because in the polystyrene @ ZIF-8 precursor particles of Examples 1, 2 and 3, the ZIF-8 shell has a very thin thickness of about 75-270 nm, so that in the heat treatment process, It is because.

FIG. 5 is a graph showing the results of thermogravimetric analysis (TGA) under nitrogen of polystyrene @ ZIF-8, polystyrene particles and ZIF-8 nanoparticles, which are precursor particles of HPC-3.

According to Fig. 5, first, the polystyrene particles started to decompose at 320 ° C and completely disappeared at 440 ° C. On the other hand, the ZIF-8 nanoparticles started to decompose at 440 ° C., and a large amount of loss occurred up to 740 ° C.

Comparing the results of these tests with those of HPC-3, the precursor particle of HPC-3, polystyrene @ ZIF-8, began to show loss at about 300 ° C, which is the temperature at which polystyrene particles began to decompose. The second loss occurs at 440 ° C, the temperature at which ZIF-8 is lost and the temperature at which the polystyrene particles are completely decomposed. Finally, a loss of up to 740 ° C occurs and is introduced in a stable state, which is the temperature at which ZIF-8 nanoparticles are converted to carbon materials and stabilized.

FIG. 6 is a photograph of HPC-3 and PC-1 photographed immediately after mixing and after complete precipitation to confirm the dispersion stability. HPC-3 has low density and does not aggregate well, It was confirmed that they were evenly dispersed in the solution phase. On the other hand, PC-1 did not disperse well in the solution immediately after mixing but precipitated by coagulation. However, all of the PC-1 flocculated and precipitated in about 2 minutes, and the solution became transparent.

FIG. 7A is a cross-sectional view of the polystyrene ZF-8 precursor particle of Example 2, FIG. 7C is a cross-sectional view taken along the line A-A of FIG. 8B is a graph showing the results of elemental analysis (EDX) of each of HPC-4. Here, the image interpolated in the graph is a transmission scanning electron microscope photograph of each sample.

As shown in FIGS. 7 and 8, significant amounts of carbon atoms were detected in the central portion of the polystyrene @ ZIF-8 precursor particles of Examples 1, 2 and 3 due to the presence of polystyrene located in the core portion.

On the other hand, HPC-2, HPC-3 and HPC-4 contained a significant amount of carbon atoms at both ends. This is because the polystyrene located at the center of the HPC-2, HPC-3 and HPC-4 was removed through heat treatment and the ZIF-8 shell portion was converted to a carbon material.

Zinc metal was found in the polystyrene @ ZIF-8 precursor particles of Examples 1, 2 and 3, but hardly was found in HPC-2, HPC-3 and HPC-4. This demonstrates that the ZIF-8 shell is converted to carbon material during the heat treatment process.

Although HPC-2, HPC-3 and HPC-4, which were heat-treated at a high temperature of 1000 ° C, although not shown, hardly detected zinc metal, HPC-2/800, HPC At -2/900, a significant zinc metal of about 13, 10 wt% was detected.

FIG. 10 is a spectrum of HPC-3 measured by X-ray photoelectron spectroscopy (XPS). According to this spectrum, 398.6 (pyridinic N), 401.0 (quaternary N) and 403.6 eV (N-oxides) A peak was observed, indicating that 3.7% (atomic%) of nitrogen was present in HPC-3.

FIG. 11 shows the ZIF-8 simulation pattern and the PXRD pattern of polystyrene @ ZIF-8 precursor particles, and FIG. 12 shows the PXRD pattern of HPC-2, HPC-3 and HPC-4. 11A is a ZIF-8 particle, FIG. 12A is a HPC-2, FIG. 12B is a HPC-3, FIG. 11C is a HPC- 4.

As shown in FIGS. 11 and 12, peaks observed in the PXRD pattern of ZIF-8 particles and polystyrene @ ZIF-8 precursor particles were not observed in the PXRD patterns of HPC-2, HPC-3 and HPC-4. Instead, in the PXRD patterns of HPC-2, HPC-3 and HPC-4, a peak was observed at 2? = 24 and 44 °, which means graphite carbon. This demonstrates that ZIF-8 having a crystallized structure in the heat treatment process is converted into a porous carbon material.

Figure 13a to c is a Raman spectra (raman spectra) for HPC-2, 3-HPC, and HPC-4, respectively in order, Accordingly, HPC-2 was a 1587 ㎝ ^-1 G band showing a graphite sheet (sheet) And a D band due to defect of carbon material was observed at 1349 cm ^-1 .

FIG. 14 is a SEM and TEM image of ZIF-8 (a) and PC-1 (b), showing that PC-1 (b) obtained by thermally treating ZIF-8 nanoparticles (a) And it can be confirmed that they are flocculated.

Figure 15A shows the N ₂ adsorption / desorption isotherms of HPC-2, HPC-3, HPC-4 and PC-1 and Figure 15B shows the adsorption isotherms of HPC-2, HPC-3, HPC- (Sorption isotherms) of CO ₂ adsorption and desorption are shown in Table 1. At this time, the graph interpolated in FIG. 15A shows the pore size distribution curve of HPC-2.

15A was measured at 77 K, and FIG. 15B was measured at 195 K. The full figure as shown in FIG. 15A means adsorption, and the open figure as in FIG. 15B means desorption.

BET surface area
(M &lt; 2 &gt; / g) Micropore
volume t-plot
(Cm3 / g) Micropore
volume
NLDFTa
(Cm3 / g) Micropore
diameter
NLDFTa
(Nm) CO2
uptake
(Cm3 / g) Example 1
(HPC-2) 1724 0.63 0.66 0.60 431 Example 2
(HPC-3) 1469 0.56 0.57 0.65 364 Example 3
(HPC-4) 1254 0.48 0.53 0.60 313 Comparative Example 1
(PC-1) 1086 0.35 0.40 0.60 308

As shown in Fig. 15 and Table 1, the adsorption / desorption amounts of HPC-2, HPC-3 and HPC-4 increased steadily at a nitrogen / carbon dioxide relative pressure of less than 0.1 (P / Po <0.1). These results demonstrate the presence of micropores in the HPC-2, HPC-3, and HPC-4 shells.

In particular, it was confirmed that HPC-2, HPC-3 and HPC-4 had a significantly higher BET surface area than PC-1. As shown in FIG. 14B, PC-1 rapidly aggregates, while HPC-2, HPC-3 and HPC-4 do not aggregate and are uniformly dispersed in solution for a long period of time It is because it exists.

Since PC-1 forms agglomerates rapidly at the stage of heat treatment of nano-sized ZIF-8 particles, it has macropores, which can be deduced from the result that the adsorption / desorption curve rapidly increases at high pressure.

The BET surface area is preferably N ₂ It is calculated from the absorption and desorption isotherm curves. HPC-2 had the largest BET surface area of 1724 m 2 / g since the shell was thin and had a high surface-to-volume ratio to volume. It is clear that the above values are considerably high considering that the BET surface area of non-hollow carbon particles prepared from bulk ZIF-8 is 822 m 2 / g.

On the other hand, HPC-3 and HPC-4 were calculated to be 1469 m 2 / g and 1254 m 2 / g, indicating that the specific surface area decreases as the shell thickness increases.

Separation of Organic Substances (Contaminants) of Hollow Porous Carbon Particles According to the Present Invention in an Aqueous Solution In order to confirm the adsorption ability of organic porous materials (contaminants) in an aqueous solution, an aqueous solution containing methylene blue (hereinafter also referred to as "MB" The samples (HPC-3 and PC-1) were mixed with each other and then UV-vis spectra were measured at various times, as shown in FIG.

FIG. 16A is a graph showing the adsorption / separation performance of HPC-3 and PC-1 with respect to time, and FIG.

PC-1 was not observed after 120 minutes of adsorption equilibrium, but HPC-3 adsorbed to MB was about 2 to 6 minutes, which was remarkably faster than that of Comparative Example 1.

In particular, as shown in Fig. 16C, HPC-3 observed that MB was adsorbed and separated in about 2-6 minutes unlike PC-1. That is, it can be seen that HPC-3 quickly and effectively adsorbs and separates specific substances from a solution, and this adsorption / separation ability is attributable to excellent dispersibility and dispersion stability of HPC-3.

17A to 17D are graphs showing the pore sizes of the HPC-2, HPC-3, HPC-4 and PC-1 according to the NLDFT (Nonlocal Density Function Theory) method.

As shown in FIG. 17, micropores having sizes of 0.6 and 1.2 nm exist in the HPC-2, HPC-3, HPC-4 and PC-1.

Figure 18 is the CO ₂ adsorption / desorption isotherms of HPC-2, HPC-3, HPC-4 and PC-1 at 298K.

Comparing FIG. 18 and FIG. 15B, the adsorption amounts of HPC-2, HPC-3 and HPC-4 were measured at maximum 431, 364 and 313 cm 3 / g respectively at FIG. 15B, ) Were decreased to 104, 98 and 91 cm3 / g, respectively.

Claims (10)

(I) preparing a reaction mixture by mixing a zinc metal and a 2-methylimidazole precursor solution capable of forming an organic-metal skeletal shell in a polymer core particle surface-treated with a carboxyl group;
II) subjecting the reaction mixture to an ultrasonic reaction to produce core-shell precursor particles, which are obtained by core-shell precursor particles comprising the polymer particles as a core and forming the organo-metallic skeleton as a shell, followed by centrifugation; And
III) heat-treating the core-shell precursor particles under nitrogen to produce hollow porous carbon particles. The method according to claim 1,
Wherein the polymer particles are selected from the group consisting of polystyrene, polyolefin, polyvinyl acetate, polyvinyl alcohol, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polyalkyl (meth) acrylate, and copolymers thereof Wherein the hollow porous carbon particles are at least one kind of hollow porous carbon particles. The method according to claim 1,
Wherein the organic-metal skeleton comprises a zeolite imidazolate skeleton. The method according to claim 1,
The step of performing the steps I) to II) is repeated one to four times by replacing the polymer particles of the step I) with the core-shell precursor particles of the step II)
Wherein the thickness of the shell is adjusted in the core-shell precursor particles. The method according to claim 1,
Wherein the step (I) is carried out by mixing and reacting by ultrasonic dispersion, and the step (III) is carried out at 1000 ° C. Spherical hollow; And a microporous porous shell made of carbon,
Wherein the shell has a plurality of nanograins bonded to each other to form a porous network. The method according to claim 6,
The hollow porous carbon particles have a diameter of 0.7 to 1 탆, a shell thickness of 40 to 150 nm, a diameter of the micropores of 0.6 to 1.2 nm, and a diameter of the nanograins of 50 to 100 nm Characterized by hollow porous carbon particles. The method according to claim 6,
Wherein the hollow porous carbon particles have a BET surface area of 1100 to 1800 m &lt; 2 &gt; / g. The method according to claim 6,
Wherein the hollow porous carbon particles have an adsorption amount of carbon dioxide of 310 to 430 cm 3 / g when the relative carbon dioxide is less than 1.0 (P / P _O < 1.0). A gas storage body comprising the hollow porous carbon particles according to any one of claims 6 to 9,
Wherein the gas storage body stores at least one gas selected from hydrogen, nitrogen, oxygen, carbon dioxide, methane, ethane, natural gas, acetic acid, LPG or a mixture thereof.

Images