KR101358655B1 - Hybrid nanocomposite having excellent capacity for hydrogen storage and method for preparing the same - Google Patents

Abstract

The present invention relates to a hybrid nanocomposite having a hydrogen storage capacity and a method for manufacturing the same, more specifically, a metal-organic skeleton; And it relates to a hybrid nanocomposite having a hydrogen storage capacity including magnesium nanocrystals (embedded) in the metal-organic skeleton and a method of manufacturing the same.
The hybrid nanocomposites according to the present invention have excellent physical adsorption and chemical adsorption properties for hydrogen gas and thus have excellent physical properties for use as hydrogen storage and transport media, thus providing a basis for the development of future energy storage media. .

Description

Hybrid nanocomposite having excellent capacity for hydrogen storage and method for preparing the same}

The present invention relates to a metal-organic and magnesium-based hybrid nanocomposite having a hydrogen storage capacity and a method of manufacturing the same.

Hydrogen is a material of great interest as a future energy storage medium, and in order to use hydrogen as a fuel, a hydrogen storage system having high density, high safety, and high efficiency characteristics must be developed. Recently, porous metal-organic frameworks (MOFs) have received great attention as potential hydrogen storage materials (Suh, MP, Park, HJ, Prasad, TK & Lim, D.-W. Hydrogen storage). ... in metal organic frameworks Chem Rev in press (doi: 10.1021 / cr200274s) reference, etc.), since some of MOF can store hydrogen (> 7 wt%) of the mass at 77K and high pressure (Furukawa, H. et al . Ultrahigh porosity in metal-organic frameworks. Science 329 , 424-428 (2010) et al.).

At room temperature, the hydrogen storage capacity of the MOFs is reduced to less than 1 wt%, because the interaction energy between the framework and hydrogen is very low (4-8 kJ mol ⁻¹ ). Thus, various efforts have been made to improve the hydrogen storage capacity of MOFs at ambient temperature, for example, tuning ligands (Wang, Z., Tanabe, KK, & Cohen, SM Tuning hydrogen sorption properties). of metal-organic frameworks by postsynthetic covalent modification. Chem .- Eur. J. 16, 212-217 (2010)), or to create an open metal sites (Lee, Y. -G., Moon , HR, Cheon, YE, & Suh, MP Comparison of H ₂ sorption capacities for isostructural MOFs without and with accessible metal sites: [Zn ₂ (ABTC) (DMF) ₂ ] ₃ and [Cu ₂ (ABTC) (DMF) ₂ ] ₃ vs. [Cu ₂ (ABTC)] _3. Angew . Chem . Int . Ed . 47 , 7741-7745 (2008)), a method of embedding palladium nanoparticles (Cheon, YE & Suh, MP Enhanced hydrogen storage by palladium nanoparticles fabricated in a redox-active metal-organic framework . Angew. Chem. Int. Ed. 48, has been developed, such as the bar 2899-2903 (2009)). Despite these modifications, previously developed methods are not very satisfactory, and none of the materials developed meets the 2015 baseline set by the US Department of Energy.

Recently, as a high-efficiency material for hydrogen storage, research on magnesium is active. Magnesium is hydrogen at 773 K and 200 atm, in the presence of a catalyst MgI _2, a chemically adsorbed (Wiberg, E., Goeltzer, H., & Bauer, R. Synthesis of magnesium hydride from the elements. Z Naturforsch. 6b , 394-395 (1951). Prepared by ball milling 50 - 100 ㎛ size of the magnesium powder it is slowly absorbed hydrogen at 673 K and 10 bar (Zaluska, A., Zaluski , L. & Strom-Olsen, JO Nanocrystalline magnesium for hydrogen storage J Alloys. Compd . 288 , 217-225 (1999).

Because magnesium hydride has a very high dehydrogenation enthalpy (~ 75 kJ per mol H ₂ ), heavy metal catalysts are commonly used to store hydrogen in magnesium, reducing the H ₂ desorption temperature and improving the reaction rate. Heavy metal catalysts also do not cause effective dehydrogenation (Bobeta, J.-L. et. al . Hydrogen sorption properties of the nanocomposites Mg-Mg ₂ Ni _{1 - x} Fe _x . J Alloys Compd . 345 , 280-285 (2002)). In addition, as the particle size of magnesium decreases, hydrogen adsorption and separation temperatures decrease due to destabilization of the metal hydride, but heavy metal catalysts are still required for faster H ₂ dissociation (Berube, V., Radtke, G). ., Dresselhaus, M. & Chen, G. Size effects on the hydrogen storage properties of nanostructured metal hydrides:.... a review Int J. Energy Res 31, 637-663 (2007)).

Conventionally, nano-sized magnesium particles have been prepared by various methods, for example ball-milling (Aguey-Zinsou, K.-F., Fernandez, JRA, Klassen, T. & Bormann, R. Effect of Nb _{2 O 5 on MgH 2 properties during} mechanical milling. Int. J. Hydrogen Energy . 32 , 2400-2407 (2007)), Condensation of Magnesium Metal Vapor (Li, W., Li, C., Ma, H. & Chen, J. Magnesium nanowires: enhanced kinetics for hydrogen absorption and desorption. J. Am . Chem . Soc . 129 , 6710-6711 (2007)), plasma metal reactions (Zhang, X. et. al . Synthesis of magnesium nanoparticles with superior hydrogen storage properties by acetylene plasma metal reaction. Int. J. Hydrogen . Energy 36 , 4967-4975 (2011)), Penetration of Molten Magnesium in Carbon Materials (de Jongh, PE et al . The preparation of carbon-supported magnesium nanoparticles using melt infiltration Chem . Mater . 19, 6052-6057 (2007)), ultrasound electrochemical methods (sonoelectrochemistry) (Haas, I. & Gedanken, A. Synthesis of metallic magnesium nanoparticles by sonoelectrochemistry. Chem. Commun. 1795-1797 (2008)) or a precursor of magnesium Chemical reduction (Jeon, K.-J. et al . Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts. Nature Materials 10 , 286-290 (2011)) have been tried.

However, these methods require long processing times, extremely high temperatures (898-1203 K), and produce products with non-uniform size distributions, even under harsh electrical or chemical conditions. Has

The present invention provides a hybrid nanocomposite having both physical adsorption and chemical adsorption properties for hydrogen, and a method of manufacturing the same, by preparing magnesium nanocrystals in hexagonal-disc form in a metal-organic skeleton to solve the problems of the prior art. do.

In order to achieve the first object of the present invention,

Metal-organic backbones; And

It provides a hybrid nanocomposite having a hydrogen storage capacity including magnesium nanocrystals embedded in the metal-organic backbone.

According to an embodiment of the present invention, the metal-organic skeleton may be Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ .

According to another embodiment of the present invention, the metal-organic skeleton has a non-interpenetrated (6,3) -connected net of a qom topology. Can be.

According to another embodiment of the present invention, the content of the magnesium nanocrystals may be 1.2% by weight to 10.5% by weight based on the total weight of the hybrid nanocomposite.

According to another embodiment of the present invention, the magnesium nanocrystals may have a hexagonal disk shape.

According to another embodiment of the present invention, the diagonal length of the hexagonal disk may be 44 nm to 88 nm, the thickness may be 16 to 61 nm.

According to another embodiment of the invention, the fast Fourier transform (fast Fourier transform) pattern for the magnesium nanocrystals may be a grid pattern having a separation distance of 2.805Å.

In order to achieve the second object of the present invention,

1) A mixture of Zn (NO ₃ ) ₂ and aniline-2,4,6-tribenzoic acid was heated in DMF to give [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] .22DMF.9H ₂ Preparing O;

2) The [Zn ₄ O (aniline-2,4,6-benzoate) _2], by activating, using the 22DMF · 9H ₂ O supercritical CO ₂ Zn ₄ O (2,4,6 aniline Preparing tribenzoate) ₂ ;

3) chemical vapor deposition of bis (cyclopentadienyl) magnesium on Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ;

4) pyrolysing the vapor deposited bis (cyclopentadienyl) magnesium; And

5) It provides a method for producing a hybrid nanocomposite having a hydrogen storage capacity comprising the step of removing the organic decomposition products generated from the pyrolysis step.

According to one embodiment of the invention, the step 1) may be performed for 24 to 48 hours at a temperature of 80 ℃ to 100 ℃.

In further embodiments, the 1) Zn (from Step NO _{3) 2} and the reaction weight ratio of aniline-2,4,6-benzoic acid is Zn (NO _{3) 2} per 100 parts by weight of aniline-2, 30 to 50 parts by weight of 4,6-tribenzoic acid can be reacted.

According to another embodiment of the present invention, step 2) may be performed under a pressure of 73 bar to 200 bar and a temperature condition of 31.1 ° C. to 50 ° C.

According to another embodiment of the present invention, the step 3) may be performed for 1 day to 3 days at a temperature of 80 ℃ to 100 ℃.

According to another embodiment of the invention, the step 3) is to make the reaction vessel pre-vacuum state before performing the step 3), and then for 3 to 5 hours at a temperature of 80 ℃ to 100 ℃ Can be performed.

According to another embodiment of the present invention, step 4) may be performed by immersing the reaction vessel in an oil bath maintained at 180 ° C to 200 ° C for 3 to 24 hours.

The hybrid nanocomposites according to the present invention have excellent physical adsorption and chemical adsorption properties for hydrogen gas and thus have excellent physical properties for use as hydrogen storage and transport media, thus providing a basis for the development of future energy storage media. .

Figure 1a is prepared according to the present invention [Zn ₄ O (aniline-2,4,6-benzoate) _2] · 22DMF · gamyeo Rate by the X- ray crystal structure of the calcium 9H ₂ O green ORTEP 1B is a 3D skeletal structure diagram thereof.
2a is produced according to the present invention [Zn ₄ O (aniline-2,4,6-benzoate) _2] · 22DMF · a TGA / DSC trace graph for 9H ₂ O, Figure 2b The supercritical against TGA data graph for [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] obtained after CO ₂ treatment.
3A to 3C are ¹ H NMR graphs of materials synthesized according to Preparation Examples 4.1 to 4.3.
4A to 4C are HRTEM image photographs of the material synthesized according to Preparation Example 4.3, and FIGS. 4D and 4E are fast Fourier transform patterns thereof.
5a to 5d are HRTEM images of materials synthesized according to Preparations 4.1 to 4.3 (5a: Preparation 4.1; 5b: Preparation 4.2; 5c and 5d: Preparation 4.3), and FIGS. 5e and 5f are respectively Figure 5g is a graph showing the size distribution and thickness distribution of magnesium nanocrystals for the materials, Figure 5g is a HRTEM image of the magnesium nanocrystals present in the material prepared from Preparation Example 4.2. 5H is EDS data for the material prepared from Preparation Example 4.2, and FIG. 5I is EDS data for the material prepared from Preparation Example 4.3.
6A (TEM image), and 6b to 6d (image for morphologically reconstituted magnesium nanocrystals at different angles) are TEM and electronic morphological images of the material prepared from Preparation Example 4.2.
7A-7D are graphs showing X-ray photoelectron spectrum (XPS) results for materials prepared from Preparation Example 4.3 (7a (peak for Zn); 7b (peak for Mg); 7c (peak for carbon); 7d (peak for oxygen)).
8 is a powder X-ray diffraction pattern for various materials in accordance with the present invention.
9A-9D are N ₂ gas sorption isotherms for Preparation 3, and materials prepared according to Preparation 4.1-4.3.
10A and 10B are high pressure H ₂ gas sorption isotherms for materials prepared according to Preparation 3 and Preparation 4.1, at 77K (10a) and 298K (10b).
FIG. 11 is a graph showing the heat of adsorption of equivalent adsorption on H ₂ physical adsorption of materials prepared according to Preparation Example 3 and Preparation Examples 4.1 to 4.3.
12A (physical sorption), FIG. 12B (chemical adsorption) and FIG. 12C (temperature programmed desorption mass spectroscopy) are H ₂ gas adsorption isotherms for materials prepared according to Preparation Examples 3, 4.2 and 4.3 .
FIG. 13A is temperature programmed desorption mass spectroscopy data for materials prepared from Preparation Example 4.3, and FIG. 13B compares the strength for hydrogen atoms and hydrogen molecules.
14 is a graph depicting TGA data of materials prepared from Preparation Example 4.3 before and after chemical adsorption of H ₂ gas.
FIG. 15A is an HPTEM image of a material prepared from Preparation Example 4.3 with hydrogen gas adsorbed, FIG. 15B is an HRTEM image showing hexagonal MgH ₂ nanocrystals supported on Zn ₄ O (atb) ₂ , and FIG. 15C Is a fast Fourier transform pattern for MgH ₂ nanocrystals.
FIG. 16A is a size distribution graph for MgH ₂ nanocrystals formed from H ₂ adsorption for materials according to the present invention, and FIG. 16B is a thickness distribution graph for the same materials.

Hereinafter, the present invention will be described in more detail with reference to the drawings and examples.

Hybrid nanocomposites according to the present invention comprise a metal-organic framework (MOF) and magnesium nanocrystals supported in the framework.

Several studies have been made on the production of Ag, Au, Ni, or Pd nanoparticles of small size (1.4-10 nm) in MOF in the MOF, but no precedent has been reported for producing Mg nanoparticles in the MOF. . Nanocomposites according to the invention are prepared by pyrolysis of bis (cyclopentadienyl) magnesium loaded into the gas phase, and this method has not been reported at all in the preparation of nano sized magnesium.

The metal-organic backbone is [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] .22DMF.9H ₂ O (Zn ₄ O (aniline-2, 4,6-tribenzoate) ₂ only), as can be seen from the analytical data of the following examples, the X-ray single crystal structure is known from the literature (Chae, HK et al . A route to high surface area, porosity and inclusion of large molecules in crystals. A non-interpenetrated (6,3) -connected network of qom topologies, similar to MOF-177 as disclosed in Nature 427 , 523-527 (2004). net) (see FIGS. 1A and 1B; see FIGS. 2A and 2B).

Subsequently, magnesium nanocrystals are loaded in the metal-organic skeleton by the vapor deposition and pyrolysis processes described below, by controlling reaction conditions such as controlling the vapor deposition process time or making the reactor pre-vacuum. The amount of magnesium nanocrystals supported can be controlled. Preferably, the content of such magnesium nanocrystals may be 1.2% by weight to 10.5% by weight based on the total weight of the entire hybrid nanocomposite. If the content of the magnesium nanocrystals is less than the above range, there is a problem that the chemical hydrogen adsorption capacity is lowered, and if it exceeds the above range, there is a problem that the physical hydrogen adsorption capacity is lowered, which is not preferable.

In particular, despite the use of bis-cyclopentadienyl magnesium (MgCp ₂ ) as a raw material for vapor deposition in the hybrid nanocomposite according to the present invention, no cyclopentadiene is observed in the final result observed in the NMR spectrum. As such, an example of preparing nano-sized magnesium by pyrolysis of MgCp ₂ has not been reported in the prior art.

The magnesium nanocrystals are hexagonal disc-shaped magnesium nanocrystals, and the hexagonal diagonal length is 44 nm to 88 nm (average: 60 ± 18 nm), and the thickness is 16 to 61 nm (average: 37 ± 12 nm). In addition, the fast Fourier transform pattern for the magnesium nanocrystals is a lattice pattern with a separation distance of 2.805 μs, which is consistent with (100) d-spaced (2.7782 μs, JCPDS 04-0770) of metal magnesium That's a number. In addition, despite supporting various amounts of magnesium nanocrystals in the metal-organic framework, the size distribution of the magnesium nanocrystals supported in the present invention is very similar in all the samples prepared. Meanwhile, when the hybrid nanocomposite according to the present invention is exposed to the air for about 3 weeks, the form of magnesium nanocrystals changes into a star shape, and the lattice pattern has a separation distance of 2.1101 Å, which is (200) of MgO. values consistent with d-spaced (2.1061 Hz, JCPDS 89-7746).

The hybrid nanocomposite according to the present invention includes magnesium nanocrystals, thereby increasing physical hydrogen adsorption capacity and chemical hydrogen adsorption capacity as compared with the metal-organic framework alone. In the case of physical hydrogen adsorption capacity, the zero coverage isosteric heats increases with increasing content of magnesium nanocrystals supported, but in the case of chemical hydrogen adsorption capacity, with increasing temperature and amount of magnesium supported Hydrogen storage capacity is increased. In addition, the chemical adsorption and separation temperatures of the hybrid nanocomposites according to the present invention are significantly lower than pure magnesium.

Meanwhile, the hybrid nanocomposite according to the present invention maintains the hexagonal disk shape even after chemically adsorbing hydrogen, but its size and thickness are 80-200 nm (average: 142 ± 41 nm) and 50-100 nm (average, respectively). : 83 ± 18 nm), as magnesium nanocrystals aggregate and lattice expands as β-MgH ₂ is formed.

In addition, the present invention provides a method for producing a hybrid nanocomposite according to the present invention in order to achieve the second object. The method according to the invention,

1) A mixture of Zn (NO ₃ ) ₂ and aniline-2,4,6-tribenzoic acid was heated in DMF to give [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] .22DMF.9H ₂ Preparing O; 2) The [Zn ₄ O (aniline-2,4,6-benzoate) _2], by activating, using the 22DMF · 9H ₂ O supercritical CO ₂ Zn ₄ O (2,4,6 aniline Preparing tribenzoate) ₂ ; 3) chemical vapor deposition of bis (cyclopentadienyl) magnesium on Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ; 4) pyrolysing the vapor deposited bis (cyclopentadienyl) magnesium; And 5) removing the organic decomposition products generated from the pyrolysis step.

Step 1) may be carried out at a temperature of 80 ℃ to 100 ℃ for 24 to 48 hours, when the reaction temperature is out of the above range [Zn ₄ O (aniline-2,4,6-tribenzoate) ) ₂ ] .22DMF.9H ₂ O is not preferable because of the problem that no generation or ancillary compounds are produced, and when the reaction time is out of the above range, it is not preferable because there is the same problem as in the reaction temperature range. In addition, the 1) NO (Zn in step _{3) 2,} and the weight ratio of the reaction of aniline-2,4,6-benzoic acid is Zn (NO _{3) 2} per 100 parts by weight of 2,4,6-benzoic acid aniline 30 It is preferred to react 50 parts by weight to 50 parts by weight. If the reaction weight of Zn (NO ₃ ) ₂ is too high, [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] .22DMF.9H ₂ There is a problem that O is not produced or ancillary compounds are produced, and even when the reaction weight of aniline-2,4,6-tribenzoic acid is too large, the same problem is not preferable.

Step 2) may be performed under a pressure of 73 bar to 200 bar and a temperature condition of 31.1 ℃ to 50 ℃, when the reaction pressure is out of the range it is impossible to maintain the supercritical state of CO ₂ [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] is not preferable because there is a problem that the activity does not appear, even if the reaction temperature is out of the above range is not preferred.

In particular, in the present invention, it is possible to adjust the content of the magnesium nanocrystals supported by the step 3), that is, the vapor deposition step as described above, according to an embodiment of the present invention, the step 3) is 80 ℃ It may be carried out for 1 to 3 days at a temperature of 100 to 100 ℃, when the reaction temperature is out of the above range, the reduction of magnesium deposition amount and [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] is not preferable because of the structural deformation problem, and when the reaction time is out of the above range, there is a problem of reducing the amount of magnesium deposition.

In addition, according to another embodiment of the present invention, the reaction vessel is pre-vacuum state before performing the step 3), and then the step 3) for 3 to 5 hours at a temperature of 80 ℃ to 100 ℃ You can also do

Step 4), that is, pyrolysis of bis (cyclopentadienyl) magnesium may be performed by immersing the reaction vessel in an oil bath maintained at 180 ° C. to 200 ° C. for 3 to 24 hours. If the temperature range of the pyrolysis step is out of the above range, there is a problem of no pyrolysis of bis (cyclopentadienyl) magnesium and a decrease in the amount of adsorbed magnesium, and even if the reaction time is out of the range, the same problem is preferable. Not.

Magnesium nanocrystals are finally produced by performing step 4), and when the organic decomposition products except the produced magnesium nanocrystals are removed (step 5), the hybrid nanocomposites according to the present invention can be prepared.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are only to aid the understanding of the present invention, and should not be construed as limiting the scope of the present invention.

Example

Materials and equipment

All chemicals and solvents were reagent grade and used without further purification. Aniline-2,4,6-tribenzoic acid (hereinafter H ₃ atb) was prepared using the Suzuki-Miyaura coupling reaction. Preparation and manipulation of dry MOF, MgCp ₂ , and magnesium nanocrystals were performed under argon atmosphere using Schlenk or dry box. Infrared spectra were recorded using a Perkin-Elmer Spectrum One FTIR spectrometer. UV / Vis diffuse reflectance spectra were recorded using a Perkin-Elmer Lambda 35 UV / Vis spectrometer. Elemental analysis was performed using a Perkin-Elmer 2400 series II CHN analyzer. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed on Q50 and Q10 model devices from TA Instruments at a scan rate of 5 ° C./min, under N ₂ (g) atmosphere, respectively. Was performed. Powder X-ray diffraction (PXRD) data were recorded using a Bruker D5005 diffractometer at a scan rate of 5 ° / min and a step size of 0.02 ° at 2θ at 40 kV and 40 mA for CuKα (λ = 1.54050 Hz). It became. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was recorded as PerkinElmer Optima-4300 DV. High resolution TEM (HRTEM) images and energy-dispersive X-ray spectra (EDS) were obtained using JEM-3000F (JEOL) and JEM-3010 (JEOL) with Oxford INCA EDS unit. Electron tomography experiments were performed using a Tecnai G2 Spirit microscope from Korea Institute of Basic Science, which operated at 120 kV. Temperature programmed desorption-mass spectroscopy (TPD-MS) data was recorded using Hiden Analytical's IGA-Mass (IGA-001, HPR-30).

Manufacturing example

Preparation Example 1 Synthesis of H ₃ atb

H ₃ atb was synthesized using the Suzuki-Miyaura coupling reaction. Pd (PPh ₃ ) ₄ (0.4012 g, 0.3472 mmol), 2,4,6-tribromoaniline (3.070 g, 9.308 mmol), and K ₂ CO ₃ (4.015 g, 29.05 mmol) were purified with anhydrous THF ( 150 mL) and a stirred for 10 minutes. To the prepared solution was added a methanol solution (15 mL) of 4-methoxycarbonylphenyl boronic acid (5.015 g, 27.93 mmol), and the resulting solution was heated at 90 ° C. for 48 hours. After cooling to room temperature, the solution was concentrated using a rotary evaporator and the resulting dark green residue was extracted using methylene dichloride (300 mL). The solution was washed with water and brine solution and dried over anhydrous magnesium sulfate. The resulting solution was concentrated to give a light green residue. The product was purified by column chromatography using silica as adsorbent and methylene dichloride as eluent.

FT-IR (Nujol): ν _{OC = O} , 1690 cm ^-1 , ν _HNH , 1606. ¹ H NMR (300 MHz, DMSO-d ⁶ ): δ 8.08 (d, J = 8 Hz, 4H), 7.96 ( d, J = 8 Hz, 2H), 7.83 (d, J = 8 Hz, 2H), 7.72 (d, J = 8 Hz, 4H), 7.49 (s, 2H) 4.69 (s, 2H) ppm. Elemental Analysis (%). Found: C, 66.09; H, 4.38; N, 2.88. Calcd for C ₂₇ H ₁₉ NO ₆ 2H ₂ O: C, 66.25; H, 4.74; N, 2.86.

Preparation Example ₂ Synthesis of [Zn ₄ O (atb) ₂ ] · 22DMF · 9H ₂ O

Zn (NO ₃ ) .6H ₂ O (1.01 g, 5.33 mmol) and H ₃ atb (0.311 g, 0.686 mmol) were dissolved in N, N -dimethylformamide (DMF, 40 mL). The solution was placed in a glass serum bottle with a silicone stopper and an aluminum sealer and heated at 80 ° C. for 24 hours. Cooling to room temperature gave yellow crystals which were filtered off and washed with anhydrous DMF for a while.

FT-IR (Nujol): ν C = O (DMF), 1664 cm -1; ν _HNH , 1606; UV / vis (diffuse reflectance, λ _max ): 390 nm. Solid: lambda _max = 468 nm (excitation at lambda _max = 390 nm). Elemental Analysis (%). Found: C, 48.66; H, 6. 74; N, 11.38. (Zn ₄ C ₅₄ H ₂₄ N ₂ O ₁₃ ). 22 (C ₃ H ₇ NO). Calculated for 9H ₂ O: C, 48.88; H, 6.97; N, 11.40.

Preparation Example 3 Synthesis of [Zn ₄ O (atb) ₂ ] by Supercritical CO ₂ Treatment of [Zn ₄ O (atb) ₂ ] · 22DMF · 9H ₂ O

Previously, the synthesized present in the mother liquor to activate _{[Zn 4 O (atb) 2} ] · 22DMF · 9H 2 O was transferred to a vial (20 mL). The mother liquor was decanted and the crystals washed briefly with anhydrous DMF (4 × 15 mL). The crystals were placed with the solvent inside the supercritical dryer and the dryer chamber was sealed. The temperature and pressure of the chamber were raised under CO ₂ atmosphere to 40 ° C. and 200 bar, which is the critical point of CO ₂ (31 ° C., 71 bar). The chamber was vented at a rate of 15 mL min ⁻¹ and again filled with CO ₂ . The process of refilling, pressurizing and ventilating the CO ₂ was repeated four times. After drying, the sealed container containing the dry crystals was transferred to a glove bag to prevent the crystals from being exposed to air.

FT-IR (KBr pellet): ν _OC═O , 1599; ν _{C = C} , 1521 cm ⁻¹ . Elemental Analysis (%). Found: C, 54.65; H, 2.68; N, 1.84. Calcd for Zn ₄ C ₅₄ H ₂₄ N ₂ 0 ₁₃ : C, 55.04; H, 2. 74; N, 2.38.

Preparation Example 4 Synthesis of Hybrid Nanocomposites According to the Invention by Chemical Vapor Deposition of Bis (cyclopentadienyl) Magnesium

A small bottle (0.45 g, 3.85 × 10 ⁻⁴ mol) filled with [Zn ₄ O (atb) ₂ ] synthesized in Preparation Example 3 was placed in a Schlenk tube, and bis (cyclopentadienyl) was placed in the Schlenk tube. ) Magnesium (MgCp ₂ ) (0.35 g, 2.26 × 10 ⁻³ mol) was charged under argon atmosphere. Chemical vapor deposition of MgCp ₂ on [Zn ₄ O (atb) ₂ ] synthesized in Preparation Example 3 was performed by three methods.

Preparation Example 4.1 Non-vacuum Treatment Method (Reaction for 1 Day)

The argon-filled reactor tube was raised to 80 ° C. and maintained for 1 day.

Preparation Example 4.2 Non-vacuum Treatment Method (Reaction for 3 Days)

The argon filled reactor tube was raised to 80 ° C. and maintained for 3 days.

Preparation Example 4.3 Vacuum Processing Method

MgCp ₂ was chemically vapor deposited in [Zn ₄ O (atb) ₂ ] by maintaining a pre-vacuum state (10 ⁻³ mbar) at room temperature, raising the temperature to 80 ° C. and then holding it for 3 hours.

Chemical vapor deposition of MgCp ₂ on the materials synthesized in Preparation Examples 4.1 to 4.3 was confirmed by ¹ H NMR, and related data are shown in FIGS. 3A to 3C. The prepared materials were transferred to another Schlenk tube in a dry box filled with argon and the tubes were immersed in an oil bath maintained at 200 ° C. for about 3 hours. Pyrolysis of MgCp ₂ was performed by the above procedure, and Mg nanocrystals were prepared. Organic decomposition products generated during the pyrolysis process were removed by vacuum exhaust (10 ⁻⁶ bar) at room temperature for 24 hours, and as a result, a hybrid nanocomposite loaded with magnesium nanocrystals of various contents was prepared.

Table 1 below shows the contents of the metal-organic framework ([Zn ₄ O (atb) ₂ ]), MgCp ₂ content and inductively coupled to the hybrid nanocomposites according to the present invention synthesized from Preparation Examples 4.1 to 4.3. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) data is shown.

sample Content of [Zn ₄ O (atb) ₂ ]
mg (mol) MgCp ₂ content
mg (mol) ICP data
Mg / Zn (mole / mole) Preparation Example 4.1 460 (3.93 × 10 ^-4 ) 369 (2.38 × 10 ^-3 ) 0.15 Preparation Example 4.2 445 (3.80 × 10 ^-4 ) 345 (2.23 × 10 ^-3 ) 0.85 Preparation Example 4.3 453 (3.87 × 10 ^-4 ) 364 (2.36 × 10 ^-3 ) 1.40

Evaluation example

Evaluation Example 1. X-ray Crystallography

Diffraction data of [Zn ₄ O (atb) ₂ ] .22DMF.9H ₂ O was obtained using an Enraf-Nonius Kappa CCD diffractometer (Mo Ka, λ = 0.71073, graphite monochromator) at 150 K. In order to obtain X-ray diffraction data of [Zn ₄ O (atb) ₂ ] .22DMF.9H ₂ O, the guest molecules of the crystals were exchanged with anhydrous toluene for 2 days, during which the anhydrous toluene was supplemented several times. One of the crystals was immediately coated with Paratone oil. Preliminary orientation matrices and unit cell parameters were obtained from the peaks of the first 10 frames and then adjusted using the entire data set. Frames are DENZO (Otwinowski, Z. & W. Minor in processing of x-ray diffraction data collected in oscillation mode, methods in enzymology.Vol. 276 Part A, (Ed. CW .Carter Jr., RM Sweet): (Academic Press, New York, 1997, pp. 307-326), and integrated and corrected for Lorentz and polarization effects, scaling and global adjustments to crystal parameters were performed using SCALEPACK. . the crystal structure is a direct method (Sheldrick, GM Phase annealing in SHELX -90:. direct methods for larger structures Acta Crystallogr . A , 46, 467-473. (1990)) and full matrix least-squares adjustment using the SHELXS-97 computer program (Sheldrick, GM SHELXS-97.Program for the crystal structure refinement: (University of Gottingen, Gottingen, Germany (1997))). (Full matrix least-square refinement) was used to adjust the position of all non-hydrogen atoms with anisotropic displacement factors.The hydrogen atoms were geometrically positioned and the riding model was adjusted. There were two independent Zn ₄ O clusters, which were statistically disordered across two positions: site occupancy factors were 0.5 (3) for the Zn (1) atom. On the fold crystallographic axis), 0.16667 for the Zn (2) atom (at its normal position), and the position occupancy factors are 0.49683 for the Zn (3) atom, Z 0.51917 for the n (4) atom, 0.50317 for the Zn (5) atom, and 0.48083 for the Zn (6) atom.The positional charge factors are O (5A), O (5B), and O (6A). , O (6B), O (9A), and O (9B) atoms were given as 0.5. All amine functional groups were also given positional charge factors; N (1A), N (1B), N (1C). 0.33333 for N) and 0.16667 for N (2). Electron density for disordered guest molecules was flattened using the SQUEEZE option from PLATON (Spek, AL PLATON99 a multipurpose crystallographic tool: (Utrecht University: Utrecht, 1999). Therefore, guest molecules in [Zn ₄ O (atb) ₂ ] .22DMF.9H ₂ O were determined based on IR spectra, elemental analysis, and TGA results. Although no electron density associated with the guest molecules was observed, the residual electron density around the phenyl ring of atb ^{3 −} was flattened using the SQUEEZE option of PLATON , which was slightly lower than the R value determined without SQUEEZE. .

Crystallographic data for [Zn ₄ O (atb) ₂ ] · 22DMF · 9H ₂ O

M _r = 1170.23, Trigonal, space group P -31c (no. 163), α = 37.1796 (6), c = 29.9563 (6) Å, V = 35861.5 (11) Å ³ , Z = 8, d _calcd = 0.433 gcm ^-3 , T = 150 K, crystal size 0.1 x 0.1 x 0.1 mm ³ , λ = 0.71073 Å, 2 θ = 24.79, 575 parameters, R ₁ = 0.1149 ( I> 2σ ( I ), 20255 reflection), wR ₂ = 0.2760 (all data, 56800 reflections), GOF = 1.070. CCDC-846696 contains supplemental crystallographic data for the present invention, which is available free of charge from The Cambridge Crystallographic Data Center via ww.ccdc.cam.ac.uk/data_request/cif.

Evaluation Example 2 Low Pressure Gas Sorption Measurement

Gas adsorption-desorption experiments were performed using Autosorb-3B (Quantachrome Instruments), an automated micropore gas analyzer. All gases used were 99.999% pure. N ₂ sorption isotherms were measured at 77 K. H ₂ sorption isotherms were monitored at 77K and 87K at each adsorption pressure by the static volume method. After the gas sorption measurement was completed, the weight of the sample was accurately measured. Surface area was measured from N ₂ adsorption isotherms measured at 77K using Brunauer-Emmett-Teller (BET) and Lanmuir model, where the data were P / P ₀ = Those in the range 0.01-0.1 (BET) and 0.005-0.3 (Langmuir) were collected. The pore volume was determined using the Dubinin-Radushkevich (DR) equation.

Evaluation Example 3 Measurement of Isosteric Heats of H ₂ Physical Adsorption

H₂ Equivalent adsorption heat of adsorption was measured at 77K and 87K₂ It was measured using the sorption data. As can be seen in Equation 1, a virial type representation was used, which is a parameter independent of temperature.a _i  Andb _i  (Czepirski, L. & Jagiello, J. Virial-type thermal equation of gas-solid adsorption.Chem . Eng . Sci . 44, 797-801 (1989); Dinca, Mmeat get Hydrogen storage in a microporous metal-organic framework with exposed Mn^{2 +} coordination sites.J. Am . Chem . Soc . 128, 16876-16883 (2006).

[Equation 1]

In Equation 1, P is the pressure (atm), N is the amount of H ₂ gas adsorbed (mg g ^-1 ), T is the temperature and (K), m and n in order to properly describe the isotherms Represents the number of coefficients required. The equations were fitted using the R statistical software package (available from http://www.r-project.org.).

In order to determine the H ₂ equivalent adsorption heat value, Equation 2 was applied, in which R represents a universal gas constant.

&Quot; (2) "

Evaluation Example 4 High Pressure Gas Sorption Measurement

High pressure H ₂ gas sorption was measured by gravimetric method using Rubotherm MSB (magnetic suspension balance) apparatus. H ₂ physical adsorption isotherms of the hybrid nanocomposites according to [Zn ₄ O (atb) ₂ ] and Preparation Example 4.1 were measured at 77 K and 298 K. H ₂ physical adsorption isotherms of hybrid storage materials according to Preparation Example 4.3 were measured at 323 K and 415 K. Adsorption of H ₂ at 473K of the hybrid nanocomposites according to Preparation Examples 4.1 to 4.3 was measured using a High Pressure Volumetric Analyzer (HPVA-100), VTI Corp. The gases used had 99.999% purity and the fine moisture contained in the gas was removed using a dry trap filled with 5 μs molecular sieve, which was purchased from Chromatography Research Supplies (model 500). Solids (over 300 mg) of the solvent-free test materials were quickly introduced into the gas sorption apparatus and activated by exhaust at 100 ° C. Prior to gas sorption experiments, the volume of the framework was determined by measuring the He isotherm (up to 80 bar) at 298 K. Excess sorption isotherms were measured and then corrected for buoyancy of the system and sample. Buoyancy correction for the sample was performed by multiplying the volume of the skeletal structure by the corresponding gas density at each pressure and temperature.

Evaluation Example 5 Measurement of NMR Spectrum

Chemically adsorbed H ₂ on a sample carrying MgCp ₂ on [Zn ₄ O (atb) ₂ ], a sample obtained by pyrolyzing the sample, and a hybrid nanocomposite prepared at Preparation Example 4.3 (200 ° C., 300 bar). Samples were dissolved in a mixture of DCl (10-20 μL) and d ₆ -dimethylsulfoxide (600 μL), and then ¹ H NMR spectra were recorded with a BRUKER DE / DPS-300 spectrometer (see FIGS. 3A-3C). .

Review

As mentioned above, [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] .22DMF.9H ₂ O could be prepared in the form of yellow crystals, which was Zn (NO ₃ ) _{2 in} DMF. And H ₃ atb by heating the mixture. The X-ray single crystal structure for the prepared crystal has a non-interpenetrated (6,3) -connected net of qom topology, which is shown in FIG. MOF-177 (Chae, HK et al. , Which is a metal-organic skeleton structure of the prior art as seen in FIGS. 1A and 1B, and FIGS. 2A and 2B). al . A route to high surface area, porosity and inclusion of large molecules in crystals. Nature 427, 523-527 (2004)). By removing the guest solvent molecules from the prepared crystals by treating with supercritical CO ₂ , it is possible to prepare [Zn ₄ O (atb) ₂ ] in which the guest molecules are not present. Bis-cyclopentadienyl magnesium vapor (MgCp ₂ ) was deposited in [Zn ₄ O (atb) ₂ ] prepared at 80 ° C., and the resultant was pyrolyzed at 473 K under argon atmosphere to obtain [Zn ₄ O ( atb) ₂ ] to obtain a compound having magnesium nanocrystals. Further, the reaction time and prior to the reactor used in the deposition of MgCp _2-metals by giving by varying the reaction conditions, such as vacuum is applied - and to control the content of MgCp ₂ is supported in the organic skeleton, and other content of magnesium nano Several samples carrying crystals could be prepared. Specifically, the contents of magnesium nanocrystals supported on the materials prepared in Preparation Examples 4.1, 4.2, and 4.3 were 1.26 wt%, 6.52 wt%, and 10.5 wt%, respectively, which were inductively coupled plasma atomic emission spectroscopy ( Inductively coupled plasma atomic emission spectroscopy (ICP-AES) measured and the results are shown in Table 1 above. Referring to the NMR spectra shown in FIGS. 3A to 3C, it can be seen that cyclopentadiene does not exist in the resulting nanocomposite. Although, the prior art discloses a method for preparing magnesium nanoparticles having a size of 5-15 nm by reducing MgCp ₂ by reacting it in a tetrahydrofuran solution of Li ⁺ (naphthalene) and polymethylmethacrylate (Jeon, K. -J. et al . Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts. Nature Materials 10, 286-290 (2011)), as in the present invention, a method for producing nanoscale Mg by pyrolyzing MgCp ₂ has not been developed at all.

High resolution transmission electron microscopy (HRTEM) photographs of the various hybrid nanocomposites prepared in the present invention show that the magnesium nanocrystals according to the present invention are in the form of hexagonal discs, having a diagonal length of 44-88 nm (average: 60 ± 18 nm), It is shown that the thickness is 16-61 nm (mean: 37 ± 12 nm) (see Figures 4a to 4e; see Figures 5a to 5i). The fast Fourier transform pattern (FIG. 4b) for the magnesium nanocrystals of the present invention is a lattice pattern with a separation distance of 2.805 μs, which is (100) d-spaced (2.7782 μs, JCPDS 04- 0770, FIG. 4D). In addition, despite supporting various amounts of magnesium nanocrystals in the metal-organic framework, the size distribution of the magnesium nanocrystals supported in the present invention is very similar in all the samples prepared. Meanwhile, when the hybrid nanocomposite according to the present invention is exposed to the atmosphere for about 3 weeks, the form of magnesium nanocrystals changes into a star shape (FIG. 4C), and the lattice pattern has a separation distance of 2.1101 μm, which is MgO. Is consistent with (200) d-spacing (2.1061 Hz, JCPDS 89-7746, FIG. 4E).

In the present invention, electron tomography (tomography) was performed to confirm that magnesium nanocrystals were supported inside the channel of the MOF. Tilt angle + 40 ° ~ -40 °,, IMOD program from the TEM images obtained at intervals of 1 ° (Kremer, JR, Mastronarde , DN & McIntosh, JR Computer visualization of three-dimensional image data using imod. J. Struct. Biol 116, using a 71-76 (1996)) were able to build a three-dimensional image. When the sample was tilted, it was observed that the magnesium nanocrystals in the sample changed from hexagon to rectangle and back from rectangle to hexagon, which means that the magnesium nanocrystals were actually supported in MOF (FIG. 6A (TEM image); 6B-6D (images for morphologically reconstituted magnesium nanocrystals at different angles). X-ray photoelectron spectrum (XPS) results of the hybrid nanocomposites according to the present invention show that Mg ⁰ and Zn ^II coexist in solids, similar to those previously reported for Mg ⁰ . Mg ⁰ (2 p ) peak at 50.6 eV was seen. In Figure 7c (carbon; peak) for the Fig. _{7b (Mg; 2 p 3/} 2 and ₂ p _1/2 peaks for Zn ^II are the peak) for the shown (Fig. 7a (Zn at 1044 and 1021 eV reference peak Peaks for oxygen); see FIG. 7D (peaks for oxygen). Powder X-ray diffraction (PXRD) patterns show that the structure of [Zn ₄ O (atb) ₂ ] remains even after magnesium nanocrystals are formed, the size of which is much larger than the channel size of the MOF (see FIG. 8). . To understand this phenomenon, the volume ratio of the network backbone to the material prepared in Preparation Example 4.3 (containing 10.5% by weight of magnesium) relative to the magnesium nanocrystals formed was calculated. Assuming that all magnesium nanocrystals destroyed the network backbone, the magnesium nanocrystals would destroy up to 4.6% by volume of the network backbone. This is too small to change the PXRD pattern of the MOF. In addition, it has been previously reported that metal nanoparticles much larger than the cavity size of the host are impregnated in the MOF while maintaining the network structure (Moon, HR, Kim, JH & Suh, MP Redox active porous metal-organic framework producing silver nanoparticles from ^{Ag I ion at room temperature. Angew} . Chem. Int. Ed. 44, 1261-1265, etc. (2005)). PXRD peaks of the crystalline magnesium generally appear at 2 θ = 32.2, 34.4, and 36.6 ° but, in the present invention, showing that a high resolution TEM / EDS (Energy Dispersive Spectroscopy) data clearly that magnesium nanocrystals are incorporated into the matrix Nevertheless, these peaks did not appear. However, when exposed to air for 2 days, it can be seen from FIG. 8 that the PXRD pattern was oxidized from Mg to MgO while maintaining the framework structure of [Zn ₄ O (atb) ₂ ].

For materials prepared from [Zn ₄ O (atb) ₂ ] and Preparation Examples 4.1 to 4.3, the adsorption-desorption isotherm for N ₂ gas at 77K and the adsorption-desorption isotherm for H ₂ gas at various temperatures were measured And the results are shown in Table 2 below.

Mg / Zn,
mol / mol
(weight%) N ₂
[cm ³ g ^-1 ] Surface area
[m ² g ^-1 ]
Void volume
[cm ³ g ^-1 ] H ₂ storage [% by weight]
Low pressure high pressure
(1atm) (condition) Q _st
[kJ mol ^-1 ] [Zn ₄ O (atb) ₂ ] N / A 1135 4244 * 4914 □ 1.64§ 1.21 (77K)
0.74 (87K) 8.81 (77 K, 75 bar)
0.45 (298K, 80bar) 4.55 Preparation Example 4.1 0.15
(1.26) 1104 4254 * 4757 □ 1.47§ 1.24 (77K)
0.65 (87 K) 8.74 (77 K, 89 bar)
0.54 (298 K, 90 bar) 5.68 Preparation Example 4.2 0.85
(6.52) 559 2056 * 2373 □ 0.84§ 0.72 (77 K)
0.40 (87 K) 0.29 (473K, 30 bar) 7.24 Preparation Example 4.3 1.40
(10.5) 378 1371 * 1581 □ 0.36§ 0.60 (77K)
0.47 (87 K) 0.20 (323 K, 80 bar)
0.24 (415K, 40 bar)
0.71 (473K, 30 bar) 11.6

*: BET surface area

□: Langmuir surface area

§: pore volume measured using Dubinin-Radushke Beach (DR) equation

The N ₂ gas sorption isotherm for the four samples was type-I and characteristic of microporous materials (see FIGS. 9A and 9B). Despite the presence of NH ₂ groups present in the ligand of [Zn ₄ O (atb) ₂ ], the surface area, pore volume, and H ₂ adsorption capacity were similar to MOF-177 of the prior art. Gas sorption data for various magnesium-loaded samples show that as the magnesium content increases, the BET surface area, pore volume, and hydrogen storage capacity at 77 K and 1 atm decrease, indicating that the magnesium nanocrystals are MOF. This is because the voids occupy the surface and space of the pores. However, at 298 K and high pressure, the material of Preparation 4.1 increased the H ₂ storage capacity to 0.54 wt%, compared to 0.45 wt% in pure [Zn ₄ O (atb) ₂ ], which resulted in magnesium nanocrystals 298 Implying a positive effect on H ₂ adsorption at K (see FIGS. 10A (77K) and 10B (298K)). The zero coverage isosteric heats of H ₂ adsorption calculated from H ₂ adsorption isotherms measured at 77K and 87K increased with increasing magnesium content, 4.55 of [Zn ₄ O (atb) ₂ ]. From kJ mol ⁻¹ , it increased to 11.6 kJ mol ⁻¹ of Preparation Example 4.3 (see Table 2 and FIG. 11). This suggests that magnesium nanocrystals reduce some pore size in the backbone, which increases the potential overlap between the backbone and hydrogen.

In order to observe the chemisorption capacity of the supported magnesium nanocrystals, the H ₂ storage of the material prepared from Preparation Example 4.3 at 323K, 415K and 473K under high pressure conditions was measured (FIG. 12B (473K), 13a (325K, 80 bar) ) And 13b (415K, 40bar)). At high temperature, unlike physical adsorption MOF for H ₂ storage is reduced, H ₂ chemical adsorption capacity was increased as the temperature rises. H ₂ adsorption capacity of the material prepared from Preparation 4.3 was 0.20% by weight in H ₂ under pressure, 323 K of 80 bar, was 0.24% by weight in H ₂ under pressure, 415 K of 40 bar, of 30 bar H ₂ pressure At 473 K, the weight was 0.71 wt%. This figure for the material of Preparation 4.3 is markedly comparable to the material of Preparation 4.2, even though the material of Preparation 4.3 has much lower surface area and pore volume due to the magnesium loaded to a higher degree. It is a high figure. This means that the H ₂ storage at 473 K increases with increasing content of the loaded magnesium nanocrystals. The fact that the H ₂ storage capacity improves with increasing temperature and content of magnesium nanocrystals confirms that the hydrogen storage of the hybrid nanocomposites according to the invention at 323 K, 415 K, and 473 K is due to chemical adsorption. . This chemisorption temperature is significantly lower (> 200 K) than the chemisorption temperature (673 K under 10 bar) of pure magnesium powder with a size of 50-100 μm. The H ₂ storage capacity with magnesium alone was calculated from the data and found to be 7.5 wt% at 473 K and 30 bar. Given that the H ₂ chemical adsorption capacity of pure magnesium is 7.66% by weight, 99% of the magnesium nanocrystals in the hybrid nanocomposites of the present invention chemically adsorb H ₂ , which is a magnesium nanoparticle that is previously incorporated into a polymer. (Jeon, K.-J. et al . Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts. Nature Materials 10, 286-290 (2011) ) or pure magnesium powder (Sakintuna, B., Lamari-Darkrim , F. & Hirscher, M. Metal hydride materials for solid hydrogen storage:. A review Int J. Hydrogen Energy 32, 1121-1140 (2007)). 473 bulk hydrogen storage material of Preparation 4.3 and 30 bar measured at K function is 3.1 g L ^{- 1} was.

The hydrogen desorption properties of the material prepared from Preparation Example 4.3 were investigated by temperature programmed desorption mass spectroscopy (TPD-MS) analysis (see FIG. 12C). The TPD-MS results showed that H ₂ desorbs at T> 523 K and 1 atm. In particular, it should be noted that the strength of the H atomic signal is exactly twice the strength of the H ₂ molecular signal. This means that all desorbed hydrogen sources are MgH ₂ and not MOF at all (see FIGS. 13A and 13B). Preparation 4.3 after H ₂ adsorption TG mass loss for the material is also in good agreement with the TPD-MS data (see FIG. 14).

HRTEM images of Preparation 4.3 material measured after H2 chemisorption at 473 K and 30 bar showed that the crystal form of Mg was retained, but the crystal size increased significantly. The FFT pattern showed a lattice pattern with a separation interval of 2.247 mm 3, which was characterized by (110) d -spaced (2.257 μs, JCPDS 35-1185) of β-MgH ₂ (FIG. 15A (HRTEM image); FIG. 15B ([ Zn ₄ O (atb) ₂ ] hexagonal MgH ₂ nanocrystals; see FIG. 15C (fast Fourier transform pattern for MgH ₂ nanocrystals). The materials according to the invention after H ₂ adsorption had crystal sizes (diagonal length of the hexagon) and thicknesses of 80-200 nm (mean: 142 ± 41 nm) and 50-110 nm (mean: 83 ± 18 nm), respectively. This is about 2.3 times larger than the size of magnesium nanocrystals (see Figure 16a (size distribution) and 16b (thickness distribution)). This fact means that MgH ₂ crystals have a volume about 12 times larger than Mg crystals. Considering that the volume of magnesium should increase by about 30% when it forms a hydride (Zlotea, C., Lu, J. & Andersson, Y. Formation of one-dimensional MgH ₂ nano-structures by hydrogen induced disproportionation. J Alloys Compd . 426, 357-362 (2006)), these results are the average of nine magnesium nanocrystals agglomeration during the process of chemical adsorption of H ₂ at high temperature and high pressure means that MgH ₂ form a nanocrystal. This is explained by three dimensional Ostwald ripening, in which larger crystals absorb smaller mobile crystals (Di Vece, M. et. al . Hydrogen-induced ostwald ripening at room temperature in a Pd nanocluster film. Phys . Rev. Lett . 100 236 105 (2008)). After that MgH ₂ is _{formed, [Zn 4 O (atb)} 2] did organic ligands are not hydride of which was observed was dissolved in the resultant nanocomposite to a mixture of d ₆ -DMSO (dimethyl sulfoxide) and DCl ¹ It can be seen from the H NMR spectrum (see FIGS. 3A to 3C). Let it the material according to the present invention the hydrogen bond exposed to the air, PXRD pattern was 2 θ = 36.8 and eotneunde represent a new peak at 42.8 degrees, which will be available for the MgO, another new peak of 2 θ = 38.0 degree The peak at corresponds to Mg (OH) ₂ , which means that MgO and Mg (OH) ₂ have changed to the combined form as the material according to the present invention in which hydrogen is bonded is exposed to air (FIG. 8). Reference).

Claims (14)

Metal-organic backbones having a non-interpenetrated (6,3) -connected net of a qom topology; And
A hybrid nanocomposite having hydrogen storage capacity, including magnesium nanocrystals embedded in the metal-organic backbone. The hybrid nanocomposite having hydrogen storage capacity according to claim 1, wherein the metal-organic skeleton is Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ . delete The hybrid nanocomposite of claim 1, wherein the magnesium nanocrystals are present in an amount of 1.2 wt% to 10.5 wt% based on the total weight of the hybrid nanocomposites. The hybrid nanocomposite of claim 1, wherein the magnesium nanocrystals have a hexagonal disk shape. 6. The hybrid nanocomposite having hydrogen storage capacity according to claim 5, wherein the hexagonal disk has a diagonal length of 44 nm to 88 nm and a thickness of 16 nm to 61 nm. The hybrid nanocomposite having hydrogen storage capacity according to claim 1, wherein the fast Fourier transform pattern for the magnesium nanocrystals is a lattice pattern having a separation distance of 2.805 μs. 1) A mixture of Zn (NO ₃ ) ₂ and aniline-2,4,6-tribenzoic acid was heated in DMF to give [Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ] .22DMF.9H ₂ Preparing O;
2) The [Zn ₄ O (aniline-2,4,6-benzoate) _2], by activating, using the 22DMF · 9H ₂ O supercritical CO ₂ Zn ₄ O (2,4,6 aniline Preparing tribenzoate) ₂ ;
3) chemical vapor deposition of bis (cyclopentadienyl) magnesium on Zn ₄ O (aniline-2,4,6-tribenzoate) ₂ ;
4) pyrolysing the vapor deposited bis (cyclopentadienyl) magnesium; And
5) A method of producing a hybrid nanocomposite having a hydrogen storage capacity, comprising the step of removing an organic decomposition product generated from the pyrolysis step. The method of claim 8, wherein the step 1) is performed at a temperature of 80 ° C. to 100 ° C. for 24 hours to 48 hours. The method of claim 8, wherein 1) at step Zn (NO _{3) 2} and the weight ratio of the reaction of aniline-2,4,6-benzoic acid is Zn (NO _{3) 2} -2,4,6 aniline relative to 100 parts by weight -30 to 50 parts by weight of tribenzoic acid is reacted, the method for producing a hybrid nanocomposite having a hydrogen storage capacity. The method of claim 8, wherein the step 2) is performed under a pressure of 73 bar to 200 bar and a temperature condition of 31.1 ° C. to 50 ° C. 10. The method of claim 8, wherein the step 3) is performed for 1 day to 3 days at a temperature of 80 ° C. to 100 ° C. 10. The method of claim 8, wherein step 3) is carried out for 3 hours to 5 hours at a temperature of 80 ℃ to 100 ℃ after making the reaction vessel in a pre-vacuum state before performing step 3) Method for producing a hybrid nanocomposite having a hydrogen storage capacity to be. The method of claim 8, wherein the step 4) is performed by immersing the reaction vessel in an oil bath maintained at 180 ° C. to 200 ° C. for 3 hours to 24 hours. .

Images