KR20130123685A - Catalyst comprising hydrogel and active ingredient - Google Patents

Abstract

The present invention relates to a metal nanoparticle catalyst supported in hydrogel. The catalyst of an embodiment of the present invention can provide hydrogel for a metal nanoparticle support capable of improving the catalyst activation and reusability and can be used as a catalyst in the reduction reaction of an aromatic or heterocyclic nitro compound by supporting a metal nanoparticle on the hydrogel. [Reference numerals] (AA) Phosphonamidate hydrogel;(BB) In-situ reduction;(CC) AuNP-deposited hydrogel reuse;(DD) Reuse route

Description

Catalyst comprising hydrogel and active ingredient

The present invention relates to a catalyst comprising a hydrogel and an active ingredient.

Metal components such as metals, metal ions or metal oxides have been used as active ingredients of catalysts. In particular, metal nanoparticles (MNP) have a higher volume-to-area ratio and higher electrical properties than corresponding bulk metals, and thus have been studied as efficient catalysts for producing organic materials. Recently, attention has been focused on improving the catalytic activity and recyclability of metal nanoparticles for applications in large scale processes. As such, solid supports have been generally used to improve the catalytic activity and reusability of metal nanoparticles and to avoid aggregation of metal nanoparticles. As the solid support, alumina, silica, zeolite, calcium carbonate, metal oxide, carbon nanotube, and the like have been used. However, when the material is used as the metal nanoparticle support, the catalytic reaction can only occur on the surface of the solid, and if the metal nanoparticle is placed inside the solid support material, the contact between the catalyst and the reactant is lost. Limited catalytic activity is lost.

Therefore, it is important to use an efficient carrier that can improve the catalytic activity and reusability of the metal nanoparticles.

The present invention is to provide a catalyst comprising a hydrogel and the active ingredient.

In one embodiment of the present invention, a hydrogel comprising an amine group or a thiol group in the structure that can improve the catalytic activity and reusability; And it can provide a catalyst comprising a catalytically active component supported on the hydrogel.

Hereinafter, the present invention will be described in detail.

The hydrogel of the present invention contains an amine group or thiol group in the structure. The amine group or thiol group may strongly adsorb a precursor of a catalytically active component, for example, metal ions, on or inside the hydrogel. Therefore, the amine group or thiol group can carry the catalytically active component on the surface or inside of the hydrogel.

As used herein, the term "support" means immobilization of the catalytically active component on or within the hydrogel by physical or chemical bonding.

As an example of the present invention, the hydrogel may be a hydrogel including the following Formula 1 as a crosslinking site.

[Formula 1]

In Formula 1, Y ₁ , Y ₂ and Y ₃ are each independently selected from -O-, -S- or -NH-, and at least one of Y ₁ , Y ₂ and Y ₃ is -S- or -NH - to be.

The hydrogel may be crosslinked based on the crosslinking site represented by Formula 1 to form a hydrogel.

The crosslinking site means a site capable of forming a branch or a network structure by forming a plurality of covalent bonds when forming a polymer or a macromolecule.

The present invention may form a hydrogel including a crosslinking site having the structure of Formula 1 as an example, the crosslinking site of Formula 1, for example, may be formed from phosphorus oxychloride (POCl ₃ ) However, any precursor that can form a crosslinking site having the above structure can be used without particular limitation.

As another example of the present invention, the hydrogel may be a hydrogel including any one of the following Formulas 2 to 4 as a repeating unit.

(2)

(3)

[Formula 4]

In Formulas 2 to 4, R ₁ , R ₃ to R ₆ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkyl group having 1 to 30 carbon atoms, L represents a branched structure having X at the terminal, o and p is an integer of 1 to 100, X is represented by the following formula (5),

[Chemical Formula 5]

In Formula 5, A ₁ and A ₂ are each independently selected from the group consisting of -NH- and -S-, and R ₇ and R ₈ are alkylene groups having 1 to 30 carbon atoms.

In the formula, o and p may be an integer of 1 to 100, 1 to 50 or 1 to 20, which may be appropriately selected according to the purpose within the above range.

As used herein, unless otherwise specified, the term alkylene group may mean an alkylene group having 1 to 30 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, or 1 to 8 carbon atoms. The alkylene group may have a linear, branched or cyclic structure. In addition, the alkylene group may be optionally substituted by one or more substituents.

As used herein, unless otherwise specified, the term alkyl group may mean an alkyl group having 1 to 30 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, or 1 to 8 carbon atoms. The alkyl group may have a linear, branched or cyclic structure. In addition, the alkyl group may be optionally substituted with one or more substituents.

In addition, the symbol used in the chemical formula of the present specification, "*" may mean a part connected to another functional group.

As another example of the present invention, L in the hydrogel may be a hydrogel including one or more of the units represented by the following Chemical Formulas 6 to 8 in the structure.

[Chemical Formula 6]

[Formula 7]

[Formula 8]

In another example of the present invention, L may be a hydrogel including a unit represented by the formula (9).

[Chemical Formula 9]

In Formulas 6 to 9, X is as defined in Formula 5.

If the hydrogel of the present invention is a hydrogel formed through the crosslinking site of Chemical Formula 1, the compounds crosslinked through the crosslinking site are not particularly limited, and may be appropriately suited for use within a range capable of maintaining the characteristics of the hydrogel. It may be selected, for example, a hyper-branched polymer (hyper-branched polymer) formed based on the formula (3) can be used.

The hyper-branched polymer is a polymer having a plurality of branched structures and includes many functional groups. As an example of the present invention, the hyper-branched polymer includes a structure of Chemical Formulas 6 to 8 and / or Chemical Formula 9 based on Chemical Formulas 3 or 4. It is possible to form branched polymers. In addition, the weight average molecular weight of the hyper-branched polymer used in the present invention is not particularly limited. For example, the lower limit of the molecular weight per mole may be 100 to 500 g, and the upper limit may be 2,000 to 10,000 g.

On the other hand, as an embodiment of the present invention, the catalytically active component that can be supported on the hydrogel includes, for example, metal, metal ions or metal oxides. Non-limiting examples of the metal include Au, Pt, Pd, Ir, Rh, Ag, Ru, Al, Cu, Te, Bi, Pb, Fe, Ce, Mo, Nb, W, Sb, Sn, V, Mn, It may be at least one selected from the group consisting of Ni, Co, Zn and Ti. The hydrogel has a swelling property and forms a network structure capable of absorbing a solution such as water, and when the catalytically active component acting as a catalyst is supported on the hydrogel, the hydrogel surface as well as the inside of the hydrogel In addition, the reactant and the catalytically active component may be brought into contact with each other, thereby improving the activity of the catalyst.

In addition, the catalytically active component may be, for example, nanoparticles having an average particle diameter of 2 to 50 nm or 2 to 40 nm.

Reacting the hydrogel by adding a compound having two or more hydroxy groups at a terminal thereof to a solution in which phosphorus oxychloride is dissolved; And it can be prepared through the step of reacting by adding a compound represented by the following formula (10) to the reaction product.

[Formula 10]

In Formula 10,

R ₉ is an alkylene group having 1 to 30 carbon atoms, and F is an amine group or a thiol group.

The compound represented by the above formula (10) is not particularly limited and may be appropriately selected and used as long as it contains an amine group or a thiol group at the terminal. Details of the alkylene group are as described above.

The solvent for dissolving phosphorus oxychloride is not particularly limited as long as the resulting hydrogel can stably form a structure. For example, THF (Tetrahydrofuran) may be used.

The compound having two or more hydroxy groups at the terminal is not particularly limited as long as it is a polyhydric alcohol having two or more hydroxy groups. For example, the number of hydroxy groups may be 500 or less.

In addition, the compound having a hydroxy group is not particularly limited, but may be, for example, 1 to 30 carbon atoms, 1 to 16 carbon atoms, or 1 to 8 carbon atoms, or may be a hyper-branched polymer having a hydroxy group at the terminal.

The temperature of the step of reacting by adding a compound having two or more hydroxy groups at the terminal to the solution in which the phosphorus oxychloride is dissolved may be, for example, 5 ° C or less. When making it react in the said temperature range, reaction etc. which produce | generate chlorination of a hydroxyl group can be suppressed. The lower limit of the reaction temperature is not particularly limited, but may be, for example, 0 ° C.

In addition, the step of reacting by adding the compound represented by Formula 10 to the reaction product may be carried out at 0 to 60 ℃, or at room temperature.

1 shows a process for producing a hydrogel as an example of the present invention.

As an example, as shown in FIG. 1, a hydrogel having a crosslinking site of Chemical Formulas 1 to 3 may be prepared.

In addition, the hydrogel manufacturing method may be a one pot process. The One Pot process is a method of preparing a desired compound at one time without passing through various processes when preparing compounds, etc., and has an advantage of easy synthesis and improved yield. That is, the hydrogel manufacturing method of the present invention can be carried out by a one-pot process, it can be prepared more easily than the conventional hydrogel manufacturing method.

As described above, the hydrogel has a swelling property and forms a network structure capable of absorbing a solution such as water, so that a catalytically active component used as a catalyst, for example, metal nanoparticles, is supported on the hydrogel. In this case, not only the surface of the hydrogel but also the inside of the hydrogel may react with the reactant and the metal nanoparticles, thereby improving the activity of the catalyst.

In one embodiment, the method for preparing the catalyst comprises a hydrogel comprising an amine group or a thiol group in the structure; And mixing the catalytically active component precursor. Since the hydrogel includes a plurality of amine or thiol functional groups in the structure, these functional groups can be immobilized by adsorbing a catalytically active component or a precursor thereof not only on the surface of the hydrogel but also inside. The functional group may generate metal nanoparticles by in situ reduction of metal ions on or inside the hydrogel. Thus no further other reducing agent is required for this reduction.

In another embodiment, when the metal ions adsorbed on or inside the hydrogel, such as heavy metal ions (Fe, Cu, Mo, Co, or Zn), are not readily reduced, the adsorbed metal ions themselves are catalytically active ingredients. Can play a role. In another embodiment, metal oxides can serve as catalytically active ingredients.

When the catalytically active component is a metal ion or a metal oxide, a catalyst may be prepared by the following method, and a manufacturing process thereof is illustrated in FIG. 2.

The method comprises the steps of adding a compound having two or more hydroxy groups at the end of the solution to dissolve the phosphorus oxychloride to produce a reactant;

Mixing the reactants with a catalytically active component or a precursor thereof to produce a mixture; And

Mixing the mixture with a compound having Formula 10:

[Formula 10]

In Formula 10,

R ₉ is an alkylene group having 1 to 30 carbon atoms, and F is an amine group, thiol group, or hydroxy group.

Specific materials used in the step of adding a compound having two or more hydroxy groups at the end of the solution to dissolve the phosphorus oxychloride to produce a reactant and mixing the mixture with a compound having the formula (10) and The reaction conditions are the same as the method for preparing the hydrogel described above.

In addition, in the step of producing a mixture by mixing the reactant with the catalytically active component or a precursor thereof, the mixture may be in the form of an emulsion, for example. The amount of catalytically active component or precursor thereof to be mixed can be determined according to the requirements of each application.

The catalytically active component or its precursor is not particularly limited, and for example, Au, Pt, Pd, Ir, Rh, Ag, Ru, Al, Cu, Te, Bi, Pb, Fe, Ce, Mo, Nb, W At least one metal selected from the group consisting of Sb, Sn, V, Mn, Ni, Co, Zn and Ti; Ions or salts thereof; Or oxides thereof.

As described above, when the catalytically active component is supported on the hydrogel using the hydrogel of the present invention, the hydrogel not only serves as a matrix for using the catalytically active component as a catalyst, but also a capping agent. It also plays a role. Therefore, the catalytically active component supported on the hydrogel, for example, metal nanoparticles, may not be agglomerated with each other, but may be stably dispersed and exist to maintain activity.

In addition, the catalyst in which the catalytically active component of the present invention is supported on a hydrogel has a characteristic of being capable of recycling. That is, since the catalytically active component, for example, metal nanoparticles is immobilized on a hydrogel having structural integrity, it is possible to maintain high catalytic activity even if it is separated again after participating in the reaction as a catalyst. It can be used repeatedly more than once.

For example, M. Tamimi, Separation and Purification Technology , 2008, 61, 103-108; Journal of Hazardous Materials , 2009, 161, 926-932; According to Applied Catalyst A: General , 2008, 346, 140-148, heavy metal ions are likely to be used as catalysts in a variety of applications such as the removal of various dyes from wastewater. However, when such heavy metal ions are used directly as a catalyst without a support, a large amount of residues may occur in the reaction system after the reaction, and thus an additional purification process is required. In contrast, when the hydrogel is used as a support (carrier) of metal ions as in the present invention, since the catalytic reaction proceeds in the hydrogel matrix, it is possible to prevent the formation of residue.

In another example of the invention, in the presence of a catalyst according to the invention, it is possible to provide a method for preparing a target material comprising the step of oxidizing or reducing a reactant.

The catalyst according to the invention can be used for various reactions, for example oxidation, reduction, or synthesis of organic compounds.

In one embodiment, the catalyst can be used to reduce the reactant aromatic nitro compound to produce an aromatic amine compound of interest. Generally, aromatic nitro compounds are prepared as by-products in pharmacy, dyes and the like and are toxic organic substances. Therefore, reducing it to a useful aromatic amine compound is one of the important processes.

When the metal nanoparticle catalyst supported on the hydrogel of the present invention is used, the catalytic activity is high, recyclable, and the aromatic nitro compound can be efficiently reduced to the aromatic amine compound.

The temperature of the reduction reaction may be, for example, -20 to 80 ℃.

The reduction reaction is, for example, NaBH ₄ , LiAlH ₄ , H ₃ NBH ₃ , NaB (CN) H ₃ , NaB (OAc) ₃ H, LiAl (CN) H ₃ , LiAl (OAc) ₃ H, NaB (OCH ₃ ) but may be carried out in the presence of at least one reducing agent selected from the group consisting of ₄ , NaBEt ₃ H and LiBEt ₃ H, but is not particularly limited.

The aromatic nitro compound is not particularly limited as long as it is an aromatic compound including at least one nitro group as a substituent.

In addition, the aromatic nitro compound includes not only a benzene cyclic nitro compound but also a heterocyclic nitro compound and a polycyclic aromatic nitro compound.

The heterocyclic nitro compound is not particularly limited as long as it is a heterocyclic compound containing a nitro group as a substituent. The heterocyclic compound refers to a compound containing one or more other atoms in the ring, and may be, for example, imidazole, furan or pyridine.

The polycyclic aromatic nitro compound is not particularly limited as long as it is a polycyclic aromatic compound containing a nitro group as a substituent. The polycyclic aromatic compound refers to a compound having a condensed ring in which two or more rings are monocyclic in the form of sharing two or more atoms, for example, may be naphthalene or anthracene.

The aromatic nitro compound is not particularly limited, and for example, 2,6-dinitrophenol, 2,4-dinitrophenol, p-nitrophenol, 2,4,6-trinitrophenol and 2-nitropyridine- At least one selected from the group consisting of 3-ols.

In addition, the aromatic amine compound may include not only a benzene ring but also a heterocyclic amine compound and a polycyclic aromatic amine compound, and is not particularly limited as long as it is an aromatic compound containing an amine group.

3 illustrates, as an example, a process for preparing an aromatic amine compound and a recycling process using a metal nanoparticle catalyst supported on a hydrogel of the present invention.

As can be seen in the photo of FIG. 3, the metal nanoparticles prepared in the present invention are less likely to be separated from the matrix during the reaction, and can be stably supported in the matrix of the hydrogel.

In another embodiment, the catalyst according to the invention can be used to oxidize the dye compound, which is a reactant, to produce an oxidative degradation product of the dye compound of interest.

The dye compound is not particularly limited but includes, for example, a heterocyclic compound. Heterocyclic compounds used as dyes include, for example, Fluorone-based compounds, or Rhodamine-based compounds.

The rhodamine-based compound includes rhodamine B, rhodamine 6G, or rhodamine 123 in addition to rhodamine.

As an example of the present invention, it is possible to provide a catalyst having excellent catalytic activity and a recyclable active ingredient supported on a hydrogel.

1 shows a process for preparing a hydrogel according to an embodiment of the present invention.
2 illustrates a process of preparing a metal ion and a metal oxide catalyst supported on a hydrogel according to an embodiment of the present invention.
FIG. 3 illustrates a process for preparing and recycling an aromatic amine compound using a metal nanoparticle catalyst supported on a hydrogel according to another embodiment of the present invention.
4 shows the IR spectrum of an exemplary dry hydrogel of the present invention.
5 shows an NMR spectrum of an exemplary dry hydrogel of the present invention.
6 shows the XPS spectrum of an exemplary dry hydrogel of the present invention.
7 shows an SEM image of an exemplary freeze dried hydrogel of the present invention.
8 illustrates the flexibility of an exemplary hydrogel of the present invention.
9 shows the swelling characteristics of an exemplary hydrogel of the present invention.
10 shows ESR values over temperature and time of an exemplary hydrogel of the present invention.
11 illustrates a process of reducing gold particles inside an exemplary hydrogel of the present invention.
12 shows TEM images and UV-Vis spectra of gold nanoparticles supported on exemplary hydrogels of the present invention.
FIG. 13 shows TEM images and UV-Vis spectra of (a) Au, (b) Ag, (c) Pd, (d) Pt, and (e) Ru nanoparticles supported on exemplary hydrogels of the present invention. .
14 is a UV-vis spectrum measured for the reaction for reducing 2,6-dinitrophenol using a gold nanoparticle catalyst supported on an exemplary hydrogel of the present invention ((a) after addition of NaBH ₄ , (b ) 10 ° C., (c) 30 ° C., and (d) 50 ° C.).
FIG. 15 is a UV-vis spectrum measured for a reaction for reducing 2,4-dinitrophenol using a gold nanoparticle catalyst supported on an exemplary hydrogel of the present invention ((a) after NaBH ₄ addition, (b ) 10 ° C., (c) 30 ° C., and (d) 50 ° C.).
FIG. 16 is a UV-vis spectrum measured for the reaction for reducing p-nitrophenol using gold nanoparticle catalyst supported on an exemplary hydrogel of the present invention ((a) after addition of NaBH ₄ , (b) 10 ° C. , (c) 30 ° C, and (d) 50 ° C).
FIG. 17 is a UV-vis spectrum measured for a reaction for reducing 2,4,6-trinitrophenol using a gold nanoparticle catalyst supported on an exemplary hydrogel of the present invention ((a) after NaBH ₄ addition, ( b) 10 degreeC, (c) 30 degreeC, and (d) 50 degreeC).
18 is a UV-vis spectrum measured for a reaction for reducing 2,6-dinitrophenol using a gold nanoparticle catalyst supported on an exemplary hydrogel of the present invention ((a) after addition of NaBH ₄ , (b ) 30 ° C.).
19 shows reaction rate constants depending on the amount of catalyst in a metal nanoparticle catalyst supported on an exemplary hydrogel of the present invention.
20 shows reaction rate constants according to the amount of NaBH ₄ in a reduction reaction using a metal nanoparticle catalyst supported on an exemplary hydrogel of the present invention.
FIG. 21 shows the change in concentration over time at each temperature with respect to the reduction reaction of the aromatic nitro compound.
Fig. 22 shows the catalyst regeneration performance of the AuNP catalyst for reducing p-nitrophenol.
FIG. 23 shows a photograph of a catalyst having various active ingredients of the present invention supported on a hydrogel. FIG.
FIG. 24 shows a graph in which TGA is used to measure the amount of active ingredient in a catalyst in which various active ingredients of the present invention are supported on a hydrogel.
FIG. 25 is a graph illustrating the resolution of rhodamine 6 in a catalyst in which various active ingredients of the present invention are supported on a hydrogel. FIG.
FIG. 26 is a photograph showing the oxidative decomposition ability of rhodamine 6 of an exemplary Fe (II) -supported catalyst of the present invention.
FIG. 27 is a graph showing the oxidative decomposition ability of rhodamine 6 of an exemplary Fe (II) -supported catalyst according to the amount of catalyst and hydrogen peroxide.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the scope of the present invention is not limited by the following Examples.

[Manufacturing Example]

end. Preparation of Hydrogel (PEOPPA400)

Bifunctional dried in phosphorous oxychloride (20 mmol, 3.04 g) and TEA (triethylamine, 120 mmol, 12.12 g) dissolved in THF (tetrahydrofuran, 100 mL) in a 250 mL two-necked flask equipped with a stirrer PEG400 (poly (ethylene glycol), Mw: 400, 10 mmol, 4.00 g) was added dropwise, and the reaction was stirred for 20 minutes while maintaining the temperature at 5 ° C or lower. Subsequently, PDA (propane-1,3-diamine, 99%, 180 mmol, 13.33 g) was injected into the reaction mixture at room temperature, followed by stirring to precipitate a yellow hydrogel. The separated hydrogel (PEOPPA400) was immersed in distilled water at room temperature for 5 hours, and the distilled water was replaced every hour to leach unreacted material. The hydrogel was then dried under vacuum at 90 ° C. for 2 days to obtain purified hydrogel (PEOPPA400).

I. Hydrogel structure and composition measurement

FT-IR spectra, NMR spectra and XPS spectra for each hydrogel were measured to confirm the structure and components of the hydrogels prepared in the above examples.

4 was confirmed P = O and COC stretching through represents the IR spectrum (measured by a Shimadzu IR Prestige-21), a peak of 1250cm ^-1 and 1104 cm ^-1 on the dry hydrogel (PEOPPA400), 958cm Peaks of ⁻¹ and 730 cm ⁻¹ confirm the presence of PNC binding.

5 relates to an NMR spectrum, analyzed by solid state ³¹ P NMR spectroscopy (Bruker Avance 500 NMR spectrometer, ³¹ P NMR frequency at 202.5 MHz, sample packed in a 4 mm od zirconia rotor), through which The hydrogel prepared in the example can be confirmed whether or not including three different phosphoryl groups.

FIG. 6 shows XPS spectra measured by XPS (ESCALAB 250, VG Scientifics, UK, pass energy of 160 eV, using an aperture slot of 300 × 700 microns), showing N1s and P2p peaks. The N1s peak appearing around 398 eV means that the diamines used in the preparation of the hydrogels each participated in the crosslinking reaction. In addition, the P2p peak appearing around 131 eV indicates the presence of phosphoryl in the hydrogel structure.

7 shows an SEM image of PEOPPA400 freeze dried. For the SEM analysis Samples of the prepared hydrogels were soaked in ultrapure water for at least 48 hours until equilibrium was reached, and the swollen hydrogel samples were freeze dried for 24 hours. Surface morphology analysis of the lyophilized hydrogel was performed by SEM (S-4800, Hitachi, Japan). As can be seen from FIG. 7, the PEOPPA400 hydrogel has an excellent network structure showing a high degree of swelling.

In addition, Figure 8 shows the hydrogel in the swelling state is elongated, it can be seen that it has excellent flexibility. In addition, Figure 9 shows a hydrogel that absorbs water while maintaining the form.

All. Equilibrium swelling ratio (ESR) of hydrogels

The hydrogels prepared in the Examples were swollen in various polar and nonpolar solvents, including water, dimethylformamide (DMF) and hexane solvents, in the temperature range of 22-80 ° C., and the ESR was measured by gravimetric method. At a predetermined temperature within the temperature range, the hydrogel was immersed in each solvent, and after 48 hours, the hydrogel was removed, wiped off with a wet filter paper to remove water from the surface, and then weighed. After measuring ESR at one temperature, the hydrogel was again equilibrated at another temperature for continuous ESR measurements. Five measurements were taken for each sample and averaged, and ESR was calculated as the following general formula.

[Formula 1]

ESR = Ws / Wd

Wherein Ws is the weight of water in the hydrogel swollen at each temperature and Wd is the dry weight of the hydrogel.

10 shows measurement results of ESR of the hydrogel PEOPPA400. Within 30 minutes the value of ESR rose to 22, and over time more water uptake was observed. ESR was also affected by temperature, measured by limiting the time to 30 minutes each, ESR also increased from 10 to 23 with increasing temperature at a temperature of 10 to 30 ℃. At temperatures above 50 ° C., the ESR reached an asymptotic value.

Example 1

Preparation of Gold Nanoparticles (HS-MNP) Supported on PEOPPA Hydrogels

_{^{AuCl 4 -, Ag +, PdCl}} 4 2 -, PtCl 4 2 -, noble metal ions such as Ru ^{3 +} were used to prepare an aqueous solution having a concentration of 0.1 M, respectively. The 0.2 mL solutions were each transferred to 10 mL vials followed by the addition of the dry hydrogel (40 mg) prepared in Preparation Example 1. Because of the high water content of the network, the solution can be completely absorbed into the hydrogel. After a further 5 mL of distilled water was injected, the vial was sealed and held fixed for 24 hours. The formation of the corresponding metal particles was determined by the color change of the hydrogel and UV-Vis spectrometer.

11 and 12 are then added to the _{HAuCl 4 (0.1 M, 0.2 mL} ) in that contains the hydrogel solution, and reducing 24 hours, UV-Vis spectra were demonstrate that the Au ^{3 +} has been fully converted into Au ^0, the The color of the hydrogel changed from colorless to red. Since AuNP does not change in the color of the aqueous solution, it can be seen that it was formed mainly on the surface and the inside of the hydrogel. Free AuNPs, generated on the surface of the hydrogel and washed into the solution, were observed by TEM and measured DLS (Zetasizer, Malvern Instruments) (FIG. 12A). The average diameter of the AuNP was about 10 nm.

Ag, Pd, Pt and Ru nanoparticles immobilized on hydrogels can also be efficiently produced in the same manner as the protocol used for HS-AuNP preparation. The formation of each HS-MNP with a narrow size distribution can be confirmed by TEM image, UV-Vis spectrum and color of the resulting HS-AuNP (FIG. 13). 13 (f) demonstrates that the hydrogels maintain their integrity so that they can easily move between reaction systems even after immobilizing the MNP.

In addition, to accurately determine the amount of MNP inside the hydrogel, the prepared HS-MNP was washed three times with distilled water, and then NP in a clean solution was measured by an ICP mass spectrometer (7500 ICP-MS, Agilent technologies). The actual amounts of AuNP, AgNP, PdNP, PtNP and RuNP corresponding to the inside of the hydrogel were calculated to be 80, 50, 48, 82 and 45 mg per gram of dry PEOPPA hydrogel, respectively.

[Experimental Example 1]

end. Determination of catalytic activity of HS-MNP

Five nitro aromatic compounds (2,6-dinitrophenol, 2,4-dinitrophenol, p-nitrophenol, 2,4,6-trinitrophenol and 2-nitropyridin-3-ol) are 10, 30 and It was selected for the catalytic activity measurement of HS-MNP in the presence of NaBH ₄ at 50 ° C. A typical process for the HS-AuNP catalyst is as follows: Each nitro aromatic solution (4 mL, 1.8 x 10 ^-3 mol / L) is prepared in 10 mL vials and 2 mg of NaBH ₄ is added for each reaction system. Was used. Prior to the addition of HS-AuNP, the solution was analyzed by UV-Vis spectroscopy to confirm the wavelength and peak intensity (0.1 mL of the prepared solution was diluted with 1 mL distilled water in a quartz cell for UV-Vis tracking). . Subsequently, after adding HS-AuNP (4 mg), the solution was analyzed by UV-vis spectroscopy at the specified temperature. Other catalysts were measured in a similar process.

Under neutral or acidic conditions, 2,6-dinitrophenol, 2,4-dinitrophenol, p-nitrophenol, 2,4,6-trinitrophenol and 2-nitropyridin-3-ol solution were found to be 427, 357, Strong absorption peaks are shown at 317, 353 and 330 nm, respectively. With the addition of NaBH ₄ , the alkalinity of the solution increases and the corresponding nitrophenolate and 2-nitropyridine-3-oleate ions react to the spectral shift of the absorption peak at 430, 414, 400, 390 and 397 nm, respectively. It was accompanied by and became dominant. Once HS-AuNP is added, as the reduction reaction proceeds, the characteristic absorption peak, indicating the disappearance of 2,4,6-trinitrophenolate at 390 nm, gradually decreases in intensity. At the same time, with increased reaction time, new absorption peaks begin to appear at lower wavelengths, indicating the production of corresponding aminophenols and 2-aminopyridin-3-ols. The corresponding UV-vis absorption peaks before and after reduction with NaBH ₄ in water using the five nitroaromatic compounds and the hydrogel supported metal nanoparticles as catalysts are illustrated in Table 1 below and FIGS. 14-18 below.

[Table 1]

The effect of the catalyst amount on the reaction rate constant in the reduction of 2,4-dinitrophenyl by NaBH ₄ was measured by slowly increasing the catalyst amount at 50 ° C. Reaction conditions and results are shown in FIG. 19. For all catalysts, the rate constant increases with increasing catalyst amount. Regarding the catalyst value, the amount of the catalyst is designated 4 mg according to each reaction.

Similarly, FIG. 20 demonstrates the effect of NaBH ₄ concentration. As shown in FIG. 17, too low a concentration in NaBH ₄ of 0.23 × 10 ⁻² mol / L causes low reaction conversion. As expected, higher concentrations help to improve reaction conversion. However, when the NaBH ₄ concentration was above 1.32 × 10 ⁻² mol / L, no significant improvement in the rate constant was seen. Therefore, 1.32 × 10 ⁻² mol / L is specified as the appropriate concentration for all reactions.

In addition, Figure 21 shows the concentration change with time at each temperature in the reduction reaction of all the aromatic nitro compounds. In particular, when no HS-AuNP catalyst was added, no reaction was observed at 30 ° C., indicating that the reduction was activated by the added catalyst. Also, it can be seen that the induction time is the shortest at 30 ° C.

I. Recyclability of HS-AuNP

The experiment was performed at 30 ° C. with p-nitrophenol. Free AuNP dispersed in solution without hydrogel carrier was applied for comparison with HS-AuNP. Following one reaction cycle, following one reaction cycle, the relevant catalyst was centrifuged at 14,000 rpm for 30 minutes and then washed three times with water. In the fresh solution, the amount of active AuNPs was measured by UV-Vis tracking before each reaction. The next reaction cycle was started by adding equal concentrations of p-nitrophenol (1.8 × 10 ⁻³ mol / L). The recycling process was repeated 20 times. Two methods were applied to separate the HS-AuNP catalyst from the reaction mixture. That is, centrifugation, washing three times with water and removing directly from the reaction product and washing three times with water before the next cycle use.

In the case of Free AuNP, it is separated only by centrifugation. The percentage loss of active AuNPs was measured by UV-Vis spectroscopy after each catalyst separation and washing.

Fig. 22 shows measurement of catalyst regeneration performance of AuNP catalysts for reducing p-nitrophenol. When separated by centrifugation, the HS-AuNP catalyst retains 82% of active AuNPs, even after 20 cycles. On the other hand, in the case of free AuNP, only 10% active AuNP remained after 20 cycles (Fig. 22 (a)). In addition, HS-AuNP can be separated from the solution by direct removal using a tweezer (FIG. 22 (b)). HS-AuNP maintains high catalytic activity even after repeated cycles because AuNP is immobilized on a hydrogel having structural integrity after separation. However, for free AuNPs, the loss of active AuNPs and the boring work up procedure are unavoidable as the number of cycles increases. In addition, aggregation and oxidation of free AuNPs cannot be avoided.

22 (c) shows that the HS-AuNP catalyst remains active for 20 cycles, but the reaction time gradually increases. Figure 22 (d) also shows that when the reaction time for each cycle is limited to 5 minutes, the conversion rate for HS-AuNP begins to decrease slowly from the fifth cycle.

[Example 2]

Preparation of Nanoparticles (HS-MNP) Supported on Hydrogels

Phosphorous oxychloride (20 mmol, 3.04 g) and TEA (triethylamine, 120 mmol, 12.12 g) dissolved in THF (tetrahydrofuran, 100 mL) in a 250 mL two-necked flask equipped with a mechanical stirrer, dried 2 Functional PEG300 (poly (ethylene glycol), 10 mmol, 3.00 g) was added dropwise while maintaining below 5 ℃. After stirring for 20 minutes, FeSO ₄ , Fe ₂ (SO ₄ ) ₃ , Fe ₂ O ₃ and MnO ₂ powder were added and stirred for 10 minutes. The solution became emulsion, and 1,3-propanediamine (PDA, 180 mmol, 13.33 g) was injected into the reaction mixture at a constant rate at room temperature under vigorous stirring. A solid in the form of a gel containing metal ions or metal oxides was precipitated. The product was washed with water and dehydrated for 2 days in a dynamic vacuum at 60 ° C.

23 shows a photo of the catalyst in which Fe (II), Fe (III), Fe ₂ O ₃ , and MnO ₂ prepared as described above are supported on a hydrogel. In addition, as a result of analyzing the prepared catalysts using a thermogravimetric analyzer (TGA), Fe (II), Fe (III), Fe ₂ O ₃ and MnO ₂ were 12.2, 22.3, 22.5 and 22.9 wt%, respectively. This was confirmed and shown in FIG. 24.

[Experimental Example 2]

Measurement of Rhodamine Degradation Activity of Nanoparticles Supported on Hydrogels (HS-MNP)

25 shows the decomposition ability of Rhodamine 6 over time of the catalyst in which Fe (II), Fe (III), Fe ₂ O ₃ , and MnO ₂ prepared in Example 2 were respectively supported on the hydrogel. According to FIG. 25, Fe (II) was most effective because it showed a decomposition efficiency of 100% within 60 minutes for the catalyst loaded on the hydrogel.

Rhodamine 6G was selected as a model for measuring the catalytic activity prepared in Example 2 in the presence of hydrogen peroxide (H ₂ O ₂ ) in water, and a photograph and UV-vis spectroscopy showing its decomposition ability were shown in FIG. 26 (a). Shown in After 15 minutes of the decomposition reaction, the solution turned colorless and no residue was found. However, as a result of testing without immobilizing Fe (II) on the hydrogel, it was confirmed that some of the rhodamine 6 remained undecomposed (FIG. 26 (b)). It has obvious advantages such as, and convenient driving.

In addition, a graph showing the decomposition ability of Rhodamine 6 of the catalyst loaded with Fe (II) on the hydrogel according to the amount of catalyst (left of FIG. 27) and the amount of hydrogen peroxide (right of FIG. 27) is shown in FIG. 27. As shown in FIG. 27, the amount of catalyst was 300 mg, and the amount of hydrogen peroxide was 7 mL, which was most effective. When the amount of the catalyst exceeds 300 mg, the decomposition efficiency is rather reduced because a large amount of catalyst has a low pH, which adversely affects the decomposition reaction of rhodamine by hydrogen peroxide.

Claims (11)

Hydrogel comprising the following formula 1 as a crosslinking site; And
Catalyst comprising a catalytically active component supported on the hydrogel:
[Chemical Formula 1]

In Formula 1, Y ₁ , Y ₂ and Y ₃ are each independently selected from -O-, -S- or -NH-, and at least one of Y ₁ , Y ₂ and Y ₃ is -S- or -NH - to be.
The method of claim 1,
Hydrogel is a catalyst comprising any one of the following formulas 2 to 4 as repeating units:
(2)

(3)

[Chemical Formula 4]

In the above Chemical Formulas 2 to 4,
R ₁ , R ₃ to R ₆ are alkylene groups of 1 to 30 carbon atoms, R ₂ is an alkyl group of 1 to 30 carbon atoms, L represents a branched structure having X at the terminal, o and p are integers of 1 to 100 X represents the following Chemical Formula 5,
[Chemical Formula 5]

In Formula 5, A ₁ and A ₂ are each independently selected from the group consisting of -NH-, and -S-, and R ₇ and R ₈ are alkylene groups having 1 to 30 carbon atoms.
3. The method of claim 2,
L is a catalyst comprising at least one of the units represented by the following formulas (6) to (8) in the structure:
[Chemical Formula 6]

(7)

[Chemical Formula 8]

3. The method of claim 2,
L is a catalyst comprising a unit represented by the following formula (9):
[Chemical Formula 9]

The method of claim 1,
The catalyst active ingredient is a metal, a metal ion or a metal oxide.
The method of claim 5,
The catalyst active ingredient is a catalyst having an average particle diameter of 2 to 50 nm nanoparticles.
The method of claim 5,
The metal is Au, Pt, Pd, Ir, Rh, Ag, Ru, Al, Cu, Te, Bi, Pb, Fe, Ce, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn And at least one catalyst selected from the group consisting of Ti.
A process for producing an aromatic amine compound, comprising the step of reducing the aromatic nitro compound in the presence of a catalyst according to claim 1.
9. The method of claim 8,
The reduction is NaBH ₄ , LiAlH ₄ , H ₃ NBH ₃ , NaB (CN) H ₃ , NaB (OAc) ₃ H, LiAl (CN) H ₃ , LiAl (OAc) ₃ H, NaB (OCH ₃ ) ₄ , NaBEt A process for preparing a target substance which is carried out in the presence of at least one reducing agent selected from the group consisting of ₃ H and LiBEt ₃ H.
A process for oxidizing or reducing a reactant in the presence of a catalyst according to claim 1.
The method of claim 10,
The reactant is rhodamine or a derivative thereof.

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