KR20210066068A - Method for preparing bead type catalyst comprising catalytically active metal supported by metal oxide - Google Patents

Abstract

The present invention relates to a method for preparing a catalytically active metal-supported metal oxide bead catalyst, including the steps of: (a) preparing a catalytically active metal-supported metal oxide; (b) adding a solution containing the catalytically active metal-supported metal oxide and an alginate-based polymer to a calcium ion (Ca^2+) solution to form spherical beads; (c) surface-treating the catalyst beads by using an acid; and (d) drying and heat treating the catalyst beads. The present invention also relates to a catalytically active metal-supported metal oxide bead catalyst prepared by the method. According to the present invention, it is possible to prepare spherical oxide bead particles including at least one metal oxide support supported with catalytically active metal nanoparticles, such as gold (Au), in a simple manner. The oxide bead catalyst supported with the catalytically active metal, such as gold (Au), prepared according to the present invention can be used as a catalyst for oxidation of harmful organic compounds in exhaust gas to remove harmful exhaust gas compounds, such as carbon monoxide, effectively.

Description

Method for producing a catalytically active metal-supported metal oxide bead catalyst {METHOD FOR PREPARING BEAD TYPE CATALYST COMPRISING CATALYTICALLY ACTIVE METAL SUPPORTED BY METAL OXIDE}

The present invention relates to a method for preparing a catalyst in the form of beads including an oxide carrying a metal catalyst such as gold (Au), which can be used to remove air pollutants such as harmful gas compounds.

With the development of the chemical industry, a lot of attention is focused on the technology to cope with chemical accidents and the resulting leakage and occurrence of hazardous compounds. As a method for removing harmful gas compounds, there are various methods such as adsorption, absorption, plasma treatment, and catalytic oxidation. Among them, the technology of removing harmful compounds through catalytic oxidation is in the spotlight because it can remove a large amount of harmful compounds for a long time through an economical and stable catalytic process. In particular, in order to remove carbon monoxide, a harmful toxic gas molecule, a catalyst in which metal particles are dispersed in a catalyst support is used. In order to achieve the desired conversion performance, noble metals (gold, platinum, palladium, etc.) and transition metals (Cu, Ni, Co etc.) are dispersed.

Among the metals used as the catalyst, gold (Au) was previously known to have no catalytic activity, but it was found that when the size of gold particles was reduced to a nanometer level, it showed excellent activity in chemical reactions such as carbon monoxide oxidation. In particular, it is known that carbon monoxide oxidation reaction activity is very high when gold nanoparticles are highly dispersed in an oxide support of titanium dioxide. Gold, known as a precious metal, has a fixed reserve and production amount, and its price is very high, so it is preferable to use it by reducing the amount of gold used or maximizing the activity per unit weight by highly dispersing it in an oxide support that can help the catalytic reaction. In addition, in order to apply the prepared catalyst to the actual process, it is necessary to prepare a catalyst molded in a shape that can minimize the pressure drop and maximize the diffusion and surface reaction of the reactants. Therefore, in the case of an oxide catalyst on which gold particles are supported, nanometer-sized gold particles are highly dispersed, and it is essential to prepare a catalyst molded to a millimeter (mm) level so that it can be applied in an actual process.

In the conventional method for preparing a molded catalyst, first, a catalyst in powder form is prepared by impregnating a metal precursor and an oxide carrier by an impregnation method or a precipitation method, and then using various binders and additives to prepare a molded catalyst using a molding apparatus. Although this method has an intuitive manufacturing method and is suitable for mass production, there are disadvantages in that gold particles, which are noble metal active metals, may not be evenly dispersed during the manufacturing process, and the utilization of the active metal may be low.

Korean Patent Registration No. 10-1046314 (Registration Date: 2011.06.28) US Patent Publication US 2012-0263633 A1 (published date: 2012.10.18) US Patent Publication US 2013-0183221 A1 (published date: 2013.07.18)

An object of the present invention is to provide a method for preparing a catalyst in the form of beads in which an active metal is supported on a metal oxide support. In particular, to provide a catalyst manufacturing technology having a simple manufacturing process of an oxide bead catalyst supported with a catalytically active metal such as gold (Au), optimized properties, uniform particle size, and high carbon monoxide conversion. do.

In order to achieve the above technical problem, the present invention comprises the steps of (a) preparing a catalytically active metal supported metal oxide; (b) preparing a spherical catalyst bead by adding a solution containing the catalytically active metal-supported metal oxide and alginate-based polymer to a calcium ion (Ca ^{2+ ) solution;} (c) surface-treating the catalyst beads with an acid; and (d) drying and heat-treating the catalyst beads; proposes a method for preparing a catalyst for catalytically active metal-supported oxide beads (FIG. 1).

In step (a), in preparing the metal oxide on which the catalytically active metal is supported, the catalytically active metal precursor and the metal oxide are mixed through wet impregnation, etc., and then heat-treated to reduce the catalytically active metal ions. Catalytically active metal particles may be supported on the metal oxide.

In this case, the catalytically active metal precursor is gold (Au), silver (Ag), platinum (Pt), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), iron ( Fe), nickel (Ni), cobalt (Co), may be a precursor of a noble metal or a transition metal such as copper (Cu), for example, the gold precursor is HAuCl ₄ , Na(AuCl ₄ ) and AuCl ₃ One selected from or more, the silver precursor may be at least _{one selected from among AgNO 3} , CH ₃ COOAg and CH ₃ CH(OH)COOAg, and the platinum precursor is H ₂ PtCl ₆ , PtCl ₄ and Pt(NH ₃ ) ₂ (NO ₂ ) It may be at least one selected from among.

In addition, the metal oxide is one selected from the group consisting of titania (TiO ₂ ), ceria (CeO ₂ ), alumina (Al ₂ O ₃ ), silica (SiO ₂ ), zirconia (ZrO ₂ ) and zeolite (zeolite) It is preferably more than, but not necessarily limited to these oxides, MgO, CrO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , CuO, ZnO, CaO, Sb ₂ O ₄ , Co ₃ O ₄ , Pb ₃ O ₄ , Mn ₃ O ₄ , Ag ₂ O ₂ , Cu ₂ O, Li ₂ O, Rb ₂ O, Ag ₂ O, BeO, CdO, GeO ₂ , HfO ₂ , PbO ₂ , MnO ₂ , TeO ₂ , SnO ₂ , La ₂ It may consist of one or more metal oxides selected from _{O 3} , WO ₂ , UO ₂ , ThO _{2 , MoO 3} , and the like.

On the other hand, in step (a), it is also possible to support the catalytically active metal particles on the metal oxide by further mixing the metal oxide precursor in addition to the catalytically active metal precursor and the metal oxide and then performing heat treatment to reduce the catalytically active metal ions.

That is, by heat-treating a mixture including a catalytically active metal precursor, a first metal oxide precursor, and a second metal oxide, a composite in which a catalytically active metal is supported on a metal oxide including the first metal oxide and the second metal oxide can be formed. .

In this case, the type of the first metal oxide precursor is not particularly limited as long as it is a precursor capable of forming a metal oxide different from the second metal oxide.

Next, in step (b), after preparing a solution containing the catalytically active metal-carrying metal oxide and an alginate-based polymer prepared in step (a), the solution is used as a solution containing calcium ions (Ca ²⁺ ) by dropwise method, etc. to prepare a spherical catalyst bead having a structure in which the catalytically active metal-supported metal oxide particles are surrounded by a gelled alginate-based polymer.

Alginate-based polymers composed of 1-4 glycosidic linkages of α-L-gluronic acid and β-D-mannuronic acid and β-D-mannuronic acid contain anionic carboxyl groups. Therefore, it ^{reacts with the cation Ca 2+} to form an irreversible insoluble gel film on the surface of the catalytically active metal-carrying metal oxide particle to obtain a catalyst in the form of spherical beads.

In this case, the alginate-based polymer may be used by selecting one or more types of water-soluble sodium alginate, potassium alginate, ammonium alginate, and triethanolamine alginate, etc., and the alginate-based polymer The calcium ion solution reacting with may be composed of a calcium chloride or calcium lactate solution, but is not necessarily limited thereto.

Subsequently, in step (c), a process of treating the surface of the catalyst bead using an acid such as hydrochloric acid is performed, and in step (d), drying and heat treatment of the surface-treated catalyst bead are performed to finally provide the present invention. A catalytically active metal-supported oxide bead catalyst is obtained.

As an example of the method for producing a catalytically active metal-supported oxide bead catalyst according to the present invention, the method for producing an oxide bead catalyst carrying gold (Au) as a catalytically active metal is (a) titanium dioxide powder using a wet impregnation method heat-treating a mixture prepared by uniformly supporting 0.1 to 1 wt% of a gold precursor and 10 wt% or less of a ceria precursor on the mixture at 400 to 500°C; (b) preparing a spherical catalyst bead by mixing the mixture heat-treated in step (a) with an alginate-based polymer compound in distilled water and then dropwise in a calcium ion solution; (c) treating the surface of the spherical catalyst beads by adding a hydrochloric acid solution; and (d) drying the spherical catalyst beads and then heat-treating them at 600 to 800° C. to finally obtain an oxide bead catalyst carrying gold (Au) ( FIG. 2 ).

The catalytically active metal-supported oxide bead catalyst prepared by the method according to the present invention may contain 0.1 to 10 wt % of catalytically active metal particles having a particle diameter of 0.1 to 10 nm, in particular, gold (Au) as a catalytically active metal. The bead catalyst carrying the toxic gas exhibits excellent activity as a catalyst in the oxidation reaction of carbon monoxide (CO), a harmful toxic gas molecule.

According to the present invention, spherical oxide bead particles in which catalytically active metal nanoparticles such as gold (Au) are supported on one or more metal oxide carriers can be easily prepared, and a bead catalyst of a uniform size can be prepared, The oxide bead catalyst prepared by the present invention on which a catalytically active metal such as gold (Au) is supported is used as a catalyst for oxidizing harmful exhaust organic compounds, and can effectively remove harmful exhaust gas compounds such as carbon monoxide.

1 is a process flow diagram sequentially illustrating each step of the method for preparing a catalyst for catalytically active metal-supported oxide bead according to the present invention.
2 is a schematic diagram showing a method for preparing a gold (Au) supported oxide bead catalyst prepared in Examples of the present application.
3 is a digital camera observation result for each size of the titanium dioxide bead carrier prepared in Example of the present application.
4 is a digital camera observation result of ceria-titanium dioxide carrier bead particles and gold-ceria-titanium dioxide oxide bead catalyst prepared in Example of the present application.
5 is an energy dispersive X-ray analysis result of the gold-ceria-titanium dioxide bead catalyst prepared in Examples of the present application.
6 is a θ-2 θ curve according to X-ray diffraction analysis of the gold-ceria-titanium dioxide catalyst and the gold-supported oxide bead catalyst prepared in Examples of the present application.
7 is a CO oxidation result showing the catalytic and chemical performance of the gold-supported oxide bead catalyst (gold-ceria-titanium dioxide bead catalyst) prepared in Examples of the present application and the conventional gold-supported titanium dioxide catalyst (gold-titanium dioxide bead catalyst). indicates.

In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Since the embodiment according to the concept of the present invention may have various changes and may have various forms, specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiment according to the concept of the present invention with respect to a specific disclosed form, and should be understood to include all changes, equivalents or substitutes included in the spirit and scope of the present invention.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate that the described feature, number, step, operation, component, part, or a combination thereof exists, and includes one or more other features or numbers. , it is to be understood that it does not preclude the possibility of the presence or addition of steps, operations, components, parts, or combinations thereof.

Hereinafter, the present invention will be described in more detail by way of examples.

Embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present specification to those of ordinary skill in the art.

<Example>

In this embodiment, after calcining the powder introduced with titanium dioxide and another oxide precursor (ceria precursor), a viscous mixture is made using a sodium alginate solution, and dropped into a calcium ion solution to prepare spherical oxide bead particles, heat treatment Thereafter, a high-efficiency gold-supported spherical catalyst (gold-ceria-titanium dioxide oxide bead catalyst) capable of effectively removing catalytic oxidation of harmful gas compounds by supporting gold was prepared.

1. Preparation of titanium dioxide type 1 oxide beads

Add 2 g of titanium dioxide powder to a mixture of 0.5 g of alginate polymer dissolved in 50 ml of distilled water, and stir until fully dissolved. After stirring for more than 6 hours, use a syringe pump to drop 2 g of calcium ions and 98 ml of distilled water into the mixture. After putting the synthesized titanium dioxide beads in the form of beads in 100 ml of 1M hydrochloric acid, the surface is acid-treated by stirring for 1 hour. The titanium dioxide beads that have undergone the surface acid treatment process are thoroughly washed with water and ethanol. After heating the bead-shaped titanium dioxide beads of uniform size at 5°C per minute to the final 600°C, the firing process is carried out for 2 hours.

3 is an observation of the size of particles synthesized by varying the amounts of titanium dioxide powder, distilled water, and alginate polymers, respectively, through an optical microscope. As can be observed in FIGS. 3a and 3b, it can be confirmed that the bead-shaped particle size increases as the amount of added alginate polymer and titanium dioxide increases. 3c, as the amount of distilled water increases, the particle size decreases. As the distilled water increases when synthesizing beads, the relative concentration of the alginate polymer decreases, the viscosity decreases, and the particle size is determined accordingly. This is because the size of the oxide-alginate droplets becomes smaller.

2. Preparation of ceria-titanium dioxide mixed oxide beads

_{Dissolve 1.5494 g of Ce(N0 3} ) ₃ as a ceria precursor in 5 ml of ethanol, add 2 g of titanium dioxide powder (TiO ₂ ), and place a plastic spoon on the 70℃ electric heater so that Ce(N0 ₃ ) _{3 is sufficiently mixed.} use to mix. Ce(N0 ₃ ) ₃ Mixed titanium dioxide powder is put in a calciner, and the temperature is raised at 5 °C per minute, and the calcination process is carried out for 2 hours to a final 400 °C. 2 g of titanium dioxide powder loaded with 10% ceria is added to a mixture of 0.5 g of alginate polymer dissolved in 50 ml of distilled water and stirred until fully dissolved. After stirring for more than 6 hours, use a syringe pump to drop 2 g of calcium ions and 98 ml of distilled water into the mixture. After putting the synthesized ceria-titanium dioxide beads in 100 ml of 1M hydrochloric acid, they are stirred for 1 hour to carry out surface acid treatment. The ceria-titanium dioxide beads that have undergone the surface acid treatment process are sufficiently washed with water and ethanol. After heating the bead-shaped ceria-titanium dioxide beads of uniform size at 5°C per minute to the final 600°C, the firing process is carried out for 2 hours.

3. Preparation of gold-ceria-titanium dioxide oxide bead catalyst

To take advantage of the impregnation method, it was dissolved in ethanol 5ml 10mg HAuCl _4, wherein 2. the ceria prepared in-titanium dioxide powder (CeO ₂ -TiO ₂₎ gave after putting an additional 2g in 70 ℃ HAuCl ₄ is sufficiently blend Mix using a rock plastic spoon. The temperature was raised to 5 ℃ per minute, and finally, the temperature was raised to 400 ℃, and the firing process was carried out for 2 hours. 2 g of the formed 1% gold-supported ceria-titanium dioxide powder is added to a mixture obtained by dissolving 0.5 g of alginate polymer in 50 ml of distilled water and stirred until sufficiently dissolved. After stirring for more than 6 hours, use a syringe pump to drop 2 g of calcium ions and 98 ml of distilled water into the mixture. After putting the synthesized gold-ceria-titanium dioxide beads in the form of beads in 100 ml of 1M hydrochloric acid, the surface is acid-treated by stirring for 1 hour. The gold-ceria-titanium dioxide beads that have undergone the surface acid treatment process are sufficiently washed with water and ethanol. After heating the bead-shaped ceria-titanium dioxide beads of uniform size at 5°C per minute to the final 600°C, the firing process is carried out for 2 hours.

4 is an image of bead-shaped gold-ceria-titanium dioxide measured with a digital camera. As can be seen in the figure, it can be seen through the blue color that the gold particles are supported and dispersed on the ceria-titanium dioxide particles.

FIG. 5 is a wavelength dispersion type fluorescence X-ray spectroscopy analysis of the gold-supported ceria-titanium dioxide bead catalyst of FIG. 4, and it can be seen that 1 wt% of gold is supported on ceria-titanium dioxide.

6 is a θ-2 θ curve according to X-ray diffraction analysis of a 1 wt% gold-supported ceria-carbon dioxide catalyst having a bead shape prepared by the method of the present invention. It was confirmed that the peak of the gold-ceria-titanium dioxide XRD curve in the form of beads is the same as that of the gold-ceria-titanium dioxide in powder form. It means that it will show catalytic performance.

The carbon monoxide oxidation reaction activity of the gold-ceria-titanium dioxide bead catalyst prepared through the present invention was measured, and the results are shown in FIG. 7 . In order to test the activity of the catalyst, the test was conducted in a laboratory-scale continuous gas phase oxidation reaction system. When the reaction temperature was gradually increased from 50°C to 200°C, it was confirmed that 100% of carbon monoxide was removed from around 160°C. This means that it has excellent catalytic performance.

According to the present invention described above, spherical oxide bead particles in which catalytically active metal nanoparticles such as gold (Au) are supported on one or more metal oxide carriers can be easily prepared, and a bead catalyst of a uniform size can be prepared. , the oxide bead catalyst prepared by the present invention on which a catalytically active metal such as gold (Au) is supported is used as a catalyst for oxidizing harmful exhaust organic compounds, and can effectively remove harmful exhaust gas compounds such as carbon monoxide.

The present invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains can take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (10)

(a) preparing a metal oxide on which a catalytically active metal is supported;
(b) preparing a spherical catalyst bead by adding a solution containing the catalytically active metal-supported metal oxide and alginate-based polymer to a calcium ion (Ca ^{2+ ) solution;}
(c) surface-treating the catalyst beads with an acid; and
(d) drying and heat-treating the catalyst beads; a method for preparing a catalyst for catalytically active metal-supported oxide beads. According to claim 1,
Method for producing a catalytically active metal-supported oxide bead catalyst, characterized in that by heat-treating a mixture comprising a catalytically active metal precursor and a metal oxide in step (a) to form a metal oxide on which a catalytically active metal is supported. According to claim 1,
Catalytically active metal supported oxide bead catalyst, characterized in that the catalytically active metal supported metal oxide is formed by heat-treating a mixture including the catalytically active metal precursor, the first metal oxide precursor, and the second metal oxide in step (a) manufacturing method. According to claim 1,
The catalytically active metal is a method for producing a catalytically active metal-supported oxide bead catalyst, characterized in that it consists of one metal selected from noble metals and transition metals, a mixture of two or more metals, or an alloy of two or more metals. According to claim 1,
The metal oxide is at least one selected from the group consisting _{of titania (TiO 2} ), ceria (CeO ₂ ), alumina (Al ₂ O ₃ ), silica (SiO ₂ ), zirconia (ZrO _{2 ) and zeolite.} A method for producing an oxide bead catalyst supported on metal catalyst particles. According to claim 1,
Through the gelation reaction between the carboxyl group and calcium ion of the alginate-based polymer in step (b), a catalytically active metal-supported oxide bead catalyst, characterized in that to prepare a spherical catalyst bead comprising a metal oxide supported with a catalytically active metal manufacturing method. According to claim 1,
The alginate-based polymer is a catalytically active metal support, characterized in that at least one selected from the group consisting of sodium alginate, potassium alginate, ammonium alginate and triethanolamine alginate. A method for preparing an oxide bead catalyst. A catalytically active metal-supported oxide bead catalyst prepared according to the method of any one of claims 1 to 7. 9. The method of claim 8,
Catalytically active metal-supported oxide bead catalyst, characterized in that it is a catalyst for carbon monoxide (CO) oxidation. 9. The method of claim 8,
Catalytically active metal-supported oxide bead catalyst comprising 0.1 to 10 wt% of catalytically active metal particles having a particle diameter of 0.1 to 10 nm.

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