KR102255059B1 - Method for preparing high efficiency ceria catalyst for air pollution purification using hydrothermal synthesis - Google Patents

Abstract

The present invention comprises the steps of (a) (i) adjusting the pH by adding a basic substance to a solution containing a cerium precursor and (ii) a zirconium or tin precursor; (b) hydrothermal reaction of the solution obtained in step (a) at a temperature of 120 to 220° C. to form ceria doped with zirconium ions or tin ions; (c) adjusting the pH by adding a basic substance to the solution containing the palladium precursor; (d) adding and stirring the zirconium ion or tin ion-doped ceria to the solution obtained in step (c) to form a zirconium ion or tin ion-doped ceria with palladium compound adsorbed on the surface; And (e) calcining the zirconium ion or tin ion doped ceria on which the palladium compound is adsorbed on the surface to prepare a catalyst powder; , According to the present invention, by adding (doping) a metal ion (Zr or Sn) to ceria, the ion radius difference (Ce ion: 103pm, Zr ion: 72pm, Sn ion: 69pm) according to the type and amount of added metal ion. ), the lattice shrinkage occurs due to the lattice distortion caused by the lattice shrinkage, and the specific surface area increases due to this lattice reduction, and the amount of oxygen participating in the reduction reaction increases due to the increase in surface energy, resulting in the ability to purify air pollutants. A catalyst having excellent phosphorus catalytic activity can be prepared.

Description

Manufacturing method of high efficiency ceria catalyst for air pollution purification using hydrothermal synthesis {METHOD FOR PREPARING HIGH EFFICIENCY CERIA CATALYST FOR AIR POLLUTION PURIFICATION USING HYDROTHERMAL SYNTHESIS}

The present invention relates to a method of manufacturing a ceria catalyst doped with metal ions, and more particularly, to a method of manufacturing a highly efficient ceria catalyst for purifying air pollution using a hydrothermal synthesis method.

In recent years, regulations on environmental pollution have become increasingly severe around the world. Among various pollutions, regulations on air pollution are being further strengthened, and research on the development of nano-catalyst materials having high purification capacity is actively underway in order to maximize the purification capacity of air pollutants.

In particular, cerium oxide, that is, ceria, among catalyst materials is widely known as a three-way catalyst capable of purifying automobile exhaust gas due to its excellent oxidation/reduction reactivity, and the excellent oxidation/reduction reaction of ceria is 4f. It is known that electrons in the -5d orbital have similar energy, so electron exchange can occur relatively easily.

Since nano-sized particles have a higher specific surface area per unit volume compared to conventional bulk-sized particles, a high application possibility can be expected when using a stepping material as a stepping material to purify a pollutant source using nano-sized particles.

There are various methods such as co-precipitation method, hydrothermal synthesis method, solvent heat synthesis method, reverse-micelle method, sol-gel method, etc. to make nano-sized powder. Among them, hydrothermal synthesis method is a simple process to synthesize compounds such as doping products. It is a suitable process, and is well known as an advantageous method for synthesizing nano-powder having crystallinity through control of process parameters such as reaction temperature, reaction time, pH, and type of precursor.

Korean Patent Application Publication No. 10-2016-0121229 (Publication date: 2016.10.19.) Japanese Unexamined Patent Application Publication No. 2004-43226 (Publication date: 2004.02.12.)

The technical problem to be solved by the present invention is to provide a method of manufacturing a material having a more excellent catalytic activity than ceria, which is widely known as a material capable of purifying air pollution.

In order to achieve the above technical problem, the present invention, as shown in Figure 1 (a) (i) cerium precursor and (ii) adding a basic material to a solution containing a zirconium or tin precursor to adjust the pH; (b) hydrothermal reaction of the solution obtained in step (a) at a temperature of 120 to 220° C. to form ceria doped with zirconium ions or tin ions; (c) adjusting the pH by adding a basic substance to the solution containing the palladium precursor; (d) adding and stirring the zirconium ion or tin ion-doped ceria to the solution obtained in step (c) to form a zirconium ion or tin ion-doped ceria with palladium compound adsorbed on the surface; And (e) calcining the zirconium ion or tin ion doped ceria with palladium compound adsorbed on the surface to prepare a catalyst powder; it proposes a method for preparing a metal ion doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method comprising .

In addition, the cerium precursor, the zirconium precursor, the tin precursor, and the palladium precursor are an acetate-based precursor, an alkoxide-based precursor, a halide-based precursor, and an oxyhalide-based precursor. A method of preparing a metal ion doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method, characterized in that it is a precursor or a nitrate based precursor, is proposed.

In addition, the cerium precursor is cerium (III) nitrate (Ce (NO ₃ ) ₃ ), the zirconium precursor is zirconium oxychloride (ZrOCl ₂ · 8H ₂ O), and the tin precursor is tin chloride (SnCl ₄ ). A method of preparing a metal ion-doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method as characterized is proposed.

_{In addition, palladium hydroxide (Pd(OH) 2} ) is precipitated by adding a basic material to a solution containing _{palladium chloride (PdCl 2} ) as a palladium precursor in step (c), and the palladium hydroxide ( Pd(OH) ₂ ) The zirconium ion or tin ion-doped ceria is added to the precipitation solution and stirred to form a zirconium ion or tin ion-doped ceria with palladium hydroxide particles adsorbed on the surface, and in step (e) A catalyst powder having a structure in which palladium oxide is attached on a support made of ceria doped with zirconium ions or tin ions is prepared by calcining zirconium ion or tin ion-doped ceria with palladium hydroxide particles adsorbed on the surface. A method of preparing a metal ion-doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method is proposed.

In addition, in steps (a) and (c), the basic material is ammonium hydroxide (NH ₄ OH), sodium hydroxide (NaOH), or potassium hydroxide (KOH). A method for preparing a ceria catalyst is proposed.

In addition, a method of preparing a metal ion-doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method is proposed, wherein the hydrothermal reaction is performed for 2 to 10 hours.

In another aspect of the present invention, the present invention proposes a catalyst for purifying exhaust gas including a metal ion-doped ceria catalyst for purifying air pollution prepared by the above manufacturing method.

In addition, there is proposed a catalyst for purifying exhaust gas having a structure in which palladium oxide is attached to a support made of ceria doped with zirconium ions or tin ions.

According to the present invention, the ion radius difference (Ce ion: 103pm, Zr ion: 72pm, Sn ion: 69pm) according to the type and amount of added metal ion by adding (doping) metal ion (Zr or Sn) to ceria. The lattice shrinkage occurs due to the lattice distortion caused by the lattice shrinkage, and the specific surface area increases due to this lattice shrinkage, and the amount of oxygen participating in the reduction reaction increases due to the increase in surface energy, resulting in the ability to purify air pollutants. A catalyst having excellent catalytic activity can be prepared.

In addition, according to the present invention, it is possible to economically synthesize a metal ion (Zr or Sn) doped ceria having a high specific surface area and crystallinity through hydrothermal synthesis without a surfactant or additional heat treatment.

1 is a process flow diagram of a method of manufacturing a metal ion doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method according to the present invention.
2 is an XRD measurement result for analyzing the crystallinity of _{Zr x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping in the present embodiment.
3 is an XRD measurement result for analyzing the crystallinity of _{Sn x} Ce _1-x O ₂ nanopowder according to the metal ion doping amount DP in the present embodiment.
4 is an FE-TEM measurement result for analyzing the microstructure of _{Zr x} Ce _1-x O ₂ nanopowder according to the metal ion doping amount in the present embodiment.
5 is an FE-TEM measurement result for analyzing the microstructure of _{Sn x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping in the present embodiment.
6 is a BET measurement result for the specific surface area analysis of _{Zr x} Ce _1-x O ₂ nanopowder according to the metal ion doping amount in the present embodiment.
7 is a BET measurement result for analyzing the specific surface area of _{Sn x} Ce _1-x O ₂ nanopowder according to the metal ion doping amount in the present embodiment.
8 is a result of evaluating the stepping characteristics (H ₂ -TPR) of the PdO@Zr doped CeO ₂ and PdO@Sr doped CeO _{2 catalysts in the present example.}

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

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

The terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate the presence of a set feature, number, step, action, component, part, or combination thereof, but one or more other features or numbers. It is to be understood that the possibility of addition or presence of, steps, actions, components, parts, or combinations thereof is not preliminarily excluded.

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

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

<Example>

To synthesize metal ion (Zr or Sn) doped ceria, the precursors are zirconium oxychloride (ZrOCl ₂ ·8H ₂ O, 99%), tin chloride (SnCl ₄ , 98%), cerium (III) nitrate (Ce ( NO ₃ ) ₃ , 99%) was used. The mixture was mixed with DI Water so that the ratio of "'Zr'and'Sn'to'Ce' was 0, 30, 50, 70 mol%, and stirred at 300 rpm for 30 minutes for uniform mixing. For control, KOH, NaOH or NH ₄ OH is added drop-by-drop, and the pH of each precursor solution is adjusted to 9, 10, 11, and then stirring is carried out at 300 rpm for 1 hour for uniform dispersion of the resulting hydroxide. Each dispersed metal ion aqueous solution was put in a Teflon container and placed in an autoclave and reacted for 2 to 10 hours at a reaction temperature of 120 to 220° C. The reacted solution was mixed with ethanol and distilled water at 5000 rpm using a centrifuge. After washing twice and drying at 100° C. for 24 hours in a dryer, Zr/Sn-doped CeO ₂ powder was recovered.

2 is an XRD measurement result for analyzing the crystallinity of _{Zr x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping. As a result of the analysis, a _{CeO 2} crystal peak with a single-phase Cubic structure ^{was identified for each condition of the Zr 4+} _{ion doping amount of 0 to 50 mol%, and the ZrO 2} phase of the Tetragonal structure was mixed under the condition of 70 mol% Zr ^{4+ ion doping.} I was able to confirm that there was.

3 is an XRD measurement result for analyzing the crystallinity of _{Sn x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping. As a result of the analysis, _{the CeO 2} crystal peak having a single-phase Cubic structure ^{was confirmed up to the conditions of the Sn 4+} _{ion doping amount of 0 and 30 mol%, and SnO 2} of the Tetragonal structure under the condition ^{of the Sn 4+} ion doping amount of 50 and 70 mol%. It was confirmed that crystal peaks were mixed.

4 is an FE-TEM measurement result for analyzing the microstructure of _{Zr x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping. As a result of the analysis, as the Zr ion doping amount increases to 0, 30, 50, 70 mol%, the size of the synthesized particles can be confirmed to decrease from about 15 nm to several nm, through which metal ions are not doped pure water. It was found that when Zr metal ions were doped rather than ceria, the size of the particles became finer as the existing ceria lattice was reduced.

5 is an FE-TEM measurement result for analyzing the microstructure of _{Sn x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping. As a result of the analysis, it was confirmed that fine spherical particles having an average of 10 nm or less were uniformly distributed for each condition, and the size of the synthesized particles gradually decreased as the doping amount increased.

6 is a BET measurement result for the specific surface area analysis of _{Zr x} Ce _1-x O ₂ nanopowder according to the metal ion doping amount. As the Zr ion doping amount increases to 0, 30, 50, 70 mol%, the specific surface area gradually increases to 52.0m ² /g, 132.3m ² /g, 198.9m ² /g, and 226.5m ² /g. there was.

7 is a BET measurement result for analyzing the specific surface area of _{Sn x} Ce _1-x O ₂ nanopowder according to the amount of metal ion doping. As the Sn ion doping amount increases to 0, 30, 50, and 70 mol%, the specific surface area gradually increases to 52.0m ² /g, 78.5m ² /g, 123.5m ² /g, and 174.6m ² /g. there was.

Next, the synthesis of the PdO@Metal doped CeO ₂ catalyst was first mixed with 50 ml of distilled water with 1 wt% of PdCl ₂ (99%, SIGMA-ALDRICH) based on the weight of the previously synthesized Zr/Sn-doped CeO _{2 support nanopowder.} Stirring was performed at 300 rpm for 30 minutes. After stirring, NH ₄ OH was added in a drop by drop format to adjust the pH to 4.6 or higher, which is an appropriate pH at which precipitation of _{Pd(OH) 2 occurs, followed by stirring at 300 rpm for 30 minutes for uniform dispersion. In addition, 0.5 g of metal-doped CeO 2} support nano-powder having relatively excellent specific surface area characteristics was _{added, followed by stirring so that Pd(OH) 2} may be properly adsorbed on the surface of the support, followed by aging. Then, the powder was recovered by drying at 100° C. for 24 hours in a dryer, and then calcined at 500° C. for 3 hours using a furnace _{to synthesize PdO@Metal doped CeO 2} catalyst powder.

8 is a result of evaluating the stepping characteristics (H ₂ -TPR) of PdO@Zr-doped CeO ₂ and PdO@Sr-doped CeO _{2 catalysts.} The pure ceria catalyst hydrogen consumption was found to be 243 μmol/g. On the other hand, _{the hydrogen consumption of the PdO@Zr 0.5} Ce _0.5 O ₂ catalyst was found to have excellent catalytic activity of 104 365 μmol/g at a high temperature of 500°C or higher, and PdO@Sr doped CeO ₂ was 222 502 μmol at a high temperature of 600°C or higher. The catalytic activity of the excellent characteristics of /g was confirmed.

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

Claims (8)

(a) adjusting the pH by adding a basic substance to a solution containing (i) a cerium precursor and (ii) a zirconium or tin precursor;
(b) hydrothermal reaction of the solution obtained in step (a) at a temperature of 120 to 220° C. to form ceria doped with zirconium ions or tin ions;
(c) adjusting the pH by adding a basic substance to the solution containing the palladium precursor;
(d) adding and stirring the zirconium ion or tin ion-doped ceria to the solution obtained in step (c) to form a zirconium ion or tin ion-doped ceria with palladium compound adsorbed on the surface; And
(e) preparing a catalyst powder by calcining zirconium ion or tin ion-doped ceria on which a palladium compound is adsorbed on the surface; including,
The cerium precursor is cerium (III) nitrate (Ce (NO ₃ ) ₃ ), the zirconium precursor is zirconium oxychloride (ZrOCl ₂ ·8H ₂ O), and the tin precursor is tin chloride (SnCl ₄ ),
In the step (c), palladium _{hydroxide (Pd(OH) 2} ) is precipitated by adding a basic substance to a solution containing _{palladium chloride (PdCl 2) as a palladium precursor,}
In the step (d), the _{zirconium ion or tin ion-doped ceria is added and stirred to the palladium hydroxide (Pd(OH) 2} ) precipitation solution, and the palladium hydroxide particles are adsorbed on the surface of the zirconium ion or tin ion-doped ceria To form,
Catalyst powder having a structure in which palladium oxide is adhered on a support made of ceria doped with zirconium ions or tin ions by calcining zirconium ion or tin ion-doped ceria with palladium hydroxide particles adsorbed on the surface in step (e) Characterized in that to manufacture,
A method for producing a metal ion-doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method. delete delete delete The method of claim 1,
In the steps (a) and (c), the basic material is ammonium hydroxide (NH ₄ OH), sodium hydroxide (NaOH), or potassium hydroxide (KOH). Method of manufacturing. The method of claim 1,
The hydrothermal reaction is a method for producing a metal ion doped ceria catalyst for purifying air pollution using a hydrothermal synthesis method, characterized in that carried out for 2 to 10 hours. delete delete

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