KR20190125086A - Method for manufacturing exhaust gas purifying catalyst and the exhaust gas purifying catalyst therefrom - Google Patents

Abstract

The present invention relates to a catalyst for purifying exhaust gas in which a noble metal catalyst is supported on a carrier and, more specifically, to a method for producing a catalyst for purifying exhaust gas with improved catalyst durability and exhaust gas purification performance and a catalyst for purifying exhaust gas formed by the producing method. The method produces the catalyst for purifying exhaust gas by: producing a zirconia (ZrO_2) carrier formed with a monoclinic crystal phase and a tetragonal crystal phase by aging at low temperatures below 100°C; and supporting a palladium metal catalyst. The present invention is able to solve performance and durability degradation problems caused by changes in electrochemical properties of novel metal catalysts by controlling the electrochemical properties of novel metal catalysts through interaction between a carrier and novel metal.

Description

Method for producing catalyst for purifying exhaust gas and catalyst for purifying exhaust gas formed through the same {METHOD FOR MANUFACTURING EXHAUST GAS PURIFYING CATALYST AND THE EXHAUST GAS PURIFYING CATALYST THEREFROM}

The present invention relates to a catalyst for automobile exhaust gas purification, and more particularly, in a catalyst for exhaust gas purification in which a noble metal catalyst is supported on a carrier, the performance and durability deterioration due to a change in electrochemical properties of the noble metal catalyst may be reduced between the carrier and the precious metal. The present invention relates to a method for preparing an exhaust gas purification catalyst having improved durability and exhaust gas purification performance by controlling electrochemical properties of a noble metal catalyst through interaction, and an exhaust gas purification catalyst formed through the same.

Catalysts for the purification of automobile exhaust gases are catalysts for converting automobile exhaust pollutants such as hydrocarbons, carbon monoxide and nitrogen oxides into harmless N ₂ , H ₂ and CO ₂ , and these catalysts are generally platinum as an active ingredient of catalysts in porous carriers. It consists of noble metals such as (Pt), rhodium (Rh) and palladium (Pd).

Among the precious metals, the catalyst using palladium (Pb) has a very good performance in purifying carbon monoxide and hydrocarbons, and has a lower cost than other precious metals such as platinum, so it is a catalyst for purifying exhaust gas of natural gas or gasoline vehicles using palladium. Development is active.

In addition, the porous carrier supporting such a noble metal catalyst is a porous oxide support, which is generally suitable for a material having excellent thermal stability even at high temperatures and capable of maintaining a high specific surface area.Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO ₂ and TiO ₂ Or their oxide complexes are mainly used, and the adsorption-desorption performance of these materials affects the purification efficiency of the exhaust gases, and therefore, there is still a pursuit to increase the efficacy of these materials.

Zirconia (ZrO ₂ ), which is used as a porous carrier for the catalyst for exhaust gas purification, may exist in three crystalline phases, such as monoclinic, tetragonal, and cubic, depending on the firing temperature. Specifically, the zirconia crystal phase is present as a monoclinic (monoclinic) crystal phase at a temperature of 1100 ℃ or less, the zirconia crystal phase is present as a tetragonal crystal phase from 1100 ℃ to 2300 ℃, the zirconia melting point of about 2600 ℃ Up to < RTI ID = 0.0 > C < / RTI > In the zirconia (ZrO ₂ ) crystal phase, tetragonal and cubic crystal phases are known to have better physical and chemical properties than monoclinic crystal phases.

However, as described above, the conventional tetragonal crystal phase of zirconia (ZrO ₂ ) uses a method synthesized at a high temperature of 1100 ° C. or higher, which makes it difficult to standardize the manufacturing process and to mass-produce the process. It was.

Compressed Natural Gas (hereinafter referred to as 'CNG') engines operating in a Lean Burn engine is an exhaust gas purification catalyst for CNG vehicles, carrying precious metals including platinum (Pt) and palladium (Pd). Compressed natural gas automobile exhaust gas purification catalyst is applied to perform oxidative purification of methane, a main component of natural gas.

Specifically, the reaction of methane (CH ₄ ) in the palladium catalyst supported on the carrier, as shown in Figure 1, first methane (CH ₄ ) molecules are palladium (Pd)-palladium oxide (PdO) catalytic reaction site site When approached at, it binds to the palladium (Pd) position, and then hydrogen (H) atoms of the methane molecule are bonded to the oxygen vacancy portion of the nearby palladium oxide (PdO). Methane is then converted to convert palladium oxide (PdO) to Pd-OH, which is then reduced to palladium (Pd).

The conversion reaction of palladium (Pd) and palladium oxide (PdO) is reversible, but only when there is only methane (CH ₄ ) or oxygen (O ₂ ). In actual compressed natural gas vehicles, in addition to the engine operating conditions and methane, nitrogen, water vapor oxygen, etc. There are several gas components, and due to their interruption, the conventional CNG vehicle exhaust gas purification catalyst is reversible due to the durability of the catalyst, that is, the deactivation of the catalyst, and the conversion reaction of palladium (Pd) and palladium oxide (PdO) is not reversible. As the mileage of the vehicle increases, it fails to maintain the proper Pd ⁰ / Pd ^{2 +} ratio required for the reaction, and Pd ^{2 +} is reduced to Pd ⁰ , resulting in a problem that the purification performance of the exhaust gas is deteriorated.

J.N.carstens, S.C. Su, A.T. Bell, J. Catal. 176 (1998) 136. S.C. Su, J.N.carstens, A.T. Bell, J. Catal. 176 (1998) 125.

In view of the above problems, the present invention is a zirconia (ZrO ₂ ) consisting of a monoclinic crystal phase and a tetragonal crystal phase by aging at a low temperature of less than 1000 ° C. as a carrier in an exhaust gas purification catalyst. By preparing a carrier and supporting a palladium catalyst, the catalyst for purifying exhaust gases that can improve not only the durability but also the purification performance of the catalyst through electrochemical property control of the noble metal (palladium) by the electrochemical interaction between palladium and the carrier An object of the present invention is to provide a catalyst for purifying exhaust gases formed through the preparation method and the preparation method thereof.

Method for producing a catalyst for purifying exhaust gas of the present invention for achieving the above object, as shown in Figure 2 (a) step of mixing the basic solution in an aqueous solution containing a zirconium precursor to form a precipitate (S110) ), (b) aging the precipitate formed in step (a) to produce a zirconia (ZrO ₂ ) carrier (S120), (c) washing and drying the prepared zirconia carrier (S130), (d) calcining the dried zirconia carrier (S140), (e) supporting palladium on the zirconia carrier (S150), (f) calcining the catalyst for purifying exhaust gas formed by supporting palladium on the zirconia carrier ( S160) may be included.

The step (a) (S110) and (b) step (S120) is a step for preparing a zirconia (ZrO ₂ ) carrier for supporting a palladium catalyst.

First, step (a) comprises forming a precipitate by mixing into a precipitation agent in a basic solution to the Zr precursor solution obtained by dissolving a zirconium precursor in distilled water, in particular of zirconium oxychloride octahydrate (ZrOCl ₂ · 8H ₂ O) as a Zr precursor to Zirconium hydroxide (Zr (OH) ₄ nH ₂ O) may be formed as a precipitate by adding and mixing a basic solution so that the pH of the aqueous solution of zirconium precursor dissolved in distilled water is adjusted to 9 to 10. If the pH of the aqueous solution of zirconium precursor is out of the above range, the pH is not uniformly precipitated, and some of the zirconium precursor solution remains in an ionic state without precipitation, thus lowering the productivity of the catalyst and lowering the efficiency of the final produced catalyst. It is preferable to adjust the concentration range, and it is more preferable that the pH concentration of the zirconium precursor aqueous solution is adjusted to 9.5.

Here, as the basic solution, aqueous ammonia (NH ₄ OH) or sodium hydroxide (NaOH) may be used. The content of the basic solution is not limited but may be added to the aqueous solution of zirconium precursor until it satisfies the suggested pH concentration.

Then (b) step (S120) is a step of preparing an zirconia (ZrO ₂ ) carrier consisting of a specific crystal structure by aging the aqueous solution containing the precipitate formed in the step (a) at a predetermined temperature conditions (aging).

Specifically (b) step (S120) is a monoclinic system (aging) by aging (zr) (Zr (OH) ₄ nH ₂ O) of the precipitate formed at a temperature of 30 ℃ or more and less than 70 ℃ for 48 hours or less ) Zirconia (ZrO ₂ ) carrier comprising a crystal phase and a tetragonal crystal phase can be prepared.

In the step (b) (S120), if the aging temperature and time is out of the above-mentioned range, the crystal structure of the zirconia (ZrO ₂ ) carrier to be prepared may not be properly produced, thus satisfying the above-mentioned range. desirable.

The crystalline structure of the zirconia carrier formed through step (b) (S120) is preferably more than 0 vol% and less than 65 vol% of the tetragonal crystal phase with respect to the total composition of the zirconia carrier, more preferably It is preferable to include more than 0 vol% and less than 15 vol%.

If the tetragonal crystal phase content is 65 vol% or more, since the low-temperature methane (CH ₄ ) oxidation activity is rather reduced, it is preferable that the tetragonal crystal phase composition satisfies the above-mentioned range.

The step (c) (S130) is a step of washing and drying the prepared zirconia carrier, washing foreign substances such as basic solution remaining on the surface of the prepared zirconia carrier with water, and washing the washed zirconia carrier at 24 to 50 to 70 ℃ It is a step of drying under time. Preferably, the drying conditions of the zirconia carrier are preferably dried at 60 ° C. for 24 hours, but are not limited thereto and may be variously modified by those skilled in the art.

The step (d) (S140) is a step of calcining the dried zirconia carrier through the step (c) (S130) to obtain a final zirconia carrier, which is carried out by heating the dried zirconia carrier to a high temperature in an air or oxygen atmosphere Can be.

Specifically (d) step (S140) is preferably carried out for 2 hours to 10 hours at 300 ℃ to 700 ℃, more preferably may be carried out for 6 hours at 600 ℃. If the firing of step (d) (S140) is carried out at a temperature of less than 300 ℃, impurities are not sufficiently removed in the zirconia carrier due to the low firing temperature, due to excessively high temperature at a temperature exceeding 700 ℃ Since the catalyst particles are sintered and a problem of deterioration of the catalyst performance for exhaust gas purification occurs, it is preferable to satisfy the above-mentioned range.

Wherein (e) step (S150) is a step of supporting palladium as a noble metal catalyst on the zirconia carrier, the palladium precursor solution dissolved in distilled water can be supported on the zirconia carrier to form a catalyst for purification of exhaust gas, preferably zirconia The carrier may be supported as a noble metal catalyst such that the content of palladium is 1 wt% relative to the total weight of the catalyst for purification of exhaust gas.

The method of supporting the palladium on the zirconia carrier is not particularly limited, but may be supported by an impregnation method, a precipitation method, a deposition method, an ion exchange method, and the like, and the step (e) may preferably include a palladium precursor solution. Palladium may be supported on a zirconia carrier in which the crystal structure is modified.

The palladium precursor is a compound containing palladium (Pd), preferably chloride (PdCl ₂ ), but is not necessarily limited to this can be used without limitation conventional palladium precursor known in the art.

In the step (f) (S160), the exhaust gas purification catalyst may be calcined at 500 ° C. to 700 ° C. for 2 hours to 10 hours, preferably at 600 ° C. for 6 hours.

In addition, in order to achieve the above object, the catalyst for purifying exhaust gases of the present invention is prepared using the preparation method as described above, and a palladium catalyst is supported on the zirconia carrier, and the crystal structure of the zirconia carrier is monoclinic. A crystal phase and tetragonal crystal phase are included together.

It is preferable that the tetragonal crystal phase is contained more than 0 vol% and less than 65 vol% with respect to the total composition of the zirconia carrier.

In addition, the content of palladium to the total weight of the catalyst for the exhaust gas purification as a noble metal catalyst in the exhaust gas purification catalyst may be included in 1 wt%.

The catalyst for purifying exhaust gas of the present invention is preferably used as an exhaust gas catalyst for a lean-burn CNG vehicle, but the catalyst for purifying exhaust gas of the present invention is not limited to the above-mentioned application targets, but is not limited to methane (CH). ₄ ) It can be applied to various catalysts which can be easily carried out by those skilled in the art as an oxidation catalyst.

According to the method for preparing a catalyst for purifying exhaust gases of the present invention as described above, in order to use tetragonal crystalline zirconia (ZrO ₂ ) used as a carrier of a noble metal palladium (Pd) catalyst as a catalyst for purifying exhaust gases in general. Unlike the separate firing process at a high temperature of 1100 ° C. or higher, zirconia composed of a monoclinic and tetragonal crystal phases by aging at a temperature lower than 100 ° C. as a carrier in an exhaust gas purification catalyst. Since the (ZrO ₂ ) carrier can be prepared and prepared by supporting a palladium catalyst on the zirconia carrier, the operation cost of the process can be reduced and the problem of mass production difficult can be solved.

In addition, a zirconia (ZrO ₂ ) carrier composed of a monoclinic crystal and tetragonal crystal phase is prepared as a carrier in the catalyst for purifying exhaust gas, and thus prepared by carrying a palladium catalyst to support the electrochemical interaction between palladium and the carrier. By controlling the electrochemical properties of the noble metal (palladium) by the effect of improving the durability as well as the purification performance of the catalyst.

FIG. 1 is a schematic diagram showing an oxidation process of methane (CH ₄ ) on a surface of a conventional palladium (Pd) -palladium oxide (PdO) catalytic reaction site.
2 is a flowchart illustrating a process of a catalyst for purifying exhaust gas of the present invention according to an example.
3 is an X-ray diffraction (XRD) result graph of the catalyst for purifying exhaust gas prepared according to an embodiment of the present invention.
4A and 4B are scanning electron microscope (SEM) images of a catalyst for purifying exhaust gas prepared according to an embodiment of the present invention.
5 is a schematic view showing a simplified method for evaluating the purification performance of the catalyst for purification of exhaust gas of the present invention.
FIG. 6 is a graph showing the results of light-off temperature (LOT) analysis of the catalyst for purification of exhaust gas of Comparative Example. FIG.
7 is a light-off temperature (LOT) analysis result graph of the catalyst for purifying exhaust gas prepared according to an embodiment of the present invention.

Hereinafter, examples and comparative examples of the catalyst for purifying exhaust gas of the present invention will be described in detail, and these examples and comparative examples may be embodied in various different forms by those skilled in the art as an example. Therefore, the present invention is not limited to the embodiment described herein.

On the other hand, the terms "comprise" or "add" as used herein are not to be construed as necessarily including all of the various components or steps described in the specification, some of the components or It is to be understood that some steps may not be included and may further include additional components or steps.

The number of repetitions, process conditions, and the like of each step described in the method for producing the catalyst for purifying exhaust gas of the present invention is not particularly limited unless the object of the present invention is departed.

Example 1 prepared a zirconium precursor solution by dissolving zirconium oxychloride octahydrate (ZrOCl ₂ · 8H ₂ O) in distilled water as a zirconium precursor, 28 wt% aqueous ammonia (NH ₄ OH) was added to the zirconium precursor solution Is adjusted to 9.5 to form a precipitate of zirconium hydroxide (Zr (OH) ₄ · nH ₂ O), the aqueous solution containing zirconium hydroxide (Zr (OH) ₄ · nH ₂ O) 48 hours at 30 ℃ Aging to prepare a zirconia (ZrO ₂ ) carrier. The prepared zirconia carrier is washed, dried at 60 ° C. for 24 hours and calcined at 600 ° C. for 6 hours. Palladium chloride (PdCl ₂ ) was sufficiently dissolved in 1 M aqueous hydrochloric acid solution to prepare a palladium precursor aqueous solution, which was then impregnated in a zirconia (ZrO ₂ ) carrier to impregnate 1 wt% palladium, and impregnated with palladium. The zirconium precursor was calcined at 600 ° C. for 6 hours to prepare a catalyst for purifying exhaust gas of final 1 wt% Pd / ZrO ₂ .

Example 2 was carried out in the same manner as in Example 1 except that the aging temperature was treated at 50 ° C. to prepare a catalyst for purifying exhaust gas of 1 wt% Pd / ZrO ₂ .

Example 3 was carried out in the same manner as in Example 1 except that the aging temperature conditions were treated at 70 ° C., thereby preparing a catalyst for purifying exhaust gas of 1 wt% Pd / ZrO ₂ .

Example 4 was carried out in the same manner as in Example 1 except that the aging temperature conditions were treated at 85 ° C. to prepare a catalyst for purifying exhaust gas of 1 wt% Pd / ZrO ₂ .

Example 5 was carried out in the same manner as in Example 1 except that the aging temperature was treated at 100 ° C. to prepare a catalyst for purifying exhaust gas of 1 wt% Pd / ZrO ₂ .

In Comparative Example 1, palladium chloride (PdCl ₂ ) was sufficiently dissolved in 1 M aqueous hydrochloric acid solution to dissolve it, and then, it was impregnated to the carrier of γ-Al ₂ O _{3 so that} the palladium content was 1 wt%, and the palladium was impregnated. The zirconium precursor was calcined at 600 ° C. for 6 hours to prepare a catalyst for purifying exhaust gas of 1 wt% Pd / γ-Al ₂ O ₃ as a comparative catalyst.

Comparative Example 2 was prepared in the same manner as in Comparative Example 1, except that cerium oxide (CeO ₂ ) was used as a support, to prepare a catalyst for purifying exhaust gas of 1 wt% Pd / CeO _{2 as} a comparative catalyst.

Comparative Example 3 was prepared in the same manner as in Comparative Example 1, except that tin oxide (SnO ₂ ) was used as a support, to prepare an exhaust gas purification catalyst having a comparative catalyst of 1 wt% Pd / SnO ₂ .

Comparative Example 4 was prepared in the same manner as in Comparative Example 1, except that magnesium aluminate (MgAl ₂ O ₄ ) was used as a carrier, to prepare a catalyst for purifying exhaust gas of 1 wt% Pd / MgAl ₂ O _{4 as} a comparative catalyst. .

Each of the catalysts for purification of exhaust gas prepared in Examples 1 to 5 and Comparative Examples 1 to 4 was measured and evaluated in terms of physical properties of the catalyst and the activity of the catalyst by the measurement method shown in the following Experimental Examples.

Experimental Example 1 is an X-ray diffraction (XRD) of the crystal phase analysis of the zirconia (ZrO ₂ ) carrier prepared before the palladium support in Examples 1 to 5 of the present invention, the results 3 is shown in Table 1 below.

division Crystal Size (nm) Tetragonal content
(vol%) Tetragonal
(2θ = 30.3 °) Monoclinic
(2θ = 28.2 °) ZrO ₂ (30 ℃) 13.7 21.7 9.0 ZrO ₂ (50 ℃) 12.4 14.3 10.5 ZrO ₂ (70 ℃) 10.6 9.6 66.8 ZrO ₂ (85 ℃) 7.8 - 100 ZrO ₂ (100 ℃) 6.8 - 100

As described, the higher the aging temperature conditions, the tetragonal composition content in the crystal structure of the zirconia (ZrO ₂ ) carrier is increased, and in particular, in Example 4 and 100 ° C., the aging temperature is 85 ° C. In Example 5 it was confirmed that only tetragonal crystal phase is observed.

Experimental Example 2 is a BET of a zirconia (ZrO ₂ ) carrier prepared before loading palladium in Examples 1 to 5 of the present invention and a 1 wt% Pd / ZrO ₂ catalyst obtained according to Examples 1 to 5 Specific surface area (S _BET ), pore volume (V _P ) and average pore size (D _P ) were measured and shown in Table 2.

division ZrO ₂ 1 wt% Pd / ZrO ₂ S _BET
(m ² / g) V _P
(cm ³ / g) D _P (nm) S _BET
(m ² / g) V _P
(cm ³ / g) D _P (nm) ZrO ₂ (30 ℃) 17 0.093 15.0 15 0.091 19.2 ZrO ₂ (50 ℃) 33 0.131 12.8 29 0.127 14.7 ZrO ₂ (70 ℃) 71 0.217 10.6 68 0.205 10.6 ZrO ₂ (85 ℃) 123 0.341 10.5 111 0.331 11.6 ZrO ₂ (100 ℃) 157 0.386 9.5 148 0.389 10.2

From Table 2, as the aging temperature increases, the diameter of the average pore size of the zirconia (ZrO ₂ ) carrier and the palladium-supported 1 wt% Pd / ZrO ₂ catalyst decreases, resulting in a BET specific surface area and pore volume. It can be seen that the increase.

In addition, the zirconia (ZrO ₂ ) carriers of Examples 1 and 2 were observed through a scanning electron microscope (SEM), and the photographs observed are shown in FIGS. 4A and 4B.

When the particle sizes of the zirconia carrier of Example 1 observed in FIG. 4A and the zirconia carrier of Example 5 observed in FIG. 4B are compared, the particle size of the zirconia carrier of Example 5 having a relatively high aging temperature is shown. It could be confirmed that the smaller.

Therefore, as the aging temperature increased, the particle size of the zirconia carrier was reduced, and it was confirmed that the specific surface area of the catalyst was increased due to the development of micropores.

Experimental Example 3 relates to the evaluation of the catalyst activity, as shown in Figure 5, after filling the reaction tube with 0.1g of the catalyst in powder form prepared in Examples 1 to 5, Comparative Examples 1 to 4 After pretreatment at 500 ° C for 1 hour with flowing air, 400 ml / min of a mixed gas containing methane (CH ₄ ), oxygen (O ₂ ), water vapor (H ₂ O), and nitrogen (N ₂ ) 0.1% CH ₄ : 10% H ₂ O) by using a MFC (Mass Flow Controller) to regulate the flow rate of gas while supplying the temperature at a temperature increase rate of 5 ℃ / min and the reaction activity is measured by temperature The oxidation performance of methane (CH ₄ ) was evaluated, and the results are shown in FIGS. 6 and 7, and Table 3 and Table 4 below.

In Tables 3 and 4 below, T ₃₀ represents a 30% methane conversion temperature, T ₅₀ represents a 50% methane conversion temperature, and T ₉₀ represents a 90% methane conversion temperature.

division T ₃₀
(℃) T ₅₀
(℃) T ₉₀
(℃) Comparative Example 1 483.6 501.2 545.5 Comparative Example 2 448.3 469.7 594.1 Comparative Example 3 470.8 511.5 - Comparative Example 4 491.1 514.4 571.4

division T ₃₀
(℃) T ₅₀
(℃) T ₉₀
(℃) Example 1 420.5 439.9 492.7 Example 2 427.8 448.6 499.4 Example 3 455.5 488.7 559.2 Example 4 451.4 480.4 542.7 Example 5 458.9 488.6 540.4

As a result of the catalytic activity evaluation, Examples 1 and 2, in which monoclinic and tetragonal crystal phases were mixed based on 50% methane conversion temperature (T ₅₀ ), consisted of only a single tetragonal crystal phase structure. It was confirmed that methane (CH ₄ ) oxidation activity was better at a lower temperature than zirconia (ZrO ₂ ) carrier, γ-Al ₂ O ₃ , CeO ₂ , Sn ₂ O ₃ , MgAl ₂ O _{4 of} Comparative Examples 1 to ₄ It can be seen that the oxidation activity of methane is excellent even when compared with a carrier such as these.

According to Non-Patent Documents 1 and 2, in the case of Pd / ZrO ₂ catalyst, when palladium (Pd) is present as metal palladium (metallic Pd), the activity is low.In contrast, as the ratio of palladium oxide (PdO) is increased, methane (CH ₄ ) Oxidation activity is improved. In particular, when metal palladium (metallic Pd) is present on the surface of palladium oxide (PdO) in a small proportion, the methane (CH ₄ ) oxidation activity is improved, which is because methane is dissociated to metal palladium rather than palladium oxide (PdO). Described.

Therefore, according to the crystal structure of zirconia (ZrO ₂ ) from the present embodiment it was confirmed that the electrochemical control of the palladium (Pd) supported thereon, as in Example 1 produced by aging (aging) at a temperature of 30 ℃ It was confirmed that the methane (CH ₄ ) oxidation activity was the most excellent in the zirconia carrier including both the monocrystalline and tetragonal crystal phases.

The foregoing detailed description is merely a preferred embodiment, and is not limited to the above-described example and the accompanying drawings. Accordingly, various substitutions and changes may be made without departing from the spirit of the present invention.

Claims (14)

(a) adding a basic solution to an aqueous zirconium precursor solution in which a zirconium precursor is dissolved in water to form a precipitate;
(b) aging the aqueous solution including the precipitate formed in step (a) at a predetermined temperature to prepare a zirconia (ZrO ₂ ) carrier;
(c) washing and drying the prepared zirconia carrier;
(d) calcining the dried zirconia carrier in step (c);
(e) supporting palladium on the zirconia carrier passed through step (d); And
(f) calcining the exhaust gas purification catalyst formed by supporting palladium on the zirconia carrier through step (e);
Method for producing a catalyst for purification of exhaust gas comprising a. The method of claim 1,
In the step (b), the precipitate is aged at a temperature of 30 ° C. or higher and less than 70 ° C. to prepare a zirconia carrier in which the crystal structure of the zirconia carrier includes a monoclinic crystal phase and a tetragonal crystal phase. A method for producing an exhaust gas purification catalyst. The method of claim 2,
The tetragonal crystal phase of the exhaust gas purifying catalyst, characterized in that it comprises more than 0 vol% less than 65 vol% based on the total composition of the zirconia carrier. The method of claim 1,
The step (c) is a method for producing a catalyst for purification of exhaust gas, characterized in that for drying the washed zirconia carrier at 50 to 70 ℃ 24 hours or less. The method of claim 1,
In the step (d), the zirconia carrier is calcined at 500 ° C. to 700 ° C. for 2 to 10 hours. The method of claim 1,
In the step (e), the palladium precursor solution in which the palladium precursor is dissolved in distilled water is supported on the zirconia carrier so that the palladium content is 1 wt%. The method of claim 1,
In the step (f), the exhaust gas purification catalyst is calcined at 500 ° C. to 700 ° C. for 2 to 10 hours. The method of claim 1,
The zirconium precursor is a zirconium oxychloride octahydrate (ZrOCl ₂ · 8H ₂ O), the method for producing a catalyst for purification of exhaust gas, characterized in that. The method of claim 1,
The step (a) is a method of producing a catalyst for purification of exhaust gas, characterized in that the basic solution is added so that the pH concentration of the aqueous solution of zirconium precursor is adjusted to 9 to 10. The method of claim 1,
The basic solution is a method for producing a catalyst for purification of exhaust gas, characterized in that ammonia water (NH ₄ OH) or sodium hydroxide (NaOH) aqueous solution. The method of claim 1,
The step (b) is a method for producing an exhaust gas purification catalyst, characterized in that the aging (aging) for less than 48 hours. A catalyst for purifying exhaust gases, which is prepared by the method according to any one of claims 1 to 11, wherein a palladium catalyst is supported on a zirconia carrier. The method of claim 12,
The catalyst for purifying exhaust gas is a catalyst for purifying exhaust gas, characterized in that the crystalline structure of the zirconia carrier includes a monoclinic crystal phase and a tetragonal crystal phase. The method of claim 13,
The tetragonal crystal phase is an exhaust gas purification catalyst, characterized in that it comprises more than 0 vol% less than 65 vol% based on the total composition of the zirconia carrier.

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