KR102268466B1 - Highly Durable Metal Ensemble Catalysts with Full Dispersion and Reduced Metallic State - Google Patents

Abstract

The present invention relates to a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state, and a method for preparing the same.

Description

Highly Durable Metal Ensemble Catalysts with Full Dispersion and Reduced Metallic State

The present invention relates to a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state, and a method for preparing the same.

In heterogeneous catalysis, supported noble metals such as platinum, palladium and rhodium have been widely used due to their high catalytic performance. However, precious metals such as platinum, palladium and rhodium are very rare and expensive. Therefore, it is very important to maximize the use efficiency of the noble metal so that there are no unused noble metal atoms. Maximizing the use of noble metals by placing all metal atoms on the surface for heterogeneous reactions has been actively pursued. Reducing the size of metal nanoparticles down to the single atom level can maximize metal dispersion to 100%.

Recently, single-atom catalysts (hereinafter referred to as SAC) in which all metal atoms are 100% dispersed on a support and exist independently of each other have received much attention. However, because there is no metal ensemble site, it does not show catalytic performance for reactions requiring an ensemble site. Also, in general, single atoms have a high oxidation state because they require strong interactions between the metal and the support. Interactions are often insufficient, so many SACs show unsatisfactory durability, especially to reduction reactions.

The metal-support or metal-adsorbent interaction must be much stronger than the metal-metal interaction to stabilize independently existing metal atoms. In general, SAC is supported by defect sites (Pt ₁ /FeOx), strong metal support interactions (Rh ₁ /ZrO ₂ ), metal support doping (Pt ₁ /Sb-SnO ₂ ), and ligands (Pt ₁ /TiN). is stabilized

SAC has received a lot of attention over the past decade due to its maximum metal utilization efficiency and unique catalytic performance. SAC efficiently catalyzed reactions such as CO oxidation, direct methane oxidation, hydroformylation of propylene, selective hydrogenation, electrochemical electron oxygen reduction reaction and direct formic acid oxidation reaction. However, to date, SAC has the following important limitations.

First, SAC cannot catalyze other important reactions that proceeded at the metal ensemble site, e.g., hydrocarbon (C≥2) oxidation, full hydrogenation, isomerization, electrochemical four-electron oxygen reduction reaction, and direct formic acid oxidation reaction. .

Second, typically fully dispersed metal catalysts are in highly oxidized states, such as ^{Pt δ+} , Pd ^δ+ , and Rh ^{δ+ .} The stabilization process of SAC metal atoms, metal-support or-adsorbent interactions, results in electron-deficient metal atoms. Therefore, metal atoms are strongly aggregated in the reduction process, and the metal dispersion degree is lowered. In addition, fully dispersed metal catalysts had poor durability under high-temperature reduction, which is a very typical condition for heterogeneous catalysts. In fact, the reduction reaction using a fully dispersed metal catalyst reported so far was carried out under very mild conditions. They have been mainly used for light hydrogenation, or otherwise durability issues are not considered.

Accordingly, the present inventors have developed highly reduced and fully dispersed ensemble catalysts (ESCs). The catalyst of the present invention was used for exhaust purification with excellent catalytic activity at low temperature, that is, a three-way catalyst (TWC) reaction. In addition, ESCs exhibit excellent durability under harsh conditions such as hydrothermal aging, long-term reactions and repeated reactions.

Accordingly, it is an object of the present invention to provide a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state.

Another object of the present invention is to provide a method for preparing a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state.

The present inventors developed a highly durable metal (Pt, Pd, Rh) ensemble catalyst that enables hydrocarbon oxidation requiring metal ensemble sites. The ensemble catalyst also has a reduced metal state that enables NO reduction. Since this ensemble catalyst has high durability, the catalyst structure is maintained after hydrothermal treatment at 900° C. for 24 hours or after a long-term reaction.

More specifically, nano-ceria ^{was immobilized on the Al 3+} penta site of reduced alumina, followed by deposition and reduction of Pt, Pd or Rh. These catalysts exhibited 100% metal dispersion and highly reduced metal state, and exhibited excellent activity and durability for three-way catalytic (TWC) reactions. Such catalysts can provide new insights beyond single atom catalysts in heterogeneous catalysts.

Hereinafter, the present invention will be described in more detail.

An example of the present invention relates to a method for preparing a highly durable metal ensemble catalyst having a fully dispersed and reduced metal state, comprising the following steps:

A method for preparing a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state, comprising the steps of:

A penta site forming step of flowing _{H 2} /N ₂ to γ-alumina ^{to form an Al 3+ penta site;}

a first impregnation step of impregnating the ceria-based support precursor into reduced γ-alumina (rAl ₂ O _{3 );}

a second impregnation step of impregnating the noble metal precursor to impregnate the support with the noble metal;

a powder obtaining step of obtaining a powder by stirring until the solution is completely evaporated;

Drying the powder to obtain a dry powder to obtain a dry powder;

calcining the dry powder to obtain calcined powder;

A catalyst obtaining step of reducing the calcined powder in H ₂ /N ₂ at a ramping rate of 10° C./min to obtain a catalyst.

In the present invention, the penta moiety forming step is 200 to 550 ℃, 250 to 550 ℃, 300 to 550 ℃, 200 to 500 ℃, 250 to 500 ℃, 300 to 500 ℃, 200 to 450 ℃, 250 to 450 ℃, It may be carried out at 300 to 450 °C, 200 to 400 °C, 250 to 400 °C, 300 to 400 °C, for example, it may be carried out at 350 °C. When performed within the above range, there is an advantage of forming a penta site only on the surface while maintaining the bulk structure of alumina.

In the present invention, the step of forming the penta site may be performed for 0.5 to 3.0 hours, 0.5 to 2.5 hours, 0.5 to 2.0 hours, 0.5 to 1.5 hours, for example, it may be performed for 1.0 hours. When performed within the above range, there is an advantage of forming a penta site only on the surface while maintaining the bulk structure of alumina.

_{In the present invention, the concentration of H 2} /N _{2 in} the step of forming the penta site is 3 to 20% (v/v), 5 to 20% (v/v), 7 to 20% (v/v), 9 to 20 % (v/v), 3 to 18 % (v/v), 5 to 18 % (v/v), 7 to 18 % (v/v), 9 to 18 % (v/v), 3 to 16 % (v/v), 5 to 16 % (v/v), 7 to 16 % (v/v), 9 to 16 % (v/v), 3 to 14 % (v/v), 5 to 14 % (v/v), 7 to 14 % (v/v), 9 to 14 % (v/v), 3 to 12 % (v/v), 5 to 12 % (v/v), 7 to 12% (v/v), 9 to 12% (v/v), for example, may be 10% (v/v). When performed within the above range, there is an advantage of forming a penta site only on the surface while maintaining the bulk structure of alumina.

In an embodiment of the present invention, the step of forming the penta moiety is _{pre-reducing γ-alumina by flowing 10% (v/v) H 2} /N ₂ at 350 ° C. for 1.0 hour to form a tunable unsaturated Al ³⁺ penta moiety. may have been created.

In the present invention, the ceria-based support may be a cerium dioxide (CeO ₂ ) support.

In the present invention, the cerium dioxide support may be prepared through the following steps:

Ce(NO ₃ ) ₃ ·6H ₂ O is dissolved in deionized water to prepare a cerium solution to prepare a cerium solution;

an impregnation step of impregnating the reduced γ-alumina;

Evaporation step to completely evaporate the solution

a drying step of drying the precipitate;

pulverization step of pulverizing the dried precipitate to obtain a fine powder; and

A calcination step in which the fine powder is calcined.

In the present invention, the content of the ceria-based support precursor in the first impregnation step is 3 to 10 wt%, 4 to 10 wt%, 5 to 10 wt%, 6 to 10 wt%, 7 to 10 wt%, 8 to 10 wt% %, 9 to 10% by weight, for example, may be 10% by weight. When performed within the above range, all ceria-based support precursors are effectively impregnated into the penta site of alumina to form defective ceria.

In the present invention, the first impregnation step is 25 to 90 ℃, 25 to 80 ℃, 25 to 70 ℃, 25 to 60 ℃, 25 to 50 ℃, 30 to 90 ℃, 30 to 80 ℃, 30 to 70 ℃, 30 to 60 °C, 30 to 50 °C, 35 to 90 °C, 35 to 80 °C, 35 to 70 °C, 35 to 60 °C, 35 to 50 °C, for example, it may be carried out at 40 °C. When performed within the above range, all ceria-based support precursors are effectively impregnated into the penta site of alumina to form defective ceria.

In the present invention, the first impregnation step is 10 to 120 minutes, 20 to 120 minutes, 30 to 120 minutes, 40 to 120 minutes, 50 to 120 minutes, 10 to 100 minutes, 20 to 100 minutes, 30 to 100 minutes, 40 to 100 minutes, 50 to 100 minutes, 10 to 80 minutes, 20 to 80 minutes, 30 to 80 minutes, 40 to 80 minutes, 50 to 80 minutes, 10 to 70 minutes, 20 to 70 minutes, 30 to 70 minutes, 40 to 70 minutes, 50 to 70 minutes, for example, it may be carried out for 60 minutes. When performed within the above range, all ceria-based support precursors are effectively impregnated into the penta site of alumina to form defective ceria.

In an embodiment of the present invention, the first impregnation step is to impregnate _{γ-alumina (rAl 2} O ₃ ) with _{3 to 10% by weight of the cerium dioxide (CeO 2} ) support precursor reduced at 25 to 90° C. for 10 to 120 minutes. it could be

In the present invention, the noble metal may be at least one selected from the group consisting of Pt, Pd and Rh.

In the present invention, the noble metal precursor may be prepared through the following steps:

A precursor solution preparation step of adding HCl to PtCl ₄ , PdCl ₂ or RhCl _{3 to prepare a H 2} PtCl ₆ , H ₂ PdCl ₄ or H ₂ RhCl _{5 precursor solution;} and

an impregnation step of impregnating the support with a H ₂ PtCl ₆ , H ₂ PdCl ₄ or H ₂ RhCl _{5 precursor solution;}

Evaporation step to completely evaporate the precursor solution

a drying step of drying the precipitate;

pulverization step of pulverizing the dried precipitate to obtain a fine powder;

a calcination step of calcining the fine powder;

A reduction step of reducing the calcined powder.

In the present invention, the second impregnation step is 40 to 90 ℃, 40 to 85 ℃, 40 to 80 ℃, 40 to 75 ℃, 40 to 70 ℃, 40 to 65 ℃, 40 to 60 ℃, 40 to 55 ℃, 40 To 50 ℃, 40 to 45 ℃, for example, it may be carried out at 40 ℃. When performed within the above range, all noble metals are completely dispersed on the defective support and there is an advantage of having an ensemble structure.

In the present invention, the noble metal precursor of the second impregnation step is 0.5 to 2.0 wt%, 0.6 to 2.0 wt%, 0.7 to 2.0 wt%, 0.8 to 2.0 wt%, 0.9 to 2.0 wt%, 0.5 to 1.8 wt%, 0.6 to 1.8 wt%, 0.7-1.8 wt%, 0.8-1.8 wt%, 0.9-1.8 wt%, 0.5-1.6 wt%, 0.6-1.6 wt%, 0.7-1.6 wt%, 0.8-1.6 wt%, 0.9-1.6 wt% %, 0.5-1.4 wt%, 0.6-1.4 wt%, 0.7-1.4 wt%, 0.8-1.4 wt%, 0.9-1.4 wt%, 0.5-1.2 wt%, 0.6-1.2 wt%, 0.7-1.2 wt%, 0.8 to 1.2 wt%, 0.9 to 1.2 wt%, for example, may be 1.0 wt%. When performed within the above range, all noble metals are completely dispersed on the defective support and there is an advantage of having an ensemble structure.

In the present invention, the powder obtaining step is 40 to 90 ℃, 40 to 85 ℃, 40 to 80 ℃, 40 to 75 ℃, 40 to 70 ℃, 40 to 65 ℃, 40 to 60 ℃, 40 to 55 ℃, 40 to 50 ℃, 40 to 45 ℃, for example, it may be carried out at 40 ℃. When performed within the above range, all noble metals are completely dispersed on the defective support and there is an advantage of having an ensemble structure.

In the present invention, the dry powder obtaining step is 60 to 100 ℃, 60 to 95 ℃, 60 to 90 ℃, 60 to 85 ℃, 65 to 100 ℃, 65 to 95 ℃, 65 to 90 ℃, 65 to 85 ℃, 70 to 100 ° C, 70 to 95 ° C, 70 to 90 ° C, 70 to 85 ° C, 75 to 100 ° C, 75 to 95 ° C, 75 to 90 ° C, 75 to 85 ° C, for example, 80 ° C. have. When carried out within the above range, there is an advantage in that the noble metal is not sintered and the solvent is completely dried.

In the present invention, the step of obtaining calcined powder is 400 to 600 °C, 450 to 600 °C, 470 to 600 °C, 490 to 600 °C, 400 to 550 °C, 450 to 550 °C, 470 to 550 °C, 490 to 550 °C, 400 to 530 °C, 450 to 530 °C, 470 to 530 °C, 490 to 530 °C, 400 to 510 °C, 450 to 510 °C, 470 to 510 °C, 490 to 510 °C, for example, it may be carried out at 500 °C. have. When carried out within the above range, there is an advantage in that the noble metal is not sintered and a strong interaction between the noble metal and the defective support is induced.

In the present invention, the step of obtaining calcined powder may be performed for 3 to 7 hours, 3 to 6 hours, 4 to 7 hours, 4 to 6 hours, for example, 5 hours. When carried out within the above range, there is an advantage in that the noble metal is not sintered and a strong interaction between the noble metal and the defective support is induced.

In the present invention, the catalyst obtaining step may be performed at 200 to 500 °C, 250 to 500 °C, 300 to 500 °C, 350 to 500 °C, 400 to 500 °C, 450 to 500 °C, for example, 500 °C. . When carried out within the above range, there is an advantage that the noble metal can be effectively reduced without being sintered.

In the present invention, the catalyst obtaining step is 60 to 180 minutes, 60 to 160 minutes, 60 to 140 minutes, 80 to 180 minutes, 80 to 160 minutes, 80 to 140 minutes, 100 to 180 minutes, 100 to 160 minutes, 100 to It may be carried out for 140 minutes, for example, 120 minutes. When carried out within the above range, there is an advantage that the noble metal can be effectively reduced without being sintered.

In the present invention, the catalyst obtaining step is 5 to 20% (v/v) H ₂ /N ₂ , 7 to 20% (v/v) H ₂ /N ₂ , 9 to 20% (v/v) H ₂ / N ₂ , 5 to 17 % (v/v) H ₂ /N ₂ , 7 to 17 % (v/v) H ₂ /N ₂ , 9 to 17 % (v/v) H ₂ /N ₂ , 5 to 14 % (v/v) H ₂ /N ₂ , 7 to 14 % (v/v) H ₂ /N ₂ , 9 to 14 % (v/v) H ₂ /N ₂ , 5 to 11 % (v/v) v) H ₂ /N ₂ , 7 to 11 % (v/v) H ₂ /N ₂ , 9 to 1 % (v/v) H ₂ /N ₂ , for example 10% (v/v) H It may be performed at ₂ /N _{2 .} When carried out within the above range, there is an advantage that the noble metal can be effectively reduced without being sintered.

In the present invention, the ensemble catalyst includes a noble metal supported on a ceria-based support, and the noble metal is dispersed at least 99% on the surface of cerium dioxide and has a reduced metal state, it is a highly durable metal ensemble catalyst.

In the present invention, the content of the noble metal of the ensemble catalyst is 0.5 to 2.0% by weight, 0.7 to 2.0% by weight, 0.9 to 2.0% by weight, 0.5 to 1.7% by weight, 0.7 to 1.7% by weight, 0.9 to 1.7 based on the total catalyst weight An amount in the range of weight percent, 0.5 to 1.4 weight percent, 0.7 to 1.4 weight percent, 0.9 to 1.4 weight percent, 0.5 to 1.1 weight percent, 0.7 to 1.1 weight percent, 0.9 to 1.1 weight percent, for example 1.0 weight percent may be present on the support. When performed within the above range, all noble metals are completely dispersed on the defective support and there is an advantage of having an ensemble structure.

Another example of the present invention relates to a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state.

In the present invention, the ensemble catalyst includes a noble metal supported on a ceria-based support, the noble metal is dispersed at least 99% on the surface of cerium dioxide, and is a highly durable metal ensemble catalyst having a reduced metal state.

In the present invention, the ceria-based support may be a cerium dioxide (CeO ₂ ) support.

In the present invention, the noble metal content of the ensemble catalyst may be present on the support in an amount ranging from 0.5 to 2.0 wt% based on the total catalyst weight.

In the present invention, the noble metal may be at least one selected from the group consisting of Pt, Pd and Rh.

In the present invention, the metal ensemble catalyst may be for removal of at least one selected from the group consisting of hydrocarbons, carbon monoxide and nitrogen oxides, for example, it may be for simultaneous removal of hydrocarbons, carbon monoxide and nitrogen oxides.

In the present invention, the metal ensemble catalyst may be prepared through the above-described method.

Another example of the present invention relates to a device for removing at least one selected from the group consisting of hydrocarbons, carbon monoxide and nitrogen oxides, including a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state.

The highly durable metal ensemble catalyst having a completely dispersed and reduced metal state is the same as described above.

In the present invention, the apparatus may be an internal combustion engine exhaust stream treatment apparatus, a gasoline vehicle three-way catalyst (TWC) apparatus, and a diesel vehicle exhaust gas purification catalyst (DOC, LNT, SCR) apparatus, but is not limited thereto.

The present invention relates to a highly durable metal ensemble catalyst having a completely dispersed and reduced metal state and a method for preparing the same, and the catalyst of the present invention is used for exhaust purification having excellent catalytic activity at low temperature, that is, a three-way catalyst (TWC) reaction. became In addition, ESCs exhibit excellent durability under harsh conditions such as hydrothermal aging, long-term reactions and repeated reactions.

에서 함침된 M/CeO₂-rAl₂O₃ (ESCs), M/CeO₂-Al₂O₃ (M/CA) 및 M/rAl₂O₃ (M/rA) (M = Pt, Pd 및 Rh)의 CO 변환 활성을 보여주는 그래프이다.
도 17b는 본 발명의 일 실시예에 따라 삼원 촉매 (TWC) 반응을 위해 40

에서 함침된 M/CeO₂-rAl₂O₃ (ESCs), M/CeO₂-Al₂O₃ (M/CA) 및 M/rAl₂O₃ (M/rA) (M = Pt, Pd 및 Rh)의 C₃H₆ 변환 활성을 보여주는 그래프이다.
도 17c는 본 발명의 일 실시예에 따라 삼원 촉매 (TWC) 반응을 위해 40

에서 함침된 M/CeO₂-rAl₂O₃ (ESCs), M/CeO₂-Al₂O₃ (M/CA) 및 M/rAl₂O₃ (M/rA) (M = Pt, Pd 및 Rh)의 C₃H₈ 변환 활성을 보여주는 그래프이다.
도 17d는 본 발명의 일 실시예에 따라 삼원 촉매 (TWC) 반응을 위해 40

에서 함침된 M/CeO₂-rAl₂O₃ (ESCs), M/CeO₂-Al₂O₃ (M/CA) 및 M/rAl₂O₃ (M/rA) (M = Pt, Pd 및 Rh)의 NO 변환 활성을 보여주는 그래프이다.
도 17e는 본 발명의 일 실시예에 따라 삼원 촉매 (TWC) 반응을 위해 40

에서 함침된 M/CeO₂-rAl₂O₃ (ESCs), M/CeO₂-Al₂O₃ (M/CA) 및 M/rAl₂O₃ (M/rA) (M = Pt, Pd 및 Rh)의 N₂ 선택도를 보여주는 그래프이다.
도 18a는 본 발명의 일 실시예에 따라 CO 산화(1% CO and 1% O₂ balanced with He)에 대한 ESC 및 SAC의 촉매 성능을 보여주는 그래프이다.
도 18b는 본 발명의 일 실시예에 따라 CO에 의한 NO 환원(200 ppm NO and 0.2% CO balanced with He)에 대한 ESC 및 SAC의 NO 전환율을 보여주는 그래프이다.
도 18c는 본 발명의 일 실시예에 따라 CO에 의한 NO 환원(200 ppm NO and 0.2% CO balanced with He)에 대한 ESC 및 SAC의 N₂ 선택도를 보여주는 그래프이다.
도 19a는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 CO 전환 촉매 성능을 보여주는 그래프이다.
도 19b는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC)반응에 대한 금속 ESC 및 SAC의 C₃H₆ 전환 촉매 성능을 보여주는 그래프이다.
도 19c는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 C₃H₈ 전환 촉매 성능을 보여주는 그래프이다.
도 19d는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 NO 전환 촉매 성능을 보여주는 그래프이다.
도 19e는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 N₂ 선택도를 보여주는 그래프이다.
도 20a는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 M/CeO₂-Al₂O₃ (M = Pt, Pd, Rh)의 CO 전환 촉매 성능을 보여주는 그래프이다.
도 20b는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC)반응에 대한 M/CeO₂-Al₂O₃ (M = Pt, Pd, Rh)의 C₃H₆ 전환 촉매 성능을 보여주는 그래프이다.
도 20c는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 M/CeO₂-Al₂O₃ (M = Pt, Pd, Rh)의 C₃H₈ 전환 촉매 성능을 보여주는 그래프이다.
도 20d는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 M/CeO₂-Al₂O₃ (M = Pt, Pd, Rh)의 NO 전환 촉매 성능을 보여주는 그래프이다.
도 20e는 본 발명의 일 실시예에 따라 수열 노화 후 (HT) 삼원 촉매 (TWC) 반응에 대한 M/CeO₂-Al₂O₃ (M = Pt, Pd, Rh)의 N₂ 선택도를 보여주는 그래프이다.
도 20f는 본 발명의 일 실시예에 따라 Pt/CeO₂-Al₂O₃, Pd/CeO₂-Al₂O₃ 및 Rh/CeO₂-Al₂O₃의 수열 노화 (hydrothermal aging; HT)시 특정 온도에서 CO, C₃H₆, C₃H₈ 및 NO의 전환 변화를 보여주는 그래프이다.
도 21a는 본 발명의 일 실시예에 따라 2번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 촉매 CO 전환 성능을 보여주는 그래프이다.
도 21b는 본 발명의 일 실시예에 따라 2번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 촉매 C₃H₆ 전환 성능을 보여주는 그래프이다.
도 21c는 본 발명의 일 실시예에 따라 2번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 촉매 C₃H₈ 전환 성능을 보여주는 그래프이다.
도 21d는 본 발명의 일 실시예에 따라 2번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 촉매 NO 전환 성능을 보여주는 그래프이다.
도 21e는 본 발명의 일 실시예에 따라 2번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 촉매 N₂ 선택도를 보여주는 그래프이다.
도 21f는 본 발명의 일 실시예에 따라 3번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 CO 전환 성능을 보여주는 그래프이다.
도 21g는 본 발명의 일 실시예에 따라 3번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 C₃H₆ 전환 성능을 보여주는 그래프이다.
도 21h는 본 발명의 일 실시예에 따라 3번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 C₃H₈ 전환 성능을 보여주는 그래프이다.
도 21i는 본 발명의 일 실시예에 따라 3번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 NO 전환 성능을 보여주는 그래프이다.
도 21j는 본 발명의 일 실시예에 따라 3번째 사이클 삼원 촉매 (TWC) 반응에 대한 금속 ESC 및 SAC의 N₂ 선택도를 보여주는 그래프이다.
도 22a는 본 발명의 일 실시예에 따라 Pt ESC의 수열 노화, 장기 TWC 반응 및 반복된 TWC 반응의 다양한 내구성 시험 후 k3 가중 FT-EXAFS 데이터이다.
도 22b는 본 발명의 일 실시예에 따라 Pd ESC의 수열 노화, 장기 TWC 반응 및 반복된 TWC 반응의 다양한 내구성 시험 후 k3 가중 FT-EXAFS 데이터이다.
도 22c는 본 발명의 일 실시예에 따라 Rh ESC의 수열 노화, 장기 TWC 반응 및 반복된 TWC 반응의 다양한 내구성 시험 후 k3 가중 FT-EXAFS 데이터이다.
도 23a는 본 발명의 일 실시예에 따라 Pt ESC의 수열노화(hydrothermal aging; HT) 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23b는 본 발명의 일 실시예에 따라 Pd ESC의 수열노화(hydrothermal aging; HT) 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23c는 본 발명의 일 실시예에 따라 Rh ESC의 수열노화(hydrothermal aging; HT) 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23d는 본 발명의 일 실시예에 따라 Pt ESC의 장기 TWC (long-term three-way catalytic) 반응의 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23e는 본 발명의 일 실시예에 따라 Pd ESC의 장기 TWC (long-term three-way catalytic) 반응의 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23f는 본 발명의 일 실시예에 따라 Rh ESC의 장기 TWC (long-term three-way catalytic) 반응의 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23g는 본 발명의 일 실시예에 따라 Pt ESC의 반복 TWC (repeated three-way catalytic) 반응 3회 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23h는 본 발명의 일 실시예에 따라 Pd ESC의 반복 TWC (repeated three-way catalytic) 반응 3회 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.
도 23i는 본 발명의 일 실시예에 따라 Rh ESC의 반복 TWC (repeated three-way catalytic) 반응 3회 내구성 시험 후 전자 특성을 보여주는 X 선 광전자 분광법 (XPS) 스펙트럼이다.1A is a process diagram schematically illustrating a process for synthesizing a metal ensemble catalyst having a completely dispersed and reduced metal state according to an embodiment of the present invention.
Figure 1b is a diffuse reflection infrared Fourier-transformation (DRIFT) spectrum graph showing the metal structure change of the Pt catalyst of _{CeO 2} -rAl ₂ O ₃ according to the impregnation temperature (40, 60 and 80 °C) according to an embodiment of the present invention. to be.
1c is a diffuse reflection infrared Fourier-transformation (DRIFT) spectrum graph showing the metal structure change of the Pd catalyst of _{CeO 2} -rAl ₂ O ₃ according to the impregnation temperature (40, 60 and 80° C.) according to an embodiment of the present invention; FIG. to be.
Figure 1d is a diffuse reflection infrared Fourier showing the metal structure change of the Rh catalyst obtained upon CO adsorption of _{CeO 2} -rAl ₂ O ₃ by the impregnation temperature (40, 60 80 and 90 ° C.) according to an embodiment of the present invention; The strain (DRIFT) spectrum graph.
1E is a k3-weighted Fourier transform-extended X-ray showing the metal structure change of a Pt sample of _{CeO 2} -rAl ₂ O _{3 with} impregnation temperatures (40, 60, and 80° C.) according to an embodiment of the present invention; FIG. Absorption microstructure (FT-EXAFS) data graph.
1f is a k3-weighted Fourier transform-extended X-ray showing the metal structure change of a Pd sample of _{CeO 2} -rAl ₂ O _{3 with} impregnation temperatures (40, 60, and 80° C.) according to an embodiment of the present invention; FIG. Absorption microstructure (FT-EXAFS) data graph.
1g is a k3-weighted Fourier transform-extended X- showing changes in the metal structure of Rh samples of _{CeO 2} -rAl ₂ O _{3 with} impregnation temperatures (40, 60, 80 and 90 °C) according to an embodiment of the present invention; Line absorption microstructure (FT-EXAFS) data graph.
2A is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image of a Pt ESC according to an embodiment of the present invention (circle: metallic ESC; left: low magnification; right: high magnification).
2B is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image of a Pd ESC according to an embodiment of the present invention (circle: metallic ESC; left: low magnification; right: high magnification).
2C is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image of a Rh ESC according to an embodiment of the present invention (circle: metallic ESC; left: low magnification; right: high magnification).
3A is a graph showing X-ray absorption near structure (XANES) data of a Pt sample according to an embodiment of the present invention.
3B is a graph showing X-ray absorption near structure (XANES) data of a Pd sample according to an embodiment of the present invention.
3C is a graph showing X-ray absorption near structure (XANES) data of a Rh sample according to an embodiment of the present invention.
3D is a graph showing an X-ray photoelectron spectroscopy (XPS) spectrum of a Pt ESC according to an embodiment of the present invention.
3E is a graph showing an X-ray photoelectron spectroscopy (XPS) spectrum of a Pd ESC according to an embodiment of the present invention.
3F is a graph showing an X-ray photoelectron spectroscopy (XPS) spectrum of Rh ESCs according to an embodiment of the present invention.
3G is a graph showing an X-ray photoelectron spectroscopy (XPS) spectrum of Pt SAC according to an embodiment of the present invention.
3H is a graph showing an X-ray photoelectron spectroscopy (XPS) spectrum of Pd SAC according to an embodiment of the present invention.
3I is a graph showing an X-ray photoelectron spectroscopy (XPS) spectrum of Rh SAC according to an embodiment of the present invention.
Figure 4a is a graph showing the catalytic performance of ESC and SAC for a three-way catalytic CO conversion reaction according to an embodiment of the present invention.
Figure 4b is a graph showing the catalytic performance of the ESC and SAC for the _three- way catalytic C 3 H ₆ conversion reaction according to an embodiment of the present invention.
Figure 4c is a graph showing the catalytic performance of the ESC and SAC for the _three- way catalyst C 3 H ₈ conversion reaction according to an embodiment of the present invention.
4D is a graph showing the catalytic performance of ESCs and SACs for a three-way catalytic NO conversion reaction according to an embodiment of the present invention.
4E is a graph showing the catalytic performance of ESC and SAC with respect _{to N 2} selectivity in a three-way catalytic NO conversion reaction according to an embodiment of the present invention.
Figure 4f shows the conversion change of _{CO, C 3} H ₆ , C ₃ H ₈ and NO at a specific temperature during hydrothermal aging (HT) of Pt ESC, Pd ESC and Rh ESC according to an embodiment of the present invention; It is a graph.
Figure 4g is a graph showing the long-term durability test results using the Pt ESC at 150 ℃ according to an embodiment of the present invention.
Figure 4h is a graph showing the long-term durability test results using the Pd ESC at 150 ℃ according to an embodiment of the present invention.
Figure 4i is a graph showing the long-term durability test results using the Rh ESC at 150 ℃ according to an embodiment of the present invention.
Figure 5a is a diffuse reflection infrared Fourier transform (DRIFT) obtained by CO adsorption of hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction and metal structure change after 3 cycles of repeated TWC of Pt ESCs according to an embodiment of the present invention. ) is the spectrum.
Figure 5b is a diffuse reflection infrared Fourier transform (DRIFT) obtained by CO adsorption of hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction and metal structure change after 3 cycles of repeated TWC of Pd ESCs according to an embodiment of the present invention. ) is the spectrum.
Figure 5c is a diffuse reflection infrared Fourier transform (DRIFT) obtained by CO adsorption of hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction and metal structure change after 3 cycles of repeated TWC of Rh ESCs according to an embodiment of the present invention. ) is the spectrum.
Figure 5d is k3 weighted FT-EXAFS data for confirming the metal structure change after hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction, and repeated TWC of 3 cycles of Pt ESCs according to an embodiment of the present invention.
Figure 5e is k3-weighted FT-EXAFS data for confirming the metal structure change after hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction, and repeated TWC of 3 cycles of Pd ESCs according to an embodiment of the present invention.
5f is k3-weighted FT-EXAFS data for confirming metal structure changes after hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction and 3 cycles of repeated TWC of Rh ESCs according to an embodiment of the present invention.
Figure 5g shows the metal state estimated from the XANES spectrum and the XPS spectrum for hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction, and metal structure change confirmation after 3 cycles of repeated TWC of Pt ESCs according to an embodiment of the present invention. is the ratio of
Figure 5h shows the metal state estimated from the XANES spectrum and the XPS spectrum for hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction, and metal structure change confirmation after 3 cycles of repeated TWC of Pd ESCs according to an embodiment of the present invention; is the ratio of
Figure 5i shows the metal state estimated from the XANES spectrum and the XPS spectrum for confirming the metal structure change after hydrothermal aging (HT), long-term three-way catalytic (TWC) reaction and 3 cycles of repeated TWC of Rh ESCs according to an embodiment of the present invention; is the ratio of
6 is a graph showing the result of temperature programmed reduction of a γ-alumina support using hydrogen (H2-TPR) according to an embodiment of the present invention.
7A is an infrared (IR) peak integration graph of geminal dicarbonyl adsorption at the Rh site of a 40 Rh catalyst according to an embodiment of the present invention.
7B is an infrared (IR) peak integration graph of geminal dicarbonyl adsorption at the Rh site of a 60 Rh catalyst according to an embodiment of the present invention.
7c is an infrared (IR) peak integration graph of geminal dicarbonyl adsorption at the Rh site of an 80 Rh catalyst according to an embodiment of the present invention.
7D is an infrared (IR) peak integration graph of geminal dicarbonyl adsorption at the Rh site of a 90 Rh catalyst according to an embodiment of the present invention.
7E is an infrared (IR) peak integration graph of geminal dicarbonyl adsorption at the Rh site of the Rh/CA catalyst according to an embodiment of the present invention.
7f is an infrared (IR) peak integration graph of geminal dicarbonyl adsorption at the Rh site of the Rh/rA catalyst according to an embodiment of the present invention.
FIG. 8a is a diagram showing the most stable CO adsorption metal configuration (CO on Pt ₁ /CeO ₂ as linear top mode) in _{CeO 2 (111) according to an embodiment of the present invention.} (Red, O; Grey, C; White, Ce; Cyan, M (M = Pt, Pd or Rh))
FIG. 8b is a diagram showing the most stable CO adsorption metal configuration (CO on upper layer of Pt ₄ /CeO ₂ as linear top mode) in _{M/CeO 2 (111) according to an embodiment of the present invention.}
FIG. 8c is a diagram showing the most stable CO adsorption metal configuration (CO on Pd ₁ /CeO ₂ as linear top mode) in _{M/CeO 2 (111) according to an embodiment of the present invention.}
FIG. 8d is a diagram showing the most stable CO adsorption metal configuration (CO on upper layer of Pd ₄ /CeO ₂ as linear top mode) in _{M/CeO 2 (111) according to an embodiment of the present invention.}
FIG. 8e is a diagram showing the most stable CO adsorption metal configuration (CO on lower layer of Pd ₄ /CeO ₂ as linear top mode) in _{M/CeO 2 (111) according to an embodiment of the present invention.}
8f is a diagram showing the most stable CO adsorption metal configuration (CO on Rh ₁ /CeO ₂ as geminal dicarbonyl mode) in _{M/CeO 2} (111) according to an embodiment of the present invention.
8g is a diagram showing the most stable CO adsorption metal configuration (CO on upper layer of Rh ₄ /CeO ₂ as linear top mode) in _{M/CeO 2} (111) according to an embodiment of the present invention.
9A is k3-weighted Fourier transform-extended X-ray absorption microstructure (FT-EXAFS) data showing X-ray absorption spectroscopy (XAS) experiments and fitting results of Pt samples according to an embodiment of the present invention.
9B is k3-weighted Fourier transform-extended X-ray absorption microstructure (FT-EXAFS) data showing the X-ray absorption spectroscopy (XAS) experiment and fitting results of a Pd sample according to an embodiment of the present invention.
9C is k3-weighted Fourier transform-extended X-ray absorption microstructure (FT-EXAFS) data showing the X-ray absorption spectroscopy (XAS) experiment and fitting results of Rh samples according to an embodiment of the present invention.
10A is a graph showing the catalytic activity in _{C 3} H _{6 oxidation of a CeO 2} -rAl ₂ O ₃ supported Pt catalyst impregnated at different temperatures (40, 60, or 80° C.) according to an embodiment of the present invention; FIG. .
10B is a graph showing the catalytic activity in _{C 3} H _{8 oxidation of CeO 2} -rAl ₂ O ₃ supported Pt catalyst impregnated at different temperatures (40, 60, or 80° C.) according to an embodiment of the present invention; FIG. .
10c is a graph showing the catalytic activity in _{C 3} H _{6 oxidation of a CeO 2} -rAl ₂ O ₃ supported Pd catalyst impregnated at different temperatures (40, 60, or 80° C.) according to an embodiment of the present invention. .
10D is a graph showing the catalytic activity in _{C 3} H _{8 oxidation of a CeO 2} -rAl ₂ O ₃ supported Pd catalyst impregnated at different temperatures (40, 60, or 80° C.) according to an embodiment of the present invention. .
10e is a graph showing the catalytic activity in _{C 3} H _{6 oxidation of CeO 2} -rAl ₂ O ₃ supported Rh catalyst impregnated at different temperatures (40, 60, 80 or 90° C.) according to an embodiment of the present invention; to be.
10f is a graph showing the catalytic activity in _{C 3} H _{8 oxidation of CeO 2} -rAl ₂ O ₃ supported Rh catalyst impregnated at different temperatures (40, 60, 80 or 90° C.) according to an embodiment of the present invention; to be.
_{11 is a diagram for γ-Al 2} O ₃ , pre-reduced γ-Al ₂ O ₃ (r-Al ₂ O ₃ ), CeO ₂ -rAl ₂ O ₃ , metal ESC and SAC according to an embodiment of the present invention. ^{A graph showing the results of 27} Al magic angle spinning (MAS)-nuclear magnetic resonance (NMR) spectroscopy.
12a is an X-ray photoelectron spectroscopy (XPS) spectrum graph of _{CeO 2} -rAl ₂ O ₃ showing the difference in the oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention; FIG. .
12b is an X-ray photoelectron spectroscopy (XPS) spectrum graph of _{CeO 2} -Al ₂ O ₃ showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention; FIG. .
12c is an X-ray photoelectron spectroscopy (XPS) spectrum graph of Pt ESCs showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention.
12d is an X-ray photoelectron spectroscopy (XPS) spectrum of _{Pt/CeO 2} -Al ₂ O ₃ showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention; FIG. It is a graph.
12E is an X-ray photoelectron spectroscopy (XPS) spectrum graph of Pd ESCs showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention.
12f is an X-ray photoelectron spectroscopy (XPS) spectrum of _{Pd/CeO 2} -Al ₂ O ₃ showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention; FIG. It is a graph.
12g is an X-ray photoelectron spectroscopy (XPS) spectrum graph of Rh ESC showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention.
12h is an X-ray photoelectron spectroscopy (XPS) spectrum of _{Rh/CeO 2} -Al ₂ O ₃ showing the difference in oxidation state of cerium with or without prior reduction of _{γ-Al 2} O ₃ according to an embodiment of the present invention; FIG. It is a graph.
13A is a graph showing the temperature-programmed reduction results of _{Pt ESC and Pt/CeO 2} -Al ₂ O ₃ using hydrogen (H2-TPR) according to an embodiment of the present invention.
13B is a graph showing the results of temperature-programmed reduction of _{Pd ESC and Pd/CeO 2} -Al ₂ O ₃ using hydrogen (H2-TPR) according to an embodiment of the present invention.
13c is a graph showing the temperature-programmed reduction results of _{Rh ESC and Rh/CeO 2} -Al ₂ O ₃ using hydrogen (H2-TPR) according to an embodiment of the present invention.
14A is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image showing the morphology of Pt ESCs according to an embodiment of the present invention. (Yellow circle: Metal ESC, Left: Low magnification. Right: High magnification)
14B is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image showing the morphology of Pt ESCs according to an embodiment of the present invention.
14C is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing the morphology of Pd ESCs according to an embodiment of the present invention.
14D is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing the morphology of Pd ESCs according to an embodiment of the present invention.
14E is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing the morphology of Rh ESCs according to an embodiment of the present invention.
14F is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image showing the morphology of Rh ESCs according to an embodiment of the present invention.
15A is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing _{rAl 2} O ₃ according to an embodiment of the present invention.
15B is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing _{CeO 2} -rAl ₂ O ₃ according to an embodiment of the present invention.
15C is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing _{CeO 2} -rAl ₂ O ₃ according to an embodiment of the present invention.
15D is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing Pt SAC according to an embodiment of the present invention.
15E is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing a Pd SAC according to an embodiment of the present invention.
15F is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing Rh SAC according to an embodiment of the present invention.
15G is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing Pt ESCs according to an embodiment of the present invention.
15H is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing Pt SAC according to an embodiment of the present invention.
15I is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing a Pd ESC according to an embodiment of the present invention.
15J is a high angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing a Pd SAC according to an embodiment of the present invention.
15K is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing Rh ESCs according to an embodiment of the present invention.
15L is a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) image showing Rh SAC according to an embodiment of the present invention.
15M is an energy-dispersive X-ray spectroscopy (EDS) mapping image of a Pt ESC according to an embodiment of the present invention. (Red: Pt, Pd or Rh, Yellow: Ce, Gray: Al)
15N is an energy-dispersive X-ray spectroscopy (EDS) mapping image of Pt SAC according to an embodiment of the present invention.
15O is an energy-dispersive X-ray spectroscopy (EDS) mapping image of a Pd ESC according to an embodiment of the present invention.
15P is an energy-dispersive X-ray spectroscopy (EDS) mapping image of a Pd SAC according to an embodiment of the present invention.
15Q is an energy-dispersive X-ray spectroscopy (EDS) mapping image of Rh ESCs according to an embodiment of the present invention.
15R is an energy-dispersive X-ray spectroscopy (EDS) mapping image of Rh SAC according to an embodiment of the present invention.
16A is an X-ray diffraction (XRD) spectrum before and after hydrothermal aging (HT) of ESCs and SACs according to an embodiment of the present invention.
16B is an XRD spectrum before and after hydrothermal aging (HT) of _{CeO 2} -rAl ₂ O ₃ and CeO ₂ -Al ₂ O ₃ according to an embodiment of the present invention.
16C is an XRD spectrum before and after hydrothermal aging (HT) of _{γ-Al 2} O ₃ and rAl ₂ O ₃ according to an embodiment of the present invention.
17A is 40 for a three-way catalytic (TWC) reaction according to an embodiment of the present invention.

Impregnated in the _{M / CeO 2 -rAl 2 O 3} (ESCs), M / CeO 2 -Al 2 O 3 (M / CA) and _{M / rAl 2 O 3 (M} / rA) (M = Pt, Pd , and Rh ) is a graph showing the CO conversion activity of
17B shows 40 for a three-way catalytic (TWC) reaction according to an embodiment of the present invention.

Impregnated in the _{M / CeO 2 -rAl 2 O 3} (ESCs), M / CeO 2 -Al 2 O 3 (M / CA) and _{M / rAl 2 O 3 (M} / rA) (M = Pt, Pd , and Rh ) is a graph showing the conversion activity of C ₃ H _{6 .}
17C shows 40 for a three-way catalytic (TWC) reaction according to an embodiment of the present invention.

Impregnated in the _{M / CeO 2 -rAl 2 O 3} (ESCs), M / CeO 2 -Al 2 O 3 (M / CA) and _{M / rAl 2 O 3 (M} / rA) (M = Pt, Pd , and Rh ) is a graph showing the conversion activity of C ₃ H _{8 .}
17D shows 40 for a three-way catalytic (TWC) reaction according to an embodiment of the present invention.

Impregnated in the _{M / CeO 2 -rAl 2 O 3} (ESCs), M / CeO 2 -Al 2 O 3 (M / CA) and _{M / rAl 2 O 3 (M} / rA) (M = Pt, Pd , and Rh ) is a graph showing the NO conversion activity of
17E shows 40 for a three-way catalytic (TWC) reaction according to an embodiment of the present invention.

Impregnated in the _{M / CeO 2 -rAl 2 O 3} (ESCs), M / CeO 2 -Al 2 O 3 (M / CA) and _{M / rAl 2 O 3 (M} / rA) (M = Pt, Pd , and Rh ) is a graph showing the N _{2 selectivity of}
18A is a graph showing the catalytic performance of ESCs and SACs for CO oxidation (1% CO and 1% O _{2 balanced with He) according to an embodiment of the present invention.}
18B is a graph showing NO conversion rates of ESCs and SACs for NO reduction by CO (200 ppm NO and 0.2% CO balanced with He) according to an embodiment of the present invention.
18C is a graph showing _{the N 2} selectivity of ESC and SAC for NO reduction by CO (200 ppm NO and 0.2% CO balanced with He) according to an embodiment of the present invention.
19A is a graph showing the CO conversion catalytic performance of metal ESCs and SACs for a three-way catalytic (TWC) reaction after hydrothermal aging according to an embodiment of the present invention.
_{19B is a graph showing the C 3} H ₆ conversion catalyst performance of metal ESCs and SACs for a three-way catalytic (TWC) reaction after hydrothermal aging according to an embodiment of the present invention.
_{19c is a graph showing the C 3} H ₈ conversion catalytic performance of metal ESCs and SACs for a three-way catalytic (TWC) reaction after hydrothermal aging according to an embodiment of the present invention.
19D is a graph showing the NO conversion catalytic performance of metal ESCs and SACs for (HT) three-way catalytic (TWC) reaction after hydrothermal aging according to an embodiment of the present invention.
19E is a graph showing _{the N 2} selectivity of metal ESCs and SACs for a three-way catalytic (TWC) reaction after hydrothermal aging (HT) according to an embodiment of the present invention.
_{Figure 20a shows the CO conversion catalyst performance of M/CeO 2} -Al ₂ O ₃ (M = Pt, Pd, Rh) for a three-way catalytic (TWC) reaction after hydrothermal aging (HT) according to an embodiment of the present invention; It is a graph.
_{20b is a C 3} H ₆ conversion catalyst of _{M/CeO 2} -Al ₂ O ₃ (M = Pt, Pd, Rh) for a three-way catalyst (TWC) reaction after hydrothermal aging (HT) according to an embodiment of the present invention; This is a graph showing the performance.
_{20c is a C 3} H ₈ conversion catalyst of _{M/CeO 2} -Al ₂ O ₃ (M = Pt, Pd, Rh) for a three-way catalytic (TWC) reaction after hydrothermal aging (HT) according to an embodiment of the present invention; This is a graph showing the performance.
_{Figure 20d shows the NO conversion catalyst performance of M/CeO 2} -Al ₂ O ₃ (M = Pt, Pd, Rh) for a three-way catalytic (TWC) reaction after hydrothermal aging (HT) according to an embodiment of the present invention; It is a graph.
_{Figure 20e shows the N 2} selectivity _{of M/CeO 2} -Al ₂ O ₃ (M = Pt, Pd, Rh) for a three-way catalytic (TWC) reaction after hydrothermal aging (HT) according to an embodiment of the present invention; It is a graph.
_{20f is a view showing} the hydrothermal aging (HT) of _{Pt/CeO 2} -Al ₂ O ₃ , Pd/CeO ₂ -Al ₂ O ₃ and Rh/CeO ₂ -Al ₂ O 3 according to an embodiment of the present invention; It is a graph showing the conversion change of CO, C ₃ H ₆ , C ₃ H _{8 and NO at specific temperatures.}
21A is a graph showing the catalytic CO conversion performance of metal ESCs and SACs for a second cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21B is a graph showing _{the catalytic C 3} H ₆ conversion performance of metal ESCs and SACs for a second cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21C is a graph showing _{the catalytic C 3} H ₈ conversion performance of metal ESCs and SACs for a second cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21D is a graph showing the catalytic NO conversion performance of metal ESCs and SACs for a second cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21E is a graph showing _{the catalytic N 2} selectivity of metal ESCs and SACs for a second cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21F is a graph showing the CO conversion performance of metal ESCs and SACs for a third cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21G is a graph showing _{the C 3} H ₆ conversion performance of metal ESCs and SACs for a third cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21H is a graph showing _{the C 3} H ₈ conversion performance of metal ESCs and SACs for a third cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21I is a graph showing the NO conversion performance of metal ESCs and SACs for a third cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
21J is a graph showing _{the N 2} selectivity of metal ESCs and SACs for a third cycle three-way catalytic (TWC) reaction according to an embodiment of the present invention.
22A is k3-weighted FT-EXAFS data after various endurance tests of hydrothermal aging, long-term TWC response, and repeated TWC response of Pt ESCs according to an embodiment of the present invention.
22B is k3-weighted FT-EXAFS data after various endurance tests of hydrothermal aging, long-term TWC response and repeated TWC response of Pd ESCs according to an embodiment of the present invention.
22C is k3-weighted FT-EXAFS data after various endurance tests of hydrothermal aging, long-term TWC response, and repeated TWC response of Rh ESCs according to an embodiment of the present invention.
23A is an X-ray photoelectron spectroscopy (XPS) spectrum showing electronic properties after a hydrothermal aging (HT) durability test of a Pt ESC according to an embodiment of the present invention.
23B is an X-ray photoelectron spectroscopy (XPS) spectrum showing electronic properties after a hydrothermal aging (HT) durability test of a Pd ESC according to an embodiment of the present invention.
23C is an X-ray photoelectron spectroscopy (XPS) spectrum showing electronic properties after a hydrothermal aging (HT) durability test of Rh ESCs according to an embodiment of the present invention.
FIG. 23D is an X-ray photoelectron spectroscopy (XPS) spectrum showing the electronic properties of Pt ESCs after a durability test of a long-term three-way catalytic (TWC) reaction according to an embodiment of the present invention.
23E is an X-ray photoelectron spectroscopy (XPS) spectrum showing the electronic properties of Pd ESCs after a durability test of a long-term three-way catalytic (TWC) reaction according to an embodiment of the present invention.
23f is an X-ray photoelectron spectroscopy (XPS) spectrum showing electronic properties after a durability test of a long-term three-way catalytic (TWC) reaction of Rh ESCs according to an embodiment of the present invention.
23G is an X-ray photoelectron spectroscopy (XPS) spectrum showing the electronic properties of Pt ESCs after repeated three-way catalytic (TWC) reaction three endurance tests according to an embodiment of the present invention.
23H is an X-ray photoelectron spectroscopy (XPS) spectrum showing the electronic properties of Pd ESCs after three-time durability test of repeated three-way catalytic (TWC) reactions according to an embodiment of the present invention.
23I is an X-ray photoelectron spectroscopy (XPS) spectrum showing the electronic properties of Rh ESCs after repeated three-way catalytic (TWC) reaction three-time durability test according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, these examples are only for illustrating the present invention, and the scope of the present invention is not limited by these examples.

manufacturing example. Catalyst preparation

Commercial γ-alumina (99.97%, Alfa Aesar) was pre-reduced by flowing _{10% H 2} /N ₂ ^{at 350° C. for 1 hour to generate tunable unsaturated Al 3+} penta sites. The reduction temperature of 350 °C was determined from a temperature programmed reduction using _{hydrogen (H 2 -TPR), as shown in FIG. 6 .}

The metal catalyst was prepared by sequential impregnation method as follows. Ceria was first impregnated with reduced γ-alumina (rAl ₂ O ₃ ), and then noble metals (M = Pt, Pd and Rh) were impregnated with _{CeO 2} -rAl ₂ O _{3 .} The amounts of noble metal and ceria were 1 and 10% by weight, respectively. Ce(NO ₃ ) ₃ ·6H ₂ O (99.99%, Kanto chemical) was homogeneously dissolved in 5 mL deionized water in a 50 mL three-necked round bottom flask while stirring at 700 rpm. After the pre-reduced γ-alumina was introduced into the cerium precursor solution, the solution was continuously stirred at room temperature for 1 hour. The solution was then heated to the target metal impregnation temperature (40, 60, 80 or 90 °C).

The impregnation temperature is a key factor to accurately control the metal structure. When the impregnation temperature is high, evaporation is accelerated and the metal structure is separated, and when the impregnation temperature is low, evaporation is slow, and a metal ensemble structure is formed.

For platinum catalyst _{, homogeneously dissolve H 2} PtCl ₆ .6H ₂ O (≤ 100%, Sigma-Aldrich) in 5 mL of deionized water until it becomes a clear solution, and then, while stirring the platinum precursor solution, CeO ₂ - It was placed in a _{rAl 2} O _{3 solution.} Stirring was continued at 700 rpm at the target immersion temperature until the synthesis solution was completely evaporated. After sequential impregnation, the resulting powder was dried overnight at 80° C. in a convection oven, and then the dried powder was calcined in static air at 500° C. at a ramping rate of 5° C./min. Finally, the calcined powder was reduced at 500° C. in 10% H ₂ /N ₂ for 2 hours at a ramping rate of 10° C./min to produce _{a Pt/CeO 2 -rAl 2} O _{3 catalyst.} For palladium or rhodium catalysts, H ₂ PdCl ₄ or H ₂ RhCl ₅ solutions were prepared prior to impregnation. HCl to PdCl ₂ (99%, Sigma-Aldrich) or RhCl ₃ .xH ₂ O (99.98%, Sigma-Aldrich) was mixed in 5 mL of deionized water in a molar ratio of 2:1, and then the solution was shaken until transparent and homogeneous. gave. Other procedures were the same as Pt/CeO ₂ -rAl ₂ O ₃ synthesis to produce Pd/CeO ₂ -rAl ₂ O ₃ and Rh/CeO ₂ -rAl ₂ O ₃ catalysts.

experimental example. Characterizations Experimental Methods

To investigate the metal structure in M/CeO ₂ -rAl ₂ O ₃ , CO adsorption on the catalyst was performed by diffuse reflection Fourier-transform infrared spectroscopy (DRIFT) using a Nicolet iS-50 (Thermo Scientific). Specifically, the catalyst was mixed with KBr powder in a weight ratio of 1:7 and finely ground. The mixed powder was placed in a sample cup and placed in a DRIFT cell. The cell was purged with a stream of Ar at 100° C. for 1 hour to remove water and impurities and cooled to room temperature under a stream of Ar flow. Room temperature 2% CO gas with Ar balance was flowed for 10 min, and DRIFT spectra were collected under vacuum to exclude gaseous CO peaks.

X-ray absorption spectroscopy (XAS) of Pt L3, Pd K and Rh K edges was performed using 8C nano XAFS and 10C wide XAFS beamlines from Pohang Light Source (PLS). Pt L3, Pd K and Rh K edge spectra were obtained in fluorescence mode using a passivated implanted planar silicon (PIPS) detector (Canberra). Reference Pt, Pd and Rh foils were also measured simultaneously to calibrate each sample. XAS data were processed and fitted using the ATHENA and ARTEMIS software programs. The coordination number was derived by fixing the SO2 value obtained by fitting a reference metal foil. The Debye-Waller factor (σ2) was fixed to an appropriate value when the number of independent points is limited.

The dispersion of noble metals in the catalyst was determined by a pulsed CO chemisorption technique modified by the method of Takeguchi et al. First, 50 mg of the catalyst _{was heated in 3.5% O 2} /He gas at 300° C. for 10 minutes, then the sample was purged with He gas for 5 minutes and cooled to 50° C. The sample was then heated to 200° C. in a flow of 5% H _{2 /Ar.} After cooling to 50° C., the samples were exposed to a gas stream in the following sequence: (i) He (5 min); (ii) 3.5% O ₂ /He (5 min); (iii) CO ₂ (10 min); (iv) He (20 min); (v) 5% H ₂ /Ar (5 min). _{CO 2} was pre-injected to form carbonate on the ceria surface. Otherwise, the metal dispersion may be overestimated, as CO can be adsorbed on the ceria surface to form carbonates. Finally, CO was pulsed in a stream of He every minute until the CO chemisorption on the catalyst was saturated. A representative H ₂ chemisorption method was also performed to measure the dispersion of noble metals. First, 50 mg of the catalyst _{was heated in 5% H 2} /Ar at 500 °C for 1 h and then cooled to 30 °C. The catalyst was then evacuated in Ar flow at 400°C for 4 h and then cooled to 30°C. _{Finally, H 2} was pulsed in a stream of Ar every minute until _{the H 2} chemisorption on the catalyst was saturated.

High angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) images and energy dispersive X-ray spectroscopy (EDS) mapping images were obtained using a Titan cubed G2 60-300 (FEI) with an accelerating voltage of 300 kV. . The electronic properties of platinum, palladium, rhodium and cerium were investigated by X-ray photoelectron spectroscopy (XPS, K-Alpha, Thermo VG Scientific). The binding energy was calculated based on the maximum intensity of the favorable Cl signal at 284.8 eV.

Inductively Coupled Plasma Light Emission Spectroscopy (ICP-OES) analysis was performed on an Agilent ICP-OES 5110 instrument to determine the actual amount of noble metals and ceria in the catalyst. The crystal structure of the catalyst was observed by powder X-ray diffraction (XRD) pattern (Rigaku, Cu Kα radiation). The Brunauer-Emmett-Teller (BET) surface area of the catalyst was measured using a Tristar II 3020 (Micromeritics). Solid state 27Al magic magic spinning (MAS) nuclear magnetic resonance (NMR) measurements were performed at room temperature on an Agilent 400 MHz 54 mm NMR DD2 operating in a 9.4 T magnetic field. Al ³⁺ sites (tetrahedral, pentahedral and octahedral coordination Al ³⁺ ) were identified in γ-alumina, rAl ₂ O ₃ , CeO ₂ -rAl ₂ O ₃ and various M/CeO ₂ -rAl ₂ O _{3 catalysts.} H ₂ -TPR was performed on a BELCAT-B (BEL, Japan) equipped with mass spectrometry (MS) and thermal conductivity detector (TCD). Before H ₂ -TPR measurement, the catalyst was pretreated by flowing 50 sccm of Ar at 250° C. for 2 hours, and cooled to room temperature. Then, a 5% H ₂ /Ar gas flow was introduced and heated to 800° C. at a ramp rate of 10° C./min.

Catalytic reactions

_{A three-} way catalyst (TWC) reaction was performed in which carbon monoxide, hydrocarbons, and nitrogen oxides were simultaneously removed using the prepared M/CeO ₂ -rAl ₂ O 3 catalyst. The reactor and catalyst were purged with 100 sccm of He gas at 100° C. for 1 hour, and then cooled to room temperature under a He flow to remove impurities. The TWC reaction was carried out at atmospheric pressure. A total of 200 sccm of feed gas was mixed with 2% CO, 0.1% C ₃ H ₆ , 0.1% C ₃ H ₈ , 500 ppm NO, 1.75% O ₂ and 5% H ₂ O in He balance with 60 mg of catalyst (gas per hour). space velocity, GHSV = 200,000 ml·hr ⁻¹ g _cat ⁻¹ ). The air-to-fuel ratio (λ) is defined as λ = (2[O ₂ ] + [NO]) / ([CO] + 9[C ₃ H ₆ ] + 10[C ₃ H ₈ ]) λ is 0.91. The reactor was heated to the target reaction temperature at a ramping rate of 5° C./min and held at that temperature for 30 minutes to reach a steady state. The product gas was run on a packed bed carboxy 1000 column (75035, SUPELCO, 15 ft X 1/8 in X 2.1 mm) and a GS-GASPRO column (USN135514H, 30 m X) with a thermal conductivity detector (TCD) and flame ionization detector (FID), respectively. 0.32 mm) was analyzed using online gas chromatography (GC, Younglin GC 6500 system). In addition, the outlet gas was analyzed using a Fourier-transform infrared (FT-IR) spectrometer (Nicolet iS 10, Thermo Scientific) with a gas measuring cell (Cyclone C2, Specac, internal volume of 0.19 L). The catalyst was subjected to hydrothermal aging (HT) by flowing air containing _{10% H 2} O at 900° C. for 24 hours.

computational calculation

Density functional theory (DFT) calculations were performed using Vienna Ab initio Software Package (VASP) to estimate the oscillation frequency and confirm the peak allocation of adsorbed CO in the DRIFT experiment. The ion-electron interactions were handled using the projector-augmented wave (PAW) method, and the Perdew-Burke-Ernzerhof (PBE) exchange correlation function was used for all calculations. The Hubbard U correction was used to accurately describe the Ce 4f state in the Ce 3f state, and an effective U parameter of 5 eV was selected from the results of previous papers. A plane wave with a cutoff energy of 408 eV was used for all calculations, and a force threshold of 0.02 eV/Å was used for shape optimization. A 5 X 5 X 1 Monkhorst-Pack kpoint grid was used for all calculations using the slab model.

First, we fully optimized the bulk ceria unit cell and split the relaxed cell into the most dominant (111) plane on the ceria surface. A vacuum layer of 15 Å was added to the (111) surface of ceria to create the slab constituting the model system. The slab structure consisting of three O-Ce-O layers was relaxed. The atoms of the lowest O-Ce-O layer were fixed, and the positions of all other atoms were optimized. A tetrahedral single metal atom or metal ensemble consisting of 1 or 4 metal atoms (Pt, Pd and Rh) was deposited on the (111) surface of ceria, and the metal/ceria system was completely relaxed. The positions of metal atoms and ensembles in the previous paper were used as initial positions of metal atoms in this system, and then carbon monoxide was added to the system and completely relaxed. The vibrational frequencies of CO molecules adsorbed to single atoms and ensembles were obtained from a fully relaxed CO/metal/ceria system.

Experiment result

The experimental results performed according to the above method are shown in Tables 1 to 11 below.

_{Table 1: CeO 2} -rAl ₂ O ₃ supported noble metal catalysts (Pt, Pd and Rh) metal dispersions and average domain sizes impregnated at different temperatures (40, 60, 80 or 90 °C). ^a

_{Table 2: Metal dispersion and average domain size of CeO 2} -rAl ₂ O ₃ supported noble metal catalysts (Pt, Pd and Rh) impregnated at different temperatures (40, 60, 80 or 90 °C). ^a

Table 3: The theoretical wavenumber of CO adsorbed on _{M/CeO 2} (111) calculated by density functional theory (DFT). Consider two structures: a metal single-atom (M ₁ ) and a cluster consisting of four metal atoms (M _{4 ).}

Table 4: Infrared (IR) peak information of the same dicarbonyl adsorption at the Rh site of various Rh catalysts. The angles between adsorbed CO molecules were estimated using the areas of symmetric and asymmetric peaks.

Table 5: Extended X-ray absorption microstructures _{of CeO 2} -rAl ₂ O ₃ supported platinum catalyst impregnated at 40, 60 or 80 °C _{and CeO 2} -Al ₂ O ₃ and rAl ₂ O ₃ supported platinum catalyst impregnated at 40 °C Best fit value according to Structural (EXAFS) analysis.

Table 6: Extended X-ray absorption microstructures _{of CeO 2} -rAl ₂ O ₃ supported palladium catalysts impregnated at 40, 60 or 80 °C _{and CeO 2} -Al ₂ O ₃ and rAl ₂ O ₃ supported palladium catalysts impregnated at 40 °C The most suitable fitting value according to the structural (EXAFS) analysis.

Table 7: Extended X-rays _{of CeO 2} -rAl ₂ O ₃ supported rhodium catalysts impregnated at 40, 60, 80 or 90° C. _{and CeO 2} -Al ₂ O ₃ and rAl ₂ O ₃ supported rhodium catalysts impregnated at 40° C. The best fit value according to absorption microstructure (EXAFS) analysis.

Table 8: Brunauer-Emmett-Teller (BET) surface areas of _{γ-Al 2} O _{3 , rAl 2} O ₃ , CeO ₂ -rAl ₂ O _{3 and metal ESCs and SACs.}

Table 9: Metal dispersion and EXAFS fitting results of Pt ESCs after various durability evaluations.

Table 10: Metal dispersion and EXAFS fitting results of Pd ESCs after various durability evaluations.

Table 11: Metal dispersion and EXAFS fitting results of Rh ESCs after various durability evaluations.

Catalyst Dispersion (%) after calcination Size (nm)
after calcination Dispersion (%) after reduction ^e Size (nm)
after reduction ^e 40Pt ^b 101.2 ≤0.9 100.4 ≤0.9 60Pt ^b 100.9 ≤0.9 101.5 ≤0.9 80Pt ^b 103.0 ≤0.9 102.7 ≤0.9 40Pd ^b 103.0 ≤0.9 101.4 ≤0.9 60Pd ^b 102.7 ≤0.9 103.5 ≤0.9 80Pd ^b 101.6 ≤0.9 102.9 ≤0.9 40Rh ^b 162.0 ≤0.9 160.6 ≤0.9 60Rh ^b 183.6 ≤0.9 184.3 ≤0.9 80Rh ^b 192.8 ≤0.9 192.9 ≤0.9 90Rh ^b 202.1 ≤0.9 201.5 ≤0.9 Pt/CA ^c 31.4 2.9 14.0 6.5 Pd/CA ^c 50.6 1.8 10.5 8.7 Rh/CA ^c 36.4 2.5 12.9 7.0 Pt/rA ^d 47.8 1.9 16.9 5.4 Pd/rA ^d 57.0 1.6 11.2 8.2 Rh/rA ^d 50.5 1.8 12.9 7.0

^a The metal dispersion was measured by pulsed CO chemisorption and the domain size was estimated from the dispersion data. The ratio of M:CO = 1:1 was used.

^b In the M/CeO ₂ -rAl ₂ O ₃ catalysts, γ-alumina was pre-reduced at 350°C, then ceria and precious metal were sequentially impregnated at 40, 60, 80, or 90°C.

^c The ceria and precious metal were sequentially impregnated to fresh γ-alumina at 40℃.

^d The γ-alumina was pre-reduced at 350℃, then precious metal was impregnated at 40℃.

^e The reduction was performed by flowing 10% H ₂ /N ₂ at 500℃ for 2 h.

Catalyst Dispersion (%) after calcination Size (nm)
after calcination Dispersion (%) after reduction ^e Size (nm)
after reduction ^e 40Pt ^b 103.4 ≤0.9 102.6 ≤0.9 60Pt ^b 102.7 ≤0.9 103.0 ≤0.9 80Pt ^b 102.9 ≤0.9 101.9 ≤0.9 40Pd ^b - - - - 60Pd ^b - - - - 80Pd ^b - - - - 40Rh ^b 101.7 ≤0.9 102.0 ≤0.9 60Rh ^b 100.6 ≤0.9 102.4 ≤0.9 80Rh ^b 102.0 ≤0.9 100.4 ≤0.9 90Rh ^b 101.5 ≤0.9 101.6 ≤0.9 Pt/CA ^c 33.6 2.7 15.2 6.0 Pd/CA ^c - - - - Rh/CA ^c 29.7 3.1 11.6 7.9 Pt/rA ^d 46.8 1.9 18.5 4.9 Pd/rA ^d - - - - Rh/rA ^d 39.5 2.3 11.7 7.8

^a The metal dispersion was measured by pulsed H ₂ chemisorption and the domain size was estimated from the dispersion data. The ratio of M:H = 1:1 was used.

^b In the M/CeO ₂ -rAl ₂ O ₃ catalysts, γ-alumina was pre-reduced at 350 °C, then ceria and precious metal were sequentially impregnated at 40, 60, 80, or 90 °C.

^c The ceria and precious metal were sequentially impregnated to fresh γ-alumina at 40 ℃.

^d The γ-alumina was pre-reduced at 350 ℃, then precious metal was impregnated at 40 ℃.

^e The reduction was performed by flowing 10% H ₂ /N ₂ at 500 ℃ for 2 h.

Structure Calculated
wavenumber (cm ^-1 ) experimental
wavenumber (cm ^-1 ) ^a Pt ₁ /CeO ₂ (111) 2021.2 2108 Pt ₄ /CeO ₂ (111) 2006.9 2083 Pd ₁ /CeO ₂ (111) 2024.8 2142 Pd ₄ /CeO ₂ (111) 2016.6, 1971.7 2116, 2075 Rh ₁ /CeO ₂ (111) 2061.9, 1984.7 2114, 2090 Rh ₄ /CeO ₂ (111) 1947.2 2019

^a The values were chosen from DRIFT results in Figure 1 (bd).

Sample Rh(CO) ₂ symmetric stretching (cm ^-1 ) A _sym ^a Rh(CO) ₂ asymmetric stretching (cm ^-1 ) A _asym ^a 2α(°) ^b 40 Rh 2114.2 0.73 2090.4 1.31 106 60 Rh 2114.2 0.58 2090.4 0.84 101 80 Rh 2114.2 0.62 2090.4 0.71 94 90 Rh 2114.2 0.72 2090.4 0.70 89 Rh/CeO ₂ -Al ₂ O ₃ 2114.2 0.30 2090.4 0.77 116 Rh/rAl ₂ O ₃ 2114.2 0.36 2090.4 0.80 116

^a The area of the symmetric or asymmetric peaks estimated from Figure 8.

^b The angle between the adsorbed CO molecules was estimated from the equation of tan ² α = A _asym /A _sym .

Sample Path Coordination number (R) Interatomic distance (Å) Debye-Waller factor
(σ ² /Å ² ) R-factor 40 Pt Pt-O 3.21 1.98 0.003 0.014 Pt-Pt 1.32 2.82 0.003 Pt-Ce 1.98 2.86 0.001 Pt-Ce 0.87 3.25 0.003 ^* 60 Pt Pt-O 3.18 1.99 0.003 ^* 0.016 Pt-Pt 0.74 2.80 0.006 Pt-Ce 2.05 2.85 0.006 Pt-Ce 0.98 3.24 0.004 80 Pt Pt-O 3.96 1.95 0.003 0.019 Pt-Pt 0.03 2.80 0.006 Pt-Ce 2.17 2.85 0.003 ^* Pt-Ce 1.04 3.24 0.010 Pt/CA Pt-O 0.59 1.98 0.008 0.007 Pt-Pt 6.54 2.75 0.010 Pt-Ce 0.79 2.85 0.003 ^* Pt-Ce 0.36 3.20 0.007 Pt/rA Pt-O 0.75 2.00 0.004 0.006 Pt-Pt 6.42 2.75 0.009 PtO ₂ Pt-O 6 2.01 0.003 0.010 Pt-Pt 6 3.12 0.003 Pt foil Pt-Pt 12 2.76 0.005 0.004

^a Fixed during EXAFS fitting.

Sample Path Coordination number (R) Interatomic distance (Å) Debye-Waller factor
(σ ² /Å ² ) R-factor 40 Pd Pd-O 2.21 2.00 0.004 0.032 Pd-Pd 1.68 2.79 0.013 Pd-Ce 3.38 2.86 0.003 Pd-Ce 1.24 3.29 0.008 60 Pd Pd-O 2.87 1.99 0.002 0.016 Pd-Pd 1.15 2.78 0.007 Pd-Ce 3.25 2.85 0.009 Pd-Ce 1.19 3.28 0.016 80 Pd Pd-O 3.49 2.00 0.004 0.018 Pd-Pd 0.08 2.75 0.007 Pd-Ce 3.35 2.85 0.005 Pd-Ce 1.27 3.24 0.013 Pd/CA Pd-O 0.54 2.03 0.009 0.005 Pd-Pd 6.84 2.73 0.006 Pd-Ce 0.86 2.90 0.003 ^* Pd-Ce 0.31 3.29 0.011 Pd/rA Pd-O 0.53 2.00 0.010 0.006 Pd-Pd 8.00 2.73 0.006 PdO Pd-O 4 2.03 0.003 0.006 Pd-Pd 4 3.06 0.006 Pd-Pd 8 3.45 0.004 Pd foil Pd-Pd 12 2.75 0.006 0.019

^a Fixed during EXAFS fitting.

Sample Path Coordination number (R) Interatomic distance (Å) Debye-Waller factor
(σ ² /Å ² ) R-factor 40 Rh
(Rh ESC) Rh-O 3.21 1.99 0.003 0.007 Rh-Rh 1.32 2.74 0.003 ^* Rh-Ce 2.08 2.88 0.007 Rh-Ce 0.87 3.27 0.010 60 Rh Rh-O 3.18 2.01 0.005 0.009 Rh-Rh 0.77 2.72 0.005 Rh-Ce 2.18 2.88 0.003 Rh-Ce 0.96 3.28 0.008 80 Rh Rh-O 3.63 2.00 0.004 0.006 Rh-Rh 0.17 2.69 0.003 Rh-Ce 2.25 2.85 0.004 Rh-Ce 1.07 3.24 0.019 90 Rh
(Rh SAC) Rh-O 3.60 1.99 0.004 0.009 Rh-Rh 0.04 2.68 0.002 Rh-Ce 2.30 2.83 0.009 Rh-Ce 1.13 3.23 0.018 Rh/CA Rh-O 2.59 1.98 0.007 0.008 Rh-Rh 5.01 2.70 0.008 Rh-Ce 0.59 2.92 0.003 ^* Rh-Ce 0.26 3.30 0.007 Rh/rA Rh-O 2.60 2.01 0.007 0.009 Rh-Rh 4.87 2.69 0.008 Rh ₂ O ₃ Rh-O 6 2.03 0.002 0.001 Rh-Rh 3 3.03 0.002 Rh-Rh 3 3.52 0.003 Rh foil Rh-Rh 12 2.69 0.004 0.003

^a Fixed during EXAFS fitting.

catalyst S _BET (m ² /g) Fresh γ-Al ₂ O ₃ 66.8 rAl ₂ O ₃ 64.1 CeO ₂ -rAl ₂ O ₃ 46.8 Pt ESC 44.7 Pd ESC 43.6 Rh ESC 45.3 Pt SAC 46.1 Pd SAC 45.2 Rh SAC 44.9

Sample Metal dispersion (%) ^a Path Coordination number (R) Interatomic distance
(Å) Debye-Waller factor
(σ ² /Å ² ) R-factor Pt ESC 100.4 Pt-O 3.21 1.98 0.003 0.014 Pt-Pt 2.63 2.82 0.003 Pt-Ce 1.98 2.86 0.001 Pt-Ce 0.87 3.25 0.003 ^b HT 100.8 Pt-O 3.15 1.98 0.004 0.008 Pt-Pt 2.68 2.82 0.005 Pt-Ce 1.96 2.86 0.006 Pt-Ce 0.84 3.24 0.005 long-term 100.7 Pt-O 3.38 1.97 0.002 0.010 Pt-Pt 2.60 2.81 0.003 Pt-Ce 1.89 2.86 0.010 Pt-Ce 0.82 3.25 0.008 3 ^rd rxn 100.5 Pt-O 3.35 1.99 0.002 0.007 Pt-Pt 2.64 2.80 0.003 Pt-Ce 1.95 2.84 0.009 Pt-Ce 0.84 3.24 0.003 ^b

^a Metal dispersion was measured by pulsed CO chemisorption. The ratio of metal:CO was 1:1.

^b This factor was fixed during the EXAFS fitting.

Sample Metal dispersion (%) ^a Path Coordination number (R) Interatomic distance
(Å) Debye-Waller factor
(σ ² /Å ² ) R-factor Pd ESC 101.4 Pd-O 2.21 2.00 0.004 0.032 Pd-Pd 2.89 2.79 0.013 Pd-Ce 3.38 2.86 0.003 Pd-Ce 1.24 3.29 0.008 HT 102.4 Pd-O 2.30 2.00 0.003 0.022 Pd-Pd 2.92 2.78 0.005 Pd-Ce 3.35 2.87 0.012 Pd-Ce 1.22 3.28 0.010 long-term 101.8 Pd-O 2.25 2.02 0.005 0.008 Pd-Pd 2.94 2.79 0.003 Pd-Ce 3.36 2.88 0.008 Pd-Ce 1.24 3.29 0.010 3 ^rd rxn 101.7 Pd-O 2.20 1.99 0.006 0.011 Pd-Pd 2.94 2.79 0.003 ^b Pd-Ce 3.40 2.87 0.007 Pd-Ce 1.26 3.27 0.009

^a Metal dispersion was measured by pulsed CO chemisorption. The ratio of metal:CO was 1:1.

^b This factor was fixed during the EXAFS fitting.

Sample Metal dispersion (%) ^a Path Coordination number (R) Interatomic distance
(Å) Debye-Waller factor
(σ ² /Å ² ) R-factor Rh ESC 102.0 Rh-O 3.21 1.99 0.003 0.007 Rh-Rh 2.59 2.74 0.003 ^b Rh-Ce 2.08 2.88 0.007 Rh-Ce 0.87 3.27 0.010 HT 100.7 Rh-O 3.20 2.00 0.005 0.010 Rh-Rh 2.62 2.74 0.005 Rh-Ce 2.10 2.86 0.010 Rh-Ce 0.88 3.25 0.008 long-term 101.4 Rh-O 3.25 1.98 0.002 0.005 Rh-Rh 2.57 2.72 0.003 Rh-Ce 2.05 2.89 0.003 ^b Rh-Ce 0.85 3.27 0.008 3 ^rd rxn 100.6 Rh-O 3.28 1.99 0.006 0.012 Rh-Rh 2.62 2.73 0.005 Rh-Ce 2.02 2.88 0.009 Rh-Ce 0.84 3.26 0.010

^a Metal dispersion was measured by pulsed H ₂ chemisorption. The ratio of metal:H was 1:1.

^b This factor was fixed during the EXAFS fitting.

Claims (20)

A method for preparing a highly durable metal ensemble catalyst for a three-way catalyst (TWC) reaction having a completely dispersed and reduced metal state, comprising the steps of:
A penta site forming step of flowing _{H 2} /N ₂ to γ-alumina ^{to form an Al 3+ penta site;}
a first impregnation step of impregnating the ceria-based support precursor into reduced γ-alumina (rAl ₂ O _{3 );}
a second impregnation step of impregnating the noble metal precursor to impregnate the support with the noble metal;
a powder obtaining step of obtaining a powder by stirring until the solution is completely evaporated;
Drying the powder to obtain a dry powder to obtain a dry powder;
calcining the dry powder to obtain calcined powder; and
A catalyst obtaining step of reducing the calcined powder in H ₂ /N _{2 to obtain a catalyst.} The method of claim 1 , wherein _{the concentration of H 2} /N ₂ in the penta site forming step is 3 to 20% (v/v). The method of claim 1, wherein the ceria-based support is a cerium dioxide (CeO ₂ ) support. The method of claim 3, wherein the cerium dioxide support powder is prepared through the following steps, a highly durable metal ensemble catalyst having a fully dispersed and reduced metal state:
Ce(NO ₃ ) ₃ ·6H ₂ O is dissolved in deionized water to prepare a cerium solution to prepare a cerium solution;
impregnating with reduced γ-alumina;
Evaporation step to completely evaporate the solution
a drying step of drying the precipitate;
pulverizing the dried precipitate to obtain a fine powder; and
Firing step in which the fine powder is fired. The method according to claim 1, wherein the content of the ceria-based support precursor in the first impregnation step is 3 to 10 wt%, the highly durable metal ensemble catalyst manufacturing method having a fully dispersed and reduced metal state. The method of claim 1, wherein the noble metal is at least one selected from the group consisting of Pt, Pd and Rh. The method according to claim 1, wherein the noble metal precursor is prepared by the following method, a highly durable metal ensemble catalyst having a fully dispersed and reduced metal state:
A precursor solution preparation step of adding HCl to PtCl ₄ , PdCl ₂ or RhCl _{3 to prepare a H 2} PtCl ₆ , H ₂ PdCl ₄ or H ₂ RhCl _{5 precursor solution;} and
an impregnation step of impregnating the support with a H ₂ PtCl ₆ , H ₂ PdCl ₄ or H ₂ RhCl _{5 precursor solution;}
Evaporation step to completely evaporate the precursor solution
a drying step of drying the precipitate;
pulverizing the dried precipitate to obtain a fine powder;
a calcination step of calcining the fine powder;
A reduction step of reducing the calcined powder. The method of claim 1 , wherein the second impregnation step is performed at 40 to 90° C., wherein the highly durable metal ensemble catalyst having a fully dispersed and reduced metal state. The method according to claim 1, wherein the noble metal precursor in the second impregnation step is 0.5 to 2.0 wt%, having a fully dispersed and reduced metal state. The method of claim 1 , wherein the catalyst obtaining step is performed at 5 to 20% (v/v) H ₂ /N ₂ , a highly durable metal ensemble catalyst having a fully dispersed and reduced metal state. The method of claim 1, wherein the catalyst obtaining step is performed at a ramping rate of 10°C/min. The fully dispersed and reduced metal according to claim 1, wherein the ensemble catalyst comprises a noble metal supported on a ceria-based support, and the noble metal is dispersed at least 99% on the cerium dioxide surface and has a reduced metal state. A method for producing a highly durable metal ensemble catalyst having a state. The highly durable metal ensemble having a fully dispersed and reduced metal state according to claim 1, wherein the content of the noble metal of the ensemble catalyst is present on the support in an amount in the range of 0.5 to 2.0% by weight based on the total catalyst weight. Catalyst preparation method. A highly durable metal ensemble catalyst for a three-way catalyst (TWC) reaction comprising a noble metal supported on a ceria-based support, wherein the noble metal is dispersed at least 99% on the surface of cerium dioxide and has a reduced metal state. The highly durable metal ensemble catalyst according to claim 14, wherein the ceria-based support is a cerium dioxide (CeO _{2 ) support.} 15. The highly durable metal ensemble having a fully dispersed and reduced metal state according to claim 14, wherein the content of the noble metal of the ensemble catalyst is present on the support in an amount in the range of 0.5 to 2.0 wt% based on the total catalyst weight. catalyst. 15. The highly durable metal ensemble catalyst according to claim 14, wherein the noble metal is at least one selected from the group consisting of Pt, Pd and Rh. The highly durable metal ensemble catalyst of claim 14, wherein the metal ensemble catalyst is for removal of at least one selected from the group consisting of hydrocarbons, carbon monoxide and nitrogen oxides. Contains a noble metal supported on a ceria-based support, wherein the noble metal is dispersed at least 99% on the surface of cerium dioxide, and a hydrocarbon, carbon monoxide and nitrogen oxide containing a highly durable metal ensemble catalyst having a reduced metal state. One or more selected removal devices. The apparatus of claim 19 , wherein the apparatus is an internal combustion engine exhaust stream treatment apparatus, a gasoline vehicle three-way catalyst (TWC) apparatus or a diesel vehicle exhaust gas purification catalyst (DOC, LNT, SCR) apparatus.

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