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DE-102023112129-B4 - METHOD FOR PRODUCEING AN EXHAUST PURIFICATION MATERIAL AND METHOD FOR PRODUCEING AN EXHAUST PURIFICATION DEVICE

DE102023112129B4DE 102023112129 B4DE102023112129 B4DE 102023112129B4DE-102023112129-B4

Abstract

A method for producing an exhaust gas purification material, wherein the method comprises the steps in this order: (a) Impregnating a metal oxide support with a solution of a rhodium compound; (b) Drying the metal oxide support impregnated with a solution of a rhodium compound to obtain a rhodium-containing catalyst comprising the metal oxide support and rhodium particles supported on the metal oxide support; (c) Heating the rhodium-containing catalyst at a temperature within a range of 700 °C to 900 °C under an inert atmosphere; and (d) Mixing the rhodium-containing catalyst with a material that has a higher basicity than the basicity of the metal oxide support.

Inventors

  • Takahiro NISHIO
  • Shogo Shirakawa
  • Nobuyuki Takagi
  • Tomomasa Aikawa
  • Hiroki NIHASHI
  • Takahiro Noguchi

Assignees

  • CATALER CORPORATION
  • TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date
20260513
Application Date
20230509
Priority Date
20220523

Claims (9)

  1. A process for producing an exhaust gas purification material, comprising the following steps in this order: (a) impregnating a metal oxide support with a solution of a rhodium compound; (b) drying the metal oxide support impregnated with the solution of a rhodium compound to obtain a rhodium-containing catalyst comprising the metal oxide support and rhodium particles supported on the metal oxide support; (c) heating the rhodium-containing catalyst at a temperature within a range of 700 °C to 900 °C under an inert atmosphere; and (d) mixing the rhodium-containing catalyst with a material having a higher basicity than that of the metal oxide support.
  2. Procedure according to Claim 1 , wherein in the rhodium-containing catalyst after step (c) there is a mean value of a particle size distribution of the rhodium particles from 1.5 nm to 18 nm, and a standard deviation of the particle size distribution of the rhodium particles is less than 1.6 nm.
  3. Procedure according to Claim 2 , wherein in the rhodium-containing catalyst after step (c) the mean value of the particle size distribution of the rhodium particles is from 4 nm to 14 nm.
  4. Procedure according to Claim 2 , wherein in the rhodium-containing catalyst after step (c) the mean value of the particle size distribution of the rhodium particles is from 2 nm to 8 nm.
  5. Procedure according to one of the Claims 1 until 4 , wherein the rhodium-containing catalyst contains the rhodium particles in an amount of 0.01 wt.% to 2 wt.%, based on a total weight of the metal oxide support and the rhodium particles.
  6. Procedure according to one of the Claims 1 until 5 , wherein the metal oxide support is an oxide containing zirconium dioxide as a main component, a composite oxide containing zirconium dioxide and aluminum oxide as main components, or a composite oxide containing zirconium dioxide, aluminum oxide, and cerium oxide as main components.
  7. Procedure according to one of the Claims 1 until 6 , wherein the metal oxide support is a composite oxide containing zirconium dioxide, aluminum oxide, and cerium oxide as main components, and the material has a higher basicity than the basicity of the metal oxide support, is a composite oxide containing cerium oxide and zirconium dioxide as main components.
  8. Procedure according to one of the Claims 1 until 7 , where the inert atmosphere is a nitrogen atmosphere.
  9. A method for manufacturing an exhaust gas purification device, wherein the method comprises: obtaining the exhaust gas purification material by the method according to one of the Claims 1 until 8 ; and arranging the exhaust gas purification material on a substrate.

Description

BACKGROUND Technical field The present invention relates to a method for producing an exhaust gas purification material and a method for producing an exhaust gas purification device. State of the art Exhaust gas emitted by an internal combustion engine used in a vehicle, such as a car, contains harmful components like carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). Regulations regarding emission levels of these harmful components have been tightened year after year. To remove these harmful components, precious metals such as platinum (Pt), palladium (Pd), and rhodium (Rh) have been used as catalysts. Meanwhile, with regard to resource risk and resource conservation, a reduction in precious metals was demanded. One method for reducing the use of precious metals in an exhaust gas purification device is known in which a precious metal is carried in the form of fine particles on a support. For example, disclosed JP 2016 - 147 256 A a process for producing an exhaust gas purification material, comprising a step of supporting precious metal particles on an oxide support to produce a precious metal-supported catalyst, and a step of carrying out a heat process on the precious metal-supported catalyst under a reducing atmosphere to control the sizes of the precious metal particles within a predetermined range. Furthermore, they reveal DE 602 16 573 T2 and DE 602 16 572 T2 State-of-the-art exhaust gas purification catalysts. SUMMARY Through intensive studies, the inventors discovered that the use of an exhaust gas purification material, which is produced by the in JP 2016 - 147 256 A The disclosed manufacturing process is obtained, in some cases leading to a reduction in catalytic activity in a high-temperature environment. The present invention provides a method for producing an exhaust gas purification material and a method for producing an exhaust gas purification device, which enable efficient removal of a harmful component, even after exposure to a high-temperature environment. The present invention offers, for example, the following aspects. [1] A method for producing an exhaust gas purification material, the method comprising the steps in this order: (a) Impregnating a metal oxide support with a solution of a rhodium compound; (b) Drying the metal oxide support impregnated with a solution of a rhodium compound to obtain a rhodium-containing catalyst comprising the metal oxide support and rhodium particles supported on the metal oxide support; (c) Heating the rhodium-containing catalyst at a temperature within a range of 700 °C to 900 °C under an inert atmosphere; and (d) Mixing the rhodium-containing catalyst with a material that has a higher basicity than the basicity of the metal oxide support. [2] The process according to aspect [1], wherein in the rhodium-containing catalyst after step (c) there is a mean of a particle size distribution of the rhodium particles of 1.5 nm to 18 nm, and a standard deviation of the particle size distribution of the rhodium particles is less than 1.6 nm. [3] The process according to aspect [2], wherein in the rhodium-containing catalyst after step (c) the mean value of the particle size distribution of the rhodium particles is from 4 nm to 14 nm. [4] The process according to aspect [2], wherein in the rhodium-containing catalyst after step (c) the mean value of the particle size distribution of the rhodium particles is from 2 nm to 8 nm. [5] The process according to one of the aspects [1] to [4], wherein the rhodium-containing catalyst contains the rhodium particles in an amount of 0.01 wt.% to 2 wt.%, based on a total weight of the metal oxide support and the rhodium particles. [6] The method according to one of the aspects [1] to [5], wherein the metal oxide support is an oxide containing zirconium dioxide as a main component, a composite oxide containing zirconium dioxide and aluminium oxide as main components, or a composite oxide containing zirconium dioxide, aluminium oxide, and cerium oxide as main components. [7] The method according to one of the aspects [1] to [6], wherein the metal oxide support is a composite oxide containing zirconium dioxide, aluminium oxide and cerium oxide as main components, and the material has a higher basicity than the basicity of the metal oxide support, is a composite oxide containing cerium oxide and zirconium dioxide as main components. [8] The method according to one of the aspects [1] to [7], wherein the inert atmosphere is a nitrogen atmosphere. [9] A method for manufacturing an exhaust gas purification device, the method comprising: Obtaining the exhaust gas purification material by the process according to one of the aspects [1] to [8]; and Arranging the exhaust gas purification material on a substrate. The exhaust gas purification material and the exhaust gas purification device produced according to the methods of the present invention enable efficient removal of a harmful component, even after exposure to a h