Honeycomb carrier for exhaust gas clarification catalyst and method for production thereof

• US 20060239880A1
• Filed: 07/29/2004
• Published: 10/26/2006
• Est. Priority Date: 07/29/2003
• Status: Active Grant

• Current Assignee: OHCERA Co. Ltd.
• Original Assignee: OHCERA Co. Ltd.
• Inventors: Fukuda, Masahiro, Takahashi, Masahide, Fukuda, Masaaki, Fukuda, Tsutomu, Yoko, Toshinobu
• Granted Patent: US 8,685,363 B2
• Time in Patent Office: Days
• US Class Current: 423/213.200
• CPC Class Codes: B01D 53/94 by catalytic processes
• CPC Class Codes: B01J 23/04 Alkali metals
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: C04B 2111/00793 as filters or diaphragms
• CPC Class Codes: C04B 2111/0081 as catalysts or catalyst carriers
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3236 Alkaline earth titanates
• CPC Class Codes: C04B 2235/3472 Alkali metal alumino-silicates other than clay, e.g. spodumene, alkali feldspars such as albite or orthoclase, micas such as muscovite, zeolites such as natrolite
• CPC Class Codes: C04B 2235/3481 Alkaline earth metal alumino-silicates other than clay, e.g. cordierite, beryl, micas such as margarite, plagioclase feldspars such as anorthite, zeolites such as chabazite
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/9607 Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 35/478 based on aluminium titanates
• CPC Class Codes: C04B 38/0006 Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: C04B 38/0009 characterised by features relating to the cell walls, e.g. wall thickness or distribution of pores in the walls
• CPC Class Codes: C04B 38/0067 characterised by the density of the end product
• CPC Class Codes: C04B 38/0074 expressed as porosity percentage

Abstract

To provide a honeycomb carrier to support a catalyst to clean e.g. an exhaust gas of an automobile particularly containing NOx, which is excellent in heat resistance, thermal shock resistance, mechanical strength and thermal decomposition resistance and has a great corrosion resistance to a catalyst, and is thus capable of being used with stability for a long period of time, and a process for its production.

The material for the honeycomb carrier is an aluminum magnesium titanate sintered product obtained by firing at from 1,000 to 1,700° C. a molded product formed from a raw material mixture comprising 100 parts by mass, as calculated as oxides, of a mixture comprising a Mg— containing compound, an Al-containing compound and a Ti— containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in an aluminum magnesium titanate represented by the empirical formula Mg_xAl_2(1+x)Ti_(1+x)O₅ (wherein 0<x<1), and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦y=1).

Claims

1. A honeycomb carrier for an exhaust gas-cleaning catalyst which is a honeycomb carrier to support a catalyst to clean an exhaust gas, characterized in that the material for the honeycomb carrier is an aluminum magnesium titanate sintered product obtained by firing at from 1,000 to 1,700°

C. a mixture comprising 100 parts by mass, as calculated as oxides, of a mixture comprising a Mg-containing compound, an Al-containing compound and a Ti-containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in an aluminum magnesium titanate represented by the empirical formula MgxAl<sub>2(1−

x)</sub>Ti_(1+x)O₅ (wherein 0<

x<

1), and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1)

4. The honeycomb carrier for an exhaust gas-cleaning catalyst according to any one of claims 1 to 3, which has a wall thickness of from 0.05 to 0.6 mm, a cell density of from 15 to 124 cells/cm², a porosity of the partition wall of from 20 to 50%, and a thermal expansion coefficient of at most 3.0×

10<sup>−

6</sup>K<sup>−

1</sup>.

5. The honeycomb carrier for an exhaust gas-cleaning catalyst according to any one of claims 1 to 4, wherein the catalyst contains an alkali metal or alkaline earth metal component to remove NOx in the exhaust gas.

6. The honeycomb carrier for an exhaust gas-cleaning catalyst according to any one of claims 1 to 5, wherein the exhaust gas is an exhaust gas of an automobile of a system wherein a fuel is directly jetted into an engine or of a system wherein a fuel is diluted and burned.

2. A honeycomb carrier for an exhaust gas-cleaning catalyst which is a honeycomb carrier to support a catalyst to clean an exhaust gas, characterized in that the material for the honeycomb carrier is an aluminum titanate sintered product obtained by firing at from 1,250 to 1,700°

C. a raw material mixture comprising 100 parts by mass of a mixture (hereinafter referred to as component X) comprising TiO₂ and Al₂O₃ in a molar ratio of the former/the latter being 40 to 60/60 to 40, and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1), an oxide of a spinel structure containing Mg, or MgO or a Mg-containing compound which can be converted to MgO by firing (hereinafter referred to as component Y).

3. The honeycomb carrier for an exhaust gas-cleaning catalyst according to claim 2, wherein the component Y is a mixture comprising an alkali feldspar represented by (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1), and an oxide of a spinel structure containing Mg and/or MgO or a Mg-containing compound which can be converted to MgO by firing.

7. A process for producing a honeycomb carrier for an exhaust gas-cleaning catalyst, characterized by preparing a raw material mixture comprising 100 parts by mass, as calculated as oxides, of a mixture comprising a Mg—

containing compound, an Al-containing compound and a Ti—

containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in an aluminum magnesium titanate represented by the empirical formula Mg_xAl<sub>2(1−

x)</sub>Ti_(1+x)O₅ (wherein 0≦

x<

1), and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1), adding a molding assistant to the raw material mixture, followed by kneading to plasticize the raw material mixture to make it extrusion-processable, and then extrusion processing it into a honeycomb body, followed by firing at from 1,000 to 1,700°

C.

9. The process for producing a honeycomb carrier for an exhaust gas-cleaning catalyst according to claim 7 or 8, wherein the average particle size of each component contained in the raw material mixture is at most 10 μ

m.

8. A process for producing a honeycomb carrier for an exhaust gas-cleaning catalyst, characterized by preparing a mixture comprising 100 parts by mass of a mixture (hereinafter referred to as component X) comprising TiO₂ and Al₂O₃ in a molar ratio of the former/the latter being 40 to 60/60 to 40, and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1), an oxide of a spinel structure containing Mg, or MgO or a Mg-containing compound which can be converted to MgO by firing (hereinafter referred to as component Y), adding a molding assistant to the mixture, followed by kneading to plasticize the mixture to make it extrusion-processable, and extrusion processing it into a honeycomb body, followed by firing at from 1,250 to 1,700°

C.

10. A method for cleaning an exhaust gas, which comprises contacting the exhaust gas to a honeycomb carrier supporting a catalyst to clean an exhaust gas, characterized in that the material for the honeycomb carrier is an aluminum magnesium titanate sintered product obtained by firing at from 1,000 to 1,700°

C. a mixture comprising 100 parts by mass, as calculated as oxides, of a mixture comprising a Mg-containing compound, an Al-containing compound and a Ti-containing compound in the same metal component ratio as the metal component ratio of Mg, Al and Ti in an aluminum magnesium titanate represented by the empirical formula Mg_xAl<sub>2(1−

x)</sub>Ti_(1+x)O₅ (wherein 0<

x<

1), and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1)

11. A method for cleaning an exhaust gas, which comprises contacting the exhaust gas to a honeycomb carrier supporting a catalyst to clean an exhaust gas, characterized in that the material for the honeycomb carrier is an aluminum titanate sintered product obtained by firing at from 1,250 to 1,700°

C. a raw material mixture comprising 100 parts by mass of a mixture (hereinafter referred to as component X) comprising TiO₂ and Al₂O₃ in a molar ratio of the former/the latter being 40 to 60/60 to 40, and from 1 to 10 parts by mass of an alkali feldspar represented by the empirical formula (Na_yK_1-y)AlSi₃O₈ (wherein 0≦

y≦

1), an oxide of a spinel structure containing Mg, or MgO or a Mg-containing compound which can be converted to MgO by firing (hereinafter referred to as component Y)