Catalyst for clarifying exhaust gas and method for preparation thereof, and exhaust gas clarification catalyst device for vehicle

• US 20060287196A1
• Filed: 08/20/2004
• Published: 12/21/2006
• Est. Priority Date: 09/12/2003
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Matsuo, Yuichi, Suzuki, Norihiko, Kiguchi, Kazunori
• Granted Patent: US 7,674,746 B2
• Time in Patent Office: Days
• US Class Current: 502/302
• CPC Class Codes: B01D 2255/1023 Palladium
• CPC Class Codes: B01D 2255/206 Rare earth metals
• CPC Class Codes: B01D 2255/2092 Aluminium
• CPC Class Codes: B01D 2255/40 Mixed oxides
• CPC Class Codes: B01D 53/945 characterised by a specific catalyst
• CPC Class Codes: B01J 21/04 Alumina
• CPC Class Codes: B01J 23/002 Mixed oxides other than spinels, e.g. perovskite
• CPC Class Codes: B01J 23/005 Spinels
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 2523/00 Constitutive chemical elements of heterogeneous catalysts
• CPC Class Codes: B01J 2523/31 Aluminium
• CPC Class Codes: B01J 2523/3706 Lanthanum
• CPC Class Codes: B01J 2523/3725 Neodymium
• CPC Class Codes: B01J 2523/375 Gadolinium
• CPC Class Codes: B01J 2523/3756 Terbium
• CPC Class Codes: B01J 2523/824 Palladium
• CPC Class Codes: B01J 37/0018 Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• CPC Class Codes: B01J 37/0236 Drying, e.g. preparing a suspension, adding a soluble salt and drying
• CPC Class Codes: C01F 17/34 Aluminates, e.g. YAlO3 or Y3-xGdxAl5O12
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: Y02A 50/20 : Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies

Abstract

A purification catalyst for exhaust gas enhances the activities of the precious metals, preventing drop of activities at high temperature, and exhibiting a sufficient performance even during low temperature (below 400° C.) operation when starting a vehicle or during idling. The Pd oxide is supported on the Al oxide, and the Al oxide is LnAlO₃ (Ln: rare-earth element).

Claims

1. A purification catalyst for exhaust gas, comprising an aluminum oxide supporting a Pd oxide, wherein the aluminum oxide is LnAlO₃ in which Ln is a rare-earth element, and wherein crystal system of the aluminum oxide is trigonal or rhombohedral.

3. The purification catalyst for exhaust gas of claim 1, wherein the Pd oxide contains at least Ln₂PdO₄ in which Ln is a rare-earth element.

4. The purification catalyst for exhaust gas according to claims 1 or 3, wherein the catalyst is produced by adding at least one kind of compound selected from the group of compounds of carboxylic acid having a hydroxyl group or a mercapto group and having a carbon number of 2 to 20, dicarboxylic acid having a carbon number of 2 or 3, and monocarboxylic acid having a carbon number of 1 to 20 to aqueous nitrate solution including a component.

5. The purification catalyst for exhaust gas according to claim 4, wherein the catalyst is produced by evaporating the aqueous nitrate solution completely, to produce a carboxylic acid complex polymer and by heating the carboxylic acid complex polymer.

2. (canceled)

6. A production method for a purification catalyst for exhaust gas, the method comprising:

preparing at least one kind of compound selected from a group of compounds of carboxylic acid having a hydroxyl group or a mercapto group and having a carbon number of 2 to 20, dicarboxylic acid having a carbon number of 2 or 3, and monocarboxylic acid having a carbon number of 1 to 20; and

adding at least one compound selected from the group to an aqueous nitrate solution including a component.

7. The production method for a purification catalyst for exhaust gas according to claim 6, the method comprising:

evaporating aqueous carboxylic acid completely to produce a carboxylic acid complex polymer; and

heating the carboxylic acid complex polymer.

8. The production method for a purification catalyst for exhaust gas according to claim 7, wherein a heating temperature in the heating of the carboxylic acid complex polymer is not more than 1000°

C.

9. A purification catalyst apparatus for automobile exhaust gas having Pd oxide supported on Al oxide for purifying exhaust gas emitted from an automobile, wherein the Al oxide is LnAlO₃ in which Ln is a rare-earth element, and wherein crystal system of the aluminum oxide is trigonal is rhombohedral.