Apparatus and method for regenerating catalyst for purifying exhaust gas

• US 8,601,794 B2
• Filed: 05/09/2008
• Issued: 12/10/2013
• Est. Priority Date: 05/09/2007
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Yamato, Masanori, Yoshida, Takeru, Takagi, Nobuyuki, Tanabe, Toshitaka, Nagai, Yasutaka, Dohmae, Kazuhiko, Takahashi, Naoki
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): LEE, BRANDON DONGPA
• Application Number:
  US12/599,079
• Publication Number:
  US 20100293921A1
• Time in Patent Office: 2,041 Days
• Field of Search: 602/75, 602/86, 602/89, 603/00, 602/74
• US Class Current: 60/286
• CPC Class Codes: B01D 2255/1021 Platinum
• CPC Class Codes: B01D 2255/206 Rare earth metals
• CPC Class Codes: B01D 53/9445 Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
• CPC Class Codes: B01J 23/42 Platinum
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 23/96 of catalysts comprising metals, oxides or hydroxides of the noble metals
• CPC Class Codes: B01J 38/10 using elemental hydrogen
• CPC Class Codes: B01J 38/12 Treating with free oxygen-containing gas
• CPC Class Codes: F01N 2240/16 an electric heater, i.e. a resistance heater
• CPC Class Codes: F01N 2240/28 a plasma reactor
• CPC Class Codes: F01N 2610/04 the substance being hydrogen
• CPC Class Codes: F01N 3/2013 using electric or magnetic heating means
• CPC Class Codes: F01N 3/206 Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents F01N3/2066 takes precedence
• CPC Class Codes: F01N 3/22 Control of additional air supply only, e.g. using by-passes or variable air pump drives
• 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 regeneration apparatus comprises a heater 2 which heats a catalyst 1 at the time of stopping fuel supply to an engine, a pump 4 which supplies an oxidizing gas or a reducing gas to the heated catalyst 1 and a switching valve 3. In the oxidizing step, catalytic poisons, for example hydrocarbon, which are absorbed on a noble metal are oxidized and removed. The particles of the noble metal become oxidized particles as pure oxide and the like. After the oxidizing step, the reducing step is carried out. In the reducing step, particles of the noble metal are reduced and re-dispersed on the support simultaneously and as a result, the particles of the noble metal become fine. Thus, a deteriorated catalyst can be regenerated without interrupting the use of catalyst and also without deteriorating the drivability.

Claims

1. An apparatus for regenerating a catalyst for purifying exhaust gas, comprising:

a heater which heats said catalyst for purifying exhaust gas including a noble metal at the time of stopping fuel supply to a vehicle engine;

an oxidizing gas supplying portion which supplies an oxidizing gas to said catalyst for purifying exhaust gas heated by said heater, wherein the oxidizing gas supplying portion includes an oxidizing gas introducing pipe and at least one of pump and injector;

a reducing gas supplying portion which supplies a reducing gas to said catalyst for purifying exhaust gas heated by said heater, wherein the reducing gas supplying portion includes a reducing gas introducing pipe and at least one of pump and injector;

a switching valve which switches over from driving of said oxidizing gas supplying member to driving of said reducing gas supplying member, and from driving of said reducing gas supplying member to driving of said oxidizing gas supplying member; and

a controller including programming configured to detect stop of fuel supply, to control the heater to heat said catalyst at the time of stopping fuel supply to control the switching valve to switch over from driving of said reducing gas supplying portion to driving of said oxidizing gas supplying portion, and from driving of said oxidizing gas supplying portion to driving of said reducing gas supplying portion at the time of stopping fuel supply to a vehicle engine, and to regenerate said catalyst at the time of stopping fuel supply to the vehicle engine.

3. The apparatus for regenerating a catalyst for purifying exhaust gas set forth in claim 1, wherein said catalyst for purifying exhaust gas comprises:

a support which includes at least ceria; and

a platinum loaded onto said support.

2. An apparatus for regenerating a catalyst for purifying exhaust gas, comprising:

an oxidizing gas supplying portion which supplies an oxidizing gas to said catalyst for purifying exhaust gas, wherein the oxidizing gas supplying portion includes an oxidizing gas introducing pipe and at least one of pump and injector;

a reducing gas supplying portion which supplies a reducing gas to said catalyst for purifying exhaust gas, wherein the reducing gas supplying portion includes a reducing gas introducing pipe and at least one of pump and injector;

a plasma generator which generates discharge plasma in said oxidizing gas or said reducing gas existing between said oxidizing gas supplying member and said reducing gas supplying member, and said catalyst for purifying exhaust gas; and

a controller including programming configured to detect stop of fuel supply, to control the oxidizing gas supplying portion to supply an oxidizing gas turned into plasma to said catalyst and then to control the reducing gas supplying portion to supply a reducing gas turned into plasma to said catalyst at the time of stopping fuel supply to a vehicle engine, and to regenerate said catalyst at the time of stopping fuel supply to the vehicle engine.

11. The apparatus for regenerating a catalyst for purifying exhaust gas set forth in claim 2, wherein said catalyst for purifying exhaust gas comprises:

a support which includes at least ceria; and

a platinum loaded onto said support.

4. A method for regenerating a catalyst for purifying exhaust gas at the time of stopping fuel supply to a vehicle engine, comprising the successive steps of:

detecting stop of fuel supply to the vehicle engine;

heating said catalyst for purifying exhaust gas including a noble metal;

oxidizing said noble metal by supplying an oxidizing gas to said heated catalyst for purifying exhaust gas; and

reducing said noble metal under oxidized condition by supplying a reducing gas to said heated catalyst for purifying exhaust gas,

wherein the successive steps are controlled by a controller including programming configured to detect stop of fuel supply, to control heating of said catalyst at the time of stopping fuel supply, to detect the temperature of said catalyst, to control switching between supplying the oxidizing gas and supplying the reducing gas, and to regenerate said catalyst at the time of stopping fuel supply to the vehicle engine.

5. The method for regenerating a catalyst for purifying exhaust gas set forth in claim 4, wherein said supplying an oxidizing gas or said supplying a reducing gas includes using a reverse-driving power when said engine is reverse-driven by rotation of a vehicle wheel at the time of stopping fuel supply.

6. The method for regenerating a catalyst for purifying exhaust gas set forth in claim 4, wherein said oxidizing step is carried out under the condition that said catalyst for purifying exhaust gas is heated within 400°

C.˜

800°

C.

7. The method for regenerating a catalyst for purifying exhaust gas set forth in claim 4, wherein said reducing step is carried out under the condition that said catalyst for purifying exhaust gas is heated to 100°

C. or above.

8. The method for regenerating a catalyst for purifying exhaust gas set forth in claim 4, wherein said oxidizing gas includes 2% or more oxygen gas.

10. The method for regenerating a catalyst for purifying exhaust gas set forth in claim 4, wherein said catalyst for purifying exhaust gas comprises:

a support which includes at least ceria; and

a platinum loaded onto said support.

9. A method for regenerating a catalyst for purifying exhaust gas at the time of stopping fuel supply to a vehicle engine, comprising the successive steps of:

detecting stop of fuel supply to the vehicle engine;

oxidizing a noble metal by supplying an oxidizing gas activated by a discharge plasma to a catalyst for purifying exhaust gas including said noble metal; and

reducing said noble metal under oxidized condition by supplying a reducing gas activated by a discharge plasma to said catalyst for purifying exhaust gas,

wherein the successive steps are controlled by a controller including programming configured to detect stop of fuel supply, to control supplying the oxidizing gas turned into plasma to said catalyst and then supplying the reducing gas turned into plasma to said catalyst, and to regenerate said catalyst at the time of stopping fuel supply to the vehicle engine.

12. The method for regenerating a catalyst for purifying exhaust gas set forth in claim 9, wherein said catalyst for purifying exhaust gas comprises:

a support which includes at least ceria; and

a platinum loaded onto said support.