METHOD AND DEVICE FOR SELECTIVE CATALYTIC NOX REDUCTION

• US 20010053342A1
• Filed: 05/06/1999
• Published: 12/20/2001
• Est. Priority Date: 07/03/1997
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: HARNDORF, HORST, WAHL, THOMAS, BAREIS, MARC, ALKEMADE, ULRICH, BRENNER, FRANK, MARKO, ARMIN
• Granted Patent: US 6,387,336 B2
• Time in Patent Office: Days
• US Class Current: 423/235
• CPC Class Codes: B01D 2251/2062 Ammonia
• CPC Class Codes: B01D 53/8625 Nitrogen oxides
• CPC Class Codes: B01D 53/9409 Nitrogen oxides
• CPC Class Codes: C01C 1/006 making use of solid ammonia storage materials, e.g. complex ammine salts
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/06 the substance being in the gaseous form
• CPC Class Codes: F01N 2610/10 the substance being heated, e.g. by heating tank or supply line of the added substance
• CPC Class Codes: F01N 2610/1406 Storage means for substances, e.g. tanks or reservoirs
• CPC Class Codes: F01N 2610/1446 Means for damping of pressure fluctuations in the delivery system, e.g. by puffer volumes or throttling
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• 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: Y02P 20/129 Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A method and a device for selective catalytic NOx reduction in oxygen-containing exhaust gases using ammonia and a reduction catalyst (9) are described, according to which gaseous ammonia is made available by heating a solid storage medium (2) in a container (1). The method and the device are suitable for use in motor vehicles in particular.

Claims

1. Method of selective catalytic NOx reduction in oxygen-containing exhaust gases using ammonia and a reduction catalyst (9), characterized in that the gaseous ammonia is made available by heating a solid storage medium (2) introduced into a container (1).

2. Method according to

claim 1

, characterized in that the storage medium (2) binds ammonia by absorption.

3. Method according to

claim 1

, characterized in that the storage medium (2) binds ammonia in the form of a chemical complex.

4. Method according to

claim 3

, characterized in that the storage medium (2) contains one or more salts, in particular chlorides and/or sulfates of one or more alkaline earth metals and/or of one or more 3d subgroup elements, preferably manganese, iron, cobalt, nickel, copper and/or zinc.

5. Method according to

claim 4

, characterized in that the storage medium contains strontium chloride and/or calcium chloride.

6. Method according to one of the foregoing claims, characterized in that the storage medium (2) is heated by an electric heating system and/or the waste heat of the engine coolant and/or of the exhaust gas.

7. Method according to

claim 6

, characterized in that the storage medium (2) is heated to 50 to 200°

C., preferably to 80 to 150°

C.

8. Method according to

claim 6

, characterized in that the storage medium (2) is heated to an ammonia vapor pressure of 0.1 to 30 bar, preferably 2 to 10 bar.

9. Device for carrying out the method according to one of the foregoing claims having a reduction catalyst (9) and a supply line for ammonia (6) in the exhaust gas line (8) between the engine (7) and the reduction catalyst (9), characterized in that the supply line (6) is connected, via a valve (4), to a container (1) that is filled with a solid storage medium (2) and is heatable using a heating device (3).

10. Device according to

claim 9

, characterized in that a buffer container for the gaseous ammonia (10) and a valve (4b) for metering ammonia from the container (10) into the exhaust gas line (8) is provided in the supply line (6).