Diesel Particulate Control

• US 20110239626A1
• Filed: 06/01/2011
• Published: 10/06/2011
• Est. Priority Date: 05/18/2006
• Status: Active Grant

• Current Assignee: Clean Diesel Technologies, Inc.
• Original Assignee: Clean Diesel Technologies, Inc.
• Inventors: Copan, Walter G., Makkee, Michiel, Kamasamudram, Krishna
• Granted Patent: US 8,715,601 B2
• Time in Patent Office: Days
• US Class Current: 60/274
• CPC Class Codes: B01D 2255/1021 Platinum
• CPC Class Codes: B01D 2255/206 Rare earth metals
• CPC Class Codes: B01D 53/90 Injecting reactants
• CPC Class Codes: B01D 53/944 Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts three-way-catalysts [TWC] B01D53/9445
• CPC Class Codes: C10L 1/14 Organic compounds
• CPC Class Codes: C10L 1/1814 Chelates
• CPC Class Codes: C10L 1/1881 carboxylic group attached to an aliphatic carbon atom
• CPC Class Codes: C10L 1/1886 naphthenic acid
• CPC Class Codes: C10L 1/189 having at least one carboxyl group bound to an aromatic carbon atom C10L1/1802, C10L1/1805, C10L1/1808, C10L1/1811, C10L1/1814, C10L1/1817, C10L1/1885, C10L1/1886, C10L1/1888 take precedence
• CPC Class Codes: C10L 1/305 organo-metallic compounds (containing a metal to carbon bond)
• CPC Class Codes: C10L 10/02 for reducing smoke development
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2430/04 by adding non-fuel substances to combustion air or fuel, e.g. additives
• CPC Class Codes: F01N 2610/01 the substance being catalytic material in liquid form
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/03 the substance being hydrocarbons, e.g. engine fuel
• CPC Class Codes: F01N 3/0231 using special exhaust apparatus upstream of the filter for producing nitrogen dioxide, e.g. for continuous filter regeneration systems [CRT]
• CPC Class Codes: F01N 3/0253 adding fuel to exhaust gases
• CPC Class Codes: F01N 3/029 by adding non-fuel substances to exhaust
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• 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 3/2066 : Selective catalytic reduction [SCR]
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies

Abstract

A method and apparatus are provided for reducing emissions of particulates from diesel engines. Exhaust is passed through a diesel particular filter having at least two stages comprised of (a) a catalyst section having a platinum group metal catalyst on contact surfaces within the catalyst section and (b) a filter section comprised of passages effective to remove particulates from a moving stream of combustion gases generated by combusting the fuel in the engine and holding them therein to permit their oxidation. Carbon removal is enhanced by utilizing levels of platinum group metal composition, cerium compositions, fuels and/or optional chemical enhancers to generate NO₂ in the catalyst section in amounts sufficient to form cerium nitrates in the filter section. The cerium oxide is associated with and maintains dispersion of the platinum in the filter section, and the cerium nitrates are available at the surface and within the soot particles to provide enhanced soot oxidation at a lower balance point.

Claims

1. A method for reducing emissions of particulates from diesel engines, which comprises:

operating a diesel engine with a fuel containing a fuel borne catalyst comprising a fuel soluble or dispersible cerium composition and a fuel soluble or dispersible platinum group metal composition;

passing exhaust produced by combustion of the fuel and containing both cerium oxide and platinum group metal released from the fuel by combustion, through a diesel particular filter having at least two stages comprised of

(a) a catalyst section having a platinum group metal catalyst and/or base metal catalyst on contact surfaces within the catalyst section and

(b) a filter section comprised of passages effective to remove particulates from a moving stream of combustion gases generated by combusting the fuel in the engine and holding them therein to permit their oxidation,

wherein the improvement comprises utilizing levels of platinum group metal composition, cerium compositions, fuels and/or optional chemical enhancers to generate NO₂ in the catalyst section in amounts sufficient to form cerium nitrates in the filter section whereby the cerium oxide is associated with and maintains dispersion of the platinum in the filter section, and the cerium nitrates will be available at the surface and within the soot particles to provide enhanced soot oxidation at a lower balance point than could be achieved without the provision of the platinum group metal and cerium fuel additive in the multi stage filter.

2. A process according to claim 1 wherein the chemical enhancers are soluble or dispersible alkali metal and/or alkaline earth compositions in the fuel in amounts effective to enhance the most active species of surface nitrates.

3. A process according to claim 1 wherein the chemical enhancers are solid phase alkali metal and/or alkaline earth metal compositions in the device catalyst section (a), and/or the filter section (b).

4. A process according to claim 3 wherein the chemical enhancer is employed in an amount of from about 0.1 to about 1.0 of the weight of the cerium.

5. A process according to claim 1 wherein a third stage filter is employed effective to remove fine and ultra fine particulates.

6. A process according to claim 1 wherein a selective catalytic reduction (SCR) unit, is provided downstream of the diesel particulate filter.

7. A process according to claim 6 wherein a catalyst is provided downstream of the diesel particulate filter to oxidize NO to NO₂ to aid in the effectiveness of the SCR unit in reducing residual NO_x.

8. A process according to claim 1 wherein the catalyst section of (a) comprises a substrate selected from the group consisting of alumina, a silica-alumina composition such as cordierite, silicon carbide, glass or metal fibers, porous glass, ceramic and metal substrates.

9. A process according to claim 1 wherein the filter section of (b) comprises device selected from the group consisting of wall flow monolith devices of type device known to be useful for particulate traps and wire mesh filters.

10. A process according to claim 1 where the catalyst section is integral with the filter section.

11. A process according to claim 1 wherein fuel is injected into the engine exhaust upstream of the catalyst (a) to raise the temperature within the catalyst and filter sections of the device.

12. A process according to claim 1 wherein a fuel containing fuel borne catalyst is injected into the engine exhaust upstream of the catalyst and filter sections of the device.

13. A process according to claim 2 wherein a fuel containing fuel borne catalyst and enhancer is injected into the engine exhaust upstream of the catalyst and filter sections of the device.

14. A process according to claim 11 wherein the injection of fuel, whether or not containing fuel borne catalyst or enhancer, is controlled based upon temperature or backpressure sensor signals upstream of the catalyst filter device, within the device, and/or downstream of the device.

15. A process according to claim 1 wherein an enhancer for cerium nitrate formation is employed as part of the catalyst section as manufactured.

16. (canceled)

17. (canceled)

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20. (canceled)