# US 7,610,752 B2 · Devices and methods for reduction of NOx emissions from lean burn engines

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- Number: US 7,610,752 B2
- Document ID: US7610752B2
- Status: Granted
- Kind: B2
- Application number: 11/715,854
- Filed: 2007-03-08
- Published: 2007-07-05
- Granted: 2009-11-03
- Earliest claimed: 2002-11-15
- Assignees: Eaton Corporation
- Inventors: Ralph Albert Dalla Betta; Joel M. Cizeron; David R. Sheridan
- Web page: https://patentgrep.com/patent/US7610752B2

## CPC

- F01N 3/0871: {using means for controlling, e.g. purging, the absorbents or adsorbents}
- F01N 3/0814: {combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts}
- F01N 3/0842: {Nitrogen oxides}
- F01N 3/2053: {By-passing catalytic reactors, e.g. to prevent overheating}
- F01N 3/2066: {Selective catalytic reduction [SCR]}
- F01N 13/009: {having two or more separate purifying devices arranged in series}
- F01N 13/0093: {the purifying devices are of the same type}
- F01N 2240/20: a flow director or deflector
- F01N 2240/30: a fuel reformer
- F01N 2610/03: the substance being hydrocarbons, e.g. engine fuel
- F01N 2610/04: the substance being hydrogen
- Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- Y02T 10/12: Improving ICE efficiencies
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The invention provides devices and methods for generating H2 and CO in an O2 containing gas stream. The invention also provides devices and methods for removal of NOX from an O2 containing gas stream, particularly the oxygen-rich exhaust stream from a lean-burning engine, such as a diesel engine. The invention includes a fuel processor that efficiently converts added hydrocarbon fuel to a reducing mixture of H2 and CO. The added fuel may be a portion of the onboard fuel on a vehicle. The H2 and CO are incorporated into the exhaust stream and reacted over a selective lean NOX catalyst to convert NOX to N2. thereby providing an efficient means of NOX emission control.

## Claims

### Claim 1

A method of forming reformate from diesel engine fuel in a diesel engine exhaust stream, comprising:
channeling a lean exhaust flow from the engine through a fuel processor, the fuel processor comprising a main chamber and a fuel reforming catalyst within the main chamber;
dividing the lean exhaust flow within the main chamber between a first flow path through the catalyst, or a portion thereof, and a second flow within the main chamber that bypasses the first flow path, with the split ratio of the division between the two flow paths being unregulated or regulated only by fixed means;
injecting the diesel fuel into the first flow path to form an overall rich composition within the first flow path while maintaining a lean composition in the bypass flow;
reforming a portion of the injected fuel to form H2 and CO within the first flow path; and
causing the the divided exhaust flow to recombine.

### Claim 2 (depends on 1)

The method of claim 1, wherein the recombined stream is channeled through a lean NOx catalyst that reduces NOx contained in the recombined exhaust stream under lean conditions using the H2 and CO.

### Claim 3 (depends on 1)

The method of claim 1, wherein the second flow path bypasses the catalyst.

### Claim 4 (depends on 1)

The method of claim 1, wherein the split ratio is unregulated.

### Claim 5 (depends on 1)

The method of claim 1, wherein the fuel processor produces H2 and CO at least in part through steam reforming reactions;
wherein steam reforming comprises endothermic reaction with H2O at temperatures of at least about 550° C.

### Claim 6 (depends on 5)

The method of claim 5, wherein at least a portion of the injected fuel is oxidized within the first flow path to provide energy that heats at least a portion of the catalyst to reach or maintain steam reforming temperatures of at least about 550° C.

### Claim 7 (depends on 1)

The method of claim 1, wherein from about 5 to about 25% of the exhaust is continuously diverted through the first flow path.

### Claim 8 (depends on 1)

The method of claim 1, wherein the fuel injection is set based on the exhaust oxygen concentration to produce a target reductant amount in the first flow path.

### Claim 9 (depends on 8)

The method of claim 8, wherein the target reductant amount is independent of the exhaust oxygen concentration.

### Claim 10

A power generation system comprising:
an engine operative to produce an exhaust stream;
an exhaust system comprising a fuel processor configured to receive the exhaust stream, the fuel processor comprising a main chamber and a fuel reforming catalyst within the main chamber, the fuel processor having a fixed structure for dividing the exhaust stream between a first flow path through the catalyst, or a portion thereof, and a second flow within the main chamber that bypasses the first flow path, with the spilt ratio of the division between the two flow paths being unregulated or regulated only by the fixed structure, the exhaust system being structured to recombine the divided exhaust stream downstream from the catalyst; and
a fuel injector configured to inject fuel into the first flow path without simultaneously injecting fuel into the bypass flow path, whereby the fuel injector is functional to produce rich conditions in the first flow path while conditions remain lean in the bypass flow.

### Claim 11 (depends on 10)

The power generation system of claim 10, further comprising a lean NOx catalyst within the exhaust system downstream from where the exhaust stream recombines.

### Claim 12 (depends on 10)

The power generation system of claim 10, wherein the second flow bypasses the catalyst.

### Claim 13 (depends on 10)

The power generation system of claim 10, wherein the fuel processor is adapted to produce H2 and CO at least in part through steam reforming reactions;
wherein the adaptations comprise a control system for heating the catalyst to temperatures of at least about 600° C. and the catalyst being effective for reforming partially combusted diesel fuel with H2O to produce H2 and CO at 600° C.

### Claim 14 (depends on 10)

The power generation system of claim 10, wherein the first flow path comprises an oxidation catalyst configured to combust injected fuel to provide energy to heat the catalyst to reach or maintain steam reforming temperatures of at least about 550° C.

### Claim 15 (depends on 10)

The power generation system of claim 10, wherein the exhaust system is configured to fixedly direct from about 3 to about 30% of the exhaust through the first flow path.

### Claim 16 (depends on 10)

The power generation system of claim 10, further comprising a controller that controls the fuel injection into the first flow path based on an amount of oxygen in the exhaust entering the first flow path, wherein the controller does not control the exhaust flow rate through the first flow path.

### Claim 17 (depends on 10)

The power generation system of claim 10, wherein:
the catalyst comprises distinct oxidation and reforming catalyst washcoats;
the reforming catalyst washcoat comprises an effective amount of catalyst for reforming partially combusted diesel fuel with H2O to produce H2 and CO at 600° C.

### Claim 18 (depends on 17)

The power generation system of claim 17, wherein the oxidation and reforming catalyst are distinct washcoats on a single monolith catalyst support structure.

### Claim 19 (depends on 17)

The power generation system of claim 17, wherein the oxidation catalyst washcoat comprises an effective amount of Pd for oxidizing diesel fuel at 250° C. and the reforming catalyst washcoat comprises an effective amount of Rh for reforming diesel fuel with H2O at 600° C.