# US 8,771,625 B2 · Method for reducing nitric oxide in the exhaust gas flow of internal combustion engines

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- Number: US 8,771,625 B2
- Document ID: US8771625B2
- Status: Granted
- Kind: B2
- Application number: 12/738,385
- Filed: 2009-09-03
- Published: 2011-02-10
- Granted: 2014-07-08
- Earliest claimed: 2008-09-09
- Assignees: Man Truck & Bus AG
- Applicants: Doering Andreas; Dieter Rothe
- Inventors: Doering Andreas; Dieter Rothe
- Web page: https://patentgrep.com/patent/US8771625B2

## CPC

- F01N 3/2073: {Means for generating a reducing substance from the exhaust gases}
- C10L 1/10: containing additives
- C10L 1/22: containing nitrogen
- C10L 10/02: for reducing smoke development
- C10L 1/1266: {nitrogen containing compounds, (e.g. NH3)}
- C10L 1/1883: {polycarboxylic acid}
- C10L 1/2222: {(cyclo)aliphatic amines; polyamines (no macromolecular substituent 30C); quaternair ammonium compounds; carbamates (C10L1/221 takes precedence)}
- C10L 1/223: having at least one amino group bound to an aromatic carbon atom {(C10L1/221, C10L1/2227 take precedence)}
- C10L 1/224: Amides; Imides {carboxylic acid amides, imides (C10L1/221, C10L1/2227 take precedence)}
- C10L 1/226: containing at least one nitrogen-to-nitrogen bond, e.g. azo compounds, azides, hydrazines {(C10L1/221 takes precedence)}
- C10L 1/2283: {containing one or more carbon to nitrogen double bonds, e.g. guanidine, hydrazone, semi-carbazone, azomethine (C10L1/221, C10L1/226 take precedence)}
- C10L 1/2286: {containing one or more carbon to nitrogen triple bonds, e.g. nitriles (C10L1/221, C10L1/226 take precedence)}
- C10L 1/232: containing nitrogen in a heterocyclic ring {(C10L1/221 takes precedence)}
- F01N 2430/04: by adding non-fuel substances to combustion air or fuel, e.g. additives
- Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- Y02C 20/10: of nitrous oxide (N2O)
- 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)
- C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A method is described for reducing nitrogen oxides in the exhaust gas flow of combustion engines, especially a motor vehicle internal combustion engine, wherein an air/fuel mixture in the combustion chamber of the combustion engine is combusted in the presence of a fuel additive and, in the process, the fuel additive decomposes and the exhaust gas flow is guided through at least one catalyst arranged downstream of the combustion chamber. This method is characterized in that a fuel additive is used, which decomposes in the combustion chamber releasing ammonia and the exhaust gas flow containing ammonia is guided through at least one SCR catalyst arranged downstream of the combustion chamber to reduce the concentration of the nitrogen oxides contained therein. The method according to the invention is highly effective in reducing the nitrogen oxide content in the exhaust gas flow of a combustion engine without an exhaust gas aftertreatment system having to be expensively formed and the installation space having to be increased.

## Claims

### Claim 1

A method for reducing nitrogen oxides in an exhaust gas flow of a combustion engine, comprising:
combusting an air/fuel mixture in a combustion chamber of the combustion engine in the presence of an effective quantity of a fuel additive and wherein, in the process, the fuel additive decomposes in the combustion chamber releasing ammonia; and
guiding the exhaust gas flow through at least one SCR catalyst arranged downstream of the combustion chamber such that the concentration of the nitrogen oxides contained therein is reduced,
wherein the fuel additive contains one or more of tetraammoniummethylenediaminetetraacetate, triammoniumnitriloacetate, tetraammoniumcyclohexanediamine-(1,2)-acetate, pentaammoniumdiethylenetriaminepentaacetate, tetraammoniumethylene glycol-bis(aminoethylether)-N,N′-tetraacetate, N-(2-hydroxyethyl)-ethylenediamine-N,N,N′-triaceticacid-triammonium salt, and/or hexaammoniumtriethylenetetraaminehexaacetate.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the fuel additive further comprises at least one additional organic nitrogen-containing compound.

### Claim 3 (depends on 2)

A method according to claim 2, wherein the additional organic nitrogen-containing compound comprises at least one of a) a nitrogen-containing, heterocyclic compound which has one or more rings and no sulphur or phosphorus content, and b) an ammonia precursor with amino and/or ammonium groups.

### Claim 4 (depends on 3)

A method according to claim 3, wherein compound a) comprises one or more of guanidine, azirine, aziridine, diaziridine, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyrazine, pyrazidine, triazine, purine, azepine, chinoline, isochinoline, indole, benzimidazole, phenazine, porphine, pteridine and isoindole.

### Claim 5 (depends on 3)

A method according to claim 3, wherein compound b) comprises an ammonium organyl of the form NR4+X−.

### Claim 6 (depends on 5)

A method according to claim 5, wherein said R+ comprises at least one of hydrogen and at least one C1-C30 alkyl.

### Claim 7 (depends on 5, 6)

A method according to claim 5 or claim 6, wherein said X comprises at least one of formiate and acetate and alkylate and oxalate and carbonate.

### Claim 8 (depends on 7)

A method according to claim 7, wherein the ammonium organyl compounds are selected from the group butyl-NH4, methyl-NH4, phenyl-NH4, ethylNH4, t-butyl-NH4, phenyl-CH2—NH4, NH4—C5H5 butyl-NR4, methyl-NR4, phenylNR4, ethyl-NR4, t-butyl-NR4, phenyl-CH2—NR4 and NR4—C5H5 (wherein R═C1-C30 alkyl-).

### Claim 9 (depends on 1, 2, 3, 4, 5, 6)

A method according to any of claims 1-6, wherein the at least one SCR catalyst comprises at least one of vanadium, vanadium pentoxide, titanium dioxide, tungsten oxide, copper-containing zeolites, iron-containing zeolites and cobalt-containing zeolites.

### Claim 10 (depends on 9)

A method according to claim 9, wherein the active component of the catalyst comprises at least one of platinum, palladium, and iridium, in the form of their oxides, and/or zeolites.

### Claim 11 (depends on 1, 2, 3, 4, 5, 6)

A method according to any of claims 1-6, wherein if the quantity of the ammonia formed exceeds the quantity of the NO formed during combustion, providing a catalyst for the oxidation of ammonia arranged downstream of the SCR catalyst to reduce undesired ammonia emissions.

### Claim 12 (depends on 1, 2, 3, 4, 5, 6)

A method according to any of claims 1-6, wherein the fuel additive comprises a solution containing at least one of dimethylacetamide, dimethylformamide and dimethylpyridine.

### Claim 13 (depends on 1, 2, 3, 4, 5, 6)

A method according to any of claims 1-6, wherein the effective quantity of the fuel additive is added directly to the fuel and/or fed to the fuel by a tank from the fuel itself.

### Claim 14 (depends on 1, 2, 3, 4, 5, 6)

A method according to any of claims 1-6, wherein the exhaust gas flow leaving the combustion chamber and/or SCR catalyst has a laughing gas (dinitrogen oxide) concentration of less than 30 ppm.

### Claim 15 (depends on 5, 6)

A method according to claim 5 or claim 6, wherein the ammonium organyl compounds are selected from the group butyl-NH4, methyl-NH4, phenyl-NH4, ethylNH4, t-butyl-NH4, phenyl-CH2—NH4, NH4—C5H5 butyl-NR4, methyl-NR4, phenylNR4, ethyl-NR4, t-butyl-NR4, phenyl-CH2—NR4 and NR4—C5H5 (wherein R═C1-C30 alkyl-).