Method for reducing emissions of NO.sub.x and particulates from a diesel engine

• US 6,051,040 A
• Filed: 11/26/1997
• Issued: 04/18/2000
• Est. Priority Date: 12/28/1988
• Status: Expired due to Term

• Current Assignee: Clean Diesel Technologies, Inc.
• Original Assignee: Clean Diesel Technologies, Inc.
• Inventors: Peter-Hoblyn, Jeremy D.
• Primary Examiner(s): MEDLEY, MARGARET B
• Application Number:
  US08/978,687
• Time in Patent Office: 874 Days
• Field of Search: 44/358, 44/359, 44/361, 44/363, 123/1 A, 423/235, 431/4
• US Class Current: 44/358
• CPC Class Codes: B01D 2251/206 Ammonium compounds
• CPC Class Codes: B01D 2255/1021 Platinum
• CPC Class Codes: B01D 2255/202 Alkali metals
• CPC Class Codes: B01D 2255/2065 Cerium
• CPC Class Codes: B01D 2255/2073 Manganese
• CPC Class Codes: B01D 2255/20738 Iron
• CPC Class Codes: B01D 2255/20761 Copper
• CPC Class Codes: B01D 2258/012 Diesel engines and lean burn gasoline engines
• CPC Class Codes: B01D 53/9418 for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
• 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: B01D 53/9477 with catalysts positioned on separate bricks, e.g. exhaust systems
• CPC Class Codes: C10L 1/10 containing additives
• CPC Class Codes: C10L 1/1233 oxygen containing compounds, e.g. oxides, hydroxides, acids and salts thereof
• CPC Class Codes: C10L 1/1241 metal carbonyls
• CPC Class Codes: C10L 1/125 water
• CPC Class Codes: C10L 1/1266 nitrogen containing compounds, (e.g. NH3)
• CPC Class Codes: C10L 1/14 Organic compounds
• CPC Class Codes: C10L 1/1608 Well defined compounds, e.g. hexane, benzene
• CPC Class Codes: C10L 1/1616 fractions, e.g. lubricants, solvents, naphta, bitumen, tars, terpentine
• CPC Class Codes: C10L 1/1814 Chelates
• CPC Class Codes: C10L 1/1824 : mono-hydroxy
• CPC Class Codes: C10L 1/1828 : Salts thereof
• CPC Class Codes: C10L 1/1852 : Ethers; Acetals; Ketals; Orthoesters
• CPC Class Codes: C10L 1/1855 : Cyclic ethers, e.g. epoxides, lactides, lactones
• CPC Class Codes: C10L 1/1857 : Aldehydes; Ketones
• CPC Class Codes: C10L 1/188 : Carboxylic acids; metal salts thereof C10L1/1802, C10L1/1805, C10L1/1808, C10L1/1811, C10L1/1814, C10L1/1817 take precedence
• 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 1/1888 : tall oil
• 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 1/2227 : urea; derivatives thereof; urethane C10L1/221 takes precedence
• CPC Class Codes: C10L 1/224 : Amides; Imides carboxylic acid amides, imides C10L1/221, C10L1/2227 take precedence
• CPC Class Codes: C10L 1/2286 : containing one or more carbon to nitrogen triple bonds, e.g. nitriles C10L1/221, C10L1/226 take precedence
• CPC Class Codes: C10L 1/231 : nitro compounds; nitrates; nitrites C10L1/221 takes precedence
• CPC Class Codes: C10L 1/2437 : Sulfonic acids; Derivatives thereof, e.g. sulfonamides, sulfosuccinic acid esters
• CPC Class Codes: C10L 1/30 : compounds not mentioned before (complexes)
• CPC Class Codes: C10L 1/301 : derived from metals
• 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: C10L 10/06 : for facilitating soot removal
• CPC Class Codes: F01N 2240/20 : a flow director or deflector
• 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 3/023 : using means for regenerating the filters, e.g. by burning trapped particles by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• 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: F02B 3/06 : with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02B 51/02 : involving catalysts
• CPC Class Codes: F02D 19/12 : peculiar to engines working with non-fuel substances or with anti-knock agents, e.g. with anti-knock fuel
• CPC Class Codes: F02D 41/0047 : Controlling exhaust gas recirculation [EGR] temperature control with cooler in recirculation circuit F02M26/33
• CPC Class Codes: F05C 2201/0427 : Platinum group, e.g. Pt, Ir
• 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 method improves the operation of a diesel engine through the use of a fuel additive, a diesel particulate trap and a NO_x -reducing catalyst. The operation of the NO_x -reducing catalyst is enhanced by the introduction of urea or like compound upstream of the catalyst at temperatures effective for non-catalytic NO_x reduction and the generation of ammonia. The additive comprises fuel-soluble compositions of platinum group metal in effective amounts to lower the emissions of unburned hydrocarbons and carbon monoxide from the trap. The catalytic activity provided to the exhaust system by the fuel additive is selective and preferably reduces the oxidation of SO₂ to SO₃. The platinum group metal compositions are preferably added in amounts effective to provide concentrations of the metal in the fuel of less than 1 part per million (ppm). Lithium and/or sodium compositions can be used in amounts effective to reduce the trap regeneration temperature, e.g. concentrations to provide about 1 to 100 ppm lithium metal, and/or 1 to 30 ppm sodium metal.

Claims

1. A method for operating a diesel engine with reduced emissions of particulates and NO_x, comprising:

(a) adding to a diesel fuel, a fuel-soluble composition of platinum group metal in effective amounts such that the gases produced by combustion selectively catalyze the exhaust system, including a particulate trap, effectively to lower the emissions of unburned hydrocarbons and carbon monoxide, said platinum group metal composition comprising a fuel soluble organic compound which

I) is resistant to breakdown under ambient temperatures;

ii) is substantially free of phosphorus, arsenic, antimony, or halogens;

iii) has a partition ratio sufficient to maintain preferential solubility in the fuel;

iv) has a breakdown temperature of at least about 122°

F. and

v) a partition ratio of at least about 25;

(b) combusting the diesel fuel in a diesel engine resulting in the production of diesel combustion gases containing NO_x and particulates;

(c) injecting into the combustion gases within the cylinder of the diesel engine near the end of the power stroke where the temperature is within the range of from 1600° and

2000°

F. an aqueous solution of a NO_x -reducing composition which produces ammonia by the decomposition of the NO_x -reducing composition selected from the group consisting of urea, cyanuric acid, dicyanimide, calcium cyanamide, and mixtures of these, the temperature being effective to reduce the level of NO_x in the combustion gases and produce ammonia by the decomposition of the NO_x -reducing composition;

(d) passing the combustion gases containing ammonia through a particulate trap comprised of a gas permeable material to reduce the level of particulates; and

(e) passing the combustion gases through a NO_x -reduction catalyst to reduce NO_x and ammonia produced by decomposition of the NO_x -reducing composition.

2. A method according to claim 1 wherein the fuel further includes at least one catalytic material selected from the group consisting of sodium, lithium, potassium, cerium, iron, copper, and manganese, in an amount of from 5 to 100 pm effective to catalyze the exhaust system by combusting the fuel.

3. A method according to claim 1 wherein the fuel further includes lithium and/or sodium composition in an amount to provide a concentration of from about 1 to 100 ppm metal in the case of lithium, and at 1 to 30 ppm metal in the case of sodium.

4. A method according to claim 1 wherein the fuel additive is employed at a level which is effective to reduce the oxidation of SO₂ to SO₃ while maintaining a high level of conversion of carbon monoxide and hydrocarbons.

5. A method according to claim 1 wherein the platinum group metal composition is added in an amount effective to provide a concentration of the metal in the fuel of less than 1 part per million (ppm).

6. A method of claim 1, wherein said diesel engine is modified by retarding engine timing or recirculating exhaust gas effectively to reduce NO_x emissions.

7. A method according to claim 1 wherein the engine is operated for a sufficient period of time to deposit sufficient catalyst in the exhaust system to reduce the regeneration temperature of the trap.

8. A method of claim 1, wherein a catalytic metal composition comprising a metal selected from the group consisting of platinum group metals, iron, copper, cerium, manganese, and mixtures of any of these, is introduced with the aqueous solution of NO_x -reducing composition.

9. A method according to claim 1 which further includes retarding ignition timing sufficiently to cause a reduction in NO_x.

10. A method according to claim 1 wherein the NO_x -reducing composition is maintained in a cartridge in solid form and is mixed with water in metered amounts to form an aqueous solution of NO_x -reducing composition for admixing with the combustion gases.

11. A method for operating a diesel engine with reduced emissions of particulates and NO_x, comprising:

(a) adding to a diesel fuel, a fuel-soluble composition of platinum group metal and at least one catalytic material selected from the group consisting of sodium, lithium, potassium, cerium, iron, copper, and manganese in effective amounts such that the gases produced by combustion selectively catalyze the exhaust system, including a particulate trap, effectively to lower the emissions of unburned hydrocarbons and carbon monoxide;

(b) combusting the diesel fuel in a diesel engine resulting in the production of diesel combustion gases containing NO_x and particulates;

(c) admixing the combustion gases with an aqueous solution of NO_x -reducing composition at a temperature effective to reduce the level of NO_x in the combustion gases and produce ammonia by the decomposition of the NO_x -reducing composition selected from the group consisting of urea, ammonium carbamate, ammonium bicarbonate, ammonium carbonate and mixtures;

(d) passing the composition gases through a particulate trap to reduce the level of particulates; and

(e) passing the combustion gases through a NO_x -reducing catalyst to reduce NO_x and ammonia produced by decomposition of the NO_x -reducing composition.

12. A method according to claim 11 wherein the NO_x -reducing composition is added to the combustion gases in the cylinder of the diesel engine near the end of the power stroke where the temperature of the combustion gases is within the range of from about 1600°

to 2000°

F.

13. A method according to claim 11 wherein the NO_x -reducing composition is added to the combustion gases in the exhaust system prior to the particulate trap where the temperature of the combustion gases is within the range of from about 1600°

to 2000°

F.

14. A method for operating a diesel engine with reduced emissions of particulates and NO_x, comprising:

(a) adding to a diesel fuel, a fuel-soluble composition of platinum group metal in effective amounts such that the gases produced by combustion selectively catalyze the exhaust system, including a particulate trap, effectively to lower the emissions of unburned hydrocarbons and carbon monoxide, said platinum group metal composition comprising a fuel soluble organic compound which

I) is resistant to breakdown under ambient temperatures;

ii) is substantially free of phosphorus, arsenic, antimony, or halogens;

iii) has a partition ratio sufficient to maintain preferential solubility in the fuel;

iv) has a breakdown temperature of at least about 122°

F.; and

v) a partition ratio of at least about 25;

(b) combusting the diesel fuel in a diesel engine resulting in the production of diesel combustion gases containing NO_x and particulates;

(c) passing the gases to an exhaust system at a temperature of from about 752°

to about 2000°

F.;

(d) injecting into the combustion gases an aqueous solution of a NO_x -reducing composition which produces ammonia by the decomposition of the NO_x -reducing composition selected from the group consisting of urea, cyanuric acid, calcium cyanamide and mixtures of these, whereby ammonia is produced by the decomposition of the NO_x -reducing composition;

(e) passing the combustion gases containing ammonia through a particulate trap comprised of a gas permeable material to reduce the level of particulates; and

(f) passing the combustion gases through a NO_x -reduction catalyst to reduce NO_x and ammonia produced by decomposition of the NO_x -reducing composition.

15. A method according to claim 14 wherein the fuel further includes at least one catalytic material selected from the group consisting of sodium, lithium, potassium, cerium, iron, copper, and manganese, in an amount of from 5 to 100 ppm effective to catalyze the exhaust system by combusting the fuel.

16. A method according to claim 14 wherein the engine is operated for a sufficient period of time to deposit sufficient catalyst in the exhaust system to reduce the regeneration temperature of the trap.

17. A method of claim 14, wherein a catalytic metal composition comprising a metal selected from the group consisting of platinum group metals, iron, copper, cerium, manganese, and mixtures of any of these, is introduced with the aqueous solution of NO_x -reducing composition.

18. A method according to claim 14 wherein the NO_x -reducing composition is maintained in a cartridge in solid form and is mixed with water in metered amounts to form an aqueous solution of NO_x -reducing composition for admixing with the combustion gases.