US20050241296A1 - Exhaust after-treatment system for a lean burn internal combustion engine - Google Patents

Exhaust after-treatment system for a lean burn internal combustion engine Download PDF

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Publication number
US20050241296A1
US20050241296A1 US10/837,951 US83795104A US2005241296A1 US 20050241296 A1 US20050241296 A1 US 20050241296A1 US 83795104 A US83795104 A US 83795104A US 2005241296 A1 US2005241296 A1 US 2005241296A1
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Prior art keywords
section
exhaust gas
oxidation
treatment system
storing
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Abandoned
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US10/837,951
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English (en)
Inventor
Robert McCabe
Lifeng Xu
John Hoard
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Ford Global Technologies LLC
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Ford Global Technologies LLC
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Priority to US10/837,951 priority Critical patent/US20050241296A1/en
Assigned to FORD GLOBAL TECHNOLOGIES, LLC reassignment FORD GLOBAL TECHNOLOGIES, LLC ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FORD MOTOR COMPANY
Assigned to FORD MOTOR COMPANY reassignment FORD MOTOR COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HOARD, JOHN W., MCCABE, ROBERT W., XU, LIFENG
Priority to DE102005017821A priority patent/DE102005017821A1/de
Publication of US20050241296A1 publication Critical patent/US20050241296A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • F01N13/0097—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series the purifying devices are arranged in a single housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/04—Adding substances to exhaust gases the substance being hydrogen

Definitions

  • This invention relates to exhaust after-treatment systems and more particularly to exhaust after-treatment systems for lean burn internal combustion engines.
  • precious metal three-way catalysts are generally used as a means for removing pollutants from the exhaust gas of an internal combustion engine. These three-way catalysts remove CO, HC, and NO x simultaneously from engine exhaust gases under stoichiometric conditions. However, under lean fuel conditions, which are desired for optimal fuel efficiency, the three-way catalyst is ineffective for the removal of NO x . Accordingly, to achieve NO x control under fuel lean conditions, exhaust after-treatment systems have included a lean NO x trap (LNT).
  • LNT lean NO x trap
  • An LNT has 3 essential components:
  • a high surface support phase such as alumina over which all the components are dispersed to create finally divided, small particles of all the active components.
  • Various stabilizers and so-called oxygen storage materials are often added as well.
  • An additional function of the Pt in the LNT is to combust reductants such as CO, H 2 , and HC to release heat needed to raise the operating temperature of the LNT to the high temperature levels required for removal of stored sulfur.
  • the LNT includes material to oxidize the CO and HC and material to store NO x .
  • the performance of NO x trap technology is limited in several respects. NO x trap performance is affected by the relatively narrow operating temperature window of current trap formulations. At temperatures outside this window, the system may not operate efficiently and NO x emissions can increase.
  • LNT lean NO x traps
  • the amount of CO and HC in the exhaust gas is typically higher than during normal engine operation. While a large portion of the total emissions generated by the engine is generated within the first few minutes after start up, the catalysts are relatively ineffective because they will not have reached the “light-off” temperature. In other words, the catalysts are the least effective during the time they are needed the most.
  • LNT lean NO x trap
  • the LNT is purged periodically to release and convert the oxides of nitrogen (NO x ) stored in the trap during the preceding lean operation.
  • NO x oxides of nitrogen
  • the engine has to be operated at an air-to-fuel ratio that is rich of stoichiometry.
  • substantial amounts of feedgas carbon monoxide (CO) and hydrocarbons (HC) are generated to convert the stored NO x .
  • the purge mode is activated on the basis of estimated trap loading. That is, when the estimated mass of NO x stored in the trap exceeds a predetermined threshold, a transition to the purge mode is initiated.
  • the rich operation continues for several seconds until the trap is emptied of the stored NO x , whereupon the purge mode is terminated and the normal lean operation is resumed.
  • the end of the purge is usually initiated by a transition in the reading of the HEGO sensor located downstream of the trap, or based on the model prediction of the LNT states. Since the engine is operated rich of stoichiometry during the purge operation, the fuel economy advantage of the lean operation is lost.
  • the LNT may also be subjected to a much higher temperature regeneration process for the removal of stored sulfur (typically temperatures in excess of 600 degrees Celsius).
  • the LNT may also be subjected to temperatures in excess of 500 degrees Celsius during regeneration of the DPF (i.e. removal of accumulated carbonaceous (i.e. soot) material via combustion with oxygen in the exhaust gas). Both of these processes can result in permanent, gradual deterioration in NO x trap performance—more so even than normal trap regeneration to remove stored NO x .
  • a LNT has both functions of oxidation of HC and CO, etc. and storage/reduction of NO x .
  • an oxidation material namely platinum, Pt
  • additional components such as rhodium (Rh), used for NO x reduction, and barium (Ba) used to store the NO x .
  • Rh rhodium
  • Ba barium
  • the inventors speculate that it is one or more of the major components of the LNT (i.e., such as rhodium (Rh) and barium (Ba)) that interacts with the Pt in a deleterious way following the high temperature operation of the LNT required for de-sulfurization and/or DPF regeneration (if such DPF is serially connected in the system).
  • Rh and Pt can form alloys, and it may turn out that the high temperature conditions required for LNT desulfurization and/or DPF regeneration causes the Pt and Rh to alloy in the LNT in such a way that the oxidation activity of the Pt is adversely affected.
  • an exhaust gas after-treatment system having a NO x storage material in a NO x storage section and an HC and CO oxidation catalyst in a separate HC and CO oxidation section, such oxidation section being substantially free of the NO x storage material.
  • the oxidation section is substantially free of Rh.
  • the HC and CO oxidation catalyst is physically separated from the NO x storage material.
  • the oxidation catalyst used in the oxidation section will not become adversely affected by any alloying or other types of interactions with components contained in the NO x storing section.
  • the oxidation catalyst is Pt for generating heat required to “light off”.
  • Pt is an effective NO x oxidation catalyst
  • the negative effects described above of using the Pt completely in conjunction with the NO x storage material such as Ba and reducing components such as Rh are avoided by separating part of the Pt out into a separate oxidation (combustion) catalyst preceding the NO x storage section.
  • an exhaust gas after-treatment system includes in one section thereof, a NO x oxidation component, a NO x storage component, and a NO x reduction component, and, in a separate section thereof, a catalytic HC and CO combustion section substantially free of the NO x storage component and the NO x reduction component.
  • a method for treating exhaust gas produced by an internal combustion engine.
  • the method includes oxidizing hydrocarbons and carbon monoxide present in the exhaust gas and storing NO x in the exhaust gas; wherein the oxidizing and NO x storing are performed as separate, sequential processes on the exhaust gas.
  • FIG. 1 is a diagram of an after-treatment system coupled to the exhaust of an internal combustion engine, such after-treatment system having a Lean NO x Trap (LNT) according to the prior art;
  • LNT Lean NO x Trap
  • FIG. 2 is a diagram of an after-treatment system coupled to the exhaust of an internal combustion engine, such after-treatment system providing NO x storage and HC and CO oxidation according to the invention;
  • FIG. 3 is a diagram of an after-treatment system coupled to the exhaust of an internal combustion engine, such after-treatment system providing NO x storage and HC and CO oxidation according to another embodiment of the invention
  • FIG. 4 are curves showing NO x conversion percentage as function of LNT temperature with and without deterioration by a de-SO x treatment of the trap at 600 degrees Celsius for 16 hours;
  • FIG. 5 are curves showing the effect of an HC and CO oxidation section separate from a NO x storage section according to the invention with the prior art, each of three curves therein showing the functional relationship between NO x conversion percent as a function of temperature, one of the curves being associated with an exhaust gas after-treatment system having an HC and CO oxidation section separate from a NO x storage section according to the invention, another one of the curves being associated with a LNT according to the prior art, and the third one of the curves being associated with an LNT which has not been deteriorated;
  • FIGS. 6 and 7 are curves showing the inlet and the catalyst middle temperatures for the two tests showed in FIG. 5 at 200 degrees Celsius, which are the deteriorated LNT (1′′ long) and the same LNT (1′′ long) plus a 1 ⁇ 8′′ thick diesel oxygen catalyst (DOC) mounted in front of the it.
  • DOC diesel oxygen catalyst
  • the exhaust gas after-treatment system 10 has two separate sections 14 , 16 .
  • the first section 14 is used to combust reductants such as CO, H 2 , and HC and is substantially free of the NO x storage component and the NO x reduction component.
  • the first section 14 contains platinum, for example, as the active combustion component.
  • the second section 16 provides NO x storage and includes: a NO x oxidation component, here for example, platinum, Pt; a NO x storage component, here for example, barium, Ba, and a NO x reduction component, here for example, rhodium, Rh.
  • the first section 14 is upstream of the second section 16 .
  • the second section 16 is in a separate housing from the first section 14 .
  • the first and second sections 14 , 16 are then physically attached by any convenient means, such as welding the two sections together.
  • the exhaust gas after-treatment system 10 is comprised of cylindrical flow-through devices.
  • Such devices are nominally monolithic honeycomb type structure catalysts containing the active components dispersed on either ceramic or metallic type substrates of various cell densities, wall thicknesses, length, shape (e.g., round, oval, or racetrack).
  • sections 14 and 16 can either be separated from one another as shown in the diagram or butted against one another. In FIG.
  • the first and second sections 14 , 16 are contained on the same substrate body via a process known as zone-coating wherein two different catalyst washcoat formulations are coated on different regions of the substrate body.
  • the first section 14 is used to combust reductants such as CO, H 2 , and HC and is substantially free of the NO x storage component and the NO x reduction component and the second section 16 provides NO x storage and includes: a NO x oxidation component; a NO x storage component; and a NO x reduction component.
  • the exhaust gases from the engine 12 pass sequentially, i.e., serially, through the first section 14 and the second section 16 .
  • a method for treating exhaust gases from an internal combustion engine. The method includes oxidizing hydrocarbons and carbon monoxide in the exhaust gas and storing NO x in the exhaust gas; wherein the oxidizing and storing are performed as separate, sequential processes on the exhaust gas after-treatment device.
  • Both the oxidation section and the NO x storing section contain Pt, in various proportions, with the Pt providing a CO and HC oxidation catalyst in the oxidation section and primarily as a NO x oxidation catalyst in the NO x storing section second section.
  • the ratio of the volume of the oxidation section to the NO x storing section ranges from 1/10 to 1 and more preferably from 1/10 to 1 ⁇ 3.
  • the NO x reduction efficiency is improved over the system of FIG. 1 at low temperature. More particularly, the inventors have observed that frequent de-sulfurization of the diesel lean NO x trap (LNT) at 600 to 700 degrees Celsius can cause the deterioration of the LNT especially its light off function, and largely reduces its low temperature NO x reduction efficiency as shown in FIG. 4 , which contains two NO x conversion vs. catalyst inlet temperature curves tested over core (1′′ diameter with 1′′ length) samples at 30,000 s.v./hr (Note that s.v.
  • LNT diesel lean NO x trap
  • space velocity a term commonly used to characterize the amount of gas flow through the catalyst body in relation to the volume of the catalyst body; e.g. cubic feet of gas flow per hour divided by the cubic feet of volume of the catalyst body based on external dimensions.
  • the space velocity therefore carries the units of inverse time, e.g., 1/hr.
  • space velocity it is also a convenient measure for matching laboratory-scale experiments as reported here to larger scale applications such as would be practiced on a vehicle.
  • the 1′′ diameter by 1′′length laboratory samples used in the laboratory at relatively low gas flow rates may translate into a 6′′ diameter by 6′′ length catalyst unit on a vehicle at much higher flow rates.
  • the exact dimensions could be adjusted to yield the same s.v.
  • the s.v. can vary between about 5000/hr to 50,000/hr under conditions experienced in automotive diesel exhaust).
  • the diesel oxidation catalyst formulation is much more stable in the de-sulfurization temperature range (600 to 700 degrees Celsius) than the LNT.
  • the zone coating of an oxidation formulation helps to maintain the “light-off” property of the aged LNT.
  • the rich condition in the diesel LNT vehicle operation is unique from gasoline (TWC, or LNT) or diesel SCR with about 1% oxygen in rich condition (gasoline exhaust contains much lower levels of oxygen for an equivalent degree of richness). Consequently, much more reaction heat, or exothermic temperature rise, can be generated in the diesel case.
  • a LNT catalyst temperature can be raised an additional 30 to 80 degrees Celsius utilizing the embodiments of FIGS. 2 and 3 , which can make quite a big impact on the low temperature NO x reduction efficiency.
  • FIG. 5 are curves showing the effect of an HC and CO oxidation section separate from a NO x storage section according to the invention compared with the prior art, each of three curves therein showing the functional relationship between NO x conversion percent as a function of temperature, curve 20 is associated with an exhaust gas after-treatment system having an HC and CO oxidation section separate from a NO x storage section according to the invention, curve 22 is associated with a LNT according to the prior art, and curve 24 is associated with an LNT according to the prior art which has not been deteriorated;
  • a one eighth inch long diesel oxidation catalyst, first section 14 (1′′ diameter) is attached in front of a one inch long aged second section 16 (i.e., the same piece as shown in FIG. 4 deteriorated by the de-sulfurization)
  • Addition of the small section of diesel oxidation catalyst improved the NO x reduction from 10% to 70% with the same inlet temperature of 200 degrees Celsius.
  • This specific diesel oxidation catalyst was aged in a much more severe condition (670 degrees Celsius for 64 hrs) than the LNT catalyst and also, it has the same Pt loading per unit volume as the LNT.
  • FIGS. 6 and 7 show the inlet (curve 30 ) and the catalyst middle temperatures (curve 32 ) for the two tests shown in FIG.
  • the zone coating of a DOC formulation at the inlet of a catalyst will function similarly as attaching a same volume of DOC catalyst in front of the catalyst.
  • the hydrocarbon and carbon monoxide oxidation material might includes Pt and/or other oxidation catalyst material.
  • the NO x storing material might include Ba, or Cs, Na, K, Sr, and/or any other similar material for storing and releasing NO x in operating temperature range of diesel exhaust gases.
  • both the oxidation section and the NO x storing section contain Pt, in various proportions, such that the Pt is utilized primarily as a CO and HC oxidation catalyst in the oxidation section and primarily as a NO x oxidation catalyst in the NO x storing section.
  • the oxidation section might include one or more CO and HC oxidation components with the oxidation section being substantially free of the NO x storage component(s) and the NO x reduction component(s).

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
US10/837,951 2004-05-03 2004-05-03 Exhaust after-treatment system for a lean burn internal combustion engine Abandoned US20050241296A1 (en)

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US10/837,951 US20050241296A1 (en) 2004-05-03 2004-05-03 Exhaust after-treatment system for a lean burn internal combustion engine
DE102005017821A DE102005017821A1 (de) 2004-05-03 2005-04-18 Abgasnachbehandlungsanlage für eine mager betriebene Brennkraftmaschine

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060037307A1 (en) * 2004-08-20 2006-02-23 Southwest Research Institute Method for rich pulse control of diesel engines
US20100242448A1 (en) * 2009-03-26 2010-09-30 Gm Global Technology Operations, Inc. Exhaust gas treatment system including a four-way catalyst and urea scr catalyst and method of using the same
US20100293929A1 (en) * 2009-05-21 2010-11-25 Southwest Research Institute EXHAUST AFTERTREATMENT SYSTEMS FOR GASOLINE AND ALTERNATIVE-FUELED ENGINES, WITH REDUCTION OF HC, CO, NOx, AND PM
US20120042631A1 (en) * 2010-08-20 2012-02-23 Gm Global Technology Operations, Inc. Catalyst materials for ammonia oxidation in lean-burn engine exhaust
CN102536393A (zh) * 2010-11-24 2012-07-04 福特全球技术公司 用于治理来自车辆的贫排放物的混合氧化催化剂系统
CN107956556A (zh) * 2016-10-14 2018-04-24 丰田自动车株式会社 内燃机的排气净化装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007008954B4 (de) 2007-02-21 2009-12-17 Umicore Ag & Co. Kg Katalysatorsystem und seine Verwendung

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US5656244A (en) * 1995-11-02 1997-08-12 Energy And Environmental Research Corporation System for reducing NOx from mobile source engine exhaust
US6375910B1 (en) * 1999-04-02 2002-04-23 Engelhard Corporation Multi-zoned catalytic trap and methods of making and using the same
US6499294B1 (en) * 1998-09-18 2002-12-31 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification device for an internal combustion engine
US6539709B2 (en) * 2000-05-02 2003-04-01 Nissan Motor Co., Ltd. Exhaust gas purifying system of internal combustion engine
US6729125B2 (en) * 2000-09-19 2004-05-04 Nissan Motor Co., Ltd. Exhaust gas purifying system
US6823662B1 (en) * 1999-10-21 2004-11-30 Nissan Motor Co., Ltd. Exhaust gas purifying system

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Publication number Priority date Publication date Assignee Title
US5471836A (en) * 1991-10-14 1995-12-05 Toyota Jidosha Kabushiki Kaisha Exhaust purification device of internal combustion engine
US5656244A (en) * 1995-11-02 1997-08-12 Energy And Environmental Research Corporation System for reducing NOx from mobile source engine exhaust
US6499294B1 (en) * 1998-09-18 2002-12-31 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification device for an internal combustion engine
US6375910B1 (en) * 1999-04-02 2002-04-23 Engelhard Corporation Multi-zoned catalytic trap and methods of making and using the same
US6823662B1 (en) * 1999-10-21 2004-11-30 Nissan Motor Co., Ltd. Exhaust gas purifying system
US6539709B2 (en) * 2000-05-02 2003-04-01 Nissan Motor Co., Ltd. Exhaust gas purifying system of internal combustion engine
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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060037307A1 (en) * 2004-08-20 2006-02-23 Southwest Research Institute Method for rich pulse control of diesel engines
WO2006023079A2 (en) * 2004-08-20 2006-03-02 Southwest Research Institute Method for rich pulse control of diesel engines
US7137379B2 (en) * 2004-08-20 2006-11-21 Southwest Research Institute Method for rich pulse control of diesel engines
WO2006023079A3 (en) * 2004-08-20 2007-04-19 Southwest Res Inst Method for rich pulse control of diesel engines
US20100242448A1 (en) * 2009-03-26 2010-09-30 Gm Global Technology Operations, Inc. Exhaust gas treatment system including a four-way catalyst and urea scr catalyst and method of using the same
US8555617B2 (en) * 2009-03-26 2013-10-15 GM Global Technology Operations LLC Exhaust gas treatment system including a four-way catalyst and urea SCR catalyst and method of using the same
US8522536B2 (en) * 2009-05-21 2013-09-03 Southwest Research Institute Exhaust aftertreatment systems for gasoline and alternative-fueled engines, with reduction of HC, CO, NOx, and PM
US20100293929A1 (en) * 2009-05-21 2010-11-25 Southwest Research Institute EXHAUST AFTERTREATMENT SYSTEMS FOR GASOLINE AND ALTERNATIVE-FUELED ENGINES, WITH REDUCTION OF HC, CO, NOx, AND PM
US20120042631A1 (en) * 2010-08-20 2012-02-23 Gm Global Technology Operations, Inc. Catalyst materials for ammonia oxidation in lean-burn engine exhaust
CN102536393A (zh) * 2010-11-24 2012-07-04 福特全球技术公司 用于治理来自车辆的贫排放物的混合氧化催化剂系统
US20130058849A1 (en) * 2010-11-24 2013-03-07 Ford Global Technologies, Llc System for remediating emissions and method of use
US8628742B2 (en) * 2010-11-24 2014-01-14 Ford Global Technologies, Llc System for remediating emissions and method of use
CN107956556A (zh) * 2016-10-14 2018-04-24 丰田自动车株式会社 内燃机的排气净化装置

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