CN102847434A - Nobel-metal-free lean NOx trap - Google Patents

Nobel-metal-free lean NOx trap Download PDF

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CN102847434A
CN102847434A CN201210222291XA CN201210222291A CN102847434A CN 102847434 A CN102847434 A CN 102847434A CN 201210222291X A CN201210222291X A CN 201210222291XA CN 201210222291 A CN201210222291 A CN 201210222291A CN 102847434 A CN102847434 A CN 102847434A
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nox
nox trap
catalytic converter
rare
adsorbent equipment
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M·巴莱诺维奇
Y·M·S·雅各布
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Ford Global Technologies LLC
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    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
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    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
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    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9481—Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start
    • 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
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
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    • B01D2251/00—Reactants
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Abstract

The invention relates to a nobel-metal-free lean NOx trap. Specifically, the invention relates to an absorption device, in the form of a lean NOx trap, for temporary absorption of nitric oxides from an exhaust stream in an engine. In an exemplary method, the absorption device comprises a ground substance and an absorption layer applied thereon. The absorption device does not contain elements from the following group consisting of Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au. In addition, absorbed nitric oxides are substantially not reduced under the working condition. In some embodiments, the lean NOx trap may be included in a catalytic converter system with a selective-catalytic-reduction catalytic converter.

Description

The rare NOx trap of non precious metal
Related application
The application requires the priority of the German patent application No.102011078326.1 that submitted on June 29th, 2011, and this is for reference for its whole content of all purposes is incorporated into.
Background technology
Adsorbent equipment can be used for the emission control system of explosive motor, for example, is used in the motor vehicles with the Diesel engine operation, in order to reduce the discharging (NOx discharging) of nitrogen oxide.For example, the adsorbent equipment of a kind of rare NOx trap (LNT) form can comprise matrix and apply thereon adsorption layer, is used for interim absorption from the nitrogen oxide of exhaust stream, particularly from the nitrogen oxide of the exhaust stream of explosive motor.For this purpose, this LNT absorption and the interim NOx that stores from the exhaust stream that is conducted through.
Because the storage volume of LNT is by restricted inevitably, the NOx that stores must be removed every now and then.For this reason, the operational factor that can regulate engine is stored in NOx among the LNT with removing.For example, engine can change to rich mode from the rare pattern during the storage process.This causes being enriched with the burning and gas-exhausting of carbon monoxide (CO) and hydrocarbon (HC).Simultaneously, rich mode increases delivery temperature.As a result, the temperature in the LNT catalytic converter increases, and wherein this moment, CO and HC will enter LNT from exhaust extraly during rich pulse mode.
The LNT catalytic converter can have the metal coating from platinum family.These catalyst make the NOx of storage and play the CO of reducing agent effect and HC between various redox reactions occur, wherein NOx is converted to the nitrogen G﹠W.After the NOx that stores was converted, engine switched rare pattern of getting back to, and the storage circulation begins again.
The top LNT catalytic converter type of mentioning is for example learnt from EP 1004347B1.Disclosed catalytic converter has double-layer structural in described document, and wherein ground floor is responsible for the NOx storage, and the second layer comprises noble metal component, and NOx is decomposed by means of these noble metal component.Described catalytic converter is kept rare/richness, be that is to say not being alternately to work constantly, and obtains approximate 20 to 30% conversion ratio of the nitrogen oxide flow through here.
But the used noble metal of NOx that is used for the reduction storage in the LNT catalytic converter that the inventor has realized that in routine can increase the cost of these catalytic converters significantly.And the manufacturing of this system can be expensive.In addition, some catalyst systems can be very sensitive to catalyst poison, for example produces and affect hydrogen sulfide and other sulfur-containing compounds of catalytic activity between the main combustion period of sulfurous fuels.Described compound generally also can suitably be decomposed by noble coatings, but needed high catalytic converter temperature can shorten the working life of catalytic converter widely for this purpose.
Except the LNT catalytic converter, so-called SCR catalytic converter (SCR) is known in the exhaust gas purification field.SCR relates to the SCR technology of the nitrogen oxide in the exhaust in combustion plant, incineration firing facility, combustion gas turbine, industrial plants and the engine.Chemical reaction in the SCR catalytic converter is optionally, that is to say, preferably, nitrogen oxide (NO, NO 2) be reduced, and undesirable secondary reaction (for example, the oxidation of sulfur dioxide and generate sulfur trioxide) is prevented from substantially.
For the SCR reaction occurs, need to be mixed in the ammonia (NH of exhaust 3).In the returning of nitrogen oxide and ammonia/product of altogether balanced reaction (comproportionation reaction) is water (H 2O) and nitrogen (N 2).Two types catalyst is arranged.One type is made of titanium dioxide, vanadic anhydride and tungsten oxide substantially.Another kind of type is utilized zeolite.In the situation of diesel vehicle, mainly be in the situation of commerial vehicle, utilize the SCR method so that the reducing polluted emission thing.
Here, the ammonia that needs is not directly utilized, and that is to say not the form with pure ammonia, but with the form utilization of 32.5% aqueous urea solution, is called without exception in industry
Figure BDA00001820088200021
This composition is for example regulated in DIN70070.This solution for example is injected in the exhaust pathway by measuring pump or injector at the SCR upstream of catalytic converter.Since hydrolysis, ammonia and CO 2Formed by aqueous solution of urea.The ammonia that produces like this under corresponding temperature can with mode recited above in the SCR catalytic converter with exhaust in nitrogen oxide react.
Why needed ammonia is not that this material is dangerous with the form of pure ammonia by vehicle-mounted reason.Ammonia has corrosiveness to skin and mucous membrane (particularly to eyes), and it forms explosive mixture in air.
The amount of the urea that sprays depends on the nitrogen oxides emissions of engine, therefore depends on current rotary speed and the torque of engine.According to untreated emissions from engines, the consumption of aqueous solution of urea is equivalent to approximate 2 to 8% of used diesel fuel.Therefore the vehicle-mounted corresponding vessel volume that provides is provided, and this can be understood as a bit unfavorable.Particularly, this is used in the passenger vehicle of diesel oil operation, because additional container must be provided inexpediently.
By SCR, nitrogen oxide is removed from exhaust in a large number.Compare with diesel particulate filter or LNT above-mentioned, do not consume excessive fuel and reduce pollutant, because compare with catalytic converter above-mentioned, the SCR catalytic converter does not need to depart from apart from any of best combustion condition at run duration temporarily.When in commerial vehicle, utilizing the SCR technology, for example, be used for moving needed The ammonia of form cause other demands.Because its specific character, it must move medium as another and be carried out in high-grade steel or plastic containers vehicle-mountedly, and is ejected in the exhaust stream continuously.As a result, except SCR catalytic converter and spraying system, except diesel fuel tanks also needs second common less container.And, should be pointed out that at run duration,
Figure BDA00001820088200031
Must spray in variable mode.Up to now, by means of so-called supply ratio,
Figure BDA00001820088200032
Must be modulated into the NOx that is suitable in the exhaust quality stream.Here, if drop into too many urea, the ammonia that then forms thus will no longer can react with NOx.In this incorrect situation of batching, ammonia can entered environment in.Even because ammonia also can perception in the situation of very little concentration, so this causes offensive odour.
Another characteristic of SCR catalytic converter is the catalyst activity that only can obtain appropriateness in the temperature that is higher than approximate 200 ° of C.Therefore during the cold operation stage of engine, the SCR catalytic converter is actually inertia, and can not impel the reduction of NOx emission.
At last, the selection that LNT catalytic converter and SCR catalytic converter sequentially are set in gas exhaust piping is known, specifically by this way, is arranged on the upstream of SCR catalytic converter along the direction LNT of exhaust stream.This set can guarantee that the nitrogen oxide that is not captured by the LNT catalytic converter is neutralized in the SCR catalytic converter.
This set for example from US 2007/0012032 and US6, is learnt among 732, the 507B1.In the disclosed catalyst system, the LNT catalytic converter that comprises in each case noble metal uses with the SCR catalytic converter in described document, and wherein system described herein does not provide direct outside supply of ammonia, that is to say, for example passes through
Figure BDA00001820088200033
Supply with.In described the setting, engine alternately remains in rare pattern and the rich mode, and therefore the nitrogen oxide in rare pattern storage is reduced during rich mode.Here, during rich mode, the NOx in the LNT catalytic converter is restored to the oxidation stage of ammonia at least in part, and being total to equilibrium for above-described and NOx after this in the SCR catalytic converter needs.
Summary of the invention
As mentioned above, the inventor of this paper has realized that and can see that in this system it is a bit disadvantageous, because the LNT catalytic converter has high bullion content, so whole system is very expensive.And, in this system, be difficult to carry out the outside supply of ammonia, because this only can occur between LNT catalytic converter and the SCR catalytic converter, and can not be in the upstream of LNT catalytic converter, because otherwise the bullion content of LNT catalytic converter is supplied with oxidation from the outside ammonia.
In a kind of exemplary method, in order to solve shortcoming above-mentioned, a kind of for interim absorption from exhaust stream, particularly from the adsorbent equipment of the nitrogen oxide of exhaust stream in the explosive motor, it comprises matrix and the adsorption layer that applies thereon, wherein this adsorbent equipment does not comprise from following one group element: Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au, and does not substantially reduce the nitrogen oxide that is adsorbed under operating mode.In some instances, this rare NOx trap can be included in the catalyst system with SCR catalytic converter.
By this way, since in rare NOx trap without noble metal, so can reduce the cost of the catalyst system that comprises rare NOx trap.And by without these metals, rare NOx trap can be not too responsive to the catalyst poison such as hydrogen sulfide and other sulfur-containing compounds that can produce between the sulfurous fuels main combustion period, therefore increases potentially the life-span of catalytic converter.
And, by the adsorbent equipment that does not have noble metal is provided, particularly, there is not the adsorbent equipment of platinum group metal, run duration can be assembled nitrogen oxide continuously.By means of the SCR catalytic converter in downstream, described nitrogen oxide can be with certain hour interval/be neutralized with gap.For this reason, the NOx of storage can be from this adsorbent equipment by thermal desorption, for example, and by with interim rich mode operation engine.
Another advantage of the present invention is particularly even in the low operating temperature that is being higher than approximate 80 ° of C, and for example during the cold operation stage, this adsorbent equipment still can adsorb the NOx from exhaust stream effectively.Therefore even it still carries out its appointed function under low operating temperature because adsorbent equipment do not have catalytic property substantially,, and when using with SCR, can allow to utilize neatly outside reducing agent source.
Storage process has guaranteed that also downstream SCR catalytic converter during the cold operation stage, was heated more tempestuously before adsorbent equipment has reached its storage volume.Therefore, the whole efficiency of this system is being high aspect the NOx reduction during the engine cold operation phase.
Should be understood that the general introduction that provides top is the design of selecting for simple form introduction, this design further describes in detailed description.This does not also mean that feature key or basic that is considered as institute's claimed subject matter, and the scope of institute's claimed subject matter is limited uniquely by the claim after describing in detail.And the theme of advocating is not limited to solve device or any part of the present invention of any shortcoming of pointing out above.
Description of drawings
Fig. 1 illustrates the exemplary engine that has catalyst system according to the present invention.
Fig. 2 illustrates the exemplary conversion ratio as the nitrogen oxide of the SCR catalytic converter of operating temperature function.
Fig. 3 illustrates for the exemplary method of operation according to catalyst system of the present invention.
Fig. 4 and Fig. 5 illustrate the exemplary comparison according to the absorption behavior of the catalytic converter of adsorbent equipment of the present invention and routine.
The specific embodiment
Below description relate to the adsorbent equipment of rare NOx trap (LNT) form in the catalyst system, this adsorbent equipment is used for interim absorption from the nitrogen oxide (NOx) of (for example in the engine shown in Figure 1) exhaust stream of engine.In some instances, this catalyst system can comprise SCR (SCR) catalyst, and it is used for the NOx that reduction is removed from rare NOx trap.For example, the catalyst activity of SCR can depend on temperature, as shown in Figure 2, therefore, as the exemplary method of the Fig. 3 that is described in greater detail below shown in, rare NOx trap can store and come self-purging NOx and basically do not reduce the NOx that is stored until reach the storage volume of rare NOx trap and/or the SCR catalyst in downstream reaches the temperature of its catalytic activity.Be stored in the NOx that substantially is not reduced in this rare NOx trap and then can be eliminated from this rare NOx trap, and by the SCR catalyst reduction in NOx trap downstream.Fig. 4 and Fig. 5 illustrate the exemplary comparison according to the absorption behavior of the LNT catalytic converter of adsorbent equipment of the present invention and routine.
Get back to accompanying drawing 1, Fig. 1 illustrates the combustion chamber of the explosive motor machine 10 that comprises catalyst system 22 or the example embodiment of cylinder.Fig. 1 only illustrates a cylinder of multicylinder engine.Like this, each cylinder can comprise himself one group of air inlet/exhaust valve, a fuel injector (a plurality of fuel injector), spark plug etc. similarly.
Engine 10 can be controlled by the ground, importation from vehicle operators 130 by the control system that comprises controller 12 with via input unit 132 at least.In this example, input unit 132 comprises accelerator pedal and for generation of the pedal position sensor 134 of proportional pedal position signal PP.The cylinder of engine 10 (that is, combustion chamber) 30 can comprise having the chamber wall 136 that piston 138 is set therein.Piston 138 can be connected in bent axle 140 in order to convert the reciprocating motion of piston to bent axle rotatablely move.Bent axle 140 can be connected in via transmission system at least one driving wheel of passenger vehicle.And starter motor can be connected in bent axle 140 via flywheel, can carry out the start-up function of engine 10.
Cylinder 30 can receive air inlet via a series of air intake ducts 142,144 and 146.Air intake duct 146 also is communicated with other cylinders of engine 10 except cylinder 30.In certain embodiments, one or can comprise turbocharger more than an air intake duct, it comprises the compressor 52 that is arranged between air intake duct 142 and 144, and the exhaust driven gas turbine 54 that arranges along exhaust duct 148.This compressor 52 can be supplied with power by exhaust driven gas turbine 54 at least in part via axle 56.In certain embodiments, axle 56 can be connected in electro-motor in order to electric boosting is provided as required.The air throttle 62 that comprises choke block 164 can be along the air intake duct setting of engine, to be used for changing air inlet flow rate and/or the pressure that is provided for engine cylinder.For example, air throttle 62 can be arranged on the downstream of compressor 52, as shown in the figure, or alternately is arranged on the upstream of compressor 52.In some instances air throttle can arrange compressor 52 upstream and downstream the two.
Except cylinder 30, exhaust duct 148 can also receive the exhaust from other cylinders of engine.Exhaust sensor 126 is illustrated as being connected in the exhaust duct 148 of catalyst system 22 upstreams.Sensor 126 can be used to any suitable sensor that provides the indication of evacuating air/fuel ratio, for example general the or wide territory exhaust of linear oxygen sensors or UEGO(oxygen), bifurcation lambda sensor or EGO(as shown), the EGO of HEGO(heating), NOx, HC or CO sensor.In some instances, sensor 126 can be connected in the exhaust duct in turbine 52 and catalyst system 22 downstreams.
Each cylinder of engine 10 can comprise one or more than an inlet valve and one or more than an exhaust valve.For example cylinder 30 is shown as including at least one inlet poppet valves 150 and at least one the exhaust lift valve 156 that is arranged on cylinder 30 upper zone.In certain embodiments, each cylinder that comprises the engine 10 of cylinder 30 can comprise at least two inlet poppet valves and at least two the exhaust lift valves that are arranged on the cylinder upper district.
Inlet valve 150 can be by actuator 152 by controller 12 controls.Equally, air bleeding valve 156 can be by actuator 154 by controller 12 controls.Under some conditions, controller 12 can change offer actuator 152 and 154 signal to control the opening and closing of corresponding inlet valve and exhaust valve.The position of inlet valve 150 and exhaust valve 156 is determined by corresponding position sensor (not shown).Valve actuator can be electronics valve actuation type, cam-actuated type, electro-hydraulic type or its combination.Air inlet and exhaust valve timing can be controlled simultaneously, maybe can be with any possibility control of the cam timing of variable admission cam timing, variable exhaust cam timing, two independent variable or fixing cam timing.Each cam-actuated system can comprise one or more than a cam and can utilize one or more than a cam profile conversion (CPS) by controller 12 operation, variable cam timing (VCT), VVT (VVT) and/or lift range variable (VVL) system, to change air door operation.For example, cylinder 30 can alternately comprise via the inlet valve of electronics valve actuation control and via the exhaust valve of the cam-actuated control that comprises CPS and/or VCT.In other embodiment, air inlet and exhaust valve can be controlled by common valve actuator or actuating system or VVT actuator or actuating system.Engine can also comprise that its data can merge to determine the cam-position sensor of engine location and cam timing with crankshaft position sensor.
Cylinder 30 can have a compression ratio, and this compression ratio is when the volumetric ratio of piston 138 during at lower dead center and top dead centre.Usually, compression ratio is in 9:1 arrives the scope of 10:1.But in some examples that use different fuel, compression ratio can increase.
In certain embodiments, each cylinder of engine 10 all can comprise the spark plug 192 for ignition.Under selected mode of operation, ignition system 190 can respond the spark of self-controller 12 to shift to an earlier date signal SA and 30 provide pilot spark by spark plug 192 to the combustion chamber.But in certain embodiments, spark plug 192 can be removed, and for example can spray by automatic ignition or by fuel and in the situation of ignition, that's how things stand for some Diesel engines at engine 10.
In certain embodiments, each cylinder of engine 10 all can be configured to have for it provides one of fuel or more than a fuel injector.As nonrestrictive example, cylinder 30 is shown as including the fuel injector 166 that is directly connected in cylinder 30.Fuel injector 166 can directly inject fuel into wherein pro rata via the pulse width of electronic driver 168 with the signal FPW that receives from controller 12.By this way, fuel injector 166 provides the so-called direct injection (hereinafter being called " DI ") in the combustion cylinder 30.Be the side injector although Fig. 2 illustrates fuel injector 166, it also can be arranged on the top of piston, for example the position of close spark plug 192.Alternately, injector can be arranged on the top of inlet valve and near inlet valve.Fuel can flow to injector 166 from the high-pressure fuel system 172 that comprises fuel tank, petrolift and fuel concetrated pipe.Alternately, fuel can be by the single-stage petrolift with low-pressure delivery.And although do not illustrate, fuel tank can have the pressure transducer that signal is provided to controller 12.
Should be understood that in alternate embodiments injector 166 can be the intake port injection device that fuel is provided in the air inlet in cylinder 30 upstreams.Be to be further appreciated that cylinder 30 can receive the fuel from a plurality of injectors, for example from the fuel of a plurality of intake port injection devices, a plurality of direct injectors or its combination.
Engine 10 can also comprise the supercharging device such as turbocharger 50.Turbocharger 50 can comprise the compressor 52 that arranges along air intake duct 42.This compressor 52 can be driven by the turbine 54 that arranges along exhaust duct 45 at least in part via axle 56.The amount of the supercharging that is provided by turbocharger can be changed by engine controller.For example, the amount of supercharging can be regulated by control waste gate 58.In an example, the amount of supercharging can reduce by opening waste gate 58 and allowing more exhausts to walk around this turbine.Alternately, the amount of supercharging can increase by closing waste gate (or reduce waste gate open) and allowing still less exhaust to walk around this turbine.In other embodiments, turbine 54 can be variable geometry turbine (VGT) or variable nozzle turbine (VNT).This VGT or VNT can be conditioned to satisfy the supercharging needs.And waste gate, VNT and/or VGT can be adjusted to the situation of overrunning that prevents in turbocharger.In certain embodiments, optionally inflate aftercooler 34 and can be included in the air intake duct 42 downstream at compressor 52.This aftercooler can be configured to reduce the temperature of the air inlet of being compressed by turbocharger 50.
The catalyst system 22 that is connected in exhaust duct 45 can comprise one of the closed link position that is installed in the exhaust or more than an emission control system.One or can comprise that more than an emission control system adsorbent equipment 77, SCR catalyst 76 and other are unshowned, for example, three-way catalyst, micronic filter, oxidation catalyst etc.Emission control system can be positioned in the exhaust duct 45 upstream and/or the downstream at turbine 54.
For example, adsorbent equipment 77 can be to comprise matrix and rare NOx trap of applying adsorption layer thereon, to be used for that absorption comes self-purging NOx and basically reducing NOx not.For example adsorbent equipment 77 can not comprise from following one group element: Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au, and does not substantially reduce the nitrogen oxide that is adsorbed under operating mode.
For adsorbent equipment 77, if do not use the element that under operating mode, can reduce more than the NOx of 1% volume, then be favourable.The operating mode of adsorbent equipment is understood to mean the normal flow in emission control system.In fact adsorbent equipment does not have the temperature range of catalytic action to the reduction of nitrogen oxide is the scope that is in from 80 to 600 ° of C.
For example, adsorbent equipment 77 can not have noble metal, does not particularly have the platinum group metal, and therefore, operating period can be assembled nitrogen oxide continuously.Afterwards, by means of the SCR catalytic converter 76 in downstream, described nitrogen oxide can be with certain hour interval/be neutralized off and on.For this reason, the NOx that is stored can be from adsorbent equipment 77 by thermal desorption.Needed temperature increase can realize in a known way by means of interim rich mode, wherein can realize the NOx desorption in the situation that is not having temperature to increase during the rich mode.
Advantage of the present invention particularly even in the low operating temperature that is higher than approximate 80 ° of C, that is to say that for example during the cold operation stage, this adsorbent equipment still can adsorb the NOx from exhaust stream effectively.Because adsorbent equipment does not have catalytic property substantially, therefore even in low operating temperature it still carries out its appointed function.
And storage process has guaranteed that downstream SCR catalytic converter 76 was being heated during the cold operation stage more tempestuously before adsorbent equipment has reached its storage volume.Therefore, the whole efficiency of this system is being high aspect the NOx reduction during the engine cold operation phase.
In another embodiment, adsorbent equipment 77 can also not comprise a group element that is made of Fe, Co and Ni.Adsorbent equipment 77 in principle can be by all host materials and made for the production of the structure of conventional LNT catalytic converter.For this reason, matrix can be selected certainly, particularly, selects self-alumina, silica, aluminosilicate, titanium dioxide, vanadic anhydride, tungsten oxide and/or zirconia, is preferably zeolite.And in order to obtain the mechanical strength of large surface area and appropriateness, matrix can be provided as honeycomb particularly.
As mentioned above, adsorbent equipment 77 comprises adsorption layer.Described adsorption layer can have all material that is suitable for nitric oxide adsorption (NOx), wherein usually by the metal oxide manufacturing.For example, adsorption layer can comprise from following one group at least a compound: BaO, CeO 2, MgO, ZrO 2, MnO x, SnO 2, FeO x
Adsorbent equipment 77 can not have the obvious catalytic property for nitrogen oxides reduction.That is to say, both do not accelerated significantly the NOx reduction reaction, also do not reduce significantly the activation evergy that is used for the respective reaction step.This not only is applied to the nominal situation of rare pattern, and preferably also for the rich mode that carries out with the certain hour interval.Therefore even at this adsorbent equipment of enriched combustion impulse duration, still basically do not reduce the nitrogen oxide that adsorbs, but can be desorbed and in SCR catalytic converter 76, be reduced subsequently at described nitrogen oxide during the rich mode.
The SCR(SCR) relates to the SCR of the NOx in the exhaust of fuel facility, incineration firing facility, combustion gas turbine, industrial plants and engine.Chemical reaction in SCR catalytic converter 76 is optionally, that is to say, preferably nitrogen oxide (NO, NO 2) be reduced, and undesirable secondary reaction (for example, the sulfur oxide oxidation forms sulfur dioxide) is prevented from substantially.
In order to react, need to be mixed in the ammonia (NH of exhaust 3).The product of the common balanced reaction of nitrogen oxide and ammonia is water (H 2O) and nitrogen (N 2).Two types catalyst is arranged.One type is substantially to be made of titanium dioxide, vanadic anhydride and tungsten oxide.Another kind of type is utilized zeolite.
From exhaust, remove a large amount of nitrogen oxide by SCR.Compare with the LNT of diesel particulate filter (DPF) or routine, do not consume excessive fuel and reduce pollutant, because compare with the LNT of routine, the SCR catalytic converter does not need to depart from apart from any of best combustion condition during operation temporarily.
In certain embodiments, adsorbent equipment 77 is arranged on the upstream of SCR catalytic converter 76 in catalyst system 22.And it is particularly preferred that adsorbent equipment is arranged in the SCR catalytic converter.In this case, adsorbent equipment and SCR catalytic converter can be accommodated in the common shell.
Can be provided for supplying with to exhaust stream supply (infeed) device 80 of reducing agent, ammonia source specifically, this feedway is arranged on the upstream of SCR catalytic converter 76.Described feedway can by
Figure BDA00001820088200091
Supply with formation,
Figure BDA00001820088200092
Itself be known.
In some instances, feedway 80 can be arranged on the upstream of turbocharger turbine 54, the reducing agent 82 such as urea or ammonia can be ejected in the exhaust, reacts at SCR catalyst 76 and NOx material being used for.Specifically, feedway 80 responses can be ejected into reducing agent 82 exhaust of turbine 54 upstreams from the signal of engine controller reception.By at turbine injected upstream reducing agent and by turbine the reducing agent that sprays being offered the SCR catalyst, can improve mixing of the gasification of reducing agent and reducing agent and exhaust.And the amount that reducing agent sprays and/or timing can be conditioned according to the engine operating condition such as the variation of the variation of supercharging and waste gate position.In alternate embodiments, feedway 80 can be arranged on the downstream of turbine 54.
In another embodiment of catalyst system, feedway 80 can be arranged on the upstream of adsorbent equipment 77.This set is particularly advantageous, because adsorbent equipment and SCR catalytic converter for example can be installed under the vehicle chassis, and feedway can be arranged in the engine nacelle that for example is more prone to approach.In the hitherto known catalyst system that comprises the LNT catalytic converter that comprises noble metal, can't realize this set, because known LNT is because its noble coatings former thereby oxidation is comprised in ammonia in the exhaust stream, so that described ammonia will no longer can be used for nitrogen oxides reduction.
Also have, in the situation according to adsorbent equipment of the present invention, the outside of reducing agent is supplied with, and for example that is to say
Figure BDA00001820088200101
Also can easily occur in the upstream of adsorbent equipment.Therefore also can be installed in the common shell 69 with downstream SCR catalytic converter according to adsorbent equipment of the present invention, this is owing to do not need to occur the reducing agent supply between adsorbent equipment and SCR catalytic converter.The reason that can obtain this advantage is, do not need senior metal coating and therefore do not need the catalytic action of adsorbent equipment.
In the situation of diesel vehicle, utilize the SCR method mainly to be used in the situation of commerial vehicle, in order to reduce pollutant emission.Here, needed ammonia is not directly utilized, and that is to say, not with the form of pure ammonia, but is utilized with the form of 32.5% aqueous urea solution, is called without exception in industry
Figure BDA00001820088200102
This composition for example is conditioned in DIN70070.This solution S CR upstream of catalytic converter for example is injected in the exhaust pathway by measuring pump or injector.Since hydrolysis, ammonia and CO 2Formed by aqueous solution of urea.Therefore the ammonia that produces the temperature of correspondence can with mode recited above in the SCR catalytic converter with exhaust in nitrogen oxide react.
Why required ammonia is not that this material is dangerous by vehicle-mounted reason in pure ammonia mode.Ammonia has corrosiveness to skin and mucous membrane (particularly to eyes), and it forms explosive mixture in air.
The amount of the urea that sprays depends on the discharged nitrous oxides of engine, therefore depends on current rotary speed and the torque of engine.According to untreated engine emission, the consumption of aqueous solution of urea is equivalent to approximate 2 to 8% of used diesel fuel.Therefore need to provide the vessel volume of correspondence, this can think a bit unfavorable vehicle-mountedly.Particularly, this is unfavorable for being used in the passenger vehicle of diesel oil operation, because additional container must be provided.When in commerial vehicle, utilizing the SCR technology, for example, be used for moving needed
Figure BDA00001820088200103
The ammonia of form can cause extra needs.Because its specific character must be implemented in high-grade steel or the plastic containers as another kind of working media, and be ejected in the exhaust stream continuously vehicle-mountedly.As a result, except SCR catalytic converter and spraying system, except diesel fuel tanks also needs second common less container.
And, should be pointed out that during operation,
Figure BDA00001820088200104
Must spray in variable mode.Up to now, by means of so-called supply ratio
Figure BDA00001820088200105
Must be modulated into the NOx that is suitable in the exhaust quality stream.Here, if drop into too many urea, the ammonia that then forms thus will no longer can react with NOx.In this incorrect situation of batching, ammonia can entered environment in.Even because in the situation of very little concentration, ammonia still can be perceived, so this produces offensive odour.
In order to determine when reached its storage volume according to adsorbent equipment of the present invention, described adsorbent equipment 77 can have or can measurement mechanism 79 be set in described adsorbent equipment downstream, determines NOx content in the exhaust stream or this adsorbent equipment downstream with this measurement mechanism 79 by means of sensor.Alternately, for this purpose, also can utilize the mathematical algorithm that is stored in the control device, and this algorithm is considered operating mode and is specified the conversion time that is molded into rich mode from rare.
Be illustrated as microcomputer at Fig. 1 middle controller 12, comprise: microprocessor (CPU) 106, input/output end port (I/O) 108, the Electronic saving medium that is used for storing executable program and calibration value that in this concrete example, is shown read-only storage (ROM) 110, random-access memory (ram) 112, keep-alive memory (KAM) 114 and conventional data/address bus.Controller 12 can receive the various signals from the sensor that is connected in engine 10, except those signals previously discussed, also comprises: from the measurement that is introduced into quality air stream (MAF) of quality air flow sensor 122; Engine coolant temperature (ECT) from the temperature sensor 116 that is connected in coolant jacket 118; From the hall effect sensor 120(or the other types that are connected in bent axle 140, for example crankshaft position sensor) PIP Profile Igntion PickUp signal (PIP); Throttle position (TP) from the TPS (not shown); And from the absolute manifold pressure signal (MAP) of sensor 124.Controller 12 can be from signal PIP(or crankshaft position sensor) produce engine rotational speed signal, RPM.Can be used to provide indication for the vacuum in the inlet manifold or pressure from the manifold pressure signal MAP of manifold pressure sensor.Storage medium read-only storage 110 can be programmed the instruction that mechanized data represents, can by microprocessor 106 carry out these instructions be used for carrying out said method and can expect but other distortion of specifically not listing.
Fig. 2 illustrates by the common balanced NOx that reacts commercially available SCR catalytic converter with ammonia and reduces and temperature relation.From being clear that in the operating temperature of only having 200 ° of C and the above situation, just guarantee to remove reliably NOx here.On the contrary, this means that the SCR catalytic converter can not guarantee the reduction of nitrogen oxide of cold-start phase appropriateness.Therefore, advantageously, the nitrogen oxide that produces during the cold operation stage is stored temporarily, if possible then until the SCR catalytic converter has reached its operating temperature.This can realize by adsorbent equipment according to the present invention, for example adsorbent equipment 77 above-mentioned.
Fig. 3 illustrates the exemplary method 300 of catalyst system that has the SCR catalyst of the adsorbent equipment of adsorbent equipment 77 for example and for example SCR catalyst 76 for operation.
302, method 300 comprises determines that whether engine is in the work of cold start situation.For example, after the engine cold starting of shutting down beginning, the temperature among the SCR can be lower than that catalyst is active threshold temperature among the SCR.For example as mentioned above, the mild catalytic activity in the SCR catalyst only just can obtain when temperature is higher than approximate 200 ° of C, and in the cold operation stage of engine, the SCR catalytic converter is actually inertia, and can not impel the reduction of NOx emission.Therefore, for example, determine whether engine can comprise that in the work of cold start situation whether definite ignition switch connection event occurs, and determines whether the temperature in the catalytic converter is lower than threshold temperature etc.
If engine is in cold start work, then method 300 proceeds to 306 in order to nitrogen oxide (NOx) is stored in rare NOx trap and basically do not reduce the NOx that is stored, as described in greater detail below.
If determine that 302 engine moves after the cold start situation, then method 300 proceeds to 304 so that with rare mode operation engine.Then method 300 proceeds to 306 and does not basically reduce the NOx that is stored and simultaneously with rare mode operation engine in order to nitrogen oxide (NOx) is stored in rare NOx trap.By this way, NOx can be trapped among the LNT until SCR becomes catalytic activity.
306, method 300 comprises and nitrogen oxide (NOx) is stored in rare NOx trap and basically do not reduce the NOx that is stored.As mentioned above, rare NOx trap according to the present invention does not comprise noble metal and does not have obvious catalytic property about the reduction of nitrogen oxide.That is to say, both do not accelerated significantly the reduction reaction of NOx, also do not reduce significantly the activation evergy that is used for corresponding reactions steps.This not only is applied to the nominal situation in rare pattern, but also for the rich mode that carries out with the certain hour interval.Therefore in addition the enriched combustion impulse duration or during temperature is higher than active temperature to be stored in NOx among the LNT with reduction this adsorbent equipment still basically do not reduce the nitrogen oxide that is adsorbed.
308, method 300 comprises and determines whether satisfy to remove the entry condition that is stored in the NOx in rare NOx trap.Because the storage volume of LNT is limited inevitably, so must remove every now and then the NOx that is stored.Therefore, in order to determine when adsorbent equipment reaches its storage volume, can utilize the NOx sensor, for example measurement mechanism 179, and/or mathematical algorithm can be used to determine when adsorbent equipment reaches its storage volume.For example, if the amount of determining to be stored in the NOx in rare NOx trap greater than threshold value, begins to remove the NOx that is stored in this adsorbent equipment so entry condition is satisfied.
The entry condition that is used for removing NOx also can be according to the temperature of SCR catalyst.For example, as mentioned above, the mild catalytic activity in the SCR catalyst only just can obtain when temperature is higher than approximate 200 ° of C.Therefore during the cold operation stage of engine, the SCR catalytic converter is actually inertia, and can not impel the reduction of NOx emission.Therefore, the entry condition that is used for beginning to remove the NOx that is stored in this adsorbent equipment can comprise whether the temperature of SCR is higher than threshold value becoming catalytic activity, so that the basically unreduced NOx that removes from adsorbent equipment can be reduced the SCR catalyst basically.
And the amount that remains on the ammonia among the SCR can be lower than the ammonia storage volume.The ammonia storage volume of SCR can be based on the various physical propertys of SCR, for example used catalyst type, catalyst surface area and and SCR temperature.Therefore, if the amount of the ammonia among the SCR is less than threshold value, then a certain amount of ammonia can be injected in the exhaust, for example by feedway 80, in order to provide ammonia to come the catalyst for SCR.The amount of the ammonia that sprays can be with rare pattern or with rich mode work based on the amount and the engine that for example calculate the current ammonia among the determined SCR of being stored in by sensor or model.For example, during the lean-burn that NOx just is being stored, the ammonia that need not add sprays, in an example, because NOx common Fails To Respond in SCR.But, during the lean-burn that reaches the NOx storage volume, ammonia spray can with enter SCR in the NOx emission be associated in order to react.Equally, rich operating period can provide ammonia to spray, to consider that the NOx that is stored is from the release of NOx trap.
But in some cases, the amount that is stored in the ammonia among the SCR can be greater than the ammonia storage volume of SCR, and this can cause the SCR hydraulic performance decline and be called as the ammonia release that ammonia leaks.In this case, ammonia can be d/d ammonia, maybe will can react by the NOx that increases SCR from the ammonia that SCR discharges, and for example by reacting from LNT release NOx and ammonia, comprises that power operation transforms to rich combustion from lean-burn.Therefore, being used for can be based on the amount of the ammonia that is stored in SCR from the entry condition of LNT removing NOx.For example, if the amount that is stored in the ammonia among the SCR greater than threshold value, then NOx can from LNT remove with SCR ammonia react, in order to reduce the amount of the ammonia among the SCR.By this way, ammonia spray can with LNT in the NOx storing state and driving N Ox stores or the engine combustion state (lean-burn or rich combustion) that discharges is associated, and be associated with the ammonia storing state of SCR catalyst.
If be satisfied in 304 entry conditions that be used for to remove the NOx that is stored in rare NOx trap, then method 300 proceeds to 306, otherwise method 300 is got back to 302 and do not reduced the NOx that is stored in order to continue NOx is stored in rare NOx trap.
310, method 300 comprises with rich mode operation engine and is stored in the NOx in rare NOx trap with removing and does not substantially reduce NOx in rare NOx trap.For example the running parameter of engine can change over rich mode from the rare pattern during the storage process.And the stoichiometric(al) of the operating mode of engine can be conditioned according to the aequum of the NOx that is eliminated from LNT.For example, the amount of the NOx that discharges from LNT can increase by the enrichment that increases rich mode, to hold the amount that is stored in the ammonia among the SCR.
In rich mode, engine moves and removes the NOx that is stored in the adsorbent equipment with the fuel quantity of the super stoichiometric(al) relevant with combustion air.And as mentioned above, urea can supply to the NOx of exhaust to be used for being eliminated in the reduction of SCR catalyst of SCR upstream.For example, urea can be fed into by feedway 80 and enter the exhaust that enters rare NOx trap in rare NOx trap and SCR upstream.The amount of the urea that sprays depends on the discharged nitrous oxides of engine, and therefore depends on current rotary speed and the torque of engine.
312, method 300 is included in the NOx that reduction is eliminated among the SCR.For example, the NOx that removes from adsorbent equipment 77 can be reduced downstream SCR catalyst 76.By this way, the nitrogen oxide that is stored in the adsorbent equipment can be neutralized by means of the SCR catalytic converter with the certain hour interval.For this reason, the NOx that is stored from adsorbent equipment by thermal desorption.Needed temperature increase can realize in known manner that by means of interim rich mode wherein the desorb at NOx during the rich mode also can realize in the situation that does not have temperature to increase.
Fig. 4 illustrates the accompanying drawing of comparison, and this comparative drawings figs illustrates each other abreast according to the storge quality of the nitrogen oxide of adsorbent equipment of the present invention (for example adsorbent equipment 77) and the storge quality of nitrogen oxide that comprises the conventional LNT catalytic converter of noble metal.In this example, adsorbent equipment according to the present invention is formed by the alumina host with honeycomb identical with the LNT catalytic converter.Matrix according to adsorbent equipment of the present invention has the adsorption layer that is made of barium monoxide.
Fig. 5 illustrates for new Europe and drives circulation (NEDC) stage, according to the storge quality of adsorbent equipment of the present invention with the nitrogen oxide of the LNT catalytic converter that comprises noble metal.
Fig. 4 and Fig. 5 illustrate the cold start part that drives circulation (NEDC) stage according to new Europe.The schematic diagram of Fig. 4 illustrates at low thermophase, and adsorbent equipment according to the present invention has the NOx storge quality that is similar to conventional LNT.Therefore the correspondence of the NOx concentration of this adsorbent equipment upstream and LNT upstream measurement curve overlaps substantially.But at hot stage, nitrogen oxide is desorbed from adsorbent equipment according to the present invention, and in the situation of LNT catalytic converter, a part of NOx is decomposed by noble metal catalyst.This causes the remarkable increase of the NOx concentration in this adsorbent equipment downstream.
Should be pointed out that the exemplary control and the estimation routine that comprise can be with various engines and/or the application of Vehicular system structure here.Concrete routine described herein can represent in any number processing policy one or more than one, such as event driven, drives interrupts, multitask, multithreading etc.Therefore, shown various steps, operation or function can with shown in order carry out, carry out simultaneously, or can omit in some cases.Equally, in order to realize the feature and advantage of the exemplary embodiments described here, the order of processing is not essential the requirement, but provides in order to illustrate easily and to describe.One or can repeatedly carry out according to used specific policy more than the step shown in or function.And exemplary routine can diagrammatically shownly be programmed in the coding in the computer-readable storage media in the controller.
Should be understood that structure disclosed herein and program are exemplary in nature, and these specific embodiments are not considered to restrictive, because many variations are possible.For example, above-mentioned technology can be used for V-6, I-4, I-6, V-12, opposed 4 and other engine types.Theme of the present invention comprise various system disclosed herein and structure and other features, function and/or character all novelties with non-obvious combination and sub-portfolio.
Below claim specifically note and think novel and more non-obvious combinations and sub-portfolio.These claims may relate to " a kind of " element or " first " element or its equivalent.These claims should be understood to comprise one or more than the combination of a this element, both neither requiring nor excluding two or more this elements.The combination of disclosed feature, energy supply, element and/or character or sub-portfolio can propose new claim by the modification of this claim or in this related application and advocate.These claims, than former claim on scope be wider, narrower, equate or difference all is contemplated as falling with in the theme of the present invention.

Claims (21)

1. one kind is used for interim absorption from the adsorbent equipment of the nitrogen oxide of the exhaust stream of engine, comprising:
Matrix and apply thereon adsorption layer, wherein this adsorbent equipment does not comprise from following one group any element: Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au, and under operating mode, substantially do not reduce the nitrogen oxide that is adsorbed.
2. adsorbent equipment according to claim 1, wherein this adsorbent equipment does not comprise coming any element of the group that free Fe, Co and Ni consist of.
3. adsorbent equipment according to claim 1, wherein this matrix is selected from aluminium oxide, silica, aluminosilicate, titanium dioxide, vanadic anhydride, tungsten oxide and/or zirconia, and is provided as particularly honeycomb.
4. adsorbent equipment according to claim 1, wherein this matrix is zeolite.
5. adsorbent equipment according to claim 1, wherein this adsorption layer comprises from following one group at least a compound: BaO, CeO 2, MgO, ZrO 2, MnO x, SnO 2, FeO x
6. adsorbent equipment according to claim 1, wherein this adsorbent equipment does not reduce the described nitrogen oxide that is adsorbed substantially in richness combustion pulse situation.
7. one kind is used for reduction from the system of the nitrogen oxide of the exhaust stream of engine, comprising:
Rare NOx trap;
The SCR catalytic converter, this rare NOx trap comprises matrix and the adsorption layer that applies thereon, wherein this rare NOx trap does not comprise from following one group any element: Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au, and under operating mode, substantially do not reduce the nitrogen oxide that is adsorbed.
8. system according to claim 7, wherein this rare NOx trap is arranged on the upstream of this SCR catalytic converter.
9. system according to claim 7, wherein this rare NOx trap is arranged in the SCR catalytic converter, and wherein this rare NOx trap and this SCR catalytic converter are accommodated in the common housing.
10. system according to claim 7 comprises that also wherein this feedway is arranged on the upstream of this SCR catalytic converter for the feedway in supply ammonia source.
11. system according to claim 10, wherein this feedway is arranged on the upstream of this rare NOx trap.
12. a method that is used for the operation engine comprises:
Be stored in NOx in rare NOx trap and basically do not reduce the NOx that is stored; And
Respond an event, move described engine in order to remove the NOx in described rare NOx trap, be stored and basically do not reduce NOx in described rare NOx trap with rich mode, and in the SCR catalytic converter the described NOx that is eliminated of reduction.
13. method according to claim 12, wherein this event is to be stored in the amount of the NOx in described rare NOx trap greater than threshold value.
14. method according to claim 12, wherein NOx is stored in rare NOx trap and this engine is with rare mode operation when substantially not reducing the NOx that is stored, and wherein this event is that the temperature of this SCR catalytic converter is greater than threshold value.
15. method according to claim 12, wherein this event is to be stored in the amount of the ammonia in this SCR catalytic converter greater than threshold value.
16. method according to claim 12, wherein this rare NOx trap does not comprise from following one group any element: Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au.
17. method according to claim 12, wherein this rare NOx trap does not comprise any element from the group that comprises Fe, Co and Ni.
18. method according to claim 12, wherein this rare NOx trap comprises matrix and the adsorption layer that applies thereon, and wherein this matrix is selected from aluminium oxide, silica, aluminosilicate, titanium dioxide, vanadic anhydride, tungsten oxide or zirconia.
19. method according to claim 18, wherein this adsorption layer comprises at least from following one group a kind of compound: BaO, CeO 2, MgO, ZrO 2, MnO x, SnO 2, FeO x
20. method according to claim 12, wherein this rare NOx trap is arranged in this SCR catalytic converter, wherein this rare NOx trap and this SCR catalytic converter are accommodated in the common housing, and the method also is included in the upstream of this rare NOx trap and this SCR catalytic converter to the exhaust supply urea that enters this rare NOx catalyst.
21. a method that is used for the operation engine comprises:
Adjusting is sprayed to the ammonia of the SCR catalyst that is connected in NOx trap downstream, this NOx trap does not comprise from following one group any element: Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au, according to regulating the ammonia emitted dose in the air-fuel ratio at this NOx trap place and the amount that is stored in the ammonia among the described SCR, engine air-fuel ratio also is conditioned based on the ammonia amount that is stored.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104475006A (en) * 2014-11-17 2015-04-01 清华大学 Absorbent for storing nitrogen oxides of diesel engine and lean-burn gasoline engine and preparation of absorbent
CN107109984A (en) * 2015-01-12 2017-08-29 全耐塑料高级创新研究公司 NOx reduction system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070012032A1 (en) * 2005-07-12 2007-01-18 Eaton Corporation Hybrid system comprising HC-SCR, NOx-trapping, and NH3-SCR for exhaust emission reduction
CN101610844A (en) * 2006-11-29 2009-12-23 巴斯福催化剂公司 The NO of resistant to thermal aging xStorage material and trap
WO2010026814A1 (en) * 2008-09-02 2010-03-11 日産自動車株式会社 Exhaust gas purifying catalyst and method for producing the same

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19854794A1 (en) 1998-11-27 2000-05-31 Degussa Catalyst for the purification of the exhaust gases of a diesel engine
GB0104682D0 (en) * 2001-02-26 2001-04-11 Johnson Matthey Plc Gas treatment using ammonia
US6732507B1 (en) 2002-12-30 2004-05-11 Southwest Research Institute NOx aftertreatment system and method for internal combustion engines
US8122712B2 (en) * 2008-01-03 2012-02-28 GM Global Technology Operations LLC Exhaust system with improved NOX emission control
DE102008026191B4 (en) * 2008-05-30 2020-10-08 Daimler Ag Motor vehicle with internal combustion engine and an exhaust gas aftertreatment device as well as a method for reducing particulate and nitrogen oxide

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070012032A1 (en) * 2005-07-12 2007-01-18 Eaton Corporation Hybrid system comprising HC-SCR, NOx-trapping, and NH3-SCR for exhaust emission reduction
CN101610844A (en) * 2006-11-29 2009-12-23 巴斯福催化剂公司 The NO of resistant to thermal aging xStorage material and trap
WO2010026814A1 (en) * 2008-09-02 2010-03-11 日産自動車株式会社 Exhaust gas purifying catalyst and method for producing the same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104475006A (en) * 2014-11-17 2015-04-01 清华大学 Absorbent for storing nitrogen oxides of diesel engine and lean-burn gasoline engine and preparation of absorbent
CN107109984A (en) * 2015-01-12 2017-08-29 全耐塑料高级创新研究公司 NOx reduction system

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