CN114109567A - LNT carrier and lean-burn NOxTrap and car - Google Patents
LNT carrier and lean-burn NOxTrap and car Download PDFInfo
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- CN114109567A CN114109567A CN202010880654.3A CN202010880654A CN114109567A CN 114109567 A CN114109567 A CN 114109567A CN 202010880654 A CN202010880654 A CN 202010880654A CN 114109567 A CN114109567 A CN 114109567A
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- 239000011248 coating agent Substances 0.000 claims abstract description 83
- 238000000576 coating method Methods 0.000 claims abstract description 83
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Inorganic materials [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 claims description 32
- 239000011247 coating layer Substances 0.000 claims description 23
- 229910052763 palladium Inorganic materials 0.000 claims description 13
- 229910052697 platinum Inorganic materials 0.000 claims description 13
- 229910052703 rhodium Inorganic materials 0.000 claims description 12
- 229910000510 noble metal Inorganic materials 0.000 claims description 11
- 239000000654 additive Substances 0.000 claims description 10
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 9
- 230000001965 increasing effect Effects 0.000 claims description 8
- 230000000996 additive effect Effects 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 229910000505 Al2TiO5 Inorganic materials 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 3
- 239000000470 constituent Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- AABBHSMFGKYLKE-SNAWJCMRSA-N propan-2-yl (e)-but-2-enoate Chemical compound C\C=C\C(=O)OC(C)C AABBHSMFGKYLKE-SNAWJCMRSA-N 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 230000002708 enhancing effect Effects 0.000 claims description 2
- 238000000746 purification Methods 0.000 abstract description 21
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 136
- 239000007789 gas Substances 0.000 description 29
- 238000006243 chemical reaction Methods 0.000 description 20
- 238000012360 testing method Methods 0.000 description 18
- 238000000034 method Methods 0.000 description 15
- 239000011148 porous material Substances 0.000 description 13
- 238000002485 combustion reaction Methods 0.000 description 7
- 238000006722 reduction reaction Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Inorganic materials [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 description 5
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000000969 carrier Substances 0.000 description 3
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- 239000003973 paint Substances 0.000 description 3
- RZCJYMOBWVJQGV-UHFFFAOYSA-N 2-naphthyloxyacetic acid Chemical compound C1=CC=CC2=CC(OCC(=O)O)=CC=C21 RZCJYMOBWVJQGV-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium nitrate Inorganic materials [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 231100001143 noxa Toxicity 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910020203 CeO Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ODUCDPQEXGNKDN-UHFFFAOYSA-N Nitrogen oxide(NO) Natural products O=N ODUCDPQEXGNKDN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000005202 decontamination Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
Images
Classifications
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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
- F01N3/10—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
- F01N3/24—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 constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
-
- 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
- F01N3/24—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 constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
- F01N3/2825—Ceramics
-
- 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
- F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
- F01N2570/14—Nitrogen oxides
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The invention provides an LNT carrier and lean-burn NOXTrap and car, LNT carrier includes: a substrate and a coating; the substrate is divided into a front part and a rear part, and the coating comprises a first coating and a second coating; the first coating is applied to the front portion of the substrate for NO in the LNTXA second coating is applied to a rear portion of the substrate for NO in the LNTXStorage and release of. LNT carrier of the invention will purify NOXIs applied to the front part of the substrate to store NOXIs applied to the rear part of the substrate in such a way that NO is purified by the segmented applicationXCan be sufficiently used for NOXWithout being subjected to NOXAnd thus to increase NOXThe total efficiency of the purification.
Description
Technical Field
The invention belongs to the field of automobiles, and particularly relates to an LNT carrier and lean-burn NOXA trap and an automobile.
Background
In the emission regulation of automobiles (national emission regulation of 6), NO is treatedXThe emission limit of (a), makes more stringent requirements.
In the prior art, because the steam engine is characterized by oxygen-enriched combustion, the tail gas of the automobile contains a large amount of NOX. To reduce NO, as is known to those skilled in the artXEmission of LNT (Lean NOx Trap, Lean NO)XTrapping technology) was developed in the state 6 regulation phase and applied in automobiles. Wherein LNT is used mainly for NOxTrapping and releasing, and to NOxReducing to purify NOxThe purpose of (1).
In practical application, NO can be enabled by adding LNT in automobilexThe total purification efficiency is improved to a certain extent, but the total purification efficiency value achieved after the improvement is still lower than 75% (75% is the standard for judging whether the purification efficiency is good, and if the purification efficiency is higher than 75%, the purification efficiency is good).
Therefore, the LNT in the prior art does not enable NO in diesel vehiclesxThe total efficiency of the purification reaches a good standard.
Disclosure of Invention
To solve the problems of the prior art, NO in a diesel vehiclexThe total purification efficiency reaches a good standard, and the invention provides an LNT carrier and a lean-burn NOXA trap and an automobile.
In a first aspect, the present invention provides an LNT support comprising: a substrate and a coating; the substrate is divided into a front part and a rear part, and the coating comprises a first coating and a second coating;
wherein the first coating is applied to a front portion of the substrate and the second coating is applied to a rear portion of the substrate;
the first coating is for NO in LNTXPurifying;
the second coating is for NO in LNTXStorage and release of.
Preferably, the constituent materials of the substrate include inert materials and additives;
the inert substance comprises any one of ceramics, metal, silicon carbide and aluminum titanate;
the additive is used for increasing the specific surface area of the carrier and enhancing NO of the carrierXThe ability to adhere.
Preferably, the first coating comprises a noble metal;
the noble metal comprises at least one of Pt, Pd and Rh.
Preferably, the first coating is applied to the first half of the substrate; the second coating is coated on the back half part of the substrate;
the coating amount of the first coating layer and the coating amount of the second coating layer are determined according to the shape and the size of the substrate.
Preferably, the second coating layer comprises CeO2And BaCO3One or two of them.
Preferably, the structure of the substrate comprises a honeycomb structure.
Preferably, the substrate is integrally formed.
Preferably, the substrate is composed of a first sub-substrate and a second sub-substrate, the first sub-substrate and the second sub-substrate being placed one behind the other;
coating the first sub-substrate with the first coating;
the second sub-substrate is coated with the second coating layer.
In a second aspect, the present invention provides a lean NOXTrap, the lean-burn NOXThe trap sequentially comprises a shell, a liner and the LNT carrier from outside to inside.
In a third aspect, the present invention provides a vehicle fitted with a lean burn NO according to the second aspectXA trap for automobiles.
The embodiment of the invention provides an LNT carrier and a lean-burn NOXTrap and car, this LNT carrier includes: a substrate and a coating; the substrate is divided into a front part and a rear part, and the coating comprises a first coating and a second coating; the first coating is applied to the front portion of the substrate for NO in the LNTXA second coating is applied to a rear portion of the substrate for NO in the LNTXStorage and release of. LNT carrier of the invention will purify NOXIs applied to the front part of the substrate to store NOXIs applied to the rear part of the substrate in such a way that NO is purified by the segmented applicationXCan be sufficiently used for NOXWithout being subjected to NOXAnd thus to increase NOXThe total efficiency of the purification.
Drawings
FIG. 1 shows a schematic representation of the treatment of one type of prior art exhaust route primary aftertreatment arrangement;
FIG. 2 illustrates a schematic diagram of a LNT configuration in an embodiment of the invention;
FIG. 3 illustrates a schematic diagram of one configuration of an LNT carrier in an embodiment of the invention;
FIG. 4 shows NO for a test car in an embodiment of the present inventionXThe discharge amount of (c).
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below. The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
The treatment method of two main post-treatment arrangements of emission routes aiming at the emission regulation of 6 countries of automobiles in the industry is shown in figure 1, and figure 1 is a schematic view of the treatment method of one main post-treatment arrangement of the emission routes in the prior art.
As shown in fig. 1, one approach to the main post-treatment arrangement of the prior art exhaust route is: after passing through the supercharger, the exhaust gas enters from the exhaust inlet and sequentially passes through an LNT (fuel LNT), a DPF (Diesel Particulate Filter) and an SCR (Selective Catalytic Reduction). Wherein LNT is used for treating Nitrogen Oxide (NO) in tail gasX) Purifying, trapping and releasing, trapping carbon particles in tail gas by DPF, and trapping NO released in LNT by SCRXCarrying out catalytic reduction.
Wherein, the application of LNT makes NO in automobile exhaustXThe total purification efficiency of the purification is improved to a certain extent, but is still lower than the mark NOXThe standard value (75%) showing a good purification effect.
Accordingly, embodiments of the present invention provide an LNT carrier, lean NOXTrap and car to solve the relatively poor problem of purification effect that exists among the above-mentioned prior art.
First, the inventors have searched for NOXThe reason why the purification effect is poor. The method comprises the following specific steps:
the inventors explored the structure of an existing LNT
FIG. 2 illustrates a schematic diagram of a LNT configuration in an embodiment of the invention; as shown in fig. 2, a conventional LNT has a structure of a shuttle shape, and includes a housing 22, a packing 23, and a carrier 21. The housing 22 has openings at both ends thereof, as shown by arrows in fig. 2, for inflow and outflow of the exhaust gas; the gasket 23 is interposed between the outer peripheral wall of the carrier 21 and the inner peripheral wall of the housing 22, and plays a role in ensuring sealability and shock absorption protection; the carrier 21 is located in the casing 22, two ends of the carrier 21 in the longitudinal direction respectively face the openings of the casing 22 on the corresponding side, a plurality of pore channels extending in the longitudinal direction are arranged on the carrier 21, and the inner walls of the pore channels are coated with a coating made of Pt, Pd, Rh and CeO2And BaCO3When the tail gas flows through the carrier 21, the tail gas passes through the plurality of pore channels on the carrier 21 and fully contacts with the inner walls of the plurality of pore channels.
As shown in fig. 2, the housing 22 includes a first connecting pipe section (221), a first expanding section 222, a main body section 223, a second expanding section 224 and a second connecting pipe section 225 in sequence along the flowing direction of the exhaust gas, wherein the carrier 21 is located in the main body section 223, the first expanding section 222 and the second expanding section 224 are formed to have inner diameters gradually increasing from one end to the other end, and the ends of the first expanding section 222 and the second expanding section 224, which have the larger inner diameters, are both directed toward the main body section 223, so that the main body section has the larger inner diameter, i.e., the larger inner space, to accommodate the carrier 21, so that the gas flow flowing through the main body section can be more sufficiently attached, trapped and reacted therein.
(II) the inventors explored LNT in purifying NOXThe function and principle of
First action of the LNT: the normal occurrence of oxidation and reduction reactions as shown in the following reactions (1-6) is catalyzed by the noble metal in the inner coating. The purpose of the function is to purify pollutants of CO, HC and NOX. Among them, NO in LNTXDecontamination is also known in the industry as D-NOX。
CO+1/2O2→CO2(1) Oxidation reaction
HC+O2→H2O+CO2(2) Oxidation reaction
CO+NO→1/2N2+CO2(3) Reduction reaction (D-NO by CO)X)
HC+NO→N2+H2O+CO2(4) Reduction reaction
NO+1/2H2→H2O+NH3(5) Reduction reaction (by H)2By carrying out D-NOX)
H2+NO→H2O+1/2N2(6) Reduction reaction (by H)2By carrying out D-NOX)
Second role of the LNT: NO, NO2In CeO2、BaCO3Is stored in the LNT, this reaction process is called NOXAnd (5) storing. Wherein oxidation of NO, NOXAnother condition under which storage occurs is that the light-duty diesel engine is in a lean burn phase, and the specific reaction is shown in equation (7-8).
NOXAnd (3) storing the reaction:
BaCO3+2NO2+1/2O2→Ba(NO3)2+CO2 (7)
CeO2+3NO+2O2→Ce(NO3)3 (8)
when the light diesel engine is in the rich combustion stage, the tail gas contains a large amount of CO (carbon monoxide) and H accounting for 1.2 percent of the total amount of the tail gas2(Hydrogen) LNT in CO and H2Can release stored NOX. This process is known as NOXAnd (4) releasing. Released NOXIs purified by a subsequent exhaust gas purification device (e.g., SCR).
NOXRelease reaction：
Ce(NO3)3→CeO2+3NO2+1/2O2 (9)
Ba(NO3)2+CO2→BaCO3+3NO2+1/2O2 (10)
Ba(NO3)2+3H2+CO2→BaCO3+2NO+2CO2 (11)
Ba(NO3)2+3CO→BaCO3+2NO+2CO2 (12)
Ba(NO3)2+1/3C3H6→BaCO3+2NO+H2O (13)
As is apparent from the reaction formulae (3), (5), (6), (11) and (12) shown above, in D-NOXIn the purification reaction of (3), CO and H are required2In NOXThe release reaction also takes part in the reaction. That is, if the LNT carrier disclosed in the prior art (inside of the pore channels of the LNT carrier, formed of CeO) is used2、BaCO3Pt, Pd, Rh, and the like are uniformly mixed to obtain a mixture, and the mixture is uniformly coated), then D-NOXMiddle to NOXOxidation reaction and reduction reaction of (2) with D-NOXThe release reaction of (A) is carried out simultaneously, so that D-NOXH required in the purification reaction of (1)2Will be consumed by the liberation reaction in about half the amount such that H is consumed2Do not sufficiently participate in D-NOXThereby reducing D-NOXThe total efficiency of the purification.
Furthermore, the inventors have also found that if H is allowed to participate in the release reaction2Removing D-NOXAs shown in the equation (12), the releasing reaction can still be completed by a large amount of CO (because of the emission of a large amount of CO in the tail gas during the rich combustion) and can be free from H2The influence of the amount of (c). I.e. in D-NOXIn (1), can let H2Plays a major role, whereas in the release reaction, CO plays a major role.
That is, it is nowIn the prior art, the traditional preparation method of LNT carrier is as follows: inside the LNT carrier (i.e., the inner surface of the channels through which the exhaust gas flows), CeO2、BaCO3Pt, Pd, Rh are mixed uniformly and coated together inside the LNT support. However, the LNT carrier prepared by such a conventional preparation method can obtain D-NO in LNTXThe efficiency is relatively low. Of course, lift LNT D-NOXThe ability of (2) can be solved by increasing the coating amount of the noble metals Pt, Pd, Rh, but this increases the cost. It is foreseeable that the precious metals Pt, Pd, Rh are more expensive than gold, i.e. the process is more costly and uneconomical. The starting point of the embodiment of the invention is as follows:
H2has very excellent D-NOXCapability, but light-duty diesel engines discharge H in the exhaust gas of the combustion chamber during rich combustion2In a proportion of only about 1.2%, if CeO is added2、BaCO3Pt, Pd, Rh are coated uniformly together on the LNT carrier, as in formula (11) H above2With "BaCO3"high efficiency" NOXRelease the 'reaction to make' BaCO3"" preemption "of some of the only, small, precious H2Resource, so H2Is "BaCO3"preemption" of "affects some LNT's H2For D-NOXThe contribution of (c). I.e. H2Is "BaCO3"" preemption "affects LNT D-NOXThe main reason for the capacity. Wherein "LNT D-NOXCapacity "refers to LNT purifying NOXThe ability of the cell to perform.
The technical conception of the invention is as follows: step coating of porous channel structure inside LNT carrier, and step coating of D-NOXDesired materials (e.g. noble metals, etc.), with NOXStoring the materials (CeO) required for the reaction2、BaCO3Etc.) are separated and then coated on different positions of the porous channel structure respectively; and, in order to avoid H2Is consumed by the release reaction to convert D-NOXThe desired materials coat the front portion of the LNT support, which refers to: a portion near the exhaust gas inlet with reference to the direction of the inflow of the exhaust gas; corresponding NOXStoring materials required for reaction, coating on LNT carrierThe rear section of the body, i.e. the section close to the exhaust outlet.
Based on the technical concept described above, a first aspect of the present invention provides an LNT carrier, comprising: a substrate and a coating; the substrate is divided into a front part and a rear part, and the coating comprises a first coating and a second coating; wherein a first coating is applied to a front portion of the substrate and a second coating is applied to a rear portion of the substrate; first coating for NO in LNTXPurifying; second coating for NO in LNTXStorage and release of.
In specific implementation, fig. 3 shows a schematic structural diagram of an LNT carrier in an embodiment of the present invention, as shown in fig. 3, the substrate in the embodiment of the present invention is a porous substrate having a porous structure inside, and a coating is coated on an inner surface of each pore channel, so that exhaust gas flows out of the pore channels in the LNT carrier after entering the LNT, and then the exhaust gas fully contacts with the coating on the inner surface of the pore channel in the process of flowing through the pore channel, and performs a corresponding reaction.
In the embodiment of the present invention, the porous substrate is divided into a front part and a rear part (as shown in fig. 3) according to the flow direction of the exhaust gas, and the inner surfaces of the pore channels of the front part are coated with the porous substrate for purifying NOXTo obtain a first coating; the inner surface of the pore canal of the rear part is coated with NO for storing NOXTo obtain a second coating.
The LNT carrier provided by the embodiment of the invention can purify NOXIs applied to the front part of the substrate to store NOXIs applied to the rear part of the substrate in such a way that the NO is reducedXCan be sufficiently used for NOXWithout being reduced by NOXAnd further to improve the effect on NOXOverall efficiency of purification with reduction.
In this embodiment, it is preferable that the constituent materials of the substrate include inert materials and additives; the additive is used to increase the specific surface area of the LNT carrier and to enhance the NO of said carrierXThe ability to adhere.
Wherein the additive increases the specific surface area of the substrate, thereby increasing the coating area of the coating layer, and further achieving the purpose of improving the specific surface area of the substrateThe purpose of increasing the specific surface area of the LNT support; moreover, the additive has strong NO adsorptionXSo that the NO of the LNT carrier can be enhanced using this additiveXThe ability to adhere.
In specific implementation, the inert substance comprises any one of ceramics, metals, silicon carbide and aluminum titanate; the additive may be alumina.
In this embodiment, preferably, the first coating layer includes a noble metal and an auxiliary; the promoter serves to increase the catalytic activity of the catalyst (i.e., the noble metal) in the first coating layer, to increase the high temperature stability of the first coating layer, and to increase the sulfur resistance of the first coating layer.
In specific implementation, the noble metal comprises at least one of Pt, Pd and Rh; the auxiliary agent may be zirconia.
In this embodiment, preferably, the first coating is applied to the first half of the substrate; the second coating is coated on the back half part of the substrate; the coating amount of the first coating layer and the coating amount of the second coating layer are determined according to the shape and size of the substrate.
In specific implementation, the substrate can be divided into two parts, namely a front part and a rear part, wherein the first coating is coated on the front half part of the substrate, and the second coating is coated on the rear half part of the substrate. Wherein the coating amount of the first coating layer and the coating amount of the first coating layer are determined according to the shape and size of the substrate, for example, for a cylindrical substrate (refer to a cylinder shown in fig. 3), the inside of the cylinder is a porous structure of a honeycomb structure, and then the coating amount of the noble metal in the first coating layer is determined according to the outer diameter and length of the cylinder and the requirement of the user.
In this embodiment, preferably, the second coating layer includes CeO2And BaCO3One or two of them.
In this embodiment, the structure of the substrate preferably comprises a honeycomb structure, as can be seen in fig. 3.
In practice, the shape of the substrate is consistent with the shape of the main body section 223 of the housing 22, so that the substrate can be seamlessly embedded in the housing 22, and thus the exhaust gas can only flow out of the pore channels of the substrate after flowing into the housing 22.
In this embodiment, preferably, the substrate is integrally formed; or the substrate consists of a first sub-substrate and a second sub-substrate which are placed in front of and behind each other; coating a first coating on a first submount; the second substrate is coated with a second coating.
In particular, in one aspect, the substrate in the embodiments of the present invention may be integrally formed, that is, an integral body, and then the first coating layer and the second coating layer are respectively coated on the front portion and the rear portion of the substrate; on the other hand, the substrate in the embodiment of the present invention may also be composed of two independent sub-substrates, which are referred to as a first sub-substrate and a second sub-substrate for convenience of description, the inner surface of the cell channel of the first sub-substrate is coated with the above-mentioned first coating layer and disposed at the front end of the body segment 223, and the inner surface of the cell channel of the second sub-substrate is coated with the above-mentioned second coating layer and disposed at the rear end of the body segment 223.
In order to make the LNT carrier in the embodiments of the present invention better understood by those skilled in the art, the LNT carrier in the embodiments of the present invention will be described below by way of specific examples for increasing NOXThe total efficiency of the purification.
The specific implementation process of this embodiment is as follows:
LNT carriers (for easy differentiation, called No. 1 carrier) were prepared using prior art: 1.33g of Pt, 1.33g of Pd, 1.33g of Rh, 2g of CeO2And 2g of BaCO3The mixed paint is prepared by uniformly mixing, and then the mixed paint is coated on the inner surfaces of the pore channels of a porous cylindrical substrate with the outer diameter of 152.4mm and the length of 101.6mm to obtain a No. 1 carrier.
LNT carriers in the examples of the invention were prepared (for ease of distinction, referred to as carrier No. 2): first, 1.33g of Pt, 1.33g of Pd and 1.33g of Rh were uniformly mixed to obtain a first coat paint, and 2g of CeO was added2And 2g of BaCO3Uniformly mixing to obtain a coating of a second coating; then, a porous cylindrical substrate having an outer diameter of 152.4mm and a length of 101.6mm was divided equally into front and rear portionsA first coating of washcoat was applied to the interior surfaces of the first 1/2 and second 1/2 channels of the LNT support (this method is referred to herein as "staged coating"), resulting in No. 2 support.
As is clear from the above-described methods for producing the carrier No. 1 and the carrier No. 2, in the examples of the present invention, the same raw materials were used, the same amounts of the respective raw materials were used, and the same substrates were used.
Step 2, installing the prepared carrier No. 1 and the carrier No. 2 in the same test vehicle for testing:
preparing two identical LNT shells and gaskets, and respectively installing a carrier No. 1 and a carrier No. 2 in each LNT to obtain two LNT; then, the LNT with No. 1 carrier was first installed in a test car, tested, and NO recordedXThe amount of emissions of (a), which test may be referred to as the first test; then, the LNT with No. 1 carrier was taken off, the LNT with No. 2 carrier was reinstalled in the test vehicle, the test was conducted again, and the NO at this time was recordedXThis test may be referred to as a second test. Finally, data statistics were performed and LNT D-NO was calculatedXThe overall efficiency of (c).
FIG. 4 shows NO for a test car in an embodiment of the present inventionXThe test result of emission amount of "LNT Pre-NO" in FIG. 4XThe "emission amount of" refers to NO in exhaust gas before entering LNTXThe emission content of (d); "LNT rear NOXThe "emission amount" of (b) means NO in the exhaust gas obtained after the exhaust gas passes through the LNT packed with the No. 1 carrierXThe emission content of (d); "post LNT NO after Using this patentXThe "emission amount" of (b) means NO in the exhaust gas obtained after the exhaust gas passes through the LNT packed with the No. 2 carrierXI.e. measured NO in the exhaust gas after LNT using LNT equipped with LNT carrier of the inventionXThe emission content of (a).
As shown in FIG. 4, a test vehicle (in this case, an LNT with a No. 1 carrier) of a test company LNT D-NO was tested according to the WLTC cycle test required in GB 18352.6-2016XThe overall efficiency of (c) is about 66.1%. LNT front-total (original row) NOX: 10.93g, LNT Total Process NOX: 7.22 g. The LNT replacement with No. 2 vehicle was then retested on this test vehicle, with LNT front total (raw) NOX: about 10.93g, LNT Total Process NOX: 8.49g LNT was treated at 77.9% on the WLTC cycle, reaching a good level.
According to the test results, the following test results are obtained: since the exhaust of the engine first flows through the LNT (as shown in FIG. 1), the more preferential first coat-passing washcoat coats the front 1/2 portion of the LNT support (as shown in FIG. 3), H2Under the action of Pt, Pd and Rh (especially Pt and Pd) to purify NO efficientlyXAs shown in formulas (5) and (6) above. Therefore, LNT D-NO can be achieved by using the LNT carrier of the inventionXThe total efficiency of the fuel reaches 77.9% (according to industry experience, LNT D-NO)XAn overall efficiency of > 75% may be referred to as good).
As can be seen from this embodiment of the invention, the invention applies Pt, Pd, Rh on the front of the LNT carrier by way of "step coating1/2Partially, adding CeO2、BaCO3After coating on LNT carrier1/2And (4) partial. The 'segmented coating' method enables the H in the gas discharged out of a combustion chamber of a light diesel engine during the rich combustion2More is applied to "H" than about 1.2%2D-NO ofX"; further, this "segmented coating" approach avoids "NOXStore "pair" H2D-NO ofX"of the composition.
The LNT carrier of the invention is Pt, Pd, Rh, CeO on the LNT carrier2、BaCO3On the premise that the amount of these substances is not changed, LNT D-NO can be realized only by the 'segmented coating' of the inventionXAn increase of at least 10% in capacity. That is, the use of the "staged coating" of the present invention allows the LNT to be NO-paired with the same amount of each substance, the same substrate, and the same operating meansXIs increased by at least 10%, and NO is generatedXThe purification effect of the method meets good requirements.
Wherein, the calculation formula of 10% is: ("LNT rear NO)XOf discharge amount ofTotal- "NO after LNT Using this patentXTotal of emission amount of)/"LNT rear NOXEmission amount of (c) ("total of emission amount ×%). "post LNT NO after Using this patentXTotal of discharge amount of (c) ": after using the LNT with Carrier No. 2, the NO measured every secondXThe amounts of emissions are added to obtain a total. LNT rear NOXTotal of discharge amount of (c) ": after using the LNT loaded with Carrier No. 1, the NO measured every secondXThe amounts of emissions are added to obtain a total.
Furthermore, the LNT carrier provided by the embodiment of the invention can effectively improve the D-NO of the LNTXCapacity, reduction of NOXThus, embodiments of the present invention provide LNT carriers that can be applied to all emissions containing NOXOf exhaust gas, in particular NOXLight diesel vehicles with high emission.
In a second aspect, the present invention provides a lean NOXTrap of the lean-burn NOXThe trap sequentially comprises a shell, a liner and the LNT carrier from outside to inside.
In a third aspect, the present invention provides a vehicle fitted with a lean burn NO engine as described in the second aspectXA trap for automobiles.
For simplicity of explanation, the method embodiments are described as a series of acts or combinations, but those skilled in the art will appreciate that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are preferred embodiments and that the acts and elements referred to are not necessarily required to practice the invention.
The LNT carrier and the lean-burn NO provided by the inventionXThe trap and the automobile are described in detail, and the principle and the implementation mode of the invention are explained by applying specific examples, and the description of the above examples is only used for helping to understand the method and the core idea of the invention; also, for one of ordinary skill in the art, according toThe idea of the present invention can be changed in the specific embodiments and the application range, and in summary, the content of the present specification should not be construed as limiting the present invention.
Claims (10)
1. An LNT support, comprising: a substrate and a coating; the substrate is divided into a front part and a rear part, and the coating comprises a first coating and a second coating;
wherein the first coating is applied to a front portion of the substrate and the second coating is applied to a rear portion of the substrate;
the first coating is for NO in LNTXPurifying;
the second coating is for NO in LNTXStorage and release of.
2. The LNT carrier of claim 1, wherein the substrate constituent materials comprise inerts and additives;
the inert substance comprises any one of ceramics, metal, silicon carbide and aluminum titanate;
the additive is used for increasing the specific surface area of the carrier and enhancing NO of the carrierXThe ability to adhere.
3. The LNT support of claim 1, wherein the first coating comprises a noble metal;
the noble metal comprises at least one of Pt, Pd and Rh.
4. The LNT support of claim 1, wherein the first coating is coated on the first half of the substrate; the second coating is coated on the back half part of the substrate;
the coating amount of the first coating layer and the coating amount of the second coating layer are determined according to the shape and the size of the substrate.
5. The LNT carrier of claim 1, wherein the LNT carrier is characterized byThe second coating layer comprises CeO2And BaCO3One or two of them.
6. LNT support according to claim 1, wherein the structure of the substrate comprises a honeycomb structure.
7. The LNT carrier of claim 1, wherein the substrate is integrally formed.
8. The LNT support of claim 1, wherein the substrate consists of a first sub-substrate and a second sub-substrate, the first sub-substrate and the second sub-substrate being positioned one behind the other;
coating the first sub-substrate with the first coating;
the second sub-substrate is coated with the second coating layer.
9. Lean burn NOXTrap, characterized in that said lean NOXThe trap comprises, in order from the outside to the inside, a shell, a liner and an LNT carrier according to any one of the preceding claims 1-8.
10. An automobile equipped with the lean burn NO of claim 9XA trap for automobiles.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106163641A (en) * | 2014-04-01 | 2016-11-23 | 庄信万丰股份有限公司 | There is NOxthe diesel oxidation catalyst of adsorbent activity |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106163641A (en) * | 2014-04-01 | 2016-11-23 | 庄信万丰股份有限公司 | There is NOxthe diesel oxidation catalyst of adsorbent activity |
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