CN216306055U

CN216306055U - LNT desulphurization unit

Info

Publication number: CN216306055U
Application number: CN202121930836.3U
Authority: CN
Inventors: 赵振兴
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2021-08-17
Filing date: 2021-08-17
Publication date: 2022-04-15
Anticipated expiration: 2031-08-17

Abstract

The present disclosure relates to an LNT desulfurization device comprising a housing (3) and a support (4) disposed within the housing (3), the support (4) comprising an inert matrix and first (1) and second (2) material segments supported on the inert matrix; the first material section is located upstream of the second material section in the gas flow direction; the first material segment (1) comprises a NOx storage material area, a first precious metal material area and a transition metal material area; the second material segment (2) comprises a rare earth oxide material region (10). The device can generate in the device at lower temperatureBaSO of₄The desulfurization is carried out, and the treatment efficiency of the device is improved; avoiding additional desulfation modes to reduce vehicle fuel consumption; can also catalyze the conversion of NO to NO₂To facilitate trapping of more NO in the NOx storage material region₂Thereby improving the nitrogen oxide treatment effect of the whole device.

Description

LNT desulphurization unit

Technical Field

The disclosure relates to the field of motor vehicle exhaust treatment, in particular to an LNT desulfurization device.

Background

By interpreting light-duty diesel vehicle (LDD) emissions regulations, it can be found that the NOx emission limit is reduced by 82.1% from the upgrade of 5(CN V) to 6b (CN VIb), and the NOx emission shows a stricter trend.

Aiming at light diesel vehicle pair in industryLNT device (lean NO) is widely applied in the main after-treatment arrangement treatment mode of the emission route of the national VI emission regulations_XTrapping technique, lean NO_Xtrap), DPF devices (Diesel Particulate Filter), SDPF devices (DPF with SCR functionality) and SCR devices (Selective catalytic reduction).

There is a very important substance "BaO" within the LNT. However, this substance reacts with sulfur (S) in the fuel oil to produce BaSO₄(sulfur poisoning), in turn, creates three industry "pain spots":

1：BaSO₄this substance corresponds to the barrier to the storage and release of NO by BaO_XThe function of (a);

2：BaSO₄not only is the function of the LNT damaged, but also the deposition of Pt on nearby Pt in the LNT causes more serious effects;

3: when LNT technology is actually researched and applied, the 'desulfurization' has a relatively strict requirement on the working condition of the engine, and some engine operating conditions are even not suitable for desulfurization, so that the desulfurization mode (D-SOx mode) can be repeatedly entered and exited, and the desulfurization effect is poor. Multiple desulfations are unsuccessful and the vehicle reports a trouble code on the dashboard, causing customer complaints and concerns. And each time of 'successful desulfurization' needs about 20 minutes, at least 1L of fuel is consumed, and the fuel consumption of the vehicle is increased. Thus, "sulfur poisoning" is an unresolved problem with LNTs.

SUMMERY OF THE UTILITY MODEL

It is an object of the present disclosure to provide an LNT desulfurization device that can treat BaSO generated in the device at a relatively low temperature₄The desulfurization is carried out, the treatment efficiency of the device is improved, and the oil consumption of the vehicle can be reduced.

In order to achieve the above object, the present disclosure provides an LNT desulfurization device including a housing and a support disposed within the housing, the support including an inert substrate and first and second material segments supported on the inert substrate; the first material segment is upstream of the second material segment in the gas flow direction; the first material segment includes a first noble metal material region and a NOx storage material region; the second material segment includes a rare earth oxide material region.

Optionally, the first material segment further comprises a transition metal material region.

Optionally, the first noble metal material region comprises one or more Pt particles; two adjacent Pt particles of the plurality of Pt particles are in contact or not in contact;

the NOx storage material region includes one or more BaO particles; two adjacent BaO particles of the plurality of BaO particles are in contact or not in contact;

the transition metal material region comprises one or more Co particles; adjacent two of said Co particles in said plurality of Co particles may or may not be in contact.

Optionally, the first material segment comprises a plurality of the first precious metal material regions, a plurality of the NOx storage material regions and a plurality of the transition metal material regions, wherein any two adjacent regions are in contact with each other or not.

Optionally, the second material segment further comprises a second noble metal material region and a rare earth metal material region.

Optionally, the rare earth oxide material region comprises one or more rare earth oxide particles; adjacent two of the rare earth oxide particles in the plurality of rare earth oxide particles are in contact or not in contact; the rare earth metal oxide particles comprise CeO₂Particles;

the second noble metal material region comprises one or more second noble metal particles; adjacent two of the second noble metal particles in the plurality of second noble metal particles are in contact or not in contact; the second noble metal particles comprise one or more of Pd particles, Pt particles, and Rh particles;

the rare earth metal material region comprises one or more rare earth metal particles; adjacent two of the rare earth metal particles in the plurality of rare earth metal particles are in contact or not in contact; the rare earth metal particles comprise Ce particles.

Optionally, the rare earth metal oxide particles are CeO₂And the rare earth metal particles are Ce particles, and the second noble metal particles are Pd particles.

Optionally, the second material segment comprises a plurality of the rare earth oxide material regions, a plurality of the second noble metal material regions and a plurality of the rare earth material regions, wherein any two adjacent regions are in contact or not in contact with each other.

Optionally, the length ratio of the first material section to the second material section in the gas flow direction is 0.8-1.2: 1.

optionally, a first gas inlet and a first gas outlet are respectively arranged at two ends of the shell; a second gas inlet and a second gas outlet are respectively formed in the two ends of the carrier along the axial direction; the first gas inlet and the second gas inlet are correspondingly arranged, and the first gas outlet and the second gas outlet are correspondingly arranged; the carrier and the housing are coaxially arranged; a plurality of pore channels extending along the gas flow direction are formed in the inert matrix; the inlets of all the cell channels are formed as the second gas inlets, and the outlets of all the cell channels are formed as the second gas outlets; the first material section and the second material section are respectively covered on the inner wall of the pore channel; the inert matrix is one or more of an alumina matrix, a ceramic matrix, a metal matrix, a silicon carbide matrix and an aluminum titanate matrix.

Through the technical scheme, the LNT desulphurization device comprises a first material section and a second material section which are arranged in a partitioning mode, wherein the first material section is arranged on the upstream of the second material section, and a NOx storage material area is arranged in the first material section, so that BaSO generated in the first material section in the rich combustion state of a vehicle is facilitated₄Desulfurization is carried out, and the sulfur is reduced into BaO, so that the treatment efficiency of the LNT is improved; the present disclosure also provides a first noble metal material region in the first material segment that can catalyze the conversion of NO to NO₂To facilitate trapping of more NO in the NOx storage material region₂The nitrogen oxide treatment effect of the whole device is improved; the desulfurization can be realized under the normal state of the engine, the additional arrangement of a desulfurization model is avoided, and the oil consumption of the vehicle is reduced.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is a schematic diagram of a structure of a substrate of an LNT desulfurization device provided by the present disclosure;

FIG. 2 is a schematic diagram of an apparatus configuration for an LNT desulfation apparatus provided by the present disclosure;

FIG. 3 is a schematic diagram of a structure of a support of an LNT desulfurization device provided by the present disclosure.

Description of the reference numerals

1-a first material section, 2-a second material section, 3-a shell, 4-a carrier, 5-a pore channel, 6-a cushion layer, 7-a first precious metal material region, 8-a NOx storage material region, 9-a transition metal material region, 10-a rare earth metal oxide material region, 11-a second precious metal material region, 12-a rare earth metal material region, Q-a gas to be treated (tail gas), Q' -LNT treated gas;

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

In the present disclosure, unless otherwise specified, the terms "first", "second", and the like are used only for distinguishing different members and do not have actual meanings such as the order of connection before and after the present disclosure. In the present disclosure, the use of directional words such as "upper" and "lower" are upper and lower in the normal use state of the device, and "inner" and "outer" are in terms of the outline of the device.

As shown in fig. 1, the present disclosure provides an LNT desulfurization device including a housing 3 and a support 4 disposed within the housing 3, the support 4 including an inert substrate and first and

second material segments

1 and 2 supported on the inert substrate; in the gas flow direction, the first material section 1 is located upstream of the second material section 2; the first material segment 1 includes a first noble metal material region 7 and a NOx storage material region 8; the second material segment 2 includes a rare earth oxide material region 10.

The disclosure provides an LNT desulfurization device that includes first and second material segments arranged in zones, with the first material segment being disposed upstream of the second material segment, and with a NOx storage material zone in the first material segment, to facilitate combustion of BaSO generated in the first material segment under rich conditions of the vehicle₄Desulfurization is carried out, and the sulfur is reduced into BaO, so that the treatment efficiency of the LNT is improved; the present disclosure also provides a first noble metal material region in the first material segment that can catalyze the conversion of NO to NO₂To facilitate trapping of more NO in the NOx storage material region₂The nitrogen oxide treatment effect of the whole device is improved; the desulfurization can be realized under the normal state of the engine, the additional arrangement of a desulfurization model is avoided, and the oil consumption of the vehicle is reduced.

In a preferred embodiment, as shown in fig. 1, the first material section 1 further comprises a transition metal material region 9. In this embodiment, a transition metal material region is provided in the first material segment, and the transition metal material may reduce BaSO generated in the NOx storage material region of the LNT₄The desulfurization temperature is further increased.

In one embodiment, the first noble metal material region 7 comprises one or more Pt particles; adjacent two Pt particles of the plurality of Pt particles are in contact or not in contact;

the NOx storage material region 8 includes one or more BaO particles; two adjacent BaO particles in the plurality of BaO particles are in contact or not in contact;

the transition metal material region 9 comprises one or more Co particles; adjacent two of the plurality of Co particles may or may not be in contact.

The inventor of the present disclosure has the following findings in research:

the method comprises the following steps that (I) in the running process of a vehicle, the working condition that the internal temperature of an LNT reaches more than 400 ℃ can account for about 1/4 of the running working condition of the vehicle, and when the working condition that the internal temperature of the LNT is more than or equal to 400 ℃, the corresponding working condition of a vehicle engine is rich combustion, and at the moment, the engine can release substances containing CO (carbon monoxide) and C (carbon monoxide)PM particles) to be treated, which is more favorable for making BaSO when entering LNT for treatment₄Reduction to BaO (BaSO)₄→ BaO) as shown in the following formulas (1) to (3):

2BaSO₄+3C→Ba₂O+2SO₂+3CO (1)

BaSO₄+2C→Ba+SO₂+2CO (2)

BaSO₄+2CO→Ba+SO₂+2CO₂ (3)。

(II) the BaO particles are arranged in the first material section at the upstream, so that the BaSO generated can be₄The first material segment is contacted with CO gas and sufficiently reduced to BaO to avoid the consumption of CO after contacting with other noble metals in the LNT, so that the residual CO is not enough to make BaSO₄Is sufficiently reduced to BaO.

(III) Co particles are arranged near BaO particles, so that BaSO which can be carried out only by needing higher temperature (above 650℃)₄The temperature of the reduction reaction of → BaO "is performed at a lower temperature (about 300 ℃), which lowers the temperature required for desulfurization and is more favorable for the LNT to realize the functions of storing and releasing nitrogen oxides. And when the vehicle is in operation, the working condition that the internal temperature of the LNT reaches over 300 ℃ can account for about 1/2 of the operating condition of the vehicle, which is also named as BaSO₄The reduction reaction → BaO "provides more favorable conditions.

Wherein engine-out NO_X(mainly NO)₂) Stored in the LNT by BaO particles, a reaction process known as NO_XAnd (5) storing. The storage of NOx occurs during lean conditions of the engine.

NO_XThe storage reaction is represented by the following formula (4):

BaO+2NO₂+1/2O₂→Ba(NO₃)₂ (4)

NO_Xrelease reaction (also known as NO)_XDesorption), decomposition of nitrate to release NOx mainly occurs in the engine rich state as shown in the following formulas (5) to (7):

Ba(NO₃)₂+CO₂→BaCO₃+3NO₂+1/2O₂ (5)

Ba(NO₃)₂+3H₂+CO₂→BaCO₃+2NO+2CO₂ (6)

Ba(NO₃)₂+1/3C₃H₆→BaCO₃+2NO+H₂O (7)。

CO involved in the reactions of the above formulae (2) to (4)₂、H₂And C₃H₆From the exhaust gases of the engine.

S in the fuel reacts with oxygen as shown in the following formula (8):

S+O₂→SO₂ (8)

BaO particles and SO formed₂The reaction proceeds "sulfur poisoning" as shown in the following formula (9):

BaO+1/2O₂+SO₂→BaSO₄ (9)。

(IV) the present disclosure co-locates Pt particles in the upstream first material segment with BaO particles, the Pt particles contributing to the conversion of NO in the exhaust gas to be treated to NO₂So that the tail gas to be treated contains more NO₂Is beneficial to the BaO particles to capture NO in the tail gas to be treated₂The inventors of the present disclosure found that this effect cannot be achieved when Pt particles are disposed in the downstream second material segment.

In the present disclosure, "rich" and "lean" of the engine mean respectively:

"lean burn" refers to combustion of the engine when the actual air-fuel ratio is greater than the theoretical air-fuel ratio (i.e. air is excessive and sufficient combustion of fuel can be achieved), and the fuel is completely combusted to produce CO₂More are.

The term "rich combustion" refers to combustion under the condition that the actual air-fuel ratio is less than the theoretical air-fuel ratio (i.e. air is not enough to fully combust fuel), the fuel combustion is incomplete, and more CO and HC are generated, wherein CH refers to the abbreviation of harmful gas hydrocarbon in the automobile exhaust.

"theoretical air-fuel ratio" refers to the stoichiometric ratio of the mass of air required for complete combustion of one kilogram of fuel, the theoretical air-fuel ratios of the various fuels being different: the gasoline is 14.7 and the diesel is 14.3.

In a preferred embodiment, the first material segment 1 comprises a plurality of first precious metal material regions 7, a plurality of NOx storage material regions 8 and a plurality of transition metal material regions 9, any two of which are adjacent to each other with or without contact.

Specifically, the first material segment in the present disclosure includes three material regions, each of which can be formed by coating using an array coater conventionally selected in the art, specifically, a plurality of first noble metal material regions are formed by first coating Pt particles on the surface of an inert substrate using an array coater; then coating BaO particles to form a plurality of NOx storage material areas; finally, the Co particles are coated to form a plurality of transition metal material regions. The coating sequence can also be adjusted by the person skilled in the art according to the actual circumstances. The description will be made taking the NOx storage material region as an example: a plurality of NOx storage material regions are contained in the first material segment, and one or more BaO particles are contained in each NOx storage material region, and the BaO particles are randomly and randomly arranged on the surface of the inert substrate due to the coating characteristics of the coater, so that when a plurality of BaO particles are contained in each NOx storage material region, every two BaO particles may be coated to be in contact or not. The first noble metal material region and the transition metal material region contain particles arranged in a manner similar to that of the NOx storage material region. The end result is that any two material regions of the plurality of first noble metal material regions, the plurality of NOx storage material regions and the plurality of transition metal material regions formed by coating may be in contact or not (the coating process is randomly determined) so that the Pt particles, BaO particles and Co particles are randomly dispersed on the surface of the inert substrate in the region of the first material segment with the particles as the smallest units.

The different shapes shown in fig. 1 are only used to distinguish between different material regions and are not intended to limit the shape of a material region and the particular shape of the particles it contains; and only two adjacent material areas are shown in contact with each other in fig. 1, it should be understood that there may be instances where two material areas do not contact when actually coated (not specifically shown in fig. 1).

In a preferred embodiment, as shown in fig. 1, the second material segment 2 further comprises a second noble metal material region 11 and a rare earth metal material region 12.

In one embodiment, the rare earth oxide material region 10 includes one or more rare earth oxide particles; adjacent two rare earth oxide particles of the plurality of rare earth oxide particles are in contact or not in contact; the rare earth metal oxide particles comprising CeO₂Particles;

the second noble metal material region 11 comprises one or more second noble metal particles; adjacent two of the plurality of second noble metal particles are in contact or not in contact; the second noble metal particles comprise one or more of Pd particles, Pt particles, and Rh particles;

the rare earth material region 12 includes one or more rare earth particles; adjacent two rare earth metal particles in the plurality of rare earth metal particles are in contact or not in contact; the rare earth metal particles comprise Ce particles.

In accordance with the present disclosure, of the rare earth metal oxide particles, CeO₂The particles refer to ceria particles.

In the second noble metal particles according to the present disclosure, the Pd particles refer to palladium particles, the Pt particles refer to platinum particles, and the Rh particles refer to rhodium particles.

In a preferred embodiment, the rare earth metal oxide particles are CeO₂The particles, the rare earth metal particles are Ce particles, and the second noble metal particles are Pd particles. The disclosure provides Ce particles, Pd particles, and CeO in the second material segment₂Particles of Ce and CeO₂The particles effectively improve the catalytic activity of the Pd particles, and improve the high-temperature stability and the sulfur resistance.

In one embodiment, the second material segment 2 comprises a plurality of regions of rare earth metal oxide material 10, a plurality of regions of second noble metal material 11, and a plurality of regions of rare earth metal material 12, wherein any two adjacent regions are in contact with each other or not.

Specifically, similar to the arrangement of the first material segments, the second material segments of the present disclosure also include three material regions, each of which can be formed by coating using an array coater conventionally selected in the art, for example, an array coater. The second noble metal material region and the second noble metal material region including Pd particles are exemplified as follows: the second material segment contains a plurality of second noble metal material areas, each second noble metal material area contains one or more Pd particles, and due to the coating characteristic of the coating machine, the Pd particles are randomly and randomly arranged on the surface of the inert matrix, so that when a plurality of Pd particles are arranged in each second noble metal material area, every two Pd particles can be coated to be in contact or not. The rare earth oxide material region and the rare earth metal material region contain particles arranged in a manner similar to the second noble metal material region. The final result is that any two material areas of the plurality of second noble metal material areas, the plurality of rare earth metal oxide material areas and the plurality of rare earth metal material areas formed by coating can be contacted or not contacted (the coating process is randomly determined), so that in the area of the second material section, the rare earth metal oxide particles, the rare earth metal particles and the second noble metal particles are randomly dispersed and arranged on the surface of the inert matrix by taking the particles as the minimum unit. The different shapes shown in fig. 1 are only used to distinguish between different material regions and are not intended to limit the specific shape of a material region and the specific shape of the particles it contains; and only the manner in which the second noble metal material region, the rare earth metal oxide material region, and the plurality of rare earth metal material regions are disposed in contact is shown in fig. 1, it is to be understood that a case in which two material regions have a gap therebetween (not specifically shown in fig. 1) may also occur at the time of actual coating.

In the present disclosure, rare earth metal oxide particles (CeO) are provided in the second material segment₂The specific process of treating the gas to be treated by the particles), the second noble metal particles (Pd particles) and the rare earth metal particles (Ce particles) comprises:

the tail gas treated by the first material section flows through the second material section, and is in the form of Pd particles, Ce particles and CeO₂The NOx in the tail gas is catalyzed by the particles to react with CO, CH and H₂React to generate N₂、CO₂And H₂O。

In one embodiment, the length ratio of the first material section 1 to the second material section 2 along the gas flow direction is 0.8-1.2: 1; in a preferred embodiment, the length ratio of the first material section 1 to the second material section 2 in the gas flow direction is 1: 1.

In one embodiment, as shown in fig. 2 and 3, the housing 3 is provided with a first gas inlet and a first gas outlet at two ends thereof; a second gas inlet and a second gas outlet are respectively arranged at two ends of the carrier 4 along the axial direction; the first gas inlet and the second gas inlet are correspondingly arranged, and the first gas outlet and the second gas outlet are correspondingly arranged; the carrier 4 and the housing 3 are coaxially arranged;

a plurality of pore channels 5 extending along the gas flow direction are formed in the inert matrix; the inlets of all the cell channels 5 are formed as second gas inlets, and the outlets of all the cell channels 5 are formed as second gas outlets; the first material section 1 and the second material section 2 are respectively covered on the inner wall of the pore canal 5; the inert matrix is one or more of an alumina matrix, a ceramic matrix, a metal matrix, a silicon carbide matrix and an aluminum titanate matrix. The inert matrix adopted by the disclosure can provide higher specific surface area and enhance NO_XThe ability to adhere.

Specifically, in the present embodiment, the first material segment 1 may be formed by applying the first noble metal material region 7, the NOx storage material region 8, and the transition metal material region 9 in an array on the inner wall upstream of each cell, respectively, using an array coater; similarly, a second material segment 2 is formed by the matrix coating of a zone 10 of rare earth oxide material, a zone 11 of a second noble metal material and a zone 12 of rare earth metal material on the inner wall downstream of each cell.

In one embodiment, as shown in fig. 2, the device further comprises a cushion 6, the cushion 6 being arranged between the outer wall of the carrier 4 and the inner wall of the housing 3. The bed course can play the leakproofness of assurance and shock attenuation guard action.

As shown in fig. 2, in an alternative embodiment, the housing 3 includes a first connecting pipe section, a first expanding section, a main body section, a second expanding section and a second connecting pipe section in this order from one end to the other end in the axial direction (extending direction), the carrier 4 is located in the main body section, the first expanding section and the second expanding section are formed such that the inner diameters thereof gradually increase from one end to the other end, and the ends of the first expanding section and the second expanding section, which have the larger inner diameters, are both directed toward the main body section, so that the main body section has the respective large inner diameters, i.e., the larger inner spaces, to accommodate the carrier 4, enabling the gas flow flowing through the main body section to be more sufficiently attached, trapped and reacted therein.

The present disclosure will be further explained and illustrated with reference to examples.

Example 1

Referring to fig. 1 to 3, the present embodiment provides an LNT desulfurization device including a housing 3 and a carrier 4 disposed inside the housing 3, and a gasket 6 is further disposed between an outer wall of the carrier 4 and an inner wall of the housing 3. Wherein the carrier 4 comprises an inert matrix and a first material segment 1 and a second material segment 2 loaded on the inert matrix; in the gas flow direction, the first material section 1 is located upstream of the second material section 2; the first material segment 1 includes a first noble metal material region 7 (containing Pt particles), a NOx storage material region 8 (containing BaO particles), and a transition metal material region 9 (containing Co particles), and the Pt particles, BaO particles, and Co particles are coated on the surface of the inert base of the support 4 in a randomly dispersed form to form the first material segment 1.

The second material segment 2 includes a rare earth metal oxide material region 10, a second noble metal material region 11, and a rare earth metal material region 12, and rare earth metal oxide particles (CeO)₂Particles), second noble metal particles (Pd particles) and rare earth metal particles (Ce particles) are coated in a randomly dispersed form on an inert matrix of a support 4 to form second material segments 2. Wherein the length ratio of the first material section 1 to the second material section 2 in the gas flow direction is 1: 1.

A first gas inlet and a first gas outlet are respectively arranged at two ends of the shell 3; a second gas inlet and a second gas outlet are respectively arranged at two ends of the carrier 4 along the axial direction; the first gas inlet and the second gas inlet are correspondingly arranged, and the first gas outlet and the second gas outlet are correspondingly arranged; the carrier 4 and the housing 3 are arranged coaxially. A plurality of pore channels 5 extending along the gas flow direction are formed in the inert matrix; the inlets of all the cell channels 5 are formed as second gas inlets, and the outlets of all the cell channels 5 are formed as second gas outlets; the first material section 1 and the second material section 2 are respectively coated on the inner wall of the pore canal 5, wherein the material of the inert matrix comprises alumina.

The operating principle of the LNT desulfurization device provided in this embodiment includes:

(1) exhaust gas Q (containing CO) to be treated generated by combustion of engine fuel oil in lean combustion state₂、 NOx、SO₂Etc.) the exhaust gas enters the housing via the first gas inlet on the housing 3 of the LNT desulfurization device and then enters each of the channels 5 via the inlet of each of the channels 5 of the support 4, respectively; flowing first through the upstream first material section in each cell channel 5, BaO particles on the inner wall of the cell channel 5 adsorb NO₂Then the nitrate is adsorbed on the surface of the first material section of the pore channel, and the Pt particles in the first material section can effectively trap NO in the tail gas and catalyze the reaction of NO and oxygen to convert NO into NO₂Increase NO in exhaust gas₂In an amount more favorable for trapping and adsorbing NO₂(ii) a Part of SO in the tail gas in the process₂Also reacts with BaO particles to generate BaSO₄Resulting in "sulfur poisoning", reducing the efficiency of the process; the tail gas treated by the first material section continuously flows through the second material section, and the tail gas contains less CO, CH and H under the lean combustion state₂The Pd particles in the second material segment can catalyze NOx and CO, CH and H in the tail gas₂Reaction takes place, Ce and CeO₂Can improve the catalytic activity and high-temperature stability of Pd particles and generate N₂、CO₂And H₂O, the tail gas Q' treated by the second material section flows out of the LNT desulfurization device through the outlet of the pore passage and flows out of the LNT desulfurization device through the first gas outlet of the shell 3 to enter a subsequent treatment device;

(2) in a rich combustion state of the engine, the to-be-treated exhaust gas Q (containing more C, CO, CH, and the like) generated by combustion enters the housing through the first gas inlet on the LNT desulfurization device housing 3, and then enters each pore channel 5 through the inlet of each pore channel 5 of the carrier 4; first of all, in each cell channel 5, flows through the upstream first material section, with the BaSO generated on the inner wall of the cell channel 5 as a result of "sulphur poisoning₄Can be reduced into BaO particles under the action of CO and C in the tail gas, and the process can be heated in the LNT at the internal temperature due to the Co in the first material sectionThe reduction reaction can be carried out when the temperature reaches 300 ℃; nitrate generated in the first material section in a lean combustion state can be decomposed under the action of CO and CH to release NOx, so that desorption of nitrogen oxide is realized; the gas treated by the first material section continuously flows through the second material section, and Pd particles, Ce particles and CeO in the pore channel₂The NOx in the tail gas is catalyzed by the particles to react with CO, CH and H₂React to generate N₂、 CO₂And H₂O; the tail gas Q' treated by the second material section flows out through the outlet of the duct and flows out of the LNT desulfurization device through the first gas outlet of the housing 3 to enter the subsequent treatment device.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. LNT desulfurization device comprising a housing (3) and a support (4) arranged inside said housing (3), characterized in that said support (4) comprises an inert matrix and a first (1) and a second (2) material section supported on said inert matrix; -the first material section (1) is located upstream of the second material section (2) in the gas flow direction; the first material section (1) comprises a first precious metal material region (7) and a NOx storage material region (8); the second material segment (2) comprises a rare earth oxide material region (10).

2. The device according to claim 1, wherein the first material section (1) further comprises a transition metal material zone (9).

3. The device according to claim 2, wherein the first zone (7) of noble metal material comprises one or more particles of platinum; two adjacent ones of said platinum particles in said plurality of platinum particles are in contact or not in contact;

the NOx storage material region (8) includes one or more BaO particles; two adjacent BaO particles of the plurality of BaO particles are in contact or not in contact;

the transition metal material region (9) comprises one or more Co particles; adjacent two of said Co particles in said plurality of Co particles may or may not be in contact.

4. The arrangement according to claim 2 or 3, characterized in that a plurality of said first noble metal material zones (7), a plurality of said NOx storage material zones (8) and a plurality of said transition metal material zones (9) are comprised in said first material section (1), any two of them being in contact or not with each other.

5. The device according to claim 1, characterized in that the second material section (2) further comprises a second zone of noble metal material (11) and a zone of rare earth metal material (12).

6. The device according to claim 5, wherein the rare earth oxide material region (10) comprises one or more rare earth oxide particles; adjacent two of the rare earth oxide particles in the plurality of rare earth oxide particles are in contact or not in contact; the rare earth metal oxide particles comprise ceria particles;

the second noble metal material region (11) comprises one or more second noble metal particles; adjacent two of the second noble metal particles in the plurality of second noble metal particles are in contact or not in contact; the second noble metal particles comprise one of palladium particles, platinum particles, and rhodium particles;

the rare earth material region (12) comprises one or more rare earth particles; adjacent two of the rare earth metal particles in the plurality of rare earth metal particles are in contact or not in contact; the rare earth metal particles comprise Ce particles.

7. The device of claim 6, wherein the rare earth oxide particles are ceria particles, the rare earth particles are Ce particles, and the second noble metal particles are palladium particles.

8. The device according to claim 6 or 7, characterized in that a plurality of said rare earth oxide material regions (10), a plurality of said second noble metal material regions (11) and a plurality of said rare earth material regions (12) are comprised in said second material section (2), any two of them being in contact or not with each other.

9. The device according to claim 1, wherein the length ratio of the first material section (1) to the second material section (2) in the gas flow direction is 0.8-1.2: 1.

10. The device according to claim 1, characterized in that the housing (3) is provided at both ends with a first gas inlet and a first gas outlet, respectively; a second gas inlet and a second gas outlet are respectively formed at two ends of the carrier (4) along the axial direction; the first gas inlet and the second gas inlet are correspondingly arranged, and the first gas outlet and the second gas outlet are correspondingly arranged; the carrier (4) and the shell (3) are coaxially arranged;

a plurality of pore channels (5) extending along the gas flow direction are formed in the inert matrix; the inlets of all the cell channels (5) are formed as the second gas inlets, and the outlets of all the cell channels (5) are formed as the second gas outlets; the first material section (1) and the second material section (2) are respectively covered on the inner wall of the pore canal (5);

the inert matrix is one of an alumina matrix, a metal matrix, a silicon carbide matrix and an aluminum titanate matrix.