Aftertreatment system for an engine and vehicle

Abstract

This invention discloses an aftertreatment system for an engine and a vehicle. The aftertreatment system includes: a first module connected to the engine's exhaust pipe for oxidizing NO in the exhaust pipe to NOx and reforming CO to H2; and a second module connected to the engine's exhaust pipe, which utilizes the H2 generated by the first module to convert NOx into NH3. According to the aftertreatment system of this invention, the first module reforms CO to H2 under rich combustion conditions, and the second module generates NH3 under rich combustion conditions, which improves the selectivity of the conversion to NH3 and allows for the production of more NH3. Furthermore, it utilizes unconverted THC and CO from rich combustion, avoiding waste of CO reducing agent.

Description

Technical Field

[0001] This invention relates to the field of vehicle exhaust treatment technology, and in particular to an aftertreatment system for an engine and a vehicle. Background Technology

[0002] Under rich combustion and stoichiometric conditions, a three-way catalytic converter (TWC) can utilize THC and CO in engine exhaust to convert NOx into N2. However, under lean combustion conditions, the higher oxygen concentration in engine exhaust makes it difficult for TWC to reduce NOx to N2. In related technologies, combining a TWC module with a selective catalytic reduction (SCR) module can effectively eliminate nitrogen oxides (NOx) produced by the engine under lean combustion conditions. Under rich combustion conditions, in the system composed of TWC and SCR, TWC can reduce NOx in engine exhaust to NH3 and store it in the SCR. When switching to lean combustion conditions, the NOx that TWC cannot convert will react with the pre-stored NH3 in the SCR to achieve effective NOx removal under lean combustion conditions.

[0003] However, the above system still has some problems. First, under rich combustion conditions, the oxygen concentration in the engine exhaust is low, and TWC has difficulty handling the residual THC and CO after reacting with NOx to form NH3. An additional oxidant source is needed to convert THC and CO under rich combustion conditions. Second, the selectivity of TWC in reducing NOx to NH3 under rich combustion conditions needs to be improved. At the same time, the NOx concentration in the engine exhaust under rich and lean combustion conditions will determine the operating time under rich and lean combustion conditions. The proportion of lean combustion operating time is not high enough, and the fuel economy advantage is not obvious. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes an aftertreatment system for an engine that can improve the selectivity of conversion to NH3 and increase the ammonia production under rich combustion conditions.

[0005] The present invention also proposes a vehicle comprising the above-described aftertreatment system for an engine.

[0006] An aftertreatment system for an engine according to an embodiment of the present invention includes: a first module disposed in the exhaust pipe of the engine, for at least oxidizing NO in the exhaust pipe to NOx, and reforming THC and CO into H2; and a second module disposed in the exhaust pipe of the engine, wherein the second module utilizes at least the H2 generated by the first module to convert NOx into NH3.

[0007] According to an embodiment of the present invention, an aftertreatment system for an engine, by providing a first module and a second module, wherein the first module oxidizes NO to NOx under lean-burn conditions and reforms CO to H2 under rich-burn conditions, and the second module generates NH3 under rich-burn conditions, the selectivity of the conversion to NH3 can be improved, and more NH3 can be generated. Furthermore, by utilizing unconverted THC and CO from rich-burn conditions, waste of CO reducing agent is avoided.

[0008] According to some embodiments of the present invention, the catalytic material of the first module is a non-precious metal material.

[0009] According to some embodiments of the present invention, the catalytic material of the first module is a transition metal and / or its oxide supported on a rare earth element oxide.

[0010] According to some embodiments of the present invention, the catalytic material of the first module is one or more of Ni / CeO2, Ni / La2O3, Co / CeO2, and Co / La2O3.

[0011] According to some embodiments of the present invention, the ammonia-producing material of the second module is a Pd-based catalyst.

[0012] According to some embodiments of the present invention, it further includes: a third module disposed in the exhaust pipe of the engine, the third module being used to at least adsorb nitrogen oxides.

[0013] According to some embodiments of the present invention, the third module is connected downstream of the first module, and the second module is connected downstream of the third module.

[0014] According to some embodiments of the present invention, the adsorption material of the third module is a K-based adsorbent or a Pt-based adsorbent.

[0015] According to some embodiments of the present invention, the system further includes: a particulate filter connected to the exhaust pipe and located downstream of the first module and the second module for filtering particles in the exhaust pipe, and / or a selective catalytic reduction module disposed in the exhaust pipe of the engine, the selective catalytic reduction module being used to store NH3.

[0016] According to some embodiments of the present invention, CO is reformed into H2 through a water-gas transformation reaction.

[0017] The vehicle according to an embodiment of the present invention includes the above-described aftertreatment system for the engine.

[0018] According to an embodiment of the present invention, the vehicle, by providing the above-described aftertreatment system for the engine, includes a first module and a second module. The first module oxidizes NO to NOx under lean-burn conditions and reforms CO to H2 under rich-burn conditions. The second module generates NH3 under rich-burn conditions, thereby improving the selectivity of the conversion to NH3 and producing more NH3. Furthermore, it utilizes unconverted THC and CO from rich-burn conditions, avoiding the waste of CO reducing agent.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a schematic diagram of an after-treatment system for an engine according to an embodiment of the present invention.

[0022] Figure label:

[0023] 10. After-treatment systems for engines;

[0024] 1. First Module; 2. Third Module; 3. Second Module; 4. Mixing Pipeline; 5. Mixer;

[0025] 20. Exhaust pipe. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The following is for reference. Figure 1 An after-treatment system 10 for an engine is described according to an embodiment of the present invention.

[0030] like Figure 1 As shown, the after-treatment system 10 for an engine according to an embodiment of the present invention includes a first module 1 and a second module 3.

[0031] Specifically, the first module 1 is installed in the engine's exhaust pipe 20 and is used to oxidize NO (nitric oxide) in the exhaust pipe 20 to NOx, such as NO2 (nitrogen dioxide), and reform CO (carbon monoxide) and THC (total hydrocarbons) into H2 (hydrogen). The second module 3 is installed in the engine's exhaust pipe 20 and utilizes the H2 generated by the first module 1 to convert NOx in the engine exhaust under rich combustion conditions into NH3. Where x is greater than or equal to 2.

[0032] The engine produces NOx (nitrogen oxides), THC (hydrocarbons), and CO under both lean-burn and rich-burn conditions. Under rich-burn conditions, NOx production is higher, with NOx acting as an oxidant and THC and CO as reducing agents. Module 3 is used to convert the NOx produced by the engine into NH3. Under rich-burn conditions, some THC and CO remain unconverted into NH3. Additionally, Module 1 can reform CO into H2 under rich-burn conditions, and Module 3 utilizes the H2 produced by Module 1 to convert nitrogen oxides into NH3, thus improving the selectivity of NOx-to-NH3 conversion, i.e., producing more NH3.

[0033] In this module, CO is reformed into H2 via a water-gas transformation reaction. THC is also reformed into H2 via hydrocarbon steam reforming.

[0034] Additionally, refer to Figure 1 According to an embodiment of the present invention, the aftertreatment system 10 for an engine performs the following process: a first module 1 oxidizes NO to NOx under lean combustion conditions, a first module 1 reforms CO to H2 under rich combustion conditions, and a second module 3 converts NOx in the exhaust gas into NH3 under rich combustion conditions.

[0035] The aftertreatment system 10 for an engine according to an embodiment of the present invention, by providing a first module 1 and a second module 3, wherein the first module 1 is used to oxidize NO to NOx under lean-burn conditions and reform CO to H2 under rich-burn conditions, and the second module 3 generates NH3 under rich-burn conditions, the selectivity of conversion to NH3 can be improved and more NH3 can be generated. In addition, the unconverted THC and CO from rich-burn conditions are utilized, avoiding the waste of CO reducing agent.

[0036] In some embodiments of the present invention, such as Figure 1 As shown, the aftertreatment system 10 for the engine also includes a third module 2, which is disposed in the engine's exhaust pipe 20. The third module 2 is used to at least adsorb nitrogen oxides (NOx). Under lean-burn conditions, NOx production is low and oxygen production is high, so NOx cannot be reduced. The third module 2 can adsorb nitrogen oxides under lean-burn conditions, store the nitrogen oxides, and then release them to produce NH3 after switching from lean-burn to rich-burn conditions, thereby increasing the production of NH3.

[0037] To increase NH3 production, this invention stores NOx from engine exhaust under lean-burn conditions in a third module 2, and converts this portion of nitrogen oxides and the nitrogen oxides in the engine exhaust under rich-burn conditions into ammonia. The first module 1 can oxidize NO to NOx under lean-burn conditions, increasing the NOx content. Additionally, the first module 1 can reform THC and CO into H2 under rich-burn conditions. The second module 3 utilizes the H2 generated by the first module 1 to convert the nitrogen oxides adsorbed in the third module 2 and the NOx in the engine exhaust under rich-burn conditions into NH3, thus improving both the selectivity of NOx to NH3 conversion and the NH3 production. The NH3 produced under rich-burn conditions can be used to reduce NOx in the exhaust gas to N2 under lean-burn conditions.

[0038] Additionally, refer to Figure 1 According to an embodiment of the present invention, the processing procedure of the aftertreatment system 10 for an engine is as follows: the first module 1 is used to oxidize NO to NOx under lean combustion conditions, the third module 2 is used to adsorb NOx under lean combustion conditions, the first module 1 reforms THC and CO into H2 under rich combustion conditions, the third module 2 releases NOx under rich combustion conditions, and the second module 3 converts the NOx released by the third module 2 and the NOx in the engine exhaust under rich combustion conditions into NH3.

[0039] In some embodiments of the present invention, such as Figure 1 As shown, the third module 2 is connected downstream of the first module 1, and the second module 3 is connected downstream of the third module 2. This facilitates the first module 1 to oxidize NO to NOx under lean-burn conditions, the third module 2 to adsorb NOx under lean-burn conditions, the first module 1 to reform THC and CO into H2 under rich-burn conditions, the third module 2 to release NOx under rich-burn conditions, and the second module 3 to convert the NOx released by the third module 2 and the NOx in the exhaust gas into NH3 under rich-burn conditions.

[0040] In some embodiments of the present invention, the catalytic material of the first module 1 is a non-precious metal material. In related technologies, the conventional third module requires the precious metal Pt to oxidize NO to NOx in order to achieve NOx storage, but the use of precious metals makes the nitrogen oxide storage module costly. Using a non-precious metal material as the catalytic material in the first module 1 of this application can reduce costs.

[0041] Optionally, the catalytic material of the first module 1 is a transition metal and / or its oxide supported on a rare earth element oxide. For example, it can be one or more of Ni / CeO2, Ni / La2O3, Co / CeO2, and Co / La2O3. Transition metals and / or their oxides supported on rare earth element oxides are low in cost and can ensure sufficient ability to oxidize NO to NOx and convert THC and CO to H2.

[0042] Optionally, the adsorbent of the third module 2 is a K-based adsorbent or a Pt-based adsorbent. When the adsorbent of the third module 2 is a Pt-based adsorbent, the adsorbent of the third module 2 can be Pt-Cs / Al2O3. K-based or Pt-based adsorbents can store as much NOx generated under lean-burn conditions as possible at higher temperatures, making them suitable for lean-burn gasoline engines.

[0043] In related technologies, the exhaust temperature of lean-burn gasoline engines is relatively high, and traditional Pt-Ba / γ-Al2O3 materials can store less NOx during lean-burn.

[0044] Optionally, the ammonia-producing material in the second module 3 is a Pd-based catalyst. Using the H2 produced in the first module 1, NOx stored under lean-burn conditions can be selectively converted into NH3.

[0045] In some embodiments of the present invention, the aftertreatment system 10 for the engine further includes a particulate filter connected to the exhaust pipe 20 and located downstream of the first module 1, the third module 2, and the second module 3, for filtering particles in the exhaust pipe 20. This prevents particles in the exhaust from being emitted into the atmosphere and polluting the environment.

[0046] In some embodiments of the present invention, the aftertreatment system 10 for the engine further includes a selective catalytic reduction module disposed on the exhaust pipe 20 for storing NH3. The selective catalytic reduction module can store NH3 under rich combustion conditions for reducing NOx under lean combustion conditions, thereby eliminating NOx in the exhaust.

[0047] The vehicle according to an embodiment of the present invention is described below.

[0048] The vehicle according to an embodiment of the present invention includes an engine and the above-described aftertreatment system 10 for the engine. The engine has an exhaust pipe 20, and a first module 1, a third module 2, and a second module 3 are all connected to the exhaust pipe 20.

[0049] According to an embodiment of the present invention, the vehicle is equipped with the above-described aftertreatment system 10 for the engine.

[0050] The system is configured with a first module 1 and a second module 3. The first module 1 oxidizes NO to NOx under lean combustion conditions and reforms CO to H2 under rich combustion conditions. The second module 3 generates NH3 under rich combustion conditions, which improves the selectivity of the conversion to NH3 and produces more NH3. Furthermore, it utilizes unconverted THC and CO from rich combustion, avoiding waste of CO reducing agent.

[0051] Other configurations of the engine according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0053] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An aftertreatment system for an engine, characterized by, include: The first module, located in the engine's exhaust pipe, is used to at least oxidize NO in the exhaust pipe to NOx, and reform THC and CO into H2; The second module is located in the engine's exhaust pipe. The second module utilizes at least the H2 generated by the first module to convert NOx into NH3.

2. The aftertreatment system for an engine of claim 1, wherein, The catalytic material of the first module is a non-precious metal material.

3. The aftertreatment system for an engine of claim 2, wherein, The catalytic material of the first module is a transition metal and / or its oxide supported on a rare earth element oxide.

4. The aftertreatment system for an engine according to claim 3, characterized in that, The catalytic material of the first module is one or more of Ni / CeO2, Ni / La2O3, Co / CeO2, and Co / La2O3.

5. The aftertreatment system for an engine according to claim 1, characterized in that, The ammonia-producing material in the second module is a Pd-based catalyst.

6. The aftertreatment system for an engine according to claim 1, characterized in that, Also includes: The third module, located in the engine's exhaust pipe, is used to adsorb at least nitrogen oxides.

7. The aftertreatment system for an engine according to claim 6, characterized in that, The third module is connected downstream of the first module, and the second module is connected downstream of the third module.

8. The aftertreatment system for an engine according to claim 6, characterized in that, The adsorption material of the third module is a K-based adsorbent or a Pt-based adsorbent.

9. The aftertreatment system for an engine according to claim 1, characterized in that, Also includes: A particulate filter, connected to the exhaust pipe and located downstream of the first module and the second module, is used to filter particles in the exhaust pipe. And / or, a selective catalytic reduction module, disposed in the exhaust pipe of the engine, the selective catalytic reduction module being used to store NH3.

10. The aftertreatment system for an engine according to claim 1, characterized in that, CO is reformed into H2 through a water-gas reaction.

11. A vehicle, characterized in that, Includes an aftertreatment system for an engine according to any one of claims 1-10.

Images