KR100766725B1 - Exhaust gas purifying device for diesel engine with exhaust gas recirculation line - Google Patents

Abstract

An exhaust gas purifying device for a diesel engine with an exhaust gas re-circulation line is provided to remarkably improving NOx reduction performance of an exhaust gas. An exhaust gas purifying device for a diesel engine with an exhaust gas re-circulation line includes a NOx reduction catalyst part(1) and a particulate matter removal filter part(2), a diesel injector(3), and an exhaust gas re-circulation line(4). The NOx reduction catalyst part and the particulate matter removal filter part are sequentially installed from an upstream part of an exhaust gas flow. The diesel injector is installed at a front end of the NOx reduction catalyst part. The exhaust gas re-circulation line introduces a portion of an exhaust gas from a rear end of the particulate matter removal filter part into an intake manifold of an engine.

Description

Exhaust gas purifying device for diesel engine with exhaust gas recirculation line

1 shows an exhaust gas purifying apparatus according to the present invention,

2 is a graph showing the change of NOx and PM according to the exhaust gas recycle rate (EGR Rate),

Figure 3 shows the case where one DeNOx catalyst layer,

4 shows a case where the DeNOx catalyst layers are several layers.

<Description of Symbols in Drawings>

1: Nitrogen oxide reduction catalyst (DeNOx catalyst) part 2: Particle removal filter (DPF) part

3: diesel injection injector 4: exhaust gas recirculation (EGR) line

5: intake manifold 6: turbocharger

6a: Compressor 6b: Turbine

7: diesel engine 8: air filter

9: intercooler 10: diesel injection controller

11: fuel tank

The present invention relates to a diesel engine exhaust purification apparatus for efficiently purifying nitrogen oxides (NOx) and particulate matter (PM) contained in exhaust gas of a diesel engine.

Diesel engines are low in fuel consumption and have excellent reliability, and are widely used in industries such as automobiles, ships, and general industries. In addition, the adoption of diesel engines in the 3L Car Program or Super Car Project, which is being promoted for low fuel consumption vehicles, is being actualized, and the increase of diesel engine vehicles is expected. However, in advanced countries, such diesel vehicles account for 40% of the total air pollution, and are recognized as a major cause of air pollution.

To cope with this, countries are tightening emission regulations for diesel engines. Air pollution of these diesel vehicles is mainly caused by nitrogen oxides (NOx) and particulate matter (PM). Therefore, the main targets of diesel vehicle emission regulation are nitrogen oxides and particulate matters, and the countermeasures for the reduction of nitrogen oxide concentrations due to the delay of fuel injection timing and exhaust gas recirculation, and the reduction of particulate matters. It was developed with the focus on improving and improving the combustion performance of the engine.

As a method for reducing nitrogen oxides, a selective catalytic reduction (SCR) method of reducing nitrogen oxides to nitrogen and oxygen on a catalyst using a reducing agent is used.

In this case, as the reducing agent used in the selective catalytic reduction reaction, ammonia, urea, and hydrocarbons may be used, but ammonia and urea have a disadvantage in that an infrastructure that can be supplied separately is preferred, and hydrocarbons are preferred. , Propylene, propane, ethylene, butylene, methane and the like.

On the other hand, the diesel particulate filter (DPF) method is widely used as a PM reduction method, and may be divided into continuous regeneration and forced regeneration according to a method of continuously regenerating PM collected in the filter. The continuous regeneration method is a method of regenerating PM by converting NO into NO ₂ by an oxidation catalyst installed at the front end of the DPF, and forcibly regenerating the forced regeneration by using an auxiliary device capable of forcibly increasing the temperature of the filter. Expression Forcible regeneration may be performed by forming an electrode on the DPF and discharging it, increasing the temperature of the filter using an electric heater, or installing a plasma reactor at the front end of the DPF or regenerating by injecting diesel. .

A conventional diesel engine exhaust purifier is provided with a DPF carrying an oxidation catalyst on the upstream side of the exhaust passage, a hydrocarbon selective reduction nitrogen oxide reduction catalyst (DeNOx catalyst) on the downstream side, and fuel injection between the DPF and the DeNOx catalyst. Exhaust purification systems with injectors are known.

However, the conventional exhaust purification apparatus is insufficient to effectively remove CO and THC (Total Hydrocarbon) simultaneously including nitrogen oxide and particulate matter in the middle temperature zone.

On the other hand, the exhaust gas recirculation (EGR) system is a technique that has been used to reduce nitrogen oxides. In general, the exhaust gas is introduced from the rear end of the turbocharger to the compressor of the turbocharger to reduce the NOx by lowering the combustion temperature of the engine. It has been used in a way. However, this method has a problem in that the exhaust gas discharged from the turbocharger contains a large amount of particulate matter, causing an engine load and lowering fuel economy. Also, as the EGR rate increases, the NOx decreases but the PM There is a tendency to increase, and there is a limit to reducing NOx by applying EGR. In addition, the conventional exhaust gas recirculation (EGR) system is equipped with a valve controlled by the engine control device and an EGR cooler for lowering the temperature of the exhaust gas being recirculated, so that the configuration of the device is complicated, and thus the layout of the engine is laid out. ) Is not only good, but the effect is also not high, there is a disadvantage in the application.

As a patent for improving the problems of the conventional EGR system, Korean Patent Publication No. 367666 discloses an exhaust gas recirculation (EGR) line connecting one side of the particle removal filter and the front of the blower of the turbocharger. In the above patent, the exhaust gas recirculation line is intended to improve in terms of ease of device configuration by recirculating a part of the exhaust gas without providing an engine control device or an EGR cooler, but since the EGR alone does not have high nitrogen oxide reduction efficiency, it is substantially exhausted. There is a disadvantage of low nitrogen oxide reduction efficiency in the gas.

In addition, although an exhaust gas purification apparatus using EGR and DeNOx catalysts is disclosed in US Patent No. 5924280, the patent discloses an EGR system for recycling exhaust gas from the upper end of the DeNOx catalyst to the intake manifold. As described above, the exhaust gas containing a large amount of particulate matter is recycled to cause an engine load and further reduce the combustion efficiency of the engine. The EGR valve and a control device for driving the engine include a complicated device configuration. Have

The inventors of the present invention in the Republic of Korea Patent Application No. 2005-0102494 is provided with a nitrogen oxide reduction catalyst (LNC) and a particle removal filter (DPF) sequentially from the upstream with respect to the exhaust gas flow, the exhaust gas purification installed with a diesel injection injector on top of the LNC The device has been filed. In this patent, although the nitrogen oxide reduction efficiency is superior to the conventional exhaust gas purification system, in order to meet the demand for more enhanced nitrogen oxide reduction efficiency in recent years, exhaust gas recirculation ( EGR) has further developed an exhaust gas purification device.

Accordingly, an object of the present invention is to provide an exhaust gas purification apparatus for a diesel engine, in which an exhaust gas purification apparatus including a nitrogen oxide reduction catalyst (LNC) and a particle removal filter (DPF) is significantly improved. have.

In addition, the present invention is very excellent in reducing the nitrogen oxide at the actual exhaust gas temperature of 250 ~ 600 ℃, high efficiency of removing particulate matter and at the same time can be removed from the exhaust gas purification device of a diesel engine that can remove CO, THC and the like. To provide.

The present inventors have endeavored to achieve the above object, and as a result, a nitrogen oxide reduction catalyst and a particle removal filter are sequentially provided upstream with respect to the flow of the exhaust gas, and a diesel injection injector is installed at the front end of the nitrogen oxide reduction catalyst, An exhaust gas purifying apparatus of a diesel engine provided with an exhaust gas recirculation (EGR) line for guiding a part of the exhaust gas to the intake manifold from the rear end of the removal filter has been invented.

The present invention relates to an exhaust purification apparatus of a diesel engine for efficiently purifying nitrogen oxides (NOx) and particulate matter (PM) contained in exhaust gas of a diesel engine, and more particularly, a nitrogen oxide reduction catalyst and particles. A removal filter is provided sequentially upstream with respect to the flow of exhaust gas, and a diesel injection injector is installed at the front end of the nitrogen oxide reduction catalyst, and for introducing a part of the exhaust gas to the intake manifold from the rear end of the particle removal filter. Provided is an exhaust gas purification device for a diesel engine having an exhaust gas recirculation line and not including a separate EGR control valve or an EGR control device.

In addition, the exhaust gas purifying apparatus according to the present invention may further include a diesel oxidation catalyst (DOC), the location of the oxidation catalyst is the front end of the diesel injection injector, between the diesel injection injector and the nitrogen oxide reduction catalyst, nitrogen oxide reduction It may be located between the catalyst and the particle removal filter, or between the particle removal filter and the inlet of the exhaust gas recirculation line, it may be provided with one or more oxidation catalyst in the position.

Hereinafter, the present invention will be described in more detail.

The exhaust gas purifying apparatus of the diesel engine according to the present invention reduces the NOx in the nitrogen oxide reduction catalyst portion (hereinafter referred to as the 'DeNOx catalyst portion') by injecting diesel, and removes particles by diesel combustion (hereinafter referred to as 'DPF'). Removes particulate matter (PM) accumulated in the unit and simultaneously removes CO and THC (Total Hydrocarbon). Also disclosed is an exhaust gas purifier that further reduces NOx by providing an exhaust gas recirculation (hereinafter referred to as "EGR") line for guiding a part of the exhaust gas from the rear end of the DPF to the intake manifold.

In the exhaust gas purifier according to the present invention, the NOx is partially reduced by providing the EGR line, and the NOx catalyst is removed from the DeNOx catalyst provided in the exhaust gas passage, so that the nitrogen oxides can be more effectively removed than the conventional exhaust gas purifier. In addition, since nitrogen oxides are additionally removed by the catalyst coated on the DPF provided at the rear of the DeNOx catalyst part, the nitrogen oxide reduction efficiency is much superior to the conventional exhaust gas purifier, and particularly in the medium temperature zone of 250 to 350 ° C. This has the advantage of increasing conversion rates.

In addition, in the present invention, the particulate matter is mostly removed from the DPF portion, when the diesel injection in the front of the DeNOx was passed through the DeNOx catalyst to uniformly distribute the diesel was able to lower the regeneration temperature of the DPF.

Furthermore, the present invention can more effectively remove CO and THC which have been removed by the conventional exhaust gas purification apparatus.

Since CO is not removed from the DeNOx catalyst, CO is increased when only the DeNOx catalyst is present. However, in the present invention, it is possible to effectively remove CO at 200 ° C. or more due to the platinum group component of the DPF part.

Even in the case of THC, it is not removed from the DeNOx catalyst. In particular, when the diesel is injected into the reducing agent to remove the nitrogen oxide, more HC (Hydrocarbon) is included in the exhaust gas than in the case where the diesel is injected into the reducing agent. In order to solve this problem, the present invention can effectively remove the unreacted HC increased while passing through the DeNOx catalyst in the DPF part.

In addition, one or more oxidation catalysts (DOC) may be placed at the front of the diesel injection injector, between the diesel injection injector and the nitrogen oxide reduction catalyst, between the nitrogen oxide reduction catalyst and the particle removal filter, or between the particle removal filter and the inlet of the exhaust gas recirculation line. When provided, NO in exhaust gas can be converted to NO ₂ to facilitate regeneration in DPF, and the efficiency of removing THC including soluble organic fraction can be improved.

As an embodiment of the present invention is shown in Figure 1 the exhaust gas purification apparatus inserted into the exhaust passage of the diesel engine. According to Figure 1 according to the flow of the exhaust gas DeNOx catalyst unit (1) is provided on the upstream side, the DPF unit 2 is provided in series, a diesel injection injector (3) is provided at the front end of the DeNOX catalyst unit And an intake manifold (5) between the rear end of the DPF section and the compressor top of the turbocharger of the engine. EGR system according to the present invention has the advantage that the device configuration is easy because there is no additional EGR cooler, EGR valve and EGR control device, a portion of the exhaust gas is automatically introduced according to the air inlet flow in the intake manifold (5) The mixture is mixed with the intake air and flows into the engine 7 via the compressor 6a of the turbocharger 6. The exhaust gas of the diesel engine 7 is exhausted through the turbine 6b of the turbocharger, and the DeNOx catalyst unit 1 and the particle removal filter (DPF) unit 2 are sequentially provided in the exhaust passage, and the DeNOx catalyst unit is sheared. The diesel injection injector 3 is provided. The exhaust gas recirculation rate (EGR rate) of the exhaust gas purification apparatus according to the present invention is preferably 0.1 to 15%, which is adjusted according to the thickness of the exhaust gas recirculation line. When the exhaust gas recirculation rate is less than 0.1%, the NOx reduction effect is hardly exhibited, and when the exhaust gas recirculation rate exceeds 15%, the amount of PM generated from the engine is significantly increased, and a load is applied to the DPF filter. Not In the case of adjusting to the above range, as shown in FIG. 2, the reduction of NOx can be increased with little increase in PM, and in combination with the NOx reduction efficiency by the DeNOX catalyst unit 1, a markedly increased NOx reduction efficiency can be achieved. Can be. In addition, the particulate matter in the exhaust gas is completely removed from the DPF unit 2, so that the diesel injected from the diesel injection injector 3 provided in front of the DeNOx catalyst unit 1 passes through the DeNOx catalyst so that the diesel is uniformly distributed. The regeneration temperature of the DPF can be lowered. The injected diesel is injected into the diesel injection injector by the inflow pump (not shown) from the fuel tank 11 and injected, the amount and timing of the injected diesel is controlled by the diesel injection control device (10). .

In the exhaust gas purifying apparatus according to the present invention, the DeNox catalyst unit 1, the DPF unit 2, and the diesel injector 3 are illustrated in FIGS. 3 and 4. In the case of FIG. 3, the DeNOx catalyst part of one layer is disclosed, and FIG. 4 shows the DeNOx catalyst part of a multilayer. Referring to FIG. 4, DeNOx catalyst sections are arranged successively with each DeNOx catalyst section adjacent to each other in multiple layers. If the DeNox catalysts are arranged in multiple layers, the NOx reduction efficiency can be improved by increasing the surface area through which exhaust gas passes.In addition, the NOx reduction efficiency can be increased by using different catalysts or changing the content of the catalyst in each layer. In addition, the NOx reduction efficiency is excellent in various temperature ranges, and has an advantage of having excellent NOx reduction performance regardless of an operating state of an engine causing a difference in NOx reduction performance according to exhaust gas temperature.

The DeNOx catalyst part according to the present invention uses a catalyst in which a silver (Ag) component, a copper (Cu) component, or a mixture thereof is supported, and a material usable for supporting the silver (Ag) component is silver (Ag) in a reduced state. The material used for supporting the copper (Cu) component may be selected from silver oxide (Ag ₂ O), silver chloride (AgCl), silver nitrate (AgNO ₃ ), silver sulfate (Ag ₂ SO ₄ ) or a mixture thereof. It is selected from copper (Cu), copper oxide, copper acetate, copper nitrate, copper sulfate or a mixture thereof. As a carrier supporting the catalyst, alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), ceria (CeO ₂ ), zirconia (ZrO ₂ ) or zeolite may be used. You may use it. Among them, using alumina as a carrier was more excellent in terms of nitrogen oxide reduction performance.

The carrier is coated on the support to be used, and the amount of the carrier is preferably 0.5 to 4 g / in ³ based on the total catalyst content. At this time, when the content of the carrier is less than 0.5 g / in ³ , the absolute amount of the supported catalyst is small, which significantly reduces the performance of the catalyst. When the content of the carrier exceeds 4 g / in ³ , the catalyst performance does not increase any more and is not easily manufactured. do.

The support of the DeNOx part is a flow-through support made of a heat resistant ceramic or metal material, and more specifically, a cordierite honeycomb molded body may be exemplified.

The silver component, the copper component, or a mixed component thereof according to the present invention is preferably used so as to be 0.1 to 10% by weight based on the weight of the carrier. If the content is less than 0.1% by weight, the absolute amount of the component responsible for the catalysis becomes small, and the performance of the catalyst is significantly reduced. If the content is more than 10% by weight, the catalyst is present in an unfavorable metal state, thereby significantly reducing the performance of the catalyst. do.

In addition, the DeNOx catalyst according to the present invention additionally supports the platinum group component so that the nitrogen oxide reduction performance is more excellent at the actual exhaust gas temperature of 250 ~ 600 ℃. Nitrogen oxide reduction catalyst according to the present invention is excellent in nitrogen oxide reduction performance at the actual exhaust gas temperature 250 ~ 600 ℃, the nitrogen oxide reduction performance is more excellent in the range of 350 ~ 450 ℃ when additionally carrying a platinum group catalyst Has

The metal usable as the platinum group precious metal supported on the DeNOx catalyst part may be made of one or two or more of Pt, Pd, Ru, Ir, and Rh, and palladium nitrate as a starting material of palladium (Pd), Palladium chloride, tetraminpalladium dichloride and the like can be used. Platinum chloride, diamine nitritoplatinum, diaminetetrachloroplatinum, etc. may be used as starting materials of platinum (Pt), and rhodium chloride, rhodium nitrate, triamine rhodium hexachloride, etc. This can be used. In addition, the content of the platinum group metal is preferably 0.0001 to 0.5% by weight, preferably 0.0005 to 0.2% by weight, and more preferably 0.001 to 0.1% by weight. If the content is less than 0.0001% by weight does not help improve the performance, if it exceeds 0.5% by weight because the performance rapidly decreases.

The DPF according to the present invention is a filter on which a platinum group catalyst is supported, and the element supported by the platinum group catalyst is one or more selected from the group consisting of Pt, Pd, Ir, and Rh, but Pt or Pd is more preferable. The content of the platinum group catalyst supported on the DPF is 0.01% to 5% by weight based on the carrier coated with the support, and when the content is less than 0.01% by weight, no particulate matter removal effect occurs. This may not be improved and may be disadvantageous economically.

In addition, the DPF may further support an oxidation promoter component in addition to the platinum group catalyst. Oxidation promoter component may serve to inhibit the oxidation of sulfurous acid gas or to increase the surface activity of the platinum group catalyst. In general, platinum group catalysts show high activity in the oxidation reaction of soluble organic matter (SOF), but sulfur sulfide gas (SO ₂ ), which is a combustion product of sulfur contained in light oil, is oxidized to become sulfate, resulting in increased particulate matter. It does not result. In order to remedy this problem, one or more catalyst components selected from V, W or Mo may additionally be used in the platinum group catalyst. The at least one catalyst component selected from V, W or Mo is preferably in an amount of 0.01% by weight to 2% by weight relative to the carrier coated carrier. When the content is less than 0.01% by weight, there is no effect of inhibiting the oxidation of sulfurous acid gas, and when the content exceeds 2% by weight, it is not economical because there is no significance due to additional addition. In addition, alkali metal components such as K and Mg have low temperature fluidity, thereby increasing the surface activity of the platinum group catalyst, thereby facilitating the catalytic reaction rate by facilitating contact between the catalyst and particulate matter. The alkali metal is preferably used in an amount of 0.01% by weight to 1% by weight based on the support coated with the carrier. When the content is less than 0.01% by weight, there is no effect of increasing the reaction rate of the platinum group catalyst, and when the content exceeds 1% by weight, it is not economical because there is no significance due to additional addition.

In addition, the carrier supporting the catalyst component may be alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), ceria (CeO ₂ ), zirconia (ZrO ₂ ) or zeolite, two kinds You may mix and use the above.

DPF according to the present invention removes the accumulated particulate matter by using the exhaust gas is heated while the diesel injected from the front end of the nitrogen oxide reduction catalyst is oxidized. In this case, the support may be made of an alloy material including cordierite having excellent heat resistance, a ceramic containing SiC, a Ni alloy, or a FeCr alloy so that the support may be used safely even when the temperature of the DPF is excessively elevated. In the case of using the above high heat resistant material as a support, it is possible to safely operate against the high heat generated during the regeneration of the DPF, and also to use the heat generated when the excessive particulate material is oxidized, thereby saving the amount of diesel fuel injected. There are advantages to it.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the embodiments described below.

[Production Example 1]

Nitrogen oxide reduction (DeNox) catalyst was prepared as follows. Gamma Alumina Powder [Surface Area: 210m ² / gr, Pore Volume: 0.5cc / gr, Specific Gravity: 0.8g / cc], acetic acid and secondary distilled water are mixed, and then pulverized using a wet ball mill for 24 hours to give a uniform alumina slurry. Was prepared. The average particle size of the alumina ground through a wet ball mill was adjusted to 2 to 8 micrometers.

The coated alumina slurry was coated with a coated coat of alumina to be 3 g / in ³ by washing the cordierite honeycomb having a diameter of 11.25 inches and a length of 3 inches of 400 cpsi, and then coating the alumina to 3 g / in ³ , and then, at a room temperature to 120 ° C. After heating 3 degreeC per minute, it dried at 120 degreeC for 3 hours, and then heated up at 3 degreeC per minute from 120 degreeC to 550 degreeC, and baked at 550 degreeC for 3 hours.

Then, the calcined alumina-supported cordierite dried body was impregnated into a solution prepared by dissolving platinum chloride with silver nitrate and a platinum precursor, followed by impregnating silver to 2.0% by weight and platinum catalyst component to 0.001% by weight. Baking was carried out at 120 ° C. for 3 hours and at 550 ° C. for 3 hours as in alumina washer coating conditions.

 [Production Example 2]

Particle removal filter (DPF) was prepared as follows. In a 2 L flask, 252 g of polyvinylpyrrolidone (Aldrich Chemical, average molecular weight 10,000) is dissolved in 1 L of distilled water to make a homogeneous solution. 30.4 g of chloroplatinic acid was added thereto, and 1 L of methanol was added thereto, followed by stirring. The solution was refluxed at 80 ° C. for 6 hours and filtered to obtain 2,070 g of a dark brown platinum colloidal solution with a platinum content of 0.62% by weight. 15.4 g of ammonium molybdate and 10 g of potassium hydroxide were added to 250 mL of distilled water and stirred to prepare an aqueous molybdenum (Mo) solution and an aqueous potassium (K) solution.

Platinum colloidal solution prepared above, molybdenum (Mo) aqueous solution and potassium (K) aqueous solution are mixed in the same weight ratio to obtain a catalyzed metal salt colloidal solution for the filter. Corning's 11.25 inches in diameter, 14 inches in length, and a wallflue type ceramic filter with a cell density of 200 cpsi are used as a support for the catalyzed filter.

The honeycomb monolith was deposited with 7% by weight of titania and silica mixed washcoat solution and then calcined dry. The catalyzed filter colloidal mixture was supported on the wash-coated support so that the platinum-supported support was 0.27 wt%, molybdenum content 0.16 wt%, and potassium content 0.077 wt%. After drying for 3 hours at 120 ℃, it was fired for 4-6 hours at a temperature of 550 ℃ to prepare a filter for removing particulate matter.

Example 1 Performance Evaluation of Exhaust Gas Purification Apparatus-1

The nitrogen oxide reduction catalyst prepared in Preparation Example 1 and the particle removal catalyst prepared in Preparation Example 2 were successively connected, and then placed in a canning made of stainless steel. As shown in FIG. 1, the 1 / 2-inch stainless steel pipe was laterally connected to the front side of the turbocharger in the DPF rear end exhaust pipe. At this time, the exhaust gas recirculation rate (EGR rate) was 5%.

The exhaust gas reduction and particulate matter reduction evaluation test was conducted by Japanese 13 mode for large diesel vehicles. The engine used for the evaluation test used a Daewoo engine with an 11-liter displacement supercharger and an intermediate cooler. The test was carried out at a constant rpm and torque specified in the test mode in the engine dynamo. The diesel used at this time was ultra low sulfur diesel having a sulfur content of 50 ppm. As a result, carbon monoxide was reduced by 93%, hydrocarbon by 32%, nitrogen oxide by 55%, and PM removal by 93%.

Table 1. Exhaust gas and particulate matter reduction test results for Daewoo engine

Comparative Example 1 Performance Evaluation of Exhaust Gas Purification Apparatus-2

The nitrogen oxide reduction catalyst prepared in Preparation Example 1 and the particle removal catalyst prepared in Preparation Example 2 were continuously connected so that only the exhaust gas circulation pipe was not installed in Example 1, and then the canning was made of stainless steel. Located. The exhaust gas reduction and particulate matter reduction evaluation test was conducted by Japanese 13 mode for large diesel vehicles. The test was carried out at a constant rpm and torque specified in the test mode in the engine dynamo. The diesel used at this time was ultra low sulfur diesel having a sulfur content of 50 ppm. As a result, the reduction rate was 92% for carbon monoxide, 34% for hydrocarbon, 38% for nitrogen oxide, and 93% for PM removal.

Table 2. Exhaust gas and particulate matter reduction test results for Daewoo engine

Exhaust gas purification device of a diesel engine according to the present invention is an exhaust gas purification device excellent in nitrogen oxide reduction performance and excellent particle removal efficiency at 250 ~ 600 ℃, the actual vehicle exhaust gas temperature, selective nitrogen oxide by diesel injection The reduction of nitrogen oxides by reduction and exhaust gas recirculation (EGR) is simultaneously performed, and the efficiency of nitrogen oxide reduction is remarkably improved, and the particle removal filter provided at the rear end of the nitrogen oxide reduction catalyst effectively removes PM. .

In addition, regardless of the operating state of the engine causing a difference in the NOx reduction performance according to the temperature of the exhaust gas has an excellent NOx reduction performance, and excellent removal efficiency of CO and HC as well as PM.

Claims (19)

A nitrogen oxide reduction (DeNOx) catalyst unit and a particle removal filter (DPF) unit which are sequentially provided upstream with respect to the flow of the exhaust gas; A diesel injection injector provided at the front end of the nitrogen oxide reduction catalyst; An exhaust gas recirculation (EGR) line for introducing a portion of the exhaust gas from the rear end of the particle removal filter part to the intake manifold of the engine; And the EGR line does not include a separate control valve or control device. The method of claim 1, The exhaust gas recirculation rate (EGR rate) is an exhaust gas purification apparatus of a diesel engine, characterized in that 0.1 to 15%. The method of claim 1, The nitrogen oxide reduction catalyst unit, the exhaust gas purification device of a diesel engine, characterized in that each catalyst unit is arranged adjacent to each other in multiple layers. The method of claim 3, wherein The exhaust catalyst purification apparatus of the diesel engine, characterized in that the adjacent catalyst portion has a different catalyst composition or content. The method of claim 1, The exhaust gas purification apparatus includes one or more oxidation catalysts in front of the diesel injection injector, between the diesel injection injector and the nitrogen oxide reduction catalyst, between the nitrogen oxide reduction catalyst and the particle removal filter, or between the particle removal filter and the inlet of the exhaust gas recirculation line. An exhaust gas purification device for a diesel engine, characterized by further comprising. The method according to any one of claims 1 to 5, The particle removal filter is an exhaust gas purification device of a diesel engine, characterized in that the platinum group catalyst is supported. The method of claim 6, The platinum group catalyst component is at least one selected from the group consisting of Pt, Pd, Ir and Rh exhaust gas purification apparatus of a diesel engine. The method of claim 7, wherein The particle removal filter is an exhaust gas purification device of a diesel engine, characterized in that the platinum (Pt) component is supported. The method of claim 6, The particle removal filter is an exhaust gas purification apparatus of a diesel engine, characterized in that at least one carrier selected from alumina, silica, titania, ceria, zirconia or zeolite is coated on a support made of a heat resistant ceramic or metal material. The method of claim 9, The particle removal filter is an exhaust gas purification device of a diesel engine, characterized in that 0.01 to 5% by weight of a platinum (Pt) component is supported on a support coated with a carrier. The method of claim 10, An exhaust gas purification device for a diesel engine, wherein the particle removal filter further carries at least one oxidation catalyst component selected from V, W, Mo, Mg or K. The method of claim 11, When the oxidation promoter component is at least one oxidation promoter component selected from V, W or Mo, it is 0.01 to 2% by weight based on the carrier coated with the carrier, and at least one oxidation tank selected from Mg or K. In the case of the catalyst component, the exhaust gas purification apparatus of a diesel engine, characterized in that 0.01 to 1% by weight based on the carrier coated. The method of claim 6, The nitrogen oxide reduction catalyst unit is a diesel engine exhaust gas purification device, characterized in that the silver (Ag) component, copper (Cu) component or a mixture thereof are supported. The method of claim 13, The nitrogen oxide reduction catalyst portion is a diesel engine exhaust gas purification device characterized in that at least one carrier selected from alumina, silica, titania, ceria, zirconia or zeolite is coated on a support made of a heat resistant ceramic or metal material. . The method of claim 14, The nitrogen oxide reduction catalyst unit is an exhaust gas purification device of a diesel engine, characterized in that 0.1 to 10% by weight of silver (Ag) component is supported with respect to the carrier. The method of claim 15, The nitrogen oxide reduction catalyst unit is an exhaust gas purification device of a diesel engine, characterized in that additionally 0.0001 to 0.5% by weight of the platinum group catalyst component to the carrier. The method of claim 16, The nitrogen oxide reduction catalyst unit is an exhaust gas purification device of a diesel engine, characterized in that additionally 0.001 to 0.1% by weight of the platinum group catalyst component to the carrier. The method of claim 17, The platinum group catalyst component is at least one selected from the group consisting of Pt, Pd, Ir and Rh exhaust gas purification apparatus of a diesel engine. The method of claim 18, Exhaust gas purification apparatus of a diesel engine, characterized in that the platinum group catalyst component is platinum (Pt).

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