KR101299970B1 - Apparatus for reducing nitrogen oxide and for antiknock in dimethylether fueled vehicles - Google Patents

Abstract

The present invention relates to an automobile using dimethyl ether as a fuel, and more particularly, a reducing agent generated through an SR catalytic reaction in an automobile using dimethyl ether as a fuel can be used to reduce nitrogen oxide and improve engine performance. The present invention relates to a nitrogen oxide reduction and anti-knocking device and a DME vehicle having the device.

Description

Nitrogen oxide reduction and anti-knocking device for automobiles using dimethyl ether as fuel, and DEM vehicles equipped with the same

The present invention relates to an automobile using dimethyl ether as a fuel, and more particularly, a reducing agent generated through an SR catalytic reaction in an automobile using dimethyl ether as a fuel can be used to reduce nitrogen oxide and improve engine performance. The present invention relates to a nitrogen oxide reduction and anti-knocking device and a DME vehicle having the device.

Clean energy, hydrogen (H ₂ ) is difficult to store and handle, but due to its high calorie and cleanliness, there is increasing interest as a future energy. In particular, DME (dimethyl ether) is currently being studied not only as a hydrogen carrier for future H ₂ supply but also as a fuel that can cope with diesel fuel. At present, the research on controlling the ignition time by using H ₂ produced in DME as an anti-knock agent in the engine has been conducted for a long time. However, numerous papers reported up to now show the concept of generating H ₂ from DME and using it as a source of H ₂ , but the actual experiment did not use H ₂ generated from DME and supplied a separate H ₂ . It was.

More specifically, the method for generating H ₂ in DME includes a catalyst using steam reforming (SR), partial oxidation (PO), and auto thermal reforming (ATR). The SR reaction is an endothermic reaction that requires an external heat source and can theoretically produce up to 75% of H ₂ . PO reaction is exothermic and H ₂ production rate is up to 44%. And it can be generated by the ATR reaction combining the SR and the reaction. Cu-based / r-Al ₂ O ₃ is widely used as the DME SR catalyst, and research on the use of zeolite having a strong acid point as an acid catalyst has been conducted to increase the H ₂ production rate at low temperatures. However, zeolites with strong acidity are lower than r-Al ₂ O ₃ at low temperatures. Although DME is rapidly converted, there are problems such as occurrence of side reactions and deposition of carbon, which results in lower H ₂ production rate. However, no clear solution has been reported.

In addition, recently, a research has been conducted to effectively reduce NOx emitted from a DME engine by directly supplying H ₂ generated in the DME to LNT (Lean NOx Trap), which is one of exhaust gas post-treatment methods. Currently, as the NOx reduction catalyst, lean NOx trap (LNT), urea-SCR (selective catalytic reduction), HC-SCR and the like are very well known. Although urea-SCR catalysts have been commercialized mainly for large vehicles, the lack of infrastructure for supplying large volume urea-SCR systems and aqueous urea solutions requires an alternative to new aftertreatment systems. On the other hand, LNT catalysts developed mainly for small vehicles occupy NOx under lean operation conditions, and NOx adsorbed on the LNT catalyst by using reducing agents (H ₂ , CO, HC) obtained through post injection of fuel without a separate device. Can be effectively removed. However, LNT also uses fuel as a reducing agent, resulting in poor fuel economy.

Therefore, there is a need for developing a new technology that solves the problems of the DME SR catalyst and / or the LNT catalyst known to date.

The present inventors have completed the present invention by developing a technology that uses the SR catalyst and LNT catalyst in parallel in the DME automobile as a result of research efforts to solve this problem.

Accordingly, an object of the present invention is to reduce the nitrogen product by using the reducing agent produced by the DME SR catalytic reaction as a reducing agent of the LNT in an automobile using dimethyl ether as a fuel, and to supply the DME engine to improve the engine performance. It is to provide a nitrogen oxide reduction and anti-knocking device of the configuration that can be used as an anti-knocking agent and a DME vehicle having the device.

Another object of the present invention is to use a heat source and water present in the exhaust gas in a vehicle using dimethyl ether as a fuel, because it does not require a separate heat source supply device to reduce the energy loss of the exhaust gas, cost savings and simplify the process It is to provide a DME vehicle having a nitrogen oxide reduction and anti-knocking device configured to achieve the.

Another object of the present invention is to reduce the NOx and anti-knocking device configured to prevent the degradation of the LNT catalyst due to sulfur poisoning because it uses dimethyl ether that does not contain sulfur in automobiles using dimethyl ether as a fuel It is to provide a DME car having.

Another object of the present invention is to deposit carbon in the SR catalyst under operating conditions in which excess oxygen (O ₂ ) contained in the exhaust gas is used even in the SR catalyst including zeolite to improve H ₂ production in the low temperature region. The present invention provides a DME vehicle having a nitrogen oxide reduction and anti-knocking device having a structure in which carbon deposition does not occur in the SR catalyst because of the super-oxidation reaction.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the object of the present invention described above, first, the present invention comprises a first catalyst for generating a reducing agent including an SR catalyst to react with dimethyl ether; And a second catalyst part disposed at a rear end of the first catalyst part and including an LNT catalyst reacting with a reducing agent supplied from the first catalyst part. It provides a nitrogen oxide reduction and knocking prevention device comprising a.

In a preferred embodiment, further comprises a temperature sensor for sensing the temperature of the second catalyst portion.

In a preferred embodiment, when the temperature of the second catalyst portion detected by the temperature sensor is 350 ℃ or more, the reducing agent generated in the first catalyst portion is supplied to the DME vehicle engine.

In a preferred embodiment, the reducing agent is at least one of H ₂ and CO.

In a preferred embodiment, the first catalyst portion is supplied with exhaust gas discharged from the engine portion of the DME vehicle and dimethyl ether injected from the injector.

In a preferred embodiment, the dimethyl ether supplied to the first catalyst portion is 5% or less of the total feed gas flow rate.

In a preferred embodiment, the SR catalyst is Cu-based / r-Al ₂ O ₃ , is supported on a carrier having a cell density of 100 cpsi ~ 1200 cpsi to form an SR catalyst body.

In a preferred embodiment, the copper content of the SR catalyst is 5% to 40% by weight relative to the total weight of the SR catalyst.

In a preferred embodiment, the SR catalyst further comprises up to 30% by weight zeolite relative to the total weight of the SR catalyst.

In a preferred embodiment, the SR catalyst is 10% by weight of Cu-based / r-Al ₂ O ₃ with 10% by weight of copper containing Modenite.

In a preferred embodiment, the temperature between the first catalyst portion and the second catalyst portion is 300 ℃ to 350 ℃.

In a preferred embodiment, it further comprises a third catalyst portion located in front of the first catalyst portion, including a diesel oxidation catalyst for oxidizing the hydrocarbon or carbon monoxide in the exhaust gas supplied to the first catalyst portion.

The present invention also provides a DME motor vehicle comprising the nitrogen oxide reduction and anti-knocking device of any one of the above-mentioned.

The present invention has the following excellent effects.

First, the present invention can not only reduce the nitrogen product by using the reducing agent produced by the DME SR catalytic reaction as a reducing agent of the LNT in a vehicle using dimethyl ether as a fuel, but also improve the engine performance by supplying the DME engine. Can be used as an anti knocking agent.

In addition, the present invention uses a heat source and moisture present in the exhaust gas in a vehicle using dimethyl ether as a fuel, so a separate heat source supply device is not required, thereby reducing the energy loss of the exhaust gas, reducing costs and simplifying the process. Can be achieved.

In addition, since the present invention uses dimethyl ether which does not contain sulfur in an automobile using dimethyl ether as a fuel, it is possible to prevent a decrease in activity of the LNT catalyst due to sulfur poisoning.

In addition, the present invention is an oxidation and carbon deposited on the SR catalyst under the operating conditions in which excess oxygen (O ₂ ) contained in the exhaust gas is used even in the SR catalyst containing a zeolite to improve the H ₂ production in the low temperature region Because of the reaction, carbon deposition does not occur in the SR catalyst.

1 is a schematic diagram of a nitrogen oxide reduction and anti-knocking device according to an embodiment of the present invention.
Figure 2 is a schematic diagram of a nitrogen oxide reduction and anti-knocking apparatus according to another embodiment of the present invention.
3A is a TME image of SR catalysts 1 and 2 obtained in an embodiment of the present invention, and FIG. 3B is an SEM image of SR catalysts 1 and 4 to 6. FIG.
Figure 4a is a graph showing an SR catalyst 1-3 of DME conversion factor and H ₂ production rate obtained by the embodiment of the invention, Figure 4b is a graph showing a conversion factor DME and H ₂ production rate in the SR catalyst 4-1 to 4-3 , Figure 4c is a graph showing a conversion factor DME and H ₂ production rate in the SR catalyst 5-1 to 5-3, Figure 4d is a graph showing an SR catalyst 6-1 to 6-3 of the DME conversion factor and H ₂ production rate.
5 is a graph showing the effect on the hydrogen production rate when the CO 2 and / or O 2 coexist in the SR catalyst 1 or SR catalyst 4-2 obtained in the embodiment of the present invention.
6 is a graph showing the effect on the hydrogen production rate when the NO and / or NO 2 coexist in the SR catalyst 1 or SR catalyst 4-2 obtained in the embodiment of the present invention.
FIG. 7 is a graph showing the effect of NO and / or O ₂ on the hydrogen production rate when the SR catalyst 1 or the SR catalyst 4-2 obtained in the embodiment of the present invention coexists.
FIG. 8 shows the NOx purification rate measured when the nitrogen oxide reduction and anti-knocking device shown in FIG. 1 including the SR + LNT catalyst having LNT installed at the rear end of the SR catalyst obtained in the embodiment of the present invention. It is a graph.
FIG. 9 is a 250 ppm NO 250ppm + NO ₂ supply of NOx reduction and an anti-knocking device shown in FIG. 2 including an SR + LNT catalyst having LNT installed at a rear end of an SR catalyst obtained in an embodiment of the present invention. It is a graph showing the NOx purification rate measured under one condition.
FIG 10 (a) is a graph showing the NOx purification rate measured by assuming the presence of O ₂ 1% is O ₂ under the same conditions as in Fig. 9 does not completely oxidized in 10, and Figure 10 (b) is LNT It is a graph which measured the air-fuel ratio ((lambda)) of an engine, when DME is supplied to SR + LNT catalyst as a reducing agent.
10 is a graph showing the TPO test results of the SR catalyst and SR + LNT catalyst obtained in the embodiment of the present invention.

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped.

Some terms used to describe the present invention will be defined as follows.

First, as the set temperature or the reference temperature, the temperature of the front end of the SR catalyst means T1, the temperature of the front end of the SR catalyst or the front end of the LNT catalyst means T2, and the temperature of the rear end of the LNT catalyst means T3.

SR catalyst means a catalyst used for reforming dimethyl ether, LNT catalyst means a catalyst for reducing NOx, the catalyst body is formed by being supported by a known supporting technique, such as coating on a carrier on which the catalyst acts as a support Means that.

SR + LNT catalyst is included in the nitrogen oxide reduction and anti-knocking device according to the embodiments of the present invention, a structure formed by arranging the second catalyst portion including the LNT catalyst at the rear end of the first catalyst portion including the SR catalyst Means.

Steady-state condition means that the experiment was performed at a specific temperature, and transient condition means that the experiment was performed while continuously increasing the temperature.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The technical feature of the present invention lies in a technical configuration in which the reducing agent (particularly H ₂ ) produced by the DME SR catalytic reaction can be used for two purposes in a DME vehicle.

That is, according to the present invention, the generated reducing agent can be used as a reducing agent for LNT to improve the de-NOx performance to cope with the restriction of the enhanced exhaust gas and to improve the engine performance by using it as an anti-knock agent in the DME engine. to be.

Therefore, the nitrogen oxide reduction and anti-knocking device of the present invention includes a first catalyst portion and a second catalyst portion located at the rear end of the first catalyst portion, wherein the first catalyst portion includes an SR catalyst which reacts with dimethyl ether to generate a reducing agent. The second catalyst part includes an LNT catalyst that reacts with a reducing agent supplied from the first catalyst part. In some cases, the third catalyst unit may further include a third catalyst unit positioned at a front end of the first catalyst unit and including a diesel oxidation catalyst that oxidizes hydrocarbons or carbon monoxide in the exhaust gas supplied to the first catalyst unit. This is because the LNT catalyst activity of the second catalyst portion may be further improved when the third catalyst portion is further included. Here, each of the catalysts included in the first to third catalysts is more preferably a catalyst body formed by supporting a catalyst on a carrier.

In the nitrogen oxide reduction and knock prevention apparatus according to an embodiment of the present invention having such a configuration, the first catalyst part including the SR catalyst is disposed in front of the second catalyst part including the LNT catalyst, and the temperature of the second catalyst part, By further including a temperature sensor for detecting the temperature (T2) of the front end of the LNT catalyst, it is possible to easily control the reducing agent produced by the DME SR catalytic reaction, especially H ₂ based on the constant temperature detected by the temperature sensor for other uses. Can be.

That is, when the LNT catalyst reacts with the reducing agent produced by the reforming reaction between the dimethyl ether and the SR catalyst, that is, the nitrogen oxide reduction effect occurs at the temperature of 350 ° C. or lower, the second catalyst is supplied to the second catalyst to be discharged by the reaction with the LNT catalyst. It is possible to reduce the nitrogen oxides, and at a temperature above 350 ° C. where the effect of reducing nitrogen oxides by the LNT catalyst does not occur, the reducing agent generated by the SR catalytic reaction can be supplied to the DME engine to control the use of the anti-knocking agent. to be.

The reducing agent generated by the dimethyl ether reforming reaction with the SR catalyst in the first catalyst portion includes H ₂ , CO, etc., the reducing agent produced by the SR catalytic reaction preferably contains a large amount of hydrogen. This is because H ₂ has the best activity even at low temperature as a reducing agent of the LNT catalyst.

Therefore, the content of copper in dimethyl reforming of ether and the SR catalyst may be performed so that the selectivity for H ₂ is high, to increase the selectivity of H ₂ to change the supply amount and the temperature of the SR catalyst of dimethyl ether or, SR catalyst Can be changed.

The SR catalyst included in the first catalyst part is Cu-based / r-Al ₂ O ₃ prepared by impregnation, and the copper content is 5 wt% to 40 wt% of the total weight of the catalyst to increase the selectivity of H ₂ . Is preferably. Here, the SR catalyst may further include a zeolite of 30% by weight or less based on the total weight of the SR catalyst. At this time, the copper content and the zeolite content are experimentally determined optimum values that can increase the selectivity of H ₂ most among the reducing agents produced.

In addition, the SR catalyst is preferably used in the form of an SR catalyst body formed by being supported on a carrier having a cell density of 100 cpsi to 1200 cpsi, that is, a support, in order to increase the contact area with the feed gas. Here, the cell density of the carrier used to form the SR catalyst body may be more preferably 200 cpsi ~ 600 cpsi.

The first catalyst part may be supplied with exhaust gas as well as dimethyl ether. The exhaust gas is discharged from an engine part of a DME vehicle, and dimethyl ether is injected through an injector from a dimethyl ether storage part built in the DME vehicle. At this time, the dimethyl ether supplied to the first catalyst part is 5% or less of the total supply gas flow rate, and the supply amount of dimethyl ether is preferably 0.5% to 2.0% relative to the total flow rate of the feed gas.

Since the reforming reaction of dimethyl ether and SR catalyst is an endothermic reaction, heat source and moisture from the outside are required, but the nitrogen oxide reduction and anti-knocking device according to an embodiment of the present invention has heat source and moisture present in the exhaust gas. By eliminating the need for a separate heat source supply device it is possible to reduce the energy loss of the exhaust gas, to reduce the cost and to simplify the process. Moreover, since dimethyl ether containing no sulfur is used, it is possible to prevent the deactivation of the LNT catalyst due to sulfur poisoning.

Preferably, the temperature between the first catalyst portion and the second catalyst portion is 300 ° C to 350 ° C. As such, the second catalyst portion including the LNT catalyst is maintained by maintaining the temperature between the first catalyst portion and the second catalyst portion. Nitrogen oxides can be effectively reduced at the latter stage. That is, the active temperature of the catalyst may vary depending on the temperature between the first catalyst part and the second catalyst part, and the activity of the catalyst may be directly related to the reduction of nitrogen oxides.

In addition, in order to reduce the nitrogen oxides by a reduction reaction in the second catalyst part including the LNT catalyst, the first catalyst part and the second catalyst part may be spaced apart in a range of 5 mm to 10 mm. The SR catalyst body included in the first catalyst part and the LNT catalyst body included in the second catalyst part may have an SR: LNT of 1.0: 1 to 4.0: 1. The size of the SR catalyst body included in the first catalyst part and the LNT catalyst body included in the second catalyst part may be preferably SR: LNT of 1.0: 1 to 2.5: 1. The size ratio may be appropriately selected depending on the temperature between the first catalyst portion and the second catalyst portion.

In particular, as described below, the SR catalyst included in the first catalyst part includes 10 wt% of Modenite in Cu-based / r-Al ₂ O ₃ having a copper content of 10 wt%, and a cell density of 200 cpsi to 600 cpsi. It can be seen that when used as the SR catalyst body formed by supporting the SR catalyst of the composition on the phosphorus carrier, it shows the highest H ₂ production rate at 350 ℃ or more.

In the apparatus according to an embodiment of the present invention, since the second catalyst part disposed at the rear end of the first catalyst part and the third catalyst part disposed at the front end of the first catalyst part may use a known configuration, a detailed description thereof will be omitted. Shall be.

Example 1

(1) Preparation of SR Catalyst

SR catalyst was prepared as follows by the impregnation method.

H ₂ O 50 ℃, r-Al ₂ O ₃ (Alfa Aesar) was added to 800ml and stirred for 30 minutes. After that, Cu ([Cu (NO ₃ ) ₂ ˜2.5H ₂ O], Sigma Aldrich), a copper precursor, was added so that the copper content was 10% by weight, followed by stirring for 2 hours, followed by evaporation of water for 4 hours under reduced pressure. After evaporation, the dried product was dried for 12 hours, the dried product was heated to 500 ° C. at 4 ° C./min, and calcined with air for 2 hours to prepare Cu 10 / r-Al ₂ O ₃ having a Cu content of 10% by weight.

(2) Preparation of SR Catalyst

In order to coat the calcined Cu10 / r-Al ₂ O ₃ powder in H ₂ O and stir for 2 hours, the carrier [cordierite honeycomb type, 400 cpsi (cell per square inch): made of cordierite material Honeycomb type cell density of 400 cpsi]. After the dip was taken out and dried for 30 minutes in a 3L / min air atmosphere at a temperature of 200 ℃. The catalyst supporting the powder was calcinated at 500 ° C. for 2 hours and then reduced with H ₂ to prepare a Cu 10 / r-Al ₂ O ₃ catalyst (SR catalyst 1).

To support the same amount of powder on the carrier, the weight of the catalyst before and after dip can be measured.

Example 2

A Cu 20 / r-Al ₂ O ₃ catalyst body (SR catalyst 2) was prepared in the same manner as in Example 1 except that the copper content was 20% by weight.

 Example 3

A Cu30 / r-Al ₂ O ₃ catalyst body (SR catalyst 3) was prepared in the same manner as in Example 1 except that the copper content was 30% by weight.

Example 4

In Example 1, r-Al ₂ O ₃ (Alfa Aesar) was added to 800 ml of H ₂ O 50 ° C., stirred for 30 minutes, and Modenite (MD) was added to 5 wt% and 10 wt% of the total weight of the catalyst before adding copper. % Or 20% by weight, except for stirring for 2 hours, the same method as in Example 1 was carried out Cu10 / r-Al ₂ O ₃ + Md 5% (SR catalyst 4-1), Cu10 / r- Al ₂ O ₃ + Md 10% (SR catalyst 4-2) and Cu 10 / r-Al ₂ O ₃ + Md 20% (SR catalyst 4-3) were prepared.

Example 5

In Example 1, after adding r-Al ₂ O ₃ (Alfa Aesar) to 800 ml of H ₂ O 50 ° C. and stirring for 30 minutes, Zeolite β (ZB) was added to 5 wt% and 10 wt% of the total weight of the catalyst before adding copper. % Or 20% by weight, except that the mixture was stirred for 2 hours, the same method as in Example 1 was carried out Cu10 / r-Al ₂ O ₃ + ZB 5% (SR catalyst 5-1), Cu10 / r- Al ₂ O ₃ + ZB 10% (SR catalyst 5-2) and Cu 10 / r-Al ₂ O ₃ + ZB 20% (SR catalyst 5-3) were prepared.

Example 6

In Example 1, after adding r-Al ₂ O ₃ (Alfa Aesar) to 800 ml of H ₂ O 50 ° C. and stirring for 30 minutes, ZSM 5 was added to 5 wt%, 10 wt%, or 20 wt% of the total weight of the catalyst before adding copper. Except for stirring to 2% by weight to give the same method as in Example 1 Cu10 / r-Al ₂ O ₃ + ZM 5% (SR catalyst 6-1), Cu10 / r-Al ₂ O ₃ + ZM 10% (SR catalyst 6-2) and Cu10 / r-Al ₂ O ₃ + ZM 20% (SR catalyst 6-3) were prepared.

Looking at the specific configuration of the nitrogen oxide reduction and anti-knocking device 100 according to an embodiment of the present invention with reference to Figure 1, the device 100 of the present invention is a first catalyst 110 and a first catalyst ( 110, the second catalyst portion 120 disposed at the rear end, the first catalyst portion 110 and the second catalyst portion 120 has a configuration that is connected to each other in a form that can be supplied with gas. Although not shown, it is preferable to include a temperature sensor capable of measuring the temperature of the second catalyst unit 120.

The first catalyst unit 110 includes an SR catalyst. In one embodiment, the SR catalyst may be a catalyst body prepared in Examples 1 to 8.

The first catalyst unit 110 is connected to an exhaust gas main supply pipe 130 that can receive the exhaust gas from the DME engine unit 200, and is connected to the exhaust gas main supply pipe 130 and the first catalyst unit 110. A switching valve 140 is formed to transfer all of the exhaust gas supplied through the exhaust gas main supply pipe 130 to the first catalyst unit 110 or only a portion of the exhaust gas under a predetermined condition, and the remaining exhaust gas is connected to the switching valve 140. While passing through the exhaust gas sub-supply pipe 150 formed to be connected to the front end of the second catalyst unit 120 is configured to be delivered to the second catalyst unit 120 without passing through the first catalyst unit 110.

In addition, an injector nozzle 180 connected to the dimethyl ether storage unit is formed in the first catalyst unit 110 to control the flow rate of dimethyl ether to be 5% or less of the total supply gas supplied to the first catalyst unit 110. To be supplied.

When the exhaust gas and / or dimethyl ether are supplied to the first catalyst unit 110 by the exhaust gas main supply pipe 130 and / or the injector nozzle 180, the SR catalyst reforming reaction is performed by the SR catalyst as described above. Rise and a reducing agent is generated.

Since the reducing agent generated in the first catalyst unit 110 must be supplied to the second catalyst unit 120 or the DME engine unit 200 according to a predetermined condition, the DME engine unit 200 in the first catalyst unit 110. It is preferable that the first reducing agent supply pipe 160 for supplying the reducing agent to the second) and the second reducing agent supply pipe 170 for supplying the reducing agent to the second catalyst unit 120 are connected by a valve. That is, under the condition that the reducing agent is supplied to the second catalyst unit 120, the valve of the second reducing agent supply pipe 170 is opened while the valve of the first reducing agent supply pipe 160 is closed, and the reducing agent is supplied to the DME engine unit 200. This is because the valve of the first reducing agent supply pipe 160 can be opened and the valve of the second reducing agent supply pipe 170 can be easily locked under the condition. In addition, under the condition that the reducing agent is supplied to the DME engine unit 200, the switching valve 140 is connected to the front end of the second catalyst unit 120, that is, to the exhaust gas sub-supply pipe 150 formed to be connected to the second reducing agent supply pipe 170. Most of the exhaust gas is connected to the second catalyst unit 120 without passing through the first catalyst unit 110.

In some cases, such as nitrogen oxide reduction and anti-knocking device 100 according to another embodiment of the present invention shown in Figure 2, further includes a third catalyst 190 in front of the first catalyst unit 110 It can be configured to.

The third catalyst unit 190 is a diesel oxidation catalyst device (DOC = Diesel Oxidation Catalyst) having a known configuration, and has an effect of promoting the catalytic reaction of the second catalyst unit 110.

In the nitrogen oxide reduction and anti-knocking device according to the embodiments of the present invention, the second catalyst part 120 and the third catalyst part disposed at the front end of the first catalyst part 110 are disposed at the rear end of the first catalyst part 110. Since the known configuration 190 may be used as it is, a detailed description thereof will be omitted.

Nitrogen oxide reduction and anti-knock device 100 according to embodiments of the present invention having such a configuration is the first catalyst unit 110 according to the temperature of the second catalyst unit 120 sensed by a temperature sensor (not shown) In order to supply the reducing agent generated in the DME engine unit 200 or the second catalyst unit 120 may be controlled to automatically adjust the valve formed in each supply pipe.

Experimental Example 1

The TEM images (x100k) of Cu10 / r-Al ₂ O ₃ and Cu20 / r-Al ₂ O ₃ powders prepared by the impregnation method in Examples 1 and 2 were used to observe the size and dispersion of Cu particles and to show the results. It is shown in 3 (a).

3 (a) shows that the shape and size of the Cu particles are different depending on the Cu content. As the Cu content increases, the size of the Cu particles grows and aggregates. Therefore, it was found that the SR catalyst containing 10% by weight of Cu had a higher dispersibility and a larger surface area than the catalyst containing 20% by weight and 30% by weight.

Experimental Example 2

Cu 10 / r-Al ₂ O ₃ + modnite (20%), Cu 10 / r-Al ₂ O ₃ + ZSM 5 (20%), Cu 10 / r-Al ₂ O ₃ + Zeolite β (20 prepared in Examples 4 to 6 %) The surface morphology of the particles was observed by SEM image and the results are shown in (b) of FIG. 3 (b) shows that the particle shape of ZSM5 and Modenite is significantly different from that of Cu10 / r-Al ₂ O ₃ , but Zeolite β is very similar. One particle of ZSM5 and Modenite is quite large but has very small micropores, so the specific surface area is quite large, but it is not observed in the SEM image.

In addition, Experimental Examples 3 to 13 used the following experimental apparatus and test method in order to demonstrate the effect of reducing the nitrogen oxide and anti-knocking device according to the embodiments of the present invention.

Experiment apparatus and method

Evaluation of each catalyst used in the nitrogen oxide reduction and anti-knocking apparatus of the present invention was performed using a laboratory scale atmospheric fixed bed model gas catalysis apparatus. The SR catalyst (18mm diameter, 30mm length, 400cell per square inch (cpsi), honeycomb type, cordierite) used in the experiment has a ratio of 2: 1 compared to LNT (SR: LNT). The heat source of the SR catalyst and LNT was supplied using an electric furnace. In order to make the temperature of the SR catalyst similar to the actual vehicle, it was observed based on the rear end (T2) of the DME reforming catalyst. Using GC (Gas-Chromatograph, HP 6890), DME and methanol were measured by Flame Ionized Detector (FID) and H _2. CH ₄ , CO, O ₂ was measured by TCD (Thermal Conductivity Detector). Columns were PLOT U (Aglient) and Molecular sieve 5A (Alglient). And CO ₂ was measured by NDIR (Non-Dispersive Infrared, HORIBA 554JK) analyzer.

The DME conversion rate was calculated from the gas concentration at the inlet and outlet of the catalytic reaction part by the formula DME conversion (%) = (([DME _in ]-[DME _out ]) / [DME _in ]) ㅧ 100. The yield ratio of the reactants was determined by standard values before measurement, and CO ₂ was expressed as (generated CO ₂ ?? 5% supplied CO ₂ ). Production (%) = ((react gases yield ratio / ((H ₂ + CO + CH ₄ + CO ₂ ) yield ratio) ㅧ DME conversion ratio (%))), and the sum of each mixture of DME conversion The temperature of SR catalyst was carried out under steady conditions from 200 ° C to 450 ° C.

The NOx purification rate was evaluated using commercialized LNT (18 mm diameter, 15 mm length, 400 cpsi, cordierite, Umicore). Due to the decrease in temperature due to the heat conduction of the exhaust gas in the SR + LNT catalyst, the temperature of the SR catalyst in the front and the LNT in the rear is different by about 50 ° C. NOx purification rate was measured by Fourier Transform Infrared Spectroscopy (I2000, MIDAC). Temperature was expressed based on LNT, and the experiment was performed under transient conditions from 200 ° C to 450 ° C.

A switching valve was installed in front of the SR catalyst to supply the DME to the SR + LNT composite device or LNT. NOx conversion (%) = (([NOx _in ]-[NOx _out ]) / [NOx _in ]) ㅧ 100 was obtained. Details of the experimental conditions are shown in Table 1 below.

Experimental Example 3

After performing the DME SR catalysis using the experimental apparatus and method described above using the SR catalysts 1 to 3 prepared in Examples 1 to 3, the DME conversion rate and the H ₂ production rate were measured and are shown in FIG. 4A.

Experimental Example 4

Except for using the SR catalyst 4-1 to 4-3 prepared in Example 4 as the SR catalyst was measured in DME conversion and H ₂ production in the same manner as in Experimental Example 3 shown in Figure 4b.

Experimental Example 5

Except for using the SR catalyst 5-1 to 5-3 prepared in Example 5 as the SR catalyst was measured in DME conversion and H ₂ production in the same manner as in Experimental Example 3 shown in Figure 4c.

Experimental Example 6

Except for using the SR catalysts 6-1 to 6-3 prepared in Example 6 as the SR catalyst was measured in DME conversion and H ₂ production in the same manner as in Experimental Example 3 shown in Figure 4d.

Referring to Figures 4a to 4d shown the results of Experimental Example 3 to 6 will be described the factors influencing the H ₂ production rate in the SR catalyst.

First, it can be seen from FIG. 4A that the H ₂ generation rate in the SR catalyst is affected by the Cu content. I.e., which it showed 56% at the 350 ℃ r-Al ₂ O ₃ in the Cu 10%, 20%, and 30% a mixture of SR catalyst 1-3 in SR catalyst _{1 (Cu10 / r-Al 2} O 3), This is because it showed the highest H ₂ production rate. Therefore, the Cu content was found to be optimal among 10%, 20%, and 30%. In Experimental Examples 4 to 6, three zeolites were added to SR catalyst 1 in which 10% Cu was mixed with r-Al ₂ O ₃ . SR catalysts 4-1 to SR catalyst 6-3, prepared to include in different amounts, were used.

Among SR catalysts mixed with zeolites from FIGS. 4B to 4D in which the results of Experimental Examples 4 to 6 are shown, in particular, SR catalyst 4-2 (Modenite 10%), SR catalyst 5-3 (Zeolite β 20%) SR It can be seen that Catalyst 6-1 (ZSM5 5%) showed a high H ₂ production rate. The difference in the H ₂ production rate according to the content of zeolite depends on the characteristics of each zeolite. In particular, the SR catalyst mixed with Modenite 10% showed 58% at 300 ° C and 73% at 350 ° C. H ₂ production rate was shown. This is for geotinde showing a 48% improvement than about 10% of the H ₂ generation rate, the existing Cu10 / r-Al ₂ O ₃ catalyst claimed at 300 ℃, because Mordenite has become a methanol when SR reaction product than other zeolites H ₂ It is expected to be more advantageous for production. Therefore, it can be seen that proper mixing of zeolite with r-Al ₂ O ₃ improves DME hydrolysis and is advantageous for H ₂ generation at low temperatures.

On the other hand, although not shown, due to the reverse water gas reaction at 500 ℃, the CO production rate increased with the decrease of hydrogen production rate in all catalysts, CH ₄ was produced by DME decomposition.

Compared with the results of Experimental Example 3 described above, the results of Experimental Examples 4 to 6 show that Cu 10 / r-Al ₂ O ₃ and zeolite promote the DME SR reaction because the zeolite promotes the DME SR reaction. Since R-Al ₂ O ₃ shows a significant advantage in improving H ₂ and CO ₂ production rates, subsequent experiments show that SR catalyst 4-2 [Cu10 / r-Al ₂ O ₃ + MD10%] catalyst has the best H ₂ production rate. It was experimented using.

Experimental Example 7

In general, about 5% and 10% of CO ₂ and O ₂ are present in the exhaust gas of vehicles driving in the lean driving range (λ = 1.5). In order to use LNT as a post-treatment device, it is necessary to reduce the concentration of O ₂ to a periodically rich operating range. Therefore, SR catalyst 1 or SR catalyst 4-2 was used as the SR catalyst, and H ₂ production rate and O ₂ conversion rate were measured in the same manner as in Experimental Example 3 except that CO ₂ and / or O ₂ were present. Shown in

In more detail, Figure 5 (a) is a result of performing the SR reaction using SR catalyst 1 and the presence of 5% CO ₂ and measuring the H ₂ production rate and O ₂ conversion rate, Figure 5 (b) to Figure 5 (d) shows the result using the SR catalyst 4-2, and resulting in _{CO 2 5%, CO 2 5} % + O 2 0.5%, CO 2 5% + O 2 1% conditions.

Compared with the results of Experimental Examples 3 to 6 in which the SR reaction was performed under the absence of CO ₂ , it can be seen that the H ₂ production rates decreased by up to 15%, respectively. In particular, when 5% CO ₂ is present (FIG. 5 (a), (b)), SR catalyst 4-2 (Cu10 / r-Al ₂ O ₃ + Md10) is SR catalyst 1 (Cu10 / r -Al ₂ O ₃ ) is up to 25% higher H ₂ production rate, which is the effect of physically mixed Mordenite. No other side reactions occurred due to the presence of CO ₂ in the SR reaction. And when O ₂ is present [Fig. 5 (c), (d)], the partial oxidation reaction occurs before the SR reaction, and the H ₂ production rate is lower than when O ₂ is not present [Fig. 5 (b)]. It can be seen that the CO ₂ production rate is increasing. And H ₂ generation rate starts to increase from 350 degreeC or more after the partial oxidation reaction (FIG. 5 (c)). This tendency is more evident when the concentration of O ₂ is 1% (Fig. 6 (d)). In the presence of O ₂ , a closer look at the DME SR reaction shows that the DME is temporarily changed from SR catalyst to a hydrocarbon species (HCHO, HCOOH, HCOO, etc.) and then reduced back to H ₂ and CO ₂ . Due to the presence of ₂ , these intermediates do not oxidize with O ₂ to produce H ₂ , resulting in a decrease in H ₂ production and an increase in CO ₂ .

Experimental Example 8

NO and NO ₂ are present in DME vehicle emissions under lean driving conditions. Therefore, SR catalyst 1 or SR catalyst 4-2 was used as the SR catalyst, except that NO and / or NO ₂ were present, and the H ₂ production rate and the NO and NO ₂ conversion rate were measured in the same manner as in Experimental Example 3 The results are shown in FIG.

It can be seen from FIG. 6 that when 500 ppm NO and 250 ppm NO ₂ are present, the H ₂ production rate is decreasing.

In particular, as shown in FIG. 6 (a), SR catalyst 1 (Cu10 / r-Al ₂ O ₃ ) has a H ₂ generation rate of 20% at 350 ° C. when 500 ppm of NO is present, and is shown in FIG. 6 (6). As described above, the SR catalyst 4-2 (Cu10 / r-Al ₂ O ₃ + Md10) has a H ₂ generation rate of 38% at 350 ° C. Compared with the results of Experiments 3 to 6 where the SR reaction was performed in the absence of both NO and NO ₂ , H ₂ production rate was reduced by about 40% at 350 ° C., respectively.

In the presence of NO, both catalysts produced CH ₄ at 450 ° C., although not shown, as the reaction temperature increased, CH ₄ production rate also increased by DME decomposition. However, CH ₄ was not produced when 250 ppm of NO ₂ was present as shown in Figs. 6 (c) and (d). There have been two reported CH ₄ production pathways in the DME SR reaction. DME decomposition, and CO methanation. CH ₄ can be generated through hydrogenation of the CH ₃ species formed by DME decompsition, but CH ₃ adsorbed on the catalyst surface when 250 ppm of NO ₂ is present in the O ₂ species produced when NO ₂ is reduced. *) increase because the partial oxidation of to CO ₂ is CO ₂ generation rate and by, CH ₄ is predicted to be not generated.

Coexistence of 250 ppm NO ₂ reduced the H ₂ production rate by about 45% as shown in FIGS. 6 (c) and (d). The presence of NO ₂ causes partial adsorption on the surface of the SR catalyst, causing blocking of the SR reaction, and due to the oxidation reaction of the O ₂ species generated when NO ₂ is reduced to N ₂ [Fig. 6 (b) )] H ₂ production rate is further reduced, CO ₂ production rate is increasing results. From more than 400 ℃ station aqueous reaction gas to CO ₂ production rate decreases and makin assumed CO production rate increases, some researchers are also claimed to be generated because CO decomposition of the methanol generated by the hydrolysis of DME.

Until now, research on DME SR catalysts has been mainly focused on generating H ₂ to supply fuel cells. However, since the CO generated from the DME SR reaction causes the deterioration of the fuel cell, research on the fuel cell SR catalyst has been conducted to improve CO ₂ selectivity by minimizing CO generation. However, in the present invention, since the reducing agent generated from the SR catalyst, that is, H ₂ and CO, is used to improve the performance of the reducing agent of the LNT and the DME engine, the CO generation is not a problem as long as CO is also an excellent reducing agent of the LNT and an anti-knocking agent.

In the presence of 250 ppm of NO _{2 in the} Cu 10 / r-Al ₂ O ₃ + Md 10 catalyst (FIG. 6 (c)), at least 90% was reduced to NO at 250 ° C. This is expected to be reduced to NO again by reacting with CH ₃ O, an intermediate product produced during the SR reaction. As shown in Figure 6 (b) and (c) the NO purification rate was reduced to more than 70% and 90% N ₂ at 300 ℃, showing a higher purification rate than the Cu 10 / r-Al ₂ O ₃ catalyst It can be seen.

In general, Cu-based / r-Al ₂ O ₃ catalysts are also widely known as HC-SCR catalysts capable of reducing NOx. In the presence of NO and NO ₂ , the sequence of DME SR reaction is that NO and NO ₂ are SR catalysts. It can be seen that the reduction reaction is performed first at, and then H ₂ is generated from the SR reaction.

Experimental Example 9

SR catalyst 4-2 was used as the SR catalyst, except that NO and / or O ₂ were present, the H ₂ production rate and the NO and O ₂ conversion rate were measured in the same manner as in Experimental Example 3, and the results are shown in FIG. 7. Indicated.

The coexistence of NO and O ₂ during the SR reaction greatly reduces the H ₂ production rate. When NO 500ppm and O ₂ 1% coexistence does not exist, the O ₂ as shown in Fig. 7 (b) than the Fig. 7 (a)] H ₂ generation rate is, and further reduced, O ₂ at 400 ℃ 80 % Is oxidized while NO is 38% reduced. In the reaction sequence, O ₂ is first oxidized and then NO is reduced, and the H ₂ generation rate is 45% at 450 ° C. after the oxidation of O ₂ and the reduction of NO are completed.

In addition, O ₂ 5% coexistence [FIG. 7 (c)] showed that most of CO ₂ was produced by oxidation reaction with O ₂ in the catalyst, and almost no H ₂ was produced. NO was also not reduced, and CH ₄ was not produced as a byproduct.

Therefore, from the results of Experiment 9, in the present invention to use the exhaust gas of the DME vehicle to modify the DME to H ₂ in the SR catalyst to be used as a reducing agent of the LNT, H is supplied as a reducing agent to improve the NOx purification rate of the DME vehicle. ₂ It is understood that it is important to reduce O ₂ because the higher the production rate, the better.

Experimental Example 10

By using the above-described experimental apparatus and method including the SR + LNT catalyst in which the SR catalyst is installed in the front of the LNT, reducing agents such as H ₂ and CO generated by the SR reaction can be supplied to the LNT to improve de-NOx performance. In order to know whether the NOx purification rate was measured and the results are shown in Figure 8. (Total flow: 2L / min, DME 0.7%, H ₂ O 5%, NO 500ppm, N ₂ balance, lean / rich time = 55 / 5, lean: O ₂ 10%, rich: O ₂ 0%) SR + LNT catalyst is SR catalyst 1 + LNT [SR (Al) + LNT], SR catalyst 4-2 + LNT [SR (MD10) + LNT], SR catalyst 5-3 + LNT [SR (ZB20) + LNT], SR catalyst 6-1 + LNT [SR (ZM5) + LNT].

From Fig. 8, the NOx purification rate of SR (MD10) + LNT catalyst using SR catalyst 4-2 [Cu10 / r-Al ₂ O ₃ + Md10], which had the highest H ₂ generation rate among SR catalysts, was about 350 ° C. than LNT. 15% improvement. On the other hand, the NOx purification rate of SR (ZB20) + LNT catalyst using SR catalyst 5-3 (Cu10 / r-Al ₂ O ₃ + ZB20) was the lowest. This is presumably because SR catalyst 5-3 has the lowest H ₂ generation rate generated from the SR reaction using the exhaust conditions of the DME vehicle. As a result, the higher the H ₂ generation rate in the SR catalyst, the higher the NOx purification rate in the SR + LNT catalyst. However, at temperatures above 400 ° C, the NOx purification rate is decreasing. This is because the amount of NO adsorption of LNT at high temperature decreases because the amount of NO adsorbed with H ₂ decreases.

Experimental Example 11

In general, in an automobile using LNT as a post-treatment system, since NO ₂ is reduced more easily than NO, oxidation of NO → NO ₂ in an oxidation catalyst (OC) located at the front end improves the NOx purification rate.

: from 200℃ to 350℃:SR+LNT, : over 350℃:LNT )By using the above-described experimental apparatus and experimental method including the SR + LNT catalyst provided with the SR catalyst in front of the LNT, it is possible to perform the same function as the nitrogen oxide reduction and anti-knocking device of the present invention shown in FIG. After supplying 250ppm NO250ppm + NO ₂ so that the catalyst part has the same effect as the SR catalyst installed, it is possible to supply a reducing agent such as H ₂ and CO generated by the SR reaction to the LNT to improve the de-NOx performance. The purification rate was measured and the results are shown in FIG. 9. (Total flow: 2L / min, DME 0.7%, H ₂ O 5%, NO 500ppm or NO250ppm + NO ₂ 250ppm, N ₂ balance, lean / rich time = 55 / 5sec, lean: O ₂ 10%, rich: O ₂ 0%,

: from 200 ℃ to 350 ℃: SR + LNT, : over 350 ℃: LNT)

However, since NO ₂ oxidized in the Oxidation Catalyst (OC) reduces the H ₂ generation rate in the SR catalyst, it can be seen that the NO x purification rate also decreased in the SR + LNT catalyst. While NOx conversion efficiency of the LNT is increased 15% in 12%, 400 ℃ at 350 ℃ than to supply NO 500ppm 250ppm + NO ₂ 250ppm NO during supply. In addition, the NOx purification rate of SR + LNT catalyst at a temperature of 400 ° C. or more shows a greater difference than that of LNT. Therefore, the use of Oxidation Catalyst (OC) with excellent ability to oxidize NO to NO ₂ improves the NOx purification rate of LNT, but rather reduces the NOx purification rate of SR + LNT catalyst. Therefore, OC located in the front of SR + LNT catalyst is more advantageous to use a catalyst with high oxidation power of HC _S and CO and low NO oxidation power emitted by DME engine. In addition, since SR + LNT catalyst exhibits a NOx purification rate almost similar to LNT at a temperature of 350 ° C. or higher, H ₂ produced from SR catalyst cannot be used effectively.

)→LNT(

)]. 그 결과, NOx 정화율은 350℃까지는 SR+LNT 촉매와 비슷한 경향을 나타내었으며, 350℃ 이상부터는 LNT와 비슷한 경향을 나타내는 것을 알 수 있었다. Therefore, H ₂ produced from SR catalyst was supplied to LNT up to 350 ° C and DME was directly supplied to LNT using a switching valve at 350 ° C or higher to evaluate NOx purification rate again [SR + LNT (

) → LNT (

)]. As a result, the NOx purification rate showed a tendency similar to SR + LNT catalyst up to 350 ° C, and similar to LNT above 350 ° C.

As a result, when the after-treatment apparatus is configured to include the SR + LNT catalyst, such as nitrogen oxide reduction and anti-knocking apparatus according to the embodiments of the present invention shown in Figures 1 and 2, the exhaust gas and the H ₂ produced from the SR catalyst using heat is used as a reducing agent for the exhaust aftertreatment device LNT when the temperature is lower than the reference temperature at 350 ° C, which is the highest active temperature of the LNT. It can be seen that the configuration that can be supplied as an engine performance improver is extremely efficient.

Experimental Example 12

: LNT, DME 0.7%,

:LNT, DME 1%,

: LNT , DME 1.5%,

:LNT, DME 1.8%,

: Cu10/r-Al₂O₃+Md10+LNT : DME 0.7%,

:Cu10/r-Al₂O₃+Md10+LNT : DME 1.5% ,

: Cu10/r-Al₂O₃+LNT : DME 1.5%, (b) LNT : DME 1.8% , Cu10/r-Al₂O₃+Md10+LNT : DME 1.5% ) 또한, LNT와 SR+LNT 촉매에 환원제로써 DME가 공급될 때 엔진의 공연비(λ)를 측정하여 도10(b)에 나타내었다. When O ₂ is not fully oxidized and 1% of O ₂ is present in the OC catalyst during rich condition (5sec) of supplying DME, LNT and SR catalyst 4-2 + LNT [Cu-10 / r-Al ₂ O ₃ + Md 10 + LNT] in the NOx purification rate was measured and the results are shown in Figure 10 (a). (Total flow: 2L / min, H ₂ O 5%, NO 500ppm, CO ₂ 5%, lean / rich time = 55 / 5sec, lean: O ₂ 10%, rich: O ₂ 1% (a)

: LNT, DME 0.7%,

: LNT, DME 1%,

: LNT, DME 1.5%,

LNT, DME 1.8%,

: Cu10 / r-Al ₂ O ₃ + Md10 + LNT: DME 0.7%,

: Cu10 / r-Al ₂ O ₃ + Md10 + LNT: DME 1.5%,

: Cu10 / r-Al ₂ O ₃ + LNT: DME 1.5%, (b) LNT: DME 1.8%, Cu10 / r-Al ₂ O ₃ + Md10 + LNT: DME 1.5%) Also, LNT and SR + LNT catalysts The air-fuel ratio (λ) of the engine when the DME was supplied as a reducing agent was measured and shown in FIG. 10 (b).

In general, LNT adsorbs NOx in a lean condition and NOx adsorbed in a rich lean condition is reduced to N ₂ , but when 1% of O ₂ is present, H is released from the SR catalyst. ₂ is produced but LNT and SR + LNT catalysts have low NOx purification rates because they do not produce a reducing atmosphere in the LNT.

Therefore, the DME supply was increased from 0.7% to 1.0%, 1.5% and 1.8% to improve the NOx purification rate of LNT. When 1.5% of DME is supplied, the NOx purification rate of LNT is improved to 60% at 350 ° C., and the NOx purification rate of SR catalyst 4-2 + LNT catalyst is about 15% higher than that of LNT. The NOx purification rate is about 5% higher at 350 ° C than when 1.8% DME is fed to the LNT. This suggests that the use of H ₂ as a NOx reducing agent is advantageous for the NOx purification rate, and it reduces the fuel penalty of 3000 ppm by reducing the single injection amount of DME from 1.8% to 1.5%. As a result, the presence of O ₂ during the rich period of supplying DME increases the amount of DME supplied. Therefore, the reduction of O ₂ is important. This reduction function is a role that should be played by the OC in the front of the SR + LNT catalyst.

The NOx purification rate of the SR catalyst 4-2 + LNT catalyst mixed with zeolite was higher than that of the SR catalyst 1 + LNT catalyst.

Referring to FIG. 10 (b), when 1.8% of DME is supplied to LNT, λ = 0.7, and λ = 0.82 when 1.5% of DME is supplied to SR + LNT catalyst. Using only LNT as a post-treatment device in the DME engine has a much richer operating range (λ = 0.7) than the SR + LNT catalyst, resulting in increased fuel penalty. These experimental results show the usefulness and necessity of the nitrogen oxide reduction and anti-knocking device of the present invention including the SR + LNT catalyst.

Experimental Example 13

SR catalyst evaluating the NOx purification rate in SR catalyst 1 (Cu10 / r-Al ₂ O ₃ ), SR catalyst 4-2 (Cu10 / r-Al ₂ O ₃ + Md10) catalyst and SR + LNT catalyst after SR reaction experiment The TPO test results of 4-2 (Cu10 / r-Al ₂ O ₃ + Md10) are shown in FIG. 11.

Deposition of carbon occurs at the Br ㆈ nsted acid site and is a major cause of inactivation in SR catalysts using zeolites, but no clear solution has been found. SR catalysts usually deposited with carbon reduce the H ₂ production rate due to the decrease in the activity of the SR catalyst.

Referring to FIG. 11, since r-Al ₂ O ₃ is composed of a weak acid point, carbon deposition does not occur when 500 ppm of NO is present in SR catalyst 1 (Cu10 / r-Al ₂ O ₃ ), but SR catalyst 4- _{2 (Cu10 / r-Al 2} O 3 + Md10) catalyst, there can be seen that they have all of the carbon deposition occurs when the NO 500ppm or NO ₂ 250ppm coexist because of the strong acidic sites of Mordenite, NO ₂ 250ppm coexistence NO 500ppm coexistence time signal The carbon deposition was low. This is because O ₂ generated as NO ₂ is reduced to N ₂ is oxidized with the deposited carbon.

However, as shown in FIG. 11, it can be seen that in the SR + LNT catalyst, carbon deposition of the SR catalyst mixed with zeolite can be suppressed. In other words, in the SR + LNT catalyst, O ₂ is present at a high concentration (about 10%) during the lean condition, and thus carbon deposition does not occur in the SR catalyst because the O ₂ is oxidized with carbon deposited during the rich period. And as a result, the H ₂ production rate is not reduced.

The above experimental results show that the problem of deposition of carbon possessed by the SR catalyst using the conventionally known zeolite is effectively solved in the nitrogen oxide reduction and anti-knocking apparatus including the SR + LNT catalyst of the present invention. That is, in the nitrogen oxide reduction and anti-knocking device of the present invention, carbon deposited on the SR catalyst is oxidized during O ₂ and lean period included in the exhaust gas, so that carbon deposition does not occur on the SR catalyst.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

100: nitrogen oxide reduction and anti-knocking device 110: first catalyst
120: second catalyst 130: exhaust gas main supply pipe
140: switching valve 150: exhaust gas supply pipe
160: first reducing agent supply pipe 170: second reducing agent supply pipe
180: injector nozzle 190: third catalyst portion

Claims (14)

A first catalyst part including a SR catalyst reacting with dimethyl ether to generate a reducing agent;
A second catalyst part located after the first catalyst part and including an LNT catalyst reacting with a reducing agent supplied from the first catalyst part;
A first reducing agent supply pipe for supplying a reducing agent generated by the first catalyst part to the DME vehicle engine to be supplied to a DME vehicle engine and used as an anti-knocking agent of the DME vehicle engine;
A second reducing agent supply pipe for supplying a reducing agent generated by the first catalyst portion to the second catalyst portion to be used as a reducing agent of the LNT catalyst;
It includes a temperature sensor for sensing the temperature of the second catalyst,
If the temperature of the second catalyst portion detected by the temperature sensor is 350 ℃ or more, the reducing agent generated in the first catalyst portion is supplied to the DME vehicle engine through the first reducing agent supply pipe,
When the temperature of the second catalyst portion detected by the temperature sensor is less than 350 ℃, reducing agent generated in the first catalyst portion is supplied to the second catalyst portion through the second reducing agent supply pipe to the nitrogen oxide reduction and anti-knocking device .
delete delete The method of claim 1,
The reducing agent is nitrogen oxide reduction and knocking prevention device, characterized in that any one or more of H ₂ and CO.
The method of claim 1,
Nitrogen oxide reduction and anti-knock apparatus, characterized in that the first catalyst is supplied to the exhaust gas discharged from the engine of the DME vehicle and dimethyl ether injected from the injector.
The method of claim 5, wherein
Dimethyl ether supplied to the first catalyst portion is nitrogen oxide reduction and knock prevention device, characterized in that less than 5% of the total supply gas flow rate.
The method of claim 1,
The SR catalyst is Cu-based / r-Al ₂ O ₃ , nitrogen oxide reduction and anti-knocking apparatus characterized in that the cell density is supported on a carrier of 100 cpsi ~ 1200 cpsi to form the SR catalyst body. The method of claim 7, wherein
Copper content of the SR catalyst is nitrogen oxide reduction and anti-knock apparatus, characterized in that 5% to 40% by weight relative to the total weight of the SR catalyst.
The method of claim 7, wherein
The SR catalyst is nitrogen oxide reduction and anti-knocking apparatus further comprises a zeolite 30% by weight or less based on the total weight of the SR catalyst.
The method of claim 9,
The SR catalyst is a nitrogen oxide reduction and anti-knocking apparatus, characterized in that 10% by weight of Modenite in Cu-based / r-Al ₂ O ₃ having a copper content of 10% by weight.
The method of claim 1,
Nitrogen oxide reduction and anti-knock apparatus, characterized in that the temperature between the first catalyst portion and the second catalyst portion is 300 ℃ to 350 ℃. The method according to any one of claims 1 and 4 to 11,
Nitrogen oxide reduction and anti-knock prevention, further comprising a third catalyst portion located in front of the first catalyst portion and including a diesel oxidation catalyst for oxidizing the hydrocarbon or carbon monoxide in the exhaust gas supplied to the first catalyst portion. Device.
12. A DME motor vehicle comprising the nitrogen oxide reduction and anti-knocking device according to any one of claims 1 and 4.
DME vehicle comprising a nitrogen oxide reduction and anti-knock device of claim 12.

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