JP2003184546A - Method and device for catalytic conversion of gaseous pollutants in combustion engine exhaust gas - Google Patents

Abstract

The present invention relates to the conversion of gaseous pollutants in the exhaust gas of a combustion engine using a catalyst. The present invention provides both devices and methods for improving the catalytic conversion of these materials. The device includes a porous catalyst holding support. The porous catalyst holding support,
It has a first surface and a second surface. The first surface allows the inflow of exhaust gas, and the second surface allows the inflow of exhaust gas. Preferably, the first surface and the second surface are on opposite sides of the substrate from each other. The method includes contacting the exhaust gas with a catalyst. The catalyst includes a porous catalyst holding support having an open pore structure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the field of catalytic conversion of gaseous pollutants.

[0002]

Combustion engines can be used, on the one hand, in real estate combustion plants and, on the other hand, in motor vehicles. Unfortunately, both types of engines produce gases containing harmful substances that significantly pollute the environment. These harmful substances or pollutants are generally carbon monoxide (C
O), hydrocarbons (HC), and nitrogen oxides (NO _x ).

[0003] Over the years, governments around the world have been reducing their allowable emission limits for these pollutants. In order to comply with these requirements, those skilled in the art are striving to optimize the combustion process of combustion engines, especially diesel and gasoline engines. These optimization techniques have significantly reduced emissions of harmful substances. However, the known optimization process is not sufficient to meet current legal restrictions.

Consequently, there is a need for catalysts that convert pollutants into harmless compounds such as water, carbon dioxide and nitrogen in order to further reduce the amount of pollutants emitted with the exhaust gas.

As an example, it is known to utilize a three-way catalyst. These types of catalysts substantially convert nitrogen oxides, hydrocarbons, and carbon monoxide into low harmful substances.

It is also known to utilize SCR catalysts. SRC catalysts are used in particular for treating the exhaust gases of combustion engines of real estate combustion plants. The abbreviation SCR stands for "selective catalytic."
"reduction". This is because the nitrogen oxides contained in the exhaust gas are even in oxygen by adding ammonia to the exhaust gas and bringing the mixture of nitrogen oxides, ammonia and other exhaust gas components into contact with the SCR catalyst. It means that it is chemically reduced to nitrogen and water.

These types of catalysts are coated on the surface of a solid support as a layer commonly referred to as a "washcoat layer". The solid support can be, for example, in the form of a palette or tablet containing alumina.

Known catalyst support systems may be designed, for example, in the form of flow-through substrates. Flow-through substrates generally have a honeycomb structure with multiple channels. The exhaust gas flows through the plurality of flow paths. The plurality of channels extend from the inlet to the outlet and are made of metal or ceramic. In these structures, the catalytic coating can be applied to the inner surface of the flow channel.

Alternatively, the flow-through substrate is made entirely of one or more catalytically active materials. To this end, one or more catalytic materials are mixed with additional components such as pore formers, plastic materials and the like. Next, extrusion molding is performed to form a desired honeycomb structure.

[0010]

In the flow-through substrate, the exhaust gas flows along the flow path. In order to catalytically convert pollutants contained in the exhaust gas, the exhaust gas components leave the main flow direction of the exhaust gas and diffuse into the catalytic coating or bulk catalytic material, where the catalytic activation center of the catalytic material. Need to contact.

Thus, before the gaseous pollutants can react at the catalytic center, they are diffused by diffusion.
It needs to be transported into the catalytic material. Furthermore, after catalytic conversion, the reaction products have to diffuse outside the catalytic material and rejoin the exhaust gas stream in the flow path.

Diffusion of gaseous pollutants occurs only when the energy of the pollutants is above a certain activation energy. Therefore, based on the temperatures of the exhaust gas and the catalyst, the conversion of gaseous pollutants can be limited by the transport mechanism of these materials. That is, not only the reaction rate of the catalyst center, but also the transport of pollutants to the catalyst center determines the rate of catalyst conversion of pollutants. This means that in the case of unfavorable reaction conditions, the contaminants do not reach a significant part of the catalyst center. As a result, it becomes impossible to cause chemical conversion of harmful substances at the catalyst center with high probability.

Accordingly, there remains a need to improve the flow of reactants towards the catalyst material and the flow of chemical products away from the catalyst material. The present invention provides one solution.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to catalytically converting gaseous pollutants in combustion engine exhaust gases. The present invention provides both devices and methods for improving the catalytic conversion of these materials.

According to one embodiment, the present invention provides a device for catalytically converting harmful substances contained in exhaust gas of an internal combustion engine. The device includes a porous catalyst-supporting support. The porous catalyst holding support is
It has a first surface and a second surface. The first surface allows the inflow of exhaust gas and the second surface allows the outflow of exhaust gas. Suitably, the first surface and the second surface are located on opposite sides of the substrate from each other.

The porous catalyst-supporting support may contain and / or be covered with a catalytic material. Alternatively, the first surface may be in contact with the first catalyst layer, and / or
The second catalyst layer may contact the second surface. Wherever the catalyst layer is applied, it is applied so as not to prevent the exhaust gas from flowing from the first surface to the second surface.

According to a second embodiment, the present invention provides a method for converting harmful substances contained in exhaust gas of an internal combustion engine using a catalyst. The method includes contacting exhaust gas with a catalyst. The catalyst comprises a porous catalyst retention support having an open pore structure. The support has a first surface and a second surface. Exhaust gas enters the support through the first surface, passes through the support, and exits through the second surface.

The present invention is a method for converting a pollutant contained in exhaust gas of an internal combustion engine using a catalyst, the method including a step of bringing the exhaust gas into contact with the catalyst, the catalyst comprising: A porous catalyst-supporting support having an open pore structure, the support having a first surface and a second surface;
The exhaust gas flows into the support through the first surface,
The above objects are achieved by passing through the support and out the catalyst through the second surface.

At least one catalyst layer may be on the first surface and / or the second surface.

The support may include a wall flow filter made of an inert ceramic material.

The support may include a wall flow filter produced by extruding a catalyst material.

The internal combustion engine is a diesel engine or a gasoline fuel-efficient direct injection engine, and the catalyst is a NO _x storage catalyst for reducing nitrogen oxides, SC.
It may be R catalyst or HC-DeNO _x catalyst.

The internal combustion engine is a diesel engine or a gasoline fuel-efficient direct injection engine, and the catalyst is a NO _x storage catalyst for reducing nitrogen oxides, SC.
It may be R catalyst or HC-DeNO _x catalyst.

The internal combustion engine may be a diesel engine, and the catalyst may be a diesel oxidation catalyst that oxidizes carbon monoxide, hydrocarbons, and soluble organic compounds attached to soot particles.

The internal combustion engine may be a diesel engine, and the catalyst may be a diesel oxidation catalyst that oxidizes carbon monoxide, hydrocarbons, and soluble organic compounds attached to soot particles.

The internal combustion engine is a stoichiometrically operated gasoline engine, and the catalyst is nitrogen oxides.
A three-way catalyst that simultaneously converts hydrocarbons and carbon monoxide may be used.

The internal combustion engine is a stoichiometrically operated gasoline engine, and the catalyst is nitrogen oxides.
A three-way catalyst that simultaneously converts hydrocarbons and carbon monoxide may be used.

The present invention is a device for converting a harmful substance contained in exhaust gas of an internal combustion engine by using a catalyst, the device including a porous catalyst holding support having an open pore structure. The pore structure achieves the above object by having a first surface that allows the inflow of the exhaust gas and a second surface that allows the outflow of the exhaust gas.

The porous catalyst holding support may include a catalyst material.

The catalyst material is an HC-adsorber, a NO _x storage catalyst, a diesel oxidation catalyst, an SCR catalyst, HC-De.
It may be a NO _x catalyst or a three-way catalyst.

The porous catalyst holding support may be in the form of a wall flow filter.

A catalyst layer may be fixed to the first surface and / or the second surface.

The porous catalyst holding support may include an inert ceramic material.

The present invention is an exhaust system comprising said device, said device being located in an exhaust gas conduit,
The first object is achieved by arranging the first surface upstream of the second surface.

The device may span the cross section of the exhaust gas conduit.

[0036]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a device and method for catalytically converting harmful substances contained in exhaust gas of an internal combustion engine. According to the invention, the exhaust gas is contacted with the catalyst. The catalyst comprises a porous catalyst retention support having an open pore structure. The support has a first surface and a second surface. Exhaust gas is flowed into the support through the first surface and passed through the pore structure of the support,
Then, the catalyst is allowed to flow out through the second surface.

This disclosure is not intended to be an academic paper on the catalytic conversion of gaseous pollutants. The reader makes appropriate reference to the available text regarding the background for this purpose.

In accordance with the present invention, high catalyst conversion is achieved by forcing exhaust gas through the fine catalytically active material of the catalyst. According to this action
The possibility of contaminants coming into contact with the catalyst center increases, which in turn exposes the catalyst center of catalyst material directly to the exhaust gas stream.
Contrary to the prior art, according to the method of the invention, the exhaust gas stream is in accelerated contact with the catalyst center. As the exhaust gas passes through the catalyst, all catalytic material is directly exposed to the exhaust gas stream.

According to one embodiment, the present invention provides a device that can be utilized to facilitate the operation of directing exhaust gas to a catalyst. The device includes a porous catalyst-supporting support having a first surface and a second surface. The first surface and the second surface are on different sides of the support, preferably
Located on opposite sides of the support.

The support is preferably located in the exhaust system in the direct path of the exhaust gas. The support is
The first surface is arranged upstream of the second surface. The phrase "exhaust system" refers to any structure through which exhaust gas flows during exhaust of the engine. For example, an exhaust conduit is relevant. The device is arranged in a path through which the exhaust gas stream directly flows and is porous so that the exhaust gas flows in through the first surface and out of the second surface. Preferably, the device spans most or all of the cross-section of the exhaust conduit so that some or all of the exhaust gas is forced through the device. For example, the device is arranged perpendicular to the length of the exhaust conduit and spans the entire cross section of the exhaust conduit.

The support itself comprises the catalytic material.
Alternatively, the support can be covered with a catalytic material. The coating of catalytic material forms the catalytic centers in the pores of the support.
The exhaust gas can be converted to reduce harmful compounds in the pores of the support by continuing to pass through the support.

In the preferred embodiment of the invention, the porous support is in the form of a wall flow filter. The filter may be made entirely of catalytic material. Alternatively, the filter can be made by forming an inert material followed by a catalytic coating. The wall flow filter may be manufactured by extruding a catalyst material.

Alternatively, the catalyst layer may be fixed to the first surface and / or the second surface separately from forming the support from the catalyst material or separately from covering the support with the catalyst material. . When the catalyst layer is adhered to the first surface and / or the second surface, the catalyst layer needs to be sufficiently porous so that exhaust gas can pass through the catalyst layer.

The device of the invention is suitable for combustion engines used in real estate combustion plants and combustion engines used in motor vehicles. Based on the type of combustion engine, diesel engine or gasoline engine,
The catalyst is, for example, a hydrogen adsorber (HC-adsorber), NO _x.
Storage catalyst, diesel oxidation catalyst, SCR catalyst, HC-D
It can be an eNO _x catalyst or a three-way catalyst.

In a second embodiment, the present invention provides a diesel engine or a gasoline fuel efficient direct injection engine (l
ean burn direct injection
A method for cleaning exhaust gas of an engine is provided. Suitably, the porous support is a NO _x storage catalyst, S
In the form of a wall-flow filter having a catalytic material comprising a CR catalyst or HC-DeNO _x catalyst, and therefore, the nitrogen oxides in the exhaust gas of the engine is reduced.

In this method, the exhaust gas leaves the engine and
The pollutants are transported to the catalytically active center of the catalyst by directional movement caused by the exhaust power of the exhaust gas as it travels through the exhaust conduit. Pollutants
It is not transported by diffusion. Therefore, the limitation of catalytic conversion of harmful substances due to the efficiency of transport of pollutants is largely avoided.

In this embodiment, the exhaust gas is forced into the porous support through the first surface and exits the support through the second surface. The support is located where the exhaust gas flows. Therefore, it is not necessary to independently change the flow direction of the exhaust gas for the purpose of exposing the exhaust gas to the catalyst.

Either the support itself or the constituent parts of the support are catalytic materials. The catalytic material may form a layer on the first surface and / or the second surface, as described above. Additionally or alternatively, the catalytic material is
A coating may be formed on the pores of the substrate, or the substrate itself may be used.

In another embodiment of the present invention, the method is utilized to clean the exhaust gas of a stoichiometrically operated gasoline engine. The porous support is for simultaneously converting nitrogen oxides, hydrocarbons, and carbon monoxide contained in the exhaust gas of the engine,
It is a wall flow filter shape having a catalyst coating containing a three-way catalyst.

The present invention may be more fully understood with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view illustrating the general structure and operation of a known catalyst system for converting pollutants in the exhaust gas of a combustion engine. The porous support 1 is formed, for example, by the walls of the channels of a honeycomb-shaped support through which a flow passes. The porous catalyst layer 2 is applied on the surface of the catalyst support 1. This catalyst layer, the so-called washcoat, contains the catalyst center 3. The catalyst center 3 is located on the surface and inside of the catalyst layer 2.

The catalyst layer 2 is exposed to exhaust gas flowing parallel to the surface of the catalyst layer. The flow direction of the exhaust gas flow is indicated by the arrow A shown in FIG.

In order to make contact with the catalyst center 3, the harmful substances of the exhaust gas must diffuse inside the catalyst layer and towards the catalyst center. The main direction of this diffusion operation is oriented transverse to the direction of the exhaust gas flow in the flow path. In FIG. 1, the direction of diffusion operation is
Schematically indicated by arrows B and C. Figure 1
Indicates that the exhaust gas needs to flow into the catalyst layer 2 in the direction shown by the arrow B in order to reach the catalyst center 3 inside the catalyst layer 2. The reaction product of the catalyst conversion needs to diffuse back to the surface of the catalyst layer 2 along the direction indicated by the arrow C. Depending on the temperature of the exhaust gas and the catalyst and the porosity of the catalyst layer, the transport of pollutants to the catalyst center 3 may be delayed, limiting the achievable conversion rate of pollutants.

FIG. 2 is an enlarged cross-sectional view illustrating the principal structure and operation of a device of the present invention for catalytically converting gaseous pollutants in combustion engine exhaust gases. The device comprises a porous support 4. The catalyst layer 2 is applied to each or either of the essentially flat first surface (front surface) and the essentially flat second surface (rear surface) of the porous support 4. This catalyst layer is similar to the catalyst layer shown in FIG.

However, unlike the assembly of FIG.
The exhaust gas does not flow parallel to the surface of the catalyst layer, but forcedly crosses the catalyst layer and the porous support 4. The exhaust gas flows into the catalyst layer 2 on the front surface (first surface) of the porous support 4, passes through the support, and passes through the catalyst layer on the rear surface (second surface) of the porous support 4. , Outflow from this configuration.

As shown in FIG. 2, the exhaust gas is directed in the direction A.
By virtue of this, it is possible to directly expose both the catalyst layer 2 on the front side and the catalyst layer 2 on the rear side of the porous support 4, and thus the catalyst center 3 contained in the catalyst layer 2, to the entire exhaust gas flow. Be certain. The direction A of the flow of exhaust gas through the catalyst layer causes unintended diffusion of exhaust gas in the conventional method shown in FIG. 1, which always requires a specific activation energy in order to cause diffusion of exhaust gas. Change According to the method of the invention, the chemical conversion of pollutants occurring at the catalyst center 3 no longer limits the transport.

As an alternative to the assembly of FIG. 2, the entire porous support may be made of catalytic material. In this case, no separate catalyst coating is required on the surface of the support 4.

Different catalyst materials may be utilized, depending on the type of combustion engine and the harmful substances in the exhaust gas of the combustion engine.

When treating the exhaust gases of diesel engines and gasoline fuel-efficient direct injection engines, NO _x storage catalysts can be utilized to convert nitrogen oxides to harmless substances. Alternatively, by covering the porous support with an SCR catalyst and combining the present invention with the selective catalytic reduction method,
It is also possible to convert nitrogen oxides. Suitable SCR catalyst materials include, for example, V ₂ O ₂ and WO
_3, made from a mixture of TiO _3. In order to carry out the selective catalytic reduction, it is necessary to add ammonia or a precursor substance which can be converted to ammonia as reducing agent to the exhaust gas stream. To remove harmful substances from the exhaust gas of stoichiometrically operated gasoline engines,
A three-way catalyst can be utilized. With these catalysts, reduction of nitrogen oxides and oxidation of hydrocarbons and oxygen monoxide,
Achieved at the same time.

Diesel oxidation catalysts may be utilized to remove harmful substances from the exhaust gas of diesel engines. These catalysts achieve the oxidation of CO and HC and the oxidation of soluble organic components adhering to the soot particles in the exhaust gas of diesel engines.

Finally, HC- for the reduction of nitrogen oxides
DeNO _x catalysts can be utilized for the treatment of diesel engine exhaust gases.

FIG. 3a shows a preferred embodiment of the device of the invention for the conversion of gaseous pollutants in the exhaust gas of combustion engines. The device basically consists of a wall flow filter 5.

The wall flow filter 5 has an inlet channel 6
And outlet channels 7 are arranged alternately. The inlet channel 6 and the outlet channel 7 are separated by a wall element forming the porous support 4.

The inner surface of the inlet channel 6 is covered with the catalyst layer 2. The inlet channel 6 is closed on the downstream side by a plug 8. The outlet channel 7 is closed by a similar plug 8 on the upstream side of the wall flow filter.

Therefore, the exhaust gas flows into the wall flow filter 5 via the inlet flow path 6, but cannot flow out on the downstream side of the flow path. Therefore, the exhaust gas forcibly crosses the separation layer between the two adjacent inlet and outlet passages and the catalyst layer 2, and then passes through the wall downstream through the open downstream side of the outlet passage. Leave the filter 5.

FIG. 3b shows the wall flow filter 5 used for comparison. Contrary to the filter of Figure 3a, the downstream plug 8 has been removed in the wall flow filter of Figure 3b. Therefore, the exhaust gas is
It can pass through the separation wall and flow through the inlet channel 6 of the wall flow filter 5 without forcibly flowing into the outlet channel.

The following examples are intended to further illustrate the method of the present invention. The configuration of the catalyst of FIGS. 3a and 3b is
It was used to compare the method of the present invention for cleaning exhaust gases with conventional methods.

Example 1 The wall flow filter of FIG. 3a was made from silicon carbide (SiC). This wall flow filter has a cell density of 31 cm.
^-2 (200 cpsi; where cpsi indicates the number of cells per square inch), length 15.24 cm
(6 inches) and the diameter is 2.54 cm (1 inch).
The wall flow filter was covered with a conventional diesel oxidation catalyst as a platinum substrate on alumina. The coating was applied from the inlet side of the wall flow filter. The load applied to the filter by the catalyst material was 44 g per liter of filter volume, and the concentration of precious metal was 0.46 g / l.
It was (13 g / ft ³ ).

The HC and CO ignition behavior of this catalyst was measured by a model gas test bench at a space velocity of 25,000 h ^-1 . The results are shown in Fig. 4. The ignition temperature is 152 ° C for CO and 200 for HC.
C was measured.

After these measurements, a wall flow filter having a length of 3 mm was cut on the downstream side. As a result, the plug of the outlet flow passage 7 of the wall flow filter is removed, and the exhaust gas can freely flow through the inlet flow passage without forcibly passing through the wall between the adjacent inlet flow passage and outlet flow passage. Could pass. This situation is shown in Figure 3b.

Again, the ignition temperatures of CO and HC of the catalyst were measured. As a result, the temperature of CO is 185 ° C, and H
The temperature of C was 209 ° C. Results are shown in FIG.

These latter ignition temperatures were clearly higher than those obtained with the configuration shown in FIG. 3a. These results show that the method of the present invention improved exhaust gas cleanliness.

While the present invention has been described and illustrated in some detail, as set forth above, the appended claims should not be limited to the above, but rather the language of the elements recited in the claims and their equivalents. It should be understood that it should have the same scope as equivalents.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view illustrating a schematic structure and operation of a conventional catalyst system.

FIG. 2 is an enlarged cross-sectional view illustrating the schematic structure and operation of the device of the present invention.

FIG. 3a is a schematic diagram showing a wall flow filter shaped catalyst support for removing gaseous pollutants from the exhaust gas of a combustion engine.

3b is a diagram of the wall flow filter of FIG. 3a with the downstream plug of the inflow passage cut.

FIG. 4 is a diagram showing a diesel ignition test when a diesel oxidation catalyst is used and the wall flow filter of FIG. 3a is closed on the downstream side (270p.
_pm, ignition tests in _{C 3 H 6 (C 1)} ).

FIG. 5 is a diagram showing a diesel ignition test using a diesel oxidation catalyst and a wall flow filter of FIG. 3b in an open state at a downstream side (270p.
_pm, ignition tests in _{C 3 H 6 (C 1)} ).

[Explanation of symbols]

2 Porous catalyst layer 3 catalyst center 4 Porous support

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 35/04 F01N 3/02 301C F01N 3/02 301 301E 321A 321 3/08 B 3/08 3/24 ZABE 3/24 ZAB B01D 53/36 101Z 103B 103C (72) Inventor Harald Behnke Germany 64285 Darmstadt, Annastraße 53 (72) Inventor Barry van Zetten Germany 63517 Rodenbach, Northring 32 (72) Inventor Bernd Lesche Germany 63571 Gainhausen, Mittlauer Wek 22 (72) Inventor Roger Staab Germany 63579 Freigericht, Adolf-Amberg-Strasse 10 (72) Inventor Jürgen Gieshof Germany 63599 Bibergemund, Amburgwerksline 10 (72) Inventor Egbert Rocks Germany 63457 Hanau, Greif Enhagenstraße 12 Be (72) Inventor Thomas Kreuzer Germany 61164 Carben, Philip-Rice- Strasse 13 F term (reference) 3G090 AA02 AA03 BA01 EA02 3G091 AA02 AA06 AA17 AA18 AA24 AB02 AB04 AB06 AB13 AB15 BA01 BA14 BA15 BA19 BA39 GA06 GA16 GA17 GB01W GB10W GB17X AB17 BAXBAXBAABABA02 BA01 AB02 BA02 BA01 AB02 BA02 AB01 CC34 EA04 4G069 AA03 AA08 BA01B BB15B BC75B BD05B CA03 CA07 CA08 CA09 CA13 CA14 CA15 CA18 DA06 EA19 EA27 EC28 EE07 EE08 FA03 FB67

Claims (18)

[Claims] 1. A method for converting a pollutant contained in exhaust gas of an internal combustion engine using a catalyst, the method including a step of bringing the exhaust gas into contact with the catalyst, wherein the catalyst has open pores. A structured porous catalyst-supporting support, the support having a first surface and a second surface, the exhaust gas flowing into the support through the first surface, the support comprising: A method of passing through the body and out of the catalyst through the second surface. 2. The method of claim 1, wherein at least one catalyst layer is on the first surface and / or the second surface. 3. The support comprises a wall flow filter made from an inert ceramic material.
The method described in. 4. The method of claim 1, wherein the support comprises a wall flow filter made by extrusion of a catalytic material. 5. The internal combustion engine is a diesel engine or a gasoline fuel-efficient direct injection engine, and the catalyst is a NO _x storage catalyst for reducing nitrogen oxides, SC.
The method according to claim 3, which is an R catalyst or an HC-DeNO _x catalyst. 6. The internal combustion engine is a diesel engine or a gasoline fuel-efficient direct injection engine, and the catalyst is a NO _x storage catalyst for reducing nitrogen oxides, SC.
The method according to claim 4, which is an R catalyst or an HC-DeNO _x catalyst. 7. The internal combustion engine is a diesel engine, and the catalyst is a diesel oxidation catalyst that oxidizes carbon monoxide, hydrocarbons, and soluble organic compounds attached to soot particles. The method described in. 8. The internal combustion engine is a diesel engine, and the catalyst is a diesel oxidation catalyst that oxidizes carbon monoxide, hydrocarbons, and soluble organic compounds attached to soot particles. The method described in. 9. The internal combustion engine is a stoichiometrically operated gasoline engine, and the catalyst is a three-way catalyst that simultaneously converts nitrogen oxides, hydrocarbons, and carbon monoxide. The method according to claim 3. 10. The internal combustion engine is a stoichiometrically operated gasoline engine, and the catalyst is a three-way catalyst that simultaneously converts nitrogen oxides, hydrocarbons, and carbon monoxide. The method of claim 4. 11. A device for converting a harmful substance contained in exhaust gas of an internal combustion engine by using a catalyst, the device including a porous catalyst holding support having an open pore structure. A device having a first surface allowing the inflow of the exhaust gas and a second surface allowing the outflow of the exhaust gas. 12. The device of claim 11, wherein the porous catalyst retention support comprises a catalytic material. 13. The catalyst material is HC-adsorber, NO.
_x storage catalyst, diesel oxidation catalyst, SCR catalyst, HC-
The device according to claim 12, which is a DeNO _x catalyst or a three-way catalyst. 14. The device of claim 13, wherein the porous catalyst retention support is in the form of a wall flow filter. 15. The device according to claim 11, wherein a catalyst layer is adhered to the first surface and / or the second surface. 16. The device of claim 11, wherein the porous catalyst-supporting support comprises an inert ceramic material. 17. An exhaust system including the device of claim 11, wherein the device is located within an exhaust gas conduit and the first surface is located upstream of the second surface. Exhaust system. 18. The exhaust system of claim 17, wherein the device spans a cross section of the exhaust gas conduit.