KR20180124343A - Multi-layer type gpf(gasoline particulate filer) and method for manufacturing of the gpf, exhaust gas treatment system for gasoline engine having the gpf, and method for judging of distribution of pore in the gpf - Google Patents

Abstract

The present invention relates to multilayered gasoline particulate filter (GPF) coated with a catalytic material in multiple times so that the flow of exhaust gas can evenly be distributed over the whole area without being concentrated in a specific region. The present invention further relates to a production method thereof. According to the present invention, the multilayered GPF, which is made of a porous material and collects particulate matters (particle number, PN) introduced into at the pore, comprises a filter wall (21) which made of a porous material and through which the exhaust gas discharged from an engine (1) passes from the inside to the outside, and the catalytic material functioning as a three-way catalyst is coated on the inner wall of the filter wall (21) at least twice to form a plurality of catalyst layers. The production method comprises the following steps: a filter wall preparation step (S110) of preparing the filter wall (21) having a tubular shape and a highly porous structure; a first catalyst coating step (S110) of coating the inside of the filter wall (21) with the catalyst material to form a first catalyst layer (22); and a second catalyst coating step (S120) of forming a second catalyst layer (23) by further coating the catalyst material on the first catalyst layer (22) formed in the first catalyst coating step (S110).

Description

FIELD OF THE INVENTION [0001] The present invention relates to a GPF having a multi-layer structure and a method of manufacturing the same, an exhaust treatment system of a gasoline engine including the GPF, and a method of determining a pore distribution of the GPF. TREATMENT SYSTEM FOR GASOLINE ENGINE HAVING THE GPF, AND METHOD FOR JUDGING OF DISTRIBUTION OF PORE IN THE GPF}

The present invention relates to a multi-layered GPF having a plurality of layers of a catalyst material coated thereon so that the flow of exhaust gas is not concentrated in a specific region but can be evenly distributed throughout the entire region and a manufacturing method thereof, System, and a method for determining the pore distribution of the GPF.

Various kinds of emissions from vehicles are being regulated, and the amount of emissions is being gradually increased.

Regulations for Particulate Numbers (PN), which are particulate matter, are gradually being strengthened in the above emissions. Regulation for gasoline engines, especially GDI (gasoline direct injection) engines, is being implemented in response to the application of RDE (Real Driving Emission) Is required.

In the case of a vehicle equipped with a GDI engine to cope with such a PN regulation, studies have been made to reduce the number of PNs discharged after combustion from the engine by improving the combustion of the engine and to reduce the number of PNs discharged from the engine through post- .

1, an exhaust pipe 2 for exhausting the exhaust gas discharged from the engine 1 is disposed downstream of a WCC (Warm-up Catalytic Converter) 10, A technique of installing a gasoline particulate filter (GPF) and collecting the PN discharged from the engine 1 in the GPF 20 is under development.

Since the GPF 20 should also function as a conventional three way catalyst (TWC), the GPF 20 is coated with the TWC catalyst material.

The GPF 20 is typically fabricated using a cordierite filter, which includes pores having a very complex shape and size on the wall. The TWC catalyst material coated on the GPF 20 for the reduction of CO, HC, and NOx should be evenly distributed on the wall surface of the cordierite filter so that the PN is collected.

That is, in the general filter shown in FIG. 3A, pores are small and the PN is collected in the filter. However, when the TWC catalyst material is nonuniformly coated in the large pore filter (see FIG. 3B) There is a phenomenon that the flow of the exhaust gas concentrates in a region where the coating of the catalyst layer is less or uncoated.

4 is a cross-sectional photograph of the GPF 20 taken along the longitudinal direction, wherein the inlet of the GPF 20 is filled with a catalyst material containing TWC catalyst material filling the pores of the GPF 20 In the middle of the GPF 20, the catalyst material is not uniformly coated in the GPF 20, and pores are present, and the PN flows out to the outside.

FIG. 5 shows distribution of pore sizes according to positions in the GPF 20 according to the prior art. However, it can be seen that the distribution is uneven compared to the filter media 21 of the superficial filter.

Thus, when the exhaust gas is concentrated in a part of the GPF 20, PN particles having a small size pass through the GPF 20 and are discharged to the outside. In addition to not being able to meet emissions regulations due to the externally vented PN, this also deteriorates the atmospheric environment.

On the other hand, the following prior art document discloses a technique relating to a particulate filter for exhaust gas purification.

KR 10-2012-0007859 A

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a method and an apparatus for preventing the PN from flowing out to the outside through the region where the catalytic material is insufficient or not coated, It is an object of the present invention to provide a GPF having a multilayer structure and a method of manufacturing the same, an exhaust treatment system of a gasoline engine including the GPF, and a method of determining a pore distribution of the GPF.

According to an aspect of the present invention, there is provided a GPF having a multi-layer structure, the GPF comprising: a gasoline particulate filter (GPF) which is made of a porous material and collects particulate matter (PN) A first catalyst layer made of a porous material and having a filter wall through which exhaust gas discharged from the engine penetrates from the inside to the outside, wherein a catalyst material functioning as a three-way catalyst is coated in the filter wall; And a second catalyst layer on which the catalyst material is further coated is formed on the first catalyst layer.

And the catalyst material coated on the second catalyst layer includes a noble metal component.

And the catalyst material coated on the first catalyst layer is made of a non-noble metal component.

And the catalyst material coated on the first catalyst layer includes a noble metal component.

Wherein the first catalyst layer and the second catalyst layer are coated with the same catalyst material.

And the catalyst layer is coated inside the filter wall.

And the second catalyst layer is further formed with another catalyst layer to which the catalyst material is added.

And the filter wall is formed in a cylindrical shape.

The engine is a gasoline direct injection (GDI) engine, and the GPF is installed downstream of the WCC in an exhaust pipe through which exhaust gas is discharged from the engine.

Meanwhile, a method of manufacturing a GPF having a multi-layer structure according to the present invention includes a first catalyst coating step of coating a catalyst material inside a filter wall having a large pore structure to form a first catalyst layer, And a second catalyst coating step of further coating the catalyst material on the formed first catalyst layer to form a second catalyst layer.

The catalytic material coated in the second catalyst coating step includes a noble metal component.

The catalytic material coated in the first catalyst coating step is a non-noble metal component.

The catalytic material coated in the first catalyst coating step may include a noble metal component.

Wherein the catalyst material of the first catalyst coating step and the catalyst material of the second catalyst coating step are the same.

Wherein the filter wall is formed in a cylindrical shape and in the first catalyst coating step and the second catalyst coating step the catalytic material is radially moved in the cross section of the filter wall, Is coated.

A pore distribution determining step of determining whether the pore distribution inside the filter wall is uniform within a predetermined range along the longitudinal direction of the filter wall after the second catalyst coating step, The second catalyst coating step is performed again when it is determined that the pore distribution of the catalyst is not uniform.

The present invention also provides a method of manufacturing a GPF having a multi-layer structure, comprising: a first catalyst coating step of forming a first catalyst layer by coating a catalytic material in a filter wall having a large pore structure; And a second catalytic coating step of further coating the catalytic material so that the filter walls are uniform in distribution of the pores along the longitudinal direction of the filter walls,

The second catalytic coating step is characterized in that a portion where a large amount of pores are distributed in the filter wall is coated more than a portion where the pores are less distributed.

The catalytic material coated in the second catalyst coating step includes a noble metal component.

The catalytic material coated in the first catalyst coating step is a non-noble metal component.

The catalytic material coated in the first catalyst coating step may include a noble metal component.

Wherein the catalyst material of the first catalyst coating step and the catalyst material of the second catalyst coating step are the same.

Wherein the filter wall is formed in a cylindrical shape and in the first catalyst coating step and the second catalyst coating step the catalytic material is radially moved in the cross section of the filter wall, Is coated.

A pore distribution determining step of determining whether the pore distribution inside the filter wall is uniform within a predetermined range along the longitudinal direction of the filter wall after the second catalyst coating step, The second catalyst coating step is performed again when it is determined that the pore distribution of the catalyst is not uniform.

An exhaust gas treatment system of a gasoline engine including a GPF of a multilayer structure includes an exhaust gas treatment system for treating an exhaust gas exhausted from a GDI (gasoline direct injection) engine, the exhaust gas treatment system comprising a WCC Warm-up Catalytic Converter) and the GPF for collecting PN contained in the exhaust gas passing through the WCC in the exhaust pipe.

A method for determining the pore distribution of a GPF of a multi-layered structure includes: a first catalyst coating step of forming a first catalyst layer by coating a catalyst material inside a filter wall having a mexican structure; A second catalytic coating step of coating the catalytic material on the second catalytic layer to form a second catalytic layer; and cutting the filter wall in a direction perpendicular to the longitudinal direction of the filter wall at predetermined intervals along the longitudinal direction of the filter wall A filter wall cutting step, a pore distribution measuring step of measuring a distribution of pores on each of the cut surfaces, and a pore distribution determining step of determining whether the distribution of the pores is uniform within a predetermined range.

According to the GPF of the present invention having the above-described structure and the method of producing the same, since the catalyst material is coated over several times, the catalyst material concentrates in a region where the coating is insufficient until the last coating, The catalyst material can be coated uniformly over the entire area of the GPF.

As described above, since the GPF is coated with the catalyst material, it is possible to prevent the PN from being leaked through the region where the coating is insufficient or not coated.

Meanwhile, the exhaust gas treatment system of the gasoline engine including the GPF of the multi-layered structure according to the present invention is characterized in that since the catalyst material is uniformly coated inside the GPF and the pores are uniformly distributed, To the outside.

Further, according to the pore distribution determination method of the GPF of the multilayer structure according to the present invention, the pore distribution in the GPF can be easily determined.

1 is a schematic view showing a state where a WCC and a GPF are installed in an exhaust pipe of a gasoline engine.
2 is a cross-sectional view of a GPF according to the prior art;
3A is a photograph of a section of a general filter.
3B is a photograph of a section of the meat pneumatic filter.
FIG. 4 is a cross-sectional view showing distribution of catalyst materials and pores in each GPF according to the prior art. FIG.
5 is a graph showing the distribution of pores per position in the GPF according to the prior art.
6 is a cross-sectional view showing a state in which a first catalyst layer is coated in a GPF having a multilayer structure according to the present invention.
7 is a cross-sectional view of a GPF of a multi-layer structure according to the present invention.
8A is a cross-sectional view of a filter wall in a state in which a first catalyst layer is coated in a GPF of a multilayer structure according to the present invention.
Figure 8b is a cross-sectional view of the filter wall during the coating of the second catalyst layer in the GPF of the multi-layer structure according to the invention.
FIG. 8C is a cross-sectional view of a filter wall in a GPF having a multilayer structure according to the present invention coated with a second catalyst layer. FIG.
9 is a flow chart showing a method of manufacturing a GPF of a multilayer structure according to the present invention.
10 is a flowchart showing a pore distribution determination method of a GPF having a multilayer structure according to the present invention.
11 is a graph showing the distribution of pores per position in the GPF of the multi-layer structure according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

The GPF having a multilayer structure according to the present invention is a gasoline particulate filter (GPF) made of a porous material and collecting particulate matter (PN) introduced into the pores into the pores, A filter wall (21) through which the exhaust gas discharged from the engine (1) penetrates from the inside to the outside, and a catalyst material functioning as a three way catalyst is coated on the inner wall of the filter wall (21) .

The filter wall 21 is made of a porous material. The filter wall 21 is formed in a cylindrical shape so that the exhaust gas flowing into the filter wall 21 flows through the wall of the filter wall 21 while the filter wall 21 ) To trap the PN (particle number) contained in the exhaust gas. Particularly, it is preferable that the filter wall 21 is made of a high porosity material, for example, a cordierite filter.

The GPF 20 also functions as a three-way catalyst (TWC). To this end, the filter wall 21 is coated with a three-way catalytic material. The three-way catalyst material may be coated at one time, but the three-way catalyst material is coated on the filter wall 21 several times to form a plurality of catalyst layers coated with the three-way catalyst material.

A catalyst material is coated on the inside of the filter wall 21 to form a first catalyst layer 22 and then a catalytic material is applied to the first catalyst layer 22 so that a radial direction of the filter wall 21 The first catalyst layer 22 and the second catalyst layer 23 are formed from the center of the filter wall 21.

When the catalyst material is coated in a divided manner, the catalyst material is coated on the catalyst material because the flow of the catalyst material is concentrated through the portion where the catalyst material is less coated and the pores are large during the immediately preceding coating.

Further, since the coating amount of the catalyst material is increased, the function of the catalyst is also improved.

Particularly, it is preferable that the three-way catalyst material is coated twice inside the filter wall 21 so as to have a two-layer structure so that the first catalyst layer 22 and the second catalyst layer 23 are formed. In this case, since the cost of the GPF 20 is increased and the back pressure is increased with respect to the entire section, the catalyst layer is formed of the first catalyst layer 22 and the second catalyst layer 22, And a second catalyst layer (23).

The catalyst material of the first catalyst layer 22 does not include a noble metal component such as platinum Pt and the catalyst material of the second catalyst layer 23 includes a noble metal component such as platinum Pt. However, the catalyst material of the first catalyst layer 22 may also include noble metal components. When the catalyst material of the first catalyst layer 22 includes a noble metal component, the first catalyst layer 22 and the second catalyst layer 23 may be the same material.

In addition, the catalyst layers formed on the filter walls 21 are all located inside the filter walls 21. If the catalyst material accumulates on the surface of the filter wall 21, it may cause a sudden increase in the back pressure. Therefore, it is preferable that the catalyst layer is located inside the filter wall 21.

The GPF 20 is installed downstream of the WCC 10 in a gasoline engine, particularly a vehicle to which a GDI engine is applied. The GPF 20 collects the PN contained in the exhaust gas by the pores of the filter wall 21, The second catalytic layer 22 and the catalytic material coated on the second catalytic layer 23 serve as a three-way catalyst. The PNs collected in the GPF 20 are removed through regeneration, so that the GPF 20 can continue to collect the PNs.

An exhaust gas treatment system for a gasoline engine according to the present invention will now be described.

The exhaust treatment system of the gasoline engine according to the present invention constitutes an exhaust treatment system using the GPF 20 of the multi-layer structure.

The GPF 20 of the multi-layer structure as described above is applied for collecting the PN contained in the exhaust gas discharged from the engine 1, preferably a gasoline engine, more preferably a GDI engine.

An exhaust pipe (2) through which exhaust gas exhausted from the engine (1) is exhausted is connected to the engine (1).

A WCC (Warm-up Catalytic Converter) is installed in the exhaust pipe 2, and the GPF 20 is installed to collect the PN contained in the exhaust gas passing through the WCC 10.

Therefore, in the GPF 20, the exhaust gas passing through the WCC 10 is not concentrated to a specific site in the GPF 20, but is uniformly dispersed and passed, and the PN contained in the exhaust gas is collected.

In the meantime, the method for manufacturing a GPF having a multi-layer structure according to the present invention includes a first catalyst coating step (S110) of forming a first catalyst layer (22) by coating a catalyst material inside a filter wall (21) And a second catalyst coating step (S120) of forming a second catalyst layer (23) by further coating the catalyst material on the first catalyst layer (22) formed in the first catalyst coating step (S110).

In the first catalyst coating step S110, a catalytic material is coated on the inner wall of the filter wall 21 having a tubular structure formed of a porous material, and a first catalyst layer (not shown) is formed on the inner wall of the filter wall 21 22) are formed (see Fig. 6). The filter wall 21 is made of a cordierite filter, and has a larger pore structure than a general filter material.

In the first catalyst coating step S110, the catalyst material is applied to the inside of the filter wall 21 in a state where the pressure outside the filter wall 21 is lowered, So that the first catalyst layer 22 is formed in the filter wall 21. Alternatively, if the filter wall 21 is immersed in a solution in which the catalyst material is dissolved, the catalyst material is coated on the pores while the solution moves due to the capillary phenomenon due to the pores of the filter wall 21. The catalyst material is coated on the inside of the filter wall 21 through the above two methods or other methods.

The catalyst material coated in the first catalyst coating step (S110) is coated with a three-way catalyst material containing a three-way catalyst material so that the GPF 20 can also function as a three-way catalyst.

Particularly, it is preferable that the catalyst material coated in the first catalyst coating step (S110) is a non-noble metal catalyst material containing no noble metal component such as platinum (Pt). Meanwhile, the catalyst material coated in the first catalyst coating step (S110) may include a noble metal component.

As shown in FIG. 8A, the GPF 20 in which the first catalyst coating step S110 is completed can be described as follows. In the filter wall 21, the catalyst material is uniformly coated, There are many pores.

The second catalyst coating step S120 further coats the inner wall of the filter wall 21 with a three-way catalyst material (see FIG. 7). In the second catalyst coating step S120, a third catalyst layer 23 is formed by further coating a three-way catalyst material on the first catalyst layer 22 coated in the first catalyst coating step S110.

The method of coating the catalyst material in the second catalyst coating step (S120) may be the same as the method of coating the catalyst material in the first catalyst coating step (S110).

The catalyst material in the second catalyst coating step S120 includes a noble metal component such as platinum (Pt). If the catalytic material including the noble metal component is coated in the first catalyst coating step S110, the catalytic material coated in the first catalytic coating step S110 and the second catalytic coating step S120 may be the same have.

In the second catalyst coating step (S120), the three-way catalytic material is unevenly coated in the first catalyst coating step (S110), and the pores are relatively small in the portion where a large amount of pores exist in the filter wall (21) The catalytic material is concentrated and moved relative to the existing part so that the catalytic material is coated more.

That is, if the catalyst material coated by the first catalyst coating step S110 is concentrated in the area A of FIG. 8A, the second catalyst coating step S120 allows more flow to the area B of FIG. 8B, Finally, the pores are filled with the catalyst material along the longitudinal direction of the GPF 20 to have a uniform coating distribution. Thus, when the catalyst material is uniformly coated, the distribution of the pores becomes uniform.

Further, since the coating amount of the catalyst material is also increased, the function of the GPF 20 as a catalyst can be expected to be improved.

On the other hand, if the catalyst material is uniformly coated on the filter wall 21 through the first catalyst coating step S110 and the second catalyst coating step S120 and the pore distribution is also uniform, S120).

However, after the second catalyst coating step (S120) is performed, if the distribution of the pores is not uniform within a predetermined standard, the second catalyst coating step (S120) may be repeatedly performed.

That is, after the second catalyst coating step (S120) is performed, the pore distribution in the filter wall (21) is determined to be uniform within a predetermined range along the longitudinal direction of the filter wall (21) If it is determined that the pore distribution in the filter wall 21 is not uniform in the pore distribution determining step S130, the second catalyst coating step S120 is performed again .

When the second catalyst coating step (S120) is repeatedly performed, the flow of the catalyst material is increased to a portion where the catalyst material is less coated during the previous catalyst coating, so that the catalyst material is coated faster than other regions.

However, considering the production cost of the GPF 20 or the back pressure of the GPF 20, it is preferable that the second catalyst coating step S120 is performed only once after the first catalyst coating step S110 .

As described above, according to the GPF of the multi-layer structure and the method of manufacturing the same according to the present invention, as shown in FIG. 11, the GPF has a uniform pore distribution irrespective of the position of the filter wall 21.

Therefore, when the actual GPF 20 is mounted on the vehicle, the exhaust gas flows uniformly over the entire length of the GPF 20, so that the flow of the exhaust gas is concentrated through a large portion of the catalyst material, And it is possible to solve the problem that the particulate matter is discharged to the outside through this portion.

Since the particulate matter is not discharged to the outside, it is possible to solve not only the PN regulation but also the deterioration of the atmospheric environment.

On the other hand, Fig. 10 shows a pore distribution determination method of a GPF having a multilayer structure according to the present invention.

In order to determine whether or not the pores are uniformly distributed in the GPF produced by the above-described method of manufacturing a GPF having the multi-layer structure, a method of determining the pore distribution of the GPF of the multi-layered structure according to the present invention is performed.

The first catalyst coating step S21 and the second catalyst coating step S220 are the same as the one catalyst coating step S110 and the second catalyst coating step S120 in the method of manufacturing the GPF of the multilayer structure described above.

The filter wall cutting step S230 cuts the filter wall 21 in a direction perpendicular to the longitudinal direction of the filter wall 21 at regular intervals along the longitudinal direction of the filter wall 21. [ By cutting the filter wall 21, the internal structure of the filter wall 21 in which the first catalyst layer 22 and the second catalyst layer 23 are formed can be exposed to the outside.

The pore distribution measurement step S240 measures the pores existing on the surface exposed to the outside by cutting the filter wall 21. [

The pore distribution determining step S250 determines whether the pore distribution measured in the pore distribution measuring step S240 is uniform within a predetermined range. The filter wall 21 is cut at a plurality of points along its longitudinal direction to determine whether the distributions of the pores at the respective cut portions are uniform.

If the pore distribution is uniform, it is determined that the pore distribution of the GPF 20 is good (S260). Otherwise, it is determined that the pore distribution is poor (S270).

1: engine
2: Exhaust pipe
10: WCC
20: GPF
21: Filter month
22: First catalyst layer
23: Second catalyst layer
120: GPF
121: Filter month
122: catalyst layer
S110: First catalyst coating step
S120: second catalyst coating step
S130: Pore distribution determination step
S210: First catalyst coating step
S220: the second catalyst coating step
S230: Filter wall cutting step
S240: Pore distribution measurement step
S250: Pore distribution determination step
S260: Good judgment step
S270: Bad determination step

Claims (25)

1. A GPF (gasoline particulate filter) made of a porous material and collecting particulate matter (PN)
And a filter wall made of a porous material and through which the exhaust gas discharged from the engine penetrates from the inside to the outside,
A first catalyst layer coated with a catalytic material functioning as a three-way catalyst in the filter wall,
Wherein the first catalyst layer is formed with a second catalyst layer on which the catalyst material is further coated. The method according to claim 1,
Wherein the catalyst material coated on the second catalyst layer comprises a noble metal component. 3. The method of claim 2,
Wherein the catalyst material coated on the first catalyst layer comprises a non-noble metal component. 3. The method of claim 2,
Wherein the catalyst material coated on the first catalyst layer comprises a noble metal component. 5. The method of claim 4,
Wherein the first catalyst layer and the second catalyst layer are coated with the same catalyst material. The method according to claim 1,
Wherein the catalyst layer is coated inside the filter wall. The method according to claim 1,
Wherein the second catalyst layer further comprises another catalyst layer to which the catalyst material is added. The method according to claim 1,
Wherein the filter wall is formed in a tubular shape. The method according to claim 1,
The engine is a gasoline direct injection (GDI) engine,
Wherein the GPF is installed downstream of the WCC in an exhaust pipe through which exhaust gas is discharged from the engine. 1. An exhaust gas treatment system for treating an exhaust gas exhausted from a GDI (gasoline direct injection) engine,
A Warm-up Catalytic Converter (WCC) installed in an exhaust pipe through which exhaust gas is discharged from the engine,
The exhaust treatment system of a gasoline engine according to any one of claims 1 to 9, which collects PN contained in the exhaust gas that has passed through the WCC in the exhaust pipe. A first catalytic coating step of forming a first catalyst layer by coating a catalytic material in a filter wall having a large pore structure,
And a second catalyst coating step of further coating the catalyst material on the first catalyst layer formed in the first catalyst coating step to form a second catalyst layer. 12. The method of claim 11,
Wherein the catalytic material coated in the second catalytic coating step comprises a noble metal component. 13. The method of claim 12,
Wherein the catalytic material coated in the first catalyst coating step is a non-noble metal component. 13. The method of claim 12,
Wherein the catalytic material coated in the first catalyst coating step comprises a noble metal component. 15. The method of claim 14,
Wherein the catalyst material of the first catalyst coating step and the catalyst material of the second catalyst coating step are the same. 12. The method of claim 11,
The filter wall is formed in a cylindrical shape,
Wherein in the first catalyst coating step and the second catalyst coating step, the catalytic material is radially moved in the cross section of the filter wall so that the catalytic material is coated inside the filter wall. Gt; 12. The method of claim 11,
After the second catalyst coating step,
A pore distribution determining step of determining whether the pore distribution in the filter wall is uniform within a predetermined range along the longitudinal direction of the filter wall;
Wherein the second catalyst coating step is performed again when it is determined that the pore distribution in the filter wall is not uniform in the pore distribution determining step. A first catalytic coating step of forming a first catalyst layer by coating a catalytic material in a filter wall having a large pore structure,
And a second catalyst coating step of further coating the catalyst material so that the filter walls on which the first catalyst layers are formed have a uniform distribution of pores along the longitudinal direction of the filter walls,
Wherein the second catalyst coating step further comprises coating the catalytic material on a portion of the filter wall where a large amount of pores are distributed as compared to a portion where the pores are less distributed so that a back pressure acting on the filter wall becomes uniform. A method for producing a GPF having a multilayer structure. 19. The method of claim 18,
Wherein the catalytic material coated in the second catalytic coating step comprises a noble metal component. 20. The method of claim 19,
Wherein the catalytic material coated in the first catalyst coating step is a non-noble metal component. 20. The method of claim 19,
Wherein the catalytic material coated in the first catalyst coating step comprises a noble metal component. 22. The method of claim 21,
Wherein the catalyst material of the first catalyst coating step and the catalyst material of the second catalyst coating step are the same. 19. The method of claim 18,
The filter wall is formed in a cylindrical shape,
Wherein in the first catalyst coating step and the second catalyst coating step, the catalytic material is radially moved in the cross section of the filter wall so that the catalytic material is coated inside the filter wall. Gt; 19. The method of claim 18,
After the second catalyst coating step,
A pore distribution determining step of determining whether the pore distribution in the filter wall is uniform within a predetermined range along the longitudinal direction of the filter wall;
Wherein the second catalyst coating step is performed again when it is determined that the pore distribution in the filter wall is not uniform in the pore distribution determining step. A first catalytic coating step of forming a first catalyst layer by coating a catalytic material in a filter wall having a large pore structure,
A second catalyst coating step of further coating the catalyst material on the first catalyst layer formed in the first catalyst coating step to form a second catalyst layer;
A filter wall cutting step of cutting the filter walls in a direction perpendicular to the longitudinal direction of the filter walls at predetermined intervals along the longitudinal direction of the filter walls;
A pore distribution measurement step of measuring a distribution of pores on each cut surface,
And a pore distribution determining step of determining whether the pore distribution is uniform within a predetermined range.

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