JPWO2015025926A1 - Ceramic support for supporting catalyst, and catalyst - Google Patents

Abstract

The porous honeycomb structure (10) used for the exhaust gas purifying catalyst body such as DPF (1), which supports the noble metal having the catalytic function for exhaust gas purification, has a specific surface area while Ce is solid-solved. Is made of a ceramic material of 0.2 m 2 / cm 3 or more.

Description

  The present invention relates to an exhaust gas purification technique for an internal combustion engine such as an automobile engine, and more particularly to a ceramic carrier that supports a noble metal that is a catalyst for exhaust gas purification and an exhaust gas purification catalyst body using the ceramic carrier.

  The exhaust gas purifying catalyst body has a structure in which a noble metal that is an exhaust gas purifying catalyst is supported on the surface of a ceramic support. Cordierite, silicon carbide, aluminum titanate and the like are often used as the ceramic material constituting the ceramic carrier.

  For example, for a diesel engine, a ceramic carrier supporting a noble metal is formed as a diesel particulate filter (DPF) in which a plurality of cells serving as exhaust gas passages are formed in a honeycomb shape and each cell is alternately sealed. The The DPF is connected to the exhaust side of the diesel engine and collects particulate matter (PM) in the exhaust gas and oxidatively decomposes the collected PM and HC and CO in the exhaust gas.

  By the way, it is known that noble metal particles such as Pt, Pd, and Rh used for the catalyst move and aggregate on the ceramic support while growing the exhaust gas purifying catalyst body. When grain growth occurs in the noble metal particles, the surface area per noble metal amount becomes small, so that the catalytic ability of the noble metal is not sufficiently exhibited, and the purification ability is lowered. Therefore, in order to ensure the purification capacity over a long period of time, it is necessary to support in advance a precious metal capable of exhibiting a sufficient purification capacity even when the grains grow.

  However, it is necessary to suppress the use of rare metals, which are rare metals, from the standpoint of elemental strategy and the like. Conventionally, various countermeasures for suppressing grain growth of noble metal particles have been studied.

For example, in a three-way catalyst for a gasoline engine, it has already been put into practical use by fixing Pt particles by Pt—O—Ce bonding onto CeO ₂ used as a cocatalyst having oxygen storage capacity. This utilizes the property that CeO ₂ has a strong chemical bonding force with a noble metal.

  In addition, the surface of the ceramic carrier supporting the catalyst is coated (coated) with γ-alumina having a large specific surface area, so that the spacing between the noble metal particles supported on the surface is widened and the particles move even if they move. Measures are also taken to make it difficult to do.

  However, since the coating layer of γ-alumina has a small pore diameter and porosity, if this measure is used as it is in the DPF, the resistance when the exhaust gas passes through the DPF increases, and the pressure loss increases.

  Therefore, a technique has been proposed in which the surface of the ceramic carrier is not coated with γ-alumina, but each particle forming the ceramic carrier is coated with an alumina thin film on a particle basis (for example, Patent Document 1, 2).

Japanese Patent Publication “Japanese Patent Laid-Open No. 2001-62302 (published on March 13, 2001)” Japanese Patent Gazette "Japanese Patent Laid-Open No. 2002-119860 (published April 23, 2002)"

  However, in order to increase the specific surface area of the ceramic carrier supporting the above-mentioned catalyst, the method of coating each particle forming the ceramic carrier with an alumina thin film on a particle basis is not limited to the manufacturing process of the ceramic carrier. There is a problem that the steps of drying and firing need to be performed a plurality of times in order to form an alumina thin film, and the number of manufacturing steps is large.

  The present invention has been made in view of the above problems, and provides an exhaust gas purifying catalyst body that can be manufactured with a small number of steps and that can more effectively suppress grain growth of noble metal particles. is there.

In order to solve the above problems, the ceramic carrier of the present invention is a porous ceramic carrier that supports a noble metal having catalytic ability for exhaust gas purification on its surface, and Ce is solid-solved and has a specific surface area. Is made of a ceramic material of 0.2 m ² / cm ³ or more. Here, the specific surface area is a surface area per unit volume of a ceramic carrier formed as DPF or the like.

  In order to solve the above problems, the exhaust gas purifying catalyst body of the present invention has at least one of Pt, Pd, and Rh as a noble metal having catalytic ability on the surface of the ceramic support body of the present invention and the ceramic support body. It is characterized in that one or more are supported.

According to this, Ce dissolved in the ceramic material forms a chemical bond with the noble metal particles (hereinafter referred to as noble metal particles), and the noble metal particles can be fixed to the surface of the ceramic carrier. Further, since the specific surface area of the ceramic material in which Ce is dissolved is 0.2 m ² / cm ³ or more, the interval between the noble metal particles fixed on the surface of the ceramic support becomes sufficiently wide, and the grain growth of the noble metal particles is increased. It can be effectively suppressed.

  As a result, the fixing effect of the noble metal particles by the solid solution Ce and the dispersion effect of widening the interval of the noble metal particles due to the large specific surface area of the ceramic material act in combination to effectively increase the grain growth of the noble metal particles. Can be suppressed.

  As a result, the catalytic ability of the noble metal can be fully exerted, and when the amount of noble metal supported is the same, the purification performance is maintained longer than that of the exhaust gas purification catalyst body using the ceramic support of the conventional configuration. can do. In addition, when the period for maintaining the purifying capability without problems is the same, the amount of noble metal to be supported can be reduced as compared with the exhaust gas purifying catalyst body using the ceramic support body of the conventional configuration.

  According to the present invention, it is possible to provide an exhaust gas purifying catalyst body that can be manufactured with a small number of steps and that can further effectively suppress the grain growth of noble metal particles, and a ceramic carrier to be provided therefor. There is an effect.

1 is a perspective view showing an overview of a DPF according to an embodiment of the present invention. It is a schematic cross section of the surface parallel to the axial direction of the DPF. (A)-(c) is a figure which shows notionally the state by which Pt particle | grains are carry | supported on the surface of the honeycomb structure 10. FIG. FIG. 3 shows an example of the present invention and is a diagram showing the results of microstructural observation and elemental analysis of the ceramic carrier of Example 1. FIG. 3 shows an example of the present invention, and is a view showing a result of an electronic state analysis in a ceramic carrier of Example 1. The SEM photograph of the sample using the ceramic support body of Example 1 is shown, (a) is a secondary electron image, (b) A reflected electron image (composition image). The SEM photograph of the sample using the ceramic support body of Example 2 is shown, (a) is a secondary electron image, (b) A reflected-electron image (composition image). The SEM photograph of the sample using the ceramic support body of Example 3 is shown, (a) is a secondary electron image, (b) A reflected-electron image (composition image). The SEM photograph of the sample using the ceramic carrier of the comparative example 1 is shown, (a) is a secondary electron image, (b) A reflected electron image (composition image). The Example of this invention is shown and it is a figure which shows the result of the fine structure observation in the ceramic carrier of Example 4, and an elemental analysis.

  In the present embodiment, the exhaust gas purification catalyst body is used as a DPF for collecting and purifying PM contained in exhaust gas and carrying an oxidation catalyst for exhaust gas treatment for a diesel engine. The exhaust gas catalyst may be supported.

  As shown in FIG. 1, the exhaust gas purifying catalyst body according to the present embodiment includes a honeycomb structure 10 in which a plurality of cells 11 serving as exhaust gas passages are formed in a honeycomb shape. The cells 11 constitute the DPF 1 alternately sealed with the sealing portions 21. The honeycomb structure 10 is a porous ceramic support, and a noble metal having catalytic ability for exhaust gas purification is supported on the surface of the honeycomb structure 10. FIG. 1 is a perspective view showing an overview of the DPF, and FIG. 2 is a schematic cross-sectional view of a plane parallel to the axial direction of the DPF.

  The plurality of cells 11 are formed by partitioning the inside of the honeycomb structure 10 with porous cell walls 12, and the cell walls 12 serve as PM collecting members. The noble metal is supported on the surface of the cell wall 12. And in DPF1 of this Embodiment, the ingenuity for making the catalytic ability of each noble metal particle stable over a long term is made | formed, and it mentions later for details.

The DPF 1 is arranged on the downstream side of the diesel engine (not shown) so that the extending direction of the cell 11 is parallel to the flow of the exhaust gas, and further between the DPF 1 and the diesel engine, a DOC (noble metal supported) Diesel oxidation catalyst) is arranged. In normal operation, before reaching the DPF 1, HC and CO contained in the exhaust gas are oxidized and decomposed by the noble metal applied to the DOC, and become harmless CO ₂ and H ₂ O.

  As shown in FIG. 2, the exhaust gas discharged from the DOC flows from each cell 11 whose end on the upstream side in the flow direction of the exhaust gas is not sealed, as shown in FIG. , Move to the cell 11 that is adjacent to each of the cells 11 on the downstream side in the exhaust gas flow direction and is not sealed. When the exhaust gas passes through the fine holes in the cell wall 12, PM contained in the exhaust gas is collected in the cell wall 12.

The collected PM comes into contact with the noble metal supported on the cell wall 12 and is oxidatively decomposed and removed from the cell wall 12 during the regeneration heat treatment of the DPF 1. In addition, during the regenerative heat treatment, HC and CO in the exhaust gas that has passed through the DOC are also contacted with the noble metal supported on the cell wall 12 while flowing through the cell 11, and are oxidatively decomposed to be harmless CO ₂ and H It is discharged as a _{2 O.}

  Next, a configuration that allows the catalytic ability of each noble metal particle in the DPF 1 according to the present embodiment to be stably exhibited over a long period of time will be described.

Conventionally, cordierite, silicon carbide, aluminum titanate, and the like have been put to practical use as the porous ceramic material constituting the honeycomb structure. However, in the DPF 1 of the present embodiment, the honeycomb structure 10 is made of cerium. Ce-β-sialon (SiAlON) having a specific surface area of 0.2 m ² / cm ³ or more in which (Ce) is dissolved is used. Sialon is a solution obtained by replacing a part of silicon (Si) and nitrogen (N) in silicon nitride (Si ₃ N ₄ ) with aluminum (Al) and oxygen (O), respectively. Ce-β-sialon is obtained by further dissolving Ce in such a sialon. The specific surface area was measured using a flow-type BET specific surface area measuring device.

  The ceramic material constituting the honeycomb structure 10 may contain Ce-α-sialon produced as a secondary phase together with Ce-β-sialon, in addition to the constitution consisting of a single phase of Ce-β-sialon. . Further, although not columnar crystals, α-sialon may be contained. The solid solution of Ce in sialon is performed in the same process as the process in which a part of Si and N in silicon nitride is substituted and dissolved in Al and O.

  And this inventor has confirmed that columnar crystallization of a sialon is accelerated | stimulated by baking by including Ce in the raw material used as a sialon. That is, by dissolving Ce in sialon, columnar crystallization of sialon is promoted, and the specific surface area of the ceramic carrier can be increased as compared with a state where Ce is not dissolved.

  Here, Ce is dissolved in sialon in order to form a chemical bond with the noble metal particles and fix the noble metal particles to the surface of the honeycomb structure 10. In the DPF 1 in this embodiment, platinum (Pt) is used as a noble metal, and a Pt—O—Ce bond is formed with Ce. O in the Pt—O—Ce bond is taken in from the air.

  The Ce content in the ceramic material is preferably 0.5 to 10 wt%. If the amount is less than 0.5 wt%, there is a possibility that the solid solution of Ce is insufficient and a required amount of noble metal particles cannot be fixed to the surface of the honeycomb structure 10. Precious metal particles that are not fixed are likely to agglomerate. On the other hand, when it exceeds 10 wt%, Ce is not dissolved in sialon, and another phase containing Ce may be deposited on the surface of the honeycomb structure 10. In consideration of Ce precipitation, the upper limit of the Ce content is more preferably 5 wt%.

Here, the specific surface area of the ceramic material in which Ce is dissolved is set to 0.2 m ² / cm ³ or more because the interval between the noble metal particles fixed on the surface of the honeycomb structure 10 is made wider. This is because the grain growth of the noble metal particles is effectively suppressed. Here, more preferably, the specific surface area of the ceramic material in which Ce is dissolved is 0.5 m ² / cm ³ or more. By setting it as this range, the grain growth of the noble metal particles can be more effectively suppressed.

The ceramic material constituting the ceramic carrier may be any ceramic material that satisfies a specific surface area of 0.2 m ² / cm ³ or more in a state in which Ce is dissolved, and examples of the material other than sialon include mullite.

  The noble metal particles supported on the surface of the honeycomb structure 10 include platinum (Pt) particles, palladium (Pd) particles, and rhodium (Rh) particles. These particles may be used alone or as a mixture of a plurality of types.

FIGS. 3A to 3C conceptually show a state in which Pt particles are supported on the surface of the honeycomb structure 10. As shown in (c), the Pt particles are Ce—O—Pt bonds formed by Ce dissolved in a ceramic material that is a constituent material of the honeycomb structure 10 and oxygen (O) in the air. It is fixed to the surface of the honeycomb structure 10. Since the specific surface area of the honeycomb structure 10 is 0.2 m ² / cm ³ or more, as shown in FIG. The Pt particles supported on the surface of the honeycomb structure 10 as described above will maintain a wide space between adjacent Pt particles as shown in FIG. This interval is sufficiently wider than the case where the same amount of Pt particles is supported on a ceramic support having a flat surface (having a small specific surface area).

  As a result, the effect of fixing Pt particles by Ce dissolved in the ceramic material constituting the honeycomb structure 10 and the effect of dispersing the Pt particles by the large specific surface area of the ceramic material act in combination. Thus, it is possible to effectively suppress the growth of Pt particles. Therefore, the catalytic ability of each Pt particle can be sufficiently exerted, and when the amount of Pt particles supported is the same, the purification performance is maintained longer than the DPF using the honeycomb structure having the conventional structure. can do. Further, when the period for maintaining the cleansing capability without problems is the same, the amount of Pt particles to be supported can be reduced as compared with the DPF using the honeycomb structure having the conventional structure.

Such a DPF 1 can be obtained by the following procedure. First, Si ₃ N ₄ , AlN, Al ₂ O ₃ , and CeO ₂ that are raw material powders of sialon are blended according to the blending amount considering the composition ratio of the ceramic material, and ethanol or the like is added and mixed. The mixture is shaped into the shape of the honeycomb structure 10 and then fired to obtain the honeycomb structure 10 having a Ce-β-sialon composition. Next, Pt is supported on the honeycomb structure 10 thus produced using a dinitrodiammine Pt nitric acid aqueous solution or the like as a starting material.

  By the way, in the present embodiment, the configuration using β-sialon as the honeycomb structure (ceramic carrier) 10 is exemplified, but it is known that the sialon includes α type and β type. The β-sialon used here has been confirmed to grow as hexagonal columnar crystal particles, and can easily satisfy the condition of the specific surface area required for the ceramic material. Moreover, Ce is easily dissolved, and the added Ce can be used effectively. On the other hand, α-sialon is usually difficult to dissolve even when Ce is added. However, even α-sialon can be dissolved in Ce by additionally adding yttrium (Y). Therefore, α-sialon can also be used as the honeycomb structure (ceramic carrier) 10.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention will be described in more detail with reference to examples.

(Examples 1-4, Comparative Example 1)
Si ₃ N ₄ (Ube Industries E10 Co., Ltd.), AlN (Tokuyama H Grade Co., Ltd.), Al ₂ O ₃ (Sumitomo Chemical AKP-30 Co., Ltd.) and CeO ₂ which are raw material powders for the honeycomb structure 10 (Shin-Etsu Chemical Co., Ltd.) was weighed so as to have the composition shown in Table 1, and wet-mixed in ethanol. As shown in Table 1, Comparative Example 1 does not contain Ce, Example 1 sets Ce to 2 w%, and Examples 2 and 3 set Ce to 4 w%, while Si and N in Si ₃ N ₄ are the same. The amount of substitution with Al and O is different. In Example 4, 9.7 w% of Ce was blended.

These mixed powders were fired under conditions of 1850 ° C., 2 h, 1500 ° C., 1 h under 0.9 MPa, N ₂ atmosphere, and the ceramic carriers of Examples 1 to 4 and Comparative Example 1 were fired. Obtained.

(Actual example 5)
Metal silicon (Si) (manufactured by Yamaishi Metal) 60.2 wt%, AlN (Tokuyama H grade) 4.2 wt%, Al ₂ O ₃ (Sumitomo Chemical AKP-30) 1.0 wt%, CeO ₂ (Shin-Etsu Chemical Co., Ltd.) 4.6 wt% was added and mixed with dry powder. Next, 0.4 wt% of a dispersant (Nippon Yushi Co., Ltd., Ceramisole), 19.6 wt% of water, and 10 wt% of methylcellulose (Shin-Etsu Chemical Co., Ltd. "Metroses") as an organic binder are mixed with this mixed material. Molded. Thereafter, the molded body was degreased in nitrogen and under nitrogen + oxygen conditions, and the degreased molded body was fired under conditions of 1350 ° C., 3 hours, and 1850 ° C., 3 hours in a nitrogen atmosphere. A support was obtained.

  Next, the six ceramic carriers thus obtained were subjected to identification of constituent phases by XRD, microstructure observation by SEM, elemental analysis by EDS, and Ce electronic state analysis by XPS. The results of microstructural observation and elemental analysis are shown in FIG. The result of the electronic state analysis is shown in FIG.

  From the XRD profile, only the β-SiAlON was produced in the ceramic carriers of Examples 1, 2, 4 and Comparative Example 1, and the ceramic carrier of Example 3 was as a secondary phase in addition to β-SiAlON. , Α-SiAlON was confirmed to be generated.

  As shown in FIGS. 4 and 10, as a result of SEM observation, it was confirmed that β-SiAlON was growing as hexagonal columnar particles (the secondary electron image in FIG. 4 is that of Example 1). Yes, the secondary electron image of FIG. 10 is that of Example 4). In Examples 1 to 3, it was also found from the EDS analysis that Ce was uniformly present in the product (the Ce distribution in FIG. 4 is that of Example 1 and the Ce distribution in FIG. 10 is Example 4).

Furthermore, as shown in FIG. 5, the presence of Ce ⁴⁺ that forms a Ce—O—Pt bond was confirmed from the electronic state of Ce.

  Next, Pt was supported on each ceramic support of Examples 1 to 5 and Comparative Example 1 using dinitrodiammine Pt nitric acid aqueous solution as a starting material, and then fired in air at 500 to 700 ° C. for 2 hours. Then, the Pt grain growth process was observed. Further, the particle size of the Pt particles was measured. The particle size is measured by the following two methods, and the results are shown in Table 1 above.

(Method of particle size measurement)
Method 1: Measurement of Pt particle size by image analysis A tissue containing Pt particles was photographed by SEM observation. Next, the Pt particles were binarized and the average particle size was measured by image processing. However, the particle size measurement of Pt particles by SEM observation cannot measure particles of several nm that cannot be observed by SEM.

Method 2: Integral intensity comparison by XRD The heat-treated material was integrated and measured by XRD under the conditions of 40 keV, 200 mA, width 0.020 ° C., scan speed 0.5 ° C./s, and number of scans 5. The integrated strength of the base material not coated with Pt was measured in advance, and the value obtained by dividing the integrated strength after the Pt coating heat treatment by the integrated strength without Pt coating was compared. The smaller the value, the finer the Pt particle size.

  In FIG. 6, the SEM photograph of the sample (500 degreeC2h) using the ceramic carrier of Example 1 is shown. In FIG. 6, (a) is a secondary electron image, and (b) is a reflected electron image (composition image). Similarly, SEM photographs of samples (500 ° C., 2 h) using the ceramic supports of Example 2, Example 3, and Comparative Example 1 are shown in FIGS. 7, 8, and 9. In FIGS. 6 to 9, the white scale is 1 μm, and photographing was performed at a magnification of 20,000 and 5.0 kV.

  From the secondary electron images of FIGS. 6 to 9, it is observed that hexagonal columnar particles are growing. 6 to 9, no Pt particles having a diameter of 100 nm or more were observed in the samples of Examples 1 to 3, and Pt particles having a diameter of 100 nm or more were not observed in the sample of Comparative Example 1. Was observed. Although no backscattered electron image is shown, no Pt particles having a diameter of 100 nm or more were observed in the samples of Examples 4 and 5.

  Further, by comparing the secondary electron images of FIGS. 6 to 8 and the secondary electron image of FIG. 9, the growth of hexagonal columnar particles is promoted in the sialon in which Ce is dissolved. It could be confirmed.

  In order to confirm the effect of suppressing grain growth by Ce, the average particle diameter of the Pt particles was measured. As a result, the sample of Comparative Example 1 was 139 nm when calcined at 500 ° C. for 2 h and 155 nm when calcined at 700 ° C. for 2 h. Met.

  On the other hand, in the sample of Example 1, when it was baked at 500 ° C. for 2 h, nothing exceeding 100 nm was observed, and when baked at 700 ° C. for 2 h, it was 128 nm. The result of the sample of Example 2 was the same as that of the sample of Example 1. In the sample of Example 3, a sample exceeding 100 nm was not observed when baked at 500 ° C. for 2 h, and was 146 nm when baked at 700 ° C. for 2 h. In the sample of Example 4, when it was baked at 500 ° C. for 2 h, no sample exceeding 100 nm was observed, and when baked at 700 ° C. for 2 h, it was 140 nm. In the sample of Example 5, a sample exceeding 100 nm was not observed when baked at 500 ° C. for 2 h, and 130 nm when baked at 700 ° C. for 2 h.

  The particle size was also measured by comparing the integrated strengths of those fired at 700 ° C. for 2 hours. The value of Examples 1-5 was smaller than this with respect to 0.31 of the sample of the comparative example 1, and it has confirmed that Pt particle size was fine.

  From these results, it was confirmed that the grain growth of Pt particles was suppressed by the fixing effect of Ce.

(Summary)
In order to solve the above problems, the ceramic carrier of the present invention is a porous ceramic carrier that supports a noble metal having catalytic ability for exhaust gas purification on its surface, and Ce is solid-solved and has a specific surface area. Is made of a ceramic material of 0.2 m ² / cm ³ or more. Here, the specific surface area is a surface area per unit volume of a ceramic carrier formed as DPF or the like.

  In order to solve the above problems, the exhaust gas purifying catalyst body of the present invention has at least one of Pt, Pd, and Rh as a noble metal having catalytic ability on the surface of the ceramic support body of the present invention and the ceramic support body. It is characterized in that one or more are supported.

According to this, Ce dissolved in the ceramic material forms a chemical bond with the noble metal particles (hereinafter referred to as noble metal particles), and the noble metal particles can be fixed to the surface of the ceramic carrier. Further, since the specific surface area of the ceramic material in which Ce is dissolved is 0.2 m ² / cm ³ or more, the interval between the noble metal particles fixed on the surface of the ceramic support becomes sufficiently wide, and the grain growth of the noble metal particles is increased. It can be effectively suppressed.

  As a result, the fixing effect of the noble metal particles by the solid solution Ce and the dispersion effect of widening the interval of the noble metal particles due to the large specific surface area of the ceramic material act in combination to effectively increase the grain growth of the noble metal particles. Can be suppressed.

  As a result, the catalytic ability of the noble metal can be fully exerted, and when the amount of noble metal supported is the same, the purification performance is maintained longer than that of the exhaust gas purification catalyst body using the ceramic support of the conventional configuration. can do. In addition, when the period for maintaining the purifying capability without problems is the same, the amount of noble metal to be supported can be reduced as compared with the exhaust gas purifying catalyst body using the ceramic support body of the conventional configuration.

  In the ceramic carrier of the present invention, the ceramic material may have a sialon composition.

  It is known that sialon has α type and β type. Among these, β-sialon has been confirmed to grow as hexagonal columnar crystal particles, and can easily satisfy the conditions of specific surface area required for ceramic materials. In addition, β-sialon easily dissolves Ce, and the added Ce can be used effectively. On the other hand, α-sialon is usually difficult to dissolve even when Ce is added, but Ce can be dissolved by adding yttrium (Y). Therefore, the ceramic carrier is not limited to β-sialon and may be α-sialon.

  The ceramic carrier of the present invention can be further configured such that the Ce content in the ceramic material is 0.5 to 10 wt%.

  When the content is less than 0.5 wt%, there is a fear that Ce to be dissolved is insufficient and a required amount of noble metal particles cannot be fixed to the surface of the ceramic support. Precious metal particles that are not fixed are likely to agglomerate. On the other hand, when the content exceeds 10 wt%, Ce is not dissolved in sialon, and another phase containing Ce may be deposited on the surface of the ceramic support. In consideration of Ce precipitation, the upper limit of the Ce content is more preferably 5 wt%.

  The present invention can be suitably used for a DPF for collecting particulate matter contained in exhaust gas of a diesel engine.

1 DPF (catalyst for exhaust gas purification)
10 Honeycomb structure (ceramic carrier)
11 Cell 12 Cell wall 21 Sealing part

Claims (4)

A porous ceramic carrier that supports a noble metal having catalytic ability for exhaust gas purification on its surface,
A ceramic carrier characterized by comprising Ce as a solid solution and comprising a ceramic material having a specific surface area of 0.2 m ² / cm ³ or more.   The ceramic carrier according to claim 1, wherein the ceramic material has a sialon composition.   The ceramic carrier according to claim 2, wherein the Ce content in the ceramic material is 0.5 to 10 wt%. The ceramic carrier according to any one of claims 1 to 3,
An exhaust gas purifying catalyst body, wherein at least one of Pt, Pd, and Rh is supported on the surface of the ceramic carrier as a noble metal having catalytic ability.