JP2006088027A - Diesel particulate filter - Google Patents
Diesel particulate filter Download PDFInfo
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- 239000003054 catalyst Substances 0.000 claims abstract description 126
- 230000002093 peripheral effect Effects 0.000 claims abstract description 102
- 239000007789 gas Substances 0.000 claims abstract description 47
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 45
- 239000001301 oxygen Substances 0.000 claims abstract description 45
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 45
- 229910052751 metal Inorganic materials 0.000 claims abstract description 38
- 239000002184 metal Substances 0.000 claims abstract description 38
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 65
- 239000011232 storage material Substances 0.000 claims description 41
- 229910052783 alkali metal Inorganic materials 0.000 claims description 24
- 150000001340 alkali metals Chemical class 0.000 claims description 24
- 239000011248 coating agent Substances 0.000 claims description 21
- 238000000576 coating method Methods 0.000 claims description 21
- 238000009423 ventilation Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 27
- 238000002485 combustion reaction Methods 0.000 abstract description 16
- 150000002739 metals Chemical class 0.000 abstract description 3
- 230000007423 decrease Effects 0.000 abstract description 2
- 102100029859 Zinc finger protein neuro-d4 Human genes 0.000 abstract 2
- 230000001133 acceleration Effects 0.000 abstract 1
- 230000008642 heat stress Effects 0.000 abstract 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 111
- 239000000843 powder Substances 0.000 description 51
- 238000011068 loading method Methods 0.000 description 37
- 230000000052 comparative effect Effects 0.000 description 30
- 230000008929 regeneration Effects 0.000 description 24
- 238000011069 regeneration method Methods 0.000 description 24
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- 239000011796 hollow space material Substances 0.000 description 12
- 238000000034 method Methods 0.000 description 9
- 238000009529 body temperature measurement Methods 0.000 description 8
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 8
- 229910052700 potassium Inorganic materials 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 229910052697 platinum Inorganic materials 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 6
- 230000001737 promoting effect Effects 0.000 description 6
- 101100224414 Caenorhabditis elegans dpf-1 gene Proteins 0.000 description 5
- GWGQWFHTAOMUBD-UHFFFAOYSA-N [[3-[bis(phosphonomethyl)amino]-2-hydroxypropyl]-(phosphonomethyl)amino]methylphosphonic acid Chemical compound OP(=O)(O)CN(CP(O)(O)=O)CC(O)CN(CP(O)(O)=O)CP(O)(O)=O GWGQWFHTAOMUBD-UHFFFAOYSA-N 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
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- 238000010998 test method Methods 0.000 description 3
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- 239000011268 mixed slurry Substances 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 239000004071 soot Substances 0.000 description 2
- 239000012798 spherical particle Substances 0.000 description 2
- 101100224419 Caenorhabditis elegans dpf-2 gene Proteins 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052792 caesium Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229910052730 francium Inorganic materials 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000006262 metallic foam Substances 0.000 description 1
- UYXRCZUOJAYSQR-UHFFFAOYSA-N nitric acid;platinum Chemical compound [Pt].O[N+]([O-])=O UYXRCZUOJAYSQR-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 235000011056 potassium acetate Nutrition 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 229910052701 rubidium Inorganic materials 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Landscapes
- Exhaust Gas After Treatment (AREA)
- Filtering Materials (AREA)
- Filtering Of Dispersed Particles In Gases (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
- Processes For Solid Components From Exhaust (AREA)
Abstract
Description
本発明はディーゼルパティキュレートフィルタに関するものである。 The present invention relates to a diesel particulate filter.
ディーゼルエンジンの排気ガスに含まれている煤（soot）等のパティキュレートを排気通路に配置したフィルタで捕集するようにした場合、該フィルタに堆積したパティキュレートを適宜燃焼させて除去し、該フィルタの再生を図る必要がある。このフィルタ再生を容易にするため、フィルタにパティキュレートの燃焼促進のための触媒層をコーティングすることは知られている。しかし、フィルタ中心部は排気ガスの流速が高いためパティキュレートがフィルタ外周側よりも多く堆積し易く、その結果、フィルタ再生時にパティキュレート燃焼に伴う発熱量が多くなっている。このため、発熱量が多いフィルタ中心部と、外部から熱が奪われるフィルタ外周部との温度差が大きくなり、フィルタに熱応力によってクラック等の損傷を招くおそれがある。 When particulates such as soot contained in the exhaust gas of a diesel engine are collected by a filter disposed in the exhaust passage, the particulates accumulated in the filter are removed by burning appropriately, It is necessary to regenerate the filter. In order to facilitate the regeneration of the filter, it is known to coat the filter with a catalyst layer for promoting the combustion of particulates. However, since the exhaust gas flow rate is high in the center of the filter, more particulates are more likely to accumulate than on the outer periphery of the filter. As a result, the amount of heat generated by particulate combustion during filter regeneration increases. For this reason, the temperature difference between the filter center portion where the amount of heat generation is large and the filter outer peripheral portion from which heat is taken from the outside becomes large, and the filter may be damaged by thermal stress.
かかる問題に対して、特許文献１には、フィルタにパティキュレートの燃焼促進のための触媒層をコーティングするにあたり、そのコーティング量をフィルタ中心部で多く、フィルタ外周部で少なくすることが記載されている。これは、フィルタ中心部の触媒層を厚くすることにより、該フィルタ中心部の通気抵抗を高めてフィルタ中心部と外周部との堆積量の差を小さくするというものである。
上記特許文献に記載された技術の場合、フィルタ再生時のフィルタの中心部と外周部との温度差を小さくする効果はあるものの、フィルタの中心側は熱がこもり易い一方、外周側では熱引き（外部への熱の逃げ）により温度が下がり易いことから、フィルタの中心部と外周部とのパティキュレート堆積量の差が小さくなっても、フィルタ再生時に上記中心部と外周部とで比較的大きな温度差を生ずることは避けられない。また、フィルタ中心部の触媒層を厚く、外周部の触媒層を薄くすると、それだけフィルタ再生時にはフィルタ中心部でパティキュレートが燃焼し易くなる一方、フィルタ外周部ではパティキュレートの燃焼が進み難くなり、上記温度差を小さくする上では不利になる。 In the case of the technique described in the above-mentioned patent document, although there is an effect of reducing the temperature difference between the central portion and the outer peripheral portion of the filter at the time of filter regeneration, the center side of the filter is likely to accumulate heat, while the outer peripheral side has a heat sink. Since the temperature is likely to decrease due to (heat escape to the outside), even when the difference in the amount of particulate deposition between the center and the outer periphery of the filter becomes smaller, the center and the outer A large temperature difference is inevitable. Also, if the catalyst layer in the center of the filter is made thicker and the catalyst layer in the outer periphery is made thinner, particulates are more likely to burn at the center of the filter during filter regeneration, while it is difficult for the particulates to burn at the outer periphery of the filter. This is disadvantageous in reducing the temperature difference.
そこで、本発明は、上記パティキュレート堆積量とは別の観点から上記温度差の縮小を図り、フィルタの損傷を防止することを課題とする。 Therefore, an object of the present invention is to reduce the temperature difference from a viewpoint different from the particulate accumulation amount and prevent damage to the filter.
本発明は、このような課題に対して、フィルタの触媒層に含まれている触媒金属等の量によってパティキュレートの燃焼性が変わってくる点に着目し、フィルタ中心側よりも外周側においてパティキュレートが燃焼し易くなるようにした。 The present invention addresses such a problem by paying attention to the fact that the combustibility of the particulates changes depending on the amount of catalyst metal or the like contained in the catalyst layer of the filter, and the particulates on the outer peripheral side rather than the filter center side. Cured was made easy to burn.
すなわち、請求項１に係る発明は、ディーゼルエンジンの排気ガス中に含まれるパティキュレートを捕集するディーゼルパティキュレートフィルタであって、
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材と触媒金属とを含有する触媒層が形成されていて、
上記触媒金属が、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とする。
That is, the invention according to claim 1 is a diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
The catalyst metal is distributed more on the filter outer peripheral side than on the filter center side.
従って、フィルタの外周側は中心側よりも触媒金属量が多いことから、フィルタ再生時にはフィルタ外周側においてパティキュレートが盛んに燃焼して発熱することになり、熱引きがあっても、フィルタの中心側と外周側との温度差が大きくなることが避けられる。 Therefore, since the amount of catalyst metal is larger on the outer peripheral side of the filter than on the central side, particulates are actively burned on the outer peripheral side of the filter during the regeneration of the filter and heat is generated. An increase in temperature difference between the outer side and the outer side can be avoided.
ここに、本発明においては、フィルタ中心を通るように該フィルタを切断した面において、フィルタ中心から外周面に至る距離の中点より外周側に触媒金属が内側（中心側）よりも相対的に多く配分されていればよい。 Here, in the present invention, on the surface where the filter is cut so as to pass through the center of the filter, the catalyst metal is relatively closer to the outer peripheral side than the middle point of the distance from the filter center to the outer peripheral surface than to the inner side (center side). It only needs to be distributed a lot.
従って、フィルタ単位容積当たりの触媒金属量を、例えば、フィルタ中心から外周面までの距離の２／３の範囲において少なく、その外側において多くしたケース、上記距離の１／３の範囲において少なく、その外側において多くしたケースのいずれであっても、上記切断面においては上記中点から外側の触媒金属配分量（端的にはフィルタ容積１Ｌ当たりの触媒金属量）の方が内側の配分量よりも相対的に多くなるから、本発明に含まれることになる。このフィルタ中心側と外周側との相対関係については、次に説明する請求項２の酸素吸蔵材の配分、請求項３のアルカリ金属の配分、請求項４の中空材と中実材の配置、並びに請求項５の触媒層コーティング量に関しても同じである。 Therefore, for example, the amount of catalyst metal per unit volume of the filter is small in the range of 2/3 of the distance from the center of the filter to the outer peripheral surface, and is increased in the outside of the filter. In any of the cases increased on the outer side, the amount of catalyst metal distributed from the midpoint to the outer side (in short, the amount of catalyst metal per 1 L of filter volume) is relative to the inner side of the cut surface. Therefore, it is included in the present invention. Regarding the relative relationship between the filter center side and the outer peripheral side, the oxygen storage material distribution according to claim 2, which will be described below, the alkali metal distribution according to claim 3, the arrangement of the hollow material and the solid material according to claim 4, The same applies to the coating amount of the catalyst layer of claim 5.
触媒金属としては、例えば、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ等の貴金属を採用することがパティキュレートの燃焼促進の点で好ましい。また、上記触媒層を形成するフィルタ本体としては、多孔質セラミックスや金属製フォームからなるモノリスフィルタを採用することができる。この触媒金属及びフィルタ本体に関しては以下に述べる各発明も同じである。 As the catalyst metal, for example, a noble metal such as Pt, Pd, Rh, or Ir is preferably used from the viewpoint of promoting combustion of particulates. Moreover, as a filter main body which forms the said catalyst layer, the monolith filter which consists of porous ceramics or metal foam can be employ | adopted. The inventions described below are the same for the catalyst metal and the filter body.
請求項２に係る発明は、ディーゼルエンジンの排気ガス中に含まれるパティキュレートを捕集するディーゼルパティキュレートフィルタであって、
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材と触媒金属とを含有する触媒層が形成されていて、
上記酸素吸蔵材が、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とする。
The invention according to claim 2 is a diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
The oxygen storage material is distributed more on the filter outer peripheral side than on the filter center side.
酸素吸蔵材は、フィルタ再生時に酸素を放出してパティキュレートの燃焼を促す。従って、当該発明によれば、フィルタ外周側ではフィルタ中心側よりもパティキュレートの燃焼促進が図れ、上記請求項１に係る発明の場合と同様に上記温度差を小さくする上で有利になる。 The oxygen storage material releases oxygen during filter regeneration and promotes the burning of particulates. Therefore, according to the present invention, the combustion of particulates can be promoted more on the filter outer periphery side than on the filter center side, which is advantageous in reducing the temperature difference as in the case of the invention according to the first aspect.
上記酸素吸蔵材としては、ＣｅＯ2の他、ＣｅとＺｒ、Ｐｒ、Ｎｄなど他の金属との複酸化物であってもよい。この点は以下に述べる他の発明も同じである。 The oxygen storage material may be CeO 2 or a double oxide of Ce and other metals such as Zr, Pr and Nd. This is the same for the other inventions described below.
請求項３に係る発明は、ディーゼルエンジンの排気ガス中に含まれるパティキュレートを捕集するディーゼルパティキュレートフィルタであって、
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材とアルカリ金属と触媒金属とを含有する触媒層が形成されていて、
上記アルカリ金属が、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とする。
The invention according to claim 3 is a diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material, an alkali metal, and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
The alkali metal is distributed more on the filter outer peripheral side than on the filter center side.
上記触媒層にアルカリ金属が含まれていると、該アルカリ金属と排気ガス中のＮＯｘと反応して硝酸塩を生成し、この硝酸塩が加熱分解して生ずる活性の高い酸素がパティキュレートの燃焼を促進する。従って、当該発明によれば、フィルタ外周側ではフィルタ中心側よりもパティキュレートの燃焼促進が図れ、上記請求項１に係る発明の場合と同様に上記温度差を小さくする上で有利になる。 If the catalyst layer contains an alkali metal, it reacts with the alkali metal and NOx in the exhaust gas to form nitrate, and the highly active oxygen produced by the thermal decomposition of the nitrate promotes the combustion of particulates. To do. Therefore, according to the present invention, the combustion of particulates can be promoted more on the filter outer periphery side than on the filter center side, which is advantageous in reducing the temperature difference as in the case of the invention according to the first aspect.
上記アルカリ金属としては、Ｌｉ、Ｎａ、Ｋ、Ｒｂ、Ｃｓ及びＦｒのうちから選ばれる１種又は２種以上を採用することができる。 As said alkali metal, 1 type, or 2 or more types chosen from Li, Na, K, Rb, Cs, and Fr is employable.
請求項４に係る発明は、ディーゼルエンジンの排気ガス中に含まれるパティキュレートを捕集するディーゼルパティキュレートフィルタであって、
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材とアルカリ金属と触媒金属とを含有する触媒層が形成されていて、
上記酸素吸蔵材、アルカリ金属及び触媒金属のうちから選ばれる少なくとも２種は、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とする。
The invention according to claim 4 is a diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material, an alkali metal, and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
At least two kinds selected from the oxygen storage material, alkali metal, and catalyst metal are distributed more on the filter outer peripheral side than on the filter center side.
従って、当該発明によれば、フィルタ外周側ではフィルタ中心側よりもパティキュレートの燃焼促進が図れ、上記請求項１に係る発明の場合と同様に上記温度差を小さくする上で有利になる。 Therefore, according to the present invention, the combustion of particulates can be promoted more on the filter outer periphery side than on the filter center side, which is advantageous in reducing the temperature difference as in the case of the invention according to the first aspect.
請求項５に係る発明は、ディーゼルエンジンの排気ガス中に含まれるパティキュレートを捕集するディーゼルパティキュレートフィルタであって、
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材と触媒金属とを含有する触媒層が形成されていて、
フィルタ外周側の上記触媒層に含まれているアルミナ及び酸素吸蔵材の少なくとも一方は、その少なくとも一部が中空状であり、
フィルタ中心側の上記触媒層に含まれているアルミナ及び酸素吸蔵材は中実であることを特徴とする。
The invention according to claim 5 is a diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
At least one of alumina and the oxygen storage material contained in the catalyst layer on the filter outer peripheral side is at least partly hollow,
The alumina and the oxygen storage material contained in the catalyst layer on the filter center side are solid.
アルミナ又は酸素吸蔵材が中空状であれば、このアルミナ又は酸素吸蔵材を含む触媒層は断熱層としての効果が高くなる。そうして、当該発明によれば、フィルタ外周側の触媒層に含まれているアルミナ及び酸素吸蔵材の少なくとも一方は、その少なくとも一部が中空状であるから、その断熱効果により熱引きが少なくなり、フィルタの中心側と外周側との温度差が大きくなることが避けられる。また、中空状のアルミナ又は酸素吸蔵材は中実である場合に比べてその表面積が大きくなるから、これに触媒金属を担持させるようにした場合、触媒金属の高分散化が図れ、そのシンタリング防止にも有利になる。 If the alumina or oxygen storage material is hollow, the catalyst layer containing the alumina or oxygen storage material is highly effective as a heat insulating layer. Thus, according to the present invention, at least one of the alumina and the oxygen storage material contained in the catalyst layer on the outer peripheral side of the filter is hollow at least partly, so that the heat is not easily absorbed by the heat insulating effect. Thus, an increase in temperature difference between the center side and the outer peripheral side of the filter can be avoided. In addition, since the surface area of hollow alumina or oxygen storage material is larger than when it is solid, the catalyst metal can be highly dispersed when the catalyst metal is supported on this, and its sintering can be achieved. It is also advantageous for prevention.
請求項６に係る発明は、請求項１乃至請求項５のいずれか一において、
上記排気ガスが通る通路の通気抵抗が上記フィルタ外周側よりも上記フィルタ中心側で高くなるように、上記通路壁面の単位面積当たりの上記触媒層のコーティング量は上記フィルタ中心側の方が上記フィルタ外周側よりも多いことを特徴とする。
The invention according to claim 6 is any one of claims 1 to 5,
The coating amount of the catalyst layer per unit area of the wall surface of the passage is higher on the filter center side so that the ventilation resistance of the passage through which the exhaust gas passes is higher on the filter center side than on the filter outer peripheral side. More than the outer peripheral side.
従って、フィルタ外周側と中心側とでパティキュレート堆積量の差が大きくなること、ひいてはパティキュレートの燃焼によるフィルタ中心側の発熱量がフィルタ外周側よりも過度に大きくなることが避けられ、上記温度差を小さくする上で有利になる。 Therefore, the difference in the amount of particulate accumulation between the filter outer peripheral side and the center side is avoided, and consequently the heat generation amount on the filter center side due to the burning of the particulates is prevented from becoming excessively larger than that of the filter outer peripheral side. This is advantageous in reducing the difference.
以上のように、請求項１に係る発明によれば、触媒金属がフィルタ中心側よりも外周側に多く配分されているから、フィルタ再生時にはフィルタ外周側においてパティキュレートが盛んに燃焼することになり、熱引きがあっても、フィルタの中心側と外周側との温度差が大きくなることが避けられ、フィルタの損傷防止に有利になる。 As described above, according to the first aspect of the present invention, the catalyst metal is distributed more on the outer peripheral side than the filter center side, so that the particulates are actively burned on the filter outer peripheral side during filter regeneration. Even if heat is applied, an increase in temperature difference between the center side and the outer periphery side of the filter is avoided, which is advantageous for preventing damage to the filter.
請求項２に係る発明によれば、酸素吸蔵材がフィルタ中心側よりも外周側に多く配分されているから、フィルタ外周側でのパティキュレートの燃焼促進が図れ、上記温度差を小さくしてフィルタを損傷を防止する上で有利になる。 According to the second aspect of the present invention, since the oxygen storage material is distributed more on the outer peripheral side than the filter center side, the combustion of particulates can be promoted on the outer peripheral side of the filter, and the temperature difference is reduced and the filter is reduced. This is advantageous in preventing damage.
請求項３に係る発明によれば、アルカリ金属がフィルタ中心側よりも外周側に多く配分されているから、フィルタ外周側でのパティキュレートの燃焼促進が図れ、上記温度差を小さくしてフィルタを損傷を防止する上で有利になる。 According to the third aspect of the invention, the alkali metal is distributed more on the outer peripheral side than on the filter center side, so that the combustion of particulates on the outer peripheral side of the filter can be promoted, and the temperature difference is reduced to reduce the filter. This is advantageous in preventing damage.
請求項４に係る発明によれば、酸素吸蔵材、アルカリ金属及び触媒金属のうちから選ばれる少なくとも２種が、フィルタ中心側よりもフィルタ外周側に多く配分されているから、フィルタ外周側ではフィルタ中心側よりもパティキュレートの燃焼促進が図れ、上記請求項１に係る発明の場合と同様に上記温度差を小さくする上で有利になる。 According to the invention according to claim 4, since at least two kinds selected from the oxygen storage material, the alkali metal, and the catalyst metal are distributed more on the filter outer peripheral side than on the filter central side, the filter on the filter outer peripheral side. The combustion of the particulates can be promoted more than the center side, which is advantageous in reducing the temperature difference as in the case of the invention according to claim 1.
請求項５に係る発明によれば、フィルタ外周側の触媒層に含まれているアルミナ及び酸素吸蔵材の少なくとも一方は、その少なくとも一部が中空状であるから、熱引きが少なくなり、上記温度差を小さくしてフィルタを損傷を防止する上で有利になる。 According to the invention of claim 5, at least one of the alumina and the oxygen storage material contained in the catalyst layer on the outer peripheral side of the filter is hollow at least partially, so that the heat pulling is reduced, and the temperature This is advantageous in reducing the difference and preventing damage to the filter.
請求項６に係る発明によれば、請求項１乃至請求項５のいずれか一において、フィルタ中心側の触媒層コーティング量をフィルタ外周側よりも多くして通気抵抗がフィルタ外周側よりもフィルタ中心側で高くなるようにしたから、フィルタ外周側と中心側とでパティキュレート堆積量の差が大きくなることが避けられ、上記温度差を小さくしてフィルタを損傷を防止する上で有利になる。 According to the invention of claim 6, in any one of claims 1 to 5, the amount of catalyst layer coating on the filter center side is greater than that on the filter outer peripheral side, so that the airflow resistance is greater than that on the filter outer periphery side. Therefore, the difference in the amount of particulate deposition between the filter outer peripheral side and the center side can be avoided, and this is advantageous in reducing the temperature difference and preventing the filter from being damaged.
以下、本発明の実施形態を図面に基づいて詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
＜ＤＰＦの構造＞
図１及び図２にディーゼルパティキュレートフィルタ（以下、ＤＰＦと略す。）１を模式的に示すように、このＤＰＦ１は、ハニカム構造をなしており、互いに平行に延びる多数のセル２，３（例えば、１平方インチ（約６．５４ｃｍ2）当たりセル数３００）を備えている。すなわち、ＤＰＦ１は、下流端が栓４により閉塞された排気ガス流入セル２と、上流端が栓４により閉塞された排気ガス流出セル３とが前後左右に交互に設けられ、排気ガス流入セル２と排気ガス流出セル３とは薄肉の隔壁５を介して隔てられている。なお、図１においてハッチングを付した部分は下流端の栓４を示している。
<Structure of DPF>
As schematically shown in FIGS. 1 and 2, a diesel particulate filter (hereinafter abbreviated as DPF) 1, the DPF 1 has a honeycomb structure and has a large number of cells 2 and 3 extending in parallel to each other (for example, 300 cells per square inch (about 6.54 cm 2 ). That is, the DPF 1 is provided with an exhaust gas inflow cell 2 whose downstream end is closed by the plug 4 and an exhaust gas outflow cell 3 whose upstream end is closed by the plug 4 alternately in front, rear, left, and right. And the exhaust gas outflow cell 3 are separated by a thin partition wall 5. In FIG. 1, the hatched portion indicates the plug 4 at the downstream end.
ＤＰＦ１は、そのフィルタ本体が例えばコーディエライトやＳｉＣ焼結体のような多孔質のセラミックスによって形成されており、排気ガス流入セル２内に流入した排気ガスは図２において矢印で示したように周囲の隔壁５を通って隣接する排気ガス流出セル３内に流出する。すなわち、図３に示すように、隔壁５は排気ガス流入セル２と排気ガス流出セル３とを連通する微細な細孔通路６を有し、この細孔通路６を排気ガスが通る。このＤＰＦ１のフィルタ本体の上記排気ガス通路（排気ガス流入セル２、排気ガス流出セル３及び細孔通路６）の壁面には、ＤＰＦ再生時のパティキュレートの燃焼を促進するための触媒層７が形成されている。 The filter body of the DPF 1 is formed of porous ceramics such as cordierite or SiC sintered body, and the exhaust gas flowing into the exhaust gas inflow cell 2 is indicated by an arrow in FIG. It flows out into the adjacent exhaust gas outflow cell 3 through the surrounding partition wall 5. That is, as shown in FIG. 3, the partition wall 5 has a fine pore passage 6 communicating the exhaust gas inflow cell 2 and the exhaust gas outflow cell 3, and the exhaust gas passes through the pore passage 6. On the wall surface of the exhaust gas passage (exhaust gas inflow cell 2, exhaust gas outflow cell 3 and pore passage 6) of the filter body of the DPF 1, a catalyst layer 7 for promoting the combustion of particulates during DPF regeneration is provided. Is formed.
そうして、上記ＤＰＦ１の触媒層７にはアルミナと触媒金属とが含まれており、触媒金属は、図４に示すフィルタ中心側８で少なく、フィルタ外周側９で多くなるように配分されている。また、触媒層７には必要に応じて酸素吸蔵材やアルカリ金属が含まれ、この酸素吸蔵材やアルカリ金属に関しても、触媒金属と同様に、フィルタ中心側８で少なく、フィルタ外周側９で多くなるように配分することができる。なお、図４において、「Ｒ」はフィルタ本体の半径を表す。さらに、触媒層７のコーティング量に関しても、フィルタ中心側８で多く、フィルタ外周側９で少なくなるようにし、それによって、フィルタ中心側８の排気ガス通路２，３，６の通気抵抗をフィルタ外周側９よりも大きくすることができる。 Thus, the catalyst layer 7 of the DPF 1 contains alumina and a catalyst metal, and the catalyst metal is distributed so that it is less on the filter center side 8 shown in FIG. Yes. In addition, the catalyst layer 7 contains an oxygen storage material and an alkali metal as necessary, and the oxygen storage material and the alkali metal are small on the filter center side 8 and large on the filter outer peripheral side 9 similarly to the catalyst metal. Can be distributed. In FIG. 4, “R” represents the radius of the filter body. Further, the coating amount of the catalyst layer 7 is also increased on the filter center side 8 and decreased on the filter outer periphery side 9, thereby reducing the ventilation resistance of the exhaust gas passages 2, 3, 6 on the filter center side 8. Can be larger than side 9.
以下、実施例及び比較例に基いて行なった本発明に係る触媒の性能評価について説明する。 Hereinafter, the performance evaluation of the catalyst according to the present invention performed based on Examples and Comparative Examples will be described.
＜触媒金属の配分について＞
−実施例１−
サポート材としての活性アルミナに触媒金属としてのＰｔを担持したＰｔ担持率＝０．５質量％（但し、ここでの「質量％」は、触媒粉全量に占めるＰｔの割合ではなく、サポート材量に対するＰｔの割合であり、「０．５質量％」はサポート材量が１００質量部であるときにＰｔ量が０．５質量部であることを意味する。以下、同じ。）の第１触媒粉とＰｔ担持率＝３質量％の第２触媒粉とを、ジニトロジアミン白金硝酸溶液を活性アルミナに加えて混合し、蒸発乾固することによって調製した。これら触媒粉各々について水及びバインダと混合してスラリーを調製し、第１触媒粉をフィルタ本体の中心側８全域に、第２触媒粉をフィルタ本体の外周側９全域に、それぞれウォッシュコートして排気ガス通路壁面に触媒層を形成した。フィルタ中心側８及びフィルタ外周側のうちの一方にウォッシュコートするときは他方にマスキングを施した。
<Distribution of catalyst metal>
Example 1
Pt loading ratio in which activated alumina as a support material carries Pt as a catalyst metal = 0.5% by mass (where “mass%” is not the proportion of Pt in the total amount of catalyst powder, but the amount of support material) The ratio of Pt to “0.5 mass%” means that when the amount of support material is 100 parts by mass, the amount of Pt is 0.5 parts by mass. The powder and the second catalyst powder having a Pt loading rate of 3% by mass were prepared by adding a dinitrodiamine platinum nitric acid solution to activated alumina, mixing, and evaporating to dryness. Each of these catalyst powders is mixed with water and a binder to prepare a slurry, and the first catalyst powder is wash coated on the entire center side 8 of the filter body, and the second catalyst powder is washed on the entire outer periphery side 9 of the filter body. A catalyst layer was formed on the wall surface of the exhaust gas passage. When wash coating was applied to one of the filter center side 8 and the filter outer peripheral side, the other was masked.
フィルタ本体は、直径１４３．７ｍｍ、長さ１５２．４ｍｍのハニカム構造の円筒状のものであり、触媒粉のコート量は、サポート材量が、フィルタ中心側８では１００ｇ／Ｌ（フィルタ容積１Ｌ当たり量のこと。以下、同じ。）、フィルタ外周側９では５０ｇ／Ｌとなるようにした。従って、フィルタ中心側８のＰｔ担持量は０．５ｇ／Ｌ、フィルタ外周側９のＰｔ担持量は１．５ｇ／Ｌである。 The filter body has a cylindrical structure with a honeycomb structure having a diameter of 143.7 mm and a length of 152.4 mm. The coating amount of the catalyst powder is 100 g / L on the filter center side 8 (per 1 L of filter volume). The same applies hereinafter), and the filter outer peripheral side 9 was set to 50 g / L. Therefore, the Pt carrying amount on the filter center side 8 is 0.5 g / L, and the Pt carrying amount on the filter outer peripheral side 9 is 1.5 g / L.
−比較例１−
活性アルミナにＰｔを担持した触媒粉（Ｐｔ担持率＝２質量％）を実施例１と同じ方法で調製し、同じくバインダを含むスラリーとし、実施例１と同じフィルタ本体全体にわたって均一にウォッシュコートした。コート量はサポート材量が６２．５ｇ／Ｌとなるようにした。従って、フィルタ本体におけるＰｔ担持量は１．２５ｇ／Ｌである。
-Comparative Example 1-
A catalyst powder having Pt supported on activated alumina (Pt support rate = 2 mass%) was prepared by the same method as in Example 1, and was also made into a slurry containing a binder, and was uniformly coated over the same filter body as in Example 1. . The amount of support was such that the amount of support material was 62.5 g / L. Therefore, the Pt carrying amount in the filter body is 1.25 g / L.
−比較例２−
比較例１と同じ触媒粉（Ｐｔ担持率＝２質量％）を同じくバインダを含むスラリーとして、実施例１と同じフィルタ本体に対して、サポート材量がフィルタ中心側８では１００ｇ／Ｌ、フィルタ外周側９では５０ｇ／Ｌとなるようにウォッシュコートした。従って、フィルタ中心側８のＰｔ担持量は２ｇ／Ｌ、フィルタ外周側９のＰｔ担持量は１ｇ／Ｌである。
-Comparative Example 2-
The same catalyst powder as in Comparative Example 1 (Pt loading rate = 2 mass%) is also made into a slurry containing a binder, and the amount of support material is 100 g / L on the filter center side 8 with respect to the same filter body as in Example 1, Side 9 was wash coated to 50 g / L. Therefore, the Pt carrying amount on the filter center side 8 is 2 g / L, and the Pt carrying amount on the filter outer peripheral side 9 is 1 g / L.
（評価テスト）
実施例１及び比較例１，２の各ＤＰＦについて、エンジンベンチテストで性能評価を行った。すなわち、ＤＰＦにパティキュレート（煤）を８ｇ／Ｌ堆積させた後、エンジン制御によってＤＰＦ入口温度を６００℃に上昇させてパティキュレートを着火させた。次いでエンジンをアイドル運転に切り替えて排気ガス流量を低くするとともに、該排気ガスの酸素濃度を高めることにより、パティキュレートを急速に燃焼させ、図４に示すＤＰＦ出口側３カ所Ａ〜Ｃの温度を熱電対により測定した。Ａはフィルタ中心位置、Ｂはフィルタ中心から半径の１／２距離だけ外側に寄った位置、Ｃはフィルタ外周縁近傍であり、各熱電対はＤＰＦの下流側の端面から１ｃｍ程度内側に入った位置の温度を測定するようにした。結果は表１及び図５に示されている。
(Evaluation test)
About each DPF of Example 1 and Comparative Examples 1 and 2, performance evaluation was performed by the engine bench test. That is, 8 g / L of particulate (soot) was deposited on the DPF, and then the DPF inlet temperature was raised to 600 ° C. by engine control to ignite the particulate. Next, the engine is switched to idle operation to lower the exhaust gas flow rate, and the oxygen concentration of the exhaust gas is increased, so that the particulates are rapidly burned, and the temperatures of the three DPF outlet side AC shown in FIG. Measured with a thermocouple. A is the center position of the filter, B is a position that is outside the filter center by a distance of ½ of the radius, C is the vicinity of the outer periphery of the filter, and each thermocouple enters about 1 cm from the downstream end face of the DPF. The temperature at the position was measured. The results are shown in Table 1 and FIG.
ＡとＣの温度差が比較例２では５００℃弱であるのに対して、実施例１では３５０℃程度であり、実施例１のようにフィルタ外周側９のＰｔ配分量をフィルタ中心側８よりも多くすると、ＤＰＦ再生時のフィルタ中心部と外周部との温度差が小さくなり、ＤＰＦの損傷防止に有効であることがわかる。 The temperature difference between A and C is a little less than 500 ° C. in the comparative example 2, whereas it is about 350 ° C. in the first embodiment. As in the first embodiment, the Pt distribution amount on the filter outer peripheral side 9 is set to the filter center side 8. If it is more, the temperature difference between the filter center and the outer periphery during DPF regeneration becomes smaller, and it can be seen that this is effective in preventing damage to the DPF.
比較例２は、比較例１よりもフィルタ中心側８のＰｔ担持量が多いが、上記温度差は比較例１よりも小さくなっている。これは、フィルタ中心側８の触媒コート量を外周側９よりも多くしたことによる効果、すなわち、フィルタ中心側８の通気抵抗が外周側９よりも大きくなって、中心部と外周部とのパティキュレートの堆積量の差が小さくなったことによる効果である。実施例１もフィルタ中心側８の触媒コート量が外周側９よりも多くなっているから、同様の効果が得られている。 In Comparative Example 2, the amount of Pt supported on the filter center side 8 is larger than that in Comparative Example 1, but the temperature difference is smaller than that in Comparative Example 1. This is because the catalyst coating amount on the filter center side 8 is larger than that on the outer periphery side 9, that is, the ventilation resistance on the filter center side 8 is larger than that on the outer periphery side 9. This is due to the fact that the difference in the amount of deposited curate is reduced. Since the amount of catalyst coating on the filter center side 8 is larger than that on the outer peripheral side 9 in Example 1, the same effect is obtained.
（中心側及び外周側の各Ｐｔ担持量が温度差に与える影響）
上記実施例１に関して、フィルタ中心側８及び外周側９の各Ｐｔ担持率を適宜変化させたＤＰＦを作製し、上記評価テスト方法でＡとＣとの温度差を測定した。結果は表２及び図６に示されている。
(Effects of Pt loading on the center side and outer periphery side on temperature difference)
Regarding Example 1 above, DPFs were prepared in which the Pt carrying ratios on the filter center side 8 and the outer peripheral side 9 were appropriately changed, and the temperature difference between A and C was measured by the above evaluation test method. The results are shown in Table 2 and FIG.
フィルタ中心側のＰｔ担持率を０．１質量％（Ｐｔ担持量０．１ｇ／Ｌ）としたケースでは上記温度差が小さくなっている。これは、フィルタ中心側のＰｔ担持量が少ないため、再生時に該中心側の温度が上がらないことによるものである。ＤＰＦの再生速度は当該中心側の温度に依存するから、当該ケースは上記温度差が小さくてもＤＰＦの速やかな再生の観点からは好ましくない。一方、フィルタ中心側のＰｔ担持率を１．５質量％（Ｐｔ担持量１．５ｇ／Ｌ）としたケースでは、該中心側の温度が上昇し易いため、再生速度の観点からは好ましいものの、上記温度差が大きくなっており、ＤＰＦの破損防止に不利になってくる。なお、当該触媒には、アルミナの他に酸素吸蔵材やアルカリ土類金属が含まれていてもよい。 In the case where the Pt carrying rate on the filter center side is 0.1% by mass (Pt carrying amount 0.1 g / L), the temperature difference is small. This is because the amount of Pt supported on the filter center side is small, and the temperature on the center side does not rise during regeneration. Since the regeneration speed of the DPF depends on the temperature on the center side, the case is not preferable from the viewpoint of prompt regeneration of the DPF even if the temperature difference is small. On the other hand, in the case where the Pt loading rate on the filter center side is 1.5% by mass (Pt loading amount 1.5 g / L), the temperature on the center side tends to rise, which is preferable from the viewpoint of the regeneration speed, The temperature difference is large, which is disadvantageous for preventing damage to the DPF. Note that the catalyst may contain an oxygen storage material or an alkaline earth metal in addition to alumina.
フィルタ外周側のＰｔ担持率を１．５質量％（Ｐｔ担持量０．７５ｇ／Ｌ）としたケースでは、ＤＰＦ全体の温度が上がり難いため、上記温度差が小さい場合でも再生速度の観点からは不利になってくる。一方、フィルタ外周側のＰｔ担持率を大きくすることは、再生速度上昇及び上記温度差の縮小の観点から好ましいが、Ｐｔ担持率が８質量％を越える（例えば、９質量％（Ｐｔ担持量４．５ｇ／Ｌ））ようにしても、効果が飽和してくることから、コスト高になるだけになる。 In the case where the Pt carrying rate on the filter outer peripheral side is 1.5 mass% (Pt carrying amount 0.75 g / L), the temperature of the entire DPF is difficult to rise. Therefore, even when the temperature difference is small, from the viewpoint of the regeneration speed. It will be disadvantageous. On the other hand, increasing the Pt loading rate on the filter outer peripheral side is preferable from the viewpoint of increasing the regeneration speed and reducing the temperature difference, but the Pt loading rate exceeds 8% by mass (for example, 9% by mass (Pt carrying amount 4 .5 g / L)), the effect is saturated and only the cost is increased.
従って、ＤＰＦの損傷を招くことなく速やかな再生を図るためには、実施例１の場合、フィルタ中心側のＰｔ担持量を０．１ｇ／Ｌよりも多く且つ１．５ｇ／Ｌよりも少なくし、フィルタ外周側のＰｔ担持量を０．７５ｇ／Ｌよりも多く且つ４．５ｇ／Ｌよりも少なくすることが好ましいということができる。特に、表２の太線で囲まれた範囲、すなわち、フィルタ中心側のＰｔ担持量を０．２５ｇ／Ｌ以上１．２５ｇ／Ｌ以下、フィルタ外周側のＰｔ担持量を１ｇ／Ｌ以上４ｇ／Ｌ以下とすることが好ましい。 Therefore, in order to achieve rapid regeneration without causing damage to the DPF, in the case of Example 1, the amount of Pt supported on the filter center side is set to be larger than 0.1 g / L and smaller than 1.5 g / L. It can be said that it is preferable that the amount of Pt supported on the outer peripheral side of the filter is larger than 0.75 g / L and smaller than 4.5 g / L. In particular, the range surrounded by the thick line in Table 2, that is, the Pt carrying amount on the filter center side is 0.25 g / L or more and 1.25 g / L or less, and the Pt carrying amount on the filter outer periphery side is 1 g / L or more and 4 g / L. The following is preferable.
＜酸素吸蔵材の配分について＞
−実施例２−
酸素吸蔵材としてのＣｅＯ2と活性アルミナとの混合物（サポート材）にＰｔを蒸発乾固法によって担持した２種類の触媒粉、すなわち、ＣｅＯ2混合率（Ｐｔのサポート材であるＣｅＯ2と活性アルミナとの混合物全量に占めるＣｅＯ2の割合）＝６質量％のサポート材にＰｔをＰｔ担持率＝０．５質量％で担持した第１触媒粉と、ＣｅＯ2混合率＝８０質量％のサポート材にＰｔをＰｔ担持率＝０．５質量％で担持した第２触媒粉とを調製した。これら触媒粉各々について水及びバインダと混合してスラリーを調製し、第１触媒粉を実施例１と同じフィルタ本体の中心側８全域に、第２触媒粉をフィルタ本体の外周側９全域に、それぞれウォッシュコートした。コート量はサポート材量がフィルタ中心側８では１００ｇ／Ｌ、フィルタ外周側９では５０ｇ／Ｌとなるようにした。
<Distribution of oxygen storage material>
-Example 2-
Two types of catalyst powders in which Pt is supported on a mixture (support material) of CeO 2 and activated alumina as an oxygen storage material by evaporation to dryness, that is, CeO 2 mixing ratio (CeO 2 which is a support material of Pt and activity) The ratio of CeO 2 in the total amount of the mixture with alumina) = a first catalyst powder in which Pt is supported on a support material of 6% by mass with a Pt support rate of 0.5% by mass, and a support of CeO 2 mixing rate = 80% by mass A second catalyst powder in which Pt was supported on the material at a Pt supporting rate of 0.5% by mass was prepared. For each of these catalyst powders, a slurry is prepared by mixing with water and a binder, the first catalyst powder is in the same region of the central side 8 of the filter body as in Example 1, and the second catalyst powder is in the entire region of the outer peripheral side 9 of the filter body. Each was washcoated. The coating amount was such that the amount of support material was 100 g / L on the filter center side 8 and 50 g / L on the filter outer peripheral side 9.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；ＣｅＯ2＝６ｇ／Ｌ，アルミナ＝９４ｇ／Ｌ，Ｐｔ＝０．５ｇ／Ｌ
外周側；ＣｅＯ2＝４０ｇ／Ｌ，アルミナ＝１０ｇ／Ｌ，Ｐｔ＝０．２５ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side; CeO 2 = 6 g / L, alumina = 94 g / L, Pt = 0.5 g / L
Outer peripheral side: CeO 2 = 40 g / L, alumina = 10 g / L, Pt = 0.25 g / L
It is.
−比較例３−
実施例２と同じ方法で調製したＣｅＯ2と活性アルミナとＰｔとを含む、ＣｅＯ2混合率＝５０質量％のサポート材にＰｔをＰｔ担持率＝０．５質量％で担持した触媒粉を、バインダを含むスラリーとし、実施例１と同じフィルタ本体全体にわたって均一にウォッシュコートした。各成分のフィルタにおける担持量は、ＣｅＯ2＝３１．３ｇ／Ｌ，アルミナ＝３１．３ｇ／Ｌ，Ｐｔ＝０．３１ｇ／Ｌである。
-Comparative Example 3-
A catalyst powder comprising CeO 2 , activated alumina, and Pt prepared in the same manner as in Example 2 and having Pt supported at 0.5% by mass on a support material with a CeO 2 mixing rate = 50% by mass, A slurry containing a binder was used, and the same filter body as in Example 1 was uniformly coated over the entire filter body. The loading of each component in the filter is CeO 2 = 31.3 g / L, alumina = 31.3 g / L, and Pt = 0.31 g / L.
−比較例４−
実施例２と同じ方法で調製したＣｅＯ2と活性アルミナとＰｔとを含む、ＣｅＯ2混合率＝５０質量％のサポート材にＰｔをＰｔ担持率＝０．５質量％で担持した触媒粉を、バインダを含むスラリーとして、実施例１と同じフィルタ本体に、サポート材量が、フィルタ中心側８に１００ｇ／Ｌ、フィルタ外周側９に５０ｇ／Ｌとなるように、それぞれ実施例２と同じ方法でウォッシュコートした。
-Comparative Example 4-
A catalyst powder comprising CeO 2 , activated alumina, and Pt prepared in the same manner as in Example 2 and having Pt supported at 0.5% by mass on a support material with a CeO 2 mixing rate = 50% by mass, As a slurry containing a binder, in the same filter body as in Example 1, the amount of support material is 100 g / L on the filter center side 8 and 50 g / L on the filter outer peripheral side 9 in the same manner as in Example 2. Wash coated.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；ＣｅＯ2＝５０ｇ／Ｌ，アルミナ＝５０ｇ／Ｌ，Ｐｔ＝０．５ｇ／Ｌ
外周側；ＣｅＯ2＝２５ｇ／Ｌ，アルミナ＝２５ｇ／Ｌ，Ｐｔ＝０．２５ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side; CeO 2 = 50 g / L, alumina = 50 g / L, Pt = 0.5 g / L
Outer peripheral side: CeO 2 = 25 g / L, alumina = 25 g / L, Pt = 0.25 g / L
It is.
（評価テスト）
実施例２及び比較例３，４の各ＤＰＦについて、先に説明した触媒金属の配分に関する評価と同じ方法でＡ〜Ｃの温度を測定した。結果は表３及び図７に示されている。
(Evaluation test)
About each DPF of Example 2 and Comparative Examples 3 and 4, the temperature of AC was measured by the same method as evaluation regarding distribution of the catalyst metal demonstrated previously. The results are shown in Table 3 and FIG.
ＡとＣの温度差が比較例４では５７５℃であるのに対して、実施例２では３８０℃であり、実施例２のようにフィルタ外周側９のＣｅＯ2配分量をフィルタ中心側８よりも多くすると、ＤＰＦ再生時のフィルタ中心部と外周部との温度差が小さくなり、ＤＰＦの損傷防止に有効であることがわかる。また、触媒コート量をフィルタ全体にわたって均一にした比較例３の上記温度差は６５０℃弱であって、この温度差は比較例４の方が小さくなっている。これはフィルタ中心側の触媒コート量をフィルタ外周側よりも多くしたことによる効果が出たものであって、この効果は実施例２でも得られている。 While the temperature difference between A and C is 575 ° C. in Comparative Example 4, it is 380 ° C. in Example 2, and the CeO 2 distribution amount on the filter outer peripheral side 9 is smaller than the filter center side 8 as in Example 2. If the number is increased, the temperature difference between the filter center and the outer periphery during DPF regeneration is reduced, which is effective in preventing damage to the DPF. Further, the temperature difference in Comparative Example 3 in which the catalyst coating amount was made uniform over the entire filter was a little less than 650 ° C., and this temperature difference was smaller in Comparative Example 4. This is because the effect of increasing the amount of catalyst coating on the center side of the filter than on the outer periphery side of the filter is obtained. This effect is also obtained in the second embodiment.
（中心側及び外周側の各ＣｅＯ2量が温度差に与える影響）
上記実施例２に関して、フィルタ中心側８及び外周側９の各ＣｅＯ2混合率を適宜変化させたＤＰＦを作製し、上記評価テスト方法でＡとＣとの温度差を測定した。結果は表４及び図８に示されている。
(Effect of each CeO 2 amount on the center side and outer periphery side on the temperature difference)
Regarding Example 2, a DPF in which the CeO 2 mixing ratios on the filter center side 8 and the outer peripheral side 9 were appropriately changed was produced, and the temperature difference between A and C was measured by the above evaluation test method. The results are shown in Table 4 and FIG.
フィルタ中心側のＣｅＯ2混合率を１質量％（ＣｅＯ2担持量１ｇ／Ｌ）としたケースでは上記温度差が小さくなっているが、これは、パティキュレート燃焼促進のためのＣｅＯ2が不足し、再生時に該中心側の温度が上がらないことによるものである。一方、フィルタ中心側のＣｅＯ2混合率を１０質量％（ＣｅＯ2担持量１０ｇ／Ｌ）としたケースでは、該中心側の温度が上昇し易いため、再生速度の観点からは好ましいものの、上記温度差が大きくなっており、ＤＰＦの破損防止に不利になってくる。 In the case where the CeO 2 mixing ratio on the filter center side is 1% by mass (CeO 2 loading 1 g / L), the above temperature difference is small, but this is insufficient for CeO 2 for promoting particulate combustion. This is because the temperature on the center side does not rise during reproduction. On the other hand, in the case where the CeO 2 mixing ratio on the filter center side is 10% by mass (CeO 2 loading 10 g / L), the temperature on the center side is likely to rise. The difference is large, which is disadvantageous for preventing damage to the DPF.
フィルタ外周側のＣｅＯ2混合率を１０質量％（ＣｅＯ2担持量５ｇ／Ｌ）としたケースでは、ＤＰＦ全体の温度が上がり難いため、上記温度差が小さい場合でも再生速度の観点からは不利になってくる。一方、フィルタ外周側のＣｅＯ2混合率を大きくすることは、再生速度上昇及び上記温度差の縮小の観点から好ましいが、９０質量％（ＣｅＯ2担持量４５ｇ／Ｌ）を越えて多くしても、効果が飽和してくる。 In the case where the CeO 2 mixing ratio on the filter outer peripheral side is 10% by mass (CeO 2 loading 5 g / L), the temperature of the entire DPF is difficult to rise, so even if the temperature difference is small, it is disadvantageous from the viewpoint of regeneration speed. It becomes. On the other hand, it is preferable to increase the CeO 2 mixing ratio on the filter outer peripheral side from the viewpoint of increasing the regeneration speed and reducing the temperature difference, but if it exceeds 90% by mass (CeO 2 loading 45 g / L), The effect is saturated.
従って、ＤＰＦの損傷を招くことなく速やかな再生を図るためには、実施例２の場合、フィルタ中心側のＣｅＯ2担持量を１ｇ／Ｌよりも多く且つ１０ｇ／Ｌよりも少なくし、フィルタ外周側のＣｅＯ2担持量を５ｇ／Ｌよりも多く且つ４５ｇ／Ｌ以下とすることが好ましいということができる。特に、表４の太線で囲まれた範囲、すなわち、フィルタ中心側のＣｅＯ2担持量を２ｇ／Ｌ以上８ｇ／Ｌ以下、フィルタ外周側のＣｅＯ2担持量を１０ｇ／Ｌ以上４５ｇ／Ｌ以下とすることが好ましい。なお、当該触媒には、アルミナや酸素吸蔵材の他に、アルカリ金属やアルカリ土類金属が含まれていてもよい。 Therefore, in order to achieve rapid regeneration without causing damage to the DPF, in the case of Example 2, the amount of CeO 2 supported on the filter center side is more than 1 g / L and less than 10 g / L, and It can be said that the CeO 2 loading on the side is preferably more than 5 g / L and not more than 45 g / L. In particular, the range surrounded by the thick line in Table 4, that is, the amount of CeO 2 supported on the center side of the filter is 2 g / L or more and 8 g / L or less, and the amount of CeO 2 supported on the outer periphery of the filter is 10 g / L or more and 45 g / L or less. It is preferable to do. The catalyst may contain an alkali metal or an alkaline earth metal in addition to alumina and an oxygen storage material.
＜アルカリ金属の配分について＞
−実施例３−
活性アルミナ（サポート材）にアルカリ金属としてのＫ（カリウム）とＰｔとを蒸発乾固法によって担持した２種類の触媒粉、すなわち、Ｋ担持率＝３質量％（但し、ここでの「質量％」は、触媒粉全量に占めるＫの割合ではなく、サポート材量に対するＫの割合であり、「３質量％」はサポート材量が１００質量部であるときにＫ量が３質量部であることを意味する。以下、同じ。）、Ｐｔ担持率＝０．５質量％の第１触媒粉と、Ｋ担持率＝３０質量％、Ｐｔ担持率＝０．５質量％の第２触媒粉とを調製した。カリウム源としては酢酸カリウム水溶液を用いた。これら触媒粉各々について水及びバインダと混合してスラリーを調製し、第１触媒粉を実施例１と同じフィルタ本体の中心側８全域に、第２触媒粉をフィルタ本体の外周側９全域に、それぞれウォッシュコートした。コート量は、サポート材量がフィルタ中心側８では１００ｇ／Ｌ、フィルタ外周側９では５０ｇ／Ｌとなるようにした。
<Alkali metal distribution>
Example 3
Two types of catalyst powders in which K (potassium) and Pt as alkali metals are supported on activated alumina (support material) by evaporation to dryness, that is, K support rate = 3% by mass (however, “% by mass” here) "Is not the ratio of K to the total amount of catalyst powder, but the ratio of K to the amount of support material, and" 3% by mass "is that the amount of K is 3 parts by mass when the amount of support material is 100 parts by mass. The same applies hereinafter.), A first catalyst powder having a Pt loading rate of 0.5% by mass, and a second catalyst powder having a K loading rate of 30% by mass and a Pt loading rate of 0.5% by mass. Prepared. An aqueous potassium acetate solution was used as the potassium source. For each of these catalyst powders, a slurry is prepared by mixing with water and a binder, the first catalyst powder is in the same region of the central side 8 of the filter body as in Example 1, and the second catalyst powder is in the entire region of the outer peripheral side 9 of the filter body. Each was washcoated. The coating amount was 100 g / L on the filter center side 8 and 50 g / L on the filter outer peripheral side 9.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；Ｋ＝３ｇ／Ｌ，Ｐｔ＝０．５ｇ／Ｌ，活性アルミナ＝１００ｇ／Ｌ
外周側；Ｋ＝１５ｇ／Ｌ，Ｐｔ＝０．２５ｇ／Ｌ，活性アルミナ＝５０ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side: K = 3 g / L, Pt = 0.5 g / L, activated alumina = 100 g / L
Outer peripheral side: K = 15 g / L, Pt = 0.25 g / L, activated alumina = 50 g / L
It is.
−比較例５−
実施例３と同じ方法で調製したＫと活性アルミナとＰｔとを含む、Ｋ担持率＝２０質量％、Ｐｔ担持率＝０．５質量％の触媒粉を、バインダを含むスラリーとして、実施例１と同じフィルタ本体全体にわたって均一にウォッシュコートした。各成分のフィルタにおける担持量は、Ｋ＝１２．５ｇ／Ｌ、Ｐｔ＝０．３１ｇ／Ｌ、アルミナ＝６２．５ｇ／Ｌである。
-Comparative Example 5-
A catalyst powder containing K, activated alumina and Pt prepared in the same manner as in Example 3 and having a K loading rate of 20 mass% and a Pt loading rate of 0.5 mass% was used as a slurry containing a binder. Was uniformly coated over the same filter body. The loadings of each component in the filter are K = 12.5 g / L, Pt = 0.31 g / L, and alumina = 62.5 g / L.
−比較例６−
実施例３と同じ方法で調製したＫと活性アルミナとＰｔとを含む、Ｋ担持率＝２０質量％、Ｐｔ担持率＝０．５質量％の触媒粉を、バインダを含むスラリーとして、実施例１と同じフィルタ本体に、サポート材量が、中心側８に１００ｇ／Ｌ、外周側９に５０ｇ／Ｌとなるように、それぞれ実施例３と同じ方法でウォッシュコートした。
-Comparative Example 6
Example 1 A catalyst powder containing K, activated alumina, and Pt prepared in the same manner as in Example 3 and having a K loading rate of 20 mass% and a Pt loading rate of 0.5 mass% was used as a slurry containing a binder. The same filter body as that of Example 3 was wash-coated by the same method as in Example 3 so that the amount of support material was 100 g / L on the center side 8 and 50 g / L on the outer peripheral side 9.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；Ｋ＝２０ｇ／Ｌ，Ｐｔ＝０．５ｇ／Ｌ，アルミナ＝１００ｇ／Ｌ
外周側；Ｋ＝１０ｇ／Ｌ，Ｐｔ＝０．２５ｇ／Ｌ，アルミナ＝５０ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side: K = 20 g / L, Pt = 0.5 g / L, alumina = 100 g / L
Outer peripheral side: K = 10 g / L, Pt = 0.25 g / L, alumina = 50 g / L
It is.
（評価テスト）
実施例３及び比較例５，６の各ＤＰＦについて、先に説明した触媒金属の配分に関する評価と同じ方法でＡ〜Ｃの温度を測定した。結果は表５及び図９に示されている。
(Evaluation test)
About each DPF of Example 3 and Comparative Examples 5 and 6, the temperature of AC was measured by the same method as evaluation regarding distribution of the catalyst metal demonstrated previously. The results are shown in Table 5 and FIG.
ＡとＣの温度差が比較例６では５３５℃であるのに対して、実施例３では３６０℃であり、実施例３のようにフィルタ外周側９のＫ配分量をフィルタ中心側８よりも多くすると、ＤＰＦ再生時のフィルタ中心部と外周部との温度差が小さくなり、ＤＰＦの損傷防止に有効であることがわかる。また、触媒コート量をフィルタ全体にわたって均一にした比較例５の上記温度差は６７０℃であって、この温度差は比較例６の方が小さくなっている。これはフィルタ中心側の触媒コート量をフィルタ外周側よりも多くしたことによる効果が出たものであって、この効果は実施例３でも得られている。 The temperature difference between A and C is 535 ° C. in the comparative example 6, whereas it is 360 ° C. in the third embodiment. As in the third embodiment, the K distribution amount on the filter outer peripheral side 9 is larger than that on the filter center side 8. If it increases, it turns out that the temperature difference of the filter center part at the time of DPF reproduction | regeneration and an outer peripheral part becomes small, and it is effective in the damage prevention of DPF. In addition, the temperature difference of Comparative Example 5 in which the catalyst coating amount is uniform over the entire filter is 670 ° C., and this temperature difference is smaller in Comparative Example 6. This is because the effect of increasing the amount of catalyst coating on the center side of the filter than on the outer periphery side of the filter is obtained. This effect is also obtained in the third embodiment.
（中心側及び外周側の各Ｐｔ担持量が温度差に与える影響）
上記実施例３に関して、フィルタ中心側８及び外周側９の各Ｋ担持率を適宜変化させたＤＰＦを作製し、上記評価テスト方法でＡとＣとの温度差を測定した。結果は表６及び図１０に示されている。
(Effects of Pt loading on the center side and outer periphery side on temperature difference)
Regarding Example 3, a DPF in which the K carrying ratios on the filter center side 8 and the outer peripheral side 9 were appropriately changed was produced, and the temperature difference between A and C was measured by the above evaluation test method. The results are shown in Table 6 and FIG.
フィルタ中心側のＫ担持率を０．５質量％（Ｋ担持量０．５ｇ／Ｌ）としたケースでは上記温度差が小さくなっているが、これは、パティキュレート燃焼促進のためのＫ担持量が少ないため、再生時に該中心側の温度が上がらないことによるものである。一方、フィルタ中心側のＫ担持率を５質量％（Ｋ担持量５ｇ／Ｌ）としたケースでは、該中心側の温度が上昇し易いため、再生速度の観点からは好ましいものの、上記温度差が大きくなっており、ＤＰＦの破損防止に不利になってくる。 In the case where the K carrying rate on the filter center side is 0.5 mass% (K carrying amount 0.5 g / L), the temperature difference is small. This is because the K carrying amount for promoting particulate combustion. This is because the temperature on the center side does not rise during reproduction. On the other hand, in the case where the K carrying rate on the filter center side is 5 mass% (K carrying amount 5 g / L), the temperature on the center side is likely to rise. It is large and disadvantageous for preventing damage to the DPF.
フィルタ外周側のＫ担持率を５質量％（Ｋ担持量２．５ｇ／Ｌ）としたケースでは、ＤＰＦ全体の温度が上がり難いため、上記温度差が小さい場合でも再生速度の観点からは不利になってくる。一方、フィルタ外周側のＫ担持率を大きくすることは、再生速度上昇及び上記温度差の縮小の観点から好ましいが、Ｋ担持率が３５質量％を越える（例えば４０質量％（Ｋ担持量２０ｇ／Ｌ））ようにしても、効果が飽和してくる。 In the case where the K carrying ratio on the filter outer peripheral side is 5% by mass (K carrying amount 2.5 g / L), the temperature of the entire DPF is difficult to rise. Therefore, even if the temperature difference is small, it is disadvantageous from the viewpoint of the regeneration speed. It becomes. On the other hand, increasing the K carrying rate on the filter outer peripheral side is preferable from the viewpoint of increasing the regeneration speed and reducing the temperature difference, but the K carrying rate exceeds 35% by mass (for example, 40% by mass (K carrying amount 20g / L)), the effect is saturated.
従って、ＤＰＦの損傷を招くことなく速やかな再生を図るためには、実施例３の場合、フィルタ中心側のＫ担持量を０．５ｇ／Ｌよりも多く且つ５ｇ／Ｌよりも少なくし、フィルタ外周側のＫ担持量を２．５ｇ／Ｌよりも多く且つ２０ｇ／Ｌよりも少なくすることが好ましいということができる。特に、表６の太線で囲まれた範囲、すなわち、フィルタ中心側のＫ担持量を１ｇ／Ｌ以上４ｇ／Ｌ以下、フィルタ外周側のＫ担持量を５ｇ／Ｌ以上１７．５ｇ／Ｌ以下とすることが好ましい。 Therefore, in order to promptly regenerate without damaging the DPF, in the case of Example 3, the K carrying amount on the filter center side is more than 0.5 g / L and less than 5 g / L. It can be said that it is preferable that the amount of K supported on the outer peripheral side is larger than 2.5 g / L and smaller than 20 g / L. In particular, the range surrounded by the thick line in Table 6, that is, the K carrying amount on the filter center side is 1 g / L or more and 4 g / L or less, and the K carrying amount on the filter outer periphery side is 5 g / L or more and 17.5 g / L or less. It is preferable to do.
以上のように、実施例１〜３により、触媒貴金属、酸素吸蔵材、又はアルカリ金属をフィルタ中心側よりもフィルタ外周側に多く配分すると、ＤＰＦの破損防止に有利になることが理解できる。また、以上の結果から、触媒貴金属及び酸素吸蔵材両者の配分を共に、触媒貴金属及びアルカリ金属両者の配分を共に、酸素吸蔵材及びアルカリ金属両者の配分を共に、或いは触媒貴金属、酸素吸蔵材及びアルカリ金属三者の配分を共に、フィルタ中心側よりもフィルタ外周側に多くした場合にも、同様の効果が得られることを期待できることわかるであろう。そこで、次に触媒貴金属、酸素吸蔵材及びアルカリ金属三者の配分を共に、フィルタ中心側よりもフィルタ外周側に多くした例について説明する。 As described above, according to Examples 1 to 3, it can be understood that it is advantageous for preventing the DPF from being damaged if more catalyst noble metal, oxygen storage material, or alkali metal is distributed to the filter outer peripheral side than to the filter central side. Further, from the above results, both the distribution of both the catalyst noble metal and the oxygen storage material, the distribution of both the catalyst noble metal and the alkali metal, the distribution of both the oxygen storage material and the alkali metal, or the catalyst noble metal, the oxygen storage material and It will be understood that the same effect can be expected even when the distribution of the three alkali metals is increased to the filter outer peripheral side rather than the filter central side. Therefore, an example in which the distribution of the catalyst precious metal, the oxygen storage material, and the alkali metal is increased to the filter outer peripheral side rather than the filter central side will be described.
＜Ｐｔ、ＣｅＯ2及びＫを含むケース＞
−実施例４−
ＣｅＯ2と活性アルミナとの混合物（サポート材）にＰｔ及びＫを蒸発乾固法によって担持した２種類の触媒粉、すなわち、ＣｅＯ2混合率＝６質量％のサポート材に、Ｐｔ担持率＝０．５質量％、Ｋ担持率＝３質量％となるようにＰｔ及びＫを担持させた第１触媒粉と、ＣｅＯ2混合率＝８０質量％のサポート材に、Ｐｔ担持率＝３質量％、Ｋ担持率＝３０質量％となるようにＰｔ及びＫを担持させた第２触媒粉とを調製した。これら触媒粉各々について水及びバインダと混合してスラリーを調製し、第１触媒粉を実施例１と同じフィルタ本体の中心側８全域に、第２触媒粉をフィルタ本体の外周側９全域に、それぞれウォッシュコートした。コート量は、サポート材量が、フィルタ中心側８では１００ｇ／Ｌ、フィルタ外周側９では５０ｇ／Ｌである。
<Case containing Pt, CeO 2 and K>
Example 4
Two types of catalyst powders in which Pt and K are supported on a mixture (support material) of CeO 2 and activated alumina by evaporation to dryness, that is, a support material having a CeO 2 mixing ratio = 6% by mass, a Pt supporting ratio = 0. The Pt support rate = 3% by mass in the first catalyst powder in which Pt and K are supported so as to be 0.5% by mass and the K support rate = 3% by mass, and the support material having the CeO 2 mixing rate = 80% by mass. A second catalyst powder on which Pt and K were supported so that the K loading rate = 30% by mass was prepared. For each of these catalyst powders, a slurry is prepared by mixing with water and a binder, the first catalyst powder is in the same region of the central side 8 of the filter body as in Example 1, and the second catalyst powder is in the entire region of the outer peripheral side 9 of the filter body. Each was washcoated. The coating amount is 100 g / L on the filter center side 8 and 50 g / L on the filter outer peripheral side 9.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；ＣｅＯ2＝６ｇ／Ｌ，アルミナ＝９４ｇ／Ｌ，Ｐｔ＝０．５ｇ／Ｌ，
Ｋ＝３ｇ／Ｌ
外周側；ＣｅＯ2＝４０ｇ／Ｌ，アルミナ＝１０ｇ／Ｌ，Ｐｔ＝１．５ｇ／Ｌ，
Ｋ＝１５ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side; CeO 2 = 6 g / L, alumina = 94 g / L, Pt = 0.5 g / L,
K = 3g / L
Outer peripheral side: CeO 2 = 40 g / L, alumina = 10 g / L, Pt = 1.5 g / L,
K = 15g / L
It is.
−比較例７−
実施例４と同じ方法によって調製したＣｅＯ2と活性アルミナとＰｔとＫとを含む触媒粉（但し、ＣｅＯ2混合率＝５０質量％のサポート材に対し、Ｐｔ担持率＝２質量％、Ｋ担持率＝２０質量％となるようにＰｔ及びＫを担持）を、バインダを含むスラリーとして、実施例１と同じフィルタ本体全体にわたって均一にウォッシュコートした。コート量はサポート材量が６２．５ｇ／Ｌとなるようにした。従って、フィルタ本体におけるＣｅＯ2担持量は３１．３ｇ／Ｌ、アルミナ担持量は３１．３ｇ／Ｌ、Ｐｔ担持量は１．２５ｇ／Ｌ、Ｋ担持量は１２．５ｇ／Ｌである。
-Comparative Example 7-
Catalyst powder containing CeO 2 , activated alumina, Pt, and K prepared by the same method as in Example 4 (provided that the support material having a CeO 2 mixing rate of 50% by mass, Pt support rate = 2% by mass, K support) Washing was carried out uniformly over the same filter main body as in Example 1 as a slurry containing a binder, carrying Pt and K so that the rate = 20% by mass. The amount of support was such that the amount of support material was 62.5 g / L. Therefore, the CeO 2 loading amount in the filter body is 31.3 g / L, the alumina loading amount is 31.3 g / L, the Pt loading amount is 1.25 g / L, and the K loading amount is 12.5 g / L.
−比較例８−
比較例７と同じ触媒粉を、バインダを含むスラリーとして、実施例１と同じフィルタ本体に、サポート材量がフィルタ中心側８に１００ｇ／Ｌ、フィルタ外周側９に５０ｇ／Ｌとなるように、それぞれ実施例４と同じ方法でウォッシュコートした。従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；ＣｅＯ2＝５０ｇ／Ｌ，アルミナ＝５０ｇ／Ｌ，Ｐｔ＝２ｇ／Ｌ，
Ｋ＝２０ｇ／Ｌ
外周側；ＣｅＯ2＝２５ｇ／Ｌ，アルミナ＝２５ｇ／Ｌ，Ｐｔ＝１ｇ／Ｌ，
Ｋ＝１０ｇ／Ｌ
である。
-Comparative Example 8-
The same catalyst powder as that of Comparative Example 7 is made into a slurry containing a binder, and the amount of support material is 100 g / L on the filter center side 8 and 50 g / L on the filter outer peripheral side 9 in the same filter body as in Example 1. Each was washcoated in the same manner as in Example 4. Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side; CeO 2 = 50 g / L, alumina = 50 g / L, Pt = 2 g / L,
K = 20g / L
Outer peripheral side: CeO 2 = 25 g / L, alumina = 25 g / L, Pt = 1 g / L,
K = 10g / L
It is.
（評価テスト）
実施例４及び比較例７，８の各ＤＰＦについて、先に説明した触媒金属の配分に関する評価と同じ方法でＡ〜Ｃの温度を測定した。結果は表７及び図１１に示されている。
(Evaluation test)
About each DPF of Example 4 and Comparative Examples 7 and 8, the temperature of AC was measured by the same method as evaluation regarding distribution of the catalyst metal demonstrated previously. The results are shown in Table 7 and FIG.
ＡとＣの温度差が比較例７では６９５℃、比較例８では６００℃であるのに対して、実施例４では３５０℃であり、このように実施例４の当該温度差が小さいのは、フィルタ外周側９のＰｔ配分量、Ｋ配分量及びＣｅＯ2配分量をフィルタ中心側８よりも多くするとともに、フィルタ中心側の触媒コート量をフィルタ外周側よりも多くしたことによる効果と認められる。 The temperature difference between A and C is 695 ° C. in Comparative Example 7 and 600 ° C. in Comparative Example 8, whereas it is 350 ° C. in Example 4. Thus, the temperature difference in Example 4 is small. , Pt distribution amount of the filter outer peripheral side 9, with the K distribution amount and CeO 2 distribution amount to more than filter center side 8, deemed effect obtained by the catalytic coating of the filter center side more than the filter outer periphery .
＜中空材の採用＞
−実施例５−
活性アルミナにＰｔを担持したＰｔ担持率０．５質量％のＰｔ／アルミナ粉末と、酸素吸蔵材としてのＣｅＺｒＯ2（Ｚｒ５０moL％の複酸化物）にＰｔを担持したＰｔ担持率０．５質量％のＰｔ／ＣｅＺｒＯ2粉末とを蒸発乾固法によって調製した。そうして、実施例１と同じフィルタ本体の中心側８には、上記両粉末をそのまま１：１の質量比で混合しさらに水及びバインダと混合してスラリーとしてウォッシュコートした。
<Adoption of hollow material>
-Example 5
Pt / alumina powder having a Pt loading ratio of 0.5 mass% with Pt supported on activated alumina and Pt loading ratio of 0.5 mass% with Pt supported on CeZrO 2 (Zr50moL% double oxide) as an oxygen storage material. Of Pt / CeZrO 2 powder was prepared by evaporation to dryness. Then, on the center side 8 of the same filter main body as in Example 1, both the powders were mixed as they were at a mass ratio of 1: 1, and further mixed with water and a binder to wash coat as a slurry.
また、活性アルミナにＰｔを担持したＰｔ担持率０．８３質量％のＰｔ／アルミナ粉末と、酸素吸蔵材としてのＣｅＺｒＯ2（Ｚｒ５０moL％の複酸化物）にＰｔを担持したＰｔ担持率０．８３質量％のＰｔ／ＣｅＺｒＯ2粉末とを蒸発乾固法によって調製した。そうして、上記フィルタ本体の外周側９には、上記両粉末各々を中空材にして１：１の質量比で混合し、さらに水及びバインダと混合してスラリーとしてウォッシュコートした。 Further, Pt / alumina powder having a Pt loading ratio of 0.83 mass%, in which Pt is supported on activated alumina, and Pt loading ratio of 0.83 in which Pt is supported on CeZrO 2 (Zr50 mol% double oxide) as an oxygen storage material. A mass% Pt / CeZrO 2 powder was prepared by evaporation to dryness. Then, on the outer peripheral side 9 of the filter main body, each of the powders was made into a hollow material and mixed at a mass ratio of 1: 1, and further mixed with water and a binder and washed as a slurry.
コート量は、サポート材量が、フィルタ中心側８では１００ｇ／Ｌ、フィルタ外周側９では３０ｇ／Ｌとなるようにした。 The coating amount was such that the support material amount was 100 g / L on the filter center side 8 and 30 g / L on the filter outer peripheral side 9.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；ＣｅＺｒＯ2＝５０ｇ／Ｌ，アルミナ＝５０ｇ／Ｌ，Ｐｔ＝０．５ｇ／Ｌ
外周側；ＣｅＺｒＯ2＝１５ｇ／Ｌ，アルミナ＝１５ｇ／Ｌ，Ｐｔ＝０．２５ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side; CeZrO 2 = 50 g / L, alumina = 50 g / L, Pt = 0.5 g / L
Outer peripheral side: CeZrO 2 = 15 g / L, alumina = 15 g / L, Pt = 0.25 g / L
It is.
上記Ｐｔ／アルミナ及びＰｔ／ＣｅＺｒＯ2各々の中空材は以下のようにして別個に調製した。 The Pt / alumina and Pt / CeZrO 2 hollow materials were separately prepared as follows.
すなわち、直径０．１〜１μｍ程度のポリビニルブチラール（ＰＶＢ）の粉末を５％ポリビニルアルコール（ＰＶＡ）水溶液に入れて攪拌することにより、ＰＶＢ溶液を作った。このＰＶＢ溶液に上記触媒成分粉末（Ｐｔ／アルミナ粉末，Ｐｔ／ＣｅＺｒＯ2粉末）を添加して混合スラリーを調製した。ＰＶＢ溶液と触媒成分粉末との比率はＰＶＢ溶液を６０質量％、触媒成分粉末を４０質量％とした。 That is, a polyvinyl butyral (PVB) powder having a diameter of about 0.1 to 1 μm was placed in a 5% polyvinyl alcohol (PVA) aqueous solution and stirred to prepare a PVB solution. The catalyst component powder (Pt / alumina powder, Pt / CeZrO 2 powder) was added to the PVB solution to prepare a mixed slurry. The ratio of the PVB solution to the catalyst component powder was 60% by mass for the PVB solution and 40% by mass for the catalyst component powder.
上記混合スラリーを、ロート状滴下器具を用いて、ＫＣｌ溶液を入れた容器内に滴下していくことにより、ＰＶＢ粒子表面に触媒成分粉末がコーティングされた球状粒子を生成させた。容器の底に堆積した球状粒子を取り出し、大気雰囲気において１５０℃の温度に２時間程度保持する乾燥処理、並びに大気雰囲気において５００℃の温度に２時間程度保持する焼成処理を施した。この焼成により、ＰＶＢは熱分解して焼失し、上記触媒成分の球状中空材が得られた。その直径は０．１〜１μｍ強となる。 The mixed slurry was dropped into a container containing a KCl solution using a funnel-shaped dropping device, thereby generating spherical particles having the PVB particle surface coated with the catalyst component powder. The spherical particles deposited on the bottom of the container were taken out, and subjected to a drying process of holding at a temperature of 150 ° C. for about 2 hours in an air atmosphere and a baking process of holding at a temperature of 500 ° C. for about 2 hours in an air atmosphere. By this firing, PVB was thermally decomposed and burned off, and the spherical hollow material of the catalyst component was obtained. The diameter becomes slightly over 0.1 to 1 μm.
図１２はＰｔ／アルミナ中空材とＰｔ／ＣｅＺｒＯ2中空材との混合物を撮影したＳＥＭ（走査型電子顕微鏡）写真である。大小の球状中空材に混じって、割れた中空材が見られるが、これは、ＳＥＭ撮影用試料調製時に割れたものである。 FIG. 12 is an SEM (scanning electron microscope) photograph of a mixture of Pt / alumina hollow material and Pt / CeZrO 2 hollow material. A cracked hollow material can be seen mixed with large and small spherical hollow materials, which is broken at the time of preparing a sample for SEM photography.
−比較例９−
実施例５と同じＰｔ担持率０．５質量％のＰｔ／アルミナ粉末とＰｔ担持率０．５質量％のＰｔ／ＣｅＺｒＯ2粉末とを１：１の質量比で混合し、さらに水及びバインダを加えてスラリーとして、実施例１と同じフィルタ本体全体にわたって均一にウォッシュコートした。上記ＣｅＺｒＯ2はＺｒ５０moL％の複酸化物である。各成分のフィルタにおける担持量は、ＣｅＺｒＯ2＝３１．３ｇ／Ｌ，アルミナ＝３１．３ｇ／Ｌ，Ｐｔ＝０．３１ｇ／Ｌである。
-Comparative Example 9-
The same Pt / alumina powder having a Pt loading rate of 0.5% by mass and Pt / CeZrO 2 powder having a Pt loading rate of 0.5% by mass as in Example 5 were mixed at a mass ratio of 1: 1, and water and binder were further added. In addition, the same filter body as in Example 1 was uniformly washcoated as a slurry. CeZrO 2 is a double oxide of Zr 50 mol%. The loadings of each component in the filter are CeZrO 2 = 31.3 g / L, alumina = 31.3 g / L, and Pt = 0.31 g / L.
−比較例１０−
実施例５と同じＰｔ担持率０．５質量％のＰｔ／アルミナ粉末とＰｔ担持率０．５質量％のＰｔ／ＣｅＺｒＯ2粉末とを１：１の質量比で混合し、さらに水及びバインダを加えてスラリーとして、実施例１と同じフィルタ本体に、サポート材量が、フィルタ中心側８に１００ｇ／Ｌ、フィルタ外周側９に５０ｇ／Ｌとなるように、それぞれ実施例５と同じ方法でウォッシュコートした。
-Comparative Example 10-
The same Pt / alumina powder having a Pt loading of 0.5% by mass and Pt / CeZrO 2 powder having a Pt loading of 0.5% by mass as in Example 5 were mixed at a mass ratio of 1: 1, and water and binder were further added. In addition, as a slurry, wash in the same manner as in Example 5 so that the amount of support material is 100 g / L on the filter center side 8 and 50 g / L on the filter outer periphery side 9 in the same filter body as Example 1. Coated.
従って、各成分のフィルタ中心側８及びフィルタ外周側９における担持量は、
中心側；ＣｅＺｒＯ2＝５０ｇ／Ｌ，アルミナ＝５０ｇ／Ｌ，
Ｐｔ＝０．５ｇ／Ｌ
外周側；ＣｅＺｒＯ2＝２５ｇ／Ｌ，アルミナ＝２５ｇ／Ｌ，
Ｐｔ＝０．２５ｇ／Ｌ
である。
Therefore, the carrying amount of each component on the filter center side 8 and the filter outer peripheral side 9 is as follows.
Center side; CeZrO 2 = 50 g / L, alumina = 50 g / L,
Pt = 0.5g / L
Outer peripheral side: CeZrO 2 = 25 g / L, alumina = 25 g / L,
Pt = 0.25g / L
It is.
（評価テスト）
実施例５及び比較例９，１０の各ＤＰＦについて、先に説明した触媒金属の配分に関する評価と同じ方法でＡ〜Ｃの温度を測定した。結果は表８及び図１３に示されている。
(Evaluation test)
About each DPF of Example 5 and Comparative Examples 9 and 10, the temperature of AC was measured by the same method as evaluation regarding allocation of the catalyst metal demonstrated previously. The results are shown in Table 8 and FIG.
ＡとＣの温度差が比較例１０では５７５℃であるのに対して、実施例５では５０５℃であり、実施例５のようにフィルタ外周側に中空のアルミナ材や酸素吸蔵材（ＣｅＺｒＯ2）を採用すると、それらが断熱材として働いてＤＰＦ外周面からの熱引きが抑制され、ＤＰＦ再生時の中心部と外周部との温度差が小さくなり、ＤＰＦ損傷防止に有利になることがわかる。特に、実施例５の場合、フィルタ外周側のＰｔ担持量は比較例１０のそれよりも少ないにも拘わらず、上記温度差が比較例１０よりも小さいことから、上記中空材による断熱効果が顕著であるということができる。 The temperature difference between A and C is 575 ° C. in Comparative Example 10, whereas it is 505 ° C. in Example 5. As in Example 5, a hollow alumina material or oxygen storage material (CeZrO 2) is formed on the filter outer peripheral side. ), It works as a heat insulating material, suppresses heat pulling from the outer peripheral surface of the DPF, reduces the temperature difference between the central portion and the outer peripheral portion during DPF regeneration, and is advantageous for preventing DPF damage. . In particular, in the case of Example 5, although the temperature difference is smaller than that of Comparative Example 10 even though the amount of Pt supported on the outer peripheral side of the filter is smaller than that of Comparative Example 10, the heat insulating effect by the hollow material is remarkable. It can be said that.
また、比較例９の上記温度差と比較例１０の上記温度差との違いはフィルタ中心側の触媒コート量をフィルタ外周側よりも多くしたことによるものであるが、当該効果は実施例５でも得られている。 Further, the difference between the temperature difference in Comparative Example 9 and the temperature difference in Comparative Example 10 is due to the fact that the amount of catalyst coating on the filter center side is larger than that on the filter outer peripheral side. Has been obtained.
１ ＤＰＦ
２ 排気ガス流入路
３ 排気ガス流出路
４ 栓
５ 隔壁
６ 細孔（排気ガス流路）
７ 触媒層
８ フィルタ中心側
９ フィルタ外周側
1 DPF
2 Exhaust gas inflow path 3 Exhaust gas outflow path 4 Plug 5 Bulkhead 6 Fine pore (exhaust gas flow path)
7 Catalyst layer 8 Filter center side 9 Filter outer periphery side
Claims (6)
上記排気ガスが通る通路の壁面にアルミナと触媒金属とを含有する触媒層が形成されていて、
上記触媒金属が、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とするディーゼルパティキュレートフィルタ。 A diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
A diesel particulate filter characterized in that a larger amount of the catalyst metal is distributed on the filter outer peripheral side than on the filter center side.
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材と触媒金属とを含有する触媒層が形成されていて、
上記酸素吸蔵材が、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とするディーゼルパティキュレートフィルタ。 A diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
A diesel particulate filter, wherein the oxygen storage material is distributed more on the filter outer periphery side than on the filter center side.
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材とアルカリ金属と触媒金属とを含有する触媒層が形成されていて、
上記アルカリ金属が、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とするディーゼルパティキュレートフィルタ。 A diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material, an alkali metal, and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
A diesel particulate filter characterized in that a larger amount of the alkali metal is distributed on the filter outer peripheral side than on the filter center side.
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材とアルカリ金属と触媒金属とを含有する触媒層が形成されていて、
上記酸素吸蔵材、アルカリ金属及び触媒金属のうちから選ばれる少なくとも２種は、フィルタ中心側よりもフィルタ外周側に多く配分されていることを特徴とするディーゼルパティキュレートフィルタ。 A diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material, an alkali metal, and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
A diesel particulate filter characterized in that at least two kinds selected from the oxygen storage material, alkali metal and catalyst metal are distributed more on the filter outer peripheral side than on the filter center side.
上記排気ガスが通る通路の壁面にアルミナと酸素吸蔵材と触媒金属とを含有する触媒層が形成されていて、
フィルタ外周側の上記触媒層に含まれているアルミナ及び酸素吸蔵材の少なくとも一方は、その少なくとも一部が中空状であり、
フィルタ中心側の上記触媒層に含まれているアルミナ及び酸素吸蔵材は中実であることを特徴とするディーゼルパティキュレートフィルタ。 A diesel particulate filter that collects particulates contained in exhaust gas of a diesel engine,
A catalyst layer containing alumina, an oxygen storage material and a catalyst metal is formed on the wall surface of the passage through which the exhaust gas passes,
At least one of alumina and the oxygen storage material contained in the catalyst layer on the filter outer peripheral side is at least partly hollow,
A diesel particulate filter, wherein the alumina and the oxygen storage material contained in the catalyst layer on the filter center side are solid.
上記排気ガスが通る通路の通気抵抗が上記フィルタ外周側よりも上記フィルタ中心側で高くなるように、上記通路壁面の単位面積当たりの上記触媒層のコーティング量は上記フィルタ中心側の方が上記フィルタ外周側よりも多いことを特徴とするディーゼルパティキュレートフィルタ。 In any one of Claims 1 thru | or 5,
The coating amount of the catalyst layer per unit area of the wall surface of the passage is higher on the filter center side so that the ventilation resistance of the passage through which the exhaust gas passes is higher on the filter center side than on the filter outer peripheral side. A diesel particulate filter characterized by having more than the outer peripheral side.
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| JP2012110859A (en) * | 2010-11-26 | 2012-06-14 | Toyota Motor Corp | Exhaust gas purifying catalyst and method of manufacturing the same |
| WO2015025890A1 (en) * | 2013-08-23 | 2015-02-26 | 住友化学株式会社 | Particulate filter |
| JP2017082745A (en) * | 2015-10-30 | 2017-05-18 | 株式会社キャタラー | Exhaust emission control device |
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