JP6627813B2 - Method for producing particulate filter with catalyst - Google Patents
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- JP6627813B2 JP6627813B2 JP2017060123A JP2017060123A JP6627813B2 JP 6627813 B2 JP6627813 B2 JP 6627813B2 JP 2017060123 A JP2017060123 A JP 2017060123A JP 2017060123 A JP2017060123 A JP 2017060123A JP 6627813 B2 JP6627813 B2 JP 6627813B2
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- 239000003054 catalyst Substances 0.000 title claims description 109
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 91
- 239000002131 composite material Substances 0.000 claims description 83
- 229910052751 metal Inorganic materials 0.000 claims description 42
- 239000002184 metal Substances 0.000 claims description 41
- 230000009467 reduction Effects 0.000 claims description 40
- 229910052763 palladium Inorganic materials 0.000 claims description 39
- 229910052697 platinum Inorganic materials 0.000 claims description 39
- 238000000034 method Methods 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 13
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 11
- 150000002910 rare earth metals Chemical class 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 8
- 229910052727 yttrium Inorganic materials 0.000 claims description 6
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 5
- 229910004625 Ce—Zr Inorganic materials 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 83
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 46
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 46
- 238000002485 combustion reaction Methods 0.000 description 31
- 238000000746 purification Methods 0.000 description 27
- 229910052799 carbon Inorganic materials 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 15
- 239000000243 solution Substances 0.000 description 13
- 230000003197 catalytic effect Effects 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000000203 mixture Substances 0.000 description 8
- 239000010948 rhodium Substances 0.000 description 8
- 238000002441 X-ray diffraction Methods 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 238000005192 partition Methods 0.000 description 7
- 239000011148 porous material Substances 0.000 description 7
- 239000002002 slurry Substances 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 239000000446 fuel Substances 0.000 description 6
- 238000011144 upstream manufacturing Methods 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 229910052703 rhodium Inorganic materials 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000001465 metallisation Methods 0.000 description 3
- 238000011946 reduction process Methods 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- 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
- 229910052769 Ytterbium Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052746 lanthanum Inorganic materials 0.000 description 2
- 230000003472 neutralizing effect Effects 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- MUJIDPITZJWBSW-UHFFFAOYSA-N palladium(2+) Chemical compound [Pd+2] MUJIDPITZJWBSW-UHFFFAOYSA-N 0.000 description 2
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- NGDQQLAVJWUYSF-UHFFFAOYSA-N 4-methyl-2-phenyl-1,3-thiazole-5-sulfonyl chloride Chemical compound S1C(S(Cl)(=O)=O)=C(C)N=C1C1=CC=CC=C1 NGDQQLAVJWUYSF-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910021193 La 2 O 3 Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical group [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- QQZMWMKOWKGPQY-UHFFFAOYSA-N cerium(3+);trinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O QQZMWMKOWKGPQY-UHFFFAOYSA-N 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 238000006731 degradation reaction Methods 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
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- VQVDTKCSDUNYBO-UHFFFAOYSA-N neodymium(3+);trinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Nd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VQVDTKCSDUNYBO-UHFFFAOYSA-N 0.000 description 1
- -1 oxygen ion Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- YWECOPREQNXXBZ-UHFFFAOYSA-N praseodymium(3+);trinitrate Chemical compound [Pr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O YWECOPREQNXXBZ-UHFFFAOYSA-N 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Landscapes
- Exhaust Gas After Treatment (AREA)
- Processes For Solid Components From Exhaust (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
本発明は、触媒付きパティキュレートフィルタの製造方法に関するものである。 The present invention relates to a method for producing a particulate filter with a catalyst.
ディーゼルエンジン等の希薄燃焼エンジンを搭載した自動車の排気ガス通路には、排気ガス中のパティキュレート（炭素質微粒子等のＰａｒｔｉｃｕｌａｔｅ ｍａｔｔｅｒ，以下、「ＰＭ」という。）を捕集するパティキュレートフィルタ（以下、「フィルタ」と称することがある。）が設けられている。フィルタのＰＭ堆積量が多くなると、エンジンの排気下流の圧力損失が大きくなり、その結果、燃費の悪化を招く。そのため、フィルタのＰＭ堆積量が所定値になった時点で、エンジンの燃料噴射制御（燃料増量や後噴射等）によって、フィルタに到達する排気ガスの温度を高め、ＰＭを燃焼させてフィルタから除去するようになされている。しかし、そのための燃料噴射制御は燃料消費量の増大を招くため、ＰＭができるだけ低い温度で燃焼するように、フィルタにＰＭ燃焼触媒が担持されている。 2. Description of the Related Art A particulate filter (hereinafter, referred to as "PM") that traps particulates (hereinafter, referred to as "PM") in exhaust gas is provided in an exhaust gas passage of an automobile equipped with a lean burn engine such as a diesel engine. , "Filter".). When the amount of PM accumulated in the filter increases, the pressure loss downstream of the exhaust gas of the engine increases, and as a result, fuel efficiency deteriorates. Therefore, when the PM accumulation amount of the filter reaches a predetermined value, the temperature of the exhaust gas reaching the filter is increased by fuel injection control of the engine (fuel increase, post-injection, etc.), and the PM is burned and removed from the filter. It has been made to be. However, since the fuel injection control for that causes an increase in fuel consumption, the filter carries a PM combustion catalyst so that PM burns at a temperature as low as possible.
一方、排気ガス中のＨＣ（炭化水素）やＣＯ（一酸化炭素）など未燃ガス成分は、フィルタよりも上流側の触媒で浄化することが望ましいが、その浄化率をより高めるにはフィルタでもそのような未燃ガス成分を効率良く浄化できるようにすることが求められる。特にフィルタ再生時にはエンジンの燃料が増量され、上流側の触媒の浄化能力では対応できない場合があることから、フィルタの排気ガス浄化性能を高めることが望まれる。 On the other hand, unburned gas components such as HC (hydrocarbon) and CO (carbon monoxide) in the exhaust gas are desirably purified by a catalyst located upstream of the filter. It is required to be able to efficiently purify such unburned gas components. Particularly, when the filter is regenerated, the amount of fuel of the engine is increased, and the purification performance of the upstream catalyst may not be sufficient, so it is desired to enhance the exhaust gas purification performance of the filter.
そうして、フィルタの排気ガス通路壁に、ＰＭ燃焼触媒に加え、ＨＣやＣＯを浄化するための排気ガス浄化触媒を設けることが行われている（例えば、特許文献１参照）。 Thus, an exhaust gas purifying catalyst for purifying HC and CO in addition to the PM combustion catalyst is provided on the exhaust gas passage wall of the filter (for example, see Patent Document 1).
特許文献１によれば、ディーゼルエンジンの排気通路に配設されるディーゼルパティキュレートフィルタ（ＤＰＦ）に設けられる触媒として、Ｃｅを主成分とし且つ他の希土類金属又はアルカリ土類金属を含む複酸化物がパティキュレート燃焼速度の増大に有効であり、これにアルミナ及びＰｔを組み合わせると、同時にＤＰＦの排ガス浄化能力が高まることが記載されている。 According to Patent Document 1, as a catalyst provided in a diesel particulate filter (DPF) disposed in an exhaust passage of a diesel engine, a double oxide containing Ce as a main component and containing another rare earth metal or an alkaline earth metal is used. Is effective in increasing the particulate combustion rate, and it is described that when this is combined with alumina and Pt, the exhaust gas purification capacity of the DPF is simultaneously increased.
ところで、上記アルミナに担持させる触媒金属としては、Ｐｔの他にＰｄ等を用いることができるが、ＰｔやＰｄ等の触媒金属を担持させたアルミナでは、触媒金属の多くは酸化状態で担持されているため、触媒金属をメタル状態に還元することで、触媒金属担持アルミナの排気ガス浄化性能を高めることができる。 By the way, as the catalyst metal supported on the alumina, Pd or the like can be used in addition to Pt, but in the case of the alumina supported with a catalyst metal such as Pt or Pd, most of the catalyst metal is supported in an oxidized state. Therefore, by reducing the catalyst metal to the metal state, the exhaust gas purification performance of the catalyst metal-carrying alumina can be enhanced.
しかしながら、これらの触媒金属を還元するためには、大気中では約８５０℃以上の熱処理が必要であり、触媒金属のシンタリングなどの触媒成分の熱劣化、及びそれに伴う、ＰＭ燃焼性能等の触媒活性の低下が問題となる。 However, in order to reduce these catalyst metals, a heat treatment of about 850 ° C. or more is required in the atmosphere, and thermal degradation of the catalyst components such as sintering of the catalyst metals, and accompanying catalyst catalysts such as PM combustion performance. The decrease in activity becomes a problem.
そこで本発明では、優れたＰＭ燃焼性能を維持するとともに、排気ガス浄化性能を向上させた触媒付きパティキュレートフィルタを提供することを目的とする。 Accordingly, an object of the present invention is to provide a particulate filter with a catalyst that maintains excellent PM combustion performance and has improved exhaust gas purification performance.
上記の目的を達成するために、本発明では、触媒金属が担持されたアルミナにＣＯ還元処理を施した後に、ＰＭ燃焼性能に優れたＺｒ系複合酸化物と混合して、フィルタ本体上に担持するようにした。 In order to achieve the above object, in the present invention, after subjecting alumina carrying a catalytic metal to a CO reduction treatment, the alumina is mixed with a Zr-based composite oxide having excellent PM combustion performance and supported on a filter body. I did it.
すなわち、ここに開示する第１の技術に係る触媒付きパティキュレートフィルタの製造方法は、エンジンの排気通路に配設され、排気ガス中のパティキュレートを捕集するためのフィルタ本体と、該フィルタ本体の排気ガス通路壁に形成された触媒層とを備えた触媒付きパティキュレートフィルタの製造方法であって、アルミナに触媒金属を担持させる工程と、Ｚｒを主成分とするＺｒ系複合酸化物を準備する工程と、前記触媒金属を担持させたアルミナに対し、ＣＯ雰囲気下で還元処理を施す工程と、前記Ｚｒ系複合酸化物と、前記還元処理されたアルミナとを混合し、前記フィルタ本体の前記排気ガス通路壁上に担持して前記触媒層を形成する工程とを備え、前記Ｚｒ系複合酸化物と前記還元処理されたアルミナとの総量に対する前記還元処理されたアルミナの比率は、５．０質量％以上５７．０質量％未満であることを特徴とする。 That is, a method of manufacturing a particulate filter with a catalyst according to a first technology disclosed herein includes a filter body disposed in an exhaust passage of an engine for collecting particulates in exhaust gas, and a filter body. A method for producing a particulate filter with a catalyst, comprising: a catalyst layer formed on the exhaust gas passage wall according to claim 1; and a step of supporting a catalyst metal on alumina; and preparing a Zr-based composite oxide containing Zr as a main component. And a step of subjecting the catalyst metal-supported alumina to a reduction treatment in a CO atmosphere; mixing the Zr-based composite oxide and the reduced treatment alumina; and carried on the exhaust gas passage on the wall and forming the catalyst layer, wherein the total amount of the Zr-based composite oxide and the reduction treatment alumina instead The ratio of the treated alumina, and less than 5.0 mass% or more 57.0% by weight.
本発明者らは、触媒金属として例えばＰｔ及び／又はＰｄを担持したアルミナをＣＯ雰囲気下で還元処理することにより、大気中における還元処理を行うよりも低温でＰｔ及び／又はＰｄのメタル化を促進させ得ることを見出した。 The present inventors carried out a reduction treatment of alumina carrying Pt and / or Pd as a catalyst metal in a CO atmosphere, thereby reducing the metallization of Pt and / or Pd at a lower temperature than performing the reduction treatment in the atmosphere. It has been found that it can be promoted.
一方、アルミナとＺｒ系複合酸化物とを混合させた後に、ＣＯ還元処理を行うと、Ｚｒ系複合酸化物の結晶構造の変化が誘発され、Ｚｒ系複合酸化物のＰＭ燃焼性能が低下し得ることも見出した。 On the other hand, if the CO reduction treatment is performed after the alumina and the Zr-based composite oxide are mixed, a change in the crystal structure of the Zr-based composite oxide is induced, and the PM combustion performance of the Zr-based composite oxide may decrease. I also found out.
本発明によれば、触媒金属が担持されたアルミナのみにＣＯ還元処理を施すため、Ｚｒ系複合酸化物の優れたＰＭ燃焼性能を維持しつつ、アルミナの排気ガス浄化性能を高め、延いては触媒金属担持量を抑えつつ、ＰＭ燃焼性能及び排気ガス浄化性能の高い触媒付きパティキュレートフィルタを得ることができる。 According to the present invention, since the CO reduction treatment is performed only on the alumina supporting the catalyst metal, the exhaust gas purification performance of the alumina is enhanced while maintaining the excellent PM combustion performance of the Zr-based composite oxide, and A particulate filter with a catalyst having high PM combustion performance and high exhaust gas purification performance while suppressing the amount of catalyst metal carried can be obtained.
また、前記Ｚｒ系複合酸化物と前記還元処理されたアルミナとの総量に対する前記還元処理されたアルミナの比率は、５．０質量％以上５７．０質量％未満である。 Further, the Zr-based ratio of the reduction-treated alumina to the total amount of the composite oxide and the reduction-treated alumina, Ru der less than 5.0 mass% or more 57.0% by weight.
本構成によれば、ＰＭ燃焼性能及び排気ガス浄化性能の双方に優れた触媒付きパティキュレートフィルタを得ることができる。 According to this configuration, it is possible to obtain a particulate filter with a catalyst that is excellent in both PM combustion performance and exhaust gas purification performance.
第２の技術は、第１の技術において、前記Ｚｒ系複合酸化物は、Ｃｅを含有するＣｅＺｒ系複合酸化物、及び、Ｃｅを含まず且つＣｅ以外の希土類金属を含有するＣｅ非含有Ｚｒ系複合酸化物の少なくとも一方であることを特徴とする。本構成によれば、触媒付きパティキュレートフィルタのＰＭ燃焼性能を向上させることができる。 A second technique is the first technique, wherein the Zr-based composite oxide is a Ce-Zr-based composite oxide containing Ce, and a Ce-free Zr-based oxide containing no Ce and containing a rare earth metal other than Ce. It is characterized by being at least one of a composite oxide. According to this configuration, the PM combustion performance of the particulate filter with a catalyst can be improved.
第３の技術は、第１又は第２の技術において、前記Ｚｒ系複合酸化物は、Ｃｅを含まず且つＣｅ以外の希土類金属を含有するＣｅ非含有Ｚｒ系複合酸化物を含み、前記Ｃｅ非含有Ｚｒ系複合酸化物は、前記Ｃｅ以外の希土類金属としてＹとＰｒとを含むＺｒＹＰｒ複合酸化物であることを特徴とする。A third technique is the first or second technique, wherein the Zr-based composite oxide includes a Ce-free Zr-based composite oxide that does not contain Ce and contains a rare earth metal other than Ce. The contained Zr-based composite oxide is a ZrYPr composite oxide containing Y and Pr as rare earth metals other than Ce.
第４の技術は、第１〜第３の技術のいずれか１つにおいて、前記還元処理を施す工程は、ＣＯを含む還元雰囲気下において、５００℃以上８００℃以下で熱処理する工程であることを特徴とする。 A fourth technique is that, in any one of the first to third techniques, the step of performing the reduction treatment is a step of performing a heat treatment at 500 ° C. or more and 800 ° C. or less in a reducing atmosphere containing CO. Features.
本構成によれば、アルミナに担持された触媒金属のシンタリング等を抑制して、アルミナの排気ガス浄化性能を向上させることができる。 According to this configuration, it is possible to suppress the sintering of the catalyst metal supported on alumina and improve the exhaust gas purification performance of alumina.
第５の技術は、第１〜第４の技術のいずれか１つにおいて、前記触媒金属は、Ｐｔ及びＰｄの少なくとも一方である。 According to a fifth technique, in any one of the first to fourth techniques, the catalyst metal is at least one of Pt and Pd.
本構成によれば、触媒金属としてＰｔやＰｄをアルミナに担持することで、触媒付パティキュレートフィルタの排気ガス浄化性能を高めることができる。 According to this configuration, by supporting Pt or Pd as a catalyst metal on alumina, it is possible to enhance the exhaust gas purification performance of the particulate filter with a catalyst.
第６の技術は、第１〜第５の技術のいずれか１つにおいて、前記エンジンは、希薄燃焼エンジンである。 A sixth technology is the engine according to any one of the first to fifth technologies, wherein the engine is a lean burn engine.
第１〜第５の技術に係る製造方法により製造された触媒付きパティキュレートフィルタを希薄燃焼エンジンの排気通路に配設することで、当該希薄燃焼エンジンから排出される排気ガス中のＰＭを効果的に燃焼除去することができるとともに、排気ガス中のＨＣやＣＯも効率よく浄化することができる。 By arranging the particulate filter with catalyst manufactured by the manufacturing method according to the first to fifth techniques in the exhaust passage of the lean burn engine, PM in the exhaust gas discharged from the lean burn engine can be effectively reduced. And the HC and CO in the exhaust gas can be efficiently purified.
以上述べたように、本発明によると、触媒金属が担持されたアルミナのみにＣＯ還元処理を施すため、Ｚｒ系複合酸化物の優れたパティキュレート燃焼性能を維持しつつ、アルミナの排気ガス浄化性能を高め、延いてはＰＭ燃焼性能及び排気ガス浄化性能の高い触媒付きパティキュレートフィルタを得ることができる。 As described above, according to the present invention, since the CO reduction treatment is performed only on the alumina supporting the catalytic metal, the exhaust gas purification performance of the alumina is maintained while maintaining the excellent particulate combustion performance of the Zr-based composite oxide. And a particulate filter with a catalyst having high PM combustion performance and high exhaust gas purification performance can be obtained.
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。以下の好ましい実施形態の説明は、本質的に例示に過ぎず、本発明、その適用物或いはその用途を制限することを意図するものでは全くない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its applications, or its uses.
（実施形態１）
＜パティキュレートフィルタの構造＞
図１に示すように、触媒付きパティキュレートフィルタ１０（以下、単に「触媒付きフィルタ１０」という。）は、ディーゼルエンジンやガソリンエンジン等のエンジン、特に希薄燃焼エンジンの排気通路１１に配設され、排気ガス中のＰＭを捕集する。触媒付きフィルタ１０よりも排気ガス流の上流側の排気通路１１には、酸化物等からなるサポート材にＰｔ、Ｐｄ等に代表される触媒金属を担持した酸化触媒（図示省略）を配置することができる。このような酸化触媒を触媒付きフィルタ１０の上流側に配置するときは、該酸化触媒によって排気ガス中のＨＣ、ＣＯを酸化させ、その酸化燃焼熱で触媒付きフィルタ１０に流入する排気ガス温度を高めて触媒付きフィルタ１０を加熱することができ、ＰＭの燃焼除去に有利になる。また、排気ガス中のＮＯが酸化触媒でＮＯ２に酸化され、該ＮＯ２が触媒付きフィルタ１０にＰＭを燃焼させる酸化剤として供給されることになる。
(Embodiment 1)
<Structure of particulate filter>
As shown in FIG. 1, a particulate filter 10 with a catalyst (hereinafter, simply referred to as “filter 10 with a catalyst”) is disposed in an exhaust passage 11 of an engine such as a diesel engine or a gasoline engine, particularly, a lean burn engine. Collect PM in exhaust gas. An oxidation catalyst (not shown) in which a support material made of an oxide or the like carries a catalyst metal represented by Pt, Pd, or the like is arranged in the exhaust passage 11 on the upstream side of the exhaust gas flow from the filter 10 with a catalyst. Can be. When such an oxidation catalyst is arranged on the upstream side of the catalyst-equipped filter 10, HC and CO in the exhaust gas are oxidized by the oxidation catalyst, and the temperature of the exhaust gas flowing into the catalyst-equipped filter 10 is reduced by the heat of the oxidation combustion. The filter 10 can be heated to a higher temperature, which is advantageous for removing PM by combustion. In addition, NO in the exhaust gas is oxidized to NO 2 by the oxidation catalyst, and the NO 2 is supplied to the catalyst-equipped filter 10 as an oxidizing agent for burning PM.
図２及び図３に模式的に示すように、触媒付きフィルタ１０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排気ガス通路１２、１３を備えている。すなわち、触媒付きフィルタ１０は、下流端が栓１４により閉塞された排気ガス流入路１２と、上流端が栓１４により閉塞された排気ガス流出路１３とが交互に設けられ、排気ガス流入路１２と排気ガス流出路１３とは薄肉の隔壁１５（排気ガス通路壁）を介して隔てられている。図２においてハッチングを付した部分は排気ガス流出路１３の上流端の栓１４を示している。 As schematically shown in FIGS. 2 and 3, the catalyst-equipped filter 10 has a honeycomb structure and includes a number of exhaust gas passages 12 and 13 extending in parallel with each other. That is, in the filter with catalyst 10, the exhaust gas inflow path 12 whose downstream end is closed by the plug 14 and the exhaust gas outflow path 13 whose upstream end is closed by the plug 14 are provided alternately. The exhaust gas outflow passage 13 is separated from the exhaust gas outflow passage 13 by a thin partition wall 15 (exhaust gas passage wall). In FIG. 2, a hatched portion indicates a plug 14 at the upstream end of the exhaust gas outflow passage 13.
触媒付きフィルタ１０において、隔壁１５を含むフィルタ本体は、コージェライト、ＳｉＣ、Ｓｉ３Ｎ４、サイアロン、ＡｌＴｉＯ３のような無機多孔質材料から形成されている。排気ガス流入路１２内に流入した排気ガスは図３において矢印で示したように周囲の隔壁１５を通って隣接する排気ガス流出路１３内に流出する。すなわち、図４に示すように、隔壁１５は排気ガス流入路１２と排気ガス流出路１３とを連通する微小な細孔１６（排気ガス通路）を有し、この細孔１６を排気ガスが通る。ＰＭは主に排気ガス流入路１２及び細孔１６の壁部に捕捉され堆積する。 In the catalyst-carried filter 10, the filter body comprising a partition wall 15, cordierite, SiC, Si 3 N 4, sialon, and is formed of an inorganic porous material such as ALTIO 3. The exhaust gas that has flowed into the exhaust gas inflow channel 12 flows out into the adjacent exhaust gas outflow channel 13 through the surrounding partition 15 as indicated by the arrow in FIG. That is, as shown in FIG. 4, the partition wall 15 has minute pores 16 (exhaust gas passages) communicating the exhaust gas inflow path 12 and the exhaust gas outflow path 13, and the exhaust gas passes through the pores 16. . PM is mainly captured and deposited on the exhaust gas inflow path 12 and the walls of the fine holes 16.
上記フィルタ本体の排気ガス通路（排気ガス流入路１２、排気ガス流出路１３及び細孔１６）を形成する隔壁１５の壁面には触媒層２０が担持されている。なお、排気ガス流出路１３側の壁面に触媒を担持することは必ずしも要しない。 A catalyst layer 20 is carried on the wall surface of the partition wall 15 that forms the exhaust gas passage (the exhaust gas inflow path 12, the exhaust gas outflow path 13, and the pores 16) of the filter body. It is not always necessary to support the catalyst on the wall surface on the exhaust gas outflow passage 13 side.
＜触媒層について＞
次に触媒層２０の構成について説明する。
<About the catalyst layer>
Next, the configuration of the catalyst layer 20 will be described.
図５に模式的に示すように、本実施形態の触媒層２０は、複数種の活性アルミナであるＬａ含有アルミナ２１（アルミナ）及び純アルミナ２２（アルミナ）（以下、Ｌａ含有アルミナ２１及び純アルミナ２２をまとめて「活性アルミナ２１，２２」と称することがある。）と、活性酸素を放出するＣｅ非含有Ｚｒ系複合酸化物としてのＺｒＹＰｒ複合酸化物２３（Ｚｒ系複合酸化物）とＣｅＺｒ系複合酸化物としてのＲｈドープＣｅＺｒＮｄ複合酸化物２４（Ｚｒ系複合酸化物）を含む。これら活性アルミナ２１，２２には触媒金属としてＰｔ２５及びＰｄ２６が担持されている。Ｌａ含有アルミナ２１はＬａ２Ｏ３を４質量％含有する活性アルミナである。純アルミナ２２はＬａ等の添加物を含まない純γ−アルミナである。ＺｒＹＰｒ複合酸化物２３は、Ｃｅを含んでおらず、主成分としてのＺｒＯ２に、金属元素としてＣｅ以外の希土類金属のうちＹとＰｒのみが含まれてなる複合酸化物である。ＲｈドープＣｅＺｒＮｄ複合酸化物２４は、主成分としてのＺｒＯ２に、金属元素としてＣｅを含み且つＣｅ以外の希土類金属のうちＮｄのみが含まれてなる複合酸化物に、触媒金属としてのＲｈを担持及び／又は固溶させたものである。 As schematically shown in FIG. 5, the catalyst layer 20 of the present embodiment is composed of a plurality of types of activated alumina, La-containing alumina 21 (alumina) and pure alumina 22 (alumina) (hereinafter, La-containing alumina 21 and pure alumina 21). 22 may be collectively referred to as “activated alumina 21 and 22”), ZrYPr composite oxide 23 (Zr-based composite oxide) as a Ce-free Zr-based composite oxide releasing active oxygen, and CeZr-based It includes Rh-doped CeZrNd composite oxide 24 (Zr-based composite oxide) as a composite oxide. These activated aluminas 21 and 22 carry Pt25 and Pd26 as catalyst metals. La-containing alumina 21 is activated alumina containing 4% by mass of La 2 O 3 . Pure alumina 22 is pure γ-alumina containing no additives such as La. The ZrYPr composite oxide 23 is a composite oxide that does not contain Ce and contains only Y and Pr among rare earth metals other than Ce as metal elements in ZrO 2 as a main component. The Rh-doped CeZrNd composite oxide 24 supports Rh as a catalyst metal on a composite oxide in which ZrO 2 as a main component contains Ce as a metal element and only Nd among rare earth metals other than Ce is contained. And / or a solid solution.
触媒層２０は、Ｐｔ２５及びＰｄ２６を担持した活性アルミナ２１，２２を含むため、排気ガス中のＮＯをＰＭの酸化剤となるＮＯ２に高効率で転換することができる。これにより、ＰＭの燃焼性が良好になる。ＺｒＹＰｒ複合酸化物２３は、優れた酸素交換反応性を有するとともに、酸素イオン伝導性が高く、そのため、ＰＭ燃焼に有効に働く活性酸素を多量に放出することができる。ＲｈドープＣｅＺｒＮｄ複合酸化物２４は、高い酸素吸蔵放出能を有し、ＰＭ燃焼に有効に働く活性が高い酸素を放出する。 The catalyst layer 20, to contain the activated alumina 21 and 22 carrying Pt25 and PD 26, can be converted with high efficiency of NO in the exhaust gas to NO 2 as the oxidizing agent of PM. Thereby, the flammability of PM is improved. The ZrYPr composite oxide 23 has excellent oxygen exchange reactivity and high oxygen ion conductivity, and therefore can release a large amount of active oxygen that effectively works for PM combustion. The Rh-doped CeZrNd composite oxide 24 has a high oxygen storage / release capability and releases highly active oxygen that works effectively for PM combustion.
活性アルミナ２１，２２に担持させる触媒金属としては、例えばＰｔ、Ｐｄ、Ｒｈ等が挙げられるが、排気ガス中のＣＯ浄化性能向上の観点から、Ｐｔ及びＰｄの少なくとも一方を担持することが好ましい。 Examples of the catalyst metal supported on the activated alumina 21 and 22 include Pt, Pd, and Rh. From the viewpoint of improving CO purification performance in exhaust gas, it is preferable to support at least one of Pt and Pd.
活性アルミナとして、Ｌａ含有アルミナ２１とこれよりも嵩が低い純アルミナ２２を併用しているため、触媒層２０を隔壁１５に担持したとき層厚になることを抑えることができ、フィルタの目詰まりの発生防止に有利になる。なお、活性アルミナは、Ｌａ含有アルミナ２１及び純アルミナ２２のいずれか一方のみを用いてもよい。また他の活性アルミナを使用してもよい。 As the activated alumina, the La-containing alumina 21 and the pure alumina 22 having a lower bulk are used together, it is possible to suppress the catalyst layer 20 from becoming thicker when the catalyst layer 20 is supported on the partition wall 15 and to prevent the filter from being clogged. This is advantageous in preventing the occurrence of the occurrence. As the activated alumina, only one of La-containing alumina 21 and pure alumina 22 may be used. Further, other activated alumina may be used.
ＺｒＹＰｒ複合酸化物２３及びＲｈドープＣｅＺｒＮｄ複合酸化物２４は、平均細孔径が２０ｎｍ以上６０ｎｍ以下のものを用いることが好ましい。パティキュレートフィルタにおいては、触媒重量当たりの排気ガス空間速度が非常に大きくなるが、細孔径が比較的大きいＺｒＹＰｒ複合酸化物２３及びＲｈドープＣｅＺｒＮｄ複合酸化物２４を用いると、排気ガスが細孔内部に入るため、排気ガスとＺｒＹＰｒ複合酸化物２３の接触性が向上し、それぞれ活性酸素を効率良く放出することができる。その結果、ＰＭの燃焼促進に有利になる。 It is preferable that the ZrYPr composite oxide 23 and the Rh-doped CeZrNd composite oxide 24 have an average pore diameter of 20 nm or more and 60 nm or less. In the particulate filter, the space velocity of the exhaust gas per catalyst weight becomes very high. However, when the ZrYPr composite oxide 23 and the Rh-doped CeZrNd composite oxide 24 having a relatively large pore diameter are used, the exhaust gas is Therefore, the contact between the exhaust gas and the ZrYPr composite oxide 23 is improved, and active oxygen can be efficiently released. As a result, it is advantageous for promoting PM combustion.
なお、Ｚｒ系複合酸化物としては、ＺｒＹＰｒ複合酸化物２３及びＲｈドープＣｅＺｒＮｄ複合酸化物２４のいずれか一方を用いる構成としてもよい。また、両者の混合比率は、特に限定されるものではなく、所望の触媒構成を得る観点から適宜調整され得る。 As the Zr-based composite oxide, any one of the ZrYPr composite oxide 23 and the Rh-doped CeZrNd composite oxide 24 may be used. The mixing ratio of the two is not particularly limited, and can be appropriately adjusted from the viewpoint of obtaining a desired catalyst configuration.
また、Ｃｅ非含有Ｚｒ系複合酸化物としては、Ｙ及びＰｒを含むＺｒＹＰｒ複合酸化物２３に限らず、Ｙ及びＰｒに加え、又はこれらに代えて、他のＣｅ以外の希土類金属Ｎｄ、Ｓｃ、Ｙｂ、Ｌａ等を含む複合酸化物であってもよい。また、ＺｒＹＰｒ複合酸化物２３には、ＰＭ燃焼性能向上の観点から、Ｐｔ、Ｐｄ、Ｒｈ等の触媒金属を担持又は固溶させてもよい。 In addition, the Ce-free Zr-based composite oxide is not limited to the ZrYPr composite oxide 23 containing Y and Pr, and may be other rare earth metals other than Ce, such as Nd, Sc, in addition to or instead of Y and Pr. It may be a composite oxide containing Yb, La, or the like. Further, a catalytic metal such as Pt, Pd, Rh or the like may be supported on the ZrYPr composite oxide 23 or solid-solved from the viewpoint of improving PM combustion performance.
ＣｅＺｒ系複合酸化物としては、Ｎｄを含むＣｅＺｒＮｄ複合酸化物に限らず、Ｎｄに加え、又はこれに代えて、他のＣｅ以外の希土類金属Ｙ、Ｐｒ、Ｓｃ、Ｙｂ、Ｌａ等を含有してもよい。また、ＲｈドープＣｅＺｒＮｄ複合酸化物２４には、ＰＭ燃焼性能向上の観点から、Ｒｈドープに限らず、Ｒｈを担持させてもよいし、Ｒｈに加え、又はＲｈに代えて、Ｐｔ、Ｐｄ等の触媒金属を担持又は固溶させてもよい。 The CeZr-based composite oxide is not limited to the Nd-containing CeZrNd composite oxide, and may include, in addition to or instead of Nd, other rare-earth metals other than Ce, such as Y, Pr, Sc, Yb, and La. Is also good. The Rh-doped CeZrNd composite oxide 24 is not limited to Rh-doped, and may carry Rh from the viewpoint of improving PM combustion performance. In addition to Rh, or instead of Rh, Pt, Pd, or the like may be used. The catalyst metal may be supported or solid-solved.
＜触媒の調製＞
ＺｒＹＰｒ複合酸化物２３は例えば次の方法で調製することができる。オキシ硝酸ジルコニル溶液と硝酸イットリウムと硝酸プラセオジウムとをイオン交換水に溶かす。この硝酸塩溶液に２８質量％アンモニア水の８倍希釈液を混合して中和することにより、ＺｒＹＰｒ複合酸化物の前駆体（共沈体）を得る。この共沈物を遠心分離し、上澄み液を除去する脱水操作と、イオン交換水を加えて撹拌する水洗操作とを交互に必要回数繰り返す。最終的に脱水を行った後の共沈物を、大気中において１５０℃で一昼夜乾燥させた後、ボールミルにより粉砕する。その後、大気中において５００℃で２時間焼成することによりＺｒＹＰｒ複合酸化物２３を得ることができる。
<Preparation of catalyst>
The ZrYPr composite oxide 23 can be prepared, for example, by the following method. A zirconyl oxynitrate solution, yttrium nitrate, and praseodymium nitrate are dissolved in ion-exchanged water. A precursor (coprecipitate) of the ZrYPr composite oxide is obtained by mixing and neutralizing the nitrate solution with an 8-fold dilution of 28% by mass aqueous ammonia. The coprecipitate is centrifuged, and a dehydration operation of removing the supernatant and a water washing operation of adding ion-exchanged water and stirring are alternately repeated the required number of times. The coprecipitate after the final dehydration is dried in the air at 150 ° C. for 24 hours, and then pulverized by a ball mill. Thereafter, by firing in the air at 500 ° C. for 2 hours, the ZrYPr composite oxide 23 can be obtained.
ＲｈドープＣｅＺｒＮｄ複合酸化物２４は例えば次の方法で調製することができる。硝酸セリウム６水和物とオキシ硝酸ジルコニル溶液と硝酸ネオジム６水和物と硝酸ロジウム溶液とをイオン交換水に溶かす。この硝酸塩溶液に２８質量％アンモニア水の８倍希釈液を混合して中和することにより、共沈物を得る。この共沈物を含む溶液を遠心分離器にかけて上澄み液を除去する脱水操作と、イオン交換水を加えて撹拌する水洗操作とを交互に必要回数繰り返す。最終的に脱水を行った後の共沈物を、大気中において１５０℃で一昼夜乾燥させた後、ボールミルにより粉砕する。その後、大気中において５００℃で２時間焼成することによりＲｈドープＣｅＺｒＮｄ複合酸化物２４を得ることができる。なお、触媒金属としてのＲｈのドープ量は、限定する意味ではないが、優れたＰＭ燃焼性能を得つつ、貴金属量を抑える観点から、ＣｅＺｒＮｄ複合酸化物に対して、質量比で０．１〜１．０％程度とすることができる。 The Rh-doped CeZrNd composite oxide 24 can be prepared, for example, by the following method. Cerium nitrate hexahydrate, zirconyl oxynitrate solution, neodymium nitrate hexahydrate and rhodium nitrate solution are dissolved in ion-exchanged water. A coprecipitate is obtained by mixing and neutralizing the nitrate solution with an 8-fold dilution of 28% by mass aqueous ammonia. The solution containing the coprecipitate is centrifuged to remove the supernatant liquid, and the washing operation of adding ion-exchanged water and stirring is alternately repeated the required number of times. The coprecipitate after the final dehydration is dried in the air at 150 ° C. for 24 hours, and then pulverized by a ball mill. Then, by baking in air at 500 ° C. for 2 hours, the Rh-doped CeZrNd composite oxide 24 can be obtained. In addition, the doping amount of Rh as a catalyst metal is not limited, but from the viewpoint of suppressing the amount of noble metal while obtaining excellent PM combustion performance, from the viewpoint of suppressing the amount of noble metal, the mass ratio of 0.1 to It can be about 1.0%.
Ｌａ含有アルミナ２１及び純アルミナ２２はそれぞれ市販されている粉末を用いることができる。 Commercially available powders can be used for the La-containing alumina 21 and the pure alumina 22, respectively.
次に活性アルミナ２１，２２にＰｔ２５及びＰｄ２６を担持する方法を説明する。活性アルミナ２１，２２にイオン交換水を加えてスラリーを調製し、それをスターラー等により十分に撹拌する。続いて、撹拌しながらそのスラリーにジニトロジアミン白金（ＩＩ）硝酸溶液及び硝酸パラジウム（ＩＩ）溶液を、Ｐｔ及びＰｄの質量比で、Ｐｔ／Ｐｄ＝２／１となるように所定量滴下し、十分に撹拌する。その後、加熱しながらさらに撹拌を続けて、水分を完全に蒸発させる。しかる後、大気中において５００℃で２時間焼成する。そして、後述する還元処理を行うことにより、Ｐｔ２５及びＰｄ２６が担持され且つ還元処理された活性アルミナ２１，２２を得ることができる。 Next, a method of supporting Pt25 and Pd26 on the activated aluminas 21 and 22 will be described. Ion exchange water is added to the activated aluminas 21 and 22 to prepare a slurry, which is sufficiently stirred with a stirrer or the like. Subsequently, a predetermined amount of a dinitrodiamineplatinum (II) nitric acid solution and a palladium (II) nitrate solution were added dropwise to the slurry with stirring so that Pt / Pd = 2/1 at a mass ratio of Pt and Pd, Stir well. Thereafter, stirring is further continued while heating to completely evaporate water. Thereafter, baking is performed at 500 ° C. for 2 hours in the air. Then, by performing a reduction process described later, activated aluminas 21 and 22 carrying Pt25 and Pd26 and subjected to the reduction process can be obtained.
Ｐｔ源としては、ヘキサヒドロキソ白金（ＩＶ）酸硝酸溶液や、ヘキサヒドロキソ白金（ＩＶ）酸エタノールアミン溶液、など他のＰｔ源を採用してもよい。Ｐｄ源としては、ヘキサヒドロキソパラジウム（ＩＶ）酸エタノールアミン溶液、ジニトロジアンミンパラジウム（ＩＩ）硝酸溶液、テトラアンミンパラジウム（ＩＩ）硝酸溶液など他のＰｄ源を採用してもよい。なお、Ｐｔ及びＰｄの混合比率は、特に限定されるものではなく、所望の触媒構成とする観点から、適宜調整され得る。また、Ｐｔ及びＰｄは、いずれか一方のみ担持された構成としてもよい。さらに、限定する意味ではないが、活性アルミナ２１，２２に対する触媒金属の担持量は、フィルタ１Ｌ当たり０．１ｇ〜１．０ｇ程度となるようにすることができる。 As the Pt source, another Pt source such as a hexahydroxoplatinic acid (IV) nitric acid solution or an ethanolamine hexahydroxoplatinum (IV) acid solution may be used. As the Pd source, other Pd sources such as an ethanolamine solution of hexahydroxo palladium (IV), a dinitrodiammine palladium (II) nitric acid solution, and a tetraammine palladium (II) nitric acid solution may be employed. The mixing ratio of Pt and Pd is not particularly limited, and can be appropriately adjusted from the viewpoint of obtaining a desired catalyst configuration. Further, Pt and Pd may be configured to carry only one of them. Further, although not limited, the amount of the catalytic metal carried on the activated alumina 21 and 22 can be about 0.1 g to 1.0 g per liter of the filter.
なお、ＺｒＹＰｒ複合酸化物２３、ＲｈドープＣｅＺｒＮｄ複合酸化物２４にＰｔ、Ｐｄ、Ｒｈ等の触媒金属を担持及び／又は固溶させる場合は、上記活性アルミナ２１，２２や上記ＲｈドープＣｅＺｒＮｄ複合酸化物２４の場合と同様の調製方法を用いて行うことができる。 When the ZrYPr composite oxide 23 and the Rh-doped CeZrNd composite oxide 24 carry and / or form a solid solution with a catalytic metal such as Pt, Pd, and Rh, the activated aluminas 21 and 22 and the Rh-doped CeZrNd composite oxide are used. The preparation can be carried out using the same preparation method as in the case of No. 24.
上記のようにして得られた、Ｐｔ及びＰｄが担持された活性アルミナ２１，２２の還元処理済みのもの、ＺｒＹＰｒ複合酸化物２３及びＲｈドープＣｅＺｒＮｄ複合酸化物２４を容器に入れ、イオン交換水及びバインダを加え、混合してスラリーを調製する。そして、このスラリーをフィルタ本体にコーティングし、乾燥させた後、５００℃で２時間焼成することにより、触媒付きフィルタ１０を得ることができる。 The activated aluminas 21 and 22 carrying Pt and Pd obtained as described above, which had been reduced, the ZrYPr composite oxide 23 and the Rh-doped CeZrNd composite oxide 24 were put in a container, and ion-exchanged water and A binder is added and mixed to prepare a slurry. Then, the slurry is coated on the filter body, dried, and then baked at 500 ° C. for 2 hours to obtain the filter with catalyst 10.
＜還元処理＞
ここに、本実施形態に係る触媒付きパティキュレートフィルタ１０の製造方法は、活性アルミナ２１，２２にＰｔ２５及びＰｄ２６を担持させた後、上述のごとく、ＣＯ雰囲気下における還元処理を行うことを特徴とする。
<Reduction process>
Here, the method for manufacturing the particulate filter with catalyst 10 according to the present embodiment is characterized in that, after Pt25 and Pd26 are supported on the activated aluminas 21 and 22, the reduction treatment is performed in a CO atmosphere as described above. I do.
ＣＯ雰囲気下の還元処理は、ＣＯを含む還元雰囲気下において、Ｐｔ及びＰｄを担持した活性アルミナ２１，２２に対して好ましくは５５０℃以上８００℃以下、より好ましくは５８０℃以上７５０℃以下の温度で、好ましくは１０分以上３時間以下、より好ましくは１５分以上２時間以内の時間、熱処理することにより行われ得る。 The reduction treatment in a CO atmosphere is preferably performed at a temperature of 550 ° C. to 800 ° C., more preferably 580 ° C. to 750 ° C., for activated alumina 21 and 22 carrying Pt and Pd in a reducing atmosphere containing CO. The heat treatment is preferably performed for 10 minutes to 3 hours, more preferably for 15 minutes to 2 hours.
図６Ａ及び図７Ａは、後述するＣＯ浄化性能の評価試験に用いたＰｔ及びＰｄが担持された活性アルミナ２１，２２の、それぞれＣＯ還元処理前後の電子顕微鏡像である。また、図６Ｂ及び図７Ｂは、図６Ａ及び図７ＡのＣＯ還元処理前後のＰｔ及びＰｄが担持された活性アルミナ２１，２２について、それぞれ大気中８００℃２４時間の熱処理を施した後の試料の電子顕微鏡像である。 FIGS. 6A and 7A are electron microscope images of activated alumina 21 and 22 supporting Pt and Pd used in an evaluation test of the CO purification performance described below before and after the CO reduction treatment, respectively. FIGS. 6B and 7B show samples of the activated alumina 21 and 22 carrying Pt and Pd before and after the CO reduction treatment in FIGS. 6A and 7A, respectively, after being subjected to a heat treatment at 800 ° C. for 24 hours in the atmosphere. It is an electron microscope image.
図６Ａに示すように、還元処理を施していない場合、Ｐｔ及びＰｄは、活性アルミナ２１，２２の表面上で、黒い塊となって担持されていることが判る。そして、図６Ｂに示すように、熱処理を施した後は、Ｐｔ及びＰｄは径約１００ｎｍ前後の黒い塊となって互いに凝集しつつ活性アルミナ２１，２２の表面上に存在していることが判る。 As shown in FIG. 6A, when no reduction treatment is performed, it can be seen that Pt and Pd are supported as black lumps on the surfaces of the activated aluminas 21 and 22. Then, as shown in FIG. 6B, after the heat treatment, it can be seen that Pt and Pd are present on the surfaces of the activated aluminas 21 and 22 while being agglomerated with each other as black lump having a diameter of about 100 nm. .
一方、図７Ａに示すように、Ｐｔ及びＰｄが担持された活性アルミナ２１，２２に還元処理を施した場合には、図６Ａの状態に比べて活性アルミナ２１，２２の表面上のＰｔ及びＰｄの黒い塊が小さくなって分散していることが判る。そして、図７Ｂに示すように、熱処理を施した後には、Ｐｔ及びＰｄの黒い塊は数１０ｎｍ程度の黒い塊として分散して存在していることが判る。 On the other hand, as shown in FIG. 7A, when the activated alumina 21 and 22 carrying Pt and Pd are subjected to a reduction treatment, the Pt and Pd on the surface of the activated alumina 21 and 22 are lower than those in FIG. 6A. It can be seen that the black lump became small and dispersed. Then, as shown in FIG. 7B, after the heat treatment, it can be seen that the black lumps of Pt and Pd are dispersed as black lumps of about several tens nm.
すなわち、ＣＯ還元処理を適用することで、ＣＯ還元処理を施していない場合に比べて、Ｐｔ及びＰｄのシンタリングが抑制されるとともに、熱処理後においてもＰｔ及びＰｄの分散性が向上していることが判る。 That is, by applying the CO reduction treatment, the sintering of Pt and Pd is suppressed as compared with the case where the CO reduction treatment is not performed, and the dispersibility of Pt and Pd is improved even after the heat treatment. You can see that.
さらに、還元処理前後のＰｔ及びＰｄが担持された活性アルミナについて、Ｘ線回折（ＸＲＤ）測定を行った。図８のＸＲＤプロファイルに示すように、還元処理前後で、酸化状態のＰｔＯ及びＰｄＯに由来するピークが減少するとともに、メタル状態のＰｔ及びＰｄに由来するピークが増加していることが判る。 Further, X-ray diffraction (XRD) measurement was performed on the activated alumina carrying Pt and Pd before and after the reduction treatment. As shown in the XRD profile of FIG. 8, it can be seen that before and after the reduction treatment, the peaks derived from PtO and PdO in the oxidized state decrease and the peaks derived from Pt and Pd in the metal state increase.
すなわち、図６〜図８から判るように、Ｐｔ及びＰｄが担持された活性アルミナ２１，２２に対し、還元処理を行うことで、上述のごとく比較的低温で、Ｐｔ及びＰｄのメタル化を促進させることができる。そうすると、これら触媒金属のシンタリング等を抑制するとともに、メタル化が促進されることで比表面積の大きい活性アルミナ２１，２２表面へのＰｔ及びＰｄの分散性が向上する。そうして、触媒活性の高いメタル状態の触媒金属量が増加するとともに、触媒金属と排気ガスとの接触面積が増加することで、触媒付きフィルタ１０における排気ガス中のＨＣ、ＣＯ浄化性能が向上する。 That is, as can be seen from FIGS. 6 to 8, by performing a reduction treatment on the activated alumina 21 and 22 carrying Pt and Pd, the metallization of Pt and Pd is promoted at a relatively low temperature as described above. Can be done. Then, sintering and the like of these catalytic metals are suppressed, and dispersibility of Pt and Pd on the surfaces of the activated alumina 21 and 22 having a large specific surface area is improved by promoting metallization. As a result, the amount of catalytic metal in a metal state having high catalytic activity increases, and the contact area between the catalytic metal and exhaust gas increases, thereby improving the performance of the filter with catalyst 10 for purifying HC and CO in exhaust gas. I do.
＜アルミナ比率＞
後述するＣＯ浄化性能の試験結果から、還元処理された活性アルミナ２１，２２、ＺｒＹＰｒ複合酸化物２３及びＲｈドープＣｅＺｒＮｄ複合酸化物２４の総量に対する還元処理された活性アルミナ２１，２２の比率（本明細書において、「アルミナ比率」と称することがある。）は、触媒金属担持量を低減させつつ良好なＣＯ浄化性能を得る観点から、好ましくは５．０質量％以上５７．０質量％未満、より好ましくは６．０質量％以上５０．０質量％以下、特に好ましくは７．１質量％以上４２．９質量％以下である。アルミナ比率が５．０質量％未満であると、触媒金属の分散性が確保され難くなるとともに十分なＣＯ浄化性能を得ることが困難となる。アルミナ比率が５７．０質量％以上であると、触媒金属担持量に対するアルミナの相対量が大きくなり触媒金属の分散性が向上するから、還元処理の有無に拘わらず良好なＣＯ浄化性能を得ることができるため、還元処理を行う必要がなくなる。
<Alumina ratio>
From the test results of the CO purification performance described later, the ratio of the reduced activated alumina 21 and 22 to the total amount of the reduced activated alumina 21 and 22, the ZrYPr composite oxide 23 and the Rh-doped CeZrNd composite oxide 24 (this specification In the present specification, the “alumina ratio” may be referred to as “alumina ratio”), from the viewpoint of obtaining good CO purification performance while reducing the amount of catalyst metal carried, preferably from 5.0% by mass to less than 57.0% by mass. It is preferably from 6.0% by mass to 50.0% by mass, particularly preferably from 7.1% by mass to 42.9% by mass. If the alumina ratio is less than 5.0% by mass, it is difficult to ensure the dispersibility of the catalyst metal and it is difficult to obtain sufficient CO purification performance. Alumina ratio of 5 to 7. When the content is 0% by mass or more, the relative amount of alumina to the amount of the supported catalyst metal increases, and the dispersibility of the catalyst metal is improved. Therefore, good CO purification performance can be obtained regardless of the presence or absence of the reduction treatment. There is no need to perform any processing.
次に、具体的に実施した実施例について説明する。 Next, a specific embodiment will be described.
＜触媒付きフィルタの調製＞
表１に示す活性アルミナ及びＺｒ系複合酸化物を用い、以下の実施例及び比較例の触媒付きフィルタを上述の方法により調整した。
<Preparation of filter with catalyst>
Using activated alumina and Zr-based composite oxides shown in Table 1, filters with a catalyst of the following Examples and Comparative Examples were prepared by the above-described method.
なお、フィルタ本体としては、ＳｉＣ製フィルタ担体（容量；２５ｍＬ，セル壁厚；１６ｍｉｌ（４０６．４×１０−３ｍｍ）、１７８ｃｐｓｉ（１平方インチ（６３５．１６ｍｍ２）当たりのセル数；１７８））を用いた。 The filter body is made of a SiC filter carrier (capacity: 25 mL, cell wall thickness: 16 mil (406.4 × 10 −3 mm), 178 cpsi (number of cells per square inch (635.16 mm 2 ); 178) ) Was used.
また、ＣＯ雰囲気下の還元処理は、ガス組成ＣＯ ０．５％、Ｎ２バランスのガス流通中６００℃で１時間の熱処理を施すことにより行った。 The reduction treatment in a CO atmosphere was performed by performing a heat treatment at 600 ° C. for 1 hour in a gas flow of a gas composition of 0.5% CO and N 2 balance.
＜ＣＯ浄化性能＞
表２に示す構成の実施例及び比較例の触媒付きフィルタを調製した。なお、各成分の担持量［ｇ／Ｌ］は、フィルタ担体１Ｌ当たりの質量ｇで表している。
<CO purification performance>
The catalyst-equipped filters of Examples and Comparative Examples having the configurations shown in Table 2 were prepared. The amount of each component carried [g / L] is represented by mass g per liter of the filter carrier.
表２に示す触媒付きフィルタに対し、大気エージング処理として、大気中８００℃で２４時間の熱処理を行った。 The filter with the catalyst shown in Table 2 was subjected to a heat treatment at 800 ° C. for 24 hours in the air as an air aging treatment.
その後、担体容量約２５ｍＬ（直径２５．４ｍｍ、長さ５０ｍｍ）のコアサンプルを固定床模擬ガス流通反応装置に取り付け、ＣＯの浄化に関する排気ガス浄化率Ｃ４００（ＣＯ）を以下の要領で測定した。Ｃ４００（ＣＯ）は、触媒入口でのモデル排気ガス温度が４００℃であるときのＣＯの浄化率である。 Thereafter, a core sample having a carrier volume of about 25 mL (diameter: 25.4 mm, length: 50 mm) was attached to a simulated fixed bed gas flow reactor, and the exhaust gas purification rate C400 (CO) for purification of CO was measured in the following manner. C400 (CO) is the CO purification rate when the model exhaust gas temperature at the catalyst inlet is 400 ° C.
すなわち、前処理として、ガス組成Ｃ３Ｈ６ ２００ｐｐｍＣ、ＣＯ ４００ｐｐｍ、ＮＯ １００ｐｐｍ、Ｏ２ １０％、Ｈ２Ｏ １０％、ＣＯ２ ４．５％、Ｎ２バランス（２２Ｌ／分）のモデル排気ガスにて、４１０℃まで３０℃／分で昇温した後、同じガス組成条件にて、１００℃まで下げた。 That is, as a pretreatment, model exhaust gas having a gas composition of C 3 H 6 200 ppmC, CO 400 ppm, NO 100 ppm, O 2 10%, H 2 O 10%, CO 2 4.5%, and N 2 balance (22 L / min) After the temperature was raised to 410 ° C. at a rate of 30 ° C./min, the temperature was lowered to 100 ° C. under the same gas composition conditions.
次に、上記前処理と同一のガス組成のモデル排気ガスにて、４１０℃まで３０℃／分で昇温し、Ｃ４００（ＣＯ）を算出した。 Next, the temperature was raised to 410 ° C. at a rate of 30 ° C./min with a model exhaust gas having the same gas composition as in the above pretreatment, and C400 (CO) was calculated.
表２及び図９に示すように、Ｐｔ及びＰｄの全担持量を０．２０ｇ／Ｌとし、活性アルミナ及びＺｒ系複合酸化物の総量に対する活性アルミナの比率、すなわちアルミナ比率を変化させると、アルミナ比率が５７．０質量％の比較例６，７では、還元処理の有無に拘わらず、ＣＯ浄化性能は良好であることが判った。これに対し、アルミナ比率が５７．０質量％より低い実施例１〜４及び比較例２〜５では、還元処理を行ったアルミナを担持した触媒付きフィルタの方が、還元処理を行っていない活性アルミナを担持した触媒付きフィルタよりもＣＯ浄化性能が優れていることが判った。なお、Ｐｔ及びＰｄが担持された活性アルミナを担持せず、Ｚｒ系複合酸化物のみ担持した比較例１の触媒付きフィルタでは、Ｃ４００（ＣＯ）は５５．３％となり、ＣＯ浄化性能が大きく低下することが判った。 As shown in Table 2 and FIG. 9, when the total loading of Pt and Pd was 0.20 g / L and the ratio of activated alumina to the total amount of activated alumina and Zr-based composite oxide, that is, the alumina ratio was changed, In Comparative Examples 6 and 7 in which the ratio was 57.0% by mass, it was found that the CO purification performance was good regardless of the presence or absence of the reduction treatment. On the other hand, in Examples 1 to 4 and Comparative Examples 2 to 5 in which the alumina ratio was lower than 57.0% by mass, the catalyst-carrying filter supporting alumina subjected to the reduction treatment had a higher activity without the reduction treatment. It was found that CO purification performance was superior to that of a filter with a catalyst supporting alumina. In the case of the catalyst-equipped filter of Comparative Example 1, which did not carry activated alumina carrying Pt and Pd, but carried only the Zr-based composite oxide, C400 (CO) was 55.3%, and the CO purification performance was significantly reduced. I found out.
＜カーボン燃焼性能＞
上記実施例３及び比較例８の触媒付きフィルタについて、ＰＭ燃焼性能を評価するため、カーボン燃焼速度を測定した。
<Carbon combustion performance>
For the catalyst-equipped filters of Example 3 and Comparative Example 8, the carbon burning rate was measured to evaluate the PM burning performance.
なお、比較例８の触媒付きフィルタとして、Ｐｔ、Ｐｄを担持させ且つ還元処理を行っていない活性アルミナと、Ｚｒ系複合酸化物とを混合して混合物を得た後に、その混合物に対して上記ＣＯ雰囲気下の還元処理を行った後にスラリーを調製し、フィルタ本体に担持した以外は、比較例４と同様に調製した。 As a catalyst-equipped filter of Comparative Example 8, a mixture was obtained by mixing Pt, Pd-supported activated alumina not subjected to reduction treatment, and a Zr-based composite oxide. The slurry was prepared in the same manner as in Comparative Example 4 except that the slurry was prepared after the reduction treatment was performed in a CO atmosphere, and the slurry was supported on the filter body.
実施例３及び比較例８の触媒付きフィルタに対し、大気雰囲気において８００℃の温度に２４時間保持するエージング処理を行なった。次に、触媒付きフィルタ１Ｌ当たり１０ｇ相当量のカーボン（カーボンブラック）に１０ｍＬのイオン交換水を加え、スターラーを用いて５分間攪拌することにより、カーボンを水中に十分に分散させた。このカーボン分散液に各触媒付きフィルタの一端面を浸すと同時に、他端面よりアスピレータによる吸引を行なった。次いで触媒付きフィルタを乾燥器に入れ１５０℃の温度に２時間保持して乾燥させた。これにより、カーボンを触媒付きフィルタの排ガス通路壁面に堆積させた。 The filters with catalysts of Example 3 and Comparative Example 8 were subjected to an aging treatment in which the temperature was kept at 800 ° C. for 24 hours in the air atmosphere. Next, 10 mL of ion-exchanged water was added to carbon (carbon black) equivalent to 10 g per 1 L of the filter with catalyst, and the mixture was stirred for 5 minutes using a stirrer to sufficiently disperse the carbon in the water. One end face of each filter with a catalyst was immersed in this carbon dispersion, and at the same time, suction was performed from the other end face by an aspirator. Next, the filter with the catalyst was placed in a dryer and kept at a temperature of 150 ° C. for 2 hours for drying. Thus, carbon was deposited on the exhaust gas passage wall surface of the filter with the catalyst.
触媒付きフィルタを固定床模擬ガス流通反応装置に取り付け、Ｎ２：１００％を空間速度９６０００／ｈで触媒付きフィルタに流し、且つ触媒付きフィルタ入口のガス温度を３０℃／分の速度で上昇させた。触媒付きフィルタの入口部のガス温度が５８０℃に達し、３０分保持した時点で模擬排ガス（Ｏ２；１０％，ＮＯ；３００ｐｐｍ，Ｈ２Ｏ；１０％，残Ｎ２）に切り替えた。そして、カーボンが燃焼することにより生じるＣＯ及びＣＯ２のガス中濃度をリアルタイムで測定し、それらの濃度から、下記の計算式（１）を用いて、各時間ごとに、単位時間当たりのカーボン燃焼量を計算した。 A filter with a catalyst was attached to a simulated fixed bed gas flow reactor, N 2 : 100% was passed through the filter with a catalyst at a space velocity of 96,000 / h, and the gas temperature at the inlet of the filter with the catalyst was increased at a rate of 30 ° C./min. Was. When the gas temperature at the inlet of the filter with a catalyst reached 580 ° C. and was maintained for 30 minutes, the exhaust gas was switched to a simulated exhaust gas (O 2 ; 10%, NO: 300 ppm, H 2 O; 10%, residual N 2 ). Then, the concentrations of CO and CO 2 in the gas generated by the burning of carbon are measured in real time, and from these concentrations, the carbon combustion per unit time is calculated for each time using the following formula (1). The amount was calculated.
カーボン燃焼速度（ｇ／ｈ）
＝｛ガス流速（Ｌ／ｈ）×［（ＣＯ＋ＣＯ２）濃度（ｐｐｍ）／（１×１０６）］｝×１２（ｇ／ｍｏｌ）／２２．４（Ｌ／ｍｏｌ） ・・・（１）
その上で、時間に対するカーボン燃焼量の積算値を求め、カーボン燃焼率が９０％に達するまでに要した時間からカーボン燃焼速度（フィルタ１Ｌでの１分間当たりのカーボン燃焼量(ｇ／分−Ｌ)を求めた。結果を図１０に示す。
Carbon burning rate (g / h)
= {Gas flow rate (L / h) × [( CO + CO 2) concentration (ppm) / (1 × 106 )]} × 12 (g / mol) /22.4 (L / mol) ··· (1)
Then, the integrated value of the amount of carbon combustion with respect to time is determined, and the time required for the carbon combustion rate to reach 90% is calculated from the carbon combustion rate (the amount of carbon combustion per minute (g / min-L in the filter 1L). The results are shown in FIG.
図１０に示すように、比較例８の触媒付きフィルタに比べ、実施例３の触媒付きフィルタでは、カーボン燃焼性能が優れていることが判った。 As shown in FIG. 10, it was found that the catalyst-equipped filter of Example 3 had better carbon combustion performance than the catalyst-equipped filter of Comparative Example 8.
図１１に、比較例８及び実施例３において使用した活性アルミナ及びＺｒ系複合酸化物の混合物サンプルのＸＲＤプロファイルを示す。すなわち、図１１中実線で示す実施例３のＸＲＤプロファイルは、Ｐｔ、Ｐｄ担持後還元処理を行ったアルミナと、Ｚｒ系複合酸化物とを実施例３に示す割合で混合したサンプルの測定結果である。また、図１１中破線で示す比較例１２のＸＲＤプロファイルは、Ｐｔ、Ｐｄ担持後還元処理を行っていないアルミナと、Ｚｒ系複合酸化物とを混合した後、混合物に対して上記還元処理を行ったサンプルの測定結果である。 FIG. 11 shows an XRD profile of a mixture sample of activated alumina and a Zr-based composite oxide used in Comparative Example 8 and Example 3. That is, the XRD profile of Example 3 shown by the solid line in FIG. 11 is a measurement result of a sample in which alumina subjected to reduction treatment after supporting Pt and Pd and a Zr-based composite oxide were mixed at the ratio shown in Example 3. is there. The XRD profile of Comparative Example 12 indicated by the broken line in FIG. 11 shows that after the reduction treatment after mixing Pt and Pd supported alumina and the Zr-based composite oxide, the mixture was subjected to the above reduction treatment. It is the measurement result of the sample which performed.
図１１の拡大図に示すように、実施例３のサンプルに比べて、比較例８のサンプルでは、２θ＝１５度近傍に新しいピークが現れていることが判る。これは、Ｚｒ系複合酸化物の結晶構造が、相転移により、蛍石型構造から一部パイロクロア型構造に変化していることを示している。この結晶構造の変化により、実施例３の触媒付きフィルタに比べて比較例８の触媒付きフィルタでは、カーボン燃焼性能が低下していると考えられる。 As shown in the enlarged view of FIG. 11, it can be seen that a new peak appears near 2θ = 15 degrees in the sample of Comparative Example 8 as compared with the sample of Example 3. This indicates that the crystal structure of the Zr-based composite oxide has partially changed from the fluorite structure to the pyrochlore structure due to the phase transition. It is thought that the carbon combustion performance of the catalyst-equipped filter of Comparative Example 8 was lower than that of the catalyst-equipped filter of Example 3 due to the change in the crystal structure.
以上述べたように、触媒付きフィルタの製造時に、触媒金属を担持させたアルミナのみにＣＯ雰囲気下における還元処理を施した後に、ＰＭ燃焼性能の高いＺｒ系複合酸化物と混ぜてフィルタ本体に担持することで、Ｚｒ系複合酸化物に由来する優れたＰＭ燃焼性能を維持しつつ、触媒金属の担持量を抑えて排気ガス浄化性能にも優れた触媒付きフィルタを得ることができる。 As described above, at the time of manufacturing a filter with a catalyst, only the alumina supporting the catalyst metal is subjected to a reduction treatment in a CO atmosphere, and then mixed with a Zr-based composite oxide having a high PM combustion performance and supported on the filter body. By doing so, it is possible to obtain a filter with a catalyst that is excellent in exhaust gas purification performance by suppressing the amount of catalyst metal loaded while maintaining excellent PM combustion performance derived from the Zr-based composite oxide.
１０ 触媒付きフィルタ（触媒付パティキュレートフィルタ）
１１ 排気通路
１２ 排気ガス流入路（排気ガス通路）
１３ 排気ガス流出路（排気ガス通路）
１４ 栓
１５ 隔壁（排気ガス通路壁）
１６ 細孔（排気ガス通路）
２０ 触媒層
２１ Ｌａ含有アルミナ（アルミナ）
２２ 純アルミナ（アルミナ）
２３ ＺｒＹＰｒ複合酸化物（Ｃｅ非含有Ｚｒ系複合酸化物、Ｚｒ系複合酸化物）
２４ ＲｈドープＣｅＺｒＮｄ複合酸化物（ＣｅＺｒ系複合酸化物、Ｚｒ系複合酸化物）
２５ Ｐｔ（触媒金属）
２６ Ｐｄ（触媒金属）
10. Filter with catalyst (particulate filter with catalyst)
11 Exhaust passage 12 Exhaust gas inflow passage (exhaust gas passage)
13 Exhaust gas outflow passage (exhaust gas passage)
14 Plug 15 Partition wall (exhaust gas passage wall)
16 pores (exhaust gas passage)
Reference Signs List 20 catalyst layer 21 La-containing alumina (alumina)
22 Pure alumina (alumina)
23 ZrYPr composite oxide (Ce-free Zr-based composite oxide, Zr-based composite oxide)
24 Rh-doped CeZrNd composite oxide (CeZr-based composite oxide, Zr-based composite oxide)
25 Pt (catalyst metal)
26 Pd (catalytic metal)
Claims (6)
アルミナに触媒金属を担持させる工程と、
Ｚｒを主成分とするＺｒ系複合酸化物を準備する工程と、
前記触媒金属を担持させたアルミナに対し、ＣＯ雰囲気下で還元処理を施す工程と、
前記Ｚｒ系複合酸化物と、前記還元処理されたアルミナとを混合し、前記フィルタ本体の前記排気ガス通路壁上に担持して前記触媒層を形成する工程とを備え、
前記Ｚｒ系複合酸化物と前記還元処理されたアルミナとの総量に対する前記還元処理されたアルミナの比率は、５．０質量％以上５７．０質量％未満である
ことを特徴とする触媒付きパティキュレートフィルタの製造方法。 Manufacture of a particulate filter with a catalyst, comprising: a filter main body disposed in an exhaust passage of an engine for collecting particulates in exhaust gas; and a catalyst layer formed on an exhaust gas passage wall of the filter main body. The method,
Supporting a catalyst metal on alumina,
Preparing a Zr-based composite oxide containing Zr as a main component;
A step of subjecting the catalyst metal-supported alumina to a reduction treatment under a CO atmosphere;
Mixing the Zr-based composite oxide and the reduced alumina, and supporting the catalyst body on the exhaust gas passage wall of the filter body to form the catalyst layer ,
The ratio of the reduced alumina to the total amount of the Zr-based composite oxide and the reduced alumina is not less than 5.0% by mass and less than 57.0% by mass. A method for producing a particulate filter with a catalyst.
前記Ｚｒ系複合酸化物は、Ｃｅを含有するＣｅＺｒ系複合酸化物、及び、Ｃｅを含まず且つＣｅ以外の希土類金属を含有するＣｅ非含有Ｚｒ系複合酸化物の少なくとも一方である
ことを特徴とする触媒付きパティキュレートフィルタの製造方法。 Oite to claim 1,
The Zr-based composite oxide is at least one of a Ce-Zr-based composite oxide containing Ce, and a Ce-free Zr-based composite oxide containing no Ce and containing a rare earth metal other than Ce. Of producing a particulate filter with a catalyst.
前記Ｚｒ系複合酸化物は、Ｃｅを含まず且つＣｅ以外の希土類金属を含有するＣｅ非含有Ｚｒ系複合酸化物を含み、The Zr-based composite oxide includes a Ce-free Zr-based composite oxide that does not contain Ce and contains a rare earth metal other than Ce.
前記Ｃｅ非含有Ｚｒ系複合酸化物は、前記Ｃｅ以外の希土類金属としてＹとＰｒとを含むＺｒＹＰｒ複合酸化物であるThe Ce-free Zr-based composite oxide is a ZrYPr composite oxide containing Y and Pr as rare earth metals other than Ce.
ことを特徴とする触媒付きパティキュレートフィルタの製造方法。A method for producing a particulate filter with a catalyst, comprising:
前記還元処理を施す工程は、ＣＯを含む還元雰囲気下において、５００℃以上８００℃以下で熱処理する工程である
ことを特徴とする触媒付きパティキュレートフィルタの製造方法。 In any one of claims 1 to 3,
The method for producing a particulate filter with a catalyst, wherein the step of performing the reduction treatment is a step of performing a heat treatment at 500 ° C. or more and 800 ° C. or less in a reducing atmosphere containing CO.
前記触媒金属は、Ｐｔ及びＰｄの少なくとも一方である
ことを特徴とする触媒付きパティキュレートフィルタの製造方法。 In any one of claims 1 to 4,
The method for manufacturing a particulate filter with a catalyst, wherein the catalyst metal is at least one of Pt and Pd.
前記エンジンは、希薄燃焼エンジンである
ことを特徴とする触媒付きパティキュレートフィルタの製造方法。 In any one of claims 1 to 5,
The method of manufacturing a particulate filter with a catalyst, wherein the engine is a lean burn engine.
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