JP2000237589A - Catalyst for purifying exhaust gas - Google Patents
Catalyst for purifying exhaust gasInfo
- Publication number
- JP2000237589A JP2000237589A JP11045737A JP4573799A JP2000237589A JP 2000237589 A JP2000237589 A JP 2000237589A JP 11045737 A JP11045737 A JP 11045737A JP 4573799 A JP4573799 A JP 4573799A JP 2000237589 A JP2000237589 A JP 2000237589A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- catalyst
- gas purifying
- group
- purifying catalyst
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000003054 catalyst Substances 0.000 title claims abstract description 150
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 14
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 13
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 11
- 239000002131 composite material Substances 0.000 claims description 34
- 239000000758 substrate Substances 0.000 claims description 18
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 6
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 6
- 229910052684 Cerium Inorganic materials 0.000 claims description 5
- 229910052779 Neodymium Inorganic materials 0.000 claims description 5
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 5
- 229910052746 lanthanum Inorganic materials 0.000 claims description 5
- 229910052726 zirconium Inorganic materials 0.000 claims description 5
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 4
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 3
- 238000002441 X-ray diffraction Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 8
- 229930195733 hydrocarbon Natural products 0.000 abstract description 3
- 150000002430 hydrocarbons Chemical class 0.000 abstract description 3
- 239000004215 Carbon black (E152) Substances 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 78
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 63
- 239000000843 powder Substances 0.000 description 22
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 20
- 239000010410 layer Substances 0.000 description 20
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 19
- 230000000694 effects Effects 0.000 description 17
- 238000000746 purification Methods 0.000 description 16
- 239000010948 rhodium Substances 0.000 description 16
- 239000012188 paraffin wax Substances 0.000 description 14
- 230000003197 catalytic effect Effects 0.000 description 11
- 239000002002 slurry Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 238000000034 method Methods 0.000 description 6
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 229910000510 noble metal Inorganic materials 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000003063 flame retardant Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 229910004625 Ce—Zr Inorganic materials 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
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 229910052878 cordierite Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 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 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 102100033041 Carbonic anhydrase 13 Human genes 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 101000867860 Homo sapiens Carbonic anhydrase 13 Proteins 0.000 description 1
- 229910021193 La 2 O 3 Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910019017 PtRh Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000011160 research Methods 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
- 229930195734 saturated hydrocarbon Natural products 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Catalysts (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、排気ガス浄化用触
媒に関し、特に自動車等の内燃機関から排出される排気
ガス中の有害成分である炭化水素(以下、「HC」と称
す)、一酸化炭素(以下、「CO」と称す)、及び窒素
酸化物(以下、「NOx 」と称す)を同時に除去する三
元触媒のなかでも、特に難燃なHCを高効率で浄化する
排気ガス浄化用触媒に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying catalyst, and more particularly to hydrocarbons (hereinafter referred to as "HC"), which are harmful components in exhaust gas discharged from an internal combustion engine of an automobile or the like, and monoxide. Among the three-way catalysts for simultaneously removing carbon (hereinafter, referred to as “CO”) and nitrogen oxides (hereinafter, referred to as “NO x ”), exhaust gas purification that purifies highly flame-retardant HC with high efficiency. For catalysts.
【0002】[0002]
【従来の技術】従来より、排気ガス浄化用触媒は高効率
でHCを浄化するために多段配置された場合、未燃排気
ガス中には難燃HC(主に飽和炭化水素:パラフィン)
が増加するため、排気下流の触媒は上流触媒に比べて効
率が悪化する。その為、難燃HC浄化能に優れた排気ガ
ス浄化用触媒の開発が期待されている。2. Description of the Related Art Conventionally, when exhaust gas purifying catalysts are arranged in multiple stages to purify HC with high efficiency, unburned exhaust gas contains flame-retardant HC (mainly saturated hydrocarbon: paraffin).
Therefore, the efficiency of the catalyst downstream of the exhaust gas is lower than that of the upstream catalyst. Therefore, development of an exhaust gas purifying catalyst having excellent flame retardant HC purifying ability is expected.
【0003】かかる排気ガス浄化用触媒としては、例え
ば、特開昭62−282641号公報、特開平5−49
929号公報、及び特開平8−24644号公報に開示
されているものがある。特開昭62−282641号公
報には、ロジウムを酸化ジルコニウムに担持させた排気
ガス浄化用触媒が開示されており、具体的にはロジウム
を含有させた酸化ジルコニウム、活性アルミナ、酸化セ
リウムとアルミナゾルとを含むスラリーを、担体に付着
・乾燥・焼成した後、白金を担持させたものである。As such an exhaust gas purifying catalyst, for example, Japanese Patent Application Laid-Open No. 62-282641, Japanese Patent Application Laid-Open No. 5-49
929 and JP-A-8-24644. Japanese Unexamined Patent Publication (Kokai) No. 62-282641 discloses an exhaust gas purification catalyst in which rhodium is supported on zirconium oxide. Specifically, zirconium oxide containing rhodium, activated alumina, cerium oxide and alumina sol are disclosed. Is applied to a carrier, dried and calcined, and then loaded with platinum.
【0004】特開平5−49929号公報には、活性ア
ルミナからなる触媒担持層をもつ一体型構造体の排気ガ
スが流入する入口側にパラジウム及びロジウムが担持さ
れ、排気ガスが流出する出口側に白金及びロジウムが担
持された触媒で、ロジウムの担持量が入口側より出口側
に多いことを特徴とする排気ガス浄化用触媒が開示され
ている。JP-A-5-49929 discloses that an integrated structure having a catalyst supporting layer made of activated alumina has palladium and rhodium supported on an inlet side where exhaust gas flows in and an outlet side on which exhaust gas flows out. There is disclosed an exhaust gas purifying catalyst in which platinum and rhodium are supported, wherein the amount of rhodium supported is larger on the outlet side than on the inlet side.
【0005】特開平8−24644号公報には、担体基
材表面に被覆形成された触媒担持層に、パラジウム、白
金、アルカリ土類金属からなる活性成分から構成された
触媒において、排気ガスが流入する入口側に白金が担持
されることを特徴とする排気ガス浄化用触媒が開示され
ている。[0005] Japanese Patent Application Laid-Open No. Hei 8-24644 discloses that an exhaust gas flows into a catalyst supporting layer coated on the surface of a carrier base material in the case of a catalyst comprising an active component comprising palladium, platinum and an alkaline earth metal. There is disclosed an exhaust gas purifying catalyst characterized in that platinum is carried on the inlet side.
【0006】[0006]
【発明が解決しようとする課題】しかし、前記公報中に
記載された従来の触媒では、触媒容量を増加させ、より
一層排気ガスにおける有害成分残存率を低下させようと
した場合、排気ガス下流においては触媒による浄化が進
んでいくため、転化しにくいHC成分割合が増加する。
その結果排気ガス雰囲気をHC燃焼に適した酸化雰囲気
においても、浄化性能が悪化するという問題点があっ
た。However, in the conventional catalyst described in the above-mentioned publication, when it is attempted to increase the catalyst capacity and further reduce the residual ratio of harmful components in the exhaust gas, it is difficult to reduce the harmful components remaining in the exhaust gas downstream. Since the purification by the catalyst proceeds, the HC component ratio that is difficult to convert increases.
As a result, even when the exhaust gas atmosphere is an oxidizing atmosphere suitable for HC combustion, there is a problem that the purification performance is deteriorated.
【0007】従って、本発明の目的は、従来の排気ガス
浄化用触媒及び触媒システムよりも、HC浄化性能が向
上し、特に、今まで未浄化だったHC成分に対して、ス
トイキを中心としてリッチからリーンのより広い雰囲気
条件下で高い浄化性能を有する排気ガス浄化用触媒を提
供することに有る。Accordingly, an object of the present invention is to improve the HC purification performance as compared with the conventional exhaust gas purifying catalyst and catalyst system, and particularly to improve the HC component, which has not been purified, up to the stoichiometric center. Another object of the present invention is to provide an exhaust gas purifying catalyst having high purifying performance under a wider range of atmosphere conditions.
【0008】[0008]
【課題を解決するための手段】本発明者らは、上記課題
を解決するために研究した結果、未浄化HCの主成分で
あるパラフィン系の炭化水素に対する触媒活性を向上さ
せるために、触媒成分担持層中にPtと2種のZr系複
合酸化物を含有させ、所定量のPtがZr複合酸化物に
担持されることにより、従来未浄化であったHC成分の
浄化性能が著しく向上し広い雰囲気下で維持され、更に
ストイキよりややリーン域のNOx 浄化能に優れるPt
の特性を有効に発現させ、スライトリーンのNOx 性能
も向上することを見出し、本発明に到達した。Means for Solving the Problems As a result of research conducted to solve the above problems, the present inventors have found that a catalyst component for improving the catalytic activity on paraffinic hydrocarbons, which is a main component of unpurified HC, is used. By including Pt and two types of Zr-based composite oxides in the support layer and carrying a predetermined amount of Pt on the Zr composite oxide, the purification performance of the HC component which has not been purified conventionally is remarkably improved and wide. Pt that is maintained under an atmosphere and has a slightly leaner NO x purification performance than stoichiometric
Characteristics effectively to express the, slight lean of the NO x performance it found that improved, thereby achieving the present invention.
【0009】請求項1記載の排気ガス浄化用触媒では、
触媒成分担持層を有する一体構造型触媒において、触媒
成分としてPtと、Pd、Rhから選ばれた少なくとも
1種を含有し、更に、2A族元素と3B族(但しCeを
除く)元素の中から選ばれた少なくとも1種を含有する
Zr複合酸化物(A)と、Ceと3A族と6B族元素の
中から選ばれた少なくとも1種を含有するZr複合酸化
物(B)の2種をPt担持基材として用いることを特徴
とする。In the exhaust gas purifying catalyst according to the first aspect,
The monolithic catalyst having a catalyst component-supporting layer contains at least one selected from the group consisting of Pt, Pd, and Rh as a catalyst component, and further includes a group 2A element and a group 3B (excluding Ce) element. Two kinds of Zr composite oxides (A) containing at least one selected from the group consisting of Pt and Zr composite oxides (B) containing at least one selected from the group consisting of Ce and Group 3A and Group 6B elements It is characterized in that it is used as a supporting substrate.
【0010】請求項2記載の排気ガス浄化用触媒では、
請求項1記載の排気ガス浄化用触媒のストイキ近傍のリ
ッチからリーン雰囲気下におけるパラフィン成分に対す
る触媒活性を更に有効に発現させるために、含有される
Pt量は、1g/L〜15g/Lであり、Zr複合酸化
物へのPt担持量比率が触媒中の全Pt量の少なくとも
10wt%以上であることを特徴とする。In the exhaust gas purifying catalyst according to the second aspect,
The amount of Pt contained in the exhaust gas purifying catalyst according to claim 1 is 1 g / L to 15 g / L in order to more effectively exhibit the catalytic activity for paraffin components in a rich to lean atmosphere near the stoichiometric atmosphere. , The ratio of the amount of Pt carried to the Zr composite oxide is at least 10 wt% or more of the total Pt amount in the catalyst.
【0011】更に、請求項1または2記載の排気ガス浄
化用触媒のパラフィン成分に対する高い触媒活性を維持
し、安定的に発現させるために、請求項3記載の排気ガ
ス浄化用触媒では、請求項1または2記載のZr複合酸
化物の含有される元素比率が、Zrに対する原子比にし
て1〜40%であることを特徴とする。Further, in order to maintain high catalytic activity on paraffin components of the exhaust gas purifying catalyst according to the first or second aspect and to stably develop the paraffin component, the exhaust gas purifying catalyst according to the third aspect has the following features. 3. The element ratio of the Zr composite oxide according to 1 or 2 is 1 to 40% in terms of atomic ratio with respect to Zr.
【0012】請求項1ないし3記載の排気ガス浄化用触
媒のパラフィン成分に対する高い触媒活性を広い空燃比
(以下、A/Fと称す)雰囲気で発現させるために、請
求項4記載の排気ガス浄化用触媒では、請求項1ないし
3記載の排気ガス浄化用触媒において、更に、Pt担持
基材に用いる2種のZr複合酸化物の含有される割合
{A/(A+B)}が、10〜90wt%であることを
特徴とする。The exhaust gas purifying catalyst according to claim 4, wherein the catalyst for purifying exhaust gas according to claim 1 to 3 exhibits high catalytic activity on paraffin components in a wide air-fuel ratio (hereinafter referred to as A / F) atmosphere. In the exhaust gas purifying catalyst according to any one of claims 1 to 3, the content ratio (A / (A + B)) of the two kinds of Zr composite oxides used in the Pt-supporting base material is 10 to 90 wt%. %.
【0013】更に、請求項1ないし4記載の排気ガス浄
化用触媒において、耐久後も高い浄化性能を発現させる
ために、請求項5記載の排気ガス浄化用触媒では、2種
のZr複合酸化物のX線回折で測定される結晶構造が、
積分強度にして、正方晶の比率が少なくとも10%以上
であることを特徴とする。Further, in the exhaust gas purifying catalyst according to any one of claims 1 to 4, the catalyst for purifying exhaust gas according to claim 5 has two kinds of Zr composite oxides so as to exhibit high purification performance even after durability. The crystal structure measured by X-ray diffraction of
It is characterized in that the ratio of the tetragonal system is at least 10% or more in terms of integrated intensity.
【0014】更に、請求項1ないし5記載の排気ガス浄
化用触媒において、リッチ・リーンの雰囲気変化による
触媒状態変化を緩和して高い触媒活性を維持できるよう
に、請求項6記載の排気ガス浄化用触媒では、更に、ラ
ンタン、ネオジウム、ジルコニウムからなる群より選ば
れた少なくとも1種を、原子比にして1〜40%含むセ
リウム酸化物が含有されることを特徴とする。Further, in the exhaust gas purifying catalyst according to any one of the first to fifth aspects, the exhaust gas purifying catalyst according to the sixth aspect is capable of maintaining a high catalytic activity by mitigating a change in the catalyst state due to a rich / lean atmosphere change. The catalyst for use is further characterized by containing a cerium oxide containing at least one selected from the group consisting of lanthanum, neodymium and zirconium in an atomic ratio of 1 to 40%.
【0015】更に、請求項1ないし6記載の排気浄化用
触媒のパラフィン浄化活性とスライトリーンNOx 活性
を安定して発現させるために、請求項7記載の排気ガス
浄化用触媒では、触媒活性成分であるPdが、Ptと同
一触媒層に共存しない構造とすることを特徴とする。Furthermore, in order to stably express the claims 1 to an exhaust purifying catalyst 6 according paraffin purification activity and scan write lean NO x activity, the exhaust gas purifying catalyst according to claim 7, wherein the catalytically active component Is characterized in that Pd does not coexist with Pt in the same catalyst layer.
【0016】本発明の主要な排気ガス浄化用触媒の触媒
成分担持層に含有される貴金属としては、少なくとも白
金が含有される。当該Ptの含有量は、触媒1L容量中
1〜15gである。1g未満では低温活性や浄化性能が
十分に発現せず、逆に15gを超えてもPtの触媒活性
は飽和し、添加量に見合う性能向上は得られず経済性に
乏しい。The noble metal contained in the catalyst component supporting layer of the main exhaust gas purifying catalyst of the present invention contains at least platinum. The content of Pt is 1 to 15 g in 1 L of the catalyst. If the amount is less than 1 g, the low-temperature activity and purification performance are not sufficiently exhibited. Conversely, if the amount exceeds 15 g, the catalytic activity of Pt is saturated, and the performance improvement corresponding to the added amount cannot be obtained, resulting in poor economy.
【0017】前記Ptが担持される基材としては、Pt
のパラフィン転化性能をリッチ雰囲気で向上させるた
め、2A族元素と3B族(希土類:但しCe除く)元素
の中から選ばれた少なくとも1種を含有するZr複合酸
化物を用いている。上記元素のうち、より好ましくは、
Mg,Ca,Y,La,Pr,Nd,Gdである。The substrate on which the Pt is supported is Pt
In order to improve the paraffin conversion performance in a rich atmosphere, a Zr composite oxide containing at least one element selected from a group 2A element and a group 3B (rare earth: excluding Ce) element is used. Of the above elements, more preferably,
Mg, Ca, Y, La, Pr, Nd, and Gd.
【0018】パラフィン転化性能をリーン雰囲気で向上
させるため、Ceと3A族元素と6B族元素の中から選
ばれた少なくとも1種を含有するZr複合酸化物を用い
ている。上記元素のうち、より好ましくは、Ce,W,
Al,Inである。In order to improve the paraffin conversion performance in a lean atmosphere, a Zr composite oxide containing Ce and at least one element selected from Group 3A and Group 6B elements is used. Of the above elements, more preferably, Ce, W,
Al and In.
【0019】更に、上記Zr複合酸化物へのPt担持濃
度は、特に限定されないが浄化性能を高めるために1.
0〜10wt%の範囲が好ましい。1.0wt%未満で
はPtの熱耐久性が低下し、10wt%以上では高濃度
過ぎてPt粒子が粗すぎるため有効でない。Further, the concentration of Pt supported on the Zr composite oxide is not particularly limited, but is set to 1.
The range of 0 to 10 wt% is preferable. If the content is less than 1.0 wt%, the thermal durability of Pt decreases, and if it is 10 wt% or more, the Pt particles are too high and the Pt particles are too coarse, which is not effective.
【0020】また、かかるZr複合酸化物の使用量は、
触媒1Lあたり10〜200gである。10g未満だと
充分な貴金属の耐久性が得られず、200gより多く使
用しても改良効果は飽和し有効でない。更に好ましくは
Zr酸化物の初期表面積は1gあたり30m2 以上のも
のが適切である。これは担持されたPtが活性を発現す
るのに適切な粒径確保をするためで、1gあたり30m
2 以下では、初期活性が低下し、その有効性が失われる
ため好ましくない。The amount of the Zr composite oxide used is as follows:
It is 10 to 200 g per liter of the catalyst. If the amount is less than 10 g, sufficient durability of the noble metal cannot be obtained, and even if the amount is more than 200 g, the improvement effect is saturated and is not effective. More preferably, the initial surface area of the Zr oxide is more than 30 m 2 per gram. This is to secure a particle size appropriate for the carried Pt to exhibit an activity, and is 30 m / g.
A ratio of 2 or less is not preferable because the initial activity decreases and its effectiveness is lost.
【0021】更に、請求項3記載の排気ガス浄化用触媒
は、Ptが担持されるZr複合酸化物が高温でも安定で
耐久後性能に優れるようにするため、含有される元素比
率が、Zrに対する原子比にして1〜40%であること
を特徴とする。1%未満では添加元素の効果が充分に発
現せず、40%を超えるとZr酸化物自体の安定性が損
なわれるため有効でない。Further, in the exhaust gas purifying catalyst according to the third aspect, in order that the Pt-supported Zr composite oxide is stable even at a high temperature and has excellent post-durability performance, the content ratio of the element contained with respect to Zr is reduced. The atomic ratio is 1 to 40%. If it is less than 1%, the effect of the added element is not sufficiently exhibited, and if it exceeds 40%, the stability of the Zr oxide itself is impaired, so that it is not effective.
【0022】更に、パラフィン成分に対する高い触媒活
性を広いA/F雰囲気で発現させるために、請求項4記
載の排気ガス浄化用触媒は、Pt担持基材に用いる2種
のZr複合酸化物の含有される割合{A/(A+B)}
が、10〜90wt%としている。上記範囲外では高活
性なA/F範囲が狭まるため有効でない。Further, in order to exhibit a high catalytic activity for paraffin components in a wide A / F atmosphere, the exhaust gas purifying catalyst according to claim 4 contains two kinds of Zr composite oxides used for a Pt-supporting substrate. Rate {A / (A + B)}
Is 10 to 90 wt%. Outside the above range, the highly active A / F range is not effective because it is narrowed.
【0023】また、かかる2種のZr複合酸化物は、X
線回折で測定される結晶構造として、積分強度比から測
った正方晶の比率が少なくとも10%以上であることを
特徴とする。ZrO2 は本来単斜晶系であるが添加元素
が固溶することで正方晶系に安定化され、相変化が抑制
されることで担持されたPtはシンタリングしにくく耐
久後もパラフィン成分に対する触媒活性が高く維持でき
る。10%未満では上記効果が十分でなく効果的でな
い。The two kinds of Zr composite oxides are represented by X
As a crystal structure measured by line diffraction, a ratio of a tetragonal crystal measured from an integrated intensity ratio is at least 10% or more. Although ZrO 2 is originally monoclinic, it is stabilized to a tetragonal system by solid solution of the added element, and the phase change is suppressed, so that the supported Pt is less likely to sinter, and even after durability, the Pt is supported on the paraffin component. High catalytic activity can be maintained. If it is less than 10%, the above effect is not sufficient and is not effective.
【0024】請求項1ないし5記載の排気ガス浄化用触
媒の雰囲気変動に対する触媒活性を維持するために、請
求項6記載の排気ガス浄化用触媒は、更に、ランタン、
ネオジウム、ジルコニウムからなる群より選ばれた少な
くとも1種を、原子比にして1〜40%含むセリウム酸
化物が含有されるものである。1〜40%としたのはセ
リウム酸化物(CeO2 )に上記添加物を加えることで
CeO2 本来の酸素吸放出能とBET比表面積(熱安定
性)を顕著に改良するためである。1%未満ではCeO
2 のみの場合と変わらないため上記添加元素の効果が現
れず、40%以上では上記効果が飽和もしくは低下す
る。In order to maintain the catalytic activity of the exhaust gas purifying catalyst according to any one of claims 1 to 5 with respect to atmospheric fluctuations, the exhaust gas purifying catalyst according to claim 6 further comprises lanthanum,
Cerium oxide containing at least one element selected from the group consisting of neodymium and zirconium in an atomic ratio of 1 to 40% is contained. The reason for setting the content to 1 to 40% is to remarkably improve the original oxygen absorption / release capacity and the BET specific surface area (thermal stability) of CeO 2 by adding the above additive to cerium oxide (CeO 2 ). If less than 1%, CeO
The effect of the additional element does not appear because it is not different from the case of only 2 and the effect is saturated or reduced at 40% or more.
【0025】更に、請求項7記載の排気ガス浄化用触媒
は、請求項1記載の排気ガス浄化用触媒において触媒活
性成分であるPdが、Ptと同一触媒層に共存しない構
造にするものである。PdとPtが同一触媒層に共存し
ていると特にリーン域のパラフィン浄化・NOx 浄化特
性に優れるPt表面状態が密に接触しているPdにより
失われてしまい、折角の基材効果が損なわれるためであ
る。Further, the exhaust gas purifying catalyst according to claim 7 has a structure in which Pd which is a catalytically active component in the exhaust gas purifying catalyst according to claim 1 does not coexist with Pt in the same catalyst layer. . Pd and Pt are be lost by Pd that when coexisting in the same catalyst layer Pt surface condition particularly excellent in paraffin purification · NO x purification characteristic of the lean zone in intimate contact, impaired substrate effect of precious This is because
【0026】本発明の排気ガス浄化用触媒を製造するに
際しては、30m2 /g以上の初期表面積を有するZr
複合酸化物にPtを含浸担持して、更に熱処理すること
により請求項1記載の排気ガス浄化用触媒が得られる。In producing the exhaust gas purifying catalyst of the present invention, Zr having an initial surface area of 30 m 2 / g or more is used.
The exhaust gas purifying catalyst according to claim 1 is obtained by impregnating and supporting Pt on the composite oxide and further performing a heat treatment.
【0027】前記Zr複合酸化物にPtを担持する方法
としては、例えば含浸法や混練法等の公知の方法の中か
ら適宜選択して行うことができるが、特に含浸法を用い
ることが好ましい。The method of supporting Pt on the Zr composite oxide can be appropriately selected from known methods such as an impregnation method and a kneading method, but it is particularly preferable to use the impregnation method.
【0028】Ptの原料化合物としては、硝酸塩等水溶
性のものであれば任意のものが使用できる。As the raw material compound of Pt, any compound can be used as long as it is water-soluble such as nitrate.
【0029】また、請求項1記載の排気ガス浄化用触媒
において、Pd、Rhから選ばれた少なくとも1種を担
持する基材には、活性アルミナ、Ce酸化物、Zr酸化
物等の耐火性無機酸化物を用いることができる。特にP
dには活性アルミナとCe酸化物に分配して担持される
ことが好ましく、Rhは活性アルミナ上では不活性化す
るため、Zr等で安定化されたアルミナまたは、Zr酸
化物に担持されることが好ましい。[0029] In the exhaust gas purifying catalyst according to the first aspect, the substrate supporting at least one selected from Pd and Rh may include a refractory inorganic material such as activated alumina, Ce oxide and Zr oxide. An oxide can be used. Especially P
It is preferable that d is distributed and supported on activated alumina and Ce oxide, and Rh is inactivated on activated alumina, so that it is supported on Zr-stabilized alumina or Zr oxide. Is preferred.
【0030】更に、請求項1ないし6記載の排気ガス浄
化用触媒中の触媒成分に加えて、担体との密着性を高め
る為に、活性アルミナ、ベーマイトアルミナ、アルミナ
ゾルからなる群より選ばれた1種を加えることが好まし
い。Further, in addition to the catalyst components in the exhaust gas purifying catalyst according to any one of claims 1 to 6, in order to enhance the adhesion to the carrier, one selected from the group consisting of activated alumina, boehmite alumina and alumina sol. Preferably, a seed is added.
【0031】Pd、及びRhの原料化合物としては、ジ
ニトロジアンミン酸塩、塩化物、硝酸塩等水溶性のもの
であれば任意のものが使用できる。As the raw material compounds of Pd and Rh, any compounds can be used as long as they are water-soluble, such as dinitrodiamminate, chloride and nitrate.
【0032】このようにして得られる本発明にかかる排
気ガス浄化用触媒は、無担体でも有効に使用することが
できるが、粉砕・スラリーとし、触媒担体にコートし
て、400〜900℃で焼成して用いることが好まし
い。触媒担体としては、公知の触媒担体の中から適宜選
択して使用することができ、例えば耐火性材料からなる
モノリス担体やメタル担体等が挙げられる。The exhaust gas purifying catalyst according to the present invention thus obtained can be used effectively without a carrier. However, the catalyst is pulverized and slurry, coated on the catalyst carrier and calcined at 400 to 900 ° C. It is preferable to use them. The catalyst carrier can be appropriately selected from known catalyst carriers and used, and examples thereof include a monolith carrier made of a refractory material and a metal carrier.
【0033】得られた前記Pt担持Zr複合酸化物粉
末、活性アルミナ、ベーマイトアルミナ、アルミナゾル
からなる群より選ばれた1種を加えて湿式にて粉砕して
スラリーとし、触媒担体に付着させ、400〜650℃
の範囲の温度で空気中及び/または空気流通下で焼成を
行うことで、請求項1記載の排気ガス浄化用触媒を得
る。One kind selected from the group consisting of the obtained Pt-supported Zr composite oxide powder, activated alumina, boehmite alumina, and alumina sol is added and wet-milled to form a slurry, which is then attached to a catalyst carrier. ~ 650 ° C
The catalyst for purifying exhaust gas according to claim 1 is obtained by performing calcination in air and / or under a flow of air at a temperature in the range described above.
【0034】更に、Pd担持アルミナ粉末、Pd担持セ
リウム酸化物粉末、Rh担持粉末、活性アルミナ、ベー
マイトアルミナ、アルミナゾルからなる群より選ばれた
1種を加えて湿式にて粉砕してスラリーとして、Pt層
と同様な手順で前記Pt触媒層の内層、あるいは表層に
配置させることで請求項1記載のPtPd、PtRh、
PtPdRh系の排気ガス浄化用触媒を得る。Further, one selected from the group consisting of Pd-supported alumina powder, Pd-supported cerium oxide powder, Rh-supported powder, activated alumina, boehmite alumina, and alumina sol is added, and the mixture is pulverized by a wet method to form a slurry to form Pt. The PtPd, PtRh, or PtPd according to claim 1, which is disposed on the inner layer or the surface layer of the Pt catalyst layer in the same procedure as the layer.
A PtPdRh-based exhaust gas purifying catalyst is obtained.
【0035】前記触媒担体の形状は、特に制限されない
が、通常はハニカム形状で使用することが好ましく、ハ
ニカム状の各種基材に触媒粉末を塗布して用いられる。
このハニカム材料としては、一般にセラミック等のコー
ジェライト質のものが多く用いられるが、フェライト系
ステンレス等の金属材料からなるハニカム材料を用いる
ことも可能であり、更には触媒成分粉末そのものをハニ
カム状に成形しても良い。触媒の形状をハニカム状とす
ることにより、触媒と排気ガスとの接触面積が大きくな
り、圧力損失も抑制できるため自動車用排気ガス浄化用
触媒として用いる場合に極めて有効である。Although the shape of the catalyst carrier is not particularly limited, it is usually preferable to use the catalyst carrier in the form of a honeycomb, and the catalyst powder is applied to various honeycomb substrates to be used.
As the honeycomb material, cordierite-based materials such as ceramics are generally used in general, but it is also possible to use a honeycomb material made of a metal material such as ferrite stainless steel, and further, the catalyst component powder itself is formed into a honeycomb shape. It may be molded. By making the shape of the catalyst into a honeycomb shape, the contact area between the catalyst and the exhaust gas is increased and the pressure loss can be suppressed, so that it is extremely effective when used as an exhaust gas purifying catalyst for automobiles.
【0036】ハニカム材料に付着させる触媒成分コート
層の量は、触媒成分全体のトータルで、触媒1Lあた
り、50g〜400gが好ましい。触媒成分担持層が多
い程、触媒活性や触媒寿命の面からは好ましいが、コー
ト層が厚くなりすぎると、触媒成分担持層内部で反応ガ
スが拡散不良となり触媒と十分に接触できなくなるた
め、活性に対する増量効果が飽和し、更にはガスの通過
抵抗も大きくなってしまう。このため、コート層量は、
上記触媒1Lあたり50g〜400gが好ましい。The amount of the catalyst component coat layer adhered to the honeycomb material is preferably 50 g to 400 g per liter of the catalyst in total of the entire catalyst components. The larger the number of catalyst component supporting layers, the more preferable in terms of catalyst activity and catalyst life.However, if the coating layer is too thick, the reaction gas will be insufficiently diffused inside the catalyst component supporting layer and will not be able to contact the catalyst sufficiently. The effect of increasing the amount of gas is saturated, and the gas passage resistance is increased. For this reason, the coat layer amount is
The amount is preferably 50 g to 400 g per liter of the catalyst.
【0037】[0037]
【作用】請求項1記載の排気ガス浄化用触媒は、Pt
と、PdとRhのうち少なくとも1種を含み、Ptが2
種のZr複合酸化物に担持された状態で用いることによ
り、未浄化HC成分中の安定で燃焼しにくいパラフィン
を選択的に浄化可能なA/Fレンジが広くなり、より安
定な活性を発現できる。更にその相乗効果としてストイ
キから少しリーン雰囲気でのNOx 浄化も向上する。こ
れは、2種のZr複合酸化物上のPt表面状態が、リッ
チ、リーンの各雰囲気でパラフィン吸着に適した表面
(酸化)状態に制御できるからである。The exhaust gas purifying catalyst according to claim 1 is a Pt catalyst.
And at least one of Pd and Rh, wherein Pt is 2
When used in a state of being supported on a kind of Zr composite oxide, the A / F range capable of selectively purifying stable and hardly combustible paraffin in the unpurified HC component is widened, and more stable activity can be exhibited. . Further, as a synergistic effect, NO x purification in a slightly lean atmosphere from stoichiometric conditions is improved. This is because the Pt surface state on the two kinds of Zr composite oxides can be controlled to a surface (oxidized) state suitable for paraffin adsorption in rich and lean atmospheres.
【0038】更に、請求項2記載の排気ガス浄化用触媒
は、Pt量を1g/L〜15g/Lとして、更にZr複
合酸化物へのPt担持量を全Pt量の10wt%以上に
制限することで、上記組合せ効果をより有効に発現させ
ることができる。Furthermore, in the exhaust gas purifying catalyst according to the second aspect, the amount of Pt is set to 1 g / L to 15 g / L, and the amount of Pt carried on the Zr composite oxide is limited to 10 wt% or more of the total Pt amount. Thereby, the above-mentioned combination effect can be more effectively exhibited.
【0039】また、請求項3記載の排気ガス浄化用触媒
は前述したPt担持に使用されるZr複合酸化物触媒の
添加元素量を1〜40モル%として用いている。これは
Zr酸化物が添加元素によって安定化され、前述したP
t状態を保つのに適するからである。The exhaust gas purifying catalyst according to the third aspect uses the Zr composite oxide catalyst used for supporting Pt in an amount of 1 to 40 mol%. This is because the Zr oxide is stabilized by the added element,
This is because it is suitable for maintaining the t state.
【0040】請求項4記載の排気ガス浄化用触媒は、請
求項1ないし3記載の排気ガス浄化用触媒において、2
種のZr複合酸化物触媒の比率を10〜90wt%に限
定することでストイキ近傍でのパラフィン活性とNOx
活性をバランス良く発現することができる。The exhaust gas purifying catalyst according to the fourth aspect is the exhaust gas purifying catalyst according to the first to third aspects.
The paraffin activity near stoichiometry and NO x
The activity can be expressed in a well-balanced manner.
【0041】請求項5記載の排気ガス浄化用触媒は、請
求項1ないし4項記載の排気ガス浄化用触媒において、
更にZr複合酸化物の結晶構造を制限している。添加元
素が固溶し安定化されたZr酸化物は正方晶をとり、単
斜晶への相変化を抑制することが知られており、一層高
温耐久性が向上する。The exhaust gas purifying catalyst according to the fifth aspect is the exhaust gas purifying catalyst according to the first to fourth aspects,
Further, it limits the crystal structure of the Zr composite oxide. It is known that the stabilized Zr oxide in which the additive element is dissolved forms a tetragonal system and suppresses a phase change to a monoclinic system, and the high-temperature durability is further improved.
【0042】請求項6記載の排気ガス浄化用触媒は、更
に請求項1ないし5記載の排気ガス浄化用触媒におい
て、更に、酸素吸放出能を有するCe複合酸化物を含有
させている。これは急激なA/F変動に対し、活性主成
分である貴金属表面を浄化に最適な状態にする働きを持
たせるためである。The exhaust gas purifying catalyst according to a sixth aspect of the present invention is the exhaust gas purifying catalyst according to the first to fifth aspects, further comprising a Ce composite oxide having an oxygen absorbing / releasing ability. This is to provide the function of bringing the surface of the noble metal, which is the active main component, into an optimum state for purification against a sudden A / F fluctuation.
【0043】請求項7記載の排気ガス浄化用触媒は、触
媒活性成分の中のPdとPtが同一触媒層に共存しない
構造とするものである。これは、前述したPt担持Zr
複合酸化物の効果が、Pd共存によりPtと密に接触し
活性な表面状態が変化することを防ぐためである。The exhaust gas purifying catalyst according to claim 7 has a structure in which Pd and Pt in the catalytically active components do not coexist in the same catalyst layer. This is due to the aforementioned Pt-supported Zr
This is because the effect of the composite oxide prevents the active surface state from changing due to the close contact with Pt due to the coexistence of Pd.
【0044】[0044]
【実施例】本発明を次の実施例及び比較例により具体的
に説明するが、本発明の趣旨に反しない限り、これらの
実施例に限定されるものではない。The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which are not intended to limit the scope of the present invention.
【0045】<実施例1>Nd−Zr複合酸化物{Nd
=0.2%(原子比)}粉末にジニトロジアンミン白金
水溶液を含浸し、150℃で12時間乾燥した後、40
0℃で1時間焼成して、Pt担持Nd−ZrO2 粉末
(粉末A)を得た。この粉末のPt濃度は2.0wt%
であった。Ce−Zr複合酸化物{Ce=0.2%(原
子比})粉末にジニトロジアンミン白金水溶液を含浸
し、150℃で12時間乾燥した後、400℃で1時間
焼成して、Pt担持Ce−ZrO2 粉末(粉末B)を得
た。この粉末のPt濃度は2.0wt%であった。上記
粉末A100g、粉末B100gと、ランタン1%(原
子比)(La2 O3 に換算して2wt%)とジルコニウ
ム32%(原子比)(ZrO2 に換算して25wt%)
を含むセリウム酸化物(La0.01Zr0.32Ce0.67O
x )粉末50gと硝酸水溶液250gを磁性ボールミル
に投入し、混合・粉砕してスラリーを得た。このスラリ
ー液をコージェライト質モノリス担体(1.7L、40
0セル/平方インチ)に付着させ、空気流にてセル内の
余剰のスラリーを除去・乾燥し、500℃で1時間焼成
した。コート量重量50g/L−担体の触媒Aを得た。
白金担持量は2.37g/L(67g/cf)であっ
た。<Example 1> Nd-Zr composite oxide {Nd
= 0.2% (atomic ratio)} The powder was impregnated with an aqueous solution of dinitrodiammine platinum, dried at 150 ° C. for 12 hours,
By baking at 0 ° C. for 1 hour, a Pt-supported Nd—ZrO 2 powder (powder A) was obtained. The Pt concentration of this powder is 2.0 wt%
Met. A Ce-Zr composite oxide {Ce = 0.2% (atomic ratio)) powder is impregnated with an aqueous solution of dinitrodiammine platinum, dried at 150 ° C for 12 hours, and calcined at 400 ° C for 1 hour to obtain Pt-supported Ce— A ZrO 2 powder (powder B) was obtained. The Pt concentration of this powder was 2.0% by weight. 100 g of powder A and 100 g of powder B, 1% (atomic ratio) of lanthanum ( 2 wt% in terms of La 2 O 3 ) and 32% (atomic ratio) of zirconium (25 wt% in terms of ZrO 2 )
Oxide containing cerium (La 0.01 Zr 0.32 Ce 0.67 O
x ) 50 g of powder and 250 g of nitric acid aqueous solution were charged into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was applied to a cordierite monolithic carrier (1.7 L, 40 L).
(0 cells / square inch), excess slurry in the cells was removed by air flow, dried, and fired at 500 ° C. for 1 hour. A catalyst A having a coating weight of 50 g / L-carrier was obtained.
The platinum carrying amount was 2.37 g / L (67 g / cf).
【0046】Ce−Zr複合酸化物{Ce=0.2%
(原子比)}粉末に硝酸ロジウム水溶液を含浸し、15
0℃で12時間乾燥した後、400℃で1時間焼成し
て、Rh担持Ce−ZrO2 粉末(粉末C)を得た。こ
の粉末CのRh濃度は1.0wt%であった。上記粉末
C195gとべーマイトアルミナ5gと硝酸水溶液30
0gを磁性ボールミルに投入し、混合・粉砕してスラリ
ーを得た。このスラリー液を先ほどの触媒Aに更に付着
させ、空気流にてセル内の余剰のスラリーを除去・乾燥
し、400℃で1時間焼成した。Rhスラリー50g/
L、コート層総重量200g/L−担体の触媒Bを得
た。Rhの担持量は0.47g/L(13g/cf)、
Pt/Rh比は5/1であった。Ce—Zr composite oxide {Ce = 0.2%
(Atomic ratio)} Impregnate the powder with rhodium nitrate aqueous solution
After drying at 0 ° C. for 12 hours, baking was performed at 400 ° C. for 1 hour to obtain a Rh-supporting Ce—ZrO 2 powder (powder C). The Rh concentration of this powder C was 1.0 wt%. 195 g of the above powder C, 5 g of boehmite alumina, and 30 of nitric acid aqueous solution
0 g was charged into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was further adhered to the catalyst A, and the excess slurry in the cell was removed by an air flow, dried, and calcined at 400 ° C. for 1 hour. Rh slurry 50g /
L, a catalyst B having a total weight of the coat layer of 200 g / L-carrier was obtained. Rh carrying amount is 0.47 g / L (13 g / cf),
The Pt / Rh ratio was 5/1.
【0047】<実施例2>実施例1の触媒Bにおいて、
Nd−ZrO2 の代わりにY−ZrO2 (Y=0.2モ
ル%)を用いた以外は、実施例1と同様にして排気ガス
浄化用触媒を得た。<Example 2> In the catalyst B of Example 1,
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1, except that Y-ZrO 2 (Y = 0.2 mol%) was used instead of Nd-ZrO 2 .
【0048】<実施例3>実施例1の触媒Bにおいて、
Nd−ZrO2 の代わりにCa−ZrO2 (Ca=0.
2モル%)を用いた以外は、実施例1と同様にして排気
ガス浄化用触媒を得た。<Example 3> In the catalyst B of Example 1,
Ca-ZrO 2 (Ca = 0 instead of Nd-ZrO 2.
Except for using 2 mol%), an exhaust gas purifying catalyst was obtained in the same manner as in Example 1.
【0049】<実施例4>実施例1の触媒Bにおいて、
Ce−ZrO2 の代わりにW−ZrO2 (W=0.2モ
ル%)を用いた以外は、実施例1と同様にして排気ガス
浄化用触媒を得た。Example 4 In the catalyst B of Example 1,
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1, except that W-ZrO 2 (W = 0.2 mol%) was used instead of Ce-ZrO 2 .
【0050】<実施例5>実施例1の触媒Bにおいて、
Ce−ZrO2 の代わりにAl−ZrO2 (Al=0.
2モル%)を用いた以外は、実施例1と同様にして排気
ガス浄化用触媒を得た。<Example 5> In the catalyst B of Example 1,
Al-ZrO 2 (Al = 0 instead of Ce-ZrO 2.
Except for using 2 mol%), an exhaust gas purifying catalyst was obtained in the same manner as in Example 1.
【0051】<実施例6>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 とCe−ZrO2 の
重量比をNd−ZrO2 が30%、Ce−ZrO2 が7
0%になるように変更した以外は、実施例1と同様にし
て排気ガス浄化用触媒を得た。<Example 6> In the catalyst B of Example 1,
Pt supported substrate Nd-ZrO 2 and the weight ratio of Ce-ZrO 2 is a Nd-ZrO 2 is 30%, Ce-ZrO 2 is 7
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1, except that the catalyst was changed to 0%.
【0052】<実施例7>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 、Ce−ZrO2 か
ら全Pt量の50wt%を活性アルミナに置き換えた以
外は、実施例1と同様にして排気ガス浄化用触媒を得
た。<Example 7> In the catalyst B of Example 1,
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1, except that 50 wt% of the total Pt amount was replaced with activated alumina from Nd-ZrO 2 and Ce-ZrO 2 which are Pt-supported substrates.
【0053】<実施例8>実施例1の触媒Bにおいて、
Pt、Rh担持層の下層に更にPd担持層(Pd担持基
材は活性アルミナ、Pd2.83g/L、コート量50
g/L)を追加したこと以外は実施例1と同様にして排
気ガス浄化用触媒を得た。<Example 8> In the catalyst B of Example 1,
Under the Pt and Rh supporting layers, a Pd supporting layer (Pd supporting base material is activated alumina, Pd 2.83 g / L, coating amount 50)
g / L) was obtained in the same manner as in Example 1 except that g / L) was added.
【0054】<比較例1>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 、Ce−ZrO2 を
全て活性アルミナに置き換えた以外は、実施例1と同様
にして排気ガス浄化用触媒を得た。<Comparative Example 1> In the catalyst B of Example 1,
But replacing Nd-ZrO 2, Ce-ZrO 2 is Pt carrier substrates all activated alumina to obtain an exhaust gas purifying catalyst in the same manner as in Example 1.
【0055】<比較例2>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 、Ce−ZrO2 の
うち、全Pt量の95wt%を活性アルミナに置き換え
た以外は、実施例1と同様にして排気ガス浄化用触媒を
得た。<Comparative Example 2> In the catalyst B of Example 1,
Of Nd-ZrO 2, Ce-ZrO 2 is supported Pt substrate, except that the 95 wt% of the total amount of Pt was replaced with activated alumina to obtain an exhaust gas purifying catalyst in the same manner as in Example 1.
【0056】<比較例3>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 とCe−ZrO2 の
重量比をNd−ZrO2 が5%になるように変更した以
外は、実施例1と同様にして排気ガス浄化用触媒を得
た。<Comparative Example 3> In the catalyst B of Example 1,
The weight ratio of the Nd-ZrO 2 and Ce-ZrO 2 is supported Pt substrate Nd-ZrO 2, except for changing to be 5%, was obtained exhaust gas purifying catalyst in the same manner as in Example 1 .
【0057】<比較例4>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 とCe−ZrO2 の
重量比をCe−ZrO2 が5%になるように変更した以
外は、実施例1と同様にして排気ガス浄化用触媒を得
た。<Comparative Example 4> In the catalyst B of Example 1,
The weight ratio of the Nd-ZrO 2 and Ce-ZrO 2 is supported Pt substrate Ce-ZrO 2, except for changing to be 5%, was obtained exhaust gas purifying catalyst in the same manner as in Example 1 .
【0058】<比較例5>実施例1の触媒Bにおいて、
Pt担持基材であるNd−ZrO2 とCe−ZrO2 の
添加元素(Nd、Ce)の含有比を50モル%に変更し
た以外は、実施例1と同様にして排気ガス浄化用触媒を
得た。<Comparative Example 5> In the catalyst B of Example 1,
Additional element of Nd-ZrO 2 and Ce-ZrO 2 is a Pt carrying substrate (Nd, Ce) except for changing the content ratio of 50 mol%, to give the exhaust gas purifying catalyst in the same manner as in Example 1 Was.
【0059】<比較例6>実施例7の触媒において、P
t層にPd担持層(Pd担持基材は活性アルミナ、Pd
2.83g/L、コート量50g/L)を共存させた排
気ガス浄化用触媒を得た。<Comparative Example 6> In the catalyst of Example 7, P
A Pd-supporting layer (Pd-supporting substrate is activated alumina, Pd
(2.83 g / L, coating amount: 50 g / L) was obtained.
【0060】<試験例>前記実施例1〜8及び比較例1
〜6の排気ガス浄化用触媒について、モデルガスによる
触媒活性評価を行った。評価温度は350℃、ガス流量
40L/min.(SV=80,000h-1相当)とし
た。ガス組成は表1にまとめて示した。<Test Example> Examples 1 to 8 and Comparative Example 1
With respect to the exhaust gas purifying catalysts Nos. 1 to 6, the catalytic activity was evaluated using a model gas. The evaluation temperature was 350 ° C. and the gas flow rate was 40 L / min. (SV = 80,000h -1 ). The gas composition is shown in Table 1.
【0061】[0061]
【表1】 [Table 1]
【0062】上記実施例1〜8及び比較例1〜6で検討
された排気ガス浄化用触媒の貴金属担持量(触媒1L中
における白金、パラジウム、ロジウムの含有量)と担持
基材の種類と特徴、また、各評価条件(酸素過剰率)に
対する触媒活性評価結果を排気ガス浄化用触媒のHC及
びNOx 浄化性能としてその転化率(%)をそれぞれ表
2、表3にまとめて示した。The noble metal loading (content of platinum, palladium and rhodium in 1 liter of catalyst) of the exhaust gas purifying catalysts studied in the above Examples 1 to 8 and Comparative Examples 1 to 6 and the type and characteristics of the loading substrate in addition, the evaluation condition that conversion catalytic activity evaluation results of (oxygen excess) as HC and NO x purification performance of the exhaust gas purifying catalyst (%), respectively Table 2, are summarized in Table 3.
【0063】[0063]
【表2】 [Table 2]
【0064】[0064]
【表3】 [Table 3]
【0065】[0065]
【発明の効果】以上説明してきたように、本発明の排気
ガス浄化用触媒にあっては、今まで未浄化だったHC成
分に対して、ストイキを中心としてリッチからリーンの
より広い雰囲気条件下で高い浄化性能を達成することが
できる。As described above, in the exhaust gas purifying catalyst according to the present invention, the HC component which has not been purified so far can be subjected to a wider range of atmosphere conditions from rich to lean, mainly stoichiometric. And high purification performance can be achieved.
フロントページの続き Fターム(参考) 4G069 AA03 AA08 BA01B BA13B BB06A BB12B BC08A BC15A BC24A BC38A BC42A BC42B BC43A BC43B BC44A BC44B BC51A BC51B BC71A BC71B BC72A BC72B BC75A BC75B CA03 CA09 CA13 CA14 CA15 DA06 EA19 EC22X EC22Y EE09 FB13 FB30 Continued on the front page F term (reference) 4G069 AA03 AA08 BA01B BA13B BB06A BB12B BC08A BC15A BC24A BC38A BC42A BC42B BC43A BC43B BC44A BC44B BC51A BC51B BC71A BC71B BC72A BC72B BC75A BC75B CA03 CA09 CA13 CA19 EC13 CA19
Claims (7)
において、 触媒成分としてPtと、Pd、Rhから選ばれた少なく
とも1種を含有し、 更に、2A族元素と3B族(但しCeを除く)元素の中
から選ばれた少なくとも1種を含有するZr複合酸化物
(A)と、Ceと3A族と6B族元素の中から選ばれた
少なくとも1種を含有するZr複合酸化物(B)の2種
をPt担持基材として用いることを特徴とする排気ガス
浄化用触媒。1. A monolithic catalyst having a catalyst component-supporting layer, wherein the catalyst component contains at least one selected from the group consisting of Pt, Pd, and Rh, and further comprises a Group 2A element and a Group 3B element (except for Ce). A) a Zr composite oxide (A) containing at least one element selected from the elements, and a Zr composite oxide (B) containing at least one element selected from the group consisting of Ce, group 3A and group 6B. A catalyst for purifying exhaust gas, wherein two types of the above are used as a Pt-supporting substrate.
いて、 含有されるPt量は、1g/L〜15g/Lであり、Z
r複合酸化物へのPt担持量比率が触媒中の全Pt量の
少なくとも10wt%以上であることを特徴とする排気
ガス浄化用触媒。2. The exhaust gas purifying catalyst according to claim 1, wherein the amount of Pt contained is 1 g / L to 15 g / L.
An exhaust gas purifying catalyst, wherein the ratio of the amount of Pt carried to the r composite oxide is at least 10 wt% or more of the total amount of Pt in the catalyst.
いて、 更にPt担持基材に用いるZr複合酸化物の含有される
元素比率が、Zrに対する原子比にして1〜40%であ
ることを特徴とする排気ガス浄化用触媒。3. The exhaust gas purifying catalyst according to claim 1, wherein the element ratio of the Zr composite oxide used for the Pt-supporting substrate is 1 to 40% in atomic ratio with respect to Zr. A catalyst for purifying exhaust gas.
触媒において、 Pt担持基材に用いる2種のZr複合酸化物の含有され
る割合{A/(A+B)}が、10〜90wt%である
ことを特徴とする排気ガス浄化用触媒。4. The exhaust gas purifying catalyst according to claim 1, wherein the content ratio (A / (A + B)) of the two kinds of Zr composite oxides used for the Pt-supporting substrate is 10 to 90 wt%. An exhaust gas purifying catalyst characterized by the following.
触媒において、 2種のZr複合酸化物のX線回折で測定される結晶構造
が、積分強度にして、正方晶の比率が少なくとも10%
以上であることを特徴とする排気ガス浄化用触媒。5. The exhaust gas purifying catalyst according to claim 1, wherein the crystal structure of the two Zr composite oxides measured by X-ray diffraction has an integral intensity of at least 10% tetragonal. %
An exhaust gas purifying catalyst characterized by the above.
触媒において、 更に、ランタン、ネオジウム、ジルコニウムからなる群
より選ばれた少なくとも1種を、原子比にして1〜40
%含むセリウム酸化物が含有されることを特徴とする排
気ガス浄化用触媒。6. The exhaust gas purifying catalyst according to claim 1, wherein at least one selected from the group consisting of lanthanum, neodymium, and zirconium has an atomic ratio of 1 to 40.
% Of cerium oxide.
いて、 触媒活性成分であるPdが、Ptと同一触媒層に共存し
ない構造とすることを特徴とする排気ガス浄化用触媒。7. The exhaust gas purifying catalyst according to claim 1, wherein Pd, which is a catalytically active component, does not coexist with Pt in the same catalyst layer.
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