JP2014171971A - Exhaust gas purifying catalyst - Google Patents
Exhaust gas purifying catalyst Download PDFInfo
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- JP2014171971A JP2014171971A JP2013046638A JP2013046638A JP2014171971A JP 2014171971 A JP2014171971 A JP 2014171971A JP 2013046638 A JP2013046638 A JP 2013046638A JP 2013046638 A JP2013046638 A JP 2013046638A JP 2014171971 A JP2014171971 A JP 2014171971A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 176
- 229910052751 metal Inorganic materials 0.000 claims abstract description 63
- 239000002184 metal Substances 0.000 claims abstract description 58
- 239000000463 material Substances 0.000 claims abstract description 41
- 239000002245 particle Substances 0.000 claims abstract description 38
- 238000010438 heat treatment Methods 0.000 claims abstract description 24
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 14
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims abstract description 6
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000002485 combustion reaction Methods 0.000 claims description 11
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- 230000003647 oxidation Effects 0.000 claims description 5
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- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 13
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- 238000011068 loading method Methods 0.000 description 7
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- 229910052772 Samarium Inorganic materials 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
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- -1 alumina (Al 2 O 3 ) Chemical class 0.000 description 2
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- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 2
- 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 2
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- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 230000010718 Oxidation Activity Effects 0.000 description 1
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- 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
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- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Abstract
Description
本発明は、内燃機関の排気系に設けられる排ガス浄化用触媒に関する。詳しくは、触媒金属を担持する担体に関する。 The present invention relates to an exhaust gas purifying catalyst provided in an exhaust system of an internal combustion engine. In detail, it is related with the support | carrier which carries a catalyst metal.
自動車エンジン等の内燃機関の排ガスに含まれる一酸化炭素（ＣＯ）、炭化水素（ＨＣ）、窒素酸化物（ＮＯｘ）等の有害成分を効率よく除去するために、ＣＯ、ＨＣの酸化とＮＯｘの還元とを同時に行うことができるいわゆる三元触媒が利用されている。
かかる三元触媒としては、アルミナ（Ａｌ２Ｏ３）等の金属酸化物からなる多孔質担体に、白金（Ｐｔ）、ロジウム（Ｒｈ）、パラジウム（Ｐｄ）等の白金族に属する貴金属（ＰＧＭ）を担持させたものが利用されている。このような複数種のＰＧＭからなる触媒金属を備える三元触媒は、理論空燃比（ストイキ：Ａ／Ｆ＝１４．７）近傍の混合気が内燃機関で燃焼して生じる排ガスに対して特に高い排ガス浄化触媒機能を発揮し得る。
In order to efficiently remove harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO x ) contained in the exhaust gas of internal combustion engines such as automobile engines, CO and HC oxidation and NO A so-called three-way catalyst that can simultaneously reduce x is used.
As such a three-way catalyst, a porous support made of a metal oxide such as alumina (Al 2 O 3 ), a noble metal (PGM) belonging to a platinum group such as platinum (Pt), rhodium (Rh), and palladium (Pd). The thing which carried | supported is used. Such a three-way catalyst including a catalytic metal composed of a plurality of types of PGMs is particularly high with respect to exhaust gas generated by combustion of an air-fuel mixture near the stoichiometric air-fuel ratio (Stoichi: A / F = 14.7) in an internal combustion engine. Exhaust gas purification catalyst function can be exhibited.
しかし、実際に内燃機関を使用する場合（典型的には自動車を運転する場合）に供給される混合気の空燃比をストイキ近傍に維持し続けることは難しく、例えば自動車の走行条件などによって混合気の空燃比が燃料過剰（リッチ：Ａ／Ｆ＜１４．７）になったり、酸素過剰（リーン：Ａ／Ｆ＞１４．７）になったりする。そこで、近年、酸素吸蔵放出能（ＯＳＣ：Oxygen Storage Capacity）を有する無機材料、即ちＯＳＣ材を担体に含ませることが一般化している。
三元触媒では、ＯＳＣ材として、セリア（ＣｅＯ２）とジルコニア（ＺｒＯ２）を主体とする複合酸化物（以下「ＣＺ複合酸化物」ともいう。）が従来から使用されている。例えば下記特許文献１には、セリウム酸化物に対するジルコニウム酸化物の固溶度が５０％以上であるＣＺ複合酸化物であって該ＣＺ複合酸化物の粒子を構成する結晶子の平均径が１００ｎｍ以下であることを特徴とするＣＺ複合酸化物から成るＯＳＣ材を備えた従来の排ガス浄化用触媒の一例が開示されている。また、下記特許文献２には、ＯＳＣ材として使用されるＣＺ複合酸化物であって結晶子径が１０ｎｍ程度のＣＺ複合酸化物粒子の製造方法が紹介されている。
However, it is difficult to keep the air-fuel ratio of the air-fuel mixture supplied in the case of actually using an internal combustion engine (typically when driving an automobile) in the vicinity of the stoichiometric condition. The air / fuel ratio of the fuel becomes excessive (rich: A / F <14.7) or excessive oxygen (lean: A / F> 14.7). Therefore, in recent years, it has become common to include an inorganic material having an oxygen storage capacity (OSC: Oxygen Storage Capacity), that is, an OSC material in a carrier.
In the three-way catalyst, a complex oxide (hereinafter also referred to as “CZ complex oxide”) mainly composed of ceria (CeO 2 ) and zirconia (ZrO 2 ) has been conventionally used as the OSC material. For example, Patent Document 1 below discloses a CZ composite oxide in which the solubility of zirconium oxide in cerium oxide is 50% or more, and the average diameter of crystallites constituting the particles of the CZ composite oxide is 100 nm or less. An example of a conventional exhaust gas purifying catalyst provided with an OSC material made of a CZ composite oxide characterized by the above is disclosed. Patent Document 2 listed below introduces a method for producing CZ composite oxide particles, which are CZ composite oxides used as OSC materials and have a crystallite diameter of about 10 nm.
ところで、かかるＯＳＣ材として用いられるＣＺ複合酸化物の弱点の一つとして耐熱性の低さが挙げられる。即ち、従来のＣＺ複合酸化物から成る粒子（一次粒子）では、該粒子を構成する結晶子の結晶成長が高温時（例えば耐久試験時）に起こり易く、それに伴って該ＣＺ複合酸化物から成るＯＳＣ材に担持された触媒金属の凝集も進行し、結果、活性点の減少を招く虞がある。
そこで、ＯＳＣ材として用いられるＣＺ複合酸化物の耐熱性を向上させること、より具体的には、ＣＺ複合酸化物粒子を構成する結晶子の結晶成長を抑制し、触媒金属の凝集及びＯＳＣ機能の低下を抑制し得る耐熱性の向上が求められている。
本発明は、かかるＯＳＣ材に関する上記課題を解決するために創出されたものであり、その主な目的は、結晶子の結晶成長を抑制して触媒金属の凝集及びＯＳＣ機能の低下を抑制し得る耐熱性を具備するＯＳＣ材の提供、ならびに該ＯＳＣ材を備える排ガス浄化用触媒を提供することである。
Incidentally, one of the weak points of the CZ composite oxide used as the OSC material is low heat resistance. That is, in the particles (primary particles) made of the conventional CZ composite oxide, crystal growth of the crystallites constituting the particles is likely to occur at a high temperature (for example, during an endurance test), and accordingly, the particles are made of the CZ composite oxide. Aggregation of the catalytic metal supported on the OSC material also proceeds, and as a result, there is a risk of reducing the active sites.
Therefore, improving the heat resistance of the CZ composite oxide used as the OSC material, more specifically, suppressing the crystal growth of the crystallites constituting the CZ composite oxide particles, agglomeration of the catalytic metal and the OSC function. There is a demand for improvement in heat resistance that can suppress the decrease.
The present invention has been created in order to solve the above-described problems related to the OSC material, and the main object of the present invention is to suppress the crystal growth of the crystallites to suppress the aggregation of the catalytic metal and the deterioration of the OSC function. An object of the present invention is to provide an OSC material having heat resistance, and to provide an exhaust gas purifying catalyst comprising the OSC material.
上記目的を実現するべく、ここで開示される排ガス浄化用触媒は、内燃機関の排気管に配置されて該内燃機関から排出される排ガスの浄化を行う排ガス浄化用触媒であって、酸化触媒及び／又は還元触媒として機能する触媒金属と該金属を担持する担体とを備えている。
そして上記担体として、ＯＳＣ材として機能する酸化物から成る担体を備えており、該担体は、以下の２種の結晶子、即ち、
ジルコニウム（Ｚｒ）及びセリウム（Ｃｅ）のうちの少なくとも一方を含む酸化物から成る結晶子Ａと、
ジルコニウム（Ｚｒ）及びセリウム（Ｃｅ）のうちの少なくとも一方を含む酸化物から成る結晶子Ｂであって、該酸化物中のＺｒ及び／又はＣｅの含有率（ｍｏｌ％）が前記結晶子Ａの酸化物中の含有率（ｍｏｌ％）とは異なる結晶子Ｂ、
とが混在した酸化物粒子から構成されていることを特徴とする。
In order to achieve the above object, an exhaust gas purification catalyst disclosed herein is an exhaust gas purification catalyst that is disposed in an exhaust pipe of an internal combustion engine and purifies exhaust gas discharged from the internal combustion engine, comprising an oxidation catalyst and The catalyst metal which functions as a reduction catalyst and / or the support | carrier which carry | supports this metal are provided.
The carrier includes an oxide that functions as an OSC material, and the carrier includes the following two types of crystallites, that is,
A crystallite A composed of an oxide containing at least one of zirconium (Zr) and cerium (Ce);
A crystallite B made of an oxide containing at least one of zirconium (Zr) and cerium (Ce), wherein the content (mol%) of Zr and / or Ce in the oxide is that of the crystallite A. Crystallite B different from the content (mol%) in the oxide,
It is characterized by being composed of oxide particles mixed with.
本発明者は、従来から使用されているＯＳＣ材（典型的にはＣＺ複合酸化物）を構成する結晶子に着目した。即ち、従来のＣＺ複合酸化物から成るＯＳＣ材の一次粒子は、通常、単一の構成の結晶子から成る集合体（凝集体）であり、このことが熱耐久試験のような高温に晒された際の焼結による結晶成長を助長する大きな要因であることに着目した。そして、相互に結晶構造が異なる（より具体的には格子定数が異なる）２種の結晶子を混在させることにより、異種結晶子同士が障壁となって結晶成長が阻まれることを見出し、本発明の創出に至った。
即ち、ここで開示される上記構成の排ガス浄化用触媒は、担体（ＯＳＣ材）として上記結晶子Ａ及び結晶子Ｂが混在して成る酸化物粒子からなるものを含むことにより、熱耐久試験のような高温条件下での使用時にも結晶成長を抑制し、該酸化物粒子（ＯＳＣ担体）に担持されるＰＧＭから成る触媒金属の凝集ならびにＯＳＣ機能の低下を抑制し、高性能（例えば三元触媒の三元性能）を安定して維持することができる。
好ましくは、ここで開示される排ガス浄化用触媒は、上記担体を構成する酸化物粒子の１１５０℃、５時間の大気中での熱処理後における比表面積が３５ｍ２／ｇ以上であることを特徴とする。高温条件下での使用時にも結晶成長を抑制し得るため、かかる高比表面積を維持することができ、高い触媒能（典型的には三元性能）を維持することができる。
The inventor paid attention to a crystallite constituting an OSC material (typically, a CZ composite oxide) that has been conventionally used. That is, the primary particles of an OSC material made of a conventional CZ composite oxide are usually aggregates (aggregates) made of crystallites having a single structure, and this is exposed to a high temperature such as a thermal endurance test. We paid attention to the fact that it is a major factor for promoting crystal growth by sintering. Then, by mixing two kinds of crystallites having crystal structures different from each other (more specifically, having different lattice constants), it has been found that different crystallites serve as a barrier to prevent crystal growth. Has led to the creation of
That is, the exhaust gas purifying catalyst having the above-described configuration disclosed herein includes a catalyst (OSC material) made of oxide particles in which the crystallite A and the crystallite B are mixed. It suppresses crystal growth even when used under such high temperature conditions, suppresses aggregation of catalytic metal composed of PGM supported on the oxide particles (OSC support) and lowers OSC function, and provides high performance (for example, ternary). The three-way performance of the catalyst can be stably maintained.
Preferably, the exhaust gas-purifying catalyst disclosed herein is characterized in that a specific surface area of the oxide particles constituting the carrier after heat treatment in the atmosphere at 1150 ° C. for 5 hours is 35 m 2 / g or more. To do. Since crystal growth can be suppressed even when used under high temperature conditions, such a high specific surface area can be maintained, and high catalytic ability (typically ternary performance) can be maintained.
ここで開示される排ガス浄化用触媒の好ましい一態様では、上記結晶子Ａと結晶子Ｂとは、それぞれ、相互に異なる含有率でＺｒ及びＣｅの両方を含む酸化物から構成されていることを特徴とする。
このように、ＣｅとＺｒとを異なる含有割合で含む異種結晶子から構成されるＣＺ複合酸化物のＯＳＣ材は、高温条件下での使用時における結晶成長が抑制され、所望のＯＳＣ機能を安定的に維持することができる。
好ましくは、一方の結晶子（結晶子Ａ）を構成する酸化物に含まれるＺｒの含有率は酸化物換算で該酸化物全体の７５〜９９ｍｏｌ％であり、他方の結晶子（結晶子Ｂ）を構成する酸化物に含まれるＣｅの含有率は酸化物換算で該酸化物全体の２０〜９９ｍｏｌ％であることを特徴とする。
このようにＺｒ主体の結晶子とＣｅを高率に含有する結晶子とを混在させた酸化物粒子（ＣＺ複合酸化物粒子）からなる担体（ＯＳＣ材でもある）は、特に高い熱安定性即ち結晶成長抑制能とＯＳＣ機能を発揮させることができる。
In a preferred embodiment of the exhaust gas purifying catalyst disclosed herein, the crystallite A and the crystallite B are each composed of an oxide containing both Zr and Ce at different contents. Features.
As described above, the OSC material of the CZ composite oxide composed of different crystallites containing Ce and Zr in different content ratios suppresses crystal growth during use under high temperature conditions and stabilizes the desired OSC function. Can be maintained.
Preferably, the content of Zr contained in the oxide constituting one crystallite (crystallite A) is 75 to 99 mol% of the whole oxide in terms of oxide, and the other crystallite (crystallite B) The content of Ce contained in the oxide constituting the metal oxide is 20 to 99 mol% of the whole oxide in terms of oxide.
Thus, the carrier (also an OSC material) composed of oxide particles (CZ composite oxide particles) in which crystallites mainly composed of Zr and crystallites containing Ce at a high rate are mixed has particularly high thermal stability, The ability to suppress crystal growth and the OSC function can be exhibited.
また、ここで開示される排ガス浄化用触媒の好ましい他の一態様では、結晶子Ａ及び結晶子Ｂのうち何れか一方の結晶子は、Ｚｒとともにイットリウム（Ｙ）を含む酸化物から成り、他方の結晶子は、Ｃｅとともにランタン（Ｌａ）を含む酸化物から成ることを特徴とする。
これら金属成分をそれぞれ含む異種結晶子が混在して成る酸化物粒子によると、より高い熱安定性（結晶成長抑制能）を発揮させることができる。
In another preferred embodiment of the exhaust gas purifying catalyst disclosed herein, one of the crystallites A and B is made of an oxide containing yttrium (Y) together with Zr, These crystallites are characterized by comprising an oxide containing lanthanum (La) together with Ce.
According to oxide particles formed by mixing different kinds of crystallites each containing these metal components, higher thermal stability (crystal growth suppressing ability) can be exhibited.
また、ここで開示される排ガス浄化用触媒の好ましい他の一態様では、結晶子Ａ及び結晶子Ｂは、高度に分散した状態、典型的には電子顕微鏡観察下でＡ及びＢのいずれについても同種の結晶子が７個以上互いに接して存在しないように高度に分散した状態で担体を構成する酸化物粒子中に混在していることを特徴とする。
ここで「同種の結晶子が７個以上互いに接して存在しない」とは、電子顕微鏡観察（典型的にはＴＥＭ像）において任意に選択した一つの結晶子からみてその周囲に存在する他の結晶子のうち、最も近い位置にある６個が全て同種の結晶子とはならない、換言すれば、電子顕微鏡観察（典型的にはＴＥＭ像）において７個以上の同種の結晶子が偏って存在せず、相互に近接する７個の結晶子を電子顕微鏡観察下で任意にピックアップしたとき、そのうちの少なくとも１個は他の６個の結晶子とは異なる種類の結晶子となる程度の高度な分散状態にあることをいう。電子顕微鏡観察を複数の視野（例えば異なるＴＥＭ画像）において行う場合は、各視野における平均値をいう。
このような高度な分散状態を維持した酸化物粒子では、特に高い熱安定性（結晶成長抑制能）を発揮させることができる。さらに同種の結晶子が６個以上互いに接して存在しない分散状態が特に好ましい。
In another preferred embodiment of the exhaust gas purifying catalyst disclosed herein, the crystallite A and the crystallite B are in a highly dispersed state, typically both of A and B under observation with an electron microscope. It is characterized by being mixed in oxide particles constituting the carrier in a highly dispersed state so that seven or more of the same kind of crystallites do not exist in contact with each other.
Here, “seven or more of the same kind of crystallites do not exist in contact with each other” means that other crystals existing around the crystallites selected from one crystallite arbitrarily selected in an electron microscope observation (typically a TEM image). Of the children, the closest six of them are not the same kind of crystallites, in other words, seven or more of the same kind of crystallites are unevenly present in an electron microscope observation (typically a TEM image). First, when seven crystallites close to each other are arbitrarily picked up under an electron microscope, at least one of them is highly dispersed so that it becomes a different type of crystallite from the other six crystallites. It means being in a state. When electron microscope observation is performed in a plurality of visual fields (for example, different TEM images), the average value in each visual field is referred to.
Oxide particles that maintain such a highly dispersed state can exhibit particularly high thermal stability (crystal growth suppression ability). Further, a dispersed state in which 6 or more of the same kind of crystallites are not in contact with each other is particularly preferable.
以下、図面を参照しつつ本発明の好適ないくつかの実施形態を説明する。なお、本明細書において特に言及している事項以外の事柄であって本発明の実施に必要な事柄は、当該分野における従来技術に基づく当業者の設計事項として把握され得る。本発明は、本明細書に開示されている内容と当該分野における技術知識とに基づいて実施することができる。 Several preferred embodiments of the present invention will be described below with reference to the drawings. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be implemented based on the contents disclosed in the present specification and technical knowledge in the field.
本明細書において「結晶子」とは、一連の連続した結晶格子から成り、単結晶とみなせる基本構造の最大の集まり（粒子）をいう。結晶子の性状は、例えばＸＲＤ（Ｘ線回折）測定を行い、リートベルト解析等を行うことにより調べることができる。また、結晶子の存在状態は、電子顕微鏡（典型的にはＴＥＭ）観察によって明らかにすることができる。また、電子顕微鏡観察とＥＤＸ（エネルギー分散型Ｘ線分光法）を組み合わせて行うことにより（例えばＴＥＭ−ＥＤＸ）、対象とする結晶子の元素分析や組成分析を行うことができる。 In this specification, “crystallite” refers to the largest group (particles) of a basic structure that consists of a series of continuous crystal lattices and can be regarded as a single crystal. The properties of the crystallites can be examined by performing, for example, XRD (X-ray diffraction) measurement and Rietveld analysis. Further, the existence state of the crystallite can be clarified by observation with an electron microscope (typically, TEM). In addition, elemental analysis and composition analysis of a target crystallite can be performed by combining electron microscope observation and EDX (energy dispersive X-ray spectroscopy) (for example, TEM-EDX).
ここで開示される排ガス浄化用触媒は、ＯＳＣ機能を有する担体として上述した２つの異種結晶子（Ａ及びＢ）が混在（分散）した状態で構成される酸化物粒子を触媒層の少なくとも一部に備えられていることで特徴付けられる排ガス浄化用触媒であり、その他の構成は特に限定されない。典型的には、三元触媒として内燃機関の排気管に配置される排ガス浄化用触媒として用いられ、基材と、該基材上に形成された触媒層であって酸化触媒及び／又は還元触媒として機能する触媒金属と該金属を担持する担体とを含む触媒層とを備える。
ここで開示される排ガス浄化用触媒は、後述する触媒金属、担体、基材の種類を適宜選択し、用途に応じて所望する形状に成形することによって種々の内燃機関、特に自動車のガソリンエンジンの排気系（排気管）に配置することができる。
以下の説明では、主として本発明の排ガス浄化用触媒を自動車のガソリンエンジンの排気管に設けられる三元触媒に適用することを前提として説明しているが、ここで開示される排ガス浄化用触媒を以下に説明する実施形態に限定することを意図したものではない。
The exhaust gas-purifying catalyst disclosed herein comprises at least a part of a catalyst layer containing oxide particles composed of the above-mentioned two different crystallites (A and B) mixed (dispersed) as a carrier having an OSC function. The catalyst for exhaust gas purification characterized by being provided in the above, and other configurations are not particularly limited. Typically, the catalyst is used as an exhaust gas purification catalyst disposed in an exhaust pipe of an internal combustion engine as a three-way catalyst, and is a base material and a catalyst layer formed on the base material, and is an oxidation catalyst and / or a reduction catalyst. And a catalyst layer including a catalyst metal that functions as a carrier and a carrier that supports the metal.
The exhaust gas-purifying catalyst disclosed herein can be selected from various types of catalytic metals, supports, and base materials, which will be described later, and formed into a desired shape according to the application, thereby being used for various internal combustion engines, particularly automobile gasoline engines. It can be arranged in an exhaust system (exhaust pipe).
In the following description, it is assumed that the exhaust gas purifying catalyst of the present invention is mainly applied to a three-way catalyst provided in the exhaust pipe of an automobile gasoline engine. It is not intended to be limited to the embodiments described below.
＜基材＞
ここで開示される排ガス浄化用触媒を排気管に設置する場合において触媒の骨格を構成する基材としては、従来この種の用途に用いられる種々の素材及び形態のものを採用することができる。例えば、高耐熱性を有するコージェライト、炭化ケイ素（ＳｉＣ）等のセラミックス、或いは合金（ステンレス鋼等）製の基材を使用することができる。
形状についても従来の排ガス浄化用触媒と同様でよい。一例として図１に示す排ガス浄化用触媒１０のように、外形が円筒形状であるハニカム基材１であって、その筒軸方向に排ガス流路としての貫通孔（セル）２が設けられ、各セル２を仕切る隔壁（リブ壁）４に排ガスが接触可能となっているものが挙げられる。基材１の形状はハニカム形状の他にフォーム形状、ペレット形状などとすることができる。また基材全体の外形については、円筒形に代えて楕円筒形、多角筒形を採用してもよい。
<Base material>
In the case where the exhaust gas purifying catalyst disclosed herein is installed in the exhaust pipe, various materials and forms conventionally used for this type of application can be adopted as the base material constituting the catalyst skeleton. For example, a cordierite having high heat resistance, a ceramic such as silicon carbide (SiC), or a base material made of an alloy (such as stainless steel) can be used.
The shape may be the same as that of a conventional exhaust gas purification catalyst. As an example, the exhaust gas purification catalyst 10 shown in FIG. 1 is a honeycomb substrate 1 having a cylindrical outer shape, and through holes (cells) 2 serving as exhaust gas passages are provided in the cylinder axis direction. The thing which exhaust gas can contact the partition (rib wall) 4 which divides the cell 2 is mentioned. The shape of the substrate 1 can be a foam shape, a pellet shape, or the like in addition to the honeycomb shape. Moreover, about the external shape of the whole base material, it may replace with a cylindrical shape and may employ | adopt an elliptical cylindrical shape and a polygonal cylindrical shape.
＜触媒層＞
基材上に形成される触媒層は、排ガスを浄化する場として、この種の排ガス浄化用触媒の主体をなすものであり、典型的には触媒金属粒子と、該触媒金属粒子を担持する担体とから構成される。例えば上述した図１に示すハニカム基材１を採用した場合には、当該基材１のセルを構成するリブ壁４上に所定の厚み、気孔率の触媒層が形成される。触媒層は全体がほぼ同一の構成の一層からなるものでもよく、或いは、基材１上に形成された相互に異なる上下二層若しくは三層以上を有する積層構造タイプの触媒層であってもよい。
<Catalyst layer>
The catalyst layer formed on the base material is the main component of this type of exhaust gas purifying catalyst as a place for purifying exhaust gas, and typically includes catalyst metal particles and a carrier supporting the catalyst metal particles. It consists of. For example, when the above-described honeycomb substrate 1 shown in FIG. 1 is employed, a catalyst layer having a predetermined thickness and porosity is formed on the rib walls 4 constituting the cells of the substrate 1. The catalyst layer as a whole may be composed of a single layer having substantially the same configuration, or may be a layered structure type catalyst layer formed on the substrate 1 and having two or more different upper and lower layers or three or more layers. .
＜触媒金属＞
ここで開示される排ガス浄化用触媒の触媒層に備えられる触媒金属は、種々の酸化触媒や還元触媒として機能し得る金属種が採用され得るが、典型的には、ＰＧＭであるロジウム（Ｒｈ）、白金（Ｐｔ）、パラジウム（Ｐｄ）等が挙げられる。ルテニウム（Ｒｕ）、オスミウム（Ｏｓ）、イリジウム（Ｉｒ）、銀（Ａｇ）、銅（Ｃｕ）等を使用してもよい。これら貴金属の２種以上が合金化したものを用いてもよい。或いは他の金属種を含むもの（典型的には合金）であってもよい。
この中で、還元活性が高いＲｈと、酸化活性が高いＰｄやＰｔとを組み合わせて用いることが三元触媒を構築するうえで特に好ましい。例えば、ここで開示される異種結晶子Ａ及びＢから成るＯＳＣ材には、Ｒｈ或いはＰｔ若しくはＰｄを担持させることが好ましい。
かかる触媒金属は、排ガスとの接触面積を高める観点から十分に小さい粒径の微粒子として使用されることが好ましい。典型的には上記金属粒子の平均粒径（ＴＥＭ観察により求められる粒径の平均値。以下同じ。）は１〜１５ｎｍ程度であり、１０ｎｍ以下、７ｎｍ以下、更には５ｎｍ以下であることが特に好ましい。
かかる貴金属の担持率（担体を１００質量％としたときの貴金属含有率）は、２質量％以下が好ましく、より好ましくは１．５質量％以下である。例えば、０．０５質量％以上２質量％以下であることが好ましく、０．１質量％以上１．５質量％以下であることがより好ましい。担持率が上記範囲より少なすぎると、金属による触媒効果が得られにくい。かかる担持率が上記範囲より多すぎると、金属の粒成長が進行する虞があり、さらにコスト面でも不利である。
<Catalyst metal>
As the catalyst metal provided in the catalyst layer of the exhaust gas purification catalyst disclosed herein, various metal species that can function as an oxidation catalyst or a reduction catalyst can be adopted. Typically, rhodium (Rh), which is PGM, is used. , Platinum (Pt), palladium (Pd), and the like. Ruthenium (Ru), osmium (Os), iridium (Ir), silver (Ag), copper (Cu), or the like may be used. An alloy of two or more of these noble metals may be used. Alternatively, it may be one containing other metal species (typically an alloy).
Among these, it is particularly preferable to use a combination of Rh having a high reduction activity and Pd or Pt having a high oxidation activity in order to construct a three-way catalyst. For example, it is preferable to support Rh, Pt, or Pd on the OSC material composed of the different crystallites A and B disclosed herein.
Such a catalyst metal is preferably used as fine particles having a sufficiently small particle diameter from the viewpoint of increasing the contact area with the exhaust gas. Typically, the average particle size of the metal particles (average value of particle sizes determined by TEM observation; the same shall apply hereinafter) is about 1 to 15 nm, particularly 10 nm or less, 7 nm or less, and more preferably 5 nm or less. preferable.
The precious metal loading rate (precious metal content when the carrier is 100% by mass) is preferably 2% by mass or less, and more preferably 1.5% by mass or less. For example, it is preferably 0.05% by mass or more and 2% by mass or less, and more preferably 0.1% by mass or more and 1.5% by mass or less. When the loading rate is too smaller than the above range, the catalytic effect of the metal is difficult to obtain. If the loading rate is too much higher than the above range, there is a risk that the metal grain growth proceeds, which is also disadvantageous in terms of cost.
＜担体＞
ここで開示される排ガス浄化用触媒の触媒層には、異種結晶子Ａ及びＢから成るＯＳＣ材以外にも１種又は２種以上の担体を備える。
好ましくは、比表面積（ＢＥＴ法により測定される比表面積をいう。以下同じ。）がある程度大きい無機化合物から成る多孔質担体が好適に用いられる。好適な担体としては、例えば、アルミナ（Ａｌ２Ｏ３）、セリア（ＣｅＯ２）、ジルコニア（ＺｒＯ２）、シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、及びそれらの固溶体（例えばセリア−ジルコニア複合酸化物（ＣＺ複合酸化物）、或いはそれらの組み合わせが挙げられる。
排ガス浄化用触媒の熱安定性を高めるという観点からは、耐熱性のよいアルミナ、ジルコニア等のセラミックスを担体若しくは非担持体（触媒金属を担持させていない触媒層の構成成分をいう。以下同じ。）として触媒層に含ませることが好ましい。
担体又は非担持体の粒子（例えばアルミナ粉末）としては、比表面積が３０ｍ２／ｇ以上であることが好ましい。アルミナ等の担体としては５０ｍ２／ｇ以上、例えば５０〜５００ｍ２／ｇ（例えば２００〜４００ｍ２／ｇ）であることが耐熱性、構造安定性の観点から好ましい。また、担体粒子の平均粒径は特に限定するものではないが、１ｎｍ以上５００ｎｍ以下（より好ましくは１０ｎｍ以上２００ｎｍ以下）程度であることが好ましい。
また、このような無機化合物（セラミックス）を担体として使用する場合、好ましくは触媒単位容積（１Ｌ）あたりの触媒金属含有量が０．１〜５ｇ／Ｌ程度が適当であり、０．２〜２ｇ／Ｌ程度が好ましい。触媒金属含有量が多すぎるとコスト的に好ましくなく、少なすぎると排ガス浄化能が低いために好ましくない。ここで触媒単位容積（１Ｌ）は、基材の純容積に加えて内部の空隙（セル）容積を含む（即ち当該空隙（セル）内に形成された触媒層を含む）嵩容積（１Ｌ）をいう。
<Carrier>
The catalyst layer of the exhaust gas purifying catalyst disclosed herein includes one or more carriers in addition to the OSC material composed of the different crystallites A and B.
Preferably, a porous carrier made of an inorganic compound having a specific surface area (referred to as a specific surface area measured by the BET method, hereinafter the same) is used to some extent. Suitable supports include, for example, alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ), silica (SiO 2 ), titania (TiO 2 ), and solid solutions thereof (eg, ceria-zirconia composites). An oxide (CZ composite oxide) or a combination thereof can be given.
From the viewpoint of enhancing the thermal stability of the exhaust gas purifying catalyst, ceramics such as alumina and zirconia with good heat resistance are supported or non-supported (components of the catalyst layer not supporting the catalyst metal. The same applies hereinafter. ) Is preferably included in the catalyst layer.
The carrier or non-supported particles (for example, alumina powder) preferably have a specific surface area of 30 m 2 / g or more. The carrier such as alumina 50 m 2 / g or more, for example 50 to 500 m 2 / g (e.g. 200 to 400 m 2 / g) is it heat resistance, from the viewpoint of structural stability. The average particle size of the carrier particles is not particularly limited, but is preferably about 1 nm to 500 nm (more preferably 10 nm to 200 nm).
Further, when such an inorganic compound (ceramics) is used as a carrier, it is preferable that the catalyst metal content per catalyst unit volume (1 L) is about 0.1 to 5 g / L, and 0.2 to 2 g. About / L is preferable. If the catalyst metal content is too high, it is not preferable in terms of cost, and if it is too low, the exhaust gas purification ability is low, which is not preferable. Here, the catalyst unit volume (1 L) includes the bulk volume (1 L) including the internal void volume (cell) volume (that is, including the catalyst layer formed in the void (cell)) in addition to the pure volume of the base material. Say.
＜ＯＳＣ材＞
異種結晶子Ａ及びＢから成るＯＳＣ材を触媒層における排ガス流動方向の上流側及び／又は下流側に備える。ここで開示される排ガス浄化用触媒の触媒層を構築するのに用いられるＯＳＣ材（担体としても用いられる。）は、上述した異種結晶子Ａ及びＢから成る酸化物粒子、具体的にはＺｒ及びＣｅのうちの少なくとも一方を含む酸化物から成る結晶子Ａと、Ｚｒ及びＣｅのうちの少なくとも一方を含む酸化物から成る結晶子Ｂであって該酸化物中のＺｒ及び／又はＣｅの含有率（ｍｏｌ％）が結晶子Ａの酸化物中の含有率（ｍｏｌ％）とは異なる結晶子Ｂとが混在して構成される酸化物粒子である。このような２種の結晶子を混在させることにより、例えば１１５０℃、５時間の大気中での熱処理後においても結晶成長を抑え、典型的には３５ｍ２／ｇ以上（特に好ましくは４０ｍ２／ｇ以上）であるような高い比表面積を維持することができる。
<OSC material>
An OSC material composed of different crystallites A and B is provided on the upstream side and / or the downstream side in the exhaust gas flow direction in the catalyst layer. The OSC material (also used as a carrier) used for constructing the catalyst layer of the exhaust gas purifying catalyst disclosed here is an oxide particle composed of the above-mentioned different crystallites A and B, specifically Zr. And a crystallite B made of an oxide containing at least one of Ce and Ce, and a crystallite B made of an oxide containing at least one of Zr and Ce, and the inclusion of Zr and / or Ce in the oxide The oxide particles are composed of crystallites B having a ratio (mol%) different from the content (mol%) of the crystallites A in the oxide. By mixing such two crystallites, for example 1150 ° C., even suppress crystal growth after heat treatment in air for 5 hours, typically 35m 2 / g or more (particularly preferably 40 m 2 / g) or higher) can be maintained.
結晶子Ａと結晶子Ｂとは相互に結晶構造が異なる、より具体的には相互に格子定数が異なることによって当該異種結晶子同士が障壁となり得て高温時の結晶成長が阻まれるように構成されていればよく、各結晶子の構成元素の種類や数に特に制限はない。
例えば、結晶子Ａ（Ａ、Ｂは区分のための記号にすぎない。）がＺｒを主体とするものである場合、その他の元素としてＣｅ、その他１種又は２種以上の希土類元素、例えば、イットリウム（Ｙ）、ランタン（Ｌａ）、ネオジム（Ｎｄ）、プラセオジム（Ｐｒ）、サマリウム（Ｓｍ）、ユウロピウム（Ｅｕ）等のうちの１種又は２種以上を含むものでもよい。例えばＺｒの含有率が酸化物換算で酸化物全体の７５〜９９ｍｏｌ％であるとともにＹを少量（例えば５ｍｏｌ％以下、或いは１０ｍｏｌ％以下）含む複合酸化物から成る結晶子Ａが好適な一例として挙げられる。
他方、結晶子ＢがＣｅを高率に含有するものである場合、その他の元素としてＺｒ、その他１種又は２種以上の希土類元素（Ｌａ、Ｙ、Ｎｄ、Ｐｒ、Ｓｍ、Ｅｕ等）を含むものでもよい。例えばＣｅの含有率が酸化物換算で酸化物全体の２０〜９９ｍｏｌ％であるとともにＬａを少量（例えば５ｍｏｌ％以下、或いは１０ｍｏｌ％以下）含む酸化物から成る結晶子Ｂが好ましい。
結晶子の平均サイズは、従来の排ガス浄化用触媒に使用されるＯＳＣ材（例えばＣＺ複合酸化物）を構成するものと同様でよく、典型的にはＴＥＭ等の電子顕微鏡観察において２〜１００ｎｍ、好ましくは５〜５０ｎｍ程度である。
The crystallite A and the crystallite B have different crystal structures, more specifically, different lattice constants from each other, so that the different crystallites can serve as a barrier to prevent crystal growth at high temperatures. There is no particular limitation on the type and number of constituent elements of each crystallite.
For example, when the crystallite A (A and B are only symbols for classification) is mainly composed of Zr, Ce as the other element, other one or more rare earth elements, for example, One or more of yttrium (Y), lanthanum (La), neodymium (Nd), praseodymium (Pr), samarium (Sm), europium (Eu) and the like may be included. For example, a preferred example is a crystallite A composed of a composite oxide having a Zr content of 75 to 99 mol% of the whole oxide in terms of oxide and containing a small amount of Y (for example, 5 mol% or less, or 10 mol% or less). It is done.
On the other hand, when the crystallite B contains Ce at a high rate, other elements include Zr and one or more rare earth elements (La, Y, Nd, Pr, Sm, Eu, etc.) as other elements. It may be a thing. For example, a crystallite B made of an oxide having a Ce content of 20 to 99 mol% in terms of oxide and containing a small amount of La (for example, 5 mol% or less, or 10 mol% or less) is preferable.
The average size of the crystallites may be the same as that constituting the OSC material (for example, CZ composite oxide) used in the conventional exhaust gas purification catalyst, and typically 2-100 nm in an electron microscope observation such as TEM. Preferably it is about 5-50 nm.
上述したような相互に結晶構造（格子定数）が異なる結晶子Ａ及び結晶子Ｂから成る酸化物粒子、即ち粉末状のＯＳＣ材は、予め結晶子Ａを構成する元素を含むように種々の化合物（典型的には構成金属元素を含む金属塩、例えばＺｒ、Ｃｅ、希土類元素それぞれの硝酸塩、アンモニウム塩、リン酸塩等の塩）から調製された前駆体（非焼成物）Ａと、同様に、予め結晶子Ｂを構成する元素を含むように種々の化合物（典型的には種々の金属塩）から調製された前駆体（非焼成物）Ｂとを、適当な酸化剤、例えば種々の有機酸や過酸化水素と共に混合して酸化条件下（典型的には大気中）で焼成することによって得ることができる。 The oxide particles composed of crystallite A and crystallite B having different crystal structures (lattice constants) as described above, that is, the powdered OSC material, includes various compounds so as to contain elements constituting crystallite A in advance. Similarly to a precursor (non-fired product) A prepared from (typically a metal salt containing a constituent metal element, such as a salt such as Zr, Ce, or a rare earth element nitrate, ammonium salt or phosphate) A precursor (non-fired product) B prepared from various compounds (typically various metal salts) so as to contain elements constituting crystallite B in advance, and an appropriate oxidizing agent such as various organic compounds It can be obtained by mixing with an acid or hydrogen peroxide and baking under oxidizing conditions (typically in the atmosphere).
上述したような構成の排ガス浄化用触媒は、従来と同様の製造プロセスによって製造することができる。
例えば、先ず、Ｐｄ、Ｐｔ、Ｒｈ等の触媒金属を担持した所望の担体粉末（アルミナ、ジルコニア等の一般的な担体、及び結晶子Ａ及びＢから成るＯＳＣ材、等）或いは非担持体（アルミナ、ジルコニア、或いは結晶子Ａ及びＢから成るＯＳＣ材を非担持体として用いてもよい。）粉末を含むスラリーを公知のウォッシュコート法等によってハニカム基材にコートする。その後、所定の温度及び時間で焼成することにより、基材上に触媒層を形成することができる。
なお、ウォッシュコート法を用いて触媒層を形成する場合、上記の手順に代えて担体（この段階では全てが非担持体）をウォッシュコート法によって予め基材上に形成しておき、その後に従来公知の含浸法等によって所望の触媒金属を担持させてもよい。
ウォッシュコートされたスラリーの焼成条件は基材または担体の形状及びサイズによって変動するので、特に限定しないが、典型的には４００〜１０００℃程度で約１〜４時間程度の焼成を行うことによって、目的の触媒層を形成することができる。なお、焼成前の乾燥条件については特に限定されるものではないが、８０〜３００℃の温度（例えば１５０〜２５０℃）で１〜１２時間程度の乾燥が好ましい。また、触媒層をこのようなウォッシュコート法により形成する場合、基材の表面、さらに積層構造触媒層の場合には下層の表面に上層形成用スラリーを好適に密着させるため、スラリーにはバインダーを含有させることが好ましい。かかる目的のバインダーとしては、例えばアルミナゾル、シリカゾル等の使用が好ましい。なお、スラリーの粘度は該スラリーが基材（例えばハニカム基材）のセル内へ容易に流入し得るように適宜調整するとよい。
The exhaust gas-purifying catalyst having the above-described configuration can be manufactured by a manufacturing process similar to the conventional one.
For example, first, a desired carrier powder carrying a catalytic metal such as Pd, Pt, Rh (a general carrier such as alumina or zirconia, and an OSC material composed of crystallites A and B, etc.) or a non-supported body (alumina , Zirconia, or OSC material composed of crystallites A and B may be used as a non-supported body.) A slurry containing powder is coated on a honeycomb substrate by a known wash coat method or the like. Thereafter, the catalyst layer can be formed on the substrate by firing at a predetermined temperature and time.
When forming the catalyst layer using the wash coat method, instead of the above procedure, a carrier (all unsupported bodies at this stage) is formed on the substrate in advance by the wash coat method, and thereafter A desired catalytic metal may be supported by a known impregnation method or the like.
The firing condition of the wash-coated slurry varies depending on the shape and size of the substrate or carrier, and is not particularly limited. Typically, by performing firing at about 400 to 1000 ° C. for about 1 to 4 hours, The target catalyst layer can be formed. In addition, although it does not specifically limit about the drying conditions before baking, The drying for about 1 to 12 hours is preferable at the temperature (for example, 150-250 degreeC) of 80-300 degreeC. Further, when the catalyst layer is formed by such a wash coat method, a binder is added to the slurry in order to suitably adhere the upper layer forming slurry to the surface of the base material, and in the case of a laminated catalyst layer, to the lower layer surface. It is preferable to contain. As such a binder, for example, use of alumina sol, silica sol or the like is preferable. Note that the viscosity of the slurry may be appropriately adjusted so that the slurry can easily flow into the cells of the substrate (for example, honeycomb substrate).
以下、本発明に関するいくつかの実施例につき説明するが、本発明をかかる具体例に示すものに限定することを意図したものではない。 Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the specific examples.
＜試験例１：排ガス浄化用触媒の製造＞
［実施例１］
イオン交換水７００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）３２．８８ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）３７６．７ｇ、硝酸ネオジム溶液（Ｎｄ２Ｏ３として１０質量％）３２．１４ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）１２．９４ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）１２．４５ｇ、ポリビニルピロリドン（ＰＶＰ Ｋ−３０（商品名））０．０５ｇを添加し、攪拌して混合溶液を調製した。
次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ１を得た。
<Test Example 1: Production of exhaust gas purification catalyst>
[Example 1]
In 700 mL of ion-exchanged water, 32.88 g of cerium nitrate solution (20% by mass as CeO 2 ), 376.7 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ), neodymium nitrate solution (10% by mass as Nd 2 O 3 ) 32.14 g, Yttrium nitrate solution (10% by mass as Y 2 O 3 ) 12.94 g, Lanthanum nitrate solution (10% by mass as La 2 O 3 ) 12.45 g, Polyvinylpyrrolidone (PVP K-30 (trade name)) 0.05 g was added and stirred to prepare a mixed solution.
Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a1.
一方、イオン交換水７００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）１６４．７ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）１１７．９ｇ、硝酸ネオジム溶液（Ｎｄ２Ｏ３として１０質量％）２６．８２ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）２５．９８ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。
次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ１を得た。
Meanwhile, 700 mL of ion-exchanged water, 164.7 g of cerium nitrate solution (20 mass% as CeO 2 ), 117.9 g of zirconium oxynitrate solution (10 mass% as ZrO 2 ), 10 mass of neodymium nitrate solution (Nd 2 O 3 as Nd 2 O 3 ) %) 26.82 g, lanthanum nitrate solution (10% by mass as La 2 O 3 ) 25.98 g, and PVP K-30 (trade name) 0.05 g were added and stirred to prepare a mixed solution.
Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b1.
イオン交換水１０００ｍＬに、上記前駆体ａ１及び前駆体ｂ１を全量添加し、さらに有機酸としてマロン酸１ｇと３％過酸化水素水１０ｇを添加して攪拌した。このようにして調製した混合スラリーを８０〜８５℃に加熱した後にホモジナイザーで６０分間の攪拌を行った。その後、濾過し、純水で洗浄した後に１１０℃で乾燥させ、大気中、８００℃で５時間の焼成を行うことにより粉末Ａ１Ｂ１を得た。得られた粉末Ａ１Ｂ１をＴＥＭ−ＥＤＸ測定（５万倍〜４０万倍、５０視野）に供し、粉末の性状を調べた。結果の一部を図２に示す。 All of the precursor a1 and precursor b1 were added to 1000 mL of ion-exchanged water, and 1 g of malonic acid and 10 g of 3% hydrogen peroxide were added as organic acids and stirred. The mixed slurry thus prepared was heated to 80 to 85 ° C. and then stirred for 60 minutes with a homogenizer. Then, after filtering and washing with pure water, it was dried at 110 ° C. and baked at 800 ° C. for 5 hours in the air to obtain a powder A1B1. The obtained powder A1B1 was subjected to TEM-EDX measurement (50,000 to 400,000 times, 50 visual fields), and the properties of the powder were examined. A part of the results is shown in FIG.
ＴＥＭ−ＥＤＸ測定結果から、本実施例１に係る粉末Ａ１Ｂ１は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｎｄ／Ｙ／Ｌａ＝８０／１０／５／３／２である結晶子Ａ１と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｎｄ／Ｌａ＝６０／３０／５／５である結晶子Ｂ１とが存在することが確認された。また、図２に示すＴＥＭ画像から、結晶子の粒径は５〜５０ｎｍ程度であった。
また、ＴＥＭ画像中において番号１，２，３，４，５，６を付して特定した個々の結晶子の元素分析についての各チャート（図２）に示されるように、得られた粉末Ａ１Ｂ１中では、結晶子Ａ１、結晶子Ｂ１の何れについても同種の結晶子が７個以上互いに接して存在しない高度な分散状態で結晶子Ａ１と結晶子Ｂ１が混在していることが確認された。具体的には、ＴＥＭ−ＥＤＸ測定（２０万倍〜４０万倍、５０視野）により、任意の直線上にある連続する５０個の結晶子について元素組成を分析し、結晶子Ａと結晶子Ｂを区別するとともに、分析した上記５０個の結晶子について、結晶子Ａが連続して接触する個数の最大値、及び結晶子Ｂが連続して接触する個数の最大値を求めた。これを５０視野において同様に行い、各視野での最大値の平均値を結晶子Ａ又は結晶子Ｂが連続して接触する個数とした。結果を表１の該当欄に示す。表１に示すように、本実施例１に係る粉末Ａ１Ｂ１では、結晶子Ａが連続して接触する個数は２個であり、結晶子Ｂが連続して接触する個数も２個であった。
From the TEM-EDX measurement results, the powder A1B1 according to Example 1 has a constituent metal element content (mol%) in terms of oxide of Zr / Ce / Nd / Y / La = 80/10/5/3 /. It is confirmed that there is a crystallite A1 that is 2 and a crystallite B1 that contains Ce / Zr / Nd / La = 60/30/5/5 in terms of oxide content (mol%) in terms of oxide It was done. Moreover, from the TEM image shown in FIG. 2, the particle size of the crystallite was about 5 to 50 nm.
Further, as shown in each chart (FIG. 2) for elemental analysis of individual crystallites identified by numbers 1, 2, 3, 4, 5, and 6 in the TEM image, the obtained powder A1B1 In particular, it was confirmed that the crystallite A1 and the crystallite B1 were mixed in a highly dispersed state in which no more than seven crystallites of the same kind existed in contact with each other in both the crystallite A1 and the crystallite B1. Specifically, the elemental composition of 50 consecutive crystallites on an arbitrary straight line is analyzed by TEM-EDX measurement (200,000 to 400,000 times, 50 visual fields), and crystallite A and crystallite B And the maximum value of the number of crystallites A that are in continuous contact and the maximum value of the number of crystallites B that are in continuous contact were determined for the 50 crystallites analyzed. This was similarly performed in 50 visual fields, and the average value of the maximum values in each visual field was defined as the number of crystallites A or B continuously contacting. The results are shown in the corresponding column of Table 1. As shown in Table 1, in the powder A1B1 according to Example 1, the number of crystallites A that are in continuous contact is two, and the number of crystallites B that are in continuous contact is also two.
次に、４９．５ｇの上記粉末Ａ１Ｂ１を４００ｍＬのイオン交換水中に分散させ、硝酸パラジウム（Ｐｄとして５質量％）１０ｇを投入して粉末に吸着担持させ、吸引濾過により水溶液を除去した。濾液をＩＣＰ発光分光で分析したところＰｄ担持効率は１００％であった。
かかるＰｄ担持粉末Ａ１Ｂ１を１１０℃で１２時間の乾燥後、大気中、５００℃で焼成することにより、本実施例１に係る排ガス浄化用触媒（Ｐｄ／Ａ１Ｂ１）を得た。この触媒粉末を圧粉成型し、粉砕して粒度０．５〜１．０ｍｍの後述する触媒活性評価試験用のペレット状触媒Ｉを得た。
Next, 49.5 g of the powder A1B1 was dispersed in 400 mL of ion-exchanged water, 10 g of palladium nitrate (5 mass% as Pd) was added and adsorbed on the powder, and the aqueous solution was removed by suction filtration. When the filtrate was analyzed by ICP emission spectroscopy, the Pd loading efficiency was 100%.
The Pd-supported powder A1B1 was dried at 110 ° C. for 12 hours and then calcined at 500 ° C. in the air to obtain an exhaust gas purifying catalyst (Pd / A1B1) according to Example 1. This catalyst powder was compacted and pulverized to obtain a pellet-shaped catalyst I for a catalytic activity evaluation test described later having a particle size of 0.5 to 1.0 mm.
［実施例２］
上記ホモジナイザーでの攪拌時間を６０分から１５分に変更した以外は上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＩＩの性状は、表１の該当欄に示す。
[Example 2]
Except that the stirring time in the homogenizer was changed from 60 minutes to 15 minutes, a pellet-like catalyst II for catalytic activity evaluation test was obtained by the same process as in Example 1 described above. Properties of catalyst II such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例３］
上記ホモジナイザーでの攪拌時間を６０分から５分に変更した以外は上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＩＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＩＩＩの性状は、表１の該当欄に示す。
[Example 3]
Except that the stirring time in the homogenizer was changed from 60 minutes to 5 minutes, a pellet-shaped catalyst III for catalytic activity evaluation test was obtained by the same process as in Example 1 described above. Properties of catalyst III such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例１］
上記マロン酸及び過酸化水素水を用いなかったこと以外は上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＩＶを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＩＶの性状は、表１の該当欄に示す。
[Comparative Example 1]
A pellet-like catalyst IV for catalytic activity evaluation test was obtained by the same process as in Example 1 described above except that the malonic acid and hydrogen peroxide solution were not used. Properties of catalyst IV such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例２］
上記マロン酸及び過酸化水素水を用いなかったことと、上記混合スラリーを加熱しなかったことと、さらに上記ホモジナイザーを使用しなかったこと以外は、上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒Ｖを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒Ｖの性状は、表１の該当欄に示す。
[Comparative Example 2]
Except that the malonic acid and the hydrogen peroxide solution were not used, the mixed slurry was not heated, and the homogenizer was not used, the catalytic activity was the same as in Example 1 described above. A pellet-shaped catalyst V for evaluation test was obtained. Properties of the catalyst V such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例３］
イオン交換水７００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）３２．８８ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）３７６．７ｇ、硝酸ネオジム溶液（Ｎｄ２Ｏ３として１０質量％）３２．１４ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）１２．９４ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）１２．４５ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。
次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄した後、１１０℃で乾燥させ、大気中、８００℃で５時間の焼成を行うことにより粉末Ａ１を得た。
ＴＥＭ−ＥＤＸ測定結果から、本比較例３に係る粉末Ａ１は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｎｄ／Ｙ／Ｌａ＝８０／１０／５／３／２である結晶子Ａ１が存在することが確認された。
[Comparative Example 3]
In 700 mL of ion-exchanged water, 32.88 g of cerium nitrate solution (20% by mass as CeO 2 ), 376.7 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ), neodymium nitrate solution (10% by mass as Nd 2 O 3 ) 32.14 g, Yttrium nitrate solution (10% by mass as Y 2 O 3 ) 12.94 g, Lanthanum nitrate solution (10% by mass as La 2 O 3 ) 12.45 g, PVP K-30 (trade name) 0.05 g A mixed solution was prepared by adding and stirring.
Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered, washed with pure water, dried at 110 ° C., and baked in the air at 800 ° C. for 5 hours to obtain Powder A1.
From the TEM-EDX measurement results, the powder A1 according to this Comparative Example 3 has a constituent metal element content (mol%) in terms of oxide of Zr / Ce / Nd / Y / La = 80/10/5/3 /. 2 was confirmed to be present.
一方、イオン交換水７００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）１６４．７ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）１１７．９ｇ、硝酸ネオジム溶液（Ｎｄ２Ｏ３として１０質量％）２６．８２ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）２５．９８ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。
次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄した後、１１０℃で乾燥させ、大気中、８００℃で５時間の焼成を行うことにより粉末Ｂ１を得た。
ＴＥＭ−ＥＤＸ測定結果から、本比較例３に係る粉末Ｂ１は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｎｄ／Ｌａ＝６０／３０／５／５である結晶子Ｂ１が存在することが確認された。また、図３に示すＴＥＭ画像から、結晶子の粒径は５〜５０ｎｍ程度であった。
また、図３のＴＥＭ画像中において番号７，８，９，１０，１１，１２を付して特定した個々の結晶子の元素分析についての各チャート（図３）に示されるように、得られた粉末（Ａ１＋Ｂ１）中では、結晶子Ａ１及び結晶子Ｂ１は上述した実施例１におけるような高度な分散状態では存在しておらず、結晶子Ａ１が偏在する部位、結晶子Ｂ１が偏在する部位が確認された。
Meanwhile, 700 mL of ion-exchanged water, 164.7 g of cerium nitrate solution (20 mass% as CeO 2 ), 117.9 g of zirconium oxynitrate solution (10 mass% as ZrO 2 ), 10 mass of neodymium nitrate solution (Nd 2 O 3 as Nd 2 O 3 ) %) 26.82 g, lanthanum nitrate solution (10% by mass as La 2 O 3 ) 25.98 g, and PVP K-30 (trade name) 0.05 g were added and stirred to prepare a mixed solution.
Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered, washed with pure water, dried at 110 ° C., and calcined in air at 800 ° C. for 5 hours to obtain Powder B1.
From the TEM-EDX measurement results, the powder B1 according to Comparative Example 3 is a crystal having a constituent metal element content (mol%) of Ce / Zr / Nd / La = 60/30/5/5 in terms of oxide. It was confirmed that child B1 exists. Moreover, from the TEM image shown in FIG. 3, the particle size of the crystallite was about 5 to 50 nm.
Further, as shown in each chart (FIG. 3) for elemental analysis of individual crystallites identified by numbers 7, 8, 9, 10, 11, and 12 in the TEM image of FIG. In the powder (A1 + B1), the crystallite A1 and the crystallite B1 are not present in a highly dispersed state as in Example 1 described above, and the crystallite A1 is unevenly distributed, and the crystallite B1 is unevenly distributed. Was confirmed.
次に、２４．７５ｇの上記粉末Ａ１と、２４．７５ｇの上記粉末Ｂ１を、４００ｍＬのイオン交換水中に分散させ、硝酸パラジウム（Ｐｄとして５質量％）１０ｇを投入して粉末に吸着担持させ、吸引濾過により水溶液を除去した。濾液をＩＣＰ発光分光で分析したところＰｄ担持効率は１００％であった。かかるＰｄ担持粉末を１１０℃で１２時間の乾燥後、大気中、５００℃で焼成することにより、本比較例３に係る排ガス浄化用触媒（Ｐｄ／（Ａ１＋Ｂ１））を得た。この触媒粉末を圧粉成型し、粉砕して粒度０．５〜１．０ｍｍの後述する触媒活性評価試験用のペレット状触媒ＶＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＶＩの性状は、表１の該当欄に示す。 Next, 24.75 g of the powder A1 and 24.75 g of the powder B1 are dispersed in 400 mL of ion-exchanged water, and 10 g of palladium nitrate (5 mass% as Pd) is added and adsorbed and supported on the powder. The aqueous solution was removed by suction filtration. When the filtrate was analyzed by ICP emission spectroscopy, the Pd loading efficiency was 100%. The Pd-supported powder was dried at 110 ° C. for 12 hours and then calcined at 500 ° C. in the air to obtain an exhaust gas purifying catalyst (Pd / (A1 + B1)) according to Comparative Example 3. The catalyst powder was compacted and pulverized to obtain a pellet-shaped catalyst VI for a catalytic activity evaluation test described later having a particle size of 0.5 to 1.0 mm. The properties of the catalyst VI, such as TEM-EDX measurement results, are shown in the corresponding column of Table 1.
［実施例４］
上記実施例１において使用した硝酸パラジウム溶液（Ｐｄとして５質量％）１０ｇに代えてジニトロジアミンＰｔ硝酸溶液（Ｐｔとして５質量％）１０ｇを用いた以外は上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＶＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＶＩＩの性状は、表１の該当欄に示す。
[Example 4]
In the same process as in Example 1 described above, except that 10 g of dinitrodiamine Pt nitric acid solution (5 mass% as Pt) was used instead of 10 g of the palladium nitrate solution (5 mass% as Pd) used in Example 1 above. A pellet catalyst VII for activity evaluation test was obtained. The properties of the catalyst VII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例４］
上記比較例３において使用した硝酸パラジウム溶液（Ｐｄとして５質量％）１０ｇに代えてジニトロジアミンＰｔ硝酸溶液（Ｐｔとして５質量％）１０ｇを用いた以外は上述した比較例３と同様のプロセスで触媒活性評価試験用のペレット状触媒ＶＩＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＶＩＩＩの性状は、表１の該当欄に示す。
[Comparative Example 4]
In the same process as in Comparative Example 3 described above except that 10 g of dinitrodiamine Pt nitric acid solution (5 mass% as Pt) was used instead of 10 g of the palladium nitrate solution (5 mass% as Pd) used in Comparative Example 3 above. A pellet-shaped catalyst VIII for activity evaluation test was obtained. The properties of catalyst VIII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例５］
上記実施例１において使用した硝酸パラジウム溶液（Ｐｄとして５質量％）１０ｇに代えて硝酸ロジウム溶液（Ｒｈとして５質量％）１０ｇを用いた以外は上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＩＸを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＩＸの性状は、表１の該当欄に示す。
[Example 5]
Evaluation of catalytic activity in the same process as in Example 1 except that 10 g of rhodium nitrate solution (5% by mass as Rh) was used instead of 10 g of the palladium nitrate solution (5% by mass as Pd) used in Example 1 above. A pellet-like catalyst IX for test was obtained. Properties of the catalyst IX such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例５］
上記比較例３において使用した硝酸パラジウム溶液（Ｐｄとして５質量％）１０ｇに代えて硝酸ロジウム溶液（Ｒｈとして５質量％）１０ｇを用いた以外は上述した比較例３と同様のプロセスで触媒活性評価試験用のペレット状触媒Ｘを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒Ｘの性状は、表１の該当欄に示す。
[Comparative Example 5]
Evaluation of catalytic activity in the same process as in Comparative Example 3 except that 10 g of rhodium nitrate solution (5 mass% as Rh) was used instead of 10 g of the palladium nitrate solution (5 mass% as Pd) used in Comparative Example 3 above. A pellet-shaped catalyst X for test was obtained. Properties of the catalyst X such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例６］
イオン交換水８５０ｍＬにオキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）６００ｇとＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ２を得た。
一方、イオン交換水５５０ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）１４９．３ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）６１．０７ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）４０．３７ｇ、ＰＶＰ Ｋ−３０（商品名）０．０４ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ２を得た。
[Comparative Example 6]
To 850 mL of ion-exchanged water, 600 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ) and 0.06 g of PVP K-30 (trade name) were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a2.
On the other hand, in 550 mL of ion-exchanged water, 149.3 g of cerium nitrate solution (20% by mass as CeO 2 ), 61.07 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ), and 10% by mass of lanthanum nitrate solution (La 2 O 3 ) %) 40.37 g and PVP K-30 (trade name) 0.04 g were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b2.
そして、上記実施例１において使用した前駆体ａ１及び前駆体ｂ１に代えて上記前駆体ａ２及び前駆体ｂ２を用いた以外は上述した実施例１と同様のプロセスで粉末Ａ２Ｂ２を得た。ＴＥＭ−ＥＤＸ測定結果から、本比較例６に係る粉末Ａ２Ｂ２は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ＝１００である結晶子Ａ２と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝７０／２０／１０である結晶子Ｂ２とが存在することが確認された。
次に、４９ｇの上記粉末Ａ２Ｂ２を４００ｍＬのイオン交換水中に分散させ、硝酸パラジウム（Ｐｄとして５質量％）２０ｇを投入して粉末に吸着担持させ、吸引濾過により水溶液を除去した。濾液をＩＣＰ発光分光で分析したところＰｄ担持効率は１００％であった。
かかるＰｄ担持粉末Ａ２Ｂ２を１１０℃で１２時間の乾燥後、大気中、５００℃で焼成することにより、本比較例６に係る排ガス浄化用触媒（Ｐｄ／Ａ２Ｂ２）を得た。この触媒粉末を上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＩの性状は、表１の該当欄に示す。
And powder A2B2 was obtained by the process similar to Example 1 mentioned above except having replaced with the precursor a1 and precursor b1 which were used in the said Example 1, and having used the said precursor a2 and the precursor b2. From the TEM-EDX measurement results, the powder A2B2 according to Comparative Example 6 is composed of the crystallite A2 having a constituent metal element content (mol%) of Zr = 100 in terms of oxide and the constituent metal element in terms of oxide. It was confirmed that a crystallite B2 having a content (mol%) of Ce / Zr / La = 70/20/10 was present.
Next, 49 g of the powder A2B2 was dispersed in 400 mL of ion-exchanged water, 20 g of palladium nitrate (5 mass% as Pd) was added and adsorbed on the powder, and the aqueous solution was removed by suction filtration. When the filtrate was analyzed by ICP emission spectroscopy, the Pd loading efficiency was 100%.
The Pd-supported powder A2B2 was dried at 110 ° C. for 12 hours and then calcined at 500 ° C. in the air to obtain an exhaust gas purifying catalyst (Pd / A2B2) according to Comparative Example 6. This catalyst powder was used in the same process as in Example 1 to obtain a pellet-shaped catalyst XI for a catalytic activity evaluation test. The properties of the catalyst XI such as the TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例６］
イオン交換水８５０ｍＬにオキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）５９４．５ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）５．５０ｇ、ＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ３を得た。
そして、上述の比較例６において使用した前駆体ａ２に代えて上記前駆体ａ３を使用した以外は上述した比較例６と同様のプロセスで粉末Ａ３Ｂ２を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例６に係る粉末Ａ３Ｂ２は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｙ＝９９／１である結晶子Ａ３と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝７０／２０／１０である結晶子Ｂ２とが存在することが確認された。
さらに、粉末Ａ２Ｂ２に代えて上記粉末Ａ３Ｂ２を用いた以外は、上述した比較例６と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＩＩの性状は、表１の該当欄に示す。
[Example 6]
In 850 mL of ion-exchanged water, 594.5 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ), 5.50 g of yttrium nitrate solution (10% by mass as Y 2 O 3 ), 0.06 g of PVP K-30 (trade name) A mixed solution was prepared by adding and stirring. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a3.
And it replaced with the precursor a2 used in the above-mentioned comparative example 6, and obtained powder A3B2 with the process similar to the comparative example 6 mentioned above except having used the said precursor a3. From the TEM-EDX measurement results, the powder A3B2 according to Example 6 has a crystallite A3 whose constituent metal element content (mol%) is Zr / Y = 99/1 in terms of oxide, and in terms of oxide. It was confirmed that there was a crystallite B2 in which the content (mol%) of the constituent metal elements was Ce / Zr / La = 70/20/10.
Further, a pellet-shaped catalyst XII for catalytic activity evaluation test was obtained by the same process as Comparative Example 6 described above except that the powder A3B2 was used instead of the powder A2B2. Properties of catalyst XII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例７］
イオン交換水８５０ｍＬにオキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）５４４．６ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）５５．４４ｇ、ＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ４を得た。
そして、上述の比較例６において使用した前駆体ａ２に代えて上記前駆体ａ４を使用した以外は上述した比較例６と同様のプロセスで粉末Ａ４Ｂ２を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例７に係る粉末Ａ４Ｂ２は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｙ＝９０／１０である結晶子Ａ４と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝７０／２０／１０である結晶子Ｂ２とが存在することが確認された。
さらに、粉末Ａ２Ｂ２に代えて上記粉末Ａ４Ｂ２を用いた以外は、上述した比較例６と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＩＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＩＩＩの性状は、表１の該当欄に示す。
[Example 7]
In 850 mL of ion-exchanged water, 544.6 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ), 55.44 g of yttrium nitrate solution (10% by mass as Y 2 O 3 ), 0.06 g of PVP K-30 (trade name) A mixed solution was prepared by adding and stirring. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a4.
And it replaced with the precursor a2 used in the above-mentioned comparative example 6, and obtained powder A4B2 by the process similar to the comparative example 6 mentioned above except having used the said precursor a4. From the TEM-EDX measurement results, the powder A4B2 according to Example 7 has a crystallite A4 in which the content (mol%) of the constituent metal element in terms of oxide is Zr / Y = 90/10, and in terms of oxide. It was confirmed that there was a crystallite B2 in which the content (mol%) of the constituent metal elements was Ce / Zr / La = 70/20/10.
Further, a pellet-shaped catalyst XIII for catalytic activity evaluation test was obtained in the same process as Comparative Example 6 described above except that the powder A4B2 was used instead of the powder A2B2. Properties of the catalyst XIII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例８］
イオン交換水８５０ｍＬに硝酸セリウム溶液（ＣｅＯ２として２０質量％）２０．７１ｇ、オキシ硝酸ジルコニウム（ＺｒＯ２として１０質量％）５０４．２ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）５４．３６ｇ、ＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ５を得た。
そして、上述の比較例６において使用した前駆体ａ２に代えて上記前駆体ａ５を使用した以外は上述した比較例６と同様のプロセスで粉末Ａ５Ｂ２を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例８に係る粉末Ａ５Ｂ２は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ＝８５／５／１０である結晶子Ａ５と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝７０／２０／１０である結晶子Ｂ２とが存在することが確認された。
さらに、粉末Ａ２Ｂ２に代えて上記粉末Ａ５Ｂ２を用いた以外は、上述した比較例６と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＩＶを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＩＶの性状は、表１の該当欄に示す。
[Example 8]
In 850 mL of ion-exchanged water, 20.71 g of cerium nitrate solution (20 mass% as CeO 2 ), 504.2 g of zirconium oxynitrate (10 mass% as ZrO 2 ), yttrium nitrate solution (10 mass% as Y 2 O 3 ) 54. 36 g and PVP K-30 (trade name) 0.06 g were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a5.
And it replaced with the precursor a2 used in the above-mentioned comparative example 6, and obtained powder A5B2 with the process similar to the comparative example 6 mentioned above except having used the said precursor a5. From the TEM-EDX measurement results, the powder A5B2 according to Example 8 is a crystallite A5 in which the content (mol%) of the constituent metal element in terms of oxide is Zr / Ce / Y = 85/5/10, It was confirmed that there was a crystallite B2 having a constituent metal element content (mol%) of Ce / Zr / La = 70/20/10 in terms of oxide.
Further, a pellet catalyst XIV for catalytic activity evaluation test was obtained in the same process as Comparative Example 6 described above except that the powder A5B2 was used instead of the powder A2B2. Properties of catalyst XIV such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例９］
イオン交換水８５０ｍＬに硝酸セリウム溶液（ＣｅＯ２として２０質量％）５９．７９ｇ、オキシ硝酸ジルコニウム（ＺｒＯ２として１０質量％）４２８．１ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）５２．３１ｇ、ＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ６を得た。
そして、上述の比較例６において使用した前駆体ａ２に代えて上記前駆体ａ６を使用した以外は上述した比較例６と同様のプロセスで粉末Ａ６Ｂ２を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例９に係る粉末Ａ６Ｂ２は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ＝７５／１５／１０である結晶子Ａ６と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝７０／２０／１０である結晶子Ｂ２とが存在することが確認された。
さらに、粉末Ａ２Ｂ２に代えて上記粉末Ａ６Ｂ２を用いた以外は、上述した比較例６と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＶを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＶの性状は、表１の該当欄に示す。
[Example 9]
In 850 mL of ion-exchanged water, 59.79 g of a cerium nitrate solution (20 mass% as CeO 2 ), 428.1 g of zirconium oxynitrate (10 mass% as ZrO 2 ), yttrium nitrate solution (10 mass% as Y 2 O 3 ) 52. 31 g and PVP K-30 (trade name) 0.06 g were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a6.
And it replaced with the precursor a2 used in the above-mentioned comparative example 6, and obtained powder A6B2 by the process similar to the comparative example 6 mentioned above except having used the said precursor a6. From the TEM-EDX measurement results, the powder A6B2 according to Example 9 has a crystallite A6 in which the content (mol%) of the constituent metal elements is Zr / Ce / Y = 75/15/10 in terms of oxides, It was confirmed that there was a crystallite B2 having a constituent metal element content (mol%) of Ce / Zr / La = 70/20/10 in terms of oxide.
Further, a pellet catalyst XV for catalytic activity evaluation test was obtained by the same process as Comparative Example 6 described above except that the powder A6B2 was used instead of the powder A2B2. The properties of the catalyst XV, such as TEM-EDX measurement results, are shown in the corresponding column of Table 1.
［比較例７］
イオン交換水８５０ｍＬに硝酸セリウム溶液（ＣｅＯ２として２０質量％）９６．０３ｇ、オキシ硝酸ジルコニウム（ＺｒＯ２として１０質量％）３５７．５ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）５０．４０ｇ、ＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ７を得た。
そして、上述の比較例６において使用した前駆体ａ２に代えて上記前駆体ａ７を使用した以外は上述した比較例６と同様のプロセスで粉末Ａ７Ｂ２を得た。ＴＥＭ−ＥＤＸ測定結果から、本比較例７に係る粉末Ａ７Ｂ２は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ＝６５／２５／１０である結晶子Ａ７と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝７０／２０／１０である結晶子Ｂ２とが存在することが確認された。
さらに、粉末Ａ２Ｂ２に代えて上記粉末Ａ７Ｂ２を用いた以外は、上述した比較例６と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＶＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＶＩの性状は、表１の該当欄に示す。
[Comparative Example 7]
96.03 g of cerium nitrate solution (20 mass% as CeO 2 ), 357.5 g of zirconium oxynitrate (10 mass% as ZrO 2 ), yttrium nitrate solution (10 mass% as Y 2 O 3 ) in 850 mL of ion-exchanged water 40 g and 0.06 g of PVP K-30 (trade name) were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a7.
And it replaced with the precursor a2 used in the above-mentioned comparative example 6, and obtained powder A7B2 by the process similar to the comparative example 6 mentioned above except having used the said precursor a7. From the TEM-EDX measurement results, the powder A7B2 according to the present Comparative Example 7 has a crystallite A7 in which the content (mol%) of the constituent metal element in terms of oxide is Zr / Ce / Y = 65/25/10, It was confirmed that there was a crystallite B2 having a constituent metal element content (mol%) of Ce / Zr / La = 70/20/10 in terms of oxide.
Further, a pellet catalyst XVI for catalytic activity evaluation test was obtained by the same process as Comparative Example 6 described above except that the powder A7B2 was used instead of the powder A2B2. Properties of catalyst XVI such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例８］
イオン交換水８００ｍＬに硝酸セリウム溶液（ＣｅＯ２として２０質量％）１８．６１ｇ、オキシ硝酸ジルコニウム（ＺｒＯ２として１０質量％）４５３．１ｇ、硝酸イットリウム溶液（Ｙ２Ｏ３として１０質量％）２４．４２ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）３５．２４ｇ、ＰＶＰ Ｋ−３０（商品名）０．０６ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ａ８を得た。
一方、イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）２２５ｇと、ＰＶＰ Ｋ−３０（商品名）０．０５ｇとを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ３を得た。
[Comparative Example 8]
18.81 g of cerium nitrate solution (20% by mass as CeO 2 ), 453.1 g of zirconium oxynitrate (10% by mass as ZrO 2 ), 800% ion-exchanged water, yttrium nitrate solution (10% by mass as Y 2 O 3 ) 42 g, 35.24 g of lanthanum nitrate solution (10% by mass as La 2 O 3 ) and 0.06 g of PVP K-30 (trade name) were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor a8.
On the other hand, 225 g of a cerium nitrate solution (20% by mass as CeO 2 ) and 0.05 g of PVP K-30 (trade name) were added to 600 mL of ion-exchanged water and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b3.
そして、上記実施例１において使用した前駆体ａ１及び前駆体ｂ１に代えて上記前駆体ａ８及び前駆体ｂ３を用いた以外は上述した実施例１と同様のプロセスで粉末Ａ８Ｂ３を得た。ＴＥＭ−ＥＤＸ測定結果から、本比較例８に係る粉末Ａ８Ｂ３は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ＝１００である結晶子Ｂ３とが存在することが確認された。
次に、４９．２５ｇの上記粉末Ａ８Ｂ３を４００ｍＬのイオン交換水中に分散させ、ジニトロジアミンＰｔ硝酸溶液（Ｐｔとして５質量％）１５ｇを投入して粉末に吸着担持させ、吸引濾過により水溶液を除去した。濾液をＩＣＰ発光分光で分析したところＰｔ担持効率は１００％であった。
かかるＰｔ担持粉末Ａ８Ｂ３を１１０℃で１２時間の乾燥後、大気中、５００℃で焼成することにより、本比較例８に係る排ガス浄化用触媒（Ｐｔ／Ａ８Ｂ３）を得た。この触媒粉末を上述した実施例１と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＶＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＶＩＩの性状は、表１の該当欄に示す。
And it replaced with the precursor a1 and the precursor b1 which were used in the said Example 1, and obtained powder A8B3 by the process similar to the above-mentioned Example 1 except having used the said precursor a8 and the precursor b3. From the TEM-EDX measurement results, the powder A8B3 according to Comparative Example 8 is a crystal in which the content (mol%) of the constituent metal element is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that the child A8 and the crystallite B3 having a constituent metal element content (mol%) of Ce = 100 in terms of oxide were present.
Next, 49.25 g of the powder A8B3 was dispersed in 400 mL of ion-exchanged water, 15 g of dinitrodiamine Pt nitric acid solution (5 mass% as Pt) was added and adsorbed on the powder, and the aqueous solution was removed by suction filtration. . When the filtrate was analyzed by ICP emission spectroscopy, the Pt loading efficiency was 100%.
The Pt-supported powder A8B3 was dried at 110 ° C. for 12 hours and then calcined at 500 ° C. in the air to obtain an exhaust gas purifying catalyst (Pt / A8B3) according to Comparative Example 8. This catalyst powder was used in the same process as in Example 1 to obtain a pellet catalyst XVII for catalytic activity evaluation test. The properties of catalyst XVII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例１０］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）２２２．９ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）４．２６ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ４を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ４を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ４を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例１０に係る粉末Ａ８Ｂ４は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｌａ＝９９／１である結晶子Ｂ４とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ４を用いた以外は、上述した比較例８と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＶＩＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＶＩＩＩの性状は、表１の該当欄に示す。
[Example 10]
In 600 mL of ion-exchanged water, 222.9 g of cerium nitrate solution (20 mass% as CeO 2 ), 4.26 g of lanthanum nitrate solution (10 mass% as La 2 O 3 ), 0.05 g of PVP K-30 (trade name) A mixed solution was prepared by adding and stirring. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b4.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B4 by the process similar to the comparative example 8 mentioned above except having used the said precursor b4. From the TEM-EDX measurement results, the powder A8B4 according to Example 10 is a crystal in which the content (mol%) of the constituent metal elements is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that the child A8 and the crystallite B4 in which the content (mol%) of the constituent metal element in terms of oxide was Ce / La = 99/1 were present.
Further, a pellet catalyst XVIII for catalytic activity evaluation test was obtained in the same process as in Comparative Example 8 except that the powder A8B4 was used instead of the powder A8B3. Properties of catalyst XVIII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例１１］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）２０３．６ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）４２．８２ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ５を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ５を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ５を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例１１に係る粉末Ａ８Ｂ５は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｌａ＝９０／１０である結晶子Ｂ５とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ５を用いた以外は、上述した比較例８と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＩＸを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＩＸの性状は、表１の該当欄に示す。
[Example 11]
In 600 mL of ion-exchanged water, 203.6 g of cerium nitrate solution (20% by mass as CeO 2 ), 42.82 g of lanthanum nitrate solution (10% by mass as La 2 O 3 ), 0.05 g of PVP K-30 (trade name) A mixed solution was prepared by adding and stirring. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b5.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B5 by the process similar to the comparative example 8 mentioned above except having used the said precursor b5. From the TEM-EDX measurement results, the powder A8B5 according to Example 11 is a crystal in which the content (mol%) of the constituent metal element is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that the child A8 and the crystallite B5 having a constituent metal element content (mol%) of Ce / La = 90/10 in terms of oxide were present.
Further, a pellet catalyst XIX for catalytic activity evaluation test was obtained in the same process as in Comparative Example 8 except that the powder A8B5 was used instead of the powder A8B3. Properties of the catalyst XIX such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例１２］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）１８６．３ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）３３．３４ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）４４．０８ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ６を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ６を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ６を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例１２に係る粉末Ａ８Ｂ６は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝８０／１０／１０である結晶子Ｂ６とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ６を用いた以外は、上述した比較例８と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＸを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＸの性状は、表１の該当欄に示す。
[Example 12]
In 600 mL of ion exchange water, 186.3 g of cerium nitrate solution (20 mass% as CeO 2 ), 33.34 g of zirconium oxynitrate solution (10 mass% as ZrO 2 ), lanthanum nitrate solution (10 mass% as La 2 O 3 ) 44.08 g and 0.05 g of PVP K-30 (trade name) were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b6.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B6 by the process similar to the comparative example 8 mentioned above except having used the said precursor b6. From the TEM-EDX measurement results, the powder A8B6 according to Example 12 is a crystal in which the content (mol%) of the constituent metal element is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that there was a child A8 and a crystallite B6 in which the content (mol%) of the constituent metal element in terms of oxide was Ce / Zr / La = 80/10/10.
Further, a pellet-shaped catalyst XX for catalytic activity evaluation test was obtained in the same process as in Comparative Example 8 except that the powder A8B6 was used instead of the powder A8B3. The properties of the catalyst XX such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例１３］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）１４８．４ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）１０６．３ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）４６．８４ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ７を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ７を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ７を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例１３に係る粉末Ａ８Ｂ７は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝６０／３０／１０である結晶子Ｂ７とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ７を用いた以外は、上述した比較例８と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＸＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＸＩの性状は、表１の該当欄に示す。
[Example 13]
In 600 mL of ion-exchanged water, 148.4 g of cerium nitrate solution (20% by mass as CeO 2 ), 106.3 g of zirconium oxynitrate solution (10% by mass as ZrO 2 ), lanthanum nitrate solution (10% by mass as La 2 O 3 ) 46.84 g and PVP K-30 (trade name) 0.05 g were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b7.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B7 by the process similar to the comparative example 8 mentioned above except having used the said precursor b7. From the TEM-EDX measurement results, the powder A8B7 according to Example 13 is a crystal in which the content (mol%) of the constituent metal element is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that there was a child A8 and a crystallite B7 having a constituent metal element content (mol%) of Ce / Zr / La = 60/30/10 in terms of oxide.
Further, a pellet catalyst XXI for catalytic activity evaluation test was obtained in the same process as in Comparative Example 8 except that the powder A8B7 was used instead of the powder A8B3. Properties of catalyst XXI such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例１４］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）１０５．６ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）１８８．９ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）５０．００ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ８を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ８を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ８を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例１４に係る粉末Ａ８Ｂ８は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝４０／５０／１０である結晶子Ｂ８とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ８を用いた以外は、上述した比較例８と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＸＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＸＩＩの性状は、表１の該当欄に示す。
[Example 14]
In 600 mL of ion exchange water, 105.6 g of cerium nitrate solution (20 mass% as CeO 2 ), 188.9 g of zirconium oxynitrate solution (10 mass% as ZrO 2 ), lanthanum nitrate solution (10 mass% as La 2 O 3 ) 50.00 g and PVP K-30 (trade name) 0.05 g were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b8.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B8 by the process similar to the comparative example 8 mentioned above except having used the said precursor b8. From the TEM-EDX measurement results, the powder A8B8 according to Example 14 is a crystal in which the content (mol%) of the constituent metal elements is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that the crystallite B8 having a constituent metal element content (mol%) of Ce / Zr / La = 40/50/10 in terms of oxide was present.
Furthermore, a pellet-like catalyst XXII for catalytic activity evaluation test was obtained in the same process as in Comparative Example 8 except that the powder A8B8 was used instead of the powder A8B3. Properties of catalyst XXII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［実施例１５］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）５６．５４ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）２８３．４ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）５３．５２ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ９を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ９を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ９を得た。ＴＥＭ−ＥＤＸ測定結果から、本実施例１５に係る粉末Ａ８Ｂ９は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝２０／７０／１０である結晶子Ｂ８とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ９を用いた以外は、上述した比較例８と同様のプロセスで触媒活性評価試験用のペレット状触媒ＸＸＩＩＩを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＸＩＩＩの性状は、表１の該当欄に示す。
[Example 15]
In 600 mL of ion exchange water, 56.54 g of cerium nitrate solution (20 mass% as CeO 2 ), 283.4 g of zirconium oxynitrate solution (10 mass% as ZrO 2 ), lanthanum nitrate solution (10 mass% as La 2 O 3 ) 53.52 g and 0.05 g of PVP K-30 (trade name) were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b9.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B9 by the process similar to the comparative example 8 mentioned above except having used the said precursor b9. From the TEM-EDX measurement results, the powder A8B9 according to Example 15 is a crystal in which the content (mol%) of the constituent metal element is Zr / Ce / Y / La = 85/5/5/5 in terms of oxide. It was confirmed that the crystallite B8 having a constituent metal element content (mol%) of Ce / Zr / La = 20/70/10 in terms of oxide was present.
Further, a pellet-like catalyst XXIII for catalytic activity evaluation test was obtained in the same process as Comparative Example 8 except that the powder A8B9 was used instead of the powder A8B3. Properties of catalyst XXIII such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
［比較例９］
イオン交換水６００ｍＬに、硝酸セリウム溶液（ＣｅＯ２として２０質量％）２９．３２ｇ、オキシ硝酸ジルコニウム溶液（ＺｒＯ２として１０質量％）３３５．９ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として１０質量％）５５．５ｇ、ＰＶＰ Ｋ−３０（商品名）０．０５ｇを添加し、攪拌して混合溶液を調製した。次いで、この混合溶液を９０〜９５℃に加熱した後、尿素を添加してｐＨを１１に調整して共沈物を得た。その後、ヒドラジン１３ｇを添加し、９０〜９５℃で１２時間攪拌した。得られた共沈物を濾過し、純水で洗浄することにより前駆体ｂ１０を得た。
そして、上述の比較例８において使用した前駆体ｂ３に代えて上記前駆体ｂ１０を使用した以外は上述した比較例８と同様のプロセスで粉末Ａ８Ｂ１０を得た。ＴＥＭ−ＥＤＸ測定結果から、本比較例９に係る粉末Ａ８Ｂ１０は、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＺｒ／Ｃｅ／Ｙ／Ｌａ＝８５／５／５／５である結晶子Ａ８と、酸化物換算で構成金属元素の含有率（ｍｏｌ％）がＣｅ／Ｚｒ／Ｌａ＝１０／８０／１０である結晶子Ｂ８とが存在することが確認された。
さらに、粉末Ａ８Ｂ３に代えて上記粉末Ａ８Ｂ１０を用いた以外は、上述した比較例８と同様のプロセスで触媒ＸＸＩＶを得た。ＴＥＭ−ＥＤＸ測定結果等の触媒ＸＸＩＶの性状は、表１の該当欄に示す。
[Comparative Example 9]
In 600 mL of ion exchange water, 29.32 g of cerium nitrate solution (20 mass% as CeO 2 ), 335.9 g of zirconium oxynitrate solution (10 mass% as ZrO 2 ), lanthanum nitrate solution (10 mass% as La 2 O 3 ) 55.5 g and 0.05 g of PVP K-30 (trade name) were added and stirred to prepare a mixed solution. Subsequently, after heating this mixed solution to 90-95 degreeC, urea was added and pH was adjusted to 11, and the coprecipitate was obtained. Thereafter, 13 g of hydrazine was added and stirred at 90 to 95 ° C. for 12 hours. The obtained coprecipitate was filtered and washed with pure water to obtain a precursor b10.
And it replaced with the precursor b3 used in the above-mentioned comparative example 8, and obtained powder A8B10 by the process similar to the comparative example 8 mentioned above except having used the said precursor b10. From the TEM-EDX measurement results, the powder A8B10 according to Comparative Example 9 is a crystal in which the content (mol%) of the constituent metal element in terms of oxide is Zr / Ce / Y / La = 85/5/5/5. It was confirmed that the crystallite B8 having a constituent metal element content (mol%) of Ce / Zr / La = 10/80/10 in terms of oxide was present.
Furthermore, catalyst XXIV was obtained by the same process as in Comparative Example 8 described above, except that the powder A8B10 was used instead of the powder A8B3. Properties of catalyst XXIV such as TEM-EDX measurement results are shown in the corresponding column of Table 1.
表１に示すように、各実施例に係る触媒では、結晶子Ａと結晶子Ｂのいずれについても電子顕微鏡観察下で同種の結晶子が７個以上互いに接して存在しないように高度に分散した状態で存在している。換言すれば、上述した規定による同種の結晶子が連続して接触する個数は５個以下であった。他方、各比較例に係る触媒では、電子顕微鏡観察下で同種の結晶子が７個以上互いに接して存在することが認められ、上述した規定による同種の結晶子が連続して接触する個数も実施例の触媒と比較して多く、同種の結晶子が連続して接触する個数が１０個以上のものも認められた。 As shown in Table 1, in the catalysts according to the respective examples, both the crystallite A and the crystallite B were highly dispersed so that seven or more of the same kind of crystallites were not in contact with each other under the electron microscope observation. Exists in a state. In other words, the number of continuous contact of the same kind of crystallites as defined above was 5 or less. On the other hand, in the catalyst according to each comparative example, it is recognized that seven or more of the same kind of crystallites exist in contact with each other under the observation of an electron microscope, and the number of the same kind of crystallites in contact with each other according to the above-mentioned regulations is also implemented. Compared to the catalyst of the example, there were many cases where the number of the same kind of crystallites continuously contacting was 10 or more.
＜試験例２：高温処理時の結晶成長の度合い〜比表面積の測定〜＞
試験例１で得られた実施例１〜１５及び比較例１〜９の各触媒を熱処理した後のＢＥＴ比表面積（ｍ２／ｇ）を調べた。
具体的には、各触媒（粉末）について大気（Ａｉｒ雰囲気）中で１１５０℃、５時間の熱処理（焼成）を行った。その後、一般的なＢＥＴ法に基づいて表面積を測定した。結果を表２に示す。
<Test Example 2: Degree of crystal growth during high temperature treatment -Measurement of specific surface area->
The BET specific surface area (m 2 / g) after heat-treating each of the catalysts of Examples 1 to 15 and Comparative Examples 1 to 9 obtained in Test Example 1 was examined.
Specifically, each catalyst (powder) was heat-treated (fired) at 1150 ° C. for 5 hours in the air (Air atmosphere). Thereafter, the surface area was measured based on a general BET method. The results are shown in Table 2.
表２に示すように、各実施例の触媒粉末（酸化物粒子）の比表面積は何れも３５ｍ２／ｇ以上であり、いくつかは４０ｍ２／ｇ以上であった。その一方で、各比較例の触媒粉末（酸化物粒子）の比表面積は何れも３０ｍ２／ｇ以下であった。このことは、分散状態で異種結晶子が混在する実施例の触媒では、異種結晶子同士が障壁となって結晶成長を阻み、結果、比表面積の低下を効果的に防ぎ得ることを示している。 As shown in Table 2, the specific surface area of the catalyst powder (oxide particles) of each Example was 35 m 2 / g or more, and some was 40 m 2 / g or more. On the other hand, the specific surface areas of the catalyst powders (oxide particles) of the respective comparative examples were all 30 m 2 / g or less. This indicates that in the catalyst of the example in which different kinds of crystallites are mixed in a dispersed state, the different kinds of crystallites serve as a barrier to prevent crystal growth, and as a result, it is possible to effectively prevent a decrease in specific surface area. .
＜試験例３：触媒活性評価＞
試験例１で得られた実施例１〜１５及び比較例１〜９の各触媒を熱耐久試験に供試した後の触媒活性の評価を調べた。
具体的には、各触媒（上記ペレット状触媒）を、流通式の熱耐久試験装置に配置し、窒素ガスに酸素（Ｏ２）を１ｍｏｌ％加えたリーンガスと、窒素ガスに一酸化炭素（ＣＯ）を２ｍｏｌ％加えたリッチガスを、触媒床温度９００℃において５００ｍＬ／分のガス流で３分周期で交互に４０時間流通させる熱耐久処理を行った。
<Test Example 3: Evaluation of catalytic activity>
The evaluation of catalyst activity after each of the catalysts of Examples 1 to 15 and Comparative Examples 1 to 9 obtained in Test Example 1 was subjected to a thermal durability test was examined.
Specifically, each catalyst (the above-described pellet-shaped catalyst) is placed in a flow-type thermal durability test apparatus, lean gas obtained by adding 1 mol% of oxygen (O 2 ) to nitrogen gas, and carbon monoxide (CO ) Was added for 2 hours in a gas flow of 500 mL / min at a catalyst bed temperature of 900.degree.
次いで、処理後の触媒を、常圧固定床流通反応装置に配置し、ストイキ相当のモデルガスを該装置内の触媒に流通させつつ、１００℃から５００℃まで１２℃／分の速度で昇温していき、その間のＨＣ浄化率及びＮＯｘ浄化率を連続的に測定した。そして当該浄化率が５０％となるときの温度を５０％浄化温度として求めた。結果を表２の該当欄に示す。また、結果の一部（実施例１〜３及び比較例１〜３）を図４及び図５に示す。
表２ならびに図４、図５に示すように、担持されるＰＧＭ（Ｐｄ，Ｐｔ，Ｒｈ）の種類にかかわらず、実施例に係る触媒の５０％ＨＣ浄化温度及び５０％ＮＯｘ浄化温度は、対応する比較例の触媒の５０％ＨＣ浄化温度及び５０％ＮＯｘ浄化温度よりも低かった。
このことは、分散状態で異種結晶子が混在する各実施例の触媒では、異種結晶子同士が障壁となって結晶成長を阻み、結果、触媒金属（ここではＰＧＭ）の凝集やＯＳＣ機能の低下を防止して高い触媒活性を維持し得ることを示している。
Next, the treated catalyst is placed in an atmospheric pressure fixed bed flow reactor, and the temperature is increased from 100 ° C. to 500 ° C. at a rate of 12 ° C./min while a stoichiometric model gas is passed through the catalyst in the device. In the meantime, the HC purification rate and the NO x purification rate were continuously measured. The temperature at which the purification rate was 50% was determined as the 50% purification temperature. The results are shown in the corresponding column of Table 2. A part of the results (Examples 1 to 3 and Comparative Examples 1 to 3) is shown in FIGS.
As shown in Table 2 and FIGS. 4 and 5, regardless of the type of PGM (Pd, Pt, Rh) carried, the 50% HC purification temperature and 50% NO x purification temperature of the catalyst according to the example are It was lower than the 50% HC purification temperature and 50% NO x purification temperature of the corresponding comparative catalyst.
This is because in the catalyst of each example in which different kinds of crystallites are mixed in a dispersed state, the different kinds of crystallites serve as a barrier to prevent crystal growth, resulting in aggregation of catalyst metal (here PGM) and deterioration of OSC function. It is shown that high catalytic activity can be maintained by preventing the above.
以上の試験例から明らかなように、ここで開示される排ガス浄化用触媒を用いることによって結晶成長による触媒金属の凝集、ＯＳＣ能の低下を防止し、例えば三元触媒の触媒活性（三元性能）を安定して発揮させることができる。従って、より高性能な三元触媒その他の排ガス浄化用触媒を提供することができる。 As is clear from the above test examples, the use of the exhaust gas-purifying catalyst disclosed herein prevents aggregation of the catalyst metal due to crystal growth and a decrease in OSC ability. For example, the catalytic activity of the three-way catalyst (three-way performance) ) Can be exhibited stably. Therefore, a higher performance three-way catalyst and other exhaust gas purification catalysts can be provided.
１ 基材
２ セル
４ リブ壁
１０ 排ガス浄化用触媒
1 Base material 2 Cell 4 Rib wall 10 Exhaust gas purification catalyst
Claims (5)
酸化触媒及び／又は還元触媒として機能する触媒金属と該金属を担持する担体とを備えており、
前記担体としてＯＳＣ材として機能する酸化物から成る担体を備えており、該担体は、
ジルコニウム（Ｚｒ）及びセリウム（Ｃｅ）のうちの少なくとも一方を含む酸化物から成る結晶子Ａと、
ジルコニウム（Ｚｒ）及びセリウム（Ｃｅ）のうちの少なくとも一方を含む酸化物から成る結晶子Ｂであって、該酸化物中のＺｒ及び／又はＣｅの含有率（ｍｏｌ％）が前記結晶子Ａの酸化物中の含有率（ｍｏｌ％）とは異なる結晶子Ｂと、
が混在した酸化物粒子から構成されており、
ここで前記酸化物粒子の１１５０℃、５時間の大気中での熱処理後における比表面積が３５ｍ２／ｇ以上であることを特徴とする、排ガス浄化用触媒。 An exhaust gas purifying catalyst that is disposed in an exhaust pipe of an internal combustion engine and purifies exhaust gas discharged from the internal combustion engine,
A catalyst metal that functions as an oxidation catalyst and / or a reduction catalyst, and a carrier that supports the metal,
The support includes a support made of an oxide that functions as an OSC material.
A crystallite A composed of an oxide containing at least one of zirconium (Zr) and cerium (Ce);
A crystallite B made of an oxide containing at least one of zirconium (Zr) and cerium (Ce), wherein the content (mol%) of Zr and / or Ce in the oxide is that of the crystallite A. A crystallite B different from the content (mol%) in the oxide;
Is composed of mixed oxide particles,
The exhaust gas purifying catalyst, wherein the oxide particles have a specific surface area of 35 m 2 / g or more after heat treatment in air at 1150 ° C. for 5 hours.
前記結晶子Ｂを構成する酸化物に含まれるＣｅの含有率は酸化物換算で該酸化物全体の２０〜９９ｍｏｌ％である、請求項２に記載の排ガス浄化用触媒。 The content of Zr contained in the oxide constituting the crystallite A is 75 to 99 mol% of the whole oxide in terms of oxide,
The exhaust gas-purifying catalyst according to claim 2, wherein the content of Ce contained in the oxide constituting the crystallite B is 20 to 99 mol% of the whole oxide in terms of oxide.
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