JP2015223560A - NOx OCCLUSION REDUCTION CATALYST AND METHOD FOR PRODUCING THE SAME - Google Patents
NOx OCCLUSION REDUCTION CATALYST AND METHOD FOR PRODUCING THE SAME Download PDFInfo
- Publication number
- JP2015223560A JP2015223560A JP2014110198A JP2014110198A JP2015223560A JP 2015223560 A JP2015223560 A JP 2015223560A JP 2014110198 A JP2014110198 A JP 2014110198A JP 2014110198 A JP2014110198 A JP 2014110198A JP 2015223560 A JP2015223560 A JP 2015223560A
- Authority
- JP
- Japan
- Prior art keywords
- compound
- catalyst
- supported
- porous carrier
- nox
- 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.)
- Granted
Links
Abstract
Description
本発明は、ＮＯｘ吸蔵還元型触媒及びその製造方法に関する。 The present invention relates to a NOx storage reduction catalyst and a method for producing the same.
従来から、ディーゼルエンジン、燃料消費率の低い希薄燃焼式（リーンバーン）エンジン等の内燃機関から排出される排ガス中に含まれる窒素酸化物（ＮＯｘ）を浄化するために、リーン雰囲気でＮＯｘを触媒上の吸着材（ＢａやＫなど）に吸蔵し、触媒を還元雰囲気に短時間晒す（間欠的にリッチ雰囲気とする）ことで吸蔵されたＮＯｘを放出して還元するＮＯｘ吸蔵還元触媒（吸蔵還元型ＮＯｘ触媒、ＮＳＲ触媒：ＮＯｘ Ｓｔｏｒａｇｅ Ｒｅｄｕｃｔｉｏｎ ｃａｔａｌｙｓｔｓ）システムなどが開発されている。 Conventionally, NOx has been catalyzed in a lean atmosphere in order to purify nitrogen oxides (NOx) contained in exhaust gas discharged from internal combustion engines such as diesel engines and lean burn engines with low fuel consumption. The NOx occlusion reduction catalyst (occlusion reduction) which occludes in the upper adsorbent (Ba, K, etc.) and releases the NOx occluded by exposing the catalyst to the reducing atmosphere for a short time (intermittently rich atmosphere) to reduce the occluded NOx Type NOx catalyst, NSR catalyst: NOx Storage Reduction catalysts) system and the like have been developed.
特表２００２−５４２０２９号公報（特許文献１）には、排ガスを処理するためのＮＯｘ補足剤として、担体と、Ｍｎ元素及びアルカリ土類金属元素を基材とする活性相とを含む組成物が記載されており、この組成物は、Ｍｎの塩及びアルカリ土類金属の塩を用い、担体に、Ｍｎ元素及びアルカリ土類金属元素をこの順で逐次的に担持せしめて製造されることが記載されている。 JP-T-2002-542029 (Patent Document 1) discloses a composition containing a support and an active phase based on Mn element and alkaline earth metal element as a NOx supplement for treating exhaust gas. The composition is manufactured by using Mn salt and alkaline earth metal salt, and supporting Mn element and alkaline earth metal element on the support sequentially in this order. Has been.
また、特開平８−２８１１１１号公報（特許文献２）及び特開平１１−２７６８９６号公報（特許文献３）には、Ｍｎ化合物を含有する触媒にＢａ溶液を含浸させ、焼成することによってＢａ化合物を担持せしめる排ガス浄化用触媒の製造方法が記載されている。 Japanese Patent Application Laid-Open No. 8-281111 (Patent Document 2) and Japanese Patent Application Laid-Open No. 11-276896 (Patent Document 3) impregnate a Ba compound into a catalyst containing an Mn compound and calcinate the Ba compound. A method for producing a supported exhaust gas purifying catalyst is described.
しかしながら、特許文献１に記載の組成物を含有する触媒や特許文献２〜３に記載の排ガス浄化用触媒は、ＮＯｘ浄化活性が十分に高いものではなかった。 However, the catalyst containing the composition described in Patent Document 1 and the exhaust gas purifying catalyst described in Patent Documents 2 to 3 have not sufficiently high NOx purification activity.
本発明は、上記従来技術の有する課題に鑑みてなされたものであり、高いＮＯｘ吸蔵性能を有し、ＮＯｘ浄化性能に優れたＮＯｘ吸蔵還元型触媒を提供することを目的とする。 The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a NOx occlusion reduction type catalyst having high NOx occlusion performance and excellent NOx purification performance.
本発明者らは、上記目的を達成すべく鋭意研究を重ねた結果、特許文献１に記載の組成物を含有する触媒や特許文献２〜３に記載の排ガス浄化用触媒において、アルカリ土類金属元素は十分に均一に分散担持されておらず、その結果、十分に高いＮＯｘ浄化活性が得られていないことを見出した。そして、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物とＭｎ化合物とを多孔質担体に同時に担持せしめることによって、前記アルカリ化合物及びＭｎ化合物が前記多孔質担体上に均一に分散担持されることを見出し、更に、このようにして得られる触媒が高いＮＯｘ吸蔵性性能を有し、ＮＯｘ浄化性能に優れたものであることを見出し、本発明を完成するに至った。 As a result of intensive studies to achieve the above object, the present inventors have found that the alkaline earth metal in the catalyst containing the composition described in Patent Document 1 and the exhaust gas purifying catalyst described in Patent Documents 2 and 3 It has been found that the elements are not sufficiently uniformly dispersed and supported, and as a result, a sufficiently high NOx purification activity is not obtained. And by carrying simultaneously the alkali compound and Mn compound containing at least 1 sort (s) selected from the group which consists of an alkali metal element and an alkaline-earth metal element on a porous support, the above-mentioned alkali compound and Mn compound are the above-mentioned It was found that the catalyst was uniformly dispersed and supported on the porous carrier, and furthermore, the catalyst obtained in this way had high NOx occlusion performance and was excellent in NOx purification performance. It came to be completed.
すなわち、本発明のＮＯｘ吸蔵還元型触媒は、Ａｌ、Ｚｒ、Ｔｉ、Ｃｅ、Ｍｇ及びＳｉからなる群から選択される少なくとも１種の元素を含む酸化物からなる多孔質担体と、前記多孔質担体に担持されている、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物と、前記多孔質担体に担持されているＭｎ化合物とを備えるＮＯｘ吸蔵還元型触媒であり、
前記触媒表面上の無作為に抽出した２０点以上の測定点において、ＴＥＭ−ＥＤＸ分析により求められる、全無機金属元素に対するアルカリ金属元素及びアルカリ土類金属元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下であり、かつ、全無機金属元素に対するＭｎ元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下であることを特徴とするものである。
That is, the NOx occlusion reduction type catalyst of the present invention comprises a porous carrier comprising an oxide containing at least one element selected from the group consisting of Al, Zr, Ti, Ce, Mg and Si, and the porous carrier. NOx occlusion reduction comprising an alkali compound containing at least one element selected from the group consisting of an alkali metal element and an alkaline earth metal element and a Mn compound supported on the porous carrier. Type catalyst,
The coefficient of variation of the content ratio of the alkali metal element and the alkaline earth metal element to the total inorganic metal elements obtained by TEM-EDX analysis at 20 or more randomly extracted measurement points on the catalyst surface (content ratio The standard deviation / average content ratio) is 0.9 or less, and the variation coefficient of the Mn element content ratio relative to all inorganic metal elements (standard deviation of content ratio / average content ratio) is 0.9 or less. It is characterized by being.
さらに、本発明のＮＯｘ吸蔵還元型触媒においては、前記多孔質担体に担持されている、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｕ、Ａｇ、Ｃｕ、Ｃｏ、Ｎｉ、Ｖ、Ｎｂ、Ｍｏ及びＷからなる群から選択される少なくとも１種の活性金属元素を含む化合物を更に備えることが好ましい。 Furthermore, the NOx storage reduction catalyst of the present invention comprises Pt, Pd, Rh, Ir, Au, Ag, Cu, Co, Ni, V, Nb, Mo, and W supported on the porous carrier. It is preferable to further comprise a compound containing at least one active metal element selected from the group.
また、本発明のＮＯｘ吸蔵還元型触媒の製造方法は、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素とＭｎ元素と多座配位子とを含有する水溶性前駆体溶液を用いて、Ａｌ、Ｚｒ、Ｔｉ、Ｃｅ、Ｍｇ及びＳｉからなる群から選択される少なくとも１種の元素を含む酸化物からなる多孔質担体に、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物とＭｎ化合物とを担持せしめることを特徴とするものである。 Further, the method for producing a NOx occlusion reduction catalyst of the present invention is a water-soluble solution containing at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements, Mn element, and a multidentate ligand. A porous support made of an oxide containing at least one element selected from the group consisting of Al, Zr, Ti, Ce, Mg and Si, using an alkaline precursor solution, and an alkali metal element and an alkaline earth metal An alkali compound containing at least one element selected from the group consisting of elements and a Mn compound are supported.
さらに、本発明のＮＯｘ吸蔵還元型触媒の製造方法においては、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｕ、Ａｇ、Ｃｕ、Ｃｏ、Ｎｉ、Ｖ、Ｎｂ、Ｍｏ及びＷからなる群から選択される少なくとも１種の活性金属元素を含有する水溶液を用いて、前記多孔質担体に、前記活性金属元素を含む化合物を担持せしめた後、前記アルカリ化合物と前記Ｍｎ化合物とを担持せしめること、或いは、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｕ、Ａｇ、Ｃｕ、Ｃｏ、Ｎｉ、Ｖ、Ｎｂ、Ｍｏ及びＷからなる群から選択される少なくとも１種の活性金属元素を更に含有する前記水溶性前駆体溶液を用いて、前記多孔質担体に、前記アルカリ化合物と前記Ｍｎ化合物と前記活性金属元素を含む化合物とを担持せしめることが好ましい。 Furthermore, in the method for producing a NOx storage reduction catalyst of the present invention, at least one selected from the group consisting of Pt, Pd, Rh, Ir, Au, Ag, Cu, Co, Ni, V, Nb, Mo, and W. Using an aqueous solution containing a seed active metal element, after the compound containing the active metal element is supported on the porous carrier, the alkali compound and the Mn compound are supported, or Pt, Pd Rh, Ir, Au, Ag, Cu, Co, Ni, V, Nb, Mo, and the water-soluble precursor solution further containing at least one active metal element selected from the group consisting of W, It is preferable to carry the alkali compound, the Mn compound and the compound containing the active metal element on the porous carrier.
なお、本発明のＮＯｘ吸蔵還元型触媒において、ＮＯｘ吸蔵性能が高くなり、ＮＯｘ浄化性能が向上する理由は必ずしも定かではないが、本発明者らは以下のように推察する。すなわち、本発明のＮＯｘ吸蔵還元型触媒においては、ＮＯの酸化に有効なＭｎ化合物とＮＯｘの吸蔵に有効なアルカリ化合物とが触媒表面に均一に分散した状態で担持されているため、図１に示すように、Ｍｎ化合物１によるＮＯの酸化が触媒表面全体にわたって起こり、さらに、生成したＮＯｘがアルカリ化合物２によって触媒表面全体にわたって吸蔵されるため、ＮＯｘ吸蔵性能が向上すると推察される。そして、本発明のＮＯｘ吸蔵還元型触媒においては、触媒表面全体にわたってＮＯｘが吸蔵されているため、リッチ還元時には触媒表面全体にわたってＮＯｘが還元され、優れたＮＯｘ浄化性能が発揮されると推察される。なお、図１中の「▽」は、吸蔵されていることを意味する。 In the NOx occlusion reduction type catalyst of the present invention, the reason why the NOx occlusion performance is increased and the NOx purification performance is improved is not necessarily clear, but the present inventors speculate as follows. That is, in the NOx occlusion reduction type catalyst of the present invention, the Mn compound effective for NO oxidation and the alkali compound effective for NOx occlusion are supported in a uniformly dispersed state on the catalyst surface. As shown, since oxidation of NO by the Mn compound 1 occurs over the entire catalyst surface, and the generated NOx is occluded over the entire catalyst surface by the alkali compound 2, it is presumed that the NOx occlusion performance is improved. In the NOx occlusion reduction type catalyst of the present invention, since NOx is occluded over the entire catalyst surface, it is presumed that NOx is reduced over the entire catalyst surface during rich reduction, and excellent NOx purification performance is exhibited. . Note that “▽” in FIG. 1 means occlusion.
他方、Ｍｎ化合物が触媒表面に均一に分散した状態で担持されていない場合には、Ｍｎ化合物によるＮＯの酸化が触媒表面全体にわたって起こらず、ＮＯｘの生成量が低下するため、アルカリ化合物によるＮＯｘの吸蔵量が少なくなり、リッチ還元時において還元されるＮＯｘが少なく、ＮＯｘ浄化性能が低下すると推察される。 On the other hand, when the Mn compound is not supported in a uniformly dispersed state on the catalyst surface, NO oxidation by the Mn compound does not occur over the entire catalyst surface, and the amount of NOx produced decreases, so that the NOx produced by the alkali compound decreases. It is presumed that the amount of occlusion decreases, the amount of NOx reduced during rich reduction decreases, and the NOx purification performance decreases.
また、アルカリ化合物が触媒表面に均一に分散した状態で担持されていない場合には、Ｍｎ化合物によるＮＯの酸化で生成したＮＯｘが触媒表面全体にわたって十分に吸蔵されずに放出されるため、ＮＯｘの吸蔵量が少なく、ＮＯｘ浄化性能が低下すると推察される。 Further, when the alkali compound is not supported in a uniformly dispersed state on the catalyst surface, NOx generated by oxidation of NO by the Mn compound is released without being fully occluded over the entire catalyst surface. It is presumed that the amount of occlusion is small and the NOx purification performance decreases.
本発明によれば、高いＮＯｘ吸蔵性性能を有し、ＮＯｘ浄化性能に優れたＮＯｘ吸蔵還元型触媒を提供することが可能となる。 According to the present invention, it is possible to provide a NOx occlusion reduction type catalyst having high NOx occlusion performance and excellent NOx purification performance.
以下、本発明をその好適な実施形態に即して詳細に説明する。先ず、本発明のＮＯｘ吸蔵還元型触媒について説明する。本発明のＮＯｘ吸蔵還元型触媒は、
Ａｌ、Ｚｒ、Ｔｉ、Ｃｅ、Ｍｇ及びＳｉからなる群から選択される少なくとも１種の元素を含む酸化物からなる多孔質担体と、前記多孔質担体に担持されている、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物と、前記多孔質担体に担持されているＭｎ化合物とを備えるＮＯｘ吸蔵還元型触媒であり、
前記触媒表面上の無作為に抽出した２０点以上の測定点において、ＴＥＭ−ＥＤＸ分析により求められる、全無機金属元素に対するアルカリ金属元素及びアルカリ土類金属元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下であり、かつ、全無機金属元素に対するＭｎ元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下であるものである。
Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof. First, the NOx storage reduction catalyst of the present invention will be described. The NOx occlusion reduction type catalyst of the present invention is
A porous carrier comprising an oxide containing at least one element selected from the group consisting of Al, Zr, Ti, Ce, Mg and Si; and an alkali metal element and an alkaline earth supported on the porous carrier. A NOx occlusion reduction catalyst comprising an alkali compound containing at least one element selected from the group consisting of metalloid elements and a Mn compound supported on the porous carrier;
The coefficient of variation of the content ratio of the alkali metal element and the alkaline earth metal element to the total inorganic metal elements obtained by TEM-EDX analysis at 20 or more randomly extracted measurement points on the catalyst surface (content ratio The standard deviation / average content ratio) is 0.9 or less, and the variation coefficient of the Mn element content ratio relative to all inorganic metal elements (standard deviation of content ratio / average content ratio) is 0.9 or less. It is what is.
（多孔質担体）
本発明にかかる多孔質担体は、Ａｌ、Ｚｒ、Ｔｉ、Ｃｅ、Ｍｇ及びＳｉからなる群から選択される少なくとも１種の元素を含む酸化物からなるものである。前記酸化物としては、アルミナ、ジルコニア、チタニア、セリア、酸化マグネシウム、シリカ、及びこれらの複合酸化物が挙げられる。このような酸化物は、１種を単独で使用しても２種以上を併用してもよい。また、このような酸化物のうち、耐久性に優れているという観点から、アルミナ、ジルコニア、及びこれらを含む複合酸化物（例えば、アルミナ−ジルコニア−セリア複合酸化物、アルミナ−ジルコニア−チタニア−セリア複合酸化物等）が好ましい。
(Porous carrier)
The porous carrier according to the present invention is made of an oxide containing at least one element selected from the group consisting of Al, Zr, Ti, Ce, Mg, and Si. Examples of the oxide include alumina, zirconia, titania, ceria, magnesium oxide, silica, and composite oxides thereof. Such an oxide may be used individually by 1 type, or may use 2 or more types together. Among these oxides, from the viewpoint of excellent durability, alumina, zirconia, and composite oxides containing these (for example, alumina-zirconia-ceria composite oxide, alumina-zirconia-titania-ceria) Complex oxides) are preferred.
また、本発明にかかる多孔質担体の形状としては、特に制限されないが、触媒担体の比表面積がより増加し、より高いＮＯｘ吸蔵性能及びＮＯｘ浄化性能が得られるという観点から、粉末状であることが好ましい。多孔質担体が粉末状である場合における多孔質担体の平均粒子径としては、１〜１００μｍが好ましく、５〜５０μｍがより好ましい。多孔質担体の平均粒子径が前記下限未満になると、多孔質担体の微細化にコストがかかるとともに、その取扱いが困難となる傾向にあり、他方、前記上限を超えると、多孔質担体を基材に安定に固定することが困難となる傾向にある。 Further, the shape of the porous carrier according to the present invention is not particularly limited, but is in the form of powder from the viewpoint that the specific surface area of the catalyst carrier is further increased and higher NOx occlusion performance and NOx purification performance can be obtained. Is preferred. When the porous carrier is in the form of powder, the average particle diameter of the porous carrier is preferably 1 to 100 μm, more preferably 5 to 50 μm. If the average particle diameter of the porous carrier is less than the lower limit, it tends to be costly to make the porous carrier fine and difficult to handle. On the other hand, if the average particle diameter exceeds the upper limit, the porous carrier is used as a base material. It tends to be difficult to fix it stably.
さらに、前記多孔質担体の比表面積としては、特に制限されないが、１００ｍ２／ｇ以上が好ましい。多孔質担体の比表面積が前記下限未満になると、ＮＯ酸化サイトやＮＯｘ吸蔵サイトの量が減少し、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する傾向にある。なお、このような比表面積は、窒素吸着等温線からＢＥＴ等温吸着式を用いてＢＥＴ比表面積として算出することができる。 Furthermore, the specific surface area of the porous carrier is not particularly limited, but is preferably 100 m 2 / g or more. When the specific surface area of the porous carrier is less than the lower limit, the amount of NO oxidation sites and NOx storage sites decreases, and the NOx storage performance and NOx purification performance tend to be reduced. In addition, such a specific surface area can be calculated as a BET specific surface area from a nitrogen adsorption isotherm using a BET isotherm adsorption formula.
また、前記多孔質担体の平均細孔直径としては、特に制限されないが、５〜３０ｎｍであることが好ましく、５〜２０ｎｍであることが特に好ましい。多孔質担体の平均細孔直径が前記下限未満になると、細孔内のガス拡散性が低下し、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する傾向にあり、他方、前記上限を超えると、多孔質担体の比表面積が低下し、ＮＯ酸化サイトやＮＯｘ吸蔵サイトの量が減少するため、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する傾向にある。このような平均細孔直径は、窒素吸着等温線を測定し、ＢＪＨ法により細孔径分布曲線を作成することによって求めることができる。 Further, the average pore diameter of the porous carrier is not particularly limited, but is preferably 5 to 30 nm, and particularly preferably 5 to 20 nm. When the average pore diameter of the porous carrier is less than the lower limit, gas diffusibility in the pores tends to be reduced, and NOx occlusion performance and NOx purification performance tend to be reduced. Since the specific surface area of the carrier decreases and the amount of NO oxidation sites and NOx storage sites decreases, the NOx storage performance and the NOx purification performance tend to decrease. Such average pore diameter can be determined by measuring a nitrogen adsorption isotherm and creating a pore diameter distribution curve by the BJH method.
このような多孔質担体の製造方法は、特に制限されず、公知の方法を適宜採用することができる。また、市販の複合酸化物を多孔質担体として使用してもよい。 The method for producing such a porous carrier is not particularly limited, and a known method can be appropriately employed. A commercially available composite oxide may be used as the porous carrier.
また、このような多孔質担体が粉末状である場合、本発明のＮＯｘ吸蔵還元型触媒においては、粉末状の多孔質担体を、そのまま使用してもよいし、ペレット状に成形して使用してもよいし、基材上に固定せしめて使用してもよい。前記基材の形状としては特に制限されず、ペレット状、ハニカム状等の公知の形状を適宜採用することができるが、好ましい基材としては、ＤＰＦ基材、モノリス状基材、ペレット状基材、プレート状基材等が挙げられる。また、基材の材質としては特に制限されないが、コーディエライト、炭化ケイ素、ムライト等のセラミックスからなる基材や、クロム及びアルミニウムを含むステンレススチール等の金属からなる基材がより好ましい。 In addition, when such a porous carrier is in a powder form, the powdery porous carrier may be used as it is in the NOx occlusion reduction type catalyst of the present invention or used after being formed into a pellet. You may use it, fixing on a base material. The shape of the base material is not particularly limited, and a known shape such as a pellet shape or a honeycomb shape can be appropriately employed. Preferred base materials include a DPF base material, a monolithic base material, and a pellet base material. And a plate-like substrate. The material of the base material is not particularly limited, but a base material made of a ceramic such as cordierite, silicon carbide, mullite, or a base material made of a metal such as stainless steel including chromium and aluminum is more preferable.
本発明にかかる多孔質担体を基材上に固定せしめる場合、前記基材容量１Ｌあたりの前記多孔質担体の固定量としては、５０〜３００ｇ／Ｌが好ましく、１００〜２００ｇ／Ｌがより好ましい。多孔質担体の固定量が前記下限未満になると、アルカリ化合物やＭｎ化合物を均一に分散担持せしめることが困難となる傾向にあり、他方、前記上限を超えると、基材の細孔が閉塞して圧損が生じたり、基材から多孔質担体が脱離しやすくなる傾向にある。 When the porous carrier according to the present invention is immobilized on a substrate, the amount of the porous carrier immobilized per 1 L of the substrate volume is preferably 50 to 300 g / L, more preferably 100 to 200 g / L. When the fixed amount of the porous carrier is less than the lower limit, it tends to be difficult to uniformly disperse and support the alkali compound or Mn compound. On the other hand, when the upper limit is exceeded, the pores of the base material are blocked. There is a tendency that pressure loss occurs or the porous carrier is easily detached from the substrate.
（アルカリ化合物）
本発明のＮＯｘ吸蔵還元型触媒においては、このような多孔質担体にアルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物が担持されている。このようなアルカリ化合物はＮＯｘの吸蔵に有効な成分である。前記アルカリ金属元素及びアルカリ土類金属元素の中でも、ＮＯｘの吸蔵性能に優れているという観点から、Ｂａ、Ｓｒ、Ｎａ、Ｋが好ましく、Ｂａ、Ｋがより好ましい。本発明にかかるアルカリ化合物の形態としては、炭酸塩、前記多孔質担体を構成する前記元素との複合酸化物、Ｍｎ元素との複合酸化物が挙げられる。
(Alkali compounds)
In the NOx occlusion reduction type catalyst of the present invention, an alkaline compound containing at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements is supported on such a porous carrier. Such an alkali compound is an effective component for storing NOx. Among the alkali metal elements and alkaline earth metal elements, Ba, Sr, Na, and K are preferable, and Ba and K are more preferable from the viewpoint of excellent NOx storage performance. Examples of the form of the alkali compound according to the present invention include carbonates, composite oxides with the elements constituting the porous carrier, and composite oxides with Mn elements.
本発明にかかるアルカリ化合物は、結晶構造を有するものであることが好ましい。このような結晶構造は、Ｘ線回折（ＸＲＤ）測定で得られるＸＲＤスペクトル中にアルカリ化合物に由来する回折ピークが存在することによって確認することができる。 The alkali compound according to the present invention preferably has a crystal structure. Such a crystal structure can be confirmed by the presence of a diffraction peak derived from an alkali compound in the XRD spectrum obtained by X-ray diffraction (XRD) measurement.
また、前記アルカリ化合物の形状として特に制限はないが、微粒子状であることが好ましく、その平均粒子径としては３０ｎｍ以下が好ましく、２０ｎｍ以下がより好ましい。アルカリ化合物微粒子の平均粒子径が前記上限を超えると、アルカリ化合物を前記多孔質担体上に十分に均一に分散担持させることが困難となる傾向にある。 Moreover, there is no restriction | limiting in particular as a shape of the said alkali compound, However, It is preferable that it is fine particle shape, As the average particle diameter, 30 nm or less is preferable and 20 nm or less is more preferable. When the average particle diameter of the alkali compound fine particles exceeds the upper limit, it tends to be difficult to disperse and carry the alkali compound on the porous carrier sufficiently uniformly.
本発明のＮＯｘ吸蔵還元型触媒においては、このようなアルカリ化合物が微細かつ均一に分散担持されている必要がある。具体的には、触媒表面上の無作為に抽出した２０点以上の測定点において、ＴＥＭ−ＥＤＸ法による元素分析（ＴＥＭ−ＥＤＸ分析）により求められる、全無機金属元素に対するアルカリ金属元素及びアルカリ土類金属元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下である必要があり、０．８以下であることが好ましく、０．５以下であることがより好ましい。前記変動係数が前記上限を超えると、アルカリ化合物が十分に均一に分散担持されておらず、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する。このような元素の変動係数は、具体的には以下の方法により求めることができる。すなわち、触媒表面上の無作為に抽出した２０点以上の測定点（１０ｎｍ×１０ｎｍの領域を１つの測定点とする）において、エネルギー分散型Ｘ線分光器を装備した走査透過型電子顕微鏡（ＴＥＭ−ＥＤＸ分析装置）を用いてエネルギー分散型の蛍光Ｘ線スペクトルを測定する。各測定点において、得られたエネルギー分散型の蛍光Ｘ線スペクトルから、その測定点内に存在する元素の種類を求め、各元素に由来する蛍光Ｘ線スペクトルのピーク面積を求める。このピーク面積に基いて、各測定点内に存在する各元素の含有割合を求める。このようにして求めた、すべての測定点における元素の含有割合から、各元素について、触媒中の元素の含有割合の標準偏差と平均値（平均濃度）を求め、下記式（１）：
［変動係数］＝［含有割合の標準偏差］／［含有割合の平均値］ （１）
に基づいて、各元素の含有割合の変動係数を求める。なお、「ピーク面積」とは、ベースラインとピークとの間の面積をいい、市販のソフト（例えば、ＯｒｉｇｉｎＬａｂ社製の商品名「Ｏｒｉｇｉｎ」等）を利用して求めることができる。
In the NOx occlusion reduction type catalyst of the present invention, such an alkali compound needs to be finely and uniformly dispersed and supported. Specifically, alkali metal elements and alkaline earths with respect to all inorganic metal elements obtained by elemental analysis by TEM-EDX method (TEM-EDX analysis) at 20 or more randomly selected measurement points on the catalyst surface. The variation coefficient (standard deviation of content ratio / average value of content ratio) of the content ratio of the metal group element must be 0.9 or less, preferably 0.8 or less, and 0.5 or less Is more preferable. When the coefficient of variation exceeds the upper limit, the alkali compound is not sufficiently uniformly dispersed and supported, and the NOx storage performance and the NOx purification performance are deteriorated. Specifically, the coefficient of variation of such an element can be obtained by the following method. That is, a scanning transmission electron microscope (TEM) equipped with an energy dispersive X-ray spectrometer at 20 or more randomly selected measurement points on the catalyst surface (with a 10 nm × 10 nm region as one measurement point). An energy dispersive X-ray fluorescence spectrum is measured using an EDX analyzer. At each measurement point, the type of element present in the measurement point is obtained from the obtained energy dispersive fluorescent X-ray spectrum, and the peak area of the fluorescent X-ray spectrum derived from each element is obtained. Based on this peak area, the content ratio of each element present in each measurement point is determined. The standard deviation and average value (average concentration) of the content ratio of the elements in the catalyst were determined for each element from the content ratios of the elements at all measurement points thus obtained, and the following formula (1):
[Coefficient of variation] = [Standard deviation of content ratio] / [Average value of content ratio] (1)
Based on the above, the variation coefficient of the content ratio of each element is obtained. The “peak area” refers to the area between the baseline and the peak, and can be obtained using commercially available software (for example, “Origin”, a product name manufactured by OriginLab).
また、本発明のＮＯｘ吸蔵還元型触媒において、前記アルカリ化合物の担持量としては、前記多孔質担体が前記基材に固定されている場合、前記基材１Ｌに対してアルカリ金属元素及びアルカリ土類金属元素の量に換算して０．０５〜１．０ｍｏｌ／Ｌが好ましく、０．１〜０．５ｍｏｌ／Ｌがより好ましい。アルカリ化合物の担持量が前記下限未満になると、十分なＮＯｘ吸蔵性能が得られない傾向があり、他方、前記上限を超えると、多孔質担体の細孔が閉塞して十分な比表面積が得られず、十分なＮＯｘ吸蔵性能やＮＯｘ浄化性能が得られない傾向がある。 Further, in the NOx occlusion reduction type catalyst of the present invention, the supported amount of the alkali compound is that when the porous carrier is fixed to the substrate, an alkali metal element and an alkaline earth with respect to the substrate 1L. In terms of the amount of the metal element, 0.05 to 1.0 mol / L is preferable, and 0.1 to 0.5 mol / L is more preferable. If the supported amount of the alkali compound is less than the lower limit, sufficient NOx storage performance tends to be not obtained. On the other hand, if the upper limit is exceeded, pores of the porous carrier are blocked and a sufficient specific surface area is obtained. Therefore, there is a tendency that sufficient NOx occlusion performance and NOx purification performance cannot be obtained.
（Ｍｎ化合物）
本発明のＮＯｘ吸蔵還元型触媒においては、前記多孔質担体にＭｎ化合物が更に担持されている。このようなＭｎ化合物はＮＯの酸化に有効な成分である。本発明にかかるＭｎ化合物の形態としては、酸化物、前記多孔質担体を構成する前記元素との複合酸化物、前記アルカリ金属元素との複合酸化物、前記アルカリ土類金属元素との複合酸化物が挙げられる。
(Mn compound)
In the NOx occlusion reduction type catalyst of the present invention, a Mn compound is further supported on the porous carrier. Such Mn compounds are effective components for NO oxidation. As the form of the Mn compound according to the present invention, an oxide, a complex oxide with the element constituting the porous carrier, a complex oxide with the alkali metal element, a complex oxide with the alkaline earth metal element Is mentioned.
本発明にかかるＭｎ化合物は非晶質であることが好ましい。Ｍｎ化合物が非晶質であることについては、Ｘ線回折（ＸＲＤ）測定で得られるＸＲＤスペクトル中にＭｎ化合物に由来する回折ピークが観察されないことによって確認することができる。Ｍｎ化合物が非晶質である場合、Ｍｎ化合物は、多孔質担体上で、後述する活性金属元素を含む化合物と相互作用しやすく、より高いＮＯ酸化性能を発現することが可能となる。 The Mn compound according to the present invention is preferably amorphous. The fact that the Mn compound is amorphous can be confirmed by the fact that a diffraction peak derived from the Mn compound is not observed in the XRD spectrum obtained by X-ray diffraction (XRD) measurement. When the Mn compound is amorphous, the Mn compound easily interacts with a compound containing an active metal element described later on the porous carrier, and can exhibit higher NO oxidation performance.
また、Ｍｎ化合物の形状として特に制限はないが、微粒子状であることが好ましく、その平均粒子径としては１０ｎｍ以下（ＸＲＤによる検出限界以下）が好ましい。Ｍｎ化合物微粒子の平均粒子径が前記上限を超えると、ＮＯ酸化サイトが減少する傾向にある。 The shape of the Mn compound is not particularly limited, but is preferably in the form of fine particles, and the average particle size is preferably 10 nm or less (below the detection limit by XRD). When the average particle diameter of the Mn compound fine particles exceeds the upper limit, NO oxidation sites tend to decrease.
本発明のＮＯｘ吸蔵還元型触媒においては、このようなＭｎ化合物が微細かつ均一に分散担持されている必要がある。具体的には、触媒表面上の無作為に抽出した２０点以上の測定点において、ＴＥＭ−ＥＤＸ法による元素分析（ＴＥＭ−ＥＤＸ分析）により求められる、全無機金属元素に対するＭｎ元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下である必要があり、０．８以下であることが好ましく、０．５以下であることがより好ましい。前記変動係数が前記上限を超えると、Ｍｎ化合物が十分に均一に分散担持されておらず、ＮＯ酸化性能が低下し、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する。このようなＭｎ元素の変動係数は、前述したアルカリ金属元素及びアルカリ土類金属元素の含有割合の変動係数と同様の方法により求めることができる。 In the NOx occlusion reduction type catalyst of the present invention, such a Mn compound needs to be finely and uniformly dispersed and supported. Specifically, the content ratio of the Mn element with respect to the total inorganic metal elements obtained by elemental analysis by the TEM-EDX method (TEM-EDX analysis) at 20 or more randomly selected measurement points on the catalyst surface. The coefficient of variation (standard deviation of content ratio / average value of content ratio) needs to be 0.9 or less, preferably 0.8 or less, and more preferably 0.5 or less. When the variation coefficient exceeds the upper limit, the Mn compound is not sufficiently uniformly dispersed and supported, the NO oxidation performance is lowered, and the NOx storage performance and the NOx purification performance are lowered. Such a variation coefficient of the Mn element can be obtained by the same method as the variation coefficient of the content ratio of the alkali metal element and the alkaline earth metal element described above.
また、本発明のＮＯｘ吸蔵還元型触媒において、前記Ｍｎ化合物の担持量としては、前記多孔質担体が前記基材に固定されている場合、前記基材１Ｌに対してＭｎ元素の量に換算して０．０５〜１．０ｍｏｌ／Ｌが好ましく、０．１〜０．５ｍｏｌ／Ｌがより好ましい。Ｍｎ化合物の担持量が前記下限未満になると、十分なＮＯ酸化性能が得られず、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する傾向があり、他方、前記上限を超えると、多孔質担体の細孔が閉塞して十分な比表面積が得られず、十分なＮＯｘ吸蔵性能やＮＯｘ浄化性能が得られない傾向がある。 In the NOx occlusion reduction catalyst of the present invention, the supported amount of the Mn compound is converted to the amount of Mn element with respect to 1 L of the base material when the porous carrier is fixed to the base material. 0.05 to 1.0 mol / L is preferable, and 0.1 to 0.5 mol / L is more preferable. If the supported amount of Mn compound is less than the lower limit, sufficient NO oxidation performance cannot be obtained, and NOx occlusion performance and NOx purification performance tend to decrease. On the other hand, if the upper limit is exceeded, pores of the porous carrier However, there is a tendency that a sufficient specific surface area cannot be obtained due to clogging and a sufficient NOx occlusion performance or NOx purification performance cannot be obtained.
（活性金属化合物）
本発明のＮＯｘ吸蔵還元型触媒においては、前記多孔質担体に、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｕ、Ａｇ、Ｃｕ、Ｃｏ、Ｎｉ、Ｖ、Ｎｂ、Ｍｏ及びＷからなる群から選択される少なくとも１種の活性金属元素を含む化合物が更に担持されていることが好ましい。前記活性金属元素の中でも、ＮＯ酸化性能が向上し、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が更に向上するという観点から、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｕ、Ａｇ、Ｃｕがより好ましく、Ｐｔ、Ｐｄ、Ｒｈが更に好ましく、Ｐｔ、Ｒｈが特に好ましく、ＮＯ酸化性能だけでなく、ＮＯｘ還元性能も更に向上するという観点から、Ｒｈが最も好ましい。
(Active metal compound)
In the NOx occlusion reduction type catalyst of the present invention, the porous carrier is at least selected from the group consisting of Pt, Pd, Rh, Ir, Au, Ag, Cu, Co, Ni, V, Nb, Mo and W. It is preferable that a compound containing one kind of active metal element is further supported. Among the active metal elements, Pt, Pd, Rh, Ir, Au, Ag, and Cu are more preferable from the viewpoint of improving NO oxidation performance and further improving NOx storage performance and NOx purification performance, and Pt, Pd, Rh is more preferable, Pt and Rh are particularly preferable, and Rh is most preferable from the viewpoint of further improving not only NO oxidation performance but also NOx reduction performance.
このような活性金属化合物は、空燃比がリーン雰囲気である場合に排ガス中の酸素を利用してＮＯを酸化してＮＯｘとし、空燃比がリッチ雰囲気である場合にＣＯやＨＣ等の還元性ガスと反応させてＮＯｘをＮ２に還元するための触媒成分（活性成分）として機能するものである。また、このような「活性金属化合物」は、ＸＲＤ分析した場合に前記活性金属元素に由来するピークが確認されることにより確認でき、その具体的な形態は、酸化物であってもメタル状であってもよく、前記多孔質担体を構成する元素や前記アルカリ金属元素、前記アルカリ土類金属元素、Ｍｎ元素と結合して化合物を形成していてもよい。 Such an active metal compound uses oxygen in exhaust gas to oxidize NO to NOx when the air-fuel ratio is a lean atmosphere, and reducing gases such as CO and HC when the air-fuel ratio is a rich atmosphere It functions as a catalyst component (active component) for reducing NOx to N 2 by reacting with NO. In addition, such an “active metal compound” can be confirmed by confirming a peak derived from the active metal element when XRD analysis is performed. The compound may be formed by combining with the element constituting the porous carrier, the alkali metal element, the alkaline earth metal element, or the Mn element.
また、活性金属化合物の形状として特に制限はないが、微粒子状であることが好ましく、その平均粒子径としては３０ｎｍ以下が好ましく、２０ｎｍ以下がより好ましい。活性金属化合物微粒子の平均粒子径が前記上限を超えると、十分に高い触媒活性を得ることが困難となる傾向にある。 Moreover, there is no restriction | limiting in particular as a shape of an active metal compound, However, It is preferable that it is a fine particle form, and the average particle diameter is 30 nm or less, and 20 nm or less is more preferable. When the average particle diameter of the active metal compound fine particles exceeds the upper limit, it tends to be difficult to obtain sufficiently high catalytic activity.
本発明のＮＯｘ吸蔵還元型触媒において、前記活性金属化合物の担持量としては、前記多孔質担体が前記基材に固定されている場合、前記基材１Ｌに対して活性金属元素の量に換算して０．１〜１０ｇ／Ｌが好ましく、０．２〜５ｇ／Ｌがより好ましい。活性金属化合物の担持量が前記下限未満になると、活性金属化合物担持によるＮＯ酸化性能及びＮＯｘ還元性能の向上効果が十分に得られない傾向にあり、他方、前記上限を超えると、活性金属化合物が均一に分散担持されにくくなり、ＮＯ酸化性能及びＮＯｘ還元性能が低下する傾向にある。 In the NOx occlusion reduction type catalyst of the present invention, the amount of the active metal compound supported is converted to the amount of the active metal element with respect to the substrate 1L when the porous carrier is fixed to the substrate. 0.1 to 10 g / L is preferable, and 0.2 to 5 g / L is more preferable. When the amount of the active metal compound supported is less than the lower limit, the effect of improving the NO oxidation performance and NOx reduction performance due to the active metal compound tends not to be sufficiently obtained. It becomes difficult to be uniformly dispersed and supported, and the NO oxidation performance and the NOx reduction performance tend to decrease.
次に、本発明のＮＯｘ吸蔵還元型触媒の製造方法について説明する。本発明のＮＯｘ吸蔵還元型触媒の製造方法は、
アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素とＭｎ元素と多座配位子とを含有する水溶性前駆体溶液を用いて、Ａｌ、Ｚｒ、Ｔｉ、Ｃｅ、Ｍｇ及びＳｉからなる群から選択される少なくとも１種の元素を含む酸化物からなる多孔質担体に、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物とＭｎ化合物とを担持せしめる方法である。
Next, a method for producing the NOx storage reduction catalyst of the present invention will be described. The method for producing the NOx storage reduction catalyst of the present invention comprises:
Using a water-soluble precursor solution containing at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements, an Mn element, and a polydentate ligand, Al, Zr, Ti, Ce The porous carrier comprising an oxide containing at least one element selected from the group consisting of Mg and Si contains at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements In this method, an alkali compound and a Mn compound are supported.
本発明のＮＯｘ吸蔵還元型触媒の製造方法においては、本発明にかかる前記多孔質担体に、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素とＭｎ元素と多座配位子とを含有する水溶性前駆体溶液を、各元素が所定の担持量となるように接触せしめ、その後、焼成することによって、前記多孔質担体に本発明にかかる前記アルカリ化合物とＭｎ化合物とを担持せしめる。このように、前記アルカリ化合物とＭｎ化合物とを前記多孔質担体に同時に担持させることによって、前記多孔質担体に前記アルカリ化合物及びＭｎ化合物が微細かつ十分に均一に分散担持され、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能に優れたＮＯｘ吸蔵還元型触媒を得ることが可能となる。 In the method for producing a NOx storage reduction catalyst of the present invention, the porous carrier according to the present invention includes at least one element selected from the group consisting of an alkali metal element and an alkaline earth metal element, an Mn element, A water-soluble precursor solution containing a bidentate ligand is brought into contact with each element so as to have a predetermined loading amount, and then calcined, whereby the above-mentioned alkaline compound and Mn according to the present invention are applied to the porous carrier. The compound is supported. Thus, by simultaneously supporting the alkali compound and the Mn compound on the porous carrier, the alkali compound and the Mn compound are finely and sufficiently uniformly dispersed and supported on the porous carrier, and NOx occlusion performance and NOx are obtained. It is possible to obtain a NOx occlusion reduction type catalyst excellent in purification performance.
また、本発明のＮＯｘ吸蔵還元型触媒の製造方法においては、予め、前記基材に前記多孔質担体を固定せしめた後、上記の方法で前記アルカリ化合物及びＭｎ化合物を担持せしめてもよい。前記基材に前記多孔質担体を固定せしめる方法としては特に制限されず、ウォッシュコート法等の公知の方法を適宜採用することができる。 In the method for producing a NOx storage reduction catalyst of the present invention, the alkali compound and the Mn compound may be supported by the method described above after the porous carrier is fixed to the base material in advance. The method for fixing the porous carrier to the substrate is not particularly limited, and a known method such as a wash coat method can be appropriately employed.
本発明にかかる多座配位子とは、２個以上の配位基で配位し得る配位子をいい、前記アルカリ金属元素やアルカリ土類金属元素、Ｍｎ元素との錯体を形成するものである。また、本発明にかかる水溶性前駆体溶液に含まれるアルカリ金属元素、アルカリ土類金属元素、及びＭｎ元素は、本発明にかかるアルカリ化合物及びＭｎ化合物を構成する元素として説明したものである。このようなアルカリ金属元素、アルカリ土類金属元素、及びＭｎ元素の形態としては、溶媒に溶解して前記多座配位子と錯体を形成するものであれば特に制限されず、例えば、硝酸塩、酢酸塩、炭酸塩等の前記元素の塩、ジニトロジアンミン錯体等の前記元素の錯体、前記元素の水酸化物等を適宜使用することができる。 The polydentate ligand according to the present invention refers to a ligand that can coordinate with two or more coordination groups, and forms a complex with the alkali metal element, alkaline earth metal element, or Mn element. It is. In addition, the alkali metal element, alkaline earth metal element, and Mn element contained in the water-soluble precursor solution according to the present invention are described as elements constituting the alkali compound and the Mn compound according to the present invention. The form of such an alkali metal element, alkaline earth metal element, and Mn element is not particularly limited as long as it dissolves in a solvent to form a complex with the polydentate ligand. For example, nitrate, A salt of the element such as acetate or carbonate, a complex of the element such as a dinitrodiammine complex, a hydroxide of the element, or the like can be appropriately used.
前記多座配位子としては、クエン酸、シュウ酸の多価カルボン酸から少なくとも１つの水素が脱離した残基、グリコール、ピナコール等のジオール類から少なくとも１つの水素が脱離した残基、エチレンジアミン等のジアミン類から少なくとも１つの水素が脱離した残基、アセト酢酸エチル等の２つのカルボニル基を有するエステル類から少なくとも１つの水素が脱離した残基等が挙げられる。このような多座配位子の中でも、クエン酸、シュウ酸、コハク酸、マレイン酸、リンゴ酸、アジピン酸、酒石酸、マロン酸、フマル酸、アコニット酸、グルタル酸、エチレンジアミン四酢酸、乳酸、グリコール酸、グリセリン酸、サリチル酸、メバロン酸、エチレンジアミン、アセト酢酸エチル、マロン酸エステル、グリコール、ピナコールから少なくとも１つの水素が脱離した残基が好ましく、ヒドロキシ基を併せ持つカルボン酸であるという観点から、クエン酸、乳酸、リンゴ酸、酒石酸、グリコール酸、サリチル酸から少なくとも１つの水素が脱離した残基がより好ましく、より微細かつ均一に分散された状態でアルカリ化合物及びＭｎ化合物を担持できるという観点から、クエン酸から少なくとも１つの水素が脱離した残基が特に好ましい。また、このような多座配位子は、１種を単独で使用しても２種以上を併用してもよい。 Examples of the polydentate ligand include residues in which at least one hydrogen is eliminated from a polycarboxylic acid such as citric acid and oxalic acid, residues in which at least one hydrogen is eliminated from diols such as glycol and pinacol, Examples thereof include a residue in which at least one hydrogen is eliminated from diamines such as ethylenediamine, and a residue in which at least one hydrogen is eliminated from esters having two carbonyl groups such as ethyl acetoacetate. Among such polydentate ligands, citric acid, oxalic acid, succinic acid, maleic acid, malic acid, adipic acid, tartaric acid, malonic acid, fumaric acid, aconitic acid, glutaric acid, ethylenediaminetetraacetic acid, lactic acid, glycol From the viewpoint that a residue in which at least one hydrogen is eliminated from an acid, glyceric acid, salicylic acid, mevalonic acid, ethylenediamine, ethyl acetoacetate, malonic acid ester, glycol or pinacol is preferable, and it is a carboxylic acid having a hydroxy group. From the viewpoint that the residue in which at least one hydrogen is eliminated from the acid, lactic acid, malic acid, tartaric acid, glycolic acid, salicylic acid is more preferable, and it can carry the alkali compound and the Mn compound in a more finely and uniformly dispersed state. Particularly preferred are residues from which at least one hydrogen has been eliminated from citric acid. Arbitrariness. Moreover, such a polydentate ligand may be used individually by 1 type, or may use 2 or more types together.
前記多孔質担体に前記水溶性前駆体溶液を接触せしめる方法としては、特に制限されず、前記水溶性前駆体溶液中に前記多孔質担体を浸漬して撹拌する方法、前記水溶性前駆体溶液を前記多孔質担体に含浸担持させる等の公知の方法を適宜採用することができる。また、前記水溶性前駆体溶液に用いられる溶媒としては特に制限されず、水、エタノール等を適宜利用することができ、廃液処理、調製コストの観点から、水が好ましい。 A method for bringing the water-soluble precursor solution into contact with the porous carrier is not particularly limited, and the method of immersing the porous carrier in the water-soluble precursor solution and stirring the water-soluble precursor solution. A known method such as impregnating and supporting the porous carrier can be appropriately employed. Moreover, it does not restrict | limit especially as a solvent used for the said water-soluble precursor solution, Water, ethanol, etc. can be utilized suitably and water is preferable from a viewpoint of a waste liquid process and preparation cost.
このような水溶性前駆体溶液中の各元素の濃度としては、０．１〜２ｍｏｌ／Ｌが好ましく、０．５〜１ｍｏｌ／Ｌがより好ましい。元素の濃度が前記下限未満になると、所定量のアルキル化合物やＭｎ化合物を多孔質担体に担持するためには多孔質担体との接触操作を複数回繰り返す必要があり、製造効率が低下する傾向にあるとともに、複数回の接触操作により元素の再溶出や析出が起こり、アルキル化合物やＭｎ化合物を十分に均一に分散担持させることが困難となる傾向にある。他方、元素の濃度が前記上限を超えると、アルキル化合物やＭｎ化合物を十分に均一に分散担持させることが困難となり、ＮＯｘ吸蔵性能及びＮＯｘ浄化性能が低下する傾向にある。 As a density | concentration of each element in such a water-soluble precursor solution, 0.1-2 mol / L is preferable and 0.5-1 mol / L is more preferable. When the concentration of the element is less than the lower limit, it is necessary to repeat the contact operation with the porous carrier a plurality of times in order to carry a predetermined amount of the alkyl compound or Mn compound on the porous carrier, and the production efficiency tends to decrease. At the same time, re-elution and precipitation of elements occur by a plurality of contact operations, and it tends to be difficult to disperse and carry alkyl compounds and Mn compounds sufficiently uniformly. On the other hand, when the element concentration exceeds the upper limit, it becomes difficult to disperse and carry the alkyl compound and Mn compound sufficiently uniformly, and the NOx occlusion performance and the NOx purification performance tend to be lowered.
また、前記水溶性前駆体溶液中の多座配位子の濃度としては、０．３〜８ｍｏｌ／Ｌが好ましく、１．５〜４ｍｏｌ／Ｌがより好ましい。多座配位子の濃度が前記下限未満になると、アルキル化合物やＭｎ化合物との錯体が形成されにくい傾向にあり、他方、前記上限を超えると、水溶性前駆体溶液としての安定性が低下する傾向にある。 Moreover, as a density | concentration of the polydentate ligand in the said water-soluble precursor solution, 0.3-8 mol / L is preferable and 1.5-4 mol / L is more preferable. When the concentration of the polydentate ligand is less than the lower limit, a complex with an alkyl compound or a Mn compound tends not to be formed. On the other hand, when the concentration exceeds the upper limit, the stability as a water-soluble precursor solution decreases. There is a tendency.
前記多孔質担体に前記水溶性前駆体溶液を接触せしめた後の焼成時の温度条件としては、３００〜６００℃が好ましく、３００〜５５０℃がより好ましい。また、焼成時間としては、２〜１０時間が好ましく、３〜５時間がより好ましい。焼成温度又は焼成時間が前記下限未満になると、多座配位子が十分に分解されず、ＮＯｘ吸蔵性能やＮＯｘ浄化性能が低下する傾向にあり、他方、前記上限を超えると、熱劣化が進行して粒成長が起こり、アルキル化合物やＭｎ化合物を微細かつ十分に均一に分散担持させることが困難となる傾向にある。 As temperature conditions at the time of baking after making the said water-soluble precursor solution contact the said porous support | carrier, 300-600 degreeC is preferable and 300-550 degreeC is more preferable. Moreover, as baking time, 2 to 10 hours are preferable and 3 to 5 hours are more preferable. When the firing temperature or firing time is less than the lower limit, the polydentate ligand is not sufficiently decomposed, and the NOx occlusion performance and NOx purification performance tend to decrease. On the other hand, when the upper limit is exceeded, thermal degradation proceeds. Thus, grain growth occurs, and it tends to be difficult to disperse and carry the alkyl compound and Mn compound finely and sufficiently uniformly.
このように、本発明のＮＯｘ吸蔵還元型触媒の製造方法においては、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素とＭｎ元素と多座配位子とを含有する水溶性前駆体溶液を用いることによって、前記多孔質担体の表面上に微細かつ十分に均一に分散した状態でアルカリ化合物及びＭｎ化合物を担持させることが可能となる。これは、以下の理由による。すなわち、前記水溶性前駆体溶液中において前記の各元素は多座配位子と錯体を形成する。錯体の核に存在する各元素は嵩高い前記多座配位子により離間した状態で多孔質担体上に離間して担持される。その結果、焼成時の元素の凝集が十分に抑制されるため、微細かつ十分に均一に分散した状態でアルカリ化合物及びＭｎ化合物が担持される。 Thus, in the method for producing a NOx storage reduction catalyst of the present invention, at least one element selected from the group consisting of an alkali metal element and an alkaline earth metal element, an Mn element, and a multidentate ligand are included. By using the contained water-soluble precursor solution, it becomes possible to support the alkali compound and the Mn compound in a finely and sufficiently uniformly dispersed state on the surface of the porous carrier. This is due to the following reason. That is, each element described above forms a complex with a polydentate ligand in the water-soluble precursor solution. Each element present in the nucleus of the complex is supported on the porous carrier while being separated by the bulky multidentate ligand. As a result, the aggregation of elements during firing is sufficiently suppressed, so that the alkali compound and the Mn compound are supported in a finely and sufficiently uniformly dispersed state.
また、本発明のＮＯｘ吸蔵還元型触媒の製造方法においては、前記多孔質担体に、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｕ、Ａｇ、Ｃｕ、Ｃｏ、Ｎｉ、Ｖ、Ｎｂ、Ｍｏ及びＷからなる群から選択される少なくとも１種の活性金属元素を含む化合物（活性金属化合物）を担持せしめることが好ましい。 In the method for producing a NOx occlusion reduction catalyst of the present invention, the porous carrier includes the group consisting of Pt, Pd, Rh, Ir, Au, Ag, Cu, Co, Ni, V, Nb, Mo, and W. It is preferable to carry a compound containing at least one active metal element selected from (active metal compound).
前記活性金属化合物を担持せしめる方法としては、前記活性金属元素を含有する水溶液を用いて、前記多孔質担体に前記活性金属化合物を担持せしめた後、前記アルカリ化合物と前記Ｍｎ化合物とを担持せしめる方法（方法１）、或いは、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素とＭｎ元素と多座配位子と、更に前記活性金属元素とを含有する前記水溶性前駆体溶液を用いて、前記多孔質担体に前記アルカリ化合物と前記Ｍｎ化合物と前記活性金属化合物とを担持せしめる方法（方法２）が好ましい。 As a method of supporting the active metal compound, a method of supporting the alkali compound and the Mn compound after supporting the active metal compound on the porous carrier using an aqueous solution containing the active metal element. (Method 1) or the water solution containing at least one element selected from the group consisting of an alkali metal element and an alkaline earth metal element, an Mn element, a polydentate ligand, and the active metal element A method (method 2) in which the alkaline compound, the Mn compound, and the active metal compound are supported on the porous carrier using a conductive precursor solution is preferable.
前記方法１においては、先ず、本発明にかかる前記多孔質担体に前記活性金属元素を含有する水溶液を、前記活性金属元素が所定の担持量となるように接触せしめ、その後、焼成することによって、前記多孔質担体に本発明にかかる前記活性金属化合物を担持せしめる。次に、前述した方法に従って、前記活性金属化合物が担持されている前記多孔質担体に前記アルカリ化合物と前記Ｍｎ化合物とを担持せしめる。 In the method 1, first, an aqueous solution containing the active metal element is brought into contact with the porous carrier according to the present invention so that the active metal element has a predetermined loading amount, and then fired. The active metal compound according to the present invention is supported on the porous carrier. Next, according to the method described above, the alkali compound and the Mn compound are supported on the porous carrier on which the active metal compound is supported.
また、前記方法２においては、本発明にかかる前記多孔質担体に、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素とＭｎ元素と多座配位子と、更に前記活性金属元素とを含有する前記水溶性前駆体溶液を、前述した方法に従って、各元素が所定の担持量となるように接触せしめ、その後、焼成することによって、前記多孔質担体に前記アルカリ化合物と前記Ｍｎ化合物と前記活性金属化合物とを担持せしめる。 In the method 2, the porous carrier according to the present invention includes at least one element selected from the group consisting of an alkali metal element and an alkaline earth metal element, an Mn element, a multidentate ligand, Further, according to the method described above, the water-soluble precursor solution containing the active metal element is brought into contact with each element so as to have a predetermined loading amount, and then calcined, whereby the porous carrier is subjected to the alkali support. A compound, the Mn compound, and the active metal compound are supported.
前記方法１に用いられる水溶液及び前記方法２に用いられる水溶性前駆体溶液に含まれる活性金属元素は、本発明にかかる活性金属化合物を構成する元素として説明したものである。また、活性金属元素の形態（活性金属化合物の前駆体）としては、溶媒に溶解し、多孔質担体に活性金属化合物として担持されるものであれば特に制限されず、例えば、硝酸塩、酢酸塩、炭酸塩等の前記活性金属元素の塩、ジニトロジアンミン錯体等の前記活性金属元素の錯体、前記活性金属元素の水酸化物等を適宜使用することができる。 The active metal elements contained in the aqueous solution used in Method 1 and the water-soluble precursor solution used in Method 2 are described as elements constituting the active metal compound according to the present invention. The form of the active metal element (precursor of the active metal compound) is not particularly limited as long as it is dissolved in a solvent and supported on the porous carrier as the active metal compound. For example, nitrate, acetate, A salt of the active metal element such as a carbonate, a complex of the active metal element such as a dinitrodiammine complex, a hydroxide of the active metal element, or the like can be appropriately used.
前記方法１において、前記多孔質担体に前記水溶液を接触せしめる方法としては、特に制限されず、前記水溶液中に前記多孔質担体を浸漬して撹拌する方法、前記水溶液を前記多孔質担体に含浸担持させる等の公知の方法を適宜採用することができる。また、前記水溶液に用いられる溶媒としては特に制限されず、水、エタノール等を適宜利用することができ、廃液処理、調製コストの観点から、水が好ましい。 In the method 1, the method for bringing the aqueous solution into contact with the porous carrier is not particularly limited, and the porous carrier is immersed and stirred in the aqueous solution, and the porous carrier is impregnated and supported on the porous carrier. It is possible to employ a known method as appropriate. Moreover, it does not restrict | limit especially as a solvent used for the said aqueous solution, Water, ethanol, etc. can be utilized suitably, and water is preferable from a viewpoint of a waste liquid process and preparation cost.
前記水溶液や前記水溶性前駆体溶液中の活性金属元素の濃度としては、５ｇ／Ｌ以下が好ましく、１〜３ｇ／Ｌがより好ましい。活性金属元素の濃度が前記下限未満になると、所定量の活性金属化合物を多孔質担体に担持するためには多孔質担体との接触操作を複数回繰り返す必要があり、製造効率が低下する傾向にあるとともに、複数回の接触操作により活性金属元素の再溶出や析出が起こり、活性金属化合物を十分に均一に分散担持させることが困難となる傾向にある。他方、活性金属元素の濃度が前記上限を超えると、活性金属化合物を十分に均一に分散担持させることが困難となり、ＮＯ酸化性能及びＮＯｘ還元性能が低下する傾向にある。 The concentration of the active metal element in the aqueous solution or the water-soluble precursor solution is preferably 5 g / L or less, and more preferably 1 to 3 g / L. When the concentration of the active metal element is less than the lower limit, it is necessary to repeat the contact operation with the porous carrier a plurality of times in order to carry a predetermined amount of the active metal compound on the porous carrier, which tends to decrease the production efficiency. At the same time, re-elution and precipitation of the active metal element occurs by a plurality of contact operations, and it tends to be difficult to disperse and carry the active metal compound sufficiently uniformly. On the other hand, when the concentration of the active metal element exceeds the upper limit, it becomes difficult to disperse and carry the active metal compound sufficiently uniformly, and the NO oxidation performance and the NOx reduction performance tend to be lowered.
前記多孔質担体に、前記活性金属元素を含有する前記水溶液又は前記水溶性前駆体溶液を接触せしめた後の焼成時の温度条件としては、３００〜６００℃が好ましく、３００〜５５０℃がより好ましい。また、焼成時間としては、２〜１０時間が好ましく、３〜５時間がより好ましい。焼成温度又は焼成時間が前記下限未満になると、活性金属化合物の前駆体が十分に分解されず、ＮＯｘ吸蔵性能やＮＯｘ浄化性能が低下する傾向にあり、他方、前記上限を超えると、熱劣化が進行して粒成長が起こり、活性金属化合物を微細かつ十分に均一に分散担持させることが困難となる傾向にある。 As a temperature condition at the time of firing after bringing the aqueous solution or the water-soluble precursor solution containing the active metal element into contact with the porous carrier, 300 to 600 ° C is preferable, and 300 to 550 ° C is more preferable. . Moreover, as baking time, 2 to 10 hours are preferable and 3 to 5 hours are more preferable. When the firing temperature or firing time is less than the lower limit, the precursor of the active metal compound is not sufficiently decomposed, and the NOx occlusion performance and the NOx purification performance tend to be lowered. On the other hand, when the upper limit is exceeded, thermal degradation occurs. It progresses and grain growth occurs, and it tends to be difficult to disperse and carry the active metal compound finely and sufficiently uniformly.
以下、実施例及び比較例に基づいて本発明をより具体的に説明するが、本発明は以下の実施例に限定されるものではない。 EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.
（調製例１）
共沈法により調製したアルミナ−ジルコニア−チタニア複合酸化物粉末（アルミナ／ジルコニア／チタニア＝５０／３５／１５（質量比）、平均粒子径：５０μｍ、比表面積：１００ｍ２／ｇ）に、白金ジニトロジアンミン水溶液（０．２５ｍｏｌ／Ｌ）と硝酸パラジウム水溶液（０．４７ｍｏｌ／Ｌ）との混合水溶液を、前記複合酸化物粉末１００ｇに対してＰｔ及びＰｄの担持量がそれぞれ０．７４ｇ及び０．２８ｇとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＰｔ−Ｐｄ担持アルミナ−ジルコニア−チタニア複合酸化物粉末を得た。
(Preparation Example 1)
Alumina-zirconia-titania composite oxide powder (alumina / zirconia / titania = 50/35/15 (mass ratio), average particle size: 50 μm, specific surface area: 100 m 2 / g) prepared by coprecipitation method was added to platinum dinitro. A mixed aqueous solution of a diammine aqueous solution (0.25 mol / L) and a palladium nitrate aqueous solution (0.47 mol / L) has a supported amount of Pt and Pd of 0.74 g and 0.28 g with respect to 100 g of the composite oxide powder, respectively. Then, it was impregnated and supported, and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Pt—Pd-supported alumina-zirconia-titania composite oxide powder.
（調製例２）
前記アルミナ−ジルコニア−チタニア複合酸化物粉末に硝酸ロジウム水溶液（０．２７ｍｏｌ／Ｌ）を、前記複合酸化物粉末１００ｇに対してＲｈ担持量が１ｇとなるように含浸させて担持せしめた以外は調製例１と同様にして、Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物粉末を得た。
(Preparation Example 2)
Prepared except that the alumina-zirconia-titania composite oxide powder was impregnated with an aqueous rhodium nitrate solution (0.27 mol / L) so that the amount of Rh supported was 1 g with respect to 100 g of the composite oxide powder. In the same manner as in Example 1, an Rh-supported alumina-zirconia-titania composite oxide powder was obtained.
（調製例３）
六角セルコージェライトモノリス基材（直径：３０ｍｍ、長さ：５０ｍｍ、容積：３５ｍＬ、セル密度：４００ｃｅｌｌ／ｉｎｃｈ２）にアルミナ粉末（ローディア社製「ＭＩ３０７」、平均粒子径：１７μｍ、比表面積：１７０ｍ２／ｇ）を、前記モノリス基材１Ｌに対してアルミナ粉末のコート量が１５０ｇ／Ｌとなるようにウォッシュコート法を用いてコートし、多孔質アルミナ担体と前記モノリス基材とを備える触媒担体１を得た。
(Preparation Example 3)
Hexagonal cordierite monolith substrate (diameter: 30 mm, length: 50 mm, volume: 35 mL, cell density: 400 cell / inch 2 ) and alumina powder (“MI307” manufactured by Rhodia, average particle size: 17 μm, specific surface area: 170 m 2 / g) using a wash coating method so that the coating amount of alumina powder is 150 g / L on 1 L of the monolith substrate, and a catalyst carrier comprising a porous alumina carrier and the monolith substrate 1 was obtained.
（調製例４）
六角セルコージェライトモノリス基材（直径：３０ｍｍ、長さ：５０ｍｍ、容積：３５ｍＬ、セル密度：４００ｃｅｌｌ／ｉｎｃｈ２）に、調製例１で得たＰｔ−Ｐｄ担持アルミナ−ジルコニア−チタニア複合酸化物粉末（１８４ｇ／Ｌ）と調製例２で得たＲｈ担持アルミナ−ジルコニア−チタニア複合酸化物粉末（２７ｇ／Ｌ）とを含有するスラリーを、前記モノリス基材１Ｌに対して各複合酸化物粉末のコート量が２１１ｇ／Ｌとなるようにウォッシュコート法を用いてコートし、多孔質のＰｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物担体と前記モノリス基材とを備える触媒担体２を得た。
(Preparation Example 4)
Pt-Pd-supported alumina-zirconia-titania composite oxide powder obtained in Preparation Example 1 on a hexagonal cell cordierite monolith substrate (diameter: 30 mm, length: 50 mm, volume: 35 mL, cell density: 400 cell / inch 2 ) A slurry containing (184 g / L) and the Rh-supported alumina-zirconia-titania composite oxide powder (27 g / L) obtained in Preparation Example 2 was coated on each monolith substrate 1L with each composite oxide powder. Coating was performed using a wash coat method so that the amount was 211 g / L, and a catalyst carrier 2 including a porous Pt—Pd—Rh-supported alumina-zirconia-titania composite oxide carrier and the monolith substrate was obtained. .
（調製例５）
３．３ｍｏｌ／Ｌのクエン酸水溶液５０ｍｌに酢酸マンガン粉末１０．２ｇを添加し、室温で２０分間撹拌して酢酸マンガン粉末を溶解せしめ、次いで、この水溶液に２．１ｍｏｌ／Ｌの酢酸バリウム水溶液３９ｍｌを添加し、室温で１０分間撹拌してＢａ−Ｍｎ複合クエン酸水溶液を得た。
(Preparation Example 5)
Add 10.2 g of manganese acetate powder to 50 ml of 3.3 mol / L citric acid aqueous solution and stir at room temperature for 20 minutes to dissolve the manganese acetate powder, and then add 39 mol of 2.1 mol / L barium acetate aqueous solution to this aqueous solution. Was added and stirred at room temperature for 10 minutes to obtain an aqueous Ba-Mn complex citric acid solution.
（調製例６）
調製例５で得たＢａ−Ｍｎ複合クエン酸水溶液１４０ｍｌに酢酸ロジウム粉末を０．５７ｇ添加し、室温で１０分間撹拌して酢酸ロジウム粉末を溶解せしめてＢａ−Ｍｎ−Ｒｈ複合クエン酸水溶液を得た。
(Preparation Example 6)
Add 0.57 g of rhodium acetate powder to 140 ml of Ba-Mn composite citric acid aqueous solution obtained in Preparation Example 5, and stir at room temperature for 10 minutes to dissolve the rhodium acetate powder to obtain Ba-Mn-Rh composite citric acid aqueous solution. It was.
（実施例１）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に調製例５で得たＢａ−Ｍｎ複合クエン酸水溶液を、前記触媒担体１Ｌに対してＢａ及びＭｎの担持量がいずれも０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ−Ｍｎ担持アルミナ触媒を得た。
Example 1
The Ba-Mn composite citric acid aqueous solution obtained in Preparation Example 5 is applied to the catalyst support 1 provided with the porous alumina support obtained in Preparation Example 3, and the supported amounts of Ba and Mn are both 0.2 mol with respect to 1 L of the catalyst support. / L was impregnated and supported, and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Ba—Mn supported alumina catalyst.
（実施例２）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に白金ジニトロジアンミン水溶液（０．２５ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＰｔ担持量が２ｇ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＰｔ担持アルミナ触媒を得た。次に、このＰｔ担持アルミナ触媒に調製例５で得たＢａ−Ｍｎ複合クエン酸水溶液を、前記触媒担体１Ｌに対してＢａ及びＭｎの担持量がいずれも０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ−Ｍｎ／Ｐｔ担持アルミナ触媒を得た。
(Example 2)
The catalyst carrier 1 provided with the porous alumina carrier obtained in Preparation Example 3 was impregnated with an aqueous platinum dinitrodiammine solution (0.25 mol / L) so that the amount of Pt supported on the catalyst carrier 1L was 2 g / L. Then, it was supported and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Pt-supported alumina catalyst. Next, this Pt-supported alumina catalyst is impregnated with the Ba-Mn composite citric acid aqueous solution obtained in Preparation Example 5 so that the supported amounts of Ba and Mn are 0.2 mol / L with respect to 1 L of the catalyst support. Then, it was calcined at 550 ° C. for 5 hours in the air to obtain a Ba—Mn / Pt supported alumina catalyst.
（実施例３）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に調製例６で得たＢａ−Ｍｎ−Ｒｈ複合クエン酸水溶液を、前記触媒担体１Ｌに対してＢａ、Ｍｎ及びＲｈの担持量がそれぞれ０．２ｍｏｌ／Ｌ、０．２ｍｏｌ／Ｌ及び０．５ｇ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ−Ｍｎ−Ｒｈ担持アルミナ触媒を得た。
(Example 3)
The Ba—Mn—Rh composite citric acid aqueous solution obtained in Preparation Example 6 is applied to the catalyst support 1 including the porous alumina support obtained in Preparation Example 3, and the supported amounts of Ba, Mn, and Rh are each 1 L of the catalyst support. Impregnated and supported so as to be 0.2 mol / L, 0.2 mol / L and 0.5 g / L, and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Ba—Mn—Rh supported alumina catalyst. It was.
（実施例４）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に硝酸ロジウム水溶液（０．２７ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＲｈ担持量が０．５ｇ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＲｈ担持アルミナ触媒を得た。次に、このＲｈ担持アルミナ触媒に調製例５で得たＢａ−Ｍｎ複合クエン酸水溶液を、前記触媒担体１Ｌに対してＢａ及びＭｎの担持量がいずれも０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ−Ｍｎ／Ｒｈ担持アルミナ触媒を得た。
Example 4
The catalyst carrier 1 having the porous alumina carrier obtained in Preparation Example 3 is impregnated with an aqueous rhodium nitrate solution (0.27 mol / L) so that the amount of Rh supported on the catalyst carrier 1L is 0.5 g / L. And then calcined in the atmosphere at 550 ° C. for 5 hours to obtain an Rh-supported alumina catalyst. Next, the Ba-Mn composite citric acid aqueous solution obtained in Preparation Example 5 was impregnated with this Rh-supported alumina catalyst so that the supported amounts of Ba and Mn were both 0.2 mol / L with respect to 1 L of the catalyst support. Then, it was calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Ba—Mn / Rh supported alumina catalyst.
（実施例５）
調製例４で得た多孔質のＰｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物担体を備える触媒担体２に調製例５で得たＢａ−Ｍｎ複合クエン酸水溶液を、前記触媒担体１Ｌに対してＢａ及びＭｎの担持量がいずれも０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ−Ｍｎ／Ｐｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物触媒を得た。この複合酸化物触媒に、酢酸カリウム水溶液（２．１６ｍｏｌ／Ｌ）と酢酸リチウム水溶液（１．４４ｍｏｌ／Ｌ）との混合水溶液を、前記触媒担体１Ｌに対してＫ及びＬｉの担持量がそれぞれ０．１５ｍｏｌ／Ｌ及び０．１０ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＫ−Ｌｉ／Ｂａ−Ｍｎ／Ｐｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物触媒を得た。
(Example 5)
The Ba—Mn composite citric acid aqueous solution obtained in Preparation Example 5 was added to the catalyst support 1L in the catalyst support 2 provided with the porous Pt—Pd—Rh-supported alumina-zirconia-titania composite oxide support obtained in Preparation Example 4. Ba-Mn / Pt-Pd-Rh-supported alumina was impregnated and supported so that the supported amounts of Ba and Mn were both 0.2 mol / L, and then fired in the atmosphere at 550 ° C. for 5 hours. -A zirconia-titania composite oxide catalyst was obtained. A mixed aqueous solution of an aqueous potassium acetate solution (2.16 mol / L) and an aqueous lithium acetate solution (1.44 mol / L) is added to the composite oxide catalyst, and the supported amounts of K and Li are 0 with respect to 1 L of the catalyst carrier. .. impregnated and supported so as to be 15 mol / L and 0.10 mol / L, and then calcined in the atmosphere at 550 ° C. for 5 hours to carry K-Li / Ba-Mn / Pt-Pd-Rh-supported alumina-zirconia -A titania composite oxide catalyst was obtained.
（比較例１）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に酢酸バリウム水溶液（２．１４ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＢａ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ担持アルミナ触媒を得た。
(Comparative Example 1)
The catalyst carrier 1 having the porous alumina carrier obtained in Preparation Example 3 was impregnated with an aqueous barium acetate solution (2.14 mol / L) so that the amount of Ba supported was 0.2 mol / L with respect to 1 L of the catalyst carrier. And then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Ba-supported alumina catalyst.
（比較例２）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に白金ジニトロジアンミン水溶液（０．２５ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＰｔ担持量が２ｇ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＰｔ担持アルミナ触媒を得た。
(Comparative Example 2)
The catalyst carrier 1 provided with the porous alumina carrier obtained in Preparation Example 3 was impregnated with an aqueous platinum dinitrodiammine solution (0.25 mol / L) so that the amount of Pt supported on the catalyst carrier 1L was 2 g / L. Then, it was supported and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Pt-supported alumina catalyst.
（比較例３）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に白金ジニトロジアンミン水溶液（０．２５ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＰｔ担持量が２ｇ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＰｔ担持アルミナ触媒を得た。次に、このＰｔ担持アルミナ触媒に酢酸バリウム水溶液（２．１４ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＢａ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ／Ｐｔ担持アルミナ触媒を得た。
(Comparative Example 3)
The catalyst carrier 1 provided with the porous alumina carrier obtained in Preparation Example 3 was impregnated with an aqueous platinum dinitrodiammine solution (0.25 mol / L) so that the amount of Pt supported on the catalyst carrier 1L was 2 g / L. Then, it was supported and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Pt-supported alumina catalyst. Next, an aqueous barium acetate solution (2.14 mol / L) is impregnated on the Pt-supported alumina catalyst so that the amount of Ba supported is 0.2 mol / L on the catalyst support 1L, and then supported on the atmosphere. Medium and calcined at 550 ° C. for 5 hours to obtain a Ba / Pt supported alumina catalyst.
（比較例４）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に酢酸マンガン水溶液（０．５８ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＭｎ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＭｎ担持アルミナ触媒を得た。
(Comparative Example 4)
An aqueous manganese acetate solution (0.58 mol / L) is impregnated on the catalyst carrier 1 including the porous alumina carrier obtained in Preparation Example 3 so that the amount of Mn supported is 0.2 mol / L with respect to 1 L of the catalyst carrier. And then calcined in the atmosphere at 550 ° C. for 5 hours to obtain an Mn-supported alumina catalyst.
（比較例５）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に白金ジニトロジアンミン水溶液（０．２５ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＰｔ担持量が２ｇ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＰｔ担持アルミナ触媒を得た。次に、このＰｔ担持アルミナ触媒に酢酸マンガン水溶液（０．５８ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＭｎ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＭｎ／Ｐｔ担持アルミナ触媒を得た。
(Comparative Example 5)
The catalyst carrier 1 provided with the porous alumina carrier obtained in Preparation Example 3 was impregnated with an aqueous platinum dinitrodiammine solution (0.25 mol / L) so that the amount of Pt supported on the catalyst carrier 1L was 2 g / L. Then, it was supported and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Pt-supported alumina catalyst. Next, an aqueous manganese acetate solution (0.58 mol / L) is impregnated on the Pt-supported alumina catalyst so that the amount of Mn supported is 0.2 mol / L with respect to 1 L of the catalyst support, Medium and calcined at 550 ° C. for 5 hours to obtain a Mn / Pt supported alumina catalyst.
（比較例６）
比較例４で得たＭｎ担持アルミナ触媒に酢酸バリウム水溶液（２．１４ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＢａ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ／Ｍｎ担持アルミナ触媒を得た。
(Comparative Example 6)
The Mn-supported alumina catalyst obtained in Comparative Example 4 was impregnated with an aqueous barium acetate solution (2.14 mol / L) so that the Ba support amount was 0.2 mol / L on the catalyst support 1L, and then supported. The Ba / Mn supported alumina catalyst was obtained by calcination in the atmosphere at 550 ° C. for 5 hours.
（比較例７）
調製例３で得た多孔質アルミナ担体を備える触媒担体１に硝酸マンガン水溶液（０．５８ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＭｎ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＭｎ担持アルミナ触媒を得た。次に、このＭｎ担持アルミナ触媒に硝酸バリウム水溶液（２．１４ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＢａ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ／Ｍｎ担持アルミナ触媒を得た。
(Comparative Example 7)
An aqueous manganese nitrate solution (0.58 mol / L) is impregnated on the catalyst carrier 1 including the porous alumina carrier obtained in Preparation Example 3 so that the amount of Mn supported is 0.2 mol / L with respect to 1 L of the catalyst carrier. And then calcined in the atmosphere at 550 ° C. for 5 hours to obtain an Mn-supported alumina catalyst. Next, the Mn-supported alumina catalyst is impregnated with an aqueous barium nitrate solution (2.14 mol / L) so that the catalyst support 1L is impregnated with a Ba support amount of 0.2 mol / L. Medium and calcined at 550 ° C. for 5 hours to obtain a Ba / Mn supported alumina catalyst.
（比較例８）
調製例４で得た多孔質のＰｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物担体を備える触媒担体２に酢酸バリウム水溶液（２．１４ｍｏｌ／Ｌ）を、前記触媒担体１Ｌに対してＢａ担持量が０．２ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＢａ／Ｐｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物触媒を得た。この複合酸化物触媒に、酢酸カリウム水溶液（２．１６ｍｏｌ／Ｌ）と酢酸リチウム水溶液（１．４４ｍｏｌ／Ｌ）との混合水溶液を、前記触媒担体１Ｌに対してＫ及びＬｉの担持量がそれぞれ０．１５ｍｏｌ／Ｌ及び０．１０ｍｏｌ／Ｌとなるように含浸させて担持せしめ、次いで、大気中、５５０℃で５時間焼成してＫ−Ｌｉ／Ｂａ／Ｐｔ−Ｐｄ−Ｒｈ担持アルミナ−ジルコニア−チタニア複合酸化物触媒を得た。
(Comparative Example 8)
An aqueous barium acetate solution (2.14 mol / L) was added to the catalyst support 2 provided with the porous Pt—Pd—Rh-supported alumina-zirconia-titania composite oxide support obtained in Preparation Example 4, and Ba to the catalyst support 1L. It was impregnated so as to have a supported amount of 0.2 mol / L and supported, and then calcined in the atmosphere at 550 ° C. for 5 hours to obtain a Ba / Pt—Pd—Rh supported alumina-zirconia-titania composite oxide catalyst. It was. A mixed aqueous solution of an aqueous potassium acetate solution (2.16 mol / L) and an aqueous lithium acetate solution (1.44 mol / L) is added to the composite oxide catalyst, and the supported amounts of K and Li are 0 with respect to 1 L of the catalyst carrier. .. impregnated and supported so as to be 15 mol / L and 0.10 mol / L, and then calcined in the atmosphere at 550 ° C. for 5 hours to carry K-Li / Ba / Pt-Pd-Rh supported alumina-zirconia-titania A composite oxide catalyst was obtained.
表１には、実施例及び比較例で得られた触媒の組成を示す。 Table 1 shows the compositions of the catalysts obtained in the examples and comparative examples.
＜耐久試験＞
実施例及び比較例で得られた触媒に対して、入りガス温度７５０℃、流量１１Ｌ／分の条件において表２に示すリーンガスとリッチガスとを１１０秒／１０秒の条件で切換えながら５時間供給する耐久試験を行なった。
<Durability test>
The catalyst obtained in the example and the comparative example is supplied for 5 hours while switching the lean gas and the rich gas shown in Table 2 under the conditions of 110 seconds / 10 seconds at the inlet gas temperature of 750 ° C. and the flow rate of 11 L / min. A durability test was conducted.
＜ＳＴＥＭ観察及びＥＤＸ分析＞
前記耐久試験後、前記モノリス基材上の触媒コート層を引っ掻いて捕集し、得られた触媒粉末を、球面収差補正機能付走査透過電子顕微鏡（ＳＴＥＭ、（株）日立製作所製「ＨＤ−２７００」）を用い、加速電圧２００ｋＶの条件で観察した。図２〜５には、実施例１、３及び比較例３、６で得られた触媒のＳＴＥＭ写真を示す。
<STEM observation and EDX analysis>
After the endurance test, the catalyst coating layer on the monolith substrate was scratched and collected, and the obtained catalyst powder was subjected to a scanning transmission electron microscope with a spherical aberration correction function (STEM, “HD-2700, manufactured by Hitachi, Ltd.). )), And observed under the condition of an acceleration voltage of 200 kV. 2 to 5 show STEM photographs of the catalysts obtained in Examples 1 and 3 and Comparative Examples 3 and 6, respectively.
また、前記走査透過電子顕微鏡に付属するＥＤＸ検出器を用い、触媒表面上の無作為に抽出した２０点以上の測定点（１０ｎｍ×１０ｎｍの領域を１つの測定点とした。）において蛍光Ｘ線スペクトルを測定し、得られたエネルギー分散型の蛍光Ｘ線スペクトルに基づいて元素分析（ＴＥＭ−ＥＤＸ分析）を行なった。なお、図２〜５には、ＴＥＭ−ＥＤＸ分析の際に利用した測定点（長方形で囲まれた領域）を明示した。得られたスペクトルのピーク面積から各測定点における各元素の含有割合を算出した。すべての測定点の元素の含有割合から、各元素について、触媒中の元素の含有割合の標準偏差と平均値（平均濃度）を求め、各元素の変動係数（含有割合の標準偏差／含有割合の平均値）を算出した。表３には、実施例１、３及び比較例３、６で得られた触媒における、Ｂａ及びＭｎの含有割合の標準偏差、平均値及び変動係数を示す。 Further, using an EDX detector attached to the scanning transmission electron microscope, fluorescent X-rays were measured at 20 or more randomly selected measurement points on the catalyst surface (a region of 10 nm × 10 nm was defined as one measurement point). The spectrum was measured, and elemental analysis (TEM-EDX analysis) was performed based on the obtained energy dispersive X-ray fluorescence spectrum. In addition, in FIGS. 2-5, the measurement point (area | region enclosed with the rectangle) utilized in the case of TEM-EDX analysis was clarified. The content ratio of each element at each measurement point was calculated from the peak area of the obtained spectrum. For each element, the standard deviation and average value (average concentration) of the element content in the catalyst are determined from the element content at all measurement points, and the variation coefficient of each element (standard deviation of content ratio / content ratio) (Average value) was calculated. Table 3 shows the standard deviation, average value, and coefficient of variation of the content ratios of Ba and Mn in the catalysts obtained in Examples 1 and 3 and Comparative Examples 3 and 6.
表３に示した結果から明らかなように、ＢａとＭｎと多座配位子とを含有する水溶性前駆体溶液を用いて調製した本発明のＮＯｘ吸蔵還元型触媒（実施例１、３）においては、Ｂａ元素及びＭｎ元素の含有割合の変動係数がともに０．９以下であり、Ｂａ及びＭｎが微細かつ均一に分散担持されていることが確認された。一方、Ｍｎ化合物を担持しなかった触媒（比較例３）、並びにＢａ化合物を担持せしめた後、Ｍｎ化合物を担持せしめた触媒（比較例６）においては、Ｂａ元素の含有割合の変動係数が１．０以上となり、Ｂａの均一分散性に劣っていることがわかった。 As is clear from the results shown in Table 3, the NOx occlusion reduction catalyst of the present invention prepared using a water-soluble precursor solution containing Ba, Mn and a polydentate ligand (Examples 1 and 3) , The coefficient of variation of the content ratios of Ba element and Mn element were both 0.9 or less, and it was confirmed that Ba and Mn were finely and uniformly dispersed and supported. On the other hand, in the catalyst not supporting the Mn compound (Comparative Example 3) and the catalyst supporting the Ba compound and then supporting the Mn compound (Comparative Example 6), the variation coefficient of the content ratio of the Ba element is 1. It was found to be inferior in uniform dispersibility of Ba.
＜ＸＲＤ測定＞
前記耐久試験後、前記モノリス基材上の触媒コート層を引っ掻いて捕集し、得られた触媒粉末を、Ｘ線回折装置（（株）リガク製「ＲＩＮＴ−ＴＴＲ ＩＩ」）を用い、触媒を構成する化合物の結晶構造を分析した。図６には、実施例１、３及び比較例３、６で得られた触媒のＸ線回折パターンを示す。
<XRD measurement>
After the endurance test, the catalyst coating layer on the monolith substrate was scratched and collected, and the resulting catalyst powder was collected using an X-ray diffractometer (“RINT-TTR II” manufactured by Rigaku Corporation). The crystal structure of the constituent compounds was analyzed. FIG. 6 shows X-ray diffraction patterns of the catalysts obtained in Examples 1 and 3 and Comparative Examples 3 and 6.
図６に示した結果から明らかなように、ＢａとＭｎと多座配位子とを含有する水溶性前駆体溶液を用いて調製した本発明のＮＯｘ吸蔵還元型触媒（実施例１、３）においては、ＢａＣＯ３結晶に由来する回折ピークの幅が狭く、粗大化したＢａＣＯ３粒子が少ないことが確認された。また、Ｍｎ由来の回折ピークは観察されず、Ｍｎ化合物は非晶質形態で触媒表面に存在していることがわかった。 As is clear from the results shown in FIG. 6, the NOx occlusion reduction catalyst of the present invention prepared using a water-soluble precursor solution containing Ba, Mn and a polydentate ligand (Examples 1 and 3). , It was confirmed that the width of the diffraction peak derived from the BaCO 3 crystal was narrow and the number of coarsened BaCO 3 particles was small. Further, no diffraction peak derived from Mn was observed, and it was found that the Mn compound was present on the catalyst surface in an amorphous form.
＜触媒活性評価試験＞
全自動流通式触媒評価装置（（株）ベスト測器「ＣＡＴＡ−５０００−８」）を用いて、以下のようにして触媒活性評価試験を行なった。すなわち、先ず、前記耐久試験後の触媒に対して、表４に示す前処理ガスを５００℃で４分間流通させ、その後、表４に示すリーンガスを４００℃で１０分間流通させ（空間時間：２５０００ｈ−１）、入りガス中と出ガス中のＮＯｘ濃度の差分から飽和ＮＯｘ吸蔵量を算出した。その結果を表５に示す。
<Catalyst activity evaluation test>
A catalyst activity evaluation test was performed as follows using a fully automatic flow-type catalyst evaluation apparatus (Best Instrument “CATA-5000-8”). That is, first, with respect to the catalyst after the durability test, the pretreatment gas shown in Table 4 was circulated at 500 ° C. for 4 minutes, and then the lean gas shown in Table 4 was circulated at 400 ° C. for 10 minutes (space time: 25000 h). -1 ), the saturated NOx occlusion amount was calculated from the difference between the NOx concentrations in the incoming gas and the outgoing gas. The results are shown in Table 5.
次に、十分なＮＯｘ吸蔵量を示した触媒（実施例１〜５及び比較例３、６〜８）に対して、表４に示すリーンガス及びリッチガスを６０秒／３秒で切換えながら４００℃で１０．５分間流通させ（空間時間：２５０００ｈ−１）、入りガス中と出ガス中のＮＯｘ濃度の差分からリッチスパイクＮＯｘ浄化率を算出した。その結果を表５に示す。 Next, with respect to the catalysts (Examples 1 to 5 and Comparative Examples 3 and 6 to 8) that showed a sufficient NOx occlusion amount, the lean gas and the rich gas shown in Table 4 were switched at 60 ° C / 3 seconds at 400 ° C. The rich spike NOx purification rate was calculated from the difference between the NOx concentration in the incoming gas and the outgoing gas after flowing for 10.5 minutes (space time: 25000 h −1 ). The results are shown in Table 5.
表５に示した結果から明らかなように、ＢａとＭｎと多座配位子とを含有する水溶性前駆体溶液を用いて調製した本発明のＮＯｘ吸蔵還元型触媒（実施例１〜５）は、Ｂａ化合物及びＭｎ化合物の両者を含有していない触媒（比較例２）、Ｂａ化合物及びＭｎ化合物のいずれか一方を含有する触媒（比較例１、３〜５、８）並びにＭｎ化合物を担持せしめた後、Ｂａ化合物を担持せしめた触媒（比較例６〜７）に比べて、飽和ＮＯｘ吸蔵量が多く、リッチスパイクＮＯｘ浄化活性に優れたものであることが確認された。 As is apparent from the results shown in Table 5, the NOx occlusion reduction type catalyst of the present invention prepared using a water-soluble precursor solution containing Ba, Mn and a polydentate ligand (Examples 1 to 5) Supports a catalyst that does not contain both a Ba compound and a Mn compound (Comparative Example 2), a catalyst that contains either a Ba compound or a Mn compound (Comparative Examples 1, 3 to 5, 8), and a Mn compound After the caking, it was confirmed that the saturated NOx occlusion amount was large and the rich spike NOx purifying activity was excellent as compared with the catalysts (Comparative Examples 6 to 7) on which the Ba compound was supported.
以上説明したように、本発明によれば、アルカリ金属元素及びアルカリ土類金属元素からなる群から選択される少なくとも１種の元素を含むアルカリ化合物及びＭｎ化合物が、多孔質担体上に微細かつ十分に均一に分散した状態で担持されたＮＯｘ吸蔵還元型触媒を得ることが可能となる。 As described above, according to the present invention, an alkali compound and an Mn compound containing at least one element selected from the group consisting of an alkali metal element and an alkaline earth metal element are fine and sufficient on the porous carrier. It is possible to obtain a NOx occlusion reduction type catalyst that is supported in a uniformly dispersed state.
したがって、本発明のＮＯｘ吸蔵還元型触媒は、高いＮＯｘ吸蔵性性能を有し、ＮＯｘ浄化性能に優れているため、自動車等の内燃機関から排出されるガスに含まれるＮＯｘを浄化するための触媒等として有用である。 Therefore, since the NOx occlusion reduction type catalyst of the present invention has high NOx occlusion performance and excellent NOx purification performance, it is a catalyst for purifying NOx contained in gas discharged from an internal combustion engine such as an automobile. Useful as such.
１：Ｍｎ化合物
２：アルカリ化合物
３：活性金属化合物
４：多孔質担体
1: Mn compound 2: Alkaline compound 3: Active metal compound 4: Porous support
Claims (5)
前記触媒表面上の無作為に抽出した２０点以上の測定点において、ＴＥＭ−ＥＤＸ分析により求められる、全無機金属元素に対するアルカリ金属元素及びアルカリ土類金属元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下であり、かつ、全無機金属元素に対するＭｎ元素の含有割合の変動係数（含有割合の標準偏差／含有割合の平均値）が０．９以下であることを特徴とするＮＯｘ吸蔵還元型触媒。 A porous carrier comprising an oxide containing at least one element selected from the group consisting of Al, Zr, Ti, Ce, Mg and Si; and an alkali metal element and an alkaline earth supported on the porous carrier. A NOx occlusion reduction catalyst comprising an alkali compound containing at least one element selected from the group consisting of metalloid elements and a Mn compound supported on the porous carrier;
The coefficient of variation of the content ratio of the alkali metal element and the alkaline earth metal element to the total inorganic metal elements obtained by TEM-EDX analysis at 20 or more randomly extracted measurement points on the catalyst surface (content ratio The standard deviation / average content ratio) is 0.9 or less, and the variation coefficient of the Mn element content ratio relative to all inorganic metal elements (standard deviation of content ratio / average content ratio) is 0.9 or less. NOx occlusion reduction type catalyst characterized by being.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014110198A JP6315192B2 (en) | 2014-05-28 | 2014-05-28 | NOx storage reduction catalyst and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014110198A JP6315192B2 (en) | 2014-05-28 | 2014-05-28 | NOx storage reduction catalyst and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2015223560A true JP2015223560A (en) | 2015-12-14 |
| JP6315192B2 JP6315192B2 (en) | 2018-04-25 |
Family
ID=54840754
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2014110198A Active JP6315192B2 (en) | 2014-05-28 | 2014-05-28 | NOx storage reduction catalyst and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6315192B2 (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1043591A (en) * | 1996-07-31 | 1998-02-17 | Osaka Gas Co Ltd | Denitration catalyst |
| JPH11276896A (en) * | 1998-01-30 | 1999-10-12 | Mazda Motor Corp | Catalyst for cleaning exhaust gas |
| JP2000279824A (en) * | 1999-03-29 | 2000-10-10 | Tanaka Kikinzoku Kogyo Kk | Production of exhaust gas cleaning catalyst and obtained catalyst |
| US6221804B1 (en) * | 1998-01-27 | 2001-04-24 | Mazda Motor Corporation | Catalyst for purifying exhaust gas and manufacturing method thereof |
| JP2002224568A (en) * | 2001-01-31 | 2002-08-13 | Hitachi Ltd | Exhaust emission control catalyst for internal combustion engine, internal combustion engine utilizing the same, and method for controlling exhaust emission |
| JP2004267961A (en) * | 2003-03-11 | 2004-09-30 | Tanaka Kikinzoku Kogyo Kk | Catalyst manufactured by utilizing polyphyletic metal colloid |
| JP2008012501A (en) * | 2006-07-10 | 2008-01-24 | Toyota Motor Corp | METHOD FOR CARRYING NOx OCCLUSION MATERIAL |
| JP2013248570A (en) * | 2012-05-31 | 2013-12-12 | Toyota Central R&D Labs Inc | Exhaust gas purifying catalyst, method of manufacturing the same, and method of purifying exhaust gas using the same |
-
2014
- 2014-05-28 JP JP2014110198A patent/JP6315192B2/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1043591A (en) * | 1996-07-31 | 1998-02-17 | Osaka Gas Co Ltd | Denitration catalyst |
| US6221804B1 (en) * | 1998-01-27 | 2001-04-24 | Mazda Motor Corporation | Catalyst for purifying exhaust gas and manufacturing method thereof |
| JPH11276896A (en) * | 1998-01-30 | 1999-10-12 | Mazda Motor Corp | Catalyst for cleaning exhaust gas |
| JP2000279824A (en) * | 1999-03-29 | 2000-10-10 | Tanaka Kikinzoku Kogyo Kk | Production of exhaust gas cleaning catalyst and obtained catalyst |
| JP2002224568A (en) * | 2001-01-31 | 2002-08-13 | Hitachi Ltd | Exhaust emission control catalyst for internal combustion engine, internal combustion engine utilizing the same, and method for controlling exhaust emission |
| JP2004267961A (en) * | 2003-03-11 | 2004-09-30 | Tanaka Kikinzoku Kogyo Kk | Catalyst manufactured by utilizing polyphyletic metal colloid |
| US20070060473A1 (en) * | 2003-03-11 | 2007-03-15 | Masayuki Saito | Catalyst produced by using multi-element metal colloid |
| JP2008012501A (en) * | 2006-07-10 | 2008-01-24 | Toyota Motor Corp | METHOD FOR CARRYING NOx OCCLUSION MATERIAL |
| JP2013248570A (en) * | 2012-05-31 | 2013-12-12 | Toyota Central R&D Labs Inc | Exhaust gas purifying catalyst, method of manufacturing the same, and method of purifying exhaust gas using the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6315192B2 (en) | 2018-04-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5350614B2 (en) | Exhaust gas purification catalyst and exhaust gas purification apparatus using the same | |
| JP5286526B2 (en) | Exhaust gas purification catalyst and method for producing the same | |
| JP2005262201A (en) | Exhaust gas-cleaning catalyst and method for manufacturing the same | |
| JP4831753B2 (en) | Exhaust gas purification catalyst | |
| JP5788298B2 (en) | Exhaust gas purification catalyst carrier, exhaust gas purification catalyst using the same, and production method thereof | |
| JP5290062B2 (en) | Exhaust gas purification catalyst | |
| WO2022249847A1 (en) | Exhaust gas purification catalyst | |
| JP6050703B2 (en) | Exhaust gas purification catalyst | |
| JP6315192B2 (en) | NOx storage reduction catalyst and method for producing the same | |
| JP6011779B2 (en) | Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification method using the same | |
| JP2007301471A (en) | Catalyst for cleaning exhaust gas | |
| JP5973914B2 (en) | Method for producing catalyst composition for exhaust gas treatment | |
| JP5488402B2 (en) | Exhaust gas purification catalyst | |
| JP5288261B2 (en) | Exhaust gas purification catalyst and method for producing the same | |
| JP2007203160A (en) | Catalyst support for purification of exhaust gas, catalyst for purification of exhaust gas using it and method of purifying exhaust gas | |
| JP2009285620A (en) | Exhaust gas purification catalyst | |
| JP6096818B2 (en) | Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification method using the same | |
| JP7238211B2 (en) | Particles for exhaust gas purification catalyst | |
| JP2011092852A (en) | Composite monolithic catalyst for cleaning exhaust gas | |
| JP5104352B2 (en) | Exhaust gas purification catalyst | |
| JP2017180453A (en) | Exhaust emission control device and its process of manufacture | |
| JP2008006337A (en) | Catalyst for cleaning exhaust gas | |
| JP2015231598A (en) | Exhaust gas purification catalyst | |
| CN117098602A (en) | Catalyst composition for exhaust gas purification and catalyst for exhaust gas purification | |
| JP5769666B2 (en) | Exhaust gas purification catalyst |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20170112 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20170725 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20170807 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20171005 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20180228 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20180313 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6315192 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |