JPH08141371A - Exhaust gas purification material and purifying method for exhaust gas - Google Patents

Exhaust gas purification material and purifying method for exhaust gas

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Publication number
JPH08141371A
JPH08141371A JP6317582A JP31758294A JPH08141371A JP H08141371 A JPH08141371 A JP H08141371A JP 6317582 A JP6317582 A JP 6317582A JP 31758294 A JP31758294 A JP 31758294A JP H08141371 A JPH08141371 A JP H08141371A
Authority
JP
Japan
Prior art keywords
exhaust gas
catalyst
silver
purifying material
gas purifying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP6317582A
Other languages
Japanese (ja)
Inventor
Mika Saitou
美香 斎藤
Akira Abe
晃 阿部
Kiyohide Yoshida
清英 吉田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Riken Corp
Original Assignee
Riken Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Riken Corp filed Critical Riken Corp
Priority to JP6317582A priority Critical patent/JPH08141371A/en
Priority to US08/466,988 priority patent/US5714130A/en
Priority to EP95308495A priority patent/EP0714693A1/en
Publication of JPH08141371A publication Critical patent/JPH08141371A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE: To efficiently reduce and remove nitrogen oxide from exhaust combustion gas by constitution exhaust gas purification material of a first and second catalysts in which silver or the like of a specified carrying-rate is carried respectively as an active species on porous inorganic oxide and arranging the first and second catalysts in order from the exhaust gas inflow side of the purification material to the outflow side. CONSTITUTION: Exhaust gas purification material is constituted of a first catalyst in which silver and/or a silver compound or the mixture thereof is carried at 0.2-12wt.% as an active species on porous inorganic oxide and of a second catalyst in which the same is carried at 0.5-15wt.% in the quantity more than the carrying rate of the active species of the first catalyst on the porous inorganic oxide. The exhaust gas purification material having the first catalyst and the second catalyst is provided in order from the exhaust gas inflow side of the purification material to the outflow side in the conduit of exhaust gas. Nitrogen oxide contained in exhaust gas is reduced and removed by bringing exhaust gas into contact with the purification material. In the exhaust gas, there is added either of hydrocarbon and oxygen-containing organic compound of >=2C, or fuel containing such a compound on the upstream side from the position for installing the purification material.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は窒素酸化物と過剰の酸素
を含む燃焼排ガスから、窒素酸化物を効果的に還元除去
することのできる排ガス浄化材及びそれを用いた浄化方
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying material capable of effectively reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and excess oxygen, and a purification method using the same.

【０００２】[0002]

【従来の技術及び発明が解決しようとする課題】自動車
用エンジン等の内燃機関や、工場等に設置された燃焼機
器、家庭用ファンヒーターなどから排出される各種の燃
焼排ガス中には、過剰の酸素とともに一酸化窒素、二酸
化窒素等の窒素酸化物が含まれている。ここで、「過剰
の酸素を含む」とは、その排ガス中に含まれる一酸化炭
素、水素、炭化水素等の未燃焼成分を燃焼するのに必要
な理論酸素量より多い酸素を含むことを意味する。ま
た、以下における窒素酸化物とは一酸化窒素及び／又は
二酸化窒素を指す。2. Description of the Related Art Excessive combustion exhaust gas discharged from internal combustion engines such as automobile engines, combustion equipment installed in factories, household fan heaters, and the like is excessive. It contains nitrogen oxides such as nitric oxide and nitrogen dioxide together with oxygen. Here, "containing excess oxygen" means that the exhaust gas contains more oxygen than the theoretical amount of oxygen necessary to burn unburned components such as carbon monoxide, hydrogen, and hydrocarbons. I do. In the following, nitrogen oxide refers to nitric oxide and / or nitrogen dioxide.

【０００３】この窒素酸化物は酸性雨の原因の一つとさ
れ、環境上の大きな問題となっている。そのため、各種
燃焼機器が排出する排ガス中の窒素酸化物を除去するさ
まざまな方法が検討されている。[0003] This nitrogen oxide is one of the causes of acid rain and is a major environmental problem. Therefore, various methods for removing nitrogen oxides in exhaust gas discharged from various combustion equipments are being studied.

【０００４】過剰の酸素を含む燃焼排ガスから窒素酸化
物を除去する方法として、特に大規模な固定燃焼装置
（工場等の大型燃焼機等）に対しては、アンモニアを用
いる選択的接触還元法が実用化されている。[0004] As a method for removing nitrogen oxides from a combustion exhaust gas containing excess oxygen, a selective catalytic reduction method using ammonia is used particularly for a large-scale fixed combustion device (a large-scale combustor in a factory or the like). Has been put to practical use.

【０００５】しかしながら、この方法においては、窒素
酸化物の還元剤として用いるアンモニアが高価であるこ
と、またアンモニアは毒性を有すること、そのために未
反応のアンモニアが排出しないように排ガス中の窒素酸
化物濃度を計測しながらアンモニア注入量を制御しなけ
ればならないこと、一般に装置が大型となること等の問
題点がある。However, in this method, ammonia used as a reducing agent for nitrogen oxides is expensive, and ammonia is toxic. Therefore, the nitrogen oxides in the exhaust gas must be removed so that unreacted ammonia is not discharged. There are problems that the amount of injected ammonia must be controlled while measuring the concentration, and that the apparatus generally becomes large.

【０００６】また、別な方法として、水素、一酸化炭
素、炭化水素等のガスを還元剤として用い、窒素酸化物
を還元する非選択的接触還元法があるが、この方法で
は、効果的な窒素酸化物の低減除去を実行するためには
排ガス中の酸素との理論反応量以上の還元剤を添加しな
ければならず、還元剤を多量に消費する欠点がある。こ
のため非選択的接触還元法は、実際上は、理論空燃比付
近で燃焼した残存酸素濃度の低い排ガスに対してのみ有
効となり、汎用性に乏しく実際的でない。As another method, there is a non-selective catalytic reduction method in which a nitrogen oxide is reduced by using a gas such as hydrogen, carbon monoxide, or a hydrocarbon as a reducing agent. In order to reduce and remove nitrogen oxides, it is necessary to add a reducing agent in an amount equal to or more than a theoretical reaction amount with oxygen in exhaust gas, and there is a disadvantage that a large amount of the reducing agent is consumed. For this reason, the non-selective catalytic reduction method is practically effective only for exhaust gas having a low residual oxygen concentration burned near the stoichiometric air-fuel ratio, and is not practical because of poor versatility.

【０００７】そこで、ゼオライト又はそれに遷移金属を
担持した触媒を用いて、排ガス中の酸素との理論反応量
以下の還元剤を添加して窒素酸化物を除去する方法が提
案された（たとえば、特開昭63-100919 号、同63-28372
7 号、特開平1-130735号等)。In view of the above, a method has been proposed for removing nitrogen oxides by using a zeolite or a catalyst supporting a transition metal on the zeolite and adding a reducing agent having a theoretical reaction amount or less with oxygen in the exhaust gas (for example, Japanese Patent Application Laid-Open Publication No. H11-163873). No.63-100919, 63-28372
No. 7, JP-A No. 1-130735).

【０００８】しかしながら、これらの方法では、効果的
な窒素酸化物の除去が狭い温度領域でしか得られず、ま
た、水分を含むような排ガスでは、窒素酸化物の除去率
が著しく低下する。つまり、１０％程度の水分を含み、
運転条件によって温度変化の大きい車等からの排ガスに
対して、窒素酸化物の効果的除去は困難である。However, in these methods, effective removal of nitrogen oxides can be obtained only in a narrow temperature range, and in an exhaust gas containing water, the removal rate of nitrogen oxides is significantly reduced. In other words, it contains about 10% water,
It is difficult to effectively remove nitrogen oxides from exhaust gas from a vehicle or the like whose temperature changes greatly depending on operating conditions.

【０００９】したがって、本発明の目的は、固定燃焼装
置および酸素過剰条件で燃焼するガソリンエンジン、デ
ィーゼルエンジン等からの燃焼排ガスのように、窒素酸
化物や、一酸化炭素、水素、炭化水素等の未燃焼分に対
する理論反応量以上の酸素を含有する燃焼排ガスから、
効率良く窒素酸化物を還元除去することができる排ガス
浄化材及び排ガス浄化方法を提供することである。Accordingly, it is an object of the present invention to provide a method for producing nitrogen oxides, carbon monoxide, hydrogen, hydrocarbons and the like, such as combustion exhaust gas from a fixed combustion device and a gasoline engine, a diesel engine or the like, which burns under oxygen excess conditions. From combustion exhaust gas containing more than the theoretical reaction amount for unburned components,
An object of the present invention is to provide an exhaust gas purifying material and an exhaust gas purifying method capable of efficiently reducing and removing nitrogen oxides.

【００１０】[0010]

【課題を解決するための手段】上記課題に鑑み鋭意研究
の結果、本発明者は、多孔質無機酸化物に銀成分を担持
してなる触媒上で、エタノールなどの有機化合物が、酸
素及び窒素酸化物を含む排ガスと反応し、窒素酸化物を
窒素ガスに還元するとともに、副生成物としてアルデヒ
ド、炭化水素、一酸化炭素を生成していることを見出し
た。生成されたアルデヒドを利用して効果的に窒素酸化
物を除去できる第二の銀系触媒を設けて、さらに炭化水
素、一酸化炭素を酸化除去する白金系成分を担持してな
る触媒とを組み合わせて形成される排ガス浄化材を用
い、排ガス中に炭化水素と炭素数２以上の含酸素有機化
合物のいずれか又はそれらを含む燃料を添加し、特定の
温度及び空間速度で上記の浄化材に排ガスを接触させれ
ば、広い温度領域で窒素酸化物を効果的に除去すること
ができることを発見し、本発明を完成した。Means for Solving the Problems In view of the above problems, as a result of intensive studies, the present inventor has found that an organic compound such as ethanol is converted to oxygen and nitrogen on a catalyst comprising a porous inorganic oxide carrying a silver component. It has been found that it reacts with exhaust gas containing oxides to reduce nitrogen oxides to nitrogen gas and to generate aldehydes, hydrocarbons and carbon monoxide as by-products. A second silver-based catalyst that can effectively remove nitrogen oxides by using the generated aldehyde is provided, and further combined with a catalyst that carries a platinum-based component that oxidizes and removes hydrocarbons and carbon monoxide. Using an exhaust gas purifying material formed by adding hydrocarbons and oxygen-containing organic compounds having 2 or more carbon atoms or a fuel containing them into the exhaust gas, and applying the exhaust gas to the purifying material at a specific temperature and space velocity. And found that nitrogen oxides could be effectively removed in a wide temperature range, and completed the present invention.

【００１１】すなわち、窒素酸化物と、共存する未燃焼
成分に対する理論反応量より多い酸素とを含む燃焼排ガ
スから窒素酸化物を還元除去する本発明の第一の排ガス
浄化材は、多孔質の無機酸化物に活性種として銀及び／
又は銀化合物、又はそれらの混合物０．２〜１２重量％
（銀元素換算値）を担持してなる第一の触媒と、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．５〜１５重量％（銀元素換算値）
かつ前記第一の触媒の活性種の担持率より多い量を担持
してなる第二の触媒とからなり、浄化材の排ガス流入側
から流出側へ順に前記第一の触媒、前記第二の触媒を有
することを特徴とする。That is, the first exhaust gas purifying material of the present invention for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen that is larger than the theoretical reaction amount of coexisting unburned components is a porous inorganic material. Silver and / or
Or 0.2 to 12% by weight of a silver compound or a mixture thereof
(A silver element conversion value), and a porous inorganic oxide containing silver and / or a silver compound as an active species or a mixture thereof in an amount of 0.5 to 15% by weight (silver element conversion value). )
And a second catalyst carrying an amount larger than the active catalyst loading rate of the first catalyst, and the first catalyst and the second catalyst in order from the exhaust gas inflow side to the outflow side of the purification material. It is characterized by having.

【００１２】また、窒素酸化物と、共存する未燃焼成分
に対する理論反応量より多い酸素とを含む燃焼排ガスか
ら窒素酸化物を還元除去する本発明の第二の排ガス浄化
材は、多孔質の無機酸化物に活性種として銀及び／又は
銀化合物、又はそれらの混合物０．２〜１２重量％（銀
元素換算値）を担持してなる第一の触媒と、多孔質の無
機酸化物に活性種として銀及び／又は銀化合物、又はそ
れらの混合物０．５〜１５重量％（銀元素換算値）かつ
前記第一の触媒の活性種の担持率より多い量を担持して
なる第二の触媒と、多孔質の無機酸化物に活性種として
Pt、Pd、Ru、Rh、Ir及びAuからなる群より選ばれた少な
くとも１種の元素０．０１〜５重量％（金属元素換算
値）を担持してなる第三の触媒とからなり、浄化材の排
ガス流入側から流出側へ順に前記第一の触媒、前記第二
の触媒、前記第三触媒を有することを特徴とする。A second exhaust gas purifying material of the present invention for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen in an amount larger than the theoretical reaction amount for coexisting unburned components is a porous inorganic material. A first catalyst in which silver and / or a silver compound or a mixture thereof is supported as an active species on an oxide at 0.2 to 12% by weight (in terms of silver element); A second catalyst comprising silver and / or a silver compound or a mixture thereof in an amount of 0.5 to 15% by weight (in terms of silver element) and an amount larger than the active species loading of the first catalyst; , As active species on porous inorganic oxides
A third catalyst carrying at least one element selected from the group consisting of Pt, Pd, Ru, Rh, Ir and Au in an amount of 0.01 to 5% by weight (in terms of a metal element); The material is characterized by having the first catalyst, the second catalyst, and the third catalyst in order from the exhaust gas inflow side to the outflow side of the material.

【００１３】さらに、窒素酸化物と、共存する未燃焼成
分に対する理論反応量より多い酸素とを含む燃焼排ガス
から窒素酸化物を還元除去する本発明の第三の排ガス浄
化材は、多孔質の無機酸化物に活性種として銀及び／又
は銀化合物、又はそれらの混合物０．２〜１２重量％
（銀元素換算値）を担持してなる第一の触媒と、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．５〜１５重量％（銀元素換算値）
かつ前記第一の触媒の活性種の担持率より多い量を担持
してなる第二の触媒と、多孔質の無機酸化物に活性種と
してPt、Pd、Ru、Rh、Ir及びAuからなる群より選ばれた
少なくとも１種の元素０．０１〜５重量％（金属元素換
算値）を担持してなる第三の触媒とからなり、前記第二
の触媒と前記第三の触媒とが混合されており、浄化材の
排ガス流入側から流出側へ順に前記第一の触媒、前記第
二の触媒、前記混合触媒を有することを特徴とする。Further, the third exhaust gas purifying material of the present invention for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen in an amount larger than the theoretical reaction amount of coexisting unburned components is a porous inorganic material. 0.2 to 12% by weight of silver and / or a silver compound or a mixture thereof as an active species in the oxide
(A silver element conversion value), and a porous inorganic oxide containing silver and / or a silver compound as an active species or a mixture thereof in an amount of 0.5 to 15% by weight (silver element conversion value). )
And a second catalyst, which carries an amount of the active species greater than the active species of the first catalyst, and a group consisting of Pt, Pd, Ru, Rh, Ir, and Au as active species on a porous inorganic oxide. A third catalyst supporting at least one element selected from the group consisting of 0.01 to 5% by weight (in terms of a metal element), wherein the second catalyst and the third catalyst are mixed. The first catalyst, the second catalyst, and the mixed catalyst are provided in order from the exhaust gas inflow side to the outflow side of the purification material.

【００１４】窒素酸化物と、共存する未燃焼成分に対す
る理論反応量より多い酸素とを含む燃焼排ガスから窒素
酸化物を還元除去する本発明の排ガス浄化方法は、上記
の排ガス浄化材を用い、前記排ガス浄化材を排ガス導管
の途中に設置し、前記浄化材の上流側で炭化水素及び／
又は含酸素有機化合物を添加した排ガスを、１５０〜６
５０℃において前記浄化材に接触させ、もって前記排ガ
ス中の炭化水素及び／又は含酸素有機化合物との反応に
より前記窒素酸化物を除去することを特徴とする。The exhaust gas purifying method of the present invention for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen which is larger than the theoretical reaction amount of coexisting unburned components uses the above exhaust gas purifying material, An exhaust gas purifying material is installed in the middle of the exhaust gas conduit, and hydrocarbons and / or
Alternatively, the exhaust gas to which the oxygen-containing organic compound is added is
The method is characterized in that the nitrogen oxides are removed by contacting the purification material at 50 ° C. with a hydrocarbon and / or an oxygen-containing organic compound in the exhaust gas.

【００１５】以下、本発明を詳細に説明する。本発明の
第一の排ガス浄化材では、多孔質の無機酸化物に活性種
として銀及び／又は銀化合物、又はそれらの混合物０．
２〜１２重量％（銀元素換算値）を担持してなる第一の
触媒と、多孔質の無機酸化物に活性種として銀及び／又
は銀化合物、又はそれらの混合物０．５〜１５重量％
（銀元素換算値）かつ前記第一の触媒の活性種の担持率
より多い量を担持してなる第二の触媒とからなり、浄化
材の排ガス流入側から流出側へ順に前記第一の触媒及び
前記第二の触媒を有する排ガス浄化材を排ガス導管中に
設置し、浄化材の設置位置より上流側で炭化水素と炭素
数２以上の含酸素有機化合物のいずれか又はそれを含む
燃料を添加した排ガスをこの浄化材に接触させて、排ガ
ス中の窒素酸化物を還元除去する。このような配置とす
ることによって、広い排ガス温度領域で窒素酸化物を効
果的に還元除去することができる。Hereinafter, the present invention will be described in detail. In the first exhaust gas purifying material of the present invention, silver and / or a silver compound or a mixture thereof is used as an active species in a porous inorganic oxide.
A first catalyst supporting 2 to 12% by weight (in terms of silver element), and silver and / or a silver compound as an active species in a porous inorganic oxide, or a mixture of 0.5 to 15% by weight thereof;
And a second catalyst which carries a larger amount of the active species than the first catalyst (in terms of silver element), and the first catalyst in order from the exhaust gas inflow side to the outflow side of the purification material. And installing an exhaust gas purifying material having the second catalyst in an exhaust gas conduit, and adding either hydrocarbon or an oxygen-containing organic compound having 2 or more carbon atoms or a fuel containing the same upstream of the purifying material installation position. The exhaust gas thus brought into contact with the purifying material is used to reduce and remove nitrogen oxides in the exhaust gas. With such an arrangement, nitrogen oxides can be effectively reduced and removed in a wide exhaust gas temperature range.

【００１６】本発明の第二の排ガス浄化材では、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．２〜１２重量％（銀元素換算値）
を担持してなる第一の触媒と、多孔質の無機酸化物に活
性種として銀及び／又は銀化合物、又はそれらの混合物
０．５〜１５重量％（銀元素換算値）かつ前記第一の触
媒の活性種の担持率より多い量を担持してなる第二の触
媒と、多孔質の無機酸化物に活性種としてPt、Pd、Ru、
Rh、Ir及びAuからなる群より選ばれた少なくとも１種の
元素０．０１〜５重量％（金属元素換算値）を担持して
なる第三の触媒とからなり、浄化材の排ガス流入側から
流出側へ順に前記第一の触媒、前記第二の触媒、前記第
三触媒を有する排ガス浄化材を排ガス導管中に設置し、
浄化材の設置位置より上流側で炭化水素と炭素数２以上
の含酸素有機化合物のいずれか又はそれを含む燃料を添
加した排ガスをこの浄化材に接触させて、排ガス中の窒
素酸化物を還元除去する。In the second exhaust gas purifying material of the present invention, silver and / or a silver compound or a mixture thereof is used as an active species in a porous inorganic oxide in an amount of 0.2 to 12% by weight (in terms of silver element).
And a silver and / or silver compound as an active species in a porous inorganic oxide, or a mixture thereof in an amount of 0.5 to 15% by weight (in terms of silver element) and the first catalyst. The second catalyst, which carries a larger amount than the loading of the active species of the catalyst, and Pt, Pd, Ru, as active species on the porous inorganic oxide.
A third catalyst supporting at least one element selected from the group consisting of Rh, Ir, and Au in an amount of 0.01 to 5% by weight (in terms of a metal element); An exhaust gas purifying material having the first catalyst, the second catalyst, and the third catalyst in order to an outflow side is installed in an exhaust gas conduit,
An exhaust gas to which a hydrocarbon and / or an oxygen-containing organic compound having 2 or more carbon atoms or a fuel containing the same has been added is brought into contact with the purification material on the upstream side of the purification material to reduce nitrogen oxides in the exhaust gas. Remove.

【００１７】本発明の第三の排ガス浄化材では、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．２〜１２重量％（銀元素換算値）
を担持してなる第一の触媒と、多孔質の無機酸化物に活
性種として銀及び／又は銀化合物、又はそれらの混合物
０．５〜１５重量％（銀元素換算値）かつ前記第一の触
媒の活性種の担持率より多い量を担持してなる第二の触
媒と、多孔質の無機酸化物に活性種としてPt、Pd、Ru、
Rh、Ir及びAuからなる群より選ばれた少なくとも１種の
元素０．０１〜５重量％（金属元素換算値）を担持して
なる第三の触媒とからなり、前記第二の触媒と前記第三
の触媒とが混合されており、浄化材の排ガス流入側から
流出側へ順に前記第一の触媒、前記第二の触媒、前記混
合触媒を有する排ガス浄化材を排ガス導管中に設置し、
浄化材の設置位置より上流側で炭化水素と炭素数２以上
の含酸素有機化合物のいずれか又はそれを含む燃料を添
加した排ガスをこの浄化材に接触させて、排ガス中の窒
素酸化物を還元除去する。In the third exhaust gas purifying material of the present invention, silver and / or a silver compound or a mixture thereof is used as an active species in a porous inorganic oxide in an amount of 0.2 to 12% by weight (in terms of silver element).
And a silver and / or silver compound as an active species in a porous inorganic oxide, or a mixture thereof in an amount of 0.5 to 15% by weight (in terms of silver element) and the first catalyst. The second catalyst, which carries a larger amount than the loading of the active species of the catalyst, and Pt, Pd, Ru, as active species on the porous inorganic oxide.
A third catalyst supporting at least one element selected from the group consisting of Rh, Ir, and Au in an amount of 0.01 to 5% by weight (in terms of a metal element); A third catalyst is mixed, the first catalyst, the second catalyst, an exhaust gas purifying material having the mixed catalyst in the exhaust gas conduit in order from the exhaust gas inflow side to the outflow side of the purifying material,
An exhaust gas to which a hydrocarbon and / or an oxygen-containing organic compound having 2 or more carbon atoms or a fuel containing the same has been added is brought into contact with the purification material on the upstream side of the purification material to reduce nitrogen oxides in the exhaust gas. Remove.

【００１８】本発明の排ガス浄化材の第一の好ましい形
態は、粉末状の多孔質無機酸化物に触媒活性種を担持し
てなる触媒を浄化材基体にコートしてなる浄化材であ
る。浄化材の基体を形成するセラミックス材料として
は、γ−アルミナ及びその酸化物（γ−アルミナ−チタ
ニア、γ−アルミナ−シリカ、γ−アルミナ−ジルコニ
ア等）、ジルコニア、チタニア−ジルコニアなどの多孔
質で表面積の大きい耐熱性のものが挙げられる。高耐熱
性が要求される場合、コージェライト、ムライト、アル
ミナ及びその複合物等を用いるのが好ましい。また、排
ガス浄化材の基体に公知の金属材料を用いることもでき
る。A first preferred embodiment of the exhaust gas purifying material of the present invention is a purifying material obtained by coating a purifying material substrate with a catalyst comprising a powdery porous inorganic oxide carrying catalytically active species. Examples of the ceramic material forming the substrate of the purifying material include porous materials such as γ-alumina and its oxides (γ-alumina-titania, γ-alumina-silica, γ-alumina-zirconia, etc.), zirconia, titania-zirconia, and the like. A heat-resistant material having a large surface area can be used. When high heat resistance is required, it is preferable to use cordierite, mullite, alumina and a composite thereof. In addition, a known metal material can be used for the base of the exhaust gas purifying material.

【００１９】排ガス浄化材の基体の形状及び大きさは、
目的に応じて種々変更できる。実用的には、入口部分、
中間部分及び出口部分等、二つ以上の部分からなること
が好ましい。またその構造としては、ハニカム構造型、
フォーム型、繊維状耐火物からなる三次元網目構造型、
あるいは顆粒状、ペレット状等が挙げられる。The shape and size of the substrate of the exhaust gas purifying material
Various changes can be made according to the purpose. Practically, at the entrance,
It is preferred that it comprises two or more parts, such as an intermediate part and an outlet part. In addition, as its structure, honeycomb structure type,
Foam type, three-dimensional network structure type made of fibrous refractory,
Alternatively, granules, pellets and the like can be mentioned.

【００２０】本発明の排ガス浄化材の第二の好ましい形
態は、ペレット状又は顆粒状粉末状の多孔質無機酸化物
に触媒活性種を担持してなる触媒、又は触媒活性種をそ
れぞれ担持した粉末状多孔質無機酸化物をペレット状又
は顆粒状に成形したものを所望形状のケーシングに充填
してなる浄化材である。A second preferred embodiment of the exhaust gas purifying material of the present invention is a catalyst comprising a porous inorganic oxide in the form of a pellet or a granular powder carrying a catalytically active species, or a powder comprising a catalytically active species, respectively. It is a purifying material obtained by molding a porous inorganic oxide into pellets or granules into a casing having a desired shape.

【００２１】本発明の浄化材には以下の触媒が形成され
ている。 （１）第一の触媒及び第二の触媒 第一の触媒及び第二の触媒は、多孔質無機酸化物に銀及
び／又は銀化合物、又はそれらの混合物を担持してな
り、排ガスの流入側に形成され、広い温度領域での窒素
酸化物除去に作用する。銀化合物は銀の酸化物、ハロゲ
ン化銀、硫酸銀及び燐酸銀などからなる群より選ばれた
少なくとも一種であり、好ましくは銀の酸化物、塩化銀
及び硫酸銀のいずれか一種以上であり、更に好ましくは
銀の酸化物及び／又は塩化銀である。多孔質の無機酸化
物としては、多孔質のアルミナ、シリカ、チタニア、ジ
ルコニア、ゼオライト及びそれらの複合酸化物等を使用
することができるが、好ましくはアルミナ単独、アルミ
ナを含む複合酸化物又はアルミナを含む混合酸化物のい
ずれかを用いる。アルミナ、又はその複合、混合酸化物
を用いることにより、添加した炭化水素、含酸素有機化
合物及び／又は排ガス中の残留炭化水素と排ガス中の窒
素酸化物との反応が効率良く起こる。特にアルミナ複合
酸化物又はアルミナ混合酸化物を用いることにより、二
酸化硫黄が存在する環境における触媒の耐久性及び耐熱
性が向上する。The following catalyst is formed on the purification material of the present invention. (1) First catalyst and second catalyst The first catalyst and the second catalyst are formed by supporting silver and / or a silver compound or a mixture thereof on a porous inorganic oxide, and on the inflow side of the exhaust gas. And acts to remove nitrogen oxides in a wide temperature range. The silver compound is at least one selected from the group consisting of silver oxide, silver halide, silver sulfate, silver phosphate, and the like, and is preferably one or more of silver oxide, silver chloride, and silver sulfate, More preferred are silver oxide and / or silver chloride. As the porous inorganic oxide, porous alumina, silica, titania, zirconia, zeolite and composite oxides thereof and the like can be used, preferably alumina alone, a composite oxide containing alumina or alumina. One of the mixed oxides is used. By using alumina, or a composite or mixed oxide thereof, a reaction between added hydrocarbons, oxygen-containing organic compounds and / or residual hydrocarbons in the exhaust gas and nitrogen oxides in the exhaust gas occurs efficiently. In particular, by using an alumina composite oxide or an alumina mixed oxide, the durability and heat resistance of the catalyst in an environment where sulfur dioxide is present are improved.

【００２２】第一の触媒及び第二の触媒で用いるアルミ
ナなどの多孔質の無機酸化物の比表面積は１０ｍ2 ／ｇ
以上であるのが好ましい。比表面積が１０ｍ2 ／ｇ未満
であると、排ガスと無機酸化物（及びこれに担持した銀
成分）との接触面積が小さくなり、良好な窒素酸化物の
除去が行えない。より好ましい多孔質無機酸化物の比表
面積は３０ｍ2 ／ｇ以上である。The specific surface area of the porous inorganic oxide such as alumina used for the first catalyst and the second catalyst is 10 m 2 / g.
It is preferable that this is the case. If the specific surface area is less than 10 m 2 / g, the contact area between the exhaust gas and the inorganic oxide (and the silver component carried thereon) becomes small, and good nitrogen oxides cannot be removed. More preferred specific surface area of the porous inorganic oxide is 30 m 2 / g or more.

【００２３】第一の触媒では、上記したγ−アルミナ等
の無機酸化物に活性種として担持する銀成分の担持量
は、無機酸化物１００重量％に対して０．２〜１２重量
％（銀元素換算値）とする。０．２重量％未満では窒素
酸化物の除去率が低下する。また、１２重量％を超す量
の銀成分を担持すると炭化水素及び／又は含酸素有機化
合物自身の燃焼が起きやすく、窒素酸化物の除去率はか
えって低下する。好ましい銀成分の担持量は０．５〜１
０重量％である。In the first catalyst, the amount of the silver component supported as an active species on the inorganic oxide such as γ-alumina is 0.2 to 12% by weight (100% by weight of the inorganic oxide). (Element conversion value). If the amount is less than 0.2% by weight, the removal rate of nitrogen oxides decreases. If the silver component is carried in an amount exceeding 12% by weight, the combustion of the hydrocarbon and / or the oxygen-containing organic compound itself tends to occur, and the nitrogen oxide removal rate is rather lowered. A preferable silver component loading is 0.5 to 1
0% by weight.

【００２４】第二の触媒では、上記したγ−アルミナ等
の無機酸化物に活性種として担持する銀成分の担持量
は、無機酸化物１００重量％に対して０．５〜１５重量
％（銀元素換算値）で、かつ第一の触媒の活性種の担持
率より多い量とする。つまり、第二の触媒上の銀成分の
含有率を常に第一の触媒上のものより大きくする。１重
量％未満又は第一の触媒の活性種の担持率以下では、第
一の触媒で生成したアルデヒドを用いた窒素酸化物の除
去が行われない。また、１５重量％を超す量の銀成分を
担持すると炭化水素及び／又は含酸素有機化合物自身の
燃焼が起きやすく、窒素酸化物の除去率はかえって低下
する。好ましい第二触媒における銀成分の担持量は１〜
１２重量％である。In the second catalyst, the amount of the silver component supported as an active species on the inorganic oxide such as γ-alumina is 0.5 to 15% by weight (100% by weight of the inorganic oxide). (In terms of element) and more than the loading rate of the active species of the first catalyst. That is, the content of the silver component on the second catalyst is always higher than that on the first catalyst. If the content is less than 1% by weight or less than the active catalyst loading of the first catalyst, the removal of nitrogen oxides using the aldehyde generated by the first catalyst is not performed. If the silver component is carried in an amount exceeding 15% by weight, the combustion of the hydrocarbon and / or the oxygen-containing organic compound itself tends to occur, and the nitrogen oxide removal rate is rather lowered. The supported amount of the silver component in the preferred second catalyst is 1 to
It is 12% by weight.

【００２５】アルミナ等の無機酸化物に銀を担持する方
法としては、公知の含浸法、沈澱法等を用いることがで
きる。含浸法を用いる際、銀の硝酸塩、塩化物、硫酸
塩、炭酸塩等の水溶液又はアンモニア性水溶液に多孔質
無機酸化物を浸漬する。又は硝酸銀水溶液に多孔質無機
酸化物を浸漬し、乾燥後、塩化アンモニウム又は硫酸ア
ンモニウムの水溶液に再び浸漬する。沈澱法では硝酸銀
とハロゲン化アンモニウムとを反応させて、ハロゲン化
銀として多孔質無機酸化物上に沈澱させる。これを５０
〜１５０℃、特に７０℃程度で乾燥後、１００〜６００
℃で段階的に昇温して焼成するのが好ましい。焼成は、
空気中、酸素を含む窒素気流下や水素ガス気流下で行う
のが好ましい。水素ガス気流下で行う場合には、最後に
３００〜６５０℃で酸化処理するのが好ましい。As a method for supporting silver on an inorganic oxide such as alumina, a known impregnation method, precipitation method, or the like can be used. When using the impregnation method, the porous inorganic oxide is immersed in an aqueous solution of silver nitrate, chloride, sulfate, carbonate, or the like, or an aqueous ammonia solution. Alternatively, the porous inorganic oxide is immersed in an aqueous solution of silver nitrate, dried, and then immersed again in an aqueous solution of ammonium chloride or ammonium sulfate. In the precipitation method, silver nitrate is reacted with ammonium halide to precipitate silver halide on the porous inorganic oxide. This is 50
After drying at about 150 ° C, especially about 70 ° C, 100 to 600
It is preferred to raise the temperature stepwise at a temperature of ° C. and to perform firing. Firing
It is preferable to carry out in air, under a flow of nitrogen containing oxygen or under a flow of hydrogen gas. When the treatment is performed under a hydrogen gas stream, it is preferable to perform the oxidation treatment at 300 to 650 ° C. at last.

【００２６】硝酸銀等の水溶液を用いて多孔質無機酸化
物に担持された銀成分は酸化雰囲気下で焼成すると円状
集合体を形成することが観測されている。本発明の浄化
材では、銀成分集合体の平均直径を１０〜１００００ｎ
ｍとするのが好ましい。一般的には、銀成分集合体の直
径が小さいほど、反応特性が高いが、平均直径が１０ｎ
ｍ未満であると、還元剤である炭化水素及び／又は含酸
素有機化合物の酸化反応のみが進み、窒素酸化物の除去
率が低下する。一方、平均直径が１００００ｎｍを越え
ると、銀成分の反応特性が低減し、窒素酸化物の除去率
が下がる。好ましい銀成分集合体の平均直径は１０〜５
０００ｎｍ、更に好ましくは１０〜２０００ｎｍとす
る。なお、ここで言う平均とは算術平均のことを意味す
る。It has been observed that a silver component supported on a porous inorganic oxide using an aqueous solution of silver nitrate or the like forms a circular aggregate when fired in an oxidizing atmosphere. In the purification material of the present invention, the average diameter of the silver component aggregate is 10 to 10,000 n
m is preferable. In general, the smaller the diameter of the silver component aggregate, the higher the reaction characteristics, but the average diameter is 10n.
If it is less than m, only the oxidation reaction of the hydrocarbon and / or the oxygen-containing organic compound as the reducing agent proceeds, and the nitrogen oxide removal rate decreases. On the other hand, when the average diameter exceeds 10,000 nm, the reaction characteristics of the silver component are reduced, and the nitrogen oxide removal rate is reduced. The average diameter of the preferred silver component aggregate is 10 to 5
000 nm, more preferably 10 to 2000 nm. Here, the average means an arithmetic average.

【００２７】なお、浄化材の形態を上述した第一の好ま
しい形態とする場合、浄化材基体上に設ける第一の触媒
及び第二の触媒の厚さは、一般に、基体材と、この触媒
との熱膨張特性の違いから制限される場合が多い。浄化
材基体上に設ける触媒の厚さを３００μｍ以下とするの
がよい。このような厚さとすれば、使用中に熱衝撃等で
浄化材が破損することを防ぐことができる。浄化材基体
の表面に触媒を形成する方法は公知のウォシュコート法
等によって行われる。In the case where the form of the purifying material is the above-described first preferred embodiment, the thicknesses of the first catalyst and the second catalyst provided on the purifying material base are generally the same as those of the base material and this catalyst. Are often limited due to differences in thermal expansion characteristics. The thickness of the catalyst provided on the purifying material base is preferably 300 μm or less. With such a thickness, it is possible to prevent the purifying material from being damaged by thermal shock or the like during use. A method for forming a catalyst on the surface of the purifying material base is performed by a known washcoat method or the like.

【００２８】また、浄化材基体の表面上に設ける第一触
媒及び第二の触媒の量は、それぞれ浄化材基体の２０〜
３００ｇ／リットルとするのが好ましい。触媒の量が２
０ｇ／リットル未満では良好なNOx の除去が行えない。
一方、触媒の量が３００ｇ／リットルを超えると除去特
性はそれほど上がらず、圧力損失が大きくなる。より好
ましくは、浄化材基体の表面上に設ける第一の触媒及び
第二の触媒をそれぞれ浄化材基体の５０〜２００ｇ／リ
ットルとする。The amount of the first catalyst and the amount of the second catalyst provided on the surface of the purifying material base are respectively 20 to
Preferably it is 300 g / l. The amount of catalyst is 2
If it is less than 0 g / liter, good NOx removal cannot be performed.
On the other hand, when the amount of the catalyst exceeds 300 g / liter, the removal characteristics do not increase so much and the pressure loss increases. More preferably, the first catalyst and the second catalyst provided on the surface of the purifying material base are each 50 to 200 g / liter of the purifying material base.

【００２９】（２）第三の触媒 第三の触媒は、多孔質無機酸化物に触媒活性種を担持し
てなり、排ガスの流出側に形成され、低い温度領域にお
ける窒素酸化物の除去に作用するとともに、一酸化炭素
や炭化水素の酸化除去を行う。多孔質無機酸化物として
は、アルミナ、チタニア、ジルコニア、シリカ、ゼオラ
イトからなる群より選ばれた一種以上の酸化物又は複合
酸化物を用いるのが好ましい。第一の触媒と同様に、多
孔質の無機酸化物の比表面積は１０ｍ2 ／ｇ以上である
ことが好ましい。(2) Third catalyst The third catalyst comprises a porous inorganic oxide carrying catalytically active species and is formed on the exhaust gas outflow side, and acts to remove nitrogen oxides in a low temperature region. And at the same time, oxidize and remove carbon monoxide and hydrocarbons. As the porous inorganic oxide, it is preferable to use one or more oxides or composite oxides selected from the group consisting of alumina, titania, zirconia, silica, and zeolite. Similar to the first catalyst, the specific surface area of the porous inorganic oxide is preferably 10 m 2 / g or more.

【００３０】上記の第三触媒の活性種としては、Pt、P
d、Ru、Rh、Ir及びAuからなる群より選ばれた少なくと
も１種の元素を用い、Pt、Pd、Ru、Rh及びAuの少なくと
も一種を用いるのが好ましく、特にPt、Pd及びAuの少な
くとも一種が好ましい。第三の触媒で無機酸化物に担持
する活性種の合計は、上述の多孔質の無機酸化物を基準
(100重量％) として０．０１〜５重量％とし、好ましく
は０．０１〜４重量％とする。触媒活性種の量が前記多
孔質無機酸化物に対して、５重量％を超す触媒担持量と
しても窒素酸化物の除去性能が向上しない。The active species of the third catalyst include Pt, P
d, Ru, Rh, using at least one element selected from the group consisting of Ir and Au, it is preferable to use at least one of Pt, Pd, Ru, Rh and Au, particularly at least Pt, Pd and Au One is preferred. The total of the active species supported on the inorganic oxide by the third catalyst is based on the above-mentioned porous inorganic oxide.
(100% by weight) is 0.01 to 5% by weight, preferably 0.01 to 4% by weight. Even when the amount of the catalytically active species exceeds 5% by weight of the porous inorganic oxide, the performance of removing nitrogen oxides is not improved.

【００３１】また、第三の触媒の活性種として、さら
に、La、Ce等の希土類元素、Ca、Mgなどのアルカリ土類
元素、Na、Ｋなどのアルカリ金属元素からなる群より選
ばれた少なくとも一つ以上の元素を１０重量％以下担持
することが好ましい。希土類、アルカリ土類、アルカリ
金属元素を担持することにより、白金系の触媒の耐熱性
を向上させることができる。また、白金系成分に限ら
ず、既知の酸化触媒、三元触媒等を第三の触媒活性種と
して用いることができる。The active species of the third catalyst may further include at least one selected from the group consisting of rare earth elements such as La and Ce, alkaline earth elements such as Ca and Mg, and alkali metal elements such as Na and K. It is preferable to carry one or more elements in an amount of 10% by weight or less. By supporting a rare earth, alkaline earth, or alkali metal element, the heat resistance of a platinum-based catalyst can be improved. In addition, not only platinum-based components but also known oxidation catalysts, three-way catalysts, and the like can be used as the third catalytically active species.

【００３２】第三の触媒における活性種の担持は、公知
の含浸法、沈澱法等を用いることができる。含浸法を用
いる際、触媒活性種元素の塩化物又はヘキサクロロ金属
酸等の水溶液に多孔質無機酸化物を浸漬し、７０℃で乾
燥後、１００〜７００℃で段階的に昇温して焼成するこ
とによって行われる。焼成は窒素気流下、水素含有又は
酸素含有窒素気流下で行い、好ましくは窒素気流下で焼
成した後、水素含有窒素気流下、酸素含有窒素気流下で
それぞれ焼成を行う。なお、Pt系担持成分は金属元素と
して表示しているが、通常の浄化材の使用温度条件では
担持成分は金属と酸化物の状態で存在する。For supporting the active species on the third catalyst, a known impregnation method, precipitation method, or the like can be used. When using the impregnation method, the porous inorganic oxide is immersed in an aqueous solution such as a chloride or hexachlorometallic acid of a catalytically active species element, dried at 70 ° C., and then gradually heated at 100 to 700 ° C. and fired. This is done by: The calcination is performed under a nitrogen stream or a hydrogen-containing or oxygen-containing nitrogen stream. Preferably, the calcination is performed under a nitrogen stream, and then the calcination is performed under a hydrogen-containing nitrogen stream or an oxygen-containing nitrogen stream. Although the Pt-based loading component is shown as a metal element, the loading component exists in a state of a metal and an oxide under a normal use temperature condition of the purification material.

【００３３】なお、浄化材の形態を上述した第一の好ま
しい形態とする場合、浄化材基体上に設ける第三の触媒
の厚さを３００μｍ以下とするのがよい。また、浄化材
基体の表面上に設ける第三の触媒の量は、浄化材基体に
対して２０〜３００ｇ／リットルとするのが好ましい。When the form of the purifying material is the first preferred embodiment described above, the thickness of the third catalyst provided on the purifying material base is preferably 300 μm or less. The amount of the third catalyst provided on the surface of the purifying material base is preferably 20 to 300 g / liter based on the purifying material base.

【００３４】第一の触媒と第二の触媒との重量比（多孔
質無機酸化物と触媒活性種との合計重量の比）は、１：
１０〜１０：１とするのが好ましい。比率が１：１０未
満である（第一の触媒が少ない）と、１５０〜６００℃
の広い温度範囲で全体的に窒素酸化物の浄化率が低下す
る。一方、比率が１０：１を超え、第二の触媒が少ない
と、第一の触媒上でできたアルデヒドが窒素酸化物の還
元に有効に使用されない。より好ましい第一触媒と第二
の触媒の重量比は１：５〜５：１である。The weight ratio of the first catalyst to the second catalyst (the ratio of the total weight of the porous inorganic oxide and the catalytically active species) is 1:
It is preferably 10 to 10: 1. When the ratio is less than 1:10 (the amount of the first catalyst is small), 150 to 600 ° C.
Over a wide temperature range, the purification rate of nitrogen oxides decreases overall. On the other hand, if the ratio exceeds 10: 1 and the amount of the second catalyst is small, the aldehyde formed on the first catalyst is not effectively used for reducing nitrogen oxides. A more preferred weight ratio of the first catalyst to the second catalyst is 1: 5 to 5: 1.

【００３５】本発明の第二の排ガス浄化材においては、
第一の触媒及び第二の触媒の合計重量と第三の触媒の重
量との比（多孔質無機酸化物と触媒活性種との合計重量
の比）は、１０：１〜１：５とするのが好ましい。比率
が１：５未満である（第一の触媒及び第二の触媒が少な
い）と、１５０〜６００℃の広い温度範囲で全体的に窒
素酸化物の浄化率が低下する。一方、比率が１０：１を
超え、第三の触媒が少ないと、炭化水素、一酸化炭素が
除去されず、そのまま排出されたる。より好ましい第一
の触媒及び第二の触媒の合計重量と第三の触媒の重量と
の比は５：１〜１：４である。In the second exhaust gas purifying material of the present invention,
The ratio of the total weight of the first catalyst and the second catalyst to the weight of the third catalyst (ratio of the total weight of the porous inorganic oxide and the catalytically active species) is 10: 1 to 1: 5. Is preferred. When the ratio is less than 1: 5 (the amount of the first catalyst and the amount of the second catalyst are small), the purification rate of nitrogen oxides is generally reduced in a wide temperature range of 150 to 600 ° C. On the other hand, when the ratio exceeds 10: 1 and the amount of the third catalyst is small, hydrocarbons and carbon monoxide are not removed and are discharged as they are. More preferably, the ratio of the total weight of the first catalyst and the second catalyst to the weight of the third catalyst is 5: 1 to 1: 4.

【００３６】本発明の第三の排ガス浄化材では、第二の
触媒と第三の触媒を混合して用いる。この混合によっ
て、第二の触媒の還元作用と第三の触媒の酸化作用が互
いに影響することなく同時に進行することができる。浄
化材が上記第一の好ましい形態である場合、浄化材基体
上に設ける第二の触媒と第三の触媒との混合触媒の厚さ
を３００μｍ以下とするのがよい。また、浄化材基体の
表面上に設ける第二の触媒と第三の触媒との混合触媒の
量は、浄化材基体に対して２０〜３００ｇ／リットルと
するのが好ましい。In the third exhaust gas purifying material of the present invention, a mixture of the second catalyst and the third catalyst is used. By this mixing, the reducing action of the second catalyst and the oxidizing action of the third catalyst can proceed simultaneously without affecting each other. In the case where the purifying material is the first preferred embodiment, the thickness of the mixed catalyst of the second catalyst and the third catalyst provided on the purifying material base is preferably 300 μm or less. Further, the amount of the mixed catalyst of the second catalyst and the third catalyst provided on the surface of the purifying material base is preferably 20 to 300 g / liter with respect to the purifying material base.

【００３７】第二の触媒と第三の触媒との重量比（多孔
質無機酸化物と触媒活性種との合計重量の比）は、２：
１〜２００：１とするのが好ましい。第二の触媒２００
重量部に対して第三の触媒が１重量部未満の場合では、
炭化水素、一酸化炭素の除去率が低下する。一方、第二
の触媒２重量部に対して第三の触媒が１重量部を越える
と、１５０〜６５０℃の広い温度範囲で全体的に窒素酸
化物の浄化率が低下する。より好ましい第二の触媒と第
三の触媒の重量比は５：１〜１００：１である。The weight ratio of the second catalyst to the third catalyst (the ratio of the total weight of the porous inorganic oxide to the catalytically active species) is 2:
The ratio is preferably 1 to 200: 1. Second catalyst 200
In the case where the third catalyst is less than 1 part by weight based on parts by weight,
The removal rate of hydrocarbons and carbon monoxide decreases. On the other hand, if the third catalyst exceeds 1 part by weight with respect to 2 parts by weight of the second catalyst, the purification rate of nitrogen oxides as a whole decreases over a wide temperature range of 150 to 650 ° C. More preferably, the weight ratio of the second catalyst to the third catalyst is 5: 1 to 100: 1.

【００３８】第一の触媒と、第二の触媒と第三の触媒と
の混合触媒との重量比（多孔質無機酸化物と触媒活性種
との合計重量の比）は、１：１０〜１０：１とするのが
好ましい。比率が１：１０未満である（第一の触媒が少
ない）と、１５０〜６００℃の広い温度範囲で全体的に
窒素酸化物の浄化率が低下する。一方、比率が１０：１
を超え、混合触媒が少ないと、第一の触媒上でできたア
ルデヒドが反応せず、そのまま排出されたり、一酸化炭
素、炭化水素の除去率が低下する。より好ましい第一触
媒と混合触媒の重量比は１：５〜５：１である。The weight ratio of the first catalyst to the mixed catalyst of the second catalyst and the third catalyst (the ratio of the total weight of the porous inorganic oxide to the catalytically active species) is from 1:10 to 10: : 1 is preferred. If the ratio is less than 1:10 (the amount of the first catalyst is small), the overall nitrogen oxide purification rate is reduced in a wide temperature range of 150 to 600 ° C. On the other hand, the ratio is 10: 1
When the amount of the mixed catalyst is less than the above, the aldehyde formed on the first catalyst does not react and is discharged as it is, or the removal rate of carbon monoxide and hydrocarbons decreases. A more preferred weight ratio of the first catalyst to the mixed catalyst is 1: 5 to 5: 1.

【００３９】上述した構成の浄化材を用いれば、１５０
〜６５０℃の広い温度領域において、水分１０％程度及
び硫黄酸化物を含む排ガスでも、良好な窒素酸化物の除
去を行うことができる。If the purifying material having the above configuration is used, 150
In a wide temperature range of up to 650 ° C., excellent removal of nitrogen oxides can be performed even with an exhaust gas containing about 10% of moisture and sulfur oxides.

【００４０】次に、本発明の方法について説明する。ま
ず、本発明の第一の排ガス浄化材を用いる場合、浄化材
の排ガス流入側から流出側へ順に第一の触媒及び第二の
触媒を排ガス導管の途中に設置する。Next, the method of the present invention will be described. First, when the first exhaust gas purifying material of the present invention is used, the first catalyst and the second catalyst are installed in the exhaust gas conduit in order from the exhaust gas inflow side to the outflow side of the purifying material.

【００４１】本発明の第二の排ガス浄化材を用いる場
合、浄化材の排ガス流入側から流出側へ順に第一の触
媒、第二の触媒及び第三の触媒を排ガス導管の途中に設
置する。When the second exhaust gas purifying material of the present invention is used, the first catalyst, the second catalyst, and the third catalyst are arranged in the exhaust gas conduit in order from the exhaust gas inflow side to the outflow side of the purifying material.

【００４２】本発明の第三の排ガス浄化材を用いる場
合、浄化材の排ガス流入側から流出側へ順に第一の触
媒、第二の触媒と第三の触媒の混合触媒を排ガス導管の
途中に設置する。When the third exhaust gas purifying material of the present invention is used, the first catalyst, the mixed catalyst of the second catalyst and the third catalyst are arranged in the exhaust gas conduit in order from the exhaust gas inflow side to the outflow side of the purifying material. Install.

【００４３】排ガス中には、残留炭化水素としてエチレ
ン、プロピレン等がある程度は含まれるが、一般に排ガ
ス中のNOx を還元するのに十分な量ではないので、外部
から炭化水素及び／又は含酸素有機化合物、好ましくは
含酸素有機化合物又はそれと炭化水素燃料と混合してな
る還元剤を排ガス中に導入する。還元剤の導入位置は、
浄化材を設置した位置より上流側である。Although the exhaust gas contains ethylene, propylene and the like to some extent as residual hydrocarbons, the amount is generally not sufficient to reduce NOx in the exhaust gas. A compound, preferably an oxygen-containing organic compound or a reducing agent obtained by mixing the compound with a hydrocarbon fuel is introduced into the exhaust gas. The introduction position of the reducing agent
It is upstream from the position where the purifying material is installed.

【００４４】外部から導入する炭化水素としては、標準
状態でガス状又は液体状のアルカン、アルケン及び／又
はアルキンを用いることができる。特にアルカン又はア
ルケンの場合では炭素数２以上が好ましい。標準状態で
液体状の炭化水素としては、具体的に、軽油、セタン、
ヘプタン、灯油、ガソリン等の炭化水素が挙げられる。
その中でも、沸点５０〜３５０℃の炭化水素が特に好ま
しい。外部から導入する含酸素有機化合物として、炭素
数２以上のエタノール、イソプロピルアルコール等のア
ルコール類、又はそれらを含む燃料を用いることができ
る。As the hydrocarbons introduced from the outside, gaseous or liquid alkanes, alkenes and / or alkynes can be used under standard conditions. In particular, in the case of an alkane or alkene, it preferably has 2 or more carbon atoms. Specific examples of hydrocarbons that are liquid in the standard state include gas oil, cetane,
Examples include hydrocarbons such as heptane, kerosene, gasoline and the like.
Among them, hydrocarbons having a boiling point of 50 to 350 ° C are particularly preferable. As the oxygen-containing organic compound introduced from the outside, alcohols such as ethanol and isopropyl alcohol having 2 or more carbon atoms, or a fuel containing them can be used.

【００４５】外部から導入する炭化水素及び／又は含酸
素有機化合物の量は、重量比（添加する還元剤の重量／
排ガス中の窒素酸化物の重量）が０．１〜５となるよう
にするのが好ましい。この重量比が０．１未満である
と、窒素酸化物の除去率が大きくならない。一方、５を
超えると、燃費悪化につながる。The amount of the hydrocarbon and / or oxygen-containing organic compound introduced from the outside is determined by the weight ratio (weight of the reducing agent to be added / weight).
(Weight of nitrogen oxides in the exhaust gas) is preferably 0.1 to 5. If the weight ratio is less than 0.1, the removal rate of nitrogen oxides does not increase. On the other hand, if it exceeds 5, fuel efficiency will be degraded.

【００４６】また、炭化水素又は含酸素有機化合物を含
有する燃料を添加する場合、燃料としてガソリン、軽
油、灯油などを用いるのが好ましい。この場合、還元剤
の量は上記と同様に重量比（添加する還元剤の重量／排
ガス中の窒素酸化物の重量）が０．１〜５となるように
設定する。When a fuel containing a hydrocarbon or an oxygen-containing organic compound is added, it is preferable to use gasoline, light oil, kerosene or the like as the fuel. In this case, the amount of the reducing agent is set such that the weight ratio (the weight of the reducing agent to be added / the weight of the nitrogen oxide in the exhaust gas) is 0.1 to 5 in the same manner as described above.

【００４７】本発明では、含酸素有機化合物、炭化水素
又はアンモニア等による窒素酸化物の還元除去を効率的
に進行させるために、本発明の第一及び第二の排ガス浄
化材では、第一の触媒及び第二の触媒における空間速度
はそれぞれ 200,000ｈ-1以下、好ましくは 150,000ｈ-1
以下とする。また、第三の触媒の空間速度は 250,000ｈ
-1以下、好ましくは 200,000ｈ-1以下とする。第一の触
媒及び第二の触媒の空間速度が 200,000ｈ-1を越える
と、窒素酸化物の還元反応が十分に起こらず、窒素酸化
物の除去率が低下する。本発明の第三の排ガス浄化材で
は、第二の触媒と第三の触媒との混合触媒の空間速度は
200,000ｈ-1以下、好ましくは 150,000ｈ-1以下とす
る。排ガス中に硫黄酸化物が共存する場合、空間速度の
下限は10,000ｈ-1とするのが好ましい。空間速度の下限
が10,000ｈ-1以下になると、硫黄酸化物の酸化特性が上
昇するので好ましくない。In the present invention, the first and second exhaust gas purifying materials of the present invention employ the first and second exhaust gas purifying materials in order to efficiently promote the reduction and removal of nitrogen oxides by an oxygen-containing organic compound, hydrocarbon, ammonia, or the like. The space velocities of the catalyst and the second catalyst are each 200,000 h -1 or less, preferably 150,000 h -1.
The following is assumed. The space velocity of the third catalyst is 250,000h
-1 or less, preferably 200,000 h -1 or less. When the space velocity of the first catalyst and the second catalyst exceeds 200,000 h -1 , the reduction reaction of nitrogen oxides does not sufficiently occur, and the nitrogen oxide removal rate decreases. In the third exhaust gas purifying material of the present invention, the space velocity of the mixed catalyst of the second catalyst and the third catalyst is
200,000 -1 or less, preferably 150,000H -1 or less. When sulfur oxides coexist in the exhaust gas, the lower limit of the space velocity is preferably 10,000 h -1 . If the lower limit of the space velocity is 10,000 h -1 or less, the oxidation characteristics of sulfur oxides are undesirably increased.

【００４８】また、本発明では、炭化水素及び／又は含
酸素有機化合物と窒素酸化物とが反応する部位である浄
化材設置部位における排ガスの温度を１５０〜６５０℃
に保つ。排ガスの温度が１５０℃未満であると還元剤と
窒素酸化物との反応が進行せず、良好な窒素酸化物の除
去を行うことができない。一方、６５０℃を超す温度と
すると炭化水素及び／又は含酸素有機化合物自身の燃焼
が始まり、窒素酸化物の還元除去が行えない。好ましい
排ガス温度は２００〜５５０℃であり、より好ましくは
３００〜５００℃である。Further, in the present invention, the temperature of the exhaust gas at the purification material installation site where the hydrocarbon and / or the oxygen-containing organic compound reacts with the nitrogen oxide is set at 150 to 650 ° C.
To keep. If the temperature of the exhaust gas is lower than 150 ° C., the reaction between the reducing agent and the nitrogen oxide does not proceed, and it is not possible to remove the nitrogen oxide satisfactorily. On the other hand, if the temperature exceeds 650 ° C., combustion of the hydrocarbon and / or the oxygen-containing organic compound itself starts, and reduction and removal of nitrogen oxides cannot be performed. The preferred exhaust gas temperature is from 200 to 550C, more preferably from 300 to 500C.

【００４９】[0049]

【実施例】本発明を以下の具体的実施例によりさらに詳
細に説明する。実施例１ 市販のγ−アルミナ粉末（比表面積２００ｍ2 ／ｇ）を
硝酸銀水溶液に浸漬したあと取り出して、７０℃で２時
間乾燥した。そして、空気中で、段階的に６００℃まで
昇温したあと、５時間焼成し、アルミナに対して３重量
％（金属元素換算値）の銀を担持した第一の触媒を調製
した。第一の触媒０．２６ｇを、市販のコージェライト
製ハニカム状成形体（直径２０ｍｍ、長さ８．３ｍｍ、
４００セル／インチ2 ）にコートし、乾燥後６００℃ま
で段階的に焼成し、銀系浄化材（第一の触媒をコートし
た浄化材）を調製した。The present invention will be described in more detail with reference to the following specific examples. Example 1 A commercially available γ-alumina powder (specific surface area: 200 m 2 / g) was immersed in an aqueous silver nitrate solution, taken out, and dried at 70 ° C. for 2 hours. Then, the temperature was gradually raised to 600 ° C. in the air, and the mixture was calcined for 5 hours to prepare a first catalyst supporting 3% by weight (in terms of metal element) of silver with respect to alumina. 0.26 g of the first catalyst was used as a commercially available cordierite honeycomb-shaped formed body (diameter 20 mm, length 8.3 mm,
The coating was carried out at 400 cells / inch 2 ), dried and baked stepwise to 600 ° C. to prepare a silver-based purifying material (a purifying material coated with a first catalyst).

【００５０】上記銀系触媒と同じ方法で、粉末状アルミ
ナに５重量％（金属元素換算値）の銀を担持した第二の
触媒を調製し、上記と同様なハニカム状成形体に第二の
触媒０．２６ｇをコートし、同じ方法で第二の銀系浄化
材（第二の触媒をコートした浄化材）を調製した。A second catalyst in which 5% by weight (in terms of metal element) of silver was supported on powdered alumina was prepared in the same manner as the above-mentioned silver-based catalyst. 0.26 g of the catalyst was coated, and a second silver-based purifying material (a purifying material coated with the second catalyst) was prepared in the same manner.

【００５１】次に、粉末状チタニア（比表面積３５ｍ2
／ｇ）を塩化白金酸水溶液に２０分間浸漬した後、空気
中、８０℃で２時間乾燥し、窒素気流下で１２０℃で２
時間、２００〜４００℃まで段階的に各１時間焼成し
た。そして、水素ガス４％を含む窒素気流下で５０℃〜
４００℃まで５時間かけて昇温し、４００℃で４時間焼
成し、さらに、酸素を１０％含む窒素気流下で５０℃〜
５００℃まで５時間かけて昇温し、５００℃で５時間焼
成し、チタニアに対してPtを０．１重量％（金属元素換
算値）担持した第三の触媒を調製した。上記銀系浄化材
と同様なハニカム成形体（直径２０ｍｍ、長さ６．６ｍ
ｍ、４００セル／インチ2 ）に０．２１ｇのスラリー化
した第三の触媒をコートし、銀系浄化材と同じ条件で乾
燥、焼成を行い、白金系浄化材（第三の触媒をコートし
た浄化材）を調製した。Next, powdered titania (specific surface area 35 m 2
/ G) in a chloroplatinic acid aqueous solution for 20 minutes, dried in air at 80 ° C. for 2 hours, and dried at 120 ° C. in a nitrogen stream at 120 ° C.
The firing was carried out step by step from 200 to 400 ° C. for 1 hour each. Then, under a nitrogen gas flow containing 4% of hydrogen gas, 50 ° C.
The temperature was raised to 400 ° C. over 5 hours, calcined at 400 ° C. for 4 hours, and further heated to 50 ° C. under a nitrogen stream containing 10% oxygen.
The temperature was raised to 500 ° C. over 5 hours and calcined at 500 ° C. for 5 hours to prepare a third catalyst carrying 0.1% by weight (converted to metal element) of Pt with respect to titania. Honeycomb molded body (diameter 20 mm, length 6.6 m) similar to the above-mentioned silver-based purifying material
m, 400 cells / inch 2 ) was coated with 0.21 g of the slurried third catalyst, dried and calcined under the same conditions as the silver-based purifying material to form a platinum-based purifying material (the third catalyst was coated). Purification material).

【００５２】反応管内の排ガスの流入側から流出側へ順
に銀系浄化材、第二の銀系浄化材、白金系浄化材をセッ
トした。次に、表１に示す組成のガス（一酸化窒素、酸
素、エタノール、二酸化硫黄、窒素及び水分）を毎分
３．４８リットル（標準状態）の流量で流して（各浄化
材の見かけ空間速度はそれぞれ約８０，０００ｈ-1、８
０，０００ｈ-1、１００，０００ｈ-1である）、反応管
内の排ガス温度を３５０〜５５０℃の範囲に保ち、エタ
ノールと窒素酸化物とを反応させた。A silver-based purifying material, a second silver-based purifying material, and a platinum-based purifying material were set in order from the inflow side to the outflow side of the exhaust gas in the reaction tube. Next, a gas (nitrogen monoxide, oxygen, ethanol, sulfur dioxide, nitrogen and moisture) having a composition shown in Table 1 was flowed at a flow rate of 3.48 liters per minute (standard state) (apparent space velocity of each purification material). Are about 80,000 h -1 and 8 respectively.
0,000h -1, is 100,000 h -1), the exhaust gas temperature in the reaction tube maintained at a range of 350 to 550 ° C., to react the ethanol and nitrogen oxides.

【００５３】反応管通過後のガスの窒素酸化物の濃度を
化学発光式窒素酸化物分析計により測定し、窒素酸化物
除去率を求めた。結果を表２に示す。The concentration of nitrogen oxides in the gas after passing through the reaction tube was measured with a chemiluminescent nitrogen oxide analyzer to determine the nitrogen oxide removal rate. Table 2 shows the results.

【００５４】 表１ 成分 濃度 一酸化窒素 800 ppm 酸素 10 容量％ エタノール 1560 ppm 二酸化硫黄 30 ppm 窒素 残部 水分 10 容量％（上記成分の総体積に対して）Table 1 Component concentration Nitric oxide 800 ppm Oxygen 10% by volume Ethanol 1560 ppm Sulfur dioxide 30 ppm Nitrogen Residual water 10% by volume (based on the total volume of the above components)

【００５５】実施例２ 実施例１と同じように硝酸銀水溶液を用いて、市販のシ
リカ・アルミナ粉末（シリカ含有量５重量％、比表面積
３５０ｍ2 ／ｇ）に３重量％（金属元素換算値）の銀を
担持して第一の触媒を調製した。第一の触媒０．２６ｇ
を、市販のコージェライト製ハニカム状成形体（直径２
０ｍｍ、長さ８．３ｍｍ、４００セル／インチ2 ）にコ
ートし、乾燥後６００℃まで段階的に焼成し、銀系浄化
材（第一の触媒をコートした浄化材）を調製した。 Example 2 In the same manner as in Example 1, 3% by weight (in terms of metal element) of a commercially available silica-alumina powder (silica content: 5% by weight, specific surface area: 350 m 2 / g) using an aqueous silver nitrate solution. To prepare a first catalyst. 0.26 g of the first catalyst
Is a commercially available cordierite honeycomb molded body (diameter 2
0 mm, length 8.3 mm, 400 cells / inch 2 ), dried and baked stepwise to 600 ° C. to prepare a silver-based purifying material (a purifying material coated with a first catalyst).

【００５６】上記銀系触媒と同じ方法で、粉末状シリカ
・アルミナに５重量％（金属元素換算値）の銀を担持し
た第二の触媒を調製し、上記と同様なハニカム状成形体
に第二の触媒０．２６ｇをコートし、同じ方法で第二の
銀系浄化材（第二の触媒をコートした浄化材）を調製し
た。In the same manner as in the above-mentioned silver-based catalyst, a second catalyst in which 5% by weight (in terms of a metal element) of silver was supported on powdered silica / alumina was prepared, and a honeycomb-shaped formed body similar to the above was prepared. 0.26 g of the second catalyst was coated, and a second silver-based purifying material (a purifying material coated with the second catalyst) was prepared in the same manner.

【００５７】次に、実施例１と同様に塩化白金酸水溶液
を用いて、粉末状チタニア（比表面積３５ｍ2 ／ｇ）に
Ptを０．１重量％（金属元素換算値）担持して第三の触
媒を調製した。上記銀系浄化材と同様なハニカム成形体
（直径２０ｍｍ、長さ６．６ｍｍ、４００セル／インチ
2 ）に０．２１ｇのスラリー化した第三の触媒をコート
し、銀系浄化材と同じ条件で乾燥、焼成を行い、白金系
浄化材（第三の触媒をコートした浄化材）を調製した。Next, powdered titania (specific surface area: 35 m 2 / g) was prepared using an aqueous chloroplatinic acid solution in the same manner as in Example 1.
A third catalyst was prepared by supporting 0.1% by weight of Pt (in terms of metal element). A honeycomb formed body similar to the above-mentioned silver-based purifying material (diameter 20 mm, length 6.6 mm, 400 cells / inch)
2 ) was coated with 0.23 g of a third catalyst which was made into a slurry, dried and fired under the same conditions as the silver-based purifying material to prepare a platinum-based purifying material (a purifying material coated with a third catalyst). .

【００５８】反応管内の排ガスの流入側から流出側へ順
に銀系浄化材、第二の銀系浄化材、白金系浄化材をセッ
トした。実施例１と同様の反応条件（各浄化材の見かけ
空間速度はそれぞれ約８０，０００ｈ-1、８０，０００
ｈ-1、１００，０００ｈ-1である）で、表１に示す組成
のガスを用いて評価を行った。結果を表２に示す。A silver-based purifying material, a second silver-based purifying material, and a platinum-based purifying material were sequentially set from the inflow side to the outflow side of the exhaust gas in the reaction tube. The same reaction conditions as in Example 1 (the apparent space velocities of the respective purification materials were about 80,000 h -1 and 80,000, respectively).
h -1, with 100,000 h -1 in a), was evaluated using the composition of the gas shown in Table 1. Table 2 shows the results.

【００５９】実施例３ 実施例１の第二の銀触媒と第三の触媒の重量比が５０：
１になるように第二の銀触媒と第三の触媒を混合してス
ラリー化した後、実施例１の銀系浄化材と同様なハニカ
ム成形体に０．２６ｇの混合触媒をコートし。実施例１
の銀系浄化材と同じ条件で乾燥、焼成を行い、銀、白金
系浄化材（第二、第三の触媒をコートした浄化材）を調
製した。 Example 3 The weight ratio of the second silver catalyst to the third catalyst in Example 1 was 50:
After mixing the second silver catalyst and the third catalyst so as to obtain a slurry and forming a slurry, the same honeycomb formed body as the silver-based purifying material of Example 1 was coated with 0.26 g of the mixed catalyst. Example 1
Drying and baking were carried out under the same conditions as those of the silver-based purifying material to prepare silver and platinum-based purifying materials (purifying materials coated with the second and third catalysts).

【００６０】反応管内の排ガスの流入側から流出側へ順
に実施例１の銀系浄化材、上記銀、白金系浄化材をセッ
トした。実施例１と同様の反応条件（各浄化材の見かけ
空間速度はそれぞれ約８０，０００ｈ-1である）で、表
１に示す組成のガスを用いて評価を行った。結果を表２
に示す。The silver-based purifying material of Example 1 and the silver and platinum-based purifying materials were set in order from the inflow side to the outflow side of the exhaust gas in the reaction tube. Evaluation was performed using the gas having the composition shown in Table 1 under the same reaction conditions as in Example 1 (the apparent space velocity of each purification material was about 80,000 h -1 ). Table 2 shows the results
Shown in

【００６１】実施例４ 実施例２の第二の銀触媒と第三の触媒の重量比が５０：
１になるように第二の銀触媒と第三の触媒を混合してス
ラリー化した後、実施例１の銀系浄化材と同様なハニカ
ム成形体に０．２６ｇの混合触媒をコートし。実施例１
の銀系浄化材と同じ条件で乾燥、焼成を行い、銀、白金
系浄化材（第二、第三の触媒をコートした浄化材）を調
製した。 Example 4 The weight ratio of the second silver catalyst to the third catalyst of Example 2 was 50:
After mixing the second silver catalyst and the third catalyst so as to obtain a slurry and forming a slurry, the same honeycomb formed body as the silver-based purifying material of Example 1 was coated with 0.26 g of the mixed catalyst. Example 1
Drying and baking were carried out under the same conditions as those of the silver-based purifying material to prepare silver and platinum-based purifying materials (purifying materials coated with the second and third catalysts).

【００６２】反応管内の排ガスの流入側から流出側へ順
に実施例２の銀系浄化材、上記銀、白金系浄化材をセッ
トした。実施例１と同様の反応条件（各浄化材の見かけ
空間速度はそれぞれ約８０，０００ｈ-1である）で、表
１に示す組成のガスを用いて評価を行った。結果を表２
に示す。The silver-based purifying material of Example 2 and the silver and platinum-based purifying materials were set in this order from the inflow side to the outflow side of the exhaust gas in the reaction tube. Evaluation was performed using the gas having the composition shown in Table 1 under the same reaction conditions as in Example 1 (the apparent space velocity of each purification material was about 80,000 h -1 ). Table 2 shows the results
Shown in

【００６３】実施例５ 実施例１の銀系浄化材と第二の銀系浄化材を用い、反応
管内の排ガスの流入側に実施例１の銀系浄化材、流出側
に実施例１の第二の銀系浄化材をセットした。実施例１
と同様の反応条件（各浄化材の見かけ空間速度はそれぞ
れ約８０，０００ｈ-1である）で、表１に示す組成のガ
スを用いて評価を行った。結果を表２に示す。 Example 5 The silver-based purifying material of Example 1 and the second silver-based purifying material were used, and the silver-based purifying material of Example 1 was provided on the inflow side of the exhaust gas in the reaction tube, and the silver-based purifying material of Example 1 was provided on the outflow side. A second silver purifying material was set. Example 1
Evaluation was carried out under the same reaction conditions as described above (the apparent space velocity of each purifying material was about 80,000 h -1 ) using a gas having a composition shown in Table 1. Table 2 shows the results.

【００６４】比較例１ 実施例１で調製した第一の触媒０．５２ｇを同様のハニ
カム成形体（直径２０ｍｍ、長さ１６．６ｍｍ）にコー
トして、乾燥、焼成を行い、銀系浄化材を調製した。銀
系浄化材を排ガスの導管にセットし、実施例１と同様の
反応条件（見かけ空間速度は約４０，０００ｈ-1であ
る）で、表１に示す組成のガスを用いて評価を行った。
結果を表２に示す。 Comparative Example 1 The same honeycomb formed body (20 mm in diameter and 16.6 mm in length) was coated with 0.52 g of the first catalyst prepared in Example 1, dried and calcined to obtain a silver-based purifying material. Was prepared. The silver-based purifying material was set in an exhaust gas conduit, and evaluated using the gas having the composition shown in Table 1 under the same reaction conditions as in Example 1 (the apparent space velocity was about 40,000 h -1 ). .
Table 2 shows the results.

【００６５】比較例２ 実施例１で調製した第二の触媒０．５２ｇを同様のハニ
カム成形体（直径２０ｍｍ、長さ１６．６ｍｍ）にコー
トして、乾燥、焼成を行い、銀系浄化材を調製した。銀
系浄化材を排ガスの導管にセットし、実施例１と同様の
反応条件（見かけ空間速度は約４０，０００ｈ-1であ
る）で、表１に示す組成のガスを用いて評価を行った。
結果を表２に示す。 Comparative Example 2 The same honeycomb formed body (20 mm in diameter and 16.6 mm in length) was coated with 0.52 g of the second catalyst prepared in Example 1, dried and calcined to obtain a silver-based purifying material. Was prepared. The silver-based purifying material was set in an exhaust gas conduit, and evaluated using the gas having the composition shown in Table 1 under the same reaction conditions as in Example 1 (the apparent space velocity was about 40,000 h -1 ). .
Table 2 shows the results.

【００６６】 表２ 窒素酸化物（ＮＯｘ）の除去率 窒素酸化物の除去率（％） 反応温度（℃） ３００ ３５０ ４００ ４５０ ５００ 実施例１ 50.5 78.5 94.7 95.6 89.6 実施例２ 48.4 77.5 92.3 94.5 89.6 実施例３ 53.5 77.5 92.7 93.6 86.6 実施例４ 49.4 76.5 90.3 92.5 86.6 実施例５ 47.2 76.8 92.5 96.5 90.2 比較例１ 24.6 45.7 68.9 82.2 78.8 比較例２ 34.3 54.7 67.4 72.5 54.5Table 2 Removal rate of nitrogen oxides (NOx) Removal rate of nitrogen oxides (%) Reaction temperature (° C.) 300 350 400 450 500 Example 1 50.5 78.5 94.7 95.6 89.6 Example 2 48.4 77.5 92.3 94.5 89.6 Example 2 Example 3 53.5 77.5 92.7 93.6 86.6 Example 4 49.4 76.5 90.3 92.5 86.6 Example 5 47.2 76.8 92.5 96.5 90.2 Comparative Example 1 24.6 45.7 68.9 82.2 78.8 Comparative Example 2 34.3 54.7 67.4 72.5 54.5

【００６７】表２からわかるように、単一担持量の銀触
媒だけを用いた比較例１及び２に比べて、実施例１〜５
では広い排ガス温度領域で窒素酸化物の良好な除去がみ
られた。As can be seen from Table 2, Examples 1 to 5 were compared with Comparative Examples 1 and 2 using only a single supported amount of silver catalyst.
Showed good removal of nitrogen oxides over a wide exhaust gas temperature range.

【００６８】[0068]

【発明の効果】以上詳述したように、本発明の排ガス浄
化材を用いれば、広い温度領域において過剰の酸素を含
む排ガス中の窒素酸化物を効率良く除去することができ
る。本発明の排ガス浄化材及び浄化方法は、各種燃焼
機、自動車等の排ガス浄化に広く利用することができ
る。As described above in detail, the use of the exhaust gas purifying material of the present invention makes it possible to efficiently remove nitrogen oxides in exhaust gas containing excess oxygen in a wide temperature range. INDUSTRIAL APPLICABILITY The exhaust gas purifying material and the purification method of the present invention can be widely used for purifying exhaust gas of various types of combustors, automobiles and the like.

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｂ０１Ｊ 23/42 ＺＡＢ Ａ 23/50 ＺＡＢ Ａ Ｆ０１Ｎ 3/28 ＺＡＢ ３０１ Ｇ Ｂ０１Ｄ 53/36 １０２ Ａ １０２ Ｂ １０２ Ｈ ──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. 6 Identification code Agency reference number FI Technical display location B01J 23/42 ZAB A 23/50 ZAB A F01N 3/28 ZAB 301 G B01D 53/36 102 A 102 B 102 H

Claims (9)

【特許請求の範囲】[Claims] 【請求項１】 窒素酸化物と、共存する未燃焼成分に対
する理論反応量より多い酸素とを含む燃焼排ガスから窒
素酸化物を還元除去する排ガス浄化材において、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．２〜１２重量％（銀元素換算値）
を担持してなる第一の触媒と、多孔質の無機酸化物に活
性種として銀及び／又は銀化合物、又はそれらの混合物
０．５〜１５重量％（銀元素換算値）かつ前記第一の触
媒の活性種の担持率より多い量を担持してなる第二の触
媒とからなり、浄化材の排ガス流入側から流出側へ順に
前記第一の触媒、前記第二の触媒を有することを特徴と
する排ガス浄化材。1. An exhaust gas purifying material for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen in excess of the theoretical reaction amount of coexisting unburned components, wherein the porous inorganic oxides are used as active species. 0.2 to 12% by weight of silver and / or a silver compound or a mixture thereof (in terms of silver element)
And a silver and / or silver compound as an active species in a porous inorganic oxide, or a mixture thereof in an amount of 0.5 to 15% by weight (in terms of silver element) and the first catalyst. The catalyst comprises a second catalyst that carries a larger amount than the loading rate of the active species of the catalyst, and includes the first catalyst and the second catalyst in order from the exhaust gas inflow side to the outflow side of the purification material. Exhaust gas purifying material. 【請求項２】 窒素酸化物と、共存する未燃焼成分に対
する理論反応量より多い酸素とを含む燃焼排ガスから窒
素酸化物を還元除去する排ガス浄化材において、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．２〜１２重量％（銀元素換算値）
を担持してなる第一の触媒と、多孔質の無機酸化物に活
性種として銀及び／又は銀化合物、又はそれらの混合物
０．５〜１５重量％（銀元素換算値）かつ前記第一の触
媒の活性種の担持率より多い量を担持してなる第二の触
媒と、多孔質の無機酸化物に活性種としてPt、Pd、Ru、
Rh、Ir及びAuからなる群より選ばれた少なくとも１種の
元素０．０１〜５重量％（金属元素換算値）を担持して
なる第三の触媒とからなり、浄化材の排ガス流入側から
流出側へ順に前記第一の触媒、前記第二の触媒、前記第
三触媒を有することを特徴とする排ガス浄化材。2. An exhaust gas purifying material for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen which is larger than a theoretical reaction amount of coexisting unburned components, wherein the porous inorganic oxides are used as active species. 0.2 to 12% by weight of silver and / or a silver compound or a mixture thereof (in terms of silver element)
And a silver and / or silver compound as an active species in a porous inorganic oxide, or a mixture thereof in an amount of 0.5 to 15% by weight (in terms of silver element) and the first catalyst. The second catalyst, which carries a larger amount than the loading of the active species of the catalyst, and Pt, Pd, Ru, as active species on the porous inorganic oxide.
A third catalyst supporting at least one element selected from the group consisting of Rh, Ir, and Au in an amount of 0.01 to 5% by weight (in terms of a metal element); An exhaust gas purifying material comprising: the first catalyst, the second catalyst, and the third catalyst in the order of an outflow side. 【請求項３】 窒素酸化物と、共存する未燃焼成分に対
する理論反応量より多い酸素とを含む燃焼排ガスから窒
素酸化物を還元除去する排ガス浄化材において、多孔質
の無機酸化物に活性種として銀及び／又は銀化合物、又
はそれらの混合物０．２〜１２重量％（銀元素換算値）
を担持してなる第一の触媒と、多孔質の無機酸化物に活
性種として銀及び／又は銀化合物、又はそれらの混合物
０．５〜１５重量％（銀元素換算値）かつ前記第一の触
媒の活性種の担持率より多い量を担持してなる第二の触
媒と、多孔質の無機酸化物に活性種としてPt、Pd、Ru、
Rh、Ir及びAuからなる群より選ばれた少なくとも１種の
元素０．０１〜５重量％（金属元素換算値）を担持して
なる第三の触媒とからなり、前記第二の触媒と前記第三
の触媒とが混合されており、浄化材の排ガス流入側から
流出側へ順に前記第一の触媒、前記第二の触媒、前記混
合触媒を有することを特徴とする排ガス浄化材。3. An exhaust gas purifying material for reducing and removing nitrogen oxides from a combustion exhaust gas containing nitrogen oxides and oxygen which is larger than a theoretical reaction amount of coexisting unburned components, wherein the porous inorganic oxides are used as active species. 0.2 to 12% by weight of silver and / or a silver compound or a mixture thereof (in terms of silver element)
And a silver and / or silver compound as an active species in a porous inorganic oxide, or a mixture thereof in an amount of 0.5 to 15% by weight (in terms of silver element) and the first catalyst. The second catalyst, which carries a larger amount than the loading of the active species of the catalyst, and Pt, Pd, Ru, as active species on the porous inorganic oxide.
A third catalyst supporting at least one element selected from the group consisting of Rh, Ir, and Au in an amount of 0.01 to 5% by weight (in terms of a metal element); An exhaust gas purifying material, wherein the first catalyst, the second catalyst, and the mixed catalyst are mixed with a third catalyst in order from the exhaust gas inflow side to the outflow side of the purifying material. 【請求項４】 請求項３に記載の排ガス浄化材におい
て、前記第二の触媒と第三の触媒の重量比は２：１〜２
００：１であることを特徴とする排ガス浄化材。4. The exhaust gas purifying material according to claim 3, wherein the weight ratio of the second catalyst to the third catalyst is 2: 1 to 2
An exhaust gas purifying material having a ratio of 00: 1. 【請求項５】 請求項１〜４のいずれかに記載の排ガス
浄化材において、前記第一、第二及び第三の触媒の内の
一つ以上がセラッミクス製又は金属製の基体の表面にコ
ートされたものであることを特徴とする排ガス浄化材。5. The exhaust gas purifying material according to claim 1, wherein at least one of the first, second and third catalysts is coated on the surface of a ceramic or metal substrate. An exhaust gas purifying material characterized in that it has been manufactured. 【請求項６】 請求項１〜４のいずれかに記載の排ガス
浄化材において、前記第一、第二及び第三の触媒の内の
一つ以上がペレット状又は顆粒状であることを特徴とす
る排ガス浄化材。6. The exhaust gas purifying material according to claim 1, wherein at least one of the first, second and third catalysts is in the form of pellets or granules. Exhaust gas purifying material. 【請求項７】 請求項１〜６のいずれかに記載の排ガス
浄化材において、前記銀化合物は銀の酸化物、ハロゲン
化銀、硫酸銀及び燐酸銀からなる群より選ばれた少なく
とも一種であることを特徴とする排ガス浄化材。7. The exhaust gas purifying material according to claim 1, wherein the silver compound is at least one selected from the group consisting of silver oxide, silver halide, silver sulfate, and silver phosphate. An exhaust gas purifying material characterized by that: 【請求項８】 請求項１〜７のいずれかに記載の排ガス
浄化材において、前記多孔質無機酸化物が、第一及び第
二の触媒ではアルミナ単独、アルミナを含む複合酸化物
又はアルミナを含む混合酸化物のいずれかであり、第三
の触媒ではアルミナ、チタニア、ジルコニア、シリカ、
ゼオライトからなる群より選ばれた一種以上の酸化物で
あることを特徴とする排ガス浄化材。8. The exhaust gas purifying material according to claim 1, wherein the porous inorganic oxide contains alumina alone, a composite oxide containing alumina or alumina in the first and second catalysts. A mixed oxide, the third catalyst is alumina, titania, zirconia, silica,
An exhaust gas purifying material comprising at least one oxide selected from the group consisting of zeolites. 【請求項９】 請求項１〜８のいずれかに記載の排ガス
浄化材を用い、窒素酸化物と、共存する未燃焼成分に対
する理論反応量より多い酸素とを含む燃焼排ガスから窒
素酸化物を還元除去する排ガス浄化方法において、前記
排ガス浄化材を排ガス導管の途中に設置し、前記浄化材
の上流側で炭化水素及び／又は含酸素有機化合物を添加
した排ガスを、１５０〜６５０℃において前記浄化材に
接触させ、もって前記排ガス中の炭化水素及び／又は含
酸素有機化合物との反応により前記窒素酸化物を除去す
ることを特徴とする排ガス浄化方法。9. An exhaust gas purifying material according to claim 1, wherein nitrogen oxide is reduced from a combustion exhaust gas containing nitrogen oxide and oxygen in an amount larger than a theoretical reaction amount for a coexisting unburned component. In the exhaust gas purifying method for removing, the exhaust gas purifying material is provided in the middle of an exhaust gas conduit, and the exhaust gas to which a hydrocarbon and / or an oxygen-containing organic compound is added at an upstream side of the purifying material is subjected to the purifying material at 150 to 650 ° C. Exhaust gas purifying method, wherein the nitrogen oxides are removed by contact with a hydrocarbon and / or an oxygen-containing organic compound in the exhaust gas.
JP6317582A 1994-11-28 1994-11-28 Exhaust gas purification material and purifying method for exhaust gas Pending JPH08141371A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP6317582A JPH08141371A (en) 1994-11-28 1994-11-28 Exhaust gas purification material and purifying method for exhaust gas
US08/466,988 US5714130A (en) 1994-11-28 1995-06-06 Exhaust gas cleaner and method for cleaning exhaust gas
EP95308495A EP0714693A1 (en) 1994-11-28 1995-11-27 Exhaust gas cleaner and method for cleaning exhaust gas

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP6317582A JPH08141371A (en) 1994-11-28 1994-11-28 Exhaust gas purification material and purifying method for exhaust gas

Publications (1)

Publication Number Publication Date
JPH08141371A true JPH08141371A (en) 1996-06-04

Family

ID=18089850

Family Applications (1)

Application Number Title Priority Date Filing Date
JP6317582A Pending JPH08141371A (en) 1994-11-28 1994-11-28 Exhaust gas purification material and purifying method for exhaust gas

Country Status (1)

Country Link
JP (1) JPH08141371A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4838997B2 (en) * 2002-11-27 2011-12-14 ボルボ テクノロジー コーポレイション Catalyst unit for the reduction of Nox compounds
JP2018176079A (en) * 2017-04-14 2018-11-15 三菱日立パワーシステムズ株式会社 Combustion exhaust gas treatment method, combustion exhaust gas treatment device and maintenance method of the same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4838997B2 (en) * 2002-11-27 2011-12-14 ボルボ テクノロジー コーポレイション Catalyst unit for the reduction of Nox compounds
JP2018176079A (en) * 2017-04-14 2018-11-15 三菱日立パワーシステムズ株式会社 Combustion exhaust gas treatment method, combustion exhaust gas treatment device and maintenance method of the same

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