JP2000042415A - Catalyst for exhaust gas purification using hydrocarbon reforming material - Google Patents
Catalyst for exhaust gas purification using hydrocarbon reforming materialInfo
- Publication number
- JP2000042415A JP2000042415A JP10220067A JP22006798A JP2000042415A JP 2000042415 A JP2000042415 A JP 2000042415A JP 10220067 A JP10220067 A JP 10220067A JP 22006798 A JP22006798 A JP 22006798A JP 2000042415 A JP2000042415 A JP 2000042415A
- Authority
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- Japan
- Prior art keywords
- catalyst
- phosphate
- exhaust gas
- catalyst layer
- honeycomb
- 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.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、炭化水素ガスの改
質材を用いた排気ガス浄化用触媒に係り、更に詳細に
は、内燃機関や燃焼器等からの排気ガス中の炭化水素類
を窒素酸化物の還元に適するように改質する炭化水素改
質材を用いた排気ガス浄化用触媒に関するものであり、
特に酸素含有量の多いリーン排気ガス中の窒素酸化物を
高効率で浄化するのに好適に利用される。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying catalyst using a hydrocarbon gas reforming material, and more particularly, to a method for removing hydrocarbons in exhaust gas from an internal combustion engine or a combustor. The present invention relates to an exhaust gas purifying catalyst using a hydrocarbon reforming material that reforms to be suitable for reduction of nitrogen oxides,
In particular, it is suitably used for efficiently purifying nitrogen oxides in lean exhaust gas having a high oxygen content.
【０００２】[0002]
【従来の技術】従来の自動車エンジン排気ガスのように
酸化成分と還元成分がほぼ等しく含まれる排気ガスを浄
化するための触媒としては、三元触媒が広く用いられて
いる。この三元触媒は、白金（Ｐｔ）、パラジウム（Ｐ
ｄ）及びロジウム（Ｒｈ）等の貴金属成分並びにセリア
（Ｃｅ）成分をはじめとする各種成分を担持した活性ア
ルミナを主成分とする触媒であり、排気ガス中の有害成
分である炭化水素（ＨＣ）、一酸化炭素（ＣＯ）及び窒
素酸化物（ＮＯｘ）を高効率で浄化することができる。2. Description of the Related Art A three-way catalyst is widely used as a catalyst for purifying an exhaust gas containing an oxidizing component and a reducing component substantially equally, such as a conventional automobile engine exhaust gas. This three-way catalyst comprises platinum (Pt), palladium (P
d) and a catalyst mainly composed of activated alumina carrying various components including a noble metal component such as rhodium (Rh) and ceria (Ce), and hydrocarbon (HC) which is a harmful component in exhaust gas. , Carbon monoxide (CO) and nitrogen oxides (NOx) can be purified with high efficiency.
【０００３】一方、近年は、燃費向上及び二酸化炭素排
出量の削減の観点から、理論空燃比より高い空燃比でも
運転するリーンバーンエンジンが普及してきている。こ
のリーンバーンエンジンの排気ガス（以下、「リーン排
ガス」という）は、理論空燃比近傍で運転する従来のエ
ンジンの排気ガス（以下、「ストイキ排ガス」という）
に比較して、酸素含有率が高く、上記三元触媒ではＮＯ
ｘの浄化が不十分となる。かかる状況から、リーン排ガ
ス中のＮＯｘを高効率で浄化できる新触媒が望まれてお
り、各種のＮＯｘ還元触媒の開発が試みられている。On the other hand, in recent years, from the viewpoint of improving fuel efficiency and reducing carbon dioxide emission, lean burn engines that operate even at an air-fuel ratio higher than the stoichiometric air-fuel ratio have become widespread. The exhaust gas of this lean burn engine (hereinafter, referred to as "lean exhaust gas") is the exhaust gas of a conventional engine operating near the stoichiometric air-fuel ratio (hereinafter, referred to as "stoichiometric exhaust gas").
And the three-way catalyst has a higher oxygen content than NO.
x is insufficiently purified. Under such circumstances, a new catalyst capable of purifying NOx in lean exhaust gas with high efficiency has been desired, and development of various NOx reduction catalysts has been attempted.
【０００４】このような要望に応じて、各種の金属成分
をＹ型、Ｌ型、モルデナイト、ＭＦＩゼオライト等のゼ
オライトに担持したゼオライト系触媒が提案されてお
り、このゼオライト系触媒は、リーン排ガス中におい
て、ＨＣの共存下でＮＯｘを比較的効率良く浄化できる
能力を有していることが知られている。また、担持する
金属成分としては、銅（Ｃｕ）、コバルト（Ｃｏ）、銀
（Ａｇ）、ニッケル（Ｎｉ）及び鉄（Ｆｅ）等の遷移金
属成分が有効であり、貴金属成分では白金も有効である
ことが認められているが、中でも銅を担持したＣｕ−ゼ
オライト系触媒は、高流速ガス条件下でも比較的優れた
ＮＯｘ浄化能を示し、自動車のような小型移動発生源や
定置型の自家発電用エンジン等の排気ガス浄化への適用
に期待が掛けられている。In response to such demands, zeolite catalysts have been proposed in which various metal components are supported on zeolites such as Y-type, L-type, mordenite, and MFI zeolite. Is known to have the ability to purify NOx relatively efficiently in the presence of HC. Further, as the metal component to be supported, transition metal components such as copper (Cu), cobalt (Co), silver (Ag), nickel (Ni), and iron (Fe) are effective, and platinum is also effective as a noble metal component. Among them, the Cu-zeolite catalyst supporting copper exhibits relatively excellent NOx purification ability even under high flow rate gas conditions, and is suitable for small mobile sources such as automobiles and stationary self-contained catalysts. Expectations are being raised for application to exhaust gas purification of power generation engines and the like.
【０００５】しかし、上記金属成分を担持したゼオライ
ト系触媒には、次の問題点があるため、リーン条件で運
転される自動車排気ガス浄化用触媒としては実用化に至
っていない。まず、ＮＯｘを比較的効率良く浄化できる
温度範囲が狭く、特に１５０〜３００℃の比較的低い温
度領域では、十分なＮＯｘ浄化能力が得られない。ま
た、排気ガス中に炭化水素が比較的少ない場合、特にＨ
Ｃ／ＮＯｘ比が５〜６以下となる条件では、ＮＯｘ浄化
能力が急激に低下する。更には、水蒸気を含む６００℃
以上の高温条件下（水熱条件下）では、極めて劣化が大
きいという根本的な問題点がある。However, the zeolite-based catalyst supporting the metal component has the following problems, and has not been put into practical use as a catalyst for purifying automobile exhaust gas operated under lean conditions. First, the temperature range in which NOx can be purified relatively efficiently is narrow, and particularly in a relatively low temperature range of 150 to 300 ° C, sufficient NOx purification performance cannot be obtained. Also, when hydrocarbons are relatively low in the exhaust gas,
Under the condition that the C / NOx ratio is 5 to 6 or less, the NOx purification ability sharply decreases. Furthermore, 600 ° C containing steam
Under the above high temperature condition (hydrothermal condition), there is a fundamental problem that the deterioration is extremely large.
【０００６】これに対し、上述のような低温領域でのＮ
Ｏｘ浄化能力の向上については、例えば、Ｃｕ−ゼオラ
イト系触媒層の下層に貴金属触媒層を設け、この貴金属
触媒層での反応熱を利用することによって、上層のＣｕ
−ゼオライト系触媒をより低温から作動させることが既
に提案されている（特開平１−１２７０４４号公報及び
特開平５−６８８８８号公報）。しかし、この場合は、
下層の貴金属触媒層における酸化反応熱のために劣化が
大きくなったり、更には、貴金属触媒層の強い酸化活性
のためにＨＣ類が優先的に酸化消費されてしまうので、
ＮＯｘ還元浄化率の低下を招くことが懸念される。な
お、この影響は、Ｃｕ−ゼオライト系触媒層と貴金属成
分を共存させる場合（特開平１−３１０７４号公報、特
開平５−１６８９３９号公報）には特に大きくなること
が予想される。On the other hand, N in a low temperature region as described above
Regarding the improvement of the Ox purification ability, for example, a noble metal catalyst layer is provided below the Cu-zeolite catalyst layer, and the heat of reaction in the noble metal catalyst layer is used to form an upper Cu layer.
It has already been proposed to operate a zeolite-based catalyst at a lower temperature (Japanese Patent Application Laid-Open Nos. 1-127044 and 5-68888). But in this case,
The deterioration is increased due to the heat of oxidation reaction in the lower noble metal catalyst layer, and furthermore, HCs are preferentially oxidized and consumed due to the strong oxidation activity of the noble metal catalyst layer.
It is feared that the NOx reduction purification rate is reduced. This effect is expected to be particularly large when the Cu-zeolite-based catalyst layer and the noble metal component coexist (JP-A-1-31074 and JP-A-5-168939).
【０００７】また、Ｐｔ系触媒を用いれば、２００〜２
５０℃の比較的低温域でもＮＯｘを転化できるが、Ｎ2
への転化のみではなく、Ｎ2Ｏへも転化するため、Ｎ2Ｏ
の生成も無視できない。更には、活性温度域が狭く、３
００℃以上の温度域では高いＮＯｘ還元率が得にくいと
いう問題点がある。このように、Ｃｕ−ゼオライト系触
媒、Ｐｔ系触媒のいずれの触媒でも、低ＨＣ／ＮＯｘ比
の排ガス条件では、ＮＯｘ浄化能が不十分となってい
た。When a Pt-based catalyst is used, 200 to 2
NOx can be converted even in a relatively low temperature range of 50 ° C.
Not only conversion to N2O but also N2O
Cannot be ignored. Furthermore, the activation temperature range is narrow and 3
There is a problem that it is difficult to obtain a high NOx reduction rate in a temperature range of 00 ° C. or higher. As described above, in any of the Cu-zeolite-based catalyst and the Pt-based catalyst, the NOx purification ability was insufficient under the exhaust gas condition with a low HC / NOx ratio.
【０００８】そこで、更に、還元剤となるＨＣ類やアル
コール類等を触媒入ロに二次的に供給する浄化方法も提
案されている。この場合、還元剤を充填したタンクを車
載する方法、燃料を還元剤に直接利用する方法等が提案
されているが、前者の場合にはタンクの搭載場所や重量
増の間題点、後者の場合にはエンジンの燃費が犠牲にな
るという問題点が生ずる。Therefore, a purification method has also been proposed in which HCs, alcohols, and the like serving as reducing agents are secondarily supplied to a catalyst inlet. In this case, a method of mounting a tank filled with a reducing agent on the vehicle, a method of directly using fuel as the reducing agent, and the like have been proposed. In this case, there is a problem that the fuel efficiency of the engine is sacrificed.
【０００９】[0009]
【発明が解決しようとする課題】上述のように、従来技
術では、実使用に際しリーン排ガスをあまり問題なく、
しかも効率良く浄化できる手法は確立されていないとい
う課題があった。本発明は、このような従来技術の有す
る課題に着目してなされたものであり、低ＨＣ／ＮＯｘ
比の排気条件の下でも、Ｎ2Ｏを殆ど生成することなく
高効率でＮＯｘ浄化でき、更には高温条件下での劣化が
少ない触媒を得ることができる炭化水素改質材を用いた
排気ガス浄化用触媒を提供することを目的としている。As described above, in the prior art, lean exhaust gas does not cause much problem in actual use.
Moreover, there has been a problem that a method for efficiently purifying has not been established. The present invention has been made in view of such problems of the prior art, and has a low HC / NOx.
Exhaust gas purification using a hydrocarbon reforming material that can purify NOx with high efficiency without generating any N2O even under specific exhaust conditions and can obtain a catalyst with less deterioration under high temperature conditions It is intended to provide a catalyst.
【００１０】[0010]
【課題を解決するための手段】本発明者らは、上記目的
を達成すべく鋭意検討を重ねた結果、所定のリン酸塩が
排気ガス中の炭化水素類の反応性を改善でき、また、か
かるリン酸塩系の炭化水素改質材を含む触媒層とロジウ
ムを含む触媒層とで適切な多層構造を形成することによ
り、上記目的が達成できることを見出し、本発明を完成
するに至った。Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a predetermined phosphate can improve the reactivity of hydrocarbons in exhaust gas, The present inventors have found that the above object can be achieved by forming an appropriate multilayer structure with the catalyst layer containing the phosphate-based hydrocarbon reforming material and the catalyst layer containing rhodium, and have completed the present invention.
【００１１】即ち、本発明の排気ガス浄化用触媒は、ハ
ニカム状モノリス型担体に触媒層を被覆して成る排気ガ
ス浄化用触媒において、上記ハニカム状モノリス型担体
上に、排気ガス中の炭化水素を部分的に酸化し得る炭化
水素改質材として、リン酸マグネシウム、リン酸銀、リ
ン酸ニッケル、リン酸銅、リン酸鉄、リン酸亜鉛、リン
酸スズ及びリン酸コバルトから成る群より選ばれた少な
くとも１種のリン酸塩を含む第１触媒層と、ロジウム成
分を含む第２触媒層とを順次積層して成ることを特徴と
する。That is, the exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst comprising a catalyst layer coated on a honeycomb monolithic carrier, wherein the hydrocarbon in the exhaust gas is provided on the honeycomb monolithic carrier. Selected from the group consisting of magnesium phosphate, silver phosphate, nickel phosphate, copper phosphate, iron phosphate, zinc phosphate, tin phosphate and cobalt phosphate as a hydrocarbon modifier capable of partially oxidizing The first catalyst layer containing at least one kind of phosphate and the second catalyst layer containing a rhodium component are sequentially laminated.
【００１２】また、本発明の排気ガス浄化用触媒の好適
形態は、上記第１触媒層及び第２触媒層のいずれか一方
又は双方が、それぞれ上記炭化水素改質材又はロジウム
及び両成分を比表面積が６０ｍ２／ｇ以上の耐火性無機
化合物に担持して成ることを特徴とする。Further, in a preferred embodiment of the exhaust gas purifying catalyst of the present invention, one or both of the first catalyst layer and the second catalyst layer are each a mixture of the hydrocarbon reforming material or rhodium and both components. It is characterized by being supported on a refractory inorganic compound having a surface area of 60 m2 / g or more.
【００１３】更に、本発明の排気ガス浄化用触媒の好適
形態は、上記耐火性無機化合物が、アルミニウム、ケイ
素、チタン、ジルコニウム及びマグネシウムから成る群
より選ばれた少なくとも１種の成分を含む酸化物である
ことを特徴とし、第１触媒層の場合には、上記耐火性無
機化合物として、モルデナイト、ＭＦＩゼオライト、β
ゼオライト及びＹ型ゼオライトから成る群より選ばれた
少なくとも１種のゼオライトを好適に用いることができ
る。Further, in a preferred embodiment of the exhaust gas purifying catalyst of the present invention, the refractory inorganic compound is an oxide containing at least one component selected from the group consisting of aluminum, silicon, titanium, zirconium and magnesium. In the case of the first catalyst layer, mordenite, MFI zeolite, β
At least one zeolite selected from the group consisting of zeolites and Y-type zeolites can be suitably used.
【００１４】更に、本発明の排気ガス浄化用触媒の他の
好適形態は、上記第２触媒層が、更にタングステンを含
有することを特徴とする。Further, another preferred embodiment of the exhaust gas purifying catalyst according to the present invention is characterized in that the second catalyst layer further contains tungsten.
【００１５】[0015]
【発明の実施の形態】以下、本発明の排気ガス浄化用触
媒について詳細に説明する。まず、本発明の触媒に用い
る炭化水素改質材は、上述の如く、リン酸マグネシウ
ム、リン酸銀、リン酸ニッケル、リン酸銅、リン酸鉄、
リン酸亜鉛、リン酸スズ又はリン酸コバルト及びこれら
の任意の混合物などのリン酸塩を含有し、排気ガス中の
炭化水素分子を部分的に酸化し、含酸素化合物を生成し
得る。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the exhaust gas purifying catalyst of the present invention will be described in detail. First, the hydrocarbon modifier used in the catalyst of the present invention is, as described above, magnesium phosphate, silver phosphate, nickel phosphate, copper phosphate, iron phosphate,
It contains phosphates such as zinc phosphate, tin phosphate or cobalt phosphate and any mixture thereof, and can partially oxidize hydrocarbon molecules in the exhaust gas to produce oxygenates.
【００１６】ここで、リン酸塩がＮＯｘ還元活性を有す
ること、更には特定のリン酸塩に貴金属成分を担持する
ことにより、その性能を改善できることが知られている
（木村、西ロ、石原、滝田、平成９年度触媒研究発表会
講演予稿集３Ａ０１）。しかし、水が共存したり酸素濃
度が高い場合には、活性が低く、実エンジン排ガスで十
分な性能が得られるかどうかは不明である。また、特定
のリン酸塩を担体とし、これに貴金属成分を担持するこ
とにより、耐熱性に優れた高性能触媒が得られるとする
提案もある（特開平６−５５０７５号公報）。同公報で
はディーゼルへの適用について言及しているものの、そ
の実施例にはストイキでの性能が示されているに過ぎ
ず、酸素濃度の高いリーン排ガスでの性能は全く不明で
ある。Here, it is known that the phosphate has NOx reduction activity, and that the performance can be improved by supporting a noble metal component on a specific phosphate (Kimura, Nishiburo, Ishihara) , Takita, 1997 Catalyst Research Presentation Lectures 3A01). However, when water coexists or the oxygen concentration is high, the activity is low, and it is unknown whether sufficient performance can be obtained with actual engine exhaust gas. There is also a proposal that a high-performance catalyst excellent in heat resistance can be obtained by using a specific phosphate as a carrier and supporting a noble metal component on the carrier (Japanese Patent Laid-Open No. 6-55075). Although this publication mentions application to diesel, its examples only show performance at stoichiometry, and its performance at lean exhaust gas with a high oxygen concentration is completely unknown.
【００１７】上述の公知技術に対し、本発明におけるリ
ン酸塩の役割は、ＨＣ分子を部分的に酸化することによ
り、含酸素ＨＣ化合物を生成するものであり、排気ガス
浄化用触媒の見地からは、ＮＯｘの還元剤として利用さ
れ難いＨＣ種をより反応性の高いＨＣ種に変換（改質）
する作用を発揮するものである。従って、リン酸塩自体
にＮＯｘ還元性能を要求されることはなく、この点にお
いて上記公知技術と異なる。In contrast to the above-mentioned known techniques, the role of the phosphate in the present invention is to generate an oxygen-containing HC compound by partially oxidizing HC molecules, and from the viewpoint of an exhaust gas purifying catalyst. Converts HC species, which are difficult to use as NOx reducing agents, to more reactive HC species (reforming)
It exerts the action of doing. Therefore, the phosphate itself is not required to have NOx reduction performance, and this is different from the above-described known technology in this point.
【００１８】また、後述する本発明の排気ガス浄化触媒
との関係では、これらのリン酸塩系ＨＣ改質材は、Ｒｈ
触媒のＮＯｘ還元能を促進する機能を果たすが、特に低
ＨＣ／ＮＯｘ比条件の排気ガスを浄化すためには、ＨＣ
をＮＯｘの還元剤としてできるだけ有効に使用すること
が望ましい。上記リン酸塩系ＨＣ改質材は、このような
ＨＣの有効利用性に優れている。Further, in relation to the exhaust gas purifying catalyst of the present invention described later, these phosphate-based HC modifiers are Rh
The catalyst fulfills the function of promoting the NOx reduction ability of the catalyst. In particular, in order to purify exhaust gas under a low HC / NOx ratio condition, it is necessary to use HC
Is desirably used as effectively as a NOx reducing agent. The phosphate-based HC modifier is excellent in such effective use of HC.
【００１９】更に、Ｒｈ触媒のＮＯｘ還元能を促進する
機能を保証すべく、このＨＣ改質材の改質効果を発現す
る温度域と、Ｒｈ触媒のＮＯｘ還元活性温度域とを合致
させることが好ましく、具体的には、ＨＣ改質材の改質
効果の発現温度を３００〜５００℃とすることが好まし
い。Further, in order to ensure the function of promoting the NOx reduction ability of the Rh catalyst, the temperature range in which the reforming effect of the HC reforming material is exhibited and the NOx reduction activation temperature range of the Rh catalyst should be matched. Preferably, specifically, it is preferable that the temperature at which the reforming effect of the HC modifying material is exhibited is 300 to 500 ° C.
【００２０】更にまた、排気ガス浄化用触媒への使用に
際し、上記ＨＣ改質材は、貴金属成分と分離されて触媒
層を形成することになり、しかもこの触媒層は貴金属成
分を含有する触媒層の内側に配置される。よって、この
点においても、リン酸塩に貴金属を担持して混合使用す
る特開平６−５５０７５号公報に記載の技術と異なると
言える。Further, when used in an exhaust gas purifying catalyst, the HC reforming material is separated from the noble metal component to form a catalyst layer, and the catalyst layer is a catalyst layer containing a noble metal component. It is arranged inside. Therefore, also in this respect, it can be said that this is different from the technique described in JP-A-6-55075 in which a noble metal is supported on a phosphate and mixed and used.
【００２１】次に、本発明の排気ガス浄化用触媒につい
て詳細に説明する。上述の如く、本発明の排気ガス浄化
用触媒は、ハニカム状モノリス担体に触媒層を被覆した
多層構造を有するものであり、下層の第１触媒層に上記
ＨＣ改質材を用い、表層の第２触媒層にＲｈを用いたも
のである。Next, the exhaust gas purifying catalyst of the present invention will be described in detail. As described above, the exhaust gas purifying catalyst of the present invention has a multilayer structure in which a catalyst layer is coated on a honeycomb-shaped monolithic carrier. Two uses Rh for the catalyst layer.
【００２２】ここで、ハニカム状モノリス型担体は、主
として多層化のために使用され、本発明の排気ガス浄化
用触媒は、かかるハニカム状担体に各種触媒成分を被覆
して得られる。このハニカム状担体としては、一般にコ
ージェライト質のものが広く用いられているが、これに
限定されるものではなく、金属材料から成るハニカム担
体も有効に使用できる。なお、ハニカム状担体を用いる
ことなどによって触媒の全体形状をハニカム状とすれ
ば、触媒と排ガスとの接触面積を大きくでき、圧力損失
も抑えることができる。よって、使用時に振動があり、
且つ限られた空間内で多量の排ガスを処理することを要
求される自動車用触媒の場合、触媒形状をハニカム状と
することは極めて有利である。Here, the honeycomb-shaped monolith-type carrier is mainly used for multilayering, and the exhaust gas purifying catalyst of the present invention is obtained by coating the honeycomb-shaped carrier with various catalyst components. As this honeycomb-shaped carrier, cordierite-based one is generally widely used, but is not limited thereto, and a honeycomb carrier made of a metal material can also be used effectively. If the overall shape of the catalyst is made into a honeycomb shape by using a honeycomb-shaped carrier or the like, the contact area between the catalyst and the exhaust gas can be increased, and the pressure loss can be suppressed. Therefore, there is vibration during use,
In addition, in the case of an automobile catalyst which is required to process a large amount of exhaust gas in a limited space, it is extremely advantageous to make the catalyst shape a honeycomb shape.
【００２３】また、本発明の排気ガス浄化用触媒におい
て、下層にＨＣ改質材を含む触媒層を配置し、表層にＲ
ｈを含む触媒層を配置する理由は、低ＨＣ／ＮＯｘ比の
排気条件で、Ｎ2Ｏを殆ど生成することなく高効率でＮ
Ｏｘを浄化可能とし、更に高温条件下での劣化が少ない
触媒を実現するためである。この層配置を逆転すると、
改質したＨＣ類をＮＯｘ還元能を有するＲｈ触媒層に効
率よく供給できなくなるため、好ましくない。Further, in the exhaust gas purifying catalyst of the present invention, a catalyst layer containing an HC reforming material is disposed in a lower layer, and R
The reason for arranging the catalyst layer containing h is that under the exhaust conditions of a low HC / NOx ratio, N2
This is because a catalyst capable of purifying Ox and further reducing deterioration under high temperature conditions is realized. When this layer arrangement is reversed,
It is not preferable because the reformed HCs cannot be efficiently supplied to the Rh catalyst layer having NOx reduction ability.
【００２４】第１触媒層に含有させるＨＣ改質材は、上
述した所定のリン酸塩又はその混合物であるが、これら
のリン酸塩は、高表面積化により触媒活性を向上すべ
く、６０ｍ２／ｇ以上の比表面積を有する耐火性無機化
合物に担持して用いることが好ましい。この耐火性無機
化合物としては、アルミニウム（Ａｌ）、珪素（Ｓ
ｉ）、チタン（Ｔｉ）、ジルコニウム（Ｚｒ）又はマグ
ネシウム（Ｍｇ）及びこれらの任意の混合物の酸化物が
効果的である。具体的には、アルミナ（Ａｌ2Ｏ3）、シ
リカ（ＳｉＯ2）、チタニア（ＴｉＯ2）−シリカ、シリ
カ−アルミナ、アルミナ−ジルコニア（ＺｒＯ2）等の
酸化物が挙げられる。The HC modifier contained in the first catalyst layer is the above-mentioned predetermined phosphate or a mixture thereof. These phosphates are used in an amount of 60 m2 / s to improve the catalytic activity by increasing the surface area. It is preferable to use it by supporting it on a refractory inorganic compound having a specific surface area of at least g. The refractory inorganic compounds include aluminum (Al), silicon (S
Oxides of i), titanium (Ti), zirconium (Zr) or magnesium (Mg) and any mixtures thereof are effective. Specific examples include oxides such as alumina (Al2O3), silica (SiO2), titania (TiO2) -silica, silica-alumina, and alumina-zirconia (ZrO2).
【００２５】また、ケイ素とアルミニウムを構成元素と
するゼオライトは、高い比表面積及びミクロ細孔を有し
ており、ＨＣをトラップする機能も高いため、リン酸塩
の担体として好ましく用いることができる。かかるゼオ
ライトとしては、モルデナイト、ＭＦＩゼオライト、β
ゼオライト又はＹ型ゼオライト及びこれらの任意の混合
物を例示できる。Zeolite containing silicon and aluminum as constituent elements has a high specific surface area and micropores, and has a high HC trapping function, and therefore can be preferably used as a phosphate carrier. Such zeolites include mordenite, MFI zeolite, β
Examples include zeolites or Y-type zeolites and any mixtures thereof.
【００２６】上述のように、本発明の排気ガス浄化用触
媒においては、ＨＣ改質材たるリン酸塩の改質効果を有
効に引き出すべく、リン酸塩を高表面積の担体に担持す
ることが望ましく、また、表層のＲｈ触媒のＮＯｘ還元
特性との特性上の合致を図ることも重要である。即ち、
本発明の排気ガス浄化用触媒において、リン酸塩のＨＣ
改質効果を有効利用するには、表層の第２触媒層にＲｈ
が含有されていることを要し、例えば、第２触媒層に、
２００〜２５０℃の低温域でＮＯｘ還元活性を有するＰ
ｔ触媒を用いると、リン酸塩の改質効果発現温度域とＰ
ｔ触媒のＮＯｘ還元活性温度域とが合致しないため、リ
ン酸塩のＨＣ改質効果が得られず、所期のＮＯｘ浄化性
能が得られない。As described above, in the exhaust gas purifying catalyst of the present invention, the phosphate is supported on a carrier having a high surface area in order to effectively bring out the reforming effect of the phosphate as the HC reforming material. Desirably, it is also important to achieve a characteristic match with the NOx reduction characteristic of the Rh catalyst on the surface layer. That is,
In the exhaust gas purifying catalyst of the present invention, the phosphate HC
In order to effectively use the reforming effect, Rh should be added to the surface second catalyst layer.
Need to be contained, for example, in the second catalyst layer,
P having NOx reduction activity in the low temperature range of 200 to 250 ° C
When the t catalyst is used, the temperature range where the phosphate reforming effect is exhibited and P
Since the catalyst does not match the NOx reduction activation temperature range, the HC reforming effect of phosphate cannot be obtained, and the desired NOx purification performance cannot be obtained.
【００２７】一方、Ｒｈ成分を含む第２触媒層も、Ｒｈ
を６０ｍ２／ｇ以上の比表面積を有する耐火性無機化合
物に担持して形成することが好ましく、この無機化合物
としては、上述の第１触媒層の形成に用いられる無機化
合物と同様に、Ａｌ、Ｓｉ、Ｔｉ、Ｚｒ又はＭｇ及びこ
れらの任意の混合物の酸化物が効果的である。また、こ
の第２触媒層においては、更にタングステン（Ｗ）成分
を付加することにより、一層の性能向上が可能となる。
なお、Ｗ成分の効果の詳細は、現時点では必ずしも明か
ではないが、触媒のＮＯｘ及びＨＣの吸着特性を変化さ
せて、触媒表面での吸着バランスを最適化するものであ
り、これにより、ＮＯｘ還元反応を高効率で進行させる
ものと推測される。On the other hand, the second catalyst layer containing the Rh component also contains Rh.
Is preferably supported on a refractory inorganic compound having a specific surface area of 60 m 2 / g or more. As the inorganic compound, Al, Si may be used in the same manner as the inorganic compound used for forming the first catalyst layer. , Ti, Zr or Mg and oxides of any mixture thereof are effective. Further, by further adding a tungsten (W) component to the second catalyst layer, the performance can be further improved.
Although the details of the effect of the W component are not always clear at the present time, the effect of changing the adsorption characteristics of NOx and HC of the catalyst is to optimize the adsorption balance on the catalyst surface. It is assumed that the reaction proceeds with high efficiency.
【００２８】次に、本発明の排気ガス浄化用触媒の製造
方法の一例について説明する。本発明の排気ガス浄化用
触媒の製造に際し、各種リン酸塩の耐火性無機化合物へ
の担持には、該リン酸塩を水溶液として、含浸法などの
通常の担持方法を適用すればよいが、該水溶液に酸又は
塩基を添加してｐＨを適当に調節することにより、好ま
しい結果が得られることがある。また、硝酸塩とリン酸
をリン酸塩の出発物質として耐火性無機化合物に担持す
る等の方法も有効であるが、本発明は担持法によって制
限されるものではない。そして、常法に従ってＲｈを耐
火性無機化合物に担持し、このようにして得られた第１
触媒層及び第２触媒層の各触媒成分を、ハニカム状担体
に順次塗布して多層化することにより、本発明の排気ガ
ス浄化用触媒を得ることができる。Next, an example of the method for producing the exhaust gas purifying catalyst of the present invention will be described. In the production of the exhaust gas purifying catalyst of the present invention, for supporting various phosphates on the refractory inorganic compound, the phosphates may be used as an aqueous solution, and a normal supporting method such as an impregnation method may be applied. By adding an acid or base to the aqueous solution to adjust the pH appropriately, favorable results may be obtained. Further, a method of loading nitrate and phosphoric acid on a refractory inorganic compound as a starting material of phosphate is also effective, but the present invention is not limited by the loading method. Then, Rh is supported on the refractory inorganic compound according to a conventional method.
By sequentially applying each catalyst component of the catalyst layer and the second catalyst layer to the honeycomb-shaped carrier to form a multilayer, the exhaust gas purifying catalyst of the present invention can be obtained.
【００２９】以上のようにして得られる本発明のハニカ
ム状モノリス型の排気ガス浄化用触媒は、空燃比が１
４．７を超えるリーン条件で運転される内燃機関の排気
系に設置するのに好適であり、酸素濃度が５％以上で、
且つＮＯｘとＨＣが反応してＮＯｘをＮ2に転化するの
に必要なＨＣ量とＮＯｘ量との比率（＝ＨＣ／ＮＯｘ
比）が１０以下の条件、即ちディーゼルエンジン排ガス
のような条件下で、高いＮＯｘ浄化性能を実現すること
ができる。The honeycomb monolithic exhaust gas purifying catalyst of the present invention obtained as described above has an air-fuel ratio of 1
It is suitable to be installed in the exhaust system of an internal combustion engine operated under lean conditions exceeding 4.7 and has an oxygen concentration of 5% or more,
In addition, the ratio between the amount of HC and the amount of NOx necessary for converting NOx to N2 by reacting NOx and HC (= HC / NOx
Ratio) of 10 or less, that is, under conditions such as diesel engine exhaust gas, high NOx purification performance can be realized.
【００３０】[0030]
【実施例】以下、本発明を実施例及び比較例により更に
詳細に説明するが、本発明はこれら実施例に限定される
ものではない。EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
【００３１】（実施例１） （１）第１触媒層の形成 リン酸亜鉛を水に添加し攪拌して良く分散させた溶液
に、アンモニアを添加してｐＨを９．５に調節した。こ
の溶液に比表面積が約２８０ｍ２／ｇの活性Ａｌ2Ｏ3粉
末を添加し、十分に撹拌した後、１５０℃で２４時間乾
燥させ、電気炉を用いて５５０℃で４時間焼成し、リン
酸亜鉛／Ａｌ2Ｏ3触媒を得た。得られたリン酸亜鉛／Ａ
ｌ2Ｏ3触媒粉に水を加え、更に硝酸酸性のアルミナゾル
を添加した後、磁性ボールミルポットに入れ、約２０分
間混合・粉砕して活性Ａｌ2Ｏ3のスラリーを得た。この
際、アルミナゾルの添加量は４ｗｔ％とした。こうして
得られたスラリーを１平方インチ断面当たり約４００個
の流路を持つコージェライト質ハニカム担体１．０Ｌに
塗布し、次いで、１５０℃の熱風を通じて乾燥した後、
５００℃で１時間焼成してコート量約５０ｇ／Ｌのハニ
カム触媒担体（ａ）を得た。Example 1 (1) Formation of First Catalyst Layer Ammonia was added to a solution in which zinc phosphate was added to water and well dispersed by stirring to adjust the pH to 9.5. To this solution was added an activated Al2O3 powder having a specific surface area of about 280 m2 / g, and after sufficient stirring, dried at 150 ° C for 24 hours, calcined at 550 ° C for 4 hours using an electric furnace, and treated with zinc phosphate / Al2O3. A catalyst was obtained. The resulting zinc phosphate / A
Water was added to the l2O3 catalyst powder, and a nitric acid acidic alumina sol was further added. Then, the mixture was placed in a magnetic ball mill pot and mixed and pulverized for about 20 minutes to obtain a slurry of activated Al2O3. At this time, the addition amount of the alumina sol was 4 wt%. The slurry thus obtained was applied to 1.0 L of a cordierite-based honeycomb carrier having about 400 channels per square inch cross section, and then dried by hot air at 150 ° C.
The honeycomb catalyst carrier (a) having a coating amount of about 50 g / L was obtained by firing at 500 ° C. for 1 hour.
【００３２】（２）第２触媒層の形成 比表面積が約２８０ｍ２／ｇの活性Ａｌ2Ｏ3粉末にメタ
タングステン酸アンモニウムの水溶液を含浸し、１２０
℃で２４時間乾燥した後、６５０℃で４時間焼成し、タ
ングステン含有量が１０ｗｔ％のＷ／Ａｌ2Ｏ3を得た。
次いで、このＷ／Ａｌ2Ｏ3粉を硝酸Ｒｈ水溶液に浸し、
含浸法によってＲｈを担持した後、１２０℃で２４時間
乾燥し、６５０℃で４時間焼成して、Ｒｈが１．８ｗｔ
％担持されたＲｈ−Ｗ／Ａｌ2Ｏ3を得た。得られたこの
Ｒｈ−Ｗ／Ａｌ2Ｏ3触媒粉を、水及び硝酸酸性のアルミ
ナゾルとともに磁性ボールミルポットに入れ、約２０分
間混合・粉砕してスラリーを得た。アルミナゾルの添加
量は２ｗｔ％とした。このスラリーを上記第１触媒層が
担持されたハニカム触媒担体（ａ）に塗布し、次いで、
１５０℃の熱風を通じて乾燥した後、５００℃で１時間
焼成し、第２触媒のコート量が約１８０ｇ／Ｌである本
例の触媒（ハニカム触媒１）を得た。(2) Formation of Second Catalyst Layer An active Al 2 O 3 powder having a specific surface area of about 280 m 2 / g is impregnated with an aqueous solution of ammonium metatungstate,
After drying at 24 ° C. for 24 hours, it was baked at 650 ° C. for 4 hours to obtain W / Al 2 O 3 having a tungsten content of 10 wt%.
Next, this W / Al2O3 powder is immersed in an aqueous solution of Rh nitrate,
After supporting Rh by the impregnation method, it is dried at 120 ° C. for 24 hours, and calcined at 650 ° C. for 4 hours to obtain Rh of 1.8 wt.
% Supported Rh-W / Al2 O3 was obtained. The obtained Rh-W / Al2O3 catalyst powder was put into a magnetic ball mill pot together with water and nitric acid acidic alumina sol, and mixed and pulverized for about 20 minutes to obtain a slurry. The addition amount of alumina sol was 2 wt%. This slurry is applied to a honeycomb catalyst carrier (a) carrying the first catalyst layer, and then
After drying with hot air at 150 ° C., it was calcined at 500 ° C. for 1 hour to obtain a catalyst of this example (honeycomb catalyst 1) in which the coating amount of the second catalyst was about 180 g / L.
【００３３】（実施例２） （１）第１触媒層の形成 リン酸亜鉛をリン酸銅に代え、比表面積が約２８０ｍ２
の活性Ａｌ2Ｏ3粉末を比表面積が約２２０ｍ２／ｇのＳ
ｉＯ2−Ａｌ2Ｏ3粉末に代えた以外は、実施例１と同様
の操作を繰り返し、コート量約５０ｇ／Ｌのハニカム触
媒担体（ｂ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／ＳｉＯ2−Ａｌ2Ｏ
3触媒スラリーを用い、同様に上記第１触媒層が担持さ
れたハニカム触媒担体（ｂ）に塗布し、第２触媒のコー
ト量が約１８０ｇ／Ｌの本例の触媒（ハニカム触媒２）
を得た。Example 2 (1) Formation of First Catalyst Layer Zinc phosphate was replaced with copper phosphate, and the specific surface area was about 280 m 2.
Of activated Al2O3 powder of S having a specific surface area of about 220 m2 / g
The same operation as in Example 1 was repeated, except that the powder was replaced with iO2-Al2O3 powder, to obtain a honeycomb catalyst carrier (b) having a coating amount of about 50 g / L. (2) Formation of second catalyst layer Rh / SiO 2 —Al 2 O obtained in the same manner as in Example 1.
(3) The catalyst of the present example (honeycomb catalyst 2) having a coating amount of about 180 g / L using the catalyst slurry and similarly coated on the honeycomb catalyst carrier (b) on which the first catalyst layer is supported.
I got
【００３４】（実施例３） （１）第１触媒層の形成 リン酸亜鉛をリン酸銀に代え、比表面積が約２８０ｍ２
／ｇの活性Ａｌ2Ｏ3粉末を比表面積が約１９０ｍ２／ｇ
のＳｉＯ2−ＴｉＯ2粉末に代えた以外は、実施例１と同
様の操作を繰り返してコート量約５０ｇ／Ｌのハニカム
触媒担体（ｃ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／ＳｉＯ2−ＴｉＯ2
触媒スラリーを用い、同様に上記第１触媒層が担持され
たハニカム触媒担体（ｃ）に塗布し、第２触媒のコート
量が約１８０ｇ／Ｌの本例の触媒（ハニカム触媒３）を
得た。Example 3 (1) Formation of First Catalyst Layer Zinc phosphate was replaced with silver phosphate, and the specific surface area was about 280 m 2.
/ G of activated Al2O3 powder having a specific surface area of about 190 m2 / g
A honeycomb catalyst carrier (c) having a coating amount of about 50 g / L was obtained by repeating the same operation as in Example 1 except that the powder was replaced with the SiO 2 —TiO 2 powder. (2) Formation of second catalyst layer Rh / SiO 2 —TiO 2 obtained in the same manner as in Example 1.
The catalyst slurry was similarly applied to the honeycomb catalyst carrier (c) carrying the first catalyst layer to obtain a catalyst of the present example (honeycomb catalyst 3) having a coating amount of the second catalyst of about 180 g / L. .
【００３５】（実施例４） （１）第１触媒層の形成 リン酸亜鉛をリン酸ニッケルに代え、比表面積が約２８
０ｍ２／ｇの活性Ａｌ2Ｏ3粉末を比表面積が約１９０ｍ
２／ｇのＡｌ2Ｏ3−ＺｒＯ2粉末に代えた以外は、実施
例１と同様の操作を繰り返してコート量約５０ｇ／Ｌの
ハニカム触媒担体（ｄ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3−ＺｒＯ
2触媒スラリーを用い、同様に上記第１触媒層が担持さ
れたハニカム触媒担体（ｄ）に塗布し、第２触媒のコー
ト量が約１８０ｇ／Ｌの本例の触媒（ハニカム触媒４）
を得た。Example 4 (1) Formation of First Catalyst Layer Zinc phosphate was replaced with nickel phosphate, and the specific surface area was about 28.
0 m2 / g of activated Al2O3 powder having a specific surface area of about 190 m
A honeycomb catalyst carrier (d) having a coating amount of about 50 g / L was obtained by repeating the same operation as in Example 1 except that 2 / g of Al2O3-ZrO2 powder was used. (2) Formation of second catalyst layer Rh / Al2O3-ZrO obtained in the same manner as in Example 1.
(2) The catalyst of the present example (honeycomb catalyst 4), which was similarly applied to the honeycomb catalyst carrier (d) carrying the first catalyst layer using the catalyst slurry and the coating amount of the second catalyst was about 180 g / L.
I got
【００３６】（実施例５） （１）第１触媒層の形成 リン酸亜鉛をリン酸鉄に代え、比表面積が約２８０ｍ２
／ｇの活性Ａｌ2Ｏ3粉末を比表面積が約２３０ｍ２／ｇ
のＡｌ2Ｏ3−ＭｇＯ粉末に代えた以外は、実施例１と同
様の操作を繰り返してコート量約５０ｇ／Ｌのハニカム
触媒担体（ｅ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ｅ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒５）を得た。Example 5 (1) Formation of First Catalyst Layer The specific surface area was about 280 m 2, except that zinc phosphate was replaced with iron phosphate.
/ G of activated Al2O3 powder having a specific surface area of about 230 m2 / g
A honeycomb catalyst carrier (e) having a coating amount of about 50 g / L was obtained by repeating the same operation as in Example 1 except that Al2O3-MgO powder was used. (2) Formation of the second catalyst layer The Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1 was applied to the honeycomb catalyst carrier (e) carrying the first catalyst layer in the same manner, About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 5) was obtained.
【００３７】（実施例６） （１）第１触媒層の形成 リン酸亜鉛をリン酸錫に代え、比表面積が約２８０ｍ２
／ｇの活性Ａｌ2Ｏ3粉末を比表面積が約２３０ｍ２／ｇ
のＡｌ2Ｏ3−ＭｇＯ粉末に代えた以外は、実施例１と同
様の操作を繰り返してコート量約６０ｇ／Ｌのハニカム
触媒担体（ｆ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3−ＭｇＯ
触媒スラリーを用い、同様に上記第１触媒層が担持され
たハニカム触媒担体（ｆ）に塗布し、第２触媒のコート
量が約１８０ｇ／Ｌの本例の触媒（ハニカム触媒６）を
得た。Example 6 (1) Formation of First Catalyst Layer The specific surface area was about 280 m 2, with the zinc phosphate replaced with tin phosphate.
/ G of activated Al2O3 powder having a specific surface area of about 230 m2 / g
A honeycomb catalyst carrier (f) having a coating amount of about 60 g / L was obtained by repeating the same operation as in Example 1 except that Al2O3-MgO powder was used. (2) Formation of second catalyst layer Rh / Al2O3-MgO obtained in the same manner as in Example 1.
The catalyst slurry was similarly applied to the honeycomb catalyst carrier (f) carrying the first catalyst layer to obtain a catalyst of the present example (honeycomb catalyst 6) having a coating amount of the second catalyst of about 180 g / L. .
【００３８】（実施例７） （１）第１触媒層の形成 リン酸亜鉛をリン酸コバルトに代え、比表面積が約２８
０ｍ２／ｇの活性Ａｌ2Ｏ3粉末を比表面積が約３１８ｍ
２／ｇのＭＦＩゼオライト粉末に代えた以外は、実施例
１と同様の操作を繰り返してコート量約５０ｇ／Ｌのハ
ニカム触媒担体（ｇ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ｇ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒７）を得た。Example 7 (1) Formation of First Catalyst Layer Zinc phosphate was replaced with cobalt phosphate, and the specific surface area was about 28.
0 m2 / g of activated Al2O3 powder having a specific surface area of about 318 m
A honeycomb catalyst carrier (g) having a coating amount of about 50 g / L was obtained by repeating the same operation as in Example 1 except that 2 / g of the MFI zeolite powder was used. (2) Formation of Second Catalyst Layer Using the Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1, similarly applied to the honeycomb catalyst carrier (g) carrying the first catalyst layer, About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 7) was obtained.
【００３９】（実施例８） （１）第１触媒層の形成 リン酸亜鉛をリン酸亜鉛とリン酸銅との混合物（重量比
１：１）に代えた以外は、実施例１と同様の操作を繰り
返してコート量約６０ｇ（リン酸亜鉛：リン酸銅＝３０
ｇ：３０ｇ）／Ｌのハニカム触媒担体（ｈ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ｈ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒８）を得た。Example 8 (1) Formation of First Catalyst Layer Same as Example 1 except that zinc phosphate was replaced by a mixture of zinc phosphate and copper phosphate (weight ratio 1: 1). Repeat the operation to coat about 60 g (zinc phosphate: copper phosphate = 30
g: 30 g) / L of a honeycomb catalyst carrier (h). (2) Formation of Second Catalyst Layer Using the Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1, similarly applied to the honeycomb catalyst carrier (h) carrying the first catalyst layer, About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 8) was obtained.
【００４０】（実施例９） （１）第１触媒層の形成 比表面積が約２８０ｍ２／ｇの活性Ａｌ2Ｏ3粉末を比表
面積が約４６０ｍ２／ｇのβゼオライト粉末に代えた以
外は、実施例１と同様の操作を繰り返してコート量約５
０ｇ／Ｌのハニカム触媒担体（ｉ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ｉ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒９）を得た。Example 9 (1) Formation of First Catalyst Layer Example 1 was repeated except that active Al 2 O 3 powder having a specific surface area of about 280 m 2 / g was replaced with β zeolite powder having a specific surface area of about 460 m 2 / g. Repeat the same operation to coat about 5
0 g / L of the honeycomb catalyst carrier (i) was obtained. (2) Formation of the second catalyst layer The Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1 was applied to the honeycomb catalyst carrier (i) carrying the first catalyst layer in the same manner as described above. About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 9) was obtained.
【００４１】（実施例１０） （１）第１触媒層の形成 比表面積が約２８０ｍ２／ｇの活性Ａｌ2Ｏ3粉末を比表
面積が約３３０ｍ２／ｇのモルデナイト粉末に代えた以
外は、実施例１と同様の操作を繰り返してコート量約５
０ｇ／Ｌのハニカム触媒担体（ｊ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ｊ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒１０）を得た。Example 10 (1) Formation of First Catalyst Layer Same as Example 1 except that active Al 2 O 3 powder having a specific surface area of about 280 m 2 / g was replaced with mordenite powder having a specific surface area of about 330 m 2 / g. Repeat the above operation to coat about 5 coats.
0 g / L of a honeycomb catalyst carrier (j) was obtained. (2) Formation of the second catalyst layer The Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1 was applied to the honeycomb catalyst carrier (j) carrying the first catalyst layer in the same manner. About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 10) was obtained.
【００４２】（実施例１１） （１）第１触媒層の形成 リン酸亜鉛をリン酸銅に代え、比表面積が約２８０ｍ２
／ｇの活性Ａｌ2Ｏ3粉末を比表面積が約２８０ｍ２／ｇ
のＹ型ゼオライト粉末に代えた以外は、実施例１と同様
の操作を繰り返してコート量約５０ｇ／Ｌのハニカム触
媒担体（ｋ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ｋ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒１１）を得た。Example 11 (1) Formation of First Catalyst Layer The specific surface area was about 280 m 2, except that zinc phosphate was replaced by copper phosphate.
/ G of activated Al2O3 powder having a specific surface area of about 280 m2 / g
A honeycomb catalyst carrier (k) having a coating amount of about 50 g / L was obtained by repeating the same operation as in Example 1 except that the powder was replaced with the Y-type zeolite powder described above. (2) Formation of the second catalyst layer The Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1 was applied to the honeycomb catalyst carrier (k) carrying the first catalyst layer similarly, About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 11) was obtained.
【００４３】（実施例１２） （１）第１触媒層の形成 比表面積が約２８０ｍ２／ｇの活性Ａｌ2Ｏ3粉末を比表
面積が約５０ｍ２／ｇの活性Ａｌ2Ｏ3粉末に代えた以外
は、実施例１と同様の操作を繰り返してコート量約５０
ｇ／Ｌのハニカム触媒担体（ｌ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ／Ａｌ2Ｏ3触媒スラ
リーを用いて、同様に上記第１触媒層が担持されたハニ
カム触媒担体（ｌ）に塗布し、第２触媒のコート量が約
１８０ｇ／Ｌの本例の触媒（ハニカム触媒１２）を得
た。Example 12 (1) Formation of First Catalyst Layer Example 1 was repeated except that active Al 2 O 3 powder having a specific surface area of about 280 m 2 / g was replaced with active Al 2 O 3 powder having a specific surface area of about 50 m 2 / g. Repeat the same operation to coat about 50
g / L of the honeycomb catalyst carrier (1) was obtained. (2) Formation of second catalyst layer Using the Rh / Al2O3 catalyst slurry obtained in the same manner as in Example 1, the first catalyst layer was similarly coated on the honeycomb catalyst carrier (l), A catalyst of this example (honeycomb catalyst 12) having a coating amount of 2 catalysts of about 180 g / L was obtained.
【００４４】（実施例１３） （１）第１触媒層の形成 実施例１と同様の操作を繰り返してコート量約５０ｇ／
Ｌのハニカム触媒担体（ａ）を得た。 （２）第２触媒層の形成 実施例１と同様にして得られたＲｈ−ＳｉＯ2触媒スラ
リーを用い、同様に上記第１触媒層が担持されたハニカ
ム触媒担体（ａ）に塗布し、第２触媒のコート量が約１
８０ｇ／Ｌの本例の触媒（ハニカム触媒１３）を得た。Example 13 (1) Formation of First Catalyst Layer The same operation as in Example 1 was repeated to coat about 50 g /
L of honeycomb catalyst carrier (a) was obtained. (2) Formation of the second catalyst layer The Rh-SiO2 catalyst slurry obtained in the same manner as in Example 1 was applied to the honeycomb catalyst carrier (a) carrying the first catalyst layer similarly, About 1 coat of catalyst
80 g / L of the catalyst of the present example (honeycomb catalyst 13) was obtained.
【００４５】（比較例１）実施例１と同様のＲｈ−Ｗ／
Ａｌ2Ｏ3触媒スラリーを得た。次いで、このスラリー
を、実施例１の第２触媒層の形成と同様の操作により、
第１触媒層を形成していない上記ハニカム担体に直接塗
布し、触媒成分のコート量が約１８０ｇ／Ｌの本例の触
媒（ハニカム触媒Ｒｅｆ１）を得た。(Comparative Example 1) Rh-W /
An Al2O3 catalyst slurry was obtained. Next, this slurry was subjected to the same operation as in the formation of the second catalyst layer in Example 1 to give
The catalyst was directly applied to the honeycomb carrier on which the first catalyst layer was not formed to obtain a catalyst of this example (honeycomb catalyst Ref1) having a coating amount of a catalyst component of about 180 g / L.
【００４６】（比較例２）実施例１と同様にリン酸亜鉛
／Ａｌ2Ｏ3粉末を調製し、同様にしてコート量約５０ｇ
／Ｌのハニカム触媒担体（ａ）を得、第２触媒層を形成
せずに、これをそのまま本例の触媒（ハニカム触媒Ｒｅ
ｆ２）とした。Comparative Example 2 A zinc phosphate / Al 2 O 3 powder was prepared in the same manner as in Example 1, and a coating amount of about 50 g was similarly prepared.
/ L of the honeycomb catalyst carrier (a), and without forming the second catalyst layer, this was directly used as the catalyst of this example (honeycomb catalyst Re).
f2).
【００４７】（比較例３）リン酸亜鉛をリン酸コバルト
に代えた以外は、比較例２と同様の操作を繰り返して本
例の触媒（ハニカム触媒Ｒｅｆ３）を得た。Comparative Example 3 The same operation as in Comparative Example 2 was repeated, except that zinc phosphate was replaced with cobalt phosphate, to obtain a catalyst of this example (honeycomb catalyst Ref3).
【００４８】（比較例４）実施例１と同様にリン酸亜鉛
／Ａｌ2Ｏ3粉末を調製し、同様にしてコート量約５０ｇ
／Ｌのハニカム触媒担体（ａ）を得た。次いで、Ｐｔを
ＳｉＯ2−Ａｌ2Ｏ3混合物に担持したスラリー用いて第
２触媒層を形成し、本例の触媒（ハニカム触媒Ｒｅｆ
４）を得た。Comparative Example 4 A zinc phosphate / Al 2 O 3 powder was prepared in the same manner as in Example 1, and a coating amount of about 50 g was similarly prepared.
/ L of the honeycomb catalyst carrier (a) was obtained. Next, a second catalyst layer was formed using a slurry in which Pt was supported on a SiO 2 —Al 2 O 3 mixture, and the catalyst of this example (honeycomb catalyst Ref) was used.
4) was obtained.
【００４９】（比較例５）実施例１と同様にリン酸亜鉛
／Ａｌ2Ｏ3粉末を調製し、同様にしてコート量約５０ｇ
／Ｌのハニカム触媒担体（ａ）を得た。次いで、Ｐｄを
Ａｌ2Ｏ3に担持したスラリーを用いて第２触媒層を形成
し、本例の触媒（ハニカム触媒Ｒｅｆ５）を得た。Comparative Example 5 A zinc phosphate / Al 2 O 3 powder was prepared in the same manner as in Example 1, and a coating amount of about 50 g was similarly prepared.
/ L of the honeycomb catalyst carrier (a) was obtained. Next, a second catalyst layer was formed using a slurry in which Pd was supported on Al2O3, and a catalyst (honeycomb catalyst Ref5) of this example was obtained.
【００５０】［触媒性能試験例］ （触媒のエンジンダイナモ装置による性能試験）上記各
例の触媒を、４気筒２．５Ｌ直接噴射式ディーゼルエン
ジンを設置したエンジンダイナモ装置の排気系に組み込
み、各触媒による排気ガス中のＮＯｘの浄化性能を測定
した。なお、本エンジンダイナモ装置の排気系には、燃
料を注入するためのノズルが設けられており、触媒入口
における排気ガス中のＨＣ／ＮＯｘ比を制御できるよう
になっている。[Test example of catalyst performance] (Performance test of catalyst using engine dynamo device) The catalysts of the above examples were incorporated into the exhaust system of an engine dynamo device equipped with a 4-cylinder 2.5L direct injection diesel engine. The performance of purifying NOx in exhaust gas was measured. The exhaust system of the engine dynamo device is provided with a nozzle for injecting fuel, so that the HC / NOx ratio in the exhaust gas at the catalyst inlet can be controlled.
【００５１】また、ＮＯｘ浄化率測定の際、触媒入口温
度を１８０〜４５０℃までは約５０℃／ｍｉｎで昇温さ
せ、触媒入口温度４００℃におけるＮＯｘ浄化率を測定
した。触媒入口温度１８０〜３００℃までの排気ガス中
の平均ＨＣ／ＮＯｘ比は１．２であり、３００〜４５０
℃までの排気ガス中の平均ＨＣ／ＮＯｘ比は４であっ
た。更に、本測定時のガス空間速度は、約４００００ｈ
−１であった。表１に、各例の触媒の触媒入口温度４０
０℃におけるＮＯｘ浄化率を示す。また、各触媒の層構
造なども表１にまとめて示す。When measuring the NOx purification rate, the catalyst inlet temperature was raised at a rate of about 50 ° C./min from 180 to 450 ° C., and the NOx purification rate at a catalyst inlet temperature of 400 ° C. was measured. The average HC / NOx ratio in the exhaust gas at a catalyst inlet temperature of 180 to 300 ° C. is 1.2,
The average HC / NOx ratio in the exhaust gas up to ° C was 4. Further, the gas space velocity at the time of the main measurement was about 40,000 hours.
-1 . Table 1 shows the catalyst inlet temperature 40 for each example catalyst.
The NOx purification rate at 0 ° C. is shown. Table 1 also shows the layer structure of each catalyst.
【００５２】[0052]
【表１】 [Table 1]
【００５３】表１から、本発明の範囲に属する実施例の
触媒では、明らかにＮＯｘ浄化率が高く、内層たる第１
触媒層に含まれるリン酸塩（ＨＣ改質材）の効果が著し
いことが分かる。なお、比較例１及び２より、リン酸塩
は単独ではＮＯｘ浄化性能を発揮せず、また、比較例４
及び５より、表層触媒（第２触媒層）としてＰｔやＰｄ
触媒を使用しても殆ど浄化性能が得られず、本発明の排
気ガス浄化用触媒の有効性が明確に示されている。From Table 1, it can be seen that the catalysts of the examples belonging to the scope of the present invention have a clearly high NOx purification rate and the first
It can be seen that the effect of the phosphate (HC modifier) contained in the catalyst layer is significant. From Comparative Examples 1 and 2, the phosphate alone did not exhibit NOx purification performance, and Comparative Example 4
And 5, Pt and Pd are used as the surface catalyst (second catalyst layer).
Even if a catalyst is used, almost no purification performance is obtained, and the effectiveness of the exhaust gas purification catalyst of the present invention is clearly shown.
【００５４】[0054]
【発明の効果】以上説明してきたように、本発明によれ
ば、所定のリン酸塩が排気ガス中の炭化水素類の反応性
を改善でき、また、かかるリン酸塩系の炭化水素改質材
を含む触媒層とロジウムを含む触媒層とで適切な多層構
造を形成することとしたため、低ＨＣ／ＮＯｘ比の排気
条件の下でも、Ｎ2Ｏを殆ど生成することなく高効率で
ＮＯｘ浄化でき、更には高温条件下での劣化が少ない触
媒を得ることができる炭化水素改質材を用いた排気ガス
浄化用触媒を提供することができる。即ち、本発明のＨ
Ｃ改質材や排気ガス浄化用触媒を用いると、１５０℃以
下の低温を含み、且つ低いＨＣ／ＮＯｘ比条件下におい
て、排気ガスの浄化が高効率で可能となるため、環境汚
染が少なく、経済性（燃費）にも優れた自動車を提供す
ることも可能となる。As described above, according to the present invention, a predetermined phosphate can improve the reactivity of hydrocarbons in exhaust gas, and the phosphate-based hydrocarbon can be reformed. The catalyst layer containing the material and the catalyst layer containing rhodium form an appropriate multilayer structure, so that even under the exhaust conditions of a low HC / NOx ratio, NOx can be purified with high efficiency with almost no generation of N2O. Further, it is possible to provide an exhaust gas purifying catalyst using a hydrocarbon reforming material capable of obtaining a catalyst with little deterioration under high temperature conditions. That is, H of the present invention
When a C reforming material or an exhaust gas purifying catalyst is used, exhaust gas can be purified with high efficiency under a low HC / NOx ratio condition including a low temperature of 150 ° C. or less, so that environmental pollution is reduced. It is also possible to provide a car that is also excellent in economy (fuel efficiency).
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｂ０１Ｊ 27/185 Ｂ０１Ｊ 29/10 Ａ 29/06 29/18 Ａ 29/10 29/40 Ａ 29/18 Ｆ０１Ｎ 3/10 Ａ 29/40 Ｂ０１Ｄ 53/36 １０２Ｈ Ｆ０１Ｎ 3/10 Ｂ０１Ｊ 23/64 １０３Ａ (72)発明者 上久保 真紀 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内 Ｆターム(参考） 3G091 AA02 AA12 AA17 AA18 AB02 AB05 BA01 BA14 BA15 BA38 BA39 FB10 GA06 GA18 GB01W GB01X GB03W GB05W GB09X GB12W GB16W GB17X HA08 4D048 AA06 AA18 AB02 AB03 AB07 BA01X BA01Y BA03X BA06X BA07X BA08X BA09X BA11X BA27X BA33X BA41X BA42X BA44X BA44Y BB02 BB17 CA01 CC51 DA01 DA02 DA03 DA05 DA06 DA08 DA20 4G069 AA01 AA03 AA08 AA12 BA01A BA01B BA02A BA02B BA03A BA03B BA04A BA04B BA05A BA05B BA06A BA06B BA07A BA07B BA13B BB02A BB02B BB04A BB04B BB14A BB14B BC10A BC22A BC22B BC31A BC31B BC32A BC32B BC35A BC35B BC66A BC66B BC67A BC67B BC68A BC68B BC71A BC71B DA05 EA19 EB12Y EC03X EC03Y EC28 ED06 FA02 FA06 FB14 FB15 FB23 FB30 ZA04A ZA04B ZA06A ZA06B ZA19A ZA19B ZA32A ZA32B ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) B01J 27/185 B01J 29/10 A 29/06 29/18 A 29/10 29/40 A 29/18 F01N 3/10 A 29/40 B01D 53/36 102H F01N 3/10 B01J 23/64 103A (72) Inventor Maki Kamikubo F-term (reference) in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa 3G091 AA02 AA12 AA17 AA18 AB02 AB05 BA01 BA14 BA15 BA38 BA39 FB10 GA06 GA18 GB01W GB01X GB03W GB05W GB09X GB12W GB16W GB17X HA08 4D048 AA06 AA18 AB02 AB03 AB07 BA01X BA01Y BA03X BA06X BA07X BA08X BA09X BA11 BABAX BA33 BA01 BA33 BAX BAX BAX X DA08 DA20 4G069 AA01 AA03 AA08 AA12 BA01A BA01B BA02A BA02B BA03A BA03B BA04A BA04B BA05A BA05B BA06A BA06B BA07A BA07B BA13B BB0 2A BB02B BB04A BB04B BB14A BB14B BC10A BC22A BC22B BC31A BC31B BC32A BC32B BC35A BC35B BC66A BC66B BC67A BC67B BC68A BC68B BC71A BC71B ZA05A32 Z04A06 ZB12A
Claims (7)
覆して成る排気ガス浄化用触媒において、 上記ハニカム状モノリス型担体上に、排気ガス中の炭化
水素を部分的に酸化し得る炭化水素改質材として、リン
酸マグネシウム、リン酸銀、リン酸ニッケル、リン酸
銅、リン酸鉄、リン酸亜鉛、リン酸スズ及びリン酸コバ
ルトから成る群より選ばれた少なくとも１種のリン酸塩
を含む第１触媒層と、 ロジウム成分を含む第２触媒層とを順次積層して成るこ
とを特徴とする排気ガス浄化用触媒。1. An exhaust gas purifying catalyst comprising a honeycomb-shaped monolith-type carrier coated with a catalyst layer, wherein a hydrocarbon-converted hydrocarbon capable of partially oxidizing hydrocarbons in exhaust gas is formed on the honeycomb-type monolith-type carrier. As a material, at least one phosphate selected from the group consisting of magnesium phosphate, silver phosphate, nickel phosphate, copper phosphate, iron phosphate, zinc phosphate, tin phosphate and cobalt phosphate is used. An exhaust gas purifying catalyst comprising: a first catalyst layer containing a rhodium component; and a second catalyst layer containing a rhodium component.
を比表面積が６０ｍ２／ｇ以上の耐火性無機化合物に担
持して成ることを特徴とする請求項１記載の排気ガス浄
化用触媒。2. The exhaust gas purifying apparatus according to claim 1, wherein the first catalyst layer comprises the hydrocarbon reforming material supported on a refractory inorganic compound having a specific surface area of 60 m 2 / g or more. catalyst.
ム、ケイ素、チタン、ジルコニウム及びマグネシウムか
ら成る群より選ばれた少なくとも１種の成分を含む酸化
物であることを特徴とする請求項２記載の排気ガス浄化
用触媒。3. The exhaust gas according to claim 2, wherein the refractory inorganic compound is an oxide containing at least one component selected from the group consisting of aluminum, silicon, titanium, zirconium and magnesium. Gas purification catalyst.
ト、ＭＦＩゼオライト、βゼオライト及びＹ型ゼオライ
トから成る群より選ばれた少なくとも１種のゼオライト
であることを特徴とする請求項２記載の排気ガス浄化用
触媒。4. The exhaust gas purification according to claim 2, wherein the refractory inorganic compound is at least one zeolite selected from the group consisting of mordenite, MFI zeolite, β zeolite and Y-type zeolite. Catalyst.
が６０ｍ２／ｇ以上の耐火性無機化合物に担持して成る
ことを特徴とする請求項１〜４のいずれか１つの項に記
載の排気ガス浄化用触媒。5. The method according to claim 1, wherein the second catalyst layer supports rhodium on a refractory inorganic compound having a specific surface area of 60 m 2 / g or more. Exhaust gas purification catalyst.
ム、ケイ素、チタン、ジルコニウム及びマグネシウムか
ら成る群より選ばれた少なくとも１種の成分を含む酸化
物であることを特徴とする請求項５記載の排気ガス浄化
用触媒。6. The exhaust gas according to claim 5, wherein said refractory inorganic compound is an oxide containing at least one component selected from the group consisting of aluminum, silicon, titanium, zirconium and magnesium. Gas purification catalyst.
含有することを特徴とする請求項１〜６のいずれか１つ
の項に記載の排気ガス浄化用触媒。7. The exhaust gas purifying catalyst according to claim 1, wherein the second catalyst layer further contains tungsten.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10220067A JP2000042415A (en) | 1998-08-04 | 1998-08-04 | Catalyst for exhaust gas purification using hydrocarbon reforming material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10220067A JP2000042415A (en) | 1998-08-04 | 1998-08-04 | Catalyst for exhaust gas purification using hydrocarbon reforming material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000042415A true JP2000042415A (en) | 2000-02-15 |
Family
ID=16745433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10220067A Pending JP2000042415A (en) | 1998-08-04 | 1998-08-04 | Catalyst for exhaust gas purification using hydrocarbon reforming material |
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| Country | Link |
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| JP (1) | JP2000042415A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013035568A1 (en) | 2011-09-06 | 2013-03-14 | 三井金属鉱業株式会社 | Catalyst carrier for exhaust gas purification and catalyst for exhaust gas purification |
| JP2014012267A (en) * | 2012-06-07 | 2014-01-23 | Toyota Central R&D Labs Inc | Catalyst for reforming hydrocarbon, exhaust gas cleaning apparatus using the same and manufacturing method of catalyst for reforming hydrocarbon |
| CN106881122A (en) * | 2017-03-30 | 2017-06-23 | 常州大学 | A kind of silver orthophosphate loads the preparation method of trbasic zinc phosphate photochemical catalyst |
| CN107096554A (en) * | 2017-03-30 | 2017-08-29 | 常州大学 | A kind of cobalt phosphate aids in the preparation method of silver phosphate photocatalyst |
| JP2018528849A (en) * | 2015-07-09 | 2018-10-04 | ユミコア アクチェンゲゼルシャフト ウント コンパニー コマンディートゲゼルシャフト | Three-way catalyst with NH3-SCR activity, ammonia oxidation activity and adsorption capacity for volatile vanadium and tungsten compounds |
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1998
- 1998-08-04 JP JP10220067A patent/JP2000042415A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013035568A1 (en) | 2011-09-06 | 2013-03-14 | 三井金属鉱業株式会社 | Catalyst carrier for exhaust gas purification and catalyst for exhaust gas purification |
| CN103958055A (en) * | 2011-09-06 | 2014-07-30 | 三井金属矿业株式会社 | Catalyst carrier for exhaust gas purification and catalyst for exhaust gas purification |
| US9827556B2 (en) | 2011-09-06 | 2017-11-28 | Mitsui Mining & Smelting Co., Ltd. | Catalyst carrier for exhaust gas purification and catalyst for exhaust gas purification |
| CN109364965A (en) * | 2011-09-06 | 2019-02-22 | 三井金属矿业株式会社 | Exhaust gas purification catalyst carrier and exhaust gas purification catalyst |
| EP3466538A1 (en) | 2011-09-06 | 2019-04-10 | Mitsui Mining & Smelting Co., Ltd. | Catalyst carrier for exhaust gas purification and catalyst for exhaust gas purification |
| JP2014012267A (en) * | 2012-06-07 | 2014-01-23 | Toyota Central R&D Labs Inc | Catalyst for reforming hydrocarbon, exhaust gas cleaning apparatus using the same and manufacturing method of catalyst for reforming hydrocarbon |
| JP2018528849A (en) * | 2015-07-09 | 2018-10-04 | ユミコア アクチェンゲゼルシャフト ウント コンパニー コマンディートゲゼルシャフト | Three-way catalyst with NH3-SCR activity, ammonia oxidation activity and adsorption capacity for volatile vanadium and tungsten compounds |
| CN106881122A (en) * | 2017-03-30 | 2017-06-23 | 常州大学 | A kind of silver orthophosphate loads the preparation method of trbasic zinc phosphate photochemical catalyst |
| CN107096554A (en) * | 2017-03-30 | 2017-08-29 | 常州大学 | A kind of cobalt phosphate aids in the preparation method of silver phosphate photocatalyst |
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