JP2548756B2 - Catalyst for removing nitrogen oxides - Google Patents
Catalyst for removing nitrogen oxidesInfo
- Publication number
- JP2548756B2 JP2548756B2 JP62308723A JP30872387A JP2548756B2 JP 2548756 B2 JP2548756 B2 JP 2548756B2 JP 62308723 A JP62308723 A JP 62308723A JP 30872387 A JP30872387 A JP 30872387A JP 2548756 B2 JP2548756 B2 JP 2548756B2
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- Japan
- Prior art keywords
- oxide
- catalyst
- nitrogen oxides
- exhaust gas
- titanium
- 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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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明はボイラ排ガス等の燃焼排ガス中に含まれる窒
素酸化物を除去するための触媒に関する。TECHNICAL FIELD The present invention relates to a catalyst for removing nitrogen oxides contained in combustion exhaust gas such as boiler exhaust gas.
重油や石炭焚ボイラ、各種化学装置に付設する燃焼
炉、製鉄プラント、硝酸プラント、デイーゼルエンジン
やタービンの如き内燃機関からの排ガス中の窒素酸化物
（以下NOxという）の無害化処理方法としては、吸着
法、酸化吸収法、固体化捕集法、接触還元法などが知ら
れている。その中でも後処理不要の触媒還元法が経済的
にも技術的にも優れている。As a method for detoxifying nitrogen oxides (hereinafter referred to as NOx) in exhaust gas from internal combustion engines such as heavy oil and coal-fired boilers, combustion furnaces attached to various chemical devices, ironmaking plants, nitric acid plants, diesel engines and turbines, Adsorption method, oxidation absorption method, solidification collection method, catalytic reduction method, etc. are known. Among them, the catalytic reduction method, which requires no post-treatment, is economically and technically superior.
接触還元法においても排ガス中の酸素の有無に影響さ
れない選択的接触還元法が脱硝操作を容易にし技術的に
も優れている。その１つに、アンモニアを添加し接触還
元して排ガス中のNOxを無害な窒素と水に分解する方法
が最も経済的でかつ効果的な方法として工業化されてお
り、現在ではこの方式を採用した数多くのブラントが稼
動している。Also in the catalytic reduction method, the selective catalytic reduction method which is not affected by the presence or absence of oxygen in the exhaust gas facilitates the denitration operation and is technically superior. One of the most economical and effective methods is to industrialize the method of adding ammonia and catalytically reducing NOx in exhaust gas into harmless nitrogen and water, and this method has been adopted at present. Many brands are in operation.
この方法に用いる触媒として、酸化タングステン、酸
化バナジウム、酸化モリブデン、酸化鉄などを酸化チタ
ンに担持した触媒（特公昭57−36012）や酸化セリウム
を酸化チタンに担持した触媒（特公昭53−13339）など
が知られている。酸化チタンを担体とする触媒以外に高
比表面積な酸化アルミニウムに酸化バナジウムを担持し
た触媒（特公昭56−44778）もあるが、重油や石炭燃焼
排ガスのような硫黄酸化物を含有する排ガス処理のため
には、硫黄酸化物に対する耐被毒性の点から酸化チタン
を担体とした触媒の方が優れている。この中でも酸化チ
タン−酸化バナジウム−酸化タングステン触媒が活性も
高く、耐久性に優れた触媒であることから数多くの実機
ブラントで窒素酸化物の除去用触媒として用いられてい
る。As a catalyst used in this method, a catalyst in which tungsten oxide, vanadium oxide, molybdenum oxide, iron oxide, etc. are supported on titanium oxide (Japanese Patent Publication No. 57-36012) and a catalyst in which cerium oxide is supported on titanium oxide (Japanese Patent Publication No. 53-13339) Are known. In addition to a catalyst using titanium oxide as a carrier, there is also a catalyst that supports vanadium oxide on aluminum oxide with a high specific surface area (Japanese Patent Publication No. 56-44778), but it is not suitable for treating exhaust gas containing sulfur oxides such as heavy oil and coal combustion exhaust gas. For this reason, a catalyst using titanium oxide as a carrier is superior in terms of resistance to poisoning to sulfur oxides. Among them, the titanium oxide-vanadium oxide-tungsten oxide catalyst has a high activity and is a catalyst having excellent durability, and therefore, it is used as a catalyst for removing nitrogen oxides in many actual-purpose blunts.
酸化チタン−酸化バナジウム−酸化タングステン触媒
を用いた実機プラントにおいて、排ガス発生源の運転状
況の変化に対応してNOxの除去効率が変化する現象が見
られた。このため排ガス中のNOxについてNOとNO2に分別
して濃度を測定したところ、定常状態ではNOxの大部分
はNOで存在し、高い除去効率が得られるものの、非定常
状態ではNOxの大部分はNO2で存在し、低い除去効率しか
得られないことが明らかとなつた。In an actual plant using a titanium oxide-vanadium oxide-tungsten oxide catalyst, a phenomenon was observed in which the NOx removal efficiency changed in response to changes in the operating conditions of the exhaust gas generation source. Therefore, when NOx in the exhaust gas was separated into NO and NO 2 and the concentration was measured, most of NOx was present in the steady state, and high removal efficiency was obtained, but most of the NOx was found in the unsteady state. It was revealed that NO 2 was present and only low removal efficiency was obtained.
本発明者らはこの現象を実験室でさらに詳細に検討す
るため、酸化チタン−酸化バナジウム−酸化タングステ
ン触媒のNOとNH3の反応、NOとNO2の混合ガスとNH3の反
応、さらにNO2とNH3との反応について実験を行なつた結
果、NOxのNH3による還元反応は下記の（１）〜（３）式
により進行し、NOおよびNO2の存在割合によつて著しくN
Ox除去効率が変化することが判つた。In order to study this phenomenon in more detail in the laboratory, the present inventors have investigated the reaction between NO and NH 3 of a titanium oxide-vanadium oxide-tungsten oxide catalyst, the reaction between a mixed gas of NO and NO 2 and NH 3 , and NO. As a result of conducting an experiment on the reaction between 2 and NH 3 , the reduction reaction of NOx with NH 3 proceeds according to the following equations (1) to (3), and the NO and NO 2 contents significantly increase.
It was found that the Ox removal efficiency changed.
4NO＋4NH3＋O2→4N2＋6H2O …（１） NO＋NO2＋2NH3→2N2＋3H2O …（２） 6NO2＋8NH3→7N2＋12H2O …（３） すなわち（２）式に示すNOxの除去効率は（１）式に
比べ混合ガス中のNO/NO2モル比が1.0以上では若干上回
るものの、NO/NO2モル比が1.0以下ではNO/NO2比が小さ
くなると共に徐々に低下していき、（３）式に示すNO2
単独では著しく低下することが判つた。第１図にこのNO
−NO2混合系のNOx除去効率をグラフに示す。4NO + 4NH 3 ＋ O 2 → 4N 2 ＋ 6H 2 O… (1) NO ＋ NO 2 ＋ 2NH 3 → 2N 2 ＋ 3H 2 O… （2） 6NO 2 ＋ 8NH 3 → 7N 2 ＋ 12H 2 O… (3) That is, NOx shown in the formula (2) removal efficiency although slightly above at not less than 1.0 NO / NO 2 molar ratio in the mixed gas compared to the (1) formula, gradually decreased with NO / NO 2 molar ratio NO / NO 2 ratio is small at 1.0 or less NO 2 shown in equation (3)
It has been found that it is significantly reduced by itself. This NO in Figure 1
The graph shows the NOx removal efficiency of the -NO 2 mixture system.
以上の如く、従来の酸化チタン−酸化バナジウム−酸
化タングステン触媒を用いた場合、NO/NO2モル比が1.0
以下あるいはNO2単独の場合にNOx除去効率が著しく低下
するという欠点がある。As described above, when the conventional titanium oxide-vanadium oxide-tungsten oxide catalyst was used, the NO / NO 2 molar ratio was 1.0.
There is a drawback that the NOx removal efficiency is remarkably reduced in the following cases or when NO 2 alone is used.
本発明は従来の排ガス中のNOxの除去方法の欠点を解
消し、特にNO/NO2モル比が1.0以下に片寄つた場合にお
いても高い除去率を維持することを可能にした排ガスの
窒素酸化物の除去用触媒を提供しようとするものであ
る。The present invention eliminates the drawbacks of the conventional method for removing NOx in exhaust gas, and in particular the NO / NO 2 molar ratio makes it possible to maintain a high removal rate even when deviating to 1.0 or less, and nitrogen oxides in exhaust gas. It is intended to provide a catalyst for removal of
本発明者らは排ガス中のNOxの内NO2がNO/NO2モル比が
1.0以下に片寄つた場合においてNOx除去効率が低下する
従来触媒の改良に関して、鋭意検討を重ねた結果、従来
の酸化チタン−酸化バナジウム−酸化タングステン触媒
に酸化銅と酸化クロムを複合酸化物の形で担持する触媒
を調製することによつて、排ガス中のNO2濃度の変化に
影響を受けないことを見い出し、本発明を完成するに至
つた。The present inventors have found that NO 2 in NOx in exhaust gas has a NO / NO 2 molar ratio of
As a result of extensive studies on the improvement of the conventional catalyst in which the NOx removal efficiency decreases when it is deviated to 1.0 or less, copper oxide and chromium oxide in the form of a composite oxide are added to the conventional titanium oxide-vanadium oxide-tungsten oxide catalyst. By preparing the supported catalyst, it was found that the catalyst was not affected by the change in NO 2 concentration in the exhaust gas, and the present invention was completed.
すなわち、本発明の窒素酸化物除去用触媒は第一成分
としてチタン酸化物、第二成分としてバナジウム酸化物
とタングステン酸化物、第三成分として銅酸化物とクロ
ム酸化物の複合酸化物を含有してなるものである。That is, the catalyst for removing nitrogen oxides of the present invention contains titanium oxide as the first component, vanadium oxide and tungsten oxide as the second component, and a composite oxide of copper oxide and chromium oxide as the third component. It will be.
上記の酸化チタン−酸化バナジウム−酸化タングステ
ン−酸化銅・酸化クロム複合酸化物含有触媒を調整する
には、まずチタン源としては塩化チタン、硫酸チタンな
どの無機性チタン化合物および修酸チタン、テトラアル
コキシチタンなどの有機性チタン化合物などから選ぶこ
とができる。バナジウム源としてはバナジウムの酸化
物、硫酸バナジル、修酸バナジル、メタバナジン酸アン
モニウムなどから、タングステン源としてはパラタング
ステン酸アンモニウム、メタタングステン酸アンモニウ
ムなどから選ぶことができる。次に銅源としては硫酸
銅、硝酸銅などから、クロム源としては硫酸クロム、硝
酸クロム、クロム酸、重クロム酸アンモニウムなどから
選ぶことができる。さらに触媒の成形性や強度を向上さ
せる目的でモンモリロナイト、酸性白土、ベントナイ
ト、カオリン、ハロイサイト、セリサイトなどの粘土系
無機物質や、グラスウール、グラスフアイバー、ロツク
ウール、カオウールなどの無機繊維状物質を添加した担
体も用い得る。ただし、触媒活性の点から、これらの添
加物は担体主成分に対して30wt％以下であることが好ま
しい。In order to prepare the above titanium oxide-vanadium oxide-tungsten oxide-copper oxide / chromium oxide composite oxide-containing catalyst, first, as a titanium source, titanium chloride, an inorganic titanium compound such as titanium sulfate, and titanium oxalate, tetraalkoxy. It can be selected from organic titanium compounds such as titanium. The vanadium source can be selected from vanadium oxide, vanadyl sulfate, vanadyl oxalate, ammonium metavanadate, and the like, and the tungsten source can be selected from ammonium paratungstate, ammonium metatungstate, and the like. Next, the copper source can be selected from copper sulfate, copper nitrate and the like, and the chromium source can be selected from chromium sulfate, chromium nitrate, chromic acid, ammonium dichromate and the like. Clay-based inorganic substances such as montmorillonite, acid clay, bentonite, kaolin, halloysite, sericite, and inorganic fibrous substances such as glass wool, glass fiber, rock wool, and kaool were added for the purpose of improving the moldability and strength of the catalyst. A carrier can also be used. However, from the viewpoint of catalytic activity, the amount of these additives is preferably 30 wt% or less with respect to the main component of the carrier.
一般的にバナジウム酸化物、タングステン酸化物は重
量比でチタン酸化物１に対し、それぞれ0.001〜0.1、0.
01〜0.2である。良好な触媒活性を得るには、第三成分
として加える銅化合物とクロム化合物の複合酸化物の配
合割合は酸化物換算の重量比で酸化チタンの１に対して
0.002〜0.2、好ましくは0.01〜0.1の範囲がよい。本発
明の触媒はその形状を選択することによつて、固定層、
移動層、流動層のいずれの反応器形成でも使用すること
ができるが、反応温度は通常は200〜600℃、好ましくは
250〜450℃が適当である。反応時間は、触媒の単位立方
米当り毎時1,000〜100.000Nm3の範囲が選ばれる。反応
圧力は大気圧、減圧、加圧のいずれでも行い得るので特
に制限はない。Generally, vanadium oxide and tungsten oxide are 0.001 to 0.1 and 0.1% by weight, respectively, with respect to titanium oxide.
01 to 0.2. In order to obtain good catalytic activity, the compounding ratio of the compound oxide of the copper compound and the chromium compound added as the third component is 1 to titanium oxide in a weight ratio of oxide conversion.
The range of 0.002-0.2, preferably 0.01-0.1 is good. The catalyst of the present invention has a fixed bed, by selecting its shape,
Although it can be used in the formation of either a moving bed or fluidized bed reactor, the reaction temperature is usually 200 to 600 ° C., preferably
250 to 450 ° C is suitable. The reaction time is selected in the range of 1,000 to 100.000 Nm 3 / hour per unit cubic rice of the catalyst. The reaction pressure may be atmospheric pressure, reduced pressure, or increased pressure, and is not particularly limited.
以下実施例により詳しく説明する。 A detailed description will be given below with reference to examples.
＜実施例１＞ メタチタン酸スラリー625g（TiO2として200g）にメタ
バナジン酸アンモニウム12.9gとパラタングステン酸ア
ンモニウム18.0gを水に溶解したものを加え、生成した
スラリー溶液を蒸発乾固する。生成した固体をＡとす
る。Example 1 To 625 g of metatitanic acid slurry (200 g as TiO 2 ) was added 12.9 g of ammonium metavanadate and 18.0 g of ammonium paratungstate dissolved in water, and the resulting slurry solution was evaporated to dryness. The produced solid is designated as A.
また別に重クロム酸アンモニウム〔（NH4）2Cr2O7〕
4.4gを100mlの水に溶解し、さらにアンモニア水（28％
溶液4.6ml）を加えた溶液に硝酸銅〔Cu（NO3）２・3H
2O〕4.2gを100mlの水に溶解させた溶液をゆつくりと滴
下し、滴下終了後60分間撹拌を行なう。この間溶液のpH
を6.7に保つためアンモニア水を少量滴下する。生成し
たスラリー溶液をＢとする。In addition, ammonium dichromate [(NH 4 ) 2 Cr 2 O 7 ]
Dissolve 4.4 g in 100 ml of water and add ammonia water (28%
Solution 4.6 ml) to a solution of copper nitrate was added [Cu (NO 3) 2 · 3H
A solution of 4.2 g of [ 2 O] in 100 ml of water is slowly added dropwise, and after completion of the addition, stirring is carried out for 60 minutes. During this time the pH of the solution
A small amount of aqueous ammonia is added dropwise to maintain 6.7. The resulting slurry solution is designated as B.
次に固体Ａとスラリー溶液Ｂを過したケーキをニー
ダで十分混練した。混練後直径3mmの棒状に押出し、120
℃で６時間乾燥後450℃で５時間焼成した。得られた触
媒は重量比でTiO2:V2O5:WO3:（CuO・Cr2O3）＝1:0.05:
0.08:0.02の組成を有する。Next, the cake containing the solid A and the slurry solution B was thoroughly kneaded with a kneader. After kneading, extruding into a rod shape with a diameter of 3 mm, 120
After drying at 6 ° C for 6 hours, it was baked at 450 ° C for 5 hours. The resulting catalyst had a weight ratio of TiO 2 : V 2 O 5 : WO 3 : (CuO.Cr 2 O 3 ) = 1: 0.05:
It has a composition of 0.08: 0.02.
比較のため、固体Ａのみに水を加え、上記と同様の方
法により触媒を調製した。得られた触媒は重量比でTi
O2:V2O5:WO3＝1:0.05:0.08の組成を有する（以下比較例
１の触媒という。）。For comparison, water was added only to solid A and a catalyst was prepared by the same method as above. The obtained catalyst is Ti in a weight ratio.
It has a composition of O 2 : V 2 O 5 : WO 3 = 1: 0.05: 0.08 (hereinafter referred to as the catalyst of Comparative Example 1).
また固体A226gに酸化クロム2gと酸化銅2gとを加え、
以下実施例と同様の方法により触媒を調製した。得られ
た触媒は重量比でTiO2:V2O5:WO3:CuO:Cr2O3＝1:0.05:0.
08:0.01:0.01の組成を有する（以下、比較例２の触媒と
いう）。In addition, 2 g of chromium oxide and 2 g of copper oxide are added to solid A226 g,
A catalyst was prepared in the same manner as in the examples below. The resulting catalyst TiO a weight ratio 2: V 2 O 5: WO 3: CuO: Cr 2 O 3 = 1: 0.05: 0.
It has a composition of 08: 0.01: 0.01 (hereinafter referred to as the catalyst of Comparative Example 2).
（２） 窒素酸化物除去試験 上記により調製した本発明及び比較例の触媒を直径3m
m、長さ３〜5mmの円柱状とし、これを内径24mmの石英製
小型反応器に充てんし、SV 20,000hr-1で脱硝活性試験
を行なつた。ガス組成は下記の通りであつた。(2) Nitrogen Oxide Removal Test The catalysts of the present invention and comparative examples prepared as described above had a diameter of 3 m.
A cylindrical reactor having an inner diameter of 3 mm and a length of 3 to 5 mm was filled in a small quartz reactor having an inner diameter of 24 mm, and a denitration activity test was conducted at SV 20,000 hr -1 . The gas composition was as follows.
（ガス組成１） （ガス組成２） NO :190ppm NO : 10ppm NO2: 10ppm NO2:190ppm NH3:200ppm NH3:200ppm O2 : ５％ O2 : ５％ CO2: 12％ CO2: 12％ H2O: ９％ H2O: ９％ N2 : 残 N2 : 残 反応器入口と出口のNOx濃度をケミルミネツセンス式
のNOx分析計により測定した。結果を表１に示す。(Gas composition 1) (Gas composition 2) NO: 190ppm NO: 10ppm NO 2 : 10ppm NO 2 : 190ppm NH 3 : 200ppm NH 3 : 200ppm O 2 : 5% O 2 : 5% CO 2 : 12% CO 2 : 12% H 2 O: 9% H 2 O: 9% N 2: the remaining N 2: the concentration of NOx remaining reactor inlet and outlet were measured by NOx analyzer chemiluminescence Tsu sense expression. The results are shown in Table 1.
表１から明らかなように本発明による触媒はガス組成
１及び２に対し、共に良好な活性（NOx除去率）を示す
が、比較触媒はガス組成１に対しては高い活性を示す
が、ガス組成２に対しては活性が低く、特に250℃と反
応温度が比較的低温の場合に顕著である。 As is clear from Table 1, the catalyst according to the present invention shows good activity (NOx removal rate) for both gas compositions 1 and 2, while the comparative catalyst shows high activity for gas composition 1, but The activity is low for the composition 2, especially when the reaction temperature is relatively low at 250 ° C.
＜実施例２〜６＞ 実施例１と同様な方法により、重クロム酸アンモニウ
ム及び硝酸銅の添加量を変化させて本発明の触媒を５種
調製した。<Examples 2 to 6> In the same manner as in Example 1, five types of catalysts of the present invention were prepared by changing the addition amounts of ammonium dichromate and copper nitrate.
これらの触媒及びガス組成２のガスを用い、実施例１
と同様にして、反応温度と窒素酸化物除去率の関係を求
めた。得られた結果を表２に示す。Example 1 using these catalysts and gas of gas composition 2
Similarly to the above, the relationship between the reaction temperature and the nitrogen oxide removal rate was obtained. The obtained results are shown in Table 2.
表２から明らかなように実施例２〜６すなわちTiO2:V
2O5:WO3:CuO・Cr2O3＝1:0.05:0.08:0.002〜0.2の範囲内
で高い活性が得られた。 As is clear from Table 2, Examples 2 to 6, that is, TiO 2 : V
A high activity was obtained within the range of 2 O 5 : WO 3 : CuO.Cr 2 O 3 = 1: 0.05: 0.08: 0.002-0.2.
〔発明の効果〕 本発明の触媒を用いることによつて、窒素酸化物の大
半が二酸化窒素として含有する排ガス中の窒素酸化物を
一酸化窒素の場合と同様に高い除去率で除去することが
できた。[Effects of the Invention] By using the catalyst of the present invention, it is possible to remove nitrogen oxides in exhaust gas containing most of nitrogen oxides as nitrogen dioxide at a high removal rate as in the case of nitric oxide. did it.
第１図は本発明の触媒の効果を示す図表である。 FIG. 1 is a chart showing the effect of the catalyst of the present invention.
Claims (2)
下で接触的に還元処理する触媒において、第一成分とし
てチタン酸化物、第二成分としてバナジウム酸化物とタ
ングステン酸化物、第三成分として銅酸化物とクロム酸
化物の複合酸化物を含有してなることを特徴とする排ガ
ス中の窒素酸化物の除去用触媒。1. A catalyst for catalytically reducing nitrogen oxides in exhaust gas in the presence of ammonia, wherein titanium oxide is used as a first component, vanadium oxide and tungsten oxide are used as a second component, and third component is used. A catalyst for removing nitrogen oxides in exhaust gas, comprising a composite oxide of copper oxide and chromium oxide.
酸化物１に対しバナジウム酸化物が0.001〜0.1、タング
ステン酸化物が0.01〜0.2、銅酸化物とクロム酸化物の
複合酸化物が0.002〜0.2であることを特徴とする特許請
求の範囲第１項に記載の排ガス中の窒素酸化物の除去用
触媒。2. The content ratio of each component is 0.001 to 0.1 of vanadium oxide, 0.01 to 0.2 of tungsten oxide, and a composite oxide of copper oxide and chromium oxide with respect to titanium oxide in a weight ratio. The catalyst for removing nitrogen oxides in exhaust gas according to claim 1, wherein the catalyst is 0.002 to 0.2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62308723A JP2548756B2 (en) | 1987-12-08 | 1987-12-08 | Catalyst for removing nitrogen oxides |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62308723A JP2548756B2 (en) | 1987-12-08 | 1987-12-08 | Catalyst for removing nitrogen oxides |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01151940A JPH01151940A (en) | 1989-06-14 |
| JP2548756B2 true JP2548756B2 (en) | 1996-10-30 |
Family
ID=17984507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62308723A Expired - Lifetime JP2548756B2 (en) | 1987-12-08 | 1987-12-08 | Catalyst for removing nitrogen oxides |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2548756B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008119651A (en) * | 2006-11-15 | 2008-05-29 | Mitsubishi Heavy Ind Ltd | Catalyst for nitrogen oxide removal, and exhaust gas treating method |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100502853B1 (en) * | 2000-08-24 | 2005-07-20 | 주식회사 포스코 | Cr·W·TiO2 CATALYST AND METHOD FOR THE REMOVAL OF DIOXINS |
| JP4508615B2 (en) | 2003-04-18 | 2010-07-21 | 三菱重工業株式会社 | Nitrogen oxide removal catalyst, catalyst molded product, exhaust gas treatment method and combined power generation facility |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5421956A (en) * | 1977-07-20 | 1979-02-19 | Hitachi Ltd | Method of removing nitrogen oxides contained in exhaust gas |
| JPH064126B2 (en) * | 1985-06-10 | 1994-01-19 | 株式会社日本触媒 | Exhaust gas purification method |
-
1987
- 1987-12-08 JP JP62308723A patent/JP2548756B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008119651A (en) * | 2006-11-15 | 2008-05-29 | Mitsubishi Heavy Ind Ltd | Catalyst for nitrogen oxide removal, and exhaust gas treating method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01151940A (en) | 1989-06-14 |
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