JPH09271674A - Oxidizing catalyst for diesel exhaust gas - Google Patents
Oxidizing catalyst for diesel exhaust gasInfo
- Publication number
- JPH09271674A JPH09271674A JP8082433A JP8243396A JPH09271674A JP H09271674 A JPH09271674 A JP H09271674A JP 8082433 A JP8082433 A JP 8082433A JP 8243396 A JP8243396 A JP 8243396A JP H09271674 A JPH09271674 A JP H09271674A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- sulfate
- supporting layer
- exhaust gas
- catalyst supporting
- 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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- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、ディーゼルエンジ
ン(以下DEという)の排ガス中に含まれるHC(炭化
水素)及びSOF(Soluble Organic Fraction)を酸化
浄化するとともに、ディーゼルパティキュレートの排出
量を低減できるディーゼル排ガス用酸化触媒に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention oxidizes and purifies HC (hydrocarbon) and SOF (Soluble Organic Fraction) contained in the exhaust gas of a diesel engine (hereinafter referred to as DE) and reduces the emission amount of diesel particulates. The present invention relates to an oxidation catalyst for diesel exhaust gas.
【0002】[0002]
【従来の技術】ガソリンエンジンについては、排ガスの
厳しい規制とそれに対処できる技術の進歩により、排ガ
ス中の有害物質は確実に減少している。しかしDEにつ
いては、有害成分が主としてパティキュレートとして排
出されるという特異な事情から、規制も技術の開発もガ
ソリンエンジンに比べて遅れており、確実に浄化できる
排ガス浄化触媒の開発が望まれている。2. Description of the Related Art Regarding gasoline engines, harmful substances in exhaust gas have been steadily reduced due to strict regulations on exhaust gas and advances in technology capable of coping with it. However, with regard to DE, due to the unique circumstances that harmful components are mainly emitted as particulates, regulations and development of technology are delayed compared to gasoline engines, and the development of exhaust gas purification catalysts that can reliably purify is desired. .
【0003】現在までに開発されているDE排気ガス浄
化装置としては、大きく分けてトラップを用いる方法
(触媒無しと触媒付き)と、オープン型SOF分解触媒
とが知られている。このうちトラップを用いる方法は、
ディーゼルパティキュレートを捕捉してその排出を規制
するものであり、特にドライスーツの比率の高い排気ガ
スに有効である。しかしながらトラップを用いる方法で
は、捕捉されたディーゼルパティキュレートを焼却する
ための再生処理装置が必要となり、再生時の触媒構造体
の割れ、アッシュによる閉塞あるいはシステムが複雑に
なるなど、実用上多くの課題を残している。[0003] As a DE exhaust gas purifying apparatus which has been developed to date, a method using a trap (without a catalyst and with a catalyst) and an open type SOF decomposition catalyst are known. Of these, the method using a trap is
It captures diesel particulates and regulates their emissions, and is especially effective for exhaust gas with a high dry suit ratio. However, the method using a trap requires a reprocessing device to incinerate the captured diesel particulates, which causes many practical problems such as cracking of the catalyst structure during regeneration, blockage by ash, or complicated systems. Is leaving.
【0004】一方オープン型SOF分解触媒は、例えば
特開平3−38255号公報に示されるように、ガソリ
ンエンジンと同様に活性アルミナなどの触媒担持層に白
金族金属などの触媒金属を担持した触媒が利用され、C
OやHCとともにSOFを酸化分解して浄化している。
このオープン型SOF分解触媒は、ドライスーツの除去
率が低いという欠点があるが、ドライスーツの量はDE
や燃料自体の改良によって低減することが可能であり、
かつ再生処理装置が不要という大きなメリットがあるた
め、今後の一段の技術の向上が期待されている。On the other hand, an open type SOF decomposition catalyst is, for example, as disclosed in Japanese Unexamined Patent Publication No. 3-38255, a catalyst in which a catalyst supporting layer such as activated alumina is loaded with a catalytic metal such as a platinum group metal as in a gasoline engine. Used, C
Purifies by oxidizing and decomposing SOF together with O and HC.
This open type SOF decomposition catalyst has a drawback that the removal rate of dry suit is low, but the amount of dry suit is DE
It can be reduced by improving the fuel and fuel itself,
Moreover, since there is a great merit that a reproduction processing device is unnecessary, further improvement of the technology is expected in the future.
【0005】[0005]
【発明が解決しようとする課題】ところがオープン型S
OF分解触媒においては、特に高温域で排ガス中のSO
2 までも酸化されてSO3 やSO4 (SOx )が生成す
る。このSOx はきわめて反応活性が高いため触媒担持
層中の金属などと容易に反応し、サルフェートとして触
媒担持層に吸着されやすい。そのため触媒担持層にはサ
ルフェートが徐々に蓄積され、それがある時吐き出され
るため、排ガス中のパティキュレート量が急激に増大す
るという問題がある。これは、SO2 はパティキュレー
トとして測定されないが、サルフェートはパティキュレ
ートとして測定されるためである。特にDEにおいては
排ガス中に酸素ガスが多く存在し、SO2 の酸化反応が
生じやすい。However, open type S
In the OF decomposition catalyst, the SO in the exhaust gas is particularly high temperature range.
TwoEven oxidized to SOThreeAnd SOFour(SOx) Generates
You. This SOxHas extremely high reaction activity, so catalyst support
It easily reacts with the metals in the layer and acts as a sulfate.
It is easily adsorbed by the medium carrying layer. Therefore, the catalyst support layer is
Luffate slowly accumulates and is exhaled when it is
Therefore, the amount of particulates in the exhaust gas increases rapidly.
There is a problem that This is SOTwoIs a particulate
Sulfate is a particulate
This is because it is measured as a sheet. Especially in DE
Exhaust gas contains a large amount of oxygen gas, and SOTwoThe oxidation reaction of
It is easy to occur.
【0006】さらにオープン型SOF分解触媒では、触
媒金属がDE排ガス中に多量に含まれる硫黄の被毒を受
け、触媒金属の触媒活性が低下することが知られてい
る。すなわち、燃料中の硫黄から生成するSO2 のさら
なる酸化により生成したSOxが、触媒担持層のアルミ
ナと反応してサルフェートである硫酸アルミニウム(A
l2 (SO4 )3 )が形成され、これが触媒金属を覆う
ために触媒活性が低下する。[0006] Further, in the open type SOF decomposition catalyst, it is known that the catalytic metal is poisoned by sulfur contained in a large amount in DE exhaust gas, and the catalytic activity of the catalytic metal is reduced. That is, SO x produced by further oxidation of SO 2 produced from sulfur in the fuel reacts with alumina of the catalyst supporting layer to form sulfate aluminum sulfate (A
l 2 (SO 4 ) 3 ) is formed, which covers the catalytic metal and reduces the catalytic activity.
【0007】本発明はこのような事情に鑑みてなされた
ものであり、触媒担持層上でのサルフェートの生成を一
層抑制するとともに、生成したサルフェートが触媒担持
層に蓄積されるのを抑制することを目的とする。The present invention has been made in view of such circumstances, and further suppresses the formation of sulfate on the catalyst-supporting layer and suppresses the accumulation of the generated sulfate on the catalyst-supporting layer. With the goal.
【0008】[0008]
【課題を解決するための手段】上記課題を解決する本発
明のディーゼル排ガス用酸化触媒の特徴は、担体基材
と、担体基材の表面に形成された触媒担持層と、触媒担
持層に担持された触媒金属と、からなるディーゼル排ガ
ス用酸化触媒において、触媒担持層にはCa、Ag、B
a、K、La、Pb、Tl及びYから選ばれる金属の硫
酸塩を含むことにある。The features of the oxidation catalyst for diesel exhaust gas of the present invention for solving the above-mentioned problems are that a carrier substrate, a catalyst supporting layer formed on the surface of the carrier substrate, and a catalyst supporting layer are supported. In the oxidation catalyst for diesel exhaust gas, the catalyst supporting layer comprises Ca, Ag, and B.
It is to contain a sulfate of a metal selected from a, K, La, Pb, Tl and Y.
【0009】[0009]
【発明の実施の形態】担体基材としては、コーディエラ
イトなどの耐熱性無機物や金属製のメタル担体が用いら
れ、その形状はハニカム型、ペレット型など従来と同様
とすることができる。触媒担持層にはCa、Ag、B
a、K、La、Pb、Tl及びYから選ばれる金属の硫
酸塩が含まれている。つまり、CaSO4 、Ag2 SO
4 、BaSO4、K2 SO4 、La2 (SO4 )3 、P
bSO4 、Tl2 SO4 及びY2 (SO 4 )3 から選ば
れる硫酸塩が含まれ、これらのうち一種でもよいし、複
数種類併用することもできる。BEST MODE FOR CARRYING OUT THE INVENTION As a carrier substrate, cordiera
If a heat-resistant inorganic substance such as iron or a metal carrier made of metal is used
The shape is the same as conventional ones such as honeycomb type and pellet type.
It can be. Ca, Ag, B are contained in the catalyst supporting layer
sulfur of a metal selected from a, K, La, Pb, Tl and Y
Contains acid salt. That is, CaSOFour, AgTwoSO
Four, BaSOFour, KTwoSOFour, LaTwo(SOFour)Three, P
bSOFour, TlTwoSOFourAnd YTwo(SO Four)ThreeChoose from
Sulphate, which may be one or more of these.
It is also possible to use several types in combination.
【0010】触媒担持層の他の材質としては、アルミナ
(Al2 O3 )、シリカ(SiO2)、シリカ−アルミ
ナ、チタニア(TiO2 )、ジルコニア(ZrO2 )、
チタン酸カリウム酸化物、ゼオライトあるいはこれらの
複合酸化物などを用いることができる。本発明の酸化触
媒では、触媒担持層に上記硫酸塩を含むことにより、触
媒担持層上でのサルフェートの新たな生成が抑制される
とともに、サルフェートの吸着・蓄積も抑制され、蓄積
されたサルフェートの吐き出しが防止される。上記硫酸
塩によりこのような作用が奏される理由は明らかではな
いが、以下のように推察される。Other materials for the catalyst supporting layer include alumina (Al 2 O 3 ), silica (SiO 2 ), silica-alumina, titania (TiO 2 ), zirconia (ZrO 2 ),
Potassium titanate oxide, zeolite, or composite oxides thereof can be used. In the oxidation catalyst of the present invention, by containing the above-mentioned sulfate in the catalyst-supporting layer, new generation of sulfate on the catalyst-supporting layer is suppressed, and adsorption / accumulation of sulfate is also suppressed. Exhalation is prevented. Although the reason why the above-mentioned sulfate exhibits such an effect is not clear, it is presumed as follows.
【0011】すなわち300℃以上の高温にて、SO2
は酸素の存在下で触媒金属により酸化されてSOx が生
成し、水分の存在下で触媒担持層の構成成分であるA
l、Si、Ti、Zrなどの金属などと反応してサルフ
ェートを生成しようとする。ところが触媒担持層中には
既に上記硫酸塩が存在している。したがって生成したS
Ox が電気的反発によって触媒担持層に近接しにくくな
り、かつ触媒担持層にはSOx が新たにサルフェートと
して吸着される余地も少ない。その結果サルフェートの
生成が防止され、吸着・蓄積も防止されると考えられ
る。That is, at a high temperature of 300 ° C. or higher, SO 2
Is oxidized by the catalytic metal in the presence of oxygen to produce SO x, and is a constituent component of the catalyst supporting layer in the presence of water.
Attempts to generate a sulfate by reacting with a metal such as l, Si, Ti or Zr. However, the sulfate is already present in the catalyst supporting layer. Therefore, the generated S
O x is less likely close to the catalyst supporting layer by electrical repulsion, and the catalyst carrying layer less room for SO x is newly adsorbed as sulfates. As a result, it is considered that the formation of sulfate is prevented, and the adsorption / accumulation is also prevented.
【0012】また上記硫酸塩は0℃の水100g中への
溶解度が7g以下と低い。そのため、排ガス中には数%
から10%の水分が含まれているが、上記硫酸塩はこの
水分に溶解することが少ない。したがって硫酸塩が移動
して凝集したりすることがなく、排ガス中でも安定な触
媒となる。硫酸塩として硫酸アルミニウム、硫酸銅など
水への溶解度が大きなものを用いた場合には、排ガス中
の水分に溶解し、容易に移動して触媒の下流に凝集した
り外部に流出してしまうため好ましくない。したがって
本発明に用いられる硫酸塩は上記7種類の金属の硫酸塩
に限られ、中でも特に溶解度が低く毒性の小さいCa、
Ba、La、Yの硫酸塩が特に好ましい。The above-mentioned sulfate has a low solubility of 7 g or less in 100 g of water at 0 ° C. Therefore, a few% in the exhaust gas
To 10% of water is contained, but the sulfate is less soluble in this water. Therefore, the sulfate does not move and aggregate, and the catalyst becomes stable even in the exhaust gas. When a sulfate having a high solubility in water such as aluminum sulfate or copper sulfate is used, it is dissolved in the water in the exhaust gas and easily moves to aggregate downstream of the catalyst or flow out to the outside. Not preferable. Therefore, the sulfates used in the present invention are limited to the above 7 types of metal sulfates, and among them, Ca, which has a low solubility and low toxicity,
Ba, La and Y sulfates are particularly preferred.
【0013】触媒担持層中の上記硫酸塩の含有量として
は、70重量%の範囲が好ましい。70重量%より少な
いと上記作用が奏されずサルフェートの新たな生成や蓄
積・吐き出しが生じるようになる。また担体基材にコー
トするために、SiO2 ゾルのような無機物のゾルを添
加するが、これらのゾルはコート層の剥離を防止するた
めに5〜30重量%添加する必要がある。The content of the above-mentioned sulfate in the catalyst supporting layer is preferably in the range of 70% by weight. If it is less than 70% by weight, the above effect is not exerted, and new generation, accumulation and discharge of sulfate occur. Further, in order to coat the carrier substrate, an inorganic sol such as SiO 2 sol is added, but these sol must be added in an amount of 5 to 30% by weight in order to prevent peeling of the coating layer.
【0014】触媒担持層に担持される触媒金属として
は、白金(Pt)、パラジウム(Pd)、ロジウム(R
h)、銀(Ag)などの貴金属の他、鉄(Fe)、ニッ
ケル(Ni)、クロム(Cr)、マンガン(Mn)、コ
バルト(Co)、銅(Cu)などの卑金属も用いられ、
目的とする酸化力に応じて選択して用いることができ
る。この触媒金属の担持量としては、触媒体積1リット
ルに対して0.1〜10g程度が適当である。担持量が
これより少ないとHC及びSOFの酸化力が不十分とな
り、これより多く担持しても効果が飽和するとともにコ
スト面での不具合が発生する場合がある。The catalyst metal supported on the catalyst supporting layer includes platinum (Pt), palladium (Pd) and rhodium (R).
h), noble metals such as silver (Ag), and also base metals such as iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), cobalt (Co), and copper (Cu).
It can be selected and used according to the desired oxidizing power. The amount of the catalyst metal supported is appropriately about 0.1 to 10 g per 1 liter of the catalyst volume. If the supported amount is smaller than this, the oxidizing power of HC and SOF becomes insufficient, and if the supported amount is larger than this, the effect is saturated and a problem in terms of cost may occur.
【0015】[0015]
【実施例】以下、実施例により本発明を具体的に説明す
る。 (実施例1)硫酸バリウム(BaSO4 )粉末100重
量部と、シリカを40重量%含むシリカゾル25重量部
と、水95重量部とを混合し、ウォッシュコート用スラ
リーを調製した。The present invention will be described below in detail with reference to examples. Example 1 100 parts by weight of barium sulfate (BaSO 4 ) powder, 25 parts by weight of silica sol containing 40% by weight of silica, and 95 parts by weight of water were mixed to prepare a slurry for washcoat.
【0016】容積1.7Lのコーディエライト製ハニカ
ム担体を用意し、このハニカム担体を上記スラリーに浸
漬後引き上げて余分なスラリーを吹き払い、120℃で
6時間乾燥後、500℃で3時間焼成して触媒担持層を
形成した。触媒担持層のコート量は170gであり、ハ
ニカム担体1L当たり100gである。次に、触媒担持
層をもつハニカム担体を白金テトラアンミンヒドロキシ
ド水溶液に浸漬し、引き上げて余分な水滴を吹き払った
後、250℃で1時間乾燥して触媒担持層にPtを担持
した。Ptの担持量はハニカム担体1L当たり1.5g
である。これにより実施例1の酸化触媒が調製された。A cordierite honeycomb carrier having a volume of 1.7 L was prepared, and the honeycomb carrier was immersed in the above slurry, pulled up to blow away excess slurry, dried at 120 ° C. for 6 hours, and fired at 500 ° C. for 3 hours. Then, a catalyst supporting layer was formed. The coating amount of the catalyst supporting layer is 170 g, which is 100 g per 1 L of the honeycomb carrier. Next, the honeycomb carrier having the catalyst supporting layer was immersed in an aqueous solution of platinum tetraammine hydroxide, pulled up to blow off excess water droplets, and then dried at 250 ° C. for 1 hour to support Pt on the catalyst supporting layer. The amount of Pt carried is 1.5 g per liter of honeycomb carrier
It is. As a result, the oxidation catalyst of Example 1 was prepared.
【0017】(比較例1)γ−アルミナ粉末100重量
部と、アルミナを20重量%含むアルミナゾル50重量
部と、水70重量部とからなるスラリーを用いたこと以
外は実施例1と同様にして触媒担持層を形成し、Ptを
同量担持して比較例1の酸化触媒を調製した。Comparative Example 1 The same procedure as in Example 1 was carried out except that a slurry consisting of 100 parts by weight of γ-alumina powder, 50 parts by weight of alumina sol containing 20% by weight of alumina, and 70 parts by weight of water was used. A catalyst supporting layer was formed and Pt was supported in the same amount to prepare an oxidation catalyst of Comparative Example 1.
【0018】(比較例2)シリカ粉末100重量部と、
シリカを40重量%含むシリカゾル50重量部と、水9
0重量部とからなるスラリーを用いたこと以外は実施例
1と同様にして触媒担持層を形成し、Ptを同量担持し
て比較例2の酸化触媒を調製した。 (比較例3)硫酸コバルト粉末100重量部と、シリカ
を40重量%含むシリカゾル30重量部と、水94重量
部とからなるスラリーを用いたこと以外は実施例1と同
様にして触媒担持層を形成し、Ptを同量担持して比較
例3の酸化触媒を調製した。Comparative Example 2 100 parts by weight of silica powder,
50 parts by weight of silica sol containing 40% by weight of silica and 9 parts of water
A catalyst supporting layer was formed in the same manner as in Example 1 except that a slurry containing 0 parts by weight was used, and the same amount of Pt was supported to prepare an oxidation catalyst of Comparative Example 2. (Comparative Example 3) A catalyst-supporting layer was prepared in the same manner as in Example 1 except that a slurry composed of 100 parts by weight of cobalt sulfate powder, 30 parts by weight of silica sol containing 40% by weight of silica, and 94 parts by weight of water was used. After being formed, the same amount of Pt was carried to prepare an oxidation catalyst of Comparative Example 3.
【0019】(評価試験)上記のそれぞれの触媒を2.
6LのDEに装着し、エンジンベンチにおける評価を行
った。条件は、エンジン回転数2000rpmにて、触
媒入りガス温度500℃で1時間の前処理を行った。次
に触媒入りガス温度を350℃に下げ、350℃で1時
間保持した後、5分間で450℃まで昇温した。350
℃で保持している途中からサルフェートの生成率をそれ
ぞれの触媒について測定し、温度条件を図1に、結果を
図2に示す。(Evaluation test)
It was mounted on a 6 L DE and evaluated on an engine bench. The conditions were such that the engine rotation speed was 2000 rpm, and the catalyst-containing gas temperature was 500 ° C. for 1 hour of pretreatment. Next, the temperature of the gas containing the catalyst was lowered to 350 ° C., the temperature was maintained at 350 ° C. for 1 hour, and then the temperature was raised to 450 ° C. in 5 minutes. 350
The production rate of sulfate was measured for each catalyst while it was kept at 0 ° C., and the temperature conditions are shown in FIG. 1 and the results are shown in FIG.
【0020】なおサルフェートの生成率は、触媒出ガス
中のSOx 量をSOx 計で測定するとともに触媒入りガ
ス中のSO2 量を測定し、100×SOx /SO2 にて
求めた。図2より、比較例1〜2の酸化触媒では入りガ
ス温度の昇温中にサルフェート生成率が急激に増大し、
比較例1では100%を超えた後急激に低下し、その後
はサルフェート生成率が安定している。このことは、昇
温時までに触媒担持層にサルフェートが蓄積され、それ
が高温となった触媒担持層から吐き出されたことを示し
ている。しかし実施例1の酸化触媒では増大したサルフ
ェート生成率の低下がほとんど認められず、サルフェー
トの吐き出しが生じていないことが明らかであり、硫酸
バリウムを触媒担持層に含むことでサルフェートの吸着
・蓄積が抑制されたことが明らかである。[0020] Note that generation rate of sulfates, the amount of SO x in the catalyst exiting gas was measured SO 2 amount of the catalyst filled in the gas as well as measured by the SO x meter, was determined at 100 × SO x / SO 2. As shown in FIG. 2, in the oxidation catalysts of Comparative Examples 1 and 2, the sulfate production rate rapidly increased during the temperature rise of the incoming gas temperature,
In Comparative Example 1, after exceeding 100%, it rapidly decreased, and thereafter the sulfate production rate was stable. This indicates that the sulfate was accumulated in the catalyst-supporting layer by the time of the temperature rise and was discharged from the catalyst-supporting layer having a high temperature. However, with the oxidation catalyst of Example 1, almost no decrease in the increased rate of sulfate formation was observed, and it is clear that the discharge of sulfate did not occur, and the inclusion of barium sulfate in the catalyst-supporting layer resulted in the adsorption / accumulation of sulfate. It is clearly suppressed.
【0021】一方、比較例3の酸化触媒では、1回目の
評価では実施例1と近い性能を示したが、2回、3回と
同じ評価を繰り返すと、図3に示すようにサルフェート
生成率が増大した。しかし実施例1の酸化触媒では、3
回目の評価でも1回目と同じ結果を示し、性能低下は認
められなかった。また350℃で保持されている間及び
450で保持されている間のサルフェート生成率は、比
較例1〜3の方が実施例1より大きく、実施例1の酸化
触媒は比較例に比べてサルフェートの生成が抑制されて
いることがわかる。On the other hand, the oxidation catalyst of Comparative Example 3 showed a performance close to that of Example 1 in the first evaluation, but when the same evaluation was repeated twice and three times, the sulfate formation rate was as shown in FIG. Has increased. However, with the oxidation catalyst of Example 1, 3
The evaluation of the second time also showed the same result as the first time, and no performance deterioration was observed. Further, the sulfate production rate during holding at 350 ° C. and during holding at 450 was higher in Comparative Examples 1 to 3 than in Example 1, and the oxidation catalyst of Example 1 had a sulfate content higher than that of Comparative Example. It can be seen that the generation of is suppressed.
【0022】(他の実施例)硫酸バリウムの代わりにC
aSO4 、Ag2 SO4 、K2 SO4 、La2 (S
O4 )3 、PbSO4 、Tl2 SO4 及びY2 (S
O4 )3 をそれぞれ100重量部用いたこと以外は実施
例1と同様にして、酸化触媒をそれぞれ調製した。これ
らの酸化触媒について、実施例1及び比較例1〜3と同
様の評価試験を繰り返し行い、3回目の評価における最
大サルフェート生成率を測定した。それぞれの結果を表
1に示す。(Other Examples) C in place of barium sulfate
aSO 4 , Ag 2 SO 4 , K 2 SO 4 , La 2 (S
O 4 ) 3 , PbSO 4 , Tl 2 SO 4 and Y 2 (S
Oxidation catalysts were prepared in the same manner as in Example 1 except that 100 parts by weight of O 4 ) 3 was used. With respect to these oxidation catalysts, the same evaluation test as in Example 1 and Comparative Examples 1 to 3 was repeated, and the maximum sulfate production rate in the third evaluation was measured. Table 1 shows the results.
【0023】[0023]
【表1】 表1より、硫酸バリウム以外の上記硫酸塩を含む酸化触
媒であっても、実施例1と同様に最大サルフェート生成
率が低く、これらの硫酸塩も硫酸バリウムと同様の効果
を奏することがわかる。[Table 1] From Table 1, it can be seen that even with the oxidation catalyst containing the above-mentioned sulfate other than barium sulfate, the maximum sulfate production rate is low as in Example 1, and these sulfates also exhibit the same effect as barium sulfate.
【0024】[0024]
【発明の効果】すなわち本発明の酸化触媒によれば、触
媒担持層上におけるサルフェートの生成が抑制されると
ともに、生成したサルフェートが触媒担持層上に蓄積さ
れるのを防止することができ、サルフェートが大量に吐
き出されるのが防止される。[Effects of the Invention] That is, according to the oxidation catalyst of the present invention, it is possible to suppress the formation of sulfate on the catalyst-supporting layer and to prevent the generated sulfate from accumulating on the catalyst-supporting layer. Is prevented from being exhaled in large quantities.
【図1】実施例における評価試験での入りガス温度条件
を示すグラフである。FIG. 1 is a graph showing incoming gas temperature conditions in an evaluation test in Examples.
【図2】実施例1及び比較例1〜2における評価試験の
結果を示し、試験時間とサルフェート生成率との関係を
示すグラフである。FIG. 2 is a graph showing the results of evaluation tests in Example 1 and Comparative Examples 1 and 2, showing the relationship between test time and sulfate production rate.
【図3】実施例1及び比較例3における評価試験の結果
を示し、試験時間とサルフェート生成率との関係を示す
グラフである。FIG. 3 is a graph showing the results of evaluation tests in Example 1 and Comparative Example 3, showing the relationship between test time and sulfate production rate.
Claims (1)
れた触媒担持層と、該触媒担持層に担持された触媒金属
と、からなるディーゼル排ガス用酸化触媒において、 前記触媒担持層にはCa、Ag、Ba、K、La、P
b、Tl及びYから選ばれる金属の硫酸塩を含むことを
特徴とするディーゼル排ガス用酸化触媒。1. A diesel exhaust gas oxidation catalyst comprising a carrier substrate, a catalyst carrier layer formed on the surface of the carrier substrate, and a catalyst metal supported on the catalyst carrier layer, wherein the catalyst carrier layer Ca, Ag, Ba, K, La, P
An oxidation catalyst for diesel exhaust gas, comprising a sulfate of a metal selected from b, Tl and Y.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8082433A JPH09271674A (en) | 1996-04-04 | 1996-04-04 | Oxidizing catalyst for diesel exhaust gas |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8082433A JPH09271674A (en) | 1996-04-04 | 1996-04-04 | Oxidizing catalyst for diesel exhaust gas |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09271674A true JPH09271674A (en) | 1997-10-21 |
Family
ID=13774436
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8082433A Pending JPH09271674A (en) | 1996-04-04 | 1996-04-04 | Oxidizing catalyst for diesel exhaust gas |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH09271674A (en) |
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