JP3779793B2 - Catalyst and method for purification of combustion exhaust gas containing methane - Google Patents
Catalyst and method for purification of combustion exhaust gas containing methane Download PDFInfo
- Publication number
- JP3779793B2 JP3779793B2 JP13205097A JP13205097A JP3779793B2 JP 3779793 B2 JP3779793 B2 JP 3779793B2 JP 13205097 A JP13205097 A JP 13205097A JP 13205097 A JP13205097 A JP 13205097A JP 3779793 B2 JP3779793 B2 JP 3779793B2
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- palladium
- alumina
- exhaust gas
- rhodium
- 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.)
- Expired - Fee Related
Links
Description
【０００１】
【発明の属する技術分野】
本発明は、メタンを含有し酸素を還元性物質の完全酸化に必要な量よりも過剰に含む燃焼排ガス中の炭化水素の浄化触媒および浄化方法、特に天然ガスの燃焼排ガス等の炭素数換算でメタンが炭化水素全体の６０％以上を占め、かつメタン換算の炭化水素濃度が体積基準で５０００ppm以下である燃焼排ガス中の炭化水素の浄化用触媒および浄化方法に関する。
【０００２】
【従来の技術】
従来より排ガス中の炭化水素の酸化除去触媒として、白金やパラジウム等の白金族金属を担持した触媒が高い性能を示すことが知られている。たとえば、特開昭５１−１０６６９１号公報にはアルミナ担体に白金とパラジウムを担持した排ガス浄化用触媒が開示されている。しかしこれらの触媒を用いても、天然ガスの燃焼排ガスのようにメタンが炭化水素の主成分である場合には、メタンの化学的安定性が高いために十分な浄化率が得られないという問題がある。さらに排ガス中には通常硫黄酸化物などの阻害物質が共存し、活性が経時的に著しく劣化することが避けられない。山本らは、平成８年度触媒研究発表会講演予稿集(平成８年９月１３日発行)においてアルミナに白金及びパラジウムを担持した触媒を用いた都市ガス燃料の排ガス中の炭化水素の酸化除去の結果を報告しているが、白金とパラジウムの両方を担持した触媒の炭化水素除去率は、併せて示されている、金属量として同量の白金担持アルミナ触媒を用いた場合の炭化水素除去率と、パラジウム担持アルミナ触媒の炭化水素除去率の和とほぼ一致しており、白金とパラジウムの両方を担持したことによる協同的な効果は認められないうえ、１００時間程度の間に顕著な活性の低下が見られる。このように従来技術の問題点は、メタンに対して高い浄化率が得られないこと、さらに硫黄酸化物などの阻害物質が共存するような条件で大きな浄化率の低下が起こることである。
【０００３】
【発明が解決しようとする課題】
本発明は、かかる状況に鑑みて行われたものであって、その目的とするところは、全炭化水素に占めるメタンの割合が高い排ガスに対しても高い浄化率を持ち、硫黄酸化物などの阻害物質の共存下でも長期にわたって安定した性能を示す、メタンを含有し酸素を還元性物質の完全酸化に必要な量よりも過剰に含む燃焼排ガス中の炭化水素浄化用触媒および方法を提供することにある。
【０００４】
【課題を解決するための手段】
発明者らは鋭意検討を重ねた結果、パラジウム触媒を用いた炭化水素の酸化においては、パラジウムの表面積を高く保つことが重要であること、さらに、アルミナにロジウムとパラジウムを同時に担持するか、またはロジウムをあらかじめアルミナに担持した後、パラジウムを担持することによって長期にわたってパラジウムの表面積を高く保つことができることを発見した。さらにこのようにして調製されたパラジウム−ロジウム／アルミナ触媒が、硫黄酸化物による活性阻害に対して高い抵抗性を持つことも見出した。
【０００５】
本発明はかかる知見に基づきなされたもので、本発明の炭化水素浄化用触媒はアルミナにパラジウム及びロジウムを担持してなることを特徴とする。また本発明の炭化水素浄化方法はアルミナにパラジウム及びロジウムを担持してなる触媒を用いることを特徴とする。
【０００６】
アルミナにパラジウムや白金、ロジウム等を担持した触媒は、いわゆる三元触媒として広く知られているが、これは燃料に対して当量の空気をもって燃焼させるいわゆる理論空燃比の排ガスに適用されるものであり、本発明が対象とする、いわゆる希薄燃焼排ガス、すなわち酸素を還元性物質の完全酸化に必要な量よりも過剰に含む排ガスの条件とは大きく異なる。そして、いわゆる三元触媒が、希薄燃焼排ガスの条件ではメタンの除去ができないことは、田畑らによる日本化学会誌１９９５年３号２２５頁の報告に示されるように公知である。
【０００７】
また、三元触媒の場合においては、特開昭５８−１４６４４１号公報や特開平３−６８４４８号公報に開示されるようにパラジウムと白金あるいはロジウムは相互作用しないように別々の層に担持することがよいとされている。本発明の特徴はこのような三元触媒における従来の方法に反して、アルミナにパラジウム及びロジウムを共に担持してなる触媒を用いることにある。
【０００８】
本発明の触媒は、市販の活性アルミナに、ロジウムおよびパラジウムをそれら金属のイオンを含む溶液を含浸することによって得られる。アルミナの比表面積はパラジウムを高分散状態に保つために重要であり、２０ｍ2／ｇ以上であることが望ましい。金属イオンを含む溶液としては、それら金属の硝酸塩やアンミン錯体などの溶液を用いればよい。溶媒は水溶液が好ましいが、アセトンやエタノールなどの水溶性の有機溶媒を加えた混合溶媒としてもよい。
【０００９】
パラジウムの担持量は、少なすぎると触媒活性が低く、また高すぎるとパラジウムの粒径が大きくなりパラジウムが有効に使われなくなるので、触媒重量に対して０.２乃至２０％、より好ましくは０.５乃至１０％がよい。ロジウムの担持量は少なすぎれば効果がなく、多すぎても活性を阻害するので、触媒重量に対して０.１乃至５％、より好ましくは０.２乃至２％がよい。
【００１０】
焼成温度は高すぎると、担持された貴金属の粒成長が進み、また低すぎても触媒の使用中に貴金属の粒成長が進むため、安定して高い活性をうるためには、４５０℃から６５０℃、好ましくは５００℃から６００℃の範囲とするのがよい。本発明の触媒は、ペレット状に成型したり、耐火性ハニカム上にウオッシュコートしたりして用いてもよい。
【００１１】
本発明のメタン含有排ガス中の炭化水素浄化方法は、上記で得られた触媒を用いることを特徴とする。触媒量は、少なすぎると有効な浄化率が得られないので、ガス時間当たり空間速度(ＧＨＳＶ)で２０００００ｈ-1以下で使用するのが望ましく、圧力損失を大きくしないためには５０００h-1以上で使用するのが望ましい。また処理ガス中の酸素濃度が極端に低い場合には、反応速度が低下するので、体積基準の酸素濃度として、２％以上であり、かつガス中の炭化水素などの還元性成分の酸化当量の５倍以上の酸素が存在することが好ましい。このとき排ガス中の酸素濃度が十分高くないときには、あらかじめ所要の量の空気を混ぜてもよい。
【００１２】
本発明のメタン含有排ガス中の炭化水素浄化触媒は、高い活性を有するが、あまりに低温では活性が下がり、所望の転化率が得られない恐れがあるので、触媒層温度が３５０℃以上に保たれるようにするのが好ましい。また、炭化水素の濃度が著しく高いときには、触媒層で急激な反応が起こって、触媒の耐久性に影響を及ぼすので、触媒層での温度上昇が１５０℃以下となる条件で用いるのが好ましい。
【００１３】
【実施例】
以下、実施例に基づき、本発明をより詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
実施例 １
住友化学工業製ＮＫ１２４アルミナを空気中１０００℃で２時間焼成した。この５gを、パラジウムとして１０％を含有する硝酸パラジウム水溶液２．５mlとロジウムとして５％を含有する硝酸ロジウム水溶液１mlを純水を加えて混合して２０mlとした溶液に０℃で一晩含浸した。これを乾燥後空気中５５０℃で２時間焼成して５％Ｐd−１％Ｒh／アルミナ触媒(１)を得た。
【００１４】
実施例 ２
実施例１と同じ焼成アルミナを５gとり、ロジウムとして５％を含有する硝酸ロジウム水溶液１mlを純水を加えて混合して２０mlとした溶液に０℃で一晩含浸した。これを乾燥後空気中５５０℃で２時間焼成して１％Ｒh／アルミナ触媒を得た。これにパラジウムとして１０％を含有する硝酸パラジウム水溶液２.５mlに水を加えて２０mlとした溶液に０℃で一晩含浸した。これを乾燥後空気中５５０℃で２時間焼成して５％Ｐd−１％Ｒh／アルミナ触媒(２)を得た。
【００１５】
比較例 １
実施例１と同じ焼成アルミナを５gとり、これにパラジウムとして１０％を含有する硝酸パラジウム水溶液２.５mlに水を加えて２０mlとした溶液に０℃で一晩含浸した。これを乾燥後空気中５５０℃で２時間焼成して５％Ｐd／アルミナ触媒を得た。
【００１６】
比較例 ２
実施例１と同じ焼成アルミナを５gとり、パラジウムとして１０％を含有する硝酸パラジウム水溶液２.５mlとジニトロジアンミン白金０.０８３gを６９％硝酸１mlに加熱溶解した液と純水を加えて２０mlとした溶液に０℃で一晩含浸した。これを乾燥後空気中５５０℃で２時間焼成して５％Ｐd−１％Ｐt／アルミナ触媒を得た。
【００１７】
実施例 ３ ( 触媒活性試験 )
実施例１から２と比較例１から２の触媒を打錠成型して１mlとり、メタン１０００ppm、酸素１０％、二酸化炭素６％、水蒸気１０％からなる組成のガスをＧＨＳＶ(ガス時間当たり空間速度)４００００h-1の条件にて流通して触媒活性試験を行った。反応層前後のガス組成は水素炎イオン化検知器を有するガスクロマトグラフにより行った。
初期活性と、５５０℃にて反応ガスを２時間流通した後の活性とをメタン転化率(％)として表１に示す。
【００１８】
【表１】
明らかに、Ｒhを添加した実施例１および２の触媒はＰtを添加した比較例１の触媒や、比較例２のＰdのみの触媒に比べて高い活性を示し、高温で処理しても活性の低下の度合いは小さい。またＲhを先に担持してからＰdを担持しても同時に担持したのと同じ効果が得られることが分かる。
【００２０】
実施例 ４ ( 耐久性評価試験 )
実施例１から２と比較例１から２の触媒を打錠成型して１mlとり、メタン１０００ppm、酸素１０％、二酸化炭素６％、水蒸気１０％と二酸化硫黄８ppmからなる組成のガスをＧＨＳＶ(ガス時間当たり空間速度)４００００h-1の条件にて流通し触媒層温度５００℃にて耐久性評価試験を行った。反応層前後のガス組成は水素炎イオン化検知器を有するガスクロマトグラフにより行った。二酸化硫黄含有ガスの流通開始後の３、１０、１８時間後のメタン転化率(％)を表２に示す。
【００２１】
【表２】
あきらかに、実施例１の触媒は、触媒活性を低下させる効果の高い二酸化硫黄の共存下でも安定した活性を示すことが分かる。
【００２３】
【発明の効果】
本発明の触媒は、長期にわたってパラジウムの表面積を高く保つことができ、また硫黄酸化物による活性阻害に対して高い抵抗性を持つために、従来の触媒では困難であった、メタンを多く含有する排ガスについても高い浄化率が得られ、また硫黄酸化物などの阻害物質が共存するような条件でも高い浄化性能が長期にわたって維持される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a purification catalyst and a purification method for hydrocarbons in combustion exhaust gas containing methane and containing oxygen in excess of the amount necessary for complete oxidation of the reducing substance, particularly in terms of carbon number in natural gas combustion exhaust gas and the like. The present invention relates to a catalyst and a purification method for purifying hydrocarbons in combustion exhaust gas in which methane accounts for 60% or more of the total hydrocarbons, and the methane equivalent hydrocarbon concentration is 5000 ppm or less on a volume basis.
[0002]
[Prior art]
Conventionally, it is known that a catalyst supporting a platinum group metal such as platinum or palladium exhibits high performance as an oxidation removal catalyst for hydrocarbons in exhaust gas. For example, Japanese Patent Application Laid-Open No. 51-106691 discloses an exhaust gas purifying catalyst in which platinum and palladium are supported on an alumina carrier. However, even when these catalysts are used, when methane is the main component of hydrocarbons, such as natural gas combustion exhaust gas, the chemical stability of methane is high, so a sufficient purification rate cannot be obtained. There is. In addition, it is inevitable that inhibitors such as sulfur oxides coexist in the exhaust gas and the activity deteriorates with time. Yamamoto et al., Proceedings of the 1996 Catalyst Research Presentation (issued September 13, 1996) oxidative removal of hydrocarbons in the exhaust gas of city gas fuel using a catalyst with platinum and palladium supported on alumina. Although the results are reported, the hydrocarbon removal rate of the catalyst supporting both platinum and palladium is shown together, the hydrocarbon removal rate when using the same amount of platinum-supported alumina catalyst as the amount of metal. And the sum of the hydrocarbon removal rates of the palladium-carrying alumina catalyst, and there is no cooperative effect due to the loading of both platinum and palladium. There is a decline. Thus, the problems of the prior art are that a high purification rate cannot be obtained with respect to methane, and that a large reduction in the purification rate occurs under the conditions where inhibitors such as sulfur oxide coexist.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of such a situation, and the object of the present invention is to have a high purification rate even for exhaust gas in which the proportion of methane in all hydrocarbons is high, such as sulfur oxides. To provide a catalyst and a method for purifying hydrocarbons in combustion exhaust gas containing methane and containing oxygen in excess of the amount necessary for complete oxidation of a reducing substance, which shows stable performance over a long period of time even in the presence of an inhibitor. It is in.
[0004]
[Means for Solving the Problems]
As a result of intensive studies, the inventors have found that it is important to keep the surface area of palladium high in the oxidation of hydrocarbons using a palladium catalyst, and further, rhodium and palladium are simultaneously supported on alumina, or It was discovered that the surface area of palladium can be kept high over a long period of time by supporting rhodium on alumina in advance and then supporting palladium. Furthermore, it has also been found that the palladium-rhodium / alumina catalyst thus prepared has high resistance to activity inhibition by sulfur oxides.
[0005]
The present invention has been made on the basis of such findings, and the hydrocarbon purifying catalyst of the present invention is characterized in that palladium and rhodium are supported on alumina. The hydrocarbon purification method of the present invention is characterized by using a catalyst obtained by supporting palladium and rhodium on alumina.
[0006]
A catalyst in which palladium, platinum, rhodium or the like is supported on alumina is widely known as a so-called three-way catalyst, which is applied to a so-called stoichiometric exhaust gas that is burned with an equivalent amount of air to fuel. The conditions of so-called lean combustion exhaust gas, that is, the exhaust gas containing oxygen in excess of the amount necessary for complete oxidation of the reducing substance, which is the subject of the present invention, are greatly different. It is well known that a so-called three-way catalyst cannot remove methane under the condition of lean combustion exhaust gas, as shown in a report on page 225, No. 3, 1995 by the Chemical Society of Japan by Tabata et al.
[0007]
In the case of a three-way catalyst, palladium and platinum or rhodium should be supported in separate layers so as not to interact as disclosed in Japanese Patent Application Laid-Open Nos. 58-146441 and 3-68448. It is said that it is good. The feature of the present invention resides in the use of a catalyst in which palladium and rhodium are supported on alumina, contrary to the conventional method of such a three-way catalyst.
[0008]
The catalyst of the present invention can be obtained by impregnating commercially available activated alumina with a solution containing rhodium and palladium containing ions of these metals. The specific surface area of alumina is important for maintaining palladium in a highly dispersed state, and is desirably 20 m 2 / g or more. As the solution containing metal ions, a solution of nitrate or ammine complex of these metals may be used. The solvent is preferably an aqueous solution, but may be a mixed solvent to which a water-soluble organic solvent such as acetone or ethanol is added.
[0009]
If the supported amount of palladium is too small, the catalyst activity is low, and if it is too high, the particle size of palladium becomes large and palladium cannot be used effectively, so 0.2 to 20%, more preferably 0, of the catalyst weight. .5 to 10% is good. If the supported amount of rhodium is too small, there is no effect, and if it is too large, the activity is inhibited.
[0010]
If the calcination temperature is too high, grain growth of the supported noble metal proceeds, and if it is too low, grain growth of the noble metal proceeds during use of the catalyst. C., preferably 500.degree. C. to 600.degree. C. The catalyst of the present invention may be used in the form of pellets or wash coated on a refractory honeycomb.
[0011]
The hydrocarbon purification method in the methane-containing exhaust gas of the present invention is characterized by using the catalyst obtained above. If the catalyst amount is too small, an effective purification rate cannot be obtained, so it is desirable to use it at a gas hourly space velocity (GHSV) of 200000 h -1 or less, and 5000 h -1 or more in order not to increase the pressure loss. It is desirable to use it. In addition, when the oxygen concentration in the processing gas is extremely low, the reaction rate decreases, so that the oxygen concentration on a volume basis is 2% or more, and the oxidation equivalent of reducing components such as hydrocarbons in the gas. It is preferable that 5 times or more oxygen is present. At this time, if the oxygen concentration in the exhaust gas is not sufficiently high, a required amount of air may be mixed in advance.
[0012]
The hydrocarbon purification catalyst in the methane-containing exhaust gas of the present invention has a high activity, but the activity decreases at a too low temperature and the desired conversion rate may not be obtained. Therefore, the catalyst layer temperature is maintained at 350 ° C. or higher. It is preferable to make it. Further, when the hydrocarbon concentration is extremely high, a rapid reaction occurs in the catalyst layer, which affects the durability of the catalyst. Therefore, it is preferably used under the condition that the temperature rise in the catalyst layer is 150 ° C. or less.
[0013]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.
Example 1
NK124 alumina manufactured by Sumitomo Chemical was calcined in air at 1000 ° C. for 2 hours. 5 g of this solution was impregnated overnight at 0 ° C. into a solution of 2.5 ml of palladium nitrate containing 10% palladium and 1 ml of rhodium nitrate containing 5% rhodium by adding pure water to 20 ml. . This was dried and calcined in air at 550 ° C. for 2 hours to obtain a 5% Pd-1% Rh / alumina catalyst (1).
[0014]
Example 2
5 g of the same calcined alumina as in Example 1 was taken, and 1 ml of a rhodium nitrate aqueous solution containing 5% as rhodium was mixed with pure water to make 20 ml, and impregnated at 0 ° C. overnight. This was dried and calcined in air at 550 ° C. for 2 hours to obtain a 1% Rh / alumina catalyst. Water was added to 2.5 ml of an aqueous palladium nitrate solution containing 10% palladium as a solution to make 20 ml. This was dried and then calcined in air at 550 ° C. for 2 hours to obtain 5% Pd-1% Rh / alumina catalyst (2).
[0015]
Comparative example 1
5 g of the same calcined alumina as in Example 1 was taken, and this was impregnated overnight at 0 ° C. with a solution of 2.5 ml of an aqueous palladium nitrate solution containing 10% palladium to make 20 ml. This was dried and calcined in air at 550 ° C. for 2 hours to obtain a 5% Pd / alumina catalyst.
[0016]
Comparative example 2
5 g of the same calcined alumina as in Example 1 was taken, and 2.5 ml of a palladium nitrate aqueous solution containing 10% of palladium and 0.083 g of dinitrodiammine platinum dissolved in 1 ml of 69% nitric acid and pure water were added to make 20 ml. The solution was impregnated at 0 ° C. overnight. This was dried and calcined in air at 550 ° C. for 2 hours to obtain a 5% Pd-1% Pt / alumina catalyst.
[0017]
Example 3 ( Catalytic activity test )
1 ml of the catalysts of Examples 1 and 2 and Comparative Examples 1 and 2 are tablet-molded, and 1 ml of methane is obtained. The catalyst activity test was conducted under the condition of 40000 h -1 . The gas composition before and after the reaction layer was determined by a gas chromatograph having a flame ionization detector.
The initial activity and the activity after flowing the reaction gas at 550 ° C. for 2 hours are shown in Table 1 as methane conversion (%).
[0018]
[Table 1]
Apparently, the catalysts of Examples 1 and 2 to which Rh was added showed higher activity than the catalyst of Comparative Example 1 to which Pt was added and the catalyst of only Pd of Comparative Example 2, and were active even when treated at high temperatures. The degree of decline is small. It can also be seen that the same effect can be obtained even if Pd is carried after carrying Rh first.
[0020]
Example 4 ( Durability evaluation test )
1 ml of the catalysts of Examples 1 and 2 and Comparative Examples 1 and 2 are tablet-molded, and 1 ml is taken. A gas having a composition of 1000 ppm methane, 10% oxygen, 6% carbon dioxide, 10% water vapor and 8 ppm sulfur dioxide is added to GHSV (gas Durability evaluation tests were conducted at a catalyst layer temperature of 500 ° C. under conditions of 40000 h −1 (space velocity per hour). The gas composition before and after the reaction layer was determined by a gas chromatograph having a flame ionization detector. Table 2 shows the methane conversion (%) after 3, 10, and 18 hours after the start of the flow of the sulfur dioxide-containing gas.
[0021]
[Table 2]
Apparently, it can be seen that the catalyst of Example 1 exhibits stable activity even in the presence of sulfur dioxide, which is highly effective in reducing the catalytic activity.
[0023]
【The invention's effect】
The catalyst of the present invention can keep the surface area of palladium high over a long period of time, and has high resistance to activity inhibition by sulfur oxides. Therefore, the catalyst of the present invention contains a large amount of methane, which has been difficult with conventional catalysts. A high purification rate is also obtained for exhaust gas, and high purification performance is maintained over a long period of time even under conditions where inhibitors such as sulfur oxides coexist.
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13205097A JP3779793B2 (en) | 1997-05-22 | 1997-05-22 | Catalyst and method for purification of combustion exhaust gas containing methane |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13205097A JP3779793B2 (en) | 1997-05-22 | 1997-05-22 | Catalyst and method for purification of combustion exhaust gas containing methane |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10314591A JPH10314591A (en) | 1998-12-02 |
| JP3779793B2 true JP3779793B2 (en) | 2006-05-31 |
Family
ID=15072359
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13205097A Expired - Fee Related JP3779793B2 (en) | 1997-05-22 | 1997-05-22 | Catalyst and method for purification of combustion exhaust gas containing methane |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3779793B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4734806B2 (en) * | 2000-09-20 | 2011-07-27 | トヨタ自動車株式会社 | Exhaust gas purification catalyst |
| CN113042038A (en) * | 2021-03-24 | 2021-06-29 | 中国科学院生态环境研究中心 | Palladium-platinum catalyst, preparation method and application thereof |
-
1997
- 1997-05-22 JP JP13205097A patent/JP3779793B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10314591A (en) | 1998-12-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4096176B2 (en) | Methane-containing exhaust gas purification catalyst and methane-containing exhaust gas purification method | |
| JP4290240B2 (en) | Exhaust gas purification catalyst and exhaust gas purification method | |
| EP1063010B1 (en) | Method for removing methane from exhaust gas | |
| JP4012320B2 (en) | Exhaust gas purification catalyst for lean combustion engine | |
| JP4025945B2 (en) | Methane-containing exhaust gas purification catalyst and methane-containing exhaust gas purification method | |
| US20040254069A1 (en) | Exhaust gas purifying catalyst and exhaust gas purifying system | |
| JP3779793B2 (en) | Catalyst and method for purification of combustion exhaust gas containing methane | |
| JPH06378A (en) | Catalyst for purification of exhaust gas | |
| JP2006026635A (en) | Method of removing nitrogen oxides contained in exhaust gas | |
| JP4568640B2 (en) | Methane-containing exhaust gas purification method, methane-containing exhaust gas purification pretreatment method and three-way catalyst using the same | |
| JP4054933B2 (en) | Methane-containing exhaust gas purification method and methane-containing exhaust gas purification device | |
| JP2002253969A (en) | Catalyst for purifying waste gas and method of purifying waste gas | |
| JP2005081250A (en) | Exhaust emission control device | |
| JP4014266B2 (en) | Purification catalyst for methane-containing exhaust gas and method for purifying methane in exhaust gas using the catalyst | |
| JP4052866B2 (en) | Catalyst for oxidizing hydrocarbons in exhaust gas and method for oxidizing and removing hydrocarbons in exhaust gas | |
| JP4171849B2 (en) | Hydrocarbon-containing exhaust gas purification catalyst and hydrocarbon-containing exhaust gas purification method | |
| JP3981807B2 (en) | Exhaust gas purification catalyst and exhaust gas purification method | |
| JP4171852B2 (en) | Catalyst for purifying hydrocarbons in exhaust gas and method for purifying hydrocarbons in exhaust gas | |
| JP2001190931A (en) | Method for purifying waste gas containing methane | |
| JP2008215359A (en) | Purification method of lean-burn engine exhaust gas | |
| JP2001162171A (en) | Catalyst for purification of exhaust gas and method of purifying exhaust gas | |
| JP2001140632A (en) | Exhaust emission control method and device | |
| JP4822049B2 (en) | Exhaust gas purification catalyst and exhaust gas purification method using the same | |
| JP2971274B2 (en) | Nitrogen oxide removal catalyst and nitrogen oxide removal method using the same | |
| JPH07256101A (en) | Denitration catalyst and denitrating method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050719 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050726 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20060228 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20060303 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120310 Year of fee payment: 6 |
|
| LAPS | Cancellation because of no payment of annual fees |