JPH07289905A - Catalyst and method for removing nitrogen oxide in engine exhaust gas - Google Patents
Catalyst and method for removing nitrogen oxide in engine exhaust gasInfo
- Publication number
- JPH07289905A JPH07289905A JP6114458A JP11445894A JPH07289905A JP H07289905 A JPH07289905 A JP H07289905A JP 6114458 A JP6114458 A JP 6114458A JP 11445894 A JP11445894 A JP 11445894A JP H07289905 A JPH07289905 A JP H07289905A
- Authority
- JP
- Japan
- Prior art keywords
- carrier
- catalyst
- cobalt
- silver
- exhaust gas
- 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.)
- Granted
Links
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 144
- 239000003054 catalyst Substances 0.000 title claims abstract description 62
- 239000007789 gas Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims description 24
- 229910052709 silver Inorganic materials 0.000 claims abstract description 54
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000004332 silver Substances 0.000 claims abstract description 52
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 49
- 239000010941 cobalt Substances 0.000 claims abstract description 49
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 49
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052751 metal Inorganic materials 0.000 claims abstract description 26
- 239000002184 metal Substances 0.000 claims abstract description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000001301 oxygen Substances 0.000 claims abstract description 12
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 12
- 150000001868 cobalt Chemical class 0.000 claims abstract description 3
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 claims abstract description 3
- 238000010304 firing Methods 0.000 claims description 8
- 150000002894 organic compounds Chemical class 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 238000002485 combustion reaction Methods 0.000 abstract description 4
- 150000002739 metals Chemical class 0.000 abstract description 2
- 239000010944 silver (metal) Substances 0.000 description 29
- 230000003197 catalytic effect Effects 0.000 description 15
- 239000003638 chemical reducing agent Substances 0.000 description 15
- 239000003426 co-catalyst Substances 0.000 description 15
- 238000011068 loading method Methods 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 8
- 239000007788 liquid Substances 0.000 description 6
- 229910001961 silver nitrate Inorganic materials 0.000 description 6
- 239000012298 atmosphere Substances 0.000 description 5
- 229940011182 cobalt acetate Drugs 0.000 description 5
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 5
- 239000000446 fuel Substances 0.000 description 5
- 239000001294 propane Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 229910052815 sulfur oxide Inorganic materials 0.000 description 5
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 2
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- -1 nitrogen-containing compound Chemical class 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940044175 cobalt sulfate Drugs 0.000 description 1
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 238000001637 plasma atomic emission spectroscopy Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- CQLFBEKRDQMJLZ-UHFFFAOYSA-M silver acetate Chemical compound [Ag+].CC([O-])=O CQLFBEKRDQMJLZ-UHFFFAOYSA-M 0.000 description 1
- 229940071536 silver acetate Drugs 0.000 description 1
- 229910001923 silver oxide Inorganic materials 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、エンジン排気ガス中の
窒素酸化物の除去触媒と除去方法に関する。詳細には、
特に酸素過剰なディーゼルエンジン排気ガスに含まれる
窒素酸化物と還元剤として軽油などエンジン燃料を共存
させることにより、窒素酸化物を無害の窒素ガスに変換
する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst and method for removing nitrogen oxides in engine exhaust gas. In detail,
Particularly, the present invention relates to a method for converting nitrogen oxides into harmless nitrogen gas by coexisting nitrogen oxides contained in exhaust gas of diesel engine with excess oxygen and engine fuel such as light oil as a reducing agent.
【０００２】[0002]
【従来の技術】エンジン排気ガス中の窒素酸化物、一酸
化炭素および炭化水素はＰｔ、Ｐｄ、Ｒｈなどを担持し
た三元触媒とエンジン燃焼システムとの複合システムに
より除去されている。しかし、ディーゼルエンジン排気
ガスのような酸素過剰雰囲気の排気ガスでは、有効な触
媒がなく、酸素を多く含んでいるエンジン排気ガスの浄
化は行われていない。2. Description of the Related Art Nitrogen oxides, carbon monoxide, and hydrocarbons in engine exhaust gas are removed by a combined system of a three-way catalyst carrying Pt, Pd, Rh, etc. and an engine combustion system. However, in an exhaust gas in an oxygen excess atmosphere such as a diesel engine exhaust gas, there is no effective catalyst, and the engine exhaust gas containing a large amount of oxygen has not been purified.
【０００３】排煙など酸素過剰雰囲気での排気ガス浄化
では、アンモニア等、含窒素化合物を還元剤とした浄化
法が実用化されているが、移動発生源である自動車には
有効な方法ではなく、このような方法は自動車では実用
化されていない。For purification of exhaust gas in an oxygen-rich atmosphere such as flue gas, a purification method using a nitrogen-containing compound such as ammonia as a reducing agent has been put into practical use, but it is not an effective method for automobiles that are mobile sources. However, such a method has not been put to practical use in automobiles.
【０００４】近年、ゼオライトやアルミナ等の金属酸化
物を担体としてＣｏやＡｇなどの各種遷移金属を担持し
た触媒が種々提案されており、このような触媒を用い、
メタン、エチレン、プロピレン、プロパン等の炭化水素
やアルコールのような有機化合物の共存下に窒素酸化物
を除去する方法が報告されている（特開平５−９２１２
４号、特開平５−７６７５７号、特開平４−２７４３１
号、特開平４−３６３１１９号、特開平４−２９７４３
号等）。In recent years, various catalysts have been proposed in which various transition metals such as Co and Ag are supported by using a metal oxide such as zeolite or alumina as a carrier.
A method of removing nitrogen oxides in the presence of hydrocarbons such as methane, ethylene, propylene, propane, and organic compounds such as alcohols has been reported (JP-A-5-9212).
4, JP-A-5-76757, and JP-A-4-27431.
JP-A-4-363119, JP-A-4-29743
Etc.).
【０００５】上記触媒は、窒素酸化物そのものの除去に
対しては有効であるが、実際の排気ガス中には水分と硫
黄酸化物とが共存しており、水分と硫黄酸化物とが共存
すると、初期においては窒素酸化物の除去能は高いが、
徐々に除去能が低下し、５０時間程度経過すると、使用
に耐えなくなってしまうという問題がある。Although the above catalyst is effective for removing nitrogen oxide itself, water and sulfur oxide coexist in the actual exhaust gas, and when water and sulfur oxide coexist. , In the early stage, the ability to remove nitrogen oxides is high,
There is a problem that the removing ability gradually decreases, and after about 50 hours, it becomes unusable.
【０００６】このような実状から、上記触媒について検
討を行ったところ、例えばＣｏを担持した触媒では共存
水分により触媒活性が低下すること、またＡｇを担持し
た触媒では共存水分による影響は低減するが、共存硫黄
酸化物により触媒活性が低下することが判明した。From the above facts, when the above-mentioned catalyst was examined, for example, the catalyst supporting Co had a decrease in catalytic activity due to the coexisting water content, and the catalyst supporting Ag had a reduced effect due to the coexisting water content. It was found that the coexisting sulfur oxides reduce the catalytic activity.
【０００７】[0007]
【発明が解決しようとする課題】本発明の目的は、第一
に、水分および硫黄酸化物の共存下においても触媒活性
の低下がなく、長期に亘る使用が可能なエンジン排気ガ
ス中の窒素酸化物除去触媒を提供することにある。SUMMARY OF THE INVENTION The first object of the present invention is to oxidize nitrogen in engine exhaust gas which does not deteriorate in catalytic activity even in the presence of water and sulfur oxides and can be used for a long period of time. It is to provide a substance removal catalyst.
【０００８】第二に、水分および硫黄酸化物が共存する
条件下においても、過剰な酸素を含むエンジン排気ガス
中の窒素酸化物を有効に除去することができるエンジン
排気ガス中の窒素酸化物除去方法を提供することにあ
る。Secondly, even under the condition that water and sulfur oxide coexist, nitrogen oxide in engine exhaust gas containing excess oxygen can be effectively removed, and nitrogen oxide in engine exhaust gas can be removed. To provide a method.
【０００９】[0009]
【課題を解決するための手段】このような目的は、下記
（１）〜（５）の本発明により達成される。 （１）γ−アルミナを担体とし、この担体に銀およびコ
バルトを担持したエンジン排気ガス中の窒素酸化物除去
触媒。 （２）前記銀を担体に設層したのち、この上にコバルト
を設層して形成されており、コバルトの担持金属全体に
占める割合が金属元素換算量で０．１〜５０重量％であ
る上記（１）のエンジン排気ガス中の窒素酸化物除去触
媒。 （３）銀塩水溶液に担体を浸漬して担体に銀を担持さ
せ、これを焼成したのち、これをコバルト塩水溶液に浸
漬して銀層上にコバルトを担持させ、焼成して得られた
上記（２）のエンジン排気ガス中の窒素酸化物除去触
媒。 （４）上記（１）〜（３）のいずれかのエンジン排気ガ
ス中の窒素酸化物除去触媒を、窒素酸化物（ＮＯx ）に
対する重量比が０．５〜５となる有機化合物の存在下
に、理論燃焼量より過剰量の酸素を含有するエンジン排
気ガスと接触させ、排気ガス中の窒素酸化物を除去する
エンジン排気ガス中の窒素酸化物除去方法。 （５）前記有機化合物が軽油である上記（４）のエンジ
ン排気ガス中の窒素酸化物除去方法。These objects are achieved by the present invention described in (1) to (5) below. (1) A catalyst for removing nitrogen oxides in engine exhaust gas in which γ-alumina is used as a carrier and silver and cobalt are carried on the carrier. (2) The silver is formed on the carrier and then cobalt is formed on the silver, and the ratio of cobalt to the entire supported metal is 0.1 to 50% by weight in terms of metal element. The catalyst for removing nitrogen oxides in engine exhaust gas according to (1) above. (3) The carrier obtained by immersing the carrier in an aqueous solution of silver salt to support silver on the carrier and firing the carrier, and then immersing the carrier in aqueous solution of cobalt salt to support cobalt on the silver layer and firing the product. (2) A catalyst for removing nitrogen oxides in engine exhaust gas. (4) The nitrogen oxide removal catalyst in the engine exhaust gas according to any one of (1) to (3) above, in the presence of an organic compound having a weight ratio of 0.5 to 5 with respect to nitrogen oxides (NO x ). A method for removing nitrogen oxides in engine exhaust gas, which comprises contacting with engine exhaust gas containing oxygen in excess of the theoretical combustion amount to remove nitrogen oxides in exhaust gas. (5) The method for removing nitrogen oxides from engine exhaust gas according to (4), wherein the organic compound is light oil.
【００１０】[0010]
【具体的構成】以下、本発明の具体的構成について詳細
に説明する。Specific Structure The specific structure of the present invention will be described in detail below.
【００１１】本発明のエンジン排気ガス中の窒素酸化物
除去触媒は、担体としてγ−アルミナを用い、この担体
に銀およびコバルトを担持したものである。The catalyst for removing nitrogen oxides in engine exhaust gas of the present invention uses γ-alumina as a carrier, and silver and cobalt are supported on this carrier.
【００１２】上記のように、銀およびコバルトを併用す
ることによって、水分および硫黄酸化物（ＳＯx ）の共
存下においても、エンジン排気ガス中の窒素酸化物（Ｎ
Ｏx）の除去能の低下がなく、長期に亘って触媒活性を
維持することができる。As described above, by using silver and cobalt in combination, nitrogen oxides (N) in engine exhaust gas can be obtained even in the presence of water and sulfur oxides (SO x ).
It is possible to maintain the catalytic activity for a long period without deteriorating the removal ability of O x ).
【００１３】これに対し、銀のおよびコバルトのうちい
ずれか一方のみでは、上記の本発明の効果は得られな
い。すなわち、銀のみでは共存硫黄酸化物による触媒活
性の低下がみられ、一方コバルトのみでは共存水分によ
る触媒活性の低下がみられる。On the other hand, the effect of the present invention described above cannot be obtained with only one of silver and cobalt. That is, when only silver was used, the coexistence of sulfur oxides decreased the catalytic activity, while when only cobalt was used, the coexistence of water decreased the catalytic activity.
【００１４】従って、本発明の効果は、銀とコバルトの
両者を併用することによってはじめて得られるものであ
り、どちらか一方の金属を担持したものでは得られな
い。Therefore, the effect of the present invention can be obtained only by using both silver and cobalt in combination, and cannot be obtained by supporting one of the metals.
【００１５】銀およびコバルトを担持させるには種々の
方法が可能である。すなわち、両成分を混合して担持さ
せても、それぞれを別個に担持させてもよい。これらの
うちでは、各成分を層状に担体に担持させることが好ま
しい。すなわち、単一種の金属の層を各々形成すること
が好ましい。このような場合、層形成後、隣接層同志の
接触面近傍で銀がコバルト層に、またコバルトが銀層に
互いに拡散して混合した状態となっていてもよい。Various methods are possible for loading silver and cobalt. That is, both components may be mixed and supported, or each may be separately supported. Among these, it is preferable that each component is supported on the carrier in layers. That is, it is preferable to form each layer of a single kind of metal. In such a case, after the layers are formed, silver may be diffused and mixed in the cobalt layer and cobalt may be mixed in the silver layer in the vicinity of the contact surfaces of the adjacent layers.
【００１６】本発明では、銀およびコバルトは各金属分
の層として層状に担体に担持させる方が好ましいが、特
に、２層構成とすることが好ましい。この場合、担体側
から第１層、第２層とすれば、第１層および第２層の金
属の合計担持量に対する第２層の金属担持量の割合が
０．１〜５０重量％となるようにすることが好ましく、
さらには０．５〜４０重量％、よりさらには１〜３０重
量％、特には１〜２０重量％とすることが好ましい。こ
のように金属担持量を規制することによって、本発明の
効果が向上する。これに対し、第１層と第２層との金属
担持量が上記とは逆になると、本発明の効果は低減す
る。具体的にいえば、第２層が銀のときは、銀量が多く
なると、銀の酸化物の生成量が多くなり、還元剤である
炭化水素類等の有機化合物が酸化反応により消費されて
しまい、窒素酸化物（ＮＯx ）の還元効率が低下してし
まう。一方、第２層がコバルトのときは、コバルト量が
多くなると、コバルトと水との親和性が良いため、水分
による触媒活性の低下が顕著になる。In the present invention, it is preferable that silver and cobalt are supported on the carrier in layers as layers of respective metal components, but it is particularly preferable to have a two-layer structure. In this case, if the first layer and the second layer are arranged from the carrier side, the ratio of the metal loading amount of the second layer to the total loading amount of the metal of the first layer and the second layer is 0.1 to 50% by weight. Preferably
Further, it is preferably 0.5 to 40% by weight, more preferably 1 to 30% by weight, and particularly preferably 1 to 20% by weight. By regulating the amount of metal carried in this way, the effect of the present invention is improved. On the other hand, when the metal loading amounts of the first layer and the second layer are opposite to the above, the effect of the present invention is reduced. Specifically, when the second layer is silver, as the amount of silver increases, the amount of silver oxide produced increases, and organic compounds such as hydrocarbons that are reducing agents are consumed by the oxidation reaction. As a result, the reduction efficiency of nitrogen oxides (NO x ) decreases. On the other hand, when the second layer is made of cobalt, when the amount of cobalt is large, the affinity of cobalt with water is good, so that the catalytic activity is significantly reduced due to water.
【００１７】従って、第１層と第２層との金属担持量を
上記範囲とすることが好ましいが、なかでも第１層とし
て銀層を形成し、第２層としてコバルト層を形成するこ
とが好ましい。このような層構成とすることによって、
初期の触媒活性が高くなるとともに、この高い触媒活性
が維持されることになる。Therefore, it is preferable that the amount of metal supported on the first layer and the second layer is within the above range, but above all, it is preferable to form a silver layer as the first layer and a cobalt layer as the second layer. preferable. With such a layer structure,
As the initial catalytic activity increases, this high catalytic activity will be maintained.
【００１８】なお、第１層をコバルト層とし、第２層を
銀層とした場合は、特に、初期の触媒活性が上記構成に
比べ劣るものとなる。When the first layer is a cobalt layer and the second layer is a silver layer, the initial catalytic activity is particularly inferior to that of the above structure.
【００１９】本発明における銀とコバルトとの合計金属
担持量は、触媒全体に対し、金属元素換算量で０．５〜
５重量％、特に０．５〜３重量％とすることが好まし
い。このような担持量とするのは、担持量が少ないと活
性が低く、また多すぎると担持効果が低減するためであ
る。従って、２層を形成する場合、第１層は０．５〜３
重量％、好ましくは０．５〜２重量％の担持量とするこ
とが好ましく、第２層は０．０５〜１．５重量％、好ま
しくは０．０５〜１．０重量％の担持量とすることが好
ましい。In the present invention, the total amount of supported metal of silver and cobalt is 0.5 to 0.5 in terms of metal element, based on the whole catalyst.
It is preferably 5% by weight, particularly preferably 0.5 to 3% by weight. The reason for setting such a loading amount is that the activity is low when the loading amount is small, and the loading effect is reduced when the loading amount is too large. Therefore, when forming two layers, the first layer is 0.5 to 3
The loading amount is preferably 0.5% to 2% by weight, and the second layer has a loading amount of 0.05 to 1.5% by weight, preferably 0.05 to 1.0% by weight. Preferably.
【００２０】本発明では、上記のように２層構成に形成
することが好ましいが、場合によっては３層以上の多層
構成に形成してもよく、例えば銀層およびコバルト層を
各々多層構成に形成して銀層上にコバルト層を設層した
り、あるいは銀層とコバルト層とを交互に設層したりす
ることもできる。In the present invention, it is preferable to form a two-layer structure as described above, but in some cases, a multi-layer structure of three or more layers may be formed. For example, a silver layer and a cobalt layer may each be formed in a multi-layer structure. Then, a cobalt layer may be formed on the silver layer, or a silver layer and a cobalt layer may be alternately formed.
【００２１】なお、銀層とコバルト層との接触面近傍で
は、前述のとおり、銀層にコバルトが、またコバルト層
に銀が、各々拡散していてもよいほか、担体に銀やコバ
ルトが、また担体中の成分が銀層またはコバルト層に拡
散していてもよい。また、銀やコバルトは通常酸化物と
して存在するが、その一部または全部が金属状態であっ
ていてもよい。In the vicinity of the contact surface between the silver layer and the cobalt layer, cobalt may be diffused in the silver layer and silver may be diffused in the cobalt layer as described above, or silver or cobalt may be diffused in the carrier. Further, the components in the carrier may be diffused in the silver layer or the cobalt layer. Further, silver and cobalt usually exist as oxides, but part or all of them may be in a metallic state.
【００２２】本発明に用いる担体は、γ−アルミナであ
る。このγ−アルミナ担体は、耐熱性に優れ、モノリス
状に成形加工が容易である。The carrier used in the present invention is γ-alumina. This γ-alumina carrier has excellent heat resistance and can be easily formed into a monolith.
【００２３】γ−アルミナは、アルミナ成分中、γ−ア
ルミナを好ましくは５０重量％以上、特に好ましくは９
０重量％以上含有するものである。この含有量は、蛍光
Ｘ線チャートから求めることができる。The amount of γ-alumina in the alumina component is preferably 50% by weight or more, and particularly preferably 9%.
The content is 0% by weight or more. This content can be obtained from a fluorescent X-ray chart.
【００２４】なお、用いるγ−アルミナは、Ａｌ2 Ｏ3
成分が９０重量％以上であり、ＳｉＯ2 が１０重量％以
下、その他、Ｎａ2 Ｏ3 、Ｆｅ2 Ｏ3 などの不純物が１
重量％以下含有されていてもよい。The γ-alumina used is Al 2 O 3
The content is 90% by weight or more, SiO 2 is 10% by weight or less, and other impurities such as Na 2 O 3 and Fe 2 O 3 are 1%.
It may be contained by weight% or less.
【００２５】γ−アルミナ粒子としては、窒素吸着法
（ＢＥＴ法）による比表面積１００m2/g以上の粒子を用
いることが好適である。なお、比表面積の上限について
は特に制限はないが、通常は１０００m2/g程度である。As the γ-alumina particles, it is preferable to use particles having a specific surface area of 100 m 2 / g or more as measured by a nitrogen adsorption method (BET method). The upper limit of the specific surface area is not particularly limited, but is usually about 1000 m 2 / g.
【００２６】γ−アルミナとしては、結晶性アルミナ水
和物の熱分解法や、アルミン酸ナトリウムを硫酸アルミ
ニウムで中和して焼成する方法（「触媒講座」”触媒設
計”講談社１９８５）またはアルミニウム金属アルコキ
シドの加水分解からのいずれの調製法で調製してよく、
あるいは市販されているものを用いてもよい。As the γ-alumina, a thermal decomposition method of crystalline alumina hydrate, a method of neutralizing sodium aluminate with aluminum sulfate and firing (“Catalyst course” “Catalyst design” Kodansha 1985) or aluminum metal It may be prepared by any method from hydrolysis of alkoxide,
Alternatively, a commercially available product may be used.
【００２７】アルミナのなかでも、γ−アルミナを用い
るのは、α−アルミナ等に比べ窒素酸化物の除去率、す
なわち脱硝率が高いからである。Among alumina, γ-alumina is used because it has a higher removal rate of nitrogen oxides, that is, a higher denitrification rate than α-alumina.
【００２８】γ−アルミナ担体は一次粒子のまま用いて
もよく、また一次粒子あるいは二次粒子を成形して用い
てもよく、または適当な基材上に種々の方法により被覆
して用いることもできる。The γ-alumina carrier may be used as the primary particles as it is, or may be used by molding the primary particles or the secondary particles, or may be used by coating it on a suitable substrate by various methods. it can.
【００２９】例えば、ハニカム状のコージェライトなど
にゾルゲル法またはアルミナゾルを接着剤として被覆し
たり、またアルミナゾルを基材上にウォッシュコート
し、被膜成形後、乾燥し４００〜７００℃で大気圧下の
空気中で焼成すればよく、その製造はきわめて容易であ
る。また、基材との接着性も良好である。For example, a honeycomb-shaped cordierite or the like is coated with a sol-gel method or alumina sol as an adhesive agent, or alumina sol is wash-coated on a substrate, dried after forming a film, and dried at 400 to 700 ° C. under atmospheric pressure. It only needs to be fired in air, and its production is extremely easy. Also, the adhesiveness with the substrate is good.
【００３０】担体の形状としては、粒状やハニカム等の
モノリス状、あるいはクロス状など、どのような形状で
あってもよい。The shape of the carrier may be any shape such as a granular shape, a monolith shape such as a honeycomb shape, or a cloth shape.
【００３１】なお、γ−アルミナ担体は、それ自体で触
媒として機能し得るものである。The γ-alumina carrier itself can function as a catalyst.
【００３２】本発明の窒素酸化物除去触媒を得るに際
し、γ−アルミナ担体に触媒金属を担持させる方法とし
ては、金属塩類の水溶液にγ−アルミナ担体を加え、攪
拌しながら担持する方法が一般的である。この際の担体
は、粒状であってもモノリス状であってもよい。この
後、１２０℃程度の温度で１０〜２０時間ほど乾燥し、
４００〜７００℃程度で１〜４時間ほど焼成すればよ
い。このとき用いる金属塩類としては、銀として、硝酸
銀、酢酸銀等が挙げられ、コバルトとしては、硝酸コバ
ルト、酢酸コバルト、硫酸コバルト等が挙げられる。こ
のとき、用いる金属塩類の水溶液の濃度は０．００５〜
１モル/l程度とする。When the catalyst for removing nitrogen oxides of the present invention is obtained, a method of supporting the catalytic metal on the γ-alumina carrier is generally a method of adding the γ-alumina carrier to an aqueous solution of metal salts and supporting the catalyst metal while stirring. Is. In this case, the carrier may be granular or monolithic. After that, it is dried at a temperature of about 120 ° C. for about 10 to 20 hours,
It suffices to perform firing at about 400 to 700 ° C. for about 1 to 4 hours. Examples of the metal salts used at this time include silver such as silver nitrate and silver acetate, and examples of cobalt include cobalt nitrate, cobalt acetate and cobalt sulfate. At this time, the concentration of the aqueous solution of the metal salt used is 0.005
It is about 1 mol / l.
【００３３】担持金属を２層構成に形成し、第１層を銀
層、第２層をコバルト層として形成する場合には、第１
層目の銀は、例えば硝酸銀溶液に担体を固液比が３（ｖ
／ｖ）程度となる割合で加え、攪拌しながら担持する。
担持後、１２０℃程度の温度で、１２時間程度の乾燥を
行い、５００℃程度の温度で、２時間程度、空気雰囲気
下で焼成を行う。第２層目のコバルトの担持は、例えば
硝酸コバルトまたは酢酸コバルト溶液に銀担持したもの
を前記の銀の場合と同じ割合で加え、攪拌しながら担持
する。担持後の乾燥、焼成は第１層目と同様に行う。When the supporting metal is formed into a two-layer structure, the first layer is formed as a silver layer and the second layer is formed as a cobalt layer, the first layer is formed.
For the silver in the layer, for example, a carrier is added to a silver nitrate solution at a solid-liquid ratio of 3 (v
/ V), and add while stirring.
After the supporting, it is dried at a temperature of about 120 ° C. for about 12 hours, and baked at a temperature of about 500 ° C. for about 2 hours in an air atmosphere. The second layer of cobalt is supported by, for example, adding a silver nitrate solution to a cobalt nitrate or cobalt acetate solution in the same proportion as in the case of the above silver, and carrying it with stirring. Drying and firing after supporting are performed in the same manner as the first layer.
【００３４】その他の層構成とするときも、上記に準じ
て行えばよい。The other layer constitution may be carried out in the same manner as above.
【００３５】本発明の触媒は、担体形状に応じ、粒状、
モノリス状等のいずれの形状であってもよい。The catalyst of the present invention is granular depending on the shape of the carrier.
It may have any shape such as a monolith shape.
【００３６】本発明の触媒は、耐熱性が高く、９００℃
程度まで有効に使用することができる。一般には、３０
０〜６００℃での使用が有効である。The catalyst of the present invention has high heat resistance and is 900 ° C.
It can be used effectively to a degree. Generally, 30
Use at 0 to 600 ° C is effective.
【００３７】本発明の窒素酸化物除去方法は、本発明の
触媒をエンジン排気ガスに接触させることによって実施
される。このときのエンジン排気ガスは理論燃焼量より
過剰量の酸素を含有するものであり、具体的にはディー
ゼルエンジンやリーン領域でのガソリンエンジンの排気
ガスが挙げられる。The method for removing nitrogen oxides of the present invention is carried out by bringing the catalyst of the present invention into contact with engine exhaust gas. The engine exhaust gas at this time contains oxygen in excess of the theoretical combustion amount, and specific examples thereof include exhaust gas of a diesel engine or a gasoline engine in a lean range.
【００３８】なお、ディーゼルエンジンの排気ガスは、
ＮＯx ：７００〜１５００ppm 、Ｏ2 ：１０〜２０体積
％、ＳＯ2 ：２０〜２００ppm 、Ｈ2 Ｏ：５〜２０体積
％程度の各成分を含んでいる。Exhaust gas from a diesel engine is
NO x : 700 to 1500 ppm, O 2 : 10 to 20 volume%, SO 2 : 20 to 200 ppm, H 2 O: 5 to 20 volume% of each component.
【００３９】またリーン領域でのエンジンの排気ガス
は、ＮＯx ：３０００〜５０００ppm、Ｏ2 ：０．５〜
１０体積％、Ｈ2 Ｏ：１０〜２０体積％程度の各成分を
含んでいる。Further, the engine exhaust gas in the lean region has NO x : 3000 to 5000 ppm, O 2 : 0.5 to
10% by volume, H 2 O: 10 to 20% by volume of each component.
【００４０】本発明の触媒とエンジン排気ガスとを接触
させるに際し、還元剤として有機化合物を存在させる。When the catalyst of the present invention is brought into contact with engine exhaust gas, an organic compound is present as a reducing agent.
【００４１】還元剤は、排気ガス中の窒素酸化物濃度
（ＮＯx ）に対して０．５〜５倍量（重量比）を添加す
ることが好ましい。The reducing agent is preferably added in an amount of 0.5 to 5 times (weight ratio) with respect to the nitrogen oxide concentration (NO x ) in the exhaust gas.
【００４２】還元剤としては、炭化水素類やアルコール
等であってもよく、エンジン燃料の一部を還元剤として
用いることもできる。このような燃料としては、軽油、
プロパンガス等が挙げられ、特に軽油が好ましい。軽油
は、本発明において好ましく使用される触媒設定温度
（触媒と排気ガスとの接触温度）３００〜６００℃の温
度範囲で窒素酸化物の除去能が安定して得られる。The reducing agent may be hydrocarbons, alcohols or the like, and a part of the engine fuel can be used as the reducing agent. As such fuel, light oil,
Propane gas and the like can be mentioned, and light oil is particularly preferable. Diesel oil can stably obtain nitrogen oxide removing ability in the temperature range of 300 to 600 ° C., which is the catalyst set temperature (contact temperature between catalyst and exhaust gas) preferably used in the present invention.
【００４３】このように、本発明の窒素酸化物除去方法
は、過剰の酸素を含むエンジン排気ガス中の窒素酸化物
を燃料を還元剤として、無害の窒素ガスに選択還元する
ことができるため、定置式発生源のみならず移動発生源
に使用することができ、特に、移動発生源である自動車
に有効である。As described above, according to the method for removing nitrogen oxides of the present invention, the nitrogen oxides in the engine exhaust gas containing excess oxygen can be selectively reduced to harmless nitrogen gas by using the fuel as a reducing agent. It can be used not only for stationary sources but also for mobile sources, and is particularly effective for automobiles, which are mobile sources.
【００４４】[0044]
【実施例】以下、本発明を実施例によって、さらに詳細
に説明する。ただし、本発明はこれにより限定されるも
のではない。EXAMPLES The present invention will now be described in more detail by way of examples. However, the present invention is not limited to this.
【００４５】実施例１ γ−アルミナ、またはγ−アルミナを担体としてＡｇ、
ＣｏもしくはＡｇおよびＣｏを担持したものを、各々触
媒として用いて、脱硝試験を行った。Example 1 γ-alumina, or Ag using γ-alumina as a carrier,
A denitration test was carried out using Co or Ag and Co-supported ones as catalysts.
【００４６】γ−アルミナは、水沢化学工業製のアルミ
ナ（ＧＢ、ＤＳ）、または触媒化成工業製（ＡＣＢＭ−
１）を用いた。なお、いずれのアルミナを用いても脱硝
試験の結果は同様であった。Γ-Alumina is alumina (GB, DS) manufactured by Mizusawa Chemical Industry, or manufactured by Catalyst Chemical Industries (ACBM-
1) was used. The results of the denitration test were the same regardless of which alumina was used.
【００４７】γ−アルミナ担体は、粒径を１〜３mmに整
粒し、比表面積が１８０〜４００m2/gのものとした。The γ-alumina carrier had a particle size of 1 to 3 mm and a specific surface area of 180 to 400 m 2 / g.
【００４８】次に、γ−アルミナ担体にＡｇを担持した
Ａｇ触媒を作製した。Next, an Ag catalyst was prepared by supporting Ag on a γ-alumina carrier.
【００４９】銀の担持方法は、０．１mol/l の硝酸銀溶
液に、固体／液体比＝１：３（体積比）になるようにγ
−アルミナ担体を加え、２５℃で３０分間攪拌しながら
浸漬したのち、固液分離して１２０℃で１２時間程度乾
燥し、さらに、５００℃の空気雰囲気下で２時間焼成し
た。The method for supporting silver is as follows: γ so that the solid / liquid ratio = 1: 3 (volume ratio) in a 0.1 mol / l silver nitrate solution.
-Alumina carrier was added, and the mixture was immersed at 25 ° C for 30 minutes with stirring, then solid-liquid separated, dried at 120 ° C for about 12 hours, and further calcined in an air atmosphere at 500 ° C for 2 hours.
【００５０】このときの銀担持量は、０．６〜１．７重
量％（元素換算量）であった。The amount of silver supported at this time was 0.6 to 1.7% by weight (elemental equivalent).
【００５１】なお、担持量の測定は、ＨＦ−ＨＮＯ3 溶
液による湿式分解後、プラズマ発光分析法により測定し
た値を元素換算して担持量とした。The supported amount was measured by carrying out wet decomposition with an HF-HNO 3 solution and then converting the value measured by plasma emission spectrometry into the supported amount.
【００５２】さらに、同様に、Ｃｏを担持したＣｏ触媒
を作製した。Further, similarly, a Co catalyst supporting Co was prepared.
【００５３】コバルト担持方法は、０．１mol/l の酢酸
コバルト溶液に担体を固体／液体比＝１：３（体積比）
になるように加え、２５℃で３０分間攪拌しながら浸漬
した。担持後の処理は上記の銀担持と同様に行った。コ
バルト担持量は０．８〜１．３重量％であった。In the cobalt loading method, the carrier is added to a 0.1 mol / l cobalt acetate solution in a solid / liquid ratio = 1: 3 (volume ratio).
And was soaked at 25 ° C. for 30 minutes with stirring. The treatment after supporting was carried out in the same manner as the above-mentioned supporting of silver. The amount of supported cobalt was 0.8 to 1.3% by weight.
【００５４】次に、第１層に銀、第２層にコバルトを用
いた２層のＡｇ・Ｃｏ触媒を作製した。Next, a two-layer Ag.Co catalyst was prepared using silver for the first layer and cobalt for the second layer.
【００５５】第１層目の銀担持は、０．１mol/l の硝酸
銀溶液に担体を固体／液体比＝１：３（体積比）の割合
で加え、上記の銀担持と同様に浸漬、乾燥、焼成などの
処理を行い、第２層目のコバルト担持は、０．０１mol/
l の酢酸コバルト溶液に銀担持したものを固体／液体比
＝１：３（体積比）の割合で加え、上記の銀担持と同様
に浸漬、乾燥、焼成を行って調製した。銀担持量は０．
７〜１．２重量％であり、コバルト担持量は０．１〜
０．４重量％であった。The first layer of silver supported was prepared by adding a carrier to a 0.1 mol / l silver nitrate solution at a solid / liquid ratio of 1: 3 (volume ratio), immersing and drying in the same manner as the above silver supporting. The second layer of cobalt loading is 0.01 mol /
It was prepared by adding silver-supported cobalt acetate solution of 1 at a ratio of solid / liquid ratio = 1: 3 (volume ratio), and immersing, drying and firing in the same manner as the above-mentioned silver-supporting. The amount of silver supported is 0.
7 to 1.2% by weight, and the amount of supported cobalt is 0.1 to
It was 0.4% by weight.
【００５６】このとき、コバルトの担持金属全体に占め
る割合は約１０重量％であった。At this time, the ratio of cobalt to the entire supported metal was about 10% by weight.
【００５７】さらに、第１層にコバルト、第２層に銀を
用いた２層のＣｏ・Ａｇ触媒を作製した。Further, a two-layer Co.Ag catalyst using cobalt as the first layer and silver as the second layer was prepared.
【００５８】第１層目のコバルト担持は、０．１mol/l
の酢酸コバルト溶液を用い、第２層目の銀担持は、０．
０１mol/l の硝酸銀溶液を用い、上記の２層のＡｇ・Ｃ
ｏ触媒と同様にして調製した。コバルト担持量は０．７
〜１．２重量％であり、銀担持量は０．１〜０．４重量
％であった。The first layer of cobalt supported was 0.1 mol / l.
Of cobalt acetate solution, the silver loading of the second layer was 0.
Using 01 mol / l silver nitrate solution, the above two layers of Ag.C
o Prepared in the same way as the catalyst. Cobalt loading is 0.7
The amount of supported silver was 0.1 to 0.4% by weight.
【００５９】このとき、銀の担持金属全体に占める割合
は約１０重量％であった。At this time, the ratio of silver to the whole supported metal was about 10% by weight.
【００６０】触媒性能試験は、窒素：９０％体積、酸
素：１０体積％の混合ガスを希釈ガスとして、ＮＯ濃
度：１０００ppm 、水分濃度：７体積％、ＳＯ2 ：１５
ppm を加えた模擬排気ガスを用い、空間速度（ＳＶ）が
２０，０００hr-1の流速で通気する固定流通式で行っ
た。還元剤としては軽油またはプロパンを用い、窒素酸
化物濃度（ＮＯx ）に対して２倍量（重量比）を添加し
た。The catalyst performance test was carried out by using a mixed gas of nitrogen: 90% by volume, oxygen: 10% by volume as a diluent gas, NO concentration: 1000 ppm, water concentration: 7% by volume, SO 2 : 15
Using a simulated exhaust gas with ppm added, a fixed flow system was used in which the space velocity (SV) was aerated at a flow rate of 20,000 hr -1 . Light oil or propane was used as the reducing agent, and a double amount (weight ratio) was added to the nitrogen oxide concentration (NO x ).
【００６１】ガス中の窒素酸化物の分析は常圧化学発光
法により行い、窒素酸化物の除去率（脱硝率）は、触媒
層出口の窒素酸化物濃度を入口濃度で割ったパーセント
値を１００％から引いた値とした。The nitrogen oxides in the gas were analyzed by the atmospheric pressure chemiluminescence method, and the removal rate (denitration rate) of nitrogen oxides was obtained by dividing the nitrogen oxide concentration at the catalyst layer outlet by the inlet concentration to 100. The value was subtracted from%.
【００６２】なお、この値は、ガスを導入しはじめてか
ら、３〜５時間の時点で測定したものである。This value is measured 3 to 5 hours after the introduction of gas.
【００６３】得られた結果を触媒の種類毎に表１〜表４
に示す。The obtained results are shown in Tables 1 to 4 for each type of catalyst.
Shown in.
【００６４】[0064]
【表１】 [Table 1]
【００６５】[0065]
【表２】 [Table 2]
【００６６】[0066]
【表３】 [Table 3]
【００６７】[0067]
【表４】 [Table 4]
【００６８】表１〜表４の結果から、γ−アルミナ自体
が脱硝効果を示し、γ−アルミナを担体として用いた金
属触媒ではさらに脱硝効果が向上することがわかる。ま
た、還元剤として軽油を用いる方が、プロパンを用いる
より、温度によらず安定した性能が得られることがわか
る。From the results shown in Tables 1 to 4, it can be seen that γ-alumina itself exhibits a denitration effect, and that the metal catalyst using γ-alumina as a carrier further improves the denitration effect. Further, it is understood that the use of light oil as the reducing agent provides more stable performance regardless of temperature than the use of propane.
【００６９】なお、Ｃｏ・Ａｇ触媒（Ｃｏ：第１層）で
も脱硝効果は得られたが、Ａｇ・Ｃｏ触媒（Ａｇ：第１
層）に比べ劣ることがわかった。Although the denitration effect was obtained also with the Co.Ag catalyst (Co: first layer), the Ag.Co catalyst (Ag: first layer)
It was found to be inferior to the (layer).
【００７０】実施例２ 実施例１の触媒のうち、γ−アルミナを担体としたＡｇ
触媒、Ｃｏ触媒、Ａｇ・Ｃｏ触媒（Ａｇ：第１層）、Ｃ
ｏ・Ａｇ触媒（Ｃｏ：第１層）を各々用い、実施例１と
同様の触媒性能試験条件で１００時間の連続試験を行
い、その耐久性を見た。なお、温度は４５０℃とし、還
元剤には軽油を用いた。また試験時間の０時間は、ガス
を流しはじめてから１２〜１５時間後に連続試験を開始
するが、その開始時点をいう。Example 2 Among the catalysts of Example 1, Ag using γ-alumina as a carrier was used.
Catalyst, Co catalyst, Ag / Co catalyst (Ag: first layer), C
Using each o.Ag catalyst (Co: first layer), a continuous test was conducted for 100 hours under the same catalyst performance test conditions as in Example 1, and the durability was observed. The temperature was 450 ° C., and light oil was used as the reducing agent. Further, the test time of 0 hour means the starting point of time when the continuous test is started 12 to 15 hours after starting the gas flow.
【００７１】結果を表５に示す。The results are shown in Table 5.
【００７２】[0072]
【表５】 [Table 5]
【００７３】表５より、Ｃｏ触媒では１０時間の時点で
劣化しており、またＡｇ触媒でも５０時間経過の時点で
劣化しはじめるのに対し、Ａｇ・Ｃｏ触媒（Ａｇ：第１
層）では１００時間の時点でもほとんど劣化しないこと
がわかる。From Table 5, it can be seen that the Co catalyst deteriorates at 10 hours, and the Ag catalyst also starts to deteriorate at 50 hours, whereas the Ag.Co catalyst (Ag: 1st
It can be seen that the layer hardly deteriorates even after 100 hours.
【００７４】なお、Ｃｏ・Ａｇ触媒（Ｃｏ：第１層）で
もＡｇ・Ｃｏ触媒と同様の挙動を示すが、初期特性がＡ
ｇ・Ｃｏ触媒に劣るため、Ａｇ・Ｃｏ触媒の方が特性に
優れることがわかった。The Co.Ag catalyst (Co: first layer) exhibits the same behavior as the Ag.Co catalyst, but the initial characteristics are A.
It was found that the Ag.Co catalyst was superior in characteristics because it was inferior to the g.Co catalyst.
【００７５】上記において触媒層設定温度を３００〜５
００℃の温度範囲で、４５０℃以外としても触媒種に応
じ同様の傾向を示した。In the above, the catalyst layer set temperature is 300 to 5
In the temperature range of 00 ° C, the same tendency was exhibited depending on the catalyst species even if the temperature was other than 450 ° C.
【００７６】実施例３ 実施例２の連続試験において、Ａｇ・Ｃｏ触媒を用い、
還元剤にプロパンを用いるほかは同様にして触媒の耐久
性を調べた。結果を表６に示す。Example 3 In the continuous test of Example 2, Ag.Co catalyst was used,
The durability of the catalyst was examined in the same manner except that propane was used as the reducing agent. The results are shown in Table 6.
【００７７】[0077]
【表６】 [Table 6]
【００７８】表６によりプロパンを還元剤としても触媒
活性の維持が良好であることがわかる。It can be seen from Table 6 that the catalytic activity is maintained well even when propane is used as the reducing agent.
【００７９】実施例４ 実施例２の連続試験において、Ａｇ・Ｃｏ触媒（Ａｇ：
第１層）での担持金属全体に占めるＣｏの割合を実施例
２の１０重量％から、１５重量％とするほかは、同様
に、Ａｇ・Ｃｏ触媒を作製し、同様に触媒の耐久性を調
べた。結果を実施例２のＡｇ・Ｃｏ触媒とともに表７に
示す。Example 4 In the continuous test of Example 2, Ag.Co catalyst (Ag:
In the same manner, except that the ratio of Co to the entire supported metal in the first layer) was changed from 10% by weight of Example 2 to 15% by weight, an Ag.Co catalyst was prepared in the same manner, and the durability of the catalyst was similarly improved. Examined. The results are shown in Table 7 together with the Ag · Co catalyst of Example 2.
【００８０】[0080]
【表７】 [Table 7]
【００８１】表７より、Ｃｏ量を１５重量％としても良
好な結果が得られることがわかる。From Table 7, it can be seen that good results can be obtained even when the Co amount is 15% by weight.
【００８２】実施例５ 実施例１のＡｇ・Ｃｏ触媒（Ａｇ：第１層）を用い、デ
ィーゼルエンジン排気ガス中の窒素酸化物の除去を５０
０時間の連続試験によって調べ、その触媒性能を確認し
た。Example 5 Using the Ag / Co catalyst (Ag: first layer) of Example 1, nitrogen oxides in exhaust gas of diesel engine were removed by 50 times.
It was examined by a continuous test for 0 hours to confirm its catalytic performance.
【００８３】ディーゼルエンジンは４サイクル直接噴射
型、排気量２２９０ccで交流発電機付きのものを用い、
黒煙や微粒子等の除去を行わず、そのまま触媒層に導入
した。触媒層に４０ccの触媒を充填し、ＳＶ＝２０００
０hr-1、触媒層設定温度４５０℃とし、還元剤として軽
油を用い、ＨＣ／ＮＯx 比＝３（ｗ／ｗ）の条件にて調
べた。触媒層通過後の窒素酸化物濃度（ＮＯ＋ＮＯ2 ）
は化学発光式ＮＯx 計で測定し、ＮＯx 除去率を算出し
た。なお、連続試験における時間は実施例２と同じ意味
である。As the diesel engine, a 4-cycle direct injection type engine with a displacement of 2290 cc and an alternator was used.
The black smoke and fine particles were not removed, and they were directly introduced into the catalyst layer. The catalyst layer is filled with 40 cc of catalyst and SV = 2000
The conditions were set to 0 hr −1 , the catalyst layer set temperature was 450 ° C., light oil was used as the reducing agent, and the HC / NO x ratio was 3 (w / w). Nitrogen oxide concentration (NO + NO 2 ) after passing through the catalyst layer
Was measured with a chemiluminescence type NO x meter, and the NO x removal rate was calculated. The time in the continuous test has the same meaning as in Example 2.
【００８４】得られた結果を表８に示す。The results obtained are shown in Table 8.
【００８５】[0085]
【表８】 [Table 8]
【００８６】表８より、触媒活性の維持効果が良好なこ
とがわかる。From Table 8, it can be seen that the effect of maintaining the catalytic activity is good.
【００８７】なお、触媒層設定温度を３００℃〜５００
℃の温度範囲で、４５０℃以外としても同様の効果を示
した。The catalyst layer set temperature is set to 300 ° C to 500 ° C.
In the temperature range of ° C, the same effect was exhibited even at a temperature other than 450 ° C.
【００８８】[0088]
【発明の効果】本発明の触媒は、水分および硫黄酸化物
の共存下においても、長期に亘って触媒活性が維持され
る。従って、軽油等の燃料を還元剤として酸素過剰雰囲
気下でのエンジン排気ガス中の窒素酸化物を有効に除去
することができる。このため、自動車などの移動発生源
に適用できる。The catalyst of the present invention maintains its catalytic activity for a long period of time even in the presence of water and sulfur oxides. Therefore, it is possible to effectively remove the nitrogen oxides in the engine exhaust gas under the oxygen excess atmosphere by using the fuel such as light oil as the reducing agent. Therefore, it can be applied to mobile sources such as automobiles.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｂ０１Ｄ 53/36 １０２ Ｈ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location B01D 53/36 102 H
Claims (5)
およびコバルトを担持したエンジン排気ガス中の窒素酸
化物除去触媒。1. A catalyst for removing nitrogen oxides in engine exhaust gas, which comprises γ-alumina as a carrier and supports silver and cobalt on the carrier.
コバルトを設層して形成されており、コバルトの担持金
属全体に占める割合が金属元素換算量で０．１〜５０重
量％である請求項１のエンジン排気ガス中の窒素酸化物
除去触媒。2. The layer is formed by layering the silver on a carrier and then layering cobalt thereon, and the ratio of cobalt to the entire supported metal is 0.1 to 50% by weight in terms of metal element. The catalyst for removing nitrogen oxides in engine exhaust gas according to claim 1.
担持させ、これを焼成したのち、これをコバルト塩水溶
液に浸漬して銀層上にコバルトを担持させ、焼成して得
られた請求項２のエンジン排気ガス中の窒素酸化物除去
触媒。3. A carrier is obtained by immersing a carrier in an aqueous solution of silver salt to support silver on the carrier, firing this, and then immersing it in an aqueous solution of cobalt salt to support cobalt on the silver layer and firing. The catalyst for removing nitrogen oxides in engine exhaust gas according to claim 2.
ガス中の窒素酸化物除去触媒を、窒素酸化物（ＮＯx ）
に対する重量比が０．５〜５となる有機化合物の存在下
に、理論燃焼量より過剰量の酸素を含有するエンジン排
気ガスと接触させ、排気ガス中の窒素酸化物を除去する
エンジン排気ガス中の窒素酸化物除去方法。4. The nitrogen oxide removal catalyst in the engine exhaust gas according to claim 1, wherein the catalyst is nitrogen oxide (NO x ).
In an engine exhaust gas in which nitrogen oxide in the exhaust gas is removed by contacting the exhaust gas with an engine exhaust gas containing an excess amount of oxygen in the presence of an organic compound having a weight ratio of 0.5 to 5 Method for removing nitrogen oxides.
エンジン排気ガス中の窒素酸化物除去方法。5. The method for removing nitrogen oxides from engine exhaust gas according to claim 4, wherein the organic compound is light oil.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11445894A JP3623255B2 (en) | 1994-04-28 | 1994-04-28 | Catalyst and method for removing nitrogen oxides from engine exhaust gas |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11445894A JP3623255B2 (en) | 1994-04-28 | 1994-04-28 | Catalyst and method for removing nitrogen oxides from engine exhaust gas |
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| Publication Number | Publication Date |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100906481B1 (en) * | 2007-09-04 | 2009-07-08 | 김만곤 | Method of Producing a Catalyst for reducing the Automobile Gas |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04260441A (en) * | 1991-02-15 | 1992-09-16 | Tosoh Corp | Catalyst and method for purifying exhaust gas |
| JPH05212246A (en) * | 1991-08-28 | 1993-08-24 | Osaka Gas Co Ltd | Method for purifying nitrogen oxide in waste gas |
| JPH06238164A (en) * | 1992-12-25 | 1994-08-30 | Riken Corp | Catalyst and method for removing nitrogen oxides |
| JPH07108136A (en) * | 1993-10-08 | 1995-04-25 | Babcock Hitachi Kk | Denitrification method for methane-containing exhaust gas |
-
1994
- 1994-04-28 JP JP11445894A patent/JP3623255B2/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04260441A (en) * | 1991-02-15 | 1992-09-16 | Tosoh Corp | Catalyst and method for purifying exhaust gas |
| JPH05212246A (en) * | 1991-08-28 | 1993-08-24 | Osaka Gas Co Ltd | Method for purifying nitrogen oxide in waste gas |
| JPH06238164A (en) * | 1992-12-25 | 1994-08-30 | Riken Corp | Catalyst and method for removing nitrogen oxides |
| JPH07108136A (en) * | 1993-10-08 | 1995-04-25 | Babcock Hitachi Kk | Denitrification method for methane-containing exhaust gas |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100906481B1 (en) * | 2007-09-04 | 2009-07-08 | 김만곤 | Method of Producing a Catalyst for reducing the Automobile Gas |
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| Publication number | Publication date |
|---|---|
| JP3623255B2 (en) | 2005-02-23 |
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