JP2013244483A - Exhaust gas purifying apparatus of thermal engine and exhaust gas purifying method - Google Patents

Exhaust gas purifying apparatus of thermal engine and exhaust gas purifying method Download PDF

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JP2013244483A
JP2013244483A JP2012122473A JP2012122473A JP2013244483A JP 2013244483 A JP2013244483 A JP 2013244483A JP 2012122473 A JP2012122473 A JP 2012122473A JP 2012122473 A JP2012122473 A JP 2012122473A JP 2013244483 A JP2013244483 A JP 2013244483A
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exhaust gas
purification
heat engine
catalyst
nox
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Masahito Kanae
雅人 金枝
Shuichi Sugano
周一 菅野
Ka Ho
河 宝
Wataru Minami
亘 南
Shoji Yamaguchi
祥司 山口
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Hitachi Construction Machinery Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas purifying apparatus of a thermal engine, which purifies CO and HC in an exhaust gas in oxygen excessive atmosphere with high purification performance.SOLUTION: An exhaust gas purifying apparatus of a thermal engine is arranged at an exhaust gas channel 3 of the thermal engine discharging an exhaust gas of oxygen excessive atmosphere compared to a stoichiometric amount in an oxidation reaction of CO and HC. The exhaust gas purifying apparatus includes a first purifying part 5 containing a conversion catalyst component converting at least one adsorption component of NOx and HC in the exhaust gas or at least a part of HC in the exhaust gas into CO, and a second purifying part 6 containing a purifying catalyst component oxidizing CO or HC in the exhaust gas passing through the first purifying part 5 to purify.

Description

本発明は、自動車や建設機械等のディーゼルエンジンに代表される内燃機関及びボイラやガスタービンなどの外燃機関から排出される酸素過剰雰囲気の排ガス中の一酸化炭素（CO）や炭化水素（HC）を浄化する熱機関の排ガス浄化装置及び排ガス浄化方法に関する。   The present invention relates to carbon monoxide (CO) and hydrocarbons (HC) in exhaust gas in an oxygen-excess atmosphere discharged from internal combustion engines typified by diesel engines such as automobiles and construction machinery and external combustion engines such as boilers and gas turbines. The present invention relates to an exhaust gas purification device and an exhaust gas purification method for a heat engine.

近年、空燃比（ガス中の空気と燃料との比）が燃料希薄であるディーゼルエンジンやリーンバーンエンジンといった内燃機関、あるいはガスタービンや化学プラント等のように酸素過剰の雰囲気下で運転する外燃機関の増加に伴い、過剰酸素下で一酸化炭素(CO)や炭化水素(HC)を高度に酸化浄化する方法が要求されている。   In recent years, internal combustion engines such as diesel engines and lean burn engines, where the air-fuel ratio (ratio of air in the gas to fuel) is lean, or external combustion that operates in an oxygen-rich atmosphere such as gas turbines and chemical plants As the number of engines increases, a method for highly oxidizing and purifying carbon monoxide (CO) and hydrocarbons (HC) under excess oxygen is required.

CO,HCを酸化浄化する方法としては、白金（Pt）やパラジウム（Pd）といった貴金属を用いて酸化する方法が知られており、ディーゼルエンジン等から排出される排ガス浄化に適用されている。しかし、エンジン燃焼開始時等は、排ガスの温度が低く触媒が活性化されていない為、CO,HCの酸化活性が低くなってしまう。   As a method for oxidizing and purifying CO and HC, a method of oxidizing using noble metals such as platinum (Pt) and palladium (Pd) is known and applied to purification of exhaust gas discharged from a diesel engine or the like. However, at the start of engine combustion, etc., the exhaust gas temperature is low and the catalyst is not activated, so that the oxidation activity of CO and HC becomes low.

そこで、排ガスの温度が低い場合を含めて、排ガス中のCO,HCを浄化することを目的として、窒素酸化物（NOx）用のトラップ還元触媒層と、HCトラップ材層を組合せ、更に排ガスの空気過剰率を変化させる技術が開示されている（特開２００９−５２５４２号公報)。また、NOx吸着還元触媒の前段にHC吸着放出材を設けることで、NOx還元効率を高める排ガス浄化システムが開示されている（特開２０００−１３５４１９号公報)。   Therefore, in order to purify CO and HC in the exhaust gas, including when the temperature of the exhaust gas is low, the trap reduction catalyst layer for nitrogen oxide (NOx) and the HC trap material layer are combined to further reduce the exhaust gas. A technique for changing the excess air ratio is disclosed (Japanese Patent Laid-Open No. 2009-52542). In addition, an exhaust gas purification system that improves NOx reduction efficiency by providing an HC adsorption / release material before the NOx adsorption / reduction catalyst is disclosed (Japanese Patent Laid-Open No. 2000-135419).

特開２００９−５２５４２号公報JP 2009-52542 A 特開２０００−１３５４１９号公報JP 2000-135419 A

特開２００９−５２５４２号公報には、HCを酸化して浄化することが記載されているが、排ガスの空気過剰率を変化させる為に燃料を多く使用する必要がある。また、特開２０００−１３５４１９号公報には、NOx浄化性能が高まることが記載されているが、HCに関しては吸着して放出する旨の記載しかなく、HC浄化性能については不明である上、HC浄化活性が不十分であると考えられる。しかし、上記各文献には、上記の不具合に対処する方法は記載されていない。   Japanese Patent Application Laid-Open No. 2009-52542 describes that HC is oxidized and purified, but it is necessary to use a large amount of fuel in order to change the excess air ratio of the exhaust gas. Japanese Patent Laid-Open No. 2000-135419 describes that the NOx purification performance is enhanced, but HC is only described as being adsorbed and released, and the HC purification performance is unknown and HC It is considered that the purification activity is insufficient. However, each of the above-mentioned documents does not describe a method for dealing with the above problem.

本発明の目的は、熱機関から排出される酸素過剰雰囲気の排ガス中の一酸化炭素(CO)や炭化水素(HC)を高度に浄化する熱機関の排ガス浄化装置及び排ガス浄化方法を提供することにある。   An object of the present invention is to provide a heat engine exhaust gas purification device and an exhaust gas purification method for highly purifying carbon monoxide (CO) and hydrocarbons (HC) in exhaust gas in an oxygen-excess atmosphere exhausted from a heat engine. It is in.

上記目的を達成するために、本発明は、CO及びHCの酸化反応における化学量論量よりも過剰な酸素雰囲気の排ガスを排出する熱機関の排ガス流路に配置される熱機関の排ガス浄化装置において、前記排ガス中のCO又はHCを酸化して浄化するCO,HC浄化触媒を備え、当該CO,HC浄化触媒が前記排ガスに接触する前に、当該排ガス中のNOx又はHCの濃度を低減させることを特徴としている。   In order to achieve the above object, the present invention provides an exhaust gas purification apparatus for a heat engine that is disposed in an exhaust gas passage of a heat engine that exhausts exhaust gas in an oxygen atmosphere that is in excess of the stoichiometric amount in the oxidation reaction of CO and HC. A CO, HC purification catalyst that oxidizes and purifies CO or HC in the exhaust gas, and reduces the concentration of NOx or HC in the exhaust gas before the CO, HC purification catalyst contacts the exhaust gas It is characterized by that.

本発明によれば、過剰な酸素雰囲気で運転される熱機関からの排ガスに含まれるCO,HCを効率よく浄化することができ、熱機関からのCO,HC排出量を高度に抑制することができる。   According to the present invention, CO and HC contained in exhaust gas from a heat engine operated in an excessive oxygen atmosphere can be efficiently purified, and CO and HC emissions from the heat engine can be highly suppressed. it can.

本発明の実施の形態に係る排ガス浄化装置の概略構成図。1 is a schematic configuration diagram of an exhaust gas purification apparatus according to an embodiment of the present invention. 本発明の第１の実施の形態におけるエンジン、上流側浄化部５及び下流側浄化部６の模式構成図。The schematic block diagram of the engine, the upstream purification | cleaning part 5, and the downstream purification | cleaning part 6 in the 1st Embodiment of this invention. 本発明の第２の実施の形態におけるエンジン、上流側浄化部５A及び下流側浄化部６の模式構成図。The schematic block diagram of the engine, the upstream purification | cleaning part 5A, and the downstream purification | cleaning part 6 in the 2nd Embodiment of this invention. 本発明の第３の実施の形態における上流側浄化部５及び下流側浄化部６の模式構成図。The schematic block diagram of the upstream purification | cleaning part 5 and the downstream purification | cleaning part 6 in the 3rd Embodiment of this invention. 本発明の第４の実施の形態における上流側浄化部５A及び下流側浄化部６の模式構成図。The schematic block diagram of 5 A of upstream purification | cleaning parts and the downstream purification | cleaning part 6 in the 4th Embodiment of this invention. 本発明の第５の実施の形態における上流側浄化部５B及び下流側浄化部６の模式構成図。The schematic block diagram of the upstream purification | cleaning part 5B and the downstream purification | cleaning part 6 in the 5th Embodiment of this invention. 本発明の第６の実施の形態に係る排ガス浄化装置の模式構成図。The schematic block diagram of the exhaust gas purification apparatus which concerns on the 6th Embodiment of this invention. CO,HC浄化触媒について、排ガス組成を変化させた場合のCO浄化活性を示す図。The figure which shows CO purification activity at the time of changing an exhaust gas composition about a CO and HC purification catalyst. CO,HC浄化触媒について、排ガス組成を変化させた場合のHC浄化活性を示す図。The figure which shows HC purification activity at the time of changing an exhaust gas composition about a CO and HC purification catalyst. NOx吸着層を設けたCO,HC浄化触媒について、CO,HC浄化活性を示す図。The figure which shows CO and HC purification activity about the CO and HC purification catalyst which provided the NOx adsorption layer. NOx吸着層を設けたCO,HC浄化触媒について、CO,HC浄化活性を示す図。The figure which shows CO and HC purification activity about the CO and HC purification catalyst which provided the NOx adsorption layer. CO,HC浄化触媒について、排ガス組成を変化させた場合のCO浄化活性を示す図。The figure which shows CO purification activity at the time of changing an exhaust gas composition about a CO and HC purification catalyst. CO,HC浄化触媒の担体量を変化させた場合のCO浄化活性を示す図。The figure which shows CO purification activity at the time of changing the support | carrier amount of a CO and HC purification catalyst.

以下、本発明を詳細に説明する。一般に、乗用車や建設機械等のディーゼルエンジンに代表される内燃機関及びボイラやガスタービンなどの外燃機関から排出される排ガスは、化学量論量よりも過剰な酸素雰囲気であることが多い。また、これら内燃機関及び外燃機関からの排ガスには、CO,HCが一般に含まれている。本発明において、化学量論量とは、排ガス中に含まれるO2及びCO,HCが互いに過不足無く反応する場合の、O2,CO,HCの量を意味する。以下に詳細に説明する。 Hereinafter, the present invention will be described in detail. In general, exhaust gas discharged from internal combustion engines typified by diesel engines such as passenger cars and construction machines and external combustion engines such as boilers and gas turbines often has an oxygen atmosphere that is in excess of the stoichiometric amount. Moreover, CO and HC are generally contained in the exhaust gas from these internal combustion engines and external combustion engines. In the present invention, the stoichiometric amount means the amount of O 2 , CO, and HC when O 2 and CO, HC contained in the exhaust gas react with each other without excess or deficiency. This will be described in detail below.

排ガス中にO2,CO及びHCが含有されている場合に、これら３種のガスにおける反応として下記化学式（１）、（２）が考えられる。 When O 2 , CO and HC are contained in the exhaust gas, the following chemical formulas (1) and (2) are considered as reactions in these three gases.

2CO + O2 →2CO2 …化学式（１）
CnHm + (n + m/4)O2 → nCO2 + (m/2)H2O …化学式（２）
例えば、排ガス中にCO及びC3H6がそれぞれ300ppm存在する場合、化学式（１）及び（２）の反応が進行する為にはO2がそれぞれ150ppm、1350ppm必要である。化学量論量よりも過剰な酸素雰囲気とは、CO,HCが全て酸化されうる酸素量であることを意味する。即ち排ガス中にCO及びC3H6がそれぞれ300ppm存在する場合、O2が1500ppm(=150ppm+1350ppm)よりも多い場合を意味する。 2CO + O 2 → 2CO 2 ... Chemical formula (1)
C n H m + (n + m / 4) O 2 → nCO 2 + (m / 2) H 2 O ... Chemical formula (2)
For example, when 300 ppm of CO and C 3 H 6 are present in the exhaust gas, 150 ppm and 1350 ppm of O 2 are required for the reactions of the chemical formulas (1) and (2) to proceed. An oxygen atmosphere in excess of the stoichiometric amount means that the amount of oxygen that can oxidize all CO and HC. That is, when 300 ppm of CO and C 3 H 6 are present in the exhaust gas, this means a case where O 2 is higher than 1500 ppm (= 150 ppm + 1350 ppm).

本発明者らは、鋭意検討した結果、排ガスがCO,HC浄化触媒に接触する前に、当該排ガス中のNOx又はHCの濃度を低減させると、当該CO,HC浄化触媒によって排ガス中のCO,HCが効果的に浄化されることを明らかにした。   As a result of intensive studies, the inventors of the present invention reduced the concentration of NOx or HC in the exhaust gas before the exhaust gas contacted the CO, HC purification catalyst. It was clarified that HC is effectively purified.

排ガス中にNOxが共存すると、CO,HC浄化触媒のCO,HC浄化活性が低下する。これは、NOxが共存することでCO,HC浄化触媒によるCO,HC酸化反応が阻害されると考えられる。同様に、排ガス中にHCが共存すると、CO,HC浄化触媒のCO浄化活性が低下する。すなわち、HCが共存することでCO,HC浄化触媒によるCO酸化反応が阻害されると考えられる。   When NOx coexists in the exhaust gas, the CO and HC purification activity of the CO and HC purification catalyst decreases. It is thought that CO and HC oxidation reaction by the CO and HC purification catalyst is inhibited by the coexistence of NOx. Similarly, when HC coexists in the exhaust gas, the CO purification activity of the CO and HC purification catalyst decreases. That is, it is considered that the CO oxidation reaction by the CO and HC purification catalyst is inhibited by the coexistence of HC.

CO,HC浄化活性が低下する温度域は、CO,HC浄化触媒の種類によって異なるが、例えばCO,HC浄化触媒として白金（Pt）成分を使用した場合、当該温度域はおよそ300℃以下である。300℃以上ではNOx,HCが共存しても、CO,HC浄化活性が高い。従って、CO,HC浄化活性が低下する温度域では、排ガス中のNOx又はHCの濃度を一旦低減させた後に排ガスをCO,HC浄化触媒へ導入することで、CO,HC浄化活性の低下を抑制できる。排ガス温度が高まり、CO,HC浄化触媒のCO,HC浄化活性が向上すると、排ガス中のNOx又はHCの濃度を一旦低減させる必要は無くなる。即ち、CO,HC浄化活性が低下する温度域でのみ、排ガス中のNOx又はHCの濃度を低減させれば良い。   The temperature range where the CO and HC purification activity decreases varies depending on the type of the CO and HC purification catalyst. For example, when a platinum (Pt) component is used as the CO and HC purification catalyst, the temperature range is about 300 ° C. or less. . Above 300 ° C, CO and HC purification activity is high even if NOx and HC coexist. Therefore, in the temperature range where the CO and HC purification activity decreases, the exhaust gas is introduced into the CO and HC purification catalyst after once reducing the concentration of NOx or HC in the exhaust gas, thereby suppressing the decrease in the CO and HC purification activity. it can. If the exhaust gas temperature is increased and the CO and HC purification activity of the CO and HC purification catalyst is improved, the concentration of NOx or HC in the exhaust gas need not be once reduced. That is, it is only necessary to reduce the concentration of NOx or HC in the exhaust gas only in the temperature range where the CO and HC purification activity is reduced.

本発明の具体的な適用法としては、ディーゼルエンジン等の熱機関の始動時における排ガスのCO,HC浄化が考えられる。即ち、熱機関の始動時は、排ガス温度が低く、排ガス中にNOx,HCが共存することでCO,HC浄化触媒のCO,HC浄化活性が低下しやすい。従って、排ガス温度が低い場合には、排ガス中のNOx,HCの濃度を一旦低減させた後にCO,HC浄化触媒へ排ガスを導入することでCO,HC浄化が向上する。   As a specific application method of the present invention, CO and HC purification of exhaust gas at the start of a heat engine such as a diesel engine can be considered. That is, when the heat engine is started, the exhaust gas temperature is low, and NOx and HC coexist in the exhaust gas, so that the CO and HC purification activity of the CO and HC purification catalyst tends to decrease. Therefore, when the exhaust gas temperature is low, CO and HC purification is improved by once reducing the concentration of NOx and HC in the exhaust gas and then introducing the exhaust gas into the CO and HC purification catalyst.

低減対象となるNOxとしては、窒素と酸素からなるものであれば特に拘らない。例としては、NO,NO2,N2O及びN2O3等が挙げられる。低減対象となるHCとしては、水素と炭素からなるものであれば特に拘らない。例としては、CH4、C3H6、C2H4、C2H2及びC3H8等が挙げられる。 The NOx to be reduced is not particularly limited as long as it consists of nitrogen and oxygen. Examples include NO, NO 2 , N 2 O and N 2 O 3 . The HC to be reduced is not particularly limited as long as it consists of hydrogen and carbon. Examples include CH 4 , C 3 H 6 , C 2 H 4 , C 2 H 2, C 3 H 8 and the like.

本発明に適用するCO,HC浄化触媒としては、CO,HC浄化性能を有する触媒であれば特に拘らない。しかし、CO,HC浄化触媒として、Al,Ce,Si,Ti及びZrから選ばれた少なくとも1種を含む無機化合物の多孔質担体にCO,HC浄化触媒成分を担持させ、さらに当該多孔質担体上にPt,Pd,Rh,Au,Ir,Ru及びOsから選ばれた少なくとも1種を含む触媒活性成分を担持させると、排ガス中のCO,HCが効果的に浄化される。   The CO and HC purification catalyst applied to the present invention is not particularly limited as long as it has a CO and HC purification performance. However, as a CO, HC purification catalyst, a CO, HC purification catalyst component is supported on a porous carrier of an inorganic compound containing at least one selected from Al, Ce, Si, Ti and Zr, and further on the porous carrier. When a catalytically active component containing at least one selected from Pt, Pd, Rh, Au, Ir, Ru, and Os is supported on the catalyst, CO and HC in the exhaust gas are effectively purified.

ここで触媒活性成分として使用するPt,Pd,Rh,Au,Ir,Ru及びOsはCO,HC酸化能力が高く、十分高い温度ではCO,HC浄化性能が高い。Pt,Pd,Rh,Au,Ir,Ru及びOsの中から二元素以上組み合わせても良い。二元素以上組合せることで得られる合金が高い性能を有すると考えられる。   Here, Pt, Pd, Rh, Au, Ir, Ru, and Os used as catalytic active components have high CO and HC oxidizing ability, and high CO and HC purification performance at sufficiently high temperatures. Two or more elements may be combined from Pt, Pd, Rh, Au, Ir, Ru, and Os. An alloy obtained by combining two or more elements is considered to have high performance.

担体成分として使用するAl,Ce,Si,Ti及びZrの酸化物は高い比表面積が得られるため、触媒活性成分の分散度を向上させてCO、HC浄化性能を高める効果がある。特にAlの酸化物は耐熱性も高く、高いCO,HC浄化性能を維持できると考えられる。またCeを含む無機酸化物は高いOSC能（酸素吸蔵放出能(Oxygen Storage Capacity）を有しており、触媒表面上への酸素の蓄積量が増加することでCO,HCの酸化反応を促進する効果があると考えられる。   Since the oxides of Al, Ce, Si, Ti and Zr used as the support component have a high specific surface area, they have the effect of improving the CO and HC purification performance by improving the degree of dispersion of the catalytically active component. In particular, Al oxides have high heat resistance and are considered to maintain high CO and HC purification performance. Inorganic oxides containing Ce have high OSC ability (Oxygen Storage Capacity) and promote the oxidation reaction of CO and HC by increasing the amount of oxygen accumulated on the catalyst surface. It is considered effective.

排ガス中のNOx濃度を低減させる手法として、排ガスがCO,HC浄化触媒に接触する前に、排ガスをNOx吸着層へ接触させる方法が考えられる。この方法を実現するためには、CO,HC浄化触媒の前段にNOx吸着層を配置すれば良い。その具体例としては、例えば、CO,HC浄化触媒成分を担持する担体から排ガス流通方向における上流側にNOx吸着材を設置するものや、CO,HC浄化触媒成分を担体に担持させ当該CO,HC浄化触媒成分の上層にNOx吸着層を積層させるもの等が考えられる。すなわち、まずNOx吸着層に排ガスを接触させ、その後にCO,HC浄化触媒成分に排ガスを接触させることが可能な構成であれば良い。なお、上記したCO,HC浄化触媒成分にNOx吸着層を積層させる手法を適用すれば、CO,HC浄化触媒とNOx吸着層を一体化でき、コンパクト化できるといったメリットがある。   As a technique for reducing the NOx concentration in the exhaust gas, a method of bringing the exhaust gas into contact with the NOx adsorption layer before the exhaust gas contacts the CO and HC purification catalyst is conceivable. In order to realize this method, a NOx adsorption layer may be disposed in front of the CO and HC purification catalyst. Specific examples thereof include, for example, a NOx adsorbent installed upstream from the carrier supporting the CO, HC purification catalyst component in the exhaust gas flow direction, and the CO, HC purification catalyst component supported on the carrier. A layer in which a NOx adsorption layer is laminated on the upper layer of the purification catalyst component can be considered. That is, it is only necessary that the exhaust gas is first brought into contact with the NOx adsorption layer and then the exhaust gas is brought into contact with the CO and HC purification catalyst component. If the above-described method of laminating the NOx adsorption layer on the CO, HC purification catalyst component is applied, there is an advantage that the CO, HC purification catalyst and the NOx adsorption layer can be integrated and can be made compact.

また、排ガスがCO,HC浄化触媒に接触する前に、排ガスをNOx吸着層へ接触させることで、排ガス中にすす等の粒子状物質が存在した場合、粒子状物質の一部がNOx吸着層で一旦捕捉される。その場合、CO,HC浄化触媒への粒子状物質の付着が抑制される為、CO,HC浄化触媒の活性を高度に維持することができる点もメリットとなる。   In addition, by contacting the exhaust gas with the NOx adsorption layer before the exhaust gas contacts the CO, HC purification catalyst, if particulate matter such as soot is present in the exhaust gas, a part of the particulate material is in the NOx adsorption layer. Is once captured. In that case, since the adhesion of the particulate matter to the CO and HC purification catalyst is suppressed, it is also advantageous that the activity of the CO and HC purification catalyst can be maintained at a high level.

本発明においては、排ガスがCO,HC浄化触媒に接触する前に、触媒等を利用して排ガス中のNOxを分解除去しても良いが、分解しなくても吸着等によりNOx濃度を低減すれば良い。従って、NOxの吸着材又は吸着層を利用する場合には、NOxを分解する為の装置が不要となり、排ガス浄化システムの簡便化及びコスト低減につながる。   In the present invention, NOx in the exhaust gas may be decomposed and removed using a catalyst or the like before the exhaust gas contacts the CO or HC purification catalyst, but the NOx concentration can be reduced by adsorption or the like without being decomposed. It ’s fine. Therefore, when the NOx adsorbent or the adsorbed layer is used, an apparatus for decomposing NOx becomes unnecessary, which leads to simplification and cost reduction of the exhaust gas purification system.

ところで、上記のようにNOx吸着層を設けた場合、エンジン始動時において排ガス温度が低い場合はNOx吸着層へNOxが吸着するが、排ガス温度が高まるとNOx吸着層に吸着していたNOxが放出される。従って、NOx吸着層からのNOx放出温度が、CO,HC酸化触媒がNOx共存下でも十分高い性能を示す温度よりも高いことが好ましい。NOxを吸着する成分を選定することでNOx放出温度を制御することができる（例えば、CO,HC浄化触媒としてPt成分を使用した場合には、成分選定によりNOx放出温度が300℃を超えるように制御することが好ましい）。   By the way, when the NOx adsorption layer is provided as described above, NOx is adsorbed to the NOx adsorption layer when the exhaust gas temperature is low at the start of the engine, but when the exhaust gas temperature rises, the NOx adsorbed to the NOx adsorption layer is released. Is done. Therefore, the NOx release temperature from the NOx adsorption layer is preferably higher than the temperature at which the CO and HC oxidation catalyst exhibit sufficiently high performance even in the presence of NOx. NOx release temperature can be controlled by selecting components that adsorb NOx (for example, when Pt components are used as CO and HC purification catalysts, the NOx release temperature should exceed 300 ° C by selecting components) Preferably controlled).

また、CO,HC酸化触媒の後段（排ガス流通方向の下流側又はCO,HC酸化触媒成分の下層）に、NOx浄化触媒を設けると、排ガス中のNOxの浄化が可能となる為、好適である。NOxを浄化する手段については拘らない。排ガス中に残留するCO又はHCを還元剤としてNOxを浄化することが考えられる。更には、CO,HC酸化触媒と接触した排ガスがNOx浄化触媒に接触するまでの間にNH3又は尿素と接触させることで、当該NH3又は尿素を還元剤としてNOxを浄化することも考えられる。この場合の具体的な構成としては、NOx浄化触媒の前段にNH3又は尿素の噴出孔を設け、当該噴出孔からNH3又は尿素を吹き込むものがある。 In addition, it is preferable to provide a NOx purification catalyst downstream of the CO and HC oxidation catalyst (downstream of the exhaust gas flow direction or lower layer of the CO and HC oxidation catalyst component) because NOx in the exhaust gas can be purified. . It does not matter about the means to purify NOx. It is conceivable to purify NOx using CO or HC remaining in the exhaust gas as a reducing agent. Furthermore, it may be possible to purify NOx using NH 3 or urea as a reducing agent by contacting NH 3 or urea until the exhaust gas that has contacted the CO or HC oxidation catalyst contacts the NOx purification catalyst. . As the specific configuration of the case, the jet holes of NH 3 or urea upstream of the NOx purifying catalyst provided, there is blowing with NH 3 or urea from the ejection hole.

NOx吸着層として使用する成分は、NOxを吸着できるものであれば特に拘らないが、Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まず、Ce,Zr,La,Al,Si及びTiから選ばれた少なくとも１種を含むことでNOx吸着性能を高めることができる。Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含めないことでNOx吸着層に費やすコストを大幅に低減できるといったメリットがある。ここで実質的というのは、NOx吸着層におけるNOx吸着作用に影響を及ぼさない程度の添加量であることを意味しており、具体的には100ppm以下の含有量である。本発明では、排ガスがCO,HC浄化触媒に接触する前に、排ガス中のNOxを分解除去する必要が必ずしも無いので、NOx吸着層にPt,Pd,Rh,Au,Ir,Ru及びOsが実質的に含有されていなくても十分高いCO,HC浄化性能が発揮できる。   The component used as the NOx adsorption layer is not particularly limited as long as it can adsorb NOx, but substantially does not contain Pt, Pd, Rh, Au, Ir, Ru and Os, Ce, Zr, La, Al, By containing at least one selected from Si and Ti, NOx adsorption performance can be enhanced. By substantially not including Pt, Pd, Rh, Au, Ir, Ru, and Os, there is an advantage that the cost spent on the NOx adsorption layer can be greatly reduced. Here, “substantially” means that the added amount is such that it does not affect the NOx adsorbing action in the NOx adsorbing layer, and specifically the content is 100 ppm or less. In the present invention, it is not always necessary to decompose and remove NOx in the exhaust gas before the exhaust gas contacts the CO, HC purification catalyst. Therefore, Pt, Pd, Rh, Au, Ir, Ru, and Os are substantially contained in the NOx adsorption layer. High CO and HC purification performance can be exhibited even if not contained.

上記とは逆に、Pt,Pd,Rh,Au,Ir,Ru又はOsをNOx吸着層へ含有させた場合、Pt,Pd,Rh,Au,Ir,Ru又はOsはNOを酸化する能力を有する為、NOx吸着層に接触したガスはNO2を多く含有すると予想される。その場合、後段のCO,HC酸化触媒へNO2が接触しやすくなり、CO,HC酸化能力が低下する可能性がある。すなわち、Pt,Pd,Rh,Au,Ir,Ru又はOsを実質的に含まないNOx吸着層を利用すれば、NO2に起因したCO,HC酸化能力の低下を抑制できる。 Contrary to the above, when Pt, Pd, Rh, Au, Ir, Ru or Os is contained in the NOx adsorption layer, Pt, Pd, Rh, Au, Ir, Ru or Os has the ability to oxidize NO. Therefore, the gas in contact with the NOx adsorption layer is expected to contain a large amount of NO 2. In that case, NO 2 tends to come into contact with the subsequent CO, HC oxidation catalyst, and the CO, HC oxidation ability may be reduced. That, Pt, Pd, Rh, Au , Ir, by utilizing the NOx adsorbent layer is substantially free of Ru or Os, CO due to NO 2, the reduction of the HC oxidation capacity can be suppressed.

更に、Pt,Pd,Rh,Au,Ir,Ru又はOsをNOx吸着層へ含有した場合、排ガス中の水分量が多いと、NOx吸着層で硝酸分が生成し、NOxとして脱離し難くなる可能性も考えられる。   Furthermore, when Pt, Pd, Rh, Au, Ir, Ru, or Os is contained in the NOx adsorption layer, if there is a large amount of water in the exhaust gas, nitric acid content is generated in the NOx adsorption layer and it is difficult to desorb as NOx. Sex is also conceivable.

Ce,Zr又はLaを含む酸化物は一般に塩基性を有していると考えられるため、酸性分子であるNOxを吸着しやすいと考えられる。また、Al,Si又はTiの酸化物は高い比表面積が得られる為、NOxを吸着する点が多く得られると考えられる。Ce,Zr,Laから選ばれた少なくとも１種とAl,Si,Tiから選ばれた少なくとも１種を組み合わせることで更にNOx吸着性能が高まる。比表面積としては50m2/g以上が好ましい。 Since an oxide containing Ce, Zr or La is generally considered to have basicity, it is considered that NOx which is an acidic molecule is easily adsorbed. In addition, since Al, Si, or Ti oxide has a high specific surface area, it is considered that many NOx adsorption points can be obtained. The combination of at least one selected from Ce, Zr, and La and at least one selected from Al, Si, Ti further increases NOx adsorption performance. The specific surface area is preferably 50 m 2 / g or more.

NOxを吸着する材料として、ゼオライト材も考えられる。ゼオライト材種には特に拘らないが、βゼオライト、Y型ゼオライト、ZSM-5、モルデナイト、フェリエライト等が挙げられる。吸着を狙うNOx種によって分子径が異なり、NOxが脱離する温度も異なる為、それに合わせて使用するゼオライト種を選定することが好ましい。ゼオライト材を使用する場合も、Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まないことが望ましい。   A zeolite material is also conceivable as a material for adsorbing NOx. There are no particular restrictions on the type of zeolite material, and examples include β zeolite, Y-type zeolite, ZSM-5, mordenite, and ferrierite. Since the molecular diameter varies depending on the NOx species targeted for adsorption, and the temperature at which NOx is desorbed also varies, it is preferable to select the zeolite species to be used in accordance with it. Even when a zeolite material is used, it is desirable that Pt, Pd, Rh, Au, Ir, Ru and Os are not substantially contained.

排ガス中のHC濃度を低減させる手法として、CO,HC浄化触媒が排ガスに接触する前に、排ガス中のHCの一部又は全てをCOに転換させる手段を設けることが考えられる。HCをCOに転換したことで、CO,HC浄化触媒に流入するCO濃度は高まるが、HC濃度が低い為、結果としてCO浄化活性が高まる。   As a technique for reducing the HC concentration in the exhaust gas, it is conceivable to provide a means for converting part or all of the HC in the exhaust gas into CO before the CO and HC purification catalyst comes into contact with the exhaust gas. By converting HC to CO, the CO concentration flowing into the CO and HC purification catalyst is increased, but since the HC concentration is low, the CO purification activity is increased as a result.

排ガス中のHCの一部又は全てをCOに転換させる手段としては、例えば、CO,HC浄化触媒の前段にHCからCOへ転換する触媒（転換触媒）を設置するものや、CO,HC浄化触媒の上層にHCからCOへ転換する触媒層（転換触媒層）を設けるもの等が考えられる。なお、後者の手法を適用すれば、CO,HC浄化触媒とHCからCOへ転換する触媒層を一体化でき、コンパクト化できるといったメリットがある。CO,HC浄化触媒が排ガスに接触する前に、排ガス中のHCを予め吸着するのみでは排ガス中のHCが浄化されない。従って後者の手法のようにHCからCOへ転換する触媒層を設けることが必要となる。   As a means for converting part or all of HC in exhaust gas to CO, for example, a catalyst (conversion catalyst) that converts HC to CO before the CO or HC purification catalyst is installed, or a CO or HC purification catalyst It is possible to provide a catalyst layer (conversion catalyst layer) for converting HC to CO on the upper layer. If the latter method is applied, there is an advantage that the CO, HC purification catalyst and the catalyst layer for converting HC to CO can be integrated, and the size can be reduced. The HC in the exhaust gas is not purified only by pre-adsorbing the HC in the exhaust gas before the CO and HC purification catalyst contacts the exhaust gas. Therefore, it is necessary to provide a catalyst layer for converting HC to CO as in the latter method.

また、排ガスがCO,HC浄化触媒に接触する前に、排ガス中のHCの一部又は全てをCOに転換させる触媒へ接触させることで、排ガス中にすす等の粒子状物質が存在した場合、粒子状物質の一部がHCの一部又は全てをCOに転換させる触媒上で一旦捕捉される。これにより、CO,HC浄化触媒への粒子状物質の付着が抑制される為、CO,HC浄化触媒の活性を高度に維持することができる。   In addition, when particulate matter such as soot is present in the exhaust gas by contacting part or all of the HC in the exhaust gas with CO before the exhaust gas contacts the CO, HC purification catalyst, Part of the particulate matter is once captured on a catalyst that converts some or all of the HC to CO. Thereby, since the adhesion of the particulate matter to the CO and HC purification catalyst is suppressed, the activity of the CO and HC purification catalyst can be maintained at a high level.

CO,HC浄化触媒の活性が低い温度領域（例えば、CO,HC浄化触媒としてPt成分を使用した場合には300℃以下）で、HCからCOへ転換できる触媒成分を使用することが望ましい。HCからCOへ転換する触媒成分を選定することで好適な転換温度領域を設定することができる。   It is desirable to use a catalyst component that can convert HC to CO in a temperature range where the activity of the CO, HC purification catalyst is low (for example, 300 ° C. or lower when a Pt component is used as the CO, HC purification catalyst). A suitable conversion temperature region can be set by selecting a catalyst component that converts HC to CO.

CO,HC浄化触媒へ排ガス中の硫黄分（S分）が蓄積し、CO,HC浄化活性が低下することがある。この場合、S分をCO,HC浄化触媒から脱離させることでCO,HC浄化活性が回復することがある。S分をCO,HC浄化触媒から脱離させる際に排ガス中にHCよりもCOが多く存在すると、S分脱離が促進されることがある。従ってCO,HC浄化触媒が排ガスに接触する前に、排ガス中のHCの一部又は全てをCOに転換させておくとCO,HC浄化触媒からのS分脱離が促進される。   Sulfur content (S content) in the exhaust gas accumulates in the CO and HC purification catalyst, and CO and HC purification activity may decrease. In this case, CO and HC purification activity may be recovered by desorbing S from the CO and HC purification catalyst. When the S component is desorbed from the CO and HC purification catalyst, if there is more CO than HC in the exhaust gas, the S component desorption may be promoted. Therefore, if part or all of the HC in the exhaust gas is converted to CO before the CO and HC purification catalyst contacts the exhaust gas, the desorption of S from the CO and HC purification catalyst is promoted.

CO,HC浄化触媒と、NOx吸着層と、HCをCOへ転換する触媒層を組み合わせても良い。例えば、担体に担持されたCO,HC浄化触媒成分上へNOx吸着層をコートし、更にその上にHCをCOへ転換する触媒層をコートする手法が考えられる。NOx吸着層と、HCをCOへ転換する触媒層をコートする順序は特に拘らない。   A CO, HC purification catalyst, a NOx adsorption layer, and a catalyst layer for converting HC to CO may be combined. For example, a method of coating a NOx adsorption layer on the CO and HC purification catalyst component supported on the carrier and further coating a catalyst layer for converting HC into CO can be considered. The order of coating the NOx adsorption layer and the catalyst layer that converts HC to CO is not particularly limited.

HCをCOに転換する手段として、Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まず、Mn,Fe,Co,Ni,Cu及びAgから選ばれた少なくとも１種を含む触媒を使用することが考えられる。Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含めないことでHCをCOへ転換する触媒層に費やすコストを大幅に低減できるといったメリットがある。また、Pt,Pd,Rh,Au,Ir,Ru及びOsを、HCをCOへ転換する触媒層に含有した場合、排ガス中の水分量が多いと、HCをCOへ転換する触媒層で硝酸分が生成し、HCをCOへ転換する反応が進み難くなる可能性が考えられる。Mn,Fe,Co,Ni,Cu又はAgは排ガス中のHCと酸素からCOを得る反応に対して高い活性を有しているため、触媒成分として好適である。   As a means for converting HC to CO, a catalyst containing at least one selected from Mn, Fe, Co, Ni, Cu and Ag substantially free of Pt, Pd, Rh, Au, Ir, Ru and Os Can be considered. By substantially not including Pt, Pd, Rh, Au, Ir, Ru, and Os, there is an advantage that the cost spent on the catalyst layer for converting HC to CO can be greatly reduced. In addition, when Pt, Pd, Rh, Au, Ir, Ru, and Os are contained in the catalyst layer that converts HC to CO, if there is a large amount of water in the exhaust gas, the catalyst layer that converts HC to CO has a nitrate content. May be generated, making it difficult for the reaction to convert HC to CO to proceed. Mn, Fe, Co, Ni, Cu or Ag is suitable as a catalyst component because it has high activity for the reaction of obtaining CO from HC and oxygen in exhaust gas.

熱機関のCO,HC浄化触媒成分としてPtを使用した場合、300℃以下の温度域でのCO,HC浄化活性が低く、従って熱機関の始動時において排ガスのCO,HC浄化が十分に行われない場合がある。その場合、上記NOx,HC低減手段に加えて、熱機関の始動時の燃焼制御により排ガスの温度を早く高めることで、更に高い効率でCO,HCを浄化できる。排ガスの温度を早く高める手段（温度上昇手段）については特に拘らない。例えば電気ヒーターを用いることができる。更に、熱機関の燃焼制御装置によってリタード燃焼又はポスト墳射させることにより、排ガス中の未燃分を増加させることで触媒反応による発熱を促進させ、CO,HC浄化触媒が活性化するまでの時間を短縮することができる。   When Pt is used as the CO and HC purification catalyst component of the heat engine, the CO and HC purification activity in the temperature range of 300 ° C or less is low, so that the CO and HC purification of exhaust gas is sufficiently performed at the start of the heat engine. There may not be. In that case, in addition to the NOx and HC reducing means, CO and HC can be purified with higher efficiency by increasing the temperature of the exhaust gas quickly by combustion control at the start of the heat engine. The means for raising the temperature of the exhaust gas quickly (temperature raising means) is not particularly concerned. For example, an electric heater can be used. Furthermore, the time until the CO and HC purification catalyst is activated by promoting the heat generation by catalytic reaction by increasing the unburned content in the exhaust gas by retarded combustion or post-spraying by the combustion control device of the heat engine. Can be shortened.

CO,HC浄化触媒の多孔質担体として比表面積が高い酸化物を用いることでPt,Pd,Rh,Au,Ir,Ru,Osが高分散化し、CO,HC浄化性能が高まる。特に、多孔質担体としてAlを含む酸化物を使用すると、安定して高いCO,HC浄化性能が得られる。本発明において用いる多孔質担体の比表面積は、30〜800m2/gの範囲が好ましく、特に50〜400m2/gの範囲が好ましい。 Pt, Pd, Rh, Au, Ir, Ru, and Os are highly dispersed by using an oxide having a high specific surface area as a porous carrier for the CO and HC purification catalyst, and the CO and HC purification performance is enhanced. In particular, when an oxide containing Al is used as the porous carrier, high CO and HC purification performance can be obtained stably. The specific surface area of the porous support used in the present invention is preferably in the range of 30~800m 2 / g, in particular in the range of 50 to 400 m 2 / g are preferred.

CO,HC浄化触媒の多孔質担体に担持させる触媒活性成分として、Pt,Pd,Rh,Au,Ir,Ru及びOsから選ばれた２種以上を含有させると、特に熱劣化後のCO,HC浄化性能が高まる。理由は定かでないが、活性成分同士が合金化することで貴金属の凝集が抑制される為と考えられる。特に、PtとPdとの組合せ又はPtとRhとの組合せは耐熱性能が高まる。   When two or more kinds selected from Pt, Pd, Rh, Au, Ir, Ru, and Os are contained as catalytic active components to be supported on the porous carrier of the CO, HC purification catalyst, the CO, HC after heat deterioration in particular. Increases purification performance. The reason is not clear, but it is thought that aggregation of noble metals is suppressed by alloying the active ingredients. In particular, the combination of Pt and Pd or the combination of Pt and Rh increases the heat resistance performance.

多孔質担体における触媒活性成分のPt,Pd,Rh,Au,Ir,Ru及びOsの合計担持量は、好ましくは、多孔質担体2mol部に対して元素換算で0.00005mol部〜1.0mol部であり、より好ましくは、0.0003mol部〜0.3mol部である。Pt,Pd,Rh,Au及びIrの合計担持量が0.00005mol部未満であると担持効果は不十分となり、一方、1.0mol部を越えると活性成分自体の比表面積が低下し、さらに触媒コストが高くなる。ここで、「mol部」とは、各成分のmol数換算での含有比率を意味する。例えば、A成分2mol部に対してB成分の担持量が1mol部とは、A成分の絶対量の多少に関わらず、mol数換算でA成分が2に対し、B成分が1の割合で担持されていることを意味する。   The total supported amount of the catalytically active components Pt, Pd, Rh, Au, Ir, Ru and Os in the porous support is preferably 0.00005 mol parts to 1.0 mol parts in terms of elements with respect to 2 mol parts of the porous support. More preferably, it is 0.0003 mol part to 0.3 mol part. If the total supported amount of Pt, Pd, Rh, Au and Ir is less than 0.00005 mol part, the loading effect will be insufficient, while if it exceeds 1.0 mol part, the specific surface area of the active ingredient itself will be reduced, and the catalyst cost will be further reduced. Get higher. Here, “mol part” means the content ratio of each component in terms of mol number. For example, the loading amount of B component is 1 mol part with respect to 2 mol part of A component, regardless of the absolute amount of A component. Means that

CO,HC浄化触媒成分を担持させるための多孔質担体、またはNOx,HC吸着成分は、基材上に担持させてもよい。基材としては従来から使用されてきたコージェライト、Si-Al-Oからなるセラミックス又はステンレススチールなどの耐熱性金属基板などが適している。基材を用いる場合には、CO,HC浄化性能を向上させる観点から、多孔質担体の担持量は、基材1Ｌに対して50g以上300g以下であることが好ましい。50g以下であると貴金属の分散が低下し触媒活性が低下する。一方300g以上であると、基材がハニカム形状の場合にガス流路への目詰まりが発生し易くなる等の不具合が生じるようになる。   The porous carrier for supporting the CO, HC purification catalyst component, or the NOx, HC adsorption component may be supported on the substrate. As the base material, cordierite, a heat-resistant metal substrate such as Si-Al-O ceramics or stainless steel, which has been conventionally used, is suitable. When a substrate is used, the amount of the porous carrier supported is preferably 50 g or more and 300 g or less with respect to 1 L of the substrate from the viewpoint of improving CO and HC purification performance. If it is 50 g or less, the dispersion of the noble metal is lowered and the catalytic activity is lowered. On the other hand, when the weight is 300 g or more, when the substrate has a honeycomb shape, problems such as clogging of the gas flow path are likely to occur.

基材を用いたCO,HC浄化触媒の上層へ、NOx吸着層又はHCをCOへ転換する触媒層をコートする場合の上層コート量は、それぞれ基材1Ｌに対して5g以上150g以下であることが好ましい。5g以下であると、上層コートの効果が現れず、150g以上であると、反応ガスが下層のCO,HC浄化触媒へ到達しづらくなり、活性が低下する等の不具合が生じるようになる。   The upper layer coating amount when the NOx adsorption layer or the catalyst layer that converts HC to CO is coated on the upper layer of the CO, HC purification catalyst using the substrate should be 5g or more and 150g or less for each 1L of the substrate. Is preferred. If it is 5 g or less, the effect of the upper layer coat does not appear, and if it is 150 g or more, it becomes difficult for the reaction gas to reach the CO and HC purification catalyst in the lower layer, resulting in problems such as reduced activity.

CO,HC浄化触媒、NOx吸着層、HCをCOへ転換する触媒層の調製方法としては、例えば、含浸法、混練法、共沈法、ゾルゲル法、イオン交換法、蒸着法等の物理的調製方法や化学反応を利用した調製方法等などを用いることができる。なかでも、化学反応を利用した調製方法を用いることで、触媒活性成分の原料と多孔質担体との接触が強固になり、触媒活性成分のシンタリング等を防止できる。   Examples of methods for preparing CO, HC purification catalyst, NOx adsorption layer, and catalyst layer for converting HC to CO include physical preparation such as impregnation method, kneading method, coprecipitation method, sol-gel method, ion exchange method, and vapor deposition method. Methods, preparation methods using chemical reactions, and the like can be used. In particular, by using a preparation method utilizing a chemical reaction, the contact between the raw material of the catalytically active component and the porous carrier is strengthened, and sintering of the catalytically active component can be prevented.

CO,HC浄化触媒、NOx吸着層、HCをCOへ転換する触媒層の出発原料としては、硝酸化合物、塩化物、酢酸化合物、錯体化合物、水酸化物、炭酸化合物、有機化合物などの種々の化合物、金属、金属酸化物を用いることができる。例えばCO,HC浄化触媒の触媒活性成分としてPt,Pd,Rh,Au,Ir,Ru及びOsから選ばれた２種以上を組み合わせる場合には、活性成分が同一の溶液中に存在するような含浸液を用いて共含浸法にて調製することで触媒成分を均一に担持することができる。   As starting materials for CO, HC purification catalyst, NOx adsorption layer, catalyst layer for converting HC to CO, various compounds such as nitrate compounds, chlorides, acetic acid compounds, complex compounds, hydroxides, carbonate compounds, organic compounds, etc. A metal or a metal oxide can be used. For example, when combining two or more selected from Pt, Pd, Rh, Au, Ir, Ru and Os as catalytic active components of a CO, HC purification catalyst, impregnation so that the active components are present in the same solution The catalyst component can be uniformly supported by preparing the solution by a co-impregnation method.

CO,HC浄化触媒の形状は、用途に応じて適宜調整できる。例えば、コージェライト、Si-Al-O、SiC、ステンレス等の各種基体材料からなるハニカム構造体に、本発明のCO,HC浄化触媒をコーティングして得られるハニカム形状をはじめ、ペレット状、板状、粒状、粉末状などが挙げられる。ハニカム形状の場合、その基材はコ−ジェライトまたはSi-Al-Oからなる構造体を用いることが好適であるが、触媒温度が高まる虞がある場合には、触媒活性成分と反応しにくい基材（例えばFeを主成分とするメタルハニカム等の基材）を用いることが好ましい。また、多孔質担体と触媒活性成分のみでハニカムを形成してもよい。また、フィルター機能を有する基材を使用すれば、排ガス中のすす等を浄化でき、好ましい場合がある。   The shape of the CO and HC purification catalyst can be appropriately adjusted according to the application. For example, the honeycomb structure obtained by coating the honeycomb structure made of various base materials such as cordierite, Si-Al-O, SiC, and stainless steel with the CO and HC purification catalyst of the present invention, pellets, and plates , Granular, powdery and the like. In the case of a honeycomb shape, it is preferable to use a structure made of cordierite or Si—Al—O as the base material. It is preferable to use a material (for example, a base material such as a metal honeycomb mainly composed of Fe). Alternatively, the honeycomb may be formed with only the porous carrier and the catalytically active component. In addition, use of a substrate having a filter function may be preferable because it can purify soot in the exhaust gas.

本発明はCO及びHCの酸化反応における化学量論量よりも過剰な酸素雰囲気の排ガスの浄化に対して特に有効であり、常に排ガス中の酸素が化学量論量よりも過剰である方が好適である。   The present invention is particularly effective for purifying exhaust gas in an oxygen atmosphere that is in excess of the stoichiometric amount in the oxidation reaction of CO and HC, and it is always preferable that the oxygen in the exhaust gas is in excess of the stoichiometric amount. It is.

以下、次に本発明の実施の形態及び実施例について説明する。
図１は本発明の実施の形態に係る排ガス浄化装置の概略構成図である。この図に示す排ガス浄化装置は、ディーゼルエンジン１の排ガスを浄化するものであり、排気管３中に設置された上流側浄化部５及び下流側浄化部６と、主にエンジン１の制御を行うためのコントローラ（制御装置）９を備えている。 Hereinafter, embodiments and examples of the present invention will be described.
FIG. 1 is a schematic configuration diagram of an exhaust gas purifying apparatus according to an embodiment of the present invention. The exhaust gas purification apparatus shown in this figure purifies the exhaust gas of the diesel engine 1 and mainly controls the upstream side purification unit 5 and the downstream side purification unit 6 installed in the exhaust pipe 3 and the engine 1. A controller (control device) 9 is provided.

ディーゼルエンジン１は、燃焼室（シリンダ）１ａ内の空気をピストン１ｂで圧縮して高温にし、その圧縮空気に燃料噴射装置２を介して燃料を供給して自然着火させることで動力を得ている。エンジン１が排出する排ガスは、CO及びHCの酸化反応における化学量論量よりも過剰な酸素雰囲気となる。また、ディーゼルエンジン１は、吸気管４と燃焼室１ａの間に吸気バルブ１ｃを備えており、燃焼室１ａと排気管３の間に排気バルブ１ｄを備えている。なお、図１には吸排気バルブ１ｃ,１ｄを１個ずつ示したが、各バルブの数はこれだけに限定されない。なお、浄化触媒５，６の下流側にはフィルタ（図示せず）を設置し、排ガス中の微粒物質（particulate matter：ＰＭ）を当該フィルタで捕集しても良い。   The diesel engine 1 obtains power by compressing the air in the combustion chamber (cylinder) 1a with the piston 1b to a high temperature, and supplying the fuel to the compressed air via the fuel injection device 2 to cause spontaneous ignition. . The exhaust gas discharged from the engine 1 has an oxygen atmosphere that is in excess of the stoichiometric amount in the oxidation reaction of CO and HC. The diesel engine 1 includes an intake valve 1c between the intake pipe 4 and the combustion chamber 1a, and an exhaust valve 1d between the combustion chamber 1a and the exhaust pipe 3. 1 shows one intake / exhaust valve 1c and 1d, but the number of each valve is not limited to this. A filter (not shown) may be installed on the downstream side of the purification catalysts 5 and 6, and particulate matter (PM) in the exhaust gas may be collected by the filter.

図２は、本発明の第１の実施の形態におけるエンジン、上流側浄化部５及び下流側浄化部６の模式構成図である。なお、先の図と同じ部分には同じ符号を付して説明を省略する（後の各図も同様とする）。この図に示すように上流側浄化部５は、排気管３内の排ガスの流通方向において、下流側浄化部６よりも上流に配置されている。この図の例では、上流側浄化部５として、排ガス中のNOx吸着成分を含む吸着材（NOx吸着材）が利用されており、下流側浄化部６として、排ガス中のCO又はHCを酸化して浄化する浄化触媒成分が担持された担体（CO,HC酸化触媒）が利用されている。   FIG. 2 is a schematic configuration diagram of the engine, the upstream purification unit 5 and the downstream purification unit 6 according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description is abbreviate | omitted (the following figures are also the same). As shown in this figure, the upstream purification unit 5 is disposed upstream of the downstream purification unit 6 in the flow direction of the exhaust gas in the exhaust pipe 3. In the example of this figure, an adsorbent (NOx adsorbent) containing NOx adsorbing components in the exhaust gas is used as the upstream purification unit 5, and CO or HC in the exhaust gas is oxidized as the downstream purification unit 6. A carrier (CO, HC oxidation catalyst) on which a purification catalyst component to be purified is supported is used.

NOx吸着材５の成分としては、既述のように、Ce,Zr,La,Al,Si及びTiから選ばれた少なくとも1種を含むことが好ましく、さらにPt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まないことが好ましい。また、NOx吸着材５としては、ゼオライトを含有したゼオライト構造体を利用しても良い。ゼオライト材種には特に拘らないが、βゼオライト、Y型ゼオライト、ZSM-5、モルデナイト、フェリエライト等が挙げられる。   As described above, the component of the NOx adsorbent 5 preferably contains at least one selected from Ce, Zr, La, Al, Si and Ti, and further includes Pt, Pd, Rh, Au, Ir, It is preferable that Ru and Os are not substantially contained. Further, as the NOx adsorbent 5, a zeolite structure containing zeolite may be used. There are no particular restrictions on the type of zeolite material, and examples include β zeolite, Y-type zeolite, ZSM-5, mordenite, and ferrierite.

CO,HC酸化触媒６における触媒成分は、既述のように、Al,Ce,Si,Ti及びZrから選ばれた少なくとも1種を含む無機化合物の多孔質担体で担持することが好ましい。また、当該多孔質担体は、Pt,Pd,Rh,Au,Ir,Ru及びOsから選ばれた少なくとも1種の触媒活性成分をさらに担持することが好ましい。   As described above, the catalyst component in the CO, HC oxidation catalyst 6 is preferably supported by a porous carrier of an inorganic compound containing at least one selected from Al, Ce, Si, Ti and Zr. The porous carrier preferably further supports at least one catalytically active component selected from Pt, Pd, Rh, Au, Ir, Ru and Os.

また、CO,HC酸化触媒６の形状は、用途に応じて適宜調整できる。例えば、コージェライト、Si-Al-O、SiC、ステンレス等の各種基体材料からなるハニカム構造体に、CO,HC酸化触媒成分をコーティングして得られるハニカム形状をはじめ、ペレット状、板状、粒状、粉末状などが挙げられる。ハニカム形状の場合、その基材はコ−ジェライトまたはSi-Al-Oからなる構造体を用いることが好適であるが、触媒温度が高まる虞がある場合には、触媒活性成分と反応しにくい基材（例えばFeを主成分とするメタルハニカム等の基材）を用いることが好ましい。また、多孔質担体と触媒活性成分のみでハニカムを形成してもよい。また、フィルター機能を有する基材を使用すれば、排ガス中のすす等を浄化でき、好ましい場合がある。   Moreover, the shape of the CO and HC oxidation catalyst 6 can be appropriately adjusted according to the application. For example, honeycomb structures obtained by coating CO, HC oxidation catalyst components on honeycomb structures made of various base materials such as cordierite, Si-Al-O, SiC, stainless steel, pellets, plates, granules And powder form. In the case of a honeycomb shape, it is preferable to use a structure made of cordierite or Si—Al—O as the base material. However, if there is a concern that the catalyst temperature may increase, a substrate that does not easily react with the catalytically active component is used. It is preferable to use a material (for example, a base material such as a metal honeycomb mainly composed of Fe). Alternatively, the honeycomb may be formed with only the porous carrier and the catalytically active component. In addition, use of a substrate having a filter function may be preferable because it can purify soot in the exhaust gas.

上記のように構成される本実施の形態の排ガス浄化装置において、エンジン始動時において排ガス温度が低いとき（例えば300℃以下）には、NOx吸着材５によって排ガス中のNOxを吸着できるので、CO,HC酸化触媒６へのNOxの流入を抑制できる。従って、CO,HC酸化触媒６が排ガスに接触する前に排ガス中のNOxの濃度を低減させることができるので、NOx共存によるCO,HC酸化反応の阻害を防ぐことができる。すなわち、本実施の形態によれば、過剰な酸素雰囲気で運転される熱機関からの排ガスに含まれるCO,HCを効率よく浄化することができ、熱機関からのCO,HC排出量を高度に抑制することができる。なお、大気に放出されるNOxを抑制する観点からは、CO,HC酸化触媒６の活性が十分高まる排ガス温度（例えば300℃を上回る温度）までNOx吸着材５からのNOx脱離を防ぐことが好ましい。   In the exhaust gas purification apparatus of the present embodiment configured as described above, when the exhaust gas temperature is low at the time of starting the engine (for example, 300 ° C. or less), NOx in the exhaust gas can be adsorbed by the NOx adsorbent 5, Therefore, the inflow of NOx to the HC oxidation catalyst 6 can be suppressed. Therefore, since the concentration of NOx in the exhaust gas can be reduced before the CO and HC oxidation catalyst 6 comes into contact with the exhaust gas, inhibition of the CO and HC oxidation reaction due to the coexistence of NOx can be prevented. That is, according to the present embodiment, CO and HC contained in the exhaust gas from the heat engine operated in an excessive oxygen atmosphere can be efficiently purified, and the CO and HC emissions from the heat engine are highly enhanced. Can be suppressed. From the viewpoint of suppressing NOx released to the atmosphere, it is possible to prevent NOx desorption from the NOx adsorbent 5 up to the exhaust gas temperature at which the activity of the CO and HC oxidation catalyst 6 is sufficiently increased (for example, a temperature exceeding 300 ° C.). preferable.

なお、図１に示した排ガス浄化装置において、ディーゼルエンジン１の運転始動時は排ガスの温度が低い。そこで、短期間で排ガス温度を上昇させる観点からは、コントローラ９によって燃料噴射装置２の燃料噴射を制御することで、主要な燃料噴射の後に追加燃料を噴射する「ポスト燃料墳射」を実施することが好ましい。ポスト燃料墳射により燃料濃度が高まった排ガスが浄化触媒5に導入され、浄化触媒5上にて燃料中のHC等が燃焼し燃焼熱が発生する為、浄化触媒6に導入される排ガス温度が高まる。以上の燃焼制御により、エンジン始動時の排ガス温度の昇温速度を高めることができ、CO,HC浄化触媒を早く活性化できる。なお、コントローラ９によりポスト燃料噴射に代えてリタード燃料を実施しても良いし、両者を併用しても良い。   In the exhaust gas purification apparatus shown in FIG. 1, the temperature of the exhaust gas is low when the diesel engine 1 is started. Therefore, from the viewpoint of raising the exhaust gas temperature in a short period of time, the controller 9 controls the fuel injection of the fuel injection device 2 to implement “post fuel injection” in which additional fuel is injected after the main fuel injection. It is preferable. Exhaust gas whose fuel concentration has increased due to post fuel spray is introduced into the purification catalyst 5, and HC in the fuel burns on the purification catalyst 5 to generate combustion heat. Rise. By the above combustion control, the temperature rise rate of the exhaust gas temperature at the time of starting the engine can be increased, and the CO and HC purification catalyst can be activated quickly. It should be noted that the controller 9 may perform retard fuel instead of post fuel injection, or may use both.

図３は、本発明の第２の実施の形態におけるエンジン、上流側浄化部５A及び下流側浄化部６の模式構成図である。この図の例では、上流側浄化部５Aとして、排ガス中のHCの少なくとも一部又は全部をCOに転換する転換触媒成分（HC→CO転換触媒）が利用されている。   FIG. 3 is a schematic configuration diagram of the engine, the upstream purification unit 5A, and the downstream purification unit 6 according to the second embodiment of the present invention. In the example of this figure, a conversion catalyst component (HC → CO conversion catalyst) that converts at least a part or all of HC in the exhaust gas into CO is used as the upstream purification unit 5A.

転換触媒成分５Aの成分としては、Mn,Fe,Co,Ni,Cu及びAgから選ばれた少なくとも1種を含むことが好ましく、さらにPt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まないことが好ましい。   The component of the conversion catalyst component 5A preferably contains at least one selected from Mn, Fe, Co, Ni, Cu and Ag, and substantially contains Pt, Pd, Rh, Au, Ir, Ru and Os. It is preferable not to include.

上記のように構成される本実施の形態の排ガス浄化装置において、エンジン始動時において排ガス温度が低いとき（例えば300℃以下）には、転換触媒５AによってHCに由来するCOが生成されるため、CO,HC酸化触媒成分に接触する排ガス中のHC濃度が低下し、CO濃度が高まる。このときCO濃度は高いものの、HC濃度が低い為、HCガスによるCO浄化反応の阻害が生じずCO浄化率を高めることができる。これにより、過剰な酸素雰囲気で運転される熱機関からの排ガスに含まれるCO,HCを効率よく浄化することができ、熱機関からのCO,HC排出量を高度に抑制することができる。   In the exhaust gas purification apparatus of the present embodiment configured as described above, when the exhaust gas temperature is low at the time of starting the engine (for example, 300 ° C. or less), CO derived from HC is generated by the conversion catalyst 5A. The HC concentration in the exhaust gas in contact with the CO and HC oxidation catalyst components decreases, and the CO concentration increases. At this time, although the CO concentration is high, since the HC concentration is low, inhibition of the CO purification reaction by HC gas does not occur, and the CO purification rate can be increased. Thereby, CO and HC contained in the exhaust gas from the heat engine operated in an excessive oxygen atmosphere can be efficiently purified, and CO and HC emissions from the heat engine can be highly suppressed.

なお、本実施の形態では、排ガス中のHCをCOに転換する転換触媒５Ａを利用することでHC濃度の低減を図ったが、転換触媒５Ａに代替して、排ガス中のHC吸着成分を含む吸着材（HC吸着材）を上流側浄化部として利用しても良い。   In this embodiment, the HC concentration is reduced by using the conversion catalyst 5A that converts HC in the exhaust gas into CO. However, instead of the conversion catalyst 5A, the HC adsorption component in the exhaust gas is included. An adsorbent (HC adsorbent) may be used as the upstream purification unit.

また、CO,HC酸化触媒６の上流側にNOx吸着材５及びHC→CO転換触媒５A（又はHC吸着材）を直列に配置しても良い。このとき、NOx吸着材５及び転換触媒５A（HC吸着材）の配置順序は特に限定しない。このように排ガス浄化装置を構成すると、排ガス中のNOx濃度及びHC濃度を低減することができるので、上記２つの実施の形態よりも排ガスに含まれるCO,HCを効率よく浄化することができる。   Further, the NOx adsorbent 5 and the HC → CO conversion catalyst 5A (or HC adsorbent) may be arranged in series upstream of the CO and HC oxidation catalyst 6. At this time, the arrangement order of the NOx adsorbent 5 and the conversion catalyst 5A (HC adsorbent) is not particularly limited. If the exhaust gas purification apparatus is configured in this way, the NOx concentration and the HC concentration in the exhaust gas can be reduced, so that CO and HC contained in the exhaust gas can be purified more efficiently than in the above two embodiments.

上記の各実施の形態では、上流側浄化部５，５Ａと下流側浄化部６を異なる担体（基材）で形成し、当該２つの担体を排気管３中に直列的に配置した例について説明したが、上流側浄化部５，５Ａの内部又は表面を通過した排ガスを第２浄化部６に導入すれば他の構成でも良い。この場合の排ガス浄化装置の例としては、排気管３中に配置した同一の多孔質状の基材上に上流側浄化部５，５Ａ及び下流側浄化部６の双方を形成するものがある。具体的には、まず当該多孔質基材を形成する構造体の表面（具体的には、当該構造体が形成する複数の孔が排ガスの流路となるが、当該構造体が排ガス流路に臨む面）に下流側浄化部６を層状に担持させ、当該下流側浄化部６の表面（すなわち、下流側浄化部６が排ガス流路に臨む面）に第１浄化部５，５Ａをさらに積層させて上流側浄化部５，５Ａを構成するものがある。すなわち、多孔質基材の構造体の表面には下流側浄化部６及び上流側浄化部５，５Ａによって２つの層が形成される。次にこの場合について図４〜６を用いて説明する。   In each of the above-described embodiments, an example in which the upstream side purification units 5 and 5A and the downstream side purification unit 6 are formed of different carriers (base materials) and the two carriers are arranged in series in the exhaust pipe 3 will be described. However, other configurations may be used as long as the exhaust gas that has passed through or on the surfaces of the upstream purification units 5 and 5A is introduced into the second purification unit 6. As an example of the exhaust gas purifying apparatus in this case, there is one that forms both the upstream side purification unit 5, 5 </ b> A and the downstream side purification unit 6 on the same porous base material arranged in the exhaust pipe 3. Specifically, first, the surface of the structure forming the porous substrate (specifically, a plurality of holes formed by the structure serves as an exhaust gas flow path. The downstream purification unit 6 is supported in a layered manner on the surface facing the first purification unit 5 and 5A on the surface of the downstream purification unit 6 (that is, the surface where the downstream purification unit 6 faces the exhaust gas flow path). There are some which constitute the upstream purification sections 5 and 5A. That is, two layers are formed on the surface of the porous substrate structure by the downstream purification unit 6 and the upstream purification units 5 and 5A. Next, this case will be described with reference to FIGS.

図４は、本発明の第３の実施の形態における上流側浄化部５及び下流側浄化部６の模式構成図である。この図に示す例では、ハニカム状の多孔質担体を利用しており、当該基材（ハニカム基材４１）の表面には、まず、下流側浄化部６であるCO,HC酸化触媒層が形成されている。そして、基材上のCO,HC酸化触媒層６の上には、上流側浄化部５であるNOx吸着層が形成されている。   FIG. 4 is a schematic configuration diagram of the upstream side purification unit 5 and the downstream side purification unit 6 according to the third embodiment of the present invention. In the example shown in this figure, a honeycomb-shaped porous carrier is used, and a CO and HC oxidation catalyst layer as the downstream purification unit 6 is first formed on the surface of the substrate (honeycomb substrate 41). Has been. An NOx adsorption layer that is the upstream purification unit 5 is formed on the CO and HC oxidation catalyst layer 6 on the substrate.

このように排ガス浄化装置を構成すると、多孔質担体中を排ガスが通過する際に、当該排ガスがNOx吸着層５の内部を通過してCO,HC酸化触媒層６に向かって拡散するので、CO,HC酸化触媒層６に接触する前にNOx吸着層５でNOxの濃度が低減される。したがって、第１の実施の形態（図１参照）と同様の効果が期待できる。特に、本実施の形態では、２つの多孔質担体（上流側浄化部５及び下流側浄化部６）を直列配置する必要が無いので、排ガス浄化装置をコンパクト化でき、省スペース化を図ることができるという点がメリットとなる。 図５は、本発明の第４の実施の形態における上流側浄化部５Ａ及び下流側浄化部６の模式構成図であり、図６は、本発明の第５の実施の形態における上流側浄化部５Ｂ及び下流側浄化部６の模式構成図である。   When the exhaust gas purification device is configured in this way, when exhaust gas passes through the porous carrier, the exhaust gas passes through the inside of the NOx adsorption layer 5 and diffuses toward the CO and HC oxidation catalyst layer 6. The NOx concentration is reduced in the NOx adsorption layer 5 before coming into contact with the HC oxidation catalyst layer 6. Therefore, the same effect as that of the first embodiment (see FIG. 1) can be expected. In particular, in the present embodiment, it is not necessary to arrange two porous carriers (upstream purification unit 5 and downstream purification unit 6) in series, so that the exhaust gas purification device can be made compact and space can be saved. The advantage is that it can be done. FIG. 5 is a schematic configuration diagram of the upstream purification unit 5A and the downstream purification unit 6 in the fourth embodiment of the present invention, and FIG. 6 shows the upstream purification unit in the fifth embodiment of the present invention. It is a schematic block diagram of 5B and the downstream purification | cleaning part 6.

図５に示した実施の形態では、ハニカム基材４１上にコーティングしたCO,HC酸化触媒層（下流側浄化部）６の上層に、HCをCOへ転換する触媒層（上流側浄化部）５Ａが形成されている。図６に示した実施の形態では、ハニカム基材４１上にコーティングしたCO,HC酸化触媒層（下流側浄化部）６の上層に、HC吸着成分を含む吸着層（上流側浄化部）５Ｂが形成されている。これらのように排ガス浄化装置を構成することで、第２の実施の形態（図２参照）と同様の効果が期待でき、更に排ガス浄化装置のコンパクト化及び省スペース化を図ることができる。   In the embodiment shown in FIG. 5, a catalyst layer (upstream purification unit) 5A for converting HC into CO is formed on the CO, HC oxidation catalyst layer (downstream purification unit) 6 coated on the honeycomb substrate 41. Is formed. In the embodiment shown in FIG. 6, an adsorption layer (upstream purification unit) 5B containing an HC adsorption component is formed on the CO, HC oxidation catalyst layer (downstream purification unit) 6 coated on the honeycomb substrate 41. Is formed. By configuring the exhaust gas purification apparatus as described above, the same effects as those of the second embodiment (see FIG. 2) can be expected, and further, the exhaust gas purification apparatus can be made compact and space-saving.

なお、図５，６の実施の形態における転換触媒層５Ａ又は吸着層５Ｂの上層にNOx吸着層を形成すると、CO,HC酸化触媒層６におけるNOxによるCO,HC酸化反応の阻害を防ぐことができるので、CO,HC浄化活性をさらに高めることができる。なお、図６のようにHC吸着層５Ｂを設けた場合には、一旦吸着したHCが排ガス温度の上昇によりHC吸着成分から脱離し始める点に留意すべきである。   When the NOx adsorption layer is formed above the conversion catalyst layer 5A or the adsorption layer 5B in the embodiment of FIGS. 5 and 6, it is possible to prevent inhibition of the CO and HC oxidation reaction by NOx in the CO and HC oxidation catalyst layer 6. Therefore, CO and HC purification activity can be further enhanced. It should be noted that when the HC adsorption layer 5B is provided as shown in FIG. 6, HC once adsorbed begins to desorb from the HC adsorption component due to the rise in exhaust gas temperature.

図７は、本発明の第６の実施の形態に係る排ガス浄化装置の模式構成図である。この図に示す排ガス浄化装置は、エンジン１と、エンジン１の下流側に設置された浄化部５０と、浄化部５０の下流側に設けられた尿素吹き込み口５１と、尿素吹き込み口５１の下流側に設置されたNOx浄化触媒５２を備えている。   FIG. 7 is a schematic configuration diagram of an exhaust gas purifying apparatus according to a sixth embodiment of the present invention. The exhaust gas purification apparatus shown in this figure includes an engine 1, a purification unit 50 installed on the downstream side of the engine 1, a urea injection port 51 provided on the downstream side of the purification unit 50, and a downstream side of the urea injection port 51. The NOx purification catalyst 52 is provided.

浄化部５０としては、図４に示した第３の実施の形態に係る多孔質担体が設置されている。すなわち、浄化部５０である多孔質担体には、ハニカム基材の表面にCO,HC酸化触媒層６が形成されており、当該CO,HC酸化触媒層６の上にはNOx吸着層５が形成されている。   As the purification unit 50, the porous carrier according to the third embodiment shown in FIG. 4 is installed. That is, the porous carrier that is the purification unit 50 has the CO and HC oxidation catalyst layer 6 formed on the surface of the honeycomb substrate, and the NOx adsorption layer 5 is formed on the CO and HC oxidation catalyst layer 6. Has been.

NOx浄化触媒５２は、浄化部５０におけるNOx吸着層５から脱離したNOxを還元浄化するためのものである。還元剤としては、排ガス中に残留したCO又はHCが利用可能である。NOx浄化触媒５２としては、例えば、TiO2担体にV2O5を担持した触媒が利用可能である。なお、浄化部５０にNOx吸着層５やNOx吸着材を配置しない場合であっても、浄化部５０を通過した後の排ガス中にNOxが含まれる場合には、NOx浄化触媒５２を設置することで排ガス中のNOxの浄化が可能であることはいうまでもない。 The NOx purification catalyst 52 is for reducing and purifying NOx desorbed from the NOx adsorption layer 5 in the purification unit 50. As the reducing agent, CO or HC remaining in the exhaust gas can be used. As the NOx purification catalyst 52, for example, a catalyst in which V 2 O 5 is supported on a TiO 2 carrier can be used. Even if the NOx adsorbing layer 5 and the NOx adsorbent are not arranged in the purifying unit 50, if NOx is contained in the exhaust gas after passing through the purifying unit 50, the NOx purifying catalyst 52 should be installed. Needless to say, NOx in exhaust gas can be purified.

尿素吹き込み口５１は、排ガス流通方向における浄化部５０とNOx浄化触媒５２の間の位置で排気管３に開口しており、尿素供給源（図示せず）からNOx浄化触媒５２に対して尿素を導入可能に構成されている。ところで、NOx浄化触媒５２に係る還元剤としては、既述のように排ガス中に残留したCO又はHCが利用可能であるが、排ガス中にCO又はHCが残留していない場合又は不十分な場合がある。その場合には、尿素吹き込み口５１からNOx浄化触媒５２に対して尿素を導入することが好ましい。なお、尿素の代わりにアンモニア（NH3）を還元剤として導入しても良い。 The urea inlet 51 opens to the exhaust pipe 3 at a position between the purification unit 50 and the NOx purification catalyst 52 in the exhaust gas circulation direction, and urea is supplied to the NOx purification catalyst 52 from a urea supply source (not shown). It is configured to be installable. By the way, as the reducing agent related to the NOx purification catalyst 52, CO or HC remaining in the exhaust gas can be used as described above, but when CO or HC does not remain in the exhaust gas or when it is insufficient. There is. In that case, it is preferable to introduce urea into the NOx purification catalyst 52 from the urea inlet 51. In addition, ammonia (NH 3 ) may be introduced as a reducing agent instead of urea.

上記のように構成される排ガス浄化装置において、エンジン始動時のように排ガス温度が低い場合（例えば、300℃以下）、浄化部５０に流入する排ガス中のNOxは、浄化部５０中のNOx吸着層５にて吸着され、NOx濃度が低下した排ガス中のCO,HCは浄化部５０のCO,HC酸化触媒層６で浄化される。その後、排ガス温度が高まると、NOx吸着層５のNOx吸着作用は低下するが、CO,HC浄化活性は向上する為、CO,HCは高度に浄化できる。一方で、浄化部５０にて吸着されていたNOxが脱離を始める。しかし、脱離したNOxは、NOx浄化触媒５２で還元浄化されるため、NOxが系外へ放出することを防ぐことができる。なお、還元剤であるCO,HCが不足する場合には、尿素吹き込み口５１を介して排気管３内に尿素を吹き込み、NOx浄化触媒にてNOxを還元浄化することが好ましい。   In the exhaust gas purification apparatus configured as described above, when the exhaust gas temperature is low (for example, 300 ° C. or less) as in the engine start, NOx in the exhaust gas flowing into the purification unit 50 is adsorbed by NOx in the purification unit 50. The CO and HC in the exhaust gas adsorbed by the layer 5 and having a reduced NOx concentration is purified by the CO and HC oxidation catalyst layer 6 of the purification unit 50. Thereafter, when the exhaust gas temperature rises, the NOx adsorption action of the NOx adsorption layer 5 decreases, but the CO and HC purification activity is improved, so that CO and HC can be highly purified. On the other hand, the NOx adsorbed by the purification unit 50 begins to desorb. However, since the desorbed NOx is reduced and purified by the NOx purification catalyst 52, it is possible to prevent NOx from being released out of the system. In addition, when CO and HC which are reducing agents are insufficient, it is preferable to inject urea into the exhaust pipe 3 through the urea inlet 51 and reduce and purify NOx with the NOx purification catalyst.

なお、上記の各実施の形態では、NOx及びHCの濃度を低減する方法として、吸着材や転換触媒を利用する場合について説明したが、この方法に限らず、他の手段でNOx及びHCの濃度を低減しても良い。   In each of the above embodiments, the case where an adsorbent or a conversion catalyst is used as a method for reducing the concentration of NOx and HC has been described. May be reduced.

次に本発明に係る実施例について説明する。   Next, examples according to the present invention will be described.

＜CO,HC浄化触媒調製法＞
本実施例で用いる触媒（基準触媒）は次のように調製した。まず、ベーマイト粉末を電気炉にて大気下にて600℃で5時間の焼成を行うことで得たAl2O3粉末及びアルミナゾルを水へ添加して調製したスラリーをコージェライト製ハニカム（300セル/inc2）にコーティングした後、150℃の熱風を15分間流通させることで乾燥した。更に得られたサンプルを電気炉にて大気下にて600℃で1時間の焼成を行うことでハニカムの見かけの容積1リットルあたり50gのAl2O3をコーティングしたAl2O3コートハニカムを得た。該Al2O3コートハニカムへ、ジニトロジアンミンPt硝酸溶液を含浸し、150℃の熱風を15分間流通させ乾燥後、電気炉にて600℃で1時間焼成した。 <CO and HC purification catalyst preparation method>
The catalyst (reference catalyst) used in this example was prepared as follows. First, a cordierite honeycomb (300 cells) was prepared by adding Al 2 O 3 powder and alumina sol obtained by firing boehmite powder in an electric furnace in the atmosphere at 600 ° C. for 5 hours. / inc 2 ) and then dried by flowing hot air at 150 ° C. for 15 minutes. Further, the obtained sample was fired at 600 ° C. for 1 hour in the air in an electric furnace to obtain an Al 2 O 3 coated honeycomb coated with 50 g of Al 2 O 3 per liter of the apparent volume of the honeycomb. It was. The Al 2 O 3 coated honeycomb was impregnated with a dinitrodiammine Pt nitric acid solution, dried by flowing hot air at 150 ° C. for 15 minutes, and then fired at 600 ° C. for 1 hour in an electric furnace.

以上により、ハニカム1リットルに対してAl2O3が50g、及び元素換算でPtがAl2O3に対して1wt%含有する基準触媒を得た。 Thus, Al 2 O 3 with respect to the honeycomb one liter 50 g, and Pt in terms of element to obtain a reference catalyst containing 1 wt% with respect to Al 2 O 3.

＜触媒性能評価方法＞
触媒の性能を評価する為、次の条件でCO,HC浄化性能試験を行った。容量6c.c.のハニカム触媒を石英ガラス製反応管中に固定した。この反応管を電気炉中に設置した。 <Catalyst performance evaluation method>
In order to evaluate the performance of the catalyst, a CO and HC purification performance test was conducted under the following conditions. A honeycomb catalyst having a capacity of 6 c.c. was fixed in a reaction tube made of quartz glass. This reaction tube was installed in an electric furnace.

ハニカム触媒の前処理として、4.5L/minの10%O2-N2ガスを流通させながら500℃まで昇温させた。その後、触媒温度を50℃付近にまで下げた後、下記の性能評価試験を実施した。反応管に導入される反応ガスは、酸素過剰雰囲気の排ガスを模擬した組成、NOx：300ppm, C3H6：300ppm, CO：300ppm, CO2：6%, O2：10%, H2O：6%, N2：残差とした。このガスを基準ガスとする。 As pretreatment of the honeycomb catalyst, the temperature was raised to 500 ° C. while 4.5 L / min of 10% O 2 —N 2 gas was circulated. Thereafter, the catalyst temperature was lowered to around 50 ° C., and then the following performance evaluation test was performed. The reaction gas introduced into the reaction tube is a composition simulating exhaust gas in an oxygen-excess atmosphere, NOx: 300 ppm, C 3 H 6 : 300 ppm, CO: 300 ppm, CO 2 : 6%, O 2 : 10%, H 2 O : 6%, N 2 : Residual. This gas is used as a reference gas.

下記２式で示すCO浄化率(%)及びHC浄化率(%)によって、触媒のCO,HC浄化性能を見積もった。なお、体積空間速度は45,000/hとした。反応ガスを流通させながら、ガス温度を150℃から500℃にまで加熱制御し、CO,HC浄化性能を測定した。   The CO and HC purification performance of the catalyst was estimated from the CO purification rate (%) and HC purification rate (%) shown in the following two formulas. The volume space velocity was 45,000 / h. While circulating the reaction gas, the gas temperature was controlled from 150 ° C to 500 ° C, and the CO and HC purification performance was measured.

CO浄化率(%)=((触媒に流入したCO濃度)-(触媒から流出したCO濃度))÷(触媒に流入したCO濃度)×100
HC浄化率(%)=((触媒に流入したC3H6濃度)-(触媒から流出したC3H6濃度))÷(触媒に流入したC3H6濃度)×100
＜検討結果：CO浄化活性＞
CO浄化性能の比較データとして、基準ガスからHC（ここでは、C3H6）を除いたガス（HC無しガス）と、基準ガスからNOを除いたガス（NO無しガス）を用いた場合について、基準触媒のCO浄化性能をそれぞれ同様に評価した。図８に基準ガス、HC無しガス、NO無しガスを使用した場合の、基準触媒のCO浄化率を示す。図８において、200℃でのCO浄化率に着目すると、基準ガスでは33%、HC無しガスでは90%、NO無しガスでは99%となった。この結果から排ガス中のNO又はHCの濃度を低減させるとCO,HC浄化触媒のCO浄化率が高まるのは明らかである。 CO purification rate (%) = ((CO concentration flowing into the catalyst)-(CO concentration flowing out from the catalyst)) ÷ (CO concentration flowing into the catalyst) × 100
HC purification rate (%) = ((C 3 H 6 concentration flowing into the catalyst)-(C 3 H 6 concentration flowing out from the catalyst)) ÷ (C 3 H 6 concentration flowing into the catalyst) x 100
<Examination result: CO purification activity>
As comparison data for CO purification performance, when using gas (HC non-gas) excluding HC (here, C 3 H 6 ) from the reference gas and gas excluding NO (NO-free gas) from the reference gas The CO purification performance of the reference catalyst was similarly evaluated. FIG. 8 shows the CO purification rate of the reference catalyst when the reference gas, the gas without HC, and the gas without NO are used. In FIG. 8, focusing on the CO purification rate at 200 ° C., the reference gas was 33%, the gas without HC was 90%, and the gas without NO was 99%. From this result, it is clear that reducing the concentration of NO or HC in the exhaust gas increases the CO purification rate of the CO and HC purification catalyst.

＜検討結果：HC浄化活性＞
HC浄化性能の比較データとして、基準ガスからCOを除いたガス（CO無しガス）と、基準ガスからNOを除いたガス（NO無しガス）を用いた場合について、基準触媒のHC浄化性能を同様に評価した。図９に基準ガス、CO無しガス、NO無しガスを使用した場合の、基準触媒のHC浄化率を示す。図９において200℃でのHC浄化率に着目すると、基準ガスでは0%、CO無しガスでは6%、NO無しガスでは57%となった。この結果から、排ガス中のCO又はNOの濃度を低減させるとCO,HC浄化触媒のHC浄化率が高まるのは明らかである。 <Examination result: HC purification activity>
As comparison data of HC purification performance, the same HC purification performance of the standard catalyst is used for the case of using the gas excluding CO from the reference gas (CO-free gas) and the gas excluding NO from the reference gas (NO-free gas). Evaluated. FIG. 9 shows the HC purification rate of the reference catalyst when the reference gas, the CO-free gas, and the NO-free gas are used. In FIG. 9, focusing on the HC purification rate at 200 ° C., the reference gas was 0%, the CO-free gas was 6%, and the NO-free gas was 57%. From this result, it is clear that reducing the concentration of CO or NO in the exhaust gas increases the HC purification rate of the CO and HC purification catalyst.

＜比較例触媒1の調製法＞
本実施例において比較例となる触媒（比較例触媒１）の調整法について説明する。まず、ベーマイト粉末を電気炉にて大気下にて600℃で5時間の焼成を行うことで得たAl2O3粉末へジニトロジアンミンPt硝酸溶液を含浸し、150℃の熱風を15分間流通させ乾燥後、電気炉にて600℃で1時間焼成した。本手法により、元素換算でPtがAl2O3に対して1wt%含有するPt/Al2O3触媒粉末を得た。得られたPt/Al2O3触媒粉末へアルミナゾルと水へ添加して調製したスラリーをコージェライト製ハニカム（300セル/inc2）にコーティングした後、150℃の熱風を15分間流通させることで乾燥した。更に得られたサンプルを電気炉にて大気下にて600℃で1時間の焼成を行うことでハニカムの見かけの容積1リットルあたり53gのPt/Al2O3触媒粉末をコーティングした比較例触媒1を得た。 <Preparation Method of Comparative Example Catalyst 1>
The adjustment method of the catalyst (comparative example catalyst 1) serving as a comparative example in the present example will be described. First, impregnating the boehmite powder in an electric furnace in the atmosphere at 600 ° C for 5 hours with Al 2 O 3 powder impregnated with dinitrodiammine Pt nitric acid solution and circulating hot air at 150 ° C for 15 minutes After drying, it was baked at 600 ° C. for 1 hour in an electric furnace. By this method, a Pt / Al 2 O 3 catalyst powder containing 1 wt% of Pt with respect to Al 2 O 3 in terms of element was obtained. After coating a slurry prepared by adding alumina sol and water to the obtained Pt / Al 2 O 3 catalyst powder on a cordierite honeycomb (300 cells / inc 2 ), hot air at 150 ° C was circulated for 15 minutes. Dried. Further, the obtained sample was fired in an electric furnace at 600 ° C. for 1 hour in the atmosphere to coat a catalyst of Comparative Example 1 with 53 g of Pt / Al 2 O 3 catalyst powder per liter of apparent volume of the honeycomb Got.

＜実施例触媒1の調製法＞
本実施例に係る触媒（実施例触媒１）の調整法について説明する。まず、Ce-Zr-O(Ce：Zr=1：1 mol比、第一稀元素製)粉末及びアルミナゾルを水へ添加して調製したスラリーを、比較例触媒1にコーティングした後、150℃の熱風を15分間流通させることで乾燥した。更に得られたサンプルを電気炉にて大気下にて600℃で1時間の焼成を行うことでハニカムの見かけの容積1リットルあたり22gのCe-Zr-O粉末を比較例触媒1へコーティングした実施例触媒1を得た。 <Preparation Method of Example Catalyst 1>
A method for adjusting the catalyst according to this example (Example catalyst 1) will be described. First, a slurry prepared by adding Ce-Zr-O (Ce: Zr = 1: 1 mol ratio, made of a first rare element) powder and alumina sol to water was coated on Comparative Example Catalyst 1 and then heated to 150 ° C. It was dried by circulating hot air for 15 minutes. Furthermore, the catalyst of Comparative Example 1 was coated with 22 g of Ce-Zr-O powder per liter of apparent volume of the honeycomb by firing the obtained sample in an electric furnace at 600 ° C. for 1 hour in the atmosphere. Example catalyst 1 was obtained.

＜コート層の効果1＞
比較例触媒1及び実施例触媒1を、実施例1に示した触媒性能評価方法と同じ手法で活性評価を行った。270℃でのCO,HC浄化率の結果を図１０に示す。この図に示すように、比較例触媒1と比較して、Ce-Zr-Oをコートした実施例触媒1はCO,HC浄化率ともに向上した。以上の結果から、CO,HC酸化触触媒へCe-Zr-OをコートするとCO,HC浄化率が高まるのは明らかである。 <Effect of coat layer 1>
Comparative Example 1 and Example Catalyst 1 were evaluated for activity in the same manner as the catalyst performance evaluation method shown in Example 1. The result of the CO and HC purification rate at 270 ° C. is shown in FIG. As shown in this figure, compared to Comparative Example Catalyst 1, Example Catalyst 1 coated with Ce—Zr—O improved both the CO and HC purification rates. From the above results, it is clear that the CO and HC purification rate increases when the CO and HC oxidation catalyst is coated with Ce-Zr-O.

＜比較例触媒２の調製法＞
本実施例で比較例として用いる触媒（比較例触媒２）は、実施例１の基準触媒と同様の手順により調製した。ただし、比較例触媒２では、Al2O3コート量が基準触媒と異なっており、ハニカム1リットルに対してAl2O3を70g、及び元素換算でPtをAl2O3に対して1wt%含有した。 <Preparation Method of Comparative Example Catalyst 2>
The catalyst used as a comparative example in this example (Comparative Example Catalyst 2) was prepared by the same procedure as that for the reference catalyst of Example 1. However, in Comparative Example Catalyst 2, the coating amount of Al 2 O 3 is different from that of the reference catalyst, 70 g of Al 2 O 3 is used for 1 liter of honeycomb, and Pt is 1 wt% with respect to Al 2 O 3 in terms of elements. Contained.

＜実施例触媒２の調製法＞
実施例２では、Ce-Zr-O粉末を比較例触媒1にコーティングして実施例触媒１を得たが、本実施例では、Ce-Zr-O粉末の代わりにモルデナイト粉末(東ソー製)を比較例触媒２にコーティングして触媒（実施例触媒２）を得た。実施例触媒２は、モルデナイト粉末を用いたこと以外は比較例触媒２と同様の手順にて調製されており、ハニカムの見かけの容積1リットルあたり21gのモルデナイト粉末をコーティングした。 <Preparation Method of Example Catalyst 2>
In Example 2, Ce-Zr-O powder was coated on Comparative Example catalyst 1 to obtain Example catalyst 1. In this example, mordenite powder (manufactured by Tosoh) was used instead of Ce-Zr-O powder. Comparative catalyst 2 was coated to obtain a catalyst (Example catalyst 2). Example catalyst 2 was prepared in the same procedure as comparative example catalyst 2 except that mordenite powder was used, and 21 g of mordenite powder was coated per liter of apparent volume of the honeycomb.

＜コート層の効果2＞
比較例触媒2及び実施例触媒2を、実施例1に示した触媒性能評価方法と同じ手法で活性評価を行った。270℃でのCO,HC浄化率の結果を図１１に示す。この図に示すように、本温度では比較例触媒2のCO浄化率が高かったため、実施例触媒2のCO浄化率は比較例触媒2とほぼ同じであったが、HC浄化率は実施例触媒2の方が高かった。以上の結果から、CO,HC酸化触触媒へモルデナイトをコートするとHC浄化率が高まるのは明らかである。 <Effect of coat layer 2>
The activity of Comparative Example Catalyst 2 and Example Catalyst 2 was evaluated by the same method as the catalyst performance evaluation method shown in Example 1. The results of the CO and HC purification rates at 270 ° C. are shown in FIG. As shown in this figure, since the CO purification rate of Comparative Example Catalyst 2 was high at this temperature, the CO purification rate of Example Catalyst 2 was almost the same as that of Comparative Example Catalyst 2, but the HC purification rate was the same as that of Example Catalyst 2. 2 was higher. From the above results, it is clear that the HC purification rate increases when mordenite is coated on the CO and HC oxidation catalyst.

＜CO増加の影響＞
図３に示した第２の実施の形態に示したように、HCをCOへ転換する触媒成分（転換触媒成分５A）を使用すると、HCに由来するCOが生成される為、CO,HC酸化触媒成分（CO,HC酸化触媒６）に接触するCO濃度が高まる。本実施例では当該CO濃度増加の影響について調べた。 <Influence of increased CO>
As shown in the second embodiment shown in FIG. 3, when a catalyst component that converts HC to CO (conversion catalyst component 5A) is used, CO derived from HC is generated, so CO and HC oxidation. The concentration of CO in contact with the catalyst component (CO, HC oxidation catalyst 6) increases. In this example, the influence of the increase in the CO concentration was examined.

基準触媒を用いて、実施例1に示したCO浄化率評価法にてCO浄化率を評価した。基準ガス中のHCが全てCOに転換された場合を模擬した排ガス組成、NOx：300ppm, CO：1200ppm, CO2：6%, O2：10%, H2O：6%, N2：残差、を有するガスを用いてCO浄化率を評価した。このガスを、HC無し-1200ppmCOガスと称する。 Using the reference catalyst, the CO purification rate was evaluated by the CO purification rate evaluation method shown in Example 1. Exhaust gas composition simulating the case where HC of reference gas is converted to all CO, NOx: 300ppm, CO: 1200ppm, CO 2: 6%, O 2: 10%, H 2 O: 6%, N 2: the remaining The CO purification rate was evaluated using a gas having a difference. This gas is referred to as HC-free 1200 ppm CO gas.

図１２に、HC無し-1200ppmCOガスと基準ガスについてCO浄化率を比較したものを示す。HC無し-1200ppmCOガスの場合は、基準ガスと比較して、300℃以下でのCO浄化率が高い。HC無し-1200ppmCOガスの場合、CO濃度は基準ガスよりも高いものの、HCが無い為、HCガスによるCO浄化反応の阻害が生じずCO浄化率が高まったものと考えられる。以上の結果から、排ガス中のHCをCOに転換した後にCO,HC酸化触媒層へ導入するとCO浄化活性が高まるのは明らかである。   FIG. 12 shows a comparison of the CO purification rates for the HC-free 1200 ppm CO gas and the reference gas. In the case of -1200ppmCO gas without HC, the CO purification rate at 300 ° C or less is higher than the reference gas. In the case of -1200ppmCO gas without HC, although the CO concentration is higher than the reference gas, there is no HC, so the inhibition of the CO purification reaction by HC gas does not occur and the CO purification rate is considered to have increased. From the above results, it is clear that the CO purification activity increases when HC in the exhaust gas is converted to CO and then introduced into the CO and HC oxidation catalyst layer.

＜担体量＞
実施例触媒１において、Al2O3担体量を変化させた場合のHC浄化活性を評価した。図１３に、Al2O3担体量を変化させた場合の、270℃における実施例触媒1のHC浄化活性を示した。図１３が示すように、Al2O3担体量はハニカム1Lに対し50g以上300g以下の場合にHC浄化率は50%を超え、高いHC浄化活性を示すことが分かる。 <Amount of carrier>
In Example catalyst 1, the HC purification activity when the amount of Al 2 O 3 support was changed was evaluated. FIG. 13 shows the HC purification activity of Example catalyst 1 at 270 ° C. when the amount of Al 2 O 3 support is changed. As shown in FIG. 13, when the Al 2 O 3 carrier amount is 50 g or more and 300 g or less with respect to the honeycomb 1L, it can be seen that the HC purification rate exceeds 50% and shows high HC purification activity.

なお、本発明は、上記の各実施の形態に限定されるものではなく、その要旨を逸脱しない範囲内の様々な変形例が含まれる。例えば、本発明は、上記の各実施の形態で説明した全ての構成を備えるものに限定されず、その構成の一部を削除したものも含まれる。また、ある実施の形態に係る構成の一部を、他の実施の形態に係る構成に追加又は置換することが可能である。   The present invention is not limited to the above-described embodiments, and includes various modifications within the scope not departing from the gist thereof. For example, the present invention is not limited to the one having all the configurations described in the above embodiments, and includes a configuration in which a part of the configuration is deleted. In addition, part of the configuration according to one embodiment can be added to or replaced with the configuration according to another embodiment.

１…エンジン、１ａ…燃焼室、１ｂ…ピストン、１ｃ…吸気バルブ、１ｄ…排気バルブ、２…燃料噴射装置、３…排気管、４…吸気管、５…上流側浄化部、６…下流側浄化部、９…エンジンコントローラ、５０…浄化部、５１…吹き込み口、５２…NOx浄化触媒   DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Combustion chamber, 1b ... Piston, 1c ... Intake valve, 1d ... Exhaust valve, 2 ... Fuel injection device, 3 ... Exhaust pipe, 4 ... Intake pipe, 5 ... Upstream purification part, 6 ... Downstream side Purification section, 9 ... engine controller, 50 ... purification section, 51 ... inlet, 52 ... NOx purification catalyst

Claims (14)

CO及びHCの酸化反応における化学量論量よりも過剰な酸素雰囲気の排ガスを排出する熱機関の排ガス流路に配置される熱機関の排ガス浄化装置において、
前記排ガス中のNOx及びHCの少なくとも一方の吸着成分又は前記排ガス中のHCの少なくとも一部をCOに転換する転換触媒成分を含む第１浄化部と、
前記第１浄化部を通過した排ガス中のCO又はHCを酸化して浄化する浄化触媒成分を含む第２浄化部とを備えることを特徴とする熱機関の排ガス浄化装置。 In a heat engine exhaust gas purification device disposed in an exhaust gas flow path of a heat engine that exhausts exhaust gas in an oxygen atmosphere that exceeds the stoichiometric amount in the oxidation reaction of CO and HC,
A first purification unit including an adsorption component of at least one of NOx and HC in the exhaust gas or a conversion catalyst component that converts at least a part of HC in the exhaust gas into CO;
An exhaust gas purification apparatus for a heat engine, comprising: a second purification unit including a purification catalyst component that oxidizes and purifies CO or HC in the exhaust gas that has passed through the first purification unit. 請求項１に記載の熱機関の排ガス浄化装置において、
前記第１浄化部及び第２浄化部は同一の基材に担持されており、
前記第１浄化部は、前記担体上の前記第２浄化部上に積層されていることを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to claim 1,
The first purification unit and the second purification unit are carried on the same base material,
The exhaust gas purification apparatus for a heat engine, wherein the first purification unit is stacked on the second purification unit on the carrier. 請求項１に記載の熱機関の排ガス浄化装置において、
前記第２浄化部は、前記排ガスの流通方向において前記第１担体の下流側に配置されていることを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to claim 1,
The exhaust gas purification apparatus for a heat engine, wherein the second purification unit is disposed on the downstream side of the first carrier in the flow direction of the exhaust gas. 請求項１から３のいずれかに記載の熱機関の排ガス浄化装置において、
前記第１浄化部には前記NOx吸着成分が含まれており、
当該吸着成分は、Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まないことを特徴とする熱機関の排ガス浄化装置。 In the exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 3,
The first purification unit contains the NOx adsorbing component,
The exhaust gas purification apparatus for a heat engine, wherein the adsorbed component does not substantially contain Pt, Pd, Rh, Au, Ir, Ru, and Os. 請求項１から４のいずれかに記載の熱機関の排ガス浄化装置において、
前記第２浄化部は、無機化合物の多孔質担体に担持されており、
当該多孔質担体は、Pt,Pd,Rh,Au,Ir,Ru及びOsから選ばれた少なくとも1種の触媒活性成分をさらに担持しており、
前記多孔質担体が、Al,Ce,Si,Ti及びZrから選ばれた少なくとも1種を含むことを特徴とする熱機関の排ガス浄化装置。 In the exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 4,
The second purification unit is supported on a porous carrier of an inorganic compound,
The porous carrier further carries at least one catalytically active component selected from Pt, Pd, Rh, Au, Ir, Ru and Os,
An exhaust gas purification apparatus for a heat engine, wherein the porous carrier contains at least one selected from Al, Ce, Si, Ti, and Zr. 請求項1から５のいずれかに記載の熱機関の排ガス浄化装置において、
前記第１浄化部には前記NOx吸着成分が含まれており、
当該吸着成分が、Ce,Zr,La,Al,Si及びTiから選ばれた少なくとも1種を含むことを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 5,
The first purification unit contains the NOx adsorbing component,
An exhaust gas purification apparatus for a heat engine, wherein the adsorbing component contains at least one selected from Ce, Zr, La, Al, Si, and Ti. 請求項1から６のいずれかに記載の熱機関の排ガス浄化装置において、
前記第１浄化部は前記NOx吸着成分を含んだNOx吸着層を有し、
前記当該NOx吸着層が、ゼオライト構造を有することを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 6,
The first purification unit has a NOx adsorption layer containing the NOx adsorption component,
The exhaust gas purification apparatus for a heat engine, wherein the NOx adsorption layer has a zeolite structure. 請求項1から７のいずれかに記載の熱機関の排ガス浄化装置において、
前記第１浄化部には、前記転換触媒成分が含まれており、
当該転換触媒成分は、Pt,Pd,Rh,Au,Ir,Ru及びOsを実質的に含まず、Mn,Fe,Co,Ni,Cu及びAgから選ばれた少なくとも1種を含むことを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 7,
The first purification unit includes the conversion catalyst component,
The conversion catalyst component is substantially free of Pt, Pd, Rh, Au, Ir, Ru and Os, and contains at least one selected from Mn, Fe, Co, Ni, Cu and Ag. Exhaust gas purification device for heat engine. 請求項１から８のいずれかに記載の熱機関の排ガス浄化装置において、
前記第２浄化部を通過した排ガス中のNOxを浄化する浄化触媒成分を含む第３浄化部をさらに備えることを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 8,
An exhaust gas purification apparatus for a heat engine, further comprising a third purification unit including a purification catalyst component that purifies NOx in the exhaust gas that has passed through the second purification unit. 請求項1から９のいずれかに記載の熱機関の排ガス浄化装置において、
熱機関の始動時に、前記第２浄化部に流入する排ガスの温度が所定温度に高まるまでの時間を短縮するための温度上昇手段をさらに備えることを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 9,
An exhaust gas purification apparatus for a heat engine, further comprising a temperature raising means for shortening a time until the temperature of the exhaust gas flowing into the second purification unit rises to a predetermined temperature when the heat engine is started. 請求項１０に記載の熱機関の排ガス浄化装置において、
前記温度上昇手段は、前記熱機関でリタード燃焼又はポスト墳射を行うための制御手段であることを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to claim 10,
The exhaust gas purification apparatus for a heat engine, wherein the temperature raising means is a control means for performing retarded combustion or post-spraying in the heat engine. 請求項５のみに従属させたが良いか。
請求項５に記載の熱機関の排ガス浄化装置において、
前記多孔質担体は、基材上に担持され、当該基材1Lに対し50g以上300g以下含まれることを特徴とする熱機関の排ガス浄化装置 Should I make it dependent only on claim 5?
The exhaust gas purification apparatus for a heat engine according to claim 5,
The exhaust gas purifying device for a heat engine, wherein the porous carrier is supported on a base material and is contained in an amount of 50 g to 300 g with respect to the base material 1L 請求項１から１２のいずれかに記載の熱機関の排ガス浄化装置において、
前記第２浄化部に流入する排ガスは常に、CO及びHCの酸化反応における化学量論量よりも過剰な酸素雰囲気であることを特徴とする熱機関の排ガス浄化装置。 The exhaust gas purification apparatus for a heat engine according to any one of claims 1 to 12,
The exhaust gas purification apparatus for a heat engine, characterized in that the exhaust gas flowing into the second purification unit is always in an oxygen atmosphere that is in excess of the stoichiometric amount in the oxidation reaction of CO and HC. 無機化合物の多孔質担体と、当該多孔質担体上に担持されたPt,Pd,Rh,Au,Ir,Ru及びOsから選ばれた少なくとも1種の触媒活性成分とを有し、前記多孔質担体が、Al,Ce,Si,Ti及びZrから選ばれた少なくとも1種を含むCO,HC浄化触媒を用いた排ガス浄化方法において、
前記CO,HC浄化触媒へ排ガスが接触する前に、排ガス中のNOx又はHCの濃度を低下させることを特徴とする排ガス浄化方法。 A porous carrier of an inorganic compound and at least one catalytically active component selected from Pt, Pd, Rh, Au, Ir, Ru and Os supported on the porous carrier, the porous carrier In the exhaust gas purification method using a CO, HC purification catalyst containing at least one selected from Al, Ce, Si, Ti and Zr,
An exhaust gas purification method comprising reducing the concentration of NOx or HC in the exhaust gas before the exhaust gas contacts the CO, HC purification catalyst.
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