JP2006305524A - Sulfur oxide absorber and exhaust gas cleaning apparatus - Google Patents

Sulfur oxide absorber and exhaust gas cleaning apparatus Download PDF

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JP2006305524A
JP2006305524A JP2005134256A JP2005134256A JP2006305524A JP 2006305524 A JP2006305524 A JP 2006305524A JP 2005134256 A JP2005134256 A JP 2005134256A JP 2005134256 A JP2005134256 A JP 2005134256A JP 2006305524 A JP2006305524 A JP 2006305524A
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oxide
absorbent
exhaust gas
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sulfur
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JP4962753B2 (en
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Kiyoshi Yamazaki
清 山崎
Yukikazu Kato
千和 加藤
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Toyota Central Res & Dev Lab Inc
株式会社豊田中央研究所
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<P>PROBLEM TO BE SOLVED: To increase the absorption amount of SOx and increase the retaining capacity of SOx in a rich atmosphere at a lower temperature region and suppress emission. <P>SOLUTION: An exhaust gas cleaning apparatus comprises a carrier which is comprised of a main oxide having a spinnel structure and a sub oxide comprising at least either iron oxide or nickel oxide and a noble metal carried on the carrier. The main oxide has a high specific surface area and a strong base point so that the main iron oxide has many base points and absorbs a large amount of SOx in a lean atmosphere. The sub iron oxide reacts with H<SB>2</SB>S and becomes to a metal sulfide in a temperature region lower than 600 °C. Thus, the discharge of H<SB>2</SB>S is suppressed in the rich atmosphere and the absorption amount of SOx is further increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、硫黄酸化物をよく吸収できる硫黄酸化物吸収材と、その硫黄酸化物吸収材を用いた排ガス浄化装置に関する。   The present invention relates to a sulfur oxide absorbent that can absorb sulfur oxide well, and an exhaust gas purification apparatus using the sulfur oxide absorbent.
燃費の低減によるCO2 の排出の抑制を目的として、自動車エンジンなどでは酸素過剰の燃料リーン雰囲気で燃焼させることが行われている。そして燃料リーン雰囲気下でもNOx の還元浄化を効率よく行う排ガス浄化用触媒として、NOx 吸蔵還元型触媒、NOx 選択還元型触媒が開発され、実用に供されている。また排ガス中のHCをさらに効率よく酸化浄化するために、HC酸化触媒も広く用いられている。 In order to suppress CO 2 emissions by reducing fuel consumption, automobile engines and the like are burned in an oxygen-rich fuel lean atmosphere. As an exhaust gas purifying catalyst that efficiently performs NO x reduction purification even in a fuel lean atmosphere, a NO x storage reduction catalyst and a NO x selective reduction catalyst have been developed and put into practical use. Further, in order to more efficiently oxidize and purify HC in exhaust gas, HC oxidation catalysts are also widely used.
NOx 吸蔵還元型触媒は、多孔質担体と、多孔質担体に担持された貴金属と、アルカリ金属、アルカリ土類金属及び希土類元素から選ばれ多孔質担体に担持されたNOx 吸蔵材とよりなり、常時は酸素過剰のリーン雰囲気で燃焼させ間欠的にストイキ〜リッチ雰囲気となるように混合気の比率を制御する燃焼システムの排気系に用いられている。 The NO x storage reduction catalyst comprises a porous support, a noble metal supported on the porous support, and a NO x storage material supported on the porous support selected from alkali metals, alkaline earth metals and rare earth elements. It is used for an exhaust system of a combustion system in which the ratio of the air-fuel mixture is controlled so that it is always burned in a lean atmosphere with excess oxygen and intermittently becomes a stoichiometric to rich atmosphere.
ところが燃料リーン雰囲気の排ガス中には、燃料中の硫黄に起因するSO2 が含まれている。そのためこのような排ガスがNOx 吸蔵還元型触媒に触れると、貴金属によってSO2 がSO3 あるいはSO4 などの硫黄酸化物(以下、SOx という)となり、NOx 吸蔵材とSOx とが反応して安定な硫酸塩が生成し、NOx 吸蔵材のNOx 吸蔵能が低下するという問題がある。この現象は、硫黄被毒と称されている。 However, the exhaust gas in the fuel lean atmosphere contains SO 2 due to sulfur in the fuel. Therefore, when such exhaust gas touches the NO x storage reduction catalyst, SO 2 becomes sulfur oxide such as SO 3 or SO 4 (hereinafter referred to as SO x ) by the noble metal, and the NO x storage material and SO x react. Thus, there is a problem that a stable sulfate is generated and the NO x storage capacity of the NO x storage material is lowered. This phenomenon is called sulfur poisoning.
またNOx 選択還元型触媒やHC酸化触媒においては、担持されている触媒活性をもつ触媒金属がSOx で覆われて活性が低下する不具合が生じ、また触媒金属上で硫黄成分がさらに酸化されてSOx が生じるため上記不具合がますます促進されるという問題もある。しかもサルフェートの排出量が増大するという不具合もあった。 In addition, in NO x selective reduction type catalysts and HC oxidation catalysts, there is a problem that the supported catalytic metal having catalytic activity is covered with SO x and the activity is lowered, and the sulfur component is further oxidized on the catalytic metal. There is also a problem that the above defects are further promoted because SO x is generated. Moreover, there is a problem that the amount of sulfate discharged increases.
そこでSOx による上記不具合を抑制する手段の一つとして、SOx 吸収材の利用が検討されている。このようなSOx 吸収材として、例えば特開昭57−162645号公報には、アルミナの表面上に単一層として分散する酸化ランタン層を形成したものが開示されている。また特開平05−146675号公報には、シリカ、ランタナなどのアルミナ安定剤とアルカリ金属などの活性成分を含有するアルミナからなるSOx 吸着剤が開示されている。 Therefore, the use of SO x absorbents has been studied as one of the means for suppressing the above-mentioned problems caused by SO x . As such an SO x absorbent, for example, JP-A-57-162645 discloses a lanthanum oxide layer dispersed as a single layer on the surface of alumina. Japanese Patent Application Laid-Open No. 05-146675 discloses an SO x adsorbent comprising an alumina stabilizer such as silica and lantana and alumina containing an active component such as an alkali metal.
このようなSOx 吸収材を上記した排ガス浄化用触媒の上流側に配置すれば、排ガス中のSOx はSOx 吸収材に吸収されるので、SOx 濃度が低減された排ガスがNOx 吸蔵還元型触媒あるいはHC酸化触媒に接触するため、上記した硫黄被毒を抑制することができる。 By arranging such a SO x absorber on the upstream side of the exhaust gas purifying catalyst as described above, since the SO x in the exhaust gas is absorbed in the SO x absorbent, the exhaust gas SO x concentration is reduced the NO x storage Since it contacts the reduction catalyst or the HC oxidation catalyst, the above-mentioned sulfur poisoning can be suppressed.
しかしながら、SOx 吸収材においては、SOx の吸収量が飽和するとそれ以上のSOx の吸収が困難となる。そこで排ガス雰囲気を還元成分過剰のリッチ雰囲気とし、SOx を吸収したSOx 吸収材を分解してSOx を放出させ、SOx 吸収能を再生する再生処理を行う必要がある。ところが上記した従来のSOx 吸収材では、リッチ雰囲気のガス中において 600〜 700℃の高温で加熱する処理が必要であり、現実の排ガス中での再生処理は困難であった。そのため再生処理を別に行わざるを得ず、工数及びコストが多大であるという問題があった。 However, in the SO x absorbent, if the SO x absorption amount is saturated, it becomes difficult to absorb more SO x . Therefore, it is necessary to perform a regeneration process in which the exhaust gas atmosphere is made rich with excess reducing components, the SO x absorbent that has absorbed SO x is decomposed to release SO x , and the SO x absorption capacity is regenerated. However, the above-described conventional SO x absorbent requires a heat treatment at a high temperature of 600 to 700 ° C. in a gas in a rich atmosphere, and the regeneration treatment in actual exhaust gas is difficult. Therefore, there is a problem that the regeneration process must be performed separately, and the man-hours and costs are enormous.
そこで本願出願人は、特開2001−293366において、 MgO・nAl2O3(nは 0.8以上で 1.1未満)からなるスピネル担体に、Ptなどの貴金属を担持したSOx 吸収材を提案している。このSOx 吸収材によれば、SOx の吸収性に優れている。また高温下での使用後も比表面積が高く、高温耐久性に優れるので、現実の排ガス中での再生処理が可能となる。したがって再生処理の回数を削減でき、工数及びコストを大幅に低減することができる。 Therefore, the applicant of the present application has proposed an SO x absorbent in which a noble metal such as Pt is supported on a spinel carrier made of MgO · nAl 2 O 3 (n is 0.8 or more and less than 1.1) in JP-A-2001-293366. . According to the SO x absorbent is excellent in the absorption of SO x. In addition, since the specific surface area is high after use under high temperature and the high temperature durability is excellent, regeneration treatment in actual exhaust gas is possible. Therefore, the number of regeneration processes can be reduced, and man-hours and costs can be greatly reduced.
しかしながら特開2001−293366に開示されたSOx 吸収材においても、SOx の吸収量が十分に多くないために、排ガス中での再生処理の頻度を高める必要があり燃費などに不具合がある。またリッチ雰囲気では吸収されたSOx が分解してSOx 吸収材から放出されるが、その温度域は比較的低い温度である。一方、NOx 吸蔵材とSOx との反応は、低温ほど起こりやすいということが明らかとなっている。 However, even in the SO x absorbent disclosed in JP-A-2001-293366, the amount of SO x absorbed is not sufficiently large, so that it is necessary to increase the frequency of regeneration treatment in exhaust gas, and there is a problem in fuel consumption. In a rich atmosphere, absorbed SO x is decomposed and released from the SO x absorbent, but the temperature range is relatively low. On the other hand, it is clear that the reaction between the NO x storage material and SO x is more likely to occur at lower temperatures.
そのため上流側にSOx 吸収材を配置し、その下流側にNOx 吸蔵還元型触媒を配置した排ガス浄化装置にあっては、リッチ雰囲気でSOx 吸収材から放出されたSOx が、下流側に存在するNOx 吸蔵還元型触媒のNOx 吸蔵材と反応し、リーン雰囲気ばかりでなくリッチ雰囲気においても硫黄被毒が生じるという問題があった。このリッチ雰囲気における硫黄被毒は、触媒床温度が 650℃以上では起こらないが、約 600℃以下で起こることがわかっている。
特開昭57−162645号 特開平05−146675号 特開2001−293366号
Therefore, in the exhaust gas purification apparatus in which the SO x absorbent is disposed on the upstream side and the NO x storage reduction catalyst is disposed on the downstream side, the SO x released from the SO x absorbent in the rich atmosphere is downstream. reacts with the NO x storage material of the NO x storage reduction catalyst present, even in a rich atmosphere not only lean atmosphere has a problem that the sulfur poisoning occurs. It has been found that sulfur poisoning in this rich atmosphere does not occur at catalyst bed temperatures above 650 ° C, but occurs at temperatures below about 600 ° C.
JP 57-162645 JP 05-146675 JP 2001-293366
本発明は、上記事情に鑑みてなされたものであり、SOx の吸収量を増大させるとともに、低温域のリッチ雰囲気におけるSOx の保持性を高めて放出を抑制することを解決すべき課題とする。 The present invention has been made in view of the above circumstances, and it is an object to be solved to suppress SOx emission by increasing SO x absorption and enhancing SO x retention in a low temperature rich atmosphere. To do.
上記課題を解決する本発明のSOx 吸収材の特徴は、MO・nAl2O3(0.8≦n<1.1 、Mはアルカリ土類金属)の組成のスピネル構造の主酸化物と、酸化鉄及び酸化ニッケルの少なくとも一方からなる副酸化物と、よりなる担体と、担体に担持された貴金属と、からなることにある。主酸化物において、MはMgであることが特に好ましい。 A feature of the SO x absorbent of the present invention that solves the above problems is that a main oxide having a spinel structure having a composition of MO · nAl 2 O 3 (0.8 ≦ n <1.1, M is an alkaline earth metal), iron oxide, and It consists of a suboxide made of at least one of nickel oxide, a carrier made of nickel oxide, and a noble metal supported on the carrier. In the main oxide, M is particularly preferably Mg.
また本発明の排ガス浄化装置の特徴は、本発明のSOx 吸収材と、NOx 吸蔵還元型触媒と、からなり、SOx 吸収材が排ガス上流側に配置され、NOx 吸蔵還元型触媒がSOx 吸収材より排ガス下流側に配置されていることにある。 Further, the exhaust gas purification apparatus of the present invention is characterized by comprising the SO x absorbent of the present invention and a NO x storage reduction catalyst, the SO x absorbent is disposed upstream of the exhaust gas, and the NO x storage reduction catalyst It exists in being arranged in the exhaust gas downstream side from the SO x absorbent.
本発明のSOx 吸収材によれば、MO・nAl2O3(0.8≦n<1.1 、Mはアルカリ土類金属)の組成のスピネル構造の主酸化物を用いている。この主酸化物は高い比表面積を有するとともに強い塩基点を有しているので塩基点の数が多く、リーン雰囲気で多量のSOx を吸収することができ、SOx 吸収量が格段に増大する。 According to the SO x absorbent of the present invention, a main oxide having a spinel structure having a composition of MO · nAl 2 O 3 (0.8 ≦ n <1.1, M is an alkaline earth metal) is used. Since this main oxide has a high specific surface area and strong base points, it has a large number of base points, can absorb a large amount of SO x in a lean atmosphere, and the SO x absorption amount is greatly increased. .
またリッチ雰囲気では吸収されていたSOx が還元されてH2S が生成する。従来のSOx 吸収材ではこのH2S が排出されるため、その分SOx 吸収量が低い値となっていた。しかし本発明のSOx 吸収材は、酸化鉄及び酸化ニッケルの少なくとも一方からなる副酸化物を有している。この副酸化物は、 600℃以下の温度域でH2S と反応して金属硫化物となり、これによってリッチ雰囲気におけるH2S の排出が抑制されるため、SOx 吸収量がさらに増大する。 Also in a rich atmosphere is SO x which is absorbed is reduced H 2 S is produced. In the conventional SO x absorbent, since this H 2 S is discharged, the amount of SO x absorbed is low accordingly. However, the SO x absorbent of the present invention has a sub-oxide composed of at least one of iron oxide and nickel oxide. This sub-oxide reacts with H 2 S in the temperature range of 600 ° C. or less to become a metal sulfide, and this suppresses the emission of H 2 S in a rich atmosphere, thereby further increasing the SO x absorption amount.
そして生成した金属硫化物は、リッチ雰囲気であっても 650℃以上であれば容易に分解してH2S を放出し、副酸化物に戻ってH2S 吸収能が再生される。したがってトータルでのSOx 吸収能の再生性能に優れている。 The generated metal sulfide is easily decomposed and releases H 2 S at a temperature of 650 ° C. or higher even in a rich atmosphere, and returns to the secondary oxide to regenerate the H 2 S absorption capacity. Therefore, the total regeneration performance of SO x absorption capacity is excellent.
したがって本発明のSOx 吸収材を有する本発明の排ガス浄化装置によれば、リーン雰囲気では排ガス中のSOx の大部分がSOx 吸収材に吸収されるので、NOx 吸蔵還元型触媒の硫黄被毒を確実に抑制することができる。そしてリッチ雰囲気においてNOx 吸蔵還元型触媒の硫黄被毒が生じやすい 600℃以下の温度域では、SOx 吸収材からのH2S の放出が抑制されているので、リッチ雰囲気におけるNOx 吸蔵還元型触媒の硫黄被毒を抑制することができる。 Therefore, according to the exhaust gas purification apparatus of the present invention having the SO x absorbent of the present invention, in the lean atmosphere, most of the SO x in the exhaust gas is absorbed by the SO x absorbent, so that the sulfur of the NO x storage reduction type catalyst Poisoning can be reliably suppressed. In a rich atmosphere, sulfur poisoning of the NO x storage reduction catalyst is likely to occur. In the temperature range below 600 ° C, H 2 S release from the SO x absorbent is suppressed, so NO x storage reduction in a rich atmosphere. Sulfur poisoning of the type catalyst can be suppressed.
本発明のSOx 吸収材は、主酸化物及び副酸化物からなる担体と、担体に担持された貴金属と、からなる。主酸化物は、MO・nAl2O3(0.8≦n<1.1 、Mはアルカリ土類金属)の組成の実質的にスピネル構造を有するものである。アルカリ土類金属Mとしては、Ba、Mg、Caなどが例示されるが、安定したスピネル構造を形成するMgが特に好ましい。 The SO x absorbent of the present invention comprises a support composed of a main oxide and a sub oxide, and a noble metal supported on the support. The main oxide has a substantially spinel structure with a composition of MO.nAl 2 O 3 (0.8 ≦ n <1.1, M is an alkaline earth metal). Examples of the alkaline earth metal M include Ba, Mg, and Ca. Mg that forms a stable spinel structure is particularly preferable.
副酸化物とは、酸化鉄及び酸化ニッケルの少なくとも一方をいう。主酸化物と副酸化物との混合比率は、重量比で副酸化物/主酸化物= 0.2/ 9.8〜5/5の範囲とするのが好ましい。副酸化物の含有量がこの範囲を超えるとリーン雰囲気でのSOx 吸収能が低下し、副酸化物の含有量がこの範囲より少ないとリッチ雰囲気でのSOx 吸収能が低下する。 The sub-oxide refers to at least one of iron oxide and nickel oxide. The mixing ratio of the main oxide and the sub oxide is preferably in the range of sub oxide / main oxide = 0.2 / 9.8 to 5/5 in weight ratio. When the content of the sub oxide exceeds this range, the SO x absorption capacity in the lean atmosphere is reduced, and when the content of the sub oxide is less than this range, the SO x absorption capacity in the rich atmosphere is reduced.
貴金属は、Pt、Pd、Rh、Irなどを用いることができる。SO2 の酸化活性が高いPtが特に好ましい。また貴金属の担持量は、金属種によって異なるが、例えばPtの場合には、SOx 吸収材の 100重量部当たり 0.2〜3重量部とするのが好ましい。なお貴金属は、主酸化物及び副酸化物のどらに担持されていてもよい。 As the noble metal, Pt, Pd, Rh, Ir or the like can be used. Pt having high SO 2 oxidation activity is particularly preferred. The amount of noble metal supported varies depending on the metal species. For example, in the case of Pt, it is preferably 0.2 to 3 parts by weight per 100 parts by weight of the SO x absorbent. The noble metal may be supported on either the main oxide or the sub oxide.
本発明のSOx 吸収材は、粉末状、ペレット状、ハニカム状、フォーム状などの形状で用いることができる。例えばハニカム状のSOx 吸収材は、コージェライトなどから形成されたハニカム基材のセル壁表面に主酸化物と副酸化物からなるコート層を形成し、そのコート層に貴金属を担持することで製造することができる。 The SO x absorbent of the present invention can be used in the form of powder, pellet, honeycomb, foam or the like. For example, a honeycomb-shaped SO x absorbent is formed by forming a coat layer made of a main oxide and a sub oxide on the surface of a cell wall of a honeycomb substrate made of cordierite, and carrying a noble metal on the coat layer. Can be manufactured.
本発明のSOx 吸収材は、それ単独で使用することもできるが、その排ガス下流側にNOx 吸蔵還元型触媒を配置した排ガス浄化装置として用いることが特に好ましい。この本発明の排ガス浄化装置では、リーン雰囲気の排ガスがSOx 吸収材に接触することで、排ガス中のSO2 は貴金属によってSOx に酸化されSOx 吸収材に吸収される。本発明のSOx 吸収材はSOx 吸収量が多いので、排ガス中のSOx はほとんど全部が吸収され、下流側に流出するのが確実に抑制される。したがって下流側のNOx 吸蔵還元型触媒の硫黄被毒が抑制され、高いNOx 浄化率が発現される。 Although the SO x absorbent of the present invention can be used alone, it is particularly preferable to use it as an exhaust gas purification apparatus in which an NO x storage reduction catalyst is disposed on the exhaust gas downstream side. In the exhaust gas purifying apparatus of the present invention, when the exhaust gas in a lean atmosphere comes into contact with the SO x absorbent, SO 2 in the exhaust gas is oxidized to SO x by the noble metal and absorbed by the SO x absorbent. Since the SO x absorbent of the present invention has a large amount of SO x absorption, almost all of the SO x in the exhaust gas is absorbed and the outflow to the downstream side is reliably suppressed. Therefore, sulfur poisoning of the downstream NO x storage reduction catalyst is suppressed, and a high NO x purification rate is expressed.
NOx 吸蔵還元型触媒は、アルミナ、チタニア、ジルコニア、セリア、シリカ、あるいはこれらの複数種からなる複合酸化物などから選ばれる多孔質酸化物を担体とし、それにPt、Rh、Pdなどの貴金属と、アルカリ金属、アルカリ土類金属及び希土類元素から選ばれるNOx 吸蔵材とを担持したものであり、従来用いられているNOx 吸蔵還元型触媒を用いることができる。 The NO x storage reduction type catalyst uses a porous oxide selected from alumina, titania, zirconia, ceria, silica, or a composite oxide composed of a plurality of these as a support, and a noble metal such as Pt, Rh, and Pd. , an alkali metal is obtained by carrying the the NO x storage material selected from alkaline earth metals and rare earth elements, can be used NO x storage-and-reduction type catalyst conventionally used.
SOx 吸収材の硫黄脱離温度は、NOx 吸蔵還元型触媒の硫黄脱離温度より高いことが望ましい。このように構成することで、下流側のNOx 吸蔵還元型触媒でNOx を還元浄化するためにストイキ又はリッチ雰囲気とされた時の温度は、SOx 吸収材の硫黄脱離温度より低くすることができる。したがってSOx 吸収材からSOx は放出されないので、リッチ雰囲気におけるNOx 吸蔵還元型触媒の硫黄被毒を確実に防止することができる。またSOx 吸収材のSOx 吸収能を回復するためにリッチ雰囲気とする際には、硫黄被毒したNOx 吸蔵材の分解温度を超えた温度となるため、SOx 吸収材のSOx 吸収能が回復するとともに、硫黄被毒したNOx 吸蔵材のNOx 吸蔵能も回復する。 The sulfur desorption temperature of the SO x absorbent is preferably higher than the sulfur desorption temperature of the NO x storage reduction catalyst. With this configuration, the temperature when the stoichiometric or rich atmosphere is used to reduce and purify NO x with the downstream NO x storage reduction catalyst is lower than the sulfur desorption temperature of the SO x absorbent. be able to. Therefore, since SO x is not released from the SO x absorbent, sulfur poisoning of the NO x storage reduction catalyst in a rich atmosphere can be reliably prevented. Further, when the rich atmosphere to restore the SO x absorption capability of the SO x absorbent, since the temperature above the decomposition temperature of the NO x storage material in which sulfur poisoning, SO x absorption of the SO x absorbent As the performance recovers, the NO x storage capacity of the sulfur poisoned NO x storage material also recovers.
SOx 吸収材の硫黄脱離温度は、NOx 吸蔵還元型触媒の硫黄脱離温度より20℃以上高いことが好ましく、50℃以上高いことがさらに望ましい。またSOx 吸収材のSOx 吸収能を回復するためのリッチ再生処理の温度も、NOx 吸蔵還元型触媒の硫黄脱離温度より20℃以上高くすることが好ましく、50℃以上高くすることがさらに望ましい。 The sulfur desorption temperature of the SO x absorbent is preferably 20 ° C. or more, more preferably 50 ° C. or more higher than the sulfur desorption temperature of the NO x storage reduction catalyst. The temperature of the rich regeneration process for recovering SO x absorption capability of the SO x absorbent is also preferably possible to increase 20 ° C. or higher than the sulfur desorption temperature of the NO x storage reduction catalyst, be higher than 50 ° C. More desirable.
このようにSOx 吸収材の硫黄脱離温度を高くするには、スピネル構造の主酸化物と、酸化鉄及び酸化ニッケルの少なくとも一方からなる副酸化物とを用いることで、容易に達成することができる。 Thus, in order to increase the sulfur desorption temperature of the SO x absorbent, it is easily achieved by using a main oxide having a spinel structure and a sub-oxide comprising at least one of iron oxide and nickel oxide. Can do.
以下、実施例及び比較例により本発明を具体的に説明する。   Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(実施例1)
酢酸マグネシウム 107gと、酢酸アルミニウム 379gとを1800mlのイオン交換水に溶解してす溶液を調製した。この水溶液に25%アンモニア水 650gを加えて沈殿物を生成させ、濾過、洗浄後、大気中にて 850℃で5時間焼成してMgAl2O4(主酸化物)を調製した。この主酸化物は、 MgO・nAl2O3で表すとn=1であり、比表面積は 104m2/gで、XRDによる構造解析の結果、MgAl2O4相のみのスピネル構造であった。
Example 1
A solution was prepared by dissolving 107 g of magnesium acetate and 379 g of aluminum acetate in 1800 ml of ion-exchanged water. 650 g of 25% aqueous ammonia was added to this aqueous solution to form a precipitate, which was filtered and washed, and then calcined in the atmosphere at 850 ° C. for 5 hours to prepare MgAl 2 O 4 (main oxide). When this main oxide is represented by MgO.nAl 2 O 3 , n = 1, the specific surface area is 104 m 2 / g, and as a result of structural analysis by XRD, it was a spinel structure of only MgAl 2 O 4 phase.
得られた主酸化物粉末19gと、酸化ニッケル(II)粉末1gをイオン交換水中で分散混合し、そこへ所定量のジニトロジアンミン白金硝酸溶液を加え、蒸発・乾固後、大気中にて 300℃で3時間焼成し、SOx 吸収材粉末を得た。このSOx 吸収材粉末は、主酸化物が95重量部と、酸化ニッケル(NiO )が5重量部と、Ptが2重量部と、から構成されている。これを圧粉成型した後、破砕して 1.0mm〜 1.7mmのペレット状のSOx 吸収材とした。 19 g of the obtained main oxide powder and 1 g of nickel oxide powder (1 g) are dispersed and mixed in ion-exchanged water, and a predetermined amount of dinitrodiammine platinum nitrate solution is added thereto. After evaporation and drying, 300 g in air. Firing at 3 ° C. for 3 hours gave an SO x absorbent powder. This SO x absorbent powder is composed of 95 parts by weight of the main oxide, 5 parts by weight of nickel oxide (NiO 2), and 2 parts by weight of Pt. This was compacted and then crushed to obtain a pellet-shaped SO x absorbent of 1.0 mm to 1.7 mm.
(実施例2)
実施例1と同様の主酸化物粉末19gと、酸化ニッケル(II)粉末に代えて酸化鉄(III) 粉末1gと、を分散混合したこと以外は実施例1と同様にして、ペレット状のSOx 吸収材を調製した。SOx 吸収材の組成は、主酸化物が95重量部と、酸化鉄(Fe2O3 )が5重量部と、Ptが2重量部と、から構成されている。
(Example 2)
A pellet-shaped SO in the same manner as in Example 1 except that 19 g of the main oxide powder similar to that in Example 1 and 1 g of iron (III) powder instead of nickel oxide (II) powder were dispersed and mixed. x Absorbent was prepared. The composition of the SO x absorbent is composed of 95 parts by weight of the main oxide, 5 parts by weight of iron oxide (Fe 2 O 3 ), and 2 parts by weight of Pt.
(比較例1)
酸化ニッケル(II)粉末を混合することなく、実施例1と同様の主酸化物粉末20gのみを用いたこと以外は実施例1と同様にして、ペレット状のSOx 吸収材を調製した。SOx 吸収材の組成は、主酸化物が 100重量部と、Ptが2重量部と、から構成されている。
(Comparative Example 1)
A pellet-shaped SO x absorbent was prepared in the same manner as in Example 1 except that only 20 g of the main oxide powder similar to that in Example 1 was used without mixing the nickel (II) oxide powder. The composition of the SO x absorbent is composed of 100 parts by weight of the main oxide and 2 parts by weight of Pt.
(比較例2)
主酸化物粉末19g及び酸化ニッケル(II)粉末1gに代えて、γ-Al2O3粉末(比表面積 220m2/g)20gを用いたこと以外は実施例1と同様にして、ペレット状のSOx 吸収材を調製した。SOx 吸収材の組成は、γ-Al2O3が 100重量部と、Ptが2重量部と、から構成されている。
(Comparative Example 2)
In the same manner as in Example 1 except that 20 g of γ-Al 2 O 3 powder (specific surface area 220 m 2 / g) was used instead of 19 g of the main oxide powder and 1 g of nickel (II) oxide powder, A SO x absorbent was prepared. The composition of the SO x absorbent is composed of 100 parts by weight of γ-Al2O3 and 2 parts by weight of Pt.
<試験・評価>
実施例及び比較例の各SOx 吸収材に対して、以下のS吸収試験、再生試験を実施し、SOx 吸収能力と再生能力を評価した。
<Test and evaluation>
For each SO x absorbing materials of Examples and Comparative Examples, the following S absorption test, carried out reproduction test was to evaluate the reproduction ability and SO x absorption capacity.
S吸収試験は、各SOx 吸収材を3g採取し、処理温度 550℃にて、表1に示すリーンモデルガスとリッチモデルガスを各々流量 30000ml/分で、リーンモデルガスを 120秒、リッチモデルガスを3秒、交互に41分間流通させた。このときの各SOx 吸収材へのS通過量は、それぞれ3.28モルである。 In the S absorption test, 3 g of each SO x absorbent was sampled, the processing temperature was 550 ° C, the lean model gas and rich model gas shown in Table 1 were each flowed at 30000 ml / min, the lean model gas was 120 seconds, and the rich model. The gas was allowed to flow alternately for 41 minutes for 3 seconds. The amount of S passing through each SO x absorbent at this time is 3.28 mol.
その後、各SOx 吸収材に付着しているS量であるS付着量を化学分析により測定し、S通過量に対する割合( 100×S付着量/S通過量)をS吸収率とした。結果をそれぞれ表3に示す。 Thereafter, the S adhesion amount, which is the S amount adhering to each SO x absorbent, was measured by chemical analysis, and the ratio to the S passage amount (100 × S adhesion amount / S passage amount) was taken as the S absorption rate. The results are shown in Table 3, respectively.
再生試験は、S吸収試験を行った各SOx 吸収材に対して、処理温度 700℃にて、表2に示すリッチモデルガスを流量 30000ml/分で10分間流通させた。 In the regeneration test, the rich model gas shown in Table 2 was circulated at a flow rate of 30000 ml / min for 10 minutes at a treatment temperature of 700 ° C. with respect to each SO x absorbent subjected to the S absorption test.
その後S付着量を化学分析により測定し、次式によりS再生率を算出した。結果をそれぞれ表3に示す。   Thereafter, the S adhesion amount was measured by chemical analysis, and the S regeneration rate was calculated by the following formula. The results are shown in Table 3, respectively.
再生率=(1−再生試験後S付着量/S吸収試験後S付着量)× 100       Regeneration rate = (1−S adhesion amount after regeneration test / S adhesion amount after S absorption test) × 100
表3から、各実施例のSOx 吸収材は、S吸収試験後のS付着量が各比較例に比べて多いことが明らかである。すなわち各実施例のSOx 吸収材は、高いSOx 吸収性能を有し、SOx 保持能力にも優れていることがわかる。 From Table 3, it is clear that the SOx absorbent material of each example has a larger amount of S adhesion after the S absorption test than the respective comparative examples. That is, it can be seen that the SO x absorbent material of each Example has high SO x absorption performance and excellent SO x retention capability.
また再生試験後の再生率は、いずれのSOx 吸収材もほぼ同等の値を示している。すなわち各実施例のSOx 吸収材は、上記のように 700℃で再生試験を行うことで、初期と同等のSOx 吸収性能を示すまで再生することができる。 Further, the regeneration rate after the regeneration test shows almost the same value for all SO x absorbents. That is, the SO x absorbent of each example can be regenerated until the SO x absorption performance equivalent to the initial value is exhibited by performing a regeneration test at 700 ° C. as described above.
(実施例3)
本実施例の排ガス浄化装置を図1に示す。排ガス上流側には本発明のSOx 吸収材1が配置され、その下流側にNOx 吸蔵還元型触媒2が配置されている。SOx 吸収材1は、実施例1のSOx 吸収材を用いている。またNOx 吸蔵還元型触媒2は、以下のようにして調製した。
(Example 3)
The exhaust gas purification apparatus of the present embodiment is shown in FIG. The SO x absorbent 1 of the present invention is disposed on the exhaust gas upstream side, and the NO x storage reduction catalyst 2 is disposed on the downstream side thereof. The SO x absorbent 1 uses the SO x absorbent of Example 1. The NO x storage reduction catalyst 2 was prepared as follows.
市販のγ-Al2O3粉末(比表面積 220m2/g) 100gと、ZrO2−TiO2固溶体粉末(比表面積 100m2/g) 100gとをイオン交換水と混合し、そこへ所定量のジニトロジアンミン白金硝酸溶液を加え、蒸発・乾固後、大気中にて 300℃で3時間焼成してPt担持触媒粉末を調製した。このPt担持触媒粉末は、γ-Al2O3が 100重量部と、ZrO2−TiO2固溶体が 100重量部と、Ptが2重量部と、から構成されている。 100 g of commercially available γ-Al 2 O 3 powder (specific surface area 220 m 2 / g) and 100 g of ZrO 2 —TiO 2 solid solution powder (specific surface area 100 m 2 / g) are mixed with ion-exchanged water, and a predetermined amount thereof is mixed therewith. Dinitrodiammineplatinum nitrate solution was added, evaporated and dried, and then calcined in the atmosphere at 300 ° C. for 3 hours to prepare a Pt-supported catalyst powder. This Pt-supported catalyst powder is composed of 100 parts by weight of γ-Al 2 O 3 , 100 parts by weight of ZrO 2 —TiO 2 solid solution, and 2 parts by weight of Pt.
このPt担持触媒粉末に、酢酸バリウム、酢酸カリウム及び酢酸リチウムの各水溶液を用いてBa、K、Liを含浸担持させ、乾燥後、大気中大気中にて 300℃で3時間焼成してNOx 吸蔵還元型触媒粉末を調製した。このNOx 吸蔵還元型触媒粉末は、γ-Al2O3が 100重量部と、ZrO2−TiO2固溶体が 100重量部と、Ptが2重量部と、Baが 0.2モルと、Kが 0.1モルと、Liが 0.1モルと、から構成されている。 In the Pt-supported catalyst powder, barium acetate, with aqueous solutions of potassium acetate and lithium acetate Ba, K, impregnated carrying Li, dried, and calcined 3 hours at 300 ° C. in air at atmospheric NO x An occlusion reduction type catalyst powder was prepared. The NO x storage-and-reduction type catalyst powder includes a gamma-Al 2 O 3 is 100 parts by weight, and ZrO 2 -TiO 2 solid solution 100 parts by weight, and Pt is 2 parts by weight, and the Ba 0.2 mol, K 0.1 And 0.1 mol of Li.
これを圧粉成型した後、破砕して 1.0mm〜 1.7mmのペレット状のNOx 吸蔵還元型触媒とした。そして実施例1のSOx 吸収材ペレット3gを排ガス上流側に配置してSOx 吸収材1を構成し、得られたNOx 吸蔵還元型触媒ペレット7gをその下流側に配置してNOx 吸蔵還元型触媒2を構成した。 After this was green compact to obtain a pellet-shaped NO x storage-and-reduction type catalyst crushed and 1.0 mm to 1.7 mm. Then, the SO x absorbent pellets 3g of Example 1 are arranged on the exhaust gas upstream side to constitute the SO x absorbent 1, and the obtained NO x storage reduction type catalyst pellet 7g is arranged on the downstream side to store the NO x storage. A reduced catalyst 2 was constructed.
(実施例4)
SOx 吸収材1として、実施例2のSOx 吸収材ペレットを用いたこと以外は実施例3と同様である。
Example 4
As SO x absorber 1, except for using SO x absorber pellets of Example 2 were the same as in Example 3.
(比較例3)
SOx 吸収材1として、比較例1のSOx 吸収材ペレットを用いたこと以外は実施例3と同様である。
(Comparative Example 3)
As SO x absorber 1, except for using SO x absorber pellets of Comparative Example 1 is the same as in Example 3.
(比較例4)
SOx 吸収材1として、比較例2のSOx 吸収材ペレットを用いたこと以外は実施例3と同様である。
(Comparative Example 4)
Example 3 is the same as Example 3 except that the SO x absorbent pellet of Comparative Example 2 was used as the SO x absorbent 1.
(比較例5)
SOx 吸収材1を配置せず、実施例3と同様のNOx 吸蔵還元型触媒ペレットのみを10g配置して、比較例5の排ガス浄化装置とした。
(Comparative Example 5)
The SO x absorbent 1 was not disposed, and only 10 g of the same NO x occlusion reduction type catalyst pellet as in Example 3 was disposed to obtain an exhaust gas purification apparatus of Comparative Example 5.
<試験・評価>
各実施例及び各比較例の排ガス浄化装置に対し、前述したS吸収試験と再生試験を実施した。その後、以下のNOx 浄化活性試験を行い、NOx 浄化活性を評価した。
<Test and evaluation>
The above-described S absorption test and regeneration test were performed on the exhaust gas purifying apparatuses of each Example and each Comparative Example. Thereafter, the following NO x purification activity test was performed to evaluate the NO x purification activity.
NOx 浄化活性試験は、各排ガス浄化装置に対して表4に示すリーンモデルガスとリッチモデルガスを各々入りガス温度 400℃、流量 30000ml/分で、リーンモデルガスを 120秒、リッチモデルガスを3秒、交互に流通させた。このときの入りガスNOx 濃度及び出ガスNOx 濃度の時間平均値をそれぞれ測定し、NOx 浄化率を算出した。結果を表5に示す。 In the NOx purification activity test, the lean model gas and the rich model gas shown in Table 4 were entered into each exhaust gas purification device at a gas temperature of 400 ° C and a flow rate of 30000 ml / min, the lean model gas was 120 seconds, and the rich model gas was 3 Circulated alternately for seconds. The time average values of the incoming gas NO x concentration and the outgoing gas NO x concentration at this time were measured, respectively, and the NO x purification rate was calculated. The results are shown in Table 5.
S吸収試験、再生試験及びNOx 浄化活性試験を行った各排ガス浄化装置に対し、もう一度S吸収試験と再生試験を実施した。その後、同様のNOx 浄化活性試験を行い、結果を2回目NOx 浄化率として表5に示す。 An S absorption test and a regeneration test were performed once again on each exhaust gas purification device that had been subjected to the S absorption test, the regeneration test, and the NO x purification activity test. Thereafter, the same NO x purification activity test was conducted, and the results are shown in Table 5 as the second NO x purification rate.
各実施例の排ガス浄化装置は、比較例5と比べて1回目、2回目共に高いNOx 浄化率を示している。すなわち実施例1及び実施例2のSOx 吸収材をNOx 吸蔵還元型触媒の上流側に配置することで、NOx 浄化性能が大きく向上することが明らかである。これは、S吸収試験時にSOx 吸収材が排ガス中のSOx を吸収することで、NOx 吸蔵還元型触媒の硫黄被毒が抑制されるためである。 The exhaust gas purifying apparatus of each example shows a higher NO x purification rate both in the first time and the second time than in Comparative Example 5. That is, it is clear that the NO x purification performance is greatly improved by disposing the SO x absorbents of Examples 1 and 2 on the upstream side of the NO x storage reduction catalyst. This is because the SO x absorbent absorbs SO x in the exhaust gas when S absorption test, because the sulfur poisoning of the NO x storage reduction catalyst can be suppressed.
また各実施例の排ガス浄化装置は、比較例3、4と比較しても高いNOx 浄化性能を示している。その序列は表3に示したS吸収率と一致することから、各実施例の排ガス浄化装置が高いNOx 浄化性能を示すのは、高いSOx 吸収性能を有するSOx 吸収材を使用していることに起因している。 Further, the exhaust gas purifying apparatus of each example shows high NO x purification performance even compared with Comparative Examples 3 and 4. Since the order is consistent with the S absorption rate shown in Table 3, the exhaust gas purifying apparatus of each example exhibits high NO x purification performance using an SO x absorbent having high SO x absorption performance. This is due to the fact that
本発明の一実施例の排ガス浄化装置を示すブロック図である。It is a block diagram which shows the exhaust gas purification apparatus of one Example of this invention.
符号の説明Explanation of symbols
1:SOx 吸収材 2:NOx 吸蔵還元型触媒 1: SO x absorbent 2: NO x storage reduction catalyst

Claims (3)

  1. MO・nAl2O3(0.8≦n<1.1 、Mはアルカリ土類金属)の組成のスピネル構造の主酸化物と、酸化鉄及び酸化ニッケルの少なくとも一方からなる副酸化物と、よりなる担体と、
    該担体に担持された貴金属と、からなることを特徴とする硫黄酸化物吸収材。
    A main oxide having a spinel structure with a composition of MO.nAl 2 O 3 (0.8 ≦ n <1.1, where M is an alkaline earth metal), a sub-oxide comprising at least one of iron oxide and nickel oxide, and a carrier comprising ,
    A sulfur oxide absorbent comprising: a noble metal supported on the carrier.
  2. 前記主酸化物において、MはMgである請求項1に記載の硫黄酸化物吸収材。   The sulfur oxide absorbent according to claim 1, wherein M is Mg in the main oxide.
  3. 請求項1又は請求項2に記載の硫黄酸化物吸収材と、NOx 吸蔵還元型触媒と、からなり、該硫黄酸化物吸収材が排ガス上流側に配置され、該NOx 吸蔵還元型触媒が該硫黄酸化物吸収材より排ガス下流側に配置されていることを特徴とする排ガス浄化装置。 The sulfur oxide absorbent according to claim 1 or 2 and a NO x storage reduction catalyst, wherein the sulfur oxide absorbent is disposed on the exhaust gas upstream side, and the NO x storage reduction catalyst An exhaust gas purification apparatus, which is disposed on the exhaust gas downstream side of the sulfur oxide absorbent.
JP2005134256A 2005-05-02 2005-05-02 Sulfur oxide absorber and exhaust gas purification device Expired - Fee Related JP4962753B2 (en)

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WO2008123628A1 (en) * 2007-04-03 2008-10-16 Toyota Jidosha Kabushiki Kaisha Exhaust purification device for internal combustion engine
RU2485332C1 (en) * 2009-07-23 2013-06-20 Тойота Дзидося Кабусики Кайся Ice exhaust cleaning system

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JPH11319481A (en) * 1998-03-27 1999-11-24 Degussa Huels Ag Storage material for sulfur oxide, its production and its use

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JPH11319481A (en) * 1998-03-27 1999-11-24 Degussa Huels Ag Storage material for sulfur oxide, its production and its use

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008123628A1 (en) * 2007-04-03 2008-10-16 Toyota Jidosha Kabushiki Kaisha Exhaust purification device for internal combustion engine
JPWO2008123628A1 (en) * 2007-04-03 2010-07-15 トヨタ自動車株式会社 Exhaust gas purification device for internal combustion engine
JP4697305B2 (en) * 2007-04-03 2011-06-08 トヨタ自動車株式会社 Exhaust gas purification device for internal combustion engine
US8156731B2 (en) 2007-04-03 2012-04-17 Toyota Jidosha Kabushiki Kaisha Exhaust purification device of internal combustion engine
RU2485332C1 (en) * 2009-07-23 2013-06-20 Тойота Дзидося Кабусики Кайся Ice exhaust cleaning system

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