JP3536311B2 - NOx removal method and NOx removal catalyst in automobile exhaust gas - Google Patents
NOx removal method and NOx removal catalyst in automobile exhaust gasInfo
- Publication number
- JP3536311B2 JP3536311B2 JP12720293A JP12720293A JP3536311B2 JP 3536311 B2 JP3536311 B2 JP 3536311B2 JP 12720293 A JP12720293 A JP 12720293A JP 12720293 A JP12720293 A JP 12720293A JP 3536311 B2 JP3536311 B2 JP 3536311B2
- Authority
- JP
- Japan
- Prior art keywords
- cao
- exhaust gas
- catalyst
- nox
- nox removal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000003054 catalyst Substances 0.000 title claims description 46
- 238000000034 method Methods 0.000 title claims description 12
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 40
- 239000002245 particle Substances 0.000 claims description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 229910002596 FexO Inorganic materials 0.000 claims description 15
- 239000002131 composite material Substances 0.000 claims description 15
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 238000010304 firing Methods 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 7
- 235000019738 Limestone Nutrition 0.000 claims description 4
- 239000006028 limestone Substances 0.000 claims description 4
- 230000004907 flux Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000011812 mixed powder Substances 0.000 claims description 2
- 239000011230 binding agent Substances 0.000 claims 1
- 239000007789 gas Substances 0.000 description 42
- 230000000694 effects Effects 0.000 description 10
- 239000000203 mixture Substances 0.000 description 8
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 229910052763 palladium Inorganic materials 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 238000003915 air pollution Methods 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 150000001721 carbon Chemical class 0.000 description 2
- 239000011362 coarse particle Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 238000005469 granulation Methods 0.000 description 2
- 230000003179 granulation Effects 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 230000001603 reducing effect Effects 0.000 description 2
- 238000003746 solid phase reaction Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車排ガス中のＮＯ
ｘ（窒素酸化物）を効率良く除去する方法及びＮＯｘ除
去触媒に関するものである。The present invention relates to NO in exhaust gas of automobiles.
The present invention relates to a method for efficiently removing x (nitrogen oxide) and a NOx removal catalyst.
【０００２】[0002]
【従来の技術】近年における自動車数の増加は著しいも
のがあり、それにつれて自動車排ガスによる大気汚染は
深刻な問題となっている。自動車排ガスのうち大気汚染
の主原因になっているのはＮＯｘであり、その低減対策
として、排ガス管内にＮＯｘ分解触媒を配置し、それに
よりＮＯｘを分解除去してから排出する方法が採用され
ている。2. Description of the Related Art The number of automobiles has increased remarkably in recent years, and as a result, air pollution caused by automobile exhaust gas has become a serious problem. The main cause of air pollution in automobile exhaust gas is NOx. As a measure for reducing NOx, a method of disposing NOx decomposing catalyst in the exhaust gas pipe, decomposing and removing NOx and then discharging it is adopted. There is.
【０００３】ところでＮＯｘ除去触媒として現在汎用さ
れているのは、多孔質のアルミナ・ボールに白金パラジ
ウムを付着させたものであり、この触媒は優れたＮＯｘ
分解作用を有しているが、貴金属を主たる触媒成分とす
るものであるから、材料コストが高くつき、経済性に難
がある。By the way, what is currently widely used as a NOx removing catalyst is one in which platinum palladium is attached to porous alumina balls, and this catalyst is an excellent NOx.
Although it has a decomposing action, it uses a noble metal as the main catalyst component, so that the material cost is high and the economy is low.
【０００４】そこで、ゼオライトの様な安価な触媒や窒
素プラズマを使用する新しい窒素酸化物分解法も研究さ
れているが、ＮＯｘ除去効果が不十分であるため実用化
されるまでに至っていない。Therefore, a new nitrogen oxide decomposing method using an inexpensive catalyst such as zeolite or nitrogen plasma has been studied, but it has not been put to practical use because the effect of removing NOx is insufficient.
【０００５】[0005]
【発明が解決しようとする課題】本発明は上記の様な事
情に着目してなされたものであって、その目的は、安価
な素材を使用し、自動車排ガス中のＮＯｘを効率良く分
解除去する方法及びＮＯｘ分解触媒を提供しようとする
ものである。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is to efficiently decompose and remove NOx in automobile exhaust gas by using an inexpensive material. The present invention seeks to provide a method and a NOx decomposition catalyst.
【０００６】[0006]
【課題を解決するための手段】上記課題を解決すること
のできた本発明に係るＮＯｘ除去方法の構成は、ＣａＯ
含有量が１０〜３０重量％であり、且つＣａＯと鉄酸化
物以外の成分が９重量％以下であるＣａＯ・ＦｅｘＯ系
複合酸化物（ただしＦｅＯを含む）を、３００〜７００
℃の温度域にある自動車エンジンの排ガス管内に配置す
るものであり、前記ＣａＯ・ＦｅｘＯ系複合酸化物の使
用量の下限を、１分間のガス排出量１ｍ3当たり０．３
２ｋｇとして、排ガス中のＮＯｘを除去するところに要
旨を有するものである。そして本発明では、この様なＮ
Ｏｘ除去触媒についても定めるものであって、その構成
は、石灰石と鉄酸化物とが、焼成後の成分で、ＣａＯ含
有量が１０〜３０重量％、ＣａＯと鉄酸化物以外の成分
含有量が９重量％以下となる様に配合されると共に、粒
径０．１ｍｍ以下のものが８０重量％以上である混合粉
末を、結合融液と共に混練し成形した後、１０００〜１
２００℃で加熱処理したものであるところに要旨を有す
るものである。The structure of the NOx removing method according to the present invention which has been able to solve the above problems is CaO.
The content of CaO / FexO-based composite oxide (including FeO) having a content of 10 to 30 wt% and a content of components other than CaO and iron oxide of 9 wt% or less is 300 to 700.
It is arranged in an exhaust gas pipe of an automobile engine in a temperature range of ℃, and the lower limit of the amount of the CaO / FexO-based composite oxide used is 0.3 per 1 m 3 of gas emission per minute.
The main point is to remove NOx in the exhaust gas with 2 kg. And in the present invention, such N
The Ox removing catalyst is also defined, and the composition is such that limestone and iron oxide are the components after firing, the CaO content is 10 to 30% by weight, and the content of components other than CaO and iron oxide is After being mixed so as to have a content of 9% by weight or less, and having a particle diameter of 0.1 mm or less in an amount of 80% by weight or more, a mixed powder is kneaded and molded with a bonding melt, and then 1000 to 1
It has the gist of being heat-treated at 200 ° C.
【０００７】[0007]
【作用】本発明は、上記の様に成分組成の特定されたＣ
ａＯ・ＦｅｘＯ系複合酸化物（ただしＦｅＯを含む）を
ＮＯｘ分解触媒として使用し、これを自動車の駆動時に
所定の温度域に達するエンジン排ガス管内に所定量配置
することによって、排ガス中のＮＯｘを効率良く分解除
去するものであり、それにより極めて安価な触媒素材
で、貴金属系触媒を用いた従来法に匹敵し若しくはこれ
を上回るＮＯｘ除去効果を得ることができる。In the present invention, the C having the specified composition as described above is used.
By using aO / FexO-based composite oxide (including FeO) as a NOx decomposition catalyst, and arranging this in a predetermined amount in the engine exhaust gas pipe that reaches a predetermined temperature range when driving an automobile, NOx in exhaust gas can be efficiently produced. Since it is well decomposed and removed, it is possible to obtain a NOx removal effect comparable to or higher than the conventional method using a noble metal catalyst with an extremely inexpensive catalyst material.
【０００８】まず本発明で用いられるＮＯｘ除去触媒
は、ＣａＯ含有量が１０〜３０重量％で且つＣａＯと鉄
酸化物以外の成分が９重量％以下（従って、鉄酸化物と
しての含有量が６１〜９０重量％）のＣａＯ・ＦｅｘＯ
系複合酸化物（ただしＦｅＯを含む）よりなるものであ
り、この複合酸化物を自動車エンジンの排ガス管内に配
置しておくと、その還元作用によってＮＯｘを還元除去
するか、或はＮＯｘを分解除去する作用を発揮する。First, the NOx removing catalyst used in the present invention has a CaO content of 10 to 30% by weight and a content of components other than CaO and iron oxide of 9% by weight or less (hence, the content of iron oxide is 61% by weight). ~ 90 wt%) CaO / FexO
It is composed of a complex oxide (including FeO). If this complex oxide is placed in the exhaust gas pipe of an automobile engine, NOx is reduced and removed by its reducing action, or NOx is decomposed and removed. Exert the action.
【０００９】従って本発明に係るＮＯｘ除去法とは、こ
れらの触媒活性を利用して自動車排ガス中のＮＯｘを還
元除去するか、或は分解除去するものである。尚Ｆｅｘ
ＯについてはＦｅＯ，Ｆｅ3Ｏ4（ＦｅＯ・Ｆｅ2Ｏ3），
Ｆｅ2Ｏ3の如何は問わないが、ＦｅＯを必ず含む。ｘは
ＦｅとＯの原子比を示し、ＦｅＯを含まない場合も考慮
すれば理論的には０．６７〜１．００の範囲となるが、
本発明のＦｅｘＯはＦｅＯを必ず含むものである。Therefore, the NOx removing method according to the present invention utilizes these catalytic activities to reduce or remove NOx in automobile exhaust gas or decompose and remove it. Fex
Regarding O, FeO, Fe 3 O 4 (FeO · Fe 2 O 3 ),
Fe 2 O 3 may be used, but FeO is always included. x represents an atomic ratio of Fe and O, and theoretically falls within the range of 0.67 to 1.00 considering the case where FeO is not included.
The FexO of the present invention always contains FeO.
【００１０】このとき、ＣａＯ・ＦｅｘＯ系複合酸化物
のＣａＯ含有量が多過ぎても少な過ぎてもＮＯｘ除去効
果は弱くなり、またＣａＯとＦｅｘＯ以外の成分（特に
脈石成分として混入することの多いＳｉＯ2）が９重量
％を超える場合も満足なＮＯｘ除去効果が得られなくな
る。この理由は、上記成分組成の要件を満たすＣａＯ・
ＦｅｘＯ主体の２元系若しくは多元系組成においてそれ
らの成分組成が共晶組成に近く、加熱処理によってＣａ
Ｏ・ＦｅｘＯ系複合組織が形成され易くなるためと考え
られる。At this time, if the CaO content of the CaO / FexO composite oxide is too large or too small, the NOx removing effect becomes weak, and components other than CaO and FexO (particularly as gangue components are mixed). Even if a large amount of SiO 2 ) exceeds 9% by weight, a satisfactory NOx removal effect cannot be obtained. The reason for this is that CaO.
In the binary or multi-component composition mainly composed of FexO, the component composition thereof is close to the eutectic composition, and Ca
It is considered that this is because the O / FexO-based composite structure is easily formed.
【００１１】上記ＣａＯ・ＦｅｘＯ系複合酸化物をＮＯ
ｘ除去触媒として自動車排ガスのＮＯｘ除去を行なうに
当たっては、この複合酸化物を自動車エンジンの排ガス
管内に、１分間のガス排出量１ｍ3当たり０．３２ｋｇ
以上配置すると共に、温度を３００℃以上に高めること
が必要となる。ちなみに図１は、排ガス量当たりの触媒
量と脱硝率の関係を調べた結果を示したものである。但
し、実験条件は下記の通りとした。The above CaO / FexO-based composite oxide is NO
When removing NOx from automobile exhaust gas as a x removal catalyst, 0.32 kg of this composite oxide is put into the exhaust gas pipe of an automobile engine per 1 m 3 of gas emission per minute.
In addition to the above arrangement, it is necessary to raise the temperature to 300 ° C. or higher. Incidentally, FIG. 1 shows the results of examining the relationship between the catalyst amount per exhaust gas amount and the denitration rate. However, the experimental conditions were as follows.
【００１２】（実験条件）
触媒組成：23.0％ＣａＯ−76.1％ＦｅｘＯ−0.9 ％Ｓｉ
Ｏ2複合酸化物
触媒粒径：平均粒径約５ｍｍ
温度 ：約３００℃(Experimental conditions) Catalyst composition: 23.0% CaO-76.1% FexO-0.9% Si
O 2 composite oxide catalyst particle size: average particle size of about 5 mm Temperature: about 300 ° C.
【００１３】（脱硝率の測定法）
図３に略示する模擬実験装置を使用し、自動車エンジン
排ガス発生部を模擬するＮＯｘ含有ガス発生部１で、Ｎ
Ｏｘ、空気、ＣＯ、ＣＯ2等を適切な比率で混合し、こ
の混合ガスを導管２を通して封管（るつぼ）３に供給す
る。ノズル４の先端から放出された上記混合ガスは、ヒ
ーター５によって所定温度に加熱されている触媒６に触
れる。７は熱電対を示す。触媒６上で還元または接触分
解を受けたガスは導管９から排出され、一部はガスサン
プルバッグ８に捕集されつつＮＯｘ測定器１０によって
ＮＯｘ濃度の測定が行なわれる。導管２から投入される
ＮＯｘ量（ＣNO IN）と導管からの排出ＮＯｘ量（ＣNO
OUT）から、下記計算式に基づいて脱硝率（ＥＬ）を求
めた。尚、図１中破線は実測値からの計算値、実線は同
一粒径に表面積補正した計算値を表わす。(Measurement Method of Denitration Rate) A NOx-containing gas generating section 1 simulating an automobile engine exhaust gas generating section was used to generate N by using a simulated experimental apparatus schematically shown in FIG.
Ox, air, CO, CO 2 and the like are mixed in an appropriate ratio, and this mixed gas is supplied to the sealed tube (crucible) 3 through the conduit 2. The mixed gas discharged from the tip of the nozzle 4 contacts the catalyst 6 heated to a predetermined temperature by the heater 5. 7 indicates a thermocouple. The gas reduced or catalytically decomposed on the catalyst 6 is discharged from the conduit 9, and a part of the gas is collected in the gas sample bag 8, and the NOx measuring device 10 measures the NOx concentration. Amount of NOx is introduced from the conduit 2 (C NO IN) and the NOx emission amount from the conduit (C NO
The denitration rate (EL) was calculated from OUT ) based on the following calculation formula. The broken line in FIG. 1 represents the calculated value from the actual measurement value, and the solid line represents the calculated value in which the surface area was corrected to the same particle size.
【００１４】 [0014]
【００１５】この図からも明らかである様に、排ガス量
当たりの触媒量を０．３２kg／m3／minに設定してやれ
ば、従来の白金系ＮＯｘ除去触媒と同程度以上のＮＯｘ
除去効果を確保できることが分かる。As is clear from this figure, if the amount of catalyst per amount of exhaust gas is set to 0.32 kg / m 3 / min, NOx at the same level or higher as that of the conventional platinum-based NOx removal catalyst will be obtained.
It can be seen that the removal effect can be secured.
【００１６】また図２は、上記実験法に準拠し、加熱温
度を変えたときの脱硝率に与える影響を調べた結果を示
したものであり、この図からも明らかである様に、満足
のいく脱硝率を得るには温度を３００℃以上、より好ま
しくは４００℃以上にすべきであることが分かる。但し
本発明はあくまでも自動車エンジン排ガスのＮＯｘ除去
を目的とするものであり、自動車エンジン用の排ガス管
材料は７００℃以上では使用できず、また排ガス温度が
７００℃以上に高まることはないので、本発明では該Ｎ
Ｏｘ除去触媒が配設される排ガス管の到達温度域を３０
０〜７００℃の範囲と定めた。Further, FIG. 2 shows the results of examining the effect on the denitration rate when the heating temperature is changed, based on the above-mentioned experimental method. As is clear from this figure, satisfactory results are obtained. It is understood that the temperature should be 300 ° C. or higher, more preferably 400 ° C. or higher in order to obtain a high denitration rate. However, the present invention is intended only to remove NOx from automobile engine exhaust gas, and exhaust gas pipe materials for automobile engines cannot be used above 700 ° C, and the exhaust gas temperature does not rise above 700 ° C. In the invention, the N
The ultimate temperature range of the exhaust gas pipe where the Ox removal catalyst is installed is set to 30
The range was set to 0 to 700 ° C.
【００１７】上記の様なＮＯｘ除去触媒は、焼成後の成
分として前述の要件を満たす原料、たとえば石灰石と鉄
鉱石を、粒径０．１ｍｍ以下のものが８０重量％以上を
占める様に微粉砕し、これを水等の結合融剤と共に均一
に混練した後任意の形状に成形し、これを１０００〜１
２００℃で加熱焼成することによって得ることができ
る。形状は粒状、ペレット状、短管状、ハニカム状の如
く比表面積を効率的に高め排ガスとの接触有効面積を拡
大し得るものであればどの様なものであってもよいが、
成形が簡単で且つ十分な比表面積が得られるのは、直径
が２〜１０ｍｍ程度の粒状物であり、この様な粒状物は
たとえば皿型造粒機によって容易に成形することができ
る。In the NOx removing catalyst as described above, raw materials satisfying the above-mentioned requirements as components after firing, such as limestone and iron ore, are finely pulverized so that 80% by weight or more of particles having a particle diameter of 0.1 mm or less occupy. Then, this is uniformly kneaded with a binding flux such as water and then molded into an arbitrary shape.
It can be obtained by heating and baking at 200 ° C. The shape may be any as long as it can efficiently increase the specific surface area such as a granular shape, a pellet shape, a short tubular shape, and a honeycomb shape and can expand the effective contact area with exhaust gas,
It is a granular material having a diameter of about 2 to 10 mm that can be easily molded and has a sufficient specific surface area, and such a granular material can be easily molded by, for example, a dish type granulator.
【００１８】このとき、原料粉末が直径０．１ｍｍを超
える粗粒が２０重量％超えるものである場合は、比表面
積の大きい成形体の成形が困難になったり、或は成形す
ることができたとしても焼結体が脆弱なものとなり、短
期間のうちに粉化して目詰りを起こしＮＯｘ除去触媒と
しての持続性に欠けるものとなる。こうした意味から、
原料粉末のより好ましい粒度構成は、直径０．１ｍｍ以
下の微粒物が８０重量％以上を占めるものである。At this time, if the raw material powder contains coarse particles having a diameter of more than 0.1 mm in an amount of more than 20% by weight, it becomes difficult to form a molded product having a large specific surface area, or the molded product can be molded. As a result, the sintered body becomes brittle and powdered in a short period of time to cause clogging, resulting in a lack of sustainability as a NOx removal catalyst. From this meaning,
A more preferable particle size constitution of the raw material powder is such that fine particles having a diameter of 0.1 mm or less account for 80% by weight or more.
【００１９】また成形後の焼成温度が１０００℃未満の
低温域では、カルシウム・フェライトの固相反応が進み
難くなってＮＯｘ除去活性を十分に高めることができ
ず、一方１２００℃を超える高温域になると焼成時に多
量の融液が生成して成形体同士の融着が起こり、好適粒
度構成の焼結成形体が得られ難くなる。ちなみに粒状の
焼結成形体とする場合の好ましい粒度構成は、比表面積
を高めつつ使用時の圧力損失を抑える意味から直径２〜
１０ｍｍ、より好ましくは３〜５ｍｍの範囲である。Further, in the low temperature range where the firing temperature after molding is less than 1000 ° C., the solid-phase reaction of calcium / ferrite is difficult to proceed and the NOx removal activity cannot be sufficiently enhanced, while in the high temperature range over 1200 ° C. If so, a large amount of melt is generated during firing, and fusion between the compacts occurs, and it becomes difficult to obtain a sintered compact having a preferable grain size configuration. By the way, the preferable particle size constitution in the case of forming a granular sintered compact is to increase the specific surface area and to suppress the pressure loss during use, the diameter of 2 to
It is in the range of 10 mm, more preferably 3 to 5 mm.
【００２０】他方、本発明の規定要件を満たすＣａＯ・
ＦｅｘＯ系複合酸化物を用いてＮＯｘ除去を行なう場合
において、脱硝率５０％以上を確保するための温度と酸
素分圧の関係を予備実験によって調べたところ図４に示
す様な傾向が得られ、この図より、３００〜７００℃の
温度条件下で５０％以上の脱硝率を得るには、酸素分圧
を１０-15以下の極低レベルに抑えなければならないこ
とが分かる。自動車エンジンの排ガス中には１％以下の
ＣＯと十数％の酸素が含まれているので、この様な排ガ
ス組成においてはＮＯｘ除去は難しいと考えられる。と
ころが本発明者らが別途確認したところによると、該エ
ンジン排ガス中には不完全燃焼によって残った多量の炭
素が存在しており、この炭素は触媒表面に付着する。そ
してこの炭素は、上記の様な温度域で排ガス中に存在す
る酸素と反応してＣＯ若しくはＣＯ2に変化するため、
実用時における触媒表面の酸素分圧は非常に低いものと
なる。その結果、本発明触媒によるＮＯｘ除去活性は、
３００〜７００℃といった比較的低い温度域でも十分効
果的に発揮されるものと考えられる。On the other hand, CaO, which satisfies the requirements of the present invention,
When performing NOx removal using a FexO-based composite oxide, the relationship between the temperature and the oxygen partial pressure for ensuring a denitrification rate of 50% or more was investigated by preliminary experiments, and the tendency shown in FIG. 4 was obtained. From this figure, it is understood that the oxygen partial pressure must be suppressed to an extremely low level of 10 -15 or less in order to obtain a denitrification rate of 50% or more under the temperature condition of 300 to 700 ° C. Since the exhaust gas of an automobile engine contains 1% or less of CO and more than 10% of oxygen, it is considered difficult to remove NOx with such an exhaust gas composition. However, according to another confirmation by the present inventors, there is a large amount of carbon remaining in the exhaust gas of the engine due to incomplete combustion, and this carbon adheres to the catalyst surface. And this carbon reacts with oxygen present in the exhaust gas in the temperature range as described above to change into CO or CO 2 ,
The oxygen partial pressure on the surface of the catalyst during practical use is extremely low. As a result, the NOx removal activity by the catalyst of the present invention is
It is considered that even in a relatively low temperature range of 300 to 700 ° C., it is sufficiently effectively exhibited.
【００２１】尚、上記触媒の排ガス管内への配設手段に
は一切制限がなく、排ガス管の適所に触媒充填部を区画
形成して直接充填する方法、触媒を予めカセット型に充
填したものを準備しておいてこれを装入する方法、排ガ
ス管の適所を触媒充填部パーツとして着脱可能に形成し
ておき、該パーツとして装着若しくは交換できる様にす
る方法、等を採用することが可能である。There is no limitation on the means for arranging the catalyst in the exhaust gas pipe, and a method of directly forming a catalyst-filled portion by partitioning the catalyst-filled portion in an appropriate place of the exhaust gas pipe, or a catalyst pre-filled in a cassette type is used. It is possible to adopt a method of preparing and charging this, a method of forming a suitable portion of the exhaust gas pipe as a catalyst-filled part detachably, and allowing it to be mounted or replaced as the part. is there.
【００２２】[0022]
【実施例】次に本発明の実施例を示すが、本発明はもと
より下記実施例によって制限を受けるものではなく、前
・後記の趣旨に適合し得る範囲で適当に変更を加えて実
施することも勿論可能であり、それらはいずれも本発明
の技術的範囲に含まれる。
実施例１
１００μｍ以下の微粒物が８０重量％以上を占めるマグ
ネタイト鉄鉱石に、１００μｍ以下の微粒物が９０重量
％以上を占める石灰石粉末を、ＣａＯ・Ｆｅ2Ｏ3換算で
２３重量％となる様に混合し、皿型造粒機を用いて、結
合融剤として水を散布しながら造粒し、この生ペレット
粒を酸化性雰囲気下に１１００〜１１５０℃で１０分間
加熱焼成し、粒径４〜６ｍｍの造粒焼結物を得た。得ら
れた造粒焼結物の組成は、Ｔ・Ｆｅ：52.1％、ＦｅＯ：
1.47％（鉄酸化物合計として76.06％）、ＳｉＯ2：0.91
％、Ａｌ2Ｏ3：0.23％、ＣａＯ：22.8％であった。EXAMPLES Examples of the present invention will now be described. However, the present invention is not limited by the following examples, and the present invention may be carried out with appropriate modifications within a range compatible with the gist of the preceding and the following. Of course, it is possible, and all of them are included in the technical scope of the present invention. Example 1 A magnetite iron ore containing 80% by weight or more of fine particles of 100 μm or less, and a limestone powder containing 90% by weight or more of fine particles of 100 μm or less was 23% by weight in terms of CaO / Fe 2 O 3 . And granulated while spraying water as a binding flux using a plate type granulator, and the raw pellet particles are heated and fired at 1100-1150 ° C. for 10 minutes in an oxidizing atmosphere to give a particle size of 4 A granulated sinter of ~ 6 mm was obtained. The composition of the obtained granulated sintered product was T.Fe: 52.1%, FeO:
1.47% (total iron oxide is 76.06%), SiO 2 : 0.91
%, Al 2 O 3 : 0.23%, CaO: 22.8%.
【００２３】この造粒焼結物を、排気量１８００ｃｃの
ガソリンエンジン車の排気管内に所定量設置し、回転数
１５００ｒｐｍでエンジン始動後１０分〜７２時間後の
ＮＯｘ除去率を測定した。また焼結温度を９５０℃また
は１２５０℃に設定した以外は上記と全く同様にして得
た造粒焼結物についても、同様にしてＮＯｘ除去触媒と
しての性能試験を行なった。また比較のため市販の白金
パラジウム系ＮＯｘ除去触媒（アルミナボールに白金と
パラジウムを担持させたもの）を使用し、上記と同様に
してＮＯｘ除去率を測定した。結果を表１に示す。A predetermined amount of this granulated sintered product was installed in an exhaust pipe of a gasoline engine vehicle having an exhaust volume of 1800 cc, and the NOx removal rate was measured 10 minutes to 72 hours after the engine was started at a rotation speed of 1500 rpm. Further, a performance test as a NOx removal catalyst was similarly performed on the granulated sintered product obtained in exactly the same manner as above except that the sintering temperature was set to 950 ° C or 1250 ° C. For comparison, a commercially available platinum-palladium-based NOx removal catalyst (alumina ball supporting platinum and palladium) was used, and the NOx removal rate was measured in the same manner as above. The results are shown in Table 1.
【００２４】[0024]
【表１】 [Table 1]
【００２５】表１において、Ｎｏ．１は本発明の規定要
件を満たす実施例であり、Ｎｏ．４の従来例に比べて脱
硝率は若干劣るものの、約５０％の高い脱硝率が得られ
ており、触媒使用量を増大することによって従来の白金
・パラジウム系触媒に匹敵し若しくはこれを上回る脱硝
率を得ることが可能である。これに対しＮｏ．２の触媒
は、焼成温度が低すぎるため固相反応が十分に進まず、
ＮＯｘ除去活性が乏しい。またＮｏ．３は焼成温度が高
すぎる比較例であり、焼成時に粒子同士の融着が起こる
と共に粒子の細孔数も低減するためか、やはり良好なＮ
Ｏｘ除去活性が得られない。In Table 1, No. No. 1 is an embodiment satisfying the requirements of the present invention. Although the denitrification rate is slightly inferior to the conventional example of No. 4, a high denitrification rate of about 50% is obtained, and by increasing the amount of catalyst used, the denitrification rate is comparable to or higher than that of conventional platinum-palladium-based catalysts. It is possible to get a rate. On the other hand, No. In the case of catalyst No. 2, the solid-phase reaction does not proceed sufficiently because the firing temperature is too low,
Poor NOx removal activity. In addition, No. No. 3 is a comparative example in which the calcination temperature is too high, and the fusion of particles with each other occurs during calcination and the number of pores of the particles is also reduced.
Ox removal activity cannot be obtained.
【００２６】比較例
上記実施例においてマグネタイト鉄鉱石として１００μ
ｍを超える粒径のものが５０重量％である粗粒物を使用
した以外は上記と同様にして造粒、焼成を行なった。こ
の造粒工程で全重量の２０％は崩壊した状態となり適正
粒径のものは４０重量％しか得られなかった。また適正
粒径のものを篩分けして上記と同じ条件で焼成して得た
焼結物を用いて上記と同様のＮＯｘ除去試験に供したと
ころ、試験開始後すぐに排ガス圧損が急激に上昇しはじ
めたので、実質上試験を行うことができなかった。エン
ジンの回転を止めて触媒を取り出し観察したところ、焼
結粒子の約２０％が崩壊・粉化していることが確認され
た。Comparative Example 100 μm as magnetite iron ore in the above example
Granulation and firing were performed in the same manner as above except that a coarse particle having a particle size of more than m was 50% by weight. In this granulation step, 20% of the total weight was in a disintegrated state, and only 40% by weight having an appropriate particle size was obtained. Also, when a NOx removal test similar to the above was performed using a sintered product obtained by sieving a powder having an appropriate particle size and firing under the same conditions as described above, the exhaust gas pressure loss rapidly increased immediately after the start of the test. Since it started to do so, the test could not be practically performed. When the engine was stopped and the catalyst was taken out and observed, it was confirmed that about 20% of the sintered particles were disintegrated and powdered.
【００２７】[0027]
【発明の効果】本発明は以上の様に構成されており、適
量のＣａＯを含み且つその他成分量の制限されたＣａＯ
・ＦｅｘＯ系複合酸化物をＮＯｘ除去触媒として使用
し、その配置温度域及びガス排出量当たりの配置量を規
定することによって、自動車エンジン排ガス中のＮＯｘ
を効率良く除去することができる。また本発明の製法を
利用すれば、優れたＮＯｘ除去性能を備えた触媒を効率
良く製造することができる。しかもこのＮＯｘ除去触媒
は製造原料が安価で製造も容易であるので、従来の白金
・パラジウム系触媒に比べて格安に提供することがで
き、更には使用後の廃触媒は製鉄原料として支障なく使
えるので、極めて経済的な技術と言える。The present invention is constituted as described above, and contains CaO in an appropriate amount and has a limited amount of other components.
・ NOx in the exhaust gas of an automobile engine is determined by using a FexO-based composite oxide as a NOx removal catalyst and defining the temperature range and the amount of gas per gas emission.
Can be removed efficiently. Further, by utilizing the production method of the present invention, a catalyst having excellent NOx removal performance can be efficiently produced. Moreover, this NOx removal catalyst can be provided cheaply as compared with the conventional platinum-palladium-based catalyst because the raw material for producing this NOx is cheap and it is easy to produce. Furthermore, the used catalyst after use can be used as a raw material for iron making without any trouble. So it can be said that it is an extremely economical technology.
【図１】排ガス量当たりの触媒量と脱硝率の関係を示す
グラフである。FIG. 1 is a graph showing the relationship between the amount of catalyst and the denitration rate per amount of exhaust gas.
【図２】ＮＯｘ除去処理温度と脱硝率の関係を示すグラ
フである。FIG. 2 is a graph showing the relationship between the NOx removal treatment temperature and the denitration rate.
【図３】脱硝率測定装置を示す説明図である。FIG. 3 is an explanatory diagram showing a denitration rate measuring device.
【図４】脱硝率５０％を得るための温度と酸素分圧の関
係を示すグラフである。FIG. 4 is a graph showing the relationship between temperature and oxygen partial pressure for obtaining a denitration rate of 50%.
１ ＮＯｘ含有ガス発生部 ６ ＮＯｘ除去触媒 1 NOx-containing gas generator 6 NOx removal catalyst
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭50−21988（ＪＰ，Ａ) 特許2674428（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.7，ＤＢ名) B01J 21/00 - 38/74 B01D 53/00 - 53/96 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-50-21988 (JP, A) Patent 2674428 (JP, B2) (58) Fields investigated (Int.Cl. 7 , DB name) B01J 21/00 -38/74 B01D 53/00-53/96
Claims (2)
り、且つＣａＯと鉄酸化物以外の成分が９重量％以下で
あるＣａＯ・ＦｅｘＯ系複合酸化物（ｘはＦｅとＯの原
子比を示し、０．６７〜１．００を意味するものである
が、該ＣａＯ・ＦｅｘＯ系複合酸化物はＦｅＯを含むも
のである）を、３００〜７００℃の温度域に達する自動
車エンジンの排ガス管内に配置する方法であって、前記
ＣａＯ・ＦｅｘＯ系複合酸化物の使用量の下限を、１分
間のガス排出量１ｍ3当たり０．３２ｋｇとすることを
特徴とする自動車排ガス中のＮＯｘ除去方法。1. A CaO / FexO-based composite oxide having a CaO content of 10 to 30% by weight and a content of components other than CaO and iron oxide of 9% by weight or less (x is a source of Fe and O).
It indicates the child ratio and means 0.67 to 1.00.
However, the CaO / FexO-based composite oxide also contains FeO.
In a), and a method of placing the exhaust gas pipe of an automobile engine reaches a temperature range of 300 to 700 ° C. of the
NOx removal method in automobile exhaust gas, characterized in that the lower limit of the amount of CaO · FexO based composite oxide, and 1 minute of gas emissions 1 m 3 per 0.32 kg.
で、ＣａＯ含有量が１０〜３０重量％、ＣａＯと鉄酸化
物以外の成分含有量が９重量％以下となる様に配合され
ると共に、粒径０．１ｍｍ以下のものが８０重量％以上
である混合粉末を、結合融剤と共に混練し成形した後、
１０００〜１２００℃で加熱処理して、ＣａＯ・Ｆｅｘ
Ｏ系複合酸化物（ｘはＦｅとＯの原子比を示し、０．６
７〜１．００を意味するものであるが、該ＣａＯ・Ｆｅ
ｘＯ系複合酸化物はＦｅＯを含むものである）としたも
のであることを特徴とする自動車排ガス用ＮＯｘ除去触
媒。2. Limestone and iron oxide, which are components after firing, are mixed so that the CaO content is 10 to 30% by weight and the content of components other than CaO and iron oxide is 9% by weight or less. In addition, a mixed powder having a particle size of 0.1 mm or less of 80% by weight or more is kneaded and molded with a binder flux,
Heat treatment at 1000-1200 ℃ , CaO ・ Fex
O-based composite oxide (x represents an atomic ratio of Fe and O, and is 0.6
It means 7 to 1.00, but the CaO.Fe
The xO-based composite oxide is one containing FeO), which is a NOx removal catalyst for automobile exhaust gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12720293A JP3536311B2 (en) | 1993-05-28 | 1993-05-28 | NOx removal method and NOx removal catalyst in automobile exhaust gas |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12720293A JP3536311B2 (en) | 1993-05-28 | 1993-05-28 | NOx removal method and NOx removal catalyst in automobile exhaust gas |
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| Publication Number | Publication Date |
|---|---|
| JPH06335620A JPH06335620A (en) | 1994-12-06 |
| JP3536311B2 true JP3536311B2 (en) | 2004-06-07 |
Family
ID=14954243
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|---|---|---|---|
| JP12720293A Expired - Fee Related JP3536311B2 (en) | 1993-05-28 | 1993-05-28 | NOx removal method and NOx removal catalyst in automobile exhaust gas |
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