JPH10286463A - Catalytic layer for purification of exhaust gas, catalytic structure for purification of exhaust gas and method for purifying exhaust gas with the same - Google Patents
Catalytic layer for purification of exhaust gas, catalytic structure for purification of exhaust gas and method for purifying exhaust gas with the sameInfo
- Publication number
- JPH10286463A JPH10286463A JP9113379A JP11337997A JPH10286463A JP H10286463 A JPH10286463 A JP H10286463A JP 9113379 A JP9113379 A JP 9113379A JP 11337997 A JP11337997 A JP 11337997A JP H10286463 A JPH10286463 A JP H10286463A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- exhaust gas
- purifying
- pore
- alumina
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000000746 purification Methods 0.000 title claims description 10
- 230000003197 catalytic effect Effects 0.000 title abstract 3
- 239000003054 catalyst Substances 0.000 claims abstract description 220
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 56
- 239000011148 porous material Substances 0.000 claims abstract description 55
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 30
- 229910052709 silver Inorganic materials 0.000 claims abstract description 16
- 229910052718 tin Inorganic materials 0.000 claims abstract description 14
- 238000001179 sorption measurement Methods 0.000 claims abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 79
- 239000010948 rhodium Substances 0.000 claims description 31
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 27
- 238000002485 combustion reaction Methods 0.000 claims description 25
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 15
- 239000004332 silver Substances 0.000 claims description 15
- 239000000758 substrate Substances 0.000 claims description 15
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 13
- 229930195733 hydrocarbon Natural products 0.000 claims description 13
- 150000002430 hydrocarbons Chemical class 0.000 claims description 13
- 239000011135 tin Substances 0.000 claims description 13
- 239000003638 chemical reducing agent Substances 0.000 claims description 12
- 239000000446 fuel Substances 0.000 claims description 8
- 239000004215 Carbon black (E152) Substances 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 3
- 239000011819 refractory material Substances 0.000 claims description 3
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 2
- 239000003546 flue gas Substances 0.000 claims 2
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 2
- 239000000969 carrier Substances 0.000 abstract 1
- 239000000567 combustion gas Substances 0.000 abstract 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 48
- 239000010410 layer Substances 0.000 description 37
- 230000000052 comparative effect Effects 0.000 description 17
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 238000011156 evaluation Methods 0.000 description 9
- 239000007864 aqueous solution Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000006722 reduction reaction Methods 0.000 description 7
- 239000002243 precursor Substances 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 229910052878 cordierite Inorganic materials 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 150000001336 alkenes Chemical class 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000003502 gasoline Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 150000003283 rhodium Chemical class 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- -1 aluminum alkoxide Chemical class 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000003350 kerosene Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000010792 warming Methods 0.000 description 2
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- MXRIRQGCELJRSN-UHFFFAOYSA-N O.O.O.[Al] Chemical compound O.O.O.[Al] MXRIRQGCELJRSN-UHFFFAOYSA-N 0.000 description 1
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 description 1
- SMYKVLBUSSNXMV-UHFFFAOYSA-K aluminum;trihydroxide;hydrate Chemical compound O.[OH-].[OH-].[OH-].[Al+3] SMYKVLBUSSNXMV-UHFFFAOYSA-K 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- LFYJSSARVMHQJB-QIXNEVBVSA-N bakuchiol Chemical compound CC(C)=CCC[C@@](C)(C=C)\C=C\C1=CC=C(O)C=C1 LFYJSSARVMHQJB-QIXNEVBVSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 229910001593 boehmite Inorganic materials 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 210000002345 respiratory system Anatomy 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 150000003378 silver Chemical class 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は燃焼排ガス、特に自
動車、ボイラー、ガスエンジン、ガスタービン、船舶な
どの移動式および固定式内燃機関の燃焼排ガス中に含ま
れる窒素酸化物の浄化に用いられる排ガス浄化用触媒層
および排ガス浄化用触媒被覆構造体に関し、さらに詳細
には希薄空燃比で運転される内燃機関から排出される排
ガス中の窒素酸化物を高い空間速度で、かつ高効率で浄
化可能な排ガス浄化用触媒層および排ガス浄化用被覆構
造体と、これらを使用しての排ガス浄化方法に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to exhaust gas used for purifying nitrogen oxides contained in combustion exhaust gas of mobile and stationary internal combustion engines of automobiles, boilers, gas engines, gas turbines, ships and the like. The present invention relates to a purification catalyst layer and an exhaust gas purification catalyst-coated structure, and more specifically, it can purify nitrogen oxides in exhaust gas discharged from an internal combustion engine operated at a lean air-fuel ratio at a high space velocity and with high efficiency. The present invention relates to an exhaust gas purifying catalyst layer and an exhaust gas purifying coating structure, and an exhaust gas purifying method using the same.
【０００２】[0002]
【従来の技術】自動車をはじめとする内燃機関から排出
される各種の燃焼排ガス中には、燃焼生成物である水や
二酸化炭素と共に一酸化窒素や二酸化窒素などの窒素酸
化物（ＮＯｘ）が含まれている。ＮＯｘは人体、特に呼
吸器系に悪影響を及ぼすばかりでなく、地球環境保全の
上からも問題視される酸性雨の原因の１つとなってい
る。そのため、これら各種の排ガスから効率よく窒素酸
化物を除去する脱硝技術の開発が望まれている。2. Description of the Related Art Various combustion exhaust gases emitted from internal combustion engines such as automobiles contain nitrogen oxides (NOx) such as nitric oxide and nitrogen dioxide together with water and carbon dioxide as combustion products. Have been. NOx not only adversely affects the human body, particularly the respiratory system, but also is one of the causes of acid rain, which is regarded as a problem from the viewpoint of global environmental protection. Therefore, development of a denitration technology for efficiently removing nitrogen oxides from these various exhaust gases is desired.
【０００３】他方において、地球温暖化防止の観点から
近年希薄燃焼方式の内燃機関が注目されている。従来の
自動車用ガソリンエンジンは、空燃比（Ａ／Ｆ）＝１
４．７付近で制御された化学量論比での燃焼であり、そ
の排ガス処理に対しては排ガス中の一酸化炭素、炭化水
素とＮＯｘとを、主として白金、ロジウム、パラジウム
およびセリアを含むアルミナ触媒に接触させて有害三成
分を同時に除去する三元触媒方式が採用されてきた。On the other hand, in view of the prevention of global warming, lean-burn internal combustion engines have recently attracted attention. A conventional gasoline engine for an automobile has an air-fuel ratio (A / F) = 1.
Combustion at a controlled stoichiometric ratio near 4.7. For exhaust gas treatment, carbon monoxide, hydrocarbons and NOx in the exhaust gas are converted to alumina mainly containing platinum, rhodium, palladium and ceria. A three-way catalyst system has been employed in which three harmful components are simultaneously removed by contact with a catalyst.
【０００４】しかしながら、この三元触媒方式は、エン
ジンが化学量論比で運転されることが絶対条件であるた
め、希薄空燃比で運転される希薄燃焼ガソリンエンジン
の排ガス浄化には適用することができない。また、ディ
ーゼルエンジンは本来希薄燃焼エンジンであるが、その
排ガスに対しては浮遊粒子状物質とＮＯｘの両方に厳し
い規制がかけられようとしている。[0004] However, since the absolute condition is that the engine is operated at a stoichiometric ratio, the three-way catalyst system can be applied to exhaust gas purification of a lean burn gasoline engine operated at a lean air-fuel ratio. Can not. In addition, diesel engines are originally lean burn engines, but strict regulations are being imposed on both the suspended particulate matter and NOx in the exhaust gas.
【０００５】従来、酸素過剰雰囲気下でΝＯｘを還元除
去する方法としては、還元ガスとして僅かな量でも選択
的に触媒に吸着するＮＨ３を使用する技術が既に確立さ
れている。この技術は、いわゆる固定発生源であるボイ
ラーやディーゼルエンジンからの排ガス脱硝方法として
工業化されている。しかし、この方法においては未反応
の還元剤の回収処理のための特別な装置を必要とし、ま
た臭気が強く有害なアンモニアを用いるので、特に自動
車などの移動発生源からの排ガス脱硝技術としては危険
性があり適用できない。Conventionally, as a method of reducing and removing the ΝOx in an oxygen-rich atmosphere, a technique of using NH 3 also adsorb selectively catalyst small amount as the reducing gas has already been established. This technology has been industrialized as a method for denitration of exhaust gas from boilers and diesel engines, which are so-called stationary sources. However, this method requires a special device for the recovery treatment of unreacted reducing agent and uses harmful ammonia, which has a strong odor, which is particularly dangerous for exhaust gas denitration technology from mobile sources such as automobiles. Not applicable.
【０００６】近年、酸素過剰雰囲気の希薄燃焼排ガス中
に残存する未燃の炭化水素を還元剤として用いることに
より、ＮＯｘ還元反応を促進させることができるという
報告がなされて以来、この反応を促進するための触媒が
種々開発され報告されている。例えば、アルミナやアル
ミナに遷移金属を担持した触媒が、炭化水素を還元剤と
して用いるＮＯｘ還元反応に有効であるとする数多くの
報告がある。また、特開平４−２８４８４８号公報には
０．１〜４重量％のＣｕ、Ｆｅ、Ｃｒ、Ｚｎ、Ｎｉ、Ｖ
を含有するアルミナあるいはシリカーアルミナをΝＯｘ
還元触媒として使用した例が報告されている。In recent years, it has been reported that a NOx reduction reaction can be promoted by using unburned hydrocarbons remaining in a lean combustion exhaust gas in an oxygen-excess atmosphere as a reducing agent. Various catalysts have been developed and reported. For example, there are many reports that alumina or a catalyst in which a transition metal is supported on alumina is effective for a NOx reduction reaction using a hydrocarbon as a reducing agent. JP-A-4-284848 discloses that 0.1 to 4% by weight of Cu, Fe, Cr, Zn, Ni, V
Alumina or silica-alumina containing ΝOx
An example of use as a reduction catalyst has been reported.
【０００７】さらに、Ρｔをアルミナに担持した触媒を
用いると、ＮＯｘ還元反応が２００〜３００℃程度の低
温領域で進行することが特開平４−２６７９４６号公
報、特開平５−６８８５５号公報や特開平５−１０３９
４９号公報などに報告されている。しかしながら、これ
らの担持貴金属触媒を用いた場合、還元剤である炭化水
素の燃焼反応が過度に促進されたり、地球温暖化の原因
物質の１つと言われているＮ２Ｏが多量に副生し、無害
なΝ２への還元反応を選択的に進行させることが困難で
あるといった欠点を有していた。Further, when a catalyst in which Δt is supported on alumina is used, the NOx reduction reaction proceeds in a low temperature range of about 200 to 300 ° C., as disclosed in JP-A-4-267946 and JP-A-5-68855. Kaihei 5-1039
No. 49, for example. However, when these supported precious metal catalysts are used, the combustion reaction of hydrocarbons as a reducing agent is excessively promoted, and a large amount of N 2 O, which is one of the substances causing global warming, is produced as a by-product. , it is made to proceed the reduction reaction of the harmless New 2 selective had disadvantage is difficult.
【０００８】本出願人の一方は、先に酸素過剰雰囲気下
で炭化水素を還元剤として銀を含有する触媒を用いると
ＮＯｘ還元反応が選択的に進行することを見出し、この
技術を特開平４−２８１８４４号公報に開示した。この
開示がなされた後においても、銀を含有する触媒を用い
る類似のΝＯｘ還元除去技術が特開平４−３５４５３６
号公報、特開平５−９２１２４号公報、特開平５−９２
１２５号公報および特開平６−２７７４５４号公報など
に開示されている。One of the present applicants has previously found that the use of a catalyst containing silver with a hydrocarbon as a reducing agent in an oxygen-excess atmosphere causes the NOx reduction reaction to proceed selectively. -281844. Even after this disclosure was made, a similar ΝOx reduction and removal technique using a catalyst containing silver was disclosed in JP-A-4-354536.
JP-A-5-92124, JP-A-5-92124
No. 125 and JP-A-6-277454.
【０００９】[0009]
【発明の解決しようとする課題】しかし、これら従来の
公報に記載されたアルミナ担持銀触媒は、ＳＯｘおよび
水蒸気共存下での脱硝性能が実用的にまだ不十分であ
り、また経時変化が大きいといった問題があった。However, the alumina-supported silver catalyst described in these conventional publications has a practically insufficient denitration performance in the coexistence of SOx and water vapor, and has a large change with time. There was a problem.
【００１０】本発明は上記従来技術の欠点を解決すべく
なされたものであり、その目的とするところは、希薄燃
焼排ガス中のＮＯｘを効率よく除去することができ、か
つ経時変化の小さい排ガス浄化用触媒層および触媒被覆
構造体と、これらを使用して希薄燃焼排ガス中のＮＯｘ
を高効率、高信頼性をもって浄化する排ガス浄化方法を
提供することにある。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art. It is an object of the present invention to efficiently remove NOx in lean combustion exhaust gas and to reduce exhaust gas purification with little change over time. Catalyst layer and catalyst coated structure, and NOx in lean combustion exhaust gas using them
Of the present invention is to provide an exhaust gas purifying method for purifying waste gas with high efficiency and high reliability.
【００１１】[0011]
【課題を解決するための手段】本発明者等は、ＳＯｘお
よび水蒸気が共存する希薄燃焼領域において高い脱硝性
能を有し、かつ経時変化の小さい排ガス浄化用触媒層お
よび排ガス浄化用触媒被覆構造体と、これらを使用して
の排ガス浄化方法について鋭意研究を重ねた結果、排ガ
スの流通方向に対して特定の細孔構造を有するアルミナ
担体にロジウムを含有してな触媒Ａを前段に、特定の細
孔構造を有するアルミナ担体にロジウム、錫および銀を
含有してなる触媒Ｂを後段になるように区分して配置さ
せ、ロジウム量は触媒Ｂより触媒Ａを多くすることによ
り上記した問題を解決できることを見出し本発明を完成
するに至った。Means for Solving the Problems The present inventors have developed an exhaust gas purifying catalyst layer and an exhaust gas purifying catalyst coating structure having high denitration performance in a lean burn region where SOx and steam coexist, and having little change over time. And, as a result of intensive studies on exhaust gas purification methods using these, as a result of a catalyst A containing rhodium in an alumina carrier having a specific pore structure in the exhaust gas flow direction, The catalyst B containing rhodium, tin and silver is divided and arranged in the latter stage on an alumina carrier having a pore structure, and the amount of rhodium solves the above problem by increasing the amount of the catalyst A to the amount of the catalyst B. We have found that we can do this and completed the present invention.
【００１２】すなわち、上記課題を解決するための本発
明の第１の実施態様は、アルミナ担体に０．００１〜１
重量％のロジウムを含有してなる触媒Ａと、アルミナ担
体に０．０００１〜０．１重量％のロジウムと錫および
銀を含有してなる触媒Ｂとから構成され、かつ前記両ア
ルミナ担体は窒素ガス吸着法により測定された細孔半径
と細孔容積の関係が、細孔半径３００オングストローム
以下の細孔の占める細孔容積の合計値をＸとし、細孔半
径２５オングストローム以上で１００オングストローム
未満の細孔の占める細孔容積の合計値をＹとし、細孔半
径１００オングストローム以上で３００オングストロー
ム以下の細孔の占める細孔容積の合計値をＺとしたと
き、ＹがＸの７０％以上であり、ＺがＸの２０％以下で
あるような細孔構造を有する排ガス浄化用触媒層を特徴
とするものである。該触媒層は、粉体または成型した状
態で排ガスの流通空間に配置するのが好ましい。That is, in a first embodiment of the present invention for solving the above-mentioned problems, an alumina carrier has a thickness of 0.001 to 1 mm.
% Of rhodium and a catalyst B containing 0.0001 to 0.1% by weight of rhodium, tin and silver in an alumina carrier. The relationship between the pore radius measured by the gas adsorption method and the pore volume is defined as X, where the total value of the pore volume occupied by pores having a pore radius of 300 Å or less is X, and the pore radius is 25 Å or more and less than 100 Å. When the total value of the pore volumes occupied by the pores having a pore radius of 100 Å or more and 300 Å or less is Z, Y is 70% or more of X, where Y is the total value of the pore volume occupied by the pores. , Z is not more than 20% of X and is characterized by an exhaust gas purifying catalyst layer having a pore structure. The catalyst layer is preferably disposed in a flow space of the exhaust gas in a powdered or molded state.
【００１３】また、本発明の第２の実施態様は、多数の
貫通孔を有する耐火性材料からなる一体構造の支持基質
と、該支持基質における少なくとも該貫通孔の内表面に
上記の触媒層を区分して被覆した触媒被覆構造体を特徴
とするものである。In a second embodiment of the present invention, a support substrate having an integral structure made of a refractory material having a large number of through holes, and the above-mentioned catalyst layer provided on at least the inner surface of the through hole in the support substrate. The present invention is characterized by a catalyst-coated structure that is separately coated.
【００１４】またさらに、本発明の第３の実施態様は希
薄空燃比で運転される内燃機関の燃焼排ガスを触媒含有
層と接触させることからなる炭化水素を還元剤とする排
ガス中のＮＯｘを除去する方法において、該触媒含有層
に含まれる触媒は前記第１の実施態様における触媒層ま
たは第２の実施態様における触媒被覆構造体であること
を特徴とし、また、排ガスの流通方向に対して触媒Ａが
前段に、触媒Ｂが後段になるように区分されて配置され
ている排ガス浄化方法を特徴とするものである。Still further, a third embodiment of the present invention removes NOx in exhaust gas containing hydrocarbons as a reducing agent, which comprises contacting the exhaust gas of an internal combustion engine operated at a lean air-fuel ratio with a catalyst-containing layer. Wherein the catalyst contained in the catalyst-containing layer is the catalyst layer according to the first embodiment or the catalyst-coated structure according to the second embodiment. The exhaust gas purification method is characterized in that A is disposed in the first stage and catalyst B is disposed in the second stage.
【００１５】[0015]
【発明の実施の形態】以下、本発明の詳細およびその作
用についてさらに具体的に説明する。 （触媒の構造およびその製法）本発明の排ガス浄化用触
媒層における触媒ＡとＢの主成分の１つであるアルミナ
は、例えば鉱物学上ベーマイト、擬ベーマイト、バイア
ライト、あるいはノルストランダイトに分類される水酸
化アルミニウムの粉体やゲルを、空気中あるいは真空中
３００〜８００℃、好ましくは４００〜９００℃で加熱
脱水することによって、結晶学的にγ一型、η−型、δ
−型、χ−型あるいはその混合型に分類されるアルミナ
に相転移させたものが脱硝性能上好ましい。他の結晶構
造をとるアルミナ、例えばα−型のアルミナは極端に比
表面積が小さく固体酸性にも乏しいので本発明の触媒成
分としては不適当である。BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention and its operation will be more specifically described below. (Catalyst Structure and Method for Producing the Same) Alumina, which is one of the main components of the catalysts A and B in the catalyst layer for purifying exhaust gas of the present invention, is classified into, for example, boehmite, pseudoboehmite, vialite, or norstrandite in terms of mineralogy. The aluminum hydroxide powder or gel is heated and dehydrated in air or vacuum at 300 to 800 ° C., preferably 400 to 900 ° C., to crystallographically form γ-type, η-type, δ
Those obtained by phase transition to alumina classified into-type, χ-type or a mixed type thereof are preferable from the viewpoint of denitration performance. Alumina having another crystal structure, for example, α-type alumina, is unsuitable as the catalyst component of the present invention because of its extremely small specific surface area and poor solid acidity.
【００１６】また触媒ＡとＢのアルミナは、窒素ガス吸
着法により測定された細孔半径が３００オングストロー
ム以下の細孔の占める細孔容積の合計値をＸとし、細孔
半径が２５オングストローム以上で１００オングストロ
ーム未満の細孔の占める細孔容積の合計値をＹとし、細
孔半径が１００オングストローム以上で３００オングス
トローム以下の細孔の占める細孔容積の合計値をＺとし
たとき、ＹがΧの７０％以上であり、ＺがＸの２０％以
下であるような細孔構造を有するアルミナであることが
必要である。細孔構造が、上記した条件を満たさないア
ルミナを本発明の触媒ＡとＢにおける担体として用いた
場合には、これにより構成される排ガス浄化用触媒は水
蒸気共存下での排ガスの脱硝性能が不十分であった。し
たがって、本発明の触媒ＡとＢの成分として有効なアル
ミナは、上記した結晶構造および細孔特性を有するもの
が適切であるといえる。The alumina of catalysts A and B has a total pore volume occupied by pores having a pore radius of 300 angstroms or less measured by a nitrogen gas adsorption method as X. When the total value of the pore volume occupied by pores smaller than 100 Å is Y, and the total value of the pore volume occupied by pores having a pore radius of 100 Å or more and 300 Å or less is Z, Y is Δ It is necessary to be alumina having a pore structure in which the content is 70% or more and Z is 20% or less of X. When alumina having a pore structure not satisfying the above-mentioned conditions is used as a carrier in the catalysts A and B of the present invention, the exhaust gas purifying catalyst constituted by the alumina has a poor exhaust gas denitration performance in the presence of steam. Was enough. Therefore, it can be said that alumina having the above-mentioned crystal structure and pore characteristics is suitable as the alumina effective as a component of the catalysts A and B of the present invention.
【００１７】本発明の排ガス浄化用触媒層は、以下のよ
うに構成される。本発明にかかる触媒層は、前記した結
晶構造および細孔特性を有するアルミナ担体に０．００
１〜１重量％のロジウムを含有させてなる触媒Ａと、同
じく前記した結晶構造および細孔特性を有するアルミナ
担体に０．０００１〜０．１重量％のロジウムと、錫お
よび銀を含有させてなる触媒Ｂとから構成されることを
特徴とする。触媒ＡとＢにおいて、アルミナに含有され
るロジウムの状態は特に限定されず、金属状態、酸化物
状態およびこれらの混合状態などが挙げられる。また触
媒Ｂにおいてアルミナに含有される錫及び銀の状態は、
特に限定されず金属状態、酸化物状態、合金状態、複合
酸化物状態およびこれらの混合状態などが挙げられる。
特に、自動車などの内燃機関の燃焼排ガス組成は運転状
態によってその都度変化するため、触媒は還元雰囲気お
よび酸化雰囲気に曝される。したがって、触媒を構成す
る活性金属の状態は雰囲気により変化することが想定さ
れる。触媒Ａのロジウムや触媒Ｂのロジウム、錫および
銀の出発原料は特に限定されないが水可溶性塩の使用が
好ましい。The exhaust gas purifying catalyst layer of the present invention is constituted as follows. The catalyst layer according to the present invention has an alumina support having the above crystal structure and pore characteristics of 0.001
Catalyst A containing 1 to 1% by weight of rhodium, and 0.0001 to 0.1% by weight of rhodium, tin and silver on an alumina carrier also having the above-mentioned crystal structure and pore characteristics. And a catalyst B. In the catalysts A and B, the state of rhodium contained in alumina is not particularly limited, and examples thereof include a metal state, an oxide state, and a mixed state thereof. The state of tin and silver contained in alumina in the catalyst B is as follows:
There is no particular limitation, and examples include a metal state, an oxide state, an alloy state, a composite oxide state, and a mixed state thereof.
In particular, the composition of the combustion exhaust gas of an internal combustion engine such as an automobile changes each time depending on the operation state, and thus the catalyst is exposed to a reducing atmosphere and an oxidizing atmosphere. Therefore, it is assumed that the state of the active metal constituting the catalyst changes depending on the atmosphere. The starting materials of rhodium for the catalyst A and rhodium, tin and silver for the catalyst B are not particularly limited, but use of a water-soluble salt is preferred.
【００１８】そして、触媒Ａにおけるアルミナにロジウ
ムを含有させる方法および触媒Ｂにおけるアルミナにロ
ジウム、錫および銀を含有させる方法は特に限定されず
従来から行われている手法、例えば吸着法、ポアフィリ
ング法、インシピエントウェットネス法、蒸発乾固法、
スプレー法などの含浸法、混練法、物理混合法およびこ
れらの組み合わせ法など通常採用されている公知の方法
を任意に採用することができる。この場合、触媒Ａでは
アルミナあるいはアルミナ前躯体物質にロジウム塩を担
持させた後、乾燥、焼成する。一方触媒Ｂではアルミナ
あるいはアルミナ前躯体物質にロジウムと錫および銀の
各塩を同時に担持させた後、乾燥、焼成してもよいし、
ロジウムと錫および銀の各塩を逐次的に担持させた後、
乾燥、焼成してもよいが、脱硝性能の点でアルミナある
いはアルミナ前躯体物質に予め銀塩を担持させた後、乾
燥、焼成し、さらにロジウムと錫塩を同時または逐次的
に担持して乾燥、焼成した方が好ましい。また、前記の
ような特定の細孔構造をとるアルミナまたはアルミナ担
体の製造時に活性金属種を含有させる触媒製造法、例え
ば触媒Ａではアルミニウムアルコキシドのアルコール溶
液とロジウム塩のアルコール溶液を、触媒Ｂではアルミ
ニウムアルコキシドのアルコール溶液とロジウム、錫、
および銀の各塩のアルコール溶液を混合後、加熱し加水
分解させるアルコキシド法や、触媒Ａではアルミニウム
とロジウムの各塩の混合水溶液に、触媒Ｂではアルミニ
ウム、ロジウム、錫および銀の各塩の混合水溶液にアル
カリを添加して沈殿させる共沈法も適用できる。The method of allowing rhodium to be contained in the alumina of the catalyst A and the method of containing rhodium, tin and silver to the alumina of the catalyst B are not particularly limited, and conventional methods such as an adsorption method and a pore filling method , Incipient wetness method, evaporation to dryness method,
Any commonly used known method such as an impregnation method such as a spray method, a kneading method, a physical mixing method, and a combination thereof can be arbitrarily adopted. In this case, the catalyst A is dried and calcined after a rhodium salt is supported on alumina or an alumina precursor substance. On the other hand, in catalyst B, rhodium, tin and silver salts are simultaneously supported on alumina or an alumina precursor substance, and then dried and calcined.
After successively supporting each salt of rhodium and tin and silver,
Although drying and baking may be performed, alumina or alumina precursor material is preliminarily loaded with a silver salt in terms of denitration performance, then dried and calcined, and rhodium and tin salts are loaded simultaneously or sequentially and dried. It is preferable to fire. Further, a method for producing a catalyst containing an active metal species at the time of producing alumina or an alumina carrier having a specific pore structure as described above, for example, in the case of the catalyst A, an alcohol solution of an aluminum alkoxide and an alcohol solution of a rhodium salt are used. Alcohol solution of aluminum alkoxide and rhodium, tin,
And an alcohol solution of each salt of silver, and then heat and hydrolyze the mixture. Alternatively, catalyst A is mixed with an aqueous solution of aluminum and rhodium salts, and catalyst B is mixed with an aqueous solution of aluminum, rhodium, tin and silver. A coprecipitation method in which an alkali is added to an aqueous solution to cause precipitation is also applicable.
【００１９】触媒Ａに対する金属換算でのロジウムの含
有量は０．００１〜１重量％とする。ロジウム含有量が
１重量％超えると、還元剤である炭化水素の燃焼反応が
過度に促進される結果、脱硝性能が低下し、一方、０．
００１重量未満ではロジウムの添加の効果が発揮されず
経時変化が大きくなるので上記範囲とする必要がある。
また触媒Ｂに対する金属換算でのロジウムの含有量は、
０．０００１〜０．１重量％とする。ロジウム含有量が
０．１重量％を超えると還元剤である炭化水素の燃焼反
応が過度に促進される結果、脱硝性能が低下し、一方、
０．０００１重量未満ではロジウムの添加による相乗効
果が十分発揮されないので上記範囲とする必要がある。
さらに、触媒Ｂに対する金属換算での錫と銀の含有量
は、特に限定されないが、それぞれ０．００１〜５重量
％、０．１〜１０重量％であることが好ましい。The content of rhodium in terms of metal relative to catalyst A is 0.001 to 1% by weight. If the rhodium content exceeds 1% by weight, the combustion reaction of the hydrocarbon as a reducing agent is excessively promoted, and as a result, the denitration performance is reduced.
If the amount is less than 001 weight, the effect of the addition of rhodium is not exhibited, and the change with the passage of time becomes large.
The content of rhodium in terms of metal relative to catalyst B is
0.0001 to 0.1% by weight. If the rhodium content exceeds 0.1% by weight, the combustion reaction of hydrocarbons as a reducing agent is excessively promoted, resulting in a decrease in denitration performance,
If the amount is less than 0.0001 weight, the synergistic effect due to the addition of rhodium is not sufficiently exerted, so the content needs to be in the above range.
Further, the content of tin and silver in terms of metal relative to catalyst B is not particularly limited, but is preferably 0.001 to 5% by weight and 0.1 to 10% by weight, respectively.
【００２０】触媒Ａおよび触媒Ｂの乾燥温度は、特に限
定されるものではなく通常８０〜１２０℃程度で乾燥す
る。また、焼成温度は３００〜１０００℃、好ましくは
４００〜９００℃程度である。焼成温度が１０００℃を
超えると、α−型アルミナへの相変態が起こるので好ま
しくない。このときの雰囲気は特に限定されないが、触
媒組成に応じて空気中、不活性ガス中、酸素中などの各
雰囲気を適宜選択すればよい。また、各雰囲気を一定時
間毎に交互に代えてもよい。The drying temperature of the catalyst A and the catalyst B is not particularly limited, and is usually dried at about 80 to 120 ° C. The firing temperature is 300 to 1000 ° C, preferably about 400 to 900 ° C. If the firing temperature exceeds 1000 ° C., phase transformation to α-type alumina occurs, which is not preferable. The atmosphere at this time is not particularly limited, but each atmosphere such as in air, in an inert gas, or in oxygen may be appropriately selected according to the catalyst composition. In addition, each atmosphere may be alternately changed at regular intervals.
【００２１】本発明の第１の実施態様において、排ガス
浄化用の触媒層を形成するに際し、該触媒層は上記した
触媒を所定の形状に成型または粉末状態のまま目的とす
る排ガスが流通する一定の空間内に充填する。触媒層を
成型体とするに際して、その形状は特に制限されず、例
えば球状、円筒状、ハニカム状、螺旋状、粒状、ペレッ
ト状、リング状など種々の形状を採用することができ
る。これらの形状、大きさなどは使用条件に応じて任意
に選択すればよい。In the first embodiment of the present invention, when a catalyst layer for purifying exhaust gas is formed, the catalyst layer is formed into a predetermined shape or a predetermined shape through which a target exhaust gas flows in a powder state. Fill in the space. When the catalyst layer is formed into a molded body, its shape is not particularly limited, and various shapes such as a spherical shape, a cylindrical shape, a honeycomb shape, a spiral shape, a granular shape, a pellet shape, and a ring shape can be adopted. These shapes, sizes, and the like may be arbitrarily selected according to use conditions.
【００２２】次に、本発明の第２の実施態様の排ガス浄
化用触媒被覆構造体について説明する。ここでいう触媒
被覆構造体とは、多数の貫通孔を有する耐火性材料で構
成された一体構造の支持基質の少なくとも貫通孔の内表
面に上記した触媒を区分して被覆した構造を有するもの
である。Next, an exhaust gas purifying catalyst-coated structure according to a second embodiment of the present invention will be described. The catalyst-coated structure referred to here has a structure in which at least the inner surface of the through-hole is coated with the above-described catalyst in a single-piece support substrate made of a refractory material having a large number of through-holes. is there.
【００２３】該支持基質には、多数の貫通孔が排ガスの
流通方向に沿って設けられるが、その流通方向に垂直な
断面において、通常、開孔率６０〜９０％、好ましくは
７０〜９０％であって、その数は１平方インチ（５．０
６ｃｍ２）当り３０〜７００個、好ましくは２００〜６
００個である。触媒は、少なくとも該貫通孔の内表面に
被覆されるが、その支持基質の端面や側面に区分されて
被覆されていてもよい。The support substrate is provided with a large number of through holes along the flow direction of the exhaust gas. In a section perpendicular to the flow direction, the porosity is usually 60 to 90%, preferably 70 to 90%. And the number is one square inch (5.0
30 to 700, preferably 200 to 6, 6 cm 2 )
00. The catalyst is coated on at least the inner surface of the through-hole, but may be coated separately on the end surface or side surface of the supporting substrate.
【００２４】該耐火性支持基質の材質としては、α−型
アルミナ、ムライト、コージェライト、シリコンカーバ
イトなどのセラミックスやオーステナイト系、フェライ
ト系のステンレス鋼などの金属などが使用される。形状
もハニカムやフォームなどの慣用のものが使用できる
が、好ましいものはコージェライト製やステンレス鋼製
のハニカム状の支持基質である。As the material of the refractory support substrate, ceramics such as α-type alumina, mullite, cordierite, and silicon carbide, and metals such as austenitic and ferritic stainless steels are used. The shape may be a conventional one such as a honeycomb or a foam, but a preferred one is a cordierite or stainless steel honeycomb supporting substrate.
【００２５】該支持基質への触媒の被覆方法としては、
一定の粒度に整粒した本発明の触媒をバインダーと共
に、またはバインダーを用いないで前記支持基質の内表
面に区分して被覆する、いわゆる通常のウォッシュコー
ト法やゾル−ゲル法が適用できる。また上記の支持基質
に予めアルミナを被覆しておいて、これに本発明の触媒
活性物質の担持処理を行って触媒被覆層を形成してもよ
い。支持基質への触媒層の被覆量は特に限定されない
が、支持基質単位体積当り５０〜２５０ｇ／リットル程
度が好ましく、１００〜２００ｇ／リットル程度とする
ことがより好ましい。The method of coating the support substrate with a catalyst includes:
A so-called ordinary wash coat method or a sol-gel method, in which the catalyst of the present invention sized to a certain particle size is separately coated on the inner surface of the supporting substrate with or without a binder, can be applied. Alternatively, the support substrate may be coated with alumina in advance, and the catalyst support layer of the present invention may be subjected to the treatment to form a catalyst coating layer. The coating amount of the catalyst layer on the support substrate is not particularly limited, but is preferably about 50 to 250 g / L, more preferably about 100 to 200 g / L per unit volume of the support substrate.
【００２６】次に、本発明の第３の実施態様の排ガス浄
化方法について説明する。本発明の第３の実施態様は、
第１の実施態様の触媒層や第２の実施態様の触媒被覆構
造体を使用して、これと排ガス中のＣＯ、ＨＣおよびＨ
２といった還元性成分をΝＯｘおよびＯ２といった酸化
性成分で完全酸化するに要する化学量論量近傍から過剰
の酸素を含有する排ガスとを接触させることによって、
ΝＯｘはＮ２とΗ２Ｏにまで還元分解させると同時にＨ
Ｃなどの還元剤もＣＯ２とＨ２Ｏに酸化させるものであ
る。Next, an exhaust gas purifying method according to a third embodiment of the present invention will be described. A third embodiment of the present invention provides:
Using the catalyst layer of the first embodiment or the catalyst-coated structure of the second embodiment, CO, HC and H in the exhaust gas are used.
By contacting the exhaust gas containing excess oxygen from the stoichiometry near requiring 2 such reducing component to be completely oxidized in the oxidizing components such ΝOx and O 2,
ΝOx is reduced and decomposed to N 2 and と 同時 に2 O,
A reducing agent such as C also oxidizes CO 2 and H 2 O.
【００２７】本発明において、触媒Ａを前段に、触媒Ｂ
を後段に配置させる理由およびロジウム量を触媒Ｂより
も触媒Ａで多くする理由は、触媒層入口部で還元剤であ
る炭化水素の不完全燃焼によるコーキングを防止して、
トータル触媒システムでの耐久性を向上させるためであ
る。なお触媒Ａと触媒Ｂの割合は、要求性能に応じて適
宜選択すればよい。In the present invention, the catalyst A is placed before the catalyst B,
The reason for disposing the latter in the latter stage and the reason for increasing the rhodium amount in the catalyst A than in the catalyst B are to prevent coking due to incomplete combustion of the hydrocarbon as the reducing agent at the inlet of the catalyst layer,
This is for improving the durability of the total catalyst system. The ratio between the catalyst A and the catalyst B may be appropriately selected according to the required performance.
【００２８】ディーゼルエンジンの排ガスのように、排
ガスそのもののＨＣ／ＮＯｘ比が低い場合には、排ガス
中にメタン換算濃度で数百〜数千ｐｐｍ程度の燃料ΗＣ
を追加添加した後、本発明の触媒と接触させるシステム
を採用すれば充分に高いＮＯｘ除去率を達成できる。な
お、ここでいうＨＣとは、パラフィン系炭化水素、オレ
フィン系炭化水素および芳香族系炭化水素、アルコー
ル、アルデヒド、ケトン、エーテルなどの含酸素有機化
合物、ガソリン、灯油、軽油、Ａ重油などを含んだもの
を意味する。When the HC / NOx ratio of the exhaust gas itself is low, such as the exhaust gas of a diesel engine, the fuel ΗC having a concentration of several hundreds to several thousands ppm in terms of methane concentration in the exhaust gas.
If the system for contacting with the catalyst of the present invention is added after additionally adding, a sufficiently high NOx removal rate can be achieved. Note that HC referred to here includes paraffinic hydrocarbons, olefinic hydrocarbons and aromatic hydrocarbons, oxygen-containing organic compounds such as alcohols, aldehydes, ketones, and ethers, gasoline, kerosene, light oil, heavy oil A, and the like. Means something.
【００２９】本発明による触媒層を用いて、希薄空燃比
の領域で運転される内燃機関の燃焼排気ガスを浄化する
際のガス空間速度（ＳＶ）は特に限定されるものではな
いが、ＳＶ５，０００ｈ−１以上で２００，０００ｈ
−１以下とすることが好ましい。The gas space velocity (SV) when purifying the combustion exhaust gas of the internal combustion engine operated in the lean air-fuel ratio region using the catalyst layer according to the present invention is not particularly limited. 200,000h over 000h -1
It is preferably set to -1 or less.
【００３０】そして、ガス組成を一定とした場合の脱硝
率は触媒の種類とＨＣの種類に依存するが、本発明の触
媒層を用いた場合は、例えばＣ２〜Ｃ６のパラフィン、
オレフィンおよびＣ６〜Ｃ９の芳香族ＨＣに対しては４
５０〜６００℃、Ｃ６〜Ｃ９のパラフィンおよびオレフ
ィンに対しては３５０〜５５０℃、Ｃ１０〜Ｃ２５のパ
ラフィンおよびオレフィンに対しては２５０〜５００℃
で高い脱硝率を示すため触媒層入口温度を１００℃以上
で７００℃以下、好ましくは２００℃以上で６００℃以
下にすることが必要である。The denitration rate when the gas composition is constant depends on the type of catalyst and the type of HC. In the case of using the catalyst layer of the present invention, for example, C 2 -C 6 paraffin,
For aromatic HC olefins and C 6 -C 9 4
50-600 ° C., 350-550 ° C. for C 6 -C 9 paraffins and olefins, 250-500 ° C. for C 10 -C 25 paraffins and olefins.
In order to exhibit a high denitrification rate, it is necessary to set the catalyst layer inlet temperature at 100 ° C. or higher to 700 ° C. or lower, preferably at 200 ° C. or higher to 600 ° C. or lower.
【００３１】[0031]
【実施例】以下に実施例および比較例により、本発明を
さらに詳細に説明する。但し、本発明は下記実施例に限
定されるものでない。 （１）アルミナの選定 使用アルミナ担体の選定のために、表１に示すような比
表面積と細孔分布を有する種々のγ一型アルミナにおい
て、ａ〜ｃが本発明の範囲に入るアルミナであり、ｄ〜
ｇが本発明の範囲外のアルミナである。なお、ａ〜ｇの
アルミナの細孔分布は、カルロエルバ社製のソープトマ
チックにより測定した。The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following examples. (1) Selection of Alumina In order to select an alumina carrier to be used, a to c are aluminas which fall within the scope of the present invention among various γ-type aluminas having specific surface areas and pore distributions as shown in Table 1. , D ~
g is alumina outside the scope of the present invention. In addition, the pore distribution of alumina of a to g was measured by a soapmatic manufactured by Carlo Elba.
【００３２】[0032]
【表１】 ───────────────────────────────── アルミナ 比表面積 細 孔 分 布 （ｍ２／ｇ） Ｙ／Χ（％） Ｚ／Χ（％） ───────────────────────────────── ａ ２４１ ８３．２ ２．４ ｂ ２１９ ８７．０ ３．９ ｃ １７４ ８８．４ ４．４ ｄ １９９ ４７．０ ０．７ ｅ １７７ ６８．５ ４．９ ｆ ２４１ ５１．０ ４５．９ ｇ ２６６ ７１．１ ２２．７ ─────────────────────────────────[Table 1] ア ル ミ ナ Alumina specific surface area pore distribution (m 2 / g) Y / Χ (%) Z / Χ (%) ─────────────────────────────────a 241 83.2 2.4 b 219 87.0 3.9 c 174 88.4 4.4 d 199 47.0 0.7 e 177 68.5 4.9 f 241 51.0 45.9 g 266 71.1 22. 7 ─────────────────────────────────
【００３３】（２）触媒層の調製 以下に、本発明の触媒層を構成するための各触媒の調製
についての調製例を参考例として示す。 （イ）触媒Ｂの製造： ［参考例１］表１のγ一型アルミナａの前駆体物質であ
るアルミナ水和物３００ｇを硝酸銀１６．１ｇを含む５
００ミリリットルの水溶液に浸漬した後、撹拌しながら
加熱し水分を蒸発させた。これを１１０℃で通風乾燥
後、空気中５５０℃で３時間焼成してＡｇ／Ａｌ２Ｏ３
を得た。つぎに、Ａｇ／Ａｌ２Ｏ３１００ｇを硝酸ロジ
ウム水溶液（Ｒｈ濃度５％）０．０１６ｇおよび塩化第
二錫５水和物０．３ｇを含む５００ミリリットル水溶液
に浸漬した後、前記Ａｇ／Ａｌ２Ｏ３と同様の方法にて
触媒１を得た。なお、触媒１における金属換算でのＡ
ｇ、ＲｈおよびＳｎの含有量は、触媒全体に対してそれ
ぞれ４．５重量％、０．０００８重量％、０．１重量％
である。(2) Preparation of Catalyst Layer Hereinafter, preparation examples of preparation of each catalyst for constituting the catalyst layer of the present invention are shown as reference examples. (A) Production of catalyst B: [Reference Example 1] A sample containing 300 g of alumina hydrate, which is a precursor of γ-type alumina a in Table 1, containing 16.1 g of silver nitrate 5
After being immersed in an aqueous solution of 00 ml, the mixture was heated with stirring to evaporate water. This is air-dried at 110 ° C., and then calcined in air at 550 ° C. for 3 hours to obtain Ag / Al 2 O 3
I got Then, after immersing the Ag / Al 2 O 3 100g 500ml aqueous solution containing rhodium nitrate solution (Rh concentration 5%) 0.016 g and stannic chloride pentahydrate 0.3 g, the Ag / Al 2 Catalyst 1 was obtained in the same manner as for O 3 . In the catalyst 1, A in metal conversion
The contents of g, Rh and Sn were 4.5% by weight, 0.0008% by weight and 0.1% by weight, respectively, based on the whole catalyst.
It is.
【００３４】［参考例２〜参考例１１］同様に、表１に
示すγ一型アルミナｂ〜ｇが得られる前駆体物質である
アルミナ水和物を用いた以外は、参考例１と同様にして
それぞれ触媒２（参考例２）、触媒３（参考例３）、触
媒４（参考例４）、触媒５（参考例５）、触媒６（参考
例６）、触媒７（参考例７）を得た。また、参考例１の
触媒１の調製に際し、銀の含有量を０重量％、２重量
％、３重量％および８重量％とした以外は参考例１と同
様にして、それぞれ触媒８（参考例８）、触媒９（参考
例９）、触媒１０（参考例１０）、触媒１１（参考例１
１）を得た。Reference Examples 2 to 11 Similarly to Reference Example 1, except that alumina hydrate, which is a precursor substance from which γ-type aluminas b to g shown in Table 1 were obtained, was used. Catalyst 2 (Reference Example 2), Catalyst 3 (Reference Example 3), Catalyst 4 (Reference Example 4), Catalyst 5 (Reference Example 5), Catalyst 6 (Reference Example 6), and Catalyst 7 (Reference Example 7) Obtained. Catalyst 8 (Reference Example 1) was prepared in the same manner as in Reference Example 1 except that the silver content was set to 0% by weight, 2% by weight, 3% by weight, and 8% by weight when preparing Catalyst 1 of Reference Example 1. 8), Catalyst 9 (Reference Example 9), Catalyst 10 (Reference Example 10), Catalyst 11 (Reference Example 1)
1) was obtained.
【００３５】（ロ）触媒Ａの製造： ［参考例１２〜参考例１７］表１に示すγ一型アルミナ
ａの前駆体物質であるアルミナ水和物３００ｇを、硝酸
ロジウム水溶液（Ｒｈ濃度５％）１．３ｇを含む５００
ミリリットル水溶液に浸漬した後、撹拌しながら加熱し
水分を蒸発させた以外は、参考例１の触媒１と同様にし
て触媒１２（参考例１２）を得た。なお触媒１２におけ
る金属換算でのＲｈの含有量は触媒全体に対して０．０
３重量％である。また、参考例１２の触媒１２の調製に
際し、ロジウムの含有量を０重量％、０．００８重量
％、０．０５重量％、２重量％とした以外は参考例１０
と同様にして、それぞれ触媒１３（参考例１３）、触媒
１４（参考例１４）、触媒１５（参考例１５）および触
媒１６（参考例１６）を、さらに表１に示すγ一型アル
ミナｆを用いた以外は参考例１０と同様にして触媒１７
（参考例１７）を得た。(B) Production of catalyst A: [Reference Examples 12 to 17] 300 g of alumina hydrate, which is a precursor of γ-type alumina a shown in Table 1, was treated with a rhodium nitrate aqueous solution (Rh concentration 5%). 500) containing 1.3 g)
Catalyst 12 (Reference Example 12) was obtained in the same manner as in Catalyst 1 of Reference Example 1, except that the resultant was immersed in a milliliter aqueous solution and then heated to evaporate water while stirring. The content of Rh in the catalyst 12 in terms of metal was 0.0
3% by weight. Reference Example 10 was repeated except that the rhodium content was changed to 0% by weight, 0.008% by weight, 0.05% by weight, and 2% by weight when preparing the catalyst 12 of Reference Example 12.
Catalyst 13 (Reference Example 13), Catalyst 14 (Reference Example 14), Catalyst 15 (Reference Example 15) and Catalyst 16 (Reference Example 16), and γ-type alumina f shown in Table 1 Catalyst 17 was used in the same manner as in Reference Example 10 except that it was used.
(Reference Example 17) was obtained.
【００３６】（ハ）ハニカム触媒の製造： ［参考例１８および参考例１９］上記の粉末触媒１の６
０ｇを、アルミナゾル（Αｌ２Ｏ３固形分２０重量％）
５ｇおよび水１２０ミリリットルと共にボールミルポッ
トに仕込み、湿式粉砕してスラリーを得た。このスラリ
ーの中に、市販の４００ｃｐｓｉ（セル／ｉｎｃｈ２）
コージェライトハニカム基質からくり貫かれた直径１イ
ンチ、長さ２．５インチの円筒状コアを浸漬し、引き上
げた後余分のスラリーをエアーブローで除去し乾燥し
た。その後、５００℃で３０分焼成し、ハニカム１リッ
トル当たりドライ換算で１５０ｇの固形分を被覆してハ
ニカム触媒１８（参考例１８）を得た。(C) Manufacture of honeycomb catalyst: [Reference Examples 18 and 19] 6 of the above powder catalyst 1
0 g of alumina sol (Αl 2 O 3 solid content 20% by weight)
5 g and 120 ml of water were charged into a ball mill pot and wet-pulverized to obtain a slurry. In this slurry, a commercially available 400 cpsi (cell / inch 2 )
A cylindrical core having a diameter of 1 inch and a length of 2.5 inches penetrated from a cordierite honeycomb substrate was immersed and pulled up, and then excess slurry was removed by air blow and dried. Then, it was baked at 500 ° C. for 30 minutes, and coated with 150 g of solid content in terms of dry weight per liter of honeycomb to obtain a honeycomb catalyst 18 (Reference Example 18).
【００３７】また、上記の粉末触媒１２の６０ｇを、そ
れぞれアルミナゾル（Αｌ２Ｏ３固形分１０重量％）８
ｇおよび水１２０ミリリットルと共にボールミルポット
に仕込み、湿式粉砕してスラリーを得た。このスラリー
の中に、市販の４００ｃｐｓｉ（セル／ｉｎｃｈ２）コ
ージェライトハニカム基質からくり貫かれた直径１イン
チ、長さ２．５インチの円筒状コアを浸漬し、引き上げ
た後余分のスラリーをエアーブローで除去し乾燥した。
その後、５００℃で３０分焼成し、ハニカム１リットル
当たりドライ換算で１５０ｇの固形分を被覆してハニカ
ム触媒１９（参考例１９）を得た。In addition, 60 g of the above-mentioned powdered catalyst 12 was mixed with alumina sol (Αl 2 O 3 solid content 10% by weight) 8
g and 120 ml of water were charged into a ball mill pot and wet-pulverized to obtain a slurry. A cylindrical core having a diameter of 1 inch and a length of 2.5 inches penetrated from a commercially available 400 cpsi (cell / inch 2 ) cordierite honeycomb substrate is immersed in the slurry, and the excess slurry is air blown. And dried.
Thereafter, the mixture was baked at 500 ° C. for 30 minutes, and coated with 150 g of solid content in terms of dry weight per liter of honeycomb to obtain a honeycomb catalyst 19 (Reference Example 19).
【００３８】以下に上記した参考例１〜１９の触媒を用
いて形成した排ガス浄化用触媒層について、種々の条件
下において脱硝性能を評価した結果について述べる。 ［実施例１］参考例１２の触媒１２と参考例１の触媒１
をそれぞれ加圧成型した後、粉砕して粒度を３５０〜５
００μｍに整粒し、排ガスの流通方向に対して触媒１２
が前段に、触媒１が後段になるように内径１５ｍｍのス
テンレス製反応管に充填して触媒層を形成し、これを常
圧固定床流通反応装置に装着した。なお、触媒１２と触
媒１の重量比は１：１である。The results of evaluating the denitration performance of the exhaust gas purifying catalyst layers formed using the catalysts of Reference Examples 1 to 19 under various conditions will be described below. Example 1 Catalyst 12 of Reference Example 12 and Catalyst 1 of Reference Example 1
Is press-molded, and then pulverized to a particle size of 350 to 5
The particle size is adjusted to 00 μm, and the catalyst 12
Was filled in a stainless steel reaction tube having an inner diameter of 15 mm so that the catalyst 1 was placed in the former stage to form a catalyst layer, and this was attached to a normal pressure fixed bed flow reactor. The weight ratio between the catalyst 12 and the catalyst 1 is 1: 1.
【００３９】［性能評価例１］この触媒層に、反応管内
の排ガス温度を４２５℃に保ち、モデル排ガスとしてＮ
Ｏ：７５０ｐｐｍ、灯油（Ｃ１）：４５００ｐｐｍ、Ｏ
２：１０％、ＳＯ２：１０ｐｐｍ、Ｈ２Ｏ：１０％、残
部：Ｎ２からなる混合ガスを空間速度７８，０００ｈ
−１で通過させた。反応管出口ガス組成の分析におい
て、ＮＯとＮＯ２の濃度については化学発光式ＮＯｘ計
で測定し、Ｎ２Ｏ濃度はΡｏｒａｐａｃｋ Ｑカラムを
装着したガスクロマトグラフ・熱伝導度検出器を用いて
測定した。脱硝率は以下の式１で定義した。また、本発
明のいずれの触媒でもＮ２ＯおよびＮＯ２は殆ど生成し
なかった。[Performance Evaluation Example 1] The temperature of the exhaust gas in the reaction tube was maintained at 425 ° C.
O: 750 ppm, kerosene (C 1 ): 4500 ppm, O
2: 10%, SO 2: 10ppm, H 2 O: 10%, the balance space, a mixed gas consisting of N 2 velocity 78,000h
-1 . In the analysis of the gas composition at the outlet of the reaction tube, the concentrations of NO and NO 2 were measured with a chemiluminescent NOx meter, and the N 2 O concentration was measured with a gas chromatograph / thermal conductivity detector equipped with a Ρorapack Q column. . The denitration rate was defined by the following equation 1. Further, N 2 O and NO 2 were hardly produced by any of the catalysts of the present invention.
【００４０】[0040]
【式１】 (Equation 1)
【００４１】［実施例２〜８および比較例１〜８］参考
例２、３、９、１０、１１の触媒２、３、９、１０、１
１および参考例４〜８の触媒４〜８をそれぞれ実施例１
の触媒１の代わりに用いて、上記と同様の触媒層を形成
し、同様にしてモデルガスによる評価試験を行った。触
媒２、３、９、１０、１１を用いた触媒層を、それぞれ
実施例２〜６とし、触媒４〜８を用いた触媒層を、それ
ぞれ比較例１〜５とした。また、実施例１の触媒１２の
代わりに、参考例１３〜１７の触媒１３〜１７用いて、
実施例１と同様の触媒層を形成し、同様にしてモデルガ
スによる評価試験を行った。触媒１４、１５を用いた触
媒層を、それぞれ実施例７、８とし、触媒１３、１６、
１７を用いた触媒層を、それぞれ比較例６〜８とした。
表２に、上記実施例および比較例の触媒層について初期
脱硝性能を示す。Examples 2 to 8 and Comparative Examples 1 to 8 Catalysts 2, 3, 9, 10, and 1 of Reference Examples 2, 3, 9, 10, and 11
Example 1 and Catalysts 4 to 8 of Reference Examples 4 to 8
A catalyst layer similar to the above was formed using the catalyst 1 in place of the above-described catalyst 1, and an evaluation test using a model gas was performed in the same manner. The catalyst layers using catalysts 2, 3, 9, 10, and 11 were Examples 2 to 6, respectively, and the catalyst layers using catalysts 4 to 8 were Comparative Examples 1 to 5, respectively. Further, instead of the catalyst 12 of Example 1, the catalysts 13 to 17 of Reference Examples 13 to 17 were used,
A catalyst layer similar to that of Example 1 was formed, and an evaluation test using a model gas was performed in the same manner. The catalyst layers using the catalysts 14 and 15 are referred to as Examples 7 and 8, respectively, and the catalysts 13 and 16 and
17 were used as Comparative Examples 6 to 8, respectively.
Table 2 shows the initial denitration performance of the catalyst layers of the above Examples and Comparative Examples.
【００４２】［性能評価例２（実施例９）］性能評価例
１において、参考例１８のハニカム触媒１８を直径１５
ｍｍ、長さ３２ｍｍに、参考例１９のハニカム触媒１９
を直径１５ｍｍ、長さ３．２ｍｍの円筒状に加工し、排
ガスの流通方向に対してハニカム触媒１９が前段に、ハ
ニカム触媒１８が後段になるように、内径１５ｍｍのス
テンレス製反応管に充填した。ハニカム触媒１８の触媒
層に対して、フィードするガスの空間速度を１３，００
０ｈ−１とした以外は性能評価例１と同様のモデルガス
による評価試験を行い、その結果を表２に併せて示す。[Performance Evaluation Example 2 (Example 9)] In the performance evaluation example 1, the honeycomb catalyst 18 of Reference Example 18 was replaced with a diameter 15 mm.
mm, length 32 mm, the honeycomb catalyst 19 of Reference Example 19
Was processed into a cylindrical shape having a diameter of 15 mm and a length of 3.2 mm, and was filled in a stainless steel reaction tube having an inner diameter of 15 mm such that the honeycomb catalyst 19 was at the front stage and the honeycomb catalyst 18 was at the rear stage in the flow direction of the exhaust gas. . The space velocity of the gas to be fed to the catalyst layer of the honeycomb catalyst 18 is 13,000
An evaluation test was performed using the same model gas as in Performance Evaluation Example 1 except that 0 h −1 was set, and the results are also shown in Table 2.
【００４３】[0043]
【表２】 ────────────────────────── 触 媒 層 初期性能 前段 後段 脱硝率（％） ────────────────────────── 実施例１ 触媒１２十触媒１ ７５ 実施例２ 触媒１２十触媒２ ７２ 実施例３ 触媒１２十触媒３ ７１ 比較例１ 触媒１２十触媒４ ２５ 比較例２ 触媒１２十触媒５ ９ 比較例３ 触媒１２十触媒６ ３１ 比較例４ 触媒１２十触媒７ ２７ 比較例５ 触媒１２十触媒８ ３０ 実施例４ 触媒１２十触媒９ ６９ 実施例５ 触媒１２十触媒１０ ７２ 実施例６ 触媒１２十触媒１１ ６３ 比較例６ 触媒１３十触媒１ ８６ 実施例７ 触媒１４十触媒１ ７７ 実施例８ 触媒１５十触媒１ ６０ 比較例７ 触媒１６十触媒１ ２０ 比較例８ 触媒１７十触媒１ ２０ 実施例９ 触媒１９十触媒１８ ７０ ──────────────────────────[Table 2] ────────────────────────── Catalyst layer Initial performance First stage Second stage Denitration rate (%) ──────── １ Example 1 Catalyst 12 and Catalyst 1 75 Example 2 Catalyst 12 and Catalyst 2 72 Example 3 Catalyst 12 and Catalyst 3 71 Comparative Example 1 Catalyst 12 Ten Catalyst 4 25 Comparative Example 2 Catalyst 12 Ten Catalyst 5 9 Comparative Example 3 Catalyst 12 Ten Catalyst 6 31 Comparative Example 4 Catalyst 12 Ten Catalyst 7 27 Comparative Example 5 Catalyst 12 Ten Catalyst 8 30 Example 4 Catalyst 12 Ten Catalyst 9 69 Implementation Example 5 Catalyst 12 and 10 Catalyst 10 72 Example 6 Catalyst 12 and 10 Catalyst 11 63 Comparative Example 6 Catalyst 13 and 10 Catalyst 1 86 Example 7 Catalyst 14 and 10 Catalyst 1 77 Example 8 Catalyst 15 and 10 Catalyst 1 60 Comparative Example 7 Catalyst 16 and 10 Catalyst 1 20 Comparative Example 8 Catalyst 17 and Catalyst 1 20 Example 9 Catalyst 19 and Catalyst 18 70 ──────────────────────────
【００４４】表２より実施例１〜９および比較例６は、
初期性能が６０％以上であり、比較例１〜５、７、８に
比べて優れた性能を示した。From Table 2, Examples 1 to 9 and Comparative Example 6
The initial performance was 60% or more, showing superior performance as compared with Comparative Examples 1 to 5, 7, and 8.
【００４５】［性能評価例３］実施例１の触媒層に性能
評価例１と同様のモデルガスを用いて、耐久試験を行っ
た。表３に活性が安定した時点の値を用いて求めた経時
変化率を示す。経時変化率を以下の式２で定義した。[Performance Evaluation Example 3] A durability test was performed on the catalyst layer of Example 1 using the same model gas as in Performance Evaluation Example 1. Table 3 shows the rate of change over time obtained using the value at the time when the activity was stabilized. The change with time was defined by the following equation 2.
【００４６】[0046]
【式２】 (Equation 2)
【００４７】[0047]
【表３】 ──────────────────────── 触 媒 経時変化率 前段 後段 （％） ──────────────────────── 実施例１ 触媒１２十触媒１ ２８ 比較例６ 触媒１３十触媒１ ５５ ──────────────────────── 表３より明らかな通り実施例１は、比較例６に比べ、耐
久後の経時変化率が小さかった。[Table 3] 率 Catalyst Change over time First stage Second stage (%) ──────────── Example 1 Catalyst 12 and Catalyst 1 28 Comparative Example 6 Catalyst 13 and Catalyst 1 55通 り As is clear from Table 3, Example 1 had a smaller rate of change with time after endurance than Comparative Example 6.
【００４８】[0048]
【発明の効果】以上のように、本発明による排ガス浄化
用触媒層および排ガス浄化用触媒被覆構造体と、これら
を用いた排ガス浄化方法によれば、ＳＯｘと水蒸気が共
存する希薄燃焼排ガス中に含まれる窒素酸化物を高い脱
硝率で還元浄化でき、かつ経時変化率が小さいことから
内燃機関の燃焼排ガス中の窒素酸化物の浄化に有用であ
る。As described above, according to the exhaust gas purifying catalyst layer and the exhaust gas purifying catalyst coating structure of the present invention and the exhaust gas purifying method using the same, the lean combustion exhaust gas in which SOx and steam coexist is contained in the exhaust gas. Since nitrogen oxides contained therein can be reduced and purified at a high denitration rate and have a small rate of change with time, they are useful for purification of nitrogen oxides in combustion exhaust gas of an internal combustion engine.
フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｂ０１Ｄ 53/36 １０２Ａ １０２Ｂ (72)発明者 加岳井 敦 千葉県市川市中国分３−18−５ 住友金属 鉱山株式会社中央研究所内 (72)発明者 船曳 正起 静岡県沼津市一本松678 エヌ・イーケム キャット株式会社沼津工場内Continuation of the front page (51) Int.Cl. 6 Identification symbol FI B01D 53/36 102A 102B (72) Inventor Atsushi Katakei 3-18-5, Chugoku, Ichikawa-shi, Chiba Sumitomo Metal Mining Co., Ltd. 72) Inventor Masaki Funabiki 678 Ipponmatsu, Numazu City, Shizuoka Prefecture
Claims (5)
のロジウムを含有させてなる触媒Ａと、アルミナ担体
に、０．０００１〜０．１重量％のロジウムと、錫およ
び銀を含有させてなる触媒Ｂとから構成され、前記両ア
ルミナ担体は窒素ガス吸着法により測定された細孔半径
と細孔容積の関係が、細孔半径３００オングストローム
以下の細孔の占める細孔容積の合計値をＸとし、細孔半
径２５オングストローム以上で１００オングストローム
未満の細孔の占める細孔容積の合計値をＹとし、細孔半
径１００オングストローム以上で３００オングストロー
ム以下の細孔の占める細孔容積の合計値をＺとしたと
き、ＹがＸの７０％以上であり、ＺがＸの２０％以下で
あるような細孔構造を有することを特徴とする排ガス浄
化用触媒層。1. An alumina carrier containing 0.001 to 1% by weight
And a catalyst B containing 0.0001 to 0.1% by weight of rhodium and tin and silver in an alumina carrier, and the alumina carrier contains nitrogen gas. The relationship between the pore radius and the pore volume measured by the adsorption method is as follows: X is the total value of the pore volume occupied by pores having a pore radius of 300 Å or less, and a fine pore having a pore radius of 25 Å or more and less than 100 Å. When the total value of the pore volume occupied by the pores is Y and the total value of the pore volume occupied by the pores having a radius of 100 Å or more and 300 Å or less is Z, Y is 70% or more of X; An exhaust gas purifying catalyst layer having a pore structure in which Z is 20% or less of X.
る一体構造の支持基質における少なくとも貫通孔の内表
面に請求項１記載の触媒層を区分して被覆してなる排ガ
ス浄化用触媒被覆構造体。2. A catalyst coating structure for purifying an exhaust gas, wherein at least an inner surface of a through-hole in a support substrate having an integral structure made of a refractory material having a large number of through-holes is divided and coated with the catalyst layer according to claim 1. body.
排ガスを、触媒含有層と接触させることからなる炭化水
素を還元剤とする排ガス浄化方法において、前記触媒含
有層に含まれる触媒は請求項１記載の排ガス浄化用触媒
層であることを特徴とする排ガス浄化方法。3. A method for purifying exhaust gas using a hydrocarbon as a reducing agent, which comprises contacting flue gas of an internal combustion engine operated at a lean air-fuel ratio with a catalyst-containing layer, wherein the catalyst contained in the catalyst-containing layer is Item 7. An exhaust gas purifying method comprising the exhaust gas purifying catalyst layer according to Item 1.
排ガスを、触媒含有層と接触させることからなる炭化水
素を還元剤とする排ガス浄化方法において、前記触媒含
有層に含まれる触媒は請求項２記載の排ガス浄化用触媒
被覆構造体で構成することを特徴とする排ガス浄化方
法。4. A method for purifying exhaust gas using a hydrocarbon as a reducing agent, which comprises contacting flue gas from an internal combustion engine operated at a lean air-fuel ratio with a catalyst-containing layer, wherein the catalyst contained in the catalyst-containing layer is Item 3. An exhaust gas purifying method comprising the exhaust gas purifying catalyst-coated structure according to Item 2.
触媒層に含まれる触媒Ａが前段に、触媒Ｂが後段に区分
されて配置されていることを特徴とする請求項３または
４記載の排ガス浄化方法。5. The catalyst according to claim 3, wherein the catalyst A contained in the exhaust gas purifying catalyst layer is disposed at a front stage and the catalyst B is disposed at a rear stage in a flow direction of the exhaust gas. Exhaust gas purification method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9113379A JPH10286463A (en) | 1997-04-15 | 1997-04-15 | Catalytic layer for purification of exhaust gas, catalytic structure for purification of exhaust gas and method for purifying exhaust gas with the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9113379A JPH10286463A (en) | 1997-04-15 | 1997-04-15 | Catalytic layer for purification of exhaust gas, catalytic structure for purification of exhaust gas and method for purifying exhaust gas with the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10286463A true JPH10286463A (en) | 1998-10-27 |
Family
ID=14610809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9113379A Pending JPH10286463A (en) | 1997-04-15 | 1997-04-15 | Catalytic layer for purification of exhaust gas, catalytic structure for purification of exhaust gas and method for purifying exhaust gas with the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10286463A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010504205A (en) * | 2006-09-20 | 2010-02-12 | ビーエーエスエフ、カタリスツ、エルエルシー | Catalyst for reducing NOx in exhaust gas flow and method for producing the same |
-
1997
- 1997-04-15 JP JP9113379A patent/JPH10286463A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010504205A (en) * | 2006-09-20 | 2010-02-12 | ビーエーエスエフ、カタリスツ、エルエルシー | Catalyst for reducing NOx in exhaust gas flow and method for producing the same |
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