JPH02191548A - Catalyst for purification of exhaust gas - Google Patents
Catalyst for purification of exhaust gasInfo
- Publication number
- JPH02191548A JPH02191548A JP1009394A JP939489A JPH02191548A JP H02191548 A JPH02191548 A JP H02191548A JP 1009394 A JP1009394 A JP 1009394A JP 939489 A JP939489 A JP 939489A JP H02191548 A JPH02191548 A JP H02191548A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- exhaust gas
- hydrogen sulfide
- palladium
- oxide
- 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
- 239000003054 catalyst Substances 0.000 title claims abstract description 84
- 238000000746 purification Methods 0.000 title claims abstract description 25
- 229910003445 palladium oxide Inorganic materials 0.000 claims abstract description 29
- JQPTYAILLJKUCY-UHFFFAOYSA-N palladium(ii) oxide Chemical compound [O-2].[Pd+2] JQPTYAILLJKUCY-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910000420 cerium oxide Inorganic materials 0.000 claims abstract description 23
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052751 metal Inorganic materials 0.000 claims abstract description 22
- 239000002184 metal Substances 0.000 claims abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 17
- 239000007789 gas Substances 0.000 abstract description 45
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 abstract description 29
- 229910000037 hydrogen sulfide Inorganic materials 0.000 abstract description 29
- 230000003197 catalytic effect Effects 0.000 abstract description 10
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052703 rhodium Inorganic materials 0.000 abstract description 6
- 238000007254 oxidation reaction Methods 0.000 abstract description 4
- 229910052697 platinum Inorganic materials 0.000 abstract description 4
- 229910052878 cordierite Inorganic materials 0.000 abstract description 3
- 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 abstract description 3
- 230000003647 oxidation Effects 0.000 abstract description 3
- 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 abstract description 2
- 229910052863 mullite Inorganic materials 0.000 abstract description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 18
- 239000000843 powder Substances 0.000 description 18
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 12
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 12
- 239000002245 particle Substances 0.000 description 11
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 10
- 239000000446 fuel Substances 0.000 description 10
- 239000002002 slurry Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 7
- 229910052717 sulfur Inorganic materials 0.000 description 7
- 239000011593 sulfur Substances 0.000 description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 239000010948 rhodium Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 229930195733 hydrocarbon Natural products 0.000 description 5
- 150000002430 hydrocarbons Chemical class 0.000 description 5
- 229910052763 palladium Inorganic materials 0.000 description 5
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 5
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 4
- 229910002090 carbon oxide Inorganic materials 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical class [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 3
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical group [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 2
- OZECDDHOAMNMQI-UHFFFAOYSA-H cerium(3+);trisulfate Chemical compound [Ce+3].[Ce+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O OZECDDHOAMNMQI-UHFFFAOYSA-H 0.000 description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 2
- 229910000480 nickel oxide Inorganic materials 0.000 description 2
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 2
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- NRUVOKMCGYWODZ-UHFFFAOYSA-N sulfanylidenepalladium Chemical compound [Pd]=S NRUVOKMCGYWODZ-UHFFFAOYSA-N 0.000 description 2
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910021130 PdO2 Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 150000001785 cerium compounds Chemical class 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000003426 co-catalyst Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910017464 nitrogen compound Inorganic materials 0.000 description 1
- 150000002830 nitrogen compounds Chemical class 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- SONJTKJMTWTJCT-UHFFFAOYSA-K rhodium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Rh+3] SONJTKJMTWTJCT-UHFFFAOYSA-K 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000019086 sulfide ion homeostasis Effects 0.000 description 1
- 125000004434 sulfur atom Chemical group 0.000 description 1
- 229910052815 sulfur oxide Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、自動車エンジンなどから排出される排気ガス
を浄化する排気ガス浄化用触媒に関し、詳しくは硫化水
素の排出を防止できる排気ガス浄化用触媒に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust gas purification catalyst that purifies exhaust gas emitted from automobile engines, etc., and more specifically, to an exhaust gas purification catalyst that can prevent the emission of hydrogen sulfide. Regarding catalysts.
［従来の技術］
排気ガス浄化用触媒としては、従来一般に、担体基材表
面に活性アルミナからなる触媒担持層を形成しへその触
媒担持層に白金、ロジウム、パラジウムなどの触媒金属
を担持させたものが知られている。この排気ガス浄化用
触媒は、排気ガス中に含まれる炭化水素（ＨＣ）および
−酸化炭素（Ｃｏ）を酸化して浄化し、窒素化合物（Ｎ
Ｏｘ）を還元することにより浄化している。[Prior art] Conventionally, as a catalyst for exhaust gas purification, a catalyst support layer made of activated alumina is formed on the surface of a carrier base material, and a catalyst metal such as platinum, rhodium, palladium, etc. is supported on the navel catalyst support layer. something is known. This exhaust gas purification catalyst oxidizes and purifies hydrocarbons (HC) and -carbon oxides (Co) contained in exhaust gas, and converts nitrogen compounds (N
It is purified by reducing Ox).
ところで硫黄を含む燃料を用いた場合、排気ガス中には
亜硫酸ガス（３０２）が含まれている。By the way, when fuel containing sulfur is used, the exhaust gas contains sulfur dioxide gas (302).
この亜硫酸ガスは触媒担持層に吸着され蓄積される。し
かしながら、ある条件下では触媒表面で還元反応が生じ
、触媒からの排出ガス中に悪臭を発する硫化水素ガスが
含まれる場合があった。例えばエンジンの高負荷時にお
いては、触媒の過熱を防止するために、２次空気の導入
停止あるいは燃料増量などの制御が行なわれる。この際
、触媒コンバータ内の排気ガスの空燃比（Ａ／Ｆ）が燃
料（Ｆ）が過剰のリッチ雰囲気となり、担持層に吸着し
ていた亜硫酸ガスは還元されて硫化水素となる反応が生
じることが知られている。この反応は触媒床温度が６０
０ ’Ｃ以上の高温の場合に生じやすく、燃料中の硫黄
の含有量が多い場合などの悪条件が重なると、悪臭を発
する排出ガスが排出される場合がある。This sulfur dioxide gas is adsorbed and accumulated on the catalyst support layer. However, under certain conditions, a reduction reaction occurs on the surface of the catalyst, and the exhaust gas from the catalyst may contain hydrogen sulfide gas that gives off a bad odor. For example, when the engine is under high load, controls such as stopping the introduction of secondary air or increasing the amount of fuel are performed in order to prevent the catalyst from overheating. At this time, the air-fuel ratio (A/F) of the exhaust gas in the catalytic converter becomes a rich atmosphere with excess fuel (F), and the sulfur dioxide gas adsorbed on the support layer is reduced and a reaction occurs to form hydrogen sulfide. It has been known. This reaction is carried out at a catalyst bed temperature of 60
This tends to occur at high temperatures of 0'C or higher, and when adverse conditions such as high sulfur content in the fuel are combined, foul-smelling exhaust gas may be emitted.
この硫化水素の排出を防止するために、実開昭５４−３
１２１０号公報には、排気ガス流路の触媒の下流側に、
硫化水素酸化用触媒装置を設けた異臭の処理装置が開示
されている。In order to prevent the emission of hydrogen sulfide,
No. 1210 discloses that on the downstream side of the catalyst in the exhaust gas flow path,
Disclosed is an off-odor treatment device equipped with a catalyst device for hydrogen sulfide oxidation.
［発明が解決しようとする課題］
排気ガス浄化用触媒と別に硫化水素酸化用触媒を設ける
ことは、コストおよび重量の増大を招くので好ましくな
い。本発明は排気ガス浄化用触媒自体で硫化水素ガスの
排出をも防止することを目的とするものである。[Problems to be Solved by the Invention] Providing a hydrogen sulfide oxidation catalyst separately from an exhaust gas purification catalyst is not preferable because it increases cost and weight. An object of the present invention is to also prevent the emission of hydrogen sulfide gas using the exhaust gas purifying catalyst itself.
［課題を解決するための手段］
従来の排気ガス浄化用触媒において、例えば特開昭６１
−１１１４７号、特開昭６０−５４７３０などの公報に
見られるように、触媒担持層に助触媒作用をもつ酸化セ
リウムなどの希土類酸化物を含有するものが知られてい
る。本発明者らは、鋭意研究の結果、酸化セリウムをも
たない触媒においてはリッチ雰囲気においても硫化水素
ガスの発生がほとんど生じないこと、および、特に酸化
セリウムをもつ排気ガス浄化用触媒において硫化水素ガ
スが発生しやすいことを見出した。そして硫化水素の発
生機構を解明するとともに、その発生の防止機構を発見
して本発明を完成したものである。[Means for solving the problem] In conventional exhaust gas purifying catalysts, for example,
As seen in publications such as No. 11147 and Japanese Patent Laid-Open No. 60-54730, it is known that the catalyst supporting layer contains a rare earth oxide such as cerium oxide which has a promoter effect. As a result of intensive research, the present inventors have found that hydrogen sulfide gas is hardly generated even in a rich atmosphere in a catalyst that does not contain cerium oxide, and that hydrogen sulfide gas is hardly generated even in a rich atmosphere in a catalyst that does not contain cerium oxide. It was found that gas was easily generated. The present invention was completed by elucidating the mechanism of hydrogen sulfide generation and discovering a mechanism for preventing its generation.
すなわち本発明の排気ガス浄化用触媒は、担体基材と、
担体基材の表面に形成され酸化セリウムおよび粒子状の
酸化パラジウムを含む触媒担持層と、触媒担持層に担持
された触媒金属と、からなることを特徴とする。That is, the exhaust gas purifying catalyst of the present invention comprises a carrier base material,
It is characterized by comprising a catalyst support layer formed on the surface of a carrier base material and containing cerium oxide and particulate palladium oxide, and a catalyst metal supported on the catalyst support layer.
担体基材としては、ハニカム形状のモノリス担体基材、
ペレット状担体基材、メタル担体基材など、従来公知の
ものをそのまま用いることができる。そのｖＪ質も、コ
ージェライト、ムライト、アルミナ、スピネルなどのセ
ラミックス、フェライト鋼などの耐熱性金属など、従来
と同様のものを利用できる。As the carrier base material, a honeycomb-shaped monolith carrier base material,
Conventionally known materials such as pellet carrier base materials and metal carrier base materials can be used as they are. The same VJ quality as conventional ones can be used, such as ceramics such as cordierite, mullite, alumina, and spinel, and heat-resistant metals such as ferritic steel.
触媒担持層は上記担体基材表面に形成されて触媒金属を
担持する機能を有し、従来と同様に活性アルミナ、ジル
コニア、酸化チタンなどから形成することができる。一
般にはγ−アルミナ、θ−アルミナなどが用いられる。The catalyst support layer is formed on the surface of the carrier base material and has the function of supporting a catalyst metal, and can be formed from activated alumina, zirconia, titanium oxide, etc. as in the conventional case. Generally, γ-alumina, θ-alumina, etc. are used.
本発明の最大の特徴は、触媒担持層に酸化セリウムと粒
子状の酸化パラジウムとを含むところにおる。酸化セリ
ウムは前述したように触媒金属の作用を援助し、例えば
−酸化炭素および炭化水素の酸化反応に寄与する。酸化
セリウムの表面積は大きい方が、すなわち粒子径は小さ
い方が好ましい。この酸化セリウムは、触媒担持層中の
アルミニウム原子のモル数を１００とした場合、セリウ
ム原子数が５〜３０モルとなる比率で存在するのが好ま
しい。酸化セリウムがこの範囲より少なくなると、助触
媒としての作用が低減して触媒性能が低下し、この範囲
より多くなると活性アルミナ成分が減少して触媒性能が
逆に低下するようになる。The greatest feature of the present invention is that the catalyst supporting layer contains cerium oxide and particulate palladium oxide. As mentioned above, cerium oxide assists the action of the catalytic metal and contributes, for example, to the oxidation reactions of carbon oxides and hydrocarbons. It is preferable that the surface area of cerium oxide is large, that is, the particle size is small. This cerium oxide is preferably present in such a ratio that the number of cerium atoms is 5 to 30 moles when the number of moles of aluminum atoms in the catalyst support layer is 100. If the amount of cerium oxide is less than this range, the action as a co-catalyst will be reduced and the catalytic performance will be lowered, and if it is more than this range, the active alumina component will be reduced and the catalytic performance will be deteriorated.
酸化パラジウムは後述するように硫黄原子を捕捉する機
能を有し、硫化水素の排出を防止する。Palladium oxide has a function of capturing sulfur atoms, as will be described later, and prevents the emission of hydrogen sulfide.
この酸化パラジウムの含有間は、触媒担持層中のアルミ
ニウム原子のモル数を１００とした場合、パラジウム原
子数が０．０５〜３モルとなる比率で存在づるのが好ま
しい。酸化パラジウムがこの範囲より少なくなると苛酷
な条件下で硫化水素が排出されるにうになり、この範囲
より多くなると活性アルミナ成分が減少して触媒性能が
逆に低下するようになる。The content of palladium oxide is preferably such that the number of palladium atoms is 0.05 to 3 moles when the number of moles of aluminum atoms in the catalyst support layer is 100. If palladium oxide is less than this range, hydrogen sulfide will be discharged under severe conditions, and if it is more than this range, the active alumina component will be reduced and the catalyst performance will be adversely affected.
また、酸化パラジウムの粒子径は、２〜５μｍの範囲が
好ましく、比表面積が５ｍ２／Ｃ１以上であることが望
ましい。粒子径および比表面積がこの範囲を超えると、
硫黄の捕捉量が減少するため硫化水素が排出されやすく
なる。また、この範囲より粒子径が小さくなると、パラ
ジウムとロジウムが反応して、ロジウムの表面を被って
触媒活性が低下するため好ましくない。この酸化パラジ
ウムは、ＰｄＯ，ＰｄＯ２、Ｐｄ２０３など各種価数の
酸化パラジウムの混合物として存在しているものと推察
される。Further, the particle size of palladium oxide is preferably in the range of 2 to 5 μm, and the specific surface area is desirably 5 m2/C1 or more. If the particle size and specific surface area exceed this range,
Because the amount of sulfur trapped decreases, hydrogen sulfide is more likely to be emitted. Furthermore, if the particle size is smaller than this range, palladium and rhodium will react and cover the surface of rhodium, resulting in a decrease in catalytic activity, which is not preferable. It is presumed that this palladium oxide exists as a mixture of palladium oxides of various valences, such as PdO, PdO2, and Pd203.
触媒金属としては、白金、ロジウム、パラジウムが代表
的であり、このうちの少なくとも一種を用いるのがよい
。その他、イリジウム、ルテニウム、オスミウムなどの
貴金属、あるいはクロム、ニッケル、バナジウム、銅、
コバルト、マンガンなどの卑金属を添加することもでき
る。この触媒金属は、上記触媒担持層に担持されている
。その担持量は目的とする性能、コストなどの条件によ
り、従来と同様に種々選択することができる。Typical examples of the catalytic metal include platinum, rhodium, and palladium, and it is preferable to use at least one of these. Other precious metals such as iridium, ruthenium, osmium, chromium, nickel, vanadium, copper,
Base metals such as cobalt and manganese can also be added. This catalyst metal is supported on the catalyst support layer. The supported amount can be variously selected depending on the desired performance, cost, and other conditions, as in the past.
次に、本発明の排気ガス浄化用触媒の製造方法を説明す
る。まず、担体基材を用意し、活性アルミナなどに酸化
パラジウム粉末が含有されたスラリーを担体基材表面に
ウオツシュコ−１・する。そして所定温度で焼成して触
媒担持層を形成する。Next, a method for manufacturing the exhaust gas purifying catalyst of the present invention will be explained. First, a carrier base material is prepared, and a slurry containing palladium oxide powder in activated alumina or the like is washed onto the surface of the carrier base material. Then, it is fired at a predetermined temperature to form a catalyst support layer.
なお、スラリー中に酸化パラジウム粉末の代りに金属パ
ラジウム粉末を含有することもできる。この場合、金属
パラジウム粉末は焼成により酸化パラジウム粉末となる
。Note that metal palladium powder can also be contained in the slurry instead of palladium oxide powder. In this case, the metal palladium powder becomes palladium oxide powder by firing.
次に硝酸セリウムなどのセリウム原子を含む溶液を上記
触媒担持層に含浸させ、次いで所定温度で焼成する。こ
れにより酸化セリウムが触媒担持層中に含有される。な
お、スラリー中に酸化セリウム粉末を含有させることも
できるが、その場合は酸化セリウムの粒子径は比較的大
きなものとなる。このように溶液状のセリウム化合物を
含浸して焼成することにより、特に微細で表面積の大き
な酸化セリウムとなるため、酸化セリウムの助触媒作用
を最大に引き出すことができる。Next, the catalyst support layer is impregnated with a solution containing cerium atoms such as cerium nitrate, and then fired at a predetermined temperature. As a result, cerium oxide is contained in the catalyst support layer. Note that cerium oxide powder can also be included in the slurry, but in that case, the particle size of the cerium oxide will be relatively large. By impregnating and firing the solution-like cerium compound in this manner, cerium oxide is produced which is particularly fine and has a large surface area, so that the promoter effect of cerium oxide can be maximized.
そして触媒金属を含む溶液を、酸化セリウムおよび酸化
パラジウムをもつ触媒担持層に含浸し、所定温度で焼成
することにより、触媒金属を担持させ、本発明の排気ガ
ス浄化用触媒が製造される。Then, a catalyst support layer containing cerium oxide and palladium oxide is impregnated with a solution containing a catalyst metal and fired at a predetermined temperature to support the catalyst metal, thereby producing the exhaust gas purifying catalyst of the present invention.
［作用］
本発明の排気ガス浄化用触媒では、空燃比が大きなリー
ン雰囲気で（１）式の反応が生じる。[Operation] In the exhaust gas purifying catalyst of the present invention, the reaction of formula (1) occurs in a lean atmosphere with a large air-fuel ratio.
Ａｌ２ ０ ３ ＋ＣｅＯ２＋５ＳＯ２＋５／２ ０
２−＋ＡＩｚ （Ｓｏ ４ ） ３ ＋Ｃｅ（ＳＯ４）
２ （１）すなわち、亜硫酸ガスがアルミナおよび
酸化セリウムと反応し、硫酸アルミニウムおよびＶｔ酸
セリウムが生成して、亜硫酸ガスは触媒担持層に吸着、
蓄積される。Al2 0 3 +CeO2+5SO2+5/2 0
2-+AIz (So 4 ) 3 +Ce(SO4)
2 (1) That is, sulfur dioxide gas reacts with alumina and cerium oxide, aluminum sulfate and cerium Vt acid are produced, and sulfur dioxide gas is adsorbed on the catalyst support layer.
Accumulated.
次に、空燃比が小さなリッチ雰囲気では（２）式の還元
反応が生じる。Next, in a rich atmosphere with a small air-fuel ratio, the reduction reaction of equation (2) occurs.
Ａｌ ２ （ＳＯ４） ３ ＋Ｃｅ（ＳＯ＋ ） ２
＋１５Ｈ２＋５Ｐｄ−＋５ＰｄＳ＋Ａｌ ２ ０
３ ＋ＣｅＯ２＋１５Ｈ２０（２＞ここで、硫酸アル
ミニウムは硫黄酸化物が還元されて硫化水素となる温度
よりかなり低温で分解し、二酸化硫黄または三酸化硫黄
として排出されるため、硫酸アルミニウムからは硫化水
素は排出されない。一方、硫酸セリウムの分解温度は硫
酸アルミニウムの分解温度より高く、硫黄酸化物が還元
される温度と近似し、従来は硫酸セリウムの分解により
硫化水素が生成していた。しかし本発明では、酸化パラ
ジウムの存在により硫黄が捕捉されて硫化パラジウムが
生成する。これにより硫化水素の排出が防止されている
。Al 2 (SO4) 3 +Ce(SO+) 2
+15H2+5Pd-+5PdS+Al20
3 +CeO2+15H20 (2>Here, aluminum sulfate decomposes at a much lower temperature than the temperature at which sulfur oxide is reduced to hydrogen sulfide and is emitted as sulfur dioxide or sulfur trioxide, so hydrogen sulfide is not emitted from aluminum sulfate. On the other hand, the decomposition temperature of cerium sulfate is higher than that of aluminum sulfate, and is close to the temperature at which sulfur oxides are reduced. Conventionally, hydrogen sulfide was produced by decomposing cerium sulfate. However, in the present invention, The presence of palladium oxide traps sulfur and forms palladium sulfide, which prevents the emission of hydrogen sulfide.
そして再びリーン雰囲気となることにより、硫化パラジ
ウムは酸化され、硫黄は硫黄酸化物として排出されると
ともに、パラジウムは酸化パラジウムとなって再び硫黄
の捕捉に貢献する。また、触媒金属は従来と同様に炭化
水素、−酸化炭素および窒素酸化物を浄化する。Then, by becoming a lean atmosphere again, palladium sulfide is oxidized, sulfur is discharged as sulfur oxide, and palladium becomes palladium oxide and again contributes to trapping sulfur. In addition, the catalytic metal purifies hydrocarbons, carbon oxides and nitrogen oxides in the same manner as in the prior art.
［発明の効果］
すなわち本発明の排気ガス浄化用触媒によれば、硫化水
素の排出が防止される。また、従来のように別に硫化水
素酸化用触媒を設ける必要がないので、重量の増大およ
びコストの上昇を防止することができる。[Effects of the Invention] That is, according to the exhaust gas purifying catalyst of the present invention, the emission of hydrogen sulfide is prevented. Further, since there is no need to separately provide a catalyst for oxidizing hydrogen sulfide as in the conventional case, an increase in weight and cost can be prevented.
［実施例］ 以下、実施例により具体的に説明する。[Example] Hereinafter, this will be explained in detail using examples.
（実施例１）
（１）酸化パラジウム粉末の調製
硝酸パラジウム（Ｐｄ（Ｎｏ ３ ） ２ ’）粉末を
電気炉中１０００’Ｃで２０時間焼成後、粉砕して平均
粒子径５μｍの酸化パラジウム粉末を調製した。(Example 1) (1) Preparation of palladium oxide powder Palladium nitrate (Pd(No 3 ) 2 ') powder was fired at 1000'C in an electric furnace for 20 hours and then ground to produce palladium oxide powder with an average particle size of 5 μm. Prepared.
（２〉スラリーの調製
次にγ−アルミナ粉末を４０重間％含有するスラリー１
２０重量部中に、上記酸化パラジウム粉末を６．１２重
患部混合してスラリーを調製した。(2> Preparation of slurry Next, slurry 1 containing 40% by weight of γ-alumina powder
A slurry was prepared by mixing 6.12 parts of the above palladium oxide powder into 20 parts by weight of the affected area.
二のとき、酸化パラジウム粉末の配合量は、アルミニウ
ム原子１００モルに対してパラジウム原子５モルである
。In case 2, the amount of palladium oxide powder blended is 5 moles of palladium atoms per 100 moles of aluminum atoms.
（３）触媒担持層の形成
市販のコージェライト質モノリス担体基材を用意し、上
記スラリー中に浸漬した後余分なスラリーを吹き飛ばし
て、１００℃で１時間乾燥後７００℃で２時間焼成した
。次に全体を硝酸セリウム（Ｃｅ（ＮＯ３） ２ ）の
１３重量％水溶液に浸漬し、引き出して１００℃で１時
間乾燥後、７００℃で１時間焼成した。これにより硝酸
セリウムは酸化セリウムとなり、微粒子状の酸化セリウ
ムと平均粒子径５μｍの酸化パラジウム粉末を含有する
触媒担持層が形成された。(3) Formation of catalyst support layer A commercially available cordierite monolith carrier base material was prepared, immersed in the above slurry, excess slurry was blown off, dried at 100°C for 1 hour, and then calcined at 700°C for 2 hours. Next, the whole was immersed in a 13% by weight aqueous solution of cerium nitrate (Ce(NO3) 2 ), pulled out, dried at 100°C for 1 hour, and then fired at 700°C for 1 hour. As a result, cerium nitrate turned into cerium oxide, and a catalyst support layer containing fine particulate cerium oxide and palladium oxide powder having an average particle diameter of 5 μm was formed.
（４）触媒金属の担持
次に、ジニトロジアンミン白金水溶液に全体を１時間浸
漬し、引き上げて余分な水滴を吹き飛ばした後、１２０
℃で２時間乾燥して白金を担持させた。さらに、塩化ロ
ジウム水溶液に同様に１時間浸漬し、同様に乾燥してロ
ジウムを担持させた。(4) Supporting catalytic metal Next, the entire body was immersed in a dinitrodiammine platinum aqueous solution for 1 hour, pulled out, and excess water droplets were blown off.
It was dried at ℃ for 2 hours to support platinum. Furthermore, it was similarly immersed in an aqueous rhodium chloride solution for 1 hour and dried in the same manner to support rhodium.
この際の担持量はＰｔ＝１．５１１］／父、Ｒｈ＝０．
３（Ｉｔ／父である。The supported amount at this time was Pt=1.511]/father, Rh=0.
3 (It/It is my father.
得られた排気ガス浄化用触媒の各元素の量を、触媒１Ｑ
当たりに換算して第１表に示す。The amount of each element in the obtained exhaust gas purification catalyst was determined as catalyst 1Q.
The winning numbers are shown in Table 1.
（５）試験
第１表
上記方法により形成された直径３０ｍｍ、長さ５Ｑｍｍ
のテスト用触媒を用い、硫黄を０．１重量％含有するモ
デルガソリンにて、空燃比（Ａ／Ｆ）＝１５．０のリー
ン雰囲気で排気ガスを１時間流通させた。その後、空燃
比＝１３．０のリッチ雰囲気で５分間流通させ、その時
の触媒からの排出ガス中の硫化水素濃度を測定した。ま
た、このテスト用触媒について空燃比＝１４．６の排気
ガスを触媒床温度９００ ’Ｃで１００時間流通させる
耐久試験を行ない、その後上記と同様に試験して耐久試
験後の排出ガス中の硫化水素濃度を測定した。それぞれ
の結果を第２表に示す。(5) Test Table 1 Diameter 30mm, length 5Qmm formed by the above method
Using the test catalyst, exhaust gas was allowed to flow for 1 hour in a lean atmosphere with an air-fuel ratio (A/F) of 15.0 using model gasoline containing 0.1% by weight of sulfur. Thereafter, the catalyst was allowed to flow for 5 minutes in a rich atmosphere with an air-fuel ratio of 13.0, and the hydrogen sulfide concentration in the exhaust gas from the catalyst at that time was measured. In addition, a durability test was conducted for this test catalyst in which exhaust gas with an air-fuel ratio of 14.6 was passed through the catalyst bed at a temperature of 900'C for 100 hours, and then the test was conducted in the same manner as above. Hydrogen concentration was measured. The results are shown in Table 2.
また、上記方法により形成された１、７９のフルサイズ
触媒を用い、３Ｑエンジンの排気系に袋筒２表
看して初期の炭化水素、−酸化炭素および窒素酸化物の
浄化率を測定した。また、回転数５００Ｏｒｐｍ、触媒
床温度９００’Ｃ（７）条（’ｔテ１００時間運転する
耐久試験を行ない、耐久試験後の浄化率を同様に測定し
た。それぞれの結果を第３表に示す。なお、浄化率の測
定条件は、２００Ｏｒｐｍ、−３６０ｍｆｆｌｌ−１ｇ
、３００ ’Ｃでめる。Further, using a full size catalyst No. 1,79 formed by the above method, two bag cylinders were placed in the exhaust system of a 3Q engine to measure the initial purification rate of hydrocarbons, carbon oxides and nitrogen oxides. In addition, a durability test was conducted in which the rotation speed was 500 rpm and the catalyst bed temperature was 900°C (7) for 100 hours, and the purification rate after the durability test was measured in the same manner.The results are shown in Table 3. The measurement conditions for the purification rate are 200Orpm, -360mffll-1g
, 300'C.
（実施例２）
塩化パラジウム（ＰｄＣＩ２）粉末を用い、実施例１と
同様に焼成、粉砕して平均粒子径５μｍの酸化パラジウ
ム粉末を調製した。この酸化パラジウム粉末を用いて、
実施例１と同様に排気ガス浄化用触媒を製造し、同様に
硫化水素濃度と浄化率を測定して、結果を第１表〜第３
表に示す。(Example 2) Using palladium chloride (PdCI2) powder, it was fired and pulverized in the same manner as in Example 1 to prepare palladium oxide powder with an average particle size of 5 μm. Using this palladium oxide powder,
An exhaust gas purification catalyst was manufactured in the same manner as in Example 1, and the hydrogen sulfide concentration and purification rate were similarly measured, and the results are shown in Tables 1 to 3.
Shown in the table.
（実施例３）
実施例１における酸化パラジウム粉末の調製の焼成時に
、水素ガスを流しながら焼成した。そして同様に粉砕し
て、平均粒子径５μｍの金属パラジウム粉末を得た。こ
の金属パラジウム粉末を用いたこと以外は実施例１と同
様にして実施例３の排気ガス浄化用触媒を調製した。な
お、金属パラジウム粉末は触媒担持層形成工程にあける
焼成時に酸化され、平均粒子径５μｍの酸化パラジウム
粉末となった。(Example 3) At the time of baking in the preparation of palladium oxide powder in Example 1, baking was performed while flowing hydrogen gas. Then, it was similarly pulverized to obtain metal palladium powder with an average particle size of 5 μm. An exhaust gas purifying catalyst of Example 3 was prepared in the same manner as Example 1 except that this metal palladium powder was used. Note that the metal palladium powder was oxidized during firing in the catalyst support layer forming step, and became palladium oxide powder with an average particle size of 5 μm.
得られた排気ガス浄化用触媒について、実施例１と同様
に硫化水素濃度と浄化率を測定して、結果を第１表〜第
３表に示す。Regarding the obtained exhaust gas purification catalyst, the hydrogen sulfide concentration and purification rate were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 3.
（比較例１）
実施例１で酸化パラジウム粉末を添加する代わりに、平
均粒子径５μｍの酸化ニッケル（ＮｉＯ）粉末を添加し
たこと以外は実施例１と同様にして、比較例１の排気ガ
ス浄化用触媒を製造した。得られた排気ガス浄化用触媒
について、実施例１と同様に硫化水素濃度と浄化率を測
定して、結果を第１表〜第３表に示す。(Comparative Example 1) Exhaust gas purification in Comparative Example 1 was carried out in the same manner as in Example 1 except that nickel oxide (NiO) powder with an average particle size of 5 μm was added instead of palladium oxide powder in Example 1. A catalyst was produced for Regarding the obtained exhaust gas purification catalyst, the hydrogen sulfide concentration and purification rate were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 3.
（比較例２）
実施例１と同様の担体基材に、γ−アルミナのみを含有
するスラリーを付着させて触媒担持層を形成した。そし
て実施例１と同様に、硝酸セリウム水溶液を含浸させた
後焼成して酸化セリウムを含有させ、同様に触媒金属を
担持させて比較例２の排気ガス浄化用触媒を製造した。(Comparative Example 2) A catalyst support layer was formed by adhering a slurry containing only γ-alumina to the same carrier base material as in Example 1. Then, in the same manner as in Example 1, an exhaust gas purifying catalyst of Comparative Example 2 was manufactured by impregnating with an aqueous cerium nitrate solution and then calcining to contain cerium oxide, and supporting a catalyst metal in the same manner.
すなわち酸化パラジウムは含有していない。得られた排
気ガス浄化用触媒について、実施例１と同様に硫化水素
濃度と浄化率を測定して、結果を第１表〜第３表にボす
。That is, it does not contain palladium oxide. Regarding the obtained exhaust gas purification catalyst, the hydrogen sulfide concentration and purification rate were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 3.
（比較例３）
比較例２と同様にγ−アルミナのみからなる触媒担持層
を形成し、硝酸パラジウム水溶液を含浸した後引き出し
て３００℃で１時間焼成した。そして実施例１と同様に
、硝酸セリウム水溶液を含浸させた後７００℃で焼成し
て酸化セリウムを含有させ、同様に触媒金属を担持させ
て比較例２の排気ガス浄化用触媒を製造した。この場合
、□パラジウムは硝酸塩として含有されており、酸化パ
ラジウムとはなっていない。得られた排気ガス浄化用触
媒について、実施例１と同様に硫化水素濃度と浄化率を
測定して、結果を第１表〜第３表に示す。(Comparative Example 3) A catalyst support layer made only of γ-alumina was formed in the same manner as in Comparative Example 2, impregnated with an aqueous palladium nitrate solution, then pulled out and calcined at 300° C. for 1 hour. Then, in the same manner as in Example 1, an exhaust gas purifying catalyst of Comparative Example 2 was manufactured by impregnating it with an aqueous cerium nitrate solution and then calcining it at 700° C. to contain cerium oxide, and similarly supporting a catalyst metal. In this case, □palladium is contained as a nitrate and not palladium oxide. Regarding the obtained exhaust gas purification catalyst, the hydrogen sulfide concentration and purification rate were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 3.
（評価）
第２表より、本発明の排気ガス浄化用触媒では、初期お
よび耐久試験後において硫化水素の排出が防止されてい
ることが明らかである。また、第３表より明らかなよう
に、比較例の触媒と同等以上の優れた浄化性能を示して
いる。(Evaluation) From Table 2, it is clear that the exhaust gas purifying catalyst of the present invention prevents the emission of hydrogen sulfide both at the initial stage and after the durability test. Furthermore, as is clear from Table 3, the catalyst exhibited excellent purification performance equivalent to or better than that of the catalyst of the comparative example.
Claims (1)
リウムおよび粒子状の酸化パラジウムを含む触媒担持層
と、該触媒担持層に担持された触媒金属と、からなるこ
とを特徴とする排気ガス浄化用触媒。(1) It consists of a carrier base material, a catalyst support layer formed on the surface of the carrier base material and containing cerium oxide and particulate palladium oxide, and a catalyst metal supported on the catalyst support layer. Exhaust gas purification catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1009394A JPH02191548A (en) | 1989-01-18 | 1989-01-18 | Catalyst for purification of exhaust gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1009394A JPH02191548A (en) | 1989-01-18 | 1989-01-18 | Catalyst for purification of exhaust gas |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02191548A true JPH02191548A (en) | 1990-07-27 |
Family
ID=11719212
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1009394A Pending JPH02191548A (en) | 1989-01-18 | 1989-01-18 | Catalyst for purification of exhaust gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02191548A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5702675A (en) * | 1994-12-16 | 1997-12-30 | Toyota Jidosha Kabushiki Kaisha | Catalyst for purifying exhaust gases and process for producing the same |
| US5968462A (en) * | 1994-02-04 | 1999-10-19 | Toyota Jidosha Kabushiki Kaisha | Process for purifying exhaust gases |
| JP2009082880A (en) * | 2007-10-02 | 2009-04-23 | Mazda Motor Corp | Exhaust gas cleaning catalyst apparatus |
| JP2013208577A (en) * | 2012-03-30 | 2013-10-10 | Mitsui Mining & Smelting Co Ltd | Palladium catalyst |
-
1989
- 1989-01-18 JP JP1009394A patent/JPH02191548A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5968462A (en) * | 1994-02-04 | 1999-10-19 | Toyota Jidosha Kabushiki Kaisha | Process for purifying exhaust gases |
| US5702675A (en) * | 1994-12-16 | 1997-12-30 | Toyota Jidosha Kabushiki Kaisha | Catalyst for purifying exhaust gases and process for producing the same |
| JP2009082880A (en) * | 2007-10-02 | 2009-04-23 | Mazda Motor Corp | Exhaust gas cleaning catalyst apparatus |
| JP2013208577A (en) * | 2012-03-30 | 2013-10-10 | Mitsui Mining & Smelting Co Ltd | Palladium catalyst |
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