JP3441267B2 - Catalyst production method - Google Patents
Catalyst production methodInfo
- Publication number
- JP3441267B2 JP3441267B2 JP26327295A JP26327295A JP3441267B2 JP 3441267 B2 JP3441267 B2 JP 3441267B2 JP 26327295 A JP26327295 A JP 26327295A JP 26327295 A JP26327295 A JP 26327295A JP 3441267 B2 JP3441267 B2 JP 3441267B2
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- particle size
- carrier
- atmosphere
- metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000003054 catalyst Substances 0.000 title claims description 55
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000002245 particle Substances 0.000 claims description 57
- 230000001590 oxidative effect Effects 0.000 claims description 43
- 229910052751 metal Inorganic materials 0.000 claims description 30
- 239000002184 metal Substances 0.000 claims description 30
- 238000009826 distribution Methods 0.000 claims description 20
- 230000003197 catalytic effect Effects 0.000 claims description 15
- 229910052763 palladium Inorganic materials 0.000 claims description 4
- 229910052741 iridium Inorganic materials 0.000 claims description 3
- 229910052707 ruthenium Inorganic materials 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 47
- 239000007789 gas Substances 0.000 description 33
- 229910000510 noble metal Inorganic materials 0.000 description 26
- 238000000034 method Methods 0.000 description 21
- 239000010948 rhodium Substances 0.000 description 14
- 239000002923 metal particle Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 229910052697 platinum Inorganic materials 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 238000004220 aggregation Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 230000003993 interaction Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 239000012266 salt solution Substances 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052703 rhodium Inorganic materials 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 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 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 239000010944 silver (metal) Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 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 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 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 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Landscapes
- Catalysts (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、内燃機関などから
排出される排ガスを浄化する排ガス浄化用触媒などの触
媒の製造方法に関し、詳しくは担持されている触媒金属
の粒径を容易に制御できる触媒の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a catalyst such as an exhaust gas purifying catalyst for purifying exhaust gas discharged from an internal combustion engine or the like, and more specifically, it is possible to easily control the particle size of a carried catalytic metal. The present invention relates to a method for producing a catalyst.
【０００２】[0002]
【従来の技術】白金（Ｐｔ）やロジウム（Ｒｈ）あるい
はパラジウム（Ｐｄ）などの貴金属は、その高い触媒活
性から排気ガスの浄化などに広く利用されている。ただ
これらの貴金属は高価であるので、触媒として利用する
にはできるだけ少量でできるだけ大きな活性を得るよう
にすることが望ましく、アルミナなどの多孔質担体に高
分散状態で担持されて用いられている。2. Description of the Related Art Noble metals such as platinum (Pt), rhodium (Rh) and palladium (Pd) are widely used for purification of exhaust gas due to their high catalytic activity. However, since these noble metals are expensive, it is desirable to obtain as large an activity as possible in a small amount for use as a catalyst, and they are used in a highly dispersed state on a porous carrier such as alumina.
【０００３】また、貴金属をこのように高分散状態で担
持するには、貴金属の塩の水溶液を担体に含浸させて乾
燥・焼成する含浸担持法、貴金属の塩の水溶液中に担体
を浸漬して貴金属を含むイオンを吸着させ、その後引き
上げて乾燥・焼成する選択担持法などが知られている。
このように高分散状態で担持された貴金属の粒径はきわ
めて微細となり、排気ガスなどの被処理物との接触面積
が大きくなるため、少量の担持量で高い活性が得られ
る。しかしながら、貴金属の粒径があまりに微細過ぎる
と使用温度や使用雰囲気などにより貴金属粒子に凝集が
生じたりする現象も見られ、貴金属の粒子径には使用目
的あるいは使用条件に応じた最適粒径が存在することが
わかってきた。In order to support the noble metal in such a highly dispersed state, an impregnation-supporting method in which the carrier is impregnated with an aqueous solution of a salt of the noble metal and dried and fired, and the carrier is immersed in the aqueous solution of the salt of the noble metal. A selective supporting method is known in which ions containing a noble metal are adsorbed, and then pulled up and dried / baked.
In this way, the particle diameter of the noble metal supported in a highly dispersed state becomes extremely fine, and the contact area with an object to be treated such as exhaust gas becomes large, so that high activity can be obtained with a small amount of supported metal. However, if the particle size of the noble metal is too small, there is a phenomenon that the noble metal particles agglomerate due to the operating temperature and atmosphere, and there is an optimum particle size for the noble metal depending on the purpose of use or the operating conditions. I've come to understand.
【０００４】したがって、上記の方法で高分散で担持さ
れた貴金属粒子は微細であり、その粒径の制御が困難で
あるため、その使用目的あるいは使用条件は特定のもの
に制限されざるを得ない。そこで特開平７−８８０７号
公報には、貴金属塩溶液中に水素化ホウ素ナトリウムや
エタノールなどの還元剤を添加し、貴金属イオンを還元
して担体上に吸着させる方法が開示されている。この方
法によれば、担持された貴金属粒子の粒径は比較的大き
くなり、貴金属塩や還元剤の種類などを適切に選択する
ことにより粒径を制御することが可能となる。Therefore, the noble metal particles carried in a highly dispersed state by the above method are fine and it is difficult to control the particle size, so that the purpose of use or the conditions of use must be limited to a specific one. . Therefore, Japanese Patent Application Laid-Open No. 7-8807 discloses a method of adding a reducing agent such as sodium borohydride or ethanol to a noble metal salt solution to reduce the noble metal ion and adsorb it on a carrier. According to this method, the particle size of the supported noble metal particles becomes relatively large, and the particle size can be controlled by appropriately selecting the kind of the noble metal salt or the reducing agent.
【０００５】また、貴金属が担持された担体を大気中や
窒素ガス中で高温焼成する方法も知られている。この方
法は、一旦担持された貴金属粒子の粒径を変化させるこ
とで粒径を制御しようとするものである。A method is also known in which a carrier carrying a noble metal is baked at a high temperature in the atmosphere or nitrogen gas. This method is intended to control the particle size by changing the particle size of the noble metal particles once carried.
【０００６】[0006]
【発明が解決しようとする課題】ところが、貴金属塩溶
液中に還元剤を添加する方法では、貴金属が溶液中で還
元された後に担持されるため、貴金属と担体との相互作
用が小さく貴金属粒子が移動しやすくなり、貴金属粒子
が凝集しやすいという不具合がある。なお、貴金属塩と
還元剤との種類の組合せを適切に選択することにより貴
金属粒子の凝集を多少改善できるが、その効果は十分と
はいえなかった。However, in the method of adding a reducing agent to a noble metal salt solution, since the noble metal is supported after being reduced in the solution, the interaction between the noble metal and the carrier is small and noble metal particles are formed. There is a problem that it becomes easy to move and the precious metal particles tend to aggregate. The aggregation of the noble metal particles can be somewhat improved by appropriately selecting the combination of the types of the noble metal salt and the reducing agent, but the effect was not sufficient.
【０００７】また貴金属が担持された担体を大気中で焼
成すると、貴金属の平均粒径は大きくなるものの粒径分
布はきわめて広くなり、微細なものから巨大粒子まで含
まれることとなる。したがって、実際の使用条件では活
性が低い粒径の粒子も含まれることとなり、高価な貴金
属の有効利用を図ることが困難である。一方、貴金属が
担持された担体を窒素ガス雰囲気中で焼成する方法によ
れば、粒径分布を狭くすることができる。しかし大きな
粒径とするためには極めて長時間の焼成が必要となり、
工数面及び省エネルギー面から好ましくない。When the carrier carrying the noble metal is fired in the atmosphere, the average particle size of the noble metal increases, but the particle size distribution becomes extremely wide, and fine particles to large particles are contained. Therefore, under actual use conditions, particles having a low activity are included, and it is difficult to effectively use expensive precious metals. On the other hand, according to the method of firing the carrier supporting the noble metal in the nitrogen gas atmosphere, the particle size distribution can be narrowed. However, in order to obtain a large particle size, firing for an extremely long time is required,
It is not preferable in terms of man-hours and energy saving.
【０００８】本発明はこのような事情に鑑みてなされた
ものであり、担体に担持されている触媒金属粒子の粒径
を短時間で任意に制御可能とし、かつ触媒金属粒子の粒
径の分布を狭くすることを目的とする。The present invention has been made in view of such circumstances, and makes it possible to arbitrarily control the particle size of the catalytic metal particles carried on the carrier in a short time and to distribute the particle size of the catalytic metal particles. The purpose is to narrow.
【０００９】[0009]
【課題を解決するための手段】上記課題を解決する本発
明の触媒の製造方法は、多孔質担体よりなる触媒担体に
Ｐｔ，Ｒｈ，Ｐｄ，Ａｕ，Ａｇ，Ｉｒ及びＲｕから選ば
れる触媒金属を担持して触媒金属担持担体とする担持工
程と、酸化雰囲気と非酸化雰囲気が交互に繰り返される
ガス雰囲気中で触媒金属担持担体を繰り返し酸化及び非
酸化処理して、担持されている触媒金属の粒径を制御し
粒径分布を狭くする処理工程と、を有することを特徴と
する。A method for producing a catalyst according to the present invention which solves the above-mentioned problems is a catalyst carrier comprising a porous carrier.
Selected from Pt, Rh, Pd, Au, Ag, Ir and Ru
The supporting step of supporting the catalytic metal to be used as the catalytic metal supporting carrier and the oxidizing atmosphere and the non-oxidizing atmosphere are alternately repeated.
The catalyst metal-supported carrier is repeatedly oxidized and non-oxidized in a gas atmosphere to control the particle size of the supported catalyst metal.
And a treatment step for narrowing the particle size distribution .
【００１０】[0010]
【発明の実施の形態】触媒担体としては、アルミナ、シ
リカ、チタニア、ジルコニア、シリカ−アルミナ、ゼオ
ライトなどの多孔質担体を用いることができる。コージ
ェライトなどの耐熱性無機物や金属からハニカム形状あ
るいはペレット形状に形成された基材に上記多孔質担体
粉末のコート層を形成して触媒担体としてもよいし、多
孔質担体からハニカム形状あるいはペレット形状に形成
して触媒担体とすることもできる。BEST MODE FOR CARRYING OUT THE INVENTION As the catalyst carrier, a porous carrier such as alumina, silica, titania, zirconia, silica-alumina or zeolite can be used. A catalyst carrier may be formed by forming a coat layer of the above-mentioned porous carrier powder on a substrate formed in a honeycomb shape or a pellet shape from a heat-resistant inorganic substance such as cordierite or a metal, or a honeycomb shape or a pellet shape from the porous carrier. It can also be formed into a catalyst carrier.
【００１１】触媒金属としては、Ｐｔ、Ｒｈ、Ｐｄ、Ａ
ｕ、Ａｇ、Ｉｒ、Ｒｕなど、従来公知の金属から一種あ
るいは複数種類を用いることができる。担持工程では、
上記触媒担体に上記触媒金属が担持される。この担持方
法としては、従来公知の各種担持法を利用することがで
きるが、触媒金属が微細粒径で高分散に担持される方法
が望ましい。このような方法としては、触媒金属の塩の
溶液を触媒担体に含浸させて乾燥・焼成する含浸担持
法、触媒金属の塩の溶液中に触媒担体を浸漬して吸着さ
せその後引き上げて乾燥・焼成する選択担持法などがあ
る。As the catalytic metal, Pt, Rh, Pd, A
One or more kinds of conventionally known metals such as u, Ag, Ir and Ru can be used. In the carrying process,
The catalyst metal is supported on the catalyst carrier. As this supporting method, various conventionally known supporting methods can be used, but a method in which the catalyst metal is supported in a fine particle size with high dispersion is desirable. Examples of such a method include an impregnation-supporting method in which a catalyst metal salt solution is impregnated into a catalyst carrier and dried / calcined, and a catalyst carrier is immersed in a catalyst metal salt solution to be adsorbed and then pulled up and dried / calcined. There is a selective loading method to do so.
【００１２】担持工程で触媒金属が担持された金属担持
担体は、酸化雰囲気と非酸化雰囲気が交互に繰り返され
る雰囲気中で繰り返し酸化及び非酸化処理される。ここ
で酸化雰囲気とは酸素などの酸化性ガス成分による酸化
性の雰囲気をいい、非酸化雰囲気とは水素、炭化水素な
どの還元性ガス成分又は窒素ガスなどの不活性ガス成分
による非酸化性の雰囲気をいう。The metal-supported carrier on which the catalytic metal is supported in the supporting step is repeatedly oxidized and non-oxidized in an atmosphere in which an oxidizing atmosphere and a non-oxidizing atmosphere are alternately repeated. Here, the oxidizing atmosphere refers to an oxidizing atmosphere due to an oxidizing gas component such as oxygen, and the non-oxidizing atmosphere refers to a non-oxidizing atmosphere due to a reducing gas component such as hydrogen or hydrocarbon or an inert gas component such as nitrogen gas. Say the atmosphere.
【００１３】雰囲気中の酸化性ガス成分又は非酸化性ガ
ス成分の濃度は特に制限されないが、触媒金属の担持さ
れている当量以上の濃度であることが好ましく、触媒金
属の担持されている当量の２〜１０倍程度の当量を含む
濃度とすることが望ましい。各雰囲気中の酸化性ガス及
び非酸化性ガスの種類あるいは組成については、上記範
囲を満たせば特に制限されない。The concentration of the oxidizing gas component or the non-oxidizing gas component in the atmosphere is not particularly limited, but it is preferable that the concentration is equal to or higher than the equivalent weight of the catalyst metal supported, and the equivalent weight of the catalyst metal supported. It is desirable to set the concentration to include an equivalent of 2 to 10 times. The types or compositions of the oxidizing gas and the non-oxidizing gas in each atmosphere are not particularly limited as long as the above ranges are satisfied.
【００１４】この処理工程は一般に加熱下で行われる
が、その温度は触媒金属が酸化又は還元される温度以上
であれば特に制限されず、１００〜１２００℃の範囲が
適当である。１００℃未満では触媒金属に反応が生じず
粒径の制御が困難となり、１２００℃を超えると触媒担
体などの収縮が著しく触媒活性が損なわれる恐れがあ
る。特に好ましい５００〜１０００℃の範囲であれば、
触媒金属の反応速度が適切であるので短時間で所定の粒
径とすることができ、しかも触媒担体の収縮を低く抑制
できる。This treatment step is generally carried out under heating, but the temperature is not particularly limited as long as it is at or above the temperature at which the catalyst metal is oxidized or reduced, and a range of 100 to 1200 ° C. is suitable. If the temperature is lower than 100 ° C., no reaction occurs in the catalyst metal and it is difficult to control the particle size. In the particularly preferred range of 500 to 1000 ° C.,
Since the reaction rate of the catalyst metal is appropriate, the particle size can be reduced to a predetermined value in a short time, and the contraction of the catalyst carrier can be suppressed low.
【００１５】酸化・非酸化の変動周期は、酸化性ガス及
び非酸化性ガスの濃度条件と同様に、触媒金属の担持さ
れている当量以上の酸化性ガス又は非酸化性ガスが接触
すればよく、濃度によっても異なるが１秒〜１００分程
度とされる。変動周期が１秒より短いと酸化性ガスと非
酸化性ガスが混ざり合い、所定の酸化雰囲気又は非酸化
雰囲気とならなくなる恐れがある。また１００分より長
くなると、雰囲気変動の効果が小さくなり粒径制御が困
難となる。１分〜３０分が特に望ましい。また各雰囲気
における処理時間は、実用上その合計で１０分〜１０時
間とするのが望ましい。The fluctuation cycle of oxidation / non-oxidation may be the same as the concentration conditions of the oxidative gas and the non-oxidative gas, as long as the oxidative gas or the non-oxidative gas supported by the catalytic metal is equal to or more than the equivalent amount. Although it depends on the concentration, it is about 1 second to 100 minutes. If the fluctuation cycle is shorter than 1 second, the oxidizing gas and the non-oxidizing gas may be mixed with each other, and the predetermined oxidizing atmosphere or non-oxidizing atmosphere may not be obtained. On the other hand, if it is longer than 100 minutes, the effect of changing the atmosphere becomes small and it becomes difficult to control the particle size. 1 minute to 30 minutes is particularly desirable. In addition, the total treatment time in each atmosphere is preferably 10 minutes to 10 hours in total.
【００１６】なお、各雰囲気中の酸化性ガスと非酸化性
ガスの当量を同一とする必要はなく、また各雰囲気にお
ける処理時間を同一とする必要もなく、目的とする粒径
や条件に応じて種々選択して処理することができる。以
下、触媒金属としてＰｔを用いた場合について、本発明
の作用を説明する。担体上における触媒金属の凝集は、
触媒金属粒子どうしの衝突によって起こることが知られ
ている。またＰｔの場合は、非酸化雰囲気下よりも酸化
雰囲気下の方が凝集し易いことも知られている。これ
は、Ｐｔの酸化物の蒸気圧がＰｔ金属のそれよりも高い
ことから予想されるように、酸化雰囲気下では気相や担
体表面を伝ってＰｔの酸化物が移動し易くなるためであ
る。ただし担体上のすべてのＰｔ粒子が同じ速度で移動
するわけではなく、担体の状態は不均一であるから、担
持位置の違いによりＰｔと担体との相互作用が異なるな
どの原因で、移動しやすいＰｔと移動しにくいＰｔとが
存在する。したがって酸化雰囲気で長時間処理すると、
Ｐｔの粒径分布はきわめて広くなってしまう。Incidentally, it is not necessary to make the equivalent amounts of the oxidizing gas and the non-oxidizing gas in each atmosphere the same, and it is not necessary to make the processing time the same in each atmosphere, depending on the target particle size and conditions. Can be selected and processed. Hereinafter, the operation of the present invention will be described when Pt is used as the catalyst metal. Aggregation of the catalytic metal on the support is
It is known to occur due to the collision of catalytic metal particles. Further, in the case of Pt, it is also known that aggregation occurs more easily in an oxidizing atmosphere than in a non-oxidizing atmosphere. This is because, as expected because the vapor pressure of Pt oxide is higher than that of Pt metal, the Pt oxide easily moves along the gas phase or the surface of the carrier in an oxidizing atmosphere. . However, not all Pt particles on the carrier move at the same speed, and the condition of the carrier is non-uniform, so it is easy for them to move due to differences in the interaction between Pt and the carrier due to differences in the loading position. There are Pt and Pt that are difficult to move. Therefore, when treated for a long time in an oxidizing atmosphere,
The particle size distribution of Pt becomes extremely wide.
【００１７】一方、窒素ガスなどの非酸化性雰囲気で
は、Ｐｔは金属状態であるため担体との相互作用が小さ
く、Ｐｔ粒子それぞれの移動速度はほぼ同一となる。し
たがって触媒金属の粒径は比較的均一になる。ただしＰ
ｔ金属はＰｔ酸化物に比べて移動しにくいので、粒径の
成長速度はきわめて小さい。本発明では酸化−非酸化を
周期的に変動させているので、粒径が成長する酸化雰囲
気と担体との相互作用を弱める非酸化雰囲気が交互に存
在し、短時間で粒径分布の狭い粒径とすることができる
ものと考えられる。なお、Ｐｔの場合には、酸素濃度な
ど酸化雰囲気の反応性を変化させることによっても、任
意の平均粒径とすることができる。On the other hand, in a non-oxidizing atmosphere such as nitrogen gas, since Pt is in a metallic state, its interaction with the carrier is small, and the moving speed of each Pt particle is almost the same. Therefore, the particle size of the catalytic metal becomes relatively uniform. However, P
Since the t metal is less likely to move than the Pt oxide, the growth rate of the grain size is extremely small. In the present invention, since the oxidation-nonoxidation is periodically changed, the oxidizing atmosphere in which the particle size grows and the non-oxidizing atmosphere that weakens the interaction with the carrier are alternately present, and the particles having a narrow particle size distribution in a short time. It is considered that the diameter can be used. In the case of Pt, the average particle diameter can be set to an arbitrary value by changing the reactivity of the oxidizing atmosphere such as the oxygen concentration.
【００１８】その他の触媒金属についても同様であり、
酸化雰囲気と非酸化雰囲気とで凝集のしやすさが異なる
ため、酸化雰囲気と非酸化雰囲気を交互に変動させるこ
とで粒径を制御することができ、粒径分布も狭くするこ
とができる。The same applies to other catalyst metals,
Since the easiness of aggregation differs between the oxidizing atmosphere and the non-oxidizing atmosphere, the particle diameter can be controlled and the particle diameter distribution can be narrowed by alternately changing the oxidizing atmosphere and the non-oxidizing atmosphere.
【００１９】[0019]
【実施例】以下、実施例及び比較例により本発明をさら
に具体的に説明する。
（実施例１）
＜担持工程＞θ−アルミナからなり直径２〜４ｍｍのペ
レット状の触媒担体を所定量用意し、所定濃度のジニト
ロジアンミン白金水溶液の所定量を含浸させ、水分を蒸
発させてＰｔを担持させた。次いで所定濃度の硝酸ロジ
ウム水溶液の所定量を含浸させ、水分を蒸発させてＲｈ
を担持させた。触媒担体１リットル当たりにＰｔは１ｇ
担持され、Ｒｈは０．１ｇ担持された。EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. Example 1 <Supporting Step> A predetermined amount of pellet-shaped catalyst carrier made of θ-alumina and having a diameter of 2 to 4 mm is prepared, impregnated with a predetermined amount of a dinitrodiammine platinum aqueous solution having a predetermined concentration, and water is evaporated to Pt. Was carried. Then, a predetermined amount of an aqueous solution of rhodium nitrate having a predetermined concentration is impregnated to evaporate the water, and Rh
Was carried. 1 g of Pt per 1 liter of catalyst carrier
It was supported, and 0.1 g of Rh was supported.
【００２０】次に、得られたＰｔ−Ｒｈ担持担体を１１
０℃で一昼夜乾燥後、Ｈ2 が２０体積％とＮ2 が８０体
積％からなるガス中にて、４５０℃で３時間保持する水
素還元処理を行ってＰｔ／Ｒｈ触媒を調製した。
＜処理工程＞酸化ガス（５体積％Ｏ2 −９５体積％
Ｎ2 ）と還元ガス（１０体積％Ｈ2 −９０体積％Ｎ2 ）
とを用意し、上記のＰｔ／Ｒｈ触媒をそれぞれのガス雰
囲気中にて１０分間周期で５分毎に交互に５時間処理し
た。各ガスの温度はそれぞれ１２００℃であり、空間速
度はそれぞれＳＶ＝６０００／ｈである。Next, the obtained Pt-Rh-supported carrier was treated with 11
After drying at 0 ° C. for one day and night, hydrogen reduction treatment was carried out by holding at 450 ° C. for 3 hours in a gas containing 20% by volume of H 2 and 80% by volume of N 2 to prepare a Pt / Rh catalyst. <Treatment process> Oxidizing gas (5 vol% O 2 -95 vol%
N 2) and a reducing gas (10 vol% H 2 -90 vol% N 2)
Were prepared, and the above Pt / Rh catalysts were alternately treated for 5 hours in each gas atmosphere at intervals of 5 minutes every 5 minutes. The temperature of each gas is 1200 ° C., and the space velocity is SV = 6000 / h.
【００２１】処理工程後のＰｔ／Ｒｈ触媒を走査型電子
顕微鏡で観察し、Ｐｔの粒径とその分布を調べた。結果
を表１及び図１に示す。
（比較例１）実施例１で調製されたＰｔ／Ｒｈ触媒を用
い、１２００℃、ＳＶ＝６０００／ｈの大気雰囲気中で
５時間処理した。処理工程後のＰｔ／Ｒｈ触媒を走査型
電子顕微鏡で観察し、Ｐｔの粒径とその分布を調べた。
結果を表１に示す。
（比較例２）実施例１で調製されたＰｔ／Ｒｈ触媒を用
い、１２００℃、ＳＶ＝６０００／ｈの酸化ガス（５体
積％Ｏ2 −９５体積％Ｎ2 ）雰囲気中で５時間処理し
た。処理工程後のＰｔ／Ｒｈ触媒を走査型電子顕微鏡で
観察し、Ｐｔの粒径とその分布を調べた。結果を表１及
び図２に示す。
（評価）The Pt / Rh catalyst after the treatment process was observed with a scanning electron microscope to examine the particle size of Pt and its distribution. The results are shown in Table 1 and FIG. (Comparative Example 1) The Pt / Rh catalyst prepared in Example 1 was used and treated for 5 hours in an air atmosphere at 1200 ° C. and SV = 6000 / h. The Pt / Rh catalyst after the treatment process was observed with a scanning electron microscope to examine the particle size of Pt and its distribution.
The results are shown in Table 1. Comparative Example 2 Using the Pt / Rh catalyst prepared in Example 1, the Pt / Rh catalyst was treated for 5 hours in an oxidizing gas atmosphere (5% by volume O 2 -95% by volume N 2 ) at 1200 ° C. and SV = 6000 / h. . The Pt / Rh catalyst after the treatment process was observed with a scanning electron microscope to examine the particle size of Pt and its distribution. The results are shown in Table 1 and FIG. (Evaluation)
【００２２】[0022]
【表１】
表１及び図１、図２より、同じ温度及び同じ時間で処理
しても、ガス種によりＰｔの粒径と粒径分布が異なるこ
とがわかる。そして比較例１の方が比較例２よりも粒径
が大きいことから、酸素濃度が高いほど粒径が大きくな
ることがわかり、Ｐｔは酸化雰囲気下でシンタリングが
生じやすいことがわかる。つまり酸素濃度によってＰｔ
の粒径を制御することができる。[Table 1] From Table 1 and FIGS. 1 and 2, it can be seen that the particle size and particle size distribution of Pt differ depending on the gas species even if the treatment is performed at the same temperature and the same time. Since the particle size of Comparative Example 1 is larger than that of Comparative Example 2, it can be seen that the particle size becomes larger as the oxygen concentration is higher, and that Pt is likely to cause sintering in an oxidizing atmosphere. In other words, depending on the oxygen concentration, Pt
The particle size of can be controlled.
【００２３】一方、図２より、比較例２では粒径分布が
広く、Ｐｔは粒径の小さいものから大きいものまで混在
している。つまり酸化雰囲気だけでは粒径分布を狭くす
ることは困難である。しかし図１より、実施例１のよう
に酸化雰囲気と還元雰囲気を交互に繰り返すことで、粒
径分布を著しく狭くすることができることが明らかであ
る。
（実施例２）γ−アルミナからなり直径２〜４ｍｍのペ
レット状の触媒担体を所定量用意し、所定濃度のジニト
ロジアンミン白金水溶液の所定量を含浸させ、水分を蒸
発させてＰｔを担持させた。触媒担体１リットル当たり
にＰｔは２ｇ担持された。On the other hand, as shown in FIG. 2, in Comparative Example 2, the particle size distribution is wide, and Pt is mixed from the small particle size to the large particle size. That is, it is difficult to narrow the particle size distribution only with the oxidizing atmosphere. However, it is clear from FIG. 1 that the particle size distribution can be significantly narrowed by alternately repeating the oxidizing atmosphere and the reducing atmosphere as in Example 1. (Example 2) A predetermined amount of a pellet-shaped catalyst carrier made of γ-alumina and having a diameter of 2 to 4 mm was prepared, impregnated with a predetermined amount of a dinitrodiammine platinum aqueous solution having a predetermined concentration, and water was evaporated to support Pt. . 2 g of Pt was loaded per liter of the catalyst carrier.
【００２４】次に、得られたＰｔ担持担体を１１０℃で
一昼夜乾燥後、Ｈ2 が２０体積％とＮ2 が８０体積％か
らなるガス中にて、４５０℃で３時間保持する水素還元
処理を行ってＰｔ触媒を調製した。
＜処理工程＞酸化ガス（１０体積％Ｏ2 −９５体積％Ｎ
2 ）と還元ガス（２０体積％Ｈ2 −ＣＯ（Ｈ2 に対して
モル比で１／３）−残部Ｎ2 ）とを用意し、上記のＰｔ
触媒をそれぞれのガス雰囲気中にて２０分間周期で１０
分毎に交互に５時間処理した。各ガスの温度はそれぞれ
９００℃であり、各ガスのＷ／Ｆ（触媒重量当たりの空
間速度）はそれぞれ８．３×１０-5ｇ・ｈ／ｃｃであ
る。Next, the obtained Pt-supported carrier was dried at 110 ° C. for a whole day and night, and then treated with hydrogen for 3 hours at 450 ° C. in a gas containing 20% by volume of H 2 and 80% by volume of N 2. Was carried out to prepare a Pt catalyst. <Treatment process> Oxidizing gas (10 vol% O 2 -95 vol% N
2 ) and a reducing gas (20 volume% H 2 —CO (molar ratio to H 2 ⅓) -balance N 2 ), and prepare the above Pt.
The catalyst was used for 10 minutes in each gas atmosphere at a cycle of 10 minutes.
Alternately every 5 minutes for 5 hours. The temperature of each gas is 900 ° C., and the W / F (space velocity per catalyst weight) of each gas is 8.3 × 10 −5 g · h / cc.
【００２５】処理工程後のＰｔ触媒についてＸ線回折を
測定するとともに走査型電子顕微鏡で観察し、Ｐｔの粒
径とその分布を調べた。結果を表２に示す。
（比較例３）実施例２で調製されたＰｔ触媒を、大気中
にて６００℃で１時間処理した。処理工程後のＰｔ触媒
についてＸ線回折を測定するとともに走査型電子顕微鏡
で観察し、Ｐｔの粒径とその分布を調べた。結果を表２
に示す。
（評価）The Pt catalyst after the treatment step was measured for X-ray diffraction and observed by a scanning electron microscope to examine the particle size of Pt and its distribution. The results are shown in Table 2. (Comparative Example 3) The Pt catalyst prepared in Example 2 was treated in the air at 600 ° C for 1 hour. The Pt catalyst after the treatment step was measured for X-ray diffraction and observed with a scanning electron microscope to examine the particle size of Pt and its distribution. The results are shown in Table 2.
Shown in. (Evaluation)
【００２６】[0026]
【表２】
表２より、実施例２の方法によれば平均粒径は比較例３
と同等であるものの、粒径分布をきわめて狭くすること
ができることがわかる。[Table 2] From Table 2, according to the method of Example 2, the average particle size is Comparative Example 3
Although it is equivalent to, it can be seen that the particle size distribution can be extremely narrowed.
【００２７】[0027]
【発明の効果】すなわち本発明の触媒の製造方法によれ
ば、触媒金属粒子の粒径を短時間で任意に制御可能であ
り、かつ得られた粒径の分布をきわめて狭くすることが
できる。したがって使用目的あるいは使用条件に応じた
最適粒径に容易に制御することができ、高価な触媒金属
の有効利用を図ることができる。[Effects of the Invention] That is, according to the method for producing a catalyst of the present invention, the particle size of the catalytic metal particles can be arbitrarily controlled in a short time, and the obtained particle size distribution can be made extremely narrow. Therefore, it is possible to easily control the optimum particle size according to the purpose of use or the conditions of use, and it is possible to effectively use the expensive catalyst metal.
【図１】本発明の一実施例で処理された触媒中のＰｔの
粒径分布を示すグラフである。FIG. 1 is a graph showing the particle size distribution of Pt in the catalyst treated in one example of the present invention.
【図２】比較例２で処理された触媒中のＰｔの粒径分布
を示すグラフである。FIG. 2 is a graph showing the particle size distribution of Pt in the catalyst treated in Comparative Example 2.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平５−261284（ＪＰ，Ａ) 特開 昭56−84636（ＪＰ，Ａ) 特開 昭50−57090（ＪＰ，Ａ) 特開 昭55−3856（ＪＰ，Ａ) 特開 昭50−4011（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B01J 21/00 - 38/74 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-5-261284 (JP, A) JP-A-56-84636 (JP, A) JP-A-50-57090 (JP, A) JP-A-55- 3856 (JP, A) JP-A-50-4011 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) B01J 21/00 -38/74
Claims (2)
ｈ，Ｐｄ，Ａｕ，Ａｇ，Ｉｒ及びＲｕから選ばれる触媒
金属を担持して触媒金属担持担体とする担持工程と、 酸化雰囲気と非酸化雰囲気が交互に繰り返されるガス雰
囲気中で該触媒金属担持担体を繰り返し酸化及び非酸化
処理して、担持されている該触媒金属の粒径を制御し粒
径分布を狭くする処理工程と、を有することを特徴とす
る触媒の製造方法。1. A catalyst carrier comprising a porous carrier, Pt, R
A supporting step of supporting a catalytic metal selected from h, Pd, Au, Ag, Ir and Ru as a catalytic metal supporting carrier, and a gas atmosphere in which an oxidizing atmosphere and a non-oxidizing atmosphere are alternately repeated.
The catalyst metal-supported carrier is repeatedly oxidized and non-oxidized in an atmosphere to control the particle size of the supported catalyst metal.
And a treatment step for narrowing the diameter distribution .
載の触媒の製造方法。A method for producing the above catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26327295A JP3441267B2 (en) | 1995-10-11 | 1995-10-11 | Catalyst production method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26327295A JP3441267B2 (en) | 1995-10-11 | 1995-10-11 | Catalyst production method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09103687A JPH09103687A (en) | 1997-04-22 |
| JP3441267B2 true JP3441267B2 (en) | 2003-08-25 |
Family
ID=17387163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26327295A Expired - Fee Related JP3441267B2 (en) | 1995-10-11 | 1995-10-11 | Catalyst production method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3441267B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11123330A (en) * | 1997-08-20 | 1999-05-11 | Hino Motors Ltd | Exhaust gas cleaning catalyst and manufacture thereof |
| JP2002210369A (en) * | 2001-01-19 | 2002-07-30 | Toyota Motor Corp | Catalyst for cleaning exhaust gas and its production method |
| EP1254711A1 (en) * | 2001-05-05 | 2002-11-06 | OMG AG & Co. KG | Supported noble metal catalyst and preparation process thereof |
| US7150861B2 (en) | 2001-09-28 | 2006-12-19 | Nippon Shokubai Co., Ltd. | Catalyst for purification of exhaust gases and process for purification of exhaust gases |
| JP4274826B2 (en) * | 2003-03-17 | 2009-06-10 | 株式会社豊田中央研究所 | Exhaust gas purification catalyst and method for producing the same |
| JP5003954B2 (en) * | 2007-11-19 | 2012-08-22 | 株式会社豊田中央研究所 | Exhaust gas purification oxidation catalyst, production method thereof, and exhaust gas purification method using exhaust gas purification oxidation catalyst |
| JP2011041913A (en) * | 2009-08-21 | 2011-03-03 | Daihatsu Motor Co Ltd | Exhaust gas purifying catalyst |
| JP5506286B2 (en) * | 2009-08-21 | 2014-05-28 | ダイハツ工業株式会社 | Exhaust gas purification catalyst |
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1995
- 1995-10-11 JP JP26327295A patent/JP3441267B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09103687A (en) | 1997-04-22 |
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