JP2013034937A - Method for producing platinum particle, method for producing platinum particle carrying catalyst, and purifying catalyst - Google Patents
Method for producing platinum particle, method for producing platinum particle carrying catalyst, and purifying catalyst Download PDFInfo
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 title claims abstract description 270
- 229910052697 platinum Inorganic materials 0.000 title claims abstract description 136
- 239000003054 catalyst Substances 0.000 title claims abstract description 84
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 31
- 239000002245 particle Substances 0.000 title abstract description 31
- 239000001257 hydrogen Substances 0.000 claims abstract description 25
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 25
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 24
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 17
- 238000006243 chemical reaction Methods 0.000 claims abstract description 14
- 239000010419 fine particle Substances 0.000 claims description 48
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 7
- 230000002441 reversible effect Effects 0.000 claims description 7
- 238000002336 sorption--desorption measurement Methods 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 6
- 239000007789 gas Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 3
- 230000001747 exhibiting effect Effects 0.000 claims description 2
- 239000000243 solution Substances 0.000 abstract description 61
- 238000000034 method Methods 0.000 abstract description 8
- -1 platinum ion Chemical class 0.000 abstract description 8
- 239000007864 aqueous solution Substances 0.000 abstract description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 abstract description 3
- 229910017604 nitric acid Inorganic materials 0.000 abstract description 3
- ZXVONLUNISGICL-UHFFFAOYSA-N 4,6-dinitro-o-cresol Chemical group CC1=CC([N+]([O-])=O)=CC([N+]([O-])=O)=C1O ZXVONLUNISGICL-UHFFFAOYSA-N 0.000 abstract 1
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- 239000001307 helium Substances 0.000 description 6
- 229910052734 helium Inorganic materials 0.000 description 6
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- 229910044991 metal oxide Inorganic materials 0.000 description 5
- 150000004706 metal oxides Chemical class 0.000 description 5
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- 230000000694 effects Effects 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 239000012876 carrier material Substances 0.000 description 3
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- 230000006798 recombination Effects 0.000 description 3
- 238000005215 recombination Methods 0.000 description 3
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 230000005574 cross-species transmission Effects 0.000 description 2
- 238000010494 dissociation reaction Methods 0.000 description 2
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- 238000004108 freeze drying Methods 0.000 description 2
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- 150000002431 hydrogen Chemical class 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000011859 microparticle Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- UYXRCZUOJAYSQR-UHFFFAOYSA-N nitric acid;platinum Chemical compound [Pt].O[N+]([O-])=O UYXRCZUOJAYSQR-UHFFFAOYSA-N 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- YZCKVEUIGOORGS-UHFFFAOYSA-N Hydrogen atom Chemical compound [H] YZCKVEUIGOORGS-UHFFFAOYSA-N 0.000 description 1
- 230000010718 Oxidation Activity Effects 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002744 anti-aggregatory effect Effects 0.000 description 1
- 229940045985 antineoplastic platinum compound Drugs 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 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
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 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
- 230000008859 change Effects 0.000 description 1
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- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000002003 electron diffraction Methods 0.000 description 1
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- 239000012528 membrane Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
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- 239000002105 nanoparticle Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 150000003058 platinum compounds Chemical class 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 239000005297 pyrex Substances 0.000 description 1
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- 238000010992 reflux Methods 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
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- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
Description
本発明は、白金微粒子の製造方法、白金を担体上に分散して担持した触媒の製造方法、ならびに浄化触媒に関する。 The present invention relates to a method for producing platinum fine particles, a method for producing a catalyst in which platinum is dispersed and supported on a carrier, and a purification catalyst.
白金微粒子の製造方法は、従来から多数知られており、一般的には塩化白金酸水溶液にヒドラジン、水素化ホウ素ナトリウム等の還元剤を加えて白金微粒子を還元させ担体上に生成させる。この際還元した白金粒子が凝集して粒子径が大きくなることが容易に起こり、ナノメーターサイズの白金微粒子を得ることが困難になる。そのため、界面活性剤等を加えて白金微粒子の凝集を防止する必要があった。 Many methods for producing platinum fine particles have been known. Generally, platinum fine particles are reduced by adding a reducing agent such as hydrazine or sodium borohydride to a chloroplatinic acid aqueous solution, and produced on a carrier. At this time, the reduced platinum particles are easily aggregated to increase the particle diameter, and it is difficult to obtain nanometer-sized platinum fine particles. Therefore, it is necessary to add a surfactant or the like to prevent the aggregation of the platinum fine particles.
しかし、界面活性剤を添加してもしばしば凝集防止効果は不十分であり、また白金微粒子を応用する際にこれより界面活性剤を除去するための洗浄が複雑になったり、加熱除去するなど手間がかかり、さらに白金がこの間にさらに凝集する等といった問題があり、触媒やそのほかの利用にあたり障害となっていた。 However, even when a surfactant is added, the anti-aggregation effect is often insufficient, and when applying fine platinum particles, the cleaning for removing the surfactant becomes more complicated, and it is troublesome to remove by heating. In addition, there is a problem that platinum is further aggregated during this period, which is an obstacle to the use of the catalyst and others.
また、白金の活性に対して最適な粒径があると推測されるが、従来の触媒の製造においては白金粒子の粒径の制御については十分検討されていなかった。白金担持触媒の白金微粒子は担体との接触の状況、製造プロセスにより、その分散度に不均一性が生じ、特に数ナノメーターの白金微粒子を担体の影響を最小限にして担体上に均一に担持させることは困難であった。 Further, although it is presumed that there is an optimum particle size for the activity of platinum, the control of the particle size of platinum particles has not been sufficiently studied in the production of conventional catalysts. The platinum fine particles of the platinum-supported catalyst have non-uniformity in the degree of dispersion depending on the state of contact with the carrier and the manufacturing process, and in particular, platinum fine particles of several nanometers are uniformly supported on the carrier with minimal influence of the carrier. It was difficult to do.
さらに、担体として一般に用いられる金属酸化物表面では、白金化合物や白金イオンが吸着して還元されるため、担体と白金溶液を混合した際、白金が溶液との接触時には非常に分散性高く担体上に高い担持率で作製できても、その後での熱処理時に著しい凝集がおこるといった問題もあった。 Furthermore, since platinum compounds and platinum ions are adsorbed and reduced on the surface of metal oxides generally used as a carrier, when the carrier and the platinum solution are mixed, the platinum is extremely dispersible when in contact with the solution. However, even if it can be produced at a high loading rate, there is a problem that significant aggregation occurs during the subsequent heat treatment.
特許文献１、２、および３には、担体と白金溶液の混合物にエタノールのような試薬を添加して白金分散触媒を製造する技術が開示されている。しかしながら、本発明者らが研究した結果、担体として金属酸化物を用い、その担体材料と白金溶液が混合されると担体への白金微粒子の分散性がよくないことがわかった。原因は詳細には不明だが、溶液からの担体表面への白金の吸着と還元がすみやかにおこるためと考えられる。特許文献１、２および３の実施例では担体に炭素材を用いており、多くの触媒で使用される金属酸化物担体での問題となる担体へ吸着および熱処理や使用時での凝集現象が見出されていなかったものと思われる。 Patent Documents 1, 2, and 3 disclose techniques for producing a platinum dispersion catalyst by adding a reagent such as ethanol to a mixture of a carrier and a platinum solution. However, as a result of studies by the present inventors, it has been found that when a metal oxide is used as a carrier and the carrier material and a platinum solution are mixed, the dispersibility of the platinum fine particles on the carrier is not good. Although the cause is unknown in detail, it is thought that the adsorption and reduction of platinum from the solution onto the support surface occur promptly. In Examples of Patent Documents 1, 2, and 3, a carbon material is used as a carrier, and adsorption and heat treatment and agglomeration phenomenon during use are observed, which is a problem with metal oxide carriers used in many catalysts. It seems that it was not issued.
以上より、アルミナ等の金属酸化物上に均一に担持させたシングルナノメータ―（１０ｎｍ未満）サイズの白金微粒子からなる触媒が実用的に得られず、したがってその特徴は十分に知られていなかった。 From the above, a catalyst consisting of single nanometer (less than 10 nm) size platinum fine particles uniformly supported on a metal oxide such as alumina has not been practically obtained, and its characteristics have not been sufficiently known.
本発明の課題は、白金微粒子の製造において、界面活性剤を用いずに製造した均一で微細な白金微粒子を担持した触媒の製造方法を提供することである。また、均一なシングルナノサイズの白金微粒子を水溶液中で簡易に生成させるとともに、白金微粒子を担持した触媒がすぐれた浄化性能を示すことを本発明の課題とする。 The subject of this invention is providing the manufacturing method of the catalyst which carry | supported the uniform and fine platinum fine particle manufactured without using surfactant in manufacture of platinum fine particle. It is another object of the present invention that uniform single nano-sized platinum fine particles are easily generated in an aqueous solution and that the catalyst supporting the platinum fine particles exhibits excellent purification performance.
本発明者は、白金イオン溶液としてジニトロジアミノ硝酸溶液を使用し、かつ還元剤としてアルコール、とくにエタノールを使用することにより、所定温度域に保持した溶液中に、微細な白金微粒子が生成する。また、これら白金微粒子が担体上に均一で高分散に担持された触媒が得られるが、そのとき白金錯体の反応率が１０％以上、より好ましくは３０％以上、さらに好ましくは８０％以上の反応率において、顕著な白金粒径の均一性と触媒活性のよいこと、すなわち、水素の吸脱着挙動の特性と浄化性能の向上することを見出し、本発明を完成した。すなわち、本発明によれば、以下の白金微粒子担持触媒の製造方法、およびそれによって得られた白金微粒子担持触媒が提供される。 The present inventor uses a dinitrodiamino nitric acid solution as a platinum ion solution and uses alcohol, particularly ethanol, as a reducing agent, whereby fine platinum fine particles are generated in a solution kept in a predetermined temperature range. In addition, a catalyst in which these platinum fine particles are uniformly and highly dispersed on a carrier can be obtained. At that time, the reaction rate of the platinum complex is 10% or more, more preferably 30% or more, and further preferably 80% or more. As a result, the inventors have found that the uniformity of the platinum particle size and the catalytic activity are excellent, that is, the characteristics of hydrogen adsorption / desorption behavior and the purification performance are improved, and the present invention has been completed. That is, according to the present invention, the following method for producing a platinum particle-supported catalyst and the platinum particle-supported catalyst obtained thereby are provided.
[１] 白金錯体水溶液に還元剤を加えて白金に還元して白金微粒子担持触媒を製造する方法において、白金イオン溶液としてジニトロジアミノ硝酸溶液、還元剤としてアルコールを使用し、８０℃〜９５℃で保持し、白金微粒子含有溶液の反応率を１０％以上として白金微粒子粉末を得ることを特徴とする白金微粒子の製造方法。 [1] In a method for producing a platinum fine particle-supported catalyst by adding a reducing agent to an aqueous platinum complex solution and reducing it to platinum, a dinitrodiaminonitric acid solution is used as the platinum ion solution, and alcohol is used as the reducing agent, A method for producing platinum fine particles, characterized in that a platinum fine particle powder is obtained with a reaction rate of the platinum fine particle-containing solution being 10% or more.
[２] 白金錯体水溶液に還元剤を加えて白金に還元して白金微粒子担持触媒を製造する方法において、白金イオン溶液としてジニトロジアミノ硝酸溶液、還元剤としてアルコールを使用し、８０℃〜９５℃で保持し、白金微粒子含有溶液の反応率を１０％以上としたのちに担体に接触させ、４００℃以上で熱処理することを特徴とする白金微粒子担持触媒の製造方法。 [2] In a method for producing a platinum fine particle-supported catalyst by adding a reducing agent to an aqueous platinum complex solution and reducing it to platinum, a dinitrodiaminonitric acid solution is used as the platinum ion solution, and an alcohol is used as the reducing agent. A method for producing a platinum fine particle-supported catalyst, characterized in that the platinum fine particle-containing catalyst is held and brought into contact with a support after the reaction rate of the platinum fine particle-containing solution is 10% or higher and heat-treated at 400 ° C or higher.
[３] 前記[１]または[２]に記載の製造法により得られる、完全に可逆的な水素の吸着脱離特性を示すナノメータサイズの白金微粒子あるいは白金微粒子担持触媒。 [3] A nanometer-sized platinum microparticle or a platinum microparticle-supported catalyst that exhibits a completely reversible hydrogen adsorption / desorption characteristic obtained by the production method according to [1] or [2].
[４] 前記[３]に記載の白金微粒子担持触媒を含む排ガス浄化用触媒。
[4] An exhaust gas purifying catalyst comprising the platinum particle-supported catalyst according to [3].
本発明によれば、界面活性剤の使用なしで均一で微細な白金微粒子が製造でき、さらに当該白金微粒子を担持した触媒を製造することができる。上記白金微粒子担持触媒の製造方法において、白金微粒子の還元、また白金微粒子担持の際に白金微粒子の分散度が低くなることや粒径が制御しがたいなどの問題が改善される。本方法では、均一な数ナノメータの白金微粒子を担持した触媒を高活性な状態で製造することができる。 According to the present invention, uniform and fine platinum fine particles can be produced without the use of a surfactant, and a catalyst supporting the platinum fine particles can be produced. In the above method for producing a platinum fine particle-supported catalyst, problems such as reduction of the platinum fine particles and a decrease in the degree of dispersion of the platinum fine particles and difficulty in controlling the particle diameter when the platinum fine particles are supported are improved. In this method, a catalyst carrying uniform fine platinum particles of several nanometers can be produced in a highly active state.
以下、図面を参照しつつ本発明の実施の形態について説明する。本発明は、以下の実施形態に限定されるものではなく、発明の範囲を逸脱しない限りにおいて、変更、修正、改良を加え得るものである。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.
本発明の第一の発明は、白金錯体水溶液に還元剤を加えて白金金属に還元して白金微粒子を製造する方法において、白金イオン溶液としてジニトロジアミノ硝酸溶液、還元剤としてアルコールを使用し、８０℃〜９５℃で保持することを特徴とする白金微粒子含有溶液ならびに白金粒子の製造方法である。ジニトロジアミン白金硝酸溶液を純水で希釈して水溶液とし、アルコールを加えて混合し、還流しながら加熱して保持する。原料溶液での白金微粒子の還元、担持において、還元温度を８０〜９５℃、還元時間を２０分以上とすることが実際上望ましい。詳細には、紫外可視分光計にて溶液中にある白金錯体の分解率に相当する還元反応率が、特定の割合以上であることを特徴とするものである。上記還元に必要な時間を見極める方法としては、溶液の一部を取り出しジニトロジアミン白金の溶液中濃度調べることが溶液の管理上特に有用であるのでこれを採用する。このような反応率を１０％以上、より好ましくは３０％以上、さらに好ましくは８０％以上としたのちの溶液を、遠心分離器によって濃縮した白金溶液として、さらに微粒子を含む溶液を凍結乾燥または熱乾燥して白金微粒子を取り出すか、基板または膜状物に溶液を注ぎ、乾燥することで分散させた状態の微粒子を得る。 The first invention of the present invention is a method for producing platinum fine particles by adding a reducing agent to an aqueous platinum complex solution and reducing it to platinum metal, using a dinitrodiaminonitric acid solution as a platinum ion solution and alcohol as a reducing agent, A platinum fine particle-containing solution and a method for producing platinum particles, which are characterized by holding at a temperature of from 95 to 95 ° C. A dinitrodiamine platinum nitric acid solution is diluted with pure water to make an aqueous solution, mixed with alcohol, heated and held under reflux. In the reduction and loading of the platinum fine particles in the raw material solution, it is practically desirable that the reduction temperature is 80 to 95 ° C. and the reduction time is 20 minutes or longer. Specifically, the reduction reaction rate corresponding to the decomposition rate of the platinum complex in the solution with an ultraviolet-visible spectrometer is a specific rate or more. As a method for determining the time required for the reduction, it is particularly useful in managing the solution to take out a part of the solution and examine the concentration of dinitrodiamine platinum in the solution. After the reaction rate is 10% or more, more preferably 30% or more, and further preferably 80% or more, the solution is concentrated as a platinum solution by a centrifuge, and the solution containing fine particles is freeze-dried or heat-treated. The platinum fine particles are taken out by drying, or the solution is poured into a substrate or a film and dried to obtain fine particles in a dispersed state.
本発明の第二の発明は、白金錯体水溶液に還元剤を加えて白金金属に還元し白金微粒子を製造する方法において、白金イオン溶液としてジニトロジアミノ硝酸溶液、還元剤としてアルコールを使用し、８０℃〜９５℃で保持し反応率を１０％以上としたのち担体に接触させることを特徴とする白金粒子担持触媒の製造方法である。第一の発明と同様に、溶液中にまず還元剤を加えて白金微粒子に還元してのち、反応率を１０％以上、より好ましくは３０％以上、さらにさらに好ましくは８０％以上において、前記担体を加え、４００℃以上で熱処理することにより白金を担持した触媒を製造する。担体としては、アルミナ、セリア、ジルコニア等の粉末もしくは塊状が好ましく、原料溶液をこれらの担体材料に接触させる。すなわち、担体である金属酸化物粉末を、はじめから溶液と接触させないで、白金溶液とアルコールの混合溶液中に白金微粒子を生成させたのち、これを担体材料と接触させることが重要である。 The second invention of the present invention is a method for producing platinum fine particles by adding a reducing agent to an aqueous platinum complex solution and reducing it to platinum metal, using a dinitrodiaminonitric acid solution as the platinum ion solution and alcohol as the reducing agent, A method for producing a platinum particle-supported catalyst, characterized in that the catalyst is maintained at ˜95 ° C. and the reaction rate is adjusted to 10% or more and then brought into contact with a carrier. In the same manner as in the first invention, after the reducing agent is first added to the solution and reduced to platinum fine particles, the reaction rate is 10% or more, more preferably 30% or more, and still more preferably 80% or more. And a catalyst carrying platinum is produced by heat treatment at 400 ° C. or higher. The carrier is preferably a powder or lump of alumina, ceria, zirconia or the like, and the raw material solution is brought into contact with these carrier materials. That is, it is important to form platinum fine particles in a mixed solution of a platinum solution and an alcohol without bringing the metal oxide powder as a carrier into contact with the solution from the beginning, and then bringing this into contact with the carrier material.
さらに、本発明は、前記白金微粒子が担持された粉末状の担体を濾過あるいは遠心分離器などによって溶液から取り出して濃縮もしくは分離後、凍結後に真空乾燥するか、大気中で熱乾燥して白金担持触媒とする。凍結乾燥では、氷点以下に凍結した状態の試料を真空中で乾燥させ、また風乾してもよく室温、大気中で３日以上放置する。また熱乾燥では、温度を １１０〜１３０℃、乾燥時間を８〜２４時間で乾燥すればよく、その後の熱処理を４００〜１０００℃の温度で任意の時間で行ってもよい。 Further, the present invention provides a method for removing the powdery carrier carrying the platinum fine particles from a solution by filtration or a centrifugal separator and concentrating or separating the solution and then vacuum-drying it after freezing or heat-drying it in the atmosphere to carry the platinum carrier. Use as a catalyst. In lyophilization, a sample frozen below the freezing point is dried in a vacuum, or may be air-dried and left at room temperature in the atmosphere for 3 days or more. In thermal drying, the temperature may be 110 to 130 ° C., the drying time may be 8 to 24 hours, and the subsequent heat treatment may be performed at a temperature of 400 to 1000 ° C. for an arbitrary time.
本発明の第三の発明は、第一、第二の発明の製造法により製造される完全に可逆的な水素の吸着脱離特性を示すナノメータサイズの白金微粒子および白金微粒子担持触媒であり、特に、特異的な水素の吸着脱離特性を示す白金微粒子担持触媒である。白金上では一般に、水素分子は解離的に吸着し、原子状水素が白金表面に観測される。本発明では、通常の製造法では、水素の完全可逆的な吸着脱離、すなわち解離および再結合に対して吸着水素が脱気処理において脱離しないことがないような完全可逆性である触媒を、本発明の白金触媒として提案する。高分散性の白金ではその表面に解離吸着した水素が担体上へ移行するスピルオーバー現象が観測される。本発明の触媒では、白金の分散度が非常に高い場合でもこのような担体の影響を受けにくく、分散度が非常に高い状態の担持触媒でも白金自体すなわち金属粒子が独立した状態の性質を示すことに特徴がある。すなわち、水素の解離吸着と再結合反応ならびに脱離が白金金属上で完全に可逆的に行われることを特徴とする。 A third invention of the present invention is a nanometer-sized platinum fine particle and a platinum fine particle-supported catalyst that exhibit completely reversible hydrogen adsorption / desorption characteristics produced by the production methods of the first and second inventions, A platinum fine particle-supported catalyst exhibiting specific hydrogen adsorption / desorption characteristics. In general, hydrogen molecules are dissociatively adsorbed on platinum, and atomic hydrogen is observed on the platinum surface. In the present invention, in a normal production method, a completely reversible adsorption / desorption of hydrogen, that is, a catalyst that is completely reversible so that the adsorbed hydrogen is not desorbed in the degassing process against dissociation and recombination. The platinum catalyst of the present invention is proposed. In high-dispersion platinum, a spillover phenomenon is observed in which hydrogen dissociated and adsorbed on the surface migrates onto the support. In the catalyst of the present invention, even when the dispersion degree of platinum is very high, it is hardly affected by such a carrier, and even with a supported catalyst in a state where the dispersion degree is very high, platinum itself, that is, metal particles exhibit independent properties. There is a special feature. That is, hydrogen is dissociatively adsorbed, recombined, and desorbed on platinum metal completely reversibly.
本発明の第四の発明は、第三の発明の完全可逆的な解離吸着および再結合反応を示す触媒を排ガス浄化に利用することを特徴とする浄化用触媒である。 According to a fourth aspect of the present invention, there is provided a purification catalyst characterized in that the catalyst showing the completely reversible dissociative adsorption and recombination reaction of the third aspect of the invention is used for exhaust gas purification.
以下、実施例及び比較例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。 EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these.
（実施例１）
白金濃度４．５ｇ／Ｌのジニトロジアンミン白金錯体の硝酸溶液を用意し、白金の濃度が０．２５、０．９および２．８ｍｍｏｌ／Ｌになるように蒸留水を加えて溶液を調製した。これにエタノールを、全溶液の１０体積％となる割合で添加して撹拌混合し、全体で１５０ｍLの溶液を作製した。溶液をフラスコに入れ、攪拌しながら、恒温槽で９５℃の温度に調整し、還流器をつけて保持した。まず、一定時間ごとに、時間を変えて溶液を各約１ｍＬずつ取り出し石英セルに入れ、紫外可視分光計（島津製作所製ＵＶ−ｍｉｎｉ）にてスペクトル測定をおこなったところ、２５０ｎｍ付近の吸収強度が保持時間とともに減少してゆくことがわかった。そこで、この吸収強度を指標として反応率をモニターした。この光吸収帯がなくなった溶液を遠心分離器にかけ、メンブランフィルターで溶液を除去後、固形物を収集し１１０℃で乾燥後、粉末Ｘ線回折計（リガク製Rint-2000）で相分析を行った。図１にその回折図形を示す。いずれの濃度の溶液からも金属の白金のみが検出され、かつその粒径が相当小さくシングルナノレベルであることが示された。さらに、これらの溶液では上記の光学的変化とともに生成物を確認するため、溶液をマイクログリッド上に滴下し、透過型電子顕微鏡観察を行った。図２に、２．８ｍｍｏｌ／Ｌの溶液から得た粒子の透過型電子顕微鏡像の一例を示すが、約２ｎｍ（ナノメーター）の粒径を中心に、独立した非常に細かい粒子が検出され、さらに電子線回折からも粒子が白金であることがわかった。図３に、２．８ｍｍｏｌ／Ｌの溶液から得た粒子の加熱保持時間が１００分のときに観察した電子顕微鏡像から測定した白金の粒径の分布の結果を示す。１０ｎｍ以上の粗大な粒子はなく、多くは１〜４ｎｍに分布する微細で均一な白金粒子が作製できた。例えば、２．８ｍｍｏｌ／Ｌの溶液では、保持時間４５分で反応率が１５％、平均粒径２．６ｎｍ、保持時間６０分で反応率が１９％、平均粒径２．４ｎｍ、保持時間１００分で反応率が３１％、平均粒径２．５ｎｍであった。以上の結果は、微細で分散した白金微粒子が製造できたことを示すものであった。
Example 1
A nitric acid solution of a dinitrodiammine platinum complex having a platinum concentration of 4.5 g / L was prepared, and distilled water was added so that the concentrations of platinum were 0.25, 0.9, and 2.8 mmol / L to prepare a solution. Ethanol was added to this at a ratio of 10% by volume of the total solution and mixed by stirring to prepare a solution of 150 mL in total. The solution was put into a flask, adjusted to a temperature of 95 ° C. in a thermostatic bath with stirring, and held with a refluxer. First, about 1 mL of each solution was taken out at different time intervals and placed in a quartz cell, and the spectrum was measured with an ultraviolet-visible spectrometer (UV-mini manufactured by Shimadzu Corporation). It was found that it decreased with the retention time. Therefore, the reaction rate was monitored using this absorption intensity as an index. Centrifuge the solution with no optical absorption band, remove the solution with a membrane filter, collect the solid, dry at 110 ° C, and perform phase analysis with a powder X-ray diffractometer (Rint-2000 manufactured by Rigaku). It was. FIG. 1 shows the diffraction pattern. Only metallic platinum was detected from solutions of any concentration, and the particle size was shown to be considerably small and single nano level. Furthermore, in these solutions, in order to confirm the product along with the above optical change, the solution was dropped on a microgrid and observed with a transmission electron microscope. FIG. 2 shows an example of a transmission electron microscope image of particles obtained from a 2.8 mmol / L solution. Independently fine particles are detected around a particle diameter of about 2 nm (nanometer). In addition, electron diffraction revealed that the particles were platinum. FIG. 3 shows the results of the particle size distribution of platinum measured from an electron microscope image observed when the heating and holding time of particles obtained from a 2.8 mmol / L solution was 100 minutes. There were no coarse particles of 10 nm or more, and many fine and uniform platinum particles distributed in the range of 1 to 4 nm could be produced. For example, in a solution of 2.8 mmol / L, the reaction rate is 15% at a retention time of 45 minutes, the average particle size is 2.6 nm, the reaction rate is 19% at a retention time of 60 minutes, the average particle size is 2.4 nm, and the retention time is 100. The reaction rate was 31% and the average particle size was 2.5 nm. The above results indicated that fine and dispersed platinum fine particles could be produced.
（実施例２）
濃度２．８ｍｍｏｌ／Ｌのジニトロジアミン白金硝酸溶液とエタノ−ルの混合溶液を実施例１と同様に準備して、溶液に０．０２５ｇの白金を含むように調整し、加熱無し、ならびに９５℃で加熱時間６０分間保持後の溶液を用意した。それぞれの溶液に担体としてアルミナ粉末（住友化学製、１１５ｍ２／ｇ）の５．０ｇを加えて十分撹拌し混合した。次に、遠心分離器にかけ上澄みを除去、濃縮後、凍結乾燥法により乾燥させ、５００℃、３時間熱処理し、アルミナ担持白金触媒を得た。前者（加熱なし）を比較触媒Ｒとして、また後者を本発明の触媒Ａとする。触媒学会の金属分散度測定での前処理条件に準拠して処理後、一酸化炭素吸着操作を行い、白金の分散度を測定した。比較触媒Ｒと触媒Ａの白金分散度は、それぞれ８５％と９６％であった。比較触媒Ｒは、従来操作による白金担持触媒の作製法に相当するが、これに比べ本発明の製造方法による触媒Ａでは、白金分散度の高いアルミナ担持白金触媒が得られたことがわかる。
(Example 2)
A mixed solution of dinitrodiamine platinum nitric acid solution and ethanol having a concentration of 2.8 mmol / L was prepared in the same manner as in Example 1, adjusted to contain 0.025 g of platinum in the solution, no heating, and 95 ° C. A solution after holding for 60 minutes was prepared. To each solution, 5.0 g of alumina powder (manufactured by Sumitomo Chemical Co., Ltd., 115 m 2 / g) was added as a carrier and sufficiently stirred and mixed. Next, the supernatant was removed by centrifuging, concentrated, dried by freeze-drying, and heat-treated at 500 ° C. for 3 hours to obtain an alumina-supported platinum catalyst. The former (without heating) is referred to as comparative catalyst R, and the latter is referred to as catalyst A of the present invention. After treatment according to the pretreatment conditions in the metal dispersity measurement of the Catalysis Society of Japan, carbon monoxide adsorption operation was performed to measure the dispersity of platinum. The platinum dispersions of Comparative Catalyst R and Catalyst A were 85% and 96%, respectively. The comparative catalyst R corresponds to a method for producing a platinum-supported catalyst according to a conventional operation, but it can be seen that an alumina-supported platinum catalyst having a high platinum dispersion was obtained with the catalyst A according to the production method of the present invention.
（実施例３）
実施例２で調製した比較触媒Ｒと本発明の触媒Ａについて、日本ベル製Ｂｅｌｓｏｒｐｍａｘを用いて、水素吸着脱離の実験を行った。試料０．１ｇを石英ガラス容器に充填した。試料をヘリウム中にて４００℃で３０分間処理後、５０℃まで冷却し、ターボ分子ポンプにより真空にしてのち、高純度水素ガスを一定圧力まで導入して水素の吸着量を測定した。圧力と吸着量の関係を、１００ｋＰａまでの範囲で調べた（１回目）。その後、再度、ターボ分子ポンプにより真空にして４時間を保持して吸着水素を脱離させ、水素を再度導入し、圧力と吸着量の関係を、１００ｋＰａまでの範囲で調べた（２回目）。本発明の触媒Ａの等温吸着線を図４に示す。ここで、第１回目（□）と第２回目（●）の吸着等温線は同じであり、吸着する水素量と圧力の関係はいつも同一の関係を示した。一方、比較触媒Ｒの等温吸着線を図５に示す。ここでは、吸着および脱離する水素は、第１回目（□）と第２回目（●）では異なる関係を示した。すなわち、比較触媒Ｒでは、最初に吸着した水素の一部が強く吸着し（いわゆる水素のスピルオーバー現象）、脱離しにくい水素の存在を示唆する。白金触媒の状態は担体と金属との強い相互作用に影響されていると考えられる。一方、本発明の触媒Ａでは、水素分子の吸着脱離がはじめから完全に可逆的となり、担体に影響されない白金固有の特徴を有しており、本発明の製造方法により白金微粒子をあらかじめ製造し、その後担持触媒とした効果があらわれている。このように本発明によれば、水素の解離と再結合性において担体の影響の極めて少ない白金触媒が得られた。
(Example 3)
The comparative catalyst R prepared in Example 2 and the catalyst A of the present invention were subjected to hydrogen adsorption / desorption experiments using Belsorbpmax manufactured by Bell Japan. A sample of 0.1 g was filled in a quartz glass container. The sample was treated in helium at 400 ° C. for 30 minutes, cooled to 50 ° C., evacuated with a turbo molecular pump, and then high purity hydrogen gas was introduced to a constant pressure to measure the amount of hydrogen adsorbed. The relationship between the pressure and the amount of adsorption was examined in the range up to 100 kPa (first time). Thereafter, vacuum was again applied by a turbo molecular pump and the adsorbed hydrogen was desorbed by maintaining for 4 hours, hydrogen was introduced again, and the relationship between the pressure and the amount of adsorption was examined in the range up to 100 kPa (second time). The isothermal adsorption line of the catalyst A of the present invention is shown in FIG. Here, the adsorption isotherms of the first (□) and the second (●) were the same, and the relationship between the amount of adsorbed hydrogen and the pressure always showed the same relationship. On the other hand, the isothermal adsorption line of the comparative catalyst R is shown in FIG. Here, the hydrogen adsorbed and desorbed showed a different relationship between the first (□) and the second (●). That is, in the comparative catalyst R, part of the hydrogen adsorbed first is strongly adsorbed (so-called hydrogen spillover phenomenon), suggesting the presence of hydrogen that is difficult to desorb. It is considered that the state of the platinum catalyst is influenced by the strong interaction between the support and the metal. On the other hand, in the catalyst A of the present invention, the adsorption and desorption of hydrogen molecules is completely reversible from the beginning and has a characteristic characteristic of platinum that is not influenced by the support. Platinum fine particles are produced in advance by the production method of the present invention. Then, the effect as a supported catalyst appears. As described above, according to the present invention, a platinum catalyst having extremely little influence of the carrier in the dissociation and recombination of hydrogen was obtained.
（実施例４）
実施例２で調製した比較触媒Ｒと本発明の触媒Ａについて、排ガス浄化触媒特性について下記のような評価を行なった。粉末状触媒０．１ｇを固定床式触媒評価装置内のパイレックスガラス製評価用管に入れ装着した。触媒を酸素ガス５体積％含有するヘリウム気流中で６００℃まで昇温し３０分間保持して前処理した後、ヘリウム中で冷却した。次に酸素５体積％含むヘリウム気流中に、さらにヘリウムで希釈したプロピレンを３３４５ｐｐｍの濃度となるように混合し、流速２００ｍｌ／分にて触媒上に導入した。１０℃／分の昇温速度にて、触媒を加熱して、排気中のＣＯ２濃度をモニターした。また、新たに同じ触媒を同様に０．１ｇ装着し、触媒を水素５体積％含有するヘリウム気流中で６００℃まで昇温し３０分間保持して前処理後、以下、冷却からは上記と同様の操作により触媒活性を評価した。以上の評価実験により得られた、触媒の８０％浄化率を示す温度を表１に示す。白金微粒子は、前処理の条件により活性が影響をうけるが、同じ前処理で比較すると、本発明の白金触媒は、比較触媒に比べ、いずれもより低温で炭化水素の完全酸化活性を示しており、浄化触媒として優れた性能を有していることがわかる。
Example 4
The comparative catalyst R prepared in Example 2 and the catalyst A of the present invention were evaluated as follows for the exhaust gas purification catalyst characteristics. 0.1 g of the powdered catalyst was placed in a Pyrex glass evaluation tube in a fixed bed type catalyst evaluation apparatus. The catalyst was heated up to 600 ° C. in a helium stream containing 5% by volume of oxygen gas and kept for 30 minutes for pretreatment, and then cooled in helium. Next, propylene diluted with helium was further mixed to a concentration of 3345 ppm in a helium stream containing 5% by volume of oxygen, and introduced onto the catalyst at a flow rate of 200 ml / min. The catalyst was heated at a rate of temperature increase of 10 ° C./min, and the CO 2 concentration in the exhaust gas was monitored. In addition, 0.1 g of the same catalyst was newly mounted in the same manner, the temperature of the catalyst was increased to 600 ° C. in a helium stream containing 5% by volume of hydrogen and maintained for 30 minutes. The catalytic activity was evaluated by the following procedure. Table 1 shows temperatures obtained by the above evaluation experiments and showing an 80% purification rate of the catalyst. The activity of platinum fine particles is affected by the conditions of the pretreatment, but when compared with the same pretreatment, the platinum catalyst of the present invention shows complete oxidation activity of hydrocarbons at a lower temperature than the comparative catalyst. It can be seen that it has excellent performance as a purification catalyst.
本発明は、分散度の高い白金微粒子、分散度の高い白金微粒子担持触媒の製造方法、ならびに白金微粒子担持触媒を含む浄化触媒に利用することができる。 INDUSTRIAL APPLICABILITY The present invention can be used for platinum particles having a high degree of dispersion, a method for producing a platinum fine particle-supported catalyst having a high degree of dispersion, and a purification catalyst including a platinum fine particle-supported catalyst.
Claims (4)
An exhaust gas purifying catalyst comprising the platinum particle-supported catalyst according to claim 3.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014171969A (en) * | 2013-03-08 | 2014-09-22 | Toyoda Gosei Co Ltd | Method for manufacturing a particulate carrier |
| GB2535466A (en) * | 2015-02-16 | 2016-08-24 | Johnson Matthey Plc | Catalyst with stable nitric oxide (NO) oxidation performance |
| CN115867380A (en) * | 2021-07-01 | 2023-03-28 | 石福金属兴业株式会社 | Method for preparing electrode catalyst for fuel cell |
-
2011
- 2011-08-08 JP JP2011172506A patent/JP2013034937A/en not_active Withdrawn
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014171969A (en) * | 2013-03-08 | 2014-09-22 | Toyoda Gosei Co Ltd | Method for manufacturing a particulate carrier |
| GB2535466A (en) * | 2015-02-16 | 2016-08-24 | Johnson Matthey Plc | Catalyst with stable nitric oxide (NO) oxidation performance |
| GB2535644A (en) * | 2015-02-16 | 2016-08-24 | Johnson Matthey Plc | Catalyst with stable nitric oxide (NO) oxidation performance |
| GB2535644B (en) * | 2015-02-16 | 2017-08-16 | Johnson Matthey Plc | Oxidation catalyst with stable nitric oxide (NO) oxidation performance |
| CN107249734A (en) * | 2015-02-16 | 2017-10-13 | 庄信万丰股份有限公司 | Catalyst with stable nitric oxide (NO) oxidation susceptibility |
| US11103855B2 (en) | 2015-02-16 | 2021-08-31 | Johnson Matthey Public Limited Company | Catalyst with stable nitric oxide (NO) oxidation performance |
| CN115867380A (en) * | 2021-07-01 | 2023-03-28 | 石福金属兴业株式会社 | Method for preparing electrode catalyst for fuel cell |
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