JP5515635B2 - Noble metal-supported silicon carbide particles, production method thereof, catalyst containing the same, and production method thereof - Google Patents
Noble metal-supported silicon carbide particles, production method thereof, catalyst containing the same, and production method thereof Download PDFInfo
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- 239000002245 particle Substances 0.000 title claims description 215
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims description 200
- 229910010271 silicon carbide Inorganic materials 0.000 title claims description 200
- 239000003054 catalyst Substances 0.000 title claims description 113
- 238000004519 manufacturing process Methods 0.000 title claims description 35
- 229910000510 noble metal Inorganic materials 0.000 claims description 79
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 73
- 239000002923 metal particle Substances 0.000 claims description 64
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 64
- 239000012298 atmosphere Substances 0.000 claims description 37
- 239000000758 substrate Substances 0.000 claims description 27
- 230000001590 oxidative effect Effects 0.000 claims description 25
- 239000011164 primary particle Substances 0.000 claims description 24
- 238000010438 heat treatment Methods 0.000 claims description 17
- 238000000746 purification Methods 0.000 claims description 14
- 238000000354 decomposition reaction Methods 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- 238000002485 combustion reaction Methods 0.000 claims description 8
- 229930195733 hydrocarbon Natural products 0.000 claims description 5
- 150000002430 hydrocarbons Chemical class 0.000 claims description 5
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 239000011856 silicon-based particle Substances 0.000 claims description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 99
- 229910052697 platinum Inorganic materials 0.000 description 49
- 239000000843 powder Substances 0.000 description 32
- 238000000034 method Methods 0.000 description 24
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 20
- 230000003197 catalytic effect Effects 0.000 description 20
- 239000006185 dispersion Substances 0.000 description 20
- 239000000203 mixture Substances 0.000 description 18
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 16
- 239000012300 argon atmosphere Substances 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 16
- 239000007789 gas Substances 0.000 description 15
- 239000007864 aqueous solution Substances 0.000 description 13
- 230000007423 decrease Effects 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 11
- 230000007704 transition Effects 0.000 description 10
- 239000002253 acid Substances 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 8
- 229910052763 palladium Inorganic materials 0.000 description 8
- 238000012360 testing method Methods 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000012855 volatile organic compound Substances 0.000 description 6
- 239000006229 carbon black Substances 0.000 description 5
- 239000002243 precursor Substances 0.000 description 5
- 239000000523 sample Substances 0.000 description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 150000001299 aldehydes Chemical class 0.000 description 3
- 150000001336 alkenes Chemical class 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 229910052878 cordierite Inorganic materials 0.000 description 3
- 230000006866 deterioration Effects 0.000 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 description 3
- 239000002270 dispersing agent Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
- 239000010931 gold Substances 0.000 description 3
- 239000000383 hazardous chemical Substances 0.000 description 3
- 238000005984 hydrogenation reaction Methods 0.000 description 3
- 229910052741 iridium Inorganic materials 0.000 description 3
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 3
- 150000002576 ketones Chemical class 0.000 description 3
- 150000002604 lanthanum compounds Chemical class 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 description 3
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000010948 rhodium Substances 0.000 description 3
- 229910052703 rhodium Inorganic materials 0.000 description 3
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000012634 fragment Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002736 metal compounds Chemical class 0.000 description 2
- 150000005309 metal halides Chemical class 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 229910052762 osmium Inorganic materials 0.000 description 2
- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000013585 weight reducing agent Substances 0.000 description 2
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 241000255969 Pieris brassicae Species 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 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 1
- 150000001553 barium compounds Chemical class 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
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910001507 metal halide Inorganic materials 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000003961 organosilicon compounds Chemical class 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Description
本発明は、貴金属担持炭化ケイ素粒子とその製造方法及びそれを含有する触媒並びにその製造方法に関し、更に詳しくは、自動車の排ガス浄化触媒やカーボン燃焼触媒、燃料電池のアノード触媒、オレフィン、アルデヒド・ケトン、ニトロの水素化触媒、アンモニアの分解触媒、炭化水素の分解触媒、ホルムアルデヒド、揮発性有機化合物（ＶＯＣ）等の環境負荷物質の分解触媒等の気体浄化用触媒に用いて好適な貴金属担持炭化ケイ素粒子とその製造方法、及び、この炭化ケイ素粒子を含有する触媒並びにその製造方法に関するものである。 The present invention relates to noble metal-supported silicon carbide particles, a method for producing the same, a catalyst containing the same, and a method for producing the same, and more particularly, an exhaust gas purification catalyst for automobiles, a carbon combustion catalyst, an anode catalyst for fuel cells, an olefin, an aldehyde / ketone Noble metal-supported silicon carbide suitable for use in gas purification catalysts such as nitro hydrogenation catalysts, ammonia decomposition catalysts, hydrocarbon decomposition catalysts, decomposition catalysts for environmentally hazardous substances such as formaldehyde and volatile organic compounds (VOC) The present invention relates to particles, a method for producing the same, a catalyst containing the silicon carbide particles, and a method for producing the same.
従来、自動車の排ガス浄化触媒やカーボン燃焼触媒としては、反応面積を大きくとるためにハニカム形状とされた担体に、無機質粉体からなる触媒担持体を付着させ、さらに、反応に適した金属触媒を担持したものが使用されている。
この触媒担持体としては、排ガス浄化触媒用としてシリカ、高比表面積のγ−アルミナ等が、また、カーボン燃焼触媒用として酸化セリウムが、それぞれ用いられている。
ところで、最近注目を集めているクリーンディーゼルエンジンを搭載した自動車の場合、排ガスの温度が１０００℃を超えていることから、排ガス浄化触媒のハニカム状担体の温度も７００℃以上になることがある。このような高温下では、シリカは比表面積が急激に減少し、また、γ−アルミナはα−アルミナに相転移して比表面積が急激に減少するという問題点があった。
また、カーボン燃焼触媒でも同様に、酸化セリウムの比表面積の低下と共に、触媒機能が低下するという問題点があった。
Conventionally, as an exhaust gas purification catalyst or a carbon combustion catalyst for automobiles, a catalyst carrier made of inorganic powder is attached to a honeycomb-shaped carrier in order to increase the reaction area, and a metal catalyst suitable for the reaction is further provided. A supported one is used.
As the catalyst carrier, silica, high specific surface area γ-alumina, and the like are used for the exhaust gas purification catalyst, and cerium oxide is used for the carbon combustion catalyst.
By the way, in the case of an automobile equipped with a clean diesel engine which has been attracting attention recently, the temperature of the exhaust gas purification catalyst exceeds 1000 ° C., and therefore the temperature of the honeycomb carrier of the exhaust gas purification catalyst may be 700 ° C. or more. Under such a high temperature, the specific surface area of silica rapidly decreases, and γ-alumina undergoes a phase transition to α-alumina, resulting in a rapid decrease in specific surface area.
Similarly, the carbon combustion catalyst has a problem in that the catalytic function is lowered as the specific surface area of cerium oxide is lowered.
そこで、触媒担持体の比表面積の低下を防止するために、次のような様々な提案がなされている。
例えば、マグネシアを含むα−アルミナと、アルミニウム金属とを、接触または近接させて配置し、次いで、これらを強熱してマグネシウム及びアルミニウムを気化させ、これらマグネシウム及びアルミニウムを大気中にて酸化させてマグネシウムを含む遷移型アルミナの粉末を得る方法が提案されている（特許文献１）。この遷移型アルミナは、実質的に単結晶であり、１３００℃を超える高温においてもα−アルミナへ相変態することもない。
Therefore, in order to prevent a reduction in the specific surface area of the catalyst carrier, various proposals have been made as follows.
For example, α-alumina containing magnesia and aluminum metal are placed in contact with or in proximity to each other, and then these are ignited to vaporize magnesium and aluminum, and the magnesium and aluminum are oxidized in the atmosphere to form magnesium. There has been proposed a method for obtaining a transition-type alumina powder containing Pt (Patent Document 1). This transition type alumina is substantially single crystal and does not undergo phase transformation to α-alumina even at a high temperature exceeding 1300 ° C.
また、硫酸アルミニウムとバリウム化合物との混合溶液を加熱して熱分解することにより、耐熱性遷移アルミナを得る方法が提案されている（特許文献２）。この耐熱性遷移アルミナの１２００℃にて３時間加熱後のＢＥＴ比表面積は、６０ｍ２／ｇ以上である。
また、アルミナ水和物にランタン化合物を含浸し、乾燥した後、この乾燥したランタン含浸アルミナ水和物を気流式粉砕機にて粉砕し、３００℃以上からα−アルミナへの転移温度未満の温度にて仮焼する耐熱性遷移アルミナの製造方法も提案されている（特許文献３）。
In addition, a method for obtaining heat-resistant transition alumina by heating and thermally decomposing a mixed solution of aluminum sulfate and a barium compound has been proposed (Patent Document 2). The heat-resistant transition alumina has a BET specific surface area of 60 m 2 / g or more after heating at 1200 ° C. for 3 hours.
Further, after impregnating the hydrated alumina with a lanthanum compound and drying, the dried lanthanum-impregnated alumina hydrate is pulverized with an airflow type pulverizer, and a temperature lower than the transition temperature from 300 ° C. to α-alumina There has also been proposed a method for producing heat-resistant transition alumina that is preliminarily calcined in (Patent Document 3).
また、排ガス浄化触媒としては、アルミナおよびセリアを含む化合物から形成される基材と、この基材の表面に担持され、白金、パラジウム及びロジウムの中から選択される少なくとも１種以上の貴金属元素から形成される貴金属粒子とを有し、この貴金属粒子の表面またはその一部が金属酸化物層により被覆された排ガス浄化触媒が提案されている（特許文献４）。
さらに、触媒担持体としては、遷移アルミナ前駆物質と炭化ケイ素超微粉との混合物を加熱処理することにより、比表面積が２０ｍ２／ｇ以上の炭化ケイ素超微粉と遷移アルミナ粉末とを含有した混合粉体からなる触媒担持体の製造方法が提案されている（特許文献５）。
Further, as the exhaust gas purification catalyst, a base material formed from a compound containing alumina and ceria, and at least one kind of noble metal element supported on the surface of the base material and selected from platinum, palladium and rhodium are used. There has been proposed an exhaust gas purifying catalyst having a noble metal particle to be formed, and the surface of the noble metal particle or a part thereof being covered with a metal oxide layer (Patent Document 4).
Furthermore, as a catalyst carrier, a mixed powder containing silicon carbide ultrafine powder having a specific surface area of 20 m 2 / g or more and transition alumina powder by heat-treating a mixture of a transition alumina precursor and silicon carbide ultrafine powder. A method for producing a catalyst carrier comprising a body has been proposed (Patent Document 5).
ところで、上述した従来のアルミナ等を用いた触媒担持体では、確かに比表面積の低下を防止することはできるものの、マグネシウム及びアルミニウムを２０００℃以上の温度で気化させる場合には、製造コストが非常に高くなるという問題点があり、また、硫化物を原料とした場合には、大量の硫化物を処理する必要があるという問題点があり、また、ランタン化合物を用いた場合には、ランタン化合物が高価であり、製造コストが高くなってしまうという問題点があった。 By the way, in the catalyst carrier using the above-mentioned conventional alumina or the like, it is possible to surely prevent a decrease in specific surface area, but when magnesium and aluminum are vaporized at a temperature of 2000 ° C. or higher, the production cost is very high. In the case of using a sulfide as a raw material, there is a problem that it is necessary to treat a large amount of sulfide, and in the case of using a lanthanum compound, a lanthanum compound However, there is a problem that the manufacturing cost becomes high.
一方、貴金属粒子の表面またはその一部に金属酸化物層を被覆した排ガス浄化触媒では、全ての貴金属粒子の表面またはその一部に金属酸化物層を選択的に析出させることが難しく、触媒としての特性の劣化が避けられない、という問題点があった。
また、遷移アルミナ前駆物質と炭化ケイ素超微粉との混合物を加熱処理する場合には、遷移アルミナ前駆物質を原料としていたために、製造プロセスが複雑になり、製造コストが非常に高くなるという問題点があった。
また、アルミナ等に貴金属粒子を担持させた場合には、高温に晒されると触媒活性が低下するという問題点があった。
On the other hand, in the exhaust gas purification catalyst in which the surface or part of the noble metal particles is coated with the metal oxide layer, it is difficult to selectively deposit the metal oxide layer on the surface or part of all the noble metal particles. There was a problem that the deterioration of the characteristics of this was inevitable.
In addition, when heat-treating a mixture of a transition alumina precursor and silicon carbide ultrafine powder, since the transition alumina precursor is used as a raw material, the manufacturing process becomes complicated and the manufacturing cost becomes very high. was there.
Further, when noble metal particles are supported on alumina or the like, there is a problem that the catalytic activity is lowered when exposed to high temperatures.
本発明は、上記の課題を解決するためになされたものであって、高温での耐久性に優れ、しかも高温における貴金属粒子の触媒活性の低下を抑制することができる貴金属担持炭化ケイ素粒子とその製造方法及びそれを含有する触媒並びにその製造方法を提供することを目的とする。 The present invention has been made to solve the above-described problems, and has noble metal-supported silicon carbide particles that are excellent in durability at high temperatures and that can suppress a decrease in catalytic activity of the noble metal particles at high temperatures, and the same. It aims at providing a manufacturing method, a catalyst containing the same, and its manufacturing method.
本発明者等は、上記課題を解決するために鋭意検討を行った結果、炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を酸化性雰囲気中にて熱処理すれば、炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させることができ、その結果、７００℃以上の高温領域における耐久性を向上させることができ、担持された貴金属粒子の触媒活性が低下する虞も無いことを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventors have supported noble metal particles on the surface of the silicon carbide particles at 0.005 mol or more and 1 mol or less with respect to 1 mol of the silicon carbide, and then the noble metal. If the silicon carbide particles carrying the particles are heat-treated in an oxidizing atmosphere, a silicon oxide layer having a thickness of 0.1 nm or more and 30 nm or less can be generated on the surface of the silicon carbide particles. It has been found that the durability in the above high temperature range can be improved, and there is no possibility that the catalytic activity of the supported noble metal particles is lowered, and the present invention has been completed.
すなわち、本発明の貴金属担持炭化ケイ素粒子は、平均一次粒子径が０．００５μｍ以上かつ５μｍ以下の炭化ケイ素粒子の表面に、貴金属粒子を担持させた酸化ケイ素層を備え、前記酸化ケイ素層の厚みは０．１ｎｍ以上かつ３０ｎｍ以下であり、前記炭化ケイ素粒子に担持される前記貴金属粒子の量は、前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下であることを特徴とする。 That is, the noble metal-supported silicon carbide particles of the present invention comprise a silicon oxide layer having noble metal particles supported on the surface of silicon carbide particles having an average primary particle diameter of 0.005 μm or more and 5 μm or less, and the thickness of the silicon oxide layer Is 0.1 nm or more and 30 nm or less, and the amount of the noble metal particles supported on the silicon carbide particles is 0.005 mol or more and 1 mol or less with respect to 1 mol of the silicon carbide .
前記炭化ケイ素粒子の比表面積は１．０ｍ２／ｇ以上かつ４００ｍ２／ｇ以下であることが好ましい。
前記酸化ケイ素層は、前記炭化ケイ素粒子に前記貴金属粒子を担持させた後、酸化性雰囲気中にて酸化することにより、生成してなることが好ましい。
The silicon carbide particles preferably have a specific surface area of 1.0 m 2 / g or more and 400 m 2 / g or less.
The silicon oxide layer is preferably formed by supporting the noble metal particles on the silicon carbide particles and then oxidizing them in an oxidizing atmosphere.
本発明の貴金属担持炭化ケイ素粒子の製造方法は、炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子が担持された炭化ケイ素粒子を、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、前記炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させることを特徴とする。 In the method for producing noble metal-supported silicon carbide particles of the present invention, the noble metal particles are supported on the surface of the silicon carbide particles by 0.005 mol to 1 mol with respect to 1 mol of the silicon carbide, and then the silicon carbide on which the noble metal particles are supported. The particles are heat-treated in an oxidizing atmosphere at a temperature of 600 ° C. or more and 1000 ° C. or less to form a silicon oxide layer having a thickness of 0.1 nm or more and 30 nm or less on the surface of the silicon carbide particles. .
本発明の触媒は、ＤＰＦまたは自動車の排ガス浄化に用いられる触媒であって、本発明の貴金属担持炭化ケイ素粒子を含有してなることを特徴とする。
前記ＤＰＦに用いられる触媒は、カーボン燃焼触媒であることが好ましい。
前記自動車の排ガス浄化に用いられる触媒は、炭化水素の分解触媒であることが好ましい。
The catalyst of the present invention is a catalyst used for DPF or automobile exhaust gas purification, and is characterized by containing the noble metal-supported silicon carbide particles of the present invention.
The catalyst used for the DPF is preferably a carbon combustion catalyst.
The catalyst used for purifying the exhaust gas of the automobile is preferably a hydrocarbon decomposition catalyst.
本発明の第１の触媒の製造方法は、炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を基体上に付着させ、次いで、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、前記炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させることを特徴とする。 In the first catalyst production method of the present invention, noble metal particles are supported on the surface of silicon carbide particles by 0.005 mol to 1 mol with respect to 1 mol of silicon carbide, and then the silicon carbide particles having the noble metal particles supported thereon. Next, heat treatment is performed at a temperature of 600 ° C. to 1000 ° C. in an oxidizing atmosphere to form a silicon oxide layer having a thickness of 0.1 nm to 30 nm on the surface of the silicon carbide particles. It is characterized by making it.
本発明の第２の触媒の製造方法は、炭化ケイ素粒子を基体上に付着させ、次いで、前記炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を基体とともに、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、前記炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させることを特徴とする。 In the second method for producing a catalyst of the present invention, silicon carbide particles are deposited on a substrate, and then noble metal particles are supported on the surface of the silicon carbide particles by 0.005 mol or more and 1 mol or less with respect to 1 mol of the silicon carbide. and then the silicon carbide particles having supported thereon a noble metal particles with the substrate, in an oxidizing atmosphere, heat treatment at 600 ° C. or higher and 1000 ° C. or less of temperatures, the thickness on the surface of the silicon carbide particles 0.1nm or more and A silicon oxide layer having a thickness of 30 nm or less is generated.
本発明の貴金属担持炭化ケイ素粒子によれば、平均一次粒子径が０．００５μｍ以上かつ５μｍ以下の炭化ケイ素粒子の表面に、貴金属粒子を担持させた酸化ケイ素層を備え、酸化ケイ素層の厚みを０．１ｎｍ以上かつ３０ｎｍ以下とし、炭化ケイ素粒子に担持される貴金属粒子の量を炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下としたので、７００℃以上の高温領域における耐久性を向上させることができ、貴金属粒子の触媒活性の低下を防止することができる。したがって、高温時での信頼性を向上させることができる。 According to the noble metal-supported silicon carbide particles of the present invention, a silicon oxide layer having noble metal particles supported on the surface of silicon carbide particles having an average primary particle diameter of 0.005 μm or more and 5 μm or less is provided , and the thickness of the silicon oxide layer is increased. Since the amount of noble metal particles carried on the silicon carbide particles is 0.005 mol or more and 1 mol or less with respect to 1 mol of silicon carbide , the durability in a high temperature region of 700 ° C. or more is improved. And a decrease in the catalytic activity of the noble metal particles can be prevented. Therefore, reliability at high temperatures can be improved.
本発明の貴金属担持炭化ケイ素粒子の製造方法によれば、炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子が担持された炭化ケイ素粒子を、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、前記炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させるので、７００℃以上の高温領域における耐久性に優れ、しかも貴金属粒子の触媒活性が低下する虞も無い貴金属担持炭化ケイ素粒子を作製することができる。 According to the method for producing noble metal-supported silicon carbide particles of the present invention, the noble metal particles are supported on the surface of the silicon carbide particles by 0.005 mol to 1 mol with respect to 1 mol of the silicon carbide, and then the noble metal particles are supported. Since the silicon carbide particles are heat-treated in an oxidizing atmosphere at a temperature of 600 ° C. or more and 1000 ° C. or less to form a silicon oxide layer having a thickness of 0.1 nm or more and 30 nm or less on the surface of the silicon carbide particles. It is possible to produce noble metal-supported silicon carbide particles that are excellent in durability in a high temperature region of not less than 0 ° C. and that there is no possibility that the catalytic activity of the noble metal particles is reduced.
本発明の触媒によれば、ＤＰＦまたは自動車の排ガス浄化に用いられる触媒に、本発明の貴金属担持炭化ケイ素粒子を含有したので、７００℃以上の高温領域における耐久性を向上させることができ、貴金属粒子の触媒活性の低下を防止することができる。したがって、高温時における触媒としての信頼性を向上させることができる。 According to the catalyst of the present invention, the noble metal-supported silicon carbide particles of the present invention are contained in the catalyst used for DPF or automobile exhaust gas purification, so that the durability in a high temperature region of 700 ° C. or higher can be improved. A decrease in the catalytic activity of the particles can be prevented. Therefore, the reliability as a catalyst at a high temperature can be improved.
本発明の第１の触媒の製造方法によれば、炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を基体上に付着させ、次いで、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、前記炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させるので、７００℃以上の高温領域における耐久性に優れるとともに、貴金属粒子の触媒活性の低下の虞も無く、したがって、高温時での信頼性が向上した触媒を容易に作製することができる。 According to the first catalyst production method of the present invention, noble metal particles are supported on the surface of silicon carbide particles by 0.005 mol or more and 1 mol or less with respect to 1 mol of silicon carbide, and then the carbonization on which the noble metal particles are supported. Silicon particles are deposited on the substrate, then heat-treated in an oxidizing atmosphere at a temperature of 600 ° C. or more and 1000 ° C. or less, and a silicon oxide layer having a thickness of 0.1 nm or more and 30 nm or less on the surface of the silicon carbide particles since to produce, is excellent in durability in a high temperature range above 700 ° C., a fear of lowering of the catalytic activity of the noble metal particles without any, thus, it can be easily produced a catalyst with improved reliability at high temperatures .
本発明の第２の触媒の製造方法によれば、炭化ケイ素粒子を基体上に付着させ、次いで、前記炭化ケイ素粒子の表面に貴金属粒子を前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を基体とともに、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、前記炭化ケイ素粒子の表面に厚みが０．１ｎｍ以上かつ３０ｎｍ以下の酸化ケイ素層を生成させるので、７００℃以上の高温領域における耐久性に優れるとともに、貴金属粒子の触媒活性の低下の虞も無く、したがって、高温時での信頼性が向上した触媒を容易に作製することができる。 According to the second method for producing a catalyst of the present invention, silicon carbide particles are deposited on a substrate, and then noble metal particles on the surface of the silicon carbide particles are 0.005 mol or more and 1 mol or less with respect to 1 mol of the silicon carbide. is supported, then the silicon carbide particles having supported thereon a noble metal particles with the substrate, in an oxidizing atmosphere, heat treatment at 600 ° C. or higher and 1000 ° C. or less of the temperature, the thickness on the surface of the silicon carbide particles 0.1nm Since a silicon oxide layer having a thickness of 30 nm or less is generated , the catalyst has excellent durability in a high temperature region of 700 ° C. or higher, and there is no risk of a decrease in the catalytic activity of the noble metal particles. Can be easily manufactured.
本発明の貴金属担持炭化ケイ素粒子とその製造方法及びそれを含有する触媒並びにその製造方法を実施するための形態について説明する。なお、この形態は、発明の趣旨をより良く理解させるために具体的に説明するものであり、特に指定のない限り、本発明を限定するものではない。 The form for carrying out the noble metal carrying | support silicon carbide particle of this invention, its manufacturing method, the catalyst containing it, and its manufacturing method is demonstrated. This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.
［貴金属担持炭化ケイ素粒子及びその製造方法］
本実施形態の貴金属担持炭化ケイ素粒子は、平均一次粒子径が０．００５μｍ以上かつ５μｍ以下の炭化ケイ素粒子の表面に、貴金属粒子を担持させた酸化ケイ素層を備えた粒子である。
この貴金属担持炭化ケイ素粒子では、上記の酸化ケイ素層は、炭化ケイ素粒子の表面に、貴金属粒子を担持させた後に、酸化性雰囲気中にて酸化することにより、この炭化ケイ素粒子の表面に生成していることが好ましい。
[Noble metal-supported silicon carbide particles and production method thereof]
The noble metal-supported silicon carbide particles of the present embodiment are particles provided with a silicon oxide layer in which noble metal particles are supported on the surface of silicon carbide particles having an average primary particle diameter of 0.005 μm or more and 5 μm or less.
In this noble metal-supported silicon carbide particle, the silicon oxide layer is formed on the surface of the silicon carbide particle by supporting the noble metal particle on the surface of the silicon carbide particle and then oxidizing in an oxidizing atmosphere. It is preferable.
この炭化ケイ素粒子は、平均一次粒子径が０．００５μｍ以上かつ５μｍ以下、好ましくは０．０１μｍ以上かつ１．５μｍ以下、より好ましくは０．０２μｍ以上かつ１μｍ以下、さらに好ましくは０．０２μｍ以上かつ０．６μｍ以下である。
ここで、平均一次粒子径を上記の範囲に限定した理由は、平均一次粒子径が０．００５μｍ未満では、触媒粒子が焼結し易くなり、その結果、耐熱が低くなるからであり、一方、平均一次粒子径が５μｍを超えると、触媒活性種が酸化ケイ素層に被膜されてしまい、十分な活性が得られない虞があるからである。
The silicon carbide particles have an average primary particle size of 0.005 μm or more and 5 μm or less, preferably 0.01 μm or more and 1.5 μm or less, more preferably 0.02 μm or more and 1 μm or less, more preferably 0.02 μm or more and 0.6 μm or less.
Here, the reason why the average primary particle diameter is limited to the above range is that when the average primary particle diameter is less than 0.005 μm, the catalyst particles are easily sintered, and as a result, the heat resistance is lowered. This is because if the average primary particle diameter exceeds 5 μm, the catalytically active species are coated on the silicon oxide layer, and sufficient activity may not be obtained.
この炭化ケイ素粒子の比表面積は１．０ｍ２／ｇ以上かつ４００ｍ２／ｇ以下が好ましく、より好ましくは２ｍ２／ｇ以上かつ２００ｍ２／ｇ以下である。
ここで、比表面積を上記の範囲に限定した理由は、比表面積が１．０ｍ２／ｇ未満では、触媒としての反応面積が小さく、その機能を十分に引き出すことができなくなるからであり、一方、比表面積が４００ｍ２／ｇを超えると、触媒粒子が焼結し易くなり、耐熱性が低くなるからである。
The specific surface area of the silicon carbide particles is preferably 1.0 m 2 / g or more and 400 m 2 / g or less, more preferably 2 m 2 / g or more and 200 m 2 / g or less.
Here, the reason why the specific surface area is limited to the above range is that when the specific surface area is less than 1.0 m 2 / g, the reaction area as a catalyst is small, and the function cannot be sufficiently extracted. When the specific surface area exceeds 400 m 2 / g, the catalyst particles are easily sintered and the heat resistance is lowered.
上記の貴金属粒子は、貴金属として白金、金、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウムの群から選択される１種または２種以上を含有する粒子のことである。
この貴金属としては、特に、白金、金、パラジウム、イリジウムが、７００℃以上の高温領域における耐久性が高く、かつ触媒機能が高いので好ましい。
ここで、貴金属から銀を除いた理由は、銀を用いると、形成される酸化ケイ素層が結晶質となり、高温下で酸化が進むにつれて、炭化ケイ素粒子の構造が脆くなり、高温における耐久性が低下する虞があるからである。
Said noble metal particle is a particle | grain containing 1 type, or 2 or more types selected from the group of platinum, gold | metal | money, ruthenium, rhodium, palladium, osmium, and iridium as a noble metal.
As this noble metal, platinum, gold, palladium, and iridium are particularly preferable because they have high durability in a high temperature region of 700 ° C. or higher and high catalytic function.
Here, the reason for removing silver from the noble metal is that when silver is used, the formed silicon oxide layer becomes crystalline, and as the oxidation proceeds at a high temperature, the structure of the silicon carbide particles becomes brittle and the durability at a high temperature is increased. This is because there is a risk of lowering.
上記の炭化ケイ素粒子の表面に形成される酸化ケイ素層は、非晶質であることが好ましい。その理由は、非晶質酸化ケイ素（アモルファスシリカ）は、貴金属と固溶し易く、炭化ケイ素粒子の表面に安定して存在し易くなるからである。
これにより、貴金属粒子の焼結による粒成長を防止することができ、また、炭化ケイ素中への拡散も防止することができ、したがって、高温下においても優れた触媒特性を発揮することができる。
The silicon oxide layer formed on the surface of the silicon carbide particles is preferably amorphous. The reason is that amorphous silicon oxide (amorphous silica) is easily dissolved in a noble metal and is likely to exist stably on the surface of the silicon carbide particles.
As a result, grain growth due to sintering of noble metal particles can be prevented, and diffusion into silicon carbide can be prevented, and thus excellent catalytic properties can be exhibited even at high temperatures.
この酸化ケイ素層の厚みは、０．１ｎｍ以上かつ３０ｎｍ以下が好ましく、より好ましくは０．５ｎｍ以上かつ１０ｎｍ以下、さらに好ましくは０．５ｎｍ以上かつ５ｎｍ以下である。
ここで、酸化ケイ素層の厚みが０．１ｎｍ未満であると、貴金属の固溶できる量が不足する虞があり、一方、３０ｎｍを超えると、酸化ケイ素層の厚みが厚くなり過ぎて貴金属粒子の触媒機能を阻害する虞があり、また、酸化ケイ素層を形成するのに長時間を要するのみでなく、貴金属粒子の触媒機能を十分に発揮させるためには、貴金属粒子の量を増加させる必要があり、製造コストを押し上げる要因となる。
The thickness of the silicon oxide layer is preferably from 0.1 nm to 30 nm, more preferably from 0.5 nm to 10 nm, still more preferably from 0.5 nm to 5 nm.
Here, if the thickness of the silicon oxide layer is less than 0.1 nm, the amount capable of dissolving the noble metal may be insufficient. On the other hand, if the thickness exceeds 30 nm, the thickness of the silicon oxide layer becomes too thick, There is a risk of hindering the catalytic function, and not only it takes a long time to form the silicon oxide layer, but in order to fully exert the catalytic function of the noble metal particles, it is necessary to increase the amount of the noble metal particles. Yes, it will increase the manufacturing cost.
上記の炭化ケイ素粒子に担持される貴金属粒子の量は、炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下が好ましく、より好ましくは０．０１ｍｏｌ以上かつ０．５ｍｏｌ以下、さらに好ましくは０．０１ｍｏｌ以上かつ０．１ｍｏｌ以下である。
貴金属粒子の量が０．０１ｍｏｌ未満であると、触媒機能の発現及び耐久性が低下する虞があり、一方、１ｍｏｌを超えると、酸化ケイ素層が形成し難くなる虞がある。
The amount of the noble metal particles supported on the silicon carbide particles is preferably 0.005 mol or more and 1 mol or less, more preferably 0.01 mol or more and 0.5 mol or less, and still more preferably 0.01 mol with respect to 1 mol of silicon carbide. Above and below 0.1 mol.
If the amount of the noble metal particles is less than 0.01 mol, the expression and durability of the catalyst function may be reduced, whereas if it exceeds 1 mol, the silicon oxide layer may be difficult to form.
次に、本実施形態の貴金属担持炭化ケイ素粒子の製造方法について説明する。
まず、一次粒子径が０．００５μｍ以上かつ５μｍ以下の炭化ケイ素粒子を用意する。
この炭化ケイ素粒子の製造方法としては、特に限定されるものではなく、アチソン法、シリカ還元法、シリコン炭化法等の工業的製法を挙げることができる。
Next, the manufacturing method of the noble metal carrying | support silicon carbide particle of this embodiment is demonstrated.
First, silicon carbide particles having a primary particle diameter of 0.005 μm or more and 5 μm or less are prepared.
The method for producing the silicon carbide particles is not particularly limited, and examples thereof include industrial production methods such as the Atchison method, the silica reduction method, and the silicon carbonization method.
特に、ナノサイズの炭化ケイ素粒子を得る方法としては、非酸化性雰囲気下にて、高温、高活性を有し、高速冷却プロセスの導入が容易である熱プラズマを利用した熱プラズマ法が挙げられる。
この方法は、平均粒子径が５ｎｍ〜１００ｎｍ程度の結晶性に優れた炭化ケイ素ナノ粒子を製造する方法として有用であり、高純度の原料を選択することにより、不純物の含有量が極めて少ない炭化ケイ素ナノ粒子を得ることが可能である。
In particular, as a method for obtaining nano-sized silicon carbide particles, there is a thermal plasma method using thermal plasma that has high temperature and high activity in a non-oxidizing atmosphere and that can easily introduce a high-speed cooling process. .
This method is useful as a method for producing silicon carbide nanoparticles having an average particle diameter of about 5 nm to 100 nm and excellent in crystallinity. By selecting a high-purity raw material, silicon carbide having an extremely small impurity content is used. Nanoparticles can be obtained.
また、前駆体（プレカーサ）法も挙げることができる。この方法は、有機ケイ素化合物、ケイ素ゾル、ケイ酸ヒドロゲル等のケイ素を含む物質と、フェノール樹脂等の炭素を含む物質と、炭化ケイ素の粒成長を抑制するリチウム等の金属化合物とを含む混合物を、非酸化雰囲気下にて焼成することにより、炭化ケイ素粒子を得る方法である。 Moreover, the precursor (precursor) method can also be mentioned. In this method, a mixture containing a silicon-containing substance such as an organosilicon compound, silicon sol, or silicic acid hydrogel, a carbon-containing substance such as a phenol resin, and a metal compound such as lithium that suppresses grain growth of silicon carbide is obtained. In this method, silicon carbide particles are obtained by firing in a non-oxidizing atmosphere.
この炭化ケイ素粒子は、製造方法によっては表面に炭化ケイ素以外の成分が付着する場合があるが、この場合には、表面に貴金属粒子を担持させる前に、予め、炭化ケイ素粒子の表面の付着物を除去しておいてもよい。
付着物の除去方法としては、炭化ケイ素粒子を還元性雰囲気下または不活性雰囲気下にて熱処理することにより付着物を除去する方法、炭化ケイ素粒子の表面をフッ酸、フッ化アンモニウム、硝酸の群から選択される１種または２種以上を含む溶液を用いて溶解することにより、付着物を除去する方法等が挙げられる。
Depending on the production method, the silicon carbide particles may have components other than silicon carbide attached to the surface. In this case, before the noble metal particles are supported on the surface, the silicon carbide particles are previously deposited on the surface of the silicon carbide particles. May be removed.
As a method for removing the deposit, a method of removing the deposit by heat-treating the silicon carbide particles in a reducing atmosphere or an inert atmosphere, and the surface of the silicon carbide particles is a group of hydrofluoric acid, ammonium fluoride, and nitric acid. Examples include a method of removing deposits by dissolving using a solution containing one or more selected from:
次いで、炭化ケイ素粒子の表面に貴金属粒子を担持させる。
貴金属粒子の担持方法としては、特に限定されるものではなく、任意の方法でよい。
例えば、炭化ケイ素粒子を、白金、金、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウムの群から選択される１種または２種以上の貴金属化合物を含む水溶液中に懸濁させることにより、この貴金属化合物を炭化ケイ素粒子の表面に担持させ、次いで、１００℃以上かつ２５０℃以下の温度にて熱処理する方法、あるいは、炭化ケイ素粒子と貴金属の塩化物、硫化物、硝酸塩等の貴金属ハロゲン化物または貴金属塩を含む水溶液を添加し、この貴金属ハロゲン化物または貴金属塩を炭化ケイ素粒子の表面に担持させ、次いで、１００℃以上かつ２５０℃以下の温度にて熱処理する方法等が挙げられる。
Next, noble metal particles are supported on the surface of the silicon carbide particles.
The method for supporting the noble metal particles is not particularly limited, and any method may be used.
For example, by suspending silicon carbide particles in an aqueous solution containing one or more kinds of noble metal compounds selected from the group of platinum, gold, ruthenium, rhodium, palladium, osmium, and iridium, A method in which silicon carbide particles are supported on the surface and then heat-treated at a temperature of 100 ° C. or more and 250 ° C. or less, or noble metal halides or noble metal salts such as chlorides, sulfides and nitrates of silicon carbide particles and noble metals. Examples include a method of adding an aqueous solution containing the precious metal halide or precious metal salt to the surface of the silicon carbide particles and then heat-treating at a temperature of 100 ° C. or higher and 250 ° C. or lower.
次いで、この貴金属粒子が担持された炭化ケイ素粒子を、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、この炭化ケイ素粒子の表面に酸化ケイ素層を生成させる。
酸化性雰囲気としては、酸素または水分を含む雰囲気であれば良く、大気、減圧下の酸素雰囲気、加圧下の酸素雰囲気等が挙げられ、経済性を考慮すると大気中の雰囲気が最も好ましい。
Next, the silicon carbide particles on which the noble metal particles are supported are heat-treated in an oxidizing atmosphere at a temperature of 600 ° C. or higher and 1000 ° C. or lower to form a silicon oxide layer on the surfaces of the silicon carbide particles.
The oxidizing atmosphere may be an atmosphere containing oxygen or moisture, and examples thereof include air, an oxygen atmosphere under reduced pressure, an oxygen atmosphere under pressure, and the like. In consideration of economy, the atmosphere in the air is most preferable.
熱処理の温度は、６００℃以上かつ１０００℃以下が好ましく、より好ましくは６５０℃以上かつ１０００℃以下、さらに好ましくは７００℃以上かつ９００℃以下である。
熱処理の時間は、熱処理の温度に依存するために必ずしも特定はできないが、０．５時間以上かつ３６時間以下が好ましく、より好ましくは４時間以上かつ１２時間以下である。
The heat treatment temperature is preferably 600 ° C. or higher and 1000 ° C. or lower, more preferably 650 ° C. or higher and 1000 ° C. or lower, and further preferably 700 ° C. or higher and 900 ° C. or lower.
The heat treatment time is not necessarily specified because it depends on the temperature of the heat treatment, but it is preferably 0.5 hours or more and 36 hours or less, more preferably 4 hours or more and 12 hours or less.
ここで、熱処理の温度を６００℃以上かつ１０００℃以下と限定した理由は、６００℃未満では、炭化ケイ素粒子の表面の酸化が不十分で、酸化ケイ素の生成が不十分になるからであり、一方、１０００℃を超えると、貴金属粒子の焼結や凝集が生じてしまい、貴金属粒子自体が有する触媒機能が低下してしまうからである。
なお、この熱処理は、炭化ケイ素粒子の表面を酸化することで、この表面に酸化ケイ素を生成させれば良いのであって、炭化ケイ素粒子全体を酸化する必要はない。したがって、必ずしも高温・長時間の熱処理を行う必要はない。
Here, the reason why the temperature of the heat treatment is limited to 600 ° C. or more and 1000 ° C. or less is that if the temperature is less than 600 ° C., the surface of the silicon carbide particles is insufficiently oxidized, and the generation of silicon oxide becomes insufficient. On the other hand, when the temperature exceeds 1000 ° C., sintering and aggregation of the noble metal particles occur, and the catalytic function of the noble metal particles themselves decreases.
In this heat treatment, the surface of the silicon carbide particles is oxidized to generate silicon oxide on the surface, and the entire silicon carbide particles need not be oxidized. Therefore, it is not always necessary to perform heat treatment for a long time at a high temperature.
以上説明したように、本実施形態の貴金属担持炭化ケイ素粒子によれば、炭化ケイ素粒子の表面に、酸化ケイ素を生成させたので、７００℃以上の高温領域における耐久性を向上させることができ、担持された貴金属粒子の触媒活性の低下を防止することができる。したがって、高温時での信頼性を向上させることができる。 As described above, according to the noble metal-supported silicon carbide particles of the present embodiment, since silicon oxide was generated on the surface of the silicon carbide particles, durability in a high temperature region of 700 ° C. or higher can be improved. A decrease in the catalytic activity of the supported noble metal particles can be prevented. Therefore, reliability at high temperatures can be improved.
本実施形態の貴金属担持炭化ケイ素粒子の製造方法によれば、７００℃以上の高温領域における耐久性を向上させることができ、担持された貴金属触媒粒子の活性低下を防止することができる貴金属担持炭化ケイ素粒子を、容易に作製することができる。
したがって、高温時での信頼性に優れた貴金属担持炭化ケイ素粒子を提供することができる。
According to the method for producing noble metal-supported silicon carbide particles of the present embodiment, it is possible to improve durability in a high temperature region of 700 ° C. or higher, and to prevent a decrease in activity of the supported noble metal catalyst particles. Silicon particles can be easily produced.
Accordingly, it is possible to provide noble metal-supported silicon carbide particles having excellent reliability at high temperatures.
［触媒及びその製造方法］
本実施形態の触媒は、本実施形態の貴金属担持炭化ケイ素粒子を含有してなる触媒である。この触媒としては、自動車の排ガス浄化触媒、カーボン燃焼触媒、燃料電池のアノード触媒、オレフィン、アルデヒド・ケトン、ニトロの水素化触媒、アンモニアの分解触媒、炭化水素の分解触媒、ホルムアルデヒド、揮発性有機化合物（ＶＯＣ）等の環境負荷物質の分解触媒等が挙げられる。なお、この触媒中における貴金属担持炭化ケイ素粒子の含有量や含有方法には特段の制限はなく、触媒の用途や形状により、任意に選択することが可能である。
[Catalyst and production method thereof]
The catalyst of the present embodiment is a catalyst containing the noble metal-supported silicon carbide particles of the present embodiment. This catalyst includes automobile exhaust gas purification catalyst, carbon combustion catalyst, fuel cell anode catalyst, olefin, aldehyde / ketone, nitro hydrogenation catalyst, ammonia decomposition catalyst, hydrocarbon decomposition catalyst, formaldehyde, volatile organic compounds Examples include decomposition catalysts for environmentally hazardous substances such as (VOC). In addition, there is no special restriction | limiting in content and the content method of the noble metal carrying | support silicon carbide particle in this catalyst, It is possible to select arbitrarily according to the use and shape of a catalyst.
この触媒では、炭化ケイ素粒子の表面に貴金属粒子を担持させるとともに、酸化ケイ素層を形成したので、７００℃以上の高温領域における耐久性を向上させることができ、担持された貴金属粒子の触媒活性の低下を防止することができる。したがって、高温時での高い信頼性が要求されるハニカム構造体のＤＰＦ（Desel Particulate Filter）、自動車の排ガス浄化触媒、カーボン燃焼触媒、燃料電池のアノード触媒、オレフィン、アルデヒド・ケトン、ニトロの水素化触媒、アンモニアの分解触媒、炭化水素の分解触媒、ホルムアルデヒド、揮発性有機化合物（ＶＯＣ）等の環境負荷物質の分解触媒等への適用が可能である。 In this catalyst, since the noble metal particles are supported on the surface of the silicon carbide particles and the silicon oxide layer is formed, the durability in a high temperature region of 700 ° C. or more can be improved, and the catalytic activity of the supported noble metal particles can be improved. A decrease can be prevented. Therefore, DPF (Desel Particulate Filter) for honeycomb structures that require high reliability at high temperatures, automobile exhaust gas purification catalyst, carbon combustion catalyst, fuel cell anode catalyst, olefin, aldehyde / ketone, nitro hydrogenation The present invention can be applied to catalysts, decomposition catalysts for ammonia, decomposition catalysts for hydrocarbons, decomposition catalysts for environmentally hazardous substances such as formaldehyde and volatile organic compounds (VOC).
本実施形態の触媒は、本実施形態の貴金属担持炭化ケイ素粒子を含有する分散液を作製し、この分散液を基体上に塗布し、乾燥、熱処理することにより、作製することができる。
この触媒は、多孔質膜状であるから、触媒特性に優れている。
The catalyst of this embodiment can be prepared by preparing a dispersion containing the noble metal-supported silicon carbide particles of this embodiment, applying this dispersion on a substrate, drying, and heat-treating.
Since this catalyst is in the form of a porous membrane, it has excellent catalytic properties.
本実施形態の触媒の製造方法としては、以下の製造方法も挙げられる。
一つは、炭化ケイ素粒子の表面に貴金属粒子を担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を基体上に付着させ、次いで、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、炭化ケイ素粒子の表面に酸化ケイ素層を生成させる方法である。
Examples of the method for producing the catalyst of the present embodiment also include the following production methods.
One is to support the noble metal particles on the surface of the silicon carbide particles, and then adhere the silicon carbide particles supporting the noble metal particles on the substrate, and then, in an oxidizing atmosphere, at 600 ° C. or more and 1000 ° C. or less. In this method, heat treatment is performed at a temperature to form a silicon oxide layer on the surface of the silicon carbide particles.
この場合、触媒の形状を膜状または塊状とするには、貴金属粒子を担持させた炭化ケイ素粒子を基体上に付着させた後、アルゴン雰囲気等の不活性雰囲気下にて熱処理して、炭化ケイ素粒子同士を部分焼結させた後、酸化性雰囲気中にて熱処理することが好ましい。 In this case, in order to make the shape of the catalyst into a film or a lump, silicon carbide particles supporting noble metal particles are deposited on the substrate, and then heat-treated in an inert atmosphere such as an argon atmosphere. It is preferable that the particles are partially sintered and then heat-treated in an oxidizing atmosphere.
もう一つは、炭化ケイ素粒子を基体上に付着させ、次いで、炭化ケイ素粒子の表面に貴金属粒子を担持させ、次いで、この貴金属粒子を担持させた炭化ケイ素粒子を基体とともに、酸化性雰囲気中、６００℃以上かつ１０００℃以下の温度にて熱処理し、炭化ケイ素粒子の表面に酸化ケイ素層を生成させる方法である。 The other is to deposit silicon carbide particles on the substrate, and then support the noble metal particles on the surface of the silicon carbide particles, and then the silicon carbide particles supporting the noble metal particles together with the substrate in an oxidizing atmosphere. In this method, heat treatment is performed at a temperature of 600 ° C. or more and 1000 ° C. or less to form a silicon oxide layer on the surface of the silicon carbide particles.
この場合、触媒の形状を膜状または塊状とするには、炭化ケイ素粒子を基体上に付着させた後、アルゴン雰囲気等の不活性雰囲気下にて熱処理して、炭化ケイ素粒子同士を部分焼結させ、その後、この炭化ケイ素粒子に貴金属粒子を担持させ、酸化性雰囲気中にて熱処理する方法、または、炭化ケイ素粒子を基体上に付着させた後、この炭化ケイ素粒子に貴金属粒子を担持させ、次いで、アルゴン雰囲気等の不活性雰囲気下にて熱処理して、炭化ケイ素粒子同士を部分焼結させ、その後、酸化性雰囲気中にて熱処理する方法が好ましい。 In this case, in order to make the shape of the catalyst into a film or a lump, the silicon carbide particles are deposited on the substrate and then heat-treated in an inert atmosphere such as an argon atmosphere to partially sinter the silicon carbide particles. Then, the noble metal particles are supported on the silicon carbide particles and heat treated in an oxidizing atmosphere, or after the silicon carbide particles are deposited on the substrate, the noble metal particles are supported on the silicon carbide particles, Next, a method in which heat treatment is performed in an inert atmosphere such as an argon atmosphere to partially sinter the silicon carbide particles, and then heat treatment in an oxidizing atmosphere is preferable.
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、本発明はこれらの実施例によって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 by these Examples.
「実施例１」
炭化ケイ素粒子（比表面積：１００ｍ２／ｇ、平均一次粒子径：０．０２μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．００７ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 1"
10 g of silicon carbide particles (specific surface area: 100 m 2 / g, average primary particle size: 0.02 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 0.007 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中７００℃にて５時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例１の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 700 ° C. for 5 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. Thus, catalyst particles of Example 1 having a silicon oxide layer having platinum particles supported on the surface were obtained.
「実施例２」
炭化ケイ素粒子（比表面積：４０ｍ２／ｇ、平均一次粒子径：０．０５μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．０１５ｍｏｌとなるようにジニトロジアミン白金水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 2"
10 g of silicon carbide particles (specific surface area: 40 m 2 / g, average primary particle size: 0.05 μm) were dispersed in 90 g of water. Next, a dinitrodiamine platinum aqueous solution was added to the dispersion and mixed so that platinum was 0.015 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中８５０℃にて１１時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例２の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 850 ° C. for 11 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. As a result, catalyst particles of Example 2 having a silicon oxide layer carrying platinum particles on the surface were obtained.
図１は、この触媒粒子を７００℃にて３０時間熱処理した後、電界放射型透過電子顕微鏡（ＦＥ−ＴＥＭ）JEM-2100（日本電子(株)社製）を用いて、この触媒粒子における白金粒子の担持状態を観察した電界放射型透過電子顕微鏡像（ＦＥ−ＴＥＭ像）である。
この図１によれば、一次粒子径が５０ｎｍ程度の炭化ケイ素粒子の表面に、１０ｎｍ程度の比較的大きな白い斑点状の白金粒子、及び５ｎｍ程度の比較的小さな白い斑点状の白金粒子が付着していることが分かった。
FIG. 1 shows that after the catalyst particles were heat-treated at 700 ° C. for 30 hours, platinum in the catalyst particles was measured using a field emission transmission electron microscope (FE-TEM) JEM-2100 (manufactured by JEOL Ltd.). It is the field emission type | mold transmission electron microscope image (FE-TEM image) which observed the support state of particle | grains.
According to FIG. 1, relatively large white spotted platinum particles of about 10 nm and relatively small white spotted platinum particles of about 5 nm adhere to the surface of silicon carbide particles having a primary particle diameter of about 50 nm. I found out.
「実施例３」
炭化ケイ素粒子（比表面積：２０ｍ２／ｇ、平均一次粒子径：０．１μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．１ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 3"
10 g of silicon carbide particles (specific surface area: 20 m 2 / g, average primary particle size: 0.1 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 0.1 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中７００℃にて５時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例３の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 700 ° C. for 5 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. As a result, catalyst particles of Example 3 having a silicon oxide layer carrying platinum particles on the surface were obtained.
「実施例４」
炭化ケイ素粒子（比表面積：４ｍ２／ｇ、平均一次粒子径：０．５μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．０１ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
Example 4
10 g of silicon carbide particles (specific surface area: 4 m 2 / g, average primary particle size: 0.5 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 0.01 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中８００℃にて４時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例４の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 800 ° C. for 4 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. Thus, catalyst particles of Example 4 having a silicon oxide layer having platinum particles supported on the surface were obtained.
「実施例５」
炭化ケイ素粒子（比表面積：１．５ｍ２／ｇ、平均一次粒子径：１．２μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．０５ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 5"
10 g of silicon carbide particles (specific surface area: 1.5 m 2 / g, average primary particle size: 1.2 μm) were dispersed in 90 g of water. Next, an aqueous chloroplatinic acid solution was added to and mixed with this dispersion so that platinum was 0.05 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中８５０℃にて４時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例５の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 850 ° C. for 4 hours in the air, thereby forming a silicon oxide layer on the surface of the silicon carbide particles. Thus, catalyst particles of Example 5 having a silicon oxide layer with platinum particles supported on the surface were obtained.
「実施例６」
炭化ケイ素粒子（比表面積：６０ｍ２／ｇ、平均一次粒子径：０．０３μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．５ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 6"
10 g of silicon carbide particles (specific surface area: 60 m 2 / g, average primary particle size: 0.03 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 0.5 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体２０質量部と平均一次粒子径５μｍの炭化ケイ素粒子８０質量部を混合し、次いで、この混合粉体１０ｇを水９０ｇ中に分散し、混合物を得た。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥した。
このようにして得られた粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中８５０℃にて８時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例６の触媒粒子を得た。
Next, 20 parts by mass of the powder and 80 parts by mass of silicon carbide particles having an average primary particle size of 5 μm were mixed, and then 10 g of the mixed powder was dispersed in 90 g of water to obtain a mixture. Subsequently, this mixture was evaporated to dryness and pulverized using an evaporator, and then dried at 150 ° C. for 12 hours.
The powder thus obtained was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 850 ° C. for 8 hours in the air, thereby forming a silicon oxide layer on the surface of the silicon carbide particles. Formed. Thus, catalyst particles of Example 6 having a silicon oxide layer having platinum particles supported on the surface were obtained.
「実施例７」
炭化ケイ素粒子（比表面積：４０ｍ２／ｇ、平均一次粒子径：０．０５μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対してパラジウムが０．０１ｍｏｌとなるようにジニトロジアミンパラジウム水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面にパラジウムが付着した粉体を得た。
"Example 7"
10 g of silicon carbide particles (specific surface area: 40 m 2 / g, average primary particle size: 0.05 μm) were dispersed in 90 g of water. Next, an aqueous dinitrodiamine palladium solution was added to and mixed with this dispersion so that the palladium was 0.01 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator, and then dried at 150 ° C. for 12 hours to obtain a powder in which palladium adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中８５０℃にて６時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面にパラジウム粒子を担持させた酸化ケイ素層を備えた実施例７の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 850 ° C. for 6 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. As a result, catalyst particles of Example 7 having a silicon oxide layer with palladium particles supported on the surface were obtained.
「実施例８」
炭化ケイ素粒子（比表面積：６０ｍ２／ｇ、平均一次粒子径：０．０３μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．０１ｍｏｌとなるようにジニトロジアミン白金水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 8"
10 g of silicon carbide particles (specific surface area: 60 m 2 / g, average primary particle size: 0.03 μm) were dispersed in 90 g of water. Next, a dinitrodiamine platinum aqueous solution was added to and mixed with this dispersion so that platinum was 0.01 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中６００℃にて４時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた実施例８の触媒粒子を得た。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 600 ° C. for 4 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. Thus, catalyst particles of Example 8 having a silicon oxide layer with platinum particles supported on the surface were obtained.
次いで、この触媒粒子をカルボン酸系分散剤と共に純水中に分散し、固形分の濃度が６質量％の分散液を得た。次いで、この分散液にコージエライト製ハニカム基材（２ｍｉｌ／９００ｃｐｓ）を浸漬させた後、１１０℃にて乾燥し、表面に白金粒子を担持させた酸化ケイ素層を備えた炭化ケイ素粒子を、ハニカム基材に単位体積当たり１８g／Ｌとなるように付着させた。これにより、ハニカム基材上に膜厚２１μｍで平均気孔径が０．０８μｍの多孔質膜を形成した実施例８のハニカム構造体を得た。 Next, the catalyst particles were dispersed in pure water together with a carboxylic acid dispersant to obtain a dispersion having a solid content of 6% by mass. Next, a cordierite honeycomb substrate (2 mil / 900 cps) was immersed in this dispersion, and then dried at 110 ° C., and silicon carbide particles provided with a silicon oxide layer having platinum particles supported on the surface were coated with honeycomb substrate. It was made to adhere to a material so that it might become 18 g / L per unit volume. Thus, a honeycomb structure of Example 8 in which a porous film having a film thickness of 21 μm and an average pore diameter of 0.08 μm was formed on the honeycomb substrate was obtained.
「実施例９」
炭化ケイ素粒子（比表面積：４ｍ２／ｇ、平均一次粒子径：０．５μｍ）を、カルボン酸系分散剤と共に純水中に分散させ、固形分の濃度が４質量％の分散液を得た。次いで、この分散液にコージエライト製ハニカム基材（２ｍｉｌ／９００ｃｐｓ）を浸漬させた後、１１０℃にて乾燥し、この炭化ケイ素粒子を、ハニカム基材に単位体積当たり１２ｇ／Ｌとなるように付着させた。これにより、表面に膜厚１０μｍで平均気孔径が０．２２μｍの多孔質膜を形成したハニカム基材を得た。
"Example 9"
Silicon carbide particles (specific surface area: 4 m 2 / g, average primary particle size: 0.5 μm) were dispersed in pure water together with a carboxylic acid dispersant to obtain a dispersion having a solid content of 4% by mass. . Next, a cordierite honeycomb substrate (2 mil / 900 cps) was immersed in this dispersion, and then dried at 110 ° C., and the silicon carbide particles were adhered to the honeycomb substrate so as to be 12 g / L per unit volume. I let you. As a result, a honeycomb substrate on which a porous film having a film thickness of 10 μm and an average pore diameter of 0.22 μm was formed was obtained.
次いで、このハニカム基材をジニトロジアミン白金水溶液に浸漬し、１５０℃にて１２時間乾燥して、炭化ケイ素粒子に、炭化ケイ素１ｍｏｌに対して白金０．１ｍｏｌを担持した。
次いで、このハニカム基材を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中６００℃にて６時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた炭化ケイ素粒子からなる多孔質触媒層を形成した実施例９のハニカム構造体を得た。
Next, this honeycomb substrate was immersed in a dinitrodiamine platinum aqueous solution and dried at 150 ° C. for 12 hours, and 0.1 mol of platinum was supported on silicon carbide particles with respect to 1 mol of silicon carbide.
Next, the honeycomb base material was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 600 ° C. for 6 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. As a result, the honeycomb structure of Example 9 in which the porous catalyst layer made of silicon carbide particles provided with the silicon oxide layer having platinum particles supported on the surface was formed was obtained.
「実施例１０」
炭化ケイ素粒子（比表面積：４ｍ２／ｇ、平均一次粒子径：０．５μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．０１ｍｏｌとなるようにジニトロジアミン白金水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素粒子の表面に白金が付着した粉体を得た。
"Example 10"
10 g of silicon carbide particles (specific surface area: 4 m 2 / g, average primary particle size: 0.5 μm) were dispersed in 90 g of water. Next, a dinitrodiamine platinum aqueous solution was added to and mixed with this dispersion so that platinum was 0.01 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator and then dried at 150 ° C. for 12 hours to obtain a powder in which platinum adhered to the surface of silicon carbide particles.
次いで、この粉体を分散剤と共に純水中に分散させ、固形分の濃度が６質量％の分散液を得た。次いで、この分散液にコージエライト製ハニカム基材（２ｍｉｌ／９００ｃｐｓ）を浸漬させた後、１１０℃にて乾燥し、表面に白金粒子を付着させた炭化ケイ素粒子を、ハニカム基材に単位体積当たり１８g／Ｌとなるように付着させた。これにより、表面に膜厚２１μｍで平均気孔径が０．２２μｍの多孔質膜を形成したハニカム基材を得た。 Next, this powder was dispersed in pure water together with a dispersant to obtain a dispersion having a solid content of 6% by mass. Next, a cordierite honeycomb substrate (2 mil / 900 cps) was immersed in this dispersion, and then dried at 110 ° C., and 18 g of silicon carbide particles having platinum particles attached to the surface thereof were applied to the honeycomb substrate per unit volume. It was made to adhere so that it might become / L. As a result, a honeycomb substrate on which a porous film having a film thickness of 21 μm and an average pore diameter of 0.22 μm was formed was obtained.
次いで、このハニカム基材を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中６００℃にて６時間、熱処理することにより、炭化ケイ素粒子の表面に酸化ケイ素層を形成した。これにより、表面に白金粒子を担持させた酸化ケイ素層を備えた炭化ケイ素粒子からなる多孔質触媒層を形成した実施例１０のハニカム構造体を得た。 Next, the honeycomb base material was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 600 ° C. for 6 hours in the air to form a silicon oxide layer on the surface of the silicon carbide particles. As a result, the honeycomb structure of Example 10 in which the porous catalyst layer composed of silicon carbide particles provided with the silicon oxide layer having platinum particles supported on the surface was formed was obtained.
「比較例１」
炭化ケイ素粒子（比表面積：５０ｍ２／ｇ、平均一次粒子径：０．０４μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が１．５ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素の表面に白金が付着した粉体を得た。
"Comparative Example 1"
10 g of silicon carbide particles (specific surface area: 50 m 2 / g, average primary particle size: 0.04 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 1.5 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator, and then dried at 150 ° C. for 12 hours to obtain a powder having platinum adhered to the surface of silicon carbide.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中８５０℃にて８時間、熱処理したが、この炭化ケイ素粒子の表面には酸化ケイ素層を形成することができなかった。 Next, the powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 850 ° C. for 8 hours in the atmosphere. A silicon oxide layer was formed on the surface of the silicon carbide particles. I could not.
「比較例２」
炭化ケイ素粒子（比表面積：０．５ｍ２／ｇ、平均一次粒子径：６．０μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が０．９ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素の表面に白金が付着した粉体を得た。
"Comparative Example 2"
10 g of silicon carbide particles (specific surface area: 0.5 m 2 / g, average primary particle size: 6.0 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 0.9 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator, and then dried at 150 ° C. for 12 hours to obtain a powder having platinum adhered to the surface of silicon carbide.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中７００℃にて５時間、熱処理したが、この炭化ケイ素粒子の表面には酸化ケイ素層を形成することができなかった。 Next, this powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 700 ° C. for 5 hours in the atmosphere. A silicon oxide layer was formed on the surface of the silicon carbide particles. I could not.
「比較例３」
炭化ケイ素粒子（比表面積：５．０ｍ２／ｇ、平均一次粒子径：０．８μｍ）１０ｇを、水９０ｇ中に分散させた。次いで、この分散液に炭化ケイ素１ｍｏｌに対して白金が１．２ｍｏｌとなるように塩化白金酸水溶液を加えて混合した。次いで、この混合物を、エバポレーターを用いて蒸発乾固、解砕した後、１５０℃にて１２時間乾燥し、炭化ケイ素の表面に白金が付着した粉体を得た。
“Comparative Example 3”
10 g of silicon carbide particles (specific surface area: 5.0 m 2 / g, average primary particle size: 0.8 μm) were dispersed in 90 g of water. Next, a chloroplatinic acid aqueous solution was added to and mixed with this dispersion so that platinum was 1.2 mol with respect to 1 mol of silicon carbide. Next, this mixture was evaporated to dryness and pulverized using an evaporator, and then dried at 150 ° C. for 12 hours to obtain a powder having platinum adhered to the surface of silicon carbide.
次いで、この粉体を、アルゴン雰囲気中、１０００℃にて１時間熱処理し、次いで、大気中５００℃にて２時間、熱処理したが、この炭化ケイ素粒子の表面には酸化ケイ素層を形成することができなかった。 Next, the powder was heat-treated at 1000 ° C. for 1 hour in an argon atmosphere, and then heat-treated at 500 ° C. for 2 hours in the atmosphere. A silicon oxide layer was formed on the surface of the silicon carbide particles. I could not.
「触媒特性の評価（その１）」
実施例１〜７で得られた触媒粒子、実施例８〜１０で得られた多孔質膜を剥いだハニカム基材の破片及び比較例１〜３で得られた各粉体を試料として、カーボンブラックの酸化試験を行い、実施例１〜１０及び比較例１〜３各々の試料の酸化触媒特性を評価した。
また、実施例１〜７で得られた触媒粒子、実施例８〜１０で得られた多孔質膜を剥いだハニカム基材の破片を試料とし、これらの試料を大気雰囲気中、７００℃にて３０時間保持した後、カーボンブラックの酸化試験を行い、各試料の熱劣化状態を評価した（熱劣化試験）。
"Evaluation of catalyst properties (1)"
Using the catalyst particles obtained in Examples 1 to 7, the fragments of the honeycomb substrate from which the porous films obtained in Examples 8 to 10 were peeled off, and the powders obtained in Comparative Examples 1 to 3 as samples, carbon A black oxidation test was performed, and the oxidation catalyst characteristics of the samples of Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated.
Moreover, the catalyst particles obtained in Examples 1 to 7 and the fragments of the honeycomb substrate from which the porous films obtained in Examples 8 to 10 were peeled off were used as samples, and these samples were used at 700 ° C. in an air atmosphere. After holding for 30 hours, an oxidation test of carbon black was performed to evaluate the thermal degradation state of each sample (thermal degradation test).
このカーボンブラックの酸化試験による各試料の酸化触媒特性評価は、次のようにして行った。
まず、測定粒子とカーボンブラック（商品名：Printex-U）とを、粒子：カーボンブラック＝９５：５（質量比）の比率で混ぜ合わせ、その後、乳鉢で十分に混合し、測定用試料とした。次いで、熱重量分析−示差熱分析装置（ＴＧ−ＤＴＡ装置）を用いて、試料を大気中で５℃／分で昇温させ、カーボンブラックの熱重量減少量が５０質量％に達した温度（Ｔ５０温度）を測定した。この熱重量減少量が５０質量％に達した温度（Ｔ５０温度）をもって、各粒子の酸化触媒特性を評価した。
Evaluation of oxidation catalyst characteristics of each sample by the oxidation test of carbon black was performed as follows.
First, measurement particles and carbon black (trade name: Printex-U) were mixed at a ratio of particle: carbon black = 95: 5 (mass ratio), and then mixed well in a mortar to obtain a measurement sample. . Next, using a thermogravimetric analysis-differential thermal analyzer (TG-DTA apparatus), the temperature of the sample was raised in the atmosphere at 5 ° C./minute, and the temperature at which the thermal weight reduction amount of carbon black reached 50% by mass ( T50 temperature) was measured. The oxidation catalyst characteristics of each particle were evaluated at the temperature (T50 temperature) at which the thermal weight loss reached 50% by mass.
「触媒特性の評価（その２）」
実施例８のハニカム構造体を用いて、ベンゼンの酸化触媒特性を評価した。
ここでは、反応装置内に上記のハニカム構造体を設置し、この反応装置内の温度を１８０℃に保ったまま、この反応装置内に挿入ガス (ベンゼン：２５ｐｐｍ、ＣＯ２：１５体積％、Ｏ２：５体積％、Ｈ２Ｏ：９体積％、Ｎ２：残部）を 空間速度（ＳＶ）６０００／Ｈｒで導入し、反応させた。
反応開始３０分後の分解率は９６％以上であり、高い触媒効果を有することが確認できた。
"Evaluation of catalyst characteristics (2)"
Using the honeycomb structure of Example 8, the oxidation catalyst characteristics of benzene were evaluated.
Here, the above honeycomb structure is installed in the reactor, and the temperature inside the reactor is kept at 180 ° C., and the inserted gas (benzene: 25 ppm, CO 2 : 15 vol%, O 2) is kept in the reactor. 2 : 5% by volume, H 2 O: 9% by volume, N 2 : balance) were introduced at a space velocity (SV) of 6000 / Hr and allowed to react.
The decomposition rate 30 minutes after the start of the reaction was 96% or more, and it was confirmed that the catalyst had a high catalytic effect.
「酸化ケイ素層の膜厚測定」
実施例及び比較例で作製した試料について、電界放射型透過電子顕微鏡（ＦＥ−ＴＥＭ）JEM-2100（日本電子(株)社製）による観察、Ｘ線光電子分析装置 Sigma Probe（VG-Scientific社製）を用いたＥＳＣＡ（Electron Spectroscopy for Chemical Analysis）、電界放出型オージェ電子分光装置 JAMP-9500F（日本電子(株)社製）により、炭化ケイ素粒子の表面の組成分析を行い、酸化ケイ素層の膜厚を測定した。なお、実施例８〜１０については、多孔質膜をハニカム基材とともに切り出し、この多孔質膜の膜厚を測定した。
"Measurement of film thickness of silicon oxide layer"
Samples prepared in Examples and Comparative Examples are observed with a field emission transmission electron microscope (FE-TEM) JEM-2100 (manufactured by JEOL Ltd.), an X-ray photoelectron analyzer Sigma Probe (manufactured by VG-Scientific) ) And ESCA (Electron Spectroscopy for Chemical Analysis), field emission type Auger electron spectrometer JAMP-9500F (manufactured by JEOL Ltd.) to analyze the composition of the surface of silicon carbide particles, The thickness was measured. In addition, about Examples 8-10, the porous film was cut out with the honeycomb base material, and the film thickness of this porous film was measured.
「比表面積の測定」
実施例１〜７にて得られた触媒粒子の比表面積を、ＢＥＬＳＯＲＰ−ｍｉｎｉ装置（日本ベル(株)社製）を用いて測定した。
実施例１〜１０及び比較例１〜３の各粒子の特性及び触媒特性評価試験結果を表１に示す。
"Measurement of specific surface area"
The specific surface area of the catalyst particles obtained in Examples 1 to 7 was measured using a BELSORP-mini apparatus (manufactured by Nippon Bell Co., Ltd.).
Table 1 shows the characteristics of the particles of Examples 1 to 10 and Comparative Examples 1 to 3 and the results of the catalyst characteristics evaluation test.
表１によれば、実施例１〜１０の触媒粒子は、炭化ケイ素粒子の表面に非晶質の酸化ケイ素層が形成されていることが確認された。また、炭化ケイ素粒子の粒子径は、酸化ケイ素層が形成された後でも変化はなかった。一方、比較例１〜３では、酸化ケイ素層は形成できていなかった。 According to Table 1, in the catalyst particles of Examples 1 to 10, it was confirmed that an amorphous silicon oxide layer was formed on the surface of the silicon carbide particles. Further, the particle size of the silicon carbide particles did not change even after the silicon oxide layer was formed. On the other hand, in Comparative Examples 1-3, the silicon oxide layer was not able to be formed.
また、実施例１〜１０では、貴金属粒子を担持させた酸化ケイ素層を備えているので、炭化ケイ素粒子に単に貴金属粒子を担持させた場合（比較例１〜３）と比べて、熱重量減少開始温度が低下しており、したがって、触媒特性が向上していることが分かった。
さらに、熱劣化試験後も熱重量減少開始温度がほとんど変化せず、高温下でも優れた触媒活性が得られ、高温耐久性に優れていた。
一方、比較例１〜３では、熱劣化試験後、熱重量減少開始温度が大幅に上昇しており、高温耐久性に劣るものであった。
Moreover, in Examples 1-10, since the silicon oxide layer which carry | supported the noble metal particle was provided, compared with the case where a silicon carbide particle is only carry | supported a noble metal particle (Comparative Examples 1-3), thermal weight reduction It has been found that the starting temperature has decreased and therefore the catalytic properties have improved.
Furthermore, the thermogravimetric decrease start temperature hardly changed even after the thermal deterioration test, and excellent catalytic activity was obtained even at high temperatures, and the high temperature durability was excellent.
On the other hand, in Comparative Examples 1 to 3, after the thermal deterioration test, the thermogravimetric decrease starting temperature was significantly increased, and the high temperature durability was poor.
図１に示す実施例６の触媒粒子では、炭化ケイ素粒子が白金粒子を担持させた酸化ケイ素層を備えているので、７００℃にて３０時間の熱履歴を加えた後においても、担持された白金粒子は、粒子径が１０ｎｍ以上のものが無く、平均でも５ｎｍ以下と、白金粒子の焼成時の粗大化は十分に阻止されていた。また、用いた炭化ケイ素粒子の粒子径や粒子の状態についても、変化が生じていないことが確認された。 In the catalyst particles of Example 6 shown in FIG. 1, since the silicon carbide particles were provided with a silicon oxide layer on which platinum particles were supported, they were supported even after applying a heat history of 30 hours at 700 ° C. There was no platinum particle having a particle diameter of 10 nm or more, and the average was 5 nm or less, and the coarsening of the platinum particles during firing was sufficiently prevented. In addition, it was confirmed that no change occurred in the particle diameter and particle state of the silicon carbide particles used.
Claims (9)
前記酸化ケイ素層の厚みは０．１ｎｍ以上かつ３０ｎｍ以下であり、
前記炭化ケイ素粒子に担持される前記貴金属粒子の量は、前記炭化ケイ素１ｍｏｌに対して０．００５ｍｏｌ以上かつ１ｍｏｌ以下であることを特徴とする貴金属担持炭化ケイ素粒子。 Provided with a silicon oxide layer carrying noble metal particles on the surface of silicon carbide particles having an average primary particle diameter of 0.005 μm or more and 5 μm or less ,
The thickness of the silicon oxide layer is 0.1 nm or more and 30 nm or less,
The noble metal-supported silicon carbide particles, wherein the amount of the noble metal particles supported on the silicon carbide particles is 0.005 mol or more and 1 mol or less with respect to 1 mol of the silicon carbide .
請求項１ないし３のいずれか１項記載の貴金属担持炭化ケイ素粒子を含有してなることを特徴とする触媒。 A catalyst used for DPF or automobile exhaust gas purification,
A catalyst comprising the noble metal-supported silicon carbide particles according to any one of claims 1 to 3.
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