JP4644798B2 - Metal-supported nanocarbon fiber catalyst - Google Patents
Metal-supported nanocarbon fiber catalyst Download PDFInfo
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- JP4644798B2 JP4644798B2 JP2004101637A JP2004101637A JP4644798B2 JP 4644798 B2 JP4644798 B2 JP 4644798B2 JP 2004101637 A JP2004101637 A JP 2004101637A JP 2004101637 A JP2004101637 A JP 2004101637A JP 4644798 B2 JP4644798 B2 JP 4644798B2
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- 239000003054 catalyst Substances 0.000 title claims description 137
- 239000000835 fiber Substances 0.000 title claims description 47
- 229910021392 nanocarbon Inorganic materials 0.000 title claims description 43
- 229910052751 metal Inorganic materials 0.000 claims description 49
- 239000002184 metal Substances 0.000 claims description 49
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 39
- 239000002245 particle Substances 0.000 claims description 28
- 229910052759 nickel Inorganic materials 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 7
- -1 nickel metals Chemical class 0.000 claims description 6
- 239000002121 nanofiber Substances 0.000 claims description 3
- 239000000969 carrier Substances 0.000 claims 1
- 238000005336 cracking Methods 0.000 claims 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 126
- 238000006243 chemical reaction Methods 0.000 description 46
- 239000007789 gas Substances 0.000 description 38
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 35
- 230000000052 comparative effect Effects 0.000 description 28
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 24
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 16
- 230000003197 catalytic effect Effects 0.000 description 16
- 229910021393 carbon nanotube Inorganic materials 0.000 description 15
- 239000002041 carbon nanotube Substances 0.000 description 15
- 229910003460 diamond Inorganic materials 0.000 description 13
- 239000010432 diamond Substances 0.000 description 13
- 238000004519 manufacturing process Methods 0.000 description 13
- 238000000354 decomposition reaction Methods 0.000 description 12
- 229930195733 hydrocarbon Natural products 0.000 description 12
- 150000002430 hydrocarbons Chemical class 0.000 description 12
- 239000002923 metal particle Substances 0.000 description 12
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 11
- 229910052799 carbon Inorganic materials 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 238000011084 recovery Methods 0.000 description 9
- 239000004215 Carbon black (E152) Substances 0.000 description 8
- 229910052786 argon Inorganic materials 0.000 description 8
- 229910052739 hydrogen Inorganic materials 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- 239000002904 solvent Substances 0.000 description 8
- 238000006555 catalytic reaction Methods 0.000 description 6
- 229910002804 graphite Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 6
- 229920000049 Carbon (fiber) Polymers 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000004917 carbon fiber Substances 0.000 description 5
- 239000012018 catalyst precursor Substances 0.000 description 5
- 239000007795 chemical reaction product Substances 0.000 description 5
- 238000005470 impregnation Methods 0.000 description 5
- 229910052763 palladium Inorganic materials 0.000 description 5
- 229910052723 transition metal Inorganic materials 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 125000004429 atom Chemical group 0.000 description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910017052 cobalt Inorganic materials 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 238000003475 lamination Methods 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 239000010948 rhodium Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000009529 body temperature measurement Methods 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000012495 reaction gas Substances 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 229910052703 rhodium Inorganic materials 0.000 description 2
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000002134 carbon nanofiber Substances 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000002079 double walled nanotube Substances 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- YJVFFLUZDVXJQI-UHFFFAOYSA-L palladium(ii) acetate Chemical compound [Pd+2].CC([O-])=O.CC([O-])=O YJVFFLUZDVXJQI-UHFFFAOYSA-L 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229930195734 saturated hydrocarbon Natural products 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910002001 transition metal nitrate Inorganic materials 0.000 description 1
- 229930195735 unsaturated hydrocarbon Natural products 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Description
本発明は、ナノサイズの金属触媒がナノ炭素繊維に担持された、金属担持ナノ炭素繊維触媒及びその製造方法に関する。 The present invention relates to a metal-supported nanocarbon fiber catalyst in which a nanosize metal catalyst is supported on a nanocarbon fiber and a method for producing the same.
水素ガス、または、水素と一酸化炭素の合成ガスは、メタン等の低級炭化水素、メタノール、または、エタノール等のアルコール類を熱分解して、あるいは、酸素、水蒸気又は二酸化炭素等の酸化剤を使用して分解することにより生成している。これらの分解反応には触媒が用いられ、触媒には主に、アルミナやシリカ等の金属酸化物を担体とし、この担体に、ニッケル（Ｎｉ）、コバルト（Ｃｏ）、鉄（Ｆｅ）、ルテニウム（Ｒｕ）、ロジウム（Ｒｈ）、パラジウム（Ｐｄ）、イリジウム（Ｉｒ）、白金（Ｐｔ）等の８族遷移金属元素を主成分とする触媒成分を担持させた、所謂金属担持触媒が使用されている。 Hydrogen gas or a synthesis gas of hydrogen and carbon monoxide is obtained by thermally decomposing lower hydrocarbons such as methane, alcohols such as methanol or ethanol, or oxidizing agents such as oxygen, water vapor or carbon dioxide. It is generated by using and decomposing. A catalyst is used for these decomposition reactions, and the catalyst mainly uses a metal oxide such as alumina or silica as a carrier, and this carrier contains nickel (Ni), cobalt (Co), iron (Fe), ruthenium ( A so-called metal-supported catalyst is used in which a catalyst component mainly composed of a group 8 transition metal element such as Ru), rhodium (Rh), palladium (Pd), iridium (Ir), or platinum (Pt) is supported. .
従来、遷移金属触媒を金属酸化物担体に担持するには、含浸法が用いられている。例えば、遷移金属の硝酸塩が含有された溶液、あるいは、遷移金属アミン錯体が含有された溶液に担体を含浸することにより、担体表面に遷移金属を分散、付着させ、続いて、乾燥により溶媒を除去し、焼成により遷移金属を強固に担持する。 Conventionally, an impregnation method is used to support a transition metal catalyst on a metal oxide support. For example, by impregnating the support in a solution containing a transition metal nitrate or a solution containing a transition metal amine complex, the transition metal is dispersed and adhered to the support surface, and then the solvent is removed by drying. The transition metal is firmly supported by firing.
また、触媒金属の単位量あたりの触媒反応速度を高めるため、γ−アルミナ等の多孔質な担体を用い、担体の微細な穴に触媒金属を分散させることによって触媒金属の比表面積を高め、触媒反応速度を高めている。 In addition, in order to increase the catalytic reaction rate per unit amount of catalytic metal, a porous carrier such as γ-alumina is used, and the catalytic metal is dispersed in fine holes in the carrier to increase the specific surface area of the catalytic metal, The reaction rate is increased.
しかしながら、触媒能力向上への化学産業界の要求は留まるところを知らず、多孔質担体の微細な穴を利用して触媒金属を分散させる方法では、これ以上の触媒反応速度の向上が見込めない状況にある。
上記課題に鑑み本発明者らは、触媒反応速度の向上を実現すべく、鋭意、研究を重ねた結果、触媒金属の単位量あたりの触媒反応速度は触媒金属の粒径に依存し、その最適のサイズはｎｍ（ナノメーター）オーダー、すなわち、クラスターサイズであることを見出した（非特許文献１参照）。本発明者らは、この事実に基づき、ｎｍオーダーの触媒金属粒子を担持した触媒の実現を目指した。 In view of the above problems, the present inventors have intensively studied to realize an improvement in the catalyst reaction rate. As a result, the catalyst reaction rate per unit amount of the catalyst metal depends on the particle size of the catalyst metal, and the optimum It was found that the size of the nanometer is on the order of nm (nanometer), that is, the cluster size (see Non-Patent Document 1). Based on this fact, the inventors of the present invention aimed to realize a catalyst supporting nanometer-order catalytic metal particles.
しかしながら、従来の金属化合物の溶液を用いた含浸法による金属の担持方法では、触媒金属のサイズを最適に制御することはできない。すなわち、含浸法により、多孔質担体に触媒金属を分散させた段階では、触媒金属は原子レベルのサイズで多孔質担体の細孔に付着しているが、溶媒の除去工程や、残留する硝酸を分解除去し、触媒金属を触媒担体に強く結合させる焼成工程において、金属原子がその熱エネルギーにより容易に細孔表面を移動して凝集し、最適サイズよりも大きな粒径の触媒金属粒子が形成されてしまう。 However, the size of the catalyst metal cannot be optimally controlled by a conventional metal loading method using an impregnation method using a solution of a metal compound. That is, at the stage where the catalyst metal is dispersed in the porous carrier by the impregnation method, the catalyst metal is attached to the pores of the porous carrier at the atomic size, but the removal process of the solvent and the remaining nitric acid are removed. In the calcination process, which decomposes and removes and bonds the catalyst metal strongly to the catalyst support, the metal atoms easily move on the surface of the pores due to their thermal energy and agglomerate to form catalyst metal particles having a particle size larger than the optimum size. End up.
このように、従来の多孔質担体を用いた溶媒含浸法では、触媒反応速度が最大になるサ
イズの触媒金属粒子を形成できないという課題がある。
Thus, the conventional solvent impregnation method using a porous carrier has a problem that catalyst metal particles having a size that maximizes the catalytic reaction rate cannot be formed.
上記課題に鑑み本発明は、触媒反応速度が最大になるサイズの触媒金属粒子、すなわち、ｎｍオーダーのサイズの触媒金属粒子を担持した触媒を提供することを目的とする。また、その製造方法を提供することを目的とする。 In view of the above problems, an object of the present invention is to provide a catalyst metal particle having a size that maximizes the catalyst reaction rate, that is, a catalyst carrying catalyst metal particles having a size on the order of nm. Moreover, it aims at providing the manufacturing method.
上記目的を達成するために本発明の触媒金属担持ナノ炭素繊維触媒は、ナノ炭素繊維からなる担体と、この担体に担持されたｎｍオーダーのサイズの触媒金属粒子とからなることを特徴とする。 In order to achieve the above object, the catalyst metal-supported nanocarbon fiber catalyst of the present invention is characterized by comprising a support made of nanocarbon fibers and catalyst metal particles having a size of nm order supported on the support.
上記ナノ炭素繊維からなる担体は、好ましくは、カーボンナノチューブ、カーボンナノフィラメント、コイン積層型ナノグラファイトの何れかまたはそれらの組合わせでなる。ナノ炭素繊維は、好ましくは、１０ｎｍ以下の径を有する。 The carrier made of the nanocarbon fiber is preferably made of any one of carbon nanotubes, carbon nanofilaments, coin-laminated nanographite, or a combination thereof. The nanocarbon fiber preferably has a diameter of 10 nm or less.
また、触媒金属は、ニッケルでなる。
Moreover, the catalyst metal is made of nickel.
上記構成によれば、触媒金属はナノ炭素繊維表面に担持され、ナノ炭素繊維の径はナノサイズであるため、担持されるた触媒金属の粒径はｎｍオーダーのサイズとなり、従って、最も触媒反応速度が大きいサイズとなる。 According to the above configuration, the catalytic metal is supported on the surface of the nanocarbon fiber, and the diameter of the nanocarbon fiber is nano-sized. The speed is a large size.
また、本発明の金属担持ナノ炭素繊維触媒の製造方法は、ナノ炭素繊維を触媒金属の金属塩を含む溶液に含浸する工程と、含浸した状態で溶媒を蒸発する工程と、溶媒を蒸発して得たナノ炭素繊維を焼成する工程と、焼成したナノ炭素繊維を還元雰囲気中で熱処理する工程とから成ることを特徴とする。 The method for producing a metal-supported nanocarbon fiber catalyst of the present invention comprises a step of impregnating nanocarbon fibers in a solution containing a metal salt of a catalyst metal, a step of evaporating the solvent in the impregnated state, and evaporating the solvent. It comprises a step of firing the obtained nanocarbon fiber and a step of heat-treating the fired nanocarbon fiber in a reducing atmosphere.
この方法によれば、ナノ炭素繊維を触媒金属の金属塩を含む溶液に含浸し、含浸した状態で溶液の溶媒を蒸発することによって、ナノ炭素繊維の表面に触媒金属原子が高い分散度で付着した触媒前駆体が得られる。触媒前駆体を焼成すると、残留する酸が分解、蒸発すると共に、ナノ炭素繊維の表面に触媒金属粒子が強固に担持される。焼成したナノ炭素繊維を還元雰囲気中で熱処理することにより、触媒金属粒子が活性化され、金属担持ナノ炭素繊維触媒が製造される。 According to this method, nanocarbon fibers are impregnated in a solution containing a metal salt of a catalyst metal, and the solvent of the solution is evaporated in the impregnated state, whereby catalyst metal atoms adhere to the surface of the nanocarbon fiber with a high degree of dispersion. The catalyst precursor thus obtained is obtained. When the catalyst precursor is calcined, the remaining acid is decomposed and evaporated, and the catalyst metal particles are firmly supported on the surface of the nanocarbon fiber. By heat-treating the calcined nanocarbon fiber in a reducing atmosphere, the catalyst metal particles are activated and a metal-supported nanocarbon fiber catalyst is produced.
この方法によれば、ｎｍオーダーの径のナノ炭素繊維を用いるので、触媒金属粒子の径がｎｍオーダーになり、触媒反応速度が著しく増大する。 According to this method, since nano-carbon fibers having a diameter on the order of nm are used, the diameter of the catalyst metal particles becomes on the order of nm, and the catalytic reaction rate is remarkably increased.
ナノ炭素繊維としては、カーボンナノチューブ、カーボンナノフィラメント、コイン積層型ナノグラファイトの何れかまたはそれらの組合わせを用いることができる。 As the nanocarbon fiber, any of carbon nanotubes, carbon nanofilaments, coin-laminated nanographite, or a combination thereof can be used.
また、触媒金属としては、ニッケルを用いることができる。
As the catalyst metal, it can be used nickel.
本発明の触媒は、触媒金属粒子の粒径がｎｍオーダーであるので、触媒金属の単位量あたりの触媒反応速度が従来の触媒に比べて高い。また、本発明の方法によれば、触媒金属粒子の粒径がｎｍオーダーの金属触媒を製造することができる。 In the catalyst of the present invention, since the particle size of the catalyst metal particles is on the order of nm, the catalyst reaction rate per unit amount of the catalyst metal is higher than that of the conventional catalyst. Moreover, according to the method of the present invention, a metal catalyst having a catalyst metal particle size of the order of nm can be produced.
以下、本発明の金属担持ナノ炭素繊維触媒、及びその製造方法を図面を参照して詳細に説明する。 Hereinafter, the metal-supported nanocarbon fiber catalyst of the present invention and the production method thereof will be described in detail with reference to the drawings.
初めに、本発明の触媒に用いるナノ炭素繊維について説明する。 First, the nanocarbon fiber used for the catalyst of the present invention will be described.
図１は、本発明の触媒に用いるナノ炭素繊維の一例であるコイン積層型ナノグラファイトの走査型電子顕微鏡像である。図において、白い繊維状の線が不規則な網の目状に配列しているのがわかる。この白い線はコイン積層型ナノグラファイトの繊維であり、径は約８ｎｍである。 FIG. 1 is a scanning electron microscope image of coin-laminated nanographite, which is an example of nanocarbon fibers used in the catalyst of the present invention. In the figure, it can be seen that white fibrous lines are arranged in an irregular mesh pattern. This white line is a coin-laminated nanographite fiber, and the diameter is about 8 nm.
触媒金属は、この繊維の表面に担持され、下記に詳しく説明するように、触媒金属の粒径は約２ｎｍである。 The catalyst metal is supported on the surface of the fiber, and the particle diameter of the catalyst metal is about 2 nm as described in detail below.
本発明の触媒に用いるカーボンナノチューブや、カーボンナノフィラメントの像は示さないが、ｎｍオーダーの径の繊維が不規則な網の目状に配列している点は、図１と共通する。 Although the image of the carbon nanotube used for the catalyst of this invention and a carbon nanofilament is not shown, the point with which the fiber of the diameter of nm order is arranged in the shape of an irregular network is common to FIG.
カーボンナノチューブ、カーボンナノフィラメント、あるいはコイン積層型ナノグラファイト等のナノ繊維は、現状では市販されておらず、手に入りにくいのが現状である。従って、これらのナノ繊維の製造方法の一例を下記に説明する（詳しくは特許文献１及び２を参照）。 Currently, nanofibers such as carbon nanotubes, carbon nanofilaments, or coin-laminated nanographite are not commercially available and are difficult to obtain. Therefore, an example of a method for producing these nanofibers will be described below (for details, refer to Patent Documents 1 and 2).
初めにカーボンナノチューブの製造方法を説明する。 First, a method for producing carbon nanotubes will be described.
カーボンナノチューブは、例えば、以下の方法によって製造することができる。粒径が１〜１０ｎｍのダイヤモンドを担体として、ニッケル、コバルト又は鉄を触媒金属として担持した触媒の下で、炭化水素を分解することによって製造できる。ダイヤモンドは市販の人工ダイヤモンドで良く、また、触媒金属を担持する前に、ダイヤモンド表面を酸化することが望ましい。炭化水素は、炭素数が１〜３０の炭化水素であれば良く、メタン、エタン、プロパンなどの飽和炭化水素の他、エチレン、プロピレン、アセチレンなどの不飽和炭化水素でも良い。 Carbon nanotubes can be produced, for example, by the following method. It can be produced by decomposing hydrocarbons under a catalyst in which diamond having a particle size of 1 to 10 nm is used as a support and nickel, cobalt or iron is supported as a catalyst metal. The diamond may be a commercially available diamond, and it is desirable to oxidize the diamond surface before supporting the catalytic metal. The hydrocarbon may be a hydrocarbon having 1 to 30 carbon atoms, and may be an unsaturated hydrocarbon such as ethylene, propylene, and acetylene in addition to a saturated hydrocarbon such as methane, ethane, and propane.
ニッケルを触媒金属とし、炭化水素としてメタンを用いた場合には、触媒を約６００℃に保ち、メタンガス流量を約２０ｃｍ3 ／分とし、約６０分の反応時間で得られる。 When nickel is the catalyst metal and methane is used as the hydrocarbon, the catalyst is kept at about 600 ° C., the methane gas flow rate is about 20 cm 3 / min, and the reaction time is about 60 minutes.
このようにして製造したカーボンナノチューブの一端には、触媒として用いたダイヤモンド粒が強固に付着している。カーボンナノチューブの他端は、閉口端または開口端とすることができるが、触媒の担体としては、他端が閉口端であることが好適である。 Diamond particles used as a catalyst are firmly attached to one end of the carbon nanotubes thus produced. The other end of the carbon nanotube can be a closed end or an open end, but as the catalyst carrier, the other end is preferably a closed end.
また、粒径が１０〜１５ｎｍのダイヤモンドを担体とすると、一端には触媒として用いたダイヤモンド粒が強固に付着し、その他端には閉口端または開口端とを有する二層カーボンナノチューブが得られる。触媒の担体としては、その他端が閉口端であることが好適である。 When diamond having a particle size of 10 to 15 nm is used as a carrier, diamond particles used as a catalyst are firmly attached to one end, and a double-walled carbon nanotube having a closed end or an open end at the other end is obtained. As the catalyst carrier, the other end is preferably a closed end.
さらに、粒径が１５〜１００ｎｍのダイヤモンドを担体とすると、一端には触媒として用いたダイヤモンド粒が強固に付着し、その他端には閉口端または開口端を有する三層以上のカーボンナノチューブが得られる。触媒の担体としては、その他端が閉口端であることが好適である。 Further, when diamond having a particle diameter of 15 to 100 nm is used as a carrier, diamond particles used as a catalyst are firmly attached to one end, and a carbon nanotube having three or more layers having a closed end or an open end is obtained at the other end. . As the catalyst carrier, the other end is preferably a closed end.
次に、カーボンナノフィラメントの製造方法について説明する。 Next, the manufacturing method of a carbon nanofilament is demonstrated.
カーボンナノフィラメントとは、炭素繊維の構造が中空状でないカーボンナノファイバーのうち、特にその径がおおよそ１０ｎｍ以下の径のものを指す。 The carbon nanofilament refers to a carbon nanofiber whose carbon fiber structure is not hollow, particularly having a diameter of approximately 10 nm or less.
ところで、平面状のグラファイト層が積層されてなる構造体は、ナノグラファイトと呼ばれている。一方、傘状又はカップ状のグラファイトが積層して成る構造体は、カーボンナノフィラメントと呼ばれている。カーボンナノフィラメントは、例えば、粒径が１００〜５００ｎｍのダイヤモンドを担体として、カーボンナノチューブと同様に、ニッケル、コバルト、又は鉄を触媒金属として担持した触媒の下で、炭化水素を分解することによって製造できる。ここで、ダイヤモンドや炭化水素は、上記カーボンナノチューブの製造方法で説明したものが使用できる。 By the way, a structure formed by laminating a planar graphite layer is called nanographite. On the other hand, a structure formed by stacking umbrella-shaped or cup-shaped graphite is called a carbon nanofilament. Carbon nanofilaments are produced, for example, by decomposing hydrocarbons under a catalyst in which nickel, cobalt, or iron is supported as a catalytic metal in the same manner as carbon nanotubes using diamond having a particle size of 100 to 500 nm as a carrier. it can. Here, as the diamond and hydrocarbon, those described in the method for producing carbon nanotubes can be used.
パラジウムを触媒金属とし、炭化水素としてメタンを用いた場合には、触媒を約６００℃に保ち、メタンガス流量を約２０ｃｍ3 ／分とし、約６０分の反応時間で得られる。 When palladium is the catalyst metal and methane is used as the hydrocarbon, the catalyst is kept at about 600 ° C., the methane gas flow rate is about 20 cm 3 / min, and the reaction time is about 60 minutes.
次に、コイン積層型ナノグラファイトの製造方法について説明する。 Next, the manufacturing method of coin laminated nanographite will be described.
コイン積層型グラファイト繊維は、例えば以下の方法によって製造することができる。
粒径が数〜数百ｎｍのダイヤモンドを担体として、パラジウム又はロジウムを触媒金属として担持した触媒の下で、炭化水素を分解することによって製造できる。ここで、ダイヤモンドや炭化水素は上記カーボンナノチューブの製造方法で説明したものが使用できる。パラジウムを触媒金属とし、炭化水素としてメタンを用いた場合には、触媒を約６００℃に保ち、メタンガス流量を約２０ｃｍ3 ／分とし、約６０分の反応時間で得られる。
The coin laminated graphite fiber can be manufactured, for example, by the following method.
It can be produced by decomposing hydrocarbons under a catalyst in which diamond having a particle size of several to several hundred nm is supported as a carrier and palladium or rhodium is supported as a catalyst metal. Here, as the diamond and the hydrocarbon, those described in the method for producing the carbon nanotube can be used. When palladium is the catalyst metal and methane is used as the hydrocarbon, the catalyst is kept at about 600 ° C., the methane gas flow rate is about 20 cm 3 / min, and the reaction time is about 60 minutes.
次に、本発明の金属担持ナノ炭素繊維触媒の製造方法を説明する。 Next, the manufacturing method of the metal carrying | support nanocarbon fiber catalyst of this invention is demonstrated.
初めに、触媒となる金属の金属塩と、金属塩の溶媒とを加えた溶液を調製する。次に、この溶液中にナノ炭素繊維を含浸する。適切な時間含浸した後、溶液中にナノ炭素繊維を含浸した状態で溶媒を蒸発させる。これにより、触媒金属原子がナノ炭素繊維表面に高い分散度で付着した触媒前駆体が得られる。次に、触媒前駆体を窒素などの不活性ガス中、あるいは、大気中で焼成する。例えば、大気中の場合は、４００〜８００℃で３〜５時間の条件が好ましい。焼成温度が４００℃より低いと残留している硝酸などの不純物を十分に除去できず、触媒活性を発現しないか又は低下させる。焼成温度は８００℃程度まで上昇させることもできる。しかしながら、８００℃を越える高温は、ナノ炭素繊維と触媒金属とが反応し、触媒金属と炭素からなるグラファイトが形成され、触媒活性を失う恐れがあるので望ましくない。 First, a solution is prepared by adding a metal salt of a metal to be a catalyst and a metal salt solvent. Next, this solution is impregnated with nanocarbon fibers. After impregnation for an appropriate time, the solvent is evaporated while the nanocarbon fiber is impregnated in the solution. As a result, a catalyst precursor in which catalytic metal atoms are attached to the nanocarbon fiber surface with a high degree of dispersion can be obtained. Next, the catalyst precursor is calcined in an inert gas such as nitrogen or in the air. For example, in the air, conditions of 400 to 800 ° C. and 3 to 5 hours are preferable. If the calcination temperature is lower than 400 ° C., residual impurities such as nitric acid cannot be sufficiently removed, and the catalytic activity is not exhibited or reduced. The firing temperature can also be raised to about 800 ° C. However, a high temperature exceeding 800 ° C. is not desirable because the nanocarbon fiber and the catalyst metal react with each other to form graphite composed of the catalyst metal and carbon and lose the catalytic activity.
次に、触媒活性を付与するために還元処理を行う。還元処理は、還元ガス中で行い、例えば、水素などの還元ガスの流気中で行なえばよい。還元温度は、３００〜５００℃が適当であり、３００℃より低いと十分に金属を還元できず、また、８００℃以上の高い還元温度は、ナノ炭素繊維の一部が触媒金属と反応し、触媒金属と炭素からなるグラファイトが形成され、触媒活性を失う恐れがあるので望ましくない。 Next, a reduction process is performed to impart catalytic activity. The reduction treatment may be performed in a reducing gas, for example, in a flow of a reducing gas such as hydrogen. The reduction temperature is suitably 300 to 500 ° C. If the temperature is lower than 300 ° C., the metal cannot be sufficiently reduced, and a high reduction temperature of 800 ° C. or higher causes a part of the nanocarbon fiber to react with the catalytic metal, This is not desirable because graphite formed of catalytic metal and carbon is formed and the catalytic activity may be lost.
次に、実施例に基づいてさらに詳細に説明する。 Next, it demonstrates still in detail based on an Example.
約８ｎｍ径のコイン積層型ナノグラファイトを担体として、触媒金属としてニッケルを用いて、次のようにして金属担持ナノ炭素繊維触媒を作製した。 A metal-supported nanocarbon fiber catalyst was prepared as follows using a coin-stacked nanographite having a diameter of about 8 nm as a carrier and nickel as the catalyst metal.
硝酸ニッケルの飽和水溶液に所定量のコイン積層型ナノグラファイトを加え、一夜放置後、水を蒸発させて乾燥した。乾燥後、触媒前駆体を４００〜５００℃の窒素ガス中で焼成し、硝酸及び残留する硝酸ニッケルを除去した。次に、３００〜５００℃の水素ガス中で還元して、触媒金属がニッケルであり、担体のナノ炭素繊維がコイン積層型ナノグラファイトである、ニッケル担持コイン積層型ナノグラファイト触媒を作製した。なお、この触媒に含まれるＮｉの担持量は、ニッケル及び担体であるコイン積層型ナノグラファイトの合計質量を基準にして、５質量％であった。
〔参考例１〕
A predetermined amount of coin-laminated nanographite was added to a saturated aqueous solution of nickel nitrate, and allowed to stand overnight, after which the water was evaporated and dried. After drying, the catalyst precursor was calcined in nitrogen gas at 400 to 500 ° C. to remove nitric acid and remaining nickel nitrate. Next, it reduced in 300-500 degreeC hydrogen gas, and produced the nickel carrying | support coin lamination type | mold nanographite catalyst whose catalyst metal is nickel and the nano carbon fiber of a support | carrier is a coin lamination type | mold nanographite. The supported amount of Ni contained in this catalyst was 5% by mass based on the total mass of nickel and the coin laminated nanographite as the carrier.
[ Reference Example 1 ]
実施例１の硝酸ニッケルに代えて酢酸パラジウムを用いた以外は、実施例１と同様にして、触媒金属がパラジウムであり、担体のナノ炭素繊維がコイン積層型ナノグラファイトである、パラジウム担持コイン積層型ナノグラファイト触媒を作製した。
〔参考例２〕
A palladium-carrying coin laminate in which the catalytic metal is palladium and the nanocarbon fiber of the carrier is a coin-laminated nanographite in the same manner as in Example 1 except that palladium acetate is used instead of nickel nitrate in Example 1. Type nano-graphite catalyst was prepared.
[ Reference Example 2 ]
コイン積層型ナノグラファイト繊維に代えて、約５〜１０ｎｍ径のカーボンナノチューブを用いた。実施例１と同様にして、触媒金属がニッケルであり、担体のナノ炭素繊維がカーボンナノチューブである、ニッケル担持カーボンナノチューブ触媒を作製した。 Carbon nanotubes having a diameter of about 5 to 10 nm were used in place of the coin laminated nanographite fibers. In the same manner as in Example 1, a nickel-supported carbon nanotube catalyst in which the catalyst metal is nickel and the support nanocarbon fibers are carbon nanotubes was produced.
次に、比較例について説明する。 Next, a comparative example will be described.
シリカ（ＳｉＯ2 ）に硝酸ニッケル水溶液を含浸させ、乾燥の後、大気雰囲気中で５００℃、２時間の焼成を行い、５質量％のニッケルが担持されたニッケル担持シリカ触媒（比較例１とする）を得た。 Silica (SiO 2 ) is impregnated with an aqueous nickel nitrate solution, dried and then calcined in the atmosphere at 500 ° C. for 2 hours to carry a nickel-supported silica catalyst on which 5% by mass of nickel is supported (Comparative Example 1) )
さらに、上記担体のシリカに代えて、ジルコニア（ＺｒＯ2 ）、活性炭、セリア（ＣｅＯ2 ）、チタニア（ＴｉＯ2 ）、アルミナ（Ａｌ2 Ｏ3 ）、及びマグネシア（ＭｇＯ）を担体とした触媒、すなわち、ニッケル担持ジルコニア触媒（比較例２とする）、ニッケル担持活性炭触媒（比較例３とする）、ニッケル担持セリア触媒（比較例４とする）、ニッケル担持チタニア触媒（比較例５とする）、ニッケル担持アルミナ触媒（比較例６とする）、及びニッケル担持マグネシア触媒（比較例７とする）を比較例１と同様な方法で作製した。 Further, instead of the silica of the carrier, a catalyst having zirconia (ZrO 2 ), activated carbon, ceria (CeO 2 ), titania (TiO 2 ), alumina (Al 2 O 3 ), and magnesia (MgO) as a carrier, , Nickel-supported zirconia catalyst (referred to as Comparative Example 2), nickel-supported activated carbon catalyst (referred to as Comparative Example 3), nickel-supported ceria catalyst (referred to as Comparative Example 4), nickel-supported titania catalyst (referred to as Comparative Example 5), nickel A supported alumina catalyst (referred to as Comparative Example 6) and a nickel-supported magnesia catalyst (referred to as Comparative Example 7) were prepared in the same manner as in Comparative Example 1.
次に、上記実施例の金属担持ナノ炭素繊維触媒と比較例の金属担持維触媒の諸特性について比較した。 Next, various characteristics of the metal-supported nanocarbon fiber catalyst of the above example and the metal-supported fiber catalyst of the comparative example were compared.
図２は、実施例１のニッケル担持コイン積層型ナノグラファイト触媒の透過型電子顕微鏡（ＴＥＭ）像を示す図である。図において、樹枝状の構造体はコイン積層型ナノグラファイト繊維であり、樹枝状の構造体に分布した白い粒子はニッケル粒子である。この図から、ニッケル粒子の平均粒径は２．２ｎｍであることがわかる。 FIG. 2 is a transmission electron microscope (TEM) image of the nickel-supported coin laminated nanographite catalyst of Example 1. In the figure, the dendritic structure is a coin laminated nanographite fiber, and the white particles distributed in the dendritic structure are nickel particles. From this figure, it can be seen that the average particle diameter of the nickel particles is 2.2 nm.
同様にＴＥＭ像を用いて、比較例の触媒について平均粒径を求めた。図３は実施例１と比較例１の、ニッケル粒子の平均粒径を比較する図である。この図から、実施例の粒径は２．２ｎｍであるのに対し、比較例の粒径は約５倍大きい、１０．３ｎｍであることがわかる。
Similarly, the average particle diameter was calculated | required about the catalyst of the comparative example using the TEM image. FIG. 3 is a diagram comparing the average particle diameters of nickel particles in Example 1 and Comparative Example 1 . From this figure, whereas the particle size of the embodiment is 2.2 nm, particle diameter of Comparative Example was about 5 times larger, it can be seen that a 10.3 nm.
この結果から、本発明の金属担持ナノ炭素繊維触媒は、従来の触媒に比べて触媒金属の粒径が小さく、典型的には、数ｎｍであることがわかる。この現象は、炭素繊維が約８ｎｍと細いため、炭素繊維の表面の曲率半径が極めて小さく、金属原子が凝集しにくくなるためと考えられる。 From this result, it can be seen that the metal-supported nanocarbon fiber catalyst of the present invention has a catalyst metal particle size smaller than that of the conventional catalyst, typically several nanometers. This phenomenon is thought to be because the carbon fiber is thin, about 8 nm, so that the radius of curvature of the surface of the carbon fiber is extremely small and metal atoms are less likely to aggregate.
次に、実施例と比較例のメタノール分解活性を比較した。 Next, the methanol decomposition activity of an Example and a comparative example was compared.
図４は、メタノール分解活性の測定に用いたメタノール分解反応装置を模式的に示す図である。図において、メタノール分解反応装置２０は、触媒反応部２１と、触媒反応部２１に、触媒反応によって分解されるガスを供給するガス供給部３０と、触媒反応によって生成するガスを回収するガス回収部５０等から構成されている。触媒反応部２１は、本発明の金属担持ナノ炭素繊維触媒２２が収容される反応容器２３と、反応容器２３を加熱する電気炉などからなる加熱手段２４と、加熱手段２４の温度制御を行う温度調節機２５とからなる。ここで、温度調節機２５が、電気配線２５ａ及び測温用熱電対２５ｂを介して加熱手段２４と接続されている。 FIG. 4 is a diagram schematically showing a methanol decomposition reaction apparatus used for measurement of methanol decomposition activity. In the figure, a methanol decomposition reaction apparatus 20 includes a catalyst reaction unit 21, a gas supply unit 30 that supplies a gas to be decomposed by the catalyst reaction to the catalyst reaction unit 21, and a gas recovery unit that recovers a gas generated by the catalyst reaction. 50 or the like. The catalyst reaction unit 21 includes a reaction vessel 23 in which the metal-supported nanocarbon fiber catalyst 22 of the present invention is accommodated, a heating unit 24 including an electric furnace for heating the reaction vessel 23, and a temperature at which the temperature of the heating unit 24 is controlled. And a controller 25. Here, the temperature controller 25 is connected to the heating means 24 via the electric wiring 25a and the thermocouple 25b for temperature measurement.
また、ガス供給部３０は、キャリアーガスであるアルゴンガス３１のアルゴンガス供給部３２と、メタノール供給部３３とからなり、メタノール供給部３３はメタノール蒸発器３４から蒸発したメタノールガス３４ａを吸引するポンプ３５から成る。アルゴンガス３１は、ストップ弁３６、ガス流量調整用のニードル弁３７、アルゴンガス流量計３８、逆止弁３９，４０を介して反応容器２３に供給される。また、メタノール蒸発器３４から蒸発したメタノールガス３４ａは、ポンプ３５に吸引されて、逆止弁４１を介して反応容器２３に供給される。 The gas supply unit 30 includes an argon gas supply unit 32 of an argon gas 31 as a carrier gas and a methanol supply unit 33. The methanol supply unit 33 is a pump that sucks the methanol gas 34a evaporated from the methanol evaporator 34. 35. The argon gas 31 is supplied to the reaction vessel 23 through a stop valve 36, a needle valve 37 for adjusting a gas flow rate, an argon gas flow meter 38, and check valves 39 and 40. The methanol gas 34 a evaporated from the methanol evaporator 34 is sucked into the pump 35 and supplied to the reaction vessel 23 through the check valve 41.
反応ガス回収部５０は、反応容器２３に接続される回収用配管５１と、未反応のメタノールを回収するトラップ５２を有し、反応容器２３から流れ出たガスのうち、未反応のメタノールはトラップ５２で回収され、反応生成ガス５３が分離される。反応生成ガス５３は、図示しないガス分析装置に供給されて、その成分が分析される。 The reaction gas recovery unit 50 includes a recovery pipe 51 connected to the reaction vessel 23 and a trap 52 for recovering unreacted methanol. Among the gases flowing out from the reaction vessel 23, unreacted methanol is trap 52. And the reaction product gas 53 is separated. The reaction product gas 53 is supplied to a gas analyzer (not shown) and its components are analyzed.
ここで、回収用配管５１は、回収用配管５１内で未反応のメタノールガスが凝縮しないようにリボンヒーターなどの回収用配管加熱手段５４により加熱する。未反応のメタノールガスは、氷水などの冷媒５５を用いたトラップ５２により回収され、反応容器２３で発生した反応生成ガス５３だけが、ガス分析装置に供給される。 Here, the recovery pipe 51 is heated by a recovery pipe heating means 54 such as a ribbon heater so that unreacted methanol gas does not condense in the recovery pipe 51. Unreacted methanol gas is recovered by a trap 52 using a refrigerant 55 such as ice water, and only the reaction product gas 53 generated in the reaction vessel 23 is supplied to the gas analyzer.
次に、上記メタノール分解反応装置２０を用いて、実施例の触媒及び比較例の触媒のメタノール分解活性を比較した。 Next, the methanol decomposition activity of the catalyst of an Example and the catalyst of a comparative example was compared using the said methanol decomposition reaction apparatus 20. FIG.
実施例及び比較例の各触媒は、粉末のままでそれぞれ０．２ｇを反応管２２に充填し、反応に供した。供給ガスの組成は、メタノール／アルゴン＝３の混合比で、総流量４０ｃｍ3 ／分の流量で供給した。反応生成ガスをオンラインガスクロマトグラフにより定量分析し、メタノール添加率、すなわち、供給したメタノールのモル数に対する、生成した一酸化炭素と水素のモル数の比を求めた。 Each catalyst of the Examples and Comparative Examples was charged with 0.2 g in the reaction tube 22 in the form of powder and used for the reaction. The composition of the supply gas was a mixture ratio of methanol / argon = 3 and a total flow rate of 40 cm 3 / min. The reaction product gas was quantitatively analyzed by an on-line gas chromatograph, and the methanol addition rate, that is, the ratio of the number of moles of produced carbon monoxide and hydrogen to the number of moles of supplied methanol was determined.
図５は、実施例１及び比較例１のメタノール転化率の反応温度依存性を示す図である。図において、縦軸はメタノール転化率（％）を示し横軸は反応温度（℃）を示している。図から、低温領域においては、実施例１のニッケル担持コイン積層型ナノグラファイト触媒のメタノール転化率は、比較例１のニッケル担持シリカ触媒の転化率に比べて２倍以上大きいことがわかる。また、高温領域においては、実施例１と比較例１のメタノール転化率は互いに接近し、３５０℃でほぼ同等となることがわかる。 FIG. 5 is a graph showing the reaction temperature dependence of the methanol conversion in Example 1 and Comparative Example 1. In the figure, the vertical axis represents the methanol conversion (%) and the horizontal axis represents the reaction temperature (° C.). From the figure, it can be seen that in the low temperature region, the methanol conversion rate of the nickel-supported coin laminated nanographite catalyst of Example 1 is at least twice as high as the conversion rate of the nickel-supported silica catalyst of Comparative Example 1. In addition, in the high temperature region, it can be seen that the methanol conversion rates of Example 1 and Comparative Example 1 are close to each other and are substantially equal at 350 ° C.
低温領域において実施例１の触媒反応速度が大きいのは、実施例１のニッケル担持コイン積層型ナノグラファイト触媒のニッケルの平均粒子径が２．２ｎｍであり、比較例１の場合の１０．３ｎｍと比較して、顕著に平均粒子径が小さく、メタノールの分解反応で高い触媒活性をもたらしているからである。 In the low temperature region, the catalyst reaction rate of Example 1 is large because the nickel-supported coin laminated nanographite catalyst of Example 1 has an average nickel particle size of 2.2 nm, which is 10.3 nm in Comparative Example 1. This is because the average particle size is remarkably small in comparison, and high catalytic activity is brought about by the decomposition reaction of methanol.
また、高温領域において実施例１と比較例１の触媒反応速度が同等になるのは、この温度領域においては、触媒反応速度の温度依存性が、触媒の粒径依存性よりも強くなるためである。 In addition, the catalyst reaction rates of Example 1 and Comparative Example 1 are equal in the high temperature region because the temperature dependency of the catalyst reaction rate is stronger than the particle size dependency of the catalyst in this temperature region. is there.
図６は、実施例１〜３の触媒、及び比較例１〜７の触媒の、反応温度３００℃におけるメタノール転化率を比較する図である。図から明らかなように、実施例１〜３の触媒のメタノール転化率は、それぞれ、９５．１％、９４．６％、８９．６％であり、メタノール転化率が極めて大きいことがわかる。 FIG. 6 is a graph comparing the methanol conversion rates of the catalysts of Examples 1 to 3 and the catalysts of Comparative Examples 1 to 7 at a reaction temperature of 300 ° C. As is apparent from the figure, the methanol conversion rates of the catalysts of Examples 1 to 3 are 95.1%, 94.6%, and 89.6%, respectively, which indicate that the methanol conversion rates are extremely large.
また、比較例１〜４の触媒のメタノール転化率は、それぞれ７８．４％、６９．９％、６０．９％、５１．８％であり、比較例５の触媒のメタノール転化率は、１４．１％で実施例の６分の１以下であり、比較例６及び７の触媒ではメタノール転化率が０％であり、本発明の触媒は、従来のいずれの触媒と比べても、メタノール転化率が大きいことがわかる。 Further, the methanol conversion rates of the catalysts of Comparative Examples 1 to 4 were 78.4%, 69.9%, 60.9%, and 51.8%, respectively. The methanol conversion rate of the catalyst of Comparative Example 5 was 14 1% is less than one-sixth of the example, and the catalysts of Comparative Examples 6 and 7 have a methanol conversion of 0%, and the catalyst of the present invention has a methanol conversion compared to any of the conventional catalysts. It can be seen that the rate is large.
上記結果から、本発明の金属担持ナノ炭素繊維触媒は、従来の触媒より、特に低温において触媒反応速度が大きいことがわかる。 From the above results, it can be seen that the metal-supported nanocarbon fiber catalyst of the present invention has a higher catalytic reaction rate than conventional catalysts, particularly at low temperatures.
本発明の金属担持ナノ炭素繊維触媒を用いれば、従来の触媒に比べて、触媒反応速度が大きいので、例えば、水素や、水素と一酸化炭素の合成ガスを、メタン等の低級炭化水素や、メタノールやエタノール等のアルコール類から生成する化学反応工程に触媒として用いれば、水素や水素と一酸化炭素の合成ガスの製造コストを下げることができる。 When the metal-supported nanocarbon fiber catalyst of the present invention is used, the catalytic reaction rate is higher than that of the conventional catalyst.For example, hydrogen, a synthesis gas of hydrogen and carbon monoxide, a lower hydrocarbon such as methane, If it is used as a catalyst in a chemical reaction step produced from alcohols such as methanol and ethanol, the production cost of hydrogen or a synthesis gas of hydrogen and carbon monoxide can be reduced.
２０：メタノール分解反応装置
２１：触媒反応部
２２：金属担持ナノ炭素繊維触媒
２３：反応容器
２４：反応容器加熱手段
２５：温度調節機
２５ａ：電気配線
２５ｂ：測温用熱電対
３０：ガス供給部
３１：アルゴンガス
３２：アルゴンガス供給部
３３：メタノールガス供給部
３４：メタノール蒸発器
３４ａ：メタノールガス
３５：ポンプ
３６：ストップ弁
３７：ニードル弁
３８：アルゴンガス流量計
３９，４０，４１：逆止弁
５０：反応ガス回収部
５１：回収用配管
５２：トラップ
５３：反応生成ガス
５４：回収用配管加熱手段
５５：冷媒
20: methanol decomposition reaction device 21: catalyst reaction unit 22: metal-supported nanocarbon fiber catalyst 23: reaction vessel 24: reaction vessel heating means 25: temperature controller 25a: electric wiring 25b: thermocouple 30 for temperature measurement: gas supply unit 31: Argon gas 32: Argon gas supply unit 33: Methanol gas supply unit 34: Methanol evaporator
34a: Methanol gas 35: Pump 36: Stop valve 37: Needle valve 38: Argon gas flow meter 39, 40, 41: Check valve 50: Reaction gas recovery section 51: Recovery pipe 52: Trap 53: Reaction product gas 54 : Recovery pipe heating means 55: Refrigerant
Claims (2)
媒を配置し当該触媒を加熱することを特徴とするアルコール分解方法。 An alcohol decomposing method comprising disposing the metal-supported nanocarbon fiber catalyst of claim 1 in an alcohol atmosphere and heating the catalyst.
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