WO2023189197A1 - Method for producing fine metal particles - Google Patents

Method for producing fine metal particles Download PDF

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WO2023189197A1
WO2023189197A1 PCT/JP2023/007950 JP2023007950W WO2023189197A1 WO 2023189197 A1 WO2023189197 A1 WO 2023189197A1 JP 2023007950 W JP2023007950 W JP 2023007950W WO 2023189197 A1 WO2023189197 A1 WO 2023189197A1
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metal particles
temperature
gas
metal
producing fine
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PCT/JP2023/007950
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French (fr)
Japanese (ja)
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敦 田中
聡信 安武
崇史 久保田
正志 清澤
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三菱重工業株式会社
三菱パワー株式会社
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Publication of WO2023189197A1 publication Critical patent/WO2023189197A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/745—Iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/30—Making metallic powder or suspensions thereof using chemical processes with decomposition of metal compounds, e.g. by pyrolysis

Definitions

  • the present disclosure relates to a method for manufacturing fine metal particles.
  • This disclosure claims priority based on Japanese Patent Application No. 2022-055626 filed with the Japan Patent Office on March 30, 2022, the contents of which are incorporated herein by reference.
  • Techniques for atomizing metals include pulverization of solid metals and an atomization method in which molten metal is cooled by injection (for example, see Patent Document 1).
  • Patent Document 1 many conventional techniques are techniques for atomizing metal particles to a particle size on the order of micrometers, and are not suitable for atomizing metal particles to a particle size on the order of submicrons.
  • Patent application No. 2021-177811 discloses a method for atomizing metal particles to a particle size on the order of micrometers.
  • metals can be refined to submicron-order particle sizes; It is desired to refine metals to submicron-order grain sizes.
  • At least one embodiment of the present disclosure aims to provide a method for producing fine metal particles that can efficiently atomize metal to a particle size on the submicron order.
  • a method for producing fine metal particles according to the present disclosure includes a step of preparing metal particles, and a step of supplying a supply gas containing a hydrocarbon to the metal particles.
  • the contact with the metal particles is carried out in a temperature range of 600° C. to 900° C., and during the contact of said feed gas with said metal particles, the temperature within said temperature range is reduced to below 600° C. and then again within said temperature range. Increase the temperature within.
  • the metal particles function as a catalyst for a reaction that directly decomposes hydrocarbons into carbon and hydrogen.
  • grain boundaries are created in the metal particles due to hydrogen erosion by the generated hydrogen, and from these grain boundaries, microparticles migrate from the metal particles and react with the generated carbon to form metal carbide. be done.
  • hydrogen erodes the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order.
  • the generated carbon is dissolved in the metal in the temperature range of 600°C to 900°C, but when the temperature is lowered to below 600°C, the solubility of carbon in the metal decreases, and the carbon is removed from the metal.
  • the metal particles are destroyed when the carbon is forced out of the metal, the metal particles are made more fine than if the temperature were not lowered. This improves the catalytic activity after the temperature is raised again to the temperature range of 600° C. to 900° C., so that the metal can be efficiently atomized to a particle size on the submicron order.
  • FIG. 1 is a schematic configuration diagram of an apparatus for carrying out a method for producing fine metal particles according to an embodiment of the present disclosure.
  • FIG. 1 is a schematic diagram illustrating the configuration of an experimental apparatus for verifying the effects of a method for producing fine metal particles according to an embodiment of the present disclosure.
  • 1 is a graph showing changes over time in feed gas conversion rates in experiments of Examples 1 and 2 and Comparative Examples 1 and 2.
  • 2 is a graph showing changes in feed gas conversion before and after temperature reduction in experiments of Examples 1 and 2.
  • the metal As hydrogen erodes, the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order. In this way, the metal can be atomized to a particle size on the submicron order.
  • the prior application exemplifies iron, nickel, cobalt, or an alloy of at least two of these metals as metals that can be made fine. Based on this knowledge, in the present disclosure, a method for producing fine metal particles that can further efficiently atomize metal to a particle size on the submicron order will be described below.
  • an apparatus 1 for carrying out a method for producing fine metal particles according to an embodiment of the present disclosure includes a reactor 3 containing metal particles 2 to be atomized.
  • the reactor 3 is provided with a heating device 4 (for example, a jacket through which steam flows) for heating the inside of the reactor 3, particularly the metal particles 2.
  • the reactor 3 is connected to a supply line 5 for supplying a feed gas containing hydrocarbons to the reactor 3, and an outflow gas distribution line 6 through which outflow gas flowing out from the reactor 3 flows.
  • the metal forming the metal particles 2 is iron, nickel, cobalt, or an alloy of at least two of these.
  • the supplied gas may contain only hydrocarbons, but may also contain an inert gas (nitrogen or rare gas) in addition to hydrocarbons.
  • the hydrocarbon may be methane alone or a mixture of methane and at least one type of hydrocarbon containing two or more carbons (ethane, ethylene, propane, etc.). When such a mixture is used as a hydrocarbon to be directly cracked, the composition of the mixture is preferably 90 vol% methane and 10 vol% at least one hydrocarbon containing two or more carbons.
  • a reactor 3 contains metal particles 2 to be atomized.
  • a feed gas is fed into the reactor 3 via the feed line 5, and the feed gas is brought into contact with the metal particles 2 within the reactor 3.
  • hydrocarbons in the supplied gas are directly decomposed into hydrogen and carbon by the catalytic action of the metal particles 2.
  • methane as an example of the hydrocarbon in this decomposition reaction (also referred to as "direct decomposition reaction")
  • a reaction represented by the following reaction formula (1) occurs in the reactor 3. CH 4 ⁇ 2H 2 +C ... (1)
  • the temperature is lowered to below 600°C, and then raised again to a range of 600°C to 900°C. Since it takes several hours for the activity of Reaction Formula (1) to rise sufficiently, the timing of lowering the temperature is preferably after the activity of Reaction Formula (1) has sufficiently increased. If the time required for the activity of reaction formula (1) to sufficiently increase is known from experience, the temperature may be lowered after that time has elapsed from the start of the reaction. If such time is not known, the change in hydrocarbon conversion rate over time can be determined by periodically sampling the effluent gas flowing through the effluent gas distribution line 6 and analyzing the composition of the effluent gas with a gas chromatograph. Therefore, the timing to lower the temperature can be determined from this change over time.
  • the metal particles 2 function as a catalyst for a reaction that directly decomposes hydrocarbons into carbon and hydrogen
  • grain boundaries are formed in the metal particles due to hydrogen erosion by the generated hydrogen, and these grain boundaries
  • fine particles migrate from the metal particles and react with the generated carbon to form metal carbide.
  • the generated carbon is dissolved in the metal in the temperature range of 600°C to 900°C, but when the temperature is lowered to below 600°C, the solubility of carbon in the metal decreases, and the carbon is removed from the metal. be chased out.
  • the metal particles are destroyed when the carbon is forced out of the metal, the metal particles are made more fine than if the temperature were not lowered. This improves the catalytic activity after the temperature is raised again to the temperature range of 600° C. to 900° C., so that the metal can be efficiently atomized to a particle size on the submicron order.
  • FIG. 2 shows the configuration of an experimental apparatus used in the experiments conducted for the verification.
  • the experimental apparatus 20 includes a reactor 23 made of quartz and having an inner diameter of 16 mm and housing therein a perforated plate 28 on which metal particles 2 are placed.
  • the reactor 23 can be heated with an electric furnace 24.
  • the reactor 23 includes a supply line 25 for supplying a supply gas or argon, and an effluent gas line 25 through which the effluent gas containing hydrogen generated by the direct decomposition reaction of hydrocarbons contained in the supply gas flows after leaving the reactor 23.
  • a distribution line 26 is connected thereto.
  • the effluent gas flow line 26 is connected to a gas chromatograph 27 for measuring the composition of the effluent gas.
  • Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1 below.
  • the metal particles 2 electrolytic iron particles available from Nilaco Co., Ltd. were used.
  • the electrolytic iron particles have an average particle size of 45 ⁇ m and an iron purity of 99% by mass.
  • H 0 is the number of hydrogen atoms possessed by the supply gas
  • H 1 is the number of hydrogen atoms possessed by the hydrocarbon gas in the reaction gas.
  • the number of hydrogen atoms possessed by each gas can be calculated from the respective gas composition and flow rate.
  • FIG. 3 shows the changes over time in the feed gas conversion rates of Examples 1 and 2 and Comparative Examples 1 and 2.
  • Examples 1 and 2 8 hours after supplying the supply gas into the reactor 23 (after starting the direct decomposition reaction), the supply of the supply gas was stopped and the temperature was lowered to 25 ° C. Thereafter, the temperature was raised to 800° C. again, and then the supply of gas was restarted, but in FIG. 3, the period of this operation is not counted in the elapsed time. That is, the plot after the plot 8 hours after supplying the supply gas into the reactor 23 is the plot after this operation is finished and the direct decomposition reaction is restarted. Therefore, in FIG.
  • FIG. 4 shows a comparison between the feed gas conversion rate immediately before the temperature drop started and the feed gas conversion rate when the direct decomposition reaction was restarted after the temperature drop in each of Examples 1 and 2. From FIG. 4, it was found that reducing the temperature to 25° C. during direct decomposition of hydrocarbons, and then returning the temperature to the baseline and restarting the direct decomposition reaction increases the feed gas conversion. It was also found that the effect of increasing the feed gas conversion rate was greater when using a feed gas containing hydrocarbons containing 2 or more carbons than when using only methane as the feed gas. .
  • the feed gas conversion after this operation can be increased. is higher than the feed gas conversion rate before this operation, so it can be said that the metal can be efficiently atomized to a particle size on the submicron order.
  • the method for producing fine metal particles includes: preparing metal particles; supplying a feed gas comprising a hydrocarbon to the metal particles; The contact between the feed gas and the metal particles is carried out at a temperature range of 600°C to 900°C, During contact of the feed gas with the metal particles, the temperature within the temperature range is lowered to less than 600° C. and then raised again to the temperature within the temperature range.
  • the metal particles function as a catalyst for a reaction that directly decomposes hydrocarbons into carbon and hydrogen.
  • grain boundaries are created in the metal particles due to hydrogen erosion by the generated hydrogen, and from these grain boundaries, microparticles migrate from the metal particles and react with the generated carbon to form metal carbide. be done.
  • hydrogen erodes the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order.
  • the generated carbon is dissolved in the metal in the temperature range of 600°C to 900°C, but when the temperature is lowered to below 600°C, the solubility of carbon in the metal decreases, and the carbon is removed from the metal.
  • the metal particles are destroyed when the carbon is forced out of the metal, the metal particles are made more fine than if the temperature were not lowered. This improves the catalytic activity after the temperature is raised again to the temperature range of 600° C. to 900° C., so that the metal can be efficiently atomized to a particle size on the submicron order.
  • a method for producing fine metal particles according to another aspect is the method for producing fine metal particles according to [1], comprising: measuring the conversion of hydrocarbons; When the measured conversion rate is equal to or higher than a predetermined set value, the temperature within the temperature range is lowered to less than 600°C, and then the temperature is raised again to the temperature within the temperature range.
  • the temperature is lowered and then raised again.
  • a larger amount of carbon is expelled from the metal, so that the metal becomes finer.
  • the metal can be efficiently atomized to a particle size on the submicron order.
  • a method for producing fine metal particles according to yet another aspect is the method for producing fine metal particles according to [1] or [2], comprising:
  • the supply gas is 90 vol% methane, 10 vol% of hydrocarbons containing two or more carbons.
  • hydrocarbons containing two or more carbon atoms are more easily decomposed than methane, so metals can be more efficiently converted to submicron particles than when using only methane as a feed gas. It can be atomized to a particle size of the order of magnitude.
  • a method for producing fine metal particles according to yet another aspect is the method for producing fine metal particles according to any one of [1] to [3], comprising:
  • the metal forming the metal particles is iron, nickel, cobalt, or an alloy of at least two of these.
  • fine metal particles made of iron, nickel, cobalt, or an alloy of at least two of these can be obtained.

Abstract

This method for producing fine metal particles comprises: a step for preparing metal particles; and a step for supplying supply gas that contains hydrocarbon to the metal particles, wherein the supply gas and the metal particles are put in contact with each other in the temperature range of 600-900°C, and while the supply gas and the metal particles are in contact with each other, the temperature in the temperature range is decreased to lower than 600°C and thereafter increased to a temperature in the temperature range.

Description

微細金属粒子の製造方法Method for producing fine metal particles
　本開示は、微細金属粒子の製造方法に関する。
　本開示は、２０２２年３月３０日に日本国特許庁に出願された特願２０２２－０５５６２６号に基づき優先権を主張し、その内容をここに援用する。 The present disclosure relates to a method for manufacturing fine metal particles.
This disclosure claims priority based on Japanese Patent Application No. 2022-055626 filed with the Japan Patent Office on March 30, 2022, the contents of which are incorporated herein by reference.
　金属を微粒化する技術として、固体金属の粉砕や、溶融した金属を噴射冷却するアトマイズ法（例えば、特許文献１参照）等がある。しかしながら、従来の多くの技術はマイクロメートルオーダーの粒径までの微粒化技術であり、サブミクロンオーダーの粒径まで金属を微粒化することには不向きである。これに対し、本開示の発明者らの研究により、金属粒子を触媒として炭化水素の直接分解を行うと、金属がサブミクロンオーダーの粒径まで微細化できることを明らかにしている（本願出願人により出願された特願２０２１－１７７８１１号）。 Techniques for atomizing metals include pulverization of solid metals and an atomization method in which molten metal is cooled by injection (for example, see Patent Document 1). However, many conventional techniques are techniques for atomizing metal particles to a particle size on the order of micrometers, and are not suitable for atomizing metal particles to a particle size on the order of submicrons. On the other hand, research by the inventors of the present disclosure has revealed that when hydrocarbons are directly decomposed using metal particles as a catalyst, metals can be refined to submicron-order particle diameters (according to the applicant). (Patent application No. 2021-177811).
特開２０１８－１４１２２３号公報（００３１段落）JP2018-141223A (paragraph 0031)
　しかしながら、本開示の発明者らの研究では、金属粒子を触媒として炭化水素の直接分解を行うことにより、金属がサブミクロンオーダーの粒径まで微細化できることは明らかになったものの、さらに効率的に金属をサブミクロンオーダーの粒径まで微細化することが望まれている。 However, research by the inventors of the present disclosure has revealed that by directly decomposing hydrocarbons using metal particles as a catalyst, metals can be refined to submicron-order particle sizes; It is desired to refine metals to submicron-order grain sizes.
　上述の事情に鑑みて、本開示の少なくとも１つの実施形態は、効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる微細金属粒子の製造方法を提供することを目的とする。 In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a method for producing fine metal particles that can efficiently atomize metal to a particle size on the submicron order.
　上記目的を達成するため、本開示に係る微細金属粒子の製造方法は、金属粒子を準備するステップと、炭化水素を含む供給ガスを前記金属粒子に供給するステップとを含み、前記供給ガスと前記金属粒子との接触は６００℃～９００℃の温度範囲で行われ、前記供給ガスと前記金属粒子との接触中に、前記温度範囲内の温度を６００℃未満に低下した後、再び前記温度範囲内の温度に上昇させる。 In order to achieve the above object, a method for producing fine metal particles according to the present disclosure includes a step of preparing metal particles, and a step of supplying a supply gas containing a hydrocarbon to the metal particles. The contact with the metal particles is carried out in a temperature range of 600° C. to 900° C., and during the contact of said feed gas with said metal particles, the temperature within said temperature range is reduced to below 600° C. and then again within said temperature range. Increase the temperature within.
　本開示の微細金属粒子の製造方法によれば、炭化水素をカーボン及び水素に直接分解する反応の触媒として金属粒子が機能する。この触媒作用の過程で、生成した水素による水素侵食によって金属粒子に粒界が生じ、この粒界を起点として、金属粒子から微粒子がマイグレーションにより移動し、生成したカーボンと反応して金属カーバイドが形成される。水素侵食に伴って金属のカーバイド化が進行し、サブミクロンオーダーの粒径の微粒子に分割されていく。生成したカーボンは、６００℃～９００℃の温度範囲では金属中に溶解しているが、温度を６００℃未満に低下する間に、金属へのカーボンの溶解度が低下することによりカーボンが金属の外に追い出される。カーボンが金属の外に追い出される際に金属粒子が破壊されるので、温度を低下させない場合に比べて、金属粒子がより微細化される。これにより、温度を再び６００℃～９００℃の温度範囲に上昇させた後の触媒活性が向上するので、効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる。 According to the method for producing fine metal particles of the present disclosure, the metal particles function as a catalyst for a reaction that directly decomposes hydrocarbons into carbon and hydrogen. In the process of this catalytic action, grain boundaries are created in the metal particles due to hydrogen erosion by the generated hydrogen, and from these grain boundaries, microparticles migrate from the metal particles and react with the generated carbon to form metal carbide. be done. As hydrogen erodes, the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order. The generated carbon is dissolved in the metal in the temperature range of 600°C to 900°C, but when the temperature is lowered to below 600°C, the solubility of carbon in the metal decreases, and the carbon is removed from the metal. be chased out. Since the metal particles are destroyed when the carbon is forced out of the metal, the metal particles are made more fine than if the temperature were not lowered. This improves the catalytic activity after the temperature is raised again to the temperature range of 600° C. to 900° C., so that the metal can be efficiently atomized to a particle size on the submicron order.
本開示の一実施形態に係る微細金属粒子の製造方法を実施するための装置の構成模式図である。FIG. 1 is a schematic configuration diagram of an apparatus for carrying out a method for producing fine metal particles according to an embodiment of the present disclosure. 本開示の一実施形態に係る微細金属粒子の製造方法の効果を検証するための実験装置の構成模式図である。FIG. 1 is a schematic diagram illustrating the configuration of an experimental apparatus for verifying the effects of a method for producing fine metal particles according to an embodiment of the present disclosure. 実施例１及び２並びに比較例１及び２の実験における供給ガス転化率の経時変化を示すグラフである。1 is a graph showing changes over time in feed gas conversion rates in experiments of Examples 1 and 2 and Comparative Examples 1 and 2. 実施例１及び２の実験において、温度低下前後の供給ガス転化率の変化を示すグラフである。2 is a graph showing changes in feed gas conversion before and after temperature reduction in experiments of Examples 1 and 2.
　以下、本開示の実施形態による微細金属粒子の製造方法について、図面に基づいて説明する。以下で説明する実施形態は、本開示の一態様を示すものであり、この開示を限定するものではなく、本開示の技術的思想の範囲内で任意に変更可能である。 Hereinafter, a method for manufacturing fine metal particles according to an embodiment of the present disclosure will be described based on the drawings. The embodiment described below shows one aspect of the present disclosure, does not limit this disclosure, and can be arbitrarily modified within the scope of the technical idea of the present disclosure.
＜本開示の発明者らの先行研究による知見＞
　本願出願人の先願（特願２０２１－１７７８１１号）では、６００℃～９００℃の温度で金属粒子に炭化水素を含むガスを接触させることで、金属をサブミクロンオーダーの粒径まで微細化できることを明らかにした。この方法では、炭化水素をカーボン及び水素に直接分解する反応の触媒として金属粒子が機能する。この触媒作用の過程で、生成した水素による水素侵食によって金属粒子に粒界が生じ、この粒界を起点として、金属粒子から微粒子がマイグレーションにより移動し、生成したカーボンと反応して金属カーバイドが形成される。水素侵食に伴って金属のカーバイド化が進行し、サブミクロンオーダーの粒径の微粒子に分割されていく。このようにして、金属をサブミクロンオーダーの粒径まで微粒化することができる。先願では、微細化できる金属として、鉄、ニッケル、コバルト、又はこれらのうちの少なくとも２つの合金を例示している。この知見に基づき、本開示では以下において、さらに効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる微細金属粒子の製造方法を説明する。 <Findings from prior research by the inventors of the present disclosure>
In the applicant's previous application (Japanese Patent Application No. 2021-177811), it was discovered that by bringing a gas containing hydrocarbon into contact with metal particles at a temperature of 600°C to 900°C, metals can be refined to a submicron-order particle size. revealed. In this method, metal particles act as catalysts for reactions that directly decompose hydrocarbons into carbon and hydrogen. In the process of this catalytic action, grain boundaries are created in the metal particles due to hydrogen erosion by the generated hydrogen, and from these grain boundaries, microparticles migrate from the metal particles and react with the generated carbon to form metal carbide. be done. As hydrogen erodes, the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order. In this way, the metal can be atomized to a particle size on the submicron order. The prior application exemplifies iron, nickel, cobalt, or an alloy of at least two of these metals as metals that can be made fine. Based on this knowledge, in the present disclosure, a method for producing fine metal particles that can further efficiently atomize metal to a particle size on the submicron order will be described below.
＜本開示の一実施形態に係る微細金属粒子の製造方法を実施するための装置の構成＞
　図１に示されるように、本開示の一実施形態に係る微細金属粒子の製造方法を実施するための装置１は、微粒化される金属粒子２が収容された反応器３を備えている。反応器３には、反応器３の内部、特に金属粒子２を昇温するための加熱装置４（例えば、スチームが流通するジャケット等）が設けられている。反応器３には、炭化水素を含む供給ガスを反応器３に供給するための供給ライン５と、反応器３から流出する流出ガスが流通する流出ガス流通ライン６とが接続されている。 <Configuration of apparatus for carrying out the method for producing fine metal particles according to an embodiment of the present disclosure>
As shown in FIG. 1, an apparatus 1 for carrying out a method for producing fine metal particles according to an embodiment of the present disclosure includes a reactor 3 containing metal particles 2 to be atomized. The reactor 3 is provided with a heating device 4 (for example, a jacket through which steam flows) for heating the inside of the reactor 3, particularly the metal particles 2. The reactor 3 is connected to a supply line 5 for supplying a feed gas containing hydrocarbons to the reactor 3, and an outflow gas distribution line 6 through which outflow gas flowing out from the reactor 3 flows.
　金属粒子２を形成する金属は、鉄、ニッケル、コバルト、又はこれらのうちの少なくとも２つの合金である。また、供給ガスは炭化水素のみを含んでもよいが、炭化水素の他に不活性ガス（窒素又は希ガス）を含んでもよい。さらに、炭化水素としては、メタンのみでもよいし、メタンと２以上の炭素を含む少なくとも１種類の炭化水素（エタン、エチレン、プロパン等）との混合物であってもよい。このような混合物を直接分解される炭化水素として使用する場合、混合物の組成は、メタンが９０ｖｏｌ％であるとともに２以上の炭素を含む少なくとも１種類の炭化水素が１０ｖｏｌ％であることが好ましい。 The metal forming the metal particles 2 is iron, nickel, cobalt, or an alloy of at least two of these. Further, the supplied gas may contain only hydrocarbons, but may also contain an inert gas (nitrogen or rare gas) in addition to hydrocarbons. Furthermore, the hydrocarbon may be methane alone or a mixture of methane and at least one type of hydrocarbon containing two or more carbons (ethane, ethylene, propane, etc.). When such a mixture is used as a hydrocarbon to be directly cracked, the composition of the mixture is preferably 90 vol% methane and 10 vol% at least one hydrocarbon containing two or more carbons.
＜本開示の一実施形態に係る微細金属粒子の製造方法＞
　次に、本開示の一実施形態に係る微細金属粒子の製造方法について説明する。反応器３内に、微粒化される金属粒子２を収容する。次に、供給ライン５を介して反応器３内に供給ガスを供給し、反応器３内で供給ガスを金属粒子２に接触させる。この際、供給ガス中の炭化水素は、金属粒子２の触媒作用によって水素とカーボンに直接分解される。この分解反応（「直接分解反応」とも言う）における炭化水素としてメタンを例にすると、下記の反応式（１）で表される反応が反応器３内で生じる。
　　ＣＨ４→２Ｈ２＋Ｃ　・・・（１）
　尚、この分解反応を促進するために、加熱装置４によって金属粒子２の温度を６００℃～９００℃の範囲に維持することが好ましい。 <Method for manufacturing fine metal particles according to an embodiment of the present disclosure>
Next, a method for manufacturing fine metal particles according to an embodiment of the present disclosure will be described. A reactor 3 contains metal particles 2 to be atomized. Next, a feed gas is fed into the reactor 3 via the feed line 5, and the feed gas is brought into contact with the metal particles 2 within the reactor 3. At this time, hydrocarbons in the supplied gas are directly decomposed into hydrogen and carbon by the catalytic action of the metal particles 2. Taking methane as an example of the hydrocarbon in this decomposition reaction (also referred to as "direct decomposition reaction"), a reaction represented by the following reaction formula (1) occurs in the reactor 3.
CH 4 → 2H 2 +C ... (1)
In order to promote this decomposition reaction, it is preferable to maintain the temperature of the metal particles 2 in the range of 600° C. to 900° C. using the heating device 4.
　本開示の製造方法では、供給ガスと金属粒子２との接触中に、温度を６００℃未満に低下した後、再び６００℃～９００℃の範囲に上昇させる。反応式（１）の活性が十分に上がるまでには数時間がかかることから、温度を低下させるタイミングについては、反応式（１）の活性が十分に上がった後が好ましい。反応式（１）の活性が十分に上がるまでに必要な時間が経験上分かっている場合は、反応開始からその時間が経過した後に温度を低下すればよい。そのような時間が分かっていない場合には、流出ガス流通ライン６を流通する流出ガスを定期的にサンプリングし、ガスクロマトグラフで流出ガスの組成を分析することにより、炭化水素の転化率の経時変化が得られるので、この経時変化から、温度を下げるタイミングを決定することができる。 In the manufacturing method of the present disclosure, during the contact between the supply gas and the metal particles 2, the temperature is lowered to below 600°C, and then raised again to a range of 600°C to 900°C. Since it takes several hours for the activity of Reaction Formula (1) to rise sufficiently, the timing of lowering the temperature is preferably after the activity of Reaction Formula (1) has sufficiently increased. If the time required for the activity of reaction formula (1) to sufficiently increase is known from experience, the temperature may be lowered after that time has elapsed from the start of the reaction. If such time is not known, the change in hydrocarbon conversion rate over time can be determined by periodically sampling the effluent gas flowing through the effluent gas distribution line 6 and analyzing the composition of the effluent gas with a gas chromatograph. Therefore, the timing to lower the temperature can be determined from this change over time.
　本開示の製造方法によれば、金属粒子２が炭化水素をカーボン及び水素に直接分解する反応の触媒として機能する過程で、生成した水素による水素侵食によって金属粒子に粒界が生じ、この粒界を起点として、金属粒子から微粒子がマイグレーションにより移動し、生成したカーボンと反応して金属カーバイドが形成される。水素侵食に伴って金属のカーバイド化が進行し、サブミクロンオーダーの粒径の微粒子に分割されていく。生成したカーボンは、６００℃～９００℃の温度範囲では金属中に溶解しているが、温度を６００℃未満に低下する間に、金属へのカーボンの溶解度が低下することによりカーボンが金属の外に追い出される。カーボンが金属の外に追い出される際に金属粒子が破壊されるので、温度を低下させない場合に比べて、金属粒子がより微細化される。これにより、温度を再び６００℃～９００℃の温度範囲に上昇させた後の触媒活性が向上するので、効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる。尚、反応式（１）の活性が十分に上がった後に温度を下げることが好ましいと述べたが、鉄の内部に溶解したカーボンが温度の低下によって析出することで活性が向上することからすれば、必ずしも活性が十分に上がった後でなくても、活性が十分に上がる前、少なくとも活性の発現を確認できた後であれば、同様の効果が得られると考えられる。 According to the manufacturing method of the present disclosure, in the process in which the metal particles 2 function as a catalyst for a reaction that directly decomposes hydrocarbons into carbon and hydrogen, grain boundaries are formed in the metal particles due to hydrogen erosion by the generated hydrogen, and these grain boundaries Using this as a starting point, fine particles migrate from the metal particles and react with the generated carbon to form metal carbide. As hydrogen erodes, the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order. The generated carbon is dissolved in the metal in the temperature range of 600°C to 900°C, but when the temperature is lowered to below 600°C, the solubility of carbon in the metal decreases, and the carbon is removed from the metal. be chased out. Since the metal particles are destroyed when the carbon is forced out of the metal, the metal particles are made more fine than if the temperature were not lowered. This improves the catalytic activity after the temperature is raised again to the temperature range of 600° C. to 900° C., so that the metal can be efficiently atomized to a particle size on the submicron order. As mentioned above, it is preferable to lower the temperature after the activity of reaction formula (1) has sufficiently increased, but considering that carbon dissolved inside the iron precipitates as the temperature decreases, the activity improves. It is thought that similar effects can be obtained not necessarily after the activity has sufficiently increased, but before the activity has sufficiently increased, or at least after the expression of the activity has been confirmed.
＜実験装置の構成＞
　後述する実施例１及び２並びに比較例１及び２によって、本開示の製造方法の作用効果を検証するが、その検証のために行われる実験で使用する実験装置の構成を図２に示す。実験装置２０は、金属粒子２を載置した目皿２８を内部に収容する内径１６ｍｍの石英製の反応器２３を備えている。反応器２３は、電気炉２４で加熱可能になっている。反応器２３には、供給ガス又はアルゴンを供給するための供給ライン２５と、供給ガスに含まれる炭化水素の直接分解反応によって生成した水素を含む流出ガスが反応器２３から流出後に流通する流出ガス流通ライン２６とが接続されている。流出ガス流通ライン２６は、流出ガスの組成を測定するためのガスクロマトグラフ２７に接続されている。 <Configuration of experimental equipment>
The effects of the manufacturing method of the present disclosure will be verified using Examples 1 and 2 and Comparative Examples 1 and 2, which will be described later. FIG. 2 shows the configuration of an experimental apparatus used in the experiments conducted for the verification. The experimental apparatus 20 includes a reactor 23 made of quartz and having an inner diameter of 16 mm and housing therein a perforated plate 28 on which metal particles 2 are placed. The reactor 23 can be heated with an electric furnace 24. The reactor 23 includes a supply line 25 for supplying a supply gas or argon, and an effluent gas line 25 through which the effluent gas containing hydrogen generated by the direct decomposition reaction of hydrocarbons contained in the supply gas flows after leaving the reactor 23. A distribution line 26 is connected thereto. The effluent gas flow line 26 is connected to a gas chromatograph 27 for measuring the composition of the effluent gas.
＜実験方法＞
　次に、実施例１及び２並びに比較例１及び２の実験方法について説明する。この実験装置２０において、金属粒子２を反応器２３内の目皿２８上に設置した後、反応器２３内をアルゴンで置換した。次に、反応器２３内にアルゴンを流通させながら、電気炉２４を起動して、反応器２３内を８００℃まで昇温した。反応器２３内の温度が８００℃となったら、反応器２３内に供給するガスを供給ガスに切り替えて、炭化水素を直接分解する実験を行った。 <Experimental method>
Next, experimental methods for Examples 1 and 2 and Comparative Examples 1 and 2 will be explained. In this experimental apparatus 20, after the metal particles 2 were placed on the perforated plate 28 in the reactor 23, the inside of the reactor 23 was replaced with argon. Next, while flowing argon into the reactor 23, the electric furnace 24 was started and the temperature inside the reactor 23 was raised to 800°C. When the temperature inside the reactor 23 reached 800° C., an experiment was conducted in which the gas supplied into the reactor 23 was switched to a supply gas to directly decompose hydrocarbons.
　実施例１及び２については、反応器２３内に供給するガスを供給ガスに切り替えてから８時間経過後に、電気炉２４を停止し、反応器２３内に供給するガスをアルゴンに切り替えることによって反応器２３内をアルゴンで置換した。１～４時間放置することで、反応器２３内の温度が２５℃となった。１０時間後、反応器２３内にアルゴンを流通させながら、電気炉２４を起動して、反応器２３内の温度を１００℃／ｍｉｎの昇温速度で８００℃まで昇温した。反応器２３内の温度が８００℃となったら、反応器２３内に供給するガスを供給ガスに切り替えて、炭化水素を直接分解する実験を再開した。比較例１及び２については、反応容器２３内の温度を低下せず、実験終了まで８００℃を維持した。 Regarding Examples 1 and 2, 8 hours after switching the gas supplied into the reactor 23 to the supply gas, the electric furnace 24 was stopped and the reaction was started by switching the gas supplied into the reactor 23 to argon. The inside of the vessel 23 was replaced with argon. By leaving it for 1 to 4 hours, the temperature inside the reactor 23 reached 25°C. After 10 hours, while flowing argon into the reactor 23, the electric furnace 24 was started and the temperature inside the reactor 23 was raised to 800°C at a rate of 100°C/min. When the temperature inside the reactor 23 reached 800° C., the gas supplied into the reactor 23 was switched to the supply gas, and the experiment for directly decomposing hydrocarbons was restarted. In Comparative Examples 1 and 2, the temperature inside the reaction vessel 23 was not lowered and was maintained at 800° C. until the end of the experiment.
　実施例１及び２並びに比較例１及び２の実験条件を下記表１に示す。尚、金属粒子２として、株式会社ニラコから入手可能な電解鉄製粒子を使用した。この電解鉄製粒子は、平均粒径が４５μｍであり、鉄の純度は９９質量％である。 The experimental conditions of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1 below. As the metal particles 2, electrolytic iron particles available from Nilaco Co., Ltd. were used. The electrolytic iron particles have an average particle size of 45 μm and an iron purity of 99% by mass.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１及び２並びに比較例１及び２のそれぞれの直接分解反応の実験において、ガスクロマトグラフ２７によって測定された反応ガスの組成から、下記式（２）によって、供給ガス転化率ＣＲ［％］を算出した。
　　ＣＲ＝（１－Ｈ１／Ｈ０）×１００　・・・（２）
ここで、Ｈ０は供給ガスが持つ水素原子数であり、Ｈ１は反応ガス中の炭化水素ガスが持つ水素原子数である。それぞれのガスが持つ水素原子数は、それぞれのガス組成と流量とから算出することができる。 In the direct decomposition reaction experiments of Examples 1 and 2 and Comparative Examples 1 and 2, the feed gas conversion rate CR [%] was calculated from the composition of the reaction gas measured by the gas chromatograph 27 using the following formula (2). Calculated.
CR=(1-H 1 /H 0 )×100 (2)
Here, H 0 is the number of hydrogen atoms possessed by the supply gas, and H 1 is the number of hydrogen atoms possessed by the hydrocarbon gas in the reaction gas. The number of hydrogen atoms possessed by each gas can be calculated from the respective gas composition and flow rate.
　実施例１及び２並びに比較例１及び２のそれぞれの供給ガス転化率の経時変化を図３に示す。実施例１及び２では、反応器２３内に供給ガスを供給してから（直接分解反応を開始してから）８時間経過後に、供給ガスの供給を停止して温度を２５℃まで低下し、その後再び８００℃まで昇温してから供給ガスの供給を再開しているが、図３ではこの操作の期間は経時時間にカウントしていない。すなわち、反応器２３内に供給ガスを供給してから８時間後のプロットの後のプロットは、この操作が終わって直接分解反応が再開した後のプロットとなっている。このため、図３では、実施例１及び２における供給ガス転化率の経時変化は、反応器２３内に供給ガスを供給してから８時間後に急変するようになっている。実施例１及び２のそれぞれと比較例１及び２のそれぞれとを比較すると、反応器２３内に供給ガスを供給してから８時間経過後の供給ガス転化率が増加している。 FIG. 3 shows the changes over time in the feed gas conversion rates of Examples 1 and 2 and Comparative Examples 1 and 2. In Examples 1 and 2, 8 hours after supplying the supply gas into the reactor 23 (after starting the direct decomposition reaction), the supply of the supply gas was stopped and the temperature was lowered to 25 ° C. Thereafter, the temperature was raised to 800° C. again, and then the supply of gas was restarted, but in FIG. 3, the period of this operation is not counted in the elapsed time. That is, the plot after the plot 8 hours after supplying the supply gas into the reactor 23 is the plot after this operation is finished and the direct decomposition reaction is restarted. Therefore, in FIG. 3, the change over time in the feed gas conversion rate in Examples 1 and 2 suddenly changes 8 hours after the feed gas is supplied into the reactor 23. Comparing each of Examples 1 and 2 with each of Comparative Examples 1 and 2, the feed gas conversion rate after 8 hours has passed since the feed gas was supplied into the reactor 23 is increased.
　図４には、実施例１及び２のそれぞれにおいて、温度低下開始直前の供給ガス転化率と温度低下後に直接分解反応を再開した時の供給ガス転化率との比較を示す。図４から、炭化水素の直接分解中に温度を２５℃まで低下し、その後温度を基に戻して直接分解反応を再開することで、供給ガス転化率が上昇することがわかった。また、供給ガス転化率が上昇する効果は、供給ガスとしてメタンのみを使用した場合に比べて、２以上の炭素を含む炭化水素を含んだ供給ガスを使用した場合の方が大きいこともわかった。 FIG. 4 shows a comparison between the feed gas conversion rate immediately before the temperature drop started and the feed gas conversion rate when the direct decomposition reaction was restarted after the temperature drop in each of Examples 1 and 2. From FIG. 4, it was found that reducing the temperature to 25° C. during direct decomposition of hydrocarbons, and then returning the temperature to the baseline and restarting the direct decomposition reaction increases the feed gas conversion. It was also found that the effect of increasing the feed gas conversion rate was greater when using a feed gas containing hydrocarbons containing 2 or more carbons than when using only methane as the feed gas. .
　したがって、６００℃～９００℃の温度範囲で炭化水素を直接分解している間に温度を２５℃に低下した後に再び温度を元の温度範囲に戻すことによって、この操作の後における供給ガス転化率がこの操作前における供給ガス転化率よりも上昇するので、効率的に金属をサブミクロンオーダーの粒径まで微粒化することができると言える。 Therefore, by reducing the temperature to 25°C during direct cracking of hydrocarbons in the temperature range of 600°C to 900°C and then returning the temperature to the original temperature range, the feed gas conversion after this operation can be increased. is higher than the feed gas conversion rate before this operation, so it can be said that the metal can be efficiently atomized to a particle size on the submicron order.
　上記各実施形態に記載の内容は、例えば以下のように把握される。 The contents described in each of the above embodiments can be understood as follows, for example.
［１］一の態様に係る微細金属粒子の製造方法は、
　金属粒子を準備するステップと、
　炭化水素を含む供給ガスを前記金属粒子に供給するステップと
を含み、
　前記供給ガスと前記金属粒子との接触は６００℃～９００℃の温度範囲で行われ、
　前記供給ガスと前記金属粒子との接触中に、前記温度範囲内の温度を６００℃未満に低下した後、再び前記温度範囲内の温度に上昇させる。 [1] The method for producing fine metal particles according to one embodiment includes:
preparing metal particles;
supplying a feed gas comprising a hydrocarbon to the metal particles;
The contact between the feed gas and the metal particles is carried out at a temperature range of 600°C to 900°C,
During contact of the feed gas with the metal particles, the temperature within the temperature range is lowered to less than 600° C. and then raised again to the temperature within the temperature range.
　本開示の微細金属粒子の製造方法によれば、炭化水素をカーボン及び水素に直接分解する反応の触媒として金属粒子が機能する。この触媒作用の過程で、生成した水素による水素侵食によって金属粒子に粒界が生じ、この粒界を起点として、金属粒子から微粒子がマイグレーションにより移動し、生成したカーボンと反応して金属カーバイドが形成される。水素侵食に伴って金属のカーバイド化が進行し、サブミクロンオーダーの粒径の微粒子に分割されていく。生成したカーボンは、６００℃～９００℃の温度範囲では金属中に溶解しているが、温度を６００℃未満に低下する間に、金属へのカーボンの溶解度が低下することによりカーボンが金属の外に追い出される。カーボンが金属の外に追い出される際に金属粒子が破壊されるので、温度を低下させない場合に比べて、金属粒子がより微細化される。これにより、温度を再び６００℃～９００℃の温度範囲に上昇させた後の触媒活性が向上するので、効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる。 According to the method for producing fine metal particles of the present disclosure, the metal particles function as a catalyst for a reaction that directly decomposes hydrocarbons into carbon and hydrogen. In the process of this catalytic action, grain boundaries are created in the metal particles due to hydrogen erosion by the generated hydrogen, and from these grain boundaries, microparticles migrate from the metal particles and react with the generated carbon to form metal carbide. be done. As hydrogen erodes, the metal progresses to become carbide and is divided into fine particles with a particle size on the submicron order. The generated carbon is dissolved in the metal in the temperature range of 600°C to 900°C, but when the temperature is lowered to below 600°C, the solubility of carbon in the metal decreases, and the carbon is removed from the metal. be chased out. Since the metal particles are destroyed when the carbon is forced out of the metal, the metal particles are made more fine than if the temperature were not lowered. This improves the catalytic activity after the temperature is raised again to the temperature range of 600° C. to 900° C., so that the metal can be efficiently atomized to a particle size on the submicron order.
［２］別の態様に係る微細金属粒子の製造方法は、［１］の微細金属粒子の製造方法であって、
　炭化水素の転化率を測定するステップを含み、
　測定された前記転化率が予め決められた設定値以上となったら、前記温度範囲内の温度を６００℃未満に低下した後、再び前記温度範囲内の温度に上昇させる。 [2] A method for producing fine metal particles according to another aspect is the method for producing fine metal particles according to [1], comprising:
measuring the conversion of hydrocarbons;
When the measured conversion rate is equal to or higher than a predetermined set value, the temperature within the temperature range is lowered to less than 600°C, and then the temperature is raised again to the temperature within the temperature range.
　このような製造方法によれば、十分な量のカーボンが生成された後に、温度の低下及び再度の上昇を行うことになる。そうすると、不十分な量のカーボンしか生成されていないときのこの動作を行う場合に比べて、カーボンが金属の外に追い出される量が多いので、金属がより微細化される。これにより、効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる。 According to such a manufacturing method, after a sufficient amount of carbon is generated, the temperature is lowered and then raised again. In this case, compared to performing this operation when only an insufficient amount of carbon is generated, a larger amount of carbon is expelled from the metal, so that the metal becomes finer. Thereby, the metal can be efficiently atomized to a particle size on the submicron order.
［３］さらに別の態様に係る微細金属粒子の製造方法は、［１］または［２］の微細金属粒子の製造方法であって、
　前記供給ガスは、
　９０ｖｏｌ％のメタンと、
　１０ｖｏｌ％の２以上の炭素を含む炭化水素と
を含む。 [3] A method for producing fine metal particles according to yet another aspect is the method for producing fine metal particles according to [1] or [2], comprising:
The supply gas is
90 vol% methane,
10 vol% of hydrocarbons containing two or more carbons.
　このような製造方法によれば、２以上の炭素を含む炭化水素の方がメタンに比べて分解しやすいので、メタンのみの供給ガスを使用した場合に比べて、より効率的に金属をサブミクロンオーダーの粒径まで微粒化することができる。 According to this production method, hydrocarbons containing two or more carbon atoms are more easily decomposed than methane, so metals can be more efficiently converted to submicron particles than when using only methane as a feed gas. It can be atomized to a particle size of the order of magnitude.
［４］さらに別の態様に係る微細金属粒子の製造方法は、［１］～［３］のいずれかの微細金属粒子の製造方法であって、
　前記金属粒子を形成する金属は、鉄、ニッケル、コバルト、又はこれらのうちの少なくとも２つの合金である。 [4] A method for producing fine metal particles according to yet another aspect is the method for producing fine metal particles according to any one of [1] to [3], comprising:
The metal forming the metal particles is iron, nickel, cobalt, or an alloy of at least two of these.
　このような製造構成によれば、鉄製、ニッケル製、コバルト製、又はこれらのうちの少なくとも２つの合金製の微細金属粒子を得ることができる。 According to such a manufacturing configuration, fine metal particles made of iron, nickel, cobalt, or an alloy of at least two of these can be obtained.
２　金属粒子 2 Metal particles

Claims (4)

  1. 　金属粒子を準備するステップと、
    　炭化水素を含む供給ガスを前記金属粒子に供給するステップと
    を含み、
    　前記供給ガスと前記金属粒子との接触は６００℃～９００℃の温度範囲で行われ、
    　前記供給ガスと前記金属粒子との接触中に、前記温度範囲内の温度を６００℃未満に低下した後、再び前記温度範囲内の温度に上昇させる、微細金属粒子の製造方法。     preparing metal particles;
    supplying a feed gas comprising a hydrocarbon to the metal particles;
    The contact between the feed gas and the metal particles is carried out at a temperature range of 600°C to 900°C,
    A method for producing fine metal particles, wherein during contact of the supply gas with the metal particles, the temperature within the temperature range is lowered to below 600°C, and then the temperature is raised again to the temperature within the temperature range.
  2. 　炭化水素の転化率を測定するステップを含み、
    　測定された前記転化率が予め決められた設定値以上となったら、前記温度範囲内の温度を６００℃未満に低下した後、再び前記温度範囲内の温度に上昇させる、請求項１に記載の微細金属粒子の製造方法。     measuring the conversion of hydrocarbons;
    When the measured conversion rate is equal to or higher than a predetermined set value, the temperature within the temperature range is lowered to less than 600°C, and then the temperature is raised again to the temperature within the temperature range. Method for producing fine metal particles.
  3. 　前記供給ガスは、
    　９０ｖｏｌ％のメタンと、
    　１０ｖｏｌ％の２以上の炭素を含む炭化水素と
    を含む、請求項１または２に記載の微細金属粒子の製造方法。     The supply gas is
    90 vol% methane,
    The method for producing fine metal particles according to claim 1 or 2, comprising 10 vol% of a hydrocarbon containing two or more carbons.
  4. 　前記金属粒子を形成する金属は、鉄、ニッケル、コバルト、又はこれらのうちの少なくとも２つの合金である、請求項１または２に記載の微細金属粒子の製造方法。 The method for producing fine metal particles according to claim 1 or 2, wherein the metal forming the metal particles is iron, nickel, cobalt, or an alloy of at least two of these.
PCT/JP2023/007950 2022-03-30 2023-03-03 Method for producing fine metal particles WO2023189197A1 (en)

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JP2001321670A (en) * 2000-05-17 2001-11-20 Japan Steel Works Ltd:The Hydrocarbon decomposing material and hydrocarbon decomposing device
JP2007527348A (en) * 2003-11-21 2007-09-27 スタットオイル エイエスエイ Method for converting hydrocarbons
JP2006043645A (en) * 2004-08-06 2006-02-16 Asao Tada Catalyst for direct decomposition of lower hydrocarbon
JP2006096590A (en) * 2004-09-28 2006-04-13 Asao Tada Apparatus for directly cracking lower hydrocarbon
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