JP2023149308A - Manufacturing method of catalyst - Google Patents
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- 239000003054 catalyst Substances 0.000 title claims abstract description 70
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 40
- 150000001875 compounds Chemical class 0.000 claims abstract description 89
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 54
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 37
- 150000002506 iron compounds Chemical class 0.000 claims abstract description 32
- 239000002904 solvent Substances 0.000 claims abstract description 29
- 229910052742 iron Inorganic materials 0.000 claims abstract description 27
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 21
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 21
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 12
- 230000001590 oxidative effect Effects 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 8
- 235000013980 iron oxide Nutrition 0.000 claims description 19
- -1 organic acid salts Chemical class 0.000 claims description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 6
- 150000003839 salts Chemical class 0.000 claims description 6
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 3
- 150000003841 chloride salts Chemical class 0.000 claims description 3
- 150000004679 hydroxides Chemical class 0.000 claims description 3
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 claims description 3
- 150000002823 nitrates Chemical class 0.000 claims description 3
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 abstract description 16
- 239000004215 Carbon black (E152) Substances 0.000 abstract description 10
- 239000001257 hydrogen Substances 0.000 description 34
- 229910052739 hydrogen Inorganic materials 0.000 description 34
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 32
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 24
- 239000000843 powder Substances 0.000 description 18
- 239000007789 gas Substances 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 15
- 239000000047 product Substances 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 12
- 239000003153 chemical reaction reagent Substances 0.000 description 10
- GLMQHZPGHAPYIO-UHFFFAOYSA-L azanium;2-hydroxypropane-1,2,3-tricarboxylate;iron(2+) Chemical compound [NH4+].[Fe+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O GLMQHZPGHAPYIO-UHFFFAOYSA-L 0.000 description 9
- 239000004313 iron ammonium citrate Substances 0.000 description 9
- 235000000011 iron ammonium citrate Nutrition 0.000 description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 239000007864 aqueous solution Substances 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 238000007654 immersion Methods 0.000 description 7
- 238000000967 suction filtration Methods 0.000 description 7
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 6
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 6
- 238000010298 pulverizing process Methods 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000000292 calcium oxide Substances 0.000 description 4
- 238000006555 catalytic reaction Methods 0.000 description 4
- 230000036571 hydration Effects 0.000 description 4
- 238000006703 hydration reaction Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- JQRLYSGCPHSLJI-UHFFFAOYSA-N [Fe].N1C(C=C2N=C(C=C3NC(=C4)C=C3)C=C2)=CC=C1C=C1C=CC4=N1 Chemical compound [Fe].N1C(C=C2N=C(C=C3NC(=C4)C=C3)C=C2)=CC=C1C=C1C=CC4=N1 JQRLYSGCPHSLJI-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- PLKYGPRDCKGEJH-UHFFFAOYSA-N azane;2-hydroxypropane-1,2,3-tricarboxylic acid;iron Chemical compound N.[Fe].OC(=O)CC(O)(C(O)=O)CC(O)=O PLKYGPRDCKGEJH-UHFFFAOYSA-N 0.000 description 3
- 229940043430 calcium compound Drugs 0.000 description 3
- 150000001674 calcium compounds Chemical class 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 150000007522 mineralic acids Chemical class 0.000 description 3
- 150000007524 organic acids Chemical class 0.000 description 3
- 235000005985 organic acids Nutrition 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 2
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical class [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000010891 electric arc Methods 0.000 description 2
- 150000004677 hydrates Chemical class 0.000 description 2
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000002082 metal nanoparticle Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 229930195734 saturated hydrocarbon Natural products 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 235000002906 tartaric acid Nutrition 0.000 description 2
- 239000011975 tartaric acid Substances 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000010416 ion conductor Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- YWYZEGXAUVWDED-UHFFFAOYSA-N triammonium citrate Chemical compound [NH4+].[NH4+].[NH4+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O YWYZEGXAUVWDED-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、１２ＣａＯ・７Ａｌ2Ｏ3化合物を使用する触媒の製造方法に関する。 The present invention relates to a method for producing a catalyst using a 12CaO.7Al 2 O 3 compound.
特異な結晶構造を有する１２ＣａＯ・７Ａｌ2Ｏ3化合物は、その結晶構造内に酸素イオンラジカルを高濃度に含むことが知られており、酸化触媒、イオン伝導体などの用途に有用であることが提案されている（特許文献１、２、３）。また、アンモニアを合成するための安定で高性能な触媒として利用できること、さらに水素が製造できることが提案されている（特許文献４、５）。 The 12CaO.7Al 2 O 3 compound, which has a unique crystal structure, is known to contain a high concentration of oxygen ion radicals within its crystal structure, and is useful for applications such as oxidation catalysts and ionic conductors. It has been proposed (Patent Documents 1, 2, and 3). It has also been proposed that it can be used as a stable and high-performance catalyst for synthesizing ammonia, and that it can also produce hydrogen (Patent Documents 4 and 5).
特許文献５においては、炭化水素を直接分解して水素を製造するために好適な１２ＣａＯ・７Ａｌ2Ｏ3化合物粒子含有担体に遷移金属が担持した触媒が提案されている。ここで遷移金属として用いられているのは、金属ナノ粒子、特にＮｉナノ粒子である。しかしながら、金属ナノ粒子はその取扱いが難しく、またコストも高いという課題がある。本発明の課題は、優れた炭化水素分解性能を有し、取扱いが簡便であり、かつ経済的な１２ＣａＯ・７Ａｌ2Ｏ3化合物を用いた触媒の製造方法を提供することにある。 Patent Document 5 proposes a catalyst in which a transition metal is supported on a carrier containing 12CaO.7Al 2 O 3 compound particles suitable for directly decomposing hydrocarbons to produce hydrogen. The transition metal used here is metal nanoparticles, especially Ni nanoparticles. However, metal nanoparticles have problems in that they are difficult to handle and are expensive. An object of the present invention is to provide a method for producing a catalyst using a 12CaO.7Al 2 O 3 compound that has excellent hydrocarbon decomposition performance, is easy to handle, and is economical.
そこで本発明者は、１２ＣａＯ・７Ａｌ2Ｏ3化合物を用いた触媒の製造方法を鋭意検討した結果、上記課題を解決し得る製造方法を見出し、本発明を完成した。 Therefore, the inventors of the present invention conducted intensive studies on a method for producing a catalyst using a 12CaO.7Al 2 O 3 compound, and as a result, discovered a production method that could solve the above-mentioned problems, and completed the present invention.
すなわち、本発明は、次の〔１〕～〔５〕を提供するものである。
〔１〕炭化水素を直接分解するための触媒の製造方法であって、
（Ａ）鉄化合物と１２ＣａＯ・７Ａｌ2Ｏ3化合物とを溶媒中に分散させた後、該溶媒を除去することによって、鉄化合物を１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持する工程と、
（Ｂ）前記鉄化合物を担持した１２ＣａＯ・７Ａｌ2Ｏ3化合物を酸化雰囲気中で熱処理することによって、酸化鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態とする工程と、
（Ｃ）工程（Ｂ）後、１２ＣａＯ・７Ａｌ2Ｏ3化合物を還元雰囲気中で熱処理することによって、金属鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態とする工程とを、
具備することを特徴とする触媒の製造方法。
〔２〕前記鉄化合物が、鉄の酸化物、水酸化物、塩化物、硝酸塩、硫酸塩、炭酸塩、有機酸塩及び錯体の群から選ばれる１種以上であることを特徴とする〔１〕の触媒の製造方法。
〔３〕前記鉄化合物が、鉄のオキシカルボン酸塩又はオキシカルボン酸アンモニウム塩であることを特徴とする〔１〕の触媒の製造方法。
〔４〕金属鉄換算の担持量が、１２ＣａＯ・７Ａｌ2Ｏ3化合物１００質量部に対して、１～４０質量部である〔１〕～〔３〕いずれか一に記載の触媒の製造方法。
〔５〕酸化雰囲気中で熱処理され、酸化鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態を経ることを特徴とする、炭化水素直接分解用の鉄－１２ＣａＯ・７Ａｌ2Ｏ3化合物触媒。
That is, the present invention provides the following [1] to [5].
[1] A method for producing a catalyst for directly decomposing hydrocarbons, comprising:
(A) dispersing the iron compound and the 12CaO 7Al 2 O 3 compound in a solvent, and then removing the solvent to support the iron compound on the 12CaO 7Al 2 O 3 compound;
(B) a step of heat-treating the 12CaO.7Al 2 O 3 compound supporting the iron compound in an oxidizing atmosphere so that iron oxide is supported on the 12CaO.7Al 2 O 3 compound;
(C) After step (B), heat-treating the 12CaO.7Al 2 O 3 compound in a reducing atmosphere to make it supported on the 12CaO.7Al 2 O 3 compound as metallic iron;
A method for producing a catalyst, comprising:
[2] The iron compound is one or more selected from the group consisting of iron oxides, hydroxides, chlorides, nitrates, sulfates, carbonates, organic acid salts, and complexes [1] ] Method for producing a catalyst.
[3] The method for producing a catalyst according to [1], wherein the iron compound is an iron oxycarboxylate or an ammonium oxycarboxylate salt.
[4] The method for producing a catalyst according to any one of [1] to [3], wherein the supported amount in terms of metallic iron is 1 to 40 parts by mass based on 100 parts by mass of the 12CaO.7Al 2 O 3 compound.
[5] An iron-12CaO.7Al 2 O 3 compound catalyst for direct decomposition of hydrocarbons, which is heat-treated in an oxidizing atmosphere and supported as iron oxide on a 12CaO.7Al 2 O 3 compound.
本発明の製造方法を用いれば、優れた炭化水素分解性能を有し、取扱いが簡便であり、かつ経済的な１２ＣａＯ・７Ａｌ2Ｏ3化合物を用いた触媒を得ることができる。この触媒を使用して炭化水素を直接分解することによって、効率的に水素を製造することができる。 By using the production method of the present invention, it is possible to obtain a catalyst using a 12CaO.7Al 2 O 3 compound that has excellent hydrocarbon decomposition performance, is easy to handle, and is economical. Hydrogen can be efficiently produced by directly decomposing hydrocarbons using this catalyst.
本発明は、１２ＣａＯ・７Ａｌ2Ｏ3化合物を用いる触媒の製造方法である。具体的には、１２ＣａＯ・７Ａｌ2Ｏ3化合物に鉄化合物を担持した鉄－１２ＣａＯ・７Ａｌ2Ｏ3化合物触媒の製造方法である。以下、詳しく説明する。 The present invention is a method for producing a catalyst using a 12CaO.7Al 2 O 3 compound. Specifically, this is a method for producing an iron-12CaO.7Al 2 O 3 compound catalyst in which an iron compound is supported on a 12CaO.7Al 2 O 3 compound. This will be explained in detail below.
＜１２ＣａＯ・７Ａｌ2Ｏ3化合物の作製＞
１２ＣａＯ・７Ａｌ2Ｏ3化合物は、カルシウム化合物及びアルミニウム化合物の混合物を、酸化雰囲気中で加熱することにより製造することができる。原料として用いるカルシウム化合物としては、酸化カルシウム、水酸化カルシウム、炭酸カルシウム等が挙げられる。また、アルミニウム化合物としては、酸化アルミニウム、水酸化カルシウム等が挙げられる。酸化アルミニウムの結晶構造はα型、γ型のいずれでもよい。原料の混合比率は、酸化物換算のモル比〔（ＣａＯ）／（Ａｌ2Ｏ3）〕で、１．５以上１．９以下が好ましく、１．６以上１．８以下がより好ましく、１．６以上１．７以下がさらに好ましい。
<Preparation of 12CaO・7Al 2 O 3 compound>
The 12CaO.7Al 2 O 3 compound can be produced by heating a mixture of a calcium compound and an aluminum compound in an oxidizing atmosphere. Examples of the calcium compound used as a raw material include calcium oxide, calcium hydroxide, and calcium carbonate. Further, examples of the aluminum compound include aluminum oxide, calcium hydroxide, and the like. The crystal structure of aluminum oxide may be either α-type or γ-type. The mixing ratio of the raw materials is preferably 1.5 or more and 1.9 or less, more preferably 1.6 or more and 1.8 or less, in terms of oxide molar ratio [(CaO)/(Al 2 O 3 )]. More preferably .6 or more and 1.7 or less.
カルシウム化合物及びアルミニウム化合物の混合物の加熱は、酸素雰囲気中で行なわれることが好ましい。酸素雰囲気としては、酸素濃度が２％以上であることが好ましく、２％以上８０％以下がより好ましく、１０％以上３０％以下がさらに好ましい。酸素濃度が約２１％の大気中は好適である。 The heating of the mixture of calcium compound and aluminum compound is preferably carried out in an oxygen atmosphere. The oxygen atmosphere preferably has an oxygen concentration of 2% or more, more preferably 2% or more and 80% or less, and even more preferably 10% or more and 30% or less. An atmosphere with an oxygen concentration of about 21% is suitable.
加熱条件は、最高温度を１２ＣａＯ・７Ａｌ2Ｏ3の溶融温度である１４００℃以上とすることが好ましく、１４００以上２５００℃以下とするのがより好ましく、１４００℃以上１８００℃以下とするのがさらに好ましい。加熱時間は特に限定されるものではないが、原料の混合物の溶け残りがないよう、所定の時間をかけて溶融することが好ましい。例えば、アーク式電気炉で溶融する場合は５分程度保持することが好ましい。また、一般の電気炉で加熱する場合は１４００℃以上の温度で１時間以上維持するのが好ましい。１４００℃以上で加熱することにより、原料化合物が溶融して１２ＣａＯ・７Ａｌ2Ｏ3化合物が生成するので、冷却して固化物とし、得られた固化物を粉砕すれば１２ＣａＯ・７Ａｌ2Ｏ3化合物の粉末が得られる。冷却条件は、特に制限されないが、溶融後の温度が１２００℃以下となるまでは降温速度５０℃／時間以上６００℃／時間以下が好ましい。 As for the heating conditions, the maximum temperature is preferably 1400°C or higher, which is the melting temperature of 12CaO.7Al 2 O 3 , more preferably 1400 to 2500°C, and even more preferably 1400°C to 1800°C. preferable. Although the heating time is not particularly limited, it is preferable to melt the mixture over a predetermined period so that there is no undissolved raw material mixture. For example, when melting is performed in an electric arc furnace, it is preferable to hold the melt for about 5 minutes. Further, when heating in a general electric furnace, it is preferable to maintain the temperature at 1400° C. or higher for 1 hour or more. By heating at 1,400°C or higher, the raw material compound melts and a 12CaO.7Al 2 O 3 compound is produced, so if it is cooled to a solidified product and the obtained solidified product is pulverized, a 12CaO.7Al 2 O 3 compound is produced. powder is obtained. The cooling conditions are not particularly limited, but the temperature decreasing rate is preferably 50° C./hour or more and 600° C./hour or less until the temperature after melting becomes 1200° C. or less.
生成した１２ＣａＯ・７Ａｌ2Ｏ3化合物は、結晶質およびガラス質のいずれでもよい。１２ＣａＯ・７Ａｌ2Ｏ3化合物の純度は５０％以上でその他のカルシウムアルミネート化合物を含んでもよいが、触媒担体として効果的に性能を発揮するためには、１２ＣａＯ・７Ａｌ2Ｏ3化合物の純度が８０％以上であることが好ましい。 The generated 12CaO.7Al 2 O 3 compound may be either crystalline or glassy. The purity of the 12CaO.7Al 2 O 3 compound is 50% or more, and it may contain other calcium aluminate compounds, but in order to effectively perform as a catalyst support, the purity of the 12CaO.7Al 2 O 3 compound must be It is preferably 80% or more.
１２ＣａＯ・７Ａｌ2Ｏ3化合物の粉末度は、触媒活性の観点から、ＢＥＴ比表面積で１ｍ2／ｇ以上であることが好ましく、２ｍ2／ｇ以上であることがより好ましい。粉砕方法としては、乾式粉砕あるいは湿式粉砕いずれの方法でもよいが、微粉砕する場合は、有機溶媒を用いた湿式粉砕が好ましい。例えば、ボールミル、ビーズミル、ジェットミル等による粉砕方法が挙げられる。 The fineness of the 12CaO.7Al 2 O 3 compound is preferably 1 m 2 /g or more, more preferably 2 m 2 /g or more in terms of BET specific surface area, from the viewpoint of catalytic activity. The pulverization method may be either dry pulverization or wet pulverization, but in the case of fine pulverization, wet pulverization using an organic solvent is preferred. For example, pulverization methods using a ball mill, bead mill, jet mill, etc. can be mentioned.
＜触媒の製造方法＞
（Ａ）鉄化合物の担持工程
金属鉄の前駆体となる鉄化合物と、１２ＣａＯ・７Ａｌ2Ｏ3化合物とを溶媒中に分散させ、その後、該溶媒を除去することによって、１２ＣａＯ・７Ａｌ2Ｏ3化合物の粒子表面に担持させる。具体的には、鉄化合物を分散させた溶媒を準備し、この溶媒中に１２ＣａＯ・７Ａｌ2Ｏ3化合物の粉末を添加し、溶媒中に溶解もしくは分散させ、浸漬させる。浸漬時間は５～６０分が好ましい。その後、溶媒を除去することによって、鉄化合物が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物が得られる。
<Catalyst manufacturing method>
(A) Supporting step of iron compound An iron compound serving as a precursor of metallic iron and a 12CaO.7Al 2 O 3 compound are dispersed in a solvent, and then the solvent is removed to support 12CaO.7Al 2 O 3 The compound is supported on the particle surface. Specifically, a solvent in which an iron compound is dispersed is prepared, and a powder of 12CaO.7Al 2 O 3 compound is added to the solvent, dissolved or dispersed in the solvent, and immersed. The immersion time is preferably 5 to 60 minutes. Thereafter, by removing the solvent, a 12CaO.7Al 2 O 3 compound carrying an iron compound is obtained.
溶媒としては、水及び有機溶媒を使用することができる。但し、水を使用する場合は、１２ＣａＯ・７Ａｌ2Ｏ3化合物の水和に留意する必要がある。１２ＣａＯ・７Ａｌ2Ｏ3化合物粒子表面等、一部の水和による水和物の生成は許容されるものの、多量の水和物生成は触媒性能を低下させる要因となるため好ましくない。水を使用する場合は、鉄化合物が分散した水溶液を準備したうえで、１２ＣａＯ・７Ａｌ2Ｏ3化合物を浸漬させた後、速やかに水を蒸発除去することが好ましい。なお、水を使用する場合は、１２ＣａＯ・７Ａｌ2Ｏ3化合物の水和を抑制するための効果を有するセメント用の遅延剤を添加することも好ましい。遅延剤としては、クエン酸、酒石酸等のオキシカルボン酸及びその塩、糖類等が挙げられる。 Water and organic solvents can be used as solvents. However, when using water, it is necessary to pay attention to hydration of the 12CaO.7Al 2 O 3 compound. Although the formation of hydrates due to partial hydration on the surface of the 12CaO.7Al 2 O 3 compound particles is acceptable, the formation of a large amount of hydrates is not preferable because it causes deterioration of catalyst performance. When using water, it is preferable to prepare an aqueous solution in which an iron compound is dispersed, and then immerse the 12CaO.7Al 2 O 3 compound in the solution, and then quickly evaporate and remove the water. In addition, when water is used, it is also preferable to add a retarder for cement that has the effect of suppressing hydration of the 12CaO.7Al 2 O 3 compound. Examples of the retarder include oxycarboxylic acids such as citric acid and tartaric acid, salts thereof, and sugars.
鉄化合物としては、溶媒に可溶性のものが好ましいが、溶媒中に安定した分散状態を確保できるものであれば、特に限定されるものではない。具体的には、鉄の酸化物、水酸化物、塩化物、硝酸塩、硫酸塩、炭酸塩、有機酸塩及び錯体の群から選ばれる１種以上が挙げられる。特に、１２ＣａＯ・７Ａｌ2Ｏ3化合物粒子の安定性の観点から強酸性を示さない鉄の有機酸塩が好ましい。例えば、酢酸塩、クエン酸塩等が挙げられる。中でも、クエン酸塩、酒石酸等のオキシカルボン酸塩、又はオキシカルボン酸アンモニウム塩が好ましい。これらの鉄化合物は１２ＣａＯ・７Ａｌ2Ｏ3化合物に対し遅延剤として作用することで１２ＣａＯ・７Ａｌ2Ｏ3化合物の過剰な水和を抑制する効果を有する点からも好ましい。 The iron compound is preferably one that is soluble in the solvent, but is not particularly limited as long as it can maintain a stable dispersion state in the solvent. Specifically, one or more types selected from the group of iron oxides, hydroxides, chlorides, nitrates, sulfates, carbonates, organic acid salts, and complexes can be mentioned. In particular, from the viewpoint of stability of the 12CaO.7Al 2 O 3 compound particles, organic acid salts of iron that do not exhibit strong acidity are preferred. Examples include acetate, citrate, and the like. Among these, oxycarboxylic acid salts such as citrate and tartaric acid, or ammonium oxycarboxylic acid salts are preferred. These iron compounds are also preferable because they have the effect of suppressing excessive hydration of the 12CaO.7Al 2 O 3 compound by acting as a retarder for the 12CaO.7Al 2 O 3 compound.
溶媒中で浸漬処理後、使用した溶媒は、吸引ろ過等により分離され、あるいは溶媒の沸点以上の温度で蒸発除去され、鉄化合物が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の乾燥粉末（乾固物）が得られる。１２ＣａＯ・７Ａｌ2Ｏ3化合物に対する鉄の担持量としては、金属鉄換算で０．１～４０質量％となるように調製されることが好ましく、１～２０質量％がより好ましい。 After the immersion treatment in the solvent, the used solvent is separated by suction filtration, etc., or evaporated at a temperature higher than the boiling point of the solvent, and a dry powder (dry powder) of the 12CaO 7Al 2 O 3 compound supporting the iron compound is obtained. things) can be obtained. The amount of iron supported on the 12CaO.7Al 2 O 3 compound is preferably adjusted to 0.1 to 40% by mass, more preferably 1 to 20% by mass in terms of metallic iron.
（Ｂ）酸化雰囲気中での熱処理工程
次に、鉄化合物が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物は、酸化雰囲気中で熱処理される。ここで酸化雰囲気とは、酸素、オゾン等の酸化性ガスを含む雰囲気をいう。酸化性ガスの濃度としては、少なくとも１％以上であり、５％以上が好ましく、１０％以上がより好ましい。約２１％の酸素を含む大気は好適である。熱処理温度は、４００～７００℃が好ましく、５００～６００℃がより好ましい。本工程により、使用した鉄化合物中の無機酸、有機酸、結晶水等の成分が分解除去され、酸化鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態となる。また、水溶液中で処理された場合、１２ＣａＯ・７Ａｌ2Ｏ3化合物の粒子表面が水和し、カルシウムアルミネート水和物が一部形成される可能性があるが、この熱処理工程によって水和物は分解され結晶水が除去される。
(B) Heat treatment step in an oxidizing atmosphere Next, the 12CaO.7Al 2 O 3 compound carrying the iron compound is heat treated in an oxidizing atmosphere. The oxidizing atmosphere herein refers to an atmosphere containing oxidizing gases such as oxygen and ozone. The concentration of the oxidizing gas is at least 1% or more, preferably 5% or more, and more preferably 10% or more. An atmosphere containing about 21% oxygen is preferred. The heat treatment temperature is preferably 400 to 700°C, more preferably 500 to 600°C. In this step, components such as inorganic acids, organic acids, and water of crystallization in the iron compound used are decomposed and removed, and iron oxide is supported on the 12CaO.7Al 2 O 3 compound. Furthermore, when treated in an aqueous solution, the particle surface of the 12CaO.7Al 2 O 3 compound may become hydrated and some calcium aluminate hydrate may be formed; is decomposed and water of crystallization is removed.
（Ｃ）還元雰囲気中での熱処理工程
工程（Ｂ）の後に、酸化鉄の状態で担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物を還元雰囲気中で熱処理を行う。ここで還元雰囲気とは、水素、一酸化炭素等の還元性ガスを含む雰囲気をいう。還元性ガスの濃度としては、少なくとも１０％以上であり、５０％以上が好ましく、８０％以上がより好ましい。水素ガス雰囲気が特に好ましい。還元処理温度は、５００～８００℃が好ましく、６００～７００℃がより好ましい。これによって、酸化鉄は還元され、金属鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態となる。
(C) Heat treatment step in reducing atmosphere After step (B), the 12CaO.7Al 2 O 3 compound supported in the state of iron oxide is heat treated in a reducing atmosphere. Here, the reducing atmosphere refers to an atmosphere containing reducing gases such as hydrogen and carbon monoxide. The concentration of the reducing gas is at least 10% or more, preferably 50% or more, and more preferably 80% or more. A hydrogen gas atmosphere is particularly preferred. The reduction treatment temperature is preferably 500 to 800°C, more preferably 600 to 700°C. As a result, the iron oxide is reduced and becomes supported on the 12CaO.7Al 2 O 3 compound as metallic iron.
本発明の触媒を用いれば、炭化水素を直接分解して水素を製造することができる。反応は、メタンガスの場合を例にとれば、ＣＨ4→Ｃ＋２Ｈ2となる。従って、水素とともに生成するのはカーボンであり、原則ＣＯ2やＣＯは副生しない。 By using the catalyst of the present invention, hydrogen can be produced by directly decomposing hydrocarbons. Taking the case of methane gas as an example, the reaction is CH 4 →C+2H 2 . Therefore, carbon is produced together with hydrogen, and in principle, CO 2 and CO are not produced as by-products.
炭化水素としては、飽和炭化水素が好ましく、炭素数１～４の飽和炭化水素がより好ましい。炭化水素の反応温度は、４００℃以上が好ましく、高転化率を維持するためには６００℃以上がより好ましい。また反応温度の上限は１０００℃で十分である。 The hydrocarbon is preferably a saturated hydrocarbon, more preferably a saturated hydrocarbon having 1 to 4 carbon atoms. The hydrocarbon reaction temperature is preferably 400°C or higher, and more preferably 600°C or higher in order to maintain a high conversion rate. Moreover, the upper limit of the reaction temperature is sufficient to be 1000°C.
水素の製造方法としては、例えば、図１に示すようなガス流通触媒反応管を用いて炭化水素から水素を製造することができる。すなわち、触媒を設置した反応管中で炭化水素（メタンガス等）を流通し、触媒と反応させて水素を生成させた後、回収することができる。反応管はヒーター等により４００℃以上に加熱される。 As a method for producing hydrogen, for example, hydrogen can be produced from hydrocarbons using a gas flow catalytic reaction tube as shown in FIG. That is, hydrocarbons (such as methane gas) are passed through a reaction tube equipped with a catalyst, reacted with the catalyst to generate hydrogen, and then recovered. The reaction tube is heated to 400° C. or higher using a heater or the like.
＜鉄－１２ＣａＯ・７Ａｌ2Ｏ3化合物触媒＞
本発明の製造方法によれば、炭化水素分解性能に優れる炭化水素直接分解用の鉄－１２ＣａＯ・７Ａｌ2Ｏ3化合物触媒が得られる。本触媒は、酸化鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態を経ることを特徴とする。そのメカニズムの詳細は不明であるが、酸化雰囲気中での熱処理工程を行い、酸化鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態を経た鉄－１２ＣａＯ・７Ａｌ2Ｏ3化合物触媒において、特に反応初期の炭化水素分解性能に優れる触媒が得られることが判明した。４００℃以上の不活性ガス雰囲気や還元雰囲気中で熱処理した場合でも、鉄化合物中の無機酸、有機酸、結晶水等の成分を分解除去することは可能だが、酸化雰囲気中での熱処理工程を実施せずに、還元雰囲気で熱処理された場合、反応初期の炭化水素分解性能は低くなった。さらに、アルミナを触媒担体とした場合より、１２ＣａＯ・７Ａｌ2Ｏ3化合物を使用した場合の方が本手法の効果が顕著であることが分かった。これは、１２ＣａＯ・７Ａｌ2Ｏ3化合物の特異な結晶構造中に存在するケージ内の「フリー酸素」が関与している可能性が示唆される。
<Iron-12CaO/7Al 2 O 3 compound catalyst>
According to the production method of the present invention, an iron-12CaO.7Al 2 O 3 compound catalyst for direct hydrocarbon decomposition having excellent hydrocarbon decomposition performance can be obtained. This catalyst is characterized in that it undergoes a state in which iron oxide is supported on a 12CaO.7Al 2 O 3 compound. Although the details of the mechanism are unknown, especially in the iron-12CaO.7Al 2 O 3 compound catalyst that has undergone a heat treatment process in an oxidizing atmosphere and has been supported as iron oxide on the 12CaO.7Al 2 O 3 compound, It has been found that a catalyst with excellent hydrocarbon decomposition performance in the initial stage of the reaction can be obtained. Although it is possible to decompose and remove components such as inorganic acids, organic acids, and water of crystallization in iron compounds even when heat-treated in an inert gas atmosphere or reducing atmosphere at 400°C or higher, it is possible to decompose and remove components such as inorganic acids, organic acids, and crystal water. When heat treatment was performed in a reducing atmosphere without carrying out this process, the hydrocarbon decomposition performance at the initial stage of the reaction became low. Furthermore, it was found that the effect of this method is more remarkable when a 12CaO.7Al 2 O 3 compound is used than when alumina is used as a catalyst carrier. This suggests that "free oxygen" within the cage that exists in the unique crystal structure of the 12CaO.7Al 2 O 3 compound may be involved.
本発明の炭化水素直接分解用の鉄－１２ＣａＯ・７Ａｌ2Ｏ3化合物触媒を用いることによって、炭化水素から直接分解により水素を効率よく製造することができる。併せて、水素と共に生成する副生炭素（ナノオーダーのカーボン）も得ることができる。 By using the iron-12CaO.7Al 2 O 3 compound catalyst for direct hydrocarbon decomposition of the present invention, hydrogen can be efficiently produced from hydrocarbons by direct decomposition. In addition, by-product carbon (nano-order carbon) produced together with hydrogen can also be obtained.
次に実施例を挙げて本発明を更に詳細に説明するが、本発明は何らこれらに限定されるものではない。 EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.
＜１２ＣａＯ・７Ａｌ2Ｏ3化合物の作製＞
酸化カルシウムとα型酸化アルミニウムがモル比［ＣａＯ］／［Ａｌ2Ｏ3］＝１．６３となる混合粉末を大気雰囲気中でアーク式電気炉によって溶解させた後室温まで自然冷却し冷却固化物を得た。得られた固化物は、粉末Ｘ線回折により１２ＣａＯ・７Ａｌ2Ｏ3を主相とする回折パターンが確認された。得られた固化物をジェットミルにて粉砕し、１２ＣａＯ・７Ａｌ2Ｏ3化合物粉末を得た。粉体のＢＥＴ比表面積が２．３ｍ2／ｇであった。比表面積測定には窒素ガス吸着測定装置（マイクロトラックベル（株）製ＢＥＬｓｏｒｐ ＭＡＸ）を用いＢＥＴ比表面積として算出した。
<Preparation of 12CaO・7Al 2 O 3 compound>
A mixed powder of calcium oxide and α-type aluminum oxide with a molar ratio [CaO]/[Al 2 O 3 ] = 1.63 is melted in an electric arc furnace in the air, and then naturally cooled to room temperature to form a cooled solidified product. I got it. The obtained solidified product was confirmed to have a diffraction pattern having 12CaO.7Al 2 O 3 as the main phase by powder X-ray diffraction. The obtained solidified product was pulverized with a jet mill to obtain a 12CaO.7Al 2 O 3 compound powder. The BET specific surface area of the powder was 2.3 m 2 /g. The specific surface area was measured using a nitrogen gas adsorption measurement device (BELsorp MAX manufactured by Microtrack Bell Co., Ltd.) and calculated as a BET specific surface area.
＜触媒の作製＞
作製した１２ＣａＯ・７Ａｌ2Ｏ3化合物を触媒担体とし、鉄を担持した触媒を作製した。以下に、各種鉄化合物を使用した実施例および比較例を示す。
<Preparation of catalyst>
Using the prepared 12CaO.7Al 2 O 3 compound as a catalyst carrier, a catalyst supporting iron was prepared. Examples and comparative examples using various iron compounds are shown below.
（実施例１）
クエン酸鉄アンモニウムを鉄化合物として、触媒を作製した。
溶媒として水を使用し、クエン酸鉄アンモニウム（試薬）を水中に溶解させた水溶液を作製した。この水溶液中に、前記１２ＣａＯ・７Ａｌ2Ｏ3化合物粉末を６０分間浸漬させ、浸漬後吸引ろ過にて粉末を回収後５０℃で乾燥を行い、乾固物を得た。なお、クエン酸鉄アンモニウムは、金属鉄換算で１２ＣａＯ・７Ａｌ2Ｏ3化合物に対して５質量％となるように調製した。
次に、前記乾固物を大気中５００℃で加熱処理し、クエン酸鉄アンモニウム中のクエン酸及びアンモニウムを分解除去し、酸化鉄の状態とした。さらに、水素雰囲気中６００℃で加熱処理し、金属鉄が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を得た。
図１の模式構成図に示すガス流通触媒反応管を用い、メタンの直接分解による水素の生成状況を調べた。反応管内に作製した触媒を２．５ｇ設置し、窒素ガス流通雰囲気で７００℃まで昇温した後、８０ｍＬ／ｍｉｎの流速でメタンガスを流し、水素生成特性をガスクロマトグラフィーにて計測した。その結果、メタン流通２０分後の水素生成濃度は、６０．２％であった。
(Example 1)
A catalyst was prepared using iron ammonium citrate as an iron compound.
Using water as a solvent, an aqueous solution was prepared by dissolving iron ammonium citrate (reagent) in water. The 12CaO.7Al 2 O 3 compound powder was immersed in this aqueous solution for 60 minutes, and after the immersion, the powder was collected by suction filtration and dried at 50° C. to obtain a dry solid. Note that ammonium iron citrate was prepared to have an amount of 5% by mass based on the 12CaO.7Al 2 O 3 compound in terms of metallic iron.
Next, the dried product was heat-treated at 500° C. in the atmosphere to decompose and remove citric acid and ammonium in the iron ammonium citrate, thereby converting it into iron oxide. Further, heat treatment was performed at 600° C. in a hydrogen atmosphere to obtain a catalyst of 12CaO.7Al 2 O 3 compound on which metallic iron was supported.
Using the gas flow catalytic reaction tube shown in the schematic diagram of FIG. 1, the production of hydrogen by direct decomposition of methane was investigated. After placing 2.5 g of the prepared catalyst in a reaction tube and raising the temperature to 700° C. in a nitrogen gas flowing atmosphere, methane gas was flowed at a flow rate of 80 mL/min, and hydrogen production characteristics were measured by gas chromatography. As a result, the hydrogen production concentration after 20 minutes of methane flow was 60.2%.
（実施例２）
酸化鉄を鉄化合物として、触媒を作製した。
溶媒として水を使用し、酸化鉄（III）（試薬）を水中に分散させた分散液を作製した。この水溶液中に、前記１２ＣａＯ・７Ａｌ2Ｏ3化合物粉末を６０分間浸漬させ、浸漬後吸引ろ過にて粉末を回収後５０℃で乾燥を行い、乾固物を得た。なお、酸化鉄は、金属鉄換算で１２ＣａＯ・７Ａｌ2Ｏ3化合物に対して１０質量％となるように調製した。
次に、前記乾固物を大気中５００℃で加熱処理し、さらに、水素雰囲気中６００℃で加熱処理し、金属鉄が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を得た。
ガス流通触媒反応管内に作製した触媒を２．５ｇ設置し、実施例１と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、４２．８％であった。
(Example 2)
A catalyst was prepared using iron oxide as an iron compound.
Using water as a solvent, a dispersion of iron (III) oxide (reagent) in water was prepared. The 12CaO.7Al 2 O 3 compound powder was immersed in this aqueous solution for 60 minutes, and after the immersion, the powder was collected by suction filtration and dried at 50° C. to obtain a dry solid. Note that the iron oxide was prepared to be 10% by mass based on the 12CaO.7Al 2 O 3 compound in terms of metallic iron.
Next, the dried product was heat-treated at 500° C. in the air and further heat-treated at 600° C. in a hydrogen atmosphere to obtain a 12CaO.7Al 2 O 3 compound catalyst on which metallic iron was supported.
2.5 g of the prepared catalyst was placed in the gas flow catalyst reaction tube, and the hydrogen production characteristics were measured in the same manner as in Example 1. As a result, the hydrogen production concentration after 20 minutes of methane flow was 42.8%.
（実施例３）
クエン酸鉄アンモニウムを鉄化合物として、触媒を作製した。
溶媒としてヘキサン（試薬）を使用し、クエン酸鉄アンモニウム（試薬）をヘキサン中に分散させた分散液を作製した。この溶媒中に、前記１２ＣａＯ・７Ａｌ2Ｏ3化合物粉末を６０分間浸漬させ、浸漬後吸引ろ過にて粉末を回収後５０℃で乾燥を行い、乾固物を得た。なお、クエン酸鉄アンモニウムは、金属鉄換算で１２ＣａＯ・７Ａｌ2Ｏ3に対して１０質量％となるように調製した。
次に、前記乾固物を大気中５００℃で加熱処理し、クエン酸鉄アンモニウム中のクエン酸及びアンモニウムを分解除去し、酸化鉄の状態とした。さらに、水素雰囲気中６００℃で加熱処理し、金属鉄が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を得た。
ガス流通触媒反応管内に作製した触媒を２．５ｇ設置し、実施例１と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、６０．０％であった。
(Example 3)
A catalyst was prepared using iron ammonium citrate as an iron compound.
Using hexane (reagent) as a solvent, a dispersion liquid in which iron ammonium citrate (reagent) was dispersed in hexane was prepared. The 12CaO.7Al 2 O 3 compound powder was immersed in this solvent for 60 minutes, and after the immersion, the powder was collected by suction filtration and dried at 50° C. to obtain a dried product. Note that ammonium iron citrate was prepared to have an amount of 10% by mass based on 12CaO.7Al 2 O 3 in terms of metallic iron.
Next, the dried product was heat-treated at 500° C. in the atmosphere to decompose and remove citric acid and ammonium in the iron ammonium citrate, thereby converting it into iron oxide. Further, heat treatment was performed at 600° C. in a hydrogen atmosphere to obtain a catalyst of 12CaO.7Al 2 O 3 compound on which metallic iron was supported.
2.5 g of the prepared catalyst was placed in the gas flow catalyst reaction tube, and the hydrogen production characteristics were measured in the same manner as in Example 1. As a result, the hydrogen production concentration after 20 minutes of methane flow was 60.0%.
（実施例４）
クエン酸鉄アンモニウムを、金属鉄換算で１２ＣａＯ・７Ａｌ2Ｏ3化合物に対して３質量％となるように調製した以外は、実施例３と同様に１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を作製した。
ガス流通触媒反応管内に作製した触媒を２．５ｇ設置し、実施例３と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、２７．６％であった。
(Example 4)
A catalyst for the 12CaO 7Al 2 O 3 compound was prepared in the same manner as in Example 3, except that ferrous ammonium citrate was prepared to be 3% by mass relative to the 12CaO 7Al 2 O 3 compound in terms of metallic iron. .
2.5 g of the prepared catalyst was placed in the gas flow catalyst reaction tube, and the hydrogen production characteristics were measured in the same manner as in Example 3. As a result, the hydrogen production concentration after 20 minutes of methane flow was 27.6%.
（実施例５）
鉄ポルフィリン錯体を鉄化合物として、触媒を作製した。
溶媒としてアセトン（試薬）を使用し、鉄ポルフィリン錯体（試薬）をアセトン中に分散させた溶媒を作製した。この溶媒中に、前記１２ＣａＯ・７Ａｌ2Ｏ3化合物粉末を６０分間浸漬させ、浸漬後吸引ろ過にて粉末を回収後５０℃で乾燥を行い、乾固物を得た。なお、鉄ポルフィリン錯体は、金属鉄換算で１２ＣａＯ・７Ａｌ2Ｏ3化合物に対して１０質量％となるように調製した。
次に、前記乾固物を大気中５００℃で加熱処理し、さらに、水素雰囲気中６００℃で加熱処理し、金属鉄が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を得た。
ガス流通触媒反応管内に作製した触媒を２．５ｇ設置し、実施例１と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、３０．７％であった。
(Example 5)
A catalyst was prepared using an iron porphyrin complex as an iron compound.
Acetone (reagent) was used as a solvent, and a solvent was prepared by dispersing an iron porphyrin complex (reagent) in acetone. The 12CaO.7Al 2 O 3 compound powder was immersed in this solvent for 60 minutes, and after the immersion, the powder was collected by suction filtration and dried at 50° C. to obtain a dried product. Note that the iron porphyrin complex was prepared to have a concentration of 10% by mass based on the 12CaO.7Al 2 O 3 compound in terms of metallic iron.
Next, the dried product was heat-treated at 500° C. in the air and further heat-treated at 600° C. in a hydrogen atmosphere to obtain a 12CaO.7Al 2 O 3 compound catalyst on which metallic iron was supported.
2.5 g of the prepared catalyst was placed in the gas flow catalyst reaction tube, and the hydrogen production characteristics were measured in the same manner as in Example 1. As a result, the hydrogen production concentration after 20 minutes of methane flow was 30.7%.
（実施例６）
酸化鉄を鉄化合物として、触媒を作製した。
溶媒としてアセトン（試薬）を使用し、酸化鉄（III）（試薬）をアセトン中に分散させた溶媒を作製した。この溶媒中に、前記１２ＣａＯ・７Ａｌ2Ｏ3化合物粉末を６０分間浸漬させ、浸漬後吸引ろ過にて粉末を回収後５０℃で乾燥を行い、乾固物を得た。なお、酸化鉄は、金属鉄換算で１２ＣａＯ・７Ａｌ2Ｏ3化合物に対して１０質量％となるように調製した。
次に、前記乾固物を大気中５００℃で加熱処理し、さらに、水素雰囲気中６００℃で加熱処理し、金属鉄が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を得た。
ガス流通触媒反応管内に作製した触媒を２．５ｇ設置し、実施例１と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、４６．２％であった。
(Example 6)
A catalyst was prepared using iron oxide as an iron compound.
Using acetone (reagent) as a solvent, a solvent was prepared in which iron (III) oxide (reagent) was dispersed in acetone. The 12CaO.7Al 2 O 3 compound powder was immersed in this solvent for 60 minutes, and after the immersion, the powder was collected by suction filtration and dried at 50° C. to obtain a dried product. Note that the iron oxide was prepared to be 10% by mass based on the 12CaO.7Al 2 O 3 compound in terms of metallic iron.
Next, the dried product was heat-treated at 500° C. in the air and further heat-treated at 600° C. in a hydrogen atmosphere to obtain a 12CaO.7Al 2 O 3 compound catalyst on which metallic iron was supported.
2.5 g of the prepared catalyst was placed in the gas flow catalyst reaction tube, and the hydrogen production characteristics were measured in the same manner as in Example 1. As a result, the hydrogen production concentration after 20 minutes of methane flow was 46.2%.
（比較例１）
大気中５００℃で加熱処理を実施しないこと以外は、実施例１と同様にして金属鉄が担持された１２ＣａＯ・７Ａｌ2Ｏ3化合物の触媒を作製した。
ガス流通触媒反応管内に作製した触媒を設置し、実施例１と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、１５．３％であった。
(Comparative example 1)
A catalyst of 12CaO.7Al 2 O 3 compound on which metallic iron was supported was prepared in the same manner as in Example 1 except that the heat treatment was not performed at 500° C. in the atmosphere.
The prepared catalyst was installed in a gas flow catalytic reaction tube, and hydrogen production characteristics were measured in the same manner as in Example 1. As a result, the hydrogen production concentration after 20 minutes of methane flow was 15.3%.
（比較例２）
触媒担体として、アルミナを使用して試験を実施した。鉄化合物としては、クエン酸鉄アンモニウムを使用して触媒を作製した。
溶媒として水を使用し、クエン酸鉄アンモニウム（試薬）を水中に分散させた水溶液を作製した。この水溶液中に、アルミナ粉末（試薬：α型酸化アルミニウム）を６０分間浸漬後吸引ろ過にて粉末を回収後５０℃で乾燥を行い、乾固物を得た。なお、クエン酸鉄アンモニウムは、金属鉄換算でアルミナに対して１０質量％となるように調製した。
次に、前記乾固物を大気中５００℃で加熱処理し、クエン酸鉄アンモニウム中のクエン酸及びアンモニウムを分解除去し、酸化鉄の状態とした。さらに、水素雰囲気中６００℃で加熱処理し、金属鉄が担持されたアルミナの触媒を得た。
ガス流通触媒反応管内に作製した触媒を２．５ｇ設置し、実施例１と同様にして、水素生成特性を計測した。その結果、メタン流通２０分後の水素生成濃度は、２２．１％であった。
(Comparative example 2)
Tests were conducted using alumina as the catalyst support. A catalyst was prepared using iron ammonium citrate as the iron compound.
Using water as a solvent, an aqueous solution was prepared by dispersing iron ammonium citrate (reagent) in water. Alumina powder (reagent: α-type aluminum oxide) was immersed in this aqueous solution for 60 minutes, the powder was collected by suction filtration, and then dried at 50° C. to obtain a dried product. Note that ammonium iron citrate was prepared to have an amount of 10% by mass based on alumina in terms of metallic iron.
Next, the dried product was heat-treated at 500° C. in the atmosphere to decompose and remove citric acid and ammonium in the iron ammonium citrate, thereby converting it into iron oxide. Further, heat treatment was performed at 600° C. in a hydrogen atmosphere to obtain an alumina catalyst on which metallic iron was supported.
2.5 g of the prepared catalyst was placed in the gas flow catalyst reaction tube, and the hydrogen production characteristics were measured in the same manner as in Example 1. As a result, the hydrogen production concentration after 20 minutes of methane flow was 22.1%.
Claims (5)
（Ａ）鉄化合物と１２ＣａＯ・７Ａｌ2Ｏ3化合物とを溶媒中に分散させた後、該溶媒を除去することによって、鉄化合物を１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持する工程と、
（Ｂ）前記鉄化合物を担持した１２ＣａＯ・７Ａｌ2Ｏ3化合物を酸化雰囲気中で熱処理することによって、酸化鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態とする工程と、
（Ｃ）工程（Ｂ）後、１２ＣａＯ・７Ａｌ2Ｏ3化合物を還元雰囲気中で熱処理することによって、金属鉄として１２ＣａＯ・７Ａｌ2Ｏ3化合物に担持された状態とする工程とを、
具備することを特徴とする触媒の製造方法。 A method for producing a catalyst for directly decomposing hydrocarbons, the method comprising:
(A) dispersing the iron compound and the 12CaO 7Al 2 O 3 compound in a solvent, and then removing the solvent to support the iron compound on the 12CaO 7Al 2 O 3 compound;
(B) a step of heat-treating the 12CaO.7Al 2 O 3 compound supporting the iron compound in an oxidizing atmosphere so that iron oxide is supported on the 12CaO.7Al 2 O 3 compound;
(C) After step (B), heat-treating the 12CaO.7Al 2 O 3 compound in a reducing atmosphere to make it supported on the 12CaO.7Al 2 O 3 compound as metallic iron;
A method for producing a catalyst, comprising:
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