JP2011224554A - Catalyst for decomposing ammonia, method for producing the catalyst, and method for producing hydrogen using the catalyst - Google Patents
Catalyst for decomposing ammonia, method for producing the catalyst, and method for producing hydrogen using the catalyst Download PDFInfo
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 136
- 239000003054 catalyst Substances 0.000 title claims abstract description 125
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 66
- 238000004519 manufacturing process Methods 0.000 title claims description 35
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims description 28
- 239000001257 hydrogen Substances 0.000 title claims description 21
- 229910052739 hydrogen Inorganic materials 0.000 title claims description 21
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 51
- 239000010941 cobalt Substances 0.000 claims abstract description 51
- 239000000654 additive Substances 0.000 claims abstract description 37
- 229910052751 metal Inorganic materials 0.000 claims abstract description 15
- 150000001875 compounds Chemical class 0.000 claims abstract description 14
- 230000000737 periodic effect Effects 0.000 claims abstract description 5
- 238000000354 decomposition reaction Methods 0.000 claims description 40
- 230000000996 additive effect Effects 0.000 claims description 36
- 239000000126 substance Substances 0.000 claims description 31
- 239000007864 aqueous solution Substances 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000002244 precipitate Substances 0.000 claims description 24
- 239000010419 fine particle Substances 0.000 claims description 22
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 13
- 229910044991 metal oxide Inorganic materials 0.000 claims description 12
- 239000002243 precursor Substances 0.000 claims description 10
- 150000004706 metal oxides Chemical class 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 8
- 239000002131 composite material Substances 0.000 claims description 7
- 239000006185 dispersion Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 5
- -1 lanthanoid metal oxides Chemical class 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 claims description 3
- 150000001868 cobalt Chemical class 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- 229910052747 lanthanoid Inorganic materials 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 150000004696 coordination complex Chemical class 0.000 claims 1
- 239000002184 metal Substances 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 9
- 229910000510 noble metal Inorganic materials 0.000 abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 37
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 18
- 229910052757 nitrogen Inorganic materials 0.000 description 16
- 239000007789 gas Substances 0.000 description 15
- 239000000843 powder Substances 0.000 description 15
- 238000006243 chemical reaction Methods 0.000 description 14
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 9
- 229910052759 nickel Inorganic materials 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 230000003197 catalytic effect Effects 0.000 description 5
- QGUAJWGNOXCYJF-UHFFFAOYSA-N cobalt dinitrate hexahydrate Chemical compound O.O.O.O.O.O.[Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O QGUAJWGNOXCYJF-UHFFFAOYSA-N 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- 229910001873 dinitrogen Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 238000004438 BET method Methods 0.000 description 4
- 239000001099 ammonium carbonate Substances 0.000 description 4
- 235000012501 ammonium carbonate Nutrition 0.000 description 4
- MFUVDXOKPBAHMC-UHFFFAOYSA-N magnesium;dinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MFUVDXOKPBAHMC-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- XNDZQQSKSQTQQD-UHFFFAOYSA-N 3-methylcyclohex-2-en-1-ol Chemical compound CC1=CC(O)CCC1 XNDZQQSKSQTQQD-UHFFFAOYSA-N 0.000 description 3
- 229910021503 Cobalt(II) hydroxide Inorganic materials 0.000 description 3
- ASKVAEGIVYSGNY-UHFFFAOYSA-L cobalt(ii) hydroxide Chemical compound [OH-].[OH-].[Co+2] ASKVAEGIVYSGNY-UHFFFAOYSA-L 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical group [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 2
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 2
- 239000006069 physical mixture Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 2
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 229940011182 cobalt acetate Drugs 0.000 description 1
- GFHNAMRJFCEERV-UHFFFAOYSA-L cobalt chloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Co+2] GFHNAMRJFCEERV-UHFFFAOYSA-L 0.000 description 1
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- AOPCKOPZYFFEDA-UHFFFAOYSA-N nickel(2+);dinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O AOPCKOPZYFFEDA-UHFFFAOYSA-N 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 150000004685 tetrahydrates Chemical class 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Abstract
Description
本発明は、アンモニア分解用触媒及びその製造方法、並びに、当該触媒を用いた水素製造方法に関する発明である。 The present invention relates to an ammonia decomposition catalyst, a method for producing the same, and a method for producing hydrogen using the catalyst.
アンモニア分解による水素製造技術は古くから提案されているが、本格的に実用されることは少ないのが現状である。例えば、コークス炉から生じるアンモニアを分解し水素を得る技術が提案されている（特許文献１）。当該触媒は白金族を必須とするものであり、コストが高くなることが実用上の問題点である。一方、白金族を必須成分とする貴金属系触媒の問題点を克服するために、非貴金属系触媒が提案されている。非貴金属系の触媒として、銅族元素、クロム族元素及び鉄族元素のうちから選ばれる少なくとも１種の金属又は化合物とニッケルを触媒成分として用いる触媒が提案されている（特許文献２）。当該触媒は、ニッケルにコバルト、銅、クロム等各成分を組み合わせることにより、ニッケル単独成分からなる触媒に比べて、触媒性能を向上させたものである。また希土類とニッケルを組み合わせた触媒も提案されている（特許文献３）。 Hydrogen production technology by ammonia decomposition has been proposed for a long time, but it is rarely put into practical use. For example, a technique for decomposing ammonia generated from a coke oven to obtain hydrogen has been proposed (Patent Document 1). The catalyst essentially requires a platinum group, and its high cost is a practical problem. On the other hand, non-noble metal catalysts have been proposed in order to overcome the problems of noble metal catalysts containing a platinum group as an essential component. As a non-noble metal catalyst, a catalyst using at least one metal or compound selected from a copper group element, a chromium group element and an iron group element and nickel as a catalyst component has been proposed (Patent Document 2). The catalyst is obtained by improving the catalyst performance by combining nickel, cobalt, copper, chromium, and other components, compared to a catalyst composed of nickel alone. A catalyst combining rare earth and nickel has also been proposed (Patent Document 3).
これらの触媒は比表面積の高い担体に各触媒成分の溶液を含浸して調製したものであり、比表面積の高い酸化物表面を利用して当該表面に触媒成分を分散して担持することで触媒活性点を物理的に増加させて触媒全体として活性を向上させようとするものである。 These catalysts are prepared by impregnating a support having a high specific surface area with a solution of each catalyst component, and by using an oxide surface having a high specific surface area, the catalyst component is dispersed and supported on the surface. The active point is physically increased to improve the activity of the catalyst as a whole.
比表面積の高い担体を用いることで触媒活性点の数を増加させた形態の触媒系では、熱劣下による担体材料の比表面積低下に伴い、触媒活性点も減少し、触媒活性が低下することとなる。また、触媒活性点を増加させるために担体成分に対して多量の触媒成分を含浸担持しても触媒成分からなる粒子が凝集しやすくなるため、結果として触媒活性比表面積が増加しない。そのため、担体成分に含浸する触媒成分の含有量を増加させても含有量増加に見合った活性向上が得られず、含有量増加によりかえって触媒活性が低下し、十分な触媒活性を有する触媒を製造することが困難となっていた。このような従来触媒にみられる問題点を克服し、かつ、コスト面でも実用性に優れる高活性な触媒を開発することが求められている。 In a catalyst system in which the number of catalytic active points is increased by using a support having a high specific surface area, the catalytic active point is reduced and the catalytic activity is reduced as the specific surface area of the support material is reduced due to thermal deterioration. It becomes. Further, even if a large amount of the catalyst component is impregnated and supported on the carrier component in order to increase the catalyst active point, the particles composed of the catalyst component are likely to aggregate, and as a result, the catalyst active specific surface area does not increase. Therefore, even if the content of the catalyst component impregnated in the carrier component is increased, the activity improvement corresponding to the increase in the content cannot be obtained, and the catalyst activity is lowered due to the increase in content, and a catalyst having sufficient catalytic activity is produced. It was difficult to do. There is a need to develop a highly active catalyst that overcomes the problems found in such conventional catalysts and that is also practical in terms of cost.
上記課題を解決することができた本発明のアンモニア分解用触媒は、コバルトと、長周期型周期律表２〜５及び１２〜１５族の金属元素からなる群から選ばれる少なくとも１種の金属酸化物及び／又は複合酸化物である添加物質とを含む触媒であって、コバルトの算出比表面積（Ｓ２）と当該触媒の比表面積（Ｓ１）との比（Ｓ２／Ｓ１）が、０．１５〜０．８５であることを特徴とする。前記添加物質はアルミナ、シリカ、ジルコニア、アルカリ土類金属酸化物及びランタノイド系金属酸化物からなる群から選ばれる少なくとも一種の金属酸化物及び／又は複合酸化物が好ましい。前記触媒は、コバルトを触媒全量に対して５５〜９５質量％含有することが好ましい。 The catalyst for decomposing ammonia according to the present invention that has solved the above problems is at least one metal oxide selected from the group consisting of cobalt and a metal element of groups 2 to 5 and 12 to 15 of the long-period periodic table. And / or an additive substance that is a composite oxide, wherein the ratio (S2 / S1) of the calculated specific surface area (S2) of cobalt to the specific surface area (S1) of the catalyst is 0.15 to 0.15. It is characterized by 0.85. The additive is preferably at least one metal oxide and / or composite oxide selected from the group consisting of alumina, silica, zirconia, alkaline earth metal oxides, and lanthanoid metal oxides. The catalyst preferably contains 55 to 95% by mass of cobalt based on the total amount of the catalyst.
本発明のアンモニア分解用触媒の製造方法の態様は、コバルトの水溶性塩と添加物質前駆体の水溶性塩とを水に溶解し、アルカリ性化合物によりコバルト及び添加物質前駆体の沈殿物を生成させた後、ろ過、水洗、乾燥、熱処理する態様；コバルト塩を水に加え水溶液を調製し、この水溶液にアルカリ性化合物を加えてコバルトを含有する微粒子を析出させて微粒子分散液を調製し、当該微粒子分散液を撹拌しながら前記添加物質の微粒子分散ゾル溶液を添加して、コバルトを含有する微粒子と添加物質微粒子からなる沈殿物を生成させた後、この沈殿物をろ過、水洗、乾燥、熱処理する態様；が好ましい。本発明には、上記アンモニア分解用触媒を用いて、アンモニアを分解し水素を得る水素製造方法も含まれる。 The embodiment of the method for producing an ammonia decomposition catalyst according to the present invention comprises dissolving a water-soluble salt of cobalt and a water-soluble salt of an additive substance precursor in water, and generating a precipitate of cobalt and the additive substance precursor with an alkaline compound. After that, filtration, washing, drying, heat treatment: Cobalt salt is added to water to prepare an aqueous solution, and an alkaline compound is added to the aqueous solution to precipitate fine particles containing cobalt to prepare a fine particle dispersion. The fine particle-dispersed sol solution of the additive substance is added while stirring the dispersion to generate a precipitate composed of cobalt-containing fine particles and additive substance fine particles, and then the precipitate is filtered, washed, dried, and heat-treated. Embodiments are preferred. The present invention also includes a hydrogen production method in which ammonia is decomposed to obtain hydrogen using the ammonia decomposition catalyst.
本発明のアンモニア分解用触媒は、活性成分であるコバルトの含有量を高めた場合であっても、コバルトの算出比表面積（Ｓ２）が当該触媒の比表面積（Ｓ１）に対して０．１５〜０．８５（Ｓ２／Ｓ１）とコバルトの算出比表面積（Ｓ２）が高く保持できる。そのため、コスト面で実用上の問題を抱える貴金属系触媒を用いることなく、アンモニア分解反応に対して高活性を示し、効率良くアンモニアを水素と窒素に分解することができる。 The ammonia decomposition catalyst of the present invention has a calculated specific surface area (S2) of cobalt of 0.15 to 0.15 relative to the specific surface area (S1) of the catalyst even when the content of cobalt as an active component is increased. 0.85 (S2 / S1) and the calculated specific surface area (S2) of cobalt can be kept high. Therefore, without using a noble metal catalyst that has practical problems in terms of cost, it exhibits high activity for the ammonia decomposition reaction and can efficiently decompose ammonia into hydrogen and nitrogen.
本発明にかかる触媒はアンモニアを分解し水素を製造するために用いる触媒である。当該触媒はコバルトと、長周期型周期律表２〜５及び１２〜１５族の金属元素からなる群から選ばれる少なくとも１種の金属酸化物及び／又は複合酸化物である添加物質とを含む。 The catalyst according to the present invention is a catalyst used for producing hydrogen by decomposing ammonia. The catalyst includes cobalt and an additive substance which is at least one metal oxide and / or composite oxide selected from the group consisting of metal elements of long-period periodic table 2-5 and 12-15 group.
コバルトの状態は、金属、酸化物、それらの混合物の何れであってもよく、好ましくは金属状態である。触媒中のコバルトの含有率は、コバルト（金属換算）と添加物質（酸化物換算）との合計質量（合計１００質量％）に対して５５〜９５質量％が好ましく、より好ましくは６０〜９０質量％、さらに好ましくは６５〜８５質量％である。コバルトの含有率が、５５質量％未満では十分なアンモニア分解活性が得られないことがあり、９５質量％を超えるとコバルト量に対して添加物質が不足し、コバルトの凝集が進み耐熱性が低下する恐れがある。 The cobalt state may be any of a metal, an oxide, and a mixture thereof, and is preferably a metal state. The content of cobalt in the catalyst is preferably 55 to 95 mass%, more preferably 60 to 90 mass%, based on the total mass (total 100 mass%) of cobalt (metal conversion) and additive substances (oxide conversion). %, More preferably 65 to 85% by mass. If the content of cobalt is less than 55% by mass, sufficient ammonia decomposition activity may not be obtained. If the content exceeds 95% by mass, the amount of cobalt is insufficient with respect to the amount of cobalt, agglomeration of cobalt proceeds, and heat resistance decreases There is a fear.
前記添加物質は、長周期型周期律表２〜５及び１２〜１５族の金属元素からなる群から選ばれる少なくとも１種の金属酸化物及び／又は複合酸化物であり、好ましくはアルミナ、シリカ、ジルコニア、アルカリ土類金属酸化物及びランタノイド系金属酸化物からなる群から選ばれる少なくとも１種の金属酸化物及び／又は複合酸化物である。当該複合酸化物とは、個々の金属酸化物の単純な物理混合物でなく、セリア・ジルコニア固溶体、シリカ・アルミナ等に例示されるように各構成金属元素が原子レベルで複合化し、個々の金属酸化物の単純物理混合物と比較して構造及び物性面で異なる特性を示す状態にあるものを指す。 The additive substance is at least one metal oxide and / or composite oxide selected from the group consisting of long-period periodic table 2-5 and group 12-15 metal elements, preferably alumina, silica, It is at least one metal oxide and / or composite oxide selected from the group consisting of zirconia, alkaline earth metal oxides, and lanthanoid metal oxides. The complex oxide is not a simple physical mixture of individual metal oxides, but each constituent metal element is complexed at the atomic level as exemplified by ceria / zirconia solid solution, silica / alumina, etc. It refers to a material that exhibits different characteristics in terms of structure and physical properties compared to a simple physical mixture of materials.
本発明のアンモニア分解用触媒は、前記コバルトの算出比表面積（Ｓ２）の触媒の比表面積（Ｓ１）に対する比（Ｓ２／Ｓ１）は０．１５以上、好ましくは０．２０以上、より好ましくは０．２２以上であり、０．８５以下、好ましくは０．８０以下、より好ましくは０．７５以下である。前記比（Ｓ２／Ｓ１）が０．１５未満では、触媒におけるコバルトの算出比表面積が少なく十分な活性が得られないことがあり、０．８５を超えると耐熱性が低下し、耐久性が低下する場合がある。 In the ammonia decomposition catalyst of the present invention, the ratio (S2 / S1) of the calculated specific surface area (S2) of cobalt to the specific surface area (S1) of the catalyst is 0.15 or more, preferably 0.20 or more, more preferably 0. .22 or more and 0.85 or less, preferably 0.80 or less, more preferably 0.75 or less. If the ratio (S2 / S1) is less than 0.15, the calculated specific surface area of cobalt in the catalyst is small and sufficient activity may not be obtained. If it exceeds 0.85, the heat resistance decreases and the durability decreases. There is a case.
前記コバルトの算出比表面積（Ｓ２）は、当該触媒の比表面積から添加物質由来の比表面積分を減じることにより算出される。添加物質のみからなる粉体は、添加物質前駆体から当該触媒調製手順と同様に作製する。得られた添加物質のみからなる粉体について、窒素ガスを用いたＢＥＴ法により比表面積（Ｓ（ｂ））を測定する。当該触媒の比表面積（Ｓ１）から当該触媒に含まれる添加物質由来の比表面積分（Ｓ（ｂ）×当該触媒中の添加物質の質量含有率）を減じて当該コバルトの算出比表面積（Ｓ２）を得ることができる。 The calculated specific surface area (S2) of the cobalt is calculated by subtracting the specific surface integral derived from the additive substance from the specific surface area of the catalyst. The powder consisting only of the additive substance is prepared in the same manner as the catalyst preparation procedure from the additive substance precursor. The specific surface area (S (b)) is measured by the BET method using nitrogen gas for the obtained powder consisting only of the additive substance. Calculated specific surface area (S2) of the cobalt by subtracting the specific surface integral (S (b) × mass content of the additive substance in the catalyst) derived from the additive contained in the catalyst from the specific surface area (S1) of the catalyst Can be obtained.
本発明のアンモニア分解用触媒は、前記コバルトの算出比表面積（Ｓ２）が、２０ｍ2／ｇ以上であることが好ましく、より好ましくは２５ｍ2／ｇ以上、さらに好ましくは３０ｍ2／ｇ以上である。前記コバルトの算出比表面積が２０ｍ2／ｇ以上であれば、アンモニア分解用触媒の触媒活性がより向上する。コバルトの算出比表面積（Ｓ２）は大きいほど好ましいが、触媒調製法の改良等によって増加できる値にも限界があり、実際的には２５０ｍ2／ｇ以下が好ましく、より好ましくは２００ｍ2／ｇ以下、さらに好ましくは１５０ｍ2／ｇ以下である。 In the ammonia decomposition catalyst of the present invention, the calculated specific surface area (S2) of cobalt is preferably 20 m 2 / g or more, more preferably 25 m 2 / g or more, and further preferably 30 m 2 / g or more. . If the calculated specific surface area of cobalt is 20 m 2 / g or more, the catalytic activity of the ammonia decomposition catalyst is further improved. Calculated specific surface area of the cobalt (S2) is preferably larger, there is a limit to a value which can be increased by improving such a catalyst preparation method, preferably 250 meters 2 / g or less in practice, more preferably 200 meters 2 / g or less More preferably, it is 150 m 2 / g or less.
本発明のアンモニア分解用触媒の比表面積（Ｓ１）は、１０〜５００ｍ2／ｇが好ましく、より好ましくは２０〜４５０ｍ2／ｇ、さらに好ましくは、２５〜４００ｍ2／ｇ、さらに好ましくは、３０〜３５０ｍ2／ｇである。触媒の比表面積（Ｓ１）が１０ｍ2／ｇ以上であれば、触媒性能がより向上し、５００ｍ2／ｇ以下であれば、触媒の強度が良好となる。アンモニア分解用触媒の比表面積は、窒素ガスを用いたＢＥＴ法により測定する。 The specific surface area of the ammonia decomposition catalyst of the present invention (S1) is preferably from 10 to 500 m 2 / g, more preferably 20~450m 2 / g, more preferably, 25~400m 2 / g, more preferably, 30 -350 m < 2 > / g. When the specific surface area (S1) of the catalyst is 10 m 2 / g or more, the catalyst performance is further improved, and when it is 500 m 2 / g or less, the strength of the catalyst is good. The specific surface area of the ammonia decomposition catalyst is measured by the BET method using nitrogen gas.
本発明のアンモニア分解用触媒の形状は、粉体、球状、ペレット、サドル型、円筒型、板状、ハニカム状等、種々の形状のものを用いることができる。 The shape of the catalyst for decomposing ammonia according to the present invention may be various shapes such as powder, sphere, pellet, saddle type, cylindrical type, plate shape, honeycomb shape and the like.
本発明にかかる触媒の製造方法の一例を示す。なお、本発明の効果を奏するものであれば以下の触媒製造方法に限定されるものではない。本発明の触媒の製造方法としては、例えば、（１）コバルト塩を水に加え水溶液を調製し、この水溶液にアルカリ性化合物を加えてコバルトを含有する微粒子（例えば、コバルト水酸化物微粒子）を析出させ微粒子分散液を調製する。この微粒子分散液を撹拌しながら、添加物質の微粒子分散ゾル溶液を添加して、コバルトを含有する微粒子（例えば、コバルト水酸化物微粒子）と添加物質微粒子からなる沈殿物を生成させる。その後、この沈殿物を、ろ過により取り出し、水洗、乾燥、熱処理（例えば、還元性雰囲気下での熱処理）して触媒を得る方法；（２）添加物質前駆体の水溶性塩とコバルトの水溶性塩とを水に加え十分に混合した後、アルカリ性化合物を加えコバルトと添加物質前駆体とを含有する微粒子（例えば、水酸化物微粒子）の沈殿物を生成させる。その後、この沈殿物をろ過により取り出し、ろ過、水洗、乾燥、熱処理（例えば、還元性雰囲気下での熱処理）して触媒を得る方法；（３）アルカリ性化合物を加えたアルカリ性水溶液を調製する。撹拌したアルカリ性水溶液中に添加物質前駆体の水溶性塩とコバルトの水溶性塩を含む混合水溶液を追加して、コバルトを含む微粒子（例えば、コバルト水酸化物微粒子）と添加物質前駆体の微粒子からなる沈殿物を生成させる。その後、この沈殿物をろ過により取り出し、水洗、乾燥、熱処理（例えば、還元性雰囲気下での熱処理）して触媒を得る方法；が挙げられる。 An example of the manufacturing method of the catalyst concerning this invention is shown. In addition, as long as there exists an effect of this invention, it is not limited to the following catalyst manufacturing methods. As the method for producing the catalyst of the present invention, for example, (1) an aqueous solution is prepared by adding a cobalt salt to water, and an alkaline compound is added to this aqueous solution to precipitate fine particles containing cobalt (for example, cobalt hydroxide fine particles). To prepare a fine particle dispersion. While stirring the fine particle dispersion, a fine particle-dispersed sol solution of the additive substance is added to generate a precipitate composed of fine particles containing cobalt (for example, cobalt hydroxide fine particles) and additive substance fine particles. Thereafter, the precipitate is removed by filtration, washed with water, dried, and heat-treated (eg, heat-treated in a reducing atmosphere) to obtain a catalyst; (2) Water-soluble salt of additive precursor and water-soluble cobalt After the salt is added to water and mixed well, an alkaline compound is added to form a precipitate of fine particles (for example, hydroxide fine particles) containing cobalt and an additive precursor. Thereafter, the precipitate is taken out by filtration, filtered, washed with water, dried, and heat-treated (for example, heat-treated in a reducing atmosphere) to obtain a catalyst; (3) An alkaline aqueous solution to which an alkaline compound is added is prepared. Add a mixed aqueous solution containing a water-soluble salt of an additive precursor and a water-soluble salt of cobalt to a stirred alkaline aqueous solution, and fine particles containing cobalt (for example, cobalt hydroxide fine particles) and fine particles of an additive precursor A precipitate is formed. Thereafter, the precipitate is taken out by filtration, washed with water, dried, and heat-treated (for example, heat-treated in a reducing atmosphere) to obtain a catalyst.
上記製造方法において、熱処理は、空気雰囲気下での焼成；窒素、アルゴン等の不活性ガス雰囲気下での熱処理；水素等の還元性ガスを含む還元性ガス雰囲気下での還元を含む。また、触媒は使用に際して還元処理をすることが好ましい。還元方法としては、水素ガス等の還元性ガスと接触させる通常の方法を採用することができる。水素ガスを用いた還元処理を行う場合、還元条件は３００〜７５０℃、好ましくは４００〜６５０℃で、３０分〜２時間処理するものである。なお、水素製造時、原料ガスが酸素ガスを含む場合、アンモニア分解反応とともにアンモニア燃焼反応が進行するが、このアンモニア燃焼反応によって触媒温度が直ちに上昇し、アンモニア分解により生成した水素によって触媒が還元される。そのため、原料ガスが酸素ガスを含む場合には、アンモニア分解用触媒について、使用前の還元処理を施さなくとも使用できる場合がある。 In the above manufacturing method, the heat treatment includes firing in an air atmosphere; heat treatment in an inert gas atmosphere such as nitrogen or argon; and reduction in a reducing gas atmosphere containing a reducing gas such as hydrogen. The catalyst is preferably subjected to a reduction treatment when used. As a reduction method, a normal method of contacting with a reducing gas such as hydrogen gas can be employed. When the reduction treatment using hydrogen gas is performed, the reduction is performed at 300 to 750 ° C., preferably 400 to 650 ° C., for 30 minutes to 2 hours. During hydrogen production, if the source gas contains oxygen gas, the ammonia combustion reaction proceeds along with the ammonia decomposition reaction. The catalyst temperature immediately rises due to the ammonia combustion reaction, and the catalyst is reduced by the hydrogen generated by the ammonia decomposition. The Therefore, when the source gas contains oxygen gas, the ammonia decomposition catalyst may be used without being subjected to reduction treatment before use.
コバルトの原料は、最終的に還元処理により金属コバルトを生成するものであれば何れの化合物でも使用することが可能であるが、好ましくは水溶性の化合物である硝酸コバルト六水和物、酢酸コバルト四水和物、塩化コバルト六水和物である。 As the cobalt raw material, any compound can be used as long as it finally generates metallic cobalt by a reduction treatment. Preferably, cobalt nitrate hexahydrate and cobalt acetate are water-soluble compounds. Tetrahydrate, cobalt chloride hexahydrate.
添加物質の原料は最終的に熱処理により金属酸化物及び／又は複合酸化物を生成するものであれば何れの化合物でも使用することが可能であり、好ましくは水溶性の化合物である各種金属の硝酸塩、酢酸塩、塩化物、硫酸塩を使用することができる。 As the additive material, any compound can be used as long as it finally generates a metal oxide and / or composite oxide by heat treatment, and various metal nitrates, preferably water-soluble compounds. , Acetates, chlorides, sulfates can be used.
前記アルカリ性化合物としては、例えば、アンモニア、炭酸アンモニウム、水酸化テトラメチルアンモニウム等のアンモニア系化合物；水酸化カリウム等のアルカリ金属水酸化物；等が挙げられる。 Examples of the alkaline compound include ammonia compounds such as ammonia, ammonium carbonate, and tetramethylammonium hydroxide; alkali metal hydroxides such as potassium hydroxide; and the like.
本発明にかかるアンモニア分解用触媒を用いた水素製造方法は、当該触媒を用いてアンモニアガスを分解し水素を製造するものである。原料ガスは、アンモニアガスであるが、本発明の効果を阻害しないものであれば、他のガスを加えることができ、例えば窒素、アルゴン、ヘリウム、一酸化炭素、酸素である。特に、原料ガスが酸素を含む場合、アンモニアガスやアンモニア分解反応で生成した水素の一部を燃焼し、その燃焼熱をアンモニア分解反応の反応熱として使用するオートサーマルリフォーマーによるアンモニア分解を行うことができる。この場合、アンモニアに対する酸素のモル比（酸素／アンモニア）は、０．７５未満とする必要がある。また、アンモニア分解により得られる水素量と、燃焼反応による燃焼熱とを両立させる観点から、モル比（酸素／アンモニア）は０．０５以上が好ましく、より好ましくは０．１以上、さらに好ましくは０．１２以上であり、０．５以下が好ましく、より好ましくは０．３以下である。 The hydrogen production method using the catalyst for ammonia decomposition according to the present invention produces hydrogen by decomposing ammonia gas using the catalyst. The source gas is ammonia gas, but other gases can be added as long as they do not hinder the effects of the present invention, such as nitrogen, argon, helium, carbon monoxide, and oxygen. In particular, when the source gas contains oxygen, ammonia decomposition can be performed by an autothermal reformer that burns part of the ammonia gas or hydrogen produced by the ammonia decomposition reaction and uses the combustion heat as the reaction heat of the ammonia decomposition reaction. it can. In this case, the molar ratio of oxygen to ammonia (oxygen / ammonia) needs to be less than 0.75. Further, from the viewpoint of achieving both the amount of hydrogen obtained by ammonia decomposition and the combustion heat by the combustion reaction, the molar ratio (oxygen / ammonia) is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0. .12 or more, preferably 0.5 or less, more preferably 0.3 or less.
アンモニアの分解反応は、反応温度が３００〜９００℃、好ましくは４００〜７００℃であり、反応圧力は０．００２〜２ＭＰａ、好ましくは０．００４〜１ＭＰａである。反応ガス（原料ガス）導入時の空間速度（ＳＶ）は１，０００〜５００，０００ｈｒ-1、好ましくは１，０００〜２００，０００ｈｒ-1である。 The ammonia decomposition reaction has a reaction temperature of 300 to 900 ° C., preferably 400 to 700 ° C., and a reaction pressure of 0.002 to 2 MPa, preferably 0.004 to 1 MPa. The space velocity (SV) when the reaction gas (raw material gas) is introduced is 1,000 to 500,000 hr −1 , preferably 1,000 to 200,000 hr −1 .
また、触媒を使用するに際して、事前に前処理することもできる。適した処理条件で前処理することにより触媒の状態を反応中の状態に近いものとすることができ、本前処理を施すことにより当初から定常的な反応状態での運転が可能になる。前処理としては、例えば、窒素ガスを反応条件で一定時間触媒に流通させることである。 Moreover, when using a catalyst, it can also pre-process in advance. By performing pretreatment under suitable treatment conditions, the state of the catalyst can be made close to that during the reaction, and by performing this pretreatment, operation in a steady reaction state can be performed from the beginning. As pretreatment, for example, nitrogen gas is allowed to flow through the catalyst for a certain period of time under reaction conditions.
以下に実施例を挙げて本発明をより具体的に説明するが、本発明は、下記実施例によって限定されるものではなく、前・後記の趣旨に適合しうる範囲で適宜変更して実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。 The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.
製造例１
１００ｇの硝酸コバルト六水和物と７３．４ｇの硝酸アルミニウム九水和物を７５０ｍＬの純水に溶解させ、硝酸コバルトと硝酸アルミニウムの混合水溶液を調製した（水溶液Ａ１）。別途、１２２ｇの炭酸アンモニウムを２．２５Ｌの純水に溶解させた水溶液Ｂ１を調製した。常温下で激しく撹拌した水溶液Ｂ１に水溶液Ａ１を一度に加え、さらに一時間撹拌を継続し、沈殿物を生成させた。その後、当該沈殿物をろ過回収し、水洗後、１５０℃で一晩乾燥させた。乾燥後の沈殿物を粉砕し、管状炉に充填して１０体積％水素ガス（窒素希釈）を用いて６５０℃で一時間還元して触媒１を得た。得られた触媒１のコバルト含有率は、金属換算で触媒全量に対して６７質量％であった。
Production Example 1
100 g of cobalt nitrate hexahydrate and 73.4 g of aluminum nitrate nonahydrate were dissolved in 750 mL of pure water to prepare a mixed aqueous solution of cobalt nitrate and aluminum nitrate (aqueous solution A1). Separately, an aqueous solution B1 in which 122 g of ammonium carbonate was dissolved in 2.25 L of pure water was prepared. The aqueous solution A1 was added at once to the aqueous solution B1 vigorously stirred at room temperature, and the stirring was further continued for 1 hour to generate a precipitate. Thereafter, the precipitate was collected by filtration, washed with water, and dried at 150 ° C. overnight. The dried precipitate was pulverized, filled into a tube furnace, and reduced at 650 ° C. for 1 hour using 10% by volume hydrogen gas (diluted with nitrogen) to obtain catalyst 1. The cobalt content of the obtained catalyst 1 was 67% by mass with respect to the total amount of the catalyst in terms of metal.
製造例２
製造例１における硝酸コバルト六水和物、硝酸アルミニウム九水和物及び炭酸アンモニウムの使用量を１２２ｇ、４２．２ｇ及び１１３ｇに変更した以外は製造例１と同様にして触媒２を得た。得られた触媒２のコバルト含有率は、金属換算で触媒全量に対して８１質量％であった。
Production Example 2
Catalyst 2 was obtained in the same manner as in Production Example 1 except that the amounts of cobalt nitrate hexahydrate, aluminum nitrate nonahydrate and ammonium carbonate used in Production Example 1 were changed to 122 g, 42.2 g and 113 g. The obtained catalyst 2 had a cobalt content of 81% by mass relative to the total amount of the catalyst in terms of metal.
製造例３
８７．４ｇの硝酸コバルト六水和物と４２．０ｇの硝酸マグネシウム六水和物を６００ｍＬの純水に溶解させ、硝酸コバルトと硝酸マグネシウムの混合水溶液を調製した（水溶液Ａ２）。別途、１３０ｇの水酸化カリウムを２．４Ｌの純水に溶解させた水溶液Ｂ２を調製した。常温下で激しく撹拌した水溶液Ｂ２に水溶液Ａ２を滴下し、沈殿物を生成させた。当該沈殿物をろ過し、十分に水洗した後、１５０℃で一晩乾燥させた。乾燥後の沈殿物を粉砕し、管状炉に充填して１０体積％水素ガス（窒素希釈）を用いて４５０℃で一時間還元して触媒３を得た。得られた触媒３のコバルト含有率は、金属換算で触媒全量に対して７３質量％であった。
Production Example 3
87.4 g of cobalt nitrate hexahydrate and 42.0 g of magnesium nitrate hexahydrate were dissolved in 600 mL of pure water to prepare a mixed aqueous solution of cobalt nitrate and magnesium nitrate (aqueous solution A2). Separately, an aqueous solution B2 in which 130 g of potassium hydroxide was dissolved in 2.4 L of pure water was prepared. The aqueous solution A2 was added dropwise to the aqueous solution B2 vigorously stirred at room temperature to generate a precipitate. The precipitate was filtered, washed thoroughly with water, and dried overnight at 150 ° C. The dried precipitate was pulverized, filled into a tubular furnace, and reduced at 450 ° C. for 1 hour using 10% by volume hydrogen gas (diluted with nitrogen) to obtain catalyst 3. The obtained catalyst 3 had a cobalt content of 73 mass% with respect to the total amount of the catalyst in terms of metal.
製造例４
γ−アルミナ（住友化学株式会社製）粉体を、空気雰囲気下、９５０℃で１０時間焼成した後、粉砕した。この熱処理によりアルミナの結晶相は、γ相からκ相に転移していた。この熱処理アルミナ粉体２０ｇに、１１．０ｇの硝酸コバルト六水和物を５０ｍＬの純水に溶解させた水溶液を加え、撹拌しながら加熱して水分を蒸発させて乾燥物を得た。得られた乾燥物を、さらに１５０℃で一晩乾燥後、粉砕して管状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて４５０℃で一時間還元して触媒４を得た。得られた触媒４のコバルト含有率は、金属換算で触媒全量に対して１０質量％であった。
Production Example 4
The γ-alumina (manufactured by Sumitomo Chemical Co., Ltd.) powder was pulverized after firing at 950 ° C. for 10 hours in an air atmosphere. By this heat treatment, the crystal phase of alumina was changed from the γ phase to the κ phase. An aqueous solution in which 11.0 g of cobalt nitrate hexahydrate was dissolved in 50 mL of pure water was added to 20 g of this heat-treated alumina powder, and the mixture was heated with stirring to evaporate the water and obtain a dried product. The obtained dried product was further dried at 150 ° C. overnight, pulverized and filled into a tubular furnace, and reduced at 450 ° C. for 1 hour using 10% by volume hydrogen gas (nitrogen dilution) to obtain catalyst 4. . The resulting catalyst 4 had a cobalt content of 10% by mass relative to the total amount of the catalyst in terms of metal.
製造例５
１５０℃で一晩乾燥させたγ−アルミナ（Ｓｔｒｅｍ Ｃｈｅｍｉｃａｌｓ Ｉｎｃ．製）粉体を粉砕し、当該粉体２０ｇに、２４．８ｇの硝酸ニッケル六水和物を５０ｍＬの純水に溶解させた水溶液を加え、撹拌しながら加熱して水分を蒸発させて乾燥物を得た。得られた乾燥物を、さらに１５０℃で一晩乾燥後、粉砕して管状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて４５０℃で一時間還元して触媒５を得た。得られた触媒５のニッケル含有率は、金属換算で触媒全量に対して２０質量％であった。
Production Example 5
An aqueous solution in which γ-alumina (manufactured by Strem Chemicals Inc.) powder dried overnight at 150 ° C. is pulverized, and 24.8 g of nickel nitrate hexahydrate is dissolved in 50 mL of pure water in 20 g of the powder. And heated with stirring to evaporate the water to obtain a dried product. The obtained dried product was further dried at 150 ° C. overnight, pulverized and filled into a tubular furnace, and reduced at 450 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain catalyst 5. . The resulting catalyst 5 had a nickel content of 20% by mass relative to the total amount of the catalyst in terms of metal.
製造例６
１０５．０ｇの硝酸アルミニウム九水和物を５００ｍＬの純水に溶解させた（水溶液Ａ３）。別途、８０．６ｇの炭酸アンモニウムを１．５Ｌの純水に溶解させた水溶液Ｂ３を調製した。常温下で激しく撹拌した水溶液Ｂ３に水溶液Ａ３を一度に加え、さらに一時間撹拌を継続し、沈殿物を生成させた。その後、当該沈殿物をろ過回収し、水洗後、１５０℃で一晩乾燥させた。乾燥後の沈殿物を粉砕し、管状炉に充填して１０体積％水素ガス（窒素希釈）を用いて６５０℃で一時間還元処理してアルミナからなる粉体１を得た（触媒１及び２の添加物質）。
Production Example 6
105.0 g of aluminum nitrate nonahydrate was dissolved in 500 mL of pure water (aqueous solution A3). Separately, an aqueous solution B3 in which 80.6 g of ammonium carbonate was dissolved in 1.5 L of pure water was prepared. The aqueous solution A3 was added at once to the aqueous solution B3 vigorously stirred at room temperature, and the stirring was continued for another hour to generate a precipitate. Thereafter, the precipitate was collected by filtration, washed with water, and dried at 150 ° C. overnight. The dried precipitate was pulverized, filled into a tubular furnace, and reduced at 650 ° C. for 1 hour using 10% by volume hydrogen gas (diluted with nitrogen) to obtain powder 1 made of alumina (catalysts 1 and 2). Additional substances).
製造例７
１０２．６ｇの硝酸マグネシウム六水和物を５００ｍＬの純水に溶解させた（水溶液Ａ４）。別途、１１２．２ｇの水酸化カリウムを２Ｌの純水に溶解させた水溶液Ｂ４を調製した。常温下で激しく撹拌した水溶液Ｂ４に水溶液Ａ４を滴下し、沈殿物を生成させた。当該沈殿物をろ過し、十分に水洗した後、１５０℃で一晩乾燥させた。乾燥後の沈殿物を粉砕し、管状炉に充填して１０体積％水素ガス（窒素希釈）を用いて４５０℃で一時間還元処理してマグネシアからなる粉体２を得た（触媒３の添加物質）。
Production Example 7
102.6 g of magnesium nitrate hexahydrate was dissolved in 500 mL of pure water (aqueous solution A4). Separately, an aqueous solution B4 in which 112.2 g of potassium hydroxide was dissolved in 2 L of pure water was prepared. The aqueous solution A4 was dropped into the aqueous solution B4 that was vigorously stirred at room temperature to form a precipitate. The precipitate was filtered, washed thoroughly with water, and dried overnight at 150 ° C. The dried precipitate was pulverized, filled into a tube furnace, and reduced at 450 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain powder 2 made of magnesia (addition of catalyst 3) material).
製造例８
製造例４で調製した熱処理アルミナ粉体を管状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて４５０℃で一時間還元処理してアルミナからなる粉体３を得た（触媒４の添加物質）。
Production Example 8
The heat-treated alumina powder prepared in Production Example 4 was filled in a tubular furnace and reduced at 450 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen) to obtain powder 3 made of alumina (Catalyst 4 Additional substances).
製造例９
製造例５で使用したγ−アルミナ（Ｓｔｒｅｍ Ｃｈｅｍｉｃａｌｓ Ｉｎｃ．製）を粉砕後、当該粉体を管状炉に充填し、１０体積％水素ガス（窒素希釈）を用いて４５０℃で一時間還元処理してアルミナからなる粉体４を得た（触媒５の添加物質）。
Production Example 9
After γ-alumina (manufactured by Strem Chemicals Inc.) used in Production Example 5 was pulverized, the powder was filled in a tubular furnace and reduced at 450 ° C. for 1 hour using 10 vol% hydrogen gas (diluted with nitrogen). Thus, powder 4 made of alumina was obtained (additional substance of catalyst 5).
＜触媒の比表面積測定法＞
触媒の比表面積は、窒素ガスを用いたＢＥＴ法により測定した。
<Method for measuring specific surface area of catalyst>
The specific surface area of the catalyst was measured by the BET method using nitrogen gas.
＜コバルト、ニッケルの比表面積算出法＞
コバルト、ニッケルの算出比表面積は、触媒の比表面積から添加物質由来の比表面積分を減じることにより算出した。触媒中の添加物質由来の比表面積は、以下のようにして求めた。具体的には、各製造例で使用した添加物質前駆体のみを用いて、その製造例における触媒調製手順と同様に、添加物質のみからなる粉体を調製した。得られた添加物質のみからなる粉体について、窒素ガスを用いたＢＥＴ法により比表面積（Ｓ（ｂ））を測定した。下記式により触媒中の添加物質由来の比表面積を算出した。
触媒中の添加物質由来の比表面積＝（Ｓ（ｂ）×当該触媒中の添加物質の質量含有率）
<Calculation method of specific surface area of cobalt and nickel>
The calculated specific surface areas of cobalt and nickel were calculated by subtracting the specific surface integral derived from the additive substance from the specific surface area of the catalyst. The specific surface area derived from the additive substance in the catalyst was determined as follows. Specifically, using only the additive precursor used in each production example, a powder consisting only of the additive substance was prepared in the same manner as the catalyst preparation procedure in the production example. The specific surface area (S (b)) was measured by the BET method using nitrogen gas for the obtained powder consisting only of the additive substance. The specific surface area derived from the additive substance in the catalyst was calculated from the following formula.
Specific surface area derived from additive substance in catalyst = (S (b) × mass content of additive substance in catalyst)
＜コバルト、ニッケルの個数平均粒子径＞
透過型電子顕微鏡観察結果からコバルト粒子（触媒１〜４）又はニッケル粒子（触媒５）の個数平均粒子径を測定した。
<Number average particle diameter of cobalt and nickel>
The number average particle diameter of cobalt particles (catalysts 1 to 4) or nickel particles (catalyst 5) was measured from the observation result of the transmission electron microscope.
＜アンモニア分解反応試験＞
１０ｍｍφのＳＵＳ３１６製反応管を用い、製造例１〜５で調製した触媒１〜５を０．８ｍＬ充填してアンモニア分解反応を行った。常圧下、ＳＶ＝１８，０００ｈｒ-1とし、電気炉で反応管を加熱し、各電気炉設定温度でのアンモニア分解率を測定した。触媒に供給する入口ガス組成は、アンモニア５８．３体積％及び残部窒素とした。
アンモニア分解率は、入口に供給しているアンモニア流速Ｖ１、窒素流速Ｖ２及び触媒層出口ガス中に含まれる未反応アンモニアをトラップした後のガス流速Ｖ３から下記式により算出した。なお、触媒の前処理として窒素で希釈した１０体積％水素を毎分１００ｍｌで流通しながら４５０℃で１時間還元を行ってからアンモニア分解反応を実施した。反応結果を表２に示す。
アンモニア分解率（％）＝１００×（Ｖ３−Ｖ２）×０．５／Ｖ１
<Ammonia decomposition reaction test>
Using a 10 mmφ SUS316 reaction tube, 0.8 mL of catalyst 1 to 5 prepared in Production Examples 1 to 5 was charged to perform an ammonia decomposition reaction. Under normal pressure, SV = 18,000 hr −1 , the reaction tube was heated in an electric furnace, and the ammonia decomposition rate at each electric furnace set temperature was measured. The inlet gas composition supplied to the catalyst was 58.3 vol% ammonia and the balance nitrogen.
The ammonia decomposition rate was calculated from the ammonia flow rate V1, nitrogen flow rate V2 supplied to the inlet, and gas flow rate V3 after trapping unreacted ammonia contained in the catalyst layer outlet gas by the following equation. As a pretreatment of the catalyst, ammonia decomposition was carried out after reducing at 450 ° C. for 1 hour while flowing 10 volume% hydrogen diluted with nitrogen at 100 ml per minute. The reaction results are shown in Table 2.
Ammonia decomposition rate (%) = 100 × (V3−V2) × 0.5 / V1
＜酸素共存下でのアンモニア分解反応＞
１０ｍｍφのＳＵＳ３１６製反応管を用い、製造例１、５で調製した触媒１、５を０．８ｍＬ充填して酸素共存下でのアンモニア分解反応を行った。常圧下、ＳＶ＝１８，０００ｈｒ-1とし、電気炉で反応管を加熱し、電気炉設定温度１５０℃でのアンモニア分解率を測定した。アンモニア分解反応は、触媒に供給する入口ガス組成をアンモニア５８体積％、酸素７．１体積％及び残部窒素として実施した。
アンモニア分解率は、入口に供給しているアンモニア流速Ｆ１、触媒出口ガス中の未反応アンモニアをホウ酸水溶液で一定時間捕集し、当該捕集液に含まれるアンモニア濃度を陽イオンクロマトグラフで定量分析して出口ガス中のアンモニア流速Ｆ２を求め、下記式により算出した。なお、触媒の前処理として窒素で希釈した１０％水素を毎分１００ｍｌで流通しながら４５０℃で１時間還元を行ってから水蒸気共存下でのアンモニア分解反応を実施した。反応結果を表３に示す。
アンモニア分解率（％）＝１００−｛１００×（Ｆ２／Ｆ１）｝
<Ammonia decomposition reaction in the presence of oxygen>
Using a 10 mmφ SUS316 reaction tube, 0.8 mL of Catalysts 1 and 5 prepared in Production Examples 1 and 5 were charged, and ammonia decomposition reaction was performed in the presence of oxygen. Under normal pressure, SV = 18,000 hr −1 , the reaction tube was heated in an electric furnace, and the ammonia decomposition rate at an electric furnace set temperature of 150 ° C. was measured. The ammonia decomposition reaction was carried out with the composition of the inlet gas supplied to the catalyst being 58 vol% ammonia, 7.1 vol% oxygen, and the balance nitrogen.
The ammonia decomposition rate is determined by collecting the ammonia flow rate F1 supplied to the inlet, unreacted ammonia in the catalyst outlet gas with an aqueous boric acid solution for a certain period of time, and quantifying the ammonia concentration contained in the collected liquid with a cation chromatograph. The ammonia flow rate F2 in the outlet gas was determined by analysis and calculated by the following formula. In addition, as a pretreatment of the catalyst, 10% hydrogen diluted with nitrogen was reduced at 450 ° C. for 1 hour while flowing at 100 ml per minute, and then an ammonia decomposition reaction was carried out in the presence of water vapor. The reaction results are shown in Table 3.
Ammonia decomposition rate (%) = 100− {100 × (F2 / F1)}
本発明は、アンモニアの分解に関するものであり、本発明を用いることでアンモニアから水素を効率よく得ることができる。本発明は、水素製造技術に関して広く応用することができるものである。 The present invention relates to the decomposition of ammonia, and hydrogen can be efficiently obtained from ammonia by using the present invention. The present invention can be widely applied to hydrogen production technology.
Claims (6)
コバルトの算出比表面積（Ｓ２）と当該触媒の比表面積（Ｓ１）との比（Ｓ２／Ｓ１）が、０．１５〜０．８５であることを特徴とするアンモニア分解用触媒。 A catalyst comprising cobalt and an additive substance which is at least one metal oxide and / or complex oxide selected from the group consisting of metal elements of groups 2 to 5 and 12 to 15 of the long-period periodic table. ,
The ammonia decomposition catalyst, wherein the ratio (S2 / S1) of the calculated specific surface area (S2) of cobalt and the specific surface area (S1) of the catalyst is 0.15 to 0.85.
コバルトの水溶性塩と添加物質前駆体の水溶性塩とを水に溶解し、アルカリ性化合物によりコバルト及び添加物質前駆体の沈殿物を生成させた後、ろ過、水洗、乾燥、熱処理することを特徴とするアンモニア分解用触媒の製造方法。 It is a manufacturing method of the catalyst for ammonia decomposition | disassembly of any one of Claims 1-3,
A water-soluble salt of cobalt and a water-soluble salt of an additive precursor are dissolved in water, and a precipitate of cobalt and the additive precursor is generated with an alkaline compound, followed by filtration, washing, drying, and heat treatment. A process for producing an ammonia decomposition catalyst.
コバルト塩を水に加え水溶液を調製し、この水溶液にアルカリ性化合物を加えてコバルトを含有する微粒子を析出させて微粒子分散液を調製し、当該微粒子分散液を撹拌しながら前記添加物質の微粒子分散ゾル溶液を添加して、コバルトを含有する微粒子と添加物質微粒子からなる沈殿物を生成させた後、この沈殿物をろ過、水洗、乾燥、熱処理することを特徴とするアンモニア分解用触媒の製造方法。 It is a manufacturing method of the catalyst for ammonia decomposition | disassembly of any one of Claims 1-3,
A cobalt salt is added to water to prepare an aqueous solution, an alkaline compound is added to the aqueous solution to precipitate fine particles containing cobalt to prepare a fine particle dispersion, and the fine particle dispersion sol of the additive substance is stirred while stirring the fine particle dispersion. A method for producing an ammonia decomposition catalyst, comprising: adding a solution to produce a precipitate comprising cobalt-containing fine particles and additive substance fine particles; and filtering, washing, drying, and heat-treating the precipitate.
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| CN110691649A (en) * | 2017-05-31 | 2020-01-14 | 古河电气工业株式会社 | Ammonia decomposition catalyst structure and fuel cell |
| CN114984967A (en) * | 2022-06-27 | 2022-09-02 | 中国科学技术大学 | Cobalt oxide catalyst, method for producing same, and method for decomposing ammonia |
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| CN110691649A (en) * | 2017-05-31 | 2020-01-14 | 古河电气工业株式会社 | Ammonia decomposition catalyst structure and fuel cell |
| CN114984967A (en) * | 2022-06-27 | 2022-09-02 | 中国科学技术大学 | Cobalt oxide catalyst, method for producing same, and method for decomposing ammonia |
| CN114984967B (en) * | 2022-06-27 | 2023-06-16 | 中国科学技术大学 | Cobalt oxide catalyst, method for preparing the same, and method for decomposing ammonia |
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