JP2011078947A - Ammonia decomposition catalyst and ammonia decomposition method - Google Patents
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 240
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 111
- 238000000354 decomposition reaction Methods 0.000 title claims abstract description 75
- 239000003054 catalyst Substances 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 23
- 229910052742 iron Inorganic materials 0.000 claims abstract description 30
- 229910052596 spinel Inorganic materials 0.000 claims abstract description 29
- 239000011029 spinel Substances 0.000 claims abstract description 29
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 18
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000001301 oxygen Substances 0.000 claims abstract description 9
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 9
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 8
- 229910052788 barium Inorganic materials 0.000 claims abstract description 7
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 7
- 229910052712 strontium Inorganic materials 0.000 claims abstract description 7
- 239000000470 constituent Substances 0.000 claims abstract description 5
- 239000002131 composite material Substances 0.000 claims description 61
- 239000007789 gas Substances 0.000 claims description 41
- 229910052751 metal Inorganic materials 0.000 claims description 35
- 239000002184 metal Substances 0.000 claims description 32
- 229910045601 alloy Inorganic materials 0.000 claims description 8
- 239000000956 alloy Substances 0.000 claims description 8
- 229910020598 Co Fe Inorganic materials 0.000 claims description 7
- 229910002519 Co-Fe Inorganic materials 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 5
- 229910020632 Co Mn Inorganic materials 0.000 claims description 4
- 229910020678 Co—Mn Inorganic materials 0.000 claims description 4
- 229910019089 Mg-Fe Inorganic materials 0.000 claims description 4
- 229910003286 Ni-Mn Inorganic materials 0.000 claims description 4
- 238000005336 cracking Methods 0.000 claims 1
- 230000003647 oxidation Effects 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 claims 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 49
- 238000006243 chemical reaction Methods 0.000 description 41
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 39
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 38
- 239000002245 particle Substances 0.000 description 27
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 24
- 230000000052 comparative effect Effects 0.000 description 23
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 18
- 229910052739 hydrogen Inorganic materials 0.000 description 18
- 239000000243 solution Substances 0.000 description 18
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 17
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 17
- 238000002441 X-ray diffraction Methods 0.000 description 17
- 238000001228 spectrum Methods 0.000 description 17
- 239000001257 hydrogen Substances 0.000 description 16
- 229910052757 nitrogen Inorganic materials 0.000 description 16
- 229910052786 argon Inorganic materials 0.000 description 14
- 238000011156 evaluation Methods 0.000 description 14
- 239000011572 manganese Substances 0.000 description 14
- 238000006722 reduction reaction Methods 0.000 description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 12
- 229910017052 cobalt Inorganic materials 0.000 description 11
- 239000010941 cobalt Substances 0.000 description 11
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 11
- 229910001868 water Inorganic materials 0.000 description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 10
- 229910021446 cobalt carbonate Inorganic materials 0.000 description 9
- ZOTKGJBKKKVBJZ-UHFFFAOYSA-L cobalt(2+);carbonate Chemical compound [Co+2].[O-]C([O-])=O ZOTKGJBKKKVBJZ-UHFFFAOYSA-L 0.000 description 9
- 229910021645 metal ion Inorganic materials 0.000 description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- NPFOYSMITVOQOS-UHFFFAOYSA-K iron(III) citrate Chemical compound [Fe+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NPFOYSMITVOQOS-UHFFFAOYSA-K 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 7
- -1 Mg—Co Inorganic materials 0.000 description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000000446 fuel Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 229910052707 ruthenium Inorganic materials 0.000 description 4
- 210000002268 wool Anatomy 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 150000007524 organic acids Chemical class 0.000 description 3
- 229910003321 CoFe Inorganic materials 0.000 description 2
- 229910002546 FeCo Inorganic materials 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- 229910016897 MnNi Inorganic materials 0.000 description 2
- FMRLDPWIRHBCCC-UHFFFAOYSA-L Zinc carbonate Chemical compound [Zn+2].[O-]C([O-])=O FMRLDPWIRHBCCC-UHFFFAOYSA-L 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- UBEWDCMIDFGDOO-UHFFFAOYSA-N cobalt(2+);cobalt(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3] UBEWDCMIDFGDOO-UHFFFAOYSA-N 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 229910052746 lanthanum Inorganic materials 0.000 description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 2
- 239000011656 manganese carbonate Substances 0.000 description 2
- 235000006748 manganese carbonate Nutrition 0.000 description 2
- 229940093474 manganese carbonate Drugs 0.000 description 2
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 2
- XMWCXZJXESXBBY-UHFFFAOYSA-L manganese(ii) carbonate Chemical compound [Mn+2].[O-]C([O-])=O XMWCXZJXESXBBY-UHFFFAOYSA-L 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 description 2
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 239000008213 purified water Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000011667 zinc carbonate Substances 0.000 description 2
- 235000004416 zinc carbonate Nutrition 0.000 description 2
- 229910000010 zinc carbonate Inorganic materials 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910020599 Co 3 O 4 Inorganic materials 0.000 description 1
- 229910002551 Fe-Mn Inorganic materials 0.000 description 1
- ONIBWKKTOPOVIA-BYPYZUCNSA-N L-Proline Chemical compound OC(=O)[C@@H]1CCCN1 ONIBWKKTOPOVIA-BYPYZUCNSA-N 0.000 description 1
- 229910019083 Mg-Ni Inorganic materials 0.000 description 1
- 229910019403 Mg—Ni Inorganic materials 0.000 description 1
- 229910003271 Ni-Fe Inorganic materials 0.000 description 1
- ONIBWKKTOPOVIA-UHFFFAOYSA-N Proline Natural products OC(=O)C1CCCN1 ONIBWKKTOPOVIA-UHFFFAOYSA-N 0.000 description 1
- OXILMYSYIKRRPW-UHFFFAOYSA-N [Pt].[La].[Ni] Chemical group [Pt].[La].[Ni] OXILMYSYIKRRPW-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 150000003304 ruthenium compounds Chemical class 0.000 description 1
- YBCAZPLXEGKKFM-UHFFFAOYSA-K ruthenium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Ru+3] YBCAZPLXEGKKFM-UHFFFAOYSA-K 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000012916 structural analysis Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- 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
-
- 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
- Y02E60/50—Fuel cells
Abstract
Description
本発明は、アンモニアガスを効率よく分解するための新規なアンモニア分解触媒、アンモニアの分解方法、及びアンモニア分解反応装置に関するものである。 The present invention relates to a novel ammonia decomposition catalyst, an ammonia decomposition method, and an ammonia decomposition reaction apparatus for efficiently decomposing ammonia gas.
公害防止や環境破壊の観点から、アンモニア分解触媒は古くから研究や開発がなされ、例えば、各種排ガス中に含まれる有害なアンモニアを水と窒素に分解するアンモニア分解触媒や、また水素と窒素とに分解するアンモニア分解触媒が知られている。
一方で、エネルギーの観点から、水素／空気燃料電池は将来のクリーンなエネルギー源として有望視されている。この燃料電池の燃料として使用される水素をアンモニアから生成する試みがなされ、アンモニアから水素と窒素を高転化率で得ることが期待されている。
From the viewpoint of pollution prevention and environmental destruction, ammonia decomposition catalysts have been researched and developed for a long time.For example, ammonia decomposition catalysts that decompose harmful ammonia contained in various exhaust gases into water and nitrogen, and hydrogen and nitrogen. Ammonia decomposition catalysts that decompose are known.
On the other hand, from the viewpoint of energy, hydrogen / air fuel cells are regarded as promising as future clean energy sources. Attempts have been made to produce hydrogen used as fuel for this fuel cell from ammonia, and it is expected to obtain hydrogen and nitrogen from ammonia at a high conversion rate.
従来、アンモニアを水素と窒素とに分解する方法や触媒としては、以下の技術が知られている。
（１）アルミナなどの無機質担体にニッケル、鉄、パラジウム、白金またはルテニウムを担持した触媒を使用し、加熱下でアンモニアを接触させ、水素と窒素とに分解する方法(特許文献１参照)。
（２）アルミナなどの無機質担体にニッケル−ランタン−白金族（白金、パラジウム、イリジウム、ルテニウムなど）を担持した触媒を使用し、加熱下でアンモニアを接触させ、水素と窒素とに分解する方法(特許文献2参照)。
（３）無機質担体であるＭｎ−Ｃｕ系の複合酸化物やＭｎ−Ｆｅ系の複合酸化物にルテニウム化合物を担持した触媒を使用し、加熱下でアンモニアを接触させ、水素と窒素とに分解する方法(特許文献３参照)。
Conventionally, the following techniques are known as methods and catalysts for decomposing ammonia into hydrogen and nitrogen.
(1) A method in which a catalyst in which nickel, iron, palladium, platinum or ruthenium is supported on an inorganic carrier such as alumina is used, and ammonia is brought into contact with heating to decompose into hydrogen and nitrogen (see Patent Document 1).
(2) A method in which a catalyst in which a nickel-lanthanum-platinum group (platinum, palladium, iridium, ruthenium, etc.) is supported on an inorganic carrier such as alumina is contacted with ammonia under heating and decomposed into hydrogen and nitrogen ( (See Patent Document 2).
(3) Using a catalyst in which a ruthenium compound is supported on a Mn—Cu composite oxide or Mn—Fe composite oxide, which is an inorganic carrier, is brought into contact with ammonia under heating and decomposed into hydrogen and nitrogen. Method (see Patent Document 3).
しかし、このような従来のアンモニア分解触媒は、無機質担体を製造し、さらに、この無機質担体に触媒作用として機能する、いわゆる活性種となる金属を別途に担持せしめたものであるために、製造方法が複雑である。また、無機質担体に活性種となる金属を均一に分散し、担持させることは難しく、触媒としての充分な機能が発揮し難いものであった。 However, such a conventional ammonia decomposition catalyst is produced by producing an inorganic carrier and further supporting a so-called active species metal that functions as a catalytic action on the inorganic carrier. Is complicated. Further, it is difficult to uniformly disperse and carry a metal as an active species on an inorganic carrier, and it is difficult to exhibit a sufficient function as a catalyst.
また、担持触媒としての白金族はアンモニアの分解に際して高活性を示すが、貴金属なので高価であり、コストの面で課題であった。また、低温での使用条件では活性が不充分であり、高温での使用条件においては触媒のシンタリングによる性能の劣化が問題となっていた。 Further, the platinum group as a supported catalyst shows high activity when decomposing ammonia, but it is expensive because it is a noble metal, which is a problem in terms of cost. Further, the activity is insufficient under the use conditions at low temperatures, and the performance degradation due to the sintering of the catalyst has been a problem under the use conditions at high temperatures.
本発明は、高価な白金族を用いず、触媒活性種を無機質担体に担持せしめなくても極めて高い触媒活性を有する新規なアンモニア分解触媒、および該触媒を用いたアンモニアの分解方法の提供を目的とする。 An object of the present invention is to provide a novel ammonia decomposition catalyst having an extremely high catalytic activity without using an expensive platinum group and supporting a catalytically active species on an inorganic support, and an ammonia decomposition method using the catalyst. And
本発明者は、鋭意研究を重ねた結果、特定の元素の組み合わせを含むスピネル構造を有する複合酸化物、及び該複合酸化物を気相下に還元してなる触媒が上記目的を達成できることを見出した。その原理はまだ明らかになっていないが、スピネル構造を有する複合酸化物では、特定の金属元素同士が均一に結晶のレベルで分散した状態とすることができ、アンモニア分解反応に有効な距離に分散しているために高活性のアンモニア分解触媒を得ることができたものと思われる。
本発明は、かかる知見に基づいて完成したものであり、以下の構成を要旨とするものである。
（１）スピネル構造を有し、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素Ａ、Ｍｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素Ｂ（ただし、元素Ａと元素Ｂは異なる元素である。）、及び酸素を構成元素とする複合酸化物を含むことを特徴とするアンモニア分解触媒。
（２）前記複合酸化物が、一般式ＡＢ2Ｏ4（ただし、ＡはＭｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素であり、ＢはＭｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素である。）で表わされる、（１）に記載のアンモニア分解触媒。
（３）前記複合酸化物が、Ｃｏ−Ｆｅ系複合酸化物、Ｎｉ−Ｍｎ系複合酸化物、Ｃｏ−Ｍｎ系複合酸化物またはＭｇ−Ｆｅ系複合酸化物からなる（１）又は（２）に記載のアンモニア分解触媒。
（４）前記複合酸化物を還元ガスで還元処理してなる（１）〜（３）のいずれかに記載のアンモニア分解触媒。
（５）（１）〜（４）のいずれかに記載のスピネル構造を有する複合酸化物と、少なくとも該複合酸化物を構成する金属元素の単体金属、その金属元素の合金、又はその金属元素の酸化物のいずれか１種とを含有する、アンモニア分解触媒。
As a result of extensive research, the present inventor has found that a composite oxide having a spinel structure containing a combination of specific elements and a catalyst obtained by reducing the composite oxide in the gas phase can achieve the above-mentioned object. It was. The principle has not been clarified yet, but with complex oxides having a spinel structure, specific metal elements can be uniformly dispersed at the crystalline level, and dispersed at a distance effective for the ammonia decomposition reaction. Therefore, it is considered that a highly active ammonia decomposition catalyst could be obtained.
The present invention has been completed based on such findings, and has the following structure.
(1) It has a spinel structure and is selected from the group consisting of one or more elements A, Mn, Fe, Co and Ni selected from the group consisting of Mg, Ca, Sr, Ba, Mn, Fe, Co and Ni. An ammonia decomposition catalyst comprising one or more elements B (wherein element A and element B are different elements) and a composite oxide containing oxygen as a constituent element.
(2) The composite oxide is a general formula AB 2 O 4 (where A is one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Mn, Fe, Co, and Ni; Is one or more elements selected from the group consisting of Mn, Fe, Co and Ni.) The ammonia decomposition catalyst according to (1).
(3) (1) or (2), wherein the composite oxide is made of a Co—Fe composite oxide, a Ni—Mn composite oxide, a Co—Mn composite oxide, or a Mg—Fe composite oxide. The ammonia decomposition catalyst as described.
(4) The ammonia decomposition catalyst according to any one of (1) to (3), wherein the composite oxide is reduced with a reducing gas.
(5) The composite oxide having the spinel structure according to any one of (1) to (4) and at least a single metal of a metal element constituting the composite oxide, an alloy of the metal element, or an alloy of the metal element An ammonia decomposition catalyst containing any one of oxides.
（６）（１）〜（５）のいずれかに記載のアンモニア分解触媒の存在下でアンモニアを分解することを特徴とするアンモニア分解方法。
（７）分解温度が３００℃〜７００℃である、（６）に記載のアンモニア分解方法。
（８）（１）〜（５）のいずれかに記載のアンモニア分解触媒を使用することを特徴とするアンモニア分解反応装置。
(6) A method for decomposing ammonia, comprising decomposing ammonia in the presence of the ammonia decomposing catalyst according to any one of (1) to (5).
(7) The ammonia decomposition method according to (6), wherein the decomposition temperature is 300 ° C to 700 ° C.
(8) An ammonia decomposition reaction apparatus using the ammonia decomposition catalyst according to any one of (1) to (5).
本発明によれば、高価な白金族を用いず、触媒活性種を無機質担体に担持せしめなくても極めて高い触媒活性を有する安価なアンモニア分解能を示す触媒が提供される。
また、本発明によれば、かかる触媒を使用することにより、熱耐久性が高く高温においてもシンタリングによる触媒性能の劣化が起こらず、アンモニアを水と窒素に効率良く分解する方法、或いは、アンモニアから燃料電池用の水素と窒素とを効率的に製造する方法が提供される。
According to the present invention, there is provided a catalyst exhibiting an inexpensive ammonia decomposability having an extremely high catalytic activity without using an expensive platinum group and supporting a catalytically active species on an inorganic carrier.
Further, according to the present invention, by using such a catalyst, a method for efficiently decomposing ammonia into water and nitrogen without causing deterioration of catalyst performance due to sintering, even at high temperatures, or ammonia Provides a method for efficiently producing hydrogen and nitrogen for fuel cells.
本発明のアンモニア分解触媒における複合酸化物は、スピネル構造を有し、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素Ａ、Ｍｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素Ｂ（ただし、元素Ａと元素Ｂは異なる元素である。）、及び酸素を構成元素とする複合酸化物を含むことを特徴とするアンモニア分解触媒である。 The composite oxide in the ammonia decomposition catalyst of the present invention has a spinel structure, and one or more elements A, Mn, Fe, selected from the group consisting of Mg, Ca, Sr, Ba, Mn, Fe, Co, and Ni, Ammonia decomposition characterized by containing one or more elements B selected from the group consisting of Co and Ni (provided that element A and element B are different elements) and a complex oxide containing oxygen as a constituent element It is a catalyst.
本願においてスピネル構造とは、空間群Ｆｄ３ｍに属し、その空間群の酸素サイトである３２eサイトのつくる正四面体型４配位空間である８aサイト及び正八面体型６配位空間である１６ｄサイトが、Ａ元素又はＢ元素で占有された結晶構造をいう。ここで、３２eサイトの一部には欠損が存在していても構わない。 In the present application, the spinel structure belongs to the space group Fd3m, and the 8a site that is a tetrahedral tetracoordinate space formed by the 32e site that is the oxygen site of the space group and the 16d site that is a regular octahedral hexacoordinate space, The crystal structure occupied by the A element or B element. Here, a defect may exist in a part of the 32e site.
前記複合酸化物は、一般式ＡＢ2Ｏ4（ただし、ＡはＭｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素であり、ＢはＭｎ、Ｆｅ、Ｃｏ及びＮｉからなる群から選ばれる１種以上の元素である。）で表される。
元素Ａとしては、Ｍｇ、Ｍｎ、Ｃｏ、Ｆｅが好ましい。特にＣｏが好ましい。Ｂ元素としては、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉが好ましく、特にＦｅが好ましい。
また、本願においてスピネル構造とは基本的には一般式ＡＢ2Ｏ4で表されるが、Ａサイトの元素の一部とＢサイトの元素の一部が相互に置換していても良く、その酸素の組成は複合酸化物が電気的中性を保つように、欠損していても良いし、又は過剰量存在していても良い。その欠損量または過剰量をδとすると、δはスピネル構造を維持できる量であれば特に限定されないが、−０．０５≦δ≦０．０５であるのが好ましい。
The composite oxide has the general formula AB 2 O 4 (where A is one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Mn, Fe, Co, and Ni, and B is Mn, And one or more elements selected from the group consisting of Fe, Co, and Ni.
As the element A, Mg, Mn, Co, and Fe are preferable. Co is particularly preferable. As the B element, Mn, Fe, Co, and Ni are preferable, and Fe is particularly preferable.
In the present application, the spinel structure is basically represented by the general formula AB 2 O 4. However, a part of the A site element and a part of the B site element may be substituted with each other. The composition of oxygen may be deficient or may be present in excess so that the composite oxide remains electrically neutral. If the deficient amount or excess amount is δ, δ is not particularly limited as long as it can maintain the spinel structure, but preferably −0.05 ≦ δ ≦ 0.05.
本発明の複合酸化物が、スピネル構造である場合は、一般式ＡＢ2Ｏ4で表わされるのが好ましい。本発明の複合酸化物における元素Ａと元素Ｂの組み合わせとしては、Ｃｏ−Ｆｅ，Ｎｉ−Ｆｅ，Ｃｏ−Ｍｎ，Ｎｉ−Ｍｎ，Ｆｅ−Ｍｎ，Ｍｇ−Ｆｅ，Ｍｇ−Ｃｏ，又はＭｇ−Ｎｉが好ましい。
本発明のより好ましい複合酸化物としては、ＣｏＦｅ２Ｏ４、ＦｅＣｏ２Ｏ４、ＭｎＣｏ２Ｏ４、ＭｎＮｉ２Ｏ４、ＭｇＦｅ２Ｏ４を例示することができる。
本発明では、これらの複合酸化物は、上記各金属元素の炭酸塩、塩基性炭酸塩、有機酸塩、又は水酸化物の共沈体、又はそれらの混合物を有機酸と水溶液または有機溶媒中で反応させて得られる複合有機酸塩を、乾燥し、焼成することにより得られる。
When the composite oxide of the present invention has a spinel structure, it is preferably represented by the general formula AB 2 O 4 . As a combination of the element A and the element B in the composite oxide of the present invention, Co—Fe, Ni—Fe, Co—Mn, Ni—Mn, Fe—Mn, Mg—Fe, Mg—Co, or Mg—Ni may be used. preferable.
More preferable composite oxides of the present invention include CoFe 2 O 4 , FeCo 2 O 4 , MnCo 2 O 4 , MnNi 2 O 4 , and MgFe 2 O 4 .
In the present invention, these composite oxides are prepared by combining a carbonate, basic carbonate, organic acid salt, or hydroxide coprecipitate of each of the above metal elements, or a mixture thereof in an organic acid and an aqueous solution or an organic solvent. The complex organic acid salt obtained by reacting with the above is dried and calcined.
本発明におけるスピネル構造を有する複合酸化物は、既知方法で製造でき、特に、構成元素の均質性の観点からクエン酸法で製造するのが好ましい。クエン酸法は、上記各金属元素の炭酸塩、塩基性炭酸塩、有機酸塩、又は水酸化物の共沈体、又はそれらの混合物を有機酸と水溶液または有機溶媒中で反応させて得られる複合有機酸塩を、乾燥し、焼成する方法である。 The composite oxide having a spinel structure in the present invention can be produced by a known method, and in particular, it is preferably produced by a citric acid method from the viewpoint of the homogeneity of constituent elements. The citric acid method is obtained by reacting a carbonate, basic carbonate, organic acid salt or hydroxide coprecipitate of each of the above metal elements, or a mixture thereof in an aqueous solution or an organic solvent. In this method, the composite organic acid salt is dried and fired.
上記有機酸としては、多塩基性の有機酸が好ましく、例えば、クエン酸、ギ酸、又は酢酸がより好ましく、なかでもクエン酸がその金属塩の水への溶解度を高くできるので更に好ましい。
複合有機酸塩を使用する場合は、４００〜７００℃、好ましくは５００〜６００℃，４〜２４時間、好ましくは６〜１２時間で酸素含有雰囲気、好ましくは大気中で仮焼成し、必要に応じて粉砕し、焼成することが好ましい。
As the organic acid, a polybasic organic acid is preferable. For example, citric acid, formic acid, or acetic acid is more preferable, and citric acid is more preferable because it can increase the solubility of the metal salt in water.
When using a complex organic acid salt, it is calcined in an oxygen-containing atmosphere, preferably in the air at 400 to 700 ° C., preferably 500 to 600 ° C., 4 to 24 hours, preferably 6 to 12 hours. It is preferable to pulverize and fire.
焼成は、酸素含有雰囲気、好ましくは大気中で、８００〜１４００℃、好ましくは９００〜１１００℃で４〜２４時間、好ましくは６〜１２時間行う。焼成後、得られた複合酸化物をボールミル、ジェットミル等で粉砕して、粒度及び比表面積を制御してもよい。 Firing is performed in an oxygen-containing atmosphere, preferably in the air, at 800 to 1400 ° C., preferably 900 to 1100 ° C., for 4 to 24 hours, preferably 6 to 12 hours. After firing, the obtained composite oxide may be pulverized with a ball mill, jet mill or the like to control the particle size and specific surface area.
上記複合酸化物は、好ましくは気相法で還元処理を行ってアンモニア分解反応に用いるのが好ましい。還元処理は、複合酸化物を、還元性のガスの雰囲気に暴露することにより行うのが好ましい。還元性のガスとしては、水素ガス、アンモニアガス、ヒドラジンガス、一酸化炭素等が挙げられるが、なかでも水素ガスが安価であり、還元力も高く好ましい。
還元性ガスは、それだけで使用することが好ましいが、不活性ガスと混合して用いても良い。その場合の混合ガス中の還元性ガス濃度は３〜１００体積%が好ましい。また、還元性ガスはアンモニアガスを用いても良い。不活性ガスとしては、窒素、アルゴン又はヘリウムが好ましいが、なかでも窒素ガス又はアルゴンガスが好ましい。
The composite oxide is preferably used for the ammonia decomposition reaction after being reduced by a gas phase method. The reduction treatment is preferably performed by exposing the composite oxide to a reducing gas atmosphere. Examples of the reducing gas include hydrogen gas, ammonia gas, hydrazine gas, and carbon monoxide. Among them, hydrogen gas is preferable because it is inexpensive and has a high reducing power.
The reducing gas is preferably used by itself, but may be used by mixing with an inert gas. In this case, the reducing gas concentration in the mixed gas is preferably 3 to 100% by volume. Further, ammonia gas may be used as the reducing gas. As the inert gas, nitrogen, argon or helium is preferable, and nitrogen gas or argon gas is particularly preferable.
複合酸化物と還元性ガスの還元処理時間は３０分以上が好ましく、１〜２時間がより好ましい。また、還元反応の温度は、３００℃以上が好ましく、３００〜７００℃がより好ましい。還元処理方法は、例えば、９７パーセントＡｒ＋３パーセントＨ２の還元性ガス下で上記アンモニア分解用触媒を１時間６００℃で熱処理することで行う。またアンモニア気流中、４００〜９００℃で、直接還元処理を行うこともできる。 The reduction treatment time of the composite oxide and the reducing gas is preferably 30 minutes or more, and more preferably 1 to 2 hours. Further, the temperature of the reduction reaction is preferably 300 ° C. or higher, and more preferably 300 to 700 ° C. The reduction treatment is performed, for example, by heat-treating the ammonia decomposition catalyst at 600 ° C. for 1 hour in a reducing gas of 97 percent Ar + 3 percent H 2 . Moreover, a direct reduction process can also be performed at 400-900 degreeC in ammonia stream.
上記複合酸化物は還元処理を行うことにより、アンモニアガスの分解やアンモニアガスから水素と窒素との生成をより高転化率で行うことができる。これは、複合酸化物中に活性点を析出させ、元素Ａ及び／又は元素Ｂの金属の粒子が複合酸化物粒子中に分散された状態で形成されるためと思われる。
還元性ガスにより還元処理された複合酸化物は、スピネル構造を有する複合酸化物と、少なくとも該複合酸化物を構成する金属元素の単体金属、その金属元素の合金、又はその金属元素の酸化物のいずれか１種とを含有するが、特に、還元処理後に含まれる元素Ａ及び元素Ｂの単独金属または合金の合計原子数が、還元処理前の複合酸化物中の元素Ａ及び元素Ｂの合計原子数の１〜９０％であるのが好ましい。
The composite oxide can be subjected to a reduction treatment to decompose ammonia gas and generate hydrogen and nitrogen from the ammonia gas at a higher conversion rate. This is presumably because active sites are precipitated in the composite oxide, and the metal particles of element A and / or element B are formed in a dispersed state in the composite oxide particles.
A composite oxide reduced by a reducing gas is composed of a composite oxide having a spinel structure, a simple metal of at least a metal element constituting the composite oxide, an alloy of the metal element, or an oxide of the metal element. In particular, the total number of atoms of the single metal or alloy of element A and element B included after the reduction treatment is the total number of atoms of element A and element B in the composite oxide before the reduction treatment. It is preferably 1 to 90% of the number.
本発明のアンモニア分解触媒は、上記した元素Ａ又は元素Ｂを含むスピネル構造を有する複合酸化物を含有するが、これに加えて、該複合酸化物を構成する金属元素の単体金属、その金属の合金、および、その金属の酸化物の１種以上を含有することができる。
かかる場合、上記の金属元素の単体金属、その金属の合金、および、その金属の酸化物は、それぞれ、３〜９０％、３〜９０％、０〜９０％含有することが好ましい。
The ammonia decomposition catalyst of the present invention contains a composite oxide having a spinel structure containing the element A or element B described above. In addition to this, a simple metal of the metal element constituting the composite oxide, One or more of an alloy and an oxide of the metal can be contained.
In such a case, it is preferable that the elemental metal of the metal element, the alloy of the metal, and the oxide of the metal are contained in an amount of 3 to 90%, 3 to 90%, and 0 to 90%, respectively.
本発明の上記複合酸化物を含むアンモニア分解触媒は、高活性であるので、既知のアルミナ、シリカ、ムライト等の無機担体を用いなくても使用できるが、必要に応じて無機担体を用いてもよい。無機担体への本発明のアンモニア触媒の担持方法は、特に限定されず、既知の担持方法が採用される。無機担体に担持する場合、担持触媒中の本発明のアンモニア触媒の担持量は１０質量％以上が好ましい。
本発明のアンモニア分解触媒は、粒状、造粒状、ペレット状、円柱状等の種々の形状が採用できる。
Since the ammonia decomposition catalyst containing the above complex oxide of the present invention has high activity, it can be used without using a known inorganic carrier such as alumina, silica, mullite, etc., but if necessary, an inorganic carrier can also be used. Good. The method for supporting the ammonia catalyst of the present invention on the inorganic carrier is not particularly limited, and a known supporting method is adopted. When supported on an inorganic carrier, the supported amount of the ammonia catalyst of the present invention in the supported catalyst is preferably 10% by mass or more.
The ammonia decomposition catalyst of the present invention can employ various shapes such as granular, granulated, pellet-shaped, and columnar.
本発明のアンモニア分解触媒は、ＢＥＴ比表面積は１．５〜８．０ｍ２／ｇであるのが好ましい。また、平均粒子径（Ｄ５０）は１．５〜１５μｍが好ましく、１．０〜１０μｍがより好ましい。ペレット状である場合は、直径が３〜１０ｍｍ、厚み１〜３ｍｍであるのが好ましい。平均粒子径は、例えばレーザー散乱式粒度分布計で測定することができる。 The ammonia decomposition catalyst of the present invention preferably has a BET specific surface area of 1.5 to 8.0 m 2 / g. The average particle diameter (D 50) preferably 1.5～15Myuemu, 1.0 to 10 [mu] m is more preferable. In the case of a pellet, the diameter is preferably 3 to 10 mm and the thickness is 1 to 3 mm. The average particle diameter can be measured, for example, with a laser scattering particle size distribution meter.
本発明のアンモニア分解触媒を用いることによりアンモニアを分解することができる。アンモニアの分解は、公害防止などの観点から、有害物としてのアンモニアを水素と窒素に分解する場合や、エネルギー源としての水素製造の観点からアンモニアを分解して水素と窒素を製造する場合のいずれにも使用される。
本発明におけるアンモニア分解触媒を用いるアンモニアの分解反応は、温度が３００〜９００℃であるのが好ましく、４００〜６００℃がより好ましい。分解反応の温度が低い場合にはＮＯｘなどの窒素酸化物が副生されるが、本発明のアンモニア分解触媒は低い温度でも高い活性を有するので、窒素酸化物の副生を抑制できるので好ましい。アンモニアの体積空間速度は１０００〜１５０００ｈ−１であるのが好ましく、３０００〜１２０００ｈ−１であるのがより好ましい。アンモニアの分解時の圧力は、適宜調整することができ、常圧以下であるのがより好ましく、常圧であるのが特に好ましい。
Ammonia can be decomposed by using the ammonia decomposition catalyst of the present invention. Ammonia is decomposed either from the viewpoint of pollution prevention, when decomposing ammonia as a harmful substance into hydrogen and nitrogen, or from the viewpoint of hydrogen production as an energy source, when decomposing ammonia to produce hydrogen and nitrogen. Also used for.
In the ammonia decomposition reaction using the ammonia decomposition catalyst in the present invention, the temperature is preferably 300 to 900 ° C, more preferably 400 to 600 ° C. When the temperature of the decomposition reaction is low, nitrogen oxides such as NOx are by-produced. However, since the ammonia decomposition catalyst of the present invention has high activity even at a low temperature, it is preferable because by-products of nitrogen oxides can be suppressed. Is preferably a volume space velocity of ammonia is 1000~15000h -1, and more preferably 3000~12000h -1. The pressure at the time of decomposition of ammonia can be adjusted as appropriate, more preferably at or below normal pressure, and particularly preferably at normal pressure.
アンモニア分解反応の反応装置の形式に特に制限はないがバッチ式、連続式のいずれの装置も使用し得るが、連続式が効率が良く、量産性が良いので好ましい。また、固定床方式、又は流動床方式のいずれも採用できるが、固定床方式が好ましい。 There are no particular restrictions on the type of the ammonia decomposition reaction apparatus, but either a batch type or a continuous type can be used. However, the continuous type is preferable because of its high efficiency and good mass productivity. Moreover, although a fixed bed system or a fluidized bed system can be employed, a fixed bed system is preferable.
以下、実施例及び比較例により本発明を具体的に説明するが、本発明はこれらの実施例に限定して解釈されるべきではない。 EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention should not be limited and limited to these Examples.
実施例１
Ｃｏ：Ｆｅが原子比で１：２となるように、即ち炭酸コバルトを(Ｃｏとして４５．５２０ｗｔ％)５３．３６ｇとクエン酸鉄(Ｆｅとして１８．５１０ｗｔ％)２４８．７０ｇを秤量し、純水１Ｌに分散させた。その溶液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。
得られた複合クエン酸塩を大気中で、６００℃、６時間仮焼した後、電気炉内でそのまま徐冷した。サンプルミルで解砕して大気中で、９００℃で６時間焼成した。その結果、９０gの複合酸化物を得た。その後、ボールミルで粉砕を４０時間行い粒度、及びＢＥＴ比表面積を測定した。粒度分布測定にはＨＯＲＩＢＡ社製 レーザー回折/散乱式粒度分布測定装置（ＬＡＳＥＲ ＳＣＡＴＴＥＲＩＮＧ ＰＡＲＴＩＣＬＥ ＳＩＺＥ ＤＩＳＴＲＩＢＵＴＩＯＮ ＡＮＡＬＴＺＥＲ）ＬＡ−９２０を用い、ＢＥＴ比表面積測定にはＭＯＵＮＴＥＣＨ社製 全自動比表面積計（Ａｕｔｏ ｓｕｒｆａｃｅ Ａｒｅａ Ａｎａｌｙｚｅｒ）Ｍａｃｓｏｒｂ ｍｏｄｅｌ−１２０８を用いた。その結果、平均粒径Ｄ５０は９．４２μｍ、比表面積は２．５ｍ２／ｇであった。
Example 1
Weighing 53.36 g of cobalt carbonate (45.520 wt% as Co) and 248.70 g of iron citrate (18.510 wt% as Fe) so that Co: Fe has an atomic ratio of 1: 2. Disperse in 1 L of water. Citric acid necessary for all metal ions to form a complex was added to the solution and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate.
The obtained composite citrate was calcined at 600 ° C. for 6 hours in the air and then gradually cooled in an electric furnace. The sample was crushed and fired at 900 ° C. for 6 hours in the air. As a result, 90 g of composite oxide was obtained. Thereafter, pulverization was performed with a ball mill for 40 hours, and the particle size and BET specific surface area were measured. For the particle size distribution measurement, a laser diffraction / scattering particle size distribution measuring apparatus (LASER SCATTERING PARTICLE SIZE ANALYZER) LA-920 manufactured by HORIBA was used, and for the BET specific surface area measurement, a fully automatic specific surface area meter (Auto surface ArealAreAreaAreaAreArealArea) ) Macsorb model-1208 was used. As a result, the average particle diameter D 50 is 9.42Myuemu, the specific surface area was 2.5 m 2 / g.
この複合酸化物粉末をＣｕ−Ｋα線を用いた粉末X線回折測定(ＸＲＤ)により構造解析し、図３に示すように立方晶スピネル構造に帰属できる回折ピークを確認した。
原料仕込み組成及びＸ線回折スペクトルより、この複合酸化物は、スピネル構造のＣｏＦｅ２O４であることが分かった。
The composite oxide powder was subjected to structural analysis by powder X-ray diffraction measurement (XRD) using Cu—Kα rays, and a diffraction peak attributable to a cubic spinel structure was confirmed as shown in FIG.
From the raw material charge composition and the X-ray diffraction spectrum, it was found that this composite oxide was spinel-structured CoFe 2 O 4 .
ガラス製のアンモニア分解反応筒（１）（図２、参照、内径４ｍｍ、長さ１８０ｍｍ）にシリカウール（２）を詰め、その上に上記複合酸化物粉末（３）０．１ｇを充填した。更にそれをシリカウール（４）ではさんだ。そのアンモニア分解反応筒（１）を試験管（５）につないで電気炉（６）に入れ、６００℃に設定した。(図１参照) Silica wool (2) was packed in a glass ammonia decomposition reaction tube (1) (see FIG. 2, reference, inner diameter 4 mm, length 180 mm), and 0.1 g of the composite oxide powder (3) was packed thereon. Furthermore, it is sandwiched with silica wool (4). The ammonia decomposition reaction tube (1) was connected to a test tube (5), placed in an electric furnace (6), and set to 600 ° C. (See Figure 1)
アンモニア分解反応筒（１）に９７％Ａｒ＋３％Ｈ２ガスを約１時間流し、還元処理を行ったあとＮＨ３ガスとＡｒガスをマスフローコントローラーを用いて流量を調整し、アンモニア分解反応筒へ供給した。空間速度は４８００ｈ−１であった。 Supply 97% Ar + 3% H 2 gas to the ammonia decomposition reactor (1) for about 1 hour, perform reduction treatment, adjust the flow rate of NH 3 gas and Ar gas using a mass flow controller, and supply to the ammonia decomposition reactor did. The space velocity was 4800 h- 1 .
アンモニア分解能力の測定方法は触媒が充填されている反応筒の後に吸収びん（７）を設置し、未反応のアンモニアガスを吸収させた後、アンモニア以外のガス出口流量を測定することで、窒素及び水素への転化率を下記式を用いて測定した。出口ではＧＣ／ＭＳ（ＡＭＥＴＥＫ社 ＰｒｏＬｉｎｅ Ｍａｓｓ Ｓｐｅｃｔｒｏｍｅｔｅｒ）で窒素と水素が生成し、それ以外の成分は副生していなことを確認した。
アンモニアの転化率は表１に示すように１００％であった。
The method for measuring the ammonia decomposing ability is to install an absorption bottle (7) after the reaction cylinder filled with the catalyst, absorb the unreacted ammonia gas, and then measure the flow rate of the gas outlet other than ammonia. And the conversion to hydrogen was measured using the following formula. At the outlet, it was confirmed that GC and MS (AMETEK ProLine Mass Spectrometer) produced nitrogen and hydrogen, and other components were not by-produced.
As shown in Table 1, the conversion rate of ammonia was 100%.
また、別の実験で、９７％Ａｒ＋３％Ｈ２ガスを６００℃で１時間流し、上記複合酸化物粉末の還元処理を行ったあと、アンモニアガスを流さずに、反応筒を解体して、還元処理を行った後の粉末を取り出し、粉末X線回折測定を行い、図４に示すＸ線回折スペクトルを得た。 In another experiment, 97% Ar + 3% H 2 gas was flowed at 600 ° C. for 1 hour to reduce the composite oxide powder, and then the reactor was disassembled without flowing ammonia gas and reduced. The powder after the treatment was taken out and powder X-ray diffraction measurement was performed to obtain an X-ray diffraction spectrum shown in FIG.
図４より、還元処理後に新たにＣｏ金属、Ｃｏ−Ｆｅ合金、及びＣｏＯに帰属されるスペクトルが観察されることが分かった。図３および図４より、還元処理によって、もとの複合酸化物中の元素AおよびBが、還元されてＣｏ金属、Ｆｅ金属及びＣｏＯに転化していることがわかった。 From FIG. 4, it was found that spectra attributable to Co metal, Co—Fe alloy, and CoO were newly observed after the reduction treatment. 3 and 4, it was found that the elements A and B in the original composite oxide were reduced and converted into Co metal, Fe metal, and CoO by the reduction treatment.
実施例２
Ｃｏ：Ｆｅが原子比で２：１となるように、即ち、炭酸コバルト(Ｃｏとして４５．５２０ｗｔ％)１０５．３８ｇ、クエン酸鉄(Ｆｅとして１８．５１０ｗｔ％)１２２．７９ｇを秤量し、純水１Ｌに分散させた。その溶液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を大気中で、６００℃、６時間仮焼した後、電気炉内でそのまま徐冷した。サンプルミルで解砕して大気中で、９００℃で６時間焼成した。
Example 2
Co: Fe was adjusted to an atomic ratio of 2: 1, that is, 105.38 g of cobalt carbonate (45.520 wt% as Co) and 122.79 g of iron citrate (18.510 wt% as Fe) were weighed. Disperse in 1 L of water. Citric acid necessary for all metal ions to form a complex was added to the solution and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours in the air and then gradually cooled in an electric furnace. The sample was crushed and fired at 900 ° C. for 6 hours in the air.
その後、ボールミルで粉砕を行い粒度、及びＢＥＴ比表面積を測定した。実施例１と同様にＸ線回折スペクトルを測定した。原料仕込み組成と、Ｘ線回折スペクトルから、生成物は、立方晶スピネル構造を有するＦｅＣｏ２Ｏ４であることが分かった。平均粒径Ｄ５０は１．８１μｍ、比表面積は３．７ｍ２／ｇであった。以下実施例１と同様にしてアンモニア分解評価を行った。反応温度は６００℃、空間速度は４５００ｈ−１であった。その結果、がアンモニアの転化率は表１に示すように８４％であった。 Then, it grind | pulverized with the ball mill and measured the particle size and the BET specific surface area. The X-ray diffraction spectrum was measured in the same manner as in Example 1. From the raw material charge composition and the X-ray diffraction spectrum, it was found that the product was FeCo 2 O 4 having a cubic spinel structure. The average particle diameter D 50 is 1.81Myuemu, the specific surface area was 3.7 m 2 / g. Hereinafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 4500 h −1 . As a result, the conversion rate of ammonia was 84% as shown in Table 1.
実施例３
Ｎｉ：Ｍｎが原子比で２：１となるように、即ち、炭酸ニッケル(Ｎｉとして２９．６９０ｗｔ％)１７３．１６ｇ、炭酸マンガン(Ｍｎとして４４．３５ｗｔ％)５４．２５ｇを秤量し、純水１Ｌに分散させた。その溶液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を大気中で、６００℃、６時間仮焼した後、電気炉内でそのまま徐冷した。サンプルミルで解砕して大気中で、９００℃で６時間焼成した。
Example 3
Ni: Mn is 2: 1 in atomic ratio, that is, nickel carbonate (29.690 wt% as Ni) 173.16 g and manganese carbonate (Mn as 44.35 wt%) 54.25 g are weighed and purified water 1 L was dispersed. Citric acid necessary for all metal ions to form a complex was added to the solution and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours in the air and then gradually cooled in an electric furnace. The sample was crushed and fired at 900 ° C. for 6 hours in the air.
その後、ボールミルで粉砕を行い粒度、及びＢＥＴ比表面積を測定した。実施例１と同様にＸ線回折スペクトルを測定した。原料仕込み組成と、Ｘ線回折スペクトルから、生成物は、立方晶スピネル構造を有するＭｎＮｉ２Ｏ４であることが分かった。平均粒径Ｄ５０は１．４μｍ、比表面積は３．１ｍ２／ｇであった。以下実施例１と同様にしてアンモニア分解評価を行った。反応温度は６００℃、空間速度は２９００ｈ−１であった。その結果アンモニアの転化率は表１に示すように９３％であった。 Then, it grind | pulverized with the ball mill and measured the particle size and the BET specific surface area. The X-ray diffraction spectrum was measured in the same manner as in Example 1. From the raw material charging composition and the X-ray diffraction spectrum, it was found that the product was MnNi 2 O 4 having a cubic spinel structure. The average particle diameter D 50 was 1.4 [mu] m, a specific surface area of 3.1m 2 / g. Hereinafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 2900 h −1 . As a result, the conversion rate of ammonia was 93% as shown in Table 1.
実施例４
Ｃｏ：Ｍｎが原子比で２：１となるように、即ち、炭酸コバルト(Ｃｏとして４５．５２０ｗｔ％)１０５．７７ｇ、炭酸マンガン(Ｍｎとして４４．３５ｗｔ％)５０．６０ｇを秤量し、純水１Ｌに分散させた。その溶液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を大気中で、６００℃、６時間仮焼した後、電気炉内でそのまま徐冷した。サンプルミルで解砕して大気中で、９００℃で６時間焼成した。
Example 4
Co: Mn is 2: 1 in atomic ratio, that is, 105.77 g of cobalt carbonate (45.520 wt% as Co) and 50.60 g of manganese carbonate (44.35 wt% as Mn) are weighed and purified water 1 L was dispersed. Citric acid necessary for all metal ions to form a complex was added to the solution and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours in the air and then gradually cooled in an electric furnace. The sample was crushed and fired at 900 ° C. for 6 hours in the air.
その後、ボールミルで粉砕を行い粒度、及びＢＥＴ比表面積を測定した。実施例１と同様にＸ線回折スペクトルを測定した。原料仕込み組成と、Ｘ線回折スペクトルから、生成物は、立方晶スピネル構造を有するＭｎＣｏ２Ｏ4であることが分かった。平均粒径Ｄ５０は１．８μｍ、比表面積は１．９ｍ２／ｇであった。以下、実施例１と同様にしてアンモニア分解評価を行った。反応温度は６００℃、空間速度は５２００ｈ−１であった。その結果アンモニアの転化率は表１に示すように７７％であった。 Then, it grind | pulverized with the ball mill and measured the particle size and the BET specific surface area. The X-ray diffraction spectrum was measured in the same manner as in Example 1. From the raw material charge composition and the X-ray diffraction spectrum, it was found that the product was MnCo 2 O 4 having a cubic spinel structure. The average particle diameter D 50 is 1.8 .mu.m, the specific surface area was 1.9m 2 / g. Thereafter, ammonia decomposition evaluation was performed in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 5200 h −1 . As a result, the conversion rate of ammonia was 77% as shown in Table 1.
実施例５
Ｍｇ：Ｆｅが原子比で１：２となるように、即ち、炭酸マグネシウム(Ｍｇとして２５．２０ｗｔ％)４８．２３ｇ、クエン酸鉄(Ｆｅとして１８．５１０ｗｔ％)３０１．７１ｇを秤量し、純水１Ｌに分散させた。その溶液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を大気中で、６００℃、６時間仮焼した後、電気炉内でそのまま徐冷した。サンプルミルで解砕して大気中で、９００℃で６時間焼成した。
Example 5
Weigh Mg.Fe so that the atomic ratio is 1: 2, that is, 48.23 g of magnesium carbonate (25.20 wt% as Mg) and 301.71 g of iron citrate (18.510 wt% as Fe). Disperse in 1 L of water. Citric acid necessary for all metal ions to form a complex was added to the solution and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours in the air and then gradually cooled in an electric furnace. The sample was crushed and fired at 900 ° C. for 6 hours in the air.
その後、ボールミルで粉砕を行い粒度、及びＢＥＴ比表面積を測定した。実施例１と同様にＸ線回折スペクトルを測定した。原料仕込み組成と、Ｘ線回折スペクトルから、生成物は、立方晶スピネル構造を有するＭｇＦｅ２Ｏ4であることが分かった。平均粒径Ｄ５０は２．４μｍ、比表面積は２．８ｍ２／ｇであった。以下、実施例１と同様にしてアンモニア分解評価を行った。反応温度は６００℃、空間速度は３５００ｈ−１であった。その結果、アンモニアの転化率は表１に示すように７６％であった。 Then, it grind | pulverized with the ball mill and measured the particle size and the BET specific surface area. The X-ray diffraction spectrum was measured in the same manner as in Example 1. From the raw material charge composition and the X-ray diffraction spectrum, it was found that the product was MgFe 2 O 4 having a cubic spinel structure. The average particle diameter D 50 was 2.4 [mu] m, a specific surface area of 2.8 m 2 / g. Thereafter, ammonia decomposition evaluation was performed in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 3500 h −1 . As a result, the conversion rate of ammonia was 76% as shown in Table 1.
比較例１
アルミナ（高純度化学研究所 比表面積 ９２．６３ｍ２／ｇ）に対して５ｗｔ％のルテニウムとなるように塩化ルテニウムを溶解させた溶液にアルミナを含浸させた後、６００℃で焼成し、ルテニウムを担持したアルミナを得た。
実施例１と同様にして測定した平均粒径Ｄ５０は２．８μｍであり、ＢＥＴ比表面積は８５．６ｍ２／ｇであった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度１８００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は１００％であった。
Comparative Example 1
After impregnating alumina into a solution in which ruthenium chloride is dissolved so as to be 5 wt% of ruthenium with respect to alumina (specific surface area 92.63 m 2 / g of High-Purity Chemical Laboratory), the ruthenium is baked at 600 ° C. A supported alumina was obtained.
The average particle size D 50 was measured in the same manner as in Example 1 is 2.8 .mu.m, BET specific surface area was 85.6m 2 / g. Ammonia decomposition evaluation was carried out in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 1800 h- 1 . As a result, the conversion rate was 100%.
比較例２
クエン酸鉄（鉄として１８．５１０ｗｔ％）を９００℃で６時間焼成し、酸化鉄（II,IIII）（Ｆｅ３Ｏ４）を得た。実施例１と同様にして測定した平均粒径Ｄ５０は１．９３μｍであり、ＢＥＴ比表面積は５．８ｍ２／ｇであった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度２７００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は６３％であった。
Comparative Example 2
Iron citrate (18.510 wt% as iron) was fired at 900 ° C. for 6 hours to obtain iron oxide (II, IIII) (Fe 3 O 4 ). The average particle size D 50 was measured in the same manner as in Example 1 was 1.93μm, BET specific surface area was 5.8 m 2 / g. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 2700 h −1 . As a result, the conversion rate was 63%.
比較例３
炭酸コバルト（コバルトとして５０．９００ｗｔ％）を６００℃で６時間焼成し、四酸化三コバルト（Ｃｏ３Ｏ４）を得た。実施例１と同様にして測定した平均粒径Ｄ５０は１．１０μｍであり、ＢＥＴ比表面積は４．０ｍ２／ｇであった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度４８００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は６２％であった。
Comparative Example 3
Cobalt carbonate (50.900 wt% as cobalt) was calcined at 600 ° C. for 6 hours to obtain tricobalt tetroxide (Co 3 O 4 ). The average particle size D 50 was measured in the same manner as in Example 1 was 1.10 .mu.m, BET specific surface area was 4.0 m 2 / g. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to be a space velocity of 4800 h- 1 . As a result, the conversion rate was 62%.
比較例４
アルミナ（高純度化学研究所 比表面積 ９２．６３ｍ２／ｇ）に対して５ｗt％の鉄となるように塩化鉄を溶解させた溶液にアルミナを含浸させた後、６００℃で焼成し、鉄を担持したアルミナを得た。
実施例１と同様にして測定した平均粒径Ｄ５０は２．４μｍであった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度２２００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は４５％であった。
Comparative Example 4
After impregnating alumina in a solution in which iron chloride is dissolved so that it becomes 5 wt% iron with respect to alumina (specific surface area 92.63 m 2 / g, High Purity Chemical Research Laboratory), the iron is baked at 600 ° C. A supported alumina was obtained.
The average particle size D 50 was measured in the same manner as in Example 1 was 2.4 [mu] m. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 2200 h −1 . As a result, the conversion rate was 45%.
比較例５
アルミナ（高純度化学研究所 比表面積 ９２．６３ｍ２／ｇ）に対して５ｗt％のコバルトとなるように炭酸コバルトを溶解させた溶液にアルミナを含浸させた後、６００℃で焼成し、鉄を担持したアルミナを得た。
実施例１と同様にして測定した平均粒径Ｄ５０は２．１６μｍであり、ＢＥＴ比表面積は７４．０ｍ２／ｇであった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度２１００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は３６％であった。
Comparative Example 5
After impregnating alumina in a solution in which cobalt carbonate is dissolved so that it becomes 5 wt% cobalt with respect to alumina (specific surface area 92.63 m 2 / g of High Purity Chemical Laboratory), it is baked at 600 ° C. A supported alumina was obtained.
The average particle size D 50 was measured in the same manner as in Example 1 was 2.16μm, BET specific surface area was 74.0m 2 / g. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 2100 h −1 . As a result, the conversion rate was 36%.
比較例６
比較例２での酸化鉄（II,III）に対して２５ｗｔ％のコバルトとなるように炭酸コバルトを溶解させた溶液に比較例２で作成した酸化鉄（II,III）を含浸させた後、６００℃で焼成し、コバルトを担持した酸化鉄（II,III）を得た。
アンモニアガスとアルゴンガスの混合ガスの流量を空間速度５６００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は１１％であった。
Comparative Example 6
After impregnating the iron oxide (II, III) prepared in Comparative Example 2 into a solution in which cobalt carbonate was dissolved so as to be 25 wt% cobalt with respect to the iron oxide (II, III) in Comparative Example 2, Calcination was performed at 600 ° C. to obtain iron oxide (II, III) supporting cobalt.
Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 5600 h −1 . As a result, the conversion rate was 11%.
比較例７
Ｚｎ：Ｃｏが原子比で１：２となるように、即ち、炭酸亜鉛（Ｚｎとして５８．５７ｗｔ％）４５．１５ｇ、炭酸コバルト(Ｃｏとして５０．９００ｗｔ％)９３．６５ｇを秤量し、純水１Ｌに分散させた。その分散液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を６００℃で６時間仮焼した後、サンプルミルで解砕して、大気中で９００℃６時間焼成した。実施例１と同様にして測定した平均粒径Ｄ５０は１．１９μｍであり、ＢＥＴ比表面積は６．４ｍ２／ｇであった。Ｘ線回折スペクトルから、生成物は、スピネル構造を有することが分かった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度５３００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は３６％であった。
Comparative Example 7
Weighed 45.15 g of zinc carbonate (58.57 wt% as Zn) and 93.65 g of cobalt carbonate (50.900 wt% as Co) so that the atomic ratio of Zn: Co was 1: 2, pure water 1 L was dispersed. Citric acid necessary for all metal ions to form a complex was added to the dispersion and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours, then crushed by a sample mill, and calcined in the atmosphere at 900 ° C. for 6 hours. The average particle size D 50 was measured in the same manner as in Example 1 was 1.19μm, BET specific surface area was 6.4 m 2 / g. From the X-ray diffraction spectrum, the product was found to have a spinel structure. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 5300 h −1 . As a result, the conversion rate was 36%.
比較例８
Ｚｎ：Ｆｅが原子比で１：２となるように、即ち、炭酸亜鉛（Ｚｎとして５８．５７ｗｔ％）４６．３１ｇ、クエン酸鉄（Ｆｅとして１８．５１０ｗｔ％）２５０．２９ｇを秤量し、純水１Ｌに分散させた。その分散液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を６００℃で６時間仮焼した後、サンプルミルで解砕して、大気中で９００℃６時間焼成した。実施例１と同様にして測定した平均粒径Ｄ５０は１．８５μｍであり、ＢＥＴ比表面積は１．８ｍ２／ｇであった。Ｘ線回折スペクトルから、生成物は、スピネル構造を有することが分かった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度４５００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は３８％であった。
Comparative Example 8
Weigh Zn.Fe in an atomic ratio of 1: 2, ie 46.31 g of zinc carbonate (58.57 wt% as Zn) and 250.29 g of iron citrate (18.510 wt% as Fe). Disperse in 1 L of water. Citric acid necessary for all metal ions to form a complex was added to the dispersion and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours, then crushed by a sample mill, and calcined in the atmosphere at 900 ° C. for 6 hours. The average particle size D 50 was measured in the same manner as in Example 1 was 1.85, BET specific surface area was 1.8 m 2 / g. From the X-ray diffraction spectrum, the product was found to have a spinel structure. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 4500 h- 1 . As a result, the conversion rate was 38%.
比較例９
ランタン：コバルト：鉄が原子比で１：０．５：０．５となるように、即ち、酸化ランタン(Ｌａとして８４．９１５ｗｔ％)４０．１８ｇ、炭酸コバルト(Ｃｏとして４５．７００ｗｔ％)１５．８４ｇ、クエン酸鉄(鉄として８．０２０ｗｔ％)８５．５１ｇを秤量し、純水１Ｌに分散させた。その分散液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を６００℃で６時間仮焼した後、サンプルミルで解砕して、大気中で９００℃６時間焼成した。実施例１と同様にして測定した平均粒径Ｄ５０は０．５３μｍであり、ＢＥＴ比表面積は０．２６ｍ２／ｇであった。Ｘ線回折スペクトルから、生成物は、ペロブスカイト型構造を有することが分かった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度１２０００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は１２％であった。
Comparative Example 9
Lanthanum: cobalt: iron in an atomic ratio of 1: 0.5: 0.5, that is, lanthanum oxide (84.915 wt% as La) 40.18 g, cobalt carbonate (45.700 wt% as Co) 15 .84 g and iron citrate (8.020 wt% as iron) 85.51 g were weighed and dispersed in 1 L of pure water. Citric acid necessary for all metal ions to form a complex was added to the dispersion and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours, then crushed by a sample mill, and calcined in the atmosphere at 900 ° C. for 6 hours. The average particle size D 50 was measured in the same manner as in Example 1 was 0.53 .mu.m, BET specific surface area was 0.26 m 2 / g. From the X-ray diffraction spectrum, the product was found to have a perovskite structure. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 12000 h- 1 . As a result, the conversion rate was 12%.
比較例１０
ランタン：コバルト：鉄：ニッケルが原子比で１：０．３３：０．３３：０．３３となるように、即ち、酸化ランタン(Ｌａとして８４．９１５ｗｔ％)６７．８０ｇ、炭酸コバルト(Ｃｏとして４５．７００ｗｔ％)１７．６４ｇ、クエン酸鉄(鉄として８．０２０ｗｔ％)９５．２４ｇ、炭酸ニッケル(ニッケルとして２９．９８０ｗｔ％)２７．０５ｇを秤量し、純水１Ｌに分散させた。その分散液に全金属イオンが錯体を形成するのに必要なクエン酸を加え６５±５℃で反応させた。反応終了後、得られた溶液を９０℃で乾燥し、複合クエン酸塩を得た。得られた複合クエン酸塩を６００℃で６時間仮焼した後、サンプルミルで解砕して、大気中で９００℃６時間焼成した。実施例１と同様にして測定した平均粒径Ｄ５０は０．８９μｍであり、ＢＥＴ比表面積は３．８ｍ２／ｇであった。Ｘ線回折スペクトルから、生成物は、ペロブスカイト型構造を有することが分かった。アンモニアガスとアルゴンガスの混合ガスの流量を空間速度３５００ｈ−１となるように調整した以外は、実施例１と同様にしてアンモニア分解評価を行った。その結果、転化率は４２％であった。
Comparative Example 10
Lanthanum: cobalt: iron: nickel in an atomic ratio of 1: 0.33: 0.33: 0.33, that is, 67.80 g of lanthanum oxide (84.915 wt% as La), cobalt carbonate (as Co 45.700 wt%) 17.64 g, iron citrate (8.020 wt% as iron) 95.24 g, nickel carbonate (29.980 wt% as nickel) 27.05 g were weighed and dispersed in 1 L of pure water. Citric acid necessary for all metal ions to form a complex was added to the dispersion and reacted at 65 ± 5 ° C. After completion of the reaction, the resulting solution was dried at 90 ° C. to obtain a complex citrate. The obtained composite citrate was calcined at 600 ° C. for 6 hours, then crushed by a sample mill, and calcined in the atmosphere at 900 ° C. for 6 hours. The average particle size D 50 was measured in the same manner as in Example 1 was 0.89μm, BET specific surface area was 3.8 m 2 / g. From the X-ray diffraction spectrum, the product was found to have a perovskite structure. Ammonia decomposition evaluation was performed in the same manner as in Example 1 except that the flow rate of the mixed gas of ammonia gas and argon gas was adjusted to a space velocity of 3500 h −1 . As a result, the conversion rate was 42%.
表１に実施例と比較例の触媒評価の結果を示す。実施例１および実施例２において、本発明のＣｏ−Ｆｅ系触媒の評価結果を示す。６００℃という低温で転化率８０％以上を示した。
実施例３のＮｉ−Ｍｎ系触媒の転化率は９３％と非常に高い値を示した。実施例４のＣｏ−Ｍｎ系触媒は７７％と比較的高い値を示した。実施例５のＭｇ−Ｆｅ系触媒は金属の単純酸化物であるＡｌ２Ｏ３にＦｅやＣｏを担持した比較例４や比較例５の転化率より高い値を示した。以上の結果より、本発明のアンモニア分解触媒は高いアンモニア分解能を有していることが分かる。
比較例１（特開平８−８４９１０号）記載の触媒であり、従来知られている白金族であるＲｕを無機質担体に担持したものは、６００℃において１００％の転化率を示した。しかし、Ｒｕが非常に高価であるため実機への搭載は難しい。
Table 1 shows the results of catalyst evaluation in Examples and Comparative Examples. In Example 1 and Example 2, the evaluation results of the Co—Fe-based catalyst of the present invention are shown. The conversion was 80% or higher at a low temperature of 600 ° C.
The conversion rate of the Ni-Mn catalyst of Example 3 was as high as 93%. The Co—Mn catalyst of Example 4 showed a relatively high value of 77%. The Mg—Fe-based catalyst of Example 5 showed a higher value than the conversion rates of Comparative Examples 4 and 5 in which Fe and Co were supported on Al 2 O 3 which is a simple metal oxide. From the above results, it can be seen that the ammonia decomposition catalyst of the present invention has high ammonia decomposing ability.
The catalyst described in Comparative Example 1 (Japanese Patent Application Laid-Open No. 8-84910), in which Ru, which is a conventionally known platinum group, was supported on an inorganic carrier, showed a conversion rate of 100% at 600 ° C. However, since Ru is very expensive, it is difficult to mount it on an actual machine.
次に、比較例２、３において活性金属の単純酸化物を評価したが、転化率は６３％、６２％と比較的低い結果となった。比較例４、比較例５および比較例６において、本発明の活性金属種であると考えられる金属を無機質担体に担持した。しかしながら、その転化率は、それぞれ４５％、３６％、１１％という低い結果となった。このことは金属活性種を単純酸化物である無機質担体に担持したのではアンモニアの分解に大きな効果を示さないことを示している。 Next, simple oxides of active metals were evaluated in Comparative Examples 2 and 3. The conversion rates were relatively low, 63% and 62%. In Comparative Example 4, Comparative Example 5 and Comparative Example 6, a metal considered to be an active metal species of the present invention was supported on an inorganic carrier. However, the conversion rates were as low as 45%, 36%, and 11%, respectively. This indicates that if the metal active species is supported on an inorganic carrier which is a simple oxide, it does not show a great effect on the decomposition of ammonia.
比較例７、８は鉄もしくはコバルト一方のみで構成したスピネル複合酸化物触媒であるが、転化率はどちらも低い結果となっている。これより、鉄とコバルトのどちらかを含有するスピネル構造触媒でも高転化率は得られないことがわかり、鉄とコバルトの両方がアンモニア分解反応に必要であることが示唆される。比較例９、１０では鉄とコバルトを含有し、スピネル構造ではないペロブスカイト型構造をもつ複合酸化物を評価したが、いずれも転化率は低い結果となった。還元処理後のペロブスカイト触媒の相構造を観察すると還元処理前とほとんど変わらず、有効に活性金属種を生成できていない。
このことからスピネル構造を持つことが還元処理において活性金属種を析出させるのに適当な酸素不安定性を与えていることが示唆され、スピネル構造がアンモニア分解特性に重要であることがわかる。
Comparative Examples 7 and 8 are spinel composite oxide catalysts composed of only iron or cobalt, but both have low conversion rates. This shows that a high conversion cannot be obtained even with a spinel structure catalyst containing either iron or cobalt, suggesting that both iron and cobalt are necessary for the ammonia decomposition reaction. In Comparative Examples 9 and 10, composite oxides containing iron and cobalt and having a perovskite structure that was not a spinel structure were evaluated, but all had low conversion rates. When the phase structure of the perovskite catalyst after the reduction treatment is observed, it is almost the same as that before the reduction treatment, and active metal species cannot be effectively generated.
This suggests that having a spinel structure provides an appropriate oxygen instability for precipitating active metal species in the reduction treatment, indicating that the spinel structure is important for ammonia decomposition characteristics.
比較例１〜１０の結果より活性種と考えられる鉄とコバルトのどちらかを含有、もしくはスピネル構造を有するだけではアンモニア分解に活性な触媒は得られず、本発明の触媒である特定の元素の組み合わせを含有し、スピネル構造を有することがアンモニア分解に活性な触媒を得るための鍵となっていることが分かる。 From the results of Comparative Examples 1 to 10, it is impossible to obtain a catalyst active for ammonia decomposition only by containing either iron or cobalt, which is considered to be an active species, or having a spinel structure. It can be seen that the combination and the spinel structure are the key to obtaining a catalyst active in ammonia decomposition.
本発明のアンモニア分解触媒は、有害なアンモニアを水と窒素に効率良く分解する場合や、アンモニアから燃料電池用の水素と窒素とを効率的に製造する場合などのアンモニアの分解に広く利用できる。 The ammonia decomposing catalyst of the present invention can be widely used for decomposing ammonia when efficiently decomposing harmful ammonia into water and nitrogen, or when efficiently producing hydrogen and nitrogen for fuel cells from ammonia.
１・・・アンモニア分解反応筒
２・・・シリカウール
３・・・複合酸化物粉末
４・・・シリカウール
５・・・試験管
６・・・電気炉
７・・・吸収びん
DESCRIPTION OF SYMBOLS 1 ... Ammonia decomposition reaction tube 2 ...
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| JP2012161713A (en) * | 2011-02-03 | 2012-08-30 | Agc Seimi Chemical Co Ltd | Ammonia decomposition catalyst and decomposition method of ammonia |
| JP2014522724A (en) * | 2011-08-08 | 2014-09-08 | ユニヴェルシテット・ヤジェロンスキ | Catalyst for direct decomposition of nitric oxide and process for producing the catalyst |
| CN108031474A (en) * | 2017-12-14 | 2018-05-15 | 西安元创化工科技股份有限公司 | A kind of coke-stove gas ammonia decomposition catalyzer and preparation method thereof |
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| CN114751369A (en) * | 2022-05-19 | 2022-07-15 | 重庆大学 | MnCo2O4.5-MgH2Composite hydrogen storage material and preparation method thereof |
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| CN114751369A (en) * | 2022-05-19 | 2022-07-15 | 重庆大学 | MnCo2O4.5-MgH2Composite hydrogen storage material and preparation method thereof |
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