JP5690158B2 - Ammonia decomposition catalyst and ammonia decomposition method - Google Patents
Ammonia decomposition catalyst and ammonia decomposition method Download PDFInfo
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- JP5690158B2 JP5690158B2 JP2011022002A JP2011022002A JP5690158B2 JP 5690158 B2 JP5690158 B2 JP 5690158B2 JP 2011022002 A JP2011022002 A JP 2011022002A JP 2011022002 A JP2011022002 A JP 2011022002A JP 5690158 B2 JP5690158 B2 JP 5690158B2
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims description 273
- 229910021529 ammonia Inorganic materials 0.000 title claims description 135
- 238000000354 decomposition reaction Methods 0.000 title claims description 94
- 239000003054 catalyst Substances 0.000 title claims description 77
- 238000000034 method Methods 0.000 title claims description 30
- 239000002131 composite material Substances 0.000 claims description 62
- 239000002245 particle Substances 0.000 claims description 38
- 150000003112 potassium compounds Chemical class 0.000 claims description 19
- 150000003388 sodium compounds Chemical class 0.000 claims description 18
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 16
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 claims description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 53
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 37
- 238000006243 chemical reaction Methods 0.000 description 36
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 29
- 229910052739 hydrogen Inorganic materials 0.000 description 20
- 229910052742 iron Inorganic materials 0.000 description 20
- 229910052759 nickel Inorganic materials 0.000 description 20
- 239000001257 hydrogen Substances 0.000 description 19
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 18
- 239000000243 solution Substances 0.000 description 18
- 238000010304 firing Methods 0.000 description 17
- 229910052757 nitrogen Inorganic materials 0.000 description 17
- 238000002441 X-ray diffraction Methods 0.000 description 16
- 230000003197 catalytic effect Effects 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 229910001868 water Inorganic materials 0.000 description 13
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 12
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 12
- 239000002994 raw material Substances 0.000 description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 11
- 229910052746 lanthanum Inorganic materials 0.000 description 11
- 239000012071 phase Substances 0.000 description 11
- 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 10
- 238000010438 heat treatment Methods 0.000 description 9
- -1 organic acid salt Chemical class 0.000 description 9
- 150000007524 organic acids Chemical class 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 9
- 238000001228 spectrum Methods 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 7
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 238000001354 calcination Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 229910000027 potassium carbonate Inorganic materials 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 239000000470 constituent Substances 0.000 description 5
- 239000000446 fuel Substances 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 4
- OBWXQDHWLMJOOD-UHFFFAOYSA-H cobalt(2+);dicarbonate;dihydroxide;hydrate Chemical compound O.[OH-].[OH-].[Co+2].[Co+2].[Co+2].[O-]C([O-])=O.[O-]C([O-])=O OBWXQDHWLMJOOD-UHFFFAOYSA-H 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 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 4
- 229910052751 metal Inorganic materials 0.000 description 4
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 4
- 210000002268 wool Anatomy 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 description 3
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000002612 dispersion medium Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 2
- 239000001095 magnesium carbonate Substances 0.000 description 2
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000002904 solvent Substances 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
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910018921 CoO 3 Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ONIBWKKTOPOVIA-BYPYZUCNSA-N L-Proline Chemical compound OC(=O)[C@@H]1CCCN1 ONIBWKKTOPOVIA-BYPYZUCNSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- LRDAUUGUXQIHED-UHFFFAOYSA-N N.[N]=O Chemical compound N.[N]=O LRDAUUGUXQIHED-UHFFFAOYSA-N 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 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
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000000969 carrier Substances 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
- 229910000428 cobalt oxide Inorganic materials 0.000 description 1
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007423 decrease Effects 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
- 238000007598 dipping method Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 150000002500 ions 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
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 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
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003304 ruthenium compounds Chemical class 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 229910000018 strontium carbonate Inorganic materials 0.000 description 1
- 238000012916 structural analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
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Classifications
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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
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- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
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およ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、低温での使用条件において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 a low temperature, and the performance deterioration due to the sintering of the catalyst has been a problem under the use conditions at a high temperature.
一方、アンモニア含有排気ガスをアンモニア分解触媒に接触させて排気ガス中のアンモニアを窒素ガスと水とに分解して浄化する際に用いる触媒として、A ’ x A 1 − x B O 3 − y ( A ’ : C a 、S r 、A : L a 、B : M n 、F e 、C o) で表されるペロブスカイト系酸化物が提案されている。(特許文献4参照) On the other hand, the ammonia-containing exhaust gas is brought into contact with the ammonia decomposition catalyst of ammonia in the exhaust gas as a catalyst to be used for purifying decomposed into nitrogen gas and water, A 'x A 1 - x B O 3 - y ( Perovskite oxides represented by A ′: C a, S r, A: L a, B: M n, F e, Co) have been proposed. (See Patent Document 4)
また、特許文献5には、一般式La1-x Cex CoO3(式中、xは0〜1である。)のランタナ/セリア/コバルト酸化物組成物をアンモニア酸化触媒(アンモニアを窒素酸化物とする酸化反応)として用いることが提案されている。 Further, Patent Document 5, the general formula La 1-x Ce x CoO 3 ( where, x is 0-1.) Of lanthana / ceria / cobalt oxide compositions of the ammonia oxidation catalyst (ammonia nitrogen oxide It has been proposed to be used as an oxidation reaction).
しかし、これらの発明の組成式ABO3で表されるペロブスカイト型酸化物は排気ガス中の微量アンモニアの除去を目的としたものであり、生成物への転化率が低く工業的に大量に水素を合成するような用途には適用が困難であるという問題があった。 However, the perovskite oxides represented by the composition formula ABO 3 of these inventions are intended for the removal of trace amounts of ammonia in the exhaust gas, and have a low conversion rate to the product and industrially produce a large amount of hydrogen. There is a problem that it is difficult to apply to uses such as synthesis.
本発明は、高価な白金族を触媒の活性種として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 decomposing catalyst having an extremely high catalytic activity without supporting an expensive platinum group as an active species of the catalyst on a carrier, and an ammonia decomposing method using the catalyst.
本発明者らは、鋭意研究を重ねた結果、La、Ni、Co、及びFeを含有する複合酸化物の表面にカリウム金属もしくはナトリウム金属またはそれらの化合物を存在させた触媒が上記目的を達成できることを見出した。さらに、ABO3で表されるペロブスカイト構造またはA2BO4で表される層状ペロブスカイト構造を有する複合酸化物のBサイトにNiとCoとFeの3元素を同時に含有する複合酸化物の表面に、カリウム金属もしくはナトリウム金属またはそれらの化合物を存在させた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、La、Ni、Co、及びFeを含有する複合酸化物の表面に存在するナトリウム金属もしくはカリウム金属、またはそれらの化合物が活性点となり転化率の高いアンモニア分解触媒を得ることができたものと考えられる。 As a result of intensive studies, the present inventors have found that a catalyst in which potassium metal or sodium metal or a compound thereof is present on the surface of a composite oxide containing La, Ni, Co, and Fe can achieve the above object. I found. Furthermore, on the surface of the composite oxide containing simultaneously three elements of Ni, Co and Fe at the B site of the composite oxide having a perovskite structure represented by ABO 3 or a layered perovskite structure represented by A 2 BO 4 , It has been found that a catalyst in which potassium metal or sodium metal or a compound thereof is present can achieve the above object. Although the principle has not been clarified yet, the decomposition of ammonia with high conversion rate by using sodium metal or potassium metal present on the surface of the complex oxide containing La, Ni, Co, and Fe, or their compounds as active sites It is considered that a catalyst could be obtained.
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)ペロブスカイト構造を有する下記式(1)で表わされる複合酸化物、または層状ペロブスカイト構造を有する下記式(2)で表わされる複合酸化物の複合酸化物粒子の表面にナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合物が存在することを特徴とするアンモニア分解触媒。
La 1−x Sr x Ni y Co z Fe 1−y−z O 3 (1)
La 2−x Sr x Ni y Co z Fe 1−y−z O 4 (2)
(ただし、式(1)においては、0≦x<1、0<y<1、0<z<1であり、y+z<1を満足し、式(2)においては、0≦x<2、0<y<1、0<z<1であり、y+z<1を満足する。)
The present invention has been completed based on such findings, and has the following structure.
(1) Sodium metal or potassium metal on the surface of a composite oxide represented by the following formula (1) having a perovskite structure, or a composite oxide particle of the composite oxide represented by the following formula (2) having a layered perovskite structure , Alternatively, an ammonia decomposition catalyst characterized by the presence of a sodium compound or a potassium compound.
La 1-x Sr x Ni y Co z Fe 1-y-z O 3 (1)
La 2-x Sr x Ni y Co z Fe 1-y-z O 4 (2)
(However, in Formula (1), 0 ≦ x <1, 0 <y <1, 0 <z <1, and satisfy y + z <1, and in Formula (2), 0 ≦ x <2, (0 <y <1, 0 <z <1, and y + z <1 is satisfied.)
(2)0.20≦y≦0.40、0.20≦z≦0.40である(1)に記載のアンモニア分解触媒。
(3)ナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合物の含有量が5〜30重量%である、(1)または(2)に記載のアンモニア分解触媒。
(4)(1)〜(3)のいずれか1項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。
(5)分解温度が300〜800℃である(4)に記載のアンモニア分解方法。
(6)(1)〜(3)のいずれか1項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。
( 2 ) The ammonia decomposition catalyst according to (1) , wherein 0.20 ≦ y ≦ 0.40 and 0.20 ≦ z ≦ 0.40.
( 3 ) The ammonia decomposition catalyst according to (1) or (2) , wherein the content of sodium metal or potassium metal, or sodium compound or potassium compound is 5 to 30% by weight.
( 4 ) A method for decomposing ammonia, comprising decomposing ammonia in the presence of the ammonia decomposing catalyst according to any one of (1) to ( 3 ).
( 5 ) The ammonia decomposition method according to ( 4 ), wherein the decomposition temperature is 300 to 800 ° C.
( 6 ) An ammonia decomposition reaction apparatus using the ammonia decomposition catalyst according to any one of (1) to ( 3 ).
本発明によれば、高価な白金族を触媒の活性種として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、および同触媒を用いたアンモニアの分解方法を提供することができる。
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、ある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を提供することができる。
According to the present invention, it is possible to provide a novel ammonia decomposition catalyst having an extremely high catalytic activity without supporting an expensive platinum group as an active species of the catalyst on a carrier, and a method for decomposing ammonia using the catalyst. it can.
Further, according to the present invention, by using such a catalyst, the thermal performance is high and the catalyst performance does not deteriorate due to sintering even at high temperatures, and ammonia is efficiently decomposed into water and nitrogen, or from ammonia. A method for efficiently producing hydrogen and nitrogen for a fuel cell can be provided.
本発明にかかるアンモニア分解触媒に適用される複合酸化物は、La、Ni、Co、及びFeを含有する複合酸化物であり、式(1)で表されるペロブスカイト構造ABO3を有する複合酸化物、または式(2)で表される層状ペロブスカイト構造A2BO4を有する複合酸化物である。
La1−xSrxNiyCozFe1−y−zO3 (1)
(ただし、0≦x<1、0<y<1、0<z<1であり、y+z<1を満足する。)
La2−xSrxNiyCozFe1−y−zO4 (2)
(ただし、0≦x<2、0<y<1、0<z<1であり、y+z<1を満足する。)
Composite oxide which is applied to the ammonia decomposition catalyst according to the present invention, La, Ni, Co, and Ri composite oxide der containing Fe, composite oxide having a perovskite structure ABO 3 of the formula (1) object, or a composite oxide having a layered perovskite structure a 2 BO 4 represented by the formula (2).
La 1-x Sr x Ni y Co z Fe 1-y-z O 3 (1)
(However, 0 ≦ x <1, 0 <y <1, 0 <z <1, and y + z <1 is satisfied.)
La 2-x Sr x Ni y Co z Fe 1-y-z O 4 (2)
(However, 0 ≦ x <2, 0 <y <1, 0 <z <1, and y + z <1 is satisfied.)
このようなペロブスカイト構造または層状ペロブスカイト構造のBサイト元素としては、Niと、Coと、Feとを同時に含有するのが好ましい。Niと、Coと、Feとからなる3元素のうちいずれか1元素でも欠けるとアンモニアの窒素と水素への転化率が低下するので好ましくない。
また、上記式(1)または式(2)中の酸素Oの組成は複合酸化物が電気的中性を保つように、欠損していてもよいし、または過剰量存在していてもよい。その欠損量または過剰量をδとすると、δはペロブスカイト構造または層状ペロブスカイト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 B site element of such a perovskite structure or a layered perovskite structure preferably contains Ni, Co, and Fe simultaneously. If any one of the three elements consisting of Ni, Co, and Fe is lacking, the conversion rate of ammonia into nitrogen and hydrogen decreases, which is not preferable.
In addition, the composition of oxygen O in the above formula (1) or formula (2) may be deficient or may be present in excess so that the composite oxide is kept electrically neutral. If the deficient amount or excess amount is δ, δ is not particularly limited as long as it can maintain the perovskite structure or the layered perovskite structure, but preferably −0.05 ≦ δ ≦ 0.05.
本発明のアンモニア分解触媒に適用される複合酸化物は前記式(1)または式(2)において、0.20≦y≦0.40、0.20≦z≦0.40であることを特徴とするものが好ましい。アンモニアの水素と窒素への転化率が高いからである。
本発明のアンモニア分解触媒に適用される複合酸化物は前記式(1)において、0≦x≦0.6であることがさらに好ましい。アンモニアの水素と窒素への転化率が高いからである。
本発明のアンモニア分解触媒に適用される複合酸化物は前記式(2)において、0.5≦x≦1.5であることがさらに好ましい。アンモニアの水素と窒素への転化率が高いからである。
The composite oxide applied to the ammonia decomposition catalyst of the present invention is characterized in that, in the formula (1) or formula (2), 0.20 ≦ y ≦ 0.40 and 0.20 ≦ z ≦ 0.40. Are preferred. This is because the conversion rate of ammonia into hydrogen and nitrogen is high.
The composite oxide applied to the ammonia decomposition catalyst of the present invention is more preferably 0 ≦ x ≦ 0.6 in the formula (1). This is because the conversion rate of ammonia into hydrogen and nitrogen is high.
The composite oxide applied to the ammonia decomposition catalyst of the present invention is more preferably 0.5 ≦ x ≦ 1.5 in the formula (2). This is because the conversion rate of ammonia into hydrogen and nitrogen is high.
本願にかかる発明は、ペロブスカイト構造または層状ペロブスカイト構造の酸化物粒子の表面にナトリウム金属もしくはカリウム金属、またはそれらの化合物が存在することが好ましい。ナトリウム化合物またはカリウム化合物としては、取扱いが容易であるので酸化物または炭酸塩が好ましく、炭酸塩が特に好ましい。 In the invention according to the present application, it is preferable that sodium metal, potassium metal, or a compound thereof exists on the surface of the oxide particle having a perovskite structure or a layered perovskite structure. As the sodium compound or potassium compound, oxides or carbonates are preferable because of easy handling, and carbonates are particularly preferable.
本発明にかかるアンモニア分解触媒は、ペロブスカイト構造または層状ペロブスカイト構造の酸化物粒子の表面にナトリウム金属もしくはカリウム金属、またはそれらの化合物を存在させることにより製造するのが好ましい。 The ammonia decomposition catalyst according to the present invention is preferably produced by allowing sodium metal or potassium metal or a compound thereof to be present on the surface of oxide particles having a perovskite structure or a layered perovskite structure.
次に、本発明にかかるLa、Ni、Co、及びFeを含有する複合酸化物の製造方法と該複合酸化物を用いたアンモニア分解触媒の製造方法について説明する。 Next, a method for producing a composite oxide containing La, Ni, Co, and Fe according to the present invention and a method for producing an ammonia decomposition catalyst using the composite oxide will be described.
本発明にかかるLa、Ni、Co、及びFeを含有する複合酸化物は、固相法、湿式法などの既知方法で製造できる。特に、構成元素の均質性の観点から湿式法である有機酸塩法で製造するのが好ましい。有機酸塩法は、複合酸化物を構成する各金属元素A、Bの炭酸塩、塩基性炭酸塩、有機酸塩、水酸化物、水酸化物の共沈体もしくはそれらの混合物を有機酸と水または有機溶媒中で反応させて複合有機酸塩を中間体として経由し、続いてその複合有機酸塩を乾燥し、その乾燥粉を仮焼成し、本焼成する方法である。 The composite oxide containing La, Ni, Co, and Fe according to the present invention can be produced by a known method such as a solid phase method or a wet method. In particular, it is preferable to manufacture by the organic acid salt method which is a wet method from the viewpoint of the homogeneity of the constituent elements. In the organic acid salt method, carbonates, basic carbonates, organic acid salts, hydroxides, hydroxide coprecipitates of the metal elements A and B constituting the composite oxide, or mixtures thereof are combined with organic acids. This is a method in which the reaction is carried out in water or an organic solvent, the complex organic acid salt is passed as an intermediate, the complex organic acid salt is subsequently dried, the dried powder is pre-fired, and the main firing is performed.
上記有機酸としては、クエン酸、ギ酸、または酢酸が好ましく、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より好ましい。
複合有機酸塩を生成させるのに使用する有機酸の量は、特に限定されないが、より均質な複合有機酸塩を生成させるためには、有機酸中に存在するカルボキシル基の数と有機酸のモル数の積である有機酸の当量数が、複合酸化物の構成元素AまたはBの価数と構成元素AとBのモル数との積の和である構成元素の当量数よりも多いことが好ましい。構成元素AとBのイオンが有機酸中のカルボキシル基と配位し錯体を形成するためである。
As the organic acid, citric acid, formic acid, or acetic acid is preferable, and citric acid is more preferable because it can increase the solubility of the metal salt in water.
The amount of the organic acid used to form the complex organic acid salt is not particularly limited, but in order to produce a more homogeneous complex organic acid salt, the number of carboxyl groups present in the organic acid and the number of organic acids The number of equivalents of the organic acid that is the product of the number of moles is greater than the number of equivalents of the constituent elements that is the sum of the products of the valence of the constituent element A or B of the composite oxide and the number of moles of the constituent elements A and B Is preferred. This is because the ions of the constituent elements A and B coordinate with the carboxyl group in the organic acid to form a complex.
次に、上記の複合有機酸塩を仮焼成する。仮焼成の焼成温度は400〜700℃が好ましく、500〜600℃が特に好ましい。仮焼成の焼成温度が、400℃以上であると有機酸の炭素成分が残留しにくいので好ましい。また、700℃以下であると構成元素が偏析しにくいので好ましい。
仮焼成の焼成時間は4〜24時間が好ましく、6〜12時間が特に好ましい。仮焼成の焼成時間が、4時間以上であると有機酸の炭素成分が残留しにくいので好ましい。また、24時間以下であると構成元素が偏析しにくいので好ましい。また、仮焼成の焼成雰囲気は酸素含有雰囲気が好ましく、大気中が特に好ましい。焼成雰囲気中に酸素が存在しないと、生成物中に目的とするペロブスカイト相または層状ペロブスカイト相以外の不純物相が存在し、触媒活性を低下させる虞があるので、酸素含有雰囲気が好ましい。仮焼成によって得られた仮焼成粉は、必要に応じてカッターミル、ジェットミル、アトマイザーなどの解砕・粉砕機を用い、一般には乾式で解砕する。
Next, the complex organic acid salt is temporarily fired. 400-700 degreeC is preferable and the firing temperature of temporary baking is especially preferable 500-600 degreeC. It is preferable that the calcining temperature of the pre-firing is 400 ° C. or higher because the carbon component of the organic acid hardly remains. Moreover, since it is hard to segregate a structural element as it is 700 degrees C or less, it is preferable.
The calcining time for the preliminary calcination is preferably 4 to 24 hours, particularly preferably 6 to 12 hours. It is preferable that the calcining time of the pre-firing is 4 hours or longer because the carbon component of the organic acid hardly remains. Moreover, since it is hard to segregate a structural element as it is 24 hours or less, it is preferable. In addition, the pre-firing firing atmosphere is preferably an oxygen-containing atmosphere, and particularly preferably in the air. If oxygen is not present in the firing atmosphere, an impurity phase other than the target perovskite phase or layered perovskite phase is present in the product, which may reduce the catalytic activity, so an oxygen-containing atmosphere is preferred. The calcined powder obtained by calcining is generally crushed by a dry method using a crushing / pulverizing machine such as a cutter mill, a jet mill, or an atomizer as necessary.
次いで、上記の解砕粉を本焼成する。本焼成の焼成温度は、800〜1400℃が好ましく、900〜1100℃が特に好ましい。800℃以上であると、ペロブスカイト相または層状ペロブスカイト相以外の不純物相が生成しにくいので好ましい。また、1400℃以下であると、目的とするペロブスカイト相または層状ペロブスカイト相が分解する可能性が低下するので好ましい。
本焼成の焼成時間は、4〜24時間が好ましく、6〜12時間が特に好ましい。4時間以上であると、生成物中に未反応物質が残留しにくいので好ましく、24時間以下であると生産性が向上するので好ましい。また、本焼成の焼成雰囲気は酸素含有雰囲気が好ましく、大気中が特に好ましい。焼成雰囲気中に酸素が存在しないと、生成物中に目的とするペロブスカイト相または層状ペロブスカイト相以外の不純物相が存在し、触媒活性を低下させる虞があるので、酸素含有雰囲気とする。
Next, the pulverized powder is fired. The firing temperature of the main firing is preferably 800 to 1400 ° C, particularly preferably 900 to 1100 ° C. A temperature of 800 ° C. or higher is preferable because an impurity phase other than the perovskite phase or the layered perovskite phase is difficult to be generated. Moreover, since it is less than 1400 degreeC, possibility that the target perovskite phase or a layered perovskite phase will decompose | disassemble is reduced.
The firing time for the main firing is preferably 4 to 24 hours, and particularly preferably 6 to 12 hours. When it is 4 hours or longer, it is preferable because unreacted substances hardly remain in the product, and when it is 24 hours or shorter, productivity is improved, which is preferable. Further, the firing atmosphere of the main firing is preferably an oxygen-containing atmosphere, and particularly preferably in the air. If oxygen is not present in the calcination atmosphere, an impurity phase other than the target perovskite phase or layered perovskite phase is present in the product, and the catalytic activity may be reduced.
なお、仮焼成と本焼成は別の工程として記載したが、仮焼成の後、室温まで降温せずに続けて本焼成を行なってもよい。また、1回の焼成で徐々に温度を上げながら焼成してもよいし、何回かに分けて、徐々に温度を上げながら焼成してもよい。
本焼成によって得られた本焼成粉が焼結している場合は、解砕する。解砕後、得られた複合酸化物をボールミル、ジェットミルなどで粉砕して、粒度および比表面積を制御してもよい。
In addition, although temporary baking and this baking were described as a separate process, you may continue this baking after temperature reduction to room temperature after temporary baking. Further, firing may be performed while gradually raising the temperature in one firing, or firing may be performed while gradually raising the temperature in several times.
If the fired powder obtained by firing is sintered, it is crushed. After pulverization, the obtained composite oxide may be pulverized with a ball mill, a jet mill or the like to control the particle size and specific surface area.
次に、上記の方法で製造したLa、Ni、Co、及びFeを含有する複合酸化物粒子の表面にナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合物を担持させる。担持させる方法は特に限定されないが、複合酸化物粒子の表面に均質に担持させるという観点から含浸法が好ましい。 Next, sodium metal or potassium metal, or a sodium compound or potassium compound is supported on the surface of the composite oxide particles containing La, Ni, Co, and Fe produced by the above method. The method of supporting is not particularly limited, but the impregnation method is preferable from the viewpoint of uniformly supporting the surface of the composite oxide particles.
含浸法とは、上記の製造方法により製造されたLa、Ni、Co、及びFeを含有する複合酸化物の粉末をナトリウム化合物原料もしくはカリウム化合物原料が溶解した溶液、またはナトリウム化合物原料もしくはカリウム化合物原料が分散した分散液に浸漬し、濾過した後に乾燥するか、または濾過をしないで蒸発乾固し、熱処理する方法である。上記の溶液の溶媒、または分散液の分散媒としては、環境に対する負荷が軽く、また使用済み溶媒、または使用済み分散媒の後処理が容易なことから水が好ましい。また、ナトリウム化合物原料もしくはカリウム化合物原料が溶解した溶液を用いるのが好ましい。
ナトリウム化合物原料またはカリウム化合物原料としては、ナトリウムまたはカリウムの炭酸塩、シュウ酸塩、酸化物、水酸化物などが挙げられる。
The impregnation method is a solution in which a powder of a composite oxide containing La, Ni, Co, and Fe produced by the above production method is dissolved in a sodium compound raw material or a potassium compound raw material, or a sodium compound raw material or a potassium compound raw material Is a method of dipping in a dispersed dispersion and drying after filtration, or evaporating to dryness without filtration and heat treatment. As the solvent of the above solution or the dispersion medium of the dispersion, water is preferable because it has a light environmental burden and can be easily used after treatment of the used solvent or the used dispersion medium. Moreover, it is preferable to use a solution in which a sodium compound raw material or a potassium compound raw material is dissolved.
Examples of the sodium compound raw material or potassium compound raw material include sodium or potassium carbonate, oxalate, oxide, hydroxide and the like.
熱処理温度は、400℃から1000℃の範囲が好ましい。400℃以上であると複合酸化物粒子表面とナトリウム化合物またはカリウム化合物の密着性が向上し、触媒能が向上するので好ましく、1000℃以下であると活性点であるナトリウム化合物やカリウム化合物が凝集し、複合酸化物の表面に均質に分散しないため触媒能が低下する可能性が低くなるので好ましい。熱処理時間は5〜24時間が好ましい。また、熱処理の雰囲気は 大気中が好ましい。 The heat treatment temperature is preferably in the range of 400 ° C to 1000 ° C. When the temperature is 400 ° C. or higher, the adhesion between the surface of the composite oxide particle and the sodium compound or potassium compound is improved, and the catalytic ability is improved. When the temperature is 1000 ° C. or lower, the sodium compound or potassium compound that is the active site aggregates. It is preferable because the possibility that the catalytic performance is lowered is reduced because the composite oxide is not uniformly dispersed on the surface of the composite oxide. The heat treatment time is preferably 5 to 24 hours. The atmosphere for the heat treatment is preferably in the air.
なお、上記の含浸工程で、La、Ni、Co、及びFeを含有する複合酸化物粒子の表面に付着したナトリウム化合物またはカリウム化合物の一部が、引続き行われる熱処理により、ナトリウムイオンまたはカリウムイオンとしてLa、Ni、Co、及びFeを含有する酸化物の結晶格子中に拡散し、結晶構造中取り込まれていてもよい。 In the above impregnation step, a part of the sodium compound or potassium compound adhering to the surface of the composite oxide particles containing La, Ni, Co, and Fe is converted into sodium ions or potassium ions by a subsequent heat treatment. It may diffuse into the crystal lattice of an oxide containing La, Ni, Co, and Fe and be incorporated into the crystal structure.
La、Ni、Co、及びFeを含有する複合酸化物粒子の表面に担持されるナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合物のアンモニア分解触媒中の含有量は5〜30重量%が好ましい。5重量%以上であると触媒能をより発揮でき、30重量%以下であるとナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合物が凝集せずに、複合酸化物粒子の表面に均質に分散し触媒能が増加するため好ましい。 The content of sodium metal or potassium metal supported on the surface of the composite oxide particles containing La, Ni, Co, and Fe, or sodium compound or potassium compound in the ammonia decomposition catalyst is preferably 5 to 30% by weight. When the amount is 5% by weight or more, the catalytic ability can be further exerted. When the amount is 30% by weight or less, sodium metal or potassium metal, or sodium compound or potassium compound does not aggregate and is uniformly dispersed on the surface of the composite oxide particle. This is preferable because the catalytic ability is increased.
本発明にかかるアンモニア分解触媒のBET比表面積は0.8〜100.0m2/gであるのが好ましい。BET比表面積が0.8〜100.0m2/gであるとアンモニアと触媒粒子とが十分に接触し、触媒能が向上するので好ましい。また、平均粒子径(D50)は0.5〜15μmが好ましく、0.8〜10μmがより好ましい。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 BET specific surface area of the ammonia decomposition catalyst according to the present invention is preferably 0.8 to 100.0 m 2 / g. A BET specific surface area of 0.8 to 100.0 m 2 / g is preferable because ammonia and the catalyst particles are sufficiently in contact with each other and the catalytic performance is improved. The average particle diameter (D 50) preferably 0.5 to 15 m, 0.8 to 10 [mu] m is more preferable. The average particle diameter can be measured, for example, with a laser scattering particle size distribution meter.
本発明の上記複合酸化物およびナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合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に担持してもよい。無機担体への本発明に係るアンモニア分解触媒の担持方法は、特に限定されず、既知の担持方法を使用することができる。無機担体に本発明にかかるアンモニア分解触媒を担持する場合は、担持触媒中の本発明にかかるアンモニア分解触媒の担持量は10重量%以上が好ましい。10重量%以上であると単位重量当たりの触媒量が十分であるため、触媒能が向上するので好ましい。 The ammonia decomposition catalyst containing the above complex oxide and sodium metal or potassium metal, or sodium compound or potassium compound of the present invention is highly active, so it can be used without using known inorganic carriers such as alumina, silica, mullite and the like. However, it may be supported on an inorganic carrier as necessary. The method for supporting the ammonia decomposition catalyst according to the present invention on the inorganic carrier is not particularly limited, and a known supporting method can be used. When the ammonia decomposition catalyst according to the present invention is supported on an inorganic carrier, the supported amount of the ammonia decomposition catalyst according to the present invention in the supported catalyst is preferably 10% by weight or more. If it is 10% by weight or more, the amount of catalyst per unit weight is sufficient, so that the catalytic performance is improved, which is preferable.
本発明にかかるアンモニア分解触媒を用いたアンモニアの分解反応は、アンモニア分解装置中に、上記のナトリウム金属もしくはカリウム金属、またはナトリウム化合物もしくはカリウム化合物を複合酸化物の表面に存在させたアンモニア分解触媒を、粒状、造粒状、ペレット状、円柱状などの種々の形状で設置するか、担体や基体に塗布するなどの状態にして設置し、アンモニア分解触媒とアンモニアガスを接触させることにより行なう。 In the ammonia decomposition reaction using the ammonia decomposition catalyst according to the present invention, an ammonia decomposition catalyst in which the above-mentioned sodium metal or potassium metal, or sodium compound or potassium compound is present on the surface of the composite oxide is added to the ammonia decomposition apparatus. It is installed in various shapes such as granular, granulated, pellet, and columnar, or in a state where it is applied to a carrier or a substrate, and brought into contact with an ammonia decomposition catalyst and ammonia gas.
アンモニア分解反応の分解温度は、300〜800℃であるのが好ましく、400〜600℃がより好ましい。分解温度が300℃以上の場合には、反応速度が速くなり十分な活性が得られるので好ましく、800℃以下の場合には熱平衡がアンモニア生成側に偏ってしまうことがないため水素の生成量が向上するので好ましい。また、本発明のアンモニア分解触媒は、高い活性を有するので、上記のように比較的低温においてもNOXなどの窒素酸化物の副生を抑制できるので好ましい。 The decomposition temperature of the ammonia decomposition reaction is preferably 300 to 800 ° C, more preferably 400 to 600 ° C. When the decomposition temperature is 300 ° C. or higher, the reaction rate is high and sufficient activity can be obtained. When the decomposition temperature is 800 ° C. or lower, the thermal equilibrium is not biased toward the ammonia production side, so the amount of hydrogen generated is small. Since it improves, it is preferable. Further, the ammonia decomposition catalyst of the present invention has high activity, it is possible to suppress the by-production of nitrogen oxides such as NO X even at relatively low temperatures as described above preferable.
アンモニア分解を行なう際のアンモニアの体積空間速度は1000h−1から15000h−1であるのが好ましく、3000h−1から12000h−1であるのがより好ましい。1000h−1以上であると転化率は向上し、アンモニアの体積空間速度が十分であるために単位時間当たりの分解量が向上するので好ましく、15000h−1以下であるとアンモニアの流速が速すぎて、未分解のアンモニアが分解生成物中に含まれてしまう可能性が低下するので好ましい。反応は平衡上減圧雰囲気が好ましいが、装置が高価となるため、圧力は常圧でもよい。 Is preferably a volume space velocity of ammonia in performing ammonia decomposition is 15000H -1 from 1000h -1, and more preferably 12000H -1 from 3000h -1. If it is 1000 h −1 or more, the conversion rate is improved, and since the volumetric space velocity of ammonia is sufficient, the decomposition amount per unit time is improved, and if it is 15000 h −1 or less, the flow rate of ammonia is too high. This is preferable because the possibility that undecomposed ammonia is contained in the decomposition product is reduced. Although the reaction is preferably carried out in a reduced pressure atmosphere for equilibrium, the pressure may be normal because the apparatus becomes expensive.
アンモニア分解反応の反応装置の形式は特に制限されない。バッチ式、連続式のいずれの装置も使用し得るが、連続式の方が効率が良く、生産性が向上するので好ましい。また、固定床方式、また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。 The type of the ammonia decomposition reaction reactor is not particularly limited. Either batch-type or continuous-type devices can be used, but the continuous-type device is preferred because it is more efficient and productivity is improved. Moreover, although either a fixed bed system or a fluidized bed system can be adopted, a fixed bed system is preferable.
以下、実施例およ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
La:Ni:Co:Feが原子比で1.0:1/3:1/3:1/3となるように、即ち酸化ランタン(Laとして84.99wt%)270.97gと炭酸ニッケル(Niとして46.81wt%)68.60gと塩基性炭酸コバルト(Coとして59.03wt%)54.62gとクエン酸鉄水溶液(Feとして8.20wt%)372.60gを秤量し、純水1L(リットル)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量より50%多いクエン酸(982g)を加え65℃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時間仮焼した後に、電気炉内でそのまま徐冷した。続いてサンプルミルで解砕して大気中、900℃で6時間焼成した。その結果、400gの複合酸化物を得た。
Example 1
La: Ni: Co: Fe is in an atomic ratio of 1.0: 1/3: 1/3: 1/3, that is, 270.97 g of lanthanum oxide (84.99 wt% as La) and nickel carbonate (Ni Weighed 68.60 g of 46.81 wt%), 54.62 g of basic cobalt carbonate (59.03 wt% as Co) and 372.60 g of iron citrate aqueous solution (8.20 wt% as Fe), and weighed 1 L of pure water (liter ). To the solution, citric acid (982 g) 50% more than the amount of citric acid required for all metal ions to form a complex was added and reacted at 65 ° 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. Subsequently, it was crushed by a sample mill and baked in the atmosphere at 900 ° C. for 6 hours. As a result, 400 g of complex oxide was obtained.
この複合酸化物をCu−Kα線を用いたX線回折測定(XRD)により構造解析し、図1に示すように立方晶系ペロブスカイト構造のLaCo0.40Fe0.60O3と菱面体晶系ペロブスカイト構造のLaNi0.60Co0.40O3と菱面体晶系ペロブスカイト構造のLaCoO3に帰属できる回折ピークを確認した。X線回折測定の結果と原料の仕込み組成から、この複合酸化物はBサイトにNiとCoとFeが存在するペロブスカイト構造のLaNi1/3Co1/3Fe1/3O3であることが判った。 The composite oxide was subjected to structural analysis by X-ray diffraction measurement (XRD) using Cu—Kα rays, and as shown in FIG. 1, cubic perovskite structure LaCo 0.40 Fe 0.60 O 3 and rhombohedral crystals. A diffraction peak attributable to LaNi 0.60 Co 0.40 O 3 having a perovskite structure and LaCoO 3 having a rhombohedral perovskite structure was confirmed. From the results of X-ray diffraction measurement and the raw material composition, this composite oxide is LaNi 1/3 Co 1/3 Fe 1/3 O 3 having a perovskite structure in which Ni, Co, and Fe exist at the B site. understood.
次に、炭酸カリウム1.33gをイオン交換水40gに溶解させた溶液を作成した。この溶液に上記の複合酸化物であるLaNi1/3Co1/3Fe1/3O3を5.0g加え、マグネットスターラーで攪拌しながら約15時間浸漬した。
炭酸カリウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理しアンモニア分解触媒を得た。
Next, a solution was prepared by dissolving 1.33 g of potassium carbonate in 40 g of ion-exchanged water. To this solution, 5.0 g of LaNi 1/3 Co 1/3 Fe 1/3 O 3 as the composite oxide was added and immersed for about 15 hours while stirring with a magnetic stirrer.
A slurry composed of an aqueous potassium carbonate solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated in the atmosphere at 600 ° C. for 6 hours to obtain an ammonia decomposition catalyst.
その後、アンモニア分解触媒をボールミルで40時間粉砕した後、粒度およびBET比表面積を測定した。粒度分布測定にはHORIBA社製のレーザー回折/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社製の全自動比表面積計(AutoSurface Area Analyzer)Macsorb model−1208を用いた。その結果、平均粒径D50は0.97μmであり、比表面積は2.0m2/gであった。 Then, after crushing the ammonia decomposition catalyst with a ball mill for 40 hours, the particle size and the BET specific surface area were measured. For the particle size distribution measurement, a laser diffraction / scattering particle size distribution analyzer LA-920 manufactured by HORIBA (LASER SCATTERING PARTICLE SIZE ANALYZER) LA-920 is used. Analyzer) Macrosorb model-1208 was used. As a result, the average particle diameter D 50 was 0.97 .mu.m, a specific surface area of 2.0 m 2 / g.
石英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、その上に上記の粉砕したアンモニア分解触媒の粉末(3)0.1gを充填し、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3参照) Silica wool (2) is packed in an ammonia decomposition reaction tube (1) made of quartz glass (see FIG. 2, inner diameter 4 mm, length 180 mm), and 0.1 g of the above-mentioned pulverized ammonia decomposition catalyst powder (3) Is filled 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 3)
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、還元処理を行なった後に、NH3ガスとArガスと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4632h−1とした。 After 97% Ar + 3% H 2 gas was allowed to flow through the ammonia decomposition reaction cylinder (1) for about 1 hour and reduction treatment was performed, the flow rate of NH 3 gas and Ar gas was adjusted using a mass flow controller, and the ammonia decomposition reaction cylinder Supplied. The space velocity was 4632h- 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、窒素および水素への転化率を下記式を用いて算出した。その結果、アンモニアの転化率は93%であった。
なお、出口ではGC/MS(AMETEK社のProLine Mass Spectrometer)により、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。
The measuring method of 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. Conversion to nitrogen and hydrogen was calculated using the following formula. As a result, the conversion rate of ammonia was 93%.
In addition, it confirmed that nitrogen and hydrogen produced | generated by GC / MS (ProLine Mass Spectrometer of AMETEK) at the exit, and other components were not by-produced.
実施例2
実施例1と同様にしてLaNi1/3Co1/3Fe1/3O3を得た。次に炭酸ナトリウム0.75gをイオン交換水40gに溶解させ、この溶液に上記のLaNi1/3Co1/3Fe1/3O3を5.0g加え、マグネットスターラーで撹拌しながら約15時間浸漬した。
炭酸ナトリウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕し、粒度およびBET比表面積を測定した。その結果、平均粒度D50は1.19μm、比表面積は1.96m2/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なった。なお、反応温度は600℃、空間速度は5311h−1とした。その結果、アンモニアの転化率は97%であった。
Example 2
In the same manner as in Example 1, LaNi 1/3 Co 1/3 Fe 1/3 O 3 was obtained. Next, 0.75 g of sodium carbonate is dissolved in 40 g of ion-exchanged water, and 5.0 g of the above LaNi 1/3 Co 1/3 Fe 1/3 O 3 is added to this solution and stirred for about 15 hours with a magnetic stirrer. Soaked.
A slurry composed of a sodium carbonate aqueous solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the atmosphere.
The heat-treated ammonia decomposition catalyst was pulverized by a ball mill in the same manner as in Example 1, and the particle size and BET specific surface area were measured. As a result, the average particle size D 50 is 1.19Myuemu, a specific surface area of 1.96m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 5311 h −1 . As a result, the conversion rate of ammonia was 97%.
実施例3
La:Ni:Co:Feが原子比で1.0:0.20:0.40:0.40となるように、即ち酸化ランタン201.82gと炭酸ニッケル30.97gと塩基性炭酸コバルト49.31gとクエン酸鉄水溶液336.38gを秤量した以外は実施例1と同様にして複合酸化物300gを得た。
Example 3
La: Ni: Co: Fe is in an atomic ratio of 1.0: 0.20: 0.40: 0.40, that is, 201.82 g of lanthanum oxide, 30.97 g of nickel carbonate, and basic cobalt carbonate. 300 g of composite oxide was obtained in the same manner as in Example 1 except that 31 g and 336.38 g of iron citrate aqueous solution were weighed.
その後、実施例1と同様にX線回折スペクトルを測定した。X線回折スペクトルから、この複合酸化物は斜方晶系ペロブスカイト構造のLaCo0.40Fe0.60O3と菱面体晶系ペロブスカイト構造のLaNi0.60Co0.40O3に帰属できた。X線回折測定の結果と原料の仕込み組成から、この複合酸化物はBサイトにNiとCoとFeが存在するペロブスカイト構造のLaNi0.20Co0.40Fe0.40O3であることが判った。 Thereafter, the X-ray diffraction spectrum was measured in the same manner as in Example 1. From the X-ray diffraction spectrum, this composite oxide could be attributed to the orthorhombic perovskite structure LaCo 0.40 Fe 0.60 O 3 and the rhombohedral perovskite structure LaNi 0.60 Co 0.40 O 3 . . From the result of X-ray diffraction measurement and the raw material composition, this composite oxide is LaNi 0.20 Co 0.40 Fe 0.40 O 3 having a perovskite structure in which Ni, Co, and Fe exist at the B site. understood.
次に、炭酸カリウム1.33gをイオン交換水40gに溶解させた。この溶液に上記のLaNi0.20Co0.40Fe0.40O3を5.0g加え、マグネットスターラーで撹拌しながら約15時間浸漬した。
炭酸カリウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕した後、粒度および比表面積を測定した。その結果、平均粒径D50は1.35μmであり比表面積は1.1m2/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なった。なお、反応温度は600℃、空間速度は4800h−1とした。その結果、アンモニアの転化率は100%であった。
Next, 1.33 g of potassium carbonate was dissolved in 40 g of ion-exchanged water. 5.0 g of the above LaNi 0.20 Co 0.40 Fe 0.40 O 3 was added to this solution and immersed for about 15 hours while stirring with a magnetic stirrer.
A slurry composed of an aqueous potassium carbonate solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the air.
The heat-treated ammonia decomposition catalyst was pulverized by a ball mill in the same manner as in Example 1, and then the particle size and specific surface area were measured. As a result, the average particle diameter D 50 is a specific surface area be 1.35μm was 1.1 m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 4800 h −1 . As a result, the conversion rate of ammonia was 100%.
実施例4
La:Sr:Ni:Co:Feが原子比で1.0:1.0:1/3:1/3:1/3となるように、即ち酸化ランタン142.17gと炭酸ストロンチウム(Srとして59.76wt%)127.53gと炭酸ニッケル35.99gと塩基性炭酸コバルト28.66gとクエン酸鉄水溶液195.49gを秤量した以外は実施例1と同様にして、複合酸化物300gを得た。
Example 4
La: Sr: Ni: Co: Fe is in an atomic ratio of 1.0: 1.0: 1/3: 1/3: 1/3, that is, 142.17 g of lanthanum oxide and strontium carbonate (59 as Sr .76 wt%) In the same manner as in Example 1 except that weighed 127.53 g, nickel carbonate 35.99 g, basic cobalt carbonate 28.66 g, and iron citrate aqueous solution 195.49 g, composite oxide 300 g was obtained.
その後、実施例1と同様にX線回折スペクトルを測定した。X線回折スペクトルから、この複合酸化物は、図5に示すように、正方晶系層状ペロブスカイト構造のLaSrCo0.50Fe0.50O4と正方晶系層状ペロブスカイト構造のLa2NiO4に帰属できた。X線回折測定の結果と原料の仕込み組成から、この複合酸化物はBサイトにNiとCoとFeが存在する層状ペロブスカイト構造のLaSrNi1/3Co1/3Mn1/3O4であることが判った。 Thereafter, the X-ray diffraction spectrum was measured in the same manner as in Example 1. From the X-ray diffraction spectrum, this complex oxide is attributed to LaSrCo 0.50 Fe 0.50 O 4 having a tetragonal layered perovskite structure and La 2 NiO 4 having a tetragonal layered perovskite structure, as shown in FIG. did it. From the results of X-ray diffraction measurement and the raw material composition, this composite oxide is LaSrNi 1/3 Co 1/3 Mn 1/3 O 4 having a layered perovskite structure in which Ni, Co, and Fe are present at the B site. I understood.
次に、炭酸カリウム1.33gをイオン交換水40gに溶解させた。この溶液に上記のLaSrNi1/3Co1/3Fe1/3O4を5.0g加え、マグネットスターラーで撹拌しながら約15時間浸漬した。
炭酸カリウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕した後、粒度および比表面積測定した。その結果、平均粒径D50は8.01μmであり比表面積は3.97m2/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なった。なお、反応温度は600℃、空間速度は3600h−1とした。その結果、アンモニアの転化率は97%であった。
Next, 1.33 g of potassium carbonate was dissolved in 40 g of ion-exchanged water. 5.0 g of the above LaSrNi 1/3 Co 1/3 Fe 1/3 O 4 was added to this solution and immersed for about 15 hours while stirring with a magnetic stirrer.
A slurry composed of an aqueous potassium carbonate solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the air.
The heat-treated ammonia decomposition catalyst was pulverized by a ball mill in the same manner as in Example 1, and then the particle size and specific surface area were measured. As a result, the average particle diameter D 50 is a specific surface area be 8.01μm was 3.97m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 3600 h −1 . As a result, the conversion rate of ammonia was 97%.
実施例5
実施例4と同様にしてLaSrNi1/3Co1/3Fe1/3O4を得た。次に、炭酸ナトリウム0.75gをイオン交換水40gに溶解させた溶液を作成した。この溶液に上記のLaSrNi1/3Co1/3Fe1/3O45.0gを加え、マグネットスターラーで攪拌しながら約15時間浸漬した。
炭酸ナトリウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕した後、粒度およびBET比表面積を測定した。その結果、平均粒径D50は5.29μm、比表面積は1.1m2/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なった。なお、反応温度は600℃、空間速度は4800h−1とした。その結果、アンモニアの転化率は100%であった。
Example 5
In the same manner as in Example 4, LaSrNi 1/3 Co 1/3 Fe 1/3 O 4 was obtained. Next, a solution in which 0.75 g of sodium carbonate was dissolved in 40 g of ion-exchanged water was prepared. To this solution, 5.0 g of LaSrNi 1/3 Co 1/3 Fe 1/3 O 4 was added and immersed for about 15 hours while stirring with a magnetic stirrer.
A slurry composed of a sodium carbonate aqueous solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the atmosphere.
The heat-treated ammonia decomposition catalyst was pulverized by a ball mill in the same manner as in Example 1, and then the particle size and BET specific surface area were measured. As a result, the average particle diameter D 50 is 5.29Myuemu, the specific surface area was 1.1 m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 4800 h −1 . As a result, the conversion rate of ammonia was 100%.
比較例1
炭酸カリウムを600℃で6時間熱処理した後に、ボールミルで40時間粉砕した。この粉砕粉について、実施例1と同様にしてBET比表面積を測定した。その結果、比表面積は0.22m2/gであった。また、この粉砕粉について、実施例1と同様にしてアンモニア分解評価を行なった。なお、反応温度は600℃、空間速度は4800h−1とした。その結果、アンモニアの転化率は1%であった。
Comparative Example 1
The potassium carbonate was heat treated at 600 ° C. for 6 hours, and then pulverized with a ball mill for 40 hours. For this pulverized powder, the BET specific surface area was measured in the same manner as in Example 1. As a result, the specific surface area was 0.22 m 2 / g. The pulverized powder was evaluated for ammonia decomposition in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 4800 h −1 . As a result, the conversion rate of ammonia was 1%.
比較例2
実施例1と同様にしてLaNi1/3Co1/3Fe1/3O3を得た。
この複合酸化物を40時間ボールミルで粉砕し、粒度およびBET比表面積を測定した。その結果、平均粒度D50は0.89μm、比表面積は3.8m2/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なった。なお、反応温度は600℃、空間速度は3533h−1とした。その結果、アンモニアの転化率は42%であった。
Comparative Example 2
In the same manner as in Example 1, LaNi 1/3 Co 1/3 Fe 1/3 O 3 was obtained.
This composite oxide was pulverized with a ball mill for 40 hours, and the particle size and BET specific surface area were measured. As a result, the average particle size D 50 is 0.89Myuemu, the specific surface area was 3.8 m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 3533 h −1 . As a result, the conversion rate of ammonia was 42%.
比較例3
実施例4と同様にしてLaSrNi1/3Co1/3Fe1/3O4を得た。
この複合酸化物を40時間ボールミルで粉砕し、粒度およびBET比表面積を測定した。その結果、平均粒度D50は6.1μm、比表面積は0.96m2/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なった。なお、反応温度は600℃、空間速度は6316h−1とした。その結果、アンモニアの転化率は32%であった。
Comparative Example 3
In the same manner as in Example 4, LaSrNi 1/3 Co 1/3 Fe 1/3 O 4 was obtained.
This composite oxide was pulverized with a ball mill for 40 hours, and the particle size and BET specific surface area were measured. As a result, the average particle size D 50 was 6.1 [mu] m, a specific surface area of 0.96 m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C., and the space velocity was 6316 h −1 . As a result, the conversion rate of ammonia was 32%.
比較例4
La:Co:Feが原子比で1.0:0.50:0.50となるように、即ち酸化ランタン200.71gと塩基性炭酸コバルト61.30gとクエン酸鉄水溶液418.17gを秤量した以外は実施例1と同様にして複合酸化物300gを得た。
Comparative Example 4
La: Co: Fe was measured to have an atomic ratio of 1.0: 0.50: 0.50, that is, 20.71 g of lanthanum oxide, 61.30 g of basic cobalt carbonate, and 418.17 g of an aqueous iron citrate solution were weighed. Except for this, 300 g of composite oxide was obtained in the same manner as in Example 1.
その後、実施例1と同様にX線回折スペクトルを測定した。X線回折スペクトルから、この複合酸化物は立方晶系ペロブスカイト構造のLaCo0.40Fe0.60O3と菱面体晶系ペロブスカイト構造のLaCoO3に帰属できた。X線回折測定の結果と原料の仕込み組成から、この複合酸化物はBサイトにCoとFeが存在するペロブスカイト構造のLaCo0.50Fe0.50O3であることが判った。 Thereafter, the X-ray diffraction spectrum was measured in the same manner as in Example 1. From the X-ray diffraction spectrum, this composite oxide could be assigned to LaCo 0.40 Fe 0.60 O 3 having a cubic perovskite structure and LaCoO 3 having a rhombohedral perovskite structure. From the result of X-ray diffraction measurement and the raw material composition, it was found that this composite oxide was LaCo 0.50 Fe 0.50 O 3 having a perovskite structure in which Co and Fe exist at the B site.
次に、炭酸カリウム1.33gをイオン交換水40gに溶解させた。この溶液に上記のLaCo0.50Fe0.50O3を5.0g加え、マグネットスターラーで撹拌しながら約15時間浸漬した。
炭酸カリウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕した後、この複合酸化物の平均粒径D50および比表面積を測定した。その結果、平均粒径D50は3.22μm、比表面積は0.90m2/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なった。なお、反応温度は600℃、空間速度は5167h−1とした。その結果、アンモニアの転化率は65%であった。
Next, 1.33 g of potassium carbonate was dissolved in 40 g of ion-exchanged water. 5.0 g of the above LaCo 0.50 Fe 0.50 O 3 was added to this solution and immersed for about 15 hours while stirring with a magnetic stirrer.
A slurry composed of an aqueous potassium carbonate solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the air.
After grinding in a ball mill to a heat treatment with ammonia decomposition catalyst in the same manner as in Example 1, to measure the average particle diameter D 50 and the specific surface area of the composite oxide. As a result, the average particle diameter D 50 is 3.22Myuemu, the specific surface area was 0.90 m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 5167 h −1 . As a result, the conversion rate of ammonia was 65%.
比較例5
実施例1と同様にしてLaNi1/3Co1/3Fe1/3O3を得た。次に炭酸マグネシウム7.9gをイオン交換40gに溶解させ、この溶液に上記のLaNi1/3Co1/3Fe1/3O3を5.0g加え、マグネットスターラーで撹拌しながら約15時間浸漬した。
炭酸マグネシウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕し、粒度およびBET比表面積を測定した。その結果、平均粒度D50は1.21μm、比表面積は4.08m2/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なった。なお、反応温度は600℃、空間速度は4200h−1とした。その結果、アンモニアの転化率は69%であった。
Comparative Example 5
In the same manner as in Example 1, LaNi 1/3 Co 1/3 Fe 1/3 O 3 was obtained. Next, 7.9 g of magnesium carbonate is dissolved in 40 g of ion exchange, 5.0 g of the above LaNi 1/3 Co 1/3 Fe 1/3 O 3 is added to this solution, and it is immersed for about 15 hours while stirring with a magnetic stirrer. did.
A slurry composed of an aqueous magnesium carbonate solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the air.
The heat-treated ammonia decomposition catalyst was pulverized by a ball mill in the same manner as in Example 1, and the particle size and BET specific surface area were measured. As a result, the average particle size D 50 is 1.21, a specific surface area of 4.08m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 4200 h −1 . As a result, the conversion rate of ammonia was 69%.
比較例6
実施例1と同様にしてLaNi1/3Co1/3Fe1/3O3を得た。次に炭酸カルシウム3.30gをイオン交換40gに溶解させ、この溶液に上記のLaNi1/3Co1/3Fe1/3O3を5.0g加え、マグネットスターラーで撹拌しながら約15時間浸漬した。
炭酸カルシウム水溶液と複合酸化物からなるスラリーを、90℃で6時間蒸発乾固した後に、アルミナ製の匣鉢に移し、大気中、600℃で6時間熱処理した。
熱処理したアンモニア分解触媒を実施例1と同様にしてボールミルで粉砕し、粒度およびBET比表面積を測定した。その結果、平均粒度D50は1.23μm、比表面積は7.07m2/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なった。なお、反応温度は600℃、空間速度は5517h−1とした。その結果、アンモニアの転化率は53%であった。
Comparative Example 6
In the same manner as in Example 1, LaNi 1/3 Co 1/3 Fe 1/3 O 3 was obtained. Next, 3.30 g of calcium carbonate is dissolved in 40 g of ion exchange, 5.0 g of the above LaNi 1/3 Co 1/3 Fe 1/3 O 3 is added to this solution, and immersed for about 15 hours while stirring with a magnetic stirrer. did.
A slurry composed of an aqueous calcium carbonate solution and a composite oxide was evaporated to dryness at 90 ° C. for 6 hours, and then transferred to an alumina sagger and heat-treated at 600 ° C. for 6 hours in the air.
The heat-treated ammonia decomposition catalyst was pulverized by a ball mill in the same manner as in Example 1, and the particle size and BET specific surface area were measured. As a result, the average particle size D 50 is 1.23 [mu] m, a specific surface area of 7.07m 2 / g. Thereafter, ammonia decomposition was evaluated in the same manner as in Example 1. The reaction temperature was 600 ° C. and the space velocity was 5517 h −1 . As a result, the conversion rate of ammonia was 53%.
以上の結果より、BサイトにNiとCoとFeの3元素を有するペロブスカイト構造または層状ペロブスカイト構造の複合酸化物にカリウムなどのアルカリ金属またはその化合物を担持させたアンモニア分解触媒は、それらを担持しないアンモニア分解触媒よりもアンモニア分解性能が飛躍的に向上する触媒を提供することができる。
一方、カリウム化合物のみのアンモニア分解触媒や、ペロブスカイト構造または層状ペロブスカイト構造の複合酸化物のみのアンモニア分解触媒は、高い触媒能は得られなかった。
From the above results, the ammonia decomposition catalyst in which an alkali metal such as potassium or a compound thereof is supported on a composite oxide having a perovskite structure or a layered perovskite structure having three elements of Ni, Co, and Fe at the B site does not support them. It is possible to provide a catalyst whose ammonia decomposition performance is remarkably improved as compared with an ammonia decomposition catalyst.
On the other hand, an ammonia decomposition catalyst composed solely of a potassium compound or an ammonia decomposition catalyst composed solely of a complex oxide having a perovskite structure or a layered perovskite structure did not provide high catalytic ability.
また、BサイトにNi,Co,Feの3元素が含まれている複合酸化物にマグネシウムやカルシウムなどのアルカリ土類金属またはその化合物を担持させてもアンモニア分解性能の向上は図れなかった。
よって、本発明にかかるアンモニア分解触媒は、カリウム金属もしくはナトリウム金属、またはカリウム化合物もしくはナトリウム化合物とLaとNiとCoとFeの4元素を有する複合酸化物との相互作用により高い触媒能が発現する。
Further, even when an alkaline earth metal such as magnesium or calcium or a compound thereof was supported on a composite oxide containing three elements of Ni, Co, and Fe at the B site, the ammonia decomposition performance could not be improved.
Therefore, the ammonia decomposition catalyst according to the present invention exhibits high catalytic ability due to the interaction between potassium metal or sodium metal, or a potassium compound or sodium compound and a composite oxide having four elements of La, Ni, Co, and Fe. .
本発明のアンモニア分解触媒は、有害なアンモニアを水素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 hydrogen 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
Claims (6)
La 1−x Sr x Ni y Co z Fe 1−y−z O 3 (1)
La 2−x Sr x Ni y Co z Fe 1−y−z O 4 (2)
(ただし、式(1)においては、0≦x<1、0<y<1、0<z<1であり、y+z<1を満足し、式(2)においては、0≦x<2、0<y<1、0<z<1であり、y+z<1を満足する。) Sodium metal or potassium metal, or a sodium compound on the surface of a composite oxide represented by the following formula (1) having a perovskite structure or a composite oxide particle of a composite oxide represented by the following formula (2) having a layered perovskite structure Alternatively, an ammonia decomposition catalyst characterized by the presence of a potassium compound.
La 1-x Sr x Ni y Co z Fe 1-y-z O 3 (1)
La 2-x Sr x Ni y Co z Fe 1-y-z O 4 (2)
(However, in Formula (1), 0 ≦ x <1, 0 <y <1, 0 <z <1, and satisfy y + z <1, and in Formula (2), 0 ≦ x <2, (0 <y <1, 0 <z <1, and y + z <1 is satisfied.)
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