JP6286523B2 - How to start the catalytic reactor - Google Patents
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- JP6286523B2 JP6286523B2 JP2016249154A JP2016249154A JP6286523B2 JP 6286523 B2 JP6286523 B2 JP 6286523B2 JP 2016249154 A JP2016249154 A JP 2016249154A JP 2016249154 A JP2016249154 A JP 2016249154A JP 6286523 B2 JP6286523 B2 JP 6286523B2
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- 230000003197 catalytic effect Effects 0.000 title claims description 4
- 239000003054 catalyst Substances 0.000 claims description 106
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 98
- 229910021529 ammonia Inorganic materials 0.000 claims description 49
- 238000007254 oxidation reaction Methods 0.000 claims description 29
- 238000006243 chemical reaction Methods 0.000 claims description 26
- 230000003647 oxidation Effects 0.000 claims description 26
- 229910052751 metal Inorganic materials 0.000 claims description 23
- 239000002184 metal Substances 0.000 claims description 23
- 238000000354 decomposition reaction Methods 0.000 claims description 19
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 18
- 239000001257 hydrogen Substances 0.000 claims description 18
- 229910052739 hydrogen Inorganic materials 0.000 claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 9
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 9
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 6
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 6
- 239000002131 composite material Substances 0.000 claims description 4
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 13
- 238000000034 method Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 229910052697 platinum Inorganic materials 0.000 description 8
- 229910052759 nickel Inorganic materials 0.000 description 5
- 238000011068 loading method Methods 0.000 description 4
- 229910044991 metal oxide Inorganic materials 0.000 description 4
- 150000004706 metal oxides Chemical class 0.000 description 4
- 229910052703 rhodium Inorganic materials 0.000 description 4
- 239000010948 rhodium Substances 0.000 description 4
- 229910052707 ruthenium Inorganic materials 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
- 239000010953 base metal Substances 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 230000036962 time dependent Effects 0.000 description 3
- 229910018967 Pt—Rh Inorganic materials 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000012790 confirmation Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000003870 refractory metal Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
- 229910052726 zirconium Inorganic materials 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
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Description
本発明は、燃料としてアンモニアを用いるアンモニアエンジンの助燃剤や燃料電池などで水素生成反応に供されるアンモニア酸化・分解触媒に関する。本発明は、触媒を充填した触媒反応器を起動させる方法に関する。 The present invention relates to an ammonia oxidation / decomposition catalyst used for a hydrogen generation reaction in an auxiliary fuel for an ammonia engine that uses ammonia as a fuel or a fuel cell. The present invention relates to a method for starting a catalytic reactor filled with a catalyst.
アンモニアを分解して水素を製造するためには、従来、ルテニウム系のアンモニア分解触媒の存在下に下記式（I）の反応を進行させる必要がある。 In order to produce hydrogen by decomposing ammonia, conventionally, the reaction of the following formula (I) needs to proceed in the presence of a ruthenium-based ammonia decomposing catalyst.
ＮＨ３ ⇔ ３／２Ｈ２ ＋ １／２Ｎ２ ・・・（I）
ΔＨ２９８Ｋ＝４６．１ｋＪ／ｍｏｌ
NH 3 ⇔ 3 / 2H 2 + 1 / 2N 2 (I)
ΔH 298K = 46.1kJ / mol
式（I）の反応は、吸熱反応であるため、安定したアンモニア分解率を得るためには反応系に熱を与えて反応温度３５０℃以上にする必要がある。 Since the reaction of formula (I) is an endothermic reaction, in order to obtain a stable ammonia decomposition rate, it is necessary to apply heat to the reaction system so that the reaction temperature is 350 ° C. or higher.
そこで、吸熱反応によるガス温度降下を抑制するために従来は外部から熱を供給していた。しかし、この方法では伝熱速度が反応速度より遅いため十分な伝熱速度を得るには伝熱面積を大きくせざるをえず、装置のコンパクト化が難しい。 Therefore, conventionally, heat is supplied from the outside in order to suppress a gas temperature drop due to an endothermic reaction. However, in this method, since the heat transfer rate is slower than the reaction rate, it is necessary to increase the heat transfer area to obtain a sufficient heat transfer rate, and it is difficult to make the apparatus compact.
外部からの熱供給の熱源としてエンジンなどの排ガスを利用する方法も考えられるが、この方法では熱源の温度が３５０℃以下である場合は触媒が作動する温度より低いため、熱供給を行うことができず、所定量の水素を製造することができないという難点がある。 A method of using exhaust gas from an engine or the like as a heat source for supplying heat from the outside is also conceivable. However, in this method, when the temperature of the heat source is 350 ° C. or lower, the temperature is lower than the temperature at which the catalyst operates, so that heat supply may be performed. There is a drawback that a predetermined amount of hydrogen cannot be produced.
熱供給の熱源としては、外部からの供給以外に下記式（II）に示されるように、アンモニアと酸素との触媒反応により熱を発生させ、この熱を利用する方法がある。 As a heat source for heat supply, there is a method in which heat is generated by a catalytic reaction between ammonia and oxygen as shown in the following formula (II) in addition to supply from the outside, and this heat is used.
ＮＨ３ ＋ ３／４Ｏ２ ⇔ １／２Ｎ２ ＋ ３／２Ｈ２Ｏ ・・・（II）
ΔＨ２９８Ｋ＝−３１５．１ｋＪ／ｍｏｌ
NH 3 + 3/4 O 2 ⇔ 1/2 N 2 + 3/2 H 2 O (II)
ΔH 298K = -315.1kJ / mol
式（I）と式（II）の反応を同一の反応管内で起こさせると式（I）の反応の吸熱分を式（II）の反応で発生する熱で補うことが可能となる。また、式（II）の反応の酸素量を制御することで触媒層温度を制御することができる。例えば、エンジン排ガスの廃熱を熱交換して予熱された供給ガス温度が変動する場合において、安定して水素を製造することが可能となる。 When the reactions of formula (I) and formula (II) are caused in the same reaction tube, the endothermic component of the reaction of formula (I) can be supplemented with the heat generated by the reaction of formula (II). Further, the catalyst layer temperature can be controlled by controlling the amount of oxygen in the reaction of the formula (II). For example, when the supply gas temperature preheated by exchanging waste heat of engine exhaust gas fluctuates, hydrogen can be produced stably.
式（II）の反応を進行させるために用いられるアンモニア酸化用触媒としては、通常、白金系触媒が用いられる。例えば特許文献１には、耐火性金属酸化物、この耐火性金属酸化物上に設けられた白金層、およびこの白金上に設けられたバナジア層を含んでなる多層化アンモニア酸化触媒が提案されている。 As the ammonia oxidation catalyst used to advance the reaction of the formula (II), a platinum-based catalyst is usually used. For example, Patent Document 1 proposes a multilayered ammonia oxidation catalyst comprising a refractory metal oxide, a platinum layer provided on the refractory metal oxide, and a vanadia layer provided on the platinum. Yes.
しかし、この触媒の作動温度は２００℃程度であり、それ以下の温度では酸化反応を進行させることができず、電気ヒータ等でガス温度を２００℃程度まで上げる必要がある。 However, the operating temperature of this catalyst is about 200 ° C., and the oxidation reaction cannot proceed at a temperature lower than that, and it is necessary to raise the gas temperature to about 200 ° C. with an electric heater or the like.
特許文献２には、セリウム及びプラセオジムから選択される少なくとも１種の元素の酸化物と、イットリウムを含む原子価非可変性希土類元素から選択される少なくとも１種の元素の酸化物と、コバルトの酸化物を含むアンモニア酸化触媒が提案され、また特許文献３には、本質的に白金、ロジウム、随時パラジウムからなるフィラメントを含み、該フィラメントが白金コーティングを有するアンモニア酸化触媒が提案されているが、これらも特許文献１と同じ問題を有する。
本願の発明者らは、酸化還元可能な金属酸化物からなる担体に触媒活性金属が担持されてなるアンモニア酸化・分解触媒を開発した。 The inventors of the present application have developed an ammonia oxidation / decomposition catalyst in which a catalytically active metal is supported on a support made of a metal oxide capable of redox.
このアンモニア酸化・分解触媒によると、（i）常温でアンモニアおよび空気をこの触媒と接触させることにより、まず還元状態にある担体が酸素と反応して酸化熱が発生し、瞬時に触媒層温度が上昇し、触媒層温度がアンモニアと酸素とが反応する温度にまで達する；（ii）その後は発熱反応であるアンモニア酸化反応が自立的に進行し、発熱反応により生じた熱が、上述の式（I）に従って触媒活性金属の存在下にアンモニアを分解する過程で使われ、これにより水素が生成する。 According to this ammonia oxidation / decomposition catalyst, (i) by bringing ammonia and air into contact with this catalyst at room temperature, the carrier in the reduced state first reacts with oxygen to generate oxidation heat, and the catalyst layer temperature is instantaneously increased. And the catalyst layer temperature reaches a temperature at which ammonia and oxygen react; (ii) Thereafter, the ammonia oxidation reaction, which is an exothermic reaction, proceeds independently, and the heat generated by the exothermic reaction is expressed by the above formula ( Used in the process of decomposing ammonia in the presence of catalytically active metals according to I), thereby producing hydrogen.
したがって、上記触媒を用いることにより、電気ヒータ等での予備加熱が不要となり、水素の製造コストを削減することができる。 Therefore, by using the above catalyst, preheating with an electric heater or the like is not necessary, and the production cost of hydrogen can be reduced.
上記触媒では、担体を予め還元しておくことにより、常温で還元された状態の担体と酸素が接触した時に担体が酸素と反応して酸化熱が発生し、常温起動性を有することとなる。 In the above catalyst, by reducing the carrier in advance, when the carrier in a reduced state at room temperature comes into contact with oxygen, the carrier reacts with oxygen to generate oxidation heat and has room temperature startability.
担体として単独のＣｅＯ２を用いた場合、常温起動性を有するようにするためには、６００℃以上もの高温で担体を還元する必要があった。 When single CeO 2 was used as the carrier, it was necessary to reduce the carrier at a high temperature of 600 ° C. or higher in order to have room temperature startability.
また、上記触媒は常温起動性を有するものであるが、常温より低い温度では起動性を発現させることができなかった。そこで常温よりもさらに低い温度で起動させることができれば、上記触媒の適用範囲を広くすることができるので便宜である。 Moreover, although the said catalyst has normal temperature starting property, it was not able to express starting property at temperature lower than normal temperature. Therefore, if it can be started at a temperature lower than room temperature, it is convenient because the application range of the catalyst can be widened.
本発明は、上記事情に鑑みてなされたものであり、触媒が常温起動性を有するようにするために必要な担体の還元温度を低減させることができ、かつ、常温よりも低い温度で起動性を持たせることができるような、アンモニア酸化・分解触媒を提供することを目的とする。 The present invention has been made in view of the above circumstances, can reduce the reduction temperature of the support necessary for the catalyst to have room temperature startability, and can be started at a temperature lower than room temperature. An object of the present invention is to provide an ammonia oxidation / decomposition catalyst capable of having
本発明は、触媒が常温起動性を有するようにするために必要な担体の還元温度を低減させることができ、かつ、常温よりも低い温度で起動性を持たせることができるような、触媒反応器を起動させる方法を提供することを目的とする。 The present invention is a catalytic reaction that can reduce the reduction temperature of the support necessary for the catalyst to have room temperature startability and can have startability at a temperature lower than room temperature. It aims at providing the method of starting a vessel.
上記課題を解決するため、本発明は、酸化セリウムと酸化ジルコニウムとの複合酸化物からなる触媒担体に触媒活性金属を担持させてなり、かつ、該触媒担体中の酸化ジルコニウムのモル濃度が１０〜９０％であるアンモニア酸化・分解触媒を、水素気流中若しくはアンモニア気流中、６００℃で加熱処理することにより該触媒担体を構成する酸化セリウムの一部または全部をＣｅＯ２−ｘ（０＜ｘ＜２）に還元させた後に−３０℃から常温にわたる温度域で酸素とアンモニアを同時に該触媒に供給することで該触媒を充填した触媒反応器を起動させる方法である。 In order to solve the above-mentioned problems, the present invention is such that a catalytically active metal is supported on a catalyst carrier made of a composite oxide of cerium oxide and zirconium oxide, and the molar concentration of zirconium oxide in the catalyst carrier is 10 to 10. A 90% ammonia oxidation / decomposition catalyst is heat-treated in a hydrogen stream or an ammonia stream at 600 ° C. so that part or all of the cerium oxide constituting the catalyst carrier is converted to CeO 2-x (0 <x < In this method, after the reduction to 2), oxygen and ammonia are simultaneously supplied to the catalyst in a temperature range from −30 ° C. to room temperature to start the catalyst reactor filled with the catalyst.
本発明のアンモニア酸化・分解触媒は、酸化セリウムと酸化ジルコニウムとの複合酸化物からなる触媒担体に、触媒活性金属として第６Ａ族、第７Ａ族、第８族、および第１Ｂ族からなる群から選ばれる少なくとも１種の金属を担持させたアンモニア酸化・分解触媒であって、前記触媒担体中の酸化ジルコニウムのモル濃度が１０〜９０％であることを特徴とする。
The ammonia oxidation / decomposition catalyst of the present invention is a catalyst carrier composed of a composite oxide of cerium oxide and zirconium oxide, and a group consisting of
好ましくは、上記アンモニア酸化・分解触媒はハニカム形状を有する。 Preferably, the ammonia oxidation / decomposition catalyst has a honeycomb shape.
好ましくは、上記アンモニア酸化・分解触媒はペレットもしくはラッシヒリング状を有する。 Preferably, the ammonia oxidation / decomposition catalyst has a pellet or Raschig ring shape.
本発明のアンモニア酸化・分解触媒に用いられる酸化還元可能な触媒担体は、酸化セリウムと酸化ジルコニウムとの複合酸化物からなるものであり、この触媒担体中の酸化ジルコニウムのモル濃度は１０〜９０％、より好ましくは２０〜７０％である。 The oxidation-reduction catalyst support used in the ammonia oxidation / decomposition catalyst of the present invention is composed of a composite oxide of cerium oxide and zirconium oxide, and the molar concentration of zirconium oxide in the catalyst support is 10 to 90%. More preferably, it is 20 to 70%.
触媒担体に担持される触媒活性金属は、好ましくは、Ｍｏ、Ｃｒ等の第６Ａ族、Ｍｎ等の第７Ａ族、Ｒｕ、Ｐｔ、Ｒｈ、Ｐｄ、Ｃｏ、Ｎｉ、Ｆｅ等の第８族、およびＣｕ、Ａｇ等の第１Ｂ族からなる群から選ばれる少なくとも１種の金属である。
The catalytically active metal supported on the catalyst carrier is preferably a Group 6A such as Mo or Cr, a Group 7A such as Mn, a
本発明によるアンモニア酸化・分解触媒は、水素気流中若しくはアンモニア気流中で２００〜４００℃で加熱処理することにより、以下の反応により触媒担体を構成する金属酸化物の一部または全部が還元される。 The ammonia oxidation / decomposition catalyst according to the present invention is heat-treated at 200 to 400 ° C. in a hydrogen stream or in an ammonia stream, whereby a part or all of the metal oxide constituting the catalyst carrier is reduced by the following reaction. .
ＣｅＯ２＋ｘＨ２→ＣｅＯ２−ｘ＋ｘＨ２Ｏ （０＜ｘ＜２）
ＣｅＯ２＋２ｘ／３ＮＨ３→ＣｅＯ２−ｘ＋ｘＨ２Ｏ＋ｘ／３Ｎ２（０＜ｘ＜２）
CeO 2 + xH 2 → CeO 2−x + xH 2 O (0 <x <2)
CeO 2 + 2x / 3NH 3 → CeO 2-x + xH 2 O + x / 3N 2 (0 <x <2)
上記還元後の触媒がアンモニア酸化・分解反応に供される。アンモニア酸化・分解触媒の還元処理は、同触媒反応器に充填する前に行っても後に行ってもよい。 The catalyst after the reduction is subjected to ammonia oxidation / decomposition reaction. The reduction treatment of the ammonia oxidation / decomposition catalyst may be performed before or after filling the catalyst reactor.
触媒担体が還元された状態にあるアンモニア酸化・分解触媒は、常温若しくはそれ以下の温度である−１５〜−３０℃の温度でアンモニアおよび空気と接触させると、まず、還元状態にある触媒担体が酸素と反応することによって酸化熱が発生し、瞬時に触媒層温度が上昇する。一旦、触媒層温度がアンモニアと酸素が反応する温度（２００℃）まで上昇すると、その後は自立的に上述した式（II）に従ってアンモニア酸化反応が進行する。この式（II）の発熱反応で生じた熱が、上述した式（I）に従って触媒活性金属の存在下にアンモニアを分解する過程で使われ、水素が生成する。 When the ammonia oxidation / decomposition catalyst in a reduced state of the catalyst carrier is brought into contact with ammonia and air at a temperature of 15 to -30 ° C., which is room temperature or lower, first, the catalyst carrier in the reduced state is Oxidation heat is generated by reaction with oxygen, and the catalyst layer temperature rises instantaneously. Once the catalyst layer temperature rises to the temperature at which ammonia and oxygen react (200 ° C.), the ammonia oxidation reaction proceeds autonomously according to the above-described formula (II) thereafter. The heat generated by the exothermic reaction of the formula (II) is used in the process of decomposing ammonia in the presence of the catalytically active metal according to the above-described formula (I) to generate hydrogen.
本発明の触媒反応器の起動方法によれば、触媒が常温起動性を有するようにするために必要な担体の還元温度を低減させることができ、かつ、常温よりも低い温度で起動性を持たせることができる。 According to the catalyst reactor start-up method of the present invention, it is possible to reduce the reduction temperature of the carrier necessary for the catalyst to have room temperature startability, and to have startability at a temperature lower than room temperature. Can be made.
本発明は、触媒活性金属として第６Ａ族、第７Ａ族、第８族、および第１Ｂ族からなる群から選ばれる少なくとも１種の金属を担持させたアンモニア酸化・分解触媒において、酸化セリウムと酸化ジルコニウムとの複合酸化物からなる触媒担体を用い、この触媒担体中の酸化ジルコニウムのモル濃度を１０〜９０％とすることにより、触媒が常温起動性を有するようにするために必要な担体の還元温度を低減させることができ、かつ、常温よりも低い温度で起動性を持たせることができる。
The present invention relates to an ammonia oxidation / decomposition catalyst supporting at least one metal selected from the group consisting of Group 6A, Group 7A,
以下、本発明を具体的に説明するために、本発明の実施例およびこれとの比較を示すための比較例、並びに参考例をいくつか挙げる。 Hereinafter, in order to specifically describe the present invention, examples of the present invention, comparative examples for showing comparison with the examples, and some reference examples will be given.
ａ）触媒担体
触媒担体として、ＺｒＯ２のモル濃度が１０、２０、５０、８０％である４種の市販のＣｅＯ２−ＺｒＯ２（第一稀元素化学工業（株）製）を用いた。
a) Catalyst carrier Four types of commercially available CeO 2 —ZrO 2 (manufactured by Daiichi Rare Element Chemical Co., Ltd.) having a molar concentration of ZrO 2 of 10, 20, 50, and 80% were used as the catalyst carrier.
ｂ）触媒活性金属の担持
上記の触媒担体に触媒活性金属を担持させた。触媒活性金属は、貴金属であるＲｕ、Ｐｔ、Ｒｈ、Ｐｔ−Ｒｈおよび卑金属であるＣｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｍｏ、Ｍｎを用いた。触媒担持量はすべて２重量％となるようにした。
b) Loading of catalytically active metal A catalytically active metal was supported on the above catalyst carrier. As the catalytically active metals, Ru, Pt, Rh, Pt—Rh as noble metals and Co, Ni, Fe, Cu, Mo, and Mn as base metals were used. The catalyst loading was all 2% by weight.
（ペレット形状の触媒の調製）
上記各金属の触媒担体上への担持は、各金属の前駆体である各金属塩を純水に溶解させ、この溶液に、上記の触媒担体を、触媒活性金属の担持量が２重量％（金属として）になるように分散させた。
(Preparation of pellet-shaped catalyst)
Each metal is supported on the catalyst carrier by dissolving each metal salt, which is a precursor of each metal, in pure water, and the catalyst carrier is loaded in this solution with a catalyst active metal loading of 2% by weight ( (As a metal).
この分散液を加熱し、水を緩やかに蒸発させた（蒸発乾固法）。 This dispersion was heated to slowly evaporate water (evaporation to dryness method).
得られた粉末状物を３００℃の空気中で３時間にわたって焼成した。 The obtained powder was fired in air at 300 ° C. for 3 hours.
焼成後の粉末状物を圧縮成型し、１〜０．８５ｍｍに篩い分けして使用に供した。 The fired powder was compression molded and sieved to 1 to 0.85 mm for use.
（ハニカム状触媒の調製）
６００ｃｐｉのコーディエライト上にウォッシュコート法を用いて約２５０ｇ／Ｌの触媒担持量になるまで触媒活性金属を担持させた。
(Preparation of honeycomb catalyst)
A catalytically active metal was supported on 600 cpi cordierite using a wash coat method until a catalyst loading of about 250 g / L was reached.
比較例のための触媒担体として、市販のＣｅＯ２（第一稀元素化学工業（株）製）を用いた。この触媒担体にＲｕ、ＣｏおよびＮｉの各触媒活性金属を担持させた。触媒担持量は、２重量％となるようにした。 As a catalyst carrier for the comparative example, commercially available CeO 2 (manufactured by Daiichi Rare Element Chemical Co., Ltd.) was used. Each catalytically active metal of Ru, Co and Ni was supported on this catalyst carrier. The amount of catalyst supported was 2% by weight.
ｃ）常温起動性試験
（触媒の還元処理）
得られた各ペレット状触媒１ｇまたはハニカム状触媒４ｍＬを流通型反応管に充填した後、水素気流中還元処理温度を１５０℃から８００℃までにわたって５０℃刻みとして処理した。還元処理時間は２時間とした。
c) Room temperature start-up test (catalyst reduction treatment)
After 1 g of each obtained pellet-shaped catalyst or 4 mL of honeycomb-shaped catalyst was filled in a flow-type reaction tube, the reduction treatment temperature in a hydrogen stream was processed from 150 ° C. to 800 ° C. in increments of 50 ° C. The reduction treatment time was 2 hours.
（常温起動性の確認）
上記の反応管に充填された各温度で還元処理された触媒を、窒素雰囲気下、２５℃で保持し、その後、酸素（空気）とアンモニアを同時に触媒層に供給した。アンモニア供給量は２．５ＮＬ／分と一定にし、空気供給量は空気／アンモニアの体積比１．０とした。触媒層温度と出口ガス組成を、それぞれ、熱電対と質量分析計により計測した。
(Confirmation of room temperature activation)
The catalyst reduced at each temperature filled in the reaction tube was kept at 25 ° C. in a nitrogen atmosphere, and then oxygen (air) and ammonia were simultaneously supplied to the catalyst layer. The ammonia supply rate was fixed at 2.5 NL / min, and the air supply rate was set to an air / ammonia volume ratio of 1.0. The catalyst layer temperature and the outlet gas composition were measured with a thermocouple and a mass spectrometer, respectively.
上記の結果、触媒層の温度が上昇すること、水素の生成が認められること、および３０分間以上にわたって安定に水素が生成すること、の３つの要件を満たした触媒を、常温起動性を発現する触媒とし、そのような触媒について還元処理に要した温度を還元温度とした。 As a result, a catalyst satisfying the three requirements of increasing the temperature of the catalyst layer, generating hydrogen and stably generating hydrogen for 30 minutes or more exhibits normal temperature startability. The temperature required for the reduction treatment for such a catalyst was defined as the reduction temperature.
各参考例および比較例の触媒の形状および組成および還元温度を以下の表１に示す。 The shapes and compositions of the catalysts of the respective reference examples and comparative examples and the reduction temperature are shown in Table 1 below.
上記表１から明らかなように、触媒担体がＣｅＯ２であった場合（比較例１〜３）、常温起動性が発現するには還元温度は６００℃以上であることが必要であったのに対して、ＣｅＯ２にＺｒを１０ｍｏｌ％添加した場合（参考例１）には常温起動性を発現させるための還元温度は４００℃であり、比較例１に比べて還元温度を２００℃低減させることができた。 As is clear from Table 1 above, when the catalyst support was CeO 2 (Comparative Examples 1 to 3), the reduction temperature was required to be 600 ° C. or higher in order to develop the room temperature starting property. On the other hand, when 10 mol% of Zr is added to CeO 2 (Reference Example 1), the reduction temperature for exhibiting normal temperature startability is 400 ° C., and the reduction temperature is reduced by 200 ° C. compared to Comparative Example 1. I was able to.
アンモニアの酸化・分解が進行し触媒層温度が６００℃以上であれば反応が停止時にアンモニアを触媒層へ吹き込むだけで発熱反応である担体触媒の酸化反応が進行することにより触媒層温度が上昇し、再び常温起動性を有することが確認された。したがって、より温和な条件で再起動が可能となった。 If the oxidation and decomposition of ammonia progresses and the catalyst layer temperature is 600 ° C. or higher, the catalyst layer temperature rises due to the exothermic reaction of the supported catalyst only by blowing ammonia into the catalyst layer when the reaction stops. Again, it was confirmed that it has room temperature startability. Therefore, it was possible to restart under milder conditions.
上記結果から、Ｚｒの添加は望ましくは２０〜７０ｍｏｌ％であり、貴金属であるＲｕを触媒活性金属として用いた場合には２００℃の還元温度で常温起動性を発現し、卑金属であるＮｉやＣｏを触媒活性金属として用いた場合には、３００℃の還元温度で常温起動性を発現させることができた。 From the above results, Zr is preferably added in an amount of 20 to 70 mol%, and when Ru, which is a noble metal, is used as a catalytically active metal, it exhibits normal temperature startability at a reduction temperature of 200 ° C., and Ni or Co which are base metals. Was used as a catalytically active metal, it was possible to develop room temperature starting properties at a reduction temperature of 300 ° C.
ｄ）低温時の起動性試験
（触媒の還元処理）
得られた各ペレット状触媒１ｇまたはハニカム状触媒４ｍＬを流通型反応管に充填した後、水素気流中６００℃で２時間にわたって還元処理を行った。
d) Start-up test at low temperature (catalyst reduction treatment)
After 1 g of each obtained pellet-shaped catalyst or 4 mL of honeycomb-shaped catalyst was filled in a flow-type reaction tube, reduction treatment was performed for 2 hours at 600 ° C. in a hydrogen stream.
（低温起動性の確認）
上記の反応管に充填された還元処理された触媒を、窒素雰囲気下に冷却し、所定の温度に達した後に、酸素（空気）とアンモニアを同時に供給した。アンモニア供給量は１ＮＬ／分と一定にし、空気供給量は空気／アンモニアの体積比１．０とした。触媒層の温度と触媒層出口における水素発生量を、それぞれ、熱電対と質量分析計により計測した。
(Confirmation of low temperature startability)
The reduced catalyst filled in the reaction tube was cooled in a nitrogen atmosphere, and after reaching a predetermined temperature, oxygen (air) and ammonia were simultaneously supplied. The ammonia supply rate was fixed at 1 NL / min, and the air supply rate was set to an air / ammonia volume ratio of 1.0. The temperature of the catalyst layer and the amount of hydrogen generated at the catalyst layer outlet were measured with a thermocouple and a mass spectrometer, respectively.
各実施例および比較例の触媒の形状および組成および還元温度を以下の表２に示す。 The shapes and compositions of the catalysts and the reduction temperatures of the examples and comparative examples are shown in Table 2 below.
上記の低温時起動性試験を行った時の触媒層温度の経時変化について実施例１７の触媒（Ｒｕ／ＣｅＯ２−ＺｒＯ２（５０ｍｏｌ％））を用いた場合と比較例４の触媒（Ｒｕ（２ｗｔ％）／ＣｅＯ２）を用いた場合とを図１に示す。また、実施例１７の触媒を用いた場合の各気体の濃度の経時変化を図２に示す。 Regarding the time-dependent change in the catalyst layer temperature when the low temperature starting property test was conducted, the catalyst of Example 17 (Ru / CeO2-ZrO 2 (50 mol%)) and the catalyst of Comparative Example 4 (Ru (2 wt) were used. %) / CeO 2 ) is shown in FIG. Further, FIG. 2 shows the change with time of the concentration of each gas when the catalyst of Example 17 is used.
図１から明らかなように、触媒担体がＣｅＯ２である比較例１では、初期触媒層温度が−１５℃では起動性は発現せず、水素は発生しなかった。 As apparent from FIG. 1, the catalyst support in Comparative Example 1 is a CeO 2, the initial temperature of the catalyst layer is -15 ° C. The starting ability do not express, hydrogen was not generated.
これに対して、実施例１５〜３２では、ＣｅＯ２にＺｒＯ２を１０〜９０ｍｏｌ％、望ましくは２０〜７０ｍｏｌ％の割合で添加することにより、室温より低い温度であっても水素の生成が見られ、起動性を発現することが分かった。 On the other hand, in Examples 15 to 32, when ZrO 2 was added to CeO 2 at a ratio of 10 to 90 mol%, desirably 20 to 70 mol%, hydrogen generation was observed even at a temperature lower than room temperature. It has been found that it exhibits startability.
特に、Ｐｔ、Ｒｈ、Ｐｔ−Ｒｈ合金などの貴金属、Ｃｏ、Ｆｅ、Ｎｉ、Ｃｕ、Ｍｏ、Ｍｎ等の卑金属などの種類を問わず、低温時の起動性を発現することができた。 In particular, regardless of the type of noble metals such as Pt, Rh, and Pt—Rh alloys and base metals such as Co, Fe, Ni, Cu, Mo, and Mn, the startability at low temperature could be expressed.
Claims (1)
An ammonia oxidation / decomposition catalyst in which a catalytic active metal is supported on a catalyst carrier made of a composite oxide of cerium oxide and zirconium oxide, and the molar concentration of zirconium oxide in the catalyst carrier is 10 to 90%, A part of or all of cerium oxide constituting the catalyst support is reduced to CeO 2-x (0 <x <2) by heat treatment at 600 ° C. in a hydrogen stream or an ammonia stream, and then in a nitrogen atmosphere. Then, oxygen and ammonia are simultaneously supplied to the catalyst in a temperature range from −30 ° C. to room temperature, whereby the ammonia and oxygen react with each other using the heat of oxidation generated by the reaction between the carrier in the reduced state and oxygen. raising the catalyst layer temperature to a temperature of 200 ° C., it was thereby decomposed ammonia filled with ammonia oxidation and decomposition catalyst for producing hydrogen catalyst How to activate the 応器.
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