JP3279185B2 - Water splitting method - Google Patents
Water splitting methodInfo
- Publication number
- JP3279185B2 JP3279185B2 JP17933196A JP17933196A JP3279185B2 JP 3279185 B2 JP3279185 B2 JP 3279185B2 JP 17933196 A JP17933196 A JP 17933196A JP 17933196 A JP17933196 A JP 17933196A JP 3279185 B2 JP3279185 B2 JP 3279185B2
- Authority
- JP
- Japan
- Prior art keywords
- reaction
- activated carbon
- carbon
- water
- methane
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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- Catalysts (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水を分解する方法
に関する。詳細には、本発明は、触媒として活性炭を用
い、化学反応により水を分解する方法に関する。[0001] The present invention relates to a method for decomposing water. In particular, the present invention relates to a method for decomposing water by a chemical reaction using activated carbon as a catalyst.
【０００２】[0002]
【従来の技術】近年、大気中の微量ガス、特に二酸化炭
素による地球の温暖化が環境問題として注目されてい
る。すなわち、大気中の二酸化炭素の濃度の増加によっ
て地表から放出される赤外線が吸収され、地表へ戻る赤
外線の量が増加し、その結果、地表の温度が高まる。現
在エネルギー源として最も多く用いられている化石燃料
は燃焼することにより必然的に二酸化炭素を発生する。
そこで二酸化炭素の発生を抑制するためのクリーンな代
替エネルギーが各種提案されている。中でも水素エネル
ギーは本質的に炭素を含まないため二酸化炭素を発生す
ることなく、またエネルギー変換後水に戻り、再生可能
なクリーンエネルギーとして注目されている。2. Description of the Related Art In recent years, global warming due to trace gases in the atmosphere, particularly carbon dioxide, has been attracting attention as an environmental problem. That is, an increase in the concentration of carbon dioxide in the atmosphere absorbs infrared radiation emitted from the surface of the earth, and increases the amount of infrared light returning to the surface of the earth, thereby increasing the temperature of the surface of the earth. At present, fossil fuels, which are most frequently used as energy sources, inevitably emit carbon dioxide by burning.
Therefore, various clean alternative energy for suppressing the generation of carbon dioxide has been proposed. Above all, hydrogen energy has been attracting attention as a renewable clean energy without generating carbon dioxide since it does not essentially contain carbon and returning to water after energy conversion.
【０００３】現在、水素はその99％が化石燃料を原材料
として製造されている。例えば、ナフサからの水蒸気改
質法及び石炭の水性ガス化反応により製造されている。
しかしながら、これらの方法は化石燃料を原材料として
いるため二酸化炭素が発生し、また必要電力が大きく、
さらに化石燃料の枯渇の問題がある。このような化石燃
料を用いず、水を電気化学的に分解することによる水素
の製造方法が工業的に確立しつつある。しかしながら、
この方法も必要電力が大きく、コスト等の点において問
題があり、電力消費の低減が課題となっている。At present, 99% of hydrogen is produced using fossil fuel as a raw material. For example, it is produced by a steam reforming method from naphtha and a water gasification reaction of coal.
However, these methods use fossil fuels as raw materials, generate carbon dioxide, and require large amounts of power,
There is also the problem of fossil fuel depletion. A method for producing hydrogen by electrochemically decomposing water without using such fossil fuels is being established industrially. However,
This method also requires a large amount of power, has problems in terms of cost and the like, and has a problem of reducing power consumption.
【０００４】このような問題を解決するため、水を化学
的に多段階で分解する方法が各種提案されている。例え
ば、特開昭55−21587 号公報は、水とハロゲンとを反応
させハロゲン化水素を形成し、次いでこの得られたハロ
ゲン化水素を電気分解して水素を形成する方法を開示し
ている。この方法によれば、フッ素以外のハロゲン、す
なわち塩素、臭素及び沃素を用いれば、水を直接電気分
解するよりもはるかに低い電圧で水素が得られ、必要な
電気エネルギーを低減できるという利点がある。[0004] In order to solve such a problem, various methods for chemically decomposing water in multiple stages have been proposed. For example, Japanese Patent Application Laid-Open No. 55-21587 discloses a method of reacting water with a halogen to form hydrogen halide, and then electrolyzing the obtained hydrogen halide to form hydrogen. According to this method, when a halogen other than fluorine, that is, chlorine, bromine, and iodine is used, hydrogen is obtained at a much lower voltage than when water is directly electrolyzed, and there is an advantage that necessary electric energy can be reduced. .
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、上記の
方法では、ハロゲンを炭素粒子及び水と反応させている
ため、副生成物として二酸化炭素が発生し、炭素が消費
されるためエネルギー効率が低いという問題がある。ま
た、この方法は反応効率が必ずしも十分ではないという
問題もあった。However, in the above method, since halogen is reacted with carbon particles and water, carbon dioxide is generated as a by-product and carbon is consumed, so that energy efficiency is low. There's a problem. Also, this method has a problem that the reaction efficiency is not always sufficient.
【０００６】[0006]
【課題を解決するための手段】上記問題点を解決するた
めに１番目の発明によれば、水とハロゲンとを反応させ
て水を分解する方法において、触媒として活性炭が用い
られ、かつ反応系に炭化水素ガスが供給されている。ま
た、２番目の発明では上記問題点を解決するために１番
目の発明において、炭化水素ガスが活性炭に向けてバブ
リングされている。According to a first aspect of the present invention, there is provided a method for decomposing water by reacting water with a halogen, wherein activated carbon is used as a catalyst, and Is supplied with a hydrocarbon gas. In the second invention, in order to solve the above problem, in the first invention, the hydrocarbon gas is bubbled toward the activated carbon.
【０００７】[0007]
【発明の実施の形態】本発明は下式 Ｈ2 Ｏ ＋ Ｘ2 → ＨＸ ＋ ＨＸＯ (1) （上式中、Ｘはハロゲンである）で表されるように、触
媒として活性炭を用い、水とハロゲンを反応させ、電気
分解によらず化学反応により水を分解させるものであ
る。この反応により形成されたハロゲン化水素ＨＸから
電気分解により水素を得ることができ、水を電気分解す
るよりもはるかに低いエネルギーで水素を得ることがで
きる。前記特開昭55−21587 号公報に記載の方法も上記
と同様な反応式に基づいている。しかしながら、この従
来の方法においては炭素粒子を反応系に加えており、こ
の炭素が次亜ハロゲン酸ＨＸＯと反応し、二酸化炭素が
発生していた。この二酸化炭素の発生メカニズムは明ら
かではないが、以下の様であると考えられる。BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses activated carbon as a catalyst and water, as represented by the following formula: H 2 O + X 2 → HX + HXO (1) (where X is a halogen). And a halogen, and decompose water by a chemical reaction instead of electrolysis. Hydrogen can be obtained by electrolysis from hydrogen halide HX formed by this reaction, and hydrogen can be obtained with much lower energy than electrolysis of water. The method described in JP-A-55-21587 is also based on the same reaction formula as described above. However, in this conventional method, carbon particles were added to the reaction system, and this carbon reacted with hypohalous acid HXO to generate carbon dioxide. Although the mechanism of generating carbon dioxide is not clear, it is considered as follows.
【０００８】上記反応において生成する次亜ハロゲン酸
ＨＸＯは強力な酸化剤であり、下式(2) に示すように炭
素を酸化する。 ２ＨＸＯ ＋ Ｃ → ２ＨＸ ＋ ＣＯ2 (2) また、上記式(1) において生成する次亜ハロゲン酸ＨＸ
Ｏは下式(3) ２ＨＸＯ → ２ＨＸ ＋ Ｏ2 (3) で表されるように酸素を分離するが、この分離された酸
素が炭素に吸着し、フリーラジカル化して炭素と反応
し、炭素が酸化されてしまう。The hypohalous acid HXO generated in the above reaction is a strong oxidizing agent, and oxidizes carbon as shown in the following formula (2). 2HXO + C → 2HX + CO 2 (2) Further, the hypohalous acid HX formed in the above formula (1)
O separates oxygen as represented by the following formula (3): 2HXO → 2HX + O 2 (3), and the separated oxygen is adsorbed on carbon, becomes free radical, reacts with carbon, and becomes carbon. It will be oxidized.
【０００９】このように上記反応系(1) に炭素を用いる
と、反応過程においてこの炭素が消費されるため、反応
系全体としてエネルギー効率が低くなり好ましくない。
また、この反応自体も反応効率が十分ではない。本発明
では、触媒として活性炭を用いることを特徴としてお
り、この活性炭は炭素粒子に比して次亜ハロゲン酸によ
り酸化されにくく、かつ式(3) の反応を促進し、次亜ハ
ロゲン酸をすばやくハロゲン化水素と酸素に分解する。
そのため、炭素を用いた場合のような二酸化炭素の発生
が抑制され、上記式(1) における水とハロゲンとの反応
の効率を高め、効率よくハロゲン化水素と酸素を生成す
ることができると推定される。As described above, when carbon is used in the reaction system (1), this carbon is consumed in the reaction process, so that the energy efficiency of the reaction system as a whole is low, which is not preferable.
In addition, the reaction itself is not sufficient in reaction efficiency. The present invention is characterized in that activated carbon is used as a catalyst, and this activated carbon is less susceptible to oxidation by hypohalous acid than carbon particles, and promotes the reaction of the formula (3) to quickly reduce hypohalous acid. Decomposes into hydrogen halide and oxygen.
Therefore, it is estimated that the generation of carbon dioxide as in the case of using carbon is suppressed, the efficiency of the reaction between water and halogen in the above formula (1) can be increased, and hydrogen halide and oxygen can be efficiently generated. Is done.
【００１０】この活性炭は、木炭、ヤシがら、石炭チャ
ー等の原料を十分に炭化させた後、水蒸気による高温処
理もしくは塩化亜鉛などの水溶液の含浸と高温焼成など
の方法で賦活化することにより製造され、その表面にカ
ルボキシル基、ヒドロキシル基等の各種の官能基を有し
ている。本発明においては、各種の活性炭を使用するこ
とができるが、特に塩基性表面官能基を有する活性炭が
好ましい。また、ハロゲンとしては、フッ素、塩素、臭
素、沃素のいずれも用いることができるが、反応の制御
及び反応速度の点から塩素及び臭素を用いることが好ま
しい。[0010] This activated carbon is produced by sufficiently carbonizing a raw material such as charcoal, coconut charcoal or coal char, and then activating it by a method such as high-temperature treatment with steam or impregnation with an aqueous solution such as zinc chloride and high-temperature calcination. The surface has various functional groups such as a carboxyl group and a hydroxyl group. In the present invention, various types of activated carbon can be used, but activated carbon having a basic surface functional group is particularly preferred. As the halogen, any of fluorine, chlorine, bromine and iodine can be used, but chlorine and bromine are preferably used from the viewpoint of control of the reaction and the reaction rate.
【００１１】活性炭は炭素よりは酸化されにくいとはい
え徐々には酸化され、活性が低下する。そこで、本発明
では反応系に炭化水素ガスを供給することにより、活性
炭の酸化を抑制している。すなわち、炭化水素ガスは活
性炭よりも酸化されやすく、次亜ハロゲン酸は活性炭と
反応する前にこの供給された炭化水素ガスと反応するこ
とにより、活性炭の酸化が抑制される。炭化水素として
メタンを使用した場合、このメタンと次亜ハロゲン酸と
の反応により、下式 ２ＨＸＯ ＋ ＣＨ4 → ２ＨＸ ＋ ＣＯ2 ＋ ２Ｈ2 (4) で表されるように、ＣＯ2 とＨ2 が発生する。Although activated carbon is less oxidizable than carbon, it is gradually oxidized and its activity is reduced. Therefore, in the present invention, the oxidation of activated carbon is suppressed by supplying a hydrocarbon gas to the reaction system. That is, the hydrocarbon gas is more easily oxidized than the activated carbon, and the hypohalous acid reacts with the supplied hydrocarbon gas before reacting with the activated carbon, thereby suppressing the oxidation of the activated carbon. When methane is used as the hydrocarbon, the reaction between the methane and hypohalous acid causes CO 2 and H 2 to be expressed by the following formula: 2HXO + CH 4 → 2HX + CO 2 + 2H 2 (4) Occurs.
【００１２】この炭化水素ガスは反応条件において気体
であればよく、例えば、メタン、エタン、プロパン、ブ
タン、ペンタン等の飽和炭化水素ガス、及びエテン、プ
ロペン、ブテン、ペンテン等の不飽和炭化水素ガスを使
用することができる。The hydrocarbon gas may be any gas under the reaction conditions, for example, a saturated hydrocarbon gas such as methane, ethane, propane, butane and pentane, and an unsaturated hydrocarbon gas such as ethene, propene, butene and pentene. Can be used.
【００１３】上記(1) の反応は、触媒である活性炭上で
おこるため、炭化水素ガスを活性炭に向けてバブリング
することが好ましい。活性炭に向けて炭化水素ガスをバ
ブリングすることにより上記(2) の活性炭の酸化反応を
より効率的に抑制することができる。Since the reaction (1) takes place on activated carbon as a catalyst, it is preferable to bubble hydrocarbon gas toward activated carbon. By bubbling the hydrocarbon gas toward the activated carbon, the oxidation reaction of the activated carbon (2) can be more efficiently suppressed.
【００１４】[0014]
【実施例】図１に示すように、テフロンコートしたＳＵ
Ｓ製の反応容器１に臭素16g 、水84g 、及び活性炭0.5g
を入れた。この反応容器を密閉した後、容器内を真空に
し、炭化水素導入管２からメタンを導入し、反応混合物
にメタンを10ml/minの速度でバブリングした。140 ℃に
おいて１時間反応させた後（メタン供給量600ml)、反応
容器内の気体を採取し、その組成を調べた。また、比較
としてメタンを導入せずに同様にして反応を行い、気体
の組成を調べた。この結果を以下の表１に示す。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
In a reaction vessel 1 made of S, 16 g of bromine, 84 g of water, and 0.5 g of activated carbon
Was put. After sealing the reaction vessel, the inside of the vessel was evacuated, methane was introduced from the hydrocarbon introduction pipe 2, and methane was bubbled through the reaction mixture at a rate of 10 ml / min. After reacting at 140 ° C. for 1 hour (600 ml of methane supply), the gas in the reaction vessel was sampled and its composition was examined. For comparison, the same reaction was carried out without introducing methane, and the gas composition was examined. The results are shown in Table 1 below.
【００１５】[0015]
【表１】 [Table 1]
【００１６】メタンを供給しない場合、活性炭は下式 ＨＢｒＯ ＋ 1/2 Ｃ → ＨＢｒ ＋ 1/2 ＣＯ2 で表されるように次亜臭素酸により酸化され、380ml の
二酸化炭素を発生している。一方、メタンを600ml 供給
して反応させた後に系内には400ml のメタンが存在して
いたことから、この反応において200ml のメタンが消費
されたことがわかる。このメタンは上記(4) の反応か
ら、次亜臭素酸ＨＢｒＯと反応し200ml のＣＯ2 を形成
したものと考えられる。従って、活性炭の酸化により発
生した二酸化炭素の量は400ml −200ml より200ml と考
えられ、200/380 より、活性炭の劣化は約半分に低減す
ることができたと考えられる。また、メタンを供給する
ことによりＨＢｒ発生量も高めることができた。When methane is not supplied, the activated carbon is oxidized by hypobromous acid as represented by the following formula: HBrO + 1 / 2C → HBr + 1 / 2CO 2 to generate 380 ml of carbon dioxide. . On the other hand, 400 ml of methane was present in the system after 600 ml of methane was supplied and reacted, indicating that 200 ml of methane was consumed in this reaction. This methane is considered to have reacted with HBrO hypobromite to form 200 ml of CO 2 from the above reaction (4). Therefore, the amount of carbon dioxide generated by the oxidation of activated carbon is considered to be 200 ml from 400 ml-200 ml, and it is considered that the deterioration of activated carbon could be reduced to about half from 200/380. Also, by supplying methane, the amount of generated HBr could be increased.
【００１７】[0017]
【発明の効果】触媒として活性炭を用い、水とハロゲン
を反応させる方法において、炭化水素ガスを反応系に供
給することにより、この供給された炭化水素ガスは活性
炭に優先して水とハロゲンとの反応により形成された次
亜ハロゲン酸と反応し、二酸化炭素と水素に分解され
る。このため活性炭の酸化が抑制され、活性炭の触媒機
能を維持することができる。According to the method of reacting water and halogen using activated carbon as a catalyst, a hydrocarbon gas is supplied to the reaction system so that the supplied hydrocarbon gas can be converted into water and halogen in preference to activated carbon. It reacts with hypohalous acid formed by the reaction and is decomposed into carbon dioxide and hydrogen. Therefore, oxidation of the activated carbon is suppressed, and the catalytic function of the activated carbon can be maintained.
【図１】本発明の方法の実施に用いる反応装置の略図で
ある。FIG. 1 is a schematic diagram of a reaction apparatus used to carry out the method of the present invention.
１…反応容器 ２…炭化水素導入管 1 ... reaction vessel 2 ... hydrocarbon introduction pipe
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) C01B 3/04 B01J 21/18 ──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. 7 , DB name) C01B 3/04 B01J 21/18
Claims (2)
る方法であって、触媒として活性炭を用い、かつ反応系
に炭化水素ガスを供給することを特徴とする方法。1. A method for decomposing water by reacting water and a halogen, wherein activated carbon is used as a catalyst and a hydrocarbon gas is supplied to the reaction system.
グすることを特徴とする、請求項１記載の方法。2. The method according to claim 1, wherein the hydrocarbon gas is bubbled toward the activated carbon.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17933196A JP3279185B2 (en) | 1996-07-09 | 1996-07-09 | Water splitting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17933196A JP3279185B2 (en) | 1996-07-09 | 1996-07-09 | Water splitting method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1025101A JPH1025101A (en) | 1998-01-27 |
| JP3279185B2 true JP3279185B2 (en) | 2002-04-30 |
Family
ID=16063977
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17933196A Expired - Fee Related JP3279185B2 (en) | 1996-07-09 | 1996-07-09 | Water splitting method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3279185B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7189382B2 (en) | 2002-09-26 | 2007-03-13 | Honda Motor Co., Ltd. | Methods for the production of hydrogen |
-
1996
- 1996-07-09 JP JP17933196A patent/JP3279185B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1025101A (en) | 1998-01-27 |
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