JP2009082780A - Catalyst for chemical oxidization of carbon monoxide - Google Patents
Catalyst for chemical oxidization of carbon monoxide Download PDFInfo
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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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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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
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Abstract
Description
本発明は、選択性に優れた一酸化炭素の化学的酸化用触媒に関するものであり、特に、改質ガス中の一酸化炭素ガスの濃度低減に有効な一酸化炭素の化学的酸化用触媒に関する。 The present invention relates to a catalyst for chemical oxidation of carbon monoxide having excellent selectivity, and more particularly to a catalyst for chemical oxidation of carbon monoxide which is effective for reducing the concentration of carbon monoxide gas in reformed gas. .
固体高分子形燃料電池は、作動温度が低いために取り扱いが容易であり、起動時間が速い等、起動性、運転操作性にも優れ、更に、電流密度が高く、小型軽量化が可能であること等から、小容量電源や移動電源として注目されている。 The polymer electrolyte fuel cell is easy to handle due to its low operating temperature, and has excellent startability and operational operability, such as fast start-up time. Furthermore, it has a high current density and can be reduced in size and weight. For this reason, it is attracting attention as a small-capacity power source and a mobile power source.
固体高分子形燃料電池では、アノード触媒としては主として白金触媒が用いられているが、低濃度の一酸化炭素によって被毒されて触媒活性が大きく低下するという欠点がある。
例えば、天然ガス、メタノール、ガソリンなどを改質して得られる水素を燃料とする場合には、改質によって生じた一酸化炭素が、白金に強く吸着して、触媒機能を大きく低下させるという問題がある。
In a polymer electrolyte fuel cell, a platinum catalyst is mainly used as an anode catalyst. However, there is a drawback that the catalytic activity is greatly reduced due to poisoning by a low concentration of carbon monoxide.
For example, when hydrogen obtained by reforming natural gas, methanol, gasoline, etc. is used as fuel, carbon monoxide generated by reforming is strongly adsorbed on platinum, and the catalyst function is greatly reduced. There is.
このため、改質ガス中に含まれる一酸化炭素を酸化除去することが望まれるが、従来知られている一酸化炭素の酸化用触媒を用いる場合には、一酸化炭素の酸化反応と同時に水素の酸化反応も進行するために、エネルギーのロスや望ましくない発熱を生じるという問題点がある。 For this reason, it is desirable to oxidize and remove carbon monoxide contained in the reformed gas. However, when a conventionally known catalyst for oxidizing carbon monoxide is used, hydrogen oxidation is simultaneously performed with the oxidation reaction of carbon monoxide. As the oxidation reaction proceeds, energy loss and undesirable heat generation occur.
また、この様な一酸化炭素による触媒被毒を受けやすい低温型燃料電池の燃料極として、遷移金属又はその合金と、特定の有機金属錯体を組み合わせて用いた耐ＣＯ被毒性を有する燃料極用触媒等が報告されている（例えば、特許文献１等）。しかしながら、化学反応によって一酸化炭素を積極的に酸化除去するために有効な触媒は報告されていない。
本発明は、上記した様な従来技術の現状に鑑みてなされたものであり、その主な目的は、燃料電池用の改質ガス中の一酸化炭素の酸化除去に適した、選択性に優れた一酸化炭素の化学的酸化用触媒を提供することである。 The present invention has been made in view of the current state of the prior art as described above, and its main purpose is excellent in selectivity suitable for the oxidation removal of carbon monoxide in the reformed gas for fuel cells. Another object is to provide a catalyst for chemical oxidation of carbon monoxide.
本発明者は、上記した目的を達成すべく鋭意研究を重ねてきた。その結果、特定の構造を有するロジウムポルフィリン錯体が、一酸化炭素の化学的酸化反応用触媒として優れた活性を有するという従来知られていない特性を見出した。更に、これを導電性担体に担持させる場合やプロトン伝導性樹脂と混合する場合には、触媒活性がより一層向上することを見出し、ここに本発明を完成するに至った。 The present inventor has intensively studied to achieve the above-described object. As a result, it has been found that a rhodium porphyrin complex having a specific structure has a conventionally unknown characteristic that it has an excellent activity as a catalyst for a chemical oxidation reaction of carbon monoxide. Furthermore, when this was supported on a conductive carrier or mixed with a proton conductive resin, it was found that the catalytic activity was further improved, and the present invention was completed here.
即ち、本発明は、下記の一酸化炭素の化学的酸化用触媒、一酸化炭素の化学的酸化方法及び一酸化炭素酸化除去装置を提供するものである。
１． 下記化学式
That is, the present invention provides the following carbon monoxide chemical oxidation catalyst, carbon monoxide chemical oxidation method, and carbon monoxide oxidation removal apparatus.
1. The following chemical formula
（式中、R2,R3,R5,R6,R8,R9,R11及びR12は、同一または異なって、それぞれアルキル基、水素原子又はハロゲン原子を示し、R1,R4,R7及びR10は、同一又は異なって、それぞれ置
換基を有することのあるフェニル基、水素原子又はアルキル基を示す。）で表されるロジウムポルフィリンを有効成分とする一酸化炭素の化学的酸化用触媒。
２． R2,R3,R5,R6,R8,R9,R11及びR12が、同一または異なって、それぞれアルキル基であり、R1,R4,R7及びR10が全て水素原子であるロジウムポルフィリンを有効成分とする請求
項１に記載の一酸化炭素の化学的酸化用触媒。
３． ロジウムポルフィリンが導電性担体に担持されたものである上記項１又は２に記載の一酸化炭素の化学的酸化用触媒。
４． 更に、プロトン導電性樹脂を含むものである上記項１〜３のいずれかに記載の一酸化炭素の化学的酸化用触媒。
５． 一酸化炭素及び酸素を含む混合ガスを上記項１〜４のいずれかの記載の触媒と接触させることを特徴とする、一酸化炭素の化学的酸化方法。
６． 混合ガスが、燃料電池用アノードガスである上記項５に記載の一酸化炭素の化学的酸化方法。
７． 上記項１〜４のいずれかの記載の触媒を充填した反応器を含む、燃料電池用アノードガス中の一酸化炭素酸化の除去装置。
(Wherein R 2 , R 3 , R 5 , R 6 , R 8 , R 9 , R 11 and R 12 are the same or different and each represents an alkyl group, a hydrogen atom or a halogen atom, and R 1 , R 4 , R 7 and R 10 are the same or different and each represents a phenyl group, a hydrogen atom or an alkyl group which may have a substituent. Oxidation catalyst.
2. R 2 , R 3 , R 5 , R 6 , R 8 , R 9 , R 11 and R 12 are the same or different and each is an alkyl group, and R 1 , R 4 , R 7 and R 10 are all hydrogen. The catalyst for chemical oxidation of carbon monoxide according to claim 1, comprising rhodium porphyrin as an active ingredient.
3. Item 3. The catalyst for chemical oxidation of carbon monoxide according to Item 1 or 2, wherein rhodium porphyrin is supported on a conductive carrier.
4). The catalyst for chemical oxidation of carbon monoxide according to any one of Items 1 to 3, further comprising a proton conductive resin.
5). A method for chemically oxidizing carbon monoxide, comprising bringing a mixed gas containing carbon monoxide and oxygen into contact with the catalyst according to any one of the above items 1 to 4.
6). Item 6. The carbon monoxide chemical oxidation method according to Item 5, wherein the mixed gas is an anode gas for a fuel cell.
7). An apparatus for removing carbon monoxide oxidation in an anode gas for a fuel cell, comprising a reactor filled with the catalyst according to any one of Items 1 to 4.
本発明の一酸化炭素の化学的酸化反応用触媒は、下記化学式 The catalyst for chemical oxidation reaction of carbon monoxide of the present invention has the following chemical formula:
（式中、R2,R3,R5,R6,R8,R9,R11及びR12は、同一または異なって、それぞれアルキル基、水素原子又はハロゲン原子を示し、R1,R4,R7及びR10は、同一又は異なって、それぞれ置
換基を有することのあるフェニル基、水素原子又はアルキル基を示す。）
で表されるロジウムポルフィリンを有効成分とするものである
(Wherein R 2 , R 3 , R 5 , R 6 , R 8 , R 9 , R 11 and R 12 are the same or different and each represents an alkyl group, a hydrogen atom or a halogen atom, and R 1 , R 4 , R 7 and R 10 are the same or different and each represents a phenyl group, a hydrogen atom or an alkyl group which may have a substituent.
The rhodium porphyrin represented by
上記化学式において、アルキル基としては、メチル、エチル、イソプロピル、ｎ−プロピル、ｔ−ブチル、ｓｅｃ−ブチル、ｎ−ブチル、イソブチル、ｎ−ペンチルなどの炭素数１〜５程度の直鎖状又は分岐鎖状の低級アルキル基が好ましい。ハロゲン原子としては、フッ素、塩素、臭素などが好ましい。置換基を有することのあるフェニル基としては、フェニル基；パラ-メトキシフェニル基、パラ-メチルフェニル基、2,4,6-トリメチルフェニル基、カルボキシフェニル基、ペンタフルオロフェニル基、フェニルスルホン酸基等の置換基として低級アルコシキ基、低級アルキル基、カルボキシル基、スルホン酸基又はハ
ロゲン原子を有するフェニル基等が好ましい。
In the above chemical formula, the alkyl group is linear or branched having about 1 to 5 carbon atoms such as methyl, ethyl, isopropyl, n-propyl, t-butyl, sec-butyl, n-butyl, isobutyl, n-pentyl and the like. A chain-like lower alkyl group is preferred. As the halogen atom, fluorine, chlorine, bromine and the like are preferable. The phenyl group which may have a substituent is a phenyl group; para-methoxyphenyl group, para-methylphenyl group, 2,4,6-trimethylphenyl group, carboxyphenyl group, pentafluorophenyl group, phenylsulfonic acid group As a substituent such as a lower alkoxy group, a lower alkyl group, a carboxyl group, a sulfonic acid group, or a phenyl group having a halogen atom is preferred.
上記化学式で表されるロジウムポルフィリンの内で、R2,R3,R5,R6,R8,R9,R11及びR12が、同一または異なって、それぞれアルキル基であり、R1,R4,R7及びR10が全て水素原子で
あるロジウムポルフィリンが好ましく、R2,R3,R5,R6,R8,R9,R11及びR12はが全てエチル基であり、R1,R4,R7及びR10が全て水素原子であるロジウムポルフィリンが特に好ましい。
Among the rhodium porphyrins represented by the above chemical formula, R 2 , R 3 , R 5 , R 6 , R 8 , R 9 , R 11 and R 12 are the same or different and each is an alkyl group, and R 1 R 4 , R 4 , R 7 and R 10 are all preferably hydrogen atoms, and R 2 , R 3 , R 5 , R 6 , R 8 , R 9 , R 11 and R 12 are all ethyl groups. Rhodium porphyrin in which R 1 , R 4 , R 7 and R 10 are all hydrogen atoms is particularly preferred.
上記化学式で表されるロジウムポルフィリンは、下記式
ＣＯ＋１／２Ｏ２ → ＣＯ２
で表される一酸化炭素の化学的酸化反応に対する触媒として優れた活性を有するものである。
The rhodium porphyrin represented by the above chemical formula has the following formula:
CO + 1 / 2O 2 → CO 2
It has excellent activity as a catalyst for the chemical oxidation reaction of carbon monoxide represented by
上記したロジウムポルフィリンは、導電性担体に担持させることにより、一酸化炭素の化学的酸化反応に対して、より高い触媒活性を有するものとなる。 The rhodium porphyrin described above has higher catalytic activity for the chemical oxidation reaction of carbon monoxide by being supported on a conductive carrier.
導電性担体としては、特に限定はなく、例えば、従来から固体高分子形燃料電池用の触媒担体として用いられている各種の担体を用いることができる。この様な担体の具体例としては、カーボンブラック、活性炭、黒鉛等の炭素質材料を挙げることができる。これらの内で、カーボンブラックは、上記化学式で表されるロジウムポルフィリンとの相互作用が大きくロジウムポルフィリンを安定化させる働きが強く、更に、導電性に優れ、比表面積も大きいために、導電性担体として特に好ましい物質である。 The conductive carrier is not particularly limited, and for example, various carriers conventionally used as catalyst carriers for polymer electrolyte fuel cells can be used. Specific examples of such a carrier include carbonaceous materials such as carbon black, activated carbon, and graphite. Among these, carbon black has a large interaction with rhodium porphyrin represented by the above chemical formula and has a strong function of stabilizing rhodium porphyrin. Further, it has excellent conductivity and a large specific surface area. As a particularly preferred substance.
導電性担体の形状などについては特に限定はないが、例えば、平均粒径が０．１〜１００μｍ程度、好ましくは１〜１０μｍ程度のものを用いることができる。また、カーボンブラックを用いる場合には、例えば、ＢＥＴ法による比表面積が１００〜８００ｍ２／ｇ程度の範囲内にあるものが好ましく、２００〜３００ｍ２／ｇ程度の範囲内にあるものがより好ましい。この様なカーボンブラックの具体例としては、Vulcan XC-72R（Cabot社製）の商標名で市販されているものを用いることができる。 The shape of the conductive carrier is not particularly limited, and for example, a conductive carrier having an average particle diameter of about 0.1 to 100 μm, preferably about 1 to 10 μm can be used. Further, when carbon black is used, for example, specific surface area by BET method is preferably one in the range of about 100~800m 2 / g, more preferably being within the range of about 200 to 300 m 2 / g . As a specific example of such a carbon black, those commercially available under the trade name Vulcan XC-72R (Cabot) can be used.
導電性担体に担持させる方法としては、例えば、溶解乾燥法、気相法などの公知の方法を適用できる。 As a method for supporting the conductive carrier, for example, a known method such as a dissolution drying method or a gas phase method can be applied.
例えば、溶解乾燥法では、ロジウムポルフィリンを有機溶媒に溶解させ、この溶液に導電性担体を加えて、例えば、数時間撹拌して、該担体にロジウムポルフィリンを吸着させた後、有機溶媒を乾燥させればよい。また、有機溶媒中にロジウムポルフィリンが多量に含まれる場合には、平衡に達するまでロジウムポルフィリンを導電性担体に吸着させた後、濾過することによって、導電性担体に吸着していないロジウムポルフィリンを除去して、該担体と相互作用しているロジウムポルフィリンのみを該担体の表面に残すことができる。 For example, in the dissolution drying method, rhodium porphyrin is dissolved in an organic solvent, and a conductive carrier is added to this solution. For example, the rhodium porphyrin is adsorbed on the carrier by stirring for several hours, and then the organic solvent is dried. Just do it. In addition, when rhodium porphyrin is contained in a large amount in an organic solvent, rhodium porphyrin is adsorbed on a conductive support until equilibrium is reached, and then filtered to remove rhodium porphyrin not adsorbed on the conductive support. Thus, only the rhodium porphyrin interacting with the carrier can be left on the surface of the carrier.
この方法では、有機溶媒としては、ロジウムポルフィリンを溶解できるものであれば、特に限定なく使用できる。例えば、エタノール等の低級アルコールを好適に用いることができる。 In this method, the organic solvent can be used without particular limitation as long as it can dissolve rhodium porphyrin. For example, a lower alcohol such as ethanol can be suitably used.
濾過によって得られた分散物を、さらに有機溶媒を用いて洗浄液が透明になるまで洗浄すれば、導電性担体との相互作用の弱いロジウムポルフィリンを洗い流すことができ、導電性担体に強固に吸着しているロジウムポルフィリンのみを含む高活性な触媒を得ることができる。 If the dispersion obtained by filtration is further washed with an organic solvent until the washing liquid becomes transparent, rhodium porphyrin, which has a weak interaction with the conductive carrier, can be washed away and firmly adsorbed on the conductive carrier. It is possible to obtain a highly active catalyst containing only the rhodium porphyrin.
気相法で担持させる場合には、例えば、プラズマ蒸着法、ＣＶＤ法、加熱蒸着法などを
公知の方法を採用できる。
In the case of carrying by a vapor phase method, for example, a known method such as a plasma vapor deposition method, a CVD method, or a heating vapor deposition method can be adopted.
導電性担体上に担持させるロジウムポルフィリンの量については、特に限定はないが、例えば、導電性担体１ｇに対して、ロジウムポルフィリンを２０μｍｏｌ〜８０μｍｏｌ程度担持させればよく、２０μｍｏｌ〜４０μｍｏｌ程度担持させることが好ましい。 The amount of rhodium porphyrin supported on the conductive carrier is not particularly limited. For example, about 20 μmol to 80 μmol of rhodium porphyrin may be supported on 1 g of the conductive carrier, and about 20 μmol to 40 μmol is supported. Is preferred.
上記したロジウムポルフィリンは、更に、プロトン伝導性樹脂と混合して用いることによって、一酸化炭素の化学的酸化反応に対する触媒活性をより一層向上させることができ、特に、比較的低い反応温度において一酸化炭素の転化率を向上させることができる。 The rhodium porphyrin described above can further improve the catalytic activity for the chemical oxidation reaction of carbon monoxide by using it mixed with a proton conductive resin. The conversion rate of carbon can be improved.
プロトン伝導性樹脂の種類については特に限定的ではなく、例えば、プロトン伝導性基として、スルホン酸基、カルボキシル基等の酸性基を有する各種の高分子化合物を用いることができる。この様なプロトン伝導性樹脂の具体例としては、商標名：Nafionとして市販されているパーフルオロスルホン酸樹脂などを挙げることができる。 The type of the proton conductive resin is not particularly limited. For example, various polymer compounds having an acidic group such as a sulfonic acid group or a carboxyl group as the proton conductive group can be used. Specific examples of such a proton conductive resin include a perfluorosulfonic acid resin marketed under the trade name: Nafion.
上記したロジウムポルフィリンとプロトン伝導性樹脂の混合方法については特に限定的ではなく、例えば、プロトン伝導性樹脂を含む溶液とロジウムポルフィリンを均一に混合した後、溶媒を蒸発させて乾燥することによって、ロジウムポルフィリンとプロトン伝導性樹脂を均一に混合することができる。その他、粉末状のプロトン伝導性樹脂をロジウムプルフィリンと均一に混合してもよい。 The method for mixing the rhodium porphyrin and the proton conductive resin is not particularly limited. For example, the solution containing the proton conductive resin and the rhodium porphyrin are uniformly mixed, and then the solvent is evaporated and dried. Porphyrin and proton conductive resin can be mixed uniformly. In addition, a powdery proton conductive resin may be uniformly mixed with rhodium purphyrin.
プロトン伝導性樹脂の使用量については特に限定的ではないが、例えば、ロジウムポルフィリン１００重量部に対して、１０００〜１５００重量部程度の使用量とすればよい。 The amount of the proton conductive resin used is not particularly limited. For example, the amount used may be about 1000 to 1500 parts by weight with respect to 100 parts by weight of rhodium porphyrin.
また、上記した導電性担体上にロジウムポリフィリンを担持させた触媒をプロトン伝導性樹脂と混合して用いる場合には、特に活性の高い一酸化炭素の化学的酸化用触媒を得ることができる。 In addition, when a catalyst in which rhodium porphyrin is supported on the above-described conductive support is used by mixing with a proton conductive resin, a highly active catalyst for chemical oxidation of carbon monoxide can be obtained.
本発明の触媒は、一酸化炭素の化学的酸化反応に対して高い活性を有するものである。反応方法については特に限定はなく、一酸化炭素と酸素を含む混合ガスを本発明の触媒に接触させることができる方法であればよい。 The catalyst of the present invention has high activity for the chemical oxidation reaction of carbon monoxide. There is no particular limitation on the reaction method, and any method can be used as long as the mixed gas containing carbon monoxide and oxygen can be brought into contact with the catalyst of the present invention.
例えば、反応器に触媒を充填し、一酸化炭素と酸素を含む混合ガスを該反応器内に流通させる方法によって、一酸化炭素の化学的酸化反応を進行させることができる。 For example, the chemical oxidation reaction of carbon monoxide can be advanced by a method in which the reactor is filled with a catalyst and a mixed gas containing carbon monoxide and oxygen is passed through the reactor.
この際、触媒の形状については特に限定はないが、例えば、粉末状、ハニカム状、シート状等として用いることができる。 At this time, the shape of the catalyst is not particularly limited, and for example, it can be used as a powder, a honeycomb, a sheet, or the like.
反応ガス中の酸素濃度については特に限定されず、一酸化炭素を完全に酸化するための必要量以上の酸素が含まれていればよい。例えば、一酸化炭素の1/2〜3倍程度、好ましくは1〜2倍程度のモル濃度の酸素が存在すればよい。 The oxygen concentration in the reaction gas is not particularly limited, as long as it contains more oxygen than necessary for completely oxidizing carbon monoxide. For example, oxygen having a molar concentration of about 1/2 to 3 times, preferably about 1 to 2 times that of carbon monoxide may be present.
反応温度については、特に限定的ではないが、例えば、５０〜１６０℃程度とすることが好ましく、７０〜１４０℃程度とすることがより好ましい。 Although it does not specifically limit about reaction temperature, For example, it is preferable to set it as about 50-160 degreeC, and it is more preferable to set it as about 70-140 degreeC.
触媒の使用量は、混合ガス中の一酸化炭素濃度、反応条件等に応じて適宜設定すればよい。例えば、触媒を充填した反応装置に一酸化炭素と酸素を含む混合ガスを通過させる方法では、反応系に供給される全ガス量の空間速度（ＳＶ）を、5000〜40000ｈｒ-1・ｍｌ
／ｇ・ｃａｔ（触媒１ｇ当たりの空間速度）程度の範囲内とすればよい。
What is necessary is just to set the usage-amount of a catalyst suitably according to the carbon monoxide density | concentration, reaction conditions, etc. in mixed gas. For example, in a method in which a mixed gas containing carbon monoxide and oxygen is passed through a reactor filled with a catalyst, the space velocity (SV) of the total gas amount supplied to the reaction system is set to 5000 to 40000 hr −1 · ml.
/ G · cat (space velocity per gram of catalyst) may be in the range.
本発明の触媒は、特に、一酸化炭素を含有する改質ガス中の一酸化炭素を選択的に酸化除去する方法において、一酸化炭素の化学酸化用触媒として有効に用いることができる。一酸化炭素を含有する改質ガスとしては、天然ガス、メタノール、ガソリンなどを改質して得られる水素及び一酸化炭素を含む燃料電池用燃料ガスを例示できる。この様なガスの具体例としては、H2 : 40-75モル%程度, CO2 : 20-25モル%, CO : 0.5-2モル%程度, H2O : 0-5モル%程度, N2 : 0-5 モル%程度の組成を有する改質ガスを例示できる。 The catalyst of the present invention can be effectively used as a catalyst for chemical oxidation of carbon monoxide, particularly in a method for selectively oxidizing and removing carbon monoxide in a reformed gas containing carbon monoxide. Examples of the reformed gas containing carbon monoxide include fuel gas for fuel cells containing hydrogen and carbon monoxide obtained by reforming natural gas, methanol, gasoline and the like. Specific examples of such gases include H 2 : about 40-75 mol%, CO 2 : 20-25 mol%, CO: about 0.5-2 mol%, H 2 O: about 0-5 mol%, N A reformed gas having a composition of about 2 : 0-5 mol% can be exemplified.
この様な改質ガスについて、一酸化炭素１モルに対して、１／２モル以上の酸素を添加して本発明の触媒と接触させることによって、改質ガス中に含まれる一酸化炭素を選択性よく酸化して、一酸化炭素濃度を低下させることができる。 For such a reformed gas, carbon monoxide contained in the reformed gas is selected by adding 1/2 mol or more of oxygen to 1 mol of carbon monoxide and bringing it into contact with the catalyst of the present invention. The carbon monoxide concentration can be lowered by oxidizing with good properties.
従って、本発明の一酸化炭素の化学的酸化用触媒は、例えば、改質ガスをアノードガスとする固体高分子形燃料電池において、アノードガスに含まれる一酸化炭素を酸化除去するための一酸化炭素酸化除去装置における一酸化炭素酸化用触媒として有効に用いることができる。この様な一酸化炭素酸化除去装置としては、例えば、本発明の触媒を充填した反応管等の反応器を含む装置を用いることができる。 Therefore, the catalyst for chemical oxidation of carbon monoxide according to the present invention is, for example, in a solid polymer fuel cell using a reformed gas as an anode gas for oxidizing and removing carbon monoxide contained in the anode gas. It can be effectively used as a catalyst for oxidizing carbon monoxide in a carbon oxidation removing apparatus. As such a carbon monoxide oxidation removal apparatus, for example, an apparatus including a reactor such as a reaction tube filled with the catalyst of the present invention can be used.
以上の通り、本発明の触媒は、一酸化炭素の化学的酸化用触媒として優れた活性を有するものであり、特に、水素を含む混合ガス中において、一酸化炭素を選択性良く酸化することができる。 As described above, the catalyst of the present invention has an excellent activity as a catalyst for chemical oxidation of carbon monoxide. In particular, it can oxidize carbon monoxide with high selectivity in a mixed gas containing hydrogen. it can.
よって、本発明の触媒を用いることにより、天然ガス、メタノール、ガソリンなどを改質して得られる改質ガス中の一酸化炭素濃度を効率良く低下させることができ、改質ガスを燃料とする固体高分子形燃料電池において、アノード触媒の触媒活性の低下を抑制して長期間安定な性能を発揮させることが可能となる。 Therefore, by using the catalyst of the present invention, the concentration of carbon monoxide in the reformed gas obtained by reforming natural gas, methanol, gasoline or the like can be efficiently reduced, and the reformed gas is used as fuel. In the polymer electrolyte fuel cell, it is possible to suppress a decrease in the catalytic activity of the anode catalyst and exhibit stable performance for a long period of time.
以下、実施例を挙げて本発明を更に詳細に説明する。 Hereinafter, the present invention will be described in more detail with reference to examples.
実施例１
ロジウムポルフィリン担持カーボン触媒の作製
ロジウムオクタエチルポルフィリンをジクロロメタンに0.7 mMの濃度で溶解させた後、このポルフィリン溶液50 mLに、カーボンブラック（比表面積250 ｍ２／ｇ、商標名：Vulcan XC 72R、Cabot社製）を100 mg加えた。ジクロロメタンの揮発を防ぐために、容器を
密閉した後、超音波洗浄器に１分掛けることにより分散性をよくした。
Example 1
Preparation of rhodium porphyrin-supported carbon catalyst Rhodium octaethylporphyrin was dissolved in dichloromethane at a concentration of 0.7 mM, and then dissolved in 50 mL of this porphyrin solution with carbon black (specific surface area 250 m 2 / g, trade names: Vulcan XC 72R, Cabot 100 mg) was added. In order to prevent the volatilization of dichloromethane, the container was sealed, and then dispersibility was improved by placing it in an ultrasonic cleaner for 1 minute.
このカーボンブラックを懸濁させたポルフィリン溶液を、マグネティックスターラーで３時間攪拌したのち、東洋濾紙 (株)のNo.5C定量濾紙を用いて吸引濾過することにより溶媒を取り除いた。濾紙上のカーボンブラックを回収してロジウムオクタエチルポルフィリン担持カーボン触媒を得た。得られた触媒では、ロジウムポルフィリンの担持量は触媒1gに対して34mmol (21.7mg)である。 The porphyrin solution in which carbon black was suspended was stirred with a magnetic stirrer for 3 hours, and then the solvent was removed by suction filtration using No. 5C quantitative filter paper manufactured by Toyo Filter Paper Co., Ltd. The carbon black on the filter paper was recovered to obtain a rhodium octaethylporphyrin-supported carbon catalyst. In the obtained catalyst, the supported amount of rhodium porphyrin is 34 mmol (21.7 mg) with respect to 1 g of the catalyst.
触媒活性の評価
上記した方法で得た触媒について、固定床流通式反応装置を用いて一酸化炭素に対する酸化活性を評価した。
Evaluation of catalyst activity About the catalyst obtained by the above-mentioned method, the oxidation activity with respect to carbon monoxide was evaluated using the fixed bed flow-type reaction apparatus.
まず、上記した触媒を70〜120メッシュにふるい分けしたもの38mgを内径6mmの石英管に充填し、触媒層の両端に石英ウールを充填した。触媒の温度は、触媒に接触させた石英製保護管付き熱電対にて測定し、この温度が目標の温度になるように電気炉を制御した。 First, 38 mg of the above catalyst sieved to 70-120 mesh was filled in a quartz tube having an inner diameter of 6 mm, and quartz wool was filled at both ends of the catalyst layer. The temperature of the catalyst was measured with a thermocouple with a quartz protective tube brought into contact with the catalyst, and the electric furnace was controlled so that this temperature became the target temperature.
反応ガスとしては、CO １vol.％、O2 １vol.％、 H2O ２vol.％、 Ar ５vol.％
、及びH2 ９１vol.％を含むガスを用いた。
The reaction gases, CO 1vol.%, O 2 1vol.%, H 2 O 2vol.%, Ar 5vol.%
, And were used H 2 91vol.% Gas containing.
上記した触媒を充填した反応管中に、１２０℃、１４０℃及び１６０℃の反応温度で上記反応ガスを10mL/分の流量で流通させて、反応管の出口ガスの濃度を分析した。この場
合の空間速度は約１６０００である。また、反応温度１４０℃の場合については、更に、反応ガスの流量を20mL/分として同様の分析を行った。出口ガスの濃度は、メタン変換器
付きFID-GCとTCD-GCにより分析した。結果を下記表１に示す。
The reaction gas was circulated at a flow rate of 10 mL / min at reaction temperatures of 120 ° C., 140 ° C., and 160 ° C. in the reaction tube filled with the catalyst, and the concentration of the outlet gas of the reaction tube was analyzed. The space velocity in this case is about 16000. Further, in the case of a reaction temperature of 140 ° C., the same analysis was further performed with the reaction gas flow rate set to 20 mL / min. The concentration of the outlet gas was analyzed by FID-GC with methane converter and TCD-GC. The results are shown in Table 1 below.
以上の結果から明らかなように、本発明の触媒を用いることによって、高い選択率で一酸化炭素を酸化できることが判る。 As is apparent from the above results, it can be seen that carbon monoxide can be oxidized with high selectivity by using the catalyst of the present invention.
尚、表中の選択率は、CO＋１／２O2 → CO2の反応式に基づいて、１／２×（平均生
成CO2濃度）／（酸素消費量）より算出した値である。
The selectivity in the table is a value calculated from 1/2 × (average generated CO 2 concentration) / (oxygen consumption) based on the reaction formula of CO + 1 / 2O 2 → CO 2 .
実施例２
実施例１で作製したロジウムオクタエチルポルフィリン担持カーボン触媒40mgに対して、プロトン伝導性樹脂であるパーフルオロスルホン酸樹脂の5重量%溶液（商標名：Nafion、Aldrich社製）280mL加えて、十分に混合した後、70℃で乾燥させて、プロトン伝導性樹脂を含むロジウムオクタエチルポルフィリン担持カーボン触媒を作製した。得られた触媒は、ロジウムオクタエチルポルフィリン1μmolに対して9mgのパーフルオロスルホン酸樹
脂を加えたものであり、ロジウムオクタエチルポルフィリン1gに対して、約14gのパーフ
ルオロスルホン酸樹脂を含むものである。
Example 2
To 40 mg of the rhodium octaethylporphyrin-supported carbon catalyst prepared in Example 1, 280 mL of a 5 wt% solution (trade name: Nafion, manufactured by Aldrich) of a perfluorosulfonic acid resin that is a proton conductive resin was sufficiently added. After mixing, drying at 70 ° C. produced a rhodium octaethylporphyrin-supported carbon catalyst containing a proton conductive resin. The obtained catalyst was obtained by adding 9 mg of perfluorosulfonic acid resin to 1 μmol of rhodium octaethylporphyrin, and containing about 14 g of perfluorosulfonic acid resin per 1 g of rhodium octaethylporphyrin.
上記方法で得られた触媒50mgを実施例１で用いた反応管と同様の反応管に充填し、８０〜１６０℃の範囲の反応温度で、実施例１と同様の方法で反応管の出口ガスの濃度分析を行った。結果を下記表２に示す。 50 mg of the catalyst obtained by the above method was filled in the same reaction tube as that used in Example 1, and the reaction tube outlet gas was reacted in the same manner as in Example 1 at a reaction temperature in the range of 80 to 160 ° C. Concentration analysis was performed. The results are shown in Table 2 below.
以上の結果から明らかなように、反応温度１２０℃及び１４０℃では、実施例１の触媒を用いた場合と比較して、COの転化率の上昇が認められる。 As is clear from the above results, at the reaction temperatures of 120 ° C. and 140 ° C., an increase in the conversion rate of CO is recognized as compared with the case of using the catalyst of Example 1.
尚、１２０〜１６０℃の反応温度では、選択率が低下しているが、これは、水素の酸化反応が進行しているのではなく、水蒸気の存在によって、下記反応が進行していることによるものと思われる。 In addition, at the reaction temperature of 120 to 160 ° C., the selectivity is decreased, but this is not because the oxidation reaction of hydrogen proceeds but the following reaction proceeds due to the presence of water vapor. It seems to be.
CO＋O2 ＋H2O → CO2＋H2O2。 CO + O 2 + H 2 O → CO 2 + H 2 O 2.
Claims (7)
換基を有することのあるフェニル基、水素原子又はアルキル基を示す。）で表されるロジウムポルフィリンを有効成分とする一酸化炭素の化学的酸化用触媒。 The following chemical formula
記載の一酸化炭素の化学的酸化用触媒。 R 2 , R 3 , R 5 , R 6 , R 8 , R 9 , R 11 and R 12 are the same or different and each is an alkyl group, and R 1 , R 4 , R 7 and R 10 are all hydrogen. The catalyst for chemical oxidation of carbon monoxide according to claim 1, comprising rhodium porphyrin as an active ingredient.
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| JP2010214313A (en) * | 2009-03-18 | 2010-09-30 | National Institute Of Advanced Industrial Science & Technology | Catalyst for chemical oxidation of carbon monoxide |
| WO2012165459A1 (en) * | 2011-06-02 | 2012-12-06 | 独立行政法人産業技術総合研究所 | Method and device for removing carbon monoxide |
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| JP2006261086A (en) * | 2005-02-21 | 2006-09-28 | National Institute Of Advanced Industrial & Technology | Catalyst for electrochemical oxidation of carbon monoxide |
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| JP2010214313A (en) * | 2009-03-18 | 2010-09-30 | National Institute Of Advanced Industrial Science & Technology | Catalyst for chemical oxidation of carbon monoxide |
| WO2012165459A1 (en) * | 2011-06-02 | 2012-12-06 | 独立行政法人産業技術総合研究所 | Method and device for removing carbon monoxide |
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