JP2009125609A - Catalyst for electrochemical oxidation of oxalates - Google Patents
Catalyst for electrochemical oxidation of oxalates Download PDFInfo
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- JP2009125609A JP2009125609A JP2007299954A JP2007299954A JP2009125609A JP 2009125609 A JP2009125609 A JP 2009125609A JP 2007299954 A JP2007299954 A JP 2007299954A JP 2007299954 A JP2007299954 A JP 2007299954A JP 2009125609 A JP2009125609 A JP 2009125609A
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- oxalic acid
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- electrochemical oxidation
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- 239000003054 catalyst Substances 0.000 title claims abstract description 107
- 238000006056 electrooxidation reaction Methods 0.000 title claims abstract description 30
- 150000003891 oxalate salts Chemical class 0.000 title abstract description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 309
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 113
- 239000010948 rhodium Substances 0.000 claims abstract description 62
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 61
- 239000000446 fuel Substances 0.000 claims abstract description 34
- -1 rhodium phthalocyanine compound Chemical class 0.000 claims abstract description 28
- 239000000126 substance Substances 0.000 claims abstract description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 27
- 238000006243 chemical reaction Methods 0.000 claims description 26
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 24
- 230000003647 oxidation Effects 0.000 claims description 17
- 238000007254 oxidation reaction Methods 0.000 claims description 17
- 239000005518 polymer electrolyte Substances 0.000 claims description 13
- 239000006229 carbon black Substances 0.000 claims description 11
- 150000002913 oxalic acids Chemical class 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 10
- 125000003545 alkoxy group Chemical group 0.000 claims description 6
- 125000000217 alkyl group Chemical group 0.000 claims description 6
- 125000005843 halogen group Chemical group 0.000 claims description 5
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 5
- 125000003118 aryl group Chemical group 0.000 claims description 4
- 150000001721 carbon Chemical group 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 4
- 230000001590 oxidative effect Effects 0.000 claims description 4
- 125000001424 substituent group Chemical group 0.000 claims description 4
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- 150000003839 salts Chemical class 0.000 abstract description 6
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- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 34
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- 238000000034 method Methods 0.000 description 24
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- IEQIEDJGQAUEQZ-UHFFFAOYSA-N phthalocyanine Chemical compound N1C(N=C2C3=CC=CC=C3C(N=C3C4=CC=CC=C4C(=N4)N3)=N2)=C(C=CC=C2)C2=C1N=C1C2=CC=CC=C2C4=N1 IEQIEDJGQAUEQZ-UHFFFAOYSA-N 0.000 description 17
- 238000005259 measurement Methods 0.000 description 16
- 239000000243 solution Substances 0.000 description 16
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 14
- 238000004519 manufacturing process Methods 0.000 description 11
- NUSQOFAKCBLANB-UHFFFAOYSA-N phthalocyanine tetrasulfonic acid Chemical compound C12=CC(S(=O)(=O)O)=CC=C2C(N=C2NC(C3=CC=C(C=C32)S(O)(=O)=O)=N2)=NC1=NC([C]1C=CC(=CC1=1)S(O)(=O)=O)=NC=1N=C1[C]3C=CC(S(O)(=O)=O)=CC3=C2N1 NUSQOFAKCBLANB-UHFFFAOYSA-N 0.000 description 10
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 229920000557 Nafion® Polymers 0.000 description 3
- 238000002835 absorbance Methods 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000000969 carrier Substances 0.000 description 3
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- 238000010438 heat treatment Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000011002 quantification Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000010992 reflux Methods 0.000 description 3
- 150000003284 rhodium compounds Chemical class 0.000 description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- MUBZPKHOEPUJKR-UHFFFAOYSA-L Oxalate Chemical compound [O-]C(=O)C([O-])=O MUBZPKHOEPUJKR-UHFFFAOYSA-L 0.000 description 2
- 230000010718 Oxidation Activity Effects 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
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- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229940039748 oxalate Drugs 0.000 description 2
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- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
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- 208000001019 Inborn Errors Metabolism Diseases 0.000 description 1
- 239000004693 Polybenzimidazole Substances 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 208000009911 Urinary Calculi Diseases 0.000 description 1
- 230000007488 abnormal function Effects 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
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- 150000007513 acids Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- QXDMQSPYEZFLGF-UHFFFAOYSA-L calcium oxalate Chemical compound [Ca+2].[O-]C(=O)C([O-])=O QXDMQSPYEZFLGF-UHFFFAOYSA-L 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
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- 238000003745 diagnosis Methods 0.000 description 1
- 210000002249 digestive system Anatomy 0.000 description 1
- IRXRGVFLQOSHOH-UHFFFAOYSA-L dipotassium;oxalate Chemical compound [K+].[K+].[O-]C(=O)C([O-])=O IRXRGVFLQOSHOH-UHFFFAOYSA-L 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000002330 electrospray ionisation mass spectrometry Methods 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
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- 229910001447 ferric ion Inorganic materials 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
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- 229910002804 graphite Inorganic materials 0.000 description 1
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- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
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- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 229940099596 manganese sulfate Drugs 0.000 description 1
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- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 1
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- CFQCIHVMOFOCGH-UHFFFAOYSA-N platinum ruthenium Chemical compound [Ru].[Pt] CFQCIHVMOFOCGH-UHFFFAOYSA-N 0.000 description 1
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- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 description 1
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Images
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
- Y02E60/50—Fuel cells
Abstract
Description
本発明は、シュウ酸類の電気化学的酸化反応用触媒に関する。 The present invention relates to a catalyst for an electrochemical oxidation reaction of oxalic acids.
シュウ酸またはその塩類の定量は臨床化学の分野において重要である。例えば、血中または尿中のシュウ酸の定量は尿路結石の診断あるいは先天性代謝異常の判定等に利用可能であり、糞便中のシュウ酸の定量は消化器系の異常機能を診断するための分析法として利用可能である。また、シュウ酸は有毒であるために食品衛生法においては、食品中の許容量が定められている。このため、規定量を超えたシュウ酸を含有する有害食品の検出のためにシュウ酸の簡易な定量法の確立が望まれている。またシュウ酸は水に対する溶解度が低いので、ビールなどにおいて原料由来のシュウ酸が析出沈殿してビールの商品価値を低下させることがあり、その防止策を立てるためにもシュウ酸の定量の重要性が認められてきている。 The quantification of oxalic acid or its salts is important in the field of clinical chemistry. For example, quantification of oxalic acid in blood or urine can be used for diagnosis of urinary stones or determination of inborn errors of metabolism, etc., and quantification of oxalic acid in feces can diagnose abnormal functions of the digestive system It can be used as an analysis method. In addition, since oxalic acid is toxic, the food hygiene law defines an allowable amount in food. For this reason, establishment of a simple quantitative method for oxalic acid is desired for detection of harmful foods containing oxalic acid in excess of the prescribed amount. Also, since oxalic acid has low solubility in water, oxalic acid derived from raw materials may be precipitated in beer and the like, thereby reducing the commercial value of beer. Has been recognized.
このような背景から様々なシュウ酸の定量法が開発されている。例えば、シュウ酸又はその塩類に第２鉄イオン溶液を反応させ、得られた溶液について特定波長の光の吸光度を測定する方法（特許文献１参照）、金属銀の表面に特定の方法でシュウ酸銀皮膜を析出させて得られたシュウ酸イオン選択性電極をシュウ酸イオンセンサとして用いる方法（特許文献２参照）等が報告されている。しかしながら、これらの方法は、測定法或いは電極の調製法が煩雑であり、簡便な電気化学センサの開発が求められている。 Against this background, various methods for determining oxalic acid have been developed. For example, a method in which a ferric ion solution is reacted with oxalic acid or a salt thereof, and the absorbance of light having a specific wavelength is measured with respect to the obtained solution (see Patent Document 1). A method of using an oxalate ion selective electrode obtained by depositing a silver film as an oxalate ion sensor (see Patent Document 2) has been reported. However, these methods require complicated measurement methods or electrode preparation methods, and the development of simple electrochemical sensors is required.
また、電気化学的反応によって廃水処理を行う方法が注目されているが、シュウ酸は電気化学的酸化反応に対しては難分解性であり、通常の電気化学的廃水処理法では、シュウ酸が蓄積するという問題点がある。シュウ酸などの排水中の難分解性有機物の電気化学的分解法としては、該有機化合物を含有する水溶液に、塩化物、硫酸マンガン等の電解質塩を添加して電気分解する方法が報告されている（特許文献３参照）。しかしながら、この方法は、新たに電解質を加えるために廃水処理法としては望ましくなく、活用する電力も依然大きいという問題点がある。このため、この分野においても、電気化学的に分解しにくいシュウ酸を電極酸化できる触媒の開発が求められている。 In addition, although a method of treating wastewater by an electrochemical reaction has attracted attention, oxalic acid is hardly decomposable to an electrochemical oxidation reaction, and oxalic acid is not dissolved in a normal electrochemical wastewater treatment method. There is a problem of accumulation. As an electrochemical decomposition method of hardly decomposable organic substances in wastewater such as oxalic acid, a method of electrolyzing by adding an electrolyte salt such as chloride or manganese sulfate to an aqueous solution containing the organic compound has been reported. (See Patent Document 3). However, this method is not desirable as a wastewater treatment method because a new electrolyte is added, and there is a problem that the power to be used is still large. For this reason, also in this field, development of a catalyst capable of electrode oxidation of oxalic acid which is not easily decomposed electrochemically is required.
シュウ酸の電気化学的酸化用触媒としては、金属ポルフィリンを有効成分とする触媒が知られている（特許文献４参照）。この触媒を用いることにより、シュウ酸を低い過電圧で効率良く酸化させることが可能となるが、センサにおける選択性の向上、電気化学的廃水処理における当入電力の低下などの観点から、より優れた性能を有するシュウ酸の電気化学的酸化反応用触媒が望まれている。
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、シュウ酸センサ、燃料電池のアノード触媒、排水有機物電解処理装置等における使用に適した、シュウ酸、その塩類などのシュウ酸類の電気化学的酸化反応に有効な新規な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. The main object of the present invention is to provide an oxalic acid sensor, a fuel cell anode catalyst, a wastewater organic electrolysis apparatus, and the like suitable for use in an oxalic acid sensor. It is to provide a novel catalyst effective for electrochemical oxidation reaction of oxalic acids such as acids and salts thereof.
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、特定のロジウムフタロシアニン化合物が、従来知られているシュウ酸類の電気化学的酸化用触媒と比較して、非常に高い触媒活性を有し、これまでにない低い過電圧で効率よくシュウ酸又はその塩類を電気化学的に酸化できることを見出し、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, a specific rhodium phthalocyanine compound has a very high catalytic activity as compared with conventionally known catalysts for electrochemical oxidation of oxalic acid, and oxalic acid or oxalic acid can be efficiently produced at an unprecedented low overvoltage. It has been found that the salts can be oxidized electrochemically, and the present invention has been completed here.
即ち、本発明は、下記のシュウ酸類の電気化学的酸化反応用触媒及びその用途を提供するものである。
１． 下記化学式：
That is, the present invention provides the following catalyst for electrochemical oxidation reaction of oxalic acid and its use.
1. The following chemical formula:
（式中、Ｒ１〜Ｒ１６は、同一又は異なって、それぞれ、水素原子、アルキル基、アルコキシル基、ハロゲン原子又はスルホン酸基を示すか、或いは、Ｒ２とＲ３、Ｒ６とＲ７、Ｒ１０とＲ１１、Ｒ１４とＲ１５の各組み合わせの少なくとも一組は互いに結合して、これらの各基が結合する炭素原子と共に、置換基を有することのある芳香族環を形成してもよい。）で表されるロジウムフタロシアニン化合物を有効成分とするシュウ酸類の電気化学的酸化反応用触媒。
２． 上記ロジウムフタロシアニン化合物が導電性担体に担持されたものである上記項１に記載のシュウ酸類の電気化学的酸化反応用触媒。
３． 導電性担体がカーボンブラックである上記項２に記載の触媒。
４． 上記項１〜３のいずれかに記載の触媒を検出部における酸化用触媒成分として含むシュウ酸類の検出用センサ。
５． 上記項１〜３のいずれかに記載の触媒をアノード触媒として含む、シュウ酸類を燃料とする固体高分子形燃料電池用アノード極。
６． 上記項１〜３のいずれかに記載の触媒、及びアノード触媒物質を含むエチレングリコールを燃料とする固体高分子形燃料電池用アノード極。
７． 電解槽、作用極、対極および電源装置を含む電解処理装置であって、上記項１〜３のいずれかに記載の触媒を作用極におけるシュウ酸類の酸化用触媒として含むことを特徴とする、水溶液中のシュウ酸類の電解処理装置。
(Wherein R 1 to R 16 are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxyl group, a halogen atom or a sulfonic acid group, or R 2 and R 3 , R 6 and R 7). , R 10 and R 11 , and each combination of R 14 and R 15 are bonded to each other to form an aromatic ring which may have a substituent together with the carbon atom to which these groups are bonded. A catalyst for an electrochemical oxidation reaction of oxalic acid containing a rhodium phthalocyanine compound represented by
2.
3.
4). A sensor for detecting oxalic acid comprising the catalyst according to any one of
5). An anode for a polymer electrolyte fuel cell using oxalic acid as a fuel, comprising the catalyst according to any one of
6). 4. An anode for a polymer electrolyte fuel cell using ethylene glycol containing the catalyst according to any one of
7). An electrolytic treatment apparatus including an electrolytic cell, a working electrode, a counter electrode, and a power supply device, wherein the aqueous solution contains the catalyst according to any one of
以下、本発明のシュウ酸類の電気化学的酸化反応用触媒について具体的に説明する。
（１）本発明触媒
本発明のシュウ酸類の電気化学的酸化反応用触媒は、下記化学式：
Hereinafter, the catalyst for electrochemical oxidation reaction of oxalic acid of the present invention will be specifically described.
(1) Catalyst of the present invention The catalyst for electrochemical oxidation reaction of oxalic acid of the present invention has the following chemical formula:
で表されるロジウムフタロシアニン化合物を有効成分とするものである。 The rhodium phthalocyanine compound represented by these is used as an active ingredient.
上記化学式において、Ｒ１〜Ｒ1６は、同一又は異なって、それぞれ、水素原子、アル
キル基、アルコキシル基、ハロゲン原子又はスルホン酸基を示す。更に、これらの内で、Ｒ２とＲ３、Ｒ６とＲ７、Ｒ１０とＲ１１、Ｒ１４とＲ１５の各組み合わせの少なくとも一組は互いに結合して、これらの各基が結合する炭素原子と共に、置換基を有することのある芳香族環を形成してもよい。
In the above chemical formula, R 1 to R 16 are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxyl group, a halogen atom, or a sulfonic acid group. Further, among these, at least one of each combination of R 2 and R 3 , R 6 and R 7 , R 10 and R 11 , R 14 and R 15 is bonded to each other, and these groups are bonded. You may form the aromatic ring which may have a substituent with a carbon atom.
これらの内で、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。アルコキシル基としては、例えば、メトキシ、エトキシ、ｎ−プロポキシ、イソプロポキシ、ｎ−ブトキシ、tert−ブトキシ、ｎ−ペンチルオキシ、ｎ−ヘキシルオキシ基等の炭素数１〜６の直鎖又は分枝鎖状アルコキシル基が好ましい。また、ハロゲン原子としては、フッ素、塩素、臭素などが好ましい。 Among these, as an alkyl group, methyl, ethyl, isopropyl, n-propyl, t-butyl, sec-butyl, n-butyl, isobutyl, n-pentyl, etc. A branched lower alkyl group is preferred. Examples of the alkoxyl group include straight chain or branched chain having 1 to 6 carbon atoms such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, n-pentyloxy, n-hexyloxy group and the like. An alkoxyl group is preferred. Further, as the halogen atom, fluorine, chlorine, bromine and the like are preferable.
上記化学式で表されるロジウムフタロシアニン化合物の内で、例えば、Ｒ１〜Ｒ１６が全て水素原子である化合物は、シュウ酸類の電気化学的酸化反応に対して高い活性を有するものである。 Among the rhodium phthalocyanine compounds represented by the above chemical formula, for example, a compound in which R 1 to R 16 are all hydrogen atoms has high activity for the electrochemical oxidation reaction of oxalic acids.
また、Ｒ２とＲ３、Ｒ６とＲ７、Ｒ１０とＲ１１、Ｒ１４とＲ１５の各組み合わせが互いに結合して、これらの各基が結合する炭素原子と共に、置換基を有することのある芳香族環を形成した化合物として、下記化学式 Each combination of R 2 and R 3 , R 6 and R 7 , R 10 and R 11 , R 14 and R 15 is bonded to each other, and has a substituent together with the carbon atom to which these groups are bonded. As an aromatic ring-containing compound, the following chemical formula
で表される化合物を例示できる。上記化学式において、Ｒ１７〜Ｒ３２は、同一又は異なって、それぞれ、水素原子、アルキル基、アルコキシル基、ハロゲン原子又はスルホン酸基を示す。これらの各基の具体例は、Ｒ１〜Ｒ1６と同様である。 The compound represented by these can be illustrated. In the above chemical formula, R 17 to R 32 are the same or different and each represents a hydrogen atom, an alkyl group, an alkoxyl group, a halogen atom, or a sulfonic acid group. Specific examples of each of these groups are the same as R 1 to R 16 .
本発明の触媒における有効成分である上記化学式で表されるロジウムフタロシアニン化合物は、シュウ酸、シュウ酸カリウム、シュウ酸ナトリウム、シュウ酸カルシウム等の水溶性シュウ酸塩等のシュウ酸類の電気化学的酸化反応用の触媒として、優れた活性を有するものである。 The rhodium phthalocyanine compound represented by the above chemical formula, which is an active ingredient in the catalyst of the present invention, is an electrochemical oxidation of oxalic acids such as water-soluble oxalates such as oxalic acid, potassium oxalate, sodium oxalate, and calcium oxalate. As a catalyst for the reaction, it has excellent activity.
シュウ酸の電気化学的酸化反応は、下記反応式：
COOH-COOH → 2 H+ + 2 CO2+ 2 e-
で表されるものであり、上記したロジウムフタロシアニン化合物の存在下にシュウ酸類を電気化学的に酸化することによって、低い過電圧で効率よくシュウ酸類を酸化することが可能となる。
The electrochemical oxidation reaction of oxalic acid is represented by the following reaction formula:
COOH-COOH → 2 H + + 2
By oxidizing the oxalic acid electrochemically in the presence of the rhodium phthalocyanine compound described above, the oxalic acid can be efficiently oxidized with a low overvoltage.
上記したロジウムフタロシアニン化合物は、例えば、目的とするロジウムフタロシアニン化合物の配位子となる化合物とロジウム化合物を溶媒中に溶解し、加熱することによって製造することができる。ロジウム化合物としては、例えば、一価のロジウム金属が含まれるロジウム錯体を用いることができる。溶媒としては、上記した配位子となる化合物とロジウム化合物を溶解できる溶媒を用いればよく、例えば、ジメチルホルムアミドなどを用いることができる。加熱温度については、例えば、使用する溶媒の還流温度とすればよい。 The rhodium phthalocyanine compound described above can be produced, for example, by dissolving a compound serving as a ligand of the target rhodium phthalocyanine compound and the rhodium compound in a solvent and heating. As the rhodium compound, for example, a rhodium complex containing a monovalent rhodium metal can be used. As the solvent, a solvent capable of dissolving the above-described ligand compound and rhodium compound may be used. For example, dimethylformamide or the like can be used. The heating temperature may be, for example, the reflux temperature of the solvent used.
上記したロジウムフタロシアニン化合物は、導電性担体に担持させることにより、シュウ酸類の電気化学的酸化反応に対して高い触媒活性を有するものとすることができる。 The rhodium phthalocyanine compound described above can have high catalytic activity for the electrochemical oxidation reaction of oxalic acids 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、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 is a particularly preferable substance as a conductive carrier because it is excellent in conductivity and has a large specific surface area.
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、２００〜３００ ｍ２／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, is preferably one in the range BET specific surface area of about 100~800m 2 / g, more is intended to be within the range of about 200 to 300 [m 2 / g preferable. 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、該ロジウムフタロシアニン化合物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、該担体にロジウムフタロシアニン化合物を吸着させた後、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フタロシアニン化合物が多量に含まれる場合には、平衡に達するまでロジウムフタロシアニン化合物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フタロシアニン化合物を除去して、該担体と相互作用しているロジウムフタロシアニン化合物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, the rhodium phthalocyanine compound is dissolved in an organic solvent, and a conductive carrier is added to the solution. For example, the rhodium phthalocyanine compound is adsorbed on the carrier by stirring for several hours. Can be dried. If the organic solvent contains a large amount of rhodium phthalocyanine compound, the rhodium phthalocyanine compound is adsorbed on the conductive support until equilibrium is reached, and then filtered to obtain rhodium phthalocyanine that is not adsorbed on the conductive support. The compound can be removed, leaving only the rhodium phthalocyanine compound interacting with the carrier on the surface of the carrier.
この方法では、有機溶媒としては、ロジウムフタロシアニン化合物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、ジクロロメタン、クロロホルム等の塩素系炭化水素を好適に用いることができる。 In this method, any organic solvent can be used without particular limitation as long as it can dissolve the rhodium phthalocyanine compound. For example, chlorinated hydrocarbons such as dichloromethane and chloroform 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フタロシアニン化合物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フタロシアニン化合物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, the rhodium phthalocyanine compound having a weak interaction with the conductive carrier can be washed away and firmly adsorbed on the conductive carrier. Thus, it is possible to obtain a highly active catalyst containing only the rhodium phthalocyanine compound.
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フタロシアニン化合物の量については、特に限定はないが、例えば、導電性担体１ｇに対して、ロジウムフタロシアニン化合物を１０μｍｏｌ〜１５０μｍｏｌ程度担持させることが好ましく、２０μｍｏｌ〜５０μｍｏｌ程度担持させることがより好ましい。 The amount of the rhodium phthalocyanine compound supported on the conductive carrier is not particularly limited. For example, the rhodium phthalocyanine compound is preferably supported on the order of 10 μmol to 150 μmol, and about 20 μmol to 50 μmol is supported on 1 g of the conductive carrier. More preferably.
上記したロジウムフタロシアニン化合物を有効成分とする本発明のシュウ酸類の電気化学的酸化反応用触媒は、該触媒にシュウ酸類が接触した状態において、所定の電位とすることによって、シュウ酸類を選択性よく電気化学的に酸化させることができる。この場合の具体的な電位については、使用するロジウムフタロシアニン化合物の種類や溶液の状態によって異なるので一概に規定できないが、例えば、0.1M H2SO4水溶液中で２５℃で測定した電位（AgCl/KCl(飽和)電極基準）として、０．３ V〜０．８ V程度とすることが好ましく、０．４ V〜０．６ V程度とすることがより好ましい。 The catalyst for electrochemical oxidation reaction of oxalic acid of the present invention comprising the rhodium phthalocyanine compound as an active ingredient described above, the oxalic acid can be selected with high selectivity by setting the oxalic acid to a predetermined potential in a state where the oxalic acid is in contact with the catalyst. It can be oxidized electrochemically. The specific potential in this case varies depending on the type of rhodium phthalocyanine compound used and the state of the solution, and thus cannot be specified unconditionally. For example, the potential (AgCl / KCl) measured at 25 ° C. in a 0.1 MH 2 SO 4 aqueous solution. (Saturation) electrode reference) is preferably about 0.3 V to 0.8 V, more preferably about 0.4 V to 0.6 V.
（２）本発明触媒の用途：
本発明のシュウ酸類の電気化学的酸化反応用触媒は、上記した所定範囲の電位に保持することによって、低い過電圧で効率よくシュウ酸類の電解化学的酸化反応を進行させることができる。この様な性質を利用して以下に示す各種の用途に用いることができる。
(2) Use of the catalyst of the present invention:
The catalyst for electrochemical oxidation reaction of oxalic acid according to the present invention can advance the electrochemical oxidation reaction of oxalic acid efficiently with a low overvoltage by maintaining the potential within the predetermined range. Utilizing such properties, it can be used for various applications described below.
（ｉ）シュウ酸センサ
導電体上に本発明の触媒を固定した電極を電気化学的にシュウ酸類の濃度を測定するためのシュウ酸センサとして用いることができる。
(I) Oxalic acid sensor An electrode in which the catalyst of the present invention is fixed on a conductor can be used as an oxalic acid sensor for electrochemically measuring the concentration of oxalic acids.
シュウ酸センサの具体的な構造については、本発明の触媒を用いること以外は、一般的な電流測定型（アンペロメトリック）センサと同様の構造とすればよい。例えば、各種金属、炭素（グラッシーカーボン電極など）などの導電体上に、ナフィオン（商標名）等の導電性を有するバインダを用いて本発明の触媒を固定することによって、シュウ酸類の測定用電極とすることができる。この様にして作製された電極を作用電極として用い、対極を用いた二電極系、又は対極と参照極を用いた三電極系において、印加電圧を一定に固定して電流値を測定することによって、シュウ酸類の濃度を測定することができる。この場合、対極、参照極などとしては、一般的な電気化学的測定に用いられているものを利用することができる。 The specific structure of the oxalic acid sensor may be the same as that of a general amperometric sensor except that the catalyst of the present invention is used. For example, an electrode for measuring oxalic acids by fixing the catalyst of the present invention on a conductive material such as various metals and carbon (such as glassy carbon electrode) using a conductive binder such as Nafion (trade name). It can be. In the two-electrode system using the counter electrode or the three-electrode system using the counter electrode and the reference electrode, the applied voltage is fixed and the current value is measured using the electrode thus manufactured as a working electrode. The concentration of oxalic acid can be measured. In this case, as a counter electrode, a reference electrode, etc., those used for general electrochemical measurement can be used.
測定対象については特に限定はなく、例えば、食品中・血液中・尿中・糞便中等の各種の媒体中に含まれるシュウ酸類を定量することができる。特に、本発明のシュウ酸センサは、水溶液中のシュウ酸類の濃度測定に適したものであり、酸性〜アルカリ性（ｐＨ０〜１４）の広いｐＨ範囲の水溶液中のシュウ酸類の濃度を測定することができる。
The measurement target is not particularly limited, and for example, oxalic acids contained in various media such as food, blood, urine, and feces can be quantified. In particular, the oxalic acid sensor of the present invention is suitable for measuring the concentration of oxalic acid in an aqueous solution, and can measure the concentration of oxalic acid in an aqueous solution in a wide pH range from acidic to alkaline (
具体的な測定方法として、センサに印加する電位を所定の電位に保持することにより、
シュウ酸類の存在量に応じて酸化電流が変化するので、この測定結果に基づいてシュウ酸類の濃度を定量すればよい。印加電圧は、十分なシュウ酸酸化電流が流れ、水や錯体が分解されない電圧とすればよい。具体的な電圧は、ｐＨによって異なるが、例えば、0.1 M H2SO4中では0.3 V〜0.8 V(Ag/AgCl/KCl(飽和)基準)程度とすればよい。測定時の液温は、例えば、10℃〜80℃程度とすればよい。
As a specific measurement method, by holding the potential applied to the sensor at a predetermined potential,
Since the oxidation current changes according to the amount of oxalic acid present, the concentration of oxalic acid may be determined based on the measurement result. The applied voltage may be a voltage at which a sufficient oxalic acid oxidation current flows and water and the complex are not decomposed. The specific voltage varies depending on the pH, but may be, for example, about 0.3 V to 0.8 V (Ag / AgCl / KCl (saturation) standard) in 0.1 MH 2 SO 4 . What is necessary is just to let the liquid temperature at the time of a measurement be about 10 degreeC-80 degreeC, for example.
（ii）固体高分子形燃料電池のアノード触媒
本発明の触媒は、シュウ酸、シュウ酸塩等のシュウ酸類を燃料として用いる固体高分子形燃料電池のアノード触媒として用いることができる。
(Ii) Anode catalyst of polymer electrolyte fuel cell The catalyst of the present invention can be used as an anode catalyst of a polymer electrolyte fuel cell using oxalic acid such as oxalic acid or oxalate as a fuel.
アノード触媒として使用する場合には、本発明触媒をアノード触媒物質として用いること以外は、アノード極の構造、及びこのアノード極を用いる固体高分子形燃料電池の構造については、特に限定はなく、公知の燃料電池、例えば、水素を燃料とする燃料電池やダイレクトメタノール形燃料電池と同様とすればよい。即ち、高分子電解質膜、電極触媒、膜−電極接合体、セル構造等については、公知の固体高分子形燃料電池と同様とすればよい。 When used as an anode catalyst, there is no particular limitation on the structure of the anode electrode and the structure of the polymer electrolyte fuel cell using this anode electrode, except that the catalyst of the present invention is used as an anode catalyst material. For example, a fuel cell using hydrogen as a fuel or a direct methanol fuel cell may be used. That is, the polymer electrolyte membrane, the electrode catalyst, the membrane-electrode assembly, the cell structure and the like may be the same as those of a known solid polymer fuel cell.
例えば、カソード極の触媒金属としては、従来から知られている種々の金属、金属合金などを使用することができる。具体例としては、白金、パラジウム、イリジウム、ロジウム、ルテニウム、白金−ルテニウムをはじめとする各種金属触媒、またはこれらの触媒微粒子をカーボンなどの担体上に分散させた担持触媒などが挙げられる。 For example, conventionally known various metals and metal alloys can be used as the cathode catalyst metal. Specific examples include various metal catalysts including platinum, palladium, iridium, rhodium, ruthenium, platinum-ruthenium, or a supported catalyst in which these catalyst fine particles are dispersed on a carrier such as carbon.
高分子電解質膜としては、パーフルオロカーボン系、スチレン−ジビニルベンゼン共重合体系、ポリベンズイミダゾール系をはじめとする各種イオン交換樹脂膜、無機高分子イオン交換膜、有機−無機複合体高分子イオン交換膜等を使用することができる。 Polymer electrolyte membranes include perfluorocarbon, styrene-divinylbenzene copolymer, polybenzimidazole and other ion exchange resin membranes, inorganic polymer ion exchange membranes, organic-inorganic composite polymer ion exchange membranes, etc. Can be used.
固体高分子電解質膜と電極触媒との接合体は、公知の方法により作製することができる。例えば、触媒粉末と電解質溶液とを混合して作製した触媒インクを薄膜化させた後、電解質膜上にホットプレスする方法、あるいは直接高分子膜上に塗布・乾燥する方法などが適用される。 The joined body of the solid polymer electrolyte membrane and the electrode catalyst can be produced by a known method. For example, a method in which a catalyst ink produced by mixing catalyst powder and an electrolyte solution is thinned and then hot-pressed on the electrolyte membrane or directly applied and dried on the polymer membrane is applied.
得られた膜−電極接合体の両面をカーボンペーパー、カーボンクロスなどの集電体で挟んでセルに組み込むことによって、燃料電池セルを作製することができる。 A fuel battery cell can be produced by sandwiching both surfaces of the obtained membrane-electrode assembly between current collectors such as carbon paper and carbon cloth and incorporating them into the cell.
本発明の触媒をアノード触媒とする燃料電池では、シュウ酸、シュウ酸塩等のシュウ酸類を燃料としてアノードに供給し、カソード側には、空気又は酸素を供給又は自然拡散させればよい。 In a fuel cell using the catalyst of the present invention as an anode catalyst, oxalic acid such as oxalic acid and oxalate may be supplied as fuel to the anode, and air or oxygen may be supplied or naturally diffused to the cathode side.
本発明の燃料電池の作動温度は、使用する電解質膜によって異なるが、通常０℃〜１００℃ 程度であり、好ましくは１０℃〜８０℃ 程度である。 The operating temperature of the fuel cell of the present invention varies depending on the electrolyte membrane to be used, but is usually about 0 ° C to 100 ° C, preferably about 10 ° C to 80 ° C.
（iii）エチレングリコール形燃料電池用助触媒
本発明の触媒は、エチレングリコールを燃料として直接供給する固体高分子形燃料電池において、アノード触媒物質と組み合わせて用いることによって、エチレングリコールを燃料とする場合のアノード反応による生成物であるシュウ酸を酸化することができる。これにより、エチレングリコール形燃料電池の反応効率を向上させることができる。
(Iii) Co-catalyst for ethylene glycol fuel cell When the catalyst of the present invention is used in combination with an anode catalyst material in a polymer electrolyte fuel cell that directly supplies ethylene glycol as a fuel, the ethylene glycol fuel is used. Oxalic acid, which is a product of the anodic reaction, can be oxidized. Thereby, the reaction efficiency of an ethylene glycol fuel cell can be improved.
アノード極におけるアノード触媒物質としては、例えば、白金等の公知の触媒を用いることができる。本発明のシュウ酸類の電気化学的酸化反応用触媒とアノード触媒物質の割合は、特に限定的ではないが、例えば、前者１００重量部に対して、後者５０〜５００重
量部程度の範囲から適宜決めればよい。エチレングリコールの電気化学的酸化用触媒とアノード触媒物質は、それぞれ、別個の導電性担体に担持させて用いても良く、或いは、同一の担体に担持させても良い。同一の担体に担持させる場合には、例えば、白金等の触媒物質を担持させた担体上に、更に、上記した各種の方法でロジウムフタロシアニン化合物を担持させる方法、ロジウムフタロシアニン化合物を担持させた担体上に、更に、白金などの触媒物質を担持させる方法などを適用できる。
As the anode catalyst material in the anode electrode, for example, a known catalyst such as platinum can be used. The ratio of the catalyst for the electrochemical oxidation reaction of the oxalic acid of the present invention and the anode catalyst material is not particularly limited. For example, it can be appropriately determined from the range of about 50 to 500 parts by weight of the latter with respect to 100 parts by weight of the former. That's fine. The catalyst for electrochemical oxidation of ethylene glycol and the anode catalyst material may be used by being supported on separate conductive carriers, or may be supported on the same carrier. In the case of carrying the same carrier, for example, a method of carrying a rhodium phthalocyanine compound by the above-mentioned various methods on a carrier carrying a catalyst material such as platinum, and a carrier carrying a rhodium phthalocyanine compound. In addition, a method of supporting a catalyst material such as platinum can be applied.
アノード極の構造、及びこのアノード極を用いる固体高分子形燃料電池の構造については、特に限定はなく、公知の燃料電池と同様とすればよい。 The structure of the anode electrode and the structure of the polymer electrolyte fuel cell using this anode electrode are not particularly limited, and may be the same as that of a known fuel cell.
（iv）シュウ酸類の電解処理装置における酸化用触媒
本発明の触媒は、排水などの水溶液中に含まれるシュウ酸類を電気化学的酸化反応によって分解するための電解処理装置における酸化用触媒として使用することができる。この電解処理装置は、酸化用触媒として、本発明の触媒を用いること以外は、通常の各種の電解装置と同様の構造とすることができる。例えば、電解槽、作用極、対極、電源装置などを含む電解装置とすればよい。
(Iv) Oxidation catalyst in oxalic acid electrolysis apparatus The catalyst of the present invention is used as an oxidation catalyst in an electrolysis apparatus for decomposing oxalic acid contained in an aqueous solution such as waste water by an electrochemical oxidation reaction. be able to. The electrolytic treatment apparatus can have the same structure as that of various ordinary electrolytic apparatuses except that the catalyst of the present invention is used as an oxidation catalyst. For example, an electrolytic device including an electrolytic cell, a working electrode, a counter electrode, a power supply device, and the like may be used.
この様な構造の電解装置において、本発明の触媒は、作用極におけるシュウ酸類の酸化用触媒として用いればよい。作用極では、炭素電極等の導電体を基材として用い、導電性を有するバインダにより本発明の触媒を該基材に固定すればよい。対極については特に限定はなく、通常の電解装置で用いられる各種電極を使用できる。例えば、炭素電極などを用いることができる。電源装置としては、例えば、所定の電位走査が可能な定電圧電源（ポテンシオスタット）などを用いることができる。更に、作用極を所定の電位に設定するために、通常、電解質溶液中に参照電極を設置する。参照電極としても、通常の電解装置において用いられている各種の電極を用いることができる。例えば、銀／塩化銀電極などを用いることができる。 In the electrolytic apparatus having such a structure, the catalyst of the present invention may be used as a catalyst for oxidizing oxalic acid at the working electrode. In the working electrode, a conductive material such as a carbon electrode may be used as a base material, and the catalyst of the present invention may be fixed to the base material with a conductive binder. There is no particular limitation on the counter electrode, and various electrodes used in a normal electrolysis apparatus can be used. For example, a carbon electrode can be used. As the power supply device, for example, a constant voltage power source (potentiostat) capable of scanning with a predetermined potential can be used. Further, in order to set the working electrode at a predetermined potential, a reference electrode is usually installed in the electrolyte solution. As the reference electrode, various electrodes used in a normal electrolysis apparatus can be used. For example, a silver / silver chloride electrode can be used.
この様な構成の電解装置を用いて、上記した条件に従って作用極を所定の電位に保持することによって、難分解性有機物であるシュウ酸類を効率よく分解することができる。 By using the electrolysis apparatus having such a configuration and maintaining the working electrode at a predetermined potential according to the above-described conditions, it is possible to efficiently decompose oxalic acids that are hardly decomposable organic substances.
本発明のシュウ酸類の電気化学的酸化反応用触媒は、シュウ酸類の電気化学的酸化反応に対して非常に高い活性を有する触媒である。よって、本発明の触媒を用いることによって、シュウ酸類を低い過電圧で効率よく酸化させることができる。 The catalyst for the electrochemical oxidation reaction of oxalic acid according to the present invention is a catalyst having very high activity for the electrochemical oxidation reaction of oxalic acid. Therefore, by using the catalyst of the present invention, oxalic acids can be efficiently oxidized at a low overvoltage.
このため、本発明の触媒は、例えば、シュウ酸センサのシュウ酸検知用触媒、シュウ酸類を燃料とする燃料電池のアノード触媒、エチレングリコールを燃料とする燃料電池のアノード用助触媒、シュウ酸類の電解処理装置における酸化用触媒などの各種の用途に有効に用いることができる。 Therefore, the catalyst of the present invention includes, for example, an oxalic acid detection catalyst for an oxalic acid sensor, an anode catalyst for a fuel cell using oxalic acid as a fuel, an auxiliary catalyst for an anode of a fuel cell using ethylene glycol as a fuel, an oxalic acid It can be effectively used for various applications such as an oxidation catalyst in an electrolytic treatment apparatus.
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.
製造例１
ロジウムフタロシアニンの製造
下記化学式
Production Example 1
Production of rhodium phthalocyanine
で表される市販のフタロシアニンを30 mg採取し、100mLのジメチルホルムアミドに溶解させた。その後、この溶液にテトラカルボニルジ-μ-クロロ二ロジウム(I) ([Rh2Cl2(CO)4])を12.5 mg加え、130℃で5時間、加熱還流を行った。還流後の沈殿物をろ過によって取り除き、濾液の紫外・可視分光スペクトル（UV-visスペクトル）を測定した。図１に紫外・可視分光スペクトルの吸光度曲線を示す。 30 mg of a commercially available phthalocyanine represented by the following formula was collected and dissolved in 100 mL of dimethylformamide. Thereafter, 12.5 mg of tetracarbonyldi-μ-chlorodirhodium (I) ([Rh 2 Cl 2 (CO) 4 ]) was added to this solution, and the mixture was heated to reflux at 130 ° C. for 5 hours. The precipitate after the reflux was removed by filtration, and the ultraviolet and visible spectrum (UV-vis spectrum) of the filtrate was measured. FIG. 1 shows an absorbance curve of an ultraviolet / visible spectrum.
図１において、曲線Ａが原料として用いたフタロシアニンに対応し、曲線Ｂが目的物であるロジウムフタロシアニンに対応する分光曲線である。曲線Ｂのスペクトルの形状は、既に報告されているロジウムフタロシアニンのスペクトル（Keen et al., J. Inorg. Nucl. Chem. 27 (1965) 1311-1319）と一致した。これにより目的化合物の生成を確認した。目的化合物の生成はESI-MSによっても確認した。この還流後の溶液をロータリーエバポレーターで濃縮した。 In FIG. 1, curve A corresponds to the phthalocyanine used as a raw material, and curve B is a spectral curve corresponding to the target rhodium phthalocyanine. The spectrum shape of curve B was consistent with the previously reported spectrum of rhodium phthalocyanine (Keen et al., J. Inorg. Nucl. Chem. 27 (1965) 1311-1319). This confirmed the formation of the target compound. The formation of the target compound was also confirmed by ESI-MS. The refluxed solution was concentrated using a rotary evaporator.
製造例２
ロジウムフタロシアニンテトラスルホン酸の製造
製造例１で用いたフタロシアニンに代えて、下記式
Production Example 2
Production of rhodium phthalocyanine tetrasulfonic acid Instead of the phthalocyanine used in Production Example 1, the following formula
で表されるフタロシアニンテトラスルホン酸を用い、それ以外は、製造例１と同様にして、ロジウムフタロシアニンテトラスルホン酸を作製した。図２に製造例１と同様にして採取した濾液の紫外・可視分光スペクトルの吸光度曲線を示す。図２において、曲線Ａが原料として用いたフタロシアニンテトラスルホン酸に対応し、曲線Ｂが目的物であるロジウムフタロシアニンテトラスルホン酸に対応する分光曲線である。 A rhodium phthalocyanine tetrasulfonic acid was produced in the same manner as in Production Example 1 except that phthalocyanine tetrasulfonic acid represented by FIG. 2 shows an absorbance curve of an ultraviolet / visible spectrum of the filtrate collected in the same manner as in Production Example 1. In FIG. 2, curve A corresponds to the phthalocyanine tetrasulfonic acid used as a raw material, and curve B is a spectral curve corresponding to the target rhodium phthalocyanine tetrasulfonic acid.
実施例１
ロジウムフタロシアニン担持カーボン触媒の作製
製造例１で得たロジウムフタロシアニンをジメチルホルムアミドに0.047 mMになるように溶解させた後、この溶液90 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30 mg加えた。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
Production of Rhodium Phthalocyanine-Supported Carbon Catalyst The rhodium phthalocyanine obtained in Production Example 1 was dissolved in dimethylformamide to a concentration of 0.047 mM, and carbon black (specific surface area 250 m 2 / g, trade name: Vulcan was then added to 90 mL of this solution. 30 mg of XC 72R (Cabot) was added. After sealing the container, 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ロジウムフタロシアニン溶液を、マグネティックス
ターラーで30分攪拌したのち、ジメチルホルムアミドをロータリーエバポレーターで除去した。その後、残ったカーボンブラックを回収してロジウムフタロシアニン担持カーボン触媒を得た。
The rhodium phthalocyanine solution in which the carbon black was suspended was stirred with a magnetic stirrer for 30 minutes, and then dimethylformamide was removed with a rotary evaporator. Thereafter, the remaining carbon black was recovered to obtain a rhodium phthalocyanine-supported carbon catalyst.
触媒活性の評価
上記した方法で得たロジウムフタロシアニン担持カーボン触媒5 mgを0.5 mLの混合溶媒（水：エタノール = 1 : 1）に懸濁させた後、5 μLの5 % Nafion溶液(Aldrich製)を加えた。この懸濁液を５分間超音波洗浄器に掛けることで、よく分散させた後、グラッシーカーボン電極（表面積= 0.071 cm2）の上に2 μLのせて乾燥させた。
Evaluation of catalytic activity After 5 mg of rhodium phthalocyanine-supported carbon catalyst obtained by the above method was suspended in 0.5 mL of mixed solvent (water: ethanol = 1: 1), 5 μL of 5% Nafion solution (Aldrich) Was added. This suspension was thoroughly dispersed by applying it to an ultrasonic cleaner for 5 minutes, and then dried by placing 2 μL on a glassy carbon electrode (surface area = 0.071 cm 2 ).
触媒のシュウ酸酸化活性評価はエー・エル・エス製のポテンショスタット（ALS model 711B）を用いて行った。触媒を塗布したグラッシーカーボン電極を作用電極とし、白金電極を対極、Ag/AgCl/KCl(sat.)電極を参照電極として用いた。電解液としては0.1 M H2SO4を用いた。 Evaluation of the oxalic acid oxidation activity of the catalyst was performed using a potentiostat (ALS model 711B) manufactured by ALS. A glassy carbon electrode coated with a catalyst was used as a working electrode, a platinum electrode as a counter electrode, and an Ag / AgCl / KCl (sat.) Electrode as a reference electrode. As the electrolyte, 0.1 MH 2 SO 4 was used.
まず、シュウ酸のない条件でのロジウムフタロシアニンの電気化学的特性を調べるために、測定前に不活性ガス（窒素またはアルゴン）を電解液に10分間吹き込んだ後、サイクリックボルタンメトリー（CV）測定を開始した。測定中は不活性ガスを溶液の上部に連続的に吹き付けることで、酸素の混入を防ぐようにした。ロジウムフタロシアニン担持カーボンのCVを図３の曲線Ａとして示す。尚、図３の右図は、低電流分の拡大図である。 First, in order to investigate the electrochemical properties of rhodium phthalocyanine in the absence of oxalic acid, inert gas (nitrogen or argon) was blown into the electrolyte for 10 minutes before measurement, and then cyclic voltammetry (CV) measurement was performed. Started. During the measurement, inert gas was continuously blown over the top of the solution to prevent oxygen contamination. The CV of the rhodium phthalocyanine-supported carbon is shown as curve A in FIG. In addition, the right figure of FIG. 3 is an enlarged view for a low current.
次に、ロジウムフタロシアニン担持カーボンのシュウ酸酸化触媒能を検討した。シュウ酸を10 mM加えた後、サイクリックボルタンメトリー（CV）測定を開始した。シュウ酸を
加えた条件では0.23 V (Ag/AgCl/KCl(飽和)基準)付近から酸化電流が上昇しはじめており、シュウ酸の酸化が低い過電圧で進行していることがわかる（図３の曲線Ｂ）。さらにシュウ酸を合計で90 mMになるように加えると、酸化電流は上昇し、濃度に応じた応答を示
すことが確認できた（曲線C）。さらに、シュウ酸濃度を0.5Mまで上昇させると、電極表
面積が0.071 cm2しかないにもかかわらず、4mAを越える高い電流値を示した（曲線D）。
Next, the oxalic acid oxidation catalytic ability of rhodium phthalocyanine-supported carbon was examined. After adding 10 mM oxalic acid, cyclic voltammetry (CV) measurement was started. Under the condition where oxalic acid was added, the oxidation current started to increase from around 0.23 V (Ag / AgCl / KCl (saturated) standard), and it can be seen that the oxidation of oxalic acid proceeds at a low overvoltage (curve in Fig. 3). B). Furthermore, when oxalic acid was added to a total of 90 mM, the oxidation current increased and it was confirmed that a response corresponding to the concentration was exhibited (curve C). Furthermore, when the oxalic acid concentration was increased to 0.5 M, a high current value exceeding 4 mA was exhibited even though the electrode surface area was only 0.071 cm 2 (curve D).
以上の結果から、ロジウムフタロシアニン担持カーボン触媒は、シュウ酸の電気化学的酸化反応に対して高い活性を有することが明らかである。 From the above results, it is clear that the rhodium phthalocyanine-supported carbon catalyst has high activity for the electrochemical oxidation reaction of oxalic acid.
実施例２
ロジウムフタロシアニンテトラスルホン酸担持カーボン触媒の作製
ロジウムフタロシアニンテトラスルホン酸をジメチルホルムアミドに0.15 mMになるよ
うに溶解させた後、この溶液20 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30 mg加えた。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 2
Preparation of rhodium phthalocyanine tetrasulfonic acid-supported carbon catalyst Rhodium phthalocyanine tetrasulfonic acid was dissolved in dimethylformamide to a concentration of 0.15 mM, and carbon black (specific surface area 250 m 2 / g, trade name: Vulcan) was added to 20 mL of this solution. 30 mg of XC 72R (Cabot) was added. After sealing the container, 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溶液を、マグネティックスターラーで30分攪拌したのち、ジメチルホルムアミドをロータリーエバポレーターで除去した。その後、残ったカーボンブラックを回収してロジウムフタロシアニンテトラスルホン酸担持カーボン触媒を得た。 The carbon black-suspended solution was stirred with a magnetic stirrer for 30 minutes, and then dimethylformamide was removed with a rotary evaporator. Thereafter, the remaining carbon black was recovered to obtain a rhodium phthalocyanine tetrasulfonic acid-supported carbon catalyst.
触媒活性の評価
上記した方法で得たロジウムフタロシアニンテトラスルホン酸担持カーボン触媒5 mgを0.5 mLの混合溶媒（水：エタノール = 1 : 1）に懸濁させた後、5 μLの5 % Nafion溶液(Aldrich製)を加えた。この懸濁液を５分間超音波洗浄器に掛けることで、よく分散させた後、グラッシーカーボン電極（表面積= 0.071 cm2）の上に2 μLのせて乾燥させた。
Evaluation of catalytic activity After 5 mg of the rhodium phthalocyanine tetrasulfonic acid-supported carbon catalyst obtained by the above-mentioned method was suspended in 0.5 mL of a mixed solvent (water: ethanol = 1: 1), 5 μL of 5% Nafion solution ( Aldrich) was added. This suspension was thoroughly dispersed by applying it to an ultrasonic cleaner for 5 minutes, and then dried by placing 2 μL on a glassy carbon electrode (surface area = 0.071 cm 2 ).
触媒のシュウ酸酸化活性評価はエー・エル・エス製のポテンショスタット（ALS model 711B）を用いて行った。上記触媒を塗布したグラッシーカーボン電極を作用電極とし、白金電極を対極、Ag/AgCl/KCl(sat.)電極を参照電極として用いた。電解液としては0.1 M H2SO4を用いた。 Evaluation of the oxalic acid oxidation activity of the catalyst was performed using a potentiostat (ALS model 711B) manufactured by ALS. A glassy carbon electrode coated with the catalyst was used as a working electrode, a platinum electrode as a counter electrode, and an Ag / AgCl / KCl (sat.) Electrode as a reference electrode. As the electrolyte, 0.1 MH 2 SO 4 was used.
まず、シュウ酸のない条件でのロジウムフタロシアニンテトラスルホン酸の電気化学的特性を調べるために、測定前に不活性ガス（窒素またはアルゴン）を電解液に10分間吹き込んだ後、サイクリックボルタンメトリー（CV）測定を開始した。測定中は不活性ガスを溶液の上部に連続的に吹き付けることで、酸素の混入を防ぐようにした。ロジウムフタロシアニンテトラスルホン酸担持カーボンのCVを図４の曲線Ａとして示す。尚、図４の右図は、低電流分の拡大図である。 First, in order to investigate the electrochemical properties of rhodium phthalocyanine tetrasulfonic acid in the absence of oxalic acid, inert gas (nitrogen or argon) was blown into the electrolyte for 10 minutes before measurement, and then cyclic voltammetry (CV ) Measurement started. During the measurement, inert gas was continuously blown over the top of the solution to prevent oxygen contamination. The CV of the rhodium phthalocyanine tetrasulfonic acid-supported carbon is shown as curve A in FIG. 4 is an enlarged view of a low current.
次に、ロジウムフタロシアニンテトラスルホン酸のシュウ酸酸化触媒能を検討した。シュウ酸を10 mM加えたあと、サイクリックボルタンメトリー（CV）測定を開始した。シュ
ウ酸を加えた条件では0.33 V (Ag/AgCl/KCl(飽和)基準)付近から酸化電流が上昇しはじめており、シュウ酸の酸化が低い過電圧で進行していることがわかる（図４の曲線Ｂ）。さらにシュウ酸を0.5 Mになるように加えると、酸化電流は大きく上昇し、濃度に応じた応
答を示すことが確認できた（曲線C）。
Next, the ability of rhodium phthalocyanine tetrasulfonic acid to catalyze oxalic acid oxidation was examined. After adding 10 mM of oxalic acid, cyclic voltammetry (CV) measurement was started. Under the condition where oxalic acid was added, the oxidation current started to increase from around 0.33 V (Ag / AgCl / KCl (saturated) standard), indicating that the oxidation of oxalic acid proceeds at a low overvoltage (curve in Fig. 4). B). Further, when oxalic acid was added to 0.5 M, the oxidation current increased greatly, and it was confirmed that a response corresponding to the concentration was exhibited (curve C).
以上の結果から、ロジウムフタロシアニンテトラスルホン酸担持カーボン触媒は、シュウ酸の電気化学的酸化反応に対して高い活性を有することが明らかである。 From the above results, it is clear that the rhodium phthalocyanine tetrasulfonic acid-supported carbon catalyst has high activity for the electrochemical oxidation reaction of oxalic acid.
実施例３
シュウ酸センサの作製
実施例１と同様の方法でロジウムフタロシアニン担持カーボン触媒を塗布したグラッシーカーボン電極を作製した。この電極をシュウ酸センサ用作用電極として用い、白金電極を対極、Ag/AgCl/KCl(sat.)電極を参照電極として、以下の方法でシュウ酸濃度の測定を
行った。
Example 3
Preparation of Oxalic Acid Sensor A glassy carbon electrode coated with a rhodium phthalocyanine-supported carbon catalyst was prepared in the same manner as in Example 1. Using this electrode as the working electrode for the oxalic acid sensor, using the platinum electrode as the counter electrode and the Ag / AgCl / KCl (sat.) Electrode as the reference electrode, the oxalic acid concentration was measured by the following method.
まず、シュウ酸を含まない0.1 MのH2SO4溶液に、上記した作用電極を浸漬し、ビー・エー・エス社製の回転電極装置により3600 rpmで回転させて、Ag/AgCl/KCl(sat.)電極を基
準として0.5 Vの電圧を印加して電流値を測定した。
First, the working electrode described above was immersed in a 0.1 M H 2 SO 4 solution containing no oxalic acid, and rotated at 3600 rpm by a rotating electrode device manufactured by BAS, and Ag / AgCl / KCl ( The current value was measured by applying a voltage of 0.5 V with respect to the sat.) electrode.
次いで、この溶液に対して、シュウ酸を段階的に添加して、シュウ酸濃度を２６０秒後に１０μＭ、５００秒後に１００μＭ、８００秒後に２９０μＭ、１０６０秒後に５６６μＭ、１５００秒後に９００μＭ、１８００秒後に２．７ｍＭ、２１３０秒後に５．４ｍＭ、２４４５秒後に９ｍＭとして、電流値を測定した。 Next, oxalic acid was added stepwise to this solution, and the oxalic acid concentration was 10 μM after 260 seconds, 100 μM after 500 seconds, 290 μM after 800 seconds, 566 μM after 1660 seconds, 900 μM after 1500 seconds, and after 1800 seconds. The current value was measured as 2.7 mM, 5.4 mM after 2130 seconds, and 9 mM after 2445 seconds.
測定開始後の経過時間と、電流値との関係を図５のグラフに示す。また、図６は、シュウ酸濃度と電流値変化との関係を示すグラフである。図６の右図は、シュウ酸濃度１ｍＭまでの範囲についての測定結果の拡大図である。 The relationship between the elapsed time after the start of measurement and the current value is shown in the graph of FIG. FIG. 6 is a graph showing the relationship between the oxalic acid concentration and the current value change. The right figure of FIG. 6 is an enlarged view of the measurement results for a range up to an oxalic acid concentration of 1 mM.
図６から明らかなように、ロジウムフタロシアニン担持カーボン触媒を塗布したグラッシーカーボン電極を作用電極として一定電圧を印加することによって、シュウ酸濃度に対して電流値が線形の応答を示すことが判る。よって、ロジウムフタロシアニン担持カーボン触媒を用いた電極は、簡易な構造であって、シュウ酸濃度に対して良好な応答性を示すものであり、シュウ酸センサとして有用であることが確認できた。 As is apparent from FIG. 6, it can be seen that by applying a constant voltage using a glassy carbon electrode coated with a rhodium phthalocyanine-supported carbon catalyst as a working electrode, the current value shows a linear response to the oxalic acid concentration. Therefore, the electrode using the rhodium phthalocyanine-carrying carbon catalyst has a simple structure, shows a good response to the oxalic acid concentration, and was confirmed to be useful as an oxalic acid sensor.
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