JP2016203134A - Catalyst for the electrochemical oxidation of carbon monoxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel catalyst useful for the electrochemical oxidation reaction of carbon monoxide, suitable for use in an anode electrode of a fuel cell, an electrochemical carbon monoxide removal device, and the like.SOLUTION: A catalyst for the electrochemical oxidation of carbon monoxide has a rhodium tetra azaannulene complex represented by formula (1) as an active ingredient [R-Rindependently represent H, a halogen atom or an alkyl group].SELECTED DRAWING: None

Description

  The present invention relates to a catalyst for electrochemical oxidation of carbon monoxide.

  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. In a polymer electrolyte fuel cell, a Pt catalyst is mainly used as an anode catalyst. However, when hydrogen obtained by reforming natural gas, methanol, gasoline or the like is used as a fuel, it is generated by reforming. There is a problem that carbon monoxide is strongly adsorbed on Pt and greatly reduces the catalytic function.

  As a fuel electrode of such a low temperature fuel cell that is susceptible to catalyst poisoning by carbon monoxide, it is used for a fuel electrode having carbon monoxide resistance that uses a combination of a transition metal or its alloy and a specific organometallic complex. A catalyst or the like has been reported (for example, Patent Document 1). However, few catalysts have been reported that are effective for actively oxidizing and removing carbon monoxide.

  As a catalyst for oxidizing and removing such carbon monoxide and a catalyst used in the carbon monoxide removing apparatus, for example, rhodium porphyrin or a derivative thereof is known (for example, Patent Document 2). However, these rhodium porphyrins or derivatives thereof cannot be said to have a sufficiently low reaction overvoltage, and the catalytic activity for removing carbon monoxide by oxidation in a low potential region is not sufficient.

  On the other hand, as a gas sensor that electrically detects carbon monoxide, an ionization electrode and a reference electrode are connected to a proton conductor, and a proton current generated by an oxidation reaction of carbon monoxide at the ionization electrode is detected to detect a gas monoxide concentration. There is known a sensor having a structure for measuring (Patent Document 3). However, this gas sensor has a disadvantage that the detection sensitivity is inferior due to the high cost because a large amount of noble metal catalyst such as Pt is used as the ionization electrode and the overvoltage when oxidizing carbon monoxide is large. is there.

  Furthermore, in a method of removing carbon monoxide by contacting a gas containing carbon monoxide with a solution containing quinones, a rhodium porphyrin complex, a cobalt porphyrin complex, or the like is used as a catalyst for removing carbon monoxide. This is also known (for example, Patent Document 4). However, rhodium porphyrin complexes, cobalt porphyrin complexes, and the like have low reactivity, so that their catalytic activity for removing carbon monoxide is not sufficient.

JP 2002-329500 A Japanese Patent Application Laid-Open No. 2006-261086 JP-A-5-39509 International Publication No. 2012/165459

  The present invention has been made in view of the current state of the prior art as described above, and its main objects are an anode electrode of a fuel cell, a carbon monoxide sensor, an electrochemical carbon monoxide removal apparatus, a carbon monoxide. It is an object of the present invention to provide a novel catalyst effective for an electrochemical oxidation reaction of carbon monoxide, which is suitable for use in an apparatus for removing quinone with quinone.

The present inventor has intensively studied to achieve the above-described object. As a result, the rhodium tetraazaannulene complex has the reaction formula:
CO + H ₂ O → CO ₂ + 2H ⁺ + 2e ⁻
It was found to have a catalytic ability for the electrochemical carbon monoxide oxidation reaction indicated by Moreover, the present inventors have also found that the rhodium tetraazaannulene complex has a small reaction overvoltage and a high catalytic activity for removing carbon monoxide by oxidation. The present invention has been completed based on these findings. That is, the present invention includes the following configurations.

  Item 1. General formula (1):

[Wherein, R ^{1 to} R ² , R ^{7 to} R ⁹ and R ¹⁴ are the same or different and are each a hydrogen atom or an optionally substituted alkyl group; R ^{3 to} R ⁶ and R ^{10 to} R ¹³ are the same. Or a hydrogen atom, a halogen atom or an optionally substituted alkyl group, respectively; the dotted line is a coordination bond. ]
A catalyst for electrochemical oxidation of carbon monoxide containing a rhodium tetraazaannulene complex represented by

Item 2. Item 2. The catalyst for electrochemical oxidation of carbon monoxide according to item 1, wherein in the general formula (1), R ^{3 to} R ⁶ and R ^{10 to} R ¹³ are all hydrogen atoms.

Item 3. Item 3. The catalyst for electrochemical oxidation of carbon monoxide according to item 1 or 2, wherein in the general formula (1), R ^{1 to} R ² , R ^{7 to} R ^9, and R ¹⁴ are all hydrogen atoms.

  Item 4. Item 4. The catalyst for electrochemical oxidation of carbon monoxide according to any one of Items 1 to 3, wherein the rhodium tetraazaannulene complex is supported on a conductive carrier.

  Item 5. Item 5. The catalyst for electrochemical oxidation of carbon monoxide according to Item 4, wherein the conductive support is carbon black.

  Item 6. Item 6. An anode for a polymer electrolyte fuel cell, comprising the catalyst for electrochemical oxidation of carbon monoxide according to any one of Items 1 to 5 and an anode catalyst material.

  Item 7. A solid polymer fuel cell using carbon monoxide as a fuel, comprising the anode electrode according to Item 6 as a constituent element.

  Item 8. Item 6. A carbon monoxide sensor comprising the carbon monoxide electrochemical oxidation catalyst according to any one of items 1 to 5 as a carbon monoxide oxidation catalyst component in a carbon monoxide detector.

  Item 9. Any one of Items 1 to 5 as a catalyst for oxidizing carbon monoxide in a working electrode in a carbon monoxide oxidation removing apparatus in an anode gas for a polymer electrolyte fuel cell, including an electrolyte, a working electrode, a counter electrode, and a power supply device An apparatus for removing oxidization of carbon monoxide in an anode gas comprising the catalyst for electrochemical oxidation of carbon monoxide.

  Item 10. Item 6. A closed container containing a solution containing the catalyst for electrochemical oxidation of carbon monoxide and quinones according to any one of Items 1 to 5, and gas introduction for introducing a gas containing carbon monoxide into the solution. An oxygen-containing gas inlet for introducing a gas containing oxygen into the solution, an oxygen-containing gas outlet, and a gas outlet for discharging the gas from which carbon monoxide has been removed. Carbon oxide removal device.

  Item 11. Item 6. A closed container containing a solution containing the catalyst for electrochemical oxidation of carbon monoxide and quinones according to any one of Items 1 to 5, and gas introduction for introducing a gas containing carbon monoxide into the solution. An apparatus for removing carbon monoxide, comprising an opening, a gas discharge port for discharging the gas from which carbon monoxide has been removed to the outside of the container, a working electrode, and a counter electrode.

Item 12. A fuel regenerative fuel cell comprising a solid polymer fuel cell using a reductant of quinones as a fuel, and a fuel regenerating device for converting quinones into a reductant,
The fuel regeneration apparatus includes a sealed container that contains a solution containing the catalyst for electrochemical oxidation of carbon monoxide according to any one of Items 1 to 5, and a solution containing quinones after an anode reaction in a fuel cell. A fuel cell comprising a supply port for feeding into the vessel, a gas inlet for introducing carbon monoxide into the solution, a gas outlet for discharging a gas containing carbon dioxide from the vessel, and a reductant of quinones A fuel cell comprising a fuel supply port for supplying to the fuel cell.

  Item 13. Item 6. A catalyst for oxidizing carbon monoxide, comprising the catalyst for electrochemical oxidation of carbon monoxide according to any one of Items 1 to 5 as an active ingredient, and a quinone as an electron acceptor.

  According to the catalyst for electrochemical oxidation of carbon monoxide of the present invention, since the rhodium tetraazaannulene complex is used, carbon monoxide can be efficiently oxidized with a low overvoltage.

  In addition, when the conductive support is carbon black, the rhodium tetraazaannulene complex can be dispersed and supported in a state close to atomic units, so that the amount of catalyst metal used can be greatly reduced and inexpensive. And a catalyst for electrochemical oxidation of carbon monoxide with high activity.

It is the schematic of a carbon monoxide oxidation removal apparatus. It is a linear sweep voltammogram of the rhodium tetraazaannulene complex carrying | support carbon catalyst obtained in Example 1 (curve A) and Example 2 (curve B). 4 is a linear sweep voltammogram of a rhodium dibenzotetraazaannulene-supported platinum ruthenium catalyst obtained in Example 3. FIG.

  The catalyst for electrochemical oxidation of carbon monoxide of the present invention has the general formula (1):

[Wherein, R ^{1 to} R ² , R ^{7 to} R ⁹ and R ¹⁴ are the same or different and are each a hydrogen atom or an optionally substituted alkyl group; R ^{3 to} R ⁶ and R ^{10 to} R ¹³ are the same. Or a hydrogen atom, a halogen atom or an optionally substituted alkyl group, respectively; the dotted line is a coordination bond. ]
A rhodium tetraazaannulene complex represented by the formula:

The rhodium tetraazaannulene complex represented by the general formula (1) has a reaction formula:
CO + H ₂ O → CO ₂ + 2H ⁺ + 2e ⁻
It has an excellent activity for the electrochemical oxidation reaction of carbon monoxide represented by Therefore, it is possible to efficiently oxidize carbon monoxide with a low overvoltage by electrochemically oxidizing carbon monoxide in the presence of the rhodium tetraazaannulene complex.

In the general formula (1), the alkyl group represented by R ^{1 to} R ² , R ^{7 to} R ⁹ and R ¹⁴ is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, Lower alkyl groups such as n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, and n-hexyl group (particularly linear having 1 to 10 carbon atoms, particularly about 1 to 6 carbon atoms) Branched alkyl group). Moreover, this alkyl group may be substituted by 0-6 pieces (especially 0-3 pieces), such as a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, etc.), for example.

In general formula (1), as R < ¹ > -R < ² >, R < ⁷ > -R < ⁹ > and R < ¹⁴ >, all are a hydrogen atom from a viewpoint which can oxidize carbon monoxide with a lower overvoltage.

In the general formula (1), the halogen atom represented by R ^{3 to} R ⁶ and R ^{10 to} R ¹³ is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, and a bromine atom.

In the general formula (1), the alkyl group represented by R ^{3 to} R ⁶ and R ^{10 to} R ¹³ is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and n-butyl. Group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group and other lower alkyl groups (particularly linear or branched having 1 to 10 carbon atoms, especially 1 to 6 carbon atoms) Alkyl group). Moreover, this alkyl group may be substituted by 0-6 pieces (especially 0-3 pieces), such as a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, etc.), for example.

In general formula (1), as R < ³ > -R < ⁶ > and R < ¹⁰ > -R < ¹³ >, all are a hydrogen atom or the alkyl group which may be substituted from a viewpoint which can oxidize carbon monoxide with a lower overvoltage. Are preferable, and a hydrogen atom is more preferable.

  Examples of rhodium tetraazaannulene complexes that satisfy the above conditions include:

Etc.

  The rhodium tetraazaannulene complex represented by the general formula (1) has the general formula (2):

[Wherein, R ^{1 to} R ¹⁴ and the dotted line are the same as above. ]
It can obtain by forming a chelate with the tetraazaannulene compound represented by these, and a rhodium atom.

  Specifically, for example, it can be synthesized according to the method described in Inorganica Chimica Acta 25 (1977) 215-218. That is, the target rhodium tetraazaannulene complex can be obtained by reacting the tetraazaannulene compound represented by the general formula (2) with a salt or complex of rhodium in an organic solvent. Specifically, the tetraazaannulene compound represented by the general formula (2) and a rhodium salt, complex, etc. are dissolved or dispersed in an organic solvent, followed by heat treatment, and purification treatment as necessary. To give the intended rhodium tetraazaannulene complex.

Salts of rhodium is not particularly limited as complex, from the viewpoint of yield, rhodium tetracarbonyl dichloride _{(Rh 2 Cl 2 (CO)} 4), rhodium chloride (RhCl _3), six rhodium hexadecanol carbonyl (Rh ₆ ( CO) ₁₆ ) and the like are preferable, and rhodium tetracarbonyl dichloride (Rh ₂ Cl ₂ (CO) ₄ ) is more preferable.

  The amount of rhodium salt, complex, etc. used is not particularly limited, but from the viewpoint of yield and the like, the number of rhodium atoms is preferably 1.0 to 2.0 moles with respect to 1 mole of the tetraazaannulene compound. 0.0 to 1.5 mol is more preferable.

  The organic solvent to be used is not particularly limited as long as both the tetraazaannulene compound and the rhodium salt, complex, etc. are dissolved, but toluene, ethanol, methanol, dichloromethane and the like are preferable from the viewpoint of yield and the like. Of these, toluene is particularly desirable.

  Although there will be no restriction | limiting in particular if heating temperature is lower than the boiling point of an organic solvent, From viewpoints, such as a yield, about 30-150 degreeC is preferable, for example, and about 80-120 degreeC is more preferable.

  The heating time may be a time during which the reaction proceeds sufficiently and is not particularly limited, but is preferably about 10 minutes to 24 hours, and more preferably about 30 minutes to 5 hours.

  The rhodium tetraazaannulene complex represented by the general formula (1) of the present invention can be favorably dispersed by supporting the rhodium tetraazaannulene complex on a conductive carrier, thereby effectively utilizing the complex. In addition, it is considered that the electron transfer between the complex and the electrode can be rapidly performed by supporting the conductive carrier. Therefore, the overvoltage of the electrochemical oxidation reaction of carbon monoxide can be made smaller, and the catalytic activity of the electrochemical oxidation reaction of carbon monoxide can be made higher. This seems to be because the rhodium tetraazaannulene complex is strongly adsorbed and supported on the carrier by the interaction with the conductive carrier.

  The conductive carrier is not particularly limited. For example, a catalyst carrier for a polymer electrolyte fuel cell, a carbon monoxide sensor, an electrochemical carbon monoxide removing device, a device for removing carbon monoxide with quinone, etc. Various carriers used in the above can be used. Specific examples of such a conductive carrier include carbonaceous materials such as carbon black (Ketjen black, furnace black, acetylene black, etc.), activated carbon, and graphite. Among these, carbon black (particularly ketjen black) has a large interaction with the rhodium tetraazaannulene complex represented by the general formula (1) and has a strong function of dispersing and supporting the rhodium tetraazaannulene complex. It is a particularly preferable substance as a conductive carrier because of its excellent conductivity and large specific surface area.

The shape and the like of the conductive carrier are not particularly limited. For example, the average primary particle diameter is preferably about 10 to 1000 nm, and more preferably about 1 to 50 nm. In the case of using carbon black as the conductive support, for example, specific surface area by BET method is preferably about ^{50~1600m 2 / g, 100~1200m 2 /} g approximately and more preferably. As specific examples of such carbon black, for example, ketjen black, Vulcan XC-72R (manufactured by Cabot) and the like can be used.

  As a method for supporting the rhodium tetraazaannulene complex on the conductive carrier, for example, a known method such as a dissolution drying method or a gas phase method can be employed.

  For example, in the dissolution drying method, the rhodium tetraazaannulene complex is adsorbed on the conductive support by dissolving the rhodium tetraazaannulene complex in an organic solvent, adding a conductive support to this solution, and stirring as necessary. Then, the organic solvent is dried as necessary. Even when a large amount of rhodium tetraazaannulene complex is contained in the organic solvent, the rhodium tetraazaannulene complex is adsorbed on the conductive support until equilibrium is reached, and is then adsorbed on the conductive support by filtration. The rhodium tetraazaannulene complex can be removed, leaving only the rhodium tetraazaannulene complex interacting with the conductive support on the surface of the conductive support.

  In this method, any organic solvent can be used without particular limitation as long as it can dissolve the rhodium tetraazaannulene complex. For example, toluene, ethanol, methanol, dichloromethane, chloroform, acetone, isopropanol and the like can be suitably used.

  If the dispersion obtained by filtration is further washed with an organic solvent until the washing liquid becomes transparent, the rhodium tetraazaannulene complex having a weak interaction with the conductive carrier can be washed away, and the conductive carrier is firmly attached. A highly active catalyst containing only the rhodium tetraazaannulene complex adsorbed on the catalyst can be obtained.

  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 heat vapor deposition method can be adopted.

  The amount of the rhodium tetraazaannulene complex supported on the conductive carrier is not particularly limited. For example, about 0.001 to 0.8 g of rhodium tetraazaannulene complex with respect to 1 g of the conductive carrier, especially 0 It is preferable to carry about 0.003 to 0.6 g.

  The method for supporting the rhodium tetraazaannulene complex on the conductive carrier is not limited to the above method. For example, the tetraazaannulene compound represented by the general formula (2) is supported on the conductive carrier. Then, a chelate may be formed by the tetraazaannulene compound and a rhodium atom. As a method of supporting the tetraazaannulene compound on the conductive carrier, the above-described solution drying method, gas phase method, or the like can be employed. Specifically, the tetraazaannulene compound can be supported on the conductive carrier according to the method described above except that a tetraazaannulene compound is used instead of the rhodium tetraazaannulene complex. Thereafter, a chelate can be formed by a rhodium atom and a tetraazaannulene compound supported on a conductive carrier according to the method described in Inorganica Chimica Acta 25 (1977) 215-218.

  The catalyst for electrochemical oxidation of carbon monoxide of the present invention comprising the rhodium tetraazaannulene complex represented by the general formula (1) as an active ingredient can oxidize oxygen monoxide with high selectivity. Since it is difficult to be poisoned by carbon monoxide, it can be used for various applications that require such characteristics.

  For example, in a polymer electrolyte fuel cell fueled with hydrogen gas containing carbon monoxide obtained by reforming natural gas, methanol, gasoline, etc., carbon monoxide is selected by using it in combination with an anode catalyst material. Thus, an anode having excellent carbon monoxide poisoning resistance can be obtained.

  As the anode catalyst material in the anode electrode in this case, for example, a known catalyst such as platinum can be used. The ratio of the carbon monoxide electrochemical oxidation catalyst and the anode catalyst material of the present invention is not particularly limited. For example, the ratio is suitably determined from the range of about 1 to 500 parts by weight with respect to 100 parts by weight of the former. That's fine. The catalyst for electrochemical oxidation of carbon monoxide and the anode catalyst material may be supported on separate conductive carriers, or may be supported on the same carrier. In the case of supporting on the same carrier, for example, a method of further supporting a rhodium tetraazaannulene complex by a variety of methods described above on a carrier supporting a catalyst material such as platinum, or supporting a rhodium tetraazaannulene complex. A method of further supporting a catalytic substance such as platinum on the supported carrier can be applied.

  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.

  In addition, the carbon monoxide electrochemical oxidation catalyst of the present invention can be used, for example, as a sensor for detecting carbon monoxide using an electrode reaction. In this case, a sensor including the catalyst of the present invention as a carbon monoxide oxidation catalyst is used, and detection methods include a method of detecting a current generated by an oxidation reaction of carbon monoxide, a method of detecting a potential difference, and a proton. A detection method or the like can be employed. For example, like the sensor in the gas detector described in Japanese Patent Publication No. 5-39509, an ionization electrode for oxidizing carbon monoxide by an electrode reaction to generate protons, a proton conductor, and a proton conductor A proton conductor gas sensor having a reference electrode for receiving protons from the gas, reacting with oxygen in the atmosphere and discharging it as water can be obtained. In the gas sensor having such a structure, the catalyst of the present invention can be used as a catalyst for oxidizing carbon monoxide in the ionization electrode.

  In addition, the catalyst for electrochemical oxidation of carbon monoxide of the present invention is, for example, a solid polymer fuel cell using a reformed gas obtained by reforming natural gas, methanol, gasoline or the like as an anode gas. In the above, before supplying the anode gas to the fuel cell, the carbon monoxide contained in the anode gas can be used as a catalyst for oxidizing carbon monoxide in a carbon monoxide oxidation removing apparatus for oxidizing and removing carbon monoxide by electrolysis. Such a carbon monoxide oxidation removal device has, for example, an electrolytic solution, a working electrode, a counter electrode, and a power supply device as basic components.

  A schematic diagram of the carbon monoxide removal apparatus is shown in FIG. The carbon monoxide oxidation removal apparatus can basically have the same structure as that of various ordinary electrolysis apparatuses. As the electrolytic solution, for example, a sulfuric acid solution of about 0.1 to 1M can be used. The catalyst of the present invention is used as a catalyst for oxidizing carbon monoxide 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 supply (potentiostat) or the like 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.

  In the carbon monoxide oxidation removing apparatus, for example, an anode gas is bubbled into the electrolyte solution by a method such as bubbling, and a positive voltage is applied to the working electrode with respect to the reference electrode using a constant voltage power source (potentiostat) during the ventilation. By applying, carbon monoxide contained in the anode gas can be electrochemically oxidized with high selectivity. At this time, by using the catalyst of the present invention as a working electrode catalyst, carbon monoxide can be electrochemically oxidized at a low overvoltage without oxidizing the fuel gas, and the anode gas can be purified. Become. By supplying the exhaust gas from the carbon monoxide oxidation removal apparatus to the polymer electrolyte fuel cell, it is possible to supply high purity hydrogen gas to the fuel cell.

  In addition, the catalyst for electrochemical oxidation of carbon monoxide of the present invention, for example, oxidizes carbon monoxide by bringing a gas containing carbon monoxide to be treated into contact with a solution containing quinones. Thus, the carbon monoxide concentration can be reduced. The removal device that can be used at this time is, for example, a closed container that contains a solution containing a rhodium tetraazaannulene complex and quinones, and a gas containing carbon monoxide (for example, a reformed gas) in the solution. A gas introduction port, an oxygen-containing gas introduction port for introducing a gas containing oxygen (for example, air) into the solution, an oxygen-containing gas discharge port, and a gas from which carbon monoxide has been removed, for example, A gas outlet for supplying the fuel cell is provided. In this apparatus, a gas containing carbon monoxide (reformed gas) is introduced from the gas inlet with the oxygen-containing gas inlet and the oxygen-containing gas outlet closed, and the rhodium tetraazaannulene complex and quinones are introduced. By allowing the gas to pass through the solution containing carbon monoxide contained in the gas, it can be oxidized and removed. The gas (reformed gas) that has passed through the solution can be discharged from the gas outlet to the outside of the container and supplied to the fuel cell as anode gas, for example. Examples of such a treatment method and treatment apparatus include the method and apparatus described in International Publication No. 2012/165459, and the description of the publication describes a rhodium tetraazaannulene complex instead of a rhodium porphyrin complex, a cobalt porphyrin complex, or the like. It can be applied as it is except for using.

  Hereinafter, the present invention will be described in more detail with reference to production examples and examples. In the following examples, the ligands (dihydrodibenzotetraazaannulene and dihydrodibenzodimethyltetraazaannulene) were synthesized according to a report (Chemistry of Heterocyclic Compounds, vol 23, pp316-320).

Production Example 1: Rhodium dibenzotetraazaannulene (C ₁₈ H ₁₄ N _Four Synthesis of Rh: molecular weight 389)

  In toluene (70 mL), the following formula:

Dihydrodibenzotetraazaannulene (20.3 mg, 0.070 mmol) and rhodium tetracarbonyl dichloride (Rh ₂ Cl ₂ (CO) ₄ ; 15.3 mg, 0.039 mmol) were added, and the solution was stirred at 60 ° C. for 3.5 hours. . Further, the temperature was raised to 100 ° C. and stirred for 1.5 hours. When ASAP-MS (atmospheric pressure solid sample analysis probe mass spectrometry) of this reaction solution is measured, the peak of m / z 389 which is the molecular ion of the product and m / z 390 which is the ion of the product molecule + H, the product M / z 391, which is a molecule + 2H ion, was observed, confirming the synthesis of the target product.

Production Example 2: Rhodium dibenzodimethyltetraazaannulene (C ₂₀ H ₁₈ N _Four Synthesis of Rh: molecular weight 417)

  In toluene (50 mL), the following formula:

Add dihydrodibenzodimethyltetraazaannulene (10.4 mg, 0.033 mmol) and rhodium tetracarbonyl dichloride (Rh ₂ Cl ₂ (CO) ₄ ; 7.8 mg, 0.020 mmol), and stir the solution at 100 ° C. for 1 hour. did. When ESI-MS of this reaction solution was measured, the peak of m / z 417, which is the molecular ion of the product, was observed, confirming the synthesis of the target product.

Example 1: Preparation of rhodium dibenzotetraazaannulene-supported carbon catalyst 35 ml of rhodium dibenzotetraazaannulene solution obtained in Production Example 1 (rhodium dibenzotetraazaannulene complex: 14 mg) was added to carbon black (Ketjen black; average 30 mg of primary particle size: 40 nm, specific surface area: 800 m ² / g) was added. After sealing the container, dispersibility was improved by placing it in an ultrasonic cleaner for 1 minute.

  The solution in which the ketjen black was suspended was stirred with a magnetic stirrer for 3 hours, and then the solvent was removed by suction filtration using a membrane filter (pore size: 1.0 μm, manufactured by Toyo Roshi Kaisha, Ltd.). The carbon black on the membrane filter was recovered to obtain a rhodium dibenzotetraazaannulene-supported carbon catalyst.

Evaluation of electrochemical carbon monoxide oxidation activity of rhodium dibenzotetraazaannulene-supported carbon catalyst 0.5 mL of a mixed solvent (water: ethanol = 1: 1) of 5 mg of rhodium dibenzotetraazaannulene-supported carbon catalyst obtained by the above method After 5 μL of 5% Nafion solution (Aldrich) was added. This suspension was placed in an ultrasonic cleaner for 5 minutes to be well dispersed, and then 2 μL was placed on a rotating disk electrode (surface area 0.0707 cm ² ) and dried.

The carbon monoxide oxidation activity of the catalyst was evaluated using a potentiostat (ALS model 711B) manufactured by BAS. The rotational speed was controlled using a rotational speed control device (BAS RDE-1) manufactured by BAS Co., Ltd. A glassy carbon rotating disk electrode coated with a catalyst was used as a working electrode, a platinum electrode as a counter electrode, and a reversible hydrogen electrode as a reference electrode. As the electrolyte, 0.1 MH ₂ SO ₄ was used. The measurement was performed at 55 ° C. However, the reversible hydrogen electrode was installed at room temperature.

  After carbon monoxide gas was blown into the electrolytic cell for 7 minutes, a linear sweep voltammogram (LSV) was measured while rotating the electrode at 6400 rpm. This LSV is shown as “Example 1” in FIG. An increase in oxidation current is observed, indicating that CO is electrochemically oxidized by the catalytic action of the rhodium dibenzotetraazaannulene complex. Under carbon monoxide saturation, the oxidation current starts to increase from around -0.01 V (reversible hydrogen electrode reference), indicating that the oxidation of carbon monoxide proceeds at a low overvoltage. The voltage at 5 μA is 1 mV, the current value at 0.1 V is 181 μA, and the voltage at 5 μA is low compared to Comparative Examples 1 to 3, and the current value at 0.1 V is high. This also shows that the oxidation activity of carbon monoxide is high and the reaction proceeds at a low overvoltage.

Example 2: Production of rhodium dibenzodimethyltetraazaannulene-supported carbon catalyst 40 ml of a rhodium dibenzodimethyltetraazaannulene solution obtained in Production Example 2 (rhodium dibenzodimethyltetraazaannulene complex: 11 mg) was added to carbon black (Ketjen). Black; average primary particle diameter: 40 nm, specific surface area: 800 m ² / g) was added in an amount of 30 mg. After sealing the container, dispersibility was improved by placing it in an ultrasonic cleaner for 1 minute.

  The solution in which the ketjen black was suspended was stirred with a magnetic stirrer for 3 hours, and then the solvent was removed by suction filtration using a membrane filter (pore size: 1.0 μm, manufactured by Toyo Roshi Kaisha, Ltd.). The carbon black on the membrane filter was recovered to obtain a rhodium dibenzodimethyltetraazaannulene-supported carbon catalyst.

Evaluation of electrochemical carbon monoxide oxidation activity of rhodium dibenzodimethyltetraazaannulene-supported carbon catalyst The catalytic activity was evaluated in the same manner as in Example 1. After carbon monoxide gas was blown into the electrolytic cell for 7 minutes, a linear sweep voltammogram (LSV) was measured while rotating the electrode at 6400 rpm. This LSV is shown as “Example 2” in FIG. An increase in oxidation current was observed, indicating that CO was electrochemically oxidized by the catalytic action of rhodium dibenzodimethyltetraazaannulene complex. Under carbon monoxide saturation, the oxidation current starts to increase from around 0.02 V (reversible hydrogen electrode reference), indicating that the oxidation of carbon monoxide proceeds at a low overvoltage. The voltage at 5 μA is 39 mV, the current value at 0.1 V is 59.3 μA, and the voltage at 5 μA is low compared to Comparative Examples 1 to 3, and the current value at 0.1 V is From the fact that it is high, it can be seen that the oxidation activity of carbon monoxide is high and the reaction proceeds at a low overvoltage.

Comparative Example 1 Production of Rhodium Tetracarboxyphenylporphyrin-Supported Carbon Catalyst A rhodium tetracarboxyphenylporphyrin-supported carbon catalyst was obtained according to Example 2 of JP 2008-036539 A.

Evaluation of electrochemical carbon monoxide oxidation activity of rhodium tetracarboxyphenylporphyrin-supported carbon catalyst The catalytic activity was evaluated in the same manner as in Example 1. After carbon monoxide gas was blown into the electrolytic cell for 7 minutes, a linear sweep voltammogram (LSV) was measured while rotating the electrode at 6400 rpm. This LSV is shown as “Comparative Example 1” in FIG. Under carbon monoxide saturation, the oxidation current started to increase from around 0.05 V (based on the reversible hydrogen electrode), indicating that the overvoltage of carbon monoxide oxidation is large and the oxidation activity of carbon monoxide is lower than in Examples 1-2. Has been. The voltage at 5 μA is 110 mV and the current value at 0.1 V is 3.6 μA. Compared with Examples 1 and 2, the voltage at 5 μA is high and the current value at 0.1 V is The low value also indicates that the oxidation activity of carbon monoxide is low and the overvoltage is large.

Comparative Example 2: Production of rhodium deuteroporphyrin disulfonic acid-supported carbon catalyst According to Example 7 of JP-A-2009-214092, a rhodium deuteroporphyrin disulfonic acid-supported carbon catalyst was obtained.

  Evaluation of catalyst activity was performed in the same manner as in Example 1. After carbon monoxide gas was blown into the electrolytic cell for 7 minutes, a linear sweep voltammogram (LSV) was measured while rotating the electrode at 6400 rpm. Under carbon monoxide saturation, the voltage at 5 μA is 43 mV, the current value at 0.1 V is 49.8 μA, and the voltage at 5 μA is higher than that of Examples 1 and 2, when the voltage is 0.1 V. Since the current value is low, it can be seen that the oxidation activity of carbon monoxide is low and the overvoltage is large.

Comparative Example 3: Production of rhodium hematoporphyrin- supported carbon catalyst A rhodium hematoporphyrin-supported carbon catalyst was obtained according to Example 1 of JP-A-2009-214092.

  Evaluation of catalyst activity was performed in the same manner as in Example 1. After carbon monoxide gas was blown into the electrolytic cell for 7 minutes, a linear sweep voltammogram (LSV) was measured while rotating the electrode at 6400 rpm. Under carbon monoxide saturation, the voltage at 5 μA is 86 mV, the current value at 0.1 V is 15.1 μA, and the voltage at 5 μA is higher than that of Examples 1 and 2, and is 0.1 V. Since the current value is low, it can be seen that the oxidation activity of carbon monoxide is low and the overvoltage is large.

  The results are shown in Table 1.

Example 3: Preparation of rhodium dibenzotetraazaannulene-supported platinum ruthenium catalyst In ruthenium dibenzotetraazaannulene solution 34 mL (rhodium dibenzotetraazaannulene complex: 6 mg) obtained in Production Example 1, platinum ruthenium-supported carbon (Tanaka noble metal) 30 mg of TEC61E54 manufactured by Kogyo Co., Ltd. was added. After sealing the container, dispersibility was improved by placing it in an ultrasonic cleaner for 1 minute.

  This suspension was stirred with a magnetic stirrer for 3 hours, and then the solvent was removed by suction filtration using a membrane filter (pore size: 1.0 μm, manufactured by Toyo Roshi Kaisha, Ltd.). The powder on the membrane filter was collected to obtain a rhodium dibenzotetraazaannulene-supported platinum ruthenium catalyst.

Evaluation of CO resistance of rhodium dibenzotetraazaannulene-supported platinum ruthenium catalyst After suspending 5 mg of rhodium dibenzotetraazaannulene-supported platinum ruthenium catalyst in the above method in a mixed solvent (water 1.8 mL and ethanol 1.2 mL), 59 μL of 5% Nafion solution (Aldrich) was added. This suspension was placed in an ultrasonic cleaner for 5 minutes to be well dispersed, and then 2 μL was placed on a rotating disk electrode (surface area 0.0707 cm ² ) and dried.

The CO resistance of the catalyst was evaluated using a potentiostat (ALS model 711B) manufactured by BAS. The rotational speed was controlled using a rotational speed control device (BAS RRDE-3A) manufactured by BAS Co., Ltd. A glassy carbon rotating disk electrode coated with a catalyst was used as a working electrode, a platinum electrode as a counter electrode, and a reversible hydrogen electrode as a reference electrode. 0.1 M HClO ₄ was used as the electrolyte. The measurement was performed at 55 ° C. However, the reversible hydrogen electrode was installed at room temperature.

  While maintaining the electrode potential at 0.05 V, hydrogen gas containing 2% CO was blown into the electrolysis cell for 700 seconds, and then the linear sweep voltammogram (LSV) was measured while rotating the electrode at 3600 rpm. This LSV is shown as “Example 3” in FIG. Meanwhile, the LSV of platinum ruthenium-supported carbon (TEC61E54 manufactured by Tanaka Kikinzoku Co., Ltd.) measured under the same conditions is shown as “platinum ruthenium” in FIG. By carrying the complex, the oxidation current greatly increases in the potential region of 0.15 V to 0.4 V. From this result, it can be seen that the rhodium dibenzotetraazaannulene complex enhances the CO resistance of the platinum ruthenium catalyst of the anode electrode for fuel cells.

Example 4: CO removal reaction using quinone with rhodium dibenzotetraazaannulene-supported carbon catalyst 0.5 mg of rhodium dibenzotetraazaannulene-supported carbon catalyst obtained in Production Example 1 and 20.6 mg of anthraquinone-2,7-sulfonic acid were added to a vial. Added to 5 mL of 0.1 M sulfuric acid in a bottle. The vial was sealed. This solution was purged with argon for 3 minutes, and the gas in the solution was replaced with hydrogen gas containing 2% carbon monoxide. The vial containing this solution was left in a 60 ° C. water bath for 1 hour, and then the gas phase above the solution was analyzed by a gas chromatograph.

  It was found that the carbon monoxide concentration in the gas phase decreased from 2% to 0.24%, and the CO concentration decreased due to the reaction with quinone.

Claims (13)

General formula (1):

[Wherein, R ^{1 to} R ² , R ^{7 to} R ⁹ and R ¹⁴ are the same or different and are each a hydrogen atom or an optionally substituted alkyl group; R ^{3 to} R ⁶ and R ^{10 to} R ¹³ are the same. Or a hydrogen atom, a halogen atom or an optionally substituted alkyl group, respectively; the dotted line is a coordination bond. ]
A catalyst for electrochemical oxidation of carbon monoxide containing a rhodium tetraazaannulene complex represented by The catalyst for electrochemical oxidation of carbon monoxide according to claim 1, wherein in the general formula (1), R ^{3 to} R ⁶ and R ^{10 to} R ¹³ are all hydrogen atoms. The catalyst for electrochemical oxidation of carbon monoxide according to claim 1 or 2, wherein in the general formula (1), R ^{1 to} R ² , R ^{7 to} R ⁹ and R ¹⁴ are all hydrogen atoms. The catalyst for electrochemical oxidation of carbon monoxide according to any one of claims 1 to 3, wherein the rhodium tetraazaannulene complex is supported on a conductive carrier. The catalyst for electrochemical oxidation of carbon monoxide according to claim 4, wherein the conductive support is carbon black. An anode for a polymer electrolyte fuel cell, comprising the catalyst for electrochemical oxidation of carbon monoxide according to claim 1 and an anode catalyst material. A polymer electrolyte fuel cell using carbon monoxide as a fuel, comprising the anode electrode according to claim 6 as a constituent element. A carbon monoxide sensor comprising the catalyst for electrochemical oxidation of carbon monoxide according to any one of claims 1 to 5 as a catalyst component for oxidation of carbon monoxide in a carbon monoxide detector. In the carbon monoxide oxidation removal apparatus in the anode gas for a polymer electrolyte fuel cell including an electrolytic solution, a working electrode, a counter electrode, and a power supply device, as a catalyst for oxidizing carbon monoxide in the working electrode, The carbon monoxide oxidation removal apparatus in anode gas containing the catalyst for the electrochemical oxidation of the carbon monoxide in any one. A closed vessel containing a solution containing the catalyst for electrochemical oxidation of carbon monoxide and quinones according to any one of claims 1 to 5, and a gas for introducing a gas containing carbon monoxide into the solution An inlet, an oxygen-containing gas inlet for introducing a gas containing oxygen into the solution, an oxygen-containing gas outlet, and a gas outlet for discharging the gas from which carbon monoxide has been removed. Carbon monoxide removal equipment. A closed vessel containing a solution containing the catalyst for electrochemical oxidation of carbon monoxide and quinones according to any one of claims 1 to 5, and a gas for introducing a gas containing carbon monoxide into the solution An apparatus for removing carbon monoxide, including an introduction port, a gas discharge port for discharging the gas from which carbon monoxide has been removed to the outside of the container, a working electrode, and a counter electrode. A fuel regenerative fuel cell comprising a solid polymer fuel cell using a reductant of quinones as a fuel, and a fuel regenerating device for converting quinones into a reductant,
A solution containing a closed container containing a solution containing the catalyst for electrochemical oxidation of carbon monoxide according to any one of claims 1 to 5 and a quinone after an anode reaction in a fuel cell. A gas supply port for introducing carbon monoxide into the solution, a gas outlet for discharging a gas containing carbon dioxide from the vessel, and a quinone reductant as fuel A fuel cell comprising a fuel supply port for supplying the battery. A catalyst for the oxidation of carbon monoxide, comprising the catalyst for electrochemical oxidation of carbon monoxide according to any one of claims 1 to 5 as an active ingredient and a quinone as an electron acceptor.

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