JP4506429B2 - Method for recovering activity of carbon monoxide removal catalyst, method for operating fuel cell power generator, and method for operating hydrogen generator - Google Patents

Description

  The present invention relates to a method for recovering the activity of a carbon monoxide removal catalyst used for removing carbon monoxide gas from a reformed gas containing hydrogen as a main component obtained by reforming a hydrocarbon compound. The present invention relates to an operating method of the used fuel cell power generator and hydrogen generator.

  Hydrogen is expected as clean energy, and its use is being studied in various industrial fields. For example, in a fuel cell, a pair of electrodes are arranged with an electrolyte layer in between, a fuel gas containing hydrogen is supplied to one electrode (anode side), and an oxidizing gas containing oxygen is supplied to the other electrode (cathode side) Is a power generation system that obtains an electromotive force by utilizing an electrochemical reaction that occurs between both electrodes, and can achieve high energy efficiency, and air pollutants such as nitrogen oxides NOx and sulfur oxides SOx Is expected to be used as a clean energy supply method.

  Fuel cells are classified according to the type of electrolyte used. Among them, solid polymer fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, etc. It is possible to use oxidant gas or carbon dioxide gas that is contained. Usually, in these fuel cells, air is used as the oxidant gas, and hydrogen produced by steam reforming a hydrocarbon-based raw fuel such as natural gas is used. Gas containing is used as fuel gas.

  Therefore, a fuel cell power generation apparatus including such a fuel cell is provided with a hydrogen generator having a reformer and the like, and a desulfurizer and a steam reformer in which raw fuel such as natural gas is continuously connected. Thus, desulfurization and steam reforming are performed to obtain a reformed gas containing hydrogen as a main component and containing carbon monoxide, carbon dioxide, moisture and the like.

  The following equation (1) is a reforming reaction in the reformer when the raw fuel is methane.

CH ₄ + H ₂ O → CO + 3H ₂ ΔH = + 206.14 KJ / mol (1)
As shown in the equation (1), since the reforming reaction is an endothermic reaction, a heater such as a burner for heating the reformer from the outside is usually installed in the reformer.

  In the case of a high-temperature type fuel cell such as a molten carbonate type, carbon monoxide contained in the reformed gas can also be used as a fuel. However, in a phosphoric acid fuel cell having a relatively low operating temperature, the electrode catalyst is poisoned by carbon monoxide, the performance is deteriorated, and the power generation efficiency is lowered. Therefore, for phosphoric acid fuel cells with low operating temperatures, reformed gas is introduced into a carbon monoxide converter, and carbon monoxide is converted to carbon dioxide by a carbon monoxide conversion reaction. Carbon monoxide is reduced to about 1.0%, and a reformed gas with reduced carbon monoxide is used.

  Since the poisoning of the electrocatalyst by carbon monoxide tends to occur at lower temperatures, the polymer electrolyte fuel cell, which has a lower operating temperature than the phosphoric acid fuel cell, is poisoned by a small amount of carbon monoxide. End up. Therefore, in the polymer electrolyte fuel cell, it is necessary to further reduce the carbon monoxide concentration in the reformed gas, and a carbon monoxide remover containing a carbon monoxide removal catalyst for oxidizing and removing carbon monoxide is provided. It is necessary to reduce the carbon monoxide concentration to about 10 ppm.

  A carbon monoxide remover selectively oxidizes carbon monoxide by adding an oxidant gas (usually air) to a reformed gas containing carbon monoxide in the presence of a carbon monoxide removal catalyst. The concentration is reduced. And since the oxidation of carbon monoxide in this carbon monoxide remover is carried out at a relatively high temperature (100 ° C. or higher), the carbon monoxide removal catalyst is easily oxidized, and the catalytic activity decreases with time. . Therefore, in order to recover the activity of the carbon monoxide removal catalyst, it is necessary to periodically contact the reducing gas to reduce the carbon monoxide removal catalyst.

  For example, Patent Document 1 below proposes an activation method in which a carbon monoxide removal catalyst is pretreated in a gas atmosphere containing hydrogen as a main component (50 mol% or more) and then used without being exposed to air. .

Further, in Patent Document 2 below, a carbon monoxide removal catalyst is activated by contacting an inert gas or a mixed gas containing hydrogen of a finite value or more and less than 50 vol% and the remaining gas being an inert gas. The measures are taken.
JP-A-10-29802 JP 2002-059883 A

  When a reducing gas containing hydrogen as a main component is used as the reducing gas used for recovering the activity of the carbon monoxide removal catalyst as in References 1 and 2 above, when the reducing gas used for the treatment is discharged out of the system, A post-treatment step such as diluting and reducing the hydrogen concentration so as to be below the explosion limit range (4 to 75 vol%) of was required.

  Further, as in Reference 2 above, when a mixed gas mixed with an inert gas such as nitrogen is used as a reducing gas, an inert gas typified by nitrogen is prepared to produce the mixed gas, and the mixed gas Since the supply device has to be provided, the device becomes large, and there are problems that installation cost and operation cost are high.

  Accordingly, an object of the present invention is to provide a method for recovering the activity of a carbon monoxide removal catalyst by a simple method in view of the above drawbacks.

  In achieving the above object, the method for recovering the activity of the carbon monoxide removal catalyst according to the present invention comprises reforming a hydrocarbon compound in a reformer having a combustion section, and a reformed gas mainly comprising the produced hydrogen. A method for recovering the activity of a carbon monoxide removal catalyst for removing carbon monoxide from the carbon monoxide removal catalyst, wherein the reformed gas generated in the reformer is brought into contact with the carbon monoxide removal catalyst without being brought into contact with air, The reformed gas brought into contact with the carbon monoxide removal catalyst is combusted in a combustion section of the reformer.

  Another method of recovering the activity of the carbon monoxide removal catalyst of the present invention is to reform a hydrocarbon compound in a reformer having a combustion section, and from a reformed gas mainly composed of generated hydrogen. A method for recovering the activity of a carbon monoxide removal catalyst for removing carbon monoxide, the hydrocarbon reformer comprising the reformer and the carbon monoxide remover filled with the carbon monoxide removal catalyst From the flow path for supplying the reformed gas to a fuel cell or a hydrogen purifier, a bypass flow path for supplying the reformed gas to the combustion unit is provided, and the reformed gas generated by the reformer is Contacting with the carbon monoxide removal catalyst without contacting with air, and supplying the reformed gas brought into contact with the carbon monoxide removal catalyst to the combustion section of the reformer through the bypass path. .

  According to the method for recovering the activity of the carbon monoxide removal catalyst of the present invention, not only the gas for use in recovering the activity of the carbon monoxide removal catalyst is generated by the reformer, but also the reformed gas used for the activity recovery is modified. Since it is post-treated in the gas purification device, there is no need to install a gas production / supply device used to recover the activity of the carbon monoxide removal catalyst, and there is no need to install a gas post-treatment device used for the treatment. Therefore, downsizing of the apparatus and reduction of installation / operation costs can be achieved.

  The fuel cell power generator operating method according to the present invention includes a reformer having a combustion section, a hydrocarbon reformer including a carbon monoxide remover filled with a carbon monoxide removal catalyst, and a fuel cell. An operating method of a fuel cell power generation apparatus comprising: a bypass flow path for supplying the reformed gas to the combustion combustion section on a flow path for supplying a reformed gas from the reformer to the fuel cell; During the start-up or standby operation of the battery power generation device, the reformed gas generated in the reformer is allowed to flow through the carbon monoxide remover without coming into contact with air to restore the activity of the carbon monoxide removal catalyst. And the product gas that has passed through the carbon monoxide remover is burned in a combustion section of the reformer.

  The operation method of the hydrogen generator of the present invention includes a reformer having a combustion section, a hydrocarbon reformer having a carbon monoxide remover filled with a carbon monoxide removal catalyst, and a hydrogen purifier. An operation method of the hydrogen generator comprising: a bypass flow path for supplying the reformed gas to the combustion combustion section on a flow path for supplying the reformed gas from the reformer to the hydrogen purifier; During the start-up or standby operation of the generator, the reformed gas generated in the reformer is allowed to flow through the carbon monoxide remover without being brought into contact with air to restore the activity of the carbon monoxide removal catalyst. The produced gas that has flowed through the carbon monoxide remover is burned in a combustion section of the reformer.

  And in this invention, it is preferable to distribute | circulate the said reformed gas by making the temperature of the said carbon monoxide removal catalyst into 150-300 degreeC.

  According to the present invention, since the activity of the carbon monoxide removal catalyst is recovered using the reformed gas generated in the reformer, a gas supply device for recovering the catalyst activity is unnecessary. In addition, since the reformed gas used for recovering the activity of the carbon monoxide removal catalyst is processed in the reformer, the processing of the reformed gas used for recovering the activity becomes unnecessary, and the fuel cell power generator and the hydrogen generator Maintenance, management and operation costs can be reduced.

  The present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a hydrogen generation apparatus to which a carbon monoxide removal catalyst activity recovery method according to the present invention can be applied.

  The hydrocarbon reformer 10 reforms a raw fuel such as a hydrocarbon compound to produce a reformed gas containing hydrogen as a main component for use in a fuel cell, and supplies the raw fuel. A supply system 1, a desulfurizer 2 for removing sulfur components contained in the raw fuel, a steam supply system 3 for mixing water vapor with the desulfurized raw fuel, and a reforming reaction of the raw fuel mixed with the water vapor A reformer 4 having a combustion section 4a to be converted, a carbon monoxide converter 5 for converting carbon monoxide into carbon dioxide from the reformed gas generated in the reformer 4, and a reformer in which the carbon monoxide is converted An oxidant supply system 6 that supplies an oxidant gas to the gas and a carbon monoxide remover 7 that further reduces carbon monoxide from the reformed gas mixed with the oxidant gas. Are connected through pipes.

  Further, a supply pipe 20 that supplies the reformed gas that has passed through the hydrocarbon reforming apparatus 10 to the hydrogen purification apparatus 8 and a supply pipe 21 that supplies the combustion section of the reformer 4 are electromagnetic. It is connected via the valve 30, and the flow path of the reformed gas can be switched by the electromagnetic valve 30. As the hydrogen purification device 8, a pressure swing adsorption device or a hydrogen separation membrane device can be used.

  Next, a method for reforming a hydrocarbon compound by the hydrocarbon reformer 10 will be described.

  Examples of the hydrocarbon compound used as the raw fuel in the present invention include hydrocarbons such as natural gas and naphtha, alcohols such as methanol and ethanol, and the like. LP gas or the like can be preferably used.

  When the raw fuel supplied from the raw fuel supply system 1 passes through the desulfurizer 2, the raw fuel is sulfurated by a desulfurization catalyst (for example, a Ni—Mo catalyst or a Co—Mo catalyst) filled in the desulfurizer 2. The compound is hydrogenated and further sulfur content is removed by contact with ZnO or the like. Then, after being mixed with the steam supplied from the steam supply system 3, it is transported to the reformer 4, where it contacts the reforming catalyst (for example, Ni-based catalyst or Ru-based catalyst), Hydrocarbons such as methane in the raw fuel are reformed to hydrogen. Since the reforming reaction of hydrocarbons to hydrogen is an endothermic reaction, the reformer 4 is heated by burning raw fuel gas or the like in the combustion section 4a. The reformed gas thus obtained is rich in hydrogen but contains carbon monoxide, carbon dioxide, moisture and the like as by-products. Then, in the carbon monoxide converter 5, the carbon monoxide is converted into carbon dioxide by contacting with a carbon monoxide conversion catalyst such as a Cu—Zn-based catalyst, and the carbon monoxide concentration is lowered to a predetermined value. ing. In the carbon monoxide conversion reaction by the carbon monoxide converter 5, the carbon monoxide concentration in the reformed gas can be reduced only to about 1.0%. Therefore, the carbon monoxide further provided with temperature adjusting means. In the remover 7, together with the oxidant gas (for example, air containing oxygen) supplied from the oxidant supply system 6, the carbon monoxide removal catalyst (for example, ruthenium, platinum, rhodium, palladium or the like noble metal such as alumina). Carbon monoxide is oxidized and removed to form carbon dioxide, and the carbon monoxide concentration in the reformed gas is 10 ppm or less.

  Through the above-described steps, the raw fuel gas composed of a hydrocarbon compound can be reformed into a hydrogen gas whose carbon monoxide is reduced to 10 ppm or less, which is supplied to the hydrogen purifier 8 to purify the reformed gas. Thus, although high purity hydrogen gas can be produced, the carbon monoxide removal catalyst charged in the carbon monoxide remover 7 is oxidized by the oxidant gas, and the catalytic activity decreases with time.

  In order to recover the activity of the carbon monoxide removal catalyst having decreased activity, the reducing gas is brought into contact with the carbon monoxide removal catalyst to recover the activity. In the present invention, the hydrocarbon compound is used as the reducing gas in the reformer 4. A reformed gas mainly composed of reformed hydrogen is used.

  Hereinafter, the method for recovering the activity of the carbon monoxide removal catalyst of the present invention will be described.

  In the activity recovery of the carbon monoxide removal catalyst of the present invention, the operation of the oxidant supply system 6 is stopped and the supply of the oxidant gas to the reformed gas produced by the reformer 4 is stopped. Then, the reformed gas is introduced into the carbon monoxide remover 7 and brought into contact with the carbon monoxide removal catalyst, and the carbon monoxide removal catalyst oxidized by the carbon monoxide removal reaction is reduced to restore the activity. . The reformed gas that has been passed through the carbon monoxide remover 7 and used to recover the activity of the carbon monoxide removal catalyst operates the electromagnetic valve 30 to open the supply pipe 21 and reforms through the supply pipe 21. The combustion gas is supplied to the combustion section 4a of the vessel 4 and burned with the reformed gas in the combustion section 4a to form combustion exhaust gas mainly containing nitrogen and carbon dioxide, and then communicated with an exhaust pipe installed in the combustion section 4a. To discharge outside the system.

  In the present invention, the flow rate of the reformed gas to be circulated during the activity recovery treatment of the carbon monoxide removal catalyst is not particularly limited. For example, in the case of a reformer for 1 kW class, 1 liter / min to 5 liter / It is preferably a minute, more preferably 3 liters / minute to 4 liters / minute. In the case of the 1 kW class, if the flow rate of the reformed gas is 5 liters / minute or more, the reformer 4 is excessively heated and the equipment such as the reformer 4 may break down. If it is less than 5 minutes, the oxidized carbon monoxide removal catalyst may be reduced and the activity may not be completely recovered.

  Further, the supply time of the reformed gas to the carbon monoxide remover 7 varies depending on the amount of catalyst charged in the carbon monoxide remover 7, but is preferably 30 minutes to 3 hours, more preferably 1 to 1 hour. 2 hours. If it is less than 30 minutes, the oxidized carbon monoxide removing catalyst may be reduced and the activity may not be completely recovered.

  Further, the reformed gas brought into contact with the carbon monoxide removal catalyst is preferably 100 to 400 ° C, more preferably 200 to 300 ° C.

  Moreover, it is preferable that the temperature of a carbon monoxide removal catalyst is 150-300 degreeC, and 200-300 degreeC is more preferable. By heating the carbon monoxide removal catalyst to the above temperature, it becomes possible to obtain a further activity recovery effect.

  The activity recovery of the carbon monoxide removal catalyst by the above operation is preferably carried out during standby operation that is performed when the hydrogen generator is started or when the demand for hydrogen is reduced, such as at night.

  FIG. 2 is a schematic configuration diagram of a fuel cell power generator that can be used in the activity recovery method of the carbon monoxide removal catalyst. In the following description of the embodiment, the same parts as those in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.

  1 differs from the embodiment shown in FIG. 1 in that the reformed gas that has been reformed through the hydrocarbon reformer 10 is supplied to the fuel cell 9, and the reformer 4 is combusted. The supply pipe 23 supplied to the section 4a is connected via an electromagnetic valve 31, and the flow path of the reformed gas can be switched by the electromagnetic valve 31.

  The method for recovering the activity of the carbon monoxide removal catalyst in this embodiment is the same as in the above-described embodiment. That is, during the activity recovery process of the carbon monoxide removal catalyst, the operation of the oxidant supply system 6 is stopped, and the supply of the oxidant gas to the reformed gas produced by the reformer 4 is stopped. Then, this reformed gas containing no oxidant gas is introduced into the carbon monoxide remover 7 and brought into contact with the carbon monoxide removal catalyst, so that the carbon monoxide removal catalyst oxidized by the carbon monoxide removal reaction is obtained. Reduce and restore activity. The reformed gas that has been passed through the carbon monoxide remover 7 and used to recover the activity of the carbon monoxide removal catalyst operates the electromagnetic valve 31 to open the supply pipe 23, passes through the supply pipe 23, and is reformed. 4 is supplied to the combustion unit 4a to form a combustion exhaust gas mainly composed of nitrogen and carbon dioxide, and then discharged out of the system through an exhaust pipe installed in the combustion unit 4a.

  In this embodiment, the fuel cell 9 using the reformed gas supplied from the hydrocarbon reformer 10 is not particularly limited, but the operating temperature is low and the electrode catalyst is easily poisoned by carbon monoxide. A polymer electrolyte fuel cell is particularly preferred.

  And it is preferable to carry out the activity recovery of the carbon monoxide removal catalyst by the above operation at the time of start-up of the fuel cell power generation device or at the time of standby operation when the power demand is reduced at night.

  The present invention can recover the activity of the carbon monoxide removal catalyst by a simple method. Further, the fuel cell and the hydrogen generator employing the activity recovery method of the present invention can be expected to reduce maintenance, management, and operation costs.

The schematic block diagram of the hydrogen generator which can be used for the activity recovery method of the carbon monoxide removal catalyst in this invention. The schematic block diagram of the fuel cell power generator which can be used for the activity recovery method of the carbon monoxide removal catalyst in this invention.

Explanation of symbols

1: Raw fuel supply system 2: Desulfurizer 3: Steam supply system 4: Reformer 4a: Combustion unit 5: Carbon monoxide converter 6: Oxidant supply system 7: Carbon monoxide remover 8: Hydrogen purifier 9 : Fuel cell 10: Hydrocarbon reformer 20, 21, 22, 23: Supply pipe 30, 31: Solenoid valve

Claims (7)

A method for recovering the activity of a carbon monoxide removal catalyst that reforms a hydrocarbon compound in a reformer having a combustion section and removes carbon monoxide from a reformed gas containing hydrogen as a main component,
Contacting the reformed gas generated in the reformer with the carbon monoxide removal catalyst without contacting with air;
A method for recovering the activity of a carbon monoxide removal catalyst, wherein the reformed gas brought into contact with the carbon monoxide removal catalyst is combusted in a combustion section of the reformer. A method for recovering the activity of a carbon monoxide removal catalyst that reforms a hydrocarbon compound in a reformer having a combustion section and removes carbon monoxide from a reformed gas containing hydrogen as a main component,
On a flow path for supplying the reformed gas to a fuel cell or a hydrogen purifier from a hydrocarbon reformer composed of the reformer and the carbon monoxide remover filled with the carbon monoxide removal catalyst Providing a bypass flow path for supplying the reformed gas to the combustion section;
Contacting the reformed gas generated in the reformer with the carbon monoxide removal catalyst without contacting with air;
A method for recovering the activity of a carbon monoxide removal catalyst, comprising supplying the reformed gas brought into contact with the carbon monoxide removal catalyst to a combustion section of the reformer through the bypass path.   The method for recovering the activity of a carbon monoxide removal catalyst according to claim 1 or 2, wherein the reformed gas is circulated at a temperature of the carbon monoxide removal catalyst of 150 to 300 ° C. A method for operating a fuel cell power generation apparatus having a reformer having a combustion section and a hydrocarbon reformer having a carbon monoxide remover filled with a carbon monoxide removal catalyst, and a fuel cell,
Providing a bypass flow path for supplying the reformed gas to the combustion section on a flow path for supplying the reformed gas from the reformer to the fuel cell;
During the start-up or standby operation of the fuel cell power generation device, the reformed gas generated in the reformer is circulated through the carbon monoxide remover without contacting the air, and the carbon monoxide removal catalyst is activated. Recover
A method of operating a fuel cell power generator, wherein the product gas that has passed through the carbon monoxide remover is combusted in a combustion section of the reformer.   The method for operating a fuel cell power generator according to claim 4, wherein the reformed gas is circulated at a temperature of the carbon monoxide removal catalyst of 150 to 300 ° C. A method for operating a hydrogen generator having a reformer having a combustion section and a hydrocarbon reformer having a carbon monoxide remover filled with a carbon monoxide removal catalyst, and a hydrogen purifier.
A bypass flow path for supplying the reformed gas to the combustion combustion section is provided on a flow path for supplying the reformed gas from the reformer to the hydrogen purifier;
During the start-up or standby operation of the hydrogen generator, the reformed gas generated in the reformer is circulated through the carbon monoxide remover without contacting the air, and the activity of the carbon monoxide removal catalyst is increased. Recover,
A method of operating a hydrogen generator, characterized in that the product gas flowing through the carbon monoxide remover is combusted in a combustion section of the reformer.   The operation method of the hydrogen generator according to claim 6, wherein the reformed gas is circulated at a temperature of the carbon monoxide removal catalyst of 150 to 300 ° C.