JP2005082409A6 - Hydrogen generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the startability and reduce the cost of a hydrogen generator for supplying a hydrogen rich gas to a distributed fuel cell. Therefore, it is a development problem to efficiently and stably remove carbon monoxide in the hydrogen-rich gas to a low concentration with a small catalyst amount.
[Solution]
A reforming section 1 for generating a hydrogen-rich gas containing carbon monoxide, an upstream catalyst layer 3 containing a catalyst mainly composed of platinum, and a downstream catalyst layer comprising a catalyst mainly composed of a metal alloyed with platinum and ruthenium A hydrogen generator comprising a shift section 2 having a shift catalyst with 4 and an oxidizing gas supply section 6 for supplying an oxidizing gas between the upstream catalyst layer 3 and the downstream catalyst layer 4.
[Selection] Figure 1

Description

  The present invention relates to a hydrogen generator. More specifically, the present invention relates to an apparatus that removes CO (carbon monoxide) in a hydrogen-rich gas produced by a reforming reaction and produces hydrogen used for fuel such as a fuel cell.

  A fuel cell cogeneration system with high power generation efficiency and high overall efficiency has attracted attention as a distributed power generator that effectively uses energy.

  Many fuel cells, such as phosphoric acid fuel cells that have been put to practical use and solid polymer fuel cells that are being developed, generate power based on hydrogen. However, since hydrogen is not provided as infrastructure, it must be generated at the site where the system is installed.

  Hydrogen is generated by mixing steam with hydrocarbon fuels such as methane, propane, gasoline, kerosene, alcohol fuels such as methanol, or ether fuels such as dimethyl ether, and bringing them into contact with a heated reforming catalyst. . Usually, the hydrocarbon fuel is reformed at a temperature of about 500 to 800 ° C, and the alcohol or ether fuel is reformed at a temperature of about 200 to 400 ° C.

  During reforming, CO is generated, and the concentration of generated CO increases as reforming is performed at a higher temperature. In particular, when a hydrocarbon fuel is used, the CO concentration is about 10% by volume (dry gas base). Therefore, the CO concentration is reduced to about several thousand ppm to several volume% by providing a shift portion containing a shift catalyst that causes CO and water vapor to contact each other to advance the water gas shift reaction.

  Furthermore, in the case of a fuel cell that operates at a low temperature of 100 ° C. or less, such as a polymer electrolyte fuel cell used for in-vehicle use or home use, the Pt (platinum) catalyst used for the electrode is replaced with hydrogen-rich gas. Since it is poisoned by the contained CO, it is necessary to remove the CO concentration to 100 ppm or less, preferably 10 ppm or less before supplying the hydrogen-rich gas to the fuel cell. For this reason, a purification unit filled with a catalyst after the shift unit is provided in the hydrogen generator, and CO is methanated or selectively oxidized by adding a small amount of air to remove CO.

  In order to ensure that the CO concentration is 100 ppm or less in the purification section, it is necessary to reduce the CO concentration to several thousand ppm or less by the shift catalyst. Conventionally, a Cu—Zn-based catalyst has been used as a shift catalyst (see, for example, Patent Document 1).

  In addition, a proposal using a shift catalyst containing a noble metal catalyst has also been made (see, for example, Patent Document 2).

A method of dividing the shift catalyst into a plurality of stages has also been proposed (see, for example, Patent Document 3).
JP-A-6-290801 JP 2000-178007 A JP 2001-180912 A

  However, the above prior art has several problems. For example, in the method described in Patent Document 1, since it is necessary to always maintain the reduced state of the Cu—Zn-based catalyst in order to proceed with the shift reaction, in the distributed fuel cell cogeneration system assuming frequent start and stop, The catalyst activity may be reduced due to air mixing at the time of stopping, which is not very practical.

  Further, in the method described in Patent Document 2, since the catalytic activity is low, a large amount of catalyst is required to reduce the CO concentration after the shift catalyst to several thousand ppm or less, and the high cost due to the use of a large amount of noble metal. Or increase the size of the apparatus and the startup time.

  In the method described in Patent Document 3, the reaction is carried out at a low temperature in order to reduce CO to several thousand ppm or less in the shift catalyst containing a noble metal. For this purpose, a large amount of catalyst is required, and there are still problems such as an increase in cost due to the use of a large amount of noble metal, an increase in the size of the apparatus, and a long startup time.

  Patent Document 2 discloses that when a shift catalyst containing a noble metal is used, air is introduced from the upstream of the shift section to maintain the shift catalyst temperature. However, introducing air from the upstream of the shift section has a problem that the temperature of the shift catalyst may be too high, and only CO cannot be effectively reduced.

  An object of the present invention is to provide a hydrogen generator capable of reducing the cost, downsizing the apparatus, shortening the startup time, or reducing CO more effectively in consideration of the above-described conventional problems. And

  In order to achieve the above object, a first aspect of the present invention includes a reforming unit that generates a hydrogen-rich gas containing carbon monoxide, and an upstream catalyst that reduces carbon monoxide in the hydrogen-rich gas by a water gas shift reaction. A hydrogen generation apparatus including a shift section having a shift catalyst having a layer and a downstream catalyst layer, and an oxidizing gas supply section that supplies an oxidizing gas between the upstream catalyst layer and the downstream catalyst layer.

In the second aspect of the present invention, the upstream catalyst layer has a catalyst mainly composed of platinum,
The downstream catalyst layer is the hydrogen generator according to the first aspect of the present invention having a catalyst whose main component is a metal alloyed with platinum and ruthenium.

  Further, according to a third aspect of the present invention, the downstream catalyst layer includes a first downstream catalyst layer having a catalyst containing platinum particles and metal particles alloyed with platinum and ruthenium on the upstream side, and platinum and ruthenium alloyed on the downstream side. It is the 1st or 2nd hydrogen generator of this invention provided with the 2nd downstream catalyst layer which has a catalyst containing the metal particle and ruthenium particle which were made.

  In a fourth aspect of the present invention, the oxidizing gas supply unit is a first oxidizing gas supply unit, and an oxidizing gas is supplied between the first downstream catalyst layer and the second downstream catalyst layer. It is the hydrogen generator of the 3rd this invention further provided with the property gas supply part.

According to a fifth aspect of the present invention, the first downstream catalyst layer comprises a step of supporting platinum by an impregnation method from a support and a platinum salt aqueous solution, a step of performing hydrogen reduction, and a ruthenium salt aqueous solution by an impregnation method. A first downstream catalyst layer produced by a supporting step and a hydrogen reduction step,
The second downstream catalyst layer performs a step of supporting ruthenium from the support and an aqueous ruthenium salt solution by an impregnation method, a step of performing hydrogen reduction, a step of supporting platinum by an impregnation method of an aqueous platinum salt solution, and performing hydrogen reduction. It is the 3rd or 4th hydrogen generator of the present invention which is the 2nd downstream catalyst layer manufactured by the process.

  According to the present invention, CO can be reduced with a relatively small amount of air supply compared with the case where an air supply unit is provided on the upstream side of a conventional noble metal catalyst layer, and CO can be used under conditions that are advantageous from the viewpoint of hydrogen generation efficiency. A hydrogen generator that can be reduced can be provided.

  Alternatively, it is possible to provide a hydrogen generator that can reduce CO more effectively even if the number of catalysts is reduced.

  Alternatively, by reducing the amount of catalyst, the heat capacity of the shift section can also be reduced, so that it is possible to provide a hydrogen generator that achieves a reduction in start-up time, a reduction in cost, and a reduction in size.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of a hydrogen generator according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a reforming unit, which generates a reformed gas (hydrogen-rich gas) with this reformer. The hydrogen-rich gas produced by the reforming unit 1 used in the present invention is composed of at least hydrogen and carbon as exemplified by hydrocarbons such as methane, propane and city gas, alcohols such as methanol or ethers such as dimethyl ether. It is produced by mixing steam or air with the raw material to be heated, passing through a heated reforming catalyst layer, and mainly steam reforming.

The composition of the hydrogen-rich gas produced by the reforming unit 1 varies depending on the reforming method and the raw material type, but excluding water vapor, hydrogen is 40 to 60% by volume, carbon dioxide is 8 to 25% by volume, and CO is 5 to 15% by volume. Generally, it is%. For example, when methane is steam reformed, hydrogen is about 60% by volume, carbon dioxide is 5 to 15% by volume, and CO is 5 to 15% by volume. In the case of a raw material such as alcohol or ether that can undergo a reforming reaction at a low temperature, the CO concentration after reforming may be about 1% by volume. The details of the configuration are omitted here. Reference numeral 2 denotes a metamorphic portion, which advances the water gas shift reaction between CO and water vapor in the hydrogen-rich gas, and is composed of an upstream catalyst layer 3 and a downstream catalyst layer 4. In the first embodiment, the upstream catalyst layer 3 is formed by supporting Pt on cerium oxide (ceria) as a carrier and then coating the cordierite honeycomb.

  Further, the downstream catalyst layer 4 was formed by supporting metal particles obtained by alloying Pt and Ru (ruthenium) on aluminum oxide (alumina) as a carrier and then coating the cordierite honeycomb. In addition, 5 is a water supply unit that supplies water to the shift unit, and 6 is an air supply unit that is an example of the oxidizing gas supply unit of the present invention that supplies air into the shift unit 2. The air supplied from the air supply unit 6 was mixed with the hydrogen-rich gas after passing through the upstream catalyst layer 3 and then passed through the downstream catalyst layer 4.

  Reference numeral 7 denotes a temperature detection unit that detects the temperature after passing through the downstream catalyst layer. The temperature detector 7 may be configured to measure the temperature of the downstream catalyst layer 4 or the temperature of the hydrogen rich gas before passing through the downstream catalyst layer 4.

  A cooling fan 8 serves as a cooling unit, and cools the downstream catalyst layer 4 from the outside of the shift unit 2. The cooling fan 8 may be configured to cool the hydrogen rich gas before and after passing through the downstream catalyst layer 4.

  In the first embodiment, the cooling fan 8 is controlled to be turned on and off in order to make the temperature detected by the temperature detector 7 constant. The temperature detection unit 7 and the cooling fan 8 can be omitted depending on the device configuration and operating conditions.

  Further, the control unit 10 issues a command to the water supply unit 5, the air supply unit 6, and the cooling fan 8, and performs output control of the water supply unit 5, the air supply unit 6, and the cooling fan 8. In particular, the control of the cooling fan 8 is performed so that the detected temperature becomes constant as described above based on the temperature detected by the temperature detector 7 input to the controller 10.

The apparatus operation in the above configuration will be described.
The hydrogen-rich gas generated by the reforming unit 1 is sent to the shift unit 2. At this time, the CO concentration in the hydrogen-rich gas is about 10%.

  In the shift unit 2, the upstream catalyst layer 3 proceeds with a water gas shift reaction that is a reaction between CO in the hydrogen-rich gas, water vapor in the hydrogen-rich gas, and water supplied from the water supply unit 5 to reduce CO. At this time, the CO concentration in the hydrogen-rich gas after passing through the upstream catalyst layer 3 is about 2%.

  The hydrogen rich gas after the upstream catalyst layer 3 is mixed with the air sent from the air supply unit 6 and sent to the downstream catalyst layer 4 of the shift unit 2. In the downstream catalyst layer 4, oxygen in the air supplied from the air supply unit 6 promotes the CO reduction reaction, and reduces the CO concentration in the hydrogen-rich gas at the outlet of the shift unit 2 to 100 ppm or less.

  In order to reduce the CO concentration in the hydrogen-rich gas after the shift section 2, rather than supplying air from the upstream of the shift section 2, a small amount of air is supplied from the middle of the shift section 2 where the CO concentration is reduced to some extent. Since the ratio of oxygen to CO can be increased even with the air, the effect of air supply can be increased. Moreover, the fact that the amount of air supply for reducing CO can be reduced leads to a reduction in the amount of hydrogen to be oxidized, which is advantageous from the viewpoint of hydrogen generation efficiency.

  The metal particles obtained by alloying Pt and Ru constituting the downstream catalyst layer 4 can effectively reduce CO. The water gas shift reaction proceeds by a reaction between CO molecules adsorbed on Pt and water adsorbed on Ru and decomposed. Since Pt and Ru are alloyed, the probability that Ru is present next to Pt is increased, and the reaction is further facilitated.

  Normally, when the catalyst temperature is low, it is difficult to desorb while CO is adsorbed on Pt, the reaction does not proceed, and it is difficult to reduce CO. However, when oxygen is supplied to a catalyst including metal particles obtained by alloying Pt and Ru, the coexistence of oxygen around Pt can promote the desorption of CO even at a low temperature. As a result, CO is easily desorbed from the Pt surface, so that the water gas shift reaction proceeds, the reaction rate of CO reduction is increased, and CO can be reduced even at low temperatures. In addition, since CO reduction by water gas shift reaction is more advantageous in terms of chemical equilibrium at lower temperatures, in the present invention, the CO concentration in the hydrogen-rich gas after the outlet of the shift unit 2 can be reduced to 100 ppm or less.

  In addition, when compared with the configuration in which the apparatus configuration of the first embodiment and the conventional noble metal conversion catalyst are used to advance the water gas shift reaction without supplying air, the present embodiment has a CO reduction reaction rate. Since the speed is increased by the action as described above, the amount of catalyst can be reduced, and CO can be reduced with a catalyst amount of 1/5 to 1/10 of the conventional amount. This reduces the amount of noble metal, which is advantageous for cost reduction.

  Further, since the volume occupied by the catalyst is reduced, space saving and compactness can be realized as a hydrogen generator and a fuel cell cogeneration system, which is advantageous in terms of carrying and flexibility in installation conditions.

  Furthermore, the small volume occupied by the catalyst means that, at the time of start-up, the time and amount of heat for raising the catalyst temperature, which is in the state of room temperature or outside air temperature, to the temperature at which the CO reduction reaction starts (about 100 ° C. or more) are small. Therefore, the time until CO can be reduced is reduced. Moreover, the energy loss at the time of starting can also be reduced from the point that warm-up time becomes short.

  In order to keep the temperature of the downstream catalyst layer 4 or the temperature of the hydrogen rich gas before and after passing through the downstream catalyst layer 4 constant in the first embodiment, the cooling fan 8 is used. It is also possible to control by increasing or decreasing the amount of air from 6. When the temperature detected by the temperature detection unit 7 becomes lower than a certain level, the control unit 10 instructs the air supply unit 6 to increase the air amount, and the air supply amount is increased to increase the reaction heat amount. On the other hand, if the temperature becomes higher than the constant temperature detected by the temperature detector 7, the controller 10 instructs the air supply unit 6 to reduce the amount of air, and the air supply amount is reduced to reduce the reaction heat amount. Thus, the temperature can be kept constant, and CO can be further stably reduced.

  Even when the amount of the medium is increased or decreased by using a heat exchanger that takes the heat of the downstream catalyst layer 4 or the hydrogen-rich gas with a medium such as water, the temperature of the downstream catalyst layer 4 or the hydrogen passing through the downstream catalyst layer 4 The temperature of the rich gas can be kept constant, and CO can be stably reduced. Further, when water is used as the medium, water can be evaporated by heat exchanged from the hydrogen-rich gas, and can be sent from the water supply unit 5 into the shift unit 2, and the water gas shift reaction can be further advanced. It is possible to stably reduce CO.

  Further, Pt particles or Ru particles may be mixed in metal particles obtained by alloying Pt and Ru.

  In the present embodiment, the catalyst containing metal particles obtained by alloying Pt and Ru is subjected to hydrogen reduction after supporting Pt and Ru from a support, an aqueous solution of Pt salt and an aqueous solution of Ru salt by an impregnation method. Prepared. However, the supporting method is not particularly limited, and for example, a coprecipitation method, a sol-gel method, a precipitation precipitation method, an alkoxide method, or the like can be used.

  The catalyst is preferably supported on a carrier so that it can be supported in a highly dispersed state. The catalyst carrier is not particularly limited as long as the catalyst active component can be supported in a highly dispersed state. Examples of such materials include alumina, silica, silica alumina, ceria, magnesia, titania, and zeolite. Examples of the type of zeolite that can carry the catalytically active component in a highly dispersed state include A-type zeolite, X-type zeolite, Y-type zeolite, beta-type zeolite, mordenite, and ZSM-5. These carriers may be used alone or in combination of two or more.

  In the first embodiment, a carrier base material such as a cordierite honeycomb is coated, but it may be formed in a pellet shape.

  In the first embodiment, the upstream catalyst layer 3 and the downstream catalyst layer 4 are installed in the shift unit 2, but the shift unit may be divided and each catalyst layer may be set separately.

  Note that the amount of air supplied from the air supply unit 6 needs to be set according to the apparatus configuration and usage conditions, such as increasing or decreasing the amount of air supplied from the air supply unit 6 according to conditions such as when the amount of hydrogen to be generated is small.

  In order to further reduce CO, a purifying unit containing a catalyst for reducing CO in the hydrogen-rich gas by selective oxidation reaction or methanation reaction may be provided after the shift unit 2.

(Embodiment 2)
FIG. 2 is a configuration diagram in the present embodiment. The present embodiment is different from the first embodiment in that the downstream catalyst layer is divided into a first downstream catalyst layer 11 and a second downstream catalyst layer 12.
Further, the temperature detection unit 17 detects the hydrogen rich gas temperature after passing through the second downstream catalyst layer 12. Note that the temperature of the first downstream catalyst layer 11 or the second downstream catalyst layer 12 or the hydrogen rich gas temperature before and after passing through the first downstream catalyst layer 11 may be detected.

  The cooling fan 18 cools the second downstream catalyst layer 12 from the outside of the shift unit 2. In addition, you may make it the structure which cools the hydrogen rich gas before and behind passing through the 1st downstream catalyst layer 11, the 1st downstream catalyst layer 11, and the 2nd downstream catalyst layer 12.

Further, a cooling fan can be additionally installed in the apparatus configuration and conditions.
In the present embodiment, the cooling fan 18 is ON / OFF controlled in order to keep the temperature detected by the temperature detector 17 constant. The temperature detection unit 17 and the cooling fan 18 can be omitted depending on the device configuration and operating conditions.

  Further, the control unit 20 issues a command to the water supply unit 5, the air supply unit 6, and the cooling fan 8, and performs output control of the water supply unit 5, the air supply unit 6, and the cooling fan 8. In particular, the control of the cooling fan 8 is performed so that the detected temperature becomes constant as described above based on the temperature detected by the temperature detector 17 input to the controller 20.

  In the present embodiment, the first downstream catalyst layer 11 is a catalyst containing metal particles obtained by alloying Pt and Ru and Pt particles. The catalyst was prepared by carrying Pt from an alumina carrier and an aqueous Pt salt solution by impregnation, followed by hydrogen reduction, and subsequently carrying Ru by impregnation with an aqueous Ru salt solution, followed by hydrogen reduction. The cordierite honeycomb coated was used.

  For the second downstream catalyst layer 12, a catalyst containing metal particles obtained by alloying Pt and Ru and Ru particles was used. The catalyst was prepared by carrying Ru from an alumina carrier and an aqueous Ru salt solution after impregnation, followed by hydrogen reduction, and then carrying Pt by impregnation with an aqueous Pt salt solution, followed by hydrogen reduction. The cordierite honeycomb coated was used.

  Next, the characteristics of the shift catalyst used in the present embodiment will be described.

  Compared with a catalyst containing only alloyed metal particles, the catalyst used for the first downstream catalyst layer 11 increases the amount of adsorption of CO due to the presence of Pt particles, and the reaction rate increases particularly at high temperatures. Therefore, the amount of catalyst can be reduced.

  In addition, the catalyst used for the second downstream catalyst layer 12 contains Ru particles in a mixed manner compared to the case where only the alloyed metal particles are included, so that the Ru catalytic characteristics are increased. Since Ru has a high activity of adsorbing and decomposing water molecules, the water gas shift reaction proceeds even at a low temperature, and CO reduction activity can be maintained.

  In the hydrogen generator, high-temperature hydrogen-rich gas flows from the reforming section on the upstream side, and heat escapes to the outside from the catalyst or the airframe containing the catalyst as it passes through the transformation section. The hydrogen rich gas temperature tends to decrease toward the side. Therefore, in the present embodiment, a catalyst including metal particles obtained by alloying Pt and Ru and Pt particles is used for the first downstream catalyst layer 11 that is at a high temperature. As a result, the amount of CO adsorbed is increased as compared with the case where only alloyed metal particles are included, so that the reaction rate is increased particularly at high temperatures, and the amount of catalyst can be reduced.

  Moreover, the catalyst containing the metal particle and Ru particle | grains which alloyed Pt and Ru was used for the 2nd downstream catalyst layer 12 which becomes low temperature easily. This is because the presence of many Ru particles increases the activity of adsorbing and decomposing water, and the water gas shift reaction activity can be maintained even at low temperatures.

  That is, by combining a catalyst that can reduce CO even at a high temperature on the upstream side and a catalyst that can reduce CO even at a low temperature on the downstream side, CO can be stably reduced.

  The mixture of Pt particles and Ru particles can be set according to the type of fuel cell to be used or the use conditions.

  In addition, the distribution of the constituent metal in such metal particles can be confirmed by performing XMA analysis using TEM.

  In the Pt—Ru alloy described here, it is desirable that Pt and Ru are each in a ratio of 40 to 60 atom% because they are easily alloyed. In the present invention, when Pt particles or Ru particles coexist, the Pt particles and Ru particles coexisting with the alloy indicate that the other metals in the particles are less than the trace amount in an analytical instrument such as XMA. Indicates that 90 atm% or more is composed of Pt and Ru.

  Pt has a face-centered cubic structure, but the lattice constant is changed by alloying with a dissimilar metal. The change can be easily measured by measuring XRD.

  In the second embodiment, the catalyst carrier is not particularly limited as long as the catalyst active component can be supported in a highly dispersed state. Examples of such materials include alumina, silica, silica alumina, ceria, magnesia, titania, and zeolite. Examples of the type of zeolite that can support the catalytically active component in a highly dispersed state include A-type zeolite, X-type zeolite, Y-type zeolite, beta-type zeolite, mordenite, and ZSM-5. These carriers may be used alone or in combination of two or more.

  In the second embodiment, a carrier base material such as a cordierite honeycomb may be coated, or may be in a pellet shape.

  In the second embodiment, the upstream catalyst layer 3, the first downstream catalyst layer 11, and the second downstream catalyst layer 12 are installed in the shift section 2, but are divided as individual shift sections, and each catalyst is divided. The layers may be installed separately.

(Embodiment 3)
FIG. 3 is a configuration diagram in the present embodiment. The third embodiment is different from the second embodiment in that the downstream catalyst interlayer air that is an example of the second dioxide gas supply unit of the present invention is provided between the first downstream catalyst layer 11 and the second downstream catalyst layer 12. The supply unit 21 is provided to supply air directly into the hydrogen rich gas after passing through the first downstream catalyst layer 11. The control of the cooling fan 18 for making the temperature detected by the temperature detection unit 17 constant can be set according to the device configuration and conditions.

  The control unit 30 issues a command to the water supply unit 5, the air supply unit 6, the cooling fan 18, and the downstream catalyst interlayer air supply unit 21 to perform output control of these devices. In particular, the control of the cooling fan 18 is performed so that the detected temperature becomes constant as described above based on the temperature detected by the temperature detection unit 7 input to the control unit 10.

  By supplying air directly into the hydrogen-rich gas after passing through the first downstream catalyst layer 11, air necessary for reducing CO in the second downstream catalyst layer 12 is supplied in advance to the first downstream catalyst layer 11. There is no need. That is, the air necessary for the first downstream catalyst layer 11 can be divided and supplied from the air supply unit 6, and the air necessary for the second downstream catalyst layer 12 can be divided and supplied from the downstream catalyst interlayer air supply unit 21. If necessary air is supplied to the second downstream catalyst layer 12 in advance by the first downstream catalyst layer 11, excess oxygen in the air may oxidize and consume hydrogen in the first downstream catalyst layer 11. By dividing and supplying hydrogen, hydrogen consumption can be suppressed and hydrogen can be generated efficiently.

  Further, the consumption due to the oxidation of hydrogen can also be suppressed by increasing or decreasing the amount of air from the air supply unit 6 and the downstream catalyst interlayer air supply unit 21 at the time of startup and when changing the amount of generated hydrogen. And can generate hydrogen efficiently. The air supply amount can be set in accordance with the apparatus configuration and operating conditions.

  In addition, it may be divided as individual metamorphic parts and each catalyst layer may be installed separately.

  Hereinafter, the hydrogen generator of the present invention will be described more specifically based on examples.

(Example 1)
Pt and Ru were supported on γ-alumina by an impregnation method using a chloroplatinic acid aqueous solution and a ruthenium chloride aqueous solution, and hydrogen reduction treatment was performed at 900 ° C. to prepare Pt-Ru / alumina. Pt was 50 atm% and Ru was 50 atm%. When the lattice constant was measured by XRD, it was 3.857 、, which was smaller than the lattice constant of 3.923 Ｐ and was confirmed to be alloyed. Alumina sol and water were added to the catalyst so that the solid content was 5 wt%, and ball milled to prepare a catalyst slurry. The catalyst slurry was coated on a cordierite honeycomb having a diameter of 80 mm and a length of 40 mm. The honeycomb was supported on the honeycomb so that the amount supported was 3 g / L of Pt. The obtained catalyst was installed as the downstream catalyst layer 4 in the shift section 2 of the hydrogen generator described in Embodiment 1 shown in FIG.

  In the reforming unit 1, hydrogen-rich gas generated from methane gas and water was supplied to the transformation unit 2. When the gas composition at the outlet of the reforming unit 1 was measured by gas chromatography after removing water vapor, CO was 10% by volume, carbon dioxide was 10% by volume, methane was 3% by volume, and the remainder was hydrogen.

  Water was added to the hydrogen rich gas exiting the reforming unit 1 from the water supply unit 5 at a flow rate of about 5 g / min. Water becomes water vapor in the metamorphic section 2, and CO in the hydrogen-rich gas and the water gas shift reaction proceed on the upstream catalyst layer 3 to reduce CO. Further, when the gas composition that passed through the upstream catalyst layer 3 was measured by gas chromatography after removing water vapor, CO was 2% by volume, carbon dioxide was 18% by volume, methane was 3% by volume, and the remainder was hydrogen.

The hydrogen rich gas that passed through the upstream catalyst layer 3 was supplied to the downstream catalyst layer 4. The hydrogen rich gas flow rate was adjusted in the reforming unit 1 so that the SV in the downstream catalyst layer 4 was 10,000 h ⁻¹ . Air was supplied at 1.5 L / min from the air supply unit 6.

  Further, the downstream catalyst layer 4 is cooled by the cooling fan 8, the temperature detected by the temperature detection unit 7 is changed, the composition of the gas discharged from the outlet of the shift unit 2 is removed by the gas chromatography after the water vapor is removed. It was measured.

(Comparative Example 1)
For comparison, when the same hydrogen generator as in Example 1 was used and the air was not supplied from the air supply unit, the composition of the gas discharged from the outlet of the transformation unit 2 was removed by gas chromatography after removing water vapor. It was measured.

(Comparative Example 2)
For comparison, measurement was performed by changing the catalyst of the downstream catalyst layer 4 of Example 1.

  Pt / ceria prepared by supporting Pt on cerium oxide (ceria) using an aqueous chloroplatinic acid solution was added to an alumina sol and water so that the solid content was 5 wt%, and ball milled to prepare a catalyst slurry. This catalyst slurry was coated on a cordierite honeycomb having a diameter of 80 mm and a length of 40 mm. The supported amount was supported on the honeycomb so as to be Pt 3 g / L. The obtained catalyst was installed as the downstream catalyst layer 4 in the shift unit 2 of the same hydrogen generator as in Example 1, and air was supplied from the air supply unit 6 at 1.5 L / min. The composition of the discharged gas was measured by gas chromatography after removing water vapor.

  The results of Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG.

  As in Example 1 in FIG. 4, the CO concentration in the hydrogen rich gas at the outlet of the shift unit 2 could be reduced to 100 ppm or less by the configuration and operation of the hydrogen generator shown in Embodiment 1.

(Example 2)
Using an aqueous chloroplatinic acid solution, Pt was supported on γ-alumina by an impregnation method, and hydrogen reduction was performed at 350 ° C. Ru was supported on this Pt / alumina by an aqueous ruthenium chloride solution, and hydrogen reduction treatment was performed at 900 ° C. to prepare Pt—Ru (Pt) / alumina. Pt was 50 atm% and Ru was 50 atm%.

  When the lattice constant was measured by XRD, it was 3.859 、, which was smaller than the lattice constant of 3.923 Ｐ, confirming that it was alloyed. From this XMA analysis, particles containing Pt and Ru in an atomic ratio of about 1: 1.2 and particles having 90% or more of this catalyst were observed for this catalyst.

  Alumina sol and water were added to the catalyst so that the solid content was 5 wt%, and ball milled to prepare a catalyst slurry. This catalyst slurry was coated on a cordierite honeycomb having a diameter of 80 mm and a length of 10 mm. The honeycomb was supported on the honeycomb so that the amount supported was 3 g / liter Pt. The catalyst thus produced is referred to as catalyst A.

  Further, Ru was supported on γ-alumina by an impregnation method using an aqueous ruthenium chloride solution, and hydrogen reduction was performed at 350 ° C. This Ru / alumina was loaded with Pt by a chloroplatinic acid aqueous solution and subjected to hydrogen reduction treatment at 900 ° C. to prepare Ru—Pt (Ru) / alumina. Pt was 50 atm% and Ru was 50 atm%.

  When the lattice constant was measured by XRD, it was 3.852 kg, and it was confirmed that it was alloyed. As a result of XMA analysis of this catalyst, particles containing Pt and Ru in an atomic ratio of about 1.2: 1 and particles having 90% or more of Ru were observed. A catalyst slurry was prepared in the same manner for this catalyst, and coated on a cordierite honeycomb having a diameter of 80 mm and a length of 20 mm. The catalyst thus produced is referred to as catalyst B.

  The obtained catalyst A was installed as the first downstream catalyst layer 11 of the hydrogen generator described in Embodiment 2 of FIG.

  As in Example 1, hydrogen rich gas is supplied into the shift unit 2, air is supplied from the air supply unit 6 at 1.5 L / min, and water vapor is removed from the composition of the gas discharged from the shift unit 2 outlet. And then measured by gas chromatography.

  FIG. 5 shows the result of comparison between Example 1 and Example 2.

  With the configuration and operation of the hydrogen generator shown in Embodiment 2, CO was able to be reduced to 100 ppm or less in Example 2 in a wider temperature range.

(Example 3)
The catalyst A obtained in Example 2 was installed as the first downstream catalyst layer 11 of the hydrogen generator described in Embodiment 3 of FIG. 3, and the catalyst B was installed as the second downstream catalyst layer 12, respectively.

  The hydrogen rich gas was supplied into the shift unit 2 in the same manner as in Example 1. The air supply amount at this time was supplied from the air supply unit 6 at a flow rate of 0.5 L / min and from the downstream catalyst interlayer air supply unit 21 at a flow rate of 0.5 L / min. As in Examples 1 and 2, the composition of the gas discharged from the outlet of the transformation section 2 was measured by gas chromatography after removing water vapor.

  FIG. 6 shows the result of comparison between Example 2 and Example 3.

  With the configuration and operation of the hydrogen generator shown in Embodiment 3, CO could be reduced to 100 ppm or less even when the amount of supplied air was reduced as compared with Example 2.

  The hydrogen generator according to the present invention has an effect that CO can be reduced with a relatively small air supply amount and also in terms of advantageous hydrogen generation efficiency. The hydrogen generator and the fuel using the hydrogen generator It is useful as a battery system.

Configuration diagram of a hydrogen generator in Embodiment 1 of the present invention Configuration diagram of a hydrogen generator in Embodiment 2 of the present invention Configuration diagram of a hydrogen generator in Embodiment 3 of the present invention The figure showing CO density | concentration of the metamorphosis part 2 exit in Example 1, Comparative example 1, and Comparative example 2 of this invention The figure showing CO concentration of the metamorphic part 2 exit in Example 1 and Example 2 of this invention The figure showing CO density | concentration of the metamorphic part 2 exit in Example 2 and Example 3 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reforming part 2 Transformation part 3 Upstream catalyst layer 4 Downstream catalyst layer 5 Water supply part 6 Air supply part 7 Temperature detection part 8 Cooling fan 10 Control part 11 First downstream catalyst layer 12 Second downstream catalyst layer 17 Temperature detection part 18 Cooling fan 20 Control unit 21 Downstream catalyst interlayer air supply unit 30 Control unit

Claims (5)

A reforming section for producing a hydrogen-rich gas containing carbon monoxide;
A shift section having a shift catalyst having an upstream catalyst layer and a downstream catalyst layer for reducing carbon monoxide in the hydrogen-rich gas by a water gas shift reaction;
A hydrogen generator comprising an oxidizing gas supply unit that supplies an oxidizing gas between the upstream catalyst layer and the downstream catalyst layer. The upstream catalyst layer has a catalyst mainly composed of platinum,
The hydrogen generator according to claim 1, wherein the downstream catalyst layer includes a catalyst mainly composed of a metal alloyed with platinum and ruthenium.   The downstream catalyst layer includes a metal particle obtained by alloying platinum and ruthenium on the upstream side and a catalyst containing platinum particles, and a metal particle obtained by alloying platinum and ruthenium and ruthenium particles on the downstream side. The hydrogen generator according to claim 1, further comprising a second downstream catalyst layer having a catalyst. The oxidizing gas supply unit is a first oxidizing gas supply unit,
The hydrogen generator according to claim 3, further comprising a second dioxide gas supply unit that supplies an oxidizing gas between the first downstream catalyst layer and the second downstream catalyst layer. The first downstream catalyst layer includes a step of supporting platinum by an impregnation method from a support and an aqueous solution of platinum salt, a step of performing hydrogen reduction, a step of supporting ruthenium by an impregnation method of an aqueous ruthenium salt solution, and performing hydrogen reduction. A first downstream catalyst layer produced by a process,
The second downstream catalyst layer performs a step of supporting ruthenium from a support and an aqueous ruthenium salt solution by an impregnation method, a step of performing hydrogen reduction, a step of supporting platinum by an impregnation method of an aqueous platinum salt solution, and performing hydrogen reduction. The hydrogen generator according to claim 3 or 4, wherein the hydrogen generator is a second downstream catalyst layer produced by a process.

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