JP2006008434A - Hydrogen generating unit, fuel cell electricity generating system, and hydrogen generating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a reforming catalyst, a shift catalyst, or a carbon monoxide removing catalyst having high heat resistance, and improved in the effect with oxygen contamination when stop-and-go of operation is repeated. <P>SOLUTION: The hydrogen generating unit comprises a reforming part 3 where a hydrogen-rich gas is formed by reacting a feed with water in the presence of a reforming catalyst, a shift part 4 where there is a shift catalyst and the generated hydrogen-rich gas is reacted with steam, and the concentration of carbon monoxide in the hydrogen-rich gas is reduced, and a carbon monoxide removing part 5 where there is the carbon monoxide removing catalyst and the carbon monoxide contained in the gas discharged from the shift part 4 is oxidized and reduced by hydrogen, and the reforming catalyst, the shift catalyst, and the carbon monoxide removing catalyst contain each a noble metal element or Ni element as its active component and the carriers of the active components contain a metal oxide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrogen generator, a fuel cell power generation system, and a hydrogen generation method.

  Recently, hydrogen energy has attracted attention as a promising candidate for fossil fuels, but there are various problems in terms of production cost, storage and transportation, etc., so hydrogen energy is generally used mostly for civilian use. It has not been. In order to realize the use of hydrogen energy at an early stage, it is an effective means to generate as much hydrogen as necessary using the existing industrial infrastructure. For example, city gas is used as a raw material for small and medium-sized on-site fuel cells, and methanol is used as a raw material for fuel cell vehicles, and a steam reforming method utilizing catalytic reaction, a partial oxidation method, or a combination of both. It is conceivable to generate hydrogen by an autothermal method.

  However, since the reforming reaction proceeds at a high temperature, carbon monoxide (CO) and carbon dioxide are generated as by-products other than hydrogen. In the case of a polymer electrolyte fuel cell operating at a low temperature of 100 ° C. or lower, the platinum catalyst used for the electrode is poisoned by carbon monoxide contained in the reformed gas. When poisoning of the platinum catalyst occurs, the hydrogen reaction is inhibited, and the power generation efficiency of the fuel cell is remarkably reduced. Therefore, it is necessary to remove carbon monoxide to 100 ppm or less, preferably 10 ppm or less.

  For this reason, in the hydrogen generator, a shift unit that performs a shift reaction is provided downstream of the reforming unit that performs the reforming reaction, and a selective oxidation unit that performs CO removal is further provided downstream thereof (see, for example, Patent Document 1). ), The CO concentration in hydrogen is reduced to several tens of ppm or less by these CO removing actions, and hydrogen can be supplied to the fuel cell.

  In order to remove carbon monoxide, in the shift section, a shift reaction, that is, carbon monoxide and water vapor are reacted to convert to carbon dioxide and hydrogen, and the carbon monoxide concentration is reduced from several thousand ppm to about 1%. Let

  Furthermore, in the case of a fuel cell that operates at a low temperature of 100 ° C. or lower, such as a polymer electrolyte fuel cell used for in-vehicle use or home use, the reformed gas contains the Pt catalyst used for the electrode. Therefore, before supplying the reformed gas to the fuel cell, it is necessary to remove the CO concentration to 100 ppm or less, preferably 10 ppm or less. For this reason, a CO selective oxidation section filled with a catalyst is provided downstream of the shift section, and CO is methanated or selectively oxidized by adding a small amount of air to remove CO from the reformed gas. In the case of a method of adding a small amount of air, it is necessary to supply oxygen of about 1 to 3 times the carbon monoxide concentration, but hydrogen is also oxidized corresponding to the amount of oxygen. At this time, when the carbon monoxide concentration is high, the amount of hydrogen consumed increases, so the overall efficiency is greatly reduced. Therefore, it is necessary to sufficiently reduce the carbon monoxide concentration at the shift portion.

Conventionally, as the shift catalyst, a copper-zinc catalyst, a copper-chromium catalyst, etc. that can be used at 150 ° C. to 300 ° C. as a medium temperature / low temperature catalyst are used, and an iron-chromium catalyst, etc. Used. These catalysts have been used only in the medium / low temperature catalyst, or in combination with the high temperature catalyst and the medium / low temperature catalyst, depending on applications such as a chemical plant and a fuel cell hydrogen generator.
JP 2002-284503 A

  As described above, when a copper-based catalyst is mainly used, the activity of the catalyst is very high, but it is necessary to activate it by performing a reduction treatment before use. At this time, since heat is generated during the activation treatment, it has been necessary to carry out the treatment for a long time while circulating the reducing gas so as not to exceed the heat-resistant temperature of the catalyst. In addition, since the activated catalyst may be reoxidized and deteriorated due to oxygen contamination when the apparatus is stopped, measures such as prevention of oxidation are necessary. Furthermore, since the low-temperature catalyst has low heat resistance, the catalyst cannot be rapidly heated when the apparatus is started, and measures such as gradually increasing the temperature are required.

  On the other hand, when only a high-temperature catalyst is used, heating at the time of starting becomes easy, but the CO shift reaction (CO shift reaction) is an equilibrium reaction that depends on temperature, and the carbon monoxide concentration is 1% or less. It was difficult to make. Therefore, the efficiency in the CO selective oxidation part connected later has fallen.

  As described above, in the conventional method, there are many problems in applications in which time is required for starting the shift unit, the reactor becomes large, and the operation is repeatedly stopped and operated. Similarly, the reforming catalyst and the carbon monoxide catalyst also have problems of heat resistance and oxygen contamination when the operation is stopped or repeated.

  The present invention takes into consideration the problems of such a hydrogen generator, and has high heat resistance, or has improved the influence of oxygen incorporation when the operation is stopped or repeated, thereby removing the reforming catalyst, shift catalyst, or carbon monoxide. An object of the present invention is to provide a hydrogen generation apparatus, a hydrogen generation method, and a fuel cell power generation system using the same, each having a catalyst.

In order to solve the above-described problem, the first aspect of the present invention includes a reforming unit that reacts a raw material and water with a reforming catalyst to generate a hydrogen-rich gas;
A shift unit having a shift catalyst that reduces carbon monoxide in the hydrogen-rich gas by reacting the generated hydrogen-rich gas with water vapor;
A carbon monoxide removal unit having a carbon monoxide removal catalyst for oxidizing and hydrogen reducing carbon monoxide contained in the gas output from the shift unit,
The reforming catalyst, the shift catalyst, and the carbon monoxide removal catalyst are hydrogen generators that contain a noble metal element or Ni element as an active component and a metal oxide as a support for the active component.

The second aspect of the present invention is the hydrogen generator according to the first aspect of the present invention, wherein the reforming catalyst includes Ru as an active component and Al ₂ O ₃ as a carrier for the active component.

  The third aspect of the present invention is the hydrogen generator according to the first or second aspect of the present invention, wherein the shift catalyst includes Pt as an active component and a composite metal oxide as a support for the active component.

The fourth aspect of the present invention is the hydrogen generator according to the third aspect of the present invention, wherein the composite metal oxide includes a solid solution of CeO ₂ and ZrO ₂ .

  The fifth aspect of the present invention is the hydrogen generator according to any one of the first to fourth aspects, wherein the carbon monoxide removal catalyst includes Ru as an active component and a composite metal oxide as a support for the active component. is there.

The sixth aspect of the present invention is the hydrogen generator according to the fifth aspect of the present invention, comprising a solid solution of Al ₂ O ₃ and TiO ₂ as a carrier for the active component of the carbon monoxide removal catalyst.

According to a seventh aspect of the present invention, the carbon monoxide removing unit includes a first purification unit and a second purification unit connected to the downstream of the first purification unit, and the first purification unit is an active ingredient. The catalyst includes a Pt—Ru alloy and includes Al ₂ O ₃ as a carrier for the active component, and the second purification unit includes Ru as an active component, and Al ₂ O ₃ as the active component carrier. The hydrogen generator according to any one of the first to fourth aspects of the present invention.

The eighth aspect of the present invention is a desulfurization section for removing sulfur components in a raw material containing at least carbon and hydrogen;
Any one of the first to seventh hydrogen generators of the present invention;
And a fuel cell to which hydrogen generated by the hydrogen generator and oxidant gas are supplied.

The ninth aspect of the present invention includes a reforming step of reacting a raw material and water with a reforming catalyst to generate a hydrogen-rich gas;
A shift step of reducing carbon monoxide in the hydrogen-rich gas by using a shift catalyst by reacting the produced hydrogen-rich gas with water vapor;
A carbon monoxide removal step of oxidizing and hydrogen reducing carbon monoxide contained in the gas that has undergone the shift step using a carbon monoxide removal catalyst,
The reforming catalyst, the shift catalyst, and the carbon monoxide removal catalyst include a noble metal element or Ni element as an active component and a metal oxide as a support for the active component.

  According to the present invention, a hydrogen generator, a hydrogen generator having a reforming catalyst, a shift catalyst, or a carbon monoxide removal catalyst, which has high heat resistance, or has improved the influence of oxygen contamination when operation is stopped or repeated A generation method and a fuel cell power generation system using the generation method can be provided.

(Embodiment 1)
(Overall configuration)
The hydrogen generator of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the entire hydrogen generator of the present invention. A raw material supply unit 1 and a water supply unit 2 are connected to a reforming unit 3 filled with a reforming catalyst. The raw material supplied by the raw material supply unit 1 flows out from the reforming unit 3, flows into the shift (transformation) unit 4 filled with the shift catalyst (transformation catalyst), and the gas flowing out from the shift unit 4 uses the CO removal catalyst. It flows into the filled carbon monoxide removal section (selective oxidation section) 5. That is, the hydrogen generator shown in FIG. 1 includes not only the reforming unit 3 but also the shift unit 4 and the purification unit 5. Then, the gas flowing out from the purification unit 5 flows as a product gas through the three-way valve 6, one is led from the hydrogen generator to the fuel cell 7, and the other is led to the burner 8 installed in the vicinity of the reforming unit 3. A road is constructed.

  The burner 8 is provided with a fuel supply unit 9 and an air supply unit 10 for supplying combustion air. Combustion gas in the burner 8 is exhausted from an exhaust port 11 provided in the reforming unit 3. Here, the raw material and fuel supplied from the raw material supply unit 1 and the fuel supply unit 9 are gaseous hydrocarbon fuels such as natural gas (city gas) or LPG, or liquid hydrocarbons such as gasoline, kerosene, or methanol. It is fuel. However, when using liquid fuel, a fuel vaporization unit is required. In this case, it is preferable to configure a vaporizing section that utilizes the heat conduction from the reforming section 3 and the burner 8 and the sensible heat in the combustion exhaust gas.

  In order to adjust the supply amount of the raw material from the raw material supply unit 1, the fuel from the fuel supply unit 9, and the air supply from the air supply unit 1, for example, a method of controlling using a pump or a fan, or a pump Or the method etc. which control with the valve etc. which were installed in the downstream of fans etc. are mention | raise | lifted. However, in FIG. 1, the supply amount (flow rate) regulator is not particularly illustrated, but each supply unit is illustrated as including a flow rate regulator. In addition, the arrow in FIG. 1 has shown the direction of flows, such as a raw material, fuel, and a reactive gas.

(Reforming catalyst)
FIG. 2 is a configuration diagram of the reforming unit 3 that is a component of the hydrogen generator of the present invention.

  An outlet portion 20 through which the reformed gas is discharged is provided in a part of the downstream portion of the reforming catalyst layer 21. In the present embodiment, a reforming catalyst layer 21 that generates a hydrogen-rich reformed gas from a reforming reaction between a hydrocarbon-based raw material and steam, a burner 8 that heats the reforming catalyst layer 21, and a supply to the burner 8 A fuel control valve 23 that controls the flow rate of the fuel to be discharged, and an outlet 20 that is provided downstream of the reforming catalyst layer 21 and collects the flow of the reformed gas.

  Next, the operation and action will be described. The combustion gas generated in the burner 8 heats the reforming catalyst layer 21 and is discharged from the exhaust port 25. The raw material and the steam supplied from the inlet 29 on the upstream side of the reforming catalyst layer 21 are heated by heat exchange with the combustion gas while flowing toward the downstream, and the hydrogen-rich reformed gas is generated by the steam reforming reaction. Is generated and led to the downstream outlet 20.

  Examples of the catalyst used in the reforming catalyst layer 21 include a supported Ni-based catalyst and a supported Ru-based catalyst (see JP 2001-155755 A). In particular, the ruthenium-based reforming catalyst using alumina as a carrier has advantages such as relatively high activity and low carbon / carbon ratio even under the operating conditions of low steam / carbon ratio. (See JP 2001-340759 A).

  In particular, when a Ru-based catalyst is used, it is not affected by a small amount of oxygen. In general, when the hydrogen generator is stopped, the pressure in the reaction chamber decreases as the temperature of the apparatus decreases, and a small amount of external air is mixed. However, according to the hydrogen generator of the present invention, it is not necessary to take measures against a small amount of oxygen, and it is very easy to stop and start the apparatus.

(Shift catalyst)
FIG. 3 is a configuration diagram showing a cross section of the hydrogen generator according to the first embodiment of the present invention. In FIG. 3, 31 is a catalyst body, which is filled in the reaction chamber 32. Reference numeral 33 denotes a reformed gas inlet from which the reformed gas is introduced. A catalyst support net 34 was installed in the reaction chamber 32 so that the reformed gas uniformly contacted the upstream portion of the catalyst body 31, and a space was provided upstream of the catalyst body 31. The reformed gas that has finished the reaction on the catalyst body 31 is discharged from the reformed gas outlet 35.

  In order to keep the reactor at a constant temperature, the outer periphery of the reaction chamber 32 was covered with a heat insulating material 36 made of ceramic wool. Here, the catalyst body 31 is produced by supporting Ce and Pt on a spherical porous alumina pellet having a diameter of 6 mm.

  Next, the principle of this embodiment will be described. The fuel used to generate the reformed gas to be supplied to the hydrogen generator of the present invention includes natural gas, methanol, gasoline, and the like. The reforming method is also steam reforming in which steam is added, or partial modification in which air is added. In this embodiment, the case where a reformed gas obtained by steam reforming natural gas is used will be described.

  The reformed gas produced by mixing steam with natural gas and contacting the reforming catalyst contains carbon dioxide and carbon monoxide as by-products in addition to hydrogen, and the remainder of the steam added before reforming. It is. The composition of the reformed gas varies somewhat depending on the catalyst temperature during reforming, but as an average value excluding steam, about 80% hydrogen, about 10% carbon dioxide, and about 10% carbon monoxide are included. The reforming reaction of natural gas is performed at about 500 to 800 ° C., whereas the shift reaction in which carbon monoxide and water vapor react is performed at about 150 to 300 ° C. It is supplied after passing through a heat exchanger before being cooled.

  The CO shift reaction is a temperature-dependent equilibrium reaction, and the CO concentration can be reduced as the reaction is performed at a lower temperature. On the other hand, when the temperature is lowered, the reaction rate on the catalyst is lowered, so that a catalyst capable of reacting at a low temperature is more effective. Usually, copper shift catalysts such as copper-zinc catalyst and copper-chromium catalyst used as shift catalysts can perform CO shift reaction at a low temperature of about 150 ° C. to 250 ° C., and the CO concentration is several hundred to several thousand. It can be reduced to about ppm. However, after the copper-based catalyst is charged into the reactor, it is necessary to activate it by circulating a reducing gas such as hydrogen or a reformed gas. Since the heat resistance of the copper-based catalyst is as low as around 300 ° C., it is necessary to dilute and supply the reducing gas or to gradually react at a small flow rate so that the heat resistance does not exceed the heat resistant temperature. Further, the content of copper in the catalyst also affects the time required for activation, but a weight ratio of about several tens of percent is necessary to ensure life reliability, and it takes a long time for activation. .

  On the other hand, in the hydrogen generator of the present invention, a noble metal catalyst is used as the catalyst body 31 and has a very high heat resistance as compared with a copper-based catalyst. It is only necessary to carry a few percent of precious metal. For this reason, it can be used by performing an activation treatment with a reducing gas for a short time or simply circulating a reformed gas.

  An outline of the characteristics of the noble metal catalyst used for the catalyst body 31 in the present embodiment is shown in FIG. For comparison, the characteristics of a copper-zinc catalyst that is a low-temperature shift catalyst and an iron-chromium catalyst that is a high-temperature shift catalyst are shown. The noble metal catalyst used in the present embodiment has an intermediate performance between the high temperature catalyst and the low temperature catalyst. A high temperature shift catalyst alone is difficult to reduce the CO concentration to 1% or less, and is often used in combination with a low temperature shift catalyst. The noble metal catalyst of this example is equivalent to a low temperature shift catalyst, and can reduce carbon monoxide to a concentration of about several thousand ppm. Even a noble metal catalyst alone can be applied to a hydrogen generator for a fuel cell.

  In addition, the CO shift reaction is usually performed at a gas flow rate (space velocity SV) per catalyst volume of 1000 or less per hour, and a large amount of catalyst is required to increase the heat capacity. It takes a long time. For this reason, it is conceivable to use heating from the outside of the reaction chamber together with an electric heater or the like, or to raise the temperature of the reformed gas to be supplied to increase the rate of temperature rise. However, since the heat resistant temperature of the copper catalyst is low, rapid heating that is locally high is not desirable. On the other hand, since the hydrogen generator of this example uses a noble metal catalyst with high heat resistance, there is no problem even if a high temperature portion of about 500 ° C. is locally generated. The apparatus can be started quickly.

  In addition, when the apparatus is stopped, the pressure in the reaction chamber decreases with a decrease in the temperature of the apparatus, and a small amount of external air is mixed. For this reason, when the apparatus is repeatedly stopped and started repeatedly over a long period of time, the copper-based catalyst gradually deteriorates. Therefore, a means for preventing oxygen from being mixed is required, and the apparatus becomes complicated. On the other hand, since the noble metal catalyst is used in the hydrogen generation apparatus of this example, it is not necessary to take measures against a small amount of oxygen, and the apparatus can be stopped and started very easily.

  In the present embodiment, the catalyst body 31 is prepared by supporting Ce and Pt on a spherical porous alumina pellet having a diameter of 6 mm. However, the active component is a noble metal element selected from Ru, Pd, and Rh. Even if it is used, it can be used without the activation treatment for a long time like a copper catalyst, and at the same time, there is no problem in heat resistance. Whether the catalyst body is spherical, conical, or foamed, there is no problem as long as the pressure loss with respect to the gas flow is sufficiently small for the application.

  Further, Ce has an effect as a co-catalyst for promoting the shift reaction, and it is preferable to add Ce for the reaction at a low temperature.

  Further, in the present embodiment, the reformed gas obtained by steam reforming natural gas is used, but there is no particular difference as long as the ratio of carbon monoxide and carbon dioxide is slightly changed in other fuels.

  In addition, when a partially reformed gas that adds air instead of water vapor is used, it is necessary to add water before entering the reaction chamber 32 because the proportion of water vapor is small. There is essentially no difference.

(Embodiment 2)
A second embodiment of the present invention will be described. In this embodiment, as shown in FIG. 5, a cordierite honeycomb carrying a noble metal catalyst is used as the catalyst body 311, and most of the operational effects are similar to those of the first embodiment. Therefore, the present embodiment will be described focusing on the different points.

  FIG. 5 is a cross-sectional configuration diagram of the present embodiment. By making the catalyst body 311 into a honeycomb structure, the contact area between the catalyst and the reformed gas can be increased, the volume of the catalyst can be reduced, and the heat capacity can be reduced, so that the time for starting the apparatus can be shortened. In addition, since a noble metal catalyst having high heat resistance is used, even when the amount of catalyst supported on the honeycomb is reduced, the characteristics can be stably maintained for a long time without deterioration.

  In the present embodiment, a honeycomb substrate having a honeycomb shape is used. However, the shape is not limited to the honeycomb shape, and the catalyst can be supported on heat-resistant fibers even if it has a foam shape as long as the pressure loss is small and the contact area between the catalyst and the gas is wide. It doesn't matter.

  In the present embodiment, a cordierite honeycomb is used as the carrier substrate. However, when using a base material with good thermal conductivity, such as a metal honeycomb, the temperature difference from the upstream portion to the downstream portion of the catalyst body is reduced, and the reaction heat on the catalyst body 311 can be quickly dissipated, Stable characteristics can be obtained.

(Embodiment 3)
A third embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 6, the CO shift catalyst body is divided into a first catalyst body 321 made of a noble metal catalyst and a second catalyst body 322 made of a copper-based catalyst. Most of them are similar to the first embodiment. Therefore, the present embodiment will be described focusing on the different points.

  FIG. 6 is a cross-sectional configuration diagram of the present embodiment. As the first catalyst body 321, a catalyst body in which a noble metal catalyst is supported on a cordierite honeycomb is used, and the reformed gas temperature supplied so as to react at about 300 ° C. is controlled. As the second catalyst body 322, a copper catalyst supported on a cordierite honeycomb is used and reacted in a temperature range of about 150 ° C. to 250 ° C. Usually, about 90% of carbon monoxide reacts in the upstream portion of the CO shift catalyst body. Further, when the temperature is raised when the apparatus is started up, the upstream portion of the CO shift catalyst body is exposed to the high-temperature reformed gas. For this reason, catalyst deterioration is more likely to proceed upstream of the shift catalyst. Here, in the hydrogen generator of the present invention, since the noble metal catalyst having high heat resistance is used for the first catalyst body 321, the above-described influence can be eliminated. Moreover, since the copper-based catalyst is used for the second catalyst body 322, the CO concentration can be lowered to several hundred to several thousand ppm equivalent to the case where the copper-based catalyst is used alone. In addition, when a high temperature shift catalyst is used instead of the noble metal catalyst of the first catalyst body 321, it is possible to similarly suppress the deterioration of the low temperature shift catalyst. Before and after the temperature is required, in order to use in combination with the low temperature shift catalyst of the second catalyst body 322 as in this example, a heat exchanger for cooling is required between the two catalysts, and the apparatus is large. Turn into.

(Embodiment 4)
A fourth embodiment of the present invention will be described. In the present embodiment, as shown in FIG. 7, an air supply unit is provided on the upstream side of the catalyst body 331, and most of the operational effects are similar to those of the first embodiment. Therefore, the present embodiment will be described focusing on the different points.

  FIG. 7 is a cross-sectional configuration diagram of the present embodiment. When the CO shift unit is connected to the reforming unit and the carbon monoxide removal unit, the CO shift unit takes the most time to increase the temperature because the heat capacity is larger than that of the reforming unit and the carbon monoxide removal unit at the time of starting. Need. An electric heater or heating by combustion can be considered, but it requires extra energy and is not efficient. Here, in this embodiment, an air supply unit is provided on the upstream side of the catalyst body 331. By supplying air so that the oxygen concentration is about 1 to 2%, Carbon oxide can be burned on the shift catalyst and heated. Since the reformed gas while the temperature of the shift catalyst is not sufficiently raised has a high carbon monoxide concentration and cannot be supplied to the fuel cell, it does not require extra energy by burning it and is efficient. The shift portion can be heated. In addition, the shift catalyst can be stably operated by supplying air when the temperature of the shift catalyst decreases even during steady operation. In the case of a copper-based catalyst, it is not preferable to add air to the shift unit because the catalyst is deteriorated. However, since a noble metal catalyst is used for the catalyst body 331 in this embodiment, there is no deterioration due to oxidation.

  Further, by detecting the temperature of the catalyst body 331 and controlling the amount of air so as to keep the catalyst temperature constant, a more stable operation is possible.

  In addition, consumption of the supplied oxygen is an oxidation reaction with a high reaction rate, and is completed in the upstream portion of the catalyst body 331, and oxygen does not reach the downstream portion. Therefore, in this embodiment, only the noble metal catalyst is used for the catalyst body 331. However, even if a copper-based catalyst is used in the downstream portion, the catalyst body 331 is not deteriorated, and higher characteristics can be obtained.

(Embodiment 5)
A fifth embodiment of the present invention will be described. In the present embodiment, a carbon monoxide removal unit (CO purification unit) using a noble metal catalyst is connected to the hydrogen generator shown in Embodiment 1 in the same manner as a reforming unit using a noble metal catalyst.

  Usually, a catalyst such as Ni or a catalyst mainly composed of Pt or Ru is used as a reforming catalyst such as natural gas, but a transition metal-based catalyst such as Ni is activated by reduction treatment in advance. Since it is necessary to activate again after oxidation after the apparatus is stopped, it is necessary to pay attention to air contamination. On the other hand, noble metal catalysts such as Ru require almost no activation treatment, and there is no problem even if measures against air contamination are not taken after the apparatus is stopped. In addition, the carbon monoxide removing section uses a noble metal catalyst such as a ruthenium catalyst or a platinum catalyst, thereby eliminating the need for an activation treatment with a reducing gas. Therefore, by connecting the reforming unit equipped with the noble metal catalyst and the carbon monoxide removal unit to the shift catalyst equipped with the noble metal catalyst, the influence of air mixing when the system is repeatedly stopped and started as a whole system. And stable performance can be obtained for a long time.

Example 1
A spherical porous alumina pellet having a diameter of 6 mm was impregnated with a mixed solution of cerium nitrate and platinum salt, and calcined at 500 ° C. in an electric furnace to produce a catalyst body 331. The catalyst body 331 is filled in the reaction chamber 32 of the hydrogen generator shown in FIG. 3, and the reformed gas, which is 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remaining hydrogen, is cooled to 350 ° C. The reformed gas inlet 33 was introduced at a flow rate of 10 liters per minute. When the composition of the reaction gas discharged from the reformed gas outlet 35 was measured by gas chromatography after removing the water vapor, the carbon monoxide concentration became 3500 ppm 30 minutes after the introduction of the reformed gas. Thereafter, after the inside of the reaction chamber 32 was replaced with nitrogen, air was supplied, reformed gas was supplied again, and the composition of the reaction gas was measured. As a result, the carbon monoxide concentration was 3400 ppm. Further, the same operation was repeated 50 times, and the characteristics were examined in the same manner. As a result, the carbon monoxide concentration was 3600 ppm.

(Example 2)
After reacting the reformed gas once in Example 1, the supply of the reformed gas was stopped, and the hydrogen generator was cooled to room temperature. Thereafter, the reformed gas first cooled to a predetermined temperature is supplied again, and when the catalyst temperature rises to 300 ° C., the supplied reformed gas temperature is set to 350 ° C., and the reaction gas discharged from the reformed gas outlet 35 is changed. It was measured. In order to know the time required for the start-up, the time until the CO concentration fell below 5000 ppm was measured. When the temperature of the reformed gas supplied first was 350 ° C., 400 ° C., 450 ° C., and 500 ° C., the rise time of the apparatus was 29 minutes, 25 minutes, 18 minutes, and 12 minutes, respectively.

Example 3
The alumina powder was impregnated with a mixed solution of a cerium nitrate solution and a platinum salt and fired at 500 ° C. in an electric furnace. This was dispersed in water to form a slurry, and supported on a cordierite honeycomb of 400 cells per square inch to obtain a catalyst body 311. When the catalyst body 311 is installed in the hydrogen generator shown in FIG. 5, the reformed gas is supplied from the reformed gas inlet 13 and the reaction gas discharged from the reformed gas outlet 15 is measured in the same manner as in Example 1. The carbon monoxide concentration was 2800 ppm. Moreover, when the reformed gas of 350 degreeC was supplied similarly to Example 2 and the time until CO density | concentration fell below 5000 ppm was measured, it was 20 minutes.

Example 4
The same cordierite honeycomb as used in Example 3 was divided into two in the length direction. One of these honeycombs carries the platinum catalyst slurry used in Example 3 as a first catalyst body, and the other carries a slurry of copper-zinc catalyst powder as a second catalyst body. . These catalyst bodies were installed in the hydrogen generator shown in FIG. When the reformed gas cooled to 350 ° C. was supplied and the reaction gas discharged from the reformed gas outlet 26 was measured in the same manner as in Example 1, the carbon monoxide concentration was 1000 ppm. Thereafter, the supply of the reformed gas was stopped, and the hydrogen generator was cooled to room temperature. Further, the reformed gas that has been first cooled to a predetermined temperature is supplied again, and when the catalyst temperature rises to 300 ° C., the supplied reformed gas temperature is set to 350 ° C., and the reaction gas discharged from the reformed gas outlet 35 is It was measured. The time until the CO concentration fell below 5000 ppm was measured. When the temperature of the reformed gas supplied first was 350 ° C., 400 ° C., 450 ° C., and 500 ° C., the rise time of the apparatus was 27 minutes, 23 minutes, 16 minutes, and 10 minutes, respectively. The initial reformed gas temperature was set to 500 ° C., and 50 times of repeated startups were carried out. Then, the reformed gas at 350 ° C. was supplied again, and the CO concentration was measured to be 1050 ppm.

(Example 5)
A spherical porous alumina pellet having a diameter of 6 mm was impregnated with a mixed solution of cerium nitrate and platinum salt, and calcined at 500 ° C. in an electric furnace to produce a catalyst body 331. The catalyst body 331 is filled in the reaction chamber 32 of the hydrogen generator shown in FIG. 7, and the reformed gas, which is 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remaining hydrogen, is cooled to 350 ° C. The reformed gas inlet 333 was introduced at a flow rate of 10 liters per minute. At this time, air was supplied from the air supply unit 37 so that the oxygen concentration was 2%. When the catalyst temperature rose to 300 ° C., the air supply was stopped and the reaction gas discharged from the reformed gas outlet 35 was measured. It was 15 minutes when time until CO density | concentration at this time fell below 5000 ppm was measured. Subsequently, the system was started up 50 times by the same method, a reformed gas at 350 ° C. was supplied, and the CO concentration was measured and found to be 3500 ppm.

(Comparative Example 1)
A copper-zinc catalyst having a diameter of 6 mm is charged into the reaction chamber 32 of the hydrogen generator shown in FIG. 3 in the same manner as in Example 1, and 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remainder is hydrogen. When the gas was cooled to 200 ° C. and introduced at a flow rate of 10 liters per minute from the reformed gas inlet 33, the catalyst temperature temporarily increased to 500 ° C. After the reduction was completed and the catalyst temperature decreased, the carbon monoxide concentration did not fall below 3% even when the temperature of the reformed gas supplied was changed.

(Comparative Example 2)
A copper-zinc catalyst having a diameter of 6 mm is charged into the reaction chamber 32 of the hydrogen generator shown in FIG. 3 in the same manner as in Example 1, and 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remainder is hydrogen. When the gas was cooled to 200 ° C. and introduced at a flow rate of 1 liter per minute from the reformed gas inlet 33, the catalyst temperature reached a steady state at 290 ° C., and the activation was completed and the catalyst temperature decreased to 50 ° C. It took time. Thereafter, the reaction gas discharged from the reformed gas outlet 35 was measured at a reformed gas flow rate of 10 liters per minute and found to be 1000 ppm. Then, after replacing the inside of the reaction chamber 32 with nitrogen, air was supplied, the above activation treatment was performed again for 50 hours, and the reaction gas composition was measured in the same manner. As a result, the carbon monoxide concentration was 8000 ppm. there were. Further, the same operation was repeated 5 times, and the characteristics were similarly examined. As a result, the CO concentration did not become 2% or less even when the temperature condition was changed.

(Comparative Example 3)
After the activation of the catalyst in Comparative Example 2, the reformed gas was stopped and the hydrogen generator was cooled to room temperature. Thereafter, the reformed gas first cooled to a predetermined temperature was supplied again, and when the catalyst temperature rose to 200 ° C., the supplied reformed gas temperature was set to 250 ° C., and the reaction gas discharged was measured. The time until the CO concentration fell below 5000 ppm was measured. When the temperature of the reformed gas supplied first was 250 ° C., 300 ° C., 350 ° C., and 400 ° C., the rise time of the apparatus was 50 minutes, 40 minutes, 30 minutes, and 20 minutes, respectively. Further, when the temperature of the reformed gas was set to 350 ° C. and started up 50 times and the characteristics were examined, the CO concentration did not become 2% or less even when the temperature condition was changed.

(Comparative Example 4)
A copper-zinc catalyst having a diameter of 6 mm was charged into the reaction chamber 32 of the hydrogen generator shown in FIG. 7 as in Example 5, and 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remainder was hydrogen. The quality gas was cooled to 250 ° C. and introduced from the reformed gas inlet 333 at a flow rate of 10 liters per minute. At this time, air was supplied from the air supply unit 37 so that the oxygen concentration was 2%. When the catalyst temperature rose to 200 ° C., the air supply was stopped and the reaction gas discharged from the reformed gas outlet 35 was measured. It was 15 minutes when time until CO density | concentration at this time fell below 5000 ppm was measured. Subsequently, the same method was used to start up 50 times, and the characteristics were examined. As a result, even if the temperature was changed, the CO concentration did not become 2% or less.

  As is clear from the comparison of the evaluation results of the apparatus of the above example and the comparative example, according to the present invention, the start-up time of the apparatus can be shortened, and the influence of oxygen mixing when the operation of the apparatus is repeatedly stopped and activated is suppressed. As a result, a hydrogen generator that operates stably over a long period of time could be provided.

In order to obtain sufficient catalytic activity, it is necessary to make Pt particles small and have many active sites. For this purpose, Pt is supported on a metal oxide having a BET specific surface area of 10 m ² / g or more. Is preferred. Here, the BET specific surface area is a specific surface area determined by a known measurement method performed by adsorbing nitrogen to a powder. Further, the upper limit of the BET specific surface area is not particularly limited, and high activity can be obtained similarly even if it is 100 to 200 m ² / g or several hundred m ² / g. The metal oxide and / or composite metal oxide supporting Pt is selected from the group consisting of Mg, Al, Si, Ca, Ti, Cr, Fe, Zn, Y, Zr, Nb, Mo, Sn, Ba, and a lanthanoid The at least one oxide is preferred.

  As these metal oxides and composite metal oxides, it is preferable to use one selected from alumina, silica, silica alumina, zirconia, titania and zeolite from the viewpoint that particularly high activity can be obtained. This is because these materials are relatively stable to acids and alkalis, and are not changed by Pt salts that are acidic or alkaline. When the metal oxide or the like is changed by the Pt salt, Pt is buried in the metal oxide or the like, and the activity is lowered.

  In the case of a composite metal oxide, it is more effective if Ce is composited. Ce has the effect of suppressing the methanation reaction on the Pt catalyst and improving the low-temperature activity for the CO shift reaction. The larger the amount of Ce added, the better. Therefore, cerium oxide may be mainly used as the metal oxide. The Ce raw material is not particularly limited as long as an oxide such as nitrate, acetate and hydroxide can be obtained.

  In addition, since heat resistance of cerium oxide alone is relatively low, heat resistance is improved by combining Zr. That is, a composite metal oxide containing Ce and Zr is preferable. A method of combining Zr with cerium oxide is not particularly limited, and for example, a coprecipitation method, a sol-gel method, an alkoxide method, or the like can be used. Further, Zr may be incorporated into cerium oxide or Ce may be incorporated into zirconium oxide.

  Further, when one kind selected from Pd, Rh, and Ru is added in an amount corresponding to 0.1 to 0.5% by weight of Pt, higher activity can be obtained. Since these noble metal elements promote the methanation reaction, it is difficult to obtain high performance as a CO shift catalyst by itself, but by combining with Pt, the performance of the Pt catalyst can be improved. If these precious metals are added in an amount of more than 0.5% by weight of Pt, the characteristics of the precious metals added will appear, and the methanation reaction will become remarkable, which is not preferred. I can't see it.

Most preferred as the shift catalyst is a catalyst in which Pt is supported on a solid solution of CeO ₂ and ZrO ₂ which are composite metal oxides.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a schematic diagram showing the configuration of the hydrogen generator according to Embodiment 6 of the present invention. In FIG. 8, 41 is a selective oxidation catalyst layer, which is a cordierite honeycomb coated with a mixture of a first catalyst supporting Pt on alumina and a second catalyst supporting Ru on alumina.

  This selective oxidation catalyst layer 41 is installed in the reaction chamber 42. The reformed gas supplied from the reformed gas inlet 43 is sent to the reaction chamber 42 together with the air supplied by the air pump 44. Air is supplied from the air pump 44 so that the oxygen concentration is about 1 to 3% by volume with respect to the CO concentration, for example, when the CO concentration is 1% by volume.

  The reformed gas mixed with oxygen is sent to the reformed gas outlet 46 after CO is removed by the selective oxidation catalyst layer 41. A diffusion plate 45 is installed upstream of the selective oxidation catalyst layer 41 so that the reformed gas flows uniformly. Further, in order to keep the reactor at a constant temperature, the outer periphery of the necessary portion is covered with a heat insulating material 47 made of ceramic wool.

  Next, the operation principle of the present invention will be described. As the selective oxidation catalyst, conventionally, a catalyst having Pt, Pd, Ru, Rh or the like as a catalytic active component as a CO selective oxidation catalyst (first catalyst in the present invention), Pd, Ru, Rh, Ni or the like as a CO methanation catalyst. Is used as a catalyst active component (second catalyst in the present invention).

  The catalyst in the case of using the first catalyst alone (a), the case of using the second catalyst alone (b), and the case of mixing both the first catalyst and the second catalyst of this embodiment (c) FIG. 9 shows the relationship between the temperature and the CO concentration in the reformed gas after passing through the selective oxidation catalyst layer.

  Here, a catalyst having 1% by weight of Pt dispersed in alumina supported on the first catalyst, and a catalyst having 1% by weight of Ru supported on alumina dispersed on the second catalyst layer, respectively, from cordierite. A honeycomb-shaped carrier substrate coated with the above was used. The reaction conditions are all the same except that the selective oxidation catalyst layer 41 is different.

  From the air pump 44, 2 to 6 times as much oxygen as the stoichiometric volume ratio required for the oxidation reaction of CO contained in the reformed gas was supplied.

  FIG. 9 shows that when the first catalyst is used alone, CO in the reformed gas is selectively oxidized and the CO concentration is reduced to several ppm, but due to the influence of the reverse shift reaction between carbon dioxide and hydrogen, It shows that the CO concentration increases exponentially as the temperature increases. This means that the temperature range in which the CO concentration can be sufficiently reduced is limited to about several tens of degrees Celsius. However, since the catalyst temperature rises due to the reaction heat, a high degree of control is required to maintain the optimum temperature.

  FIG. 9 shows that the CO concentration can be removed up to several ppm in a relatively high temperature region when the second catalyst is used alone. This is because Ru promotes the methanation reaction of CO. However, as the temperature rises, the methanation reaction of carbon dioxide proceeds exponentially and the hydrogen concentration decreases. Decreases.

  Therefore, the temperature range in which the methane concentration can be suppressed to 1 to 2% by volume or less with a small influence on the efficiency of the system is limited to about several tens of degrees Celsius. However, since the methanation reaction is also an exothermic reaction, advanced control is required to maintain the optimum temperature.

  On the other hand, FIG. 9 shows that CO can be removed to a low concentration over a wide temperature range when both the first catalyst and the second catalyst are mixed. The temperature range in which the first catalyst can remove CO to several ppm is about several tens of degrees Celsius, but CO can be reduced in a temperature range of about 100 deg as long as the CO concentration level is several hundred ppm. Further, the second catalyst functions substantially only in a narrow temperature range of about several tens of degrees centigrade for high concentration CO of about 0.5 to 1% by volume, but for low concentration CO of about several hundred ppm. Thus, CO can be removed to several ppm or less in a temperature range of 100 deg.

  Therefore, because of the combined effect of the first catalyst and the second catalyst, CO generated by the reverse shift reaction can be removed by the methanation reaction, so that CO can be removed to a level of several ppm over a wide temperature range.

  The temperature range in which CO can be efficiently removed is higher than the temperature at which CO can be removed up to several hundred ppm with the first catalyst, and the methanation reaction of carbon dioxide proceeds with the second catalyst so as to affect the efficiency of the system. The temperature range is below the starting temperature. This preferable temperature range varies depending on the active component of the catalyst, the supported amount, etc., but is generally 60 to 350 ° C., preferably 80 to 250 ° C.

  This embodiment is a preferable embodiment when the CO concentration in the reformed gas is 0.1 to 2% by volume. As the first catalyst and the second catalyst, a catalyst in which 0.1 to 10% by weight of a catalytically active component is dispersed and supported on a carrier is preferably used.

As a catalytically active component used for the first catalyst,
(Chemical formula 1)
2CO + O ₂ → 2CO ₂
That is selectively active in the above reaction, that is, among hydrogen and CO in the reformed gas, those that are active only in the oxidation reaction of CO or highly active in the oxidation reaction of CO are used. It is done.

  Examples of such materials include noble metals such as Pt, Pd, Ru, and Rh. In particular, it is preferable to contain at least Pt or Ru as a catalytically active component.

Moreover, as a catalyst active component used for a 2nd catalyst,
(Chemical formula 2)
CO + 3H ₂ → CH ₄ + H ₂ O
One that is selectively active in the reaction, ie, CO2 and CO in the reformed gas that are only active in the CO hydrogenation reaction or that are highly selective in the CO hydrogenation reaction Is used. Examples of such materials include metals such as Ru, Rh, Pd, and Ni. In particular, it is preferable to contain at least Ru, Rh, or Ni as a catalytically active component.

  The active component carrier of the catalyst used for the first catalyst and the second catalyst is not particularly limited as long as it can support the catalytic active component in a highly dispersed state. Examples of such materials include alumina, silica, silica alumina, 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 present embodiment, each catalytic active component is previously supported on a powdery carrier, and the first catalyst and the second catalyst are formed of separate particles. The first catalyst and the second catalyst are physically separated. The cordierite honeycomb, which is the carrier base material, was coated with the mixed material as long as the first catalyst and the second catalyst can exhibit the functions of CO selective oxidation and CO hydrogenation reaction, respectively.

  That is, as a composite method, the same effect can be obtained by first coating the support base material with the first catalyst and then coating the second catalyst to form a composite layer. Alternatively, the first catalyst and the second catalyst in the form of pellets may be prepared and mixed.

  Even if the average value of the composition of the combined selective oxidation catalyst is the same as that of the present embodiment, for example, when Pt and Ru are simultaneously supported on an alumina support, noble metals may be alloyed. In this case, the activity for CO selective oxidation is improved, but the activity for the CO methanation reaction is not so high. This is because the characteristics of the respective catalytic active components are averaged by alloying Pt and Ru. Since the alloyed catalyst can be used as the first catalyst, higher performance can be obtained by mixing a Ru catalyst or the like as the second catalyst.

  The composite ratio of the catalytically active components of the first catalyst and the second catalyst is such that the CO concentration after passing through the selective oxidation catalyst layer is 0.01-100 ppm, preferably 0.01-20 ppm, depending on the reaction conditions used. A person skilled in the art may choose. Usually, high performance can be obtained when the ratio of the first catalyst is in the range of 10 wt% to 90 wt%.

  In addition, there are catalysts such as Ru catalysts that have both selective oxidation and methanation performances, and intermediate performance between the first catalyst and the second catalyst, but the CO selective oxidation reaction and the CO selective methanation reaction. However, since the optimum composition differs, high characteristics can be obtained by combining Ru catalysts having different compositions or preparation conditions as the first catalyst and the second catalyst.

(Embodiment 7)
Next, an embodiment of the hydrogen purification apparatus in which the selective oxidation catalyst layer is divided into a plurality of stages and an oxygen supply unit for introducing a gas containing oxygen into each of the divided catalyst layers is provided. The points different from the sixth embodiment will be mainly described.

  When the volume of the CO shift catalyst layer for reacting CO with water vapor is reduced or the CO shift catalyst layer is omitted for the purpose of reducing the size of the hydrogen generation system, the CO concentration becomes higher and the one-stage selective oxidation catalyst layer In this case, CO may not be sufficiently removed. The amount of air introduced at a time has an upper limit in terms of the influence of reaction heat and safety, but when the CO concentration is high, an oxygen concentration higher than this upper limit may be required.

  In the present embodiment, the selective oxidation catalyst layer is divided into a plurality of stages, preferably 2 to 3 stages, and an oxygen supply unit for introducing a gas containing oxygen is provided on the upstream side of each catalyst layer. Therefore, air can be supplied twice or more, and CO can be efficiently removed even when the CO concentration is relatively high. This embodiment is a preferred embodiment when the CO concentration in the reformed gas is 1 to 3% by volume.

  FIG. 10 is a schematic diagram showing the configuration of the hydrogen purification apparatus according to Embodiment 7 of the present invention. In FIG. 10, the selective oxidation catalyst layer is divided into two stages of a first purification catalyst layer 411 and a second purification catalyst layer 412, and a second air supply unit 420 is installed in the middle thereof.

  Air is supplied from the first air supply unit 419 so that the oxygen concentration is 1 to 2% by volume of the whole, and the oxygen concentration is 0.5 to 1.5% by volume of the whole from the second air supply unit 420. It is preferable that air is supplied.

  When the CO concentration is high, oxygen is insufficient only with the air supplied from the first air supply unit 419, so that the oxidation reaction does not proceed sufficiently when the reformed gas passes through the first catalyst layer 411. However, since air is supplied again from the second air supply unit 420, CO oxidation further proceeds when passing through the second purification catalyst layer 412, and the CO concentration is further reduced to several ppm level.

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

(Example 6)
Alumina supporting Pt as the first catalyst (Pt loading is 1% by weight) and alumina supporting Ru as the second catalyst (Ru loading is 1% by weight) are mixed in a ratio of 50% by weight. A cordierite honeycomb having a length of 100 mm and a length of 50 mm was coated.

  The obtained selective oxidation catalyst layer 41 is placed in a reaction chamber 42 of a hydrogen generator as shown in FIG. 8, and CO is 1% by volume, carbon dioxide is 15% by volume, water vapor is 15% by volume, and the remainder is hydrogen. The reformed gas was introduced at a flow rate of 10 liters per minute from the reformed gas inlet.

  Air was supplied from the air supply unit 4 so that the oxygen concentration was 2% by volume of the whole. The reformed gas was cooled in front of the reformed gas inlet 43, and the reformed gas temperature was changed to 80 to 250 ° C. for reaction. The composition of the gas discharged from the reformed gas outlet 46 was measured by gas chromatography after removing water vapor, and the CO concentration and the methane concentration were calculated. The results are shown in Table 1.

(Example 7)
As shown in FIG. 10, the selective oxidation catalyst layer is divided into a first purification catalyst 411 and a second purification catalyst layer 412, a second air supply unit 420 is disposed between them, and CO is 2% by volume. A reformed gas having 14% by volume of carbon dioxide, 15% by volume of water vapor, and hydrogen remaining was introduced from the reformed gas inlet 14 at a flow rate of 10 liters per minute. Air was supplied from the first air supply unit 419 and the second air supply unit 420 so that the oxygen concentration was 2% by volume of the whole.

  The reformed gas was cooled in front of the reformed gas inlet 414, and the reformed gas temperature was changed to 80 to 250 ° C. for reaction. The composition of the gas discharged from the reformed gas outlet 417 was measured by gas chromatography after removing water vapor, and the CO concentration and methane concentration were calculated. The results are shown in Table 2.

In addition, by providing a heat radiating part or a cooling part between the catalyst layers, the temperature of the catalyst layer on the downstream side can be optimized by removing the heat generated on the upstream side.
(Example 8)
The same operation as in Example 6 was performed, except that the second catalyst was replaced with one using Rh instead of Ru. The results are shown in Table 3.

Example 9
The same operation as in Example 6 was performed except that the second catalyst was replaced with one using Ni instead of Ru. The results are shown in Table 4.

(Comparative Example 5)
The same operation as in Example 6 was performed except that the second catalyst was removed. The results are shown in Table 5.

(Comparative Example 6)
Table 6 shows the results of the same operations as in Example 6 except that the first catalyst was removed.

(Comparative Example 7)
Pt and Ru were each supported on alumina at a ratio of 0.5% by weight and coated on a cordierite honeycomb having a diameter of 100 mm and a length of 50 mm to produce a selective oxidation catalyst layer. Table 7 shows the results obtained when the selective oxidation catalyst layer was subjected to the same operation as in Example 6.

  As is apparent from the above description, according to the present invention, it is possible to provide a hydrogen generator capable of allowing the selective oxidation catalyst layer to function in a wide temperature range and stably removing CO. .

  In the seventh embodiment, an example in which the first purification catalyst layer 411 uses alumina supporting Pt and the second purification catalyst layer 412 uses alumina supporting Ru is described. The case where alumina supporting a Pt—Ru alloy is used in the catalyst layer 411 and the case where alumina supporting Ru is used in the second purification catalyst layer 412 is preferable for the same reason as described in the sixth embodiment. .

  As shown in FIG. 8, when a single-layer selective oxidation catalyst layer is used, various catalysts can be used as the selective oxidation removal catalyst for CO. Although a catalyst in which ruthenium and an alkali metal compound and / or an alkaline earth metal compound are supported on the refractory inorganic oxide carrier described in JP-A-9-131553 can be suitably used, it is described in JP-A-2001-155755. In particular, a carrier made of a solid solution of titania and alumina carrying ruthenium, or a carrier made of a solid solution of titania and alumina carrying ruthenium, and an alkali metal and / or an alkaline earth metal, in particular. Is preferred.

  In addition, the selective oxidation catalyst layer may be a single layer or two layers, and the active component carrier of the catalyst may be a metal composite oxide other than the above.

In the above description, the active component of the preferred catalyst and the carrier supporting the active component in each of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst have been described. The combination having is most preferred. That is, the active component of the reforming catalyst includes Ru, the carrier thereof includes Al ₂ O ₃ , the active component of the shift catalyst includes Pt, the carrier includes a solid solution of CeO ₂ and ZrO ₂ , In the case where the carbon monoxide removal catalyst is composed of a part, the active component contains Ru, the carrier contains a solid solution of Al ₂ O ₃ and TiO _2, and the carbon monoxide removal catalyst is the first purification unit. And the second purification unit, the first purification unit includes a Pt—Ru alloy as an active component, Al ₂ O ₃ as a carrier thereof, and the second purification unit includes Ru as an active component. A configuration containing Al ₂ O ₃ as the carrier is most preferable.

  According to the hydrogen generation apparatus and the hydrogen generation method of the present invention, in the reforming catalyst, shift catalyst, or carbon monoxide removal catalyst, heat resistance is increased, or oxygen is mixed when operation is stopped or repeated. This is useful as a fuel cell power generation system.

Schematic configuration diagram of a hydrogen generator for carrying out a method for starting a hydrogen generator according to the present invention Configuration diagram of a hydrogen generator according to an embodiment of the present invention The block diagram which showed the cross section of the hydrogen generator which is one embodiment of this invention The figure which showed the relationship between the operating temperature of the shift catalyst body used with the hydrogen generator which is one embodiment of this invention, and the carbon monoxide density | concentration after a catalyst passage The block diagram which showed the cross section of the hydrogen generator which is one embodiment of this invention The block diagram which showed the cross section of the hydrogen generator which is one embodiment of this invention The block diagram which showed the cross section of the hydrogen generator which is one embodiment of this invention Schematic which shows the structure of the hydrogen generator which concerns on one embodiment of this invention The figure which shows the characteristic of the 1st catalyst of the selective oxidation catalyst layer used for the selective oxidation catalyst layer used for the hydrogen generator which concerns on one embodiment of this invention, and a 2nd catalyst Schematic which shows the structure of the hydrogen generator which concerns on one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material supply part 2 Water supply part 3 Reforming part 4 Shift part 5 Selective oxidation part 6 Three-way valve 7 Fuel cell 8 Burner 9 Fuel supply part 10 Air supply part 11 Exhaust port

Claims (9)

A reforming unit that reacts a raw material and water with a reforming catalyst to generate a hydrogen-rich gas;
A shift unit having a shift catalyst that reduces carbon monoxide in the hydrogen-rich gas by reacting the generated hydrogen-rich gas with water vapor;
A carbon monoxide removal unit having a carbon monoxide removal catalyst for oxidizing and hydrogen reducing carbon monoxide contained in the gas output from the shift unit,
The reforming catalyst, the shift catalyst, and the carbon monoxide removal catalyst each include a noble metal element or Ni element as an active component, and a metal oxide as a support for the active component. The hydrogen generating apparatus according to claim 1, wherein the reforming catalyst includes Ru as an active component and Al ₂ O ₃ as a support for the active component.   The hydrogen generating apparatus according to claim 1 or 2, wherein the shift catalyst includes Pt as an active component and a composite metal oxide as a support for the active component. The hydrogen generator according to claim 3, wherein the composite metal oxide includes a solid solution of CeO ₂ and ZrO ₂ .   The hydrogen generator according to any one of claims 1 to 4, wherein the carbon monoxide removal catalyst includes Ru as an active component and a composite metal oxide as a support for the active component. The hydrogen generator according to claim 5, comprising a solid solution of Al ₂ O ₃ and TiO ₂ as a carrier for the active component of the carbon monoxide removal catalyst. The carbon monoxide removal unit includes a first purification unit and a second purification unit connected to the downstream of the first purification unit, and the first purification unit includes a Pt—Ru alloy as an active component, has a catalyst containing Al ₂ O ₃ as a carrier for the active ingredient, the second purification member includes Ru as active ingredient, including for Al ₂ O ₃ carrier of the active ingredient, according to claim 1 5. The hydrogen generator according to any one of 4 above. A desulfurization section for removing sulfur components in the raw material containing at least carbon and hydrogen;
A hydrogen generator according to any one of claims 1 to 7;
And a fuel cell to which hydrogen generated by the hydrogen generator and oxidant gas are supplied. A reforming step of reacting the raw material and water with a reforming catalyst to generate a hydrogen-rich gas;
A shift step of reducing carbon monoxide in the hydrogen-rich gas by using a shift catalyst by reacting the produced hydrogen-rich gas with water vapor;
A carbon monoxide removal step of oxidizing and hydrogen reducing carbon monoxide contained in the gas that has undergone the shift step using a carbon monoxide removal catalyst,
The reforming catalyst, the shift catalyst, and the carbon monoxide removal catalyst include a noble metal element or Ni element as an active component, and a metal oxide as a support for the active component.

Images