JP5009556B2 - Dehydrogenation / hydrogen addition catalyst and hydrogen supply device using the same - Google Patents

Description

The present invention relates to a dehydrogenation / hydrogen addition catalyst for a supply device for supplying hydrogen to an engine or fuel cell such as an automobile or a distributed power source using hydrogen, and a hydrogen supply device using the same.

  As global warming due to carbon dioxide and the like becomes serious, hydrogen is attracting attention as an energy source for the next generation instead of fossil fuels. In addition, cogeneration of power generation facilities has attracted attention in order to promote energy saving by effectively using energy and reducing CO2 emissions. In recent years, fuel cell power generation systems that generate power using hydrogen have been rapidly developed as a power source for various uses such as automobiles, household power generation facilities, vending machines, and portable devices. A fuel cell generates electricity when hydrogen and oxygen are reacted to form water, and can be used for hot water supply and air conditioning using thermal energy generated at the same time. In addition to fuel cells, internal combustion engines such as microturbines and microengines are also being developed.

  On the other hand, a hydrogen transportation, storage, and supply system that is indispensable for using hydrogen as a fuel has become a major issue. Since hydrogen is a gas at room temperature, it is difficult to store and transport compared to liquids and solids. Moreover, hydrogen is a flammable substance, and there is a risk of explosion when it is mixed with air at a predetermined mixing ratio.

  As disclosed in Patent Document 1, hydrogen is generated by adding water vapor to a hydrocarbon fuel, and this hydrogen is stored in a hydrogen storage alloy and released at start-up, as disclosed in Patent Document 1. There is a power generation system that is added to fuel, hydrodesulfurized, and supplied to a fuel cell.

  In recent years, organic hydride systems using hydrocarbons such as cyclohexane and decalin have attracted attention as a hydrogen storage method that is excellent in safety, transportability, and storage capacity. Since these hydrocarbons are liquid at room temperature, they are excellent in transportability.

  For example, benzene and cyclohexane are cyclic hydrocarbons having the same carbon number, but benzene is an unsaturated hydrocarbon in which the bonds between carbons are double bonds, whereas cyclohexane is a saturated hydrocarbon having no double bonds. Hydrogen. Cyclohexane is obtained by the hydrogenation reaction of benzene, and benzene is obtained by the dehydrogenation reaction of cyclohexane. That is, hydrogen can be stored and supplied by utilizing hydrogenation and dehydrogenation of these hydrocarbons.

  As disclosed in Patent Documents 2, 3, and 4, there is a method in which cyclohexane is sprayed onto a high-temperature catalyst layer by a sprayer to perform a dehydrogenation reaction, and a product hydrogen and benzene are separated into a gas and a liquid by a cooler. Are known.

  Further, Non-Patent Document 1 discloses a relationship between catalyst body micropore diameter and catalyst activity by performing combustion treatment of volatile organic exhaust gas (VOC) using an alumite catalyst body. The method for producing an alumite catalyst body is a method in which the fine pores are controlled by controlling the thickness of the catalyst layer by an anodic oxidation method and hydrating and firing the sample after the anodic oxidation. Using a serrated alumite catalyst that takes advantage of the complex structure of an aluminum structure and controlling the pore diameter, a combustion rate of 90% or more can be obtained even at a high space velocity (SV) of 90,000 h-1. It has been reported.

JP 7-192746 A JP 2002-274801 A JP 2002-184436 A JP 2005-126315 A "Surface technology", 48, 994-997 (1997)

  However, when hydrogen is supplied using a dehydrogenation reaction typified by the reaction between benzene and cyclohexane, this reaction is an endothermic reaction, and thus there is a problem in the heat supply method. In the dehydrogenation reaction, the higher the temperature, the higher the activity of the catalyst, and the faster the reaction proceeds, the faster the reaction rate on the high temperature side and the slower the reaction rate on the low temperature side. However, since the dehydrogenation reaction has a large endothermic amount, as the reaction becomes faster on the high temperature side, the endothermic amount due to the reaction increases, the supply heat becomes insufficient, and the reaction rate decreases. As a phenomenon, the reaction rate decreases at a certain temperature (hereinafter referred to as the inflection point temperature) or higher. How to quickly supply heat to the catalyst and maintain the reaction temperature is important.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydrogen supply catalyst and a hydrogen supply device that improve thermal efficiency and are fast and highly efficient.

In order to solve the above-mentioned problems, the present invention designs the structure of the porous oxide film, the particle size of the catalyst, and the heat conduction of the catalyst, and is small and efficient with a dehydrogenation / hydrogenation catalyst having a high reaction conversion rate. Provide a good hydrogen supply device.

Specifically, in the dehydrogenation / hydrogenation catalyst comprising a metal catalyst supported on a catalyst carrier made of a porous oxide film and taking out hydrogen using a medium that repeatedly stores and supplies hydrogen chemically, Provided is a dehydrogenation catalyst characterized in that the water absorption / film thickness of an oxide film is 0.030 to 0.065 (mg / (cm ² · μm)).

Further, the present invention provides a dehydrogenation / hydrogen addition catalyst, wherein the porous oxide film has a water absorption rate / film thickness of 0.030 to 0.065 (mg / (cm ² · μm)).

The present invention also provides a dehydrogenation / hydrogenation catalyst, wherein the metal catalyst is Pt, and the Pt catalyst particle size is 1 to 4 nm.

The present invention also provides a dehydrogenation / hydrogenation catalyst, wherein the porous oxide film has pores of 45 to 100 nm.

A dehydrogenation / hydrogen addition catalyst characterized in that the porous oxide film has a thermal diffusivity / film thickness of 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ (m ² / (s · μm)). provide.

Further, the water absorption / film thickness of the porous oxide film is 0.030 to 0.065 (mg / (cm ² · μm)), the Pt catalyst particle diameter is 1 to 4 nm, and the pore diameter of the porous oxide film is 45 to 45 nm. Hydrogen supply using a dehydrogenation / hydrogenation catalyst having a structure of 100 nm, porous oxide film having thermal diffusivity / film thickness of 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ (m ² / (s · μm)) Providing equipment.

Also provided is a hydrogen supply apparatus in which an aluminum substrate is laminated using the dehydrogenation / hydrogen addition catalyst of the present invention, a hydrogen separation membrane is provided in a hydrogen flow path, and a number of hydrogen diffusion through holes are provided between the laminations.

  By optimizing the structure of the porous oxide film and the catalyst particle size, the thermal efficiency was improved, and a high-speed and high-efficiency hydrogen supply catalyst and hydrogen supply device could be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail by way of specific examples, but the present invention is not limited to the following examples.

A schematic diagram of the dehydrogenation / hydrogenation catalyst of the present invention is shown in FIG. The dehydrogenation / hydrogen addition catalyst has a configuration in which catalyst particles 5 are supported on a porous oxide catalyst carrier 2 formed on a high thermal conductive substrate made of an Al substrate 1. A catalyst layer 20 is constituted by the catalyst carrier 2 and the catalyst particles 5. As shown in FIG. 1, the porous oxide catalyst support 2 has macropores 4 and micropores existing in the walls constituting the macropores. The catalyst particles 5 are supported on the catalyst carrier 2 to construct a reaction site.

  This catalyst support can directly produce a porous oxide by anodic oxidation on the surface of aluminum having high thermal conductivity. The catalyst carrier formed by anodic oxidation has good adhesion to the high thermal conductive substrate and good thermal conductivity. The macropores produced by anodizing the aluminum surface and then anodizing the macropores are then expanded, followed by boehmite treatment and calcined porous oxide as the support. The number of micropores contained in the wall increases. This increases the surface area of the support and can increase the amount of catalyst supported, which is a more preferable form.

  In the anodic oxidation method, for example, phosphoric acid, chromic acid, oxalic acid, sulfuric acid aqueous solution or the like can be used as the electrolytic solution, but phosphoric acid, chromic acid, or oxalic acid aqueous solution is preferable in order to avoid catalyst poisoning. The pore diameter and film thickness of the porous layer formed by anodization can be appropriately set according to conditions such as applied voltage, processing temperature, and processing time. In general, the macropore diameter can be produced from 10 nm to 300 nm and the film thickness from 5 to 300 μm.

Further, the treatment time of this anodic oxidation varies depending on the treatment conditions and the film thickness to be formed. For example, when a 4 wt% oxalic acid aqueous solution is used as the electrolyte, the treatment bath temperature is 50 ° C., and the applied voltage is 40 V, By treating for 1 to 5 hours, an anodized layer having high thermal conductivity can be formed. If the catalyst has a pore diameter of 45 to 100 nm and a water absorption / film thickness of 0.030 to 0.065 (mg / (cm ² · μm)) and falls under these conditions, the reaction rate can be improved. .

  In order to increase the reaction efficiency, it is effective to increase the number of reaction sites, and it is important to increase the surface area of Pt serving as a catalyst. In order to increase the Pt surface area, it is necessary to decrease the Pt diameter. As a result of intensive experiments, it was found that 4 nm or less is preferable. However, since it is difficult to actually make Pt of 1 nm or less, the range is set to 1 nm to 4 nm.

  In order to hold 1 nm to 4 nm of Pt in the form of fine particles, a carrier capable of suppressing aggregation of Pt particles is desirable. In order to suppress the aggregation of Pt, the pore structure of the porous oxide support is important. In general, when a carrier having a large pore volume and a high surface area is used, Pt particles can be dispersed, and thus aggregation of Pt particles can be suppressed.

  The pore structure of the porous oxide can be evaluated by measuring the water absorption / film thickness of the porous oxide film. The water absorption rate can be evaluated by the amount of water absorption per unit area. The amount of water absorption can be related to the pore volume per unit volume by normalizing per film thickness. That is, knowledge about the pore volume can be obtained from the value of the water absorption rate / film thickness of the porous oxide. The smaller the water absorption rate / film thickness, the denser the film, and the larger the water absorption rate / film thickness, the more porous It can be said that the film has a large surface area.

  Furthermore, since the present method utilizes the capillary force of the membrane, it evaluates the structure of the micropores in the membrane, and can also be related to the pore diameter. Since the capillary force increases as the pore diameter decreases, the pore diameter of the membrane having a very large water absorption rate decreases.

On the other hand, the Pt particles supported on the porous film have different dispersibility depending on the surface area of the porous film. Pt on a porous film having a large surface area has good dispersibility and can maintain the initial particle diameter. However, Pt on a low surface area has poor dispersibility, tends to aggregate and grow particles, resulting in a large particle size. Therefore, when the water absorption rate / film thickness is small, the surface area of the porous film is small, so that the Pt particles are aggregated into large particles. When the surface area is large, the Pt particles are difficult to aggregate, the Pt particles become fine particles, and there are many reaction sites and a catalyst having a high reaction rate can be obtained. However, if the water absorption rate / film thickness is too large, the pore diameter becomes small and the Pt particles hardly enter the micropores, and as a result, Pt aggregates on the surface. Therefore, in the present invention, the conditions for optimizing the water absorption / film thickness of the porous oxide of the catalyst support have been found. As a result of intensive experiments, the value of water absorption / film thickness was 0.030 to 0.065 (mg / (cm ² · μm)). By using a carrier that satisfies this condition, the Pt catalyst particle size can be reduced to 1 to 4 nm.

  In the dehydrogenation reaction, the higher the temperature, the higher the reaction rate and the faster hydrogen supply becomes possible. However, since the dehydrogenation reaction involves a large endotherm, heat supply must also be performed at a high speed. As the reaction becomes faster on the high temperature side, if the supply heat becomes insufficient because of the endothermic reaction, the temperature decreases and the reaction rate decreases. Therefore, in order to efficiently supply heat to the catalyst layer, a hydrogen supply device having a high thermal conductivity is required. The hydrogen supply device is composed of a catalyst plate, a catalyst carrier, and the like. By increasing the heat conduction of these, heat can be supplied to the catalyst faster, and the reaction rate can be improved.

  Fabrication of a catalyst carrier by aluminum anodization can produce a structure in which alumina serving as a catalyst carrier is directly bonded on a high thermal conductivity aluminum substrate. Therefore, it is possible to efficiently supply heat directly from aluminum to the catalyst. However, alumina serving as a carrier has a lower thermal conductivity than aluminum and is rate-limiting when supplying heat. For this reason, it is desirable that the alumina carrier also has high thermal conductivity. As a result of intensive experiments, it was found that the thermal diffusivity of alumina changes depending on the anodizing conditions.

In the production of the porous oxide by anodic oxidation, the influence of the processing temperature is large. When the treatment temperature is increased, the dissolution rate of the oxide film is increased, and a dense film having a large macropore diameter can be formed. Since the density of the dense oxide is increased, heat conduction is increased. Enlarging the pores of the porous oxide of the catalyst support at a higher anodizing temperature is an effective means. In the present invention, the pores of the porous oxide of the catalyst support are set to 45 to 100 nm, and the thermal diffusivity / film thickness of the porous oxide is set to 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ (m ² / ( s · μm)) makes it possible to produce a catalyst that can suppress a decrease in reaction rate even at high temperatures.

Next, FIG. 2 shows a hydrogen supply system configuration using the dehydrogenation / hydrogenation catalyst of the present invention as a catalyst layer. FIG. 2 includes a fuel tank unit 6, a fuel supply unit 7, a hydrogen supply device (reactor) 8, a heat exchanger 9, a cooler 12, a hydrogen discharge port 13, and a waste liquid tank unit 14. Hereinafter, the components will be described. The fuel tank unit 6 is a component that stores fuel. The fuel supply unit 7 is a component that supplies fuel from the tank to the hydrogen supply device 8. The hydrogen supply device 8 is a device that generates hydrogen by dehydrogenating the fuel. The heat exchanger 9 is a component that uses heat discharged from the engine or fuel cell through the hot gas inlet 10 and the hot gas outlet 11. The cooler 12 is a component that cools the mixed gas exiting from the hydrogen supply device 8 and performs gas-liquid separation. The waste liquid tank unit 14 is a component that stores the organic solvent after gas-liquid separation by the cooler 12.

  Next, the hydrogen supply apparatus shown in FIG. 3 will be described. 3A shows a cross-sectional view of a hydrogen supply device without a hydrogen separation membrane, and FIG. 3B shows a cross-sectional view of the hydrogen supply device with a hydrogen separation membrane. In the hydrogen supply device of FIG. 3A, various patterns were formed as fuel flow paths on the Al substrate 1 having high thermal conductivity. The highly active catalyst layer 20 excellent in heat conduction of the present invention, the gas flow path 3 and the upper lid 15 are integrated on the upper part. The catalyst is directly joined on a highly heat-conductive aluminum substrate, has high heat supply efficiency to the catalyst, and is a reactor capable of high-speed hydrogen supply by using a highly active catalyst. The hydrogen supply device of FIG. 3B has a configuration in which the hydrogen separation membrane 16, the spacer 17, and the hydrogen flow path 18 are integrated on the structure of FIG. Hydrogen separation using a hydrogen separation membrane separates gaseous hydrogen and medium inside the hydrogen supply device, moves the equilibrium state in the dehydrogenation direction, and enables hydrogen generation at a low temperature. If the pressure on the hydrogen permeation side is set to a lower pressure than the pressure on the reaction side, the hydrogen permeation rate can be increased.

  Hydrogen separation membranes include heat-resistant polymers such as porous polyimide, alumina silicates such as zeolite, oxides such as silica, zirconia, and alumina, and Pd, Pd-Ag, V-based, Nb-based, Zr-based, Ta-based, A film of a hydrogen storage metal such as a Ni—Zr system can be used. Further, the above materials can be used in combination, such as forming a Pd—Ag film on the surface of the porous polyimide piece. A V-based metal film is preferably used as the metal film. A film obtained by alloying Mo, Co, Ni or the like with V metal is excellent in hydrogen permeation performance even at a low temperature of 250 ° C. or lower.

The spacer is mounted on the upper part of the hydrogen separation membrane and serves as a flow path for product hydrogen. The spacer has a structure in which a groove is cut in a plane or a through-hole is formed in a direction perpendicular to the substrate, and a hydrogen separation membrane is provided on one side of the spacer.
[Reference Example 1]

In order to investigate the relationship between the structure of the porous oxide and the catalyst performance, a test was conducted by the following operation. The catalyst preparation process is described below.
(Patterning formation)
Patterning formation on the aluminum surface was performed by the following procedure. The aluminum substrate was immersed in a 4 wt% NaOH aqueous solution to remove the natural oxide layer, and then a resist was applied. Next, it developed after exposing using the photomask which has a pattern. Subsequently, etching was performed with an FeCl ₃ / HCl aqueous solution, and finally, post-treatment was performed using an aqueous NaOH solution and 10 wt% HNO ₃ .
(anodization)
Using 0.3 mol / L oxalic acid (C ₂ O ₄ H ₂ ) as the anodic oxidation electrolyte, using an Al plate with a cleaned surface as the anode, and a platinum-titanium (Pt—Ti) plate as the cathode, A porous oxide film (alumina) was formed by performing 40 V direct current constant voltage electrolysis at a bath temperature of 30 ° C.
(Pore wide)
In order to enlarge the micropores of the porous oxide film, the porous oxide film is treated with H ₃ PO ₄ at a bath temperature of 30 ° C. and 5% for 30 minutes.
(Boehmite)
The alumina porous oxide film produced by anodic oxidation is treated with pure water at 90 ° C. to 100 ° C. for 120 minutes to hydrate the film.
(Baking)
Firing is for forming γ-alumina and is performed at 550 ° C. for 90 minutes.
(Pt catalyst support)
A porous oxide film was impregnated with a Pt colloid solution and baked at 450 ° C. for 20 minutes to prepare a catalyst.

The prepared catalyst was measured for water absorption, fine pore diameter, and Pt particle diameter, and investigated the relationship with the dehydrogenation reaction test. Various measurement methods are shown below.
(Water absorption rate / film thickness)
The water absorption measurement is a method of measuring the water absorption per unit area by immersing a sample in water in order to evaluate the porous structure of the porous oxide film. The sample is dried at 160 ° C. for 15 minutes, weighed the sample after cooling for 5 minutes, soaked the sample in water for 5 minutes, wiped around for 1 minute, weighed the sample (on a scale) Record the value after 1 minute) and measure the difference in weight before and after water absorption. Film thickness measurement is a method of measuring the thickness of a porous oxide film from a cross-sectional photograph of a sample. The water absorption / film thickness was calculated from the water absorption and the film thickness. This water absorption / film thickness is related to the pore structure, and in particular, knowledge about micropores can be obtained. That is, it can be said that there are many micropores if the water absorption / film thickness is large, and there are few micropores if the water absorption / film thickness is small.
(Micropore diameter)
An SEM photograph of the cross section of the porous oxide film was taken, and the diameter of the macropores was measured by image processing.
(Pt particle size)
The diameter of the Pt particles supported on the porous oxide film catalyst support was measured by X-ray analysis.
(Dehydrogenation reaction)
While the catalyst was filled in the reaction tube and heated, methylocyclohexane (C ₇ H ₁₄ ) as a fuel was allowed to flow through the fuel pump and reacted, and the produced hydrogen was measured to calculate the conversion rate of the reaction. Furthermore, the conversion ratio of the reaction was calculated based on the reaction conversion ratio of Reference Example 1.
(Bending point)
The reaction rate constant k can be obtained from the relationship between the reaction conversion rate and 1 / space velocity. Furthermore, from the result of plotting the logarithm of the reaction rate constant k and 1 / reaction temperature T, the temperature point at the intersection of the two straight lines is called the inflection point temperature. This point is an inflection point.
(Thermal diffusivity)
For the thermal diffusivity, the temperature of the sample is kept constant, the frequency of the AC temperature wave applied to the sample surface is changed, the phase difference at the back of the sample is measured for each frequency, and this phase difference is plotted against the square root of the frequency. Then, it can be obtained from the slope of the obtained straight line. The thermal diffusivity of the catalyst layer of unit thickness was evaluated by the thermal diffusivity / the thickness of the catalyst layer.

In this example, 0.3 mol / L oxalic acid (C ₂ O ₄ H ₂ ) was used as the anodic oxidation electrolyte, the surface was washed with an Al plate, and the cathode was platinum-titanium (Pt—Ti). ) Using a plate, 40 V direct current constant voltage electrolysis was performed for 1 hour at a bath temperature of 30 ° C. to form a porous oxide film. Further, a catalyst was prepared by the above process.

In Example 1 , as described in Reference Example 1 , a porous oxide film was formed at a bath temperature of 30 ° C. for 5 hours to prepare a catalyst.

In Example 2 , as described in Reference Example 1, a porous oxide film was formed at a bath temperature of 50 ° C. for 1 hour to prepare a catalyst.

In Example 3 , as described in Reference Example 1, a porous oxide film was formed at a bath temperature of 50 ° C. for 5 hours to prepare a catalyst.

In Example 4 , as described in Reference Example 1, a porous oxide film was formed at a bath temperature of 40 ° C. for 5 hours to prepare a catalyst.
[Reference Example 2]

In Reference Example 2 , as described in Reference Example 1, a porous oxide film was formed at a bath temperature of 30 ° C. for 10 hours to prepare a catalyst.

The evaluation results of the catalysts prepared in Reference Examples 1 and 2 and Examples 1 to 4 are shown in Table 1.

The evaluation results of the catalysts prepared in Reference Examples 1 and 2 and Examples 1 to 4 are shown in FIGS.

FIG. 6 shows the water absorption / film thickness dependence of the dehydrogenation conversion ratio, and FIG. 7 shows the water absorption / film thickness dependence of the inflection point temperature. If the water absorption ratio / film thickness is in the range of 0.030 to 0.065 (mg / (cm ² · μm)), as in the results of Examples 2 and 3 , the reaction conversion ratio ratio of the catalyst is large, The inflection point of the reaction rate was found to be on the high temperature side.

As described above, in order to increase the reaction efficiency, it is effective to increase the number of reaction sites, and it is important to increase the surface area of Pt serving as a catalyst. The smaller the particle size of the supported Pt catalyst, the higher the reaction efficiency because the surface area of the chemical reaction increases. In order to hold Pt in the form of fine particles, a carrier that suppresses aggregation of Pt particles is desirable. For the carrier that suppresses the aggregation of Pt, the pore structure of the porous oxide becomes important. The pore structure of the porous oxide can be evaluated by measuring the water absorption / film thickness of the porous oxide film. The smaller the water absorption / film thickness, the denser the film, and the larger the water absorption / film thickness, the more porous the film. When the water absorption / film thickness is small, the surface area of the porous film is small, so that the Pt particles are aggregated into large particles. On the other hand, if the water absorption / film thickness is too large, the Pt particles hardly enter the micropores, and as a result, Pt aggregates on the surface. Accordingly, the conditions for optimizing the water absorption / film thickness of the porous oxide of the catalyst carrier were found from FIGS. The value of the water absorption rate / film thickness is 0.030 to 0.065 (mg / (cm ² · μm)). By using a carrier that satisfies this condition, the Pt catalyst particle size can be reduced to 1 to 4 nm.

FIG. 8 shows the micropore diameter dependence of the dehydrogenation conversion ratio, and FIG. 9 shows the micropore diameter dependence of the inflection point temperature. If the pore size of the porous oxide of the catalyst carrier is 45 to 100 nm, as shown in Examples 2 and 3 , the reaction conversion ratio of the catalyst is large, and the deflection point of the reaction rate is on the high temperature side. I understood. In order to efficiently supply heat to the catalyst layer, a hydrogen supply device having a high thermal conductivity is required. It has been found that the thermal diffusivity of alumina varies depending on the anodizing conditions. In the production of the porous oxide by anodic oxidation, the influence of the processing temperature is large. When the treatment temperature is increased, the dissolution rate of the oxide film is increased, and a dense film having a large macropore diameter can be formed. Since the density of the dense oxide is increased, heat conduction is increased. Enlarging the pores of the porous oxide of the catalyst carrier at a higher anodizing temperature is an effective means. From FIGS. 8 and 9, the pores of the porous oxide of the catalyst carrier are 45 to 100 nm. To do.

FIG. 10 shows the thermal diffusivity / film thickness dependence of the dehydrogenation conversion ratio, and FIG. 11 shows the thermal diffusivity / film thickness dependence of the inflection point temperature. 10 and 11, when the thermal diffusivity / film thickness of the catalyst is larger than 1 × 10 ⁻⁶ (m ² / (s · μm)) (thermal diffusivity / film thickness of dense alumina: 1 × 10 ⁻⁵ ( m ² / (s · μm))), the inflection point moved to the high temperature side, and the dehydrogenation conversion rate also increased. The higher the temperature, the higher the reaction rate of the dehydrogenation reaction and the high-speed hydrogen supply becomes possible. However, since the dehydrogenation reaction involves a large endotherm, the heat supply must be performed at a high speed for the generation of high-speed hydrogen. In order to efficiently supply heat to the catalyst layer, a hydrogen supply device having a high thermal conductivity is required. The hydrogen supply device is composed of a catalyst plate, a catalyst carrier, and the like. By increasing the heat conduction of these, heat can be supplied to the catalyst faster, and the reaction rate can be improved. However, alumina serving as a carrier has a lower thermal conductivity than aluminum and is rate-limiting when supplying heat. For this reason, it is desirable that the alumina carrier also has high thermal conductivity. 10 and 11, the thermal diffusivity / film thickness of the porous oxide is set to 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ (m ² / (s · μm)).

Therefore, the catalyst is composed of a water absorption / film thickness of 0.030 to 0.065 (mg / (cm ² · μm)), a Pt catalyst particle diameter of 1 to 4 nm, and a fine pore diameter of the porous oxide of 45. It was found that if the thermal diffusivity / film thickness of the porous oxide is 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ (m ² / (s · μm)), it becomes a high-performance catalyst. .

  In the above examples, the anodic oxidation voltage at the time of catalyst preparation was 40 V. However, even if the applied voltage was changed, the above water absorption / film thickness, Pt catalyst particle size, fine pores, heat of porous oxide It has been confirmed that if the value of diffusivity / film thickness falls within the set range, it becomes a high-performance catalyst.

In this example, as shown in FIG. 4, four aluminum substrates were laminated using the highly active catalyst produced in Example 2 , and a laminated hydrogen supply apparatus was produced. By laminating, it is possible to directly produce a porous oxide with excellent thermal conductivity by anodizing on the surface of aluminum with high thermal conductivity, and hydrogen supply with high adhesion and thermal conductivity between the high thermal conductivity substrate and the catalyst carrier It can be a device.

  The organic hydride as a medium passes through the fuel gas flow path in the concave portion, and a dehydrogenation reaction proceeds while contacting with the catalyst layer formed on the pattern surface to generate hydrogen. The produced hydrogen is separated from the fuel and the produced aromatic hydrocarbon by a cooler, passes through a hydrogen flow path, and is supplied to an external engine, a fuel cell, or the like.

The hydrogen supply device of this example is a hydrogen supply device manufactured according to Example 5 as shown in FIG. 5, and is provided with a hydrogen separation membrane in the hydrogen flow path and a large number of through-holes 19 between the layers. Is a feature. Gaseous hydrogen and medium are separated inside the hydrogen supply device, and the equilibrium state is moved in the dehydrogenation direction. These films are preferably as thin as possible with a thickness of 50 μm or less because the hydrogen permeation rate decreases as the film thickness increases. In the case of using a thicker membrane, the hydrogen permeation rate can be increased by setting the pressure on the hydrogen permeation side to be lower than the pressure on the reaction side. The hydrogen supply apparatus of this example is a reactor that can be further cooled by providing a hydrogen separation membrane in the configuration of Example 5 . Furthermore, by providing the through hole 19 in the aluminum laminate, the hydrogen separation membrane can be effectively used, and the hydrogen separation efficiency can be improved while maintaining the thermal efficiency.

It is a schematic diagram of a dehydrogenation and hydrogenation catalyst. It is an external view of a hydrogen supply system. (A) is a hydrogen separation membrane, (b) is sectional drawing of a hydrogen supply apparatus in case of a hydrogen separation membrane. It is sectional drawing of a laminated | stacked hydrogen supply apparatus (without a hydrogen separation membrane). It is sectional drawing of a laminated | stacked hydrogen supply apparatus (with a hydrogen separation membrane). It is a characteristic figure which shows the water absorption rate / film thickness dependence of dehydrogenation conversion ratio. It is a characteristic view which shows the water absorption rate / film thickness dependence of an inflection point temperature. It is a characteristic view which shows the micropore diameter dependence of dehydrogenation conversion ratio. It is a characteristic view which shows the micropore diameter dependence of an inflection point temperature. It is a characteristic view which shows the thermal diffusivity / film thickness dependence of dehydrogenation conversion ratio. It is a characteristic view which shows the thermal diffusivity / film thickness dependence of an inflection point temperature.

DESCRIPTION OF SYMBOLS 1 ... Al substrate, 2 ... Catalyst support, 3 ... Gas flow path, 4 ... Macro pore, 5 ... Catalyst particle, 6 ... Fuel tank part, 7 ... Fuel supply part, 8 ... Hydrogen supply apparatus (reactor), 9 ... Heat exchanger, 10 ... hot gas inlet, 11 ... hot gas outlet, 12 ... cooler, 13 ... hydrogen discharge port, 14 ... waste liquid tank, 15 ... upper lid, 16 ... hydrogen separation membrane, 17 ... spacer, 18 ... hydrogen A flow path, 19 ... through-hole, 20 ... catalyst layer.

Claims (6)

Made from those supported on the catalyst carrier made of a porous oxide film of the metal catalyst, in catalyze to eject the hydrogen using the medium to repeat the chemical hydrogen storage and supply, the catalyst support, the surface of the aluminum substrate It is a porous aluminum oxide film produced by anodizing and firing, and the water absorption / film thickness of the porous aluminum oxide film is 0.030 to 0.065 (mg / (cm ² · μm)). Dehydrogenation / hydrogenation catalyst characterized by The dehydrogenation / hydrogenation catalyst according to claim 1, wherein the metal catalyst is Pt, and the Pt catalyst particle size is 1 to 4 nm. The dehydrogenation / hydrogenation catalyst according to claim 1, wherein the porous oxide film has pores of 45 to 100 nm. ^2. The dehydrogenation / hydrogen of claim 1, wherein the porous oxide film has a thermal diffusivity / film thickness of 1 × 10 ⁻⁶ to 1 × 10 ⁻⁵ (m ² / (s · μm)). Addition catalyst. In the hydrogen supply apparatus having a dehydrogenation-hydrogenation catalyst, before Kisawa medium is from those carrying a catalyst carrier Pt catalyst particles consisting of a porous oxide layer, and the catalyst support, the surface of the aluminum substrate anodized A porous aluminum oxide film produced by firing, wherein the aluminum porous oxide film has a water absorption rate / film thickness of 0.030 to 0.065 (mg / (cm ² · μm) ). Hydrogen supply device. A catalyst carrier comprising a porous oxide film carries Pt catalyst particles, and the catalyst carrier is a porous aluminum oxide film produced by anodizing and firing the surface of an aluminum substrate, and the porous aluminum An aluminum substrate provided with a dehydrogenation / hydrogenation catalyst having a water absorption rate / film thickness of 0.030 to 0.065 (mg / (cm ² · μm)) of the oxide film is laminated, and a hydrogen separation membrane is formed in the hydrogen channel. A hydrogen supply apparatus comprising a plurality of hydrogen diffusion through holes between the stacked layers.

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