JP2005041728A - Hydrogen generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen production apparatus for efficiently producing a hydrogen enriched fuel gas from an oxygen-containing hydrocarbon such as methyl ether or the like. <P>SOLUTION: In the hydrogen producing apparatus for producing the hydrogen enriched fuel reformed gas by passing a gaseous dimethyl ether through a support on which a catalyst is supported and which is filled in a reforming tube of a reformer to carry out steam reforming, a three dimensional mesh like ceramic porous body 17 is used as the support 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen generator that uses oxygen-containing hydrocarbons such as dimethyl ether and methanol as raw fuel, steam is reformed by adding steam to the raw fuel, and hydrogen-rich fuel reformed gas is generated by steam reforming.
[0002]
[Prior art]
In the recent electric power industry and automobile industry, etc., fuel diversification has been promoted from the viewpoint of energy conservation in response to fossil fuel depletion and environmental conservation due to increased concentrations of CO ₂ and NOx. There is technology for using hydrogen gas.
[0003]
Examples of the hydrogen gas utilization technology include a fuel cell power plant and a hydrogen combustion power plant.
[0004]
The former is a method in which hydrogen-rich fuel reformed gas reformed from hydrocarbon or the like and oxygen are reacted electrochemically to directly generate electric energy. For example, Japanese Patent Application Laid-Open No. 2001-85040 (patent) Numerous inventions have been disclosed.
[0005]
In the latter, high-pressure hydrogen gas and pure oxygen gas are burned to generate high-temperature water vapor, and the generated high-temperature water vapor is expanded by a turbine, and the generator is driven by the power generated at that time to generate power. For example, Japanese Patent Laid-Open No. 11-36820 (see Patent Document 2) discloses many inventions.
[0006]
R & D results are expected as part of the new energy promotion policy of the 21st century in that both the former and the latter use extremely clean energy that does not generate environmental pollutants such as NOx, SOx, CO ₂ and greenhouse gases. ing.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-85040
[Patent Document 2]
Japanese Patent Laid-Open No. 11-36820
[Problems to be solved by the invention]
Incidentally, it has been proposed that hydrogen gas supplied as fuel to a fuel cell power plant or a hydrogen combustion power plant is produced by electrolysis of water.
[0010]
In this hydrogen production by electrolysis of water, as shown in FIG. 8, a container 22 is filled with an electrolyte solution 23 dissolved in water such as sodium hydroxide, and the electrolyte solution 23 to be filled is filled with an anode 24 and a cathode 25. And soaked. The oxygen gas generated at the anode 24 is collected in the oxygen collection unit 26 and taken out from the oxygen extraction port 27. Further, the hydrogen gas generated at the cathode 25 is collected in the hydrogen collecting unit 28 and taken out from the hydrogen outlet 29.
[0011]
In hydrogen production by electrolysis of water, most of the necessary cost is electric power.
[0012]
In current nuclear power plants and thermal power plants, only about 50% of fission energy exchanged for heat and fuel energy such as oil and natural gas are converted into electric power. In particular, in the case of a nuclear power plant, the heat utilization efficiency is about 30%.
[0013]
For this reason, hydrogen production by electrolysis of water involves problems such as extremely low energy utilization efficiency and high cost.
[0014]
On the other hand, when producing hydrogen gas from fuel, oxygen-containing hydrocarbons such as methyl ether and methanol are advantageous in terms of cost because they can be steam reformed at low temperature and low pressure.
[0015]
In addition, oxygen-containing hydrocarbons such as methyl ether and methanol are produced from methane in a small and medium gas group, a gas group having a high carbon dioxide content or CO ₂ content, and therefore the amount thereof is relatively large.
[0016]
The present invention has been made paying attention to such points, and an object thereof is to provide a hydrogen generator that efficiently generates a hydrogen-rich fuel reformed gas from oxygen-containing hydrocarbons such as methyl ether. .
[0017]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the hydrogen generator according to the present invention is filled with a carrier carrying a catalyst in a reforming tube of a reformer as described in claim 1, and the carrier is loaded into the carrier. In a hydrogen generator that passes gaseous dimethyl ether and generates hydrogen-rich fuel reformed gas by steam reforming, the carrier is a three-dimensional network ceramic porous body.
[0018]
Further, in order to achieve the above-described object, the hydrogen generator according to the present invention has a three-dimensional network ceramic porous body formed of a shaped column, a hollow column, a honeycomb, One of the shapes of the pellets is selected.
[0019]
In order to achieve the above object, the hydrogen generator according to the present invention sets the open pores to 0.5 mm to 10 mm in the ceramic porous body of the three-dimensional network as described in claim 3. The porosity is set to 70% or more.
[0020]
In order to achieve the above object, the hydrogen generator according to the present invention is characterized in that, as described in claim 4, the ceramic porous body of the three-dimensional network is alumina, magnesia, titania, silica, zirconia, At least one or more are selected.
[0021]
In the hydrogen generator according to the present invention, in order to achieve the above-mentioned object, as described in claim 5, the catalyst supported on the support includes γ-alumina.
[0022]
In order to achieve the above object, the hydrogen generator according to the present invention is characterized in that the catalyst supported on the support is at least one of Pd, Ni, Pt, and Ru. The above is selected.
[0023]
In order to achieve the above object, the hydrogen generator according to the present invention is characterized in that, as described in claim 7, the catalyst supported on the support is at least one of Pd, Ni, Pt, and Ru. While selecting the above, the particle diameter of the selected metal is set to 10 to 500 mm.
[0024]
Moreover, in order to achieve the above-mentioned object, the hydrogen generator according to the present invention is filled with a carrier carrying a catalyst in a reforming tube of a reformer, as described in claim 8, and this carrying In a hydrogen generator that passes a raw fuel through a body and generates a hydrogen-rich fuel reformed gas by steam reforming, the carrier carrying the catalyst filled in the reforming tube follows the flow of the raw fuel. The reformer tube is filled with a catalyst density increased on the inlet side and a catalyst density relatively lowered on the outlet side.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the hydrogen generator according to the present invention will be described with reference to the drawings and the reference numerals attached to the drawings.
[0026]
Prior to the description of the hydrogen generator according to the present invention, first, an exemplary fuel cell power generator incorporating the hydrogen generator according to the present invention will be described.
[0027]
FIG. 6 is a schematic system diagram showing the fuel cell power generator according to this embodiment.
[0028]
The fuel cell power generator according to the present embodiment uses oxygen-containing hydrocarbons such as dimethyl ether and methanol as a raw fuel, adds water vapor from the heat exchanger 1 to this raw fuel, and adds the water vapor (hereinafter referred to as mixed fuel and Is supplied to the reforming unit 3 incorporated in the reformer 2, where steam reforming is performed under heating of the combustion gas from the burner 4 to generate a hydrogen-rich fuel reformed gas. Yes.
[0029]
In addition, the fuel cell power generation apparatus treats carbon monoxide contained in the hydrogen-rich fuel reformed gas from the reforming unit 3 with the carbon monoxide converter 5 and the carbon monoxide remover 6, and then the fuel cell. The main body 7 is configured to chemically react with an oxidant, such as air, to collect the generated electrons and generate electric power.
[0030]
On the other hand, a reformer 2 which uses oxygen-containing hydrocarbons such as dimethyl ether as a raw fuel and steam-reforms the mixed fuel obtained by adding and mixing water vapor to the raw fuel has a cylindrical body 8 as shown in FIG. Is provided with a burner 4 for generating combustion gas with fuel and air on the head side, and an inlet manifold 9 for steam reforming the mixed fuel to which water vapor has been added and steam reformed fuel reformed gas outside the system. An outlet manifold 10 for supplying gas to the heat exchanger and a combustion gas outlet 11 for supplying combustion gas to a heat source of a heat exchanger (not shown), while an outer tube 12 and an inner tube 13 are formed in the middle portion of the body 8. The reforming section 14 is provided with the reforming unit 3 filled with a carrier 15 carrying a catalyst on the outer pipe 12 side of the reforming pipe 14, and when the mixed fuel supplied from the inlet manifold 9 passes through the carrier 15, a combustion gas temperature 250. Under heating at ℃ to 350 ℃ The reformed hydrogen-rich fuel reformed gas is supplied to a carbon monoxide converter (not shown) through the inner pipe 13 and the outlet manifold 10. ing.
[0031]
A carrier 15 configured as a hydrogen generator used in the reforming unit 3 of the exemplary fuel cell power generation apparatus having such a configuration is formed into a three-dimensional mesh column 16 as shown in FIG. The processed ceramic porous body 17 is used.
[0032]
The ceramic porous body 17 is formed by forming an open pore 19 having a diameter of 0.5 mm to 10 mm in a base 18 formed of a fibrous skeleton, and having a porosity of 70% or more.
[0033]
The reason why the diameter of the open air holes 19 is 0.5 mm to 10 mm is that clogging may occur if the diameter is 0.5 mm or less, and if the diameter is 10 mm or more, the mechanical strength decreases and breaks. Based on the fear of. These numerical values are a preferable application range confirmed by experiments.
[0034]
Further, the ceramic porous body 17 molded into the columnar body 16 of the three-dimensional network is composed of at least one metal selected from alumina, magnesia, titania, silica, silicon carbide, and zirconia.
[0035]
This is because these metals have sufficient corrosion resistance when steam reforming the mixed fuel shown in FIG. 7 under heating at a combustion gas temperature of 250 ° C. to 300 ° C.
[0036]
On the other hand, a catalyst is supported (coated) when the mixed fuel shown in FIG. 7 is steam-reformed on the support 15 used as the ceramic porous body 17 formed into the columnar body 16 of the three-dimensional network.
[0037]
This catalyst is made of γ-alumina, and the catalyst layer supported (coated) with γ-alumina contains a noble metal, specifically, at least one metal of Pd, Ni, Pt, and Ru. It is. These metals have a particle size of 10 to 500 mm.
[0038]
Γ-Alumina was selected as the catalyst because the chemical formula, CH ₃ OCH ₃ + H ₂ O → 2CH ₃ OH, was used when steam reforming the mixed fuel under heating at a combustion gas temperature of 250 ° C. to 300 ° C. This is to facilitate the quality reaction.
[0039]
Moreover, the reason why at least one metal of Pd, Ni, Pt, and Ru is mixed in the catalyst layer formed of γ-alumina is that when the mixed fuel is steam reformed, for example, when methanol is used, This is to make the reaction of CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ even better.
[0040]
The reason why the particle size of at least one metal among Pd, Ni, Pt, and Ru mixed in the catalyst is set to 10 to 500 is based on promoting the activation of the catalyst.
[0041]
When the carrier 15 carrying the catalyst made of γ-alumina or the like is filled in the reforming tube 14 shown in FIG. 7, the density (layer thickness) of the catalyst is set on the inlet side along the flow of the mixed fuel. It is high and its exit side is relatively low. This is to make the steam reforming react more effectively without waste.
[0042]
As described above, in the present embodiment, the ceramic porous body 17 formed into the three-dimensional mesh column 16 is used as the carrier 15 and the open pores 19 of the ceramic porous body 17 have a diameter of 0.5 mm to 10 mm. While the porosity is set to 70% or more, the ceramic porous body 17 is loaded with a catalyst in which a noble metal is mixed with γ-alumina, and the surface area of the catalyst is further increased. The pressure loss of the passing mixed fuel can be further reduced, and the reforming of the mixed fuel can be further promoted under the larger surface area of the catalyst.
[0043]
In the present embodiment, the ceramic porous body 17 molded into the columnar body 16 of the three-dimensional mesh is used as the carrier 15. However, the present invention is not limited to this example. For example, as shown in FIG. 15 may be a ceramic porous body 17 formed into a hollow column 20 having a hollow 21 at the center of the three-dimensional network, and may be a ceramic porous body 17 formed into a honeycomb.
[0044]
Further, in the present embodiment, when the carrier 15 shown in FIGS. 1 and 2 is filled in the reforming tube, it may be a long product. Further, as shown in FIG. A plurality of 15 may be assembled, or a spherical carrier 15 may be formed as shown in FIG. The carrier 15 shown in FIGS. 3 and 4 is both the three-dimensional mesh ceramic porous body 17 shown in FIG.
[0045]
Next, a manufacturing method for supporting a catalyst made of γ-alumina on the support 15 will be described.
[0046]
When the catalyst is supported on the support 15, any one of a gas phase method, a coprecipitation method, a hot water method, a freeze drying method, a spray pyrolysis method, and an emulsion method is used.
[0047]
For example, when the sol method is used, a metal aqueous solution of at least one of Pd, Ni, Pt, and Ru is added to γ-alumina and stirred to synthesize a sol, which is then formed into a three-dimensional mesh column 16. The carrier 15 using the processed ceramic porous body 17 is coated, evaporated and dried as necessary, and subjected to a reduction treatment.
[0048]
By adopting such a technique, γ-alumina can effectively reform dimethyl ether (DME) into methanol by a reaction of CH ₃ OCH ₃ + H ₂ O → 2CH ₃ OH.
[0049]
In addition, when at least one kind of Pd, Ni, Pt, and Ru is mixed in γ-alumina, methanol is hydrogen-rich fuel reforming by the reaction of CH ₃ OH + H ₂ O → CO ₂ + 3H _2. Gas can be generated. In addition, when Cu is mixed in γ-alumina, the production of hydrogen is improved. In particular, the production rate of hydrogen is very high at a combustion gas of 300 ° C. or less.
[0050]
FIG. 5 is a reforming rate diagram showing the reforming rate of hydrogen (hydrogen generation rate) when dimethyl ether (DME) is steam reformed.
[0051]
From this reforming rate diagram, it is understood that when dimethyl ether (DME) is heated under heating at a combustion gas temperature of 250 ° C. to 300 ° C., dimethyl ether (DME) has a higher hydrogen reforming rate as the pressure decreases. It was.
[0052]
【The invention's effect】
As described above, the hydrogen generator according to the present invention is a carrier that fills the reformer tube of the reformer and uses oxygen-containing hydrocarbons such as dimethyl ether and methanol as raw fuel, and steam reforming from this raw fuel. When generating hydrogen-rich fuel reformed gas, a ceramic porous body with a three-dimensional mesh is used as the support, and the pressure loss of the raw fuel passing through the ceramic porous body is reduced, and under a wider catalyst surface area, The catalyst can be activated to produce a more efficient hydrogen-rich fuel reformed gas.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a first embodiment of a carrier used as a hydrogen generator according to the present invention.
FIG. 2 is a conceptual diagram showing a second embodiment of a carrier used as a hydrogen generator according to the present invention.
FIG. 3 is a conceptual diagram showing a third embodiment of a carrier used as a hydrogen generator according to the present invention.
FIG. 4 is a conceptual diagram showing a fourth embodiment of a carrier used as a hydrogen generator according to the present invention.
FIG. 5 is a reforming rate diagram showing the reforming rate of hydrogen when dimethyl tail is steam reformed.
FIG. 6 is a schematic system diagram showing an exemplary fuel cell power generator incorporating the hydrogen generator according to the present invention.
FIG. 7 is a longitudinal sectional view of a reformer containing a hydrogen generator according to the present invention.
FIG. 8 is a conceptual diagram for generating hydrogen by conventional water electrolysis.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Reformer 3 Reformer 4 Burner 5 Carbon monoxide transformer 6 Carbon monoxide remover 7 Fuel cell body 8 Body 9 Inlet manifold 10 Outlet manifold 11 Combustion gas outlet 12 Outer pipe 13 Inner pipe 14 Tube 15 Carrier 16 Column 17 Ceramic porous body 18 Base 19 Open pore 20 Hollow column 21 Hollow 22 Container 23 Electrolyte solution 24 Anode 25 Cathode 26 Oxygen collector 27 Oxygen outlet 28 Hydrogen collector 29 Hydrogen outlet

Claims (8)

In a hydrogen generator that fills a reformer tube of a reformer with a carrier carrying a catalyst, passes gaseous dimethyl ether through the carrier, and generates a hydrogen-rich fuel reformed gas by steam reforming. The hydrogen generating apparatus according to claim 1, wherein the carrier is a ceramic porous body having a three-dimensional network. 2. The hydrogen generating apparatus according to claim 1, wherein the ceramic porous body having a three-dimensional network is selected from the shape of a columnar body, a hollow columnar body, a honeycomb, and a pellet. 2. The hydrogen generating apparatus according to claim 1, wherein the three-dimensional mesh ceramic porous body has an open pore set to 0.5 mm to 10 mm and a porosity set to 70% or more. 2. The hydrogen generating apparatus according to claim 1, wherein the three-dimensional mesh ceramic porous body is selected from at least one of alumina, magnesia, titania, silica, and zirconia. 2. The hydrogen generator according to claim 1, wherein the catalyst supported on the support contains γ-alumina. 2. The hydrogen generator according to claim 1, wherein the catalyst carried on the carrier is selected from at least one of Pd, Ni, Pt and Ru. The catalyst supported on the carrier is selected from at least one of Pd, Ni, Pt, and Ru, and the particle size of the selected metal is set to 10 to 500%. Hydrogen generator. In the hydrogen generator in which the reformer tube of the reformer is filled with a carrier carrying a catalyst, the raw fuel is passed through the carrier, and a hydrogen-rich fuel reformed gas is generated by steam reforming. The carrier carrying the catalyst filled in the material pipe is filled in the reforming pipe with the catalyst density increased on the inlet side and the catalyst density relatively lowered on the outlet side along the flow of the raw fuel. A hydrogen generator characterized by this.

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