JP2005081303A - Cu/ZnO CATALYST, ITS PRODUCING METHOD, AND GENERATOR - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for preventing a catalytically active property from lowering in a low temperature environment of not more than 300°C . <P>SOLUTION: A generator 1 is provided with a modified reactor 42 producing hydrogen from a mixture of methanol and water, and a fuel cell 91 producing an electric energy from the hydrogen produced by the modified reactor 42. In the modified reactor 42, a passage making the mixture of methanol and water flow is formed, in which Cu/ZnO catalyst having a surface area of not less than 65 m<SP>2</SP>/g, and a ZnO crystallite diameter of not more than 121 Å is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a Cu / ZnO-based catalyst, a method for producing the same, and a power generation device, and more particularly to a Cu / ZnO-based catalyst capable of preventing a catalyst function from being lowered even at a low reaction temperature, a method for producing the same, and a power generation device.

In recent years, fuel cells using hydrogen as fuel as a clean power source with high energy conversion efficiency have begun to be applied to automobiles and portable devices. There are two types of fuel cells: a direct type in which a compound containing hydrogen as a fuel is directly introduced into the solid polymer membrane, and a modified type in which a compound containing hydrogen is reformed and introduced into the solid polymer membrane as hydrogen. The reforming reaction when methanol is applied as the compound is as follows.
CH ₃ OH + H ₂ O → 3H ₂ + CO ₂

By the way, as a catalyst for reforming methanol that promotes the above chemical reaction, there are many proposals such as a catalyst in which a platinum group metal such as platinum or palladium is supported on a carrier or a catalyst in which a base metal element such as copper, nickel, chromium, or zinc is supported on a carrier. Has been. Among them, the so-called “Cu / ZnO-based catalyst” in which copper and zinc are supported on a carrier has high catalytic activity particularly in a high temperature range of 300 ° C. or higher, and high-purity hydrogen can be produced quickly and efficiently. It is in the spotlight (see Patent Document 1).
JP 2001-300315 A

However, since the chemical reaction is an endothermic reaction, it is necessary to supply reaction heat to promote the chemical reaction. Therefore, in order to incorporate a Cu / ZnO-based catalyst into a small portable device as a part of a fuel cell type power generator, the power generator itself must provide energy for reaction heat. When brought about by the generated electric energy, it is not preferable to exert a catalytic function in a high temperature environment from the viewpoint of power generation efficiency and safety with respect to fuel consumption, and a high catalyst even in a low temperature environment of 300 ° C. or lower, preferably 280 ° C. or lower. It is practical to demonstrate the function.
An object of the present invention is to provide a Cu / ZnO-based catalyst that can suppress a decrease in catalytic activity even in a low-temperature environment of 300 ° C. or lower, a method for producing the same, and a power generator.

To solve the above problem,
The Cu / ZnO-based catalyst of the invention according to claim 1 is
The surface area is 65 m ² / g or more.

The invention described in claim 2
In the Cu / ZnO-based catalyst according to claim 1,
The ZnO crystallite diameter is 121 mm or less.

Invention of Claim 3 is a manufacturing method of a Cu / ZnO type catalyst,
A copper / zinc aqueous solution containing a copper / zinc metal salt in which the molar ratio of copper and zinc is copper: zinc = 1: 2 to 8: 1 and an alkaline solution are mixed at 50 to 70 ° C. to form a precipitate. A precipitation step to form,
A drying / firing step for drying / firing the precipitate;
It is characterized by having.

Invention of Claim 4 is a manufacturing method of a Cu / ZnO type catalyst, Comprising:
A precipitation step in which a copper / zinc aqueous solution containing a metal salt of copper / zinc and an alkaline solution are mixed while maintaining a pH of 8.0 to 9.4 to form a precipitate;
A drying / firing step for drying / firing the precipitate;
It is characterized by having.

The invention described in claim 5
In the manufacturing method of the Cu / ZnO-type catalyst of Claim 3 or 4,
After the precipitation step, it has a filtration / washing step of filtering the mixed solution and washing the precipitate remaining after the filtration,
In the filtration / washing step, the precipitate remaining after the filtration is washed at a temperature higher than the temperature of the mixed solution during the precipitation step.

The invention described in claim 6
In the manufacturing method of the Cu / ZnO-type catalyst as described in any one of Claims 3-5,
In the precipitation step, the copper / zinc aqueous solution and the alkaline solution are mixed in an aqueous solution containing aluminum oxide.

The invention described in claim 7
In the electric power generating apparatus using the Cu / ZnO-based catalyst according to claim 1,
A reforming reactor for producing hydrogen from a mixture of methanol and water;
A fuel cell that generates electrical energy from hydrogen generated in the reforming reactor;
With
The reforming reactor is formed with a flow path for allowing a mixture of methanol and water to flow, and the Cu / ZnO-based catalyst is arranged in the flow path.

The invention according to claim 8 provides:
The power generator according to claim 7,
A reactor for removing carbon monoxide produced in the reforming reactor is provided.

  According to the first aspect of the present invention, it is possible to prevent the catalytic activity from being lowered in a low temperature environment of 300 ° C. or lower.

  According to the invention described in claims 3 to 6, it is possible to produce a Cu / ZnO-based catalyst that is catalytically active even in a range exceeding 300 ° C. and that can suppress a decrease in catalytic activity even in a low temperature environment of 300 ° C. or lower. Can do.

  In the seventh aspect of the invention, since the Cu / ZnO-based catalyst is arranged in the flow path, when a mixture of methanol and water flows through the flow path, hydrogen can be generated from the mixture.

  In the invention described in claim 8, since the reactor for removing carbon monoxide is provided, the carbon monoxide generated in the reforming reactor can be removed.

The best mode for carrying out the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
First, the power generator according to the present invention will be described with reference to FIG. FIG. 1 is a perspective view of the power generator 1 with a part thereof broken away.

  A power generation device 1 shown in FIG. 1 is a fuel cell type power generation device that generates power using a fuel cell, and generates power using a fuel storage module 2 that stores fuel 99 and a fuel 99 stored in the fuel storage module 2. And a power generation module 3.

  The fuel storage module 2 has a substantially cylindrical casing 4, and the casing 4 is detachably attached to the power generation module 3. A circular through hole 5 is formed at the top of the casing 4, and a first drain pipe 6 for circulating the by-product water generated by the power generation module 3 is provided on the outer periphery of the casing 4. Is formed. A drainage container 7 (see FIG. 2) for storing drainage water is disposed at the bottom of the fuel storage module 2, and the first drainage pipe 6 is connected to the drainage container 7.

  A fuel tank 8 is housed inside the housing 4, and a part of the outer peripheral surface of the fuel tank 8 is exposed to the outside of the housing 4. Liquid fuel 99 is stored inside the fuel tank 8. The fuel tank 8 is a transparent or translucent substantially cylindrical container having an internal space, and is made of a material such as polyethylene, polypropylene, polycarbonate, or acrylic. In the fuel storage module 2, a part of the outer peripheral surface of the fuel tank 8 is exposed to the outside of the housing 4, and the fuel tank 8 is composed of a transparent or translucent container. You can easily check the remaining amount.

  The fuel 99 is a mixture of a liquid chemical fuel and water. As the chemical fuel, a mixture of alcohols such as methanol and ethanol and a hydrocarbon such as gasoline is applicable. In the power generation device 1, a mixed liquid (water / methanol = 2 (molar ratio)) in which methanol and water are uniformly mixed is used as the fuel 99.

  A supply port 10 for supplying the fuel 99 to the power generation module 3 is provided at the top of the fuel tank 8, and the supply port 10 is inserted into the through hole 5 of the housing 4. Inside the supply port 10, a blocking film 11 that closes the entire supply port 10 is disposed. A supply pipe 12 extending in the vertical direction in FIG. 1 is disposed inside the fuel tank 8, and the supply pipe 12 is inserted into the supply port 10. The supply pipe 12 extends from the bottom of the fuel tank 8 to just below the blocking film 11 in the supply port 10. In the fuel tank 8, the supply port 10 is closed by the closing film 11, and the fuel 99 can be prevented from leaking outside the fuel tank 8.

Next, the power generation module 3 will be described.
As shown in FIG. 1, the power generation module 3 has a substantially cylindrical housing 30. Inside the housing 30 is disposed a reformer 40 that reforms methanol in the fuel 99 stored in the fuel tank 8 to generate hydrogen. The reformer 40 has a structure in which a vaporizer 41, a reforming reactor 42, an aqueous shift reactor 43, and a selective oxidation reactor 44 are stacked in this order.

  In the power generation module 3, a fuel cell 91 is disposed so as to surround the vaporizer 41, the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44. The fuel cell 91 includes a fuel electrode (cathode) containing or adhering catalyst fine particles such as Pt / C and an air electrode (anode) containing or adhering catalyst fine particles such as Pt / Ru / C. In addition, a film-like ion conductive membrane is interposed between the fuel electrode and the air electrode.

  A plurality of slits 31, 31,... For inhaling oxygen in the outside air are formed in parallel with each other on the outer peripheral surface of the housing 30 outside the fuel cell 91. A terminal 32 for supplying electric energy to an external device is disposed on the top of the housing 30, and by-product dioxide dioxide is provided around the terminal 32 and on the top of the housing 30. A plurality of exhaust holes 33, 33,... For exhausting carbon, water vapor, and the like are formed.

  A second drain pipe 34 is disposed on the outer peripheral side of the housing 30. The second drain pipe 34 protrudes downward from the bottom of the housing 30 and is disposed at a position corresponding to the first drain pipe 6 of the fuel storage module 2. The second drain pipe 34 is for circulating the by-product water generated in the fuel cell 91, and the by-product water generated in the fuel cell 91 is the second drain pipe 34 and the first drain pipe. 6 is drained and stored in the drainage container 7.

  A suction nipple portion 37 is disposed at the center of the bottom of the housing 30 so as to protrude downward. The suction nipple portion 37 is formed with a flow path penetrating from the tip along the center line. The suction nipple portion 37 is disposed at a position corresponding to the through hole 5 of the fuel storage module 2 and is for sucking the fuel 99 from the fuel tank 8.

  In the power generation apparatus 1 having the above configuration, when the fuel storage module 2 containing the fuel tank 8 is attached (connected) to the power generation module 3, the fuel storage module 2 is connected to the outer peripheral side of the connection portion between the modules 2 and 3. One drain pipe 6 is connected to the second drain pipe 34 of the power generation module 3. Thereby, the first drain pipe 6 and the second drain pipe 34 communicate with each other, and the by-product water generated in the fuel cell 91 of the power generation module 3 is transferred from the second drain pipe 34 to the first drain pipe 6. It becomes a state which can be drained to the drainage container 7 by circulating.

  On the other hand, in the central portion of the connection location between the modules 2 and 3, the suction nipple portion 37 of the power generation module 3 is inserted into the through hole 5 of the fuel storage module 2 and the supply port 10 of the fuel tank 8. Break through 11. As a result, the suction nipple portion 37 communicates with the supply pipe 12 of the fuel tank 8, and the fuel 99 stored in the fuel tank 8 can be supplied from the supply pipe 12 to the suction nipple portion 37.

  Next, the power generation system in the power generation apparatus 1 will be described in detail with reference to FIG. FIG. 2 is a block diagram illustrating a basic configuration of the power generation system of the power generation apparatus 1.

  The fuel 99 stored in the fuel tank 8 is first supplied to the vaporizer 41. In the vaporizer 41, the supplied fuel 99 is heated and vaporized (evaporated) to become a mixed gas (mixed gas) of methanol and water (water vapor) and supplied to the reforming reactor 42.

In the reforming reactor 42, hydrogen and carbon dioxide are generated from the fuel 99 vaporized in the vaporizer 41. Specifically, as shown in the chemical reaction formula (1), methanol and water vapor mixed in the vaporizer 41 react to generate carbon dioxide and hydrogen.
CH ₃ OH + H ₂ O → 3H ₂ + CO ₂ (1)

In the reforming reactor 42, the methanol and water vapor mixed in the vaporizer 41 may not be completely reformed to carbon dioxide and hydrogen. In this case, as shown in the chemical reaction formula (2), The methanol and water vapor react to produce carbon dioxide, carbon monoxide and water vapor.
2CH ₃ OH + H ₂ O → 5H ₂ + CO + CO ₂ (2)
Steam, carbon monoxide, carbon dioxide and hydrogen generated in the reforming reactor 42 are supplied to the aqueous shift reactor 43.

In the aqueous shift reactor 43, carbon dioxide and hydrogen are generated from carbon monoxide and water vapor contained in the gas mixture supplied from the reforming reactor 42. Specifically, as shown in the chemical reaction formula (3), carbon monoxide and water react to generate carbon dioxide and hydrogen, and the generated carbon dioxide and hydrogen and the unreacted one in the aqueous shift reactor 43. Carbon oxide, carbon dioxide and hydrogen are supplied to the selective oxidation reactor 44.
CO + H ₂ O → CO ₂ + H ₂ (3)

In the selective oxidation reactor 44, carbon monoxide contained in the air-fuel mixture supplied from the aqueous shift reactor 43 is selectively oxidized to remove carbon monoxide from the air-fuel mixture. Specifically, carbon monoxide specifically selected from the air-fuel mixture supplied from the aqueous shift reactor 43 reacts with oxygen in the outside air taken in through the slits 31 to produce carbon dioxide. Carbon is produced.
2CO + O ₂ → 2CO ₂ (4)

  Thus, carbon dioxide and hydrogen are generated from the fuel 99 that has passed through the respective reactors of the vaporizer 41, the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44 of the reformer 40. The generated hydrogen is supplied to the fuel cell 91, and the generated carbon dioxide is exhausted into the outside air from each exhaust hole 33 as a by-product. Further, water vapor generated through each reactor of the reformer 40 is also exhausted from each exhaust hole 33 as a by-product.

In the fuel cell 91, as shown in the electrochemical reaction formula (5), the hydrogen supplied from the selective oxidation reactor 44 is separated into hydrogen ions and electrons under the action of the catalyst fine particles of the fuel electrode. Hydrogen ions are conducted to the air electrode through the ion conductive membrane, and electrons are taken out by the fuel electrode.
H ₂ → 2H ⁺ + 2e ⁻ (5)

In the fuel cell 91, oxygen in the outside air is taken in through each slit 31, and this oxygen is supplied to the air electrode. Then, as shown in the electrochemical reaction formula (6), oxygen taken in from the outside air, hydrogen ions that have passed through the ion conductive membrane, and electrons taken out by the fuel electrode react to form water as a byproduct. Is generated as The generated water as a by-product is drained and stored in the drainage container 7 through the second drain pipe 34 and the first drain pipe 6.
2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O (6)

  As described above, in the power generation device 1, electric energy is generated by the electrochemical reactions shown in the above (5) and (6) in the fuel cell 91.

  Next, the reformer 40 will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the reformer 40.

  As shown in FIG. 3, the reformer 40 has a structure in which a vaporizer 41, a reforming reactor 42, an aqueous shift reactor 43, and a selective oxidation reactor 44 are stacked in this order. Each of the vaporizer 41, the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44 has a heat insulating package 45 in which a space is formed. Each heat insulating package 45 is made of a heat insulating material such as glass having a relatively low thermal conductivity, and a radiation reflecting film (not shown) formed of Au, Ag, Al or the like on the inner wall of each heat insulating package 45. ) Is formed.

  The radiation reflection film has a high reflectance with respect to electromagnetic waves including infrared rays, and reflects the electromagnetic waves emitted inside each heat insulating package 45. Therefore, in each reactor of the vaporizer 41, the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44, almost no heat is transferred to the heat insulation package 45, and heat loss in the heat insulation package 45 is suppressed. Can be done.

  The interior of each heat insulation package 45 is a completely sealed space, and the space is evacuated. However, the inside of each heat insulation package 45 may be replaced with fluorine-containing methane or ethane polyhalogenated derivative gas (Freon (trade name) gas) or carbon dioxide gas. Examples of the methane or ethane polyhalogenated derivative gas containing fluorine include trichlorofluoromethane and dichlorodifluoromethane.

  Supports 46 are respectively disposed in the corners of the inner walls of the respective heat insulation packages 45, and the four small reactors 51 are supported by the respective supports 46, the vaporizer 41, the reforming reactor 42, and the like. One water shift reactor 43 is provided for each reactor.

  Each small reactor 51 has a structure in which a glass substrate 53 and a silicon substrate 54 are overlapped and joined to each other. The glass substrate 53 is an ion conductive glass substrate containing Na or the like, and the silicon substrate 54 is a semiconductive silicon substrate. The silicon substrate 54 may be a substrate made of amorphous silicon, or may be a substrate made of crystalline silicon such as single crystal silicon or polycrystalline silicon.

FIG. 4 shows a cross-sectional view (middle stage) of the silicon substrate 54 of each small reactor 51, a plan view (upper stage) of the silicon substrate 54, and a bottom view (lower stage) of the silicon substrate 54.
As shown in the upper part of FIG. 4, a twisted heater 55 is disposed on the upper surface of the silicon substrate 54 (the surface opposite to the bonding surface with the glass substrate 53). The heater 55 is a thin film formed of an electrical resistance heating element, a semiconductor heating element, and the like, and generates heat when a current flows or a voltage is applied thereto.

  Lead wires (not shown) that pass through the heat insulation package 45 and extend to the outside of the heat insulation package 45 are respectively connected to both ends of the heater 55, and electrical energy is supplied to the heater 55 through the lead wires. It comes to be supplied. A portion where each lead wire penetrates the heat insulation package 45 is completely sealed, and has a structure that blocks gas from entering and exiting between the inside and the outside of the heat insulation package 45.

  As shown in the lower part of FIG. 4, a twisted microchannel 56 is formed on the lower surface of the silicon substrate 54 (the bonding surface with the glass substrate 53). As shown in the middle of FIG. 4, the microchannel 56 is a groove having a bow shape when viewed in cross-section, and specifically, photolithography, etching, or the like is appropriately applied to the lower surface of the silicon substrate 54. It is formed by. The microchannel 56 extends from the one end portion 56a to the other end portion 56b while having the same width.

  As shown in FIG. 3, in each reactor of the vaporizer 41, the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44, the inflow pipe 61 and the outflow pipe 62 pass through the heat insulating package 45. One by one.

  The inflow pipe 61 of the carburetor 41 communicates with the suction nipple portion 37 and one end portion 56a of the micro flow channel 56 of the small reactor 51, and the fuel 99 stored in the fuel tank 8 flows into the suction nipple portion 37 and the inflow portion. The micro channel 56 is supplied through the tube 61. However, a micro pump (not shown) is disposed between the inflow pipe 61 of the carburetor 41 and the suction nipple portion 37, and the flow rate of the fuel 99 flowing into the inflow pipe 61 of the carburetor 41 by the micro pump is reduced. It can be adjusted. The outflow pipe 62 of the vaporizer 41 communicates with the other end 56 b of the microchannel 56 of the small reactor 51 and the inflow pipe 61 of the reforming reactor 42.

  The inflow pipe 61 of the reforming reactor 42 communicates with the outflow pipe 62 of the vaporizer 41 and the other end portion 56 b of the microchannel 56 of the small reactor 51. The outflow pipe 62 of the reforming reactor 42 communicates with one end portion 56 a of the micro flow path 56 of the small reactor 51 and the inflow pipe 61 of the aqueous shift reactor 43.

  The inflow pipe 61 of the aqueous shift reactor 43 communicates with the outflow pipe 62 of the reforming reactor 42 and one end portion 56 a of the microchannel 56 of the small reactor 51. The outflow pipe 62 of the aqueous shift reactor 43 communicates with the other end portion 56 b of the microchannel 56 of the small reactor 51 and the inflow pipe 61 of the selective oxidation reactor 44.

  The inflow pipe 61 of the selective oxidation reactor 44 communicates with the outflow pipe 62 of the aqueous shift reactor 43 and the other end portion 56 b of the microchannel 56 of the small reactor 51. The outflow pipe 62 of the selective oxidation reactor 44 communicates with one end portion 56a of the micro-channel 56 of the small reactor 51 inside the heat insulation package 45, and is branched into two branches outside the heat insulation package 45. One leads to the fuel electrode of the fuel cell 91, and the other branched leads to the exhaust holes 33, 33,... (See FIG. 1).

  As shown in FIG. 3, an air inflow pipe 63 communicates with the micro flow path 56 of the small reactor 51 of the selective oxidation reactor 44. The air inflow pipe 63 passes through the heat insulating package 45 and communicates with the other end portion 56b of the micro flow path 56 and the slits 31, 31,... (See FIG. 1). In addition, the other end portion 56 b of the microchannel 56 is supplied via the air inflow pipe 63.

  Here, as shown in FIG. 3, in each of the small reactors 51 of the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44, the catalysts 70, 71, 72 are disposed along the inner wall of the microchannel 56. Each is arranged.

The catalyst 70 is a catalyst for reforming a mixed gas (mixed gas) of methanol and water into hydrogen and carbon dioxide (see the above chemical reaction formula (1)), and copper and zinc are added to aluminum oxide as a support. It is a so-called “Cu / ZnO-based catalyst (Cu / ZnO / Al ₂ O ₃ compound)” supported. The catalyst 70 has a surface area of 65 m ² / g (measured by the BET method) or more and a ZnO crystallite diameter of 121 測定 (measured by the X-ray diffraction method (Scherrer method)) or less by a manufacturing method described later. Compared to known Cu / ZnO-based catalysts, a high methanol conversion can be maintained even in a low temperature environment of 300 ° C. or lower, and the amount of carbon monoxide produced as a by-product can be kept low ( (See FIG. 7).

  The catalyst 71 is a catalyst that shifts the mixture of carbon monoxide and water to hydrogen and carbon dioxide (see the above chemical reaction formula (3)), and the catalyst 72 selectively oxidizes carbon monoxide ( The chemical reaction formula (4))) catalyst.

In this embodiment, the catalyst 70 uses a porous aluminum oxide (alumina: Al ₂ O ₃ ) as a carrier. However, a compound other than the aluminum oxide may be used as a carrier, and copper and zinc may be used. The carrier may not be supported (the carrier may be omitted). Further, among the reactors of the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44, the catalysts 70, 71, 72 may be formed of the same type of catalyst, or different types. It may be formed with the catalyst. In any of the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44, each catalyst 70, 71, 72 may be formed of one type of catalyst, or a plurality of types of catalysts. The catalyst type may be different depending on the location in the microchannel 56.

  Next, a method for manufacturing the catalyst 70 disposed in the reforming reactor 42 will be described.

  First, an aqueous copper / zinc solution containing each metal salt of copper / zinc is prepared so that the molar ratio of copper to zinc is copper: zinc = 1: 2 to 8: 1. Prepare an alkaline solution and a suspension of aluminum oxide containing aluminum in a predetermined ratio (molar ratio) to copper / zinc (mixed solution in which aluminum oxide is suspended in pure water) (preparation step) ).

  In the above preparation step, the “copper / zinc aqueous solution” only needs to contain a copper / zinc metal salt as a water-soluble compound, but the “copper / zinc aqueous solution” is practically a nitric acid containing copper / zinc nitrate. It is preferable to use an aqueous copper / zinc nitrate solution. Therefore, in this embodiment, an example in which a copper nitrate / zinc nitrate aqueous solution is used as the “copper / zinc aqueous solution” is shown below. In the above preparation step, as the “alkali solution”, an alkali carbonate solution such as an aqueous sodium carbonate solution, a caustic alkaline solution such as sodium hydroxide or potassium hydroxide, or an aqueous sodium hydrogen carbonate solution may be used. , An alkali bicarbonate solution such as an aqueous potassium hydrogen carbonate solution may be used, or another alkali solution may be used. Since an alkaline solution is generally difficult to handle and expensive, it is preferable to use an aqueous sodium carbonate solution as the alkaline solution from the viewpoint of handling and economy. Therefore, in this embodiment, an example in which an aqueous sodium carbonate solution is used as the “alkali solution” is shown below.

  After the preparation step, a copper nitrate / zinc nitrate aqueous solution as a copper / zinc aqueous solution and a sodium carbonate aqueous solution as an alkaline solution were simultaneously dropped into the suspension of the aluminum oxide being stirred at the same time. A precipitate is formed by maintaining at 90 ° C. (preferably 50 to 70 ° C.) and pH 8.0 to 9.4 (preferably 8.4 to 9.3) (precipitation step).

  In the above precipitation step, since aluminum oxide is used as a carrier in the catalyst 70, a copper nitrate / zinc nitrate aqueous solution and a sodium carbonate aqueous solution are dropped into the aluminum oxide suspension. A copper / zinc nitrate aqueous solution and a sodium carbonate aqueous solution may be simultaneously dropped into distilled water being stirred to form a precipitate.

  After the precipitation step, the mixed solution containing the precipitate is filtered, and the precipitate remaining after the filtration is washed while being heated to a predetermined temperature in distilled water, and this filtration / washing step is repeated once or a plurality of times. . However, the first washing is performed at a temperature higher than the temperature maintained in the precipitation step. After the final washing, distilled water containing the precipitate is filtered again to obtain a precipitate. (Filtering and washing process).

After the filtration / washing step, the precipitate remaining after the last filtration is dried at about 100 ° C., and the dried precipitate is baked at a predetermined temperature (drying / baking step). A catalyst precursor (CuO / ZnO / Al ₂ O ₃ compound or CuO / ZnO compound) compression-molded into pellets can be obtained by the treatment in the drying / firing step.

After the drying / firing process, the catalyst precursor is heated in an air stream containing hydrogen to perform a hydrogen reduction treatment (reduction process), and the Cu / ZnO-based catalyst (Cu / ZnO / Al ₂ ) as the catalyst 70 from the catalyst precursor. O ₃ compound or CuO / ZnO compound) can be produced.

  Next, two filling methods for filling the catalyst 70 into the micro flow channel 56 of the small reactor 51 will be described separately as [first filling method] and [second filling method]. FIG. 5 is a drawing showing a first filling method for filling the catalyst 70 into the microchannel 56 over time, and FIG. 6 shows a second filling method for filling the catalyst 70 into the microchannel 56 over time. FIG.

[First filling method]
First, a silicon substrate 54 on which a twisted micro-channel 56 is formed in advance by cutting with sandblasting or the like is prepared (see FIG. 5A), and on one surface of the silicon substrate 54 (micro-channel 56). A photoresist 57 made of a dry film is affixed on the surface on which the film is formed (see FIG. 5B). After the photoresist 57 is pasted, the photoresist 57 is patterned to form an opening 58 in a portion corresponding to the micro flow path 56 of the photoresist 57 (see FIG. 5C).

  In the steps shown in FIGS. 5A to 5C, the microchannel 56 is formed by pasting a photoresist 57 on the silicon substrate 54 on which the microchannel 56 is previously formed. The microchannel 56 may be formed by attaching a photoresist 57 to the silicon substrate 54 before being patterned and patterning it in a distorted manner, and etching using the patterned photoresist 57 as a mask.

  After the opening 58 is formed, a dispersion liquid in which the catalyst precursor is dispersed in a solvent is applied to the surface of the photoresist 57 including the inner wall surface of the microchannel 56 and the inner wall surface of the opening 58, and the catalyst precursor is applied. A layer 59 (see FIG. 5D) is formed. The catalyst precursor dispersed in the solvent is a catalyst precursor before being subjected to the treatment in the drying / calcination step, and more specifically, a precipitate formed in the final filtration treatment in the filtration / washing step. is there.

  When the catalyst precursor layer 59 is formed, the photoresist 57 and the unnecessary catalyst precursor layer 59 formed on the surface of the photoresist 57 are removed from the silicon substrate 54 by a mechanical force to be removed. The catalyst precursor layer 59 is left only on the wall surface (see FIG. 5E). However, when the photoresist 57 is removed, if a little resist residue (scum) remains on the surface of the silicon substrate 54, the resist residue may be removed by oxygen plasma ashing.

  After the photoresist 57 is removed, a heater 55, which is an electric heating resistor made of a twisted metal oxide or the like, is formed on the other surface of the silicon substrate 54 (on the surface where the microchannel 56 is not formed). Then, a wiring for heating is connected to the heater 55 (see FIG. 5F). After the heater 55 is formed, a glass substrate 53 is overlaid on one surface of the silicon substrate 54, and in a high temperature environment of about 400 to 600 ° C., the silicon substrate 54 side becomes an anode and the glass substrate 53 side becomes a cathode about 1 kV. The glass substrate 53 and the silicon substrate 54 are anodic bonded (see FIG. 5G). Since the heater 55 heats the fluid flowing through the micro flow channel 56, the heater 55 may be disposed so as to overlap the micro flow channel 56 when seen in a plan view.

  When the glass substrate 53 and the silicon substrate 54 are anodically bonded, the heater 55 is operated to heat the silicon substrate 54, and the catalyst precursor layer 59 remaining on the inner wall surface of the microchannel 56 is dried and fired. After the catalyst precursor layer 59 has been dried and fired, one tube is connected to each of the one end 56a and the other end 56b of the micro flow channel 56, and the silicon substrate 54 is heated by the operation of the heater 55 again. Then, hydrogen (a mixed gas containing hydrogen) may be circulated in the microchannel 56 from the first to the other tube, and the catalyst precursor layer 59 is subjected to hydrogen reduction treatment.

  Through the above steps, the catalyst precursor layer 59 is chemically changed to a layer made of the catalyst 70, and the catalyst 70 can be filled in the microchannel 56 of the small reactor 51.

[Second filling method]
First, the silicon substrate 54 and the glass substrate 53 on which the twisted micro-channels 56 are formed by sandblasting or the like are overlapped with each other, and the silicon substrate 54 side is an anode in a high temperature environment of about 400 to 600 ° C. Then, a voltage of about 1 kV is applied so that the glass substrate 53 side becomes a cathode, and the glass substrate 53 and the silicon substrate 54 are anodically bonded (see FIG. 6A). When the glass substrate 53 and the silicon substrate 54 are anodically bonded, a twisted heater which is an electric heating resistor made of a metal oxide or the like on the surface of the silicon substrate 54 (on the surface where the microchannel 56 is not formed). 55 is formed, and wiring for heating is connected to the heater 55 (see FIG. 6B). Since the heater 55 heats the fluid flowing through the micro flow channel 56, the heater 55 may be disposed so as to overlap the micro flow channel 56 when seen in a plan view.

  After the heater 55 is formed, a pipe is connected to one end 56a and the other end 56b of the micro flow path 56, and the dispersion 80 in which the catalyst precursor is dispersed in the solvent is transferred from one pipe to the other pipe. The micro flow channel 56 is filled with the dispersion liquid 80 (see FIG. 6C). The catalyst precursor in the dispersion 80 is a catalyst precursor before being subjected to the treatment in the drying / calcination step, and specifically is a precipitate formed in the last filtration treatment in the filtration / washing step. is there.

  In addition, it is preferable to add to the dispersion liquid 80 a dispersant that increases the dispersibility of the catalyst precursor in a solvent, a thickener that prevents sedimentation and aggregation of the catalyst precursor in the solvent, and the like. When the dispersion liquid 80 is injected, in order to uniformly and quickly fill the inside of the micro flow path 56 with the dispersion liquid 80, the micro flow from one of the two pipes connected to the micro flow path 56 is made. A pressure may be applied to the inside of the channel 56, or a gas inside the micro channel 56 may be sucked.

  When the inside of the micro flow path 56 is filled with the dispersion liquid 80, the heater 55 is operated to heat the silicon substrate 54, and the dispersion liquid 80 is dried to form a catalyst precursor layer 81 along the inner wall surface of the micro flow path 56. (See FIG. 6 (d)).

  After the formation of the catalyst precursor layer 81, the silicon substrate 54 is heated by re-operation of the heater 55 to fire the catalyst precursor layer 81, and the silicon substrate 54 is operated by the operation of the heater 5, as in the first filling method. In a heated state, hydrogen (or a mixed gas containing hydrogen) is circulated in the microchannel 56 from one tube to the other tube, and the catalyst precursor layer 81 is subjected to hydrogen reduction treatment.

  Through the above steps, the catalyst precursor layer 81 is chemically changed to a layer made of the catalyst 70, and the catalyst 70 can be filled in the microchannel 56 of the small reactor 51.

Since the catalyst 70 has a relatively small crystallite size of ZnO crystallite diameter of 121 mm (measured value by X-ray diffraction method) or less, the surface area of the unit weight of the catalyst is 65 m ² / g (measured value by BET method). This can be done. Therefore, since a lot of fine particles are dispersed in the catalyst 70, the actual surface area of the catalyst 70 per unit area of the microchannel 56 to which the catalyst 70 is attached can be increased, and the unit area of the microchannel 56 is increased. In contrast, the rate at which the chemical reaction caused by the catalyst 70 occurs can be improved.

Then, operation | movement of the electric power generating apparatus 1 is demonstrated.
When the power generation device 1 is started, the power generation system of the power generation device 1 starts to function, and the heaters 55 of the reactors of the vaporizer 41, the reforming reactor 42, the aqueous shift reactor 43, and the selective oxidation reactor 44 generate heat. At the same time, a member such as a micropump in the power generation module 3 is activated, and the fuel 99 stored in the fuel tank 8 is sucked into the suction nipple portion 37 and the small reaction of the carburetor 41 through the inflow pipe 61 of the carburetor 41. While being supplied to the micro flow path 56 of the vessel 51, oxygen in the outside air is sucked from each slit 31 and supplied to the air electrode of the fuel cell 91.

  The fuel 99 supplied to the carburetor 41 is vaporized by receiving the heat of the heater 55 while flowing in the micro flow path 56 from one end 56a to 56b, and changes into a mixture of methanol and water vapor. Then, the internal pressure of the micro flow path 56 rises and convection occurs, and the mixture gas is passed from the outflow pipe 62 of the vaporizer 41 to the reforming reactor 42, the aqueous shift reactor 43, the selective oxidation reactor 44, and the fuel cell. It flows to 91 in order through each inflow pipe 61 and outflow pipe 62.

  In the reforming reactor 42, the air-fuel mixture generated in the vaporizer 41 flows in the micro flow channel 56 of the small reactor 51 from the other end 56b toward the one end 56a. At this time, the air-fuel mixture is heated by the heater 55 and is subjected to the catalytic action of the catalyst 70 to cause a reaction like the above chemical reaction formula (1), and hydrogen and carbon dioxide are generated from the air-fuel mixture of methanol and water vapor. The In the reforming reactor 42, the air-fuel mixture may not be completely reformed to hydrogen and carbon dioxide. In this case, as shown in the chemical reaction formula (2), carbon dioxide, Carbon monoxide and water vapor are produced. That is, in the reforming reactor 42, the reaction in which methanol is converted to hydrogen according to the chemical reaction formula (1) and the reaction in which carbon monoxide is generated according to the chemical reaction formula (2) occur almost simultaneously.

  Here, the chemical reaction formula is measured by measuring the methanol conversion rate (ratio in which methanol is converted into hydrogen) and the carbon monoxide concentration in the reforming reactor 42 with respect to the heating temperature (reforming temperature) of the heater 55. A graph showing how much each chemical change shown in (1) and chemical reaction formula (2) depends on the reforming temperature (how much the catalytic function of the catalyst 70 according to the present invention depends on the reforming temperature). This will be described with reference to FIG.

  FIG. 7 shows the concentration of carbon monoxide generated with respect to the heating temperature of the heater 55. In FIG. 7, “CO concentration” indicates the carbon monoxide concentration when the chemical reaction formula (2) reaches equilibrium. Further, the mixture of the fuel 91 flowing in the micro flow path 56 of the reforming reactor 42 has a steam carbon ratio S / C (water / methanol molar ratio) = 2.

  As can be seen from FIG. 7, in the reforming reactor 42, the carbon monoxide concentration increases as the reforming temperature increases, and decreases as the reforming temperature decreases. That is, in the reforming reactor 42 to which the catalyst 70 according to the present invention is applied, it is possible to prevent the catalytic function of the catalyst 70 from being lowered even at a low reforming temperature, and to further suppress the amount of carbon monoxide produced. Can do.

In particular, as described above, the catalyst 70 produced in this embodiment has a surface area of 65 m ² / g (measured value by BET method) or more and a ZnO crystallite diameter of 121 Å (measured value by X-ray diffraction method) or less. From FIG. 7, a good result shown in FIG. 7 can be obtained, but the surface area is less than 65 m ² / g (measured value by BET method) and the ZnO crystallite diameter exceeds 121 mm (measured value by X-ray diffraction method). With a / ZnO-based catalyst, the results shown in FIG. 7 cannot be obtained.

  In the aqueous shift reactor 43, the air-fuel mixture composed of hydrogen, carbon monoxide, carbon dioxide and water vapor generated in the reforming reactor 42 passes through the inside of the microchannel 56 of the small reactor 51 from the one end 56a to the other end. It flows toward the part 56b. At this time, the air-fuel mixture receives the catalytic action of the catalyst 71 while being heated by the heater 55 and causes a reaction like the above chemical reaction formula (3), and carbon dioxide is generated from the carbon monoxide and the water vapor to produce the monoxide. Carbon is detoxified.

  In the selective oxidation reactor 44, an air-fuel mixture composed of carbon dioxide generated in the aqueous shift reactor 43 and unreacted carbon monoxide, hydrogen, and carbon dioxide in the aqueous shift reactor 43 is supplied from the inflow pipe 61 to a small reactor. It flows into the other end part 56 b of the microchannel 56 of 51. In the selective oxidation reactor 44, oxygen in the outside air sucked from each slit 31 also flows from the air inflow pipe 63 into the other end portion 56 b of the microchannel 56 of the small reactor 51.

  Thereby, in the selective oxidation reactor 44, the air-fuel mixture that has passed through the inflow pipe 61 from the small reactor 51 of the aqueous shift reactor 43 and the oxygen in the outside air that has passed through the air inflow pipe 63 are converted into the micro flow path of the small reactor 51. At the other end 56 b of 56, they merge together and are mixed (mixed), and an air-fuel mixture (including oxygen in the outside air) composed of carbon monoxide, hydrogen and carbon dioxide is contained in the micro flow channel 56 of the small reactor 51. Flows from the other end 56b toward the one end 56a. At this time, the air-fuel mixture is heated by the heater 55 and receives the catalytic action of the catalyst 72 to cause a reaction (aqueous shift reaction) as shown in the chemical reaction formula (4), and carbon dioxide is converted from carbon monoxide and oxygen. Generated.

  In the selective oxidation reactor 44, since the catalyst 72 of the small reactor 51 selectively promotes the reaction represented by the chemical reaction formula (4), hydrogen is hardly oxidized in the air-fuel mixture flowing through the microchannel 56. It is like that. Further, when the air-fuel mixture flowing through the micro flow channel 56 reaches the outflow pipe 62 of the selective oxidation reactor 44, the air-fuel mixture hardly contains carbon monoxide, and the concentrations of hydrogen and carbon dioxide are very high. It is high. If the carbon monoxide generated in the reforming reactor 42 can be sufficiently removed, only one of the aqueous shift reactor 43 and the selective oxidation reactor 44 may be provided.

  Thereafter, carbon dioxide and water vapor generated through the reactors of the reformer 40 are exhausted from the exhaust holes 33 to the outside air through the outflow pipes 62 of the selective oxidation reactor 44 as by-products. On the other hand, hydrogen generated through each reactor of the reformer 40 is supplied as a main product to the fuel electrode of the fuel cell 91 through the outflow pipe 62 of the selective oxidation reactor 44.

  In the fuel cell 91, the hydrogen supplied from the reformer 40 undergoes a reaction as shown in the electrochemical reaction formula (5) at the fuel electrode and is separated into hydrogen ions and electrons. Hydrogen ions are conducted to the air electrode through the ion conductive membrane, and electrons are taken out by the fuel electrode. In the fuel cell 91, oxygen in the outside air is taken in through the slits 31 and supplied to the air electrode. And oxygen taken in from the outside air, hydrogen ions that have passed through the ion conductive membrane, and electrons taken out by the fuel electrode cause a reaction as shown in the electrochemical reaction formula (6) at the air electrode, Water as a by-product is produced.

  In the fuel cell 91, electric energy is generated by the occurrence of an electrochemical reaction such as the above electrochemical reaction formulas (5) and (6). The generated electrical energy charges a charging unit (not shown) such as a secondary battery provided inside the power generation apparatus 1 and is supplied from the charging unit to an external device (not shown) through the terminal 32 of the power generation module 3. Or used as energy for driving each heater 55, micropump or other member. Further, by-product water generated at the air electrode of the fuel cell 91 moves to the fuel storage module 2 through the second drain pipe 34 and the first drain pipe 6 and is drained and stored in the drain container 7.

In the present embodiment described above, a Cu / ZnO-based catalyst having a ZnO crystallite diameter of 121 mm or less and a surface area of 65 m ² / g or more is applied as the catalyst 70. Even if the surface area of the catalyst 70 is large and the reforming reactor 42 is in a low temperature environment of 300 ° C. or lower, it is possible to prevent the catalytic activity from being lowered. Therefore, in this embodiment, in each step of the manufacturing method of the catalyst 70, the composition ratio of copper and zinc during the preparation step, the temperature / pH during the precipitation step, the washing temperature during the filtration / washing step, etc. Therefore, the catalyst 70 that prevents the catalyst activity from being reduced in a low temperature environment of 300 ° C. or lower can be manufactured.

  In Example 1, five types of Cu / ZnO-based catalysts having different component ratios of copper and zinc were produced, and the methanol conversion rate (ratio of hydrogen generation from methanol) of each Cu / ZnO-based catalyst was measured. .

First, five types of copper nitrate / zinc nitrate aqueous solution (copper / zinc combined) with a molar ratio of copper and zinc of copper: zinc = 1: 8, 3: 6, 6: 3, 8: 1, 1: 0. In addition, a 0.5 mol / l sodium carbonate aqueous solution and a surface area of about 110 m ² / g (measured by the BET method) and 0.01 mol of aluminum are contained. An aluminum oxide suspension was prepared (preparation step).

  After the preparation process, for each of the five types of copper nitrate / zinc nitrate aqueous solutions, the copper nitrate / zinc nitrate aqueous solution and the sodium carbonate aqueous solution were simultaneously added dropwise to the suspension of the aluminum oxide being stirred, respectively, and the mixed solution being added dropwise Was kept at 60 ° C. and pH 9.2 to form a precipitate (precipitation step).

  After the precipitation step, the mixed solution containing the precipitate was kept stirred for 1 hour and then allowed to stand for 12 hours. After 12 hours, the mixture was filtered, and the precipitate remaining after filtration was washed in distilled water with stirring for 20 minutes. This filtration / washing process was repeated a total of 4 times. However, the first cleaning was performed while maintaining at 90 ° C., and the second and subsequent cleanings (from the second to the fourth) were performed while maintaining at 60 ° C. After the final 4th washing, distilled water containing the precipitate was filtered again to obtain a precipitate (filtering and washing step).

After the filtration / washing step, the precipitate remaining after the last filtration was dried at 100 ° C. for 12 hours, and the dried precipitate was baked at 360 ° C. for 1 hour (drying / baking step). After the drying / firing process, a catalyst precursor (CuO / ZnO / Al ₂ O ₃ compound) compressed into a pellet was obtained.

Thereafter, the catalyst precursor was pulverized and sieved, and a granular catalyst precursor having a size of 0.5 to 1 mm was selected. A tubular reactor with an inner diameter of 8 mm is filled with 0.25 ml of the granular catalyst precursor, and the catalyst precursor in the tubular reactor is exposed to a hydrogen stream for 1 hour while being heated at 300 ° C. to perform hydrogen reduction treatment. (Reduction process), a Cu / ZnO-based catalyst (Cu / ZnO / Al ₂ O ₃ ) was generated from the catalyst precursor.

While heating the tubular reactor filled with the Cu / ZnO-based catalyst produced in the reduction step to 250 ° C., GHSV (Gas Hourly Space Velocity) = 100,000 hr ⁻ A mixture of water and methanol (S / C ratio = 2) was circulated at a rate of ¹ to convert the methanol in the mixture to hydrogen (methanol conversion step), and the methanol conversion rate after the methanol conversion step (%) Was measured.

  Table 1 shows the methanol conversion rates of five types of Cu / ZnO-based catalysts having different component ratios of copper and zinc. Table 1 also shows the methanol conversion rate of a commercially available industrial Cu / ZnO-based catalyst as a comparative example.

  As can be seen from the measurement results in Table 1, a Cu / ZnO catalyst prepared with a copper / zinc component ratio in a range of copper: zinc = 3: 6-8: 1 is a commercially available industrial Cu / ZnO catalyst. In particular, the Cu / ZnO-based catalyst when the component ratio of copper and zinc was copper: zinc = 3: 6 had a maximum activity.

  In Example 2, two types of Cu / ZnO-based catalysts with different temperature conditions were produced in the precipitation step, and the methanol conversion rate of each Cu / ZnO-based catalyst was measured. However, in Example 2, the processing contents and conditions of the preparation process and the precipitation process of Example 1 are slightly different, and all other processes of the filtration / washing process, drying / calcination process, reduction process, and methanol conversion process are performed. Same as Example 1.

In the preparation process of Example 2, one type of copper nitrate / zinc nitrate aqueous solution (copper / zinc was combined to make a total of 0.09 mol) in which the molar ratio of copper to zinc was copper: zinc = 6: 3, A 0.5 mol / l aqueous sodium carbonate solution and a suspension of aluminum oxide having a surface area of 150 m ² / g (measured by the BET method) and containing 0.01 mol of aluminum were prepared.

  In the precipitation step of Example 2, the mixed solution was maintained at 60 ° C. or 90 ° C. (pH 9.4) to form two types of precipitates having different temperature conditions. For each precipitate, Example 1 and The same filtration / washing step, drying / calcination step, reduction step and methanol conversion step were carried out to measure the methanol conversion (%).

  Table 2 shows the methanol conversion rates of two types of Cu / ZnO-based catalysts having different temperature conditions in the precipitation step. Table 2 also shows the methanol conversion rate of a commercially available industrial Cu / ZnO-based catalyst as a comparative example.

  As can be seen from the measurement results in Table 2, the Cu / ZnO-based catalyst in which the temperature of the precipitation step is maintained at 60 ° C. is a Cu / ZnO-based catalyst maintained at 90 ° C. in the precipitation step or a commercially available Cu / ZnO-based catalyst. It showed higher activity.

  In Example 3, five types of Cu / ZnO-based catalysts with different pH conditions were produced in the precipitation step, the methanol conversion rate of each Cu / ZnO-based catalyst, the surface area of each Cu / ZnO-based catalyst, and ZnO particles. The diameter was measured. However, in Example 3, the contents and conditions of the preparation process and precipitation process of Example 1 are slightly different, and all other processes of the filtration / washing process, drying / calcination process, reduction process and methanol conversion process are performed. Same as Example 1.

In the preparation step of Example 3, one kind of copper nitrate / zinc nitrate aqueous solution (copper / zinc was combined to make a total of 0.09 mol) in which the molar ratio of copper to zinc was copper: zinc = 6: 3, A 0.5 mol / l aqueous sodium carbonate solution and a suspension of aluminum oxide having a surface area of 150 m ² / g (measured by the BET method) and containing 0.01 mol of aluminum were prepared.

In the precipitation step of Example 3, the mixed solution was kept at pH 8.0, pH 8.4, pH 8.8, pH 9.3, or pH 9.4 (temperature is 60 ° C.), respectively, and the three kinds of pH conditions were different from each other. Each precipitate is formed, and each precipitate is subjected to the same filtration / washing step, drying / calcination step, reduction step and methanol conversion step as in Example 1, and the methanol conversion rate of each Cu / ZnO-based catalyst. (%), Surface area (measured value by BET method (m ² / g)) and ZnO particle diameter (crystallite diameter (Å)) were measured.

  In addition, the ZnO particle diameter of each Cu / ZnO-based catalyst was measured using a well-known X-ray diffractometer while following the Scherrer method.

  Table 3 shows the methanol conversion, surface area, and ZnO particle diameter of each of the three types of Cu / ZnO-based catalysts having different pH conditions in the precipitation step. Table 3 also shows the methanol conversion rate of a commercially available industrial Cu / ZnO-based catalyst as a comparative example.

As can be seen from the measurement results in Table 3, the Cu / ZnO-based catalyst produced by maintaining the pH of the precipitation step in the range of 8.0 to 9.4 has a methanol conversion rate of more than 65%, and is commercially available. It showed higher activity than the Cu / ZnO-based catalyst. Further, the Cu / ZnO-based catalyst when the pH of the precipitation step is maintained at 8.0 to 9.3 has a surface area of 65 m ² / g (measured by the BET method) or more and a methanol conversion rate of more than 70%. The Cu / ZnO-based catalyst when the pH of the precipitation step is maintained at 8.4 to 9.3 has a surface area of 70 m ² / g (measured by the BET method) or more, the conversion rate exceeds 78%, and the activity is high It was remarkable. All of the five types of Cu / ZnO-based catalysts had a surface area of 65 m ² / g or more and a ZnO particle diameter of 121 mm or less.

  In Example 4, two types of Cu / ZnO-based catalysts with different temperature conditions were produced in the filtration / washing step, and the methanol conversion of each Cu / ZnO-based catalyst was measured. However, in Example 4, the contents and conditions of the preparation process, precipitation process and filtration / washing process of Example 1 are slightly different, and all other processes of the drying / calcination process, reduction process and methanol conversion process are performed. Same as Example 1.

In the preparation step of Example 4, one kind of copper nitrate / zinc nitrate aqueous solution (copper / zinc was combined to make a total of 0.09 mol) in which the molar ratio of copper and zinc was copper: zinc = 6: 3, A 0.5 mol / l aqueous sodium carbonate solution and a suspension of aluminum oxide having a surface area of 150 m ² / g (measured by the BET method) and containing 0.01 mol of aluminum were prepared.

  In the precipitation step of Example 4, a precipitate was formed in the same manner as in Example 1 except that the mixed solution was maintained at 60 ° C. and pH 9.4.

  In the filtration / washing step of Example 4, the first washing was heated to 90 ° C. or 60 ° C. (both the second and subsequent washings were heated to 60 ° C.). Two different types of precipitates are produced, and each of the washed precipitates is subjected to the same treatments as the drying / calcination step, reduction step and methanol conversion step in Example 1 to obtain the methanol conversion rate (%). It was measured.

  Table 4 shows the methanol conversion rates of two types of Cu / ZnO-based catalysts having different temperature conditions at the time of the first washing in the filtration / washing step. Table 4 also shows the methanol conversion rate of a commercially available industrial Cu / ZnO-based catalyst as a comparative example.

  As can be seen from the measurement results in Table 4, the Cu / ZnO-based catalyst in which the temperature at the first washing in the filtration / washing process is 90 ° C. is set to 60 ° C. at the first washing in the filtration / washing process. It showed higher activity than the obtained Cu / ZnO-based catalyst and commercially available industrial Cu / ZnO-based catalyst.

  In Example 5, in the methanol conversion process using the produced catalyst, the heating temperature was set to 250 ° C. in Example 1, but the methanol conversion rate of the Cu / ZnO-based catalyst was changed to 280 ° C. It was measured. However, in Example 5, the contents and conditions of the preparation process, drying / calcination process, reduction process, and methanol conversion process of Example 1 are slightly different, and all other precipitation processes and filtration / washing processes are the same as in Example 1. Same as above.

  In the preparation process of Example 5, as a copper nitrate / zinc nitrate aqueous solution, one type of copper nitrate / zinc nitrate aqueous solution (copper / zinc combined with copper / zinc = 6: 3) was used. 0.09 mol) was prepared.

  After preparing the copper nitrate / zinc nitrate aqueous solution, the same precipitation process and filtration / washing process as in Example 1 are performed, and the precipitate remaining in the last filtration process of the filtration / washing process is dispersed in the solvent. The dispersion is injected into a microchannel of a small reactor similar to the small reactor 51 in the above embodiment and dried at about 100 ° C. for 12 hours with a heater, and the layer of the dispersion remaining after drying is heated with a heater. Firing was carried out at 360 ° C. for 1 hour (drying / firing step) to form a catalyst precursor layer on the inner wall surface of the microchannel.

  When the catalyst precursor layer is formed in the microchannel of the small reactor, hydrogen is passed through the microchannel for 30 minutes while heating the microchannel of the small reactor to 250 ° C. with a heater. Hydrogen reduction treatment was performed (reduction process), and the inside of the microchannel was filled with a Cu / ZnO-based catalyst.

After the Cu / ZnO-based catalyst is filled in the microchannel, the small reactor is heated to 280 ° C. with a heater, and the mixture of water and methanol (SSV) is supplied to the microchannel at a rate of GHSV = 200,000 hr ^−1. / C = 2) was circulated, methanol in the gas mixture was converted to hydrogen (methanol conversion step), and the methanol conversion rate (%) after the methanol conversion step was measured.

  Table 5 shows the methanol conversion of the Cu / ZnO-based catalyst in which the small reactor was heated to 280 ° C. Table 5 also shows the methanol conversion rate of a commercially available industrial Cu / ZnO-based catalyst as a comparative example.

As can be seen from the measurement results in Table 5, the Cu / ZnO catalyst heated to 280 ° C. at a rate of GHSV = 200,000 hr ⁻¹ in the methanol conversion process shows higher activity than the commercially available industrial Cu / ZnO catalyst. It was.

It is a partially broken perspective view of a power generator. It is the block diagram which showed the basic composition of the electric power generation system of an electric power generating apparatus. It is sectional drawing of a reformer. It is drawing which shows the silicon substrate of each small reactor. It is drawing which showed the 1st filling method which fills a catalyst with a micro channel over time. It is drawing which showed the 2nd filling method which fills a catalyst with a micro channel over time. It is drawing which shows the carbon monoxide density | concentration with respect to reforming temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generation device 2 Fuel storage module 3 Power generation module 40 Reformer 41 Vaporizer 42 Reformer reactor 43 Water shift reactor 44 Selective oxidation reactor 51 Small reactor 53 Glass substrate 54 Silicon substrate 55 Heater 56 Micro flow path 70, 71, 72 Catalyst 91 Fuel cell 99 Fuel

Claims (8)

A Cu / ZnO-based catalyst having a surface area of 65 m ² / g or more. In the Cu / ZnO-based catalyst according to claim 1,
A Cu / ZnO-based catalyst having a ZnO crystallite diameter of 121 mm or less. A copper / zinc aqueous solution containing a copper / zinc metal salt in which the molar ratio of copper and zinc is copper: zinc = 1: 2 to 8: 1 and an alkaline solution are mixed at 50 to 70 ° C. to form a precipitate. A precipitation step to form,
A drying / firing step for drying / firing the precipitate;
A process for producing a Cu / ZnO-based catalyst, comprising: A precipitation step in which a copper / zinc aqueous solution containing a metal salt of copper / zinc and an alkaline solution are mixed while maintaining a pH of 8.0 to 9.4 to form a precipitate;
A drying / firing step for drying / firing the precipitate;
A process for producing a Cu / ZnO-based catalyst, comprising: In the manufacturing method of the Cu / ZnO-type catalyst of Claim 3 or 4,
After the precipitation step, it has a filtration / washing step of filtering the mixed solution and washing the precipitate remaining after the filtration,
In the filtration / washing step, the precipitate remaining after filtration is washed at a temperature higher than the temperature of the mixed solution in the precipitation step. In the manufacturing method of the Cu / ZnO-type catalyst as described in any one of Claims 3-5,
In the precipitation step, the copper / zinc aqueous solution and the alkaline solution are mixed in an aqueous solution containing an aluminum oxide. In the electric power generating apparatus using the Cu / ZnO-based catalyst according to claim 1,
A reforming reactor for producing hydrogen from a mixture of methanol and water;
A fuel cell that generates electrical energy from hydrogen generated in the reforming reactor;
With
The reforming reactor is formed with a flow path for flowing a mixture of methanol and water, and the Cu / ZnO-based catalyst is arranged in the flow path. The power generator according to claim 7,
A power generation apparatus comprising a reactor for removing carbon monoxide produced in the reforming reactor.

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