JP6005331B2 - Hydrogen generation method for generating hydrogen from water - Google Patents

Description

  The present invention relates to a hydrogen generation method for generating hydrogen from water.

  A method in which nickel, chromium and iron elements are dissolved in an alkali metal molten salt, fine particles are scattered in the reaction space from the liquid surface of the molten salt, and water is collided with the fine particles to collect hydrogen from water. The applicant has filed several applications.

Japanese Patent Application No. 2009-9733 Japanese Patent Application No. 2009-125 Japanese Patent Application No. 2009-120757 Japanese Patent Application No. 2009-0356

  However, although these applications recognize that hydrogen can be collected in large quantities, the recognition that it is important not to allow oxygen to exist in the reaction space is not sufficient.

Accordingly, the hydrogen generation method of the present invention comprises melting at least the surface of an alkali molten salt composed of at least one alkali metal hydroxide containing sodium hydroxide, potassium hydroxide and barium hydroxide, and adding nickel into the melt. At least one first metal of Group 10 metals including palladium and platinum, and at least one second metal of transition metals of other groups including chromium, molybdenum, tungsten, cobalt, and iron. Melting, supplying the first metal and the second metal from a metal element supplier, and fine particles containing an alkali molten salt, the first and second metal element ions, and electrons from the liquid surface of the melt groups allowed scattered in the reaction space of trace oxygen state, caused to collide steam by which the hydrogen gas from the hydrogen in the water vapor to the fine particles, in the reaction To form a compound in Oite metal element supply surface, and the compound as allowed to act as a catalyst.

The alkali molten salt is a sodium hydroxide salt heated to 300 ° C. or higher, and the first and second metals are preferably supplied with SUS304.
Further, the alkali molten salt and the first and second metals are accommodated in a reaction furnace, and when the reaction space becomes negative pressure, an inert gas is supplied into the reaction space and air flows into the reaction space. It is preferable to prevent this from happening and maintain a trace oxygen state.

Furthermore, the alkali molten salt and the first and second metals are accommodated in a reaction furnace, an on-off valve is provided on the hydrogen outlet side of the reaction furnace, and the on-off valve is closed to set the pressure in the reaction space to a predetermined value. After the positive pressure is reached, water is injected to generate hydrogen, and when the pressure rises, the on-off valve is opened and hydrogen is discharged from the hydrogen outlet. It is preferable to maintain the space at a positive pressure to prevent the inflow of air from the outside into the reaction space and maintain a trace oxygen state.

  Furthermore, the alkali molten salt and the first and second metals are housed in a reaction furnace, and a relief valve is provided on the hydrogen outlet side of the reaction furnace, and the relief valve releases pressure at a predetermined positive pressure. Thus, it is preferable to inject water at a predetermined timing and discharge hydrogen by releasing the relief valve.

A solution obtained by melting the first and second metal ions in an alkali molten salt is stored in a reaction vessel, and fine particles are scattered, and the reaction vessel is set in an oxygen-free state (hereinafter including the concept of a trace oxygen state). When the water vapor collides with the fine particle group, the fine particle group has a large hygroscopic property, so that the water vapor is adsorbed on the surface of the fine particle group, and alkali metal ions (Na ⁺ , K ⁺ etc.), first metal ions (Ni ²⁺ , Pd ²⁺ , Pt ²⁺ ) and secondary metal ions (Cr ²⁺ , Mo ²⁺ , Fe ³⁺ , W ^2+, etc.), hydrogen in the water vapor is separated and hydrogen gas (H ₂ ) occurs. Thus, the reaction becomes active in an anoxic state. In addition, since oxygen does not exist at all in the state of gas, even if the inside of the reaction vessel is 300 ° C. or higher, it is safe without explosion.

  If sodium hydroxide at 300 ° C. or higher is used as the alkali molten salt, the reaction is more active than other molten salts, and the mixing ratio of the first and second metals is SUS304 (18Cr-8Ni-residual Fe) was the most appropriate and produced the largest amount of hydrogen. Further, it is necessary to make the system in an oxygen-free state in order to activate the reaction. If the negative pressure in the reaction space is prevented by inflow of an inert gas, the oxygen-free state can be maintained. Furthermore, if an on-off valve or a relief valve is provided on the hydrogen outlet side of the reaction vessel and the reaction space is always maintained at a positive pressure by this valve operation, the inflow of oxygen from the outside can be effectively prevented.

It is a schematic structure figure of the hydrogen generator for carrying out the hydrogen generating method of the present invention. It is a phase diagram of fine particles scattered from the molten salt It is an experiment figure which shows reaction of a fine fine particle group and water vapor | steam. It is a figure which shows the state of the oxide in the state which put air in the reaction furnace. It is a figure which shows the state of an oxide when the inside of a reaction furnace is made into an oxygen-free state. FIG. 3 is a first relationship diagram between temperature and pressure when a reactant is heated. It is a 2nd relationship figure of the temperature when a reactant is heated. It is a graph which shows the pressure reduction in a reaction furnace when making the temperature of a reactant constant. FIG. 3 is a structural diagram showing a negative pressure prevention means in a reaction space. It is a block diagram of the non-return valve which is a negative pressure prevention means of reaction space. It is a system diagram which shows the control system of hydrogen generation. It is a figure which shows valve operation of the control system of FIG. It is a figure which shows the other valve operation of the control system of FIG. It is a front view which shows the specific structure of a reaction furnace. It is a side view which shows the specific structure of a reaction furnace. It is a partial cross section figure which shows the internal structure of a reaction cell. It is a figure which shows the hollow state of the reaction cell.

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

  In FIG. 1, a hydrogen generator M according to the present invention has a heating furnace 1, a heating burner 2 is built in the lower part of the heating furnace 1, and a reaction vessel 3 heated by the heating burner 2 It is stored in the upper part. The reaction vessel 3 has a spherical shape, and a steam coil 4 for making steam is wound around it. The steam coil 4 is supplied with water from a water tank 6 through a water pipe 5. The water tank 6 is provided with a water supply pipe 8 having a valve 7. The water pipe 5 has a flow rate adjusting valve 9 Is provided. A steam pipe 10 extends from the lower end of the steam coil 4, and the steam pipe 10 extends into the reaction container 3 through the lid 3 b of the neck 3 a of the reaction container 3. The lid 3b is provided with an argon purge pipe 3c for bringing the inside of the system into a trace oxygen state.

  In the reaction vessel 3, a hot air pipe 11 for allowing hot air to pass therethrough is branched into an upper part and extends, and the branched branch pipes 11 a and 11 a extend into the reaction space S. A reactant 12 is accommodated in the lower part of the container 3, and metal element supply bodies 13, 13, 13 are accommodated in the reactant 12. The reaction vessel 3 is supported by support grids 14 and 14 provided in the heating furnace 1, and hot air generated by the heating burner 2 is heated outside the reaction vessel 3 and then discharged to the outside through an exhaust cylinder 15. Is done.

  The hydrogen generated in the reaction vessel 3 is sent from the hydrogen pipe 14 to the water vapor removing device 15 forming a water tank, and the hydrogen from which the water vapor has been removed is sent to a cylinder (not shown). The hydrogen pipe 14 is provided with a vacuum pump 16, check valves 17 and 18 are provided before and after the vacuum pump 16, and a generated gas measuring device 19 (measures the pressure in the system) downstream of the check valve 18. Is provided).

  The reactant 12 is an alkali metal hydroxide such as sodium hydroxide (NaOH) or potassium hydroxide (KOH), and the reactant is heated to 350 to 500 ° C. to form a molten salt. In this molten salt, at least one metal element of the periodic table group 10 such as nickel, palladium and platinum from the metal element supplier 13 and other groups such as chromium, molybdenum, iron, cobalt, tungsten, etc. Among the transition metals, at least one kind of metal element is supplied as those ions, and specifically, 18-8 stainless steel (SUS304; 18Cr—Ni8—residual Fe) is most preferable.

  The group 10 metal element acts to break the OH bond, and the other group transition metals seem to assist the OH bond breakage. Only one of these two metal elements is active. Can't happen.

From the liquid surface of the molten salt, invisible fine particle groups protrude, and the components appear to be as shown in FIG. That is, the molten salt itself is ionized with sodium ions (Na ⁺ ) and hydroxyl ions (OH ⁻ ) at 350 ° C. to 500 ° C., and each ion (Fe ²⁺ , Ni ²⁺ , Cr ³⁺ ) eluted from SUS304. ) Is included. In addition, it contains electrons (e−) emitted when the components of SUS304 are eluted.

1. Experimental example (1) Experiment that main reaction is fine particle group and water vapor (first experimental example)
In FIG. 3, the reactant 12 is stored in a fine particle generating cylinder 30, the generating cylinder 30 is heated by a heater 31, and a group of fine particles from the generating cylinder 30 is supplied from a pipe 32 provided with a valve 33 to a reaction cylinder. 33 It comes to enter a . The reaction cylinder 33 a includes a water pipe 34, a water receiver 35, and a hydrogen pipe 36, and the reaction cylinder 33 a is heated by a heater 37. Predetermined time, after pooled by heating occurs cylinder 30 with open valve 33 fine particles in the reaction cylinder 33 a, closing the valve 33, the water tube 34 to supply water in the reaction cylinder 33 a When steam was made, hydrogen was detected from the hydrogen pipe 36. As a result, it was found that the main reaction was a group of fine particles and water vapor, and it did not occur in the molten salt of the generating cylinder 30. Therefore, the surface area of the fine particles was extremely large, and most of the hydrogen contained in the water supplied by one supply of water was collected.

(2) Experiments in which the reaction differs when air is introduced into the system, when a small amount of air is added, and when the air is completely shut off (second experimental example)
In FIG. 1, air is introduced from an argon purge pipe 3c attached to the lid 3b of the reaction vessel 3, and a predetermined amount of water in the water tank 6 is supplied by the steam coil 4 without operating the vacuum pump 16. Was supplied to the reaction space S of the reaction vessel 3 through the steam pipe 10.

If the reaction is continued while air is introduced in this manner, a layered oxide 130 (NaFeO ₂ , NaCrO ₂ ) of Basabasa is formed in the reactor 3 as shown in FIG. 4, and the reaction takes ₂ to 3 days. Stopped. However, conversely, when the vacuum pump 16 is operated for a short time and the reaction is continued with a trace amount of oxygen in the system, a hard compound 131 can be formed into a layer on the metal surface as shown in FIG. 5, and when this component was analyzed, NaFeO ₂ , Na ₂ CrO ₄ , Fe · Ni alloy. Incidentally, the compound 131, that have been found to be 800 do not melt even when heated above ℃ the liquid NaOH acts as a catalyst is also no longer present in the reactor 3. Also, when is prolonged operating the vacuum pump 16 to be in the system complete absence of oxygen, the compound 131 is not generated, the reaction was carried out more actively.

(3) Experiment of storing hydrogen in the semi-molten state of reactant 12 (third experiment example)
When the pressure in the reaction furnace 3 is measured by the generated gas measuring device 19 while the temperature in the reaction furnace 3 is gradually increased from room temperature, the pressure decreases slightly from the increase and then increases. Is known. That is, as shown in FIGS. 6 and 7, when the temperature is gradually increased from room temperature, the hydrogen in the reactor 3 expands and the pressure increases, but the reactant becomes a semi-molten state 200. The pressure once falls between ℃ and 300 ℃. At normal temperature, hydrogen contracts (hydrogen generated at 400 ° C to 500 ° C remains in the reactor 3 and when the temperature is lowered to normal temperature, the hydrogen contracts and becomes negative pressure). As the temperature rises, the hydrogen gas expands and the pressure in the furnace rises, but the pressure falls between 200 ° C. and 300 ° C., and rises again when it passes the temperature range. Therefore, if the temperature is maintained in the temperature range (250 ° C. to 280 ° C.), the pressure can be lowered from that at the normal temperature as shown in FIG.

  Furthermore, when the temperature is maintained at around 500 ° C. and the pressure is maintained at a positive pressure (for example, 0.05 MPa or more), the reactant can absorb hydrogen and the pressure drops to almost normal pressure.

2. analysis
1) The main reaction is a reaction between a group of fine particles of the reactant and water vapor, and the fine particles collide with water vapor and appear to react as follows.

^{_{2H 2 O + 2e - → H}} 2 ↑ + 2OH - ...... (1)
That is, water vapor (2 H ₂ O) reacts with the electrons (e ⁻ ) in the fine particles and is ionized to generate hydrogen gas (H ₂ ). Here, electrons (e ⁻ ) are emitted from molten Fe ³⁺ , Cr ²⁺ , and Ni ²⁺ , and sodium ions (Na ⁺ ) in the fine particles are generated by heat and collision energy of 300 to 500 ° C. e ^-) is expected to emit, by the presence of sufficient electron (1) of the reaction is ensured. Then
_{^{2 OH - → H 2 O +}} O 2- ...... (2)
By this reaction, water vapor and radical oxygen (O ²⁻ ) are generated.

The water vapor (H ₂ O) here generates hydrogen (H ₂ ) again by the reaction of the formula (1), and after the reaction of the formulas (1) and (2) is repeated and the water vapor injection is stopped for several minutes. The reaction continues. The radical oxygen (O ²⁻ ) is combined with sodium ions (Na ⁺ ) to form an oxide (Na ₂ O).

2Na ⁺ + O ^2- → Na ₂ O (3)
Furthermore, this oxide (Na ₂ O) reacts with water vapor (H ₂ O) to become NaOH, and supplements consumed NaOH.
Na2O + H2O → 2NaOH (4)

Here, when air (N ₂ , O ₂ ) enters the reactor, oxygen (O ₂ ) here is not a radical, but simple iron, chromium and ordinary oxides (Fe ₂ O ₃ , Cr ₂ O ₃ ) and the reaction in the system is stopped in a short time. Therefore, in order to cause the main reaction, it is important not to put outside air into the reaction furnace. The reaction in the reaction space S is an OH bond breaking reaction, which is a significant endothermic reaction, and the molten salt is exothermic. It is.

  In order to bring the inside of the reaction furnace into a trace oxygen state, for example, as shown in FIG. When the pressure is contracted to become a negative pressure, the negative pressure is detected by the pressure gauge 101, and an inert gas in an amount corresponding to the negative pressure is injected into the reaction furnace. That is, the controller 102 receives data from the pressure gauge 101 and opens and closes the on-off valve 104 provided in the reservoir 100. The argon purge pipe 3c is provided with a check valve 103 biased in a closing direction by a spring 105, and when the reaction space S becomes negative pressure, the valve 103a of the check valve 103 is opened and a predetermined amount of inertness is generated. When the gas enters the reaction space and the negative pressure is eliminated, the check valve 103 may be closed.

  2) Since the reactant 12 has been found to occlude hydrogen under a positive pressure in the semi-molten state and around 500 ° C., the reactant 12 is in a semi-molten state (200-300 ° C.) or positive If the pressure is maintained at around 500 ° C. and hydrogen is injected into the storage container while applying pressure, it can be used as a hydrogen storage device.

3) In order to ensure the operation in an oxygen-free state, in addition to completely joining the pipes, as described above, when the gas (water vapor, H ₂ gas) in the reaction space contracts, In addition, there is a means for automatically injecting an inert gas or the like, but in addition to this, the inside of the reaction furnace may always be maintained at a positive pressure. Both of these means will be described in more detail.

  In FIG. 11, a steam chamber 201 to which water is supplied is formed in a rectangular tube-shaped reaction cell 200 by a partition wall 202, and a catalyst chamber 203 is formed between the partition wall 202 and the right wall of the reaction cell 200. Catalyst C (reactant) is accommodated in the catalyst chamber 203, and fins 204 made of SUS304 as a metal element supplier are immersed in the catalyst C. Then, a reaction space S is formed on the catalyst C, and this reaction space S is filled with water vapor and a group of fine particles shown in FIG. 2, and this group of fine particles is a planar shape provided on the lower surface of the reaction cell 200. The heat of the heater 205 scatters from the liquid level of the catalyst C. The steam chamber 201 is supplied with water from a water tank 206 through a water pipe 207. The water pipe 207 is provided with a first on-off valve 208, and the water tank 206 is maintained at a predetermined pressure by an air compressor 209. For example, the pressure is set to 2 to 3 atm, and is maintained at a pressure higher than the pressure in the reaction cell 200. A hydrogen pipe 210 extends from the upper right side wall of the reaction cell 200. The hydrogen pipe 210 is provided with a second on-off valve 211. The hydrogen pipe 210 further detects a pressure in the reaction space S. A pressure gauge 212 is provided.

  On the other hand, an inert gas supply pipe 213 is provided in the vicinity of the hydrogen pipe 210. The inert gas supply pipe 213 is provided with a third on-off valve 214, and the inert gas supply pipe 213 includes an argon gas. A gas cylinder 215 for storing an inert gas or the like is connected, and the first, second, and third on-off valves 208, 211, and 214 and the pressure gauge 212 are connected to a controller 216. Since hydrogen gas and inert gas flow in the hydrogen pipe 210, in order to extract only hydrogen gas, it is necessary to pass through a separator 217 provided with a separation membrane made of a palladium alloy or the like. The active gas is returned into the gas cylinder 215.

Water is supplied into the reaction cell 200, and the gas (water vapor, hydrogen gas) in the reaction space S contracts due to the reaction (violent endothermic reaction) between water vapor (120 to 150 ° C.) and fine particles. when a negative pressure (when the reaction of the catalyst C is active, the hydrogen is not negative pressure necessarily so immediately returns to normal pressure occurs successively is detected by a pressure gauge 212), a pressure gauge 212 Detects the negative pressure, whereby the controller 216 opens the third on-off valve 214 to supply the inert gas into the reaction cell to normal pressure therein, and when the normal pressure is reached, the third on-off valve 214 Close. Thus, the negative pressure in the system is released, so that external air is prevented from flowing into the reaction cell.

  Further, if the inside of the reaction cell 200 is always maintained at a positive pressure, it is possible to prevent external air from flowing into the reaction cell 200 and oxidize the catalyst. You may operate as shown in 12.

  That is, when the heating of the heater 205 is first maintained with the second on-off valve 211 closed, since the previously injected water vapor remains, hydrogen gas is slightly generated in the cell and the pressure rises. For example, when normal pressure has increased to about 0.5 atm from normal pressure, the first on-off valve 208 is opened and water is injected (1 cc in the experiment) to generate hydrogen in the reaction cell. From normal pressure to about 1.5 atm positive pressure When the second open valve 211 is opened, hydrogen is collected and the atmospheric pressure is reached.After that, the second open valve 211 is closed and raised to about 0.5 atm positive pressure, and the first open / close valve 208 is opened. Inject water. By repeating this operation, the inside of the reaction cell can always be set to a positive pressure, and inflow of air from the outside can be prevented.

  According to experiments, it has been found that when the operation as shown in FIG. 12 is performed, the amount of collected hydrogen is remarkably increased as compared with the case where water is injected while the second on-off valve 211 is always open. Next, experimental results are shown below.

Experimental procedure
a) With the 2nd on-off valve 211 opened, a total of 5 cc was injected at a rate of 1 cc every 10 minutes, and this continuous operation was repeated 3 times. The amount of hydrogen collected at that time is as follows.

1st time 1cc × 5 times Hydrogen collection 2.26 l
2nd 1cc x 5 times Hydrogen collection 2.9 l
3rd 1cc x 5 times Hydrogen collection 2.7 l
b) First and second on-off valve 211 is closed as described above. First, the second on-off valve 211 is closed. After 10 minutes, the positive pressure is about 0.5 to 0.7 atm. After 10 minutes, the first on-off valve 208 is opened to supply water. Then, the second on-off valve 211 is opened at a positive pressure of 1.5 atm to collect hydrogen, and the second on-off valve 211 is immediately closed and water is injected 10 minutes later. This operation was repeated 5 times (5cc) as a continuous operation, and this continuous operation was performed 3 times.

1st time 1cc × 5 times Hydrogen collection 5.16 l
2nd 1cc x 5 times Hydrogen collection 5.35 l
3rd 1cc x 5 times Hydrogen collection 4.05 l
As a result of the experiment, when water was injected under positive pressure, the amount of hydrogen collected was about twice that of normal pressure.

  From this, control of the reaction cell as shown in FIG. 13 can be considered.

  That is, a relief valve is attached instead of the second on-off valve 211 of FIG. 11, the relief valve is operated at, for example, 4 atmospheres or more, water is injected at a predetermined timing by opening the first on-off valve 208, When hydrogen is generated and the pressure in the reaction cell 200 reaches 4 atmospheres or more, the relief valve is opened and hydrogen is recovered. As the pressure in the cell increases, the reaction becomes active. Therefore, if water is injected while the pressure is constantly increased, the yield of hydrogen increases remarkably.

  In this way, if the pressure in the cell is adjusted by injecting water or water vapor, it is not necessary to adjust the pressure by injecting another inert gas, and it is not necessary to separate the inert gas and hydrogen. Furthermore, in order to expel the air in the cell when the cell is started up, if water vapor is injected, the water vapor decomposes and generates hydrogen when the temperature in the cell rises above a predetermined temperature. Hydrogen can be discharged when pressure is reached.

3. Specific Structure of Reaction Furnace In FIG. 14, a reaction furnace 300 is provided with a burner port 301, and a catalyst cell unit containing a rectangular parallelepiped hot air furnace 302, 302 for generating hot air and three cylindrical catalyst cells 303, 303. It consists of 304, 304 ... 304. Each unit 304 is a flat rectangular parallelepiped, and three sets of units 304 are stacked on the hot-air furnaces 302, 302 of the rectangular parallelepiped, and a chimney 305 extends to one end side of the uppermost cell unit 304. . The catalyst cells 303 are arranged in a staggered manner in the vertical direction as shown in FIG. 15, and the hot air from the lower hot air furnace 302 enters from the rear part of the cell unit above it, and the outer periphery of the catalyst cell and the inner cylinder 305 are connected. Then, it flows into the cell unit stacked on the upper side, enters the upper hot air furnace 302, merges with the hot air of the upper hot air furnace 302, passes through the cell unit 304 stacked on the upper side, and passes from the chimney 305 to the outside. To leak.

  As shown in FIG. 16, the catalyst cell 303 has a cylindrical body 310. The inner cylinder 305 extends into the cylindrical body 310, and punching fins 311 are fixed to the inner cylinder 305 at a predetermined interval. A catalyst 312 is accommodated in the body 310, and an upper part in the cylindrical body 310 forms a reaction space 313. One end of the cylindrical body 310 is provided with a protector 314 for maintaining airtightness, a hydrogen pipe 315 that discharges hydrogen through the protector 314 extends, and an end portion of the cylindrical body 310 where the hydrogen pipe 315 is provided. A water supply pipe 316 for supplying water is provided on the opposite side (rear side).

  The material of the cylindrical body 310 and the crystal structure of the inner surface are important, and the cylindrical body 310 needs to be a rolled SUS304 plate material or a seamless tube drawn while applying pressure by drawing, The crystal structure of the inner surface that the catalyst 312 contacts must be under pressure.

That is, as shown in FIG. 17, in the state of the inner surface when the space 320 was formed by drilling a columnar ingot made of stainless steel with a drill, the ability of the catalyst 312 quickly declined and water could not be decomposed. When the lid 322 was opened and the inside was confirmed, a hard insulating film was formed on the inner surface 321 of the cylinder.

  The present invention can be applied to power generation facilities using hydrogen, hydrogen stations, ships equipped with hydrogen engines, and the like.

DESCRIPTION OF SYMBOLS 1 ... Heating furnace 3 ... Reaction container 6 ... Water tank 12 ... Reactant 13 ... Metal element supply body 30 ... Fine particle group generation cylinder 100 ... Reservoir 101 ... Pressure gauge 103 ... Check valve

Claims (5)

Periodic table 10 containing at least the surface of an alkali molten salt comprising at least one alkali metal hydroxide containing sodium hydroxide, potassium hydroxide and barium hydroxide and containing nickel, palladium and platinum in the melt. At least one first metal of the group metals and at least one second metal among the transition metals of other groups including chromium, molybdenum, tungsten, cobalt, and iron, and the first metal and the second metal A metal is supplied from a metal element supplier, and a fine particle group including an alkali molten salt, the first and second metal element ions, and an electron is introduced into a reaction space in a trace oxygen state from the liquid surface of the melt. In the reaction, the fine particles are made to collide with water vapor to generate hydrogen gas from hydrogen in the water vapor. Forming a hydrogen generating method of this compound was as allowed to act as a catalyst.   2. The hydrogen generation method according to claim 1, wherein the alkali molten salt is a sodium hydroxide salt heated to 300 ° C. or more, and the first and second metals are supplied by SUS304. The alkali molten salt and the first and second metals are housed in a reaction furnace, and when the reaction space becomes negative pressure, an inert gas is supplied into the reaction space and air flows into the reaction space. The method for generating hydrogen according to claim 1, wherein the trace oxygen state is prevented and the trace oxygen state is maintained. The alkali molten salt and the first and second metals are accommodated in a reaction furnace, an on-off valve is provided on the hydrogen outlet side of the reaction furnace, and the on-off valve is closed to set the pressure in the reaction space to a predetermined positive pressure. Then, water is injected to generate hydrogen, and when the pressure rises, the on-off valve is opened to discharge hydrogen from the hydrogen outlet, and after this hydrogen discharge, the on-off valve is closed again to correct the reaction space. 2. The method for generating hydrogen according to claim 1, wherein the pressure is maintained to prevent a flow of air from the outside into the reaction space to maintain a trace oxygen state.   The alkali molten salt and the first and second metals are housed in a reaction furnace, a relief valve is provided on the hydrogen outlet side of the reaction furnace, and the relief valve releases pressure at a predetermined positive pressure, The hydrogen generation method according to claim 1, wherein water is injected at a predetermined timing and hydrogen is discharged by releasing the relief valve.

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