阅读说明：本技术 气体制造系统和气体制造方法 (Gas production system and gas production method ) 是由 明田川恭平 平敷勇 野崎智洋 坂田谦太 于 2019-04-23 设计创作，主要内容包括：在对反应器(2)内的催化剂照射等离子体、将所供给的原料气体(8)和氧化剂气体(10)改性以制造生成气体(14)的气体制造系统中,具备使原料气体供给单元(9)供给至反应器(2)的原料气体(8)和氧化气体供给单元(11)供给至反应器(2)的氧化气体(10)的比率变化的气体比率变化单元(101)和产生照射于催化剂的等离子体的等离子体发生单元,促进在催化剂表面有效率地形成反应性高的化学种的形成,从而提高生成气体(14)的收率和能量效率。(A gas production system for producing a product gas (14) by irradiating a catalyst in a reactor (2) with plasma and modifying a raw material gas (8) and an oxidizing gas (10) supplied thereto, wherein a gas ratio changing means (101) for changing the ratio of the raw material gas (8) supplied from a raw material gas supplying means (9) to the reactor (2) and the oxidizing gas (10) supplied from an oxidizing gas supplying means (11) to the reactor (2) and a plasma generating means for generating plasma to be irradiated to the catalyst are provided, and the formation of highly reactive chemical species on the surface of the catalyst is promoted, thereby improving the yield and energy efficiency of the product gas (14).)

1. A gas production system for producing a product gas by irradiating a catalyst in a reactor with plasma and modifying a raw material gas and an oxidizing gas supplied thereto, the gas production system comprising:

a raw material gas supply unit for supplying the raw material gas to the reactor;

an oxidant gas supply unit that supplies the oxidant gas to the reactor;

a gas ratio changing unit that changes a ratio of a supply amount of the raw material gas supplied to the reactor by the raw material gas supplying unit to a supply amount of the oxidizing gas supplied to the reactor by the oxidizing gas supplying unit; and

a plasma generation unit for generating plasma for irradiating the catalyst.

2. The gas production system according to claim 1, wherein the gas ratio changing unit sets a reference supply amount of the raw material gas, sets a time during which the raw material gas is supplied to the reactor at the reference supply amount and a time during which the raw material gas is supplied to the reactor at a supply amount smaller than the reference supply amount, and changes the supply amount of the raw material gas to the reactor based on the set times.

3. The gas production system according to claim 2, wherein the reference supply amount is set based on a stoichiometric ratio determined by a kind and a reaction of the raw material gas and the oxidant gas.

4. The gas production system according to claim 2 or claim 3, wherein the gas ratio changing means makes the supply amount of the raw material gas to the reactor zero during a time when the raw material gas is supplied to the reactor by a supply amount smaller than the reference supply amount.

5. The gas production system according to any one of claims 2 to 4, comprising:

a gas production device having the reactor, a first electrode and a second electrode between which plasma is generated, a catalyst layer disposed within the reactor and containing the catalyst; and

an external power source connected to the first electrode and the second electrode for generating a voltage,

wherein a plasma is generated within the reactor using a voltage generated by the external power supply and applied to the first electrode and the second electrode.

6. The gas production system according to claim 5, wherein the gas ratio changing unit sets a time for supplying the raw material gas to the reactor at the reference supply amount and a time for supplying the raw material gas to the reactor at a supply amount smaller than the reference supply amount, in accordance with a frequency of the voltage generated by the external power supply.

7. The gas production system according to claim 5 or claim 6, wherein the second electrode and the reactor are cylindrical, the second electrode is coated on an outer periphery of the reactor, and the first electrode is disposed on a central axis of the reactor.

8. The gas production system according to any one of claims 2 to 7, wherein the reactor is composed of a dielectric.

9. The gas production system according to any one of claims 2 to 8, wherein a plurality of the reactors are provided in parallel, and the raw material gas supply means is capable of switching supply of the raw material gas to any one of the plurality of reactors.

10. The gas production system according to claim 9, wherein the gas ratio changing means makes the supply of the source gas to at least another one of the reactors a supply amount smaller than the reference supply amount, in a period in which the supply of the source gas to one of the reactors is set to the reference supply amount.

11. The gas production system according to any one of claims 1 to 10, wherein the oxidant gas is 1 gas or a mixed gas of 2 or more gases selected from water vapor, carbon dioxide gas, and oxygen gas.

12. The gas production system according to any one of claims 1 to 11, wherein the raw material gas is a hydrocarbon-based gas, and the generated gas is a hydrogen-containing gas.

13. The gas production system according to claim 12, wherein the reactor is provided with a hydrogen sensor, and the gas ratio changing means changes the ratio of the supply amount of the hydrocarbon-based gas to the supply amount of the oxidizing gas based on a measurement value of the hydrogen sensor.

14. The gas production system according to claim 13, wherein the gas ratio changing means stops the supply of the hydrocarbon-based gas to the reactor for a predetermined time based on a measurement value of the hydrogen sensor.

15. A gas production method for producing a product gas by irradiating a catalyst in a reactor with plasma and modifying a raw material gas and an oxidizing gas supplied thereto, the gas production method comprising:

a raw material gas supply step of supplying the raw material gas to a catalyst layer containing the catalyst;

an oxidizing gas supplying step of supplying the oxidizing gas to the catalyst layer;

a plasma irradiation step of irradiating the catalyst layer with the plasma;

a reforming step of producing the generated gas from the raw material gas and the oxidizing gas; and

and a gas ratio changing step of changing a ratio of a supply amount of the raw material gas supplied to the catalyst layer in the raw material gas supply step to a supply amount of the oxidizing gas supplied to the catalyst layer in the oxidizing gas supply step to supply the raw material gas and the oxidizing gas.

16. The gas production method according to claim 15, wherein the raw material gas is supplied at a reference supply amount for a predetermined time in the raw material gas supply step, and the raw material gas is supplied at a supply amount smaller than the reference supply amount for a predetermined time in the gas ratio changing step.

17. The gas production method according to claim 16, wherein the time during which the raw material gas is supplied in the raw material gas supply step and the time during which the raw material gas is supplied in the gas ratio changing step are set in accordance with a frequency of a voltage at which plasma is generated in the plasma irradiation step.

18. The gas production method according to claim 16 or claim 17, wherein in the gas ratio changing step, supply of the raw material gas is stopped.

19. The gas production method according to any one of claims 16 to 18, wherein a plurality of reactors having the catalyst layer are used, and wherein the steps of the reactors are sequentially switched so that all of the other reactors are not in the raw material gas supply step while at least one of the plurality of reactors is in the raw material gas supply step.

Technical Field

The present application relates to a gas production system and a gas production method.

Background

Heretofore, as a method for producing a useful gas such as hydrogen gas or ammonia gas, a method using a catalyst has been known. In this production method, a mixed gas of 2 or more types including a raw material gas that is a raw material of a generated gas and an oxidizing gas that oxidizes the raw material gas is introduced as a gas to be processed into a catalytic reaction site, and the gas to be processed is reacted in a high-temperature environment to produce the generated gas.

When the gas to be treated is a mixed gas containing a hydrocarbon and water vapor or a molecular oxygen-containing gas, hydrogen can be produced as a generated gas (for example, patent document 1). Further, when the gas to be treated is a mixed gas containing a hydrogen gas and a carbon monoxide gas, a methane gas, an alcohol, or the like can be produced as the generated gas, and when the gas to be treated is a mixed gas containing a hydrocarbon-based gas and air, an ammonia gas can be produced as the generated gas (for example, patent document 2).

In the above-described gas production method, in order to increase the yield (amount of produced gas), the environment of the catalytic reaction site needs to be brought to a very high temperature, and the amount of heat energy to be input is large, so that the energy efficiency is low and the production cost of the produced gas is high. Therefore, it is desired to improve energy efficiency in producing the generated gas.

As one of methods for improving energy efficiency in producing a generated gas, a gas production method using plasma is known, and plasma is also used in patent documents 1 and 2.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-35852

Patent document 2: japanese patent laid-open publication No. 2002-

Disclosure of Invention

Problems to be solved by the invention

The reason why the yield of the generated gas and the energy efficiency can be improved by using the plasma is not only that the gas reaction substance in the gas to be processed can be excited by using the plasma, but also that chemical species (chemical species) such as ions and radicals having high reactivity are formed on the surface of the catalyst by using the plasma.

However, in a conventional gas production system using a catalytic reaction and plasma, a mixed gas of 2 or more kinds including a raw material gas that is a raw material of a generated gas and an oxidizing gas that oxidizes the raw material gas is continuously supplied as a target gas. Therefore, although there is a possibility that the gas reactant in the gas to be processed can be excited by the plasma, the effect of forming chemical species such as highly reactive ions or radicals on the catalyst surface is not necessarily sufficient, and the improvement of the yield and energy efficiency of the generated gas can be suppressed.

The present application discloses a technique for solving the above-described problems, and aims to provide a gas production system and a gas production method that can improve the yield and energy efficiency of a generated gas by efficiently promoting the formation of highly reactive chemical species on the surface of a catalyst.

Means for solving the problems

A gas production system disclosed in the present application is a gas production system that irradiates a catalyst in a reactor with plasma to modify a supplied raw material gas and an oxidant gas to produce a generated gas, and includes: a raw material gas supply unit for supplying the raw material gas to the reactor; an oxidant gas supply unit that supplies the oxidant gas to the reactor; a gas ratio changing unit that changes a ratio of a supply amount of the raw material gas supplied to the reactor by the raw material gas supplying unit to a supply amount of the oxidizing gas supplied to the reactor by the oxidizing gas supplying unit; and a plasma generating unit that generates plasma to be irradiated to the catalyst.

A gas production method disclosed in the present application is a gas production method for producing a product gas by irradiating a catalyst in a reactor with plasma and modifying a supplied raw material gas and an oxidant gas, and includes: a raw material gas supply step of supplying the raw material gas to a catalyst layer containing the catalyst; an oxidizing gas supplying step of supplying the oxidizing gas to the catalyst layer; a plasma irradiation step of irradiating the catalyst layer with the plasma; a reforming step of producing the generated gas from the raw material gas and the oxidizing gas; and a gas ratio changing step of changing a ratio of a supply amount of the raw material gas supplied to the catalyst layer in the raw material gas supply step to a supply amount of the oxidizing gas supplied to the catalyst layer in the oxidizing gas supply step to supply the raw material gas and the oxidizing gas.

Effects of the invention

According to the gas production system and the gas production method disclosed in the present application, it is possible to provide a gas production system and a gas production method that can efficiently promote the formation of highly reactive chemical species on the surface of a catalyst and can improve the yield and energy efficiency of the generated gas.

Drawings

Fig. 1A is a schematic diagram showing the configuration of a gas production system according to embodiment 1.

Fig. 1B is a schematic view showing an X-X section in fig. 1A.

Fig. 2 is a diagram illustrating a flow of operation of the gas production system according to embodiment 1.

Fig. 3 is a schematic diagram showing the configuration of the gas production system according to embodiment 2.

Fig. 4 is a schematic diagram showing the configuration of the gas production system according to embodiment 3.

Fig. 5 is a schematic diagram showing the configuration of the gas production system according to embodiment 4.

Detailed Description

Embodiments of a gas production system and a gas production method are described below with reference to the drawings. The embodiments described below are merely examples, and the present invention is not limited to these embodiments. In the drawings, the same reference numerals denote the same or corresponding parts.

Embodiment 1.

The following describes a gas production system according to embodiment 1. Fig. 1A is a schematic diagram showing the configuration of the gas production system according to embodiment 1. The gas production system is provided with: a gas production apparatus 1 having a reactor 2, a first electrode 3 and a second electrode 4 for generating plasma, and a catalyst layer 5; an external power supply 15 connected to the first electrode 3 and the second electrode 4 for supplying electric power; a raw material gas supply unit 9 for supplying a raw material gas 8 to the reactor 2; and an oxidizing gas supply means 11 for supplying the oxidizing gas 10 to the reactor 2. Fig. 1A shows a cross section of the gas production apparatus 1.

The gas production apparatus 1 includes a supply unit 6 and an outflow unit 7, and the supply unit 6 and the outflow unit 7 are connected to the reactor 2, respectively. The raw material gas 8 and the oxidizing gas 10 are supplied from the supply unit 6 to the reactor 2. The reactor 2 is formed with a flow path 12 through which the raw material gas 8 and the oxidizing gas 10 flow. The reactor 2 is provided with a first electrode 3 inside, the reactor 2 is provided with a second electrode 4 outside, the second electrode 4 is grounded, and the first electrode 3 is connected to the reactor 2 via a support 13 and fixed to the second electrode 4 in an insulated manner. Further, a catalyst layer 5 containing a catalyst that modifies the raw material gas 8 and the oxidizing gas 10 into the generated gas 14 is provided in a space between the first electrode 3 and the second electrode 4 in the flow path 12, and the generated gas 14 modified by the catalytic reaction in the catalyst layer 5 is sent out from the outflow portion 7 to the outside of the gas production apparatus 1.

The first electrode 3 and the second electrode 4 are connected to an external power supply 15, and the external power supply 15 generates a high voltage to generate plasma in a space between the first electrode 3 and the second electrode 4. The type of the plasma is not particularly limited, and from the viewpoint of energy efficiency, a non-equilibrium plasma is preferred in which the electron temperature is much higher than the gas temperature, and the catalytic reaction of the raw material gas 8 and the oxidizing gas 10 can be activated at a relatively low temperature.

The structure of the gas production apparatus 1 is not particularly limited as long as the gas production apparatus 1 includes the reactor 2, the first electrode 3, and the second electrode 4, and the raw material gas 8 and the oxidizing gas 10 are supplied to the catalyst layer 5 provided in the space between the first electrode 3 and the second electrode 4. However, in order to efficiently activate the catalytic reaction between the raw material gas 8 and the oxidizing gas 10, it is preferable that plasma be generated along the surface of the catalyst layer 5, and the gas production apparatus 1 is preferably cylindrical. FIG. 1B shows a schematic view of the X-X cross section in FIG. 1A. As shown in fig. 1B, the reactor 2 and the second electrode 4 are preferably cylindrical, the reactor 2 is covered with the second electrode 4, and the first electrode 3 is preferably rod-shaped and provided on the central axis of the reactor 2.

The material of the first electrode 3 and the second electrode 4 is not particularly limited as long as plasma can be generated by a high voltage of the external power supply 15, and a known material such as copper, iron, or tungsten can be used. From the viewpoint of corrosion of the electrode, it is more preferable to use an alloy such as stainless steel which is less susceptible to corrosion. The material of the reactor 2 is preferably a dielectric, and a known material such as ceramic or glass can be used.

The form of the catalyst constituting the catalyst layer 5 is not particularly limited, and a pellet-like (pellet-like) or granular catalyst may be used.

When a high voltage is generated by the external power supply 15 in a state where the raw material gas 8 and the oxidizing gas 10 are supplied from the supply unit 6 into the reactor 2, plasma can be generated in the catalyst layer 5 provided in the space between the first electrode 3 and the second electrode 4 in the reactor 2. The raw material gas 8 and the oxidizing gas 10 are reformed into the generated gas 14 in the catalyst layer 5.

The raw material gas 8 is supplied to the reactor 2 by a raw material gas supply unit 9, and the oxidizing gas 10 is supplied to the reactor 2 by an oxidizing gas supply unit 11. Further, as shown in fig. 1A, a gas ratio changing unit 101 having a function of controlling the supply amount of the raw material gas 8 and changing the supply amount is provided between the raw material gas supply unit 9 and the supply portion 6. The gas ratio changing means 101 defines 1 cycle in which the time ST for supplying the raw material gas 8 at the reference supply amount and the time CT for supplying the raw material gas 8 at the supply amount smaller than the reference supply amount are set and repeated, and the reference supply amount of the raw material gas 8. As a result, the ratio of the supply amount of the raw material gas 8 to the reactor 2 to the supply amount of the oxidizing gas 10 to the reactor 2 can be changed.

Further, the gas ratio changing means 101 may define 1 cycle in which the time ST for supplying the oxidizing gas 10 at the reference supply amount is set and the reference supply amount of the oxidizing gas 10 is set for the change of the ratio of the supply amount of the raw material gas 8 to the supply amount of the oxidizing gas 10, and the reference supply amount of the oxidizing gas 10_OAnd a time CT during which the oxidizing gas 10 is supplied in a larger amount than the reference supply amount_OAnd repeatedly executing. Further, the gas ratio changing unit 101 may control so that the supply amounts of both the raw material gas 8 and the oxidant gas 10 are changed. In fig. 1A, the gas ratio changing means 101 is provided between the raw material gas supply means 9 and the oxidizing gas supply means 11 and the supply section 6, but the raw material gas supply means 9 or the oxidizing gas supply means 11 may have the function of the gas ratio changing means 101 itself or both of them may have the function. In this case, the gas ratio changing means 101 may be incorporated in the raw material gas supplying means 9, the oxidizing gas supplying means 11, or both.

When the raw material gas 8 is supplied at the reference supply amount, the gas reactant in the raw material gas 8 and the oxidizing gas 10 can be efficiently excited by plasma. On the other hand, when the raw material gas 8 is supplied at a supply amount smaller than the reference supply amount, the oxidizing gas 10 is in a rich (abundant) state with respect to the raw material gas 8, and the oxidizing gas 10 is easily excited by the plasma, so that the formation of active oxygen species, which are highly reactive chemical species, is promoted on the catalyst surface of the catalyst layer 5. When the supply of the raw material gas 8 at the reference supply amount is resumed (for the next cycle) in a state where the active oxygen species, which is the highly reactive chemical species, is formed on the catalyst surface of the catalyst layer 5, the synergistic effect of the plasma and the catalytic reaction increases, and the yield and the energy efficiency of the generated gas can be improved.

The external power supply 15 that generates a high voltage is not particularly limited, and a known power supply such as an ac power supply or a pulse power supply can be used, and therefore, a sine wave, a pulse wave, a rectangular wave, or the like can be used as the signal waveform of the external power supply 15.

The magnitude of the high voltage generated by the external power supply 15 is not particularly limited as long as plasma can be generated in the space between the first electrode 3 and the second electrode 4, and if the magnitude of the high voltage is too low, plasma cannot be generated any more, whereas if the magnitude of the high voltage is too high, power consumption increases, and energy efficiency decreases. Therefore, it is preferably 0.5kV or more and 10kV or less, and more preferably 1kV or more and 5kV or less.

The ratio ST/CT of the time ST of supplying the raw material gas 8 at the reference supply amount to the time CT of supplying the raw material gas 8 at the reference supply amount may be set as appropriate in consideration of the amount of the raw material gas 8 to be prepared, the amount of the predetermined generated gas 14, and the like, and is not particularly limited. However, if the time ST for supplying the raw material gas 8 at the reference supply amount is too long, the chemical species on the catalyst surface of the catalyst layer 5 may decrease, and this may become insufficient. Further, if the time CT for supplying the raw material gas 8 at a supply amount smaller than the reference supply amount is long and the ST/CT is small, the amount of the generated gas 14 decreases, and the productivity of the generated gas 14 decreases. Therefore, the time ST for supplying the raw material gas 8 at the reference supply amount is preferably 5 minutes to 120 minutes, and more preferably 15 minutes to 60 minutes. The ratio ST/CT is preferably 0.5 or more and 10 or less, more preferably 1 or more and 3 or less.

Further, since the density of electrons in the generated plasma increases as the frequency of the high voltage of the external power supply 15 increases, the effect of promoting the formation of highly reactive chemical species on the catalyst surface of the catalyst layer 5 by the plasma when the raw material gas 8 is supplied at a supply amount smaller than the reference supply amount increases. However, if the frequency of the high voltage of the external power supply 15 is too high, the density of electrons becomes excessive, and power consumption necessary for plasma generation increases, so that energy efficiency may decrease. Therefore, the frequency of the high voltage of the external power supply 15 is preferably 50Hz to 13.56 MHz. In consideration of the influence of the frequency, the ratio ST/CT of the time ST during which the source gas 8 is supplied at the reference supply amount and the time ST during which the source gas 8 is supplied at the reference supply amount to the time CT during which the source gas 8 is supplied at the supply amount lower than the reference supply amount can be adjusted according to the frequency of the high voltage of the external power supply 15. For example, when the frequency of the high voltage of the external power supply 15 is low, the time CT for supplying the raw material gas 8 at a supply amount smaller than the reference supply amount is extended to reduce the ratio ST/CT in order to secure the effect of promoting the formation of the chemical species on the catalyst surface of the catalyst layer 5. When the frequency of the high voltage of the external power supply 15 is high, the time ST for supplying the source gas 8 at the reference supply amount can be increased in order to suppress a decrease in energy efficiency due to an increase in power consumption required for plasma generation.

The reference supply amount of the raw material gas 8 defined by the raw material gas supply means 9 may be appropriately set in consideration of the amount of the prepared raw material gas 8, the amount of the predetermined generated gas 14, and the like, and is not particularly limited. However, if the reaction efficiency of the raw material gas 8 and the oxidizing gas 10 is taken into consideration, it is preferable to determine the reference supply amount of the raw material gas 8 based on the kinds of the raw material gas 8 and the oxidizing gas 10 and the stoichiometric ratio determined by the reaction.

For example, in the case where the raw material gas 8 is hydrogen, the oxidizing gas 10 is carbon monoxide, and the generated gas 14 is methane, the reaction of the following formula (1) is a main reaction, and therefore, it is preferable to determine the reference supply amount so that the partial pressure of hydrogen as the raw material gas 8 becomes 3 times the partial pressure of carbon monoxide as the oxidizing gas 10. By doing so, it is possible to easily form the oxidizing gas 10 in a rich state with respect to the raw material gas 8 during the time when the raw material gas 8 is supplied at a supply amount lower than the reference supply amount.

3H₂+CO→CH₄+H₂O···(1)

The raw material gas supply means 9 and the oxidizing gas supply means 11 are not particularly limited in terms of means and structure as long as the raw material gas 8 and the oxidizing gas 10 can be supplied to the reactor 2. For example, when the raw material gas 8 and the oxidizing gas 10 are stored as high-pressure gases in the high-pressure gas tank, the raw material gas 8 and the oxidizing gas 10 can be supplied to the reactor 2 by utilizing the pressure difference between the high-pressure gas tank and the gas production apparatus 1. When a gas transport means such as a pump is provided, the raw material gas 8 and the oxidizing gas 10 can be supplied to the reactor 2 by the operation of the gas transport means.

The gas ratio changing means 101 is not particularly limited as long as it can control and change the supply amount of the raw material gas 8 to the reactor 2 or the supply amount ratio of the raw material gas 8 and the oxidizing gas 10. A known gas flow rate control device such as a flow rate control valve or a mass flow controller can be used. Further, instead of supplying the raw material gas 8 at a supply amount smaller than the reference supply amount, the supply of the raw material gas 8 may be completely stopped.

Fig. 2 is a diagram illustrating a flow of operation of the gas production system according to embodiment 1, and shows a method for producing a generated gas. The gas production method includes: a raw material gas supply step, an oxidizing gas supply step, a plasma irradiation step, a modification step, and a gas ratio changing step.

First, in step S1, it is determined whether or not the active oxygen species are sufficiently present on the catalyst surface of the catalyst layer 5 in the reactor 2, and if it is determined that the active oxygen species are sufficiently present (yes in step S1), the process proceeds to step S4. When the active oxygen species are not sufficiently present on the catalyst surface (no in step S1), in step S2, the oxidizing gas 10 is supplied to the catalyst layer 5 of the reactor 2 by the oxidizing gas supply means 11, and a high voltage is applied between the first electrode 3 and the second electrode 4 by the external power supply 15, thereby generating plasma in the catalyst layer 5. By the generation of this plasma, active oxygen species are formed on the catalyst surface of the catalyst layer 5. In step S1, whether or not the active oxygen species are present on the catalyst surface of the catalyst layer 5 in the reactor 2 can be determined by the elapsed time since the last operation of the gas production system, or the elapsed time or the processing procedure, such as the completion of the last operation of the gas production system after the active oxygen species have been formed on the catalyst surface. In addition, step S1 is an example of the oxidizing gas supplying step and the plasma irradiating step.

Step S3 is a step of determining whether or not the active oxygen species are sufficiently formed on the catalyst surface of the catalyst layer 5 by the processing of step S2, and for example, it may be determined whether or not the processing time t0 of step S2 has elapsed the predetermined time CT. The time CT is a time CT during which the raw material gas 8 is supplied at a supply amount smaller than the reference supply amount, but is not limited to this time. Step S2 is repeated until the processing time t0 reaches the time CT or until it is judged that the reactive oxygen species are sufficiently formed.

In the next step S4, the raw material gas 8 is supplied to the catalyst layer 5 in the reactor 2 at a predetermined reference supply rate by the raw material gas supply means 9, the oxidizing gas 10 is supplied by the oxidizing gas supply means 11, and a high voltage is applied between the first electrode 3 and the second electrode 4 by the external power supply 15 to generate plasma, thereby irradiating the catalyst layer 5 with the plasma. After step S3, plasma generation may be stopped or continued until step S4. Step S4 includes an example of a raw material gas supply step, an example of an oxidizing gas supply step, and an example of a plasma irradiation step. In step S4 including these 3 steps, the generated gas 14 is produced from the raw material gas 8 and the oxidizing gas 10 in the catalyst layer 5.

In step S5, it is determined whether or not the processing time t1 in step S4 has reached the time ST at which the raw material gas 8 is supplied at the reference supply amount in 1 cycle defined by the gas ratio changing unit 101 until the time ST is reached, and the process returns to step S4 to continue the processing in step S4. The processing of this continued step S4 is an example of the reforming step. If the processing time t1 in step S4 reaches the time ST (yes in step S5), the flow proceeds to the next step S6.

In step S6, if the generated gas 14 generated by reforming the raw material gas 8 and the oxidizing gas 10 reaches a predetermined generation amount (yes in step S6), the process proceeds to step S9. If the generated gas 14 does not reach the predetermined generated amount (no in step S6), the process proceeds to step S7.

In step S7, the raw material gas supply means 9 is used to reduce the supply amount of the raw material gas 8 to a value smaller than a predetermined reference supply amount, or to stop the supply of the raw material gas 8. Step S5 is an example of a gas ratio changing step in which the formation of active oxygen species is promoted on the catalyst surface of the catalyst layer 5 in the reactor 2.

In step S8, it is determined whether or not the processing time t2 in step S5 reaches the time CT at which the source gas 8 is supplied at a supply amount smaller than the reference supply amount in 1 cycle defined by the gas ratio changing means 101 until the time CT is reached, and the process returns to step S7 to continue the processing. If the processing time t2 in step S7 reaches the time CT (yes in step S8), the flow returns to step S4 to set the supply amount of the source gas 8 to the reference supply amount.

The process of the reforming step of step S4 and the process of the gas ratio changing step of step S7 are repeated for a period of time ST and time CT in 1 cycle defined by the gas ratio changing means 101, respectively, to produce the generated gas 14 up to a predetermined generated gas amount.

If the generated gas 14 is produced up to the predetermined generated gas amount, the application of the high voltage between the first electrode 3 and the second electrode 4 is stopped with the external power supply 15, and the plasma generation is stopped in step S9. The supply of the raw material gas 8 and the supply of the oxidizing gas 10 are stopped by the raw material gas supply means 9 and the oxidizing gas supply means 11, respectively. The above series of gas production processes is completed.

In the steps of the above-described gas production method, step S6 may be arranged after step S8, and it may be determined whether or not the predetermined generated gas amount is reached every 1 cycle defined by the gas ratio changing means 101. In this case, since the reaction is completed in a state where the active oxygen species are formed on the catalyst surface of the catalyst layer 5 in the reactor 2, the process time in step S2 can be skipped or the process time in step S2 can be shortened in the next operation of the gas production system.

In addition, although the example in which the supply amount of the source gas 8 in step S4 is changed in step S7 to perform the gas ratio changing step has been described, the supply amount of the oxidizing gas 10 may be used as the reference as described above. That is, it may be in step S4Supplying the oxidizing gas 10 for a reference supply amount for a time ST_OIn step S7, the oxidizing gas 10 is supplied for a supply time CT that is longer than the reference supply amount_OAnd (6) processing. Further, the gas ratio changing unit 101 may control so that the supply amounts of both the raw material gas 8 and the oxidizing gas 10 are changed.

As described above, according to embodiment 1, since the gas production system includes the gas ratio changing means 101 capable of changing the ratio of the raw material gas 8 and the oxidizing gas 10, the oxidizing gas 10 that oxidizes the raw material gas 8 can be made rich in the raw material gas 8, and the formation of active oxygen species, which are highly reactive chemical species, can be promoted on the catalyst surface of the catalyst layer 5. Therefore, the synergistic effect of the plasma and the catalytic reaction is increased, and the yield and energy efficiency of the generated gas 14 can be improved.

In embodiment 1, a description has been given of an example of a configuration in which the reactor 2 and the second electrode 4 have cylindrical cross sections, the reactor 2 is covered with the second electrode 4, and the first electrode 3 has a rod shape and is provided on the central axis of the reactor 2. However, the present invention is not limited to this example. For example, when the same function is obtained, the reactor 2 and the second electrode 4 may be configured to have a rectangular cross section.

Embodiment 2.

The following describes a gas production system according to embodiment 2. The basic configuration and operation of the gas production system according to embodiment 2 are the same as those of embodiment 1, and are different in that the gas production system includes a second gas production apparatus 16 having the same components as those of the gas production apparatus 1, a second external power supply 17 for supplying electric power to the second gas production apparatus 16, a raw material gas branching portion 19 for supplying the raw material gas 8 to the second gas production apparatus 16, second raw material gas supply means 20, an oxidizing agent gas branching portion 21 for supplying the oxidizing agent gas 10 to the second gas production apparatus 16, second oxidizing agent gas supply means 22, and second gas ratio changing means 102.

Fig. 3 is a schematic diagram showing the configuration of the gas production system according to embodiment 2.

In the drawings, the same constituent devices and members as those of the gas production system according to embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted unless otherwise particularly required. In fig. 3, the gas production system according to embodiment 2 includes a second gas production apparatus 16 having the same components as those of the gas production apparatus 1, in addition to the gas production apparatus 1. That is, the second gas production apparatus 16 has all the components corresponding to the reactor 2, the first electrode 3, the second electrode 4, the catalyst layer 5, the supply section 6, the outflow section 7, the flow channel 12, and the support 13, is the same mechanism as the gas production apparatus 1, and can obtain the second generated gas 18 by applying a high voltage by using the second external power supply 17 to generate plasma in the reactor 2. In the present embodiment, the same gas production is performed in the gas production apparatuses 1 and 16, and the produced gases 14 and 18 are considered to be equivalent.

Further, since the raw material gas branching portion 19, the second raw material gas supply means 20, the oxidizing gas branching portion 21, and the second oxidizing gas supply means 22 are provided, not only the raw material gas 8 and the oxidizing gas 10 can be supplied to the gas production apparatus 1, but also the second gas production apparatus 16. Further, the second gas ratio changing means 102 can be used to control and change the supply amount of the raw material gas 8 to the second gas production apparatus 16 independently of the gas ratio changing means 101.

By providing the gas production apparatus 1 and the second gas production apparatus 16, the productivity of the generated gases 14 and 18 can be improved. That is, in the gas production apparatus 1, when the raw material gas 8 is supplied at a supply amount lower than the reference supply amount to form a state in which the oxidizing gas 10 is rich in the raw material gas 8 and the formation of the chemical species is promoted on the catalyst surface of the catalyst layer 5 (gas ratio changing step), the raw material gas 8 can be supplied at the reference supply amount in the second gas production apparatus 16 to produce the second generated gas 18 (gas reforming step). On the other hand, when the raw material gas 8 is supplied at a lower supply rate than the reference supply rate in the second gas production apparatus 16 (gas ratio changing step), the raw material gas 8 can be supplied at the reference supply rate in the gas production apparatus 1 to produce the generated gas 14 (gas reforming step).

In the gas production apparatus 1, the amount of the generated gas 14 decreases during the gas ratio changing step, and the productivity of the generated gas 14 decreases. In the second gas production apparatus 16, the second product gas 18 can be produced in the gas reforming step. Next, in the gas production apparatus 1, the gas reforming step is performed with high catalytic activity to efficiently produce the produced gas 14, and in the meantime, in the second gas production apparatus 16, the gas ratio changing step is performed to promote formation of the chemical species for activating the catalyst surface, so that productivity of the produced gases 14 and 18 can be improved. That is, in order to maintain high catalytic activity and obtain the effect of increasing the synergistic effect of plasma and catalytic reaction, the period in which the productivity of the generated gas 14 is decreased in the gas production apparatus 1 can be a period in which the productivity of the second generated gas 18 is ensured in the second gas production apparatus 16 and the period in which the productivity of the generated gas 14 is ensured in the gas production apparatus 1 can be a period in which high catalytic activity of the second gas production apparatus 16 is maintained and the effect of increasing the synergistic effect of plasma and catalytic reaction is obtained. Therefore, as a gas production system, the yield and energy efficiency of the generated gas can be improved while improving the productivity of the generated gas.

Next, the supply time of the raw material gas 8 was examined.

The ratio ST2/CT2 of the time at which the raw material gas 8 is supplied to the gas production apparatus 1 at the reference supply amount to the ratio ST1/CT1 of the time ST1 at which the raw material gas 8 is supplied to the gas production apparatus 1 at the reference supply amount to the time CT1 at which the raw material gas 8 is supplied to the gas production apparatus 1 at a supply amount smaller than the reference supply amount, the time at which the raw material gas 8 is additionally supplied to the second gas production apparatus 16 at the reference supply amount, and the time ST2 at which the raw material gas 8 is supplied to the second gas production apparatus 16 at the reference supply amount to the time CT2 at which the raw material gas 8 is supplied to the second gas production apparatus 16 at a supply amount lower than the reference supply amount can take into account the amount of the raw material gas 8 prepared in the gas production apparatus 1 and the second gas production apparatus 16 or the predetermined amounts of the generated gases 14, 18 and the like, the content is not particularly limited. However, from the viewpoint of the productivity of the generated gas, it is preferable to set CT1 and ST2 to the same value and set ST1 and CT2 to the same value. Thereby, the generated gas (the generated gas 14 or the second generated gas 18) can be continuously produced. For example, when the amounts of production of the process gas 14 and the second process gas 18 are the same, ST1 ═ CT1 ═ ST2 ═ CT2 may be used.

The form and material of the components of the second gas production apparatus 16 are not necessarily exactly the same as those of the gas production apparatus 1 as long as they can obtain the same functions. In addition, not only the second gas production apparatus 16 but also a plurality of gas production apparatuses having the same components as those of the gas production apparatus 1 may be provided.

As described above, according to the gas production system according to embodiment 2, the same effects as those of embodiment 1 can be obtained.

Further, the gas production system according to embodiment 2 includes the second gas production apparatus 16 having a configuration equivalent to that of the gas production apparatus 1, and can supply the raw material gas 8 and the oxidizing gas 10 to the gas production apparatus 1 as well as to the second gas production apparatus 16; the second gas ratio changing means 102 is provided, so that the ratio of the raw material gas 8 to the oxidizing gas 10 can be changed by changing the supply amount of the raw material gas 8 to the second gas production apparatus 16. Thus, in the gas production apparatus 1, the second produced gas 18 is produced in the gas reforming step in the second gas production apparatus 16 during the gas ratio changing step, and the produced gas 14 is efficiently produced in the gas production apparatus 1 during the gas reforming step under high catalytic activity, and during this period, the gas ratio changing step is performed in the second gas production apparatus 16 to promote the formation of the chemical species for activating the catalyst surface, so that the productivity of the produced gases 14 and 18 can be improved. That is, while maintaining high catalytic activity and obtaining the effect of increasing the synergistic effect of the plasma and the catalytic reaction, productivity is ensured in the second gas production apparatus 16, and while ensuring productivity in the gas production apparatus 1, high catalytic activity of the second gas production apparatus 16 is maintained and the effect of increasing the synergistic effect of the plasma and the catalytic reaction is obtained. Therefore, as a gas production system, the yield and energy efficiency of the generated gas can be improved while improving the productivity of the generated gas.

In the above description, the gas production apparatus (i.e., the reactor having the catalyst layer) is illustrated as 2, and may be provided in plurality of 3 or more. In the case of 3 or more reactors, the steps of the reactors may be sequentially switched so that all of the other reactors are not in the raw material gas supply step during the time when at least 1 of the plurality of reactors is in the raw material gas supply step. For example, the first gas production apparatus may be sequentially switched from the gas ratio changing step to the raw gas supply step in the first gas production apparatus when the gas reforming step is completed, and from the gas ratio changing step to the raw gas supply step in the second gas production apparatus when the raw gas supply step and the gas reforming step are completed, and from the gas ratio changing step to the raw gas supply step in the third gas production apparatus when the raw gas supply step and the gas reforming step are completed. In addition, when there are 4, the process may be switched between the first group and the second group by dividing the process into 2 groups.

Embodiment 3.

The following describes a gas production system according to embodiment 3. The basic configuration and operation of the gas production system according to embodiment 3 are the same as those of embodiment 2, and an example is shown in which the hydrocarbon-based gas 23 as the raw material gas 8 is supplied to the gas production apparatus 1 or the second gas production apparatus 16, the hydrogen-containing gas 24 as the generated gas 14, and the second hydrogen-containing gas 25 as the second generated gas 18 are produced.

Fig. 4 is a schematic diagram showing the configuration of the gas production system according to embodiment 3. In the drawings, the same constituent devices and members as those of the gas production system according to embodiment 3 are denoted by the same reference numerals, and description thereof will be omitted unless otherwise particularly required.

In the gas production system according to embodiment 3, the hydrocarbon-based gas 23 and the oxidizing gas 10 are supplied from the supply unit 6 to the gas production apparatus 1. In a state where the hydrocarbon-based gas 23 and the oxidizing gas 10 are supplied from the supply unit 6 to the gas production apparatus 1, a high voltage is applied between the first and second electrodes 3 and 4 by the external power supply 15, and plasma is generated in the catalyst layer 5. The hydrocarbon-based gas 23 and the oxidizing gas 10 react with each other in the catalyst layer 5 to be reformed, thereby producing a hydrogen-containing gas 24. Similarly, in the second gas production apparatus 16, in a state where the hydrocarbon-based gas 23 and the oxidizing gas 10 are supplied to the second gas production apparatus 16, a high voltage is applied by the second external power supply 17 to generate plasma, and the second hydrogen-containing gas 25 is produced from the hydrocarbon-based gas 23 and the oxidizing gas 10.

By providing the gas production apparatus 1 and the second gas production apparatus 16, the productivity of the hydrogen-containing gases 24 and 25 can be improved. That is, in the gas production apparatus 1, when the hydrocarbon-based gas 23 is supplied at a supply amount lower than the reference supply amount so that the oxidizing gas 10 is in a rich state with respect to the source gas 8 and the formation of the chemical species is promoted on the catalyst surface of the catalyst layer 5 (gas ratio changing step), the hydrocarbon-based gas 23 is supplied at the reference supply amount in the second gas production apparatus 16, and the second hydrogen-containing gas 25 can be produced (gas reforming step). On the other hand, when the hydrocarbon-based gas 23 is supplied at a supply amount lower than the reference supply amount in the second gas production apparatus 16 (gas ratio changing step), the hydrocarbon-based gas 23 can be supplied at the reference supply amount in the gas production apparatus 1 to produce the hydrogen-containing gas 24 (gas reforming step).

In the gas production apparatus 1, the amount of the hydrogen-containing gas 24 produced decreases during the gas ratio changing step, and the productivity of the produced gas 14 decreases. In the second gas production apparatus 16, the second hydrogen-containing gas 25 can be produced in the gas reforming step. Next, the gas production apparatus 1 is used as a gas reforming step with high catalytic activity to efficiently produce the hydrogen-containing gas 24, and during this period, the second gas production apparatus 16 is used as a gas ratio changing step to promote the formation of chemical species for activating the catalyst surface, so that the productivity of the hydrogen-containing gases 24 and 25 can be improved. That is, in order to maintain high catalytic activity and obtain the effect of increasing the synergistic effect of plasma and catalytic reaction, while the productivity of the hydrogen-containing gas 24 is decreased in the gas production apparatus 1, the productivity of the second hydrogen-containing gas 25 is ensured in the second gas production apparatus 16, and while the productivity of the hydrogen-containing gas 24 is ensured in the gas production apparatus 1, the effect of increasing the synergistic effect of plasma and catalytic reaction can be obtained while maintaining high catalytic activity of the second gas production apparatus 16. Therefore, as a gas production system, the yield and energy efficiency of the generated gas can be improved while improving the productivity of the generated gas.

The hydrocarbon gas 23 is not particularly limited as long as it contains carbon atoms and hydrogen atoms and can be modified to a hydrogen-containing gas, and hydrocarbons such as methane, ethane, and propane, and alcohols such as methanol and ethanol can be used.

The oxidizing gas 10 is not particularly limited as long as it can react with the hydrocarbon-based gas 23 to produce a hydrogen-containing gas, and molecular oxygen-containing gas such as water vapor or carbon monoxide can be used. Among them, from the viewpoint of reactivity of the hydrocarbon-based gas 23 and the oxidizing gas 10, the oxidizing gas 10 is preferably 1 gas selected from water vapor, carbon dioxide gas, and oxygen gas, or a mixed gas of 2 or more gases.

The reference supply amount of the hydrocarbon-based gas 23 defined by the gas ratio changing means 101 can be appropriately set in consideration of the amount of the prepared hydrocarbon-based gas 23, the production amount of the predetermined hydrogen-containing gas 24, and the like, and is not particularly limited. However, in consideration of the reaction efficiency of the hydrocarbon-based gas 23 and the oxidizing gas 10, it is preferable to determine the reference supply amount of the hydrocarbon-based gas 23 based on the kinds of the hydrocarbon-based gas 23 and the oxidizing gas 10 and the stoichiometric ratio determined by the reaction.

For example, in the case where the hydrocarbon-based gas 23 is methane and the oxidizing gas 10 is carbon dioxide, the reaction of the following formula (2) is a main reaction, and therefore, it is preferable to determine the reference supply amount so that the partial pressure of the hydrocarbon-based gas 23 becomes 1 time the partial pressure of the oxidizing gas 10. By doing so, during the time when the hydrocarbon-based gas 23 is supplied at a supply amount lower than the reference supply amount, the oxidizing gas 10 can be easily made to be rich in the hydrocarbon-based gas 23.

CH₄+CO₂→2CO+2H₂···(2)

The reaction for producing the hydrogen-containing gas 24 in the catalyst layer 5 of the gas production apparatus 1 is composed of, for example, a reaction for decomposing the hydrocarbon-based gas 23 to produce hydrogen, in addition to a reaction for producing hydrogen by oxidizing the hydrocarbon-based gas 23 with the oxidant gas 10. At this time, carbon, which is a constituent of the hydrocarbon-based gas 23, may be deposited on the catalyst surface. The carbon deposited on the catalyst surface inhibits the reaction for producing the hydrogen-containing gas 24, and therefore the yield of hydrogen gas in the hydrogen-containing gas 24 may decrease. When the hydrocarbon-based gas 23 is methane and the oxidizing gas 10 is carbon dioxide, the reaction of decomposing the hydrocarbon-based gas 23 to generate hydrogen is represented by the following formula (3),

CH₄→2H₂+C···(3)

carbon (C) is precipitated on the catalyst surface.

However, if the supply amount of the hydrocarbon-based gas 23 to the gas production apparatus 1 is changed to change the ratio of the oxidizing gas 10 to the hydrocarbon-based gas 23, and plasma is generated in a state where the oxidizing gas 10 that oxidizes the hydrocarbon-based gas 23 is abundant in the hydrocarbon-based gas 23 (gas ratio changing step), the formation of active oxygen species, which are highly reactive chemical species, is promoted on the catalyst surface of the catalyst layer 5, and a reaction of forming an oxide on the catalyst surface occurs. By using the oxide thus formed, when the hydrocarbon-based gas 23 is supplied at the reference supply amount (gas reforming step), the deposition of carbon on the catalyst surface can be suppressed. Therefore, the yield of hydrogen gas in the hydrogen-containing gas 24 can be further improved, and the energy efficiency can be further improved.

In the present embodiment, the type of the catalyst is not particularly limited as long as the hydrocarbon-based gas 23 can be reformed into the hydrogen-containing gas, and a known catalyst can be used.

As described above, in the gas production system according to embodiment 3, the same effects as those in embodiment 2 can be obtained.

Further, in the gas production system according to embodiment 3, the hydrocarbon-based gas 23 is used as the raw material gas, the second hydrogen-containing gas 25 is produced in the gas reforming step in the second gas production device 16 during the gas ratio changing step in the gas production device 1, the hydrogen-containing gas 24 is efficiently produced during the gas reforming step with high catalytic activity in the gas production device 1, and the gas ratio changing step is performed in the second gas production device 16 during this period to promote the formation of the chemical species for activating the catalyst surface, so that the productivity of the hydrogen-containing gases 24 and 25 can be improved. That is, while maintaining high catalytic activity and obtaining the effect of increasing the synergistic effect of the plasma and the catalytic reaction, productivity is ensured in the second gas production apparatus 16, and while ensuring productivity in the gas production apparatus 1, high catalytic activity of the second gas production apparatus 16 can be maintained and the effect of increasing the synergistic effect of the plasma and the catalytic reaction is obtained. Therefore, as a gas production system, the yield and energy efficiency of the generated gas (hydrogen-containing gas) can be improved while improving the productivity of the generated gas. In the gas production apparatus 1 and the second gas production apparatus 16, during the gas ratio changing step, an oxide that functions to suppress the deposition of carbon due to the decomposition of the hydrocarbon-based gas 23 as the raw material gas can be formed on the catalyst surface simultaneously with the formation of the chemical species for activating the catalyst surface. Therefore, the productivity of the hydrogen-containing gas can be improved, the yield of hydrogen gas in the hydrogen-containing gas can be further improved, and the energy efficiency can be further improved.

Embodiment 4.

The following describes a gas production system according to embodiment 4. The basic configuration and operation of the gas production system according to embodiment 4 are the same as those of embodiment 3, but differ in that the gas production apparatus 1 is provided with the hydrogen sensor 26 and the second gas production apparatus 16 is provided with the second hydrogen sensor 27.

Fig. 5 is a schematic diagram showing the configuration of the gas production system according to embodiment 4. In the drawings, the same constituent devices and members as those of the gas production system according to embodiment 3 are denoted by the same reference numerals, and description thereof will be omitted unless otherwise particularly required.

In the gas production system according to embodiment 4, the hydrogen sensor 26 provided in the gas production apparatus 1 measures information, such as concentration, relating to the yield of hydrogen gas in the hydrogen-containing gas 24 produced in the gas production apparatus 1. The second hydrogen sensor 27 provided in the second gas production apparatus 16 measures information on the yield of hydrogen gas, for example, the concentration of hydrogen gas in the hydrogen-containing gas 25 produced in the second gas production apparatus 16. Then, the yield of hydrogen gas in the hydrogen-containing gases 24 and 25 is calculated from the measurement values of the hydrogen sensors 26 and 27.

When the hydrogen sensor 26 detects a decrease in the yield of hydrogen gas in the hydrogen-containing gas 24, the gas ratio changing means 101 corrects to increase the time CT1 for supplying the hydrocarbon-based gas 23 to the gas production apparatus 1 at a supply amount lower than the reference supply amount. Alternatively, when the hydrogen sensor 26 detects a decrease in the yield of the hydrogen gas in the hydrogen-containing gas 24, the supply of the hydrocarbon-based gas 23 to the gas production apparatus 1 is completely stopped for a certain time. After a certain time has elapsed, the supply of the hydrocarbon-based gas 23 to the gas production apparatus 1 is resumed. The time of the stop may be predetermined by an empirical value or the like. Further, depending on the state of recovering the yield of the hydrogen gas after the supply of the hydrocarbon-based gas 23, for example, when the recovery of the yield is delayed, the stop time can be appropriately changed such as being set long.

When the second hydrogen sensor 27 similarly detects a decrease in the yield of hydrogen gas in the hydrogen-containing gas 25, the second gas ratio changing means 102 corrects the time CT2 for increasing the supply amount of the hydrocarbon-based gas 23 to the second gas production apparatus 16 by a supply amount lower than the reference supply amount. Alternatively, when the second hydrogen sensor 27 detects a decrease in the yield of hydrogen gas in the hydrogen-containing gas 25, the supply of the hydrocarbon-based gas 23 to the second gas production apparatus 16 is completely stopped for a certain period of time. After a certain time has elapsed, the supply of the hydrocarbon-based gas 23 to the second gas production apparatus 16 is resumed.

The hydrogen sensor 26 and the second hydrogen sensor 27 are not particularly limited as long as they can measure information on the yield of hydrogen gas, and known measuring instruments, analyzing devices, and the like such as a quadrupole mass spectrometer and a gas chromatograph can be used. However, since it is preferable to continuously measure information on the yield of hydrogen on line, it is preferable to use a quadrupole mass spectrometer.

By operating the system as described above, the time for supplying the hydrocarbon-based gas 23 at a supply amount lower than the reference supply amount is appropriately ensured, and the effect of promoting the formation of the chemical species on the catalyst surface and the effect of forming the oxide on the catalyst surface to suppress the deposition of carbon on the catalyst surface can be stably maintained. Therefore, the productivity of the hydrogen-containing gas can be improved, and the effects of improving the yield and energy efficiency of the hydrogen gas in the hydrogen-containing gas can be stably obtained.

As described above, in the gas production system according to embodiment 4, the same effects as those in embodiment 3 can be obtained.

Further, in the gas production system according to embodiment 4, since the hydrogen sensor 26 capable of detecting a decrease in the yield of hydrogen gas in the hydrogen-containing gas 24 and the second hydrogen sensor 27 capable of detecting a decrease in the yield of hydrogen gas in the hydrogen-containing gas 25 are provided, the time CT1 for supplying the hydrocarbon-based gas 23 to the gas production apparatus 1 at a supply amount lower than the reference supply amount and the time CT2 for supplying the hydrocarbon-based gas 23 to the second gas production apparatus 16 at a supply amount lower than the reference supply amount can be increased in accordance with the decrease in the yield of hydrogen gas. Therefore, the time for supplying the hydrocarbon-based gas 23 at a supply amount lower than the reference supply amount is appropriately ensured, and the effect of promoting the formation of the chemical species on the catalyst surface and the effect of forming the oxide on the catalyst surface to suppress the deposition of carbon on the catalyst surface can be stably maintained. This stably improves the productivity of the hydrogen-containing gas and improves the yield and energy efficiency of the hydrogen gas in the hydrogen-containing gas.

In the above description, the amount of the oxidizing gas 10 supplied is kept constant, and the amount of the raw material gas 8 or the hydrocarbon-based gas 23 supplied is reduced, so that the oxidizing gas 10 is in a rich state with respect to the raw material gas 8 or the hydrocarbon-based gas 23. For example, the same effect can be obtained by increasing the supply amount of the oxidizing gas 10 for a certain period of time while keeping the supply amount of the raw material gas 8 or the hydrocarbon-based gas 23 constant, thereby producing a state in which the oxidizing gas 10 is rich in the raw material gas 8 or the hydrocarbon-based gas 23.

Various illustrative embodiments and examples are described in this disclosure, but the various features, modes and functions described in one or more embodiments are not limited to the application of the specific embodiments and can be applied to the embodiments alone or in various combinations.

Therefore, a myriad of modifications not illustrated yet can be expected within the technical scope disclosed in the present specification. For example, the present invention includes a case where at least one component is modified, added, or omitted, and a case where at least one component is extracted and combined with components of other embodiments.

Description of the reference numerals

1: gas production apparatus, 2: reactor, 3: first electrode, 4: second electrode, 5: catalyst layer, 6: supply unit, 7: outflow portion, 8: raw material gas, 9: raw material gas supply unit, 10: oxidant gas, 11: oxidant gas supply unit, 12: flow path, 13: support, 14: generated gas, 15: external power supply, 16: second gas production device, 17: second external power supply, 18: second generated gas, 19: raw material gas branching portion, 20: second source gas supply unit, 21: oxidant gas branching portion, 22: second oxidant gas supply unit, 23: hydrocarbon gas, 24: hydrogen-containing gas, 25: second hydrogen-containing gas, 26: hydrogen sensor, 27: second hydrogen sensor, 101: gas ratio changing unit, 102: a second gas ratio changing unit.