JP5343297B2 - Catalytic reactor, catalyst heating method, and fuel reforming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a catalytic reaction apparatus in which a catalyst can be heated without using an electric heater or a burner, and to provide a catalyst reaction method and a fuel reforming method. <P>SOLUTION: When a raw material to be reformed and a reforming gas are supplied into a reaction tube 22 and brought into contact with a catalyst layer 24 in a microwave reformation apparatus 10, a reformation reaction is caused to produce a hydrogen-containing reformed gas. The catalyst layer 24 is irradiated with a microwave emitted from a microwave heating unit 25 and heated to cause the reformation reaction. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a catalytic reaction apparatus, a catalyst heating method, or a fuel reforming method for performing a reaction such as a reforming reaction for reforming a hydrocarbon-based raw material into a hydrogen-containing gas.

  For example, a technique for obtaining hydrogen to be supplied to a fuel cell by reforming a hydrocarbon gas such as methanol is known. As reforming methods, steam reforming, partial oxidation reforming and the like are known. Since steam reforming is an endothermic reaction, it is necessary to heat the reactor with a burner or an electric heater from the outside. For this reason, there are problems such as a low reaction rate, a complicated and large reformer as a whole, and poor startability and load response. On the other hand, since partial oxidation reforming is an exothermic reaction, the reaction rate is high and the load response is relatively good. However, in partial oxidation reforming, since air is used for the oxidation reaction, there is a problem that the hydrogen concentration in the reformed gas obtained by reforming is reduced or ammonia is generated. In addition, it is difficult to adjust the air supply amount, and the catalyst partially becomes hot, and the catalyst is likely to be sintered.

  Furthermore, an autothermal method using steam reforming and partial oxidation reforming together has been considered (see, for example, Patent Document 1). In this technique, the life of the catalyst is improved by changing the supply amount of the oxidant gas and the supply amount of the fuel gas according to the output change of the reformer so as to suppress the fluctuation of the catalyst temperature. However, since this autothermal method includes a partial oxidation reaction, there are problems in that the hydrogen concentration in the reformed gas is reduced and ammonia is generated, as in the case of reforming by only partial oxidation. Further, for example, in automobile applications, further reduction in size and weight of the entire apparatus is desired.

Therefore, in order to reduce the size of the entire apparatus including the reformer and improve the startability, a technique for heating the steam generating unit installed in the lower stage of the CO converter with a microwave is considered (for example, Patent Document 2). In addition, a technique is known in which a hydrocarbon-based fuel is irradiated with microwaves to form fine droplets before being supplied to the reactor (see, for example, Patent Document 3).
JP 2001-80905 A JP 2001-210349 A JP 2004-2090 A

  However, in the configurations described in Patent Document 2 and Patent Document 3, a reformer or a reaction tank (a catalyst thereof) in which a reforming reaction for obtaining a hydrogen-rich gas is performed is heated by a burner or a heater, There is room for improvement in order to reduce the size and startability.

  An object of the present invention is to obtain a catalytic reactor, a fuel reforming method, and a fuel reforming method capable of heating a catalyst without relying on an electric heater or a burner in consideration of the above facts.

In order to achieve the above object, a catalytic reaction apparatus according to the first aspect of the present invention incorporates a catalyst layer constituted by mixing a microwave absorber with a catalyst , and the reforming raw material gas and reforming are contained in the catalyst layer. The reforming reaction is caused by irradiating the catalyst layer with the reactor for obtaining the reformed gas by bringing the reforming reaction into contact with the working gas and the microwave introduced into the reactor. And a microwave heating device that heats the catalyst layer so that the set temperature is maintained or maintained .

In the catalytic reaction apparatus according to claim 1, when the reforming raw material and the reforming gas are brought into contact with the catalyst layer which is supplied into the reactor and heated by the microwave irradiation, a reforming reaction occurs, and the reforming reaction occurs. A quality gas is produced. Here, since the catalyst layer can be directly and selectively heated by the microwave from the microwave heating apparatus, it is not necessary to heat the reactor in which the catalyst layer is incorporated, and a reforming reaction occurs. Input energy is reduced, and energy efficiency is high. In addition, since the heat capacity of the object to be heated is smaller than the configuration in which the entire reactor is heated, an improvement in load response and startability is expected.
Moreover, in this catalyst reaction apparatus, the microwave absorber is mixed with the catalyst to form the catalyst layer, so that the microwave is effectively absorbed into the catalyst layer and the catalyst layer is efficiently heated. This further improves the energy efficiency for obtaining the catalytic reaction.

Thus, in the catalytic reaction apparatus according to the first aspect, the catalyst can be heated without relying on an electric heater or a burner. For this reason, the whole apparatus can be reduced in size and weight.

In order to achieve the above object, the catalytic reaction apparatus according to the invention of claim 2 has a built-in catalyst layer formed by mixing a microwave absorber with a catalyst, and a mixed gas of hydrocarbon fuel and water is included. is supplied, the reactor for the gas mixture obtained hydrogen-containing gas to cause by the catalytic reforming reaction in the catalyst layer, the microwaves introduced into said reactor by irradiating the catalyst layer And a microwave heating apparatus that heats the catalyst layer so as to have a set temperature for causing or maintaining the reforming reaction .

3. The catalyst reaction apparatus according to claim 2, wherein a mixed gas in which a hydrocarbon raw material and water are mixed in a gas phase is supplied into the reactor and heated by microwave irradiation from a microwave heating apparatus. When contacted, a reforming reaction occurs and a hydrogen-containing gas is generated. Here, since the catalyst layer can be directly and selectively heated by using the microwave, it is not necessary to heat the reactor in which the catalyst layer is incorporated, and the input energy for causing the reforming reaction is eliminated. Is small and energy efficient. In particular, since microwaves have extremely high reactivity with water (water vapor) having a high dielectric loss factor, the efficiency of the reforming reaction is further improved. In addition, since the heat capacity of the object to be heated is smaller than the configuration in which the entire reactor is heated, an improvement in load response and startability is expected.
Moreover, in this catalyst reaction apparatus, the microwave absorber is mixed with the catalyst to form the catalyst layer, so that the microwave is effectively absorbed into the catalyst layer and the catalyst layer is efficiently heated. This further improves the energy efficiency for obtaining the catalytic reaction.

Thus, in the catalytic reaction apparatus according to the second aspect, the catalyst can be heated without relying on an electric heater or a burner. For this reason, the whole apparatus can be reduced in size and weight.

A catalytic reaction apparatus according to a third aspect of the present invention is the catalytic reaction apparatus according to the first or second aspect , wherein the microwave heating device uses the microwave in a range of 0.3 GHz to 30 GHz. Heat.

In the catalytic reaction apparatus according to the third aspect , since the microwave (wavelength of about 1 m to 0.01 m) in the range of 0.3 GHz to 30 GHz is used, the apparatus can be configured compactly.

Catalytic reactor according to the invention of claim 4, wherein, in the catalytic reactor according to any one of claims 1 to 3, wherein the catalyst layer, the microwave absorbing material in powder or fibrous dispersion Is retained .

The catalytic reaction apparatus according to claim 5 is the catalytic reaction apparatus according to any one of claims 1 to 4 , wherein the reactor can resonate in a single mode when a microwave is introduced. It is a rectangular parallelepiped cavity resonator.

In the catalytic reaction apparatus according to the fifth aspect , since the reactor is a single-mode cavity resonator, the energy of the microwave can be concentrated on the catalyst layer. For this reason, the heating time of the catalyst layer can be remarkably shortened, and the startability and load response can be improved. Further, since the cavity resonator is a rectangular parallelepiped, the resonance state can be easily adjusted.

A catalytic reaction apparatus according to a sixth aspect of the present invention is the catalytic reaction apparatus according to the fifth aspect , wherein the catalyst layer is disposed at a portion where the electric field strength is maximum in the cavity resonator in the resonance state. Yes.

In the catalytic reaction apparatus according to the sixth aspect , since the catalyst layer is arranged at the site where the energy is most concentrated in the cavity resonator, the energy of the microwave can be more concentrated on the catalyst layer.

Fuel reforming method according to the invention of claim 7, wherein in order to achieve the above object, over the catalyst heated by microwave irradiation to microwave absorbing material is mixed catalyst, a reforming raw material gas A reforming gas is obtained by a reforming reaction with the reforming gas.

In the fuel reforming method of the seventh aspect , the reforming reaction between the reforming raw material gas and the reforming gas is caused on the catalyst while heating the catalyst by irradiating the catalyst with microwaves. A reformed gas is generated by this reforming reaction. Here, since the catalyst can be directly and selectively heated by the microwave, the input energy for causing the reaction is reduced, and the energy efficiency is high. In addition, since the heat capacity of the object to be heated becomes smaller compared to a configuration in which the entire reactor containing the catalyst is heated, for example, an improvement in load response and startability is expected.

Thus, in the fuel reforming method according to the seventh aspect, the catalyst can be heated without depending on the electric heater or the burner.

In order to achieve the above object, a fuel reforming method according to an eighth aspect of the invention provides a hydrogen-containing gas by reforming the hydrocarbon fuel by reacting a hydrocarbon fuel and water on a catalyst. In the fuel reforming method, the reforming reaction is caused by irradiating the catalyst mixed with the microwave absorbing material with microwaves and heating the catalyst.

In the fuel reforming method according to the eighth aspect , the catalyst is irradiated with microwaves to heat the catalyst, and a reforming reaction between the hydrocarbon fuel and water is caused on the catalyst. By this reforming reaction, a hydrogen-containing gas is generated. Here, since the catalyst can be directly and selectively heated by the microwave, the input energy for causing the reaction is reduced, and the energy efficiency is high. In addition, since the heat capacity of the object to be heated becomes smaller compared to a configuration in which the entire reactor containing the catalyst is heated, for example, an improvement in load response and startability is expected.

Thus, in the fuel reforming method according to the eighth aspect, the catalyst can be heated without depending on the electric heater or the burner.

A fuel reforming method according to a ninth aspect of the present invention is the fuel reforming method according to the seventh or eighth aspect , wherein the catalyst is irradiated with a microwave in a range of 0.3 GHz to 30 GHz.

In the fuel reforming method according to claim 9 , since a microwave (wavelength of about 1 m to 0.01 m) in the range of 0.3 GHz to 30 GHz is used, the apparatus for executing the method can be configured compactly. become.

Fuel reforming method according to the invention of claim 10, wherein, in the fuel reforming method of any one of claims 7 to claim 9, in the catalyst, the microwave is the resonance state is introduced empty Microwaves are irradiated in the body resonator.

In the fuel reforming method of the tenth aspect , the catalyst is irradiated with the microwave in the cavity resonator brought into the resonance state by the introduction of the microwave. For this reason, microwave energy can be concentrated on the catalyst layer, and the heating time of the catalyst layer can be remarkably shortened. Thereby, startability and load responsiveness can be improved.

A fuel reforming method according to an eleventh aspect of the present invention is the fuel reforming method according to the tenth aspect , wherein the catalyst has a maximum electric field strength in a cavity resonator in which a microwave is introduced to be in a resonance state. The microwave is irradiated at a position where

In the fuel reforming method according to the eleventh aspect , since the catalyst layer is disposed at the site where the energy is most concentrated in the cavity resonator, the energy of the microwave can be more concentrated on the catalyst layer.

  As described above, the catalyst reaction apparatus, the catalyst heating method, and the fuel reforming method according to the present invention each have an excellent effect that the catalyst can be heated without relying on an electric heater or a burner.

  A microwave reformer 10 to which a catalytic reaction apparatus according to an embodiment of the present invention is applied and a catalyst heating method or a fuel reforming method is used will be described with reference to FIGS.

FIG. 1 is a block diagram showing a schematic overall configuration of the microwave reformer 10. As shown in this figure, this is an apparatus for reforming fuel to obtain a reformed gas. In this embodiment, a hydrocarbon-based fuel is used as a reforming raw material (fuel) to obtain a hydrogen-rich reformed gas. It is configured. As the hydrocarbon fuel, liquid fuel such as gasoline, kerosene, methanol, ethanol (including those derived from biomass), gas fuel such as natural gas (mainly methane), propane, butane, naphtha and the like can be used. In this embodiment, an example in which ethanol (C ₂ H ₅ OH) is used as a reforming raw material is shown.

  Specifically, the microwave reformer 10 includes a fuel supply unit 12 that stores and delivers a mixed solution (solution) of ethanol, which is a liquid fuel, and water, which is evaporated to form a reforming gas. The fuel supply unit 12 communicates with the evaporator 16 via the fuel flow path 14. The evaporator 16 vaporizes a mixed liquid of ethanol and water. The evaporator 16 is communicated with the reforming unit 20 via the fuel gas flow path 18. As described above, the reforming unit 20 is supplied with the mixed gas of ethanol gas (fuel gas) and steam (reforming gas) as the reforming raw material gas supplied from the fuel supply unit 12 and vaporized by the evaporator 16. It is the composition which is done.

  The reforming unit 20 includes a reaction tube 22 that forms a space for reforming ethanol in the supplied mixed gas to generate a reformed gas. The reaction tube 22 is formed in a tubular shape with a heat-resistant material that easily transmits microwaves described in detail later. In this embodiment, the reaction tube 22 is made of quartz glass. It is also possible to use dense alumina, mullite or the like as the material constituting the reaction tube 22. A catalyst layer 24 for accelerating the ethanol reforming reaction is provided in the reaction tube 22. The catalyst layer 24 is in the form of pellets or honeycombs.

  Here, the reforming reaction employed in this embodiment and reforming ethanol with a hydrogen-rich reformed gas includes reactions represented by the following formulas (1) and (2).

C ₂ H ₅ OH + H ₂ O → 4H ₂ + 2CO (1)
2CO + 2H ₂ O → 2H ₂ + 2CO ₂ (2)
Since the reactions of these formulas (1) and (2) proceed simultaneously, they can be collectively represented as formula (3).

C ₂ H ₅ OH + 3H ₂ O → 6H ₂ + 2CO ₂ (3)
Therefore, in this embodiment, a steam reforming reaction is mainly used as the reforming reaction. Examples of the catalyst for promoting such a steam reforming reaction include porous oxidation of one or a compound such as Al ₂ O ₃ , CeO ₂ , ZrO ₂ , TiO ₂ , SiO ₂ , MgO, ZnO, La ₂ O _3, etc. A material carrier carrying a noble metal such as Rh, Ru, Pt, Pd or the like is used. Although there is no restriction | limiting in particular about the amount of temples of noble metal, It is preferable to set it in the range of 0.1 to 10 weight% with respect to 100 weight% of supports. When the steam reforming reaction is performed at a relatively low temperature, a Cu-based or Ni-based catalyst can be used in place of the noble metal. In the catalyst layer 24 of this embodiment, a pellet-shaped catalyst in which fine powder of Rh is supported on a CeO ₂ carrier is employed.

  The catalyst layer 24 described above is held in the middle portion in the longitudinal direction in the reaction tube 22. One end of the reaction tube 22 in the longitudinal direction is a raw material supply port 22A to which the above-described mixed gas is supplied, and the other end in the longitudinal direction is a reformed gas discharge port 22B that discharges the reformed gas. A microwave absorbing material is added to the catalyst layer 24, and the outer periphery of the reaction tube 22 is covered with a heat insulating material 36, which will be described later.

  Further, since the steam reforming reaction is an endothermic reaction, the reforming unit 20 of the microwave reforming apparatus 10 includes a microwave heating apparatus 25 that applies heat to the catalyst layer 24 to cause or maintain the reforming reaction. I have. The microwave heating device 25 is configured to heat the catalyst layer 24 by irradiating the catalyst layer 24 with microwaves. This will be specifically described below.

  The microwave heating device 25 includes a microwave transmitter 26 that generates a microwave. As the microwave transmitter 26, a magnetron or a solid element transmitter is used. A microwave frequency in the range of 0.3 GHz to 30 GHz (wavelength 1 m to 0.01 m) is used, but a range of 1 GHz to 10 GHz is preferable. The microwave transmitter 26 is connected to the cavity resonator 30 as a reactor (reformer) via a coaxial cable 28. Thereby, in the microwave heating device 25, the microwave generated by the microwave transmitter 26 is introduced into the cavity resonator 30. A waveguide may be used instead of the coaxial cable 28.

  The cavity resonator 30 is formed in a substantially rectangular parallelepiped shape (box shape) using a material such as aluminum, copper, or brass, for example, and incorporates at least a portion where the catalyst layer 24 is provided in the reaction tube 22. When heat resistance is required for the cavity resonator 30, for example, the material may be stainless steel. The cavity resonator 30 has a coaxial cable 28 connected to one end 30A in the longitudinal direction so that microwaves are introduced, and a cross-sectional dimension (microwaves) with respect to the microwave frequency so as to generate single-mode resonance. (Longitudinal dimension × width dimension), which is the traveling direction of the above, is determined.

Here, the resonance mode (electromagnetic field mode) of the single-mode cavity resonator 30 is the TE _10n mode. As shown in FIG. 3, the first subscript “1” in the TE mode indicates the number of electric field components (standing waves, antinodes of vibration) in the width direction of the cavity resonator 30. The letter “0” is the number of electric field components facing the microwave traveling direction (see arrow A in FIG. 3), and the third subscript “n” is the microwave traveling direction (longitudinal direction of the cavity 30). Indicates the number of electric field components along. In order to increase the electric field strength, “n” is preferably 3 or less. In this embodiment, n = 3.

  For example, the cavity resonator 30 has a cross-sectional dimension of approximately 250 mm × 125 mm when the microwave frequency is 1 GHz, and a cross-sectional dimension of approximately 20 mm × 10 mm when the microwave frequency is 10 GHz. The microwave frequency and the cross-sectional dimension of the cavity resonator 30 are appropriately selected depending on the purpose of reforming. In the present embodiment in which the steam reforming of ethanol is performed as described above, a microwave of 2.45 GHz is generated as an example. A magnetron is used as the microwave transmitter 26, and the cavity resonator 30 is formed of aluminum in a rectangular parallelepiped shape having a cross-sectional dimension of approximately 110 mm × 55 mm.

  As shown in FIG. 2, the microwave heating device 25 has a microwave reflectance as an adjusting means for bringing the cavity resonator 30 into a resonance state in a state where the mixed gas is supplied to the reaction tube 22. The iris 32 (variable coupling window) 32 that can change the aperture area into which the microwave is incident so as to approach 0, and the longitudinal dimension of the cavity resonator 30 to correct the deviation of the frequency of the cavity resonator 30 from the microwave frequency. And a plunger 34 capable of changing. The opening area of the iris 32, the longitudinal dimension of the cavity resonator 30 (position of the plunger 34), the type of reforming raw material (ethanol in this embodiment) supplied to the reaction tube 22, the flow rate, the catalyst layer 24 (catalyst ) Is appropriately adjusted according to the type and amount.

  Here, the resonance state of the cavity resonator 30 is a state in which the frequency of the cavity resonator 30 matches the microwave frequency, and in this state, the reflectance (reflected power) is almost zero. Since the cross-sectional dimension of the cavity resonator 30 described above is set so as to obtain resonance when the cavity resonator 30 is empty, the catalyst layer 24 in the reaction tube 22 is heated by microwave irradiation. In this embodiment, the structure which can be adjusted to the resonance state according to the heating object with the iris 32 and the plunger 34 is employ | adopted. When the reforming raw material and the catalyst (type and amount) are determined as in the present embodiment, considering that the resonance adjustment is not sensitive to the flow rate of the mixed gas, It is also possible to adopt a configuration in which the cavity resonator 30 is resonated in accordance with the type of catalyst (preliminarily adjusted dimensions), and the iris 32 and the plunger 34 are omitted.

As shown in FIG. 1, the catalyst layer 24 in the reaction tube 22 is disposed at a site where the electric field strength E is maximum in the cavity resonator 30 in the resonance state (an antinode position of the standing wave). . That is, as described above, the catalyst layer 24 is disposed at each center portion in the longitudinal direction and the width direction of the cavity resonator 30 of the TE ₁₀₃ mode. As described above, in the microwave reforming apparatus 10, the energy-concentrated microwave heating apparatus 25, that is, the reforming unit 20, for concentrating and irradiating the catalyst layer 24 with microwave energy and heating the catalyst layer 24 is realized. Yes.

In addition, the reforming unit 20 adds a microwave absorbing material to the catalyst layer 24 in order to absorb microwave energy into the catalyst layer 24. As the microwave absorbing material, a powder or fibrous material having a large dielectric loss factor, for example, a powder of MnO ₂ , Co ₂ O ₃ , Fe ₃ O ₄ , or a WC, SiC, or SiC-based composite oxide A thing powder or a fibrous thing can be used. Examples of the SiC-based composite oxide include Si—C—O, Si—C—Zr—O, and Si—C—Ti—O. In this embodiment, a mixture of SiC powder and Si—C—Zr—O powder is dispersed (held) substantially uniformly in the catalyst layer 24 as the microwave absorber. The amount of the microwave absorbing material added was in the range of 5 to 10% by weight with respect to 100% by weight of the catalyst.

  Further, the reforming unit 20 and the microwave heating device 25 include a heat insulating material 36 that covers the outer periphery of the reaction tube 22, and prevents heat from being released from the catalyst layer 24 heated by the microwave irradiation. It is like that. The heat insulating material 36 is made of a material that easily transmits microwaves, such as alumina fiber. Note that the influence of the heat insulating material 36 is also taken into consideration in the adjustment of the resonance of the cavity resonator 30 described above.

  As shown in FIG. 1, the microwave reformer 10 includes a controller 38. The control device 38 operates the fuel supply unit 12 or controls the supply amount of the liquid mixture, and controls the reforming unit 20 according to the hydrogen (reformed gas) request amount from the load side. Yes. That is, the control device 38 controls the output of the microwave power generated by the microwave transmitter 26, the opening area of the iris 32, the position of the plunger 34, and the like according to the hydrogen demand from the load side. Yes. Needless to say, these controls are not necessary in the configuration without the iris 32 and the plunger 34.

  The microwave reformer 10 described above includes, for example, a hydrogen supply device for supplying a hydrogen-rich gas to a fuel cell, particularly a fuel cell for supplying electric power to a large load fluctuation electric motor as a driving source of an automobile. As applied.

  When reforming hydrocarbon fuel (steam reforming as described later), the steam / carbon ratio (hereinafter referred to as S / C ratio), which is the mixing ratio of steam and fuel gas, is 0.5 to A range of 5 is preferable, and a range of 1 to 3 is particularly preferable. When the S / C ratio is less than 0.5, carbon is deposited on the catalyst layer 24 (see formula (1)), and when the S / C ratio exceeds 5, excess water vapor is required. A large amount of energy is consumed in the evaporator 16, the reforming unit 20, and the like, which is not preferable. As can be seen from Equation (3), in this configuration using ethanol as the reforming material, the S / C ratio is 1.5 or more, and the maximum hydrogen gas (with respect to 1 mol of ethanol) relative to the amount of hydrogen atoms of the reforming material. 6 mol of hydrogen gas) can be obtained. In this embodiment, the mixing ratio of ethanol and water in the fuel supply unit 12 is adjusted so that the S / C ratio of the mixed gas supplied to the reforming unit 20 (reaction tube 22) is 1.5. Yes.

  Next, the operation of the first embodiment will be described.

  In the microwave reformer 10 having the above-described configuration, the mixed liquid of water and ethanol supplied to the evaporator 16 from the fuel supply unit 12 is evaporated by the evaporator 16 and modified as a mixed gas of water vapor and ethanol. It is supplied into the reaction tube 22 of the mass part 20. This mixed gas comes into contact with the catalyst layer 24 heated by the microwave irradiation. Then, the ethanol is steam reformed, and a hydrogen-rich reformed gas is generated. This reformed gas is supplied to a hydrogen consuming device such as a fuel cell.

  At this time, in the microwave heating device 25, the microwave oscillator 26 oscillates a microwave having a predetermined frequency, and the microwave is introduced into the cavity resonator 30, so that the cavity resonator 30 is in a resonance state. It has become. Then, the energy of the microwave is intensively applied to the catalyst layer 24 disposed in the portion where the electric field strength in the cavity resonator 30 in the resonance state is maximum, and the catalyst layer 24 is directly and selectively heated, This heat causes the above-described steam reforming of ethanol, which is an endothermic reaction.

  Here, since the microwave reformer 10 uses microwaves for heating the catalyst layer 24, the catalyst layer 24 can be directly and selectively heated from the inside as described above. For this reason, in this microwave reforming apparatus 10, the space (gas) before and behind the reaction tube 22 and the catalyst layer is heated, for example, as configured to transfer heat to the catalyst layer 24 via the reaction tube 22. Energy is not consumed. That is, by using microwaves, the heat capacity of the target to be heated by external energy is reduced, and the reformed gas containing high-concentration hydrogen gas is reduced while keeping the energy for maintaining steam reforming, which is an endothermic reaction, low. Can be obtained. Therefore, the microwave reformer 10 can generate hydrogen gas from a hydrocarbon raw material with high efficiency. As a result, the microwave reformer 10 can be reduced in size and weight as a whole.

  Moreover, in the microwave reformer 10, since the microwave absorber is added to the catalyst layer 24, the microwave is effectively absorbed by the catalyst layer, and the catalyst layer 24 is efficiently heated. This further improves the energy efficiency for maintaining the steam reforming catalytic reaction.

  Furthermore, since the microwave reformer 10 has the cavity resonator 30 as a reactor, the microwave energy can be concentrated on the catalyst layer 24. In particular, since the catalyst layer 24 is disposed at a portion where the electric field strength is maximum in the cavity resonator 30, the microwave energy can be more concentrated on the catalyst layer. Thus, in the microwave reformer 10, the heating time of the catalyst layer 24 can be remarkably shortened, and the startability and load response of the reforming unit 20 (reforming process) can be improved. Moreover, since the cavity resonator 30 is formed in a rectangular parallelepiped, the resonance state can be easily adjusted as compared with, for example, a cylindrical type.

  Hereinafter, the result of the reforming experiment by the microwave reforming apparatus 10 that obtains the above effects will be described.

  FIG. 4 shows a heating profile when the catalyst layer 24 for steam reforming is heated by microwave irradiation. This figure shows the time change of the temperature of the catalyst layer 24 when heating was performed at a set (target) temperature of 800 ° C., and this temperature was measured by a radiation thermometer. In this experiment, the microwave output of the microwave transmitter 26 was controlled so that the temperature of the catalyst layer 24 became the set temperature. From FIG. 4, it can be seen that in the microwave reformer 10, the temperature of the catalyst layer 24 is set to the set temperature (temperature control) in a very short time.

  Specifically, in the experiment that obtained the results shown in FIG. 4, immediately after the start of microwave irradiation, the temperature of the catalyst layer 24 increased at about 100 ° C./second, and about 7 seconds after the start of microwave irradiation. As a result, the temperature of the catalyst layer reached 600 ° C., and the temperature of the catalyst layer 24 stabilized at about 800 ° C. in about 25 seconds from the start of microwave irradiation. Further, the microwave output when the temperature of the catalyst layer 24 is 600 ° C. is about 65 W, and the microwave output when the temperature is 800 ° C. is about 94 W. It was also confirmed that the power consumption was small. Furthermore, although illustration is omitted, a heating profile similar to that of FIG. 4 could be obtained when the position control of the plunger 34 was performed instead of the microwave output control. In addition, it has been confirmed that heating as set can be performed in a short time even at a set temperature other than 800 ° C.

  As described above, in the microwave reformer 10, the temperature of the catalyst layer 24 can be accurately set to the target temperature in a very short time, so that the startability and load responsiveness of the reforming unit 20 are significantly improved. Can do.

  FIG. 5 shows the relationship between the temperature of the catalyst layer 24 and the ethanol reforming rate. The reforming rate (conversion rate) of ethanol is the rate at which the reforming material ethanol is converted, and is 100 when ethanol is not present in the reformed gas (when the formula (1) is completely performed). %. This experiment was performed under the condition that 3 moles of water was mixed with 1 mole of ethanol so that the S / C ratio was 1.5. From FIG. 5, the reforming rate of ethanol is almost 100% from 400 ° C. at which the temperature of the catalyst layer 24 is relatively low, and this reforming rate is maintained at each temperature from 800 ° C. which is relatively high. I understand that. Further, the hydrogen gas concentration in the reformed gas is a high concentration of about 45% when the temperature of the catalyst layer 24 is 400 ° C. and about 66% when the temperature of the catalyst layer 24 is 800 ° C. It was.

  Furthermore, in the microwave reformer 10, when the temperature of the catalyst layer 24 is 800 ° C., the hydrogen generation amount is as high as about 77% with respect to the theoretical value of the hydrogen generation amount (when the formula (3) is completely performed). A quantity was obtained. This is approximately 154% in terms of hydrogen selectivity. Here, the hydrogen selectivity indicates the ratio of hydrogen gas obtained by reforming 1 mol of ethanol (the number of hydrogen atoms H = 6), and the formula (3) can be completely performed as described above (hydrogen gas is In the case of S / C = 1.5, the theoretical value is 200%. A hydrogen selectivity of 154% in the present embodiment indicates that approximately 4.6 mol (theoretical value: 6 mol) of hydrogen gas is obtained with respect to 1 mol of ethanol.

As a comparative example, G. A Delagna, J. et al. R. Salge, L.M. D. Schmidt, X.M. E. An example of the modification of ethanol described in Verykios "Renewable Hydrogen from Ethanol by Automatic Thermal Reforming", SIENCE VOL303 13 February 2004 is shown. In this comparative example, an external heater is used to maintain the reforming reaction, and steam reforming and partial oxidation reforming are performed using the same Rh—CeO ₂ -based catalyst as in the present embodiment as the catalyst. The combined autothermal method is used. Further, in this comparative example, after the reforming, a shift reaction (CO + H ₂ O → CO 2 + H ₂ ) is performed using a Pt—CeO ₂ -based catalyst to reduce CO and increase the amount of hydrogen generated. In this comparative example, in the reforming at 700 ° C. or higher, an ethanol reforming rate close to 100% is obtained as in the present embodiment, but the ethanol reforming rate at 400 ° C. is 50% or less, and the low temperature The reforming rate in the region is low (see FIG. 3B in the above paper). On the other hand, in the present embodiment, an ethanol reforming rate close to 100% is realized at 400 ° C. as shown in FIG. The hydrogen selectivity in the comparative example is about 110% at maximum corresponding to the fact that 3.3 mol of hydrogen is obtained for 1 mol of ethanol in the case of only the reforming reaction by the autothermal method (see FIG. 3A, the theoretical value is 167%). Further, the hydrogen selectivity when the shift reaction is used in combination is about 130% at maximum (3.9 mol of hydrogen per 1 mol of ethanol). The hydrogen selectivity of 154% by steam reforming of this embodiment indicates that the hydrogen production rate has improved by about 40% compared with the reforming reaction by autothermal of the comparative example.

  As described above, by using microwaves for heating the catalyst layer 24 as in this embodiment, the energy efficiency is high as described above, and the catalyst temperature can be set to the set temperature in a short time (control response of the catalyst temperature). In addition to the fact that the reforming rate of ethanol is almost 100% at a low temperature of 400 ° C., it can be seen that the reforming temperature can be lowered, and hydrogen is generated compared to external heating by a heater. It has been found that the rate can be greatly improved.

  As described above, as a mechanism that the reforming rate at a low temperature is high or the hydrogen production rate is high, the catalyst layer 24 has a macroscopically low temperature, but has a microscopically localized high temperature portion at the particle interface or the like. It is considered that the catalyst is activated by being produced (the reforming reaction is promoted microscopically). Further, it is conceivable that the catalyst layer 24 is heated from the inside to a substantially uniform temperature by the microwave so that a uniform and highly efficient reforming reaction occurs in each part of the catalyst layer 24 where the temperature distribution does not occur. . Since no temperature distribution is generated in the catalyst layer 24, sintering of the catalyst layer 24 is also prevented.

  Further, in the microwave reforming apparatus 10, since the temperature control response of the catalyst layer 24 is high by the energy-concentrated microwave irradiation (output control) as described above, the steam reforming is performed without using an oxidation reaction accompanied by heat generation. Only the reaction can be employed. Thereby, the hydrogen concentration in the reformed gas can be increased, and the generation of ammonia due to the mixing of nitrogen (air) is also prevented.

  As described above, in the microwave reforming apparatus 10 according to the present embodiment, the catalyst heating method and the fuel reforming method applied to the microwave reforming apparatus 10 respectively, the catalyst layer 24 can be used without relying on an electric heater or a burner. It can be selectively heated. Thereby, it is possible to obtain a reforming device and a reforming process having high energy efficiency and good temperature controllability. In particular, the microwave irradiation activates the micro catalyst surface at the catalyst particle interface, thereby promoting the reforming reaction, enabling hydrogen gas to be generated at a higher concentration and higher efficiency than the external heating method. became.

In the above-described embodiment, an example in which only the steam reforming reaction is performed in the reforming unit 20 of the microwave reforming apparatus 10 is described. However, the present invention is not limited to this example. oxide may be to perform the reforming and shift reactions by autothermal, also for example, may be to perform the reforming reaction for obtaining such reformate by adding hydrogen to the fuel gas in the reforming unit 20.

  Moreover, although the example which applied the microwave reforming apparatus 10 to the continuous reforming process was shown in the said embodiment, this invention is not limited to this, For example, for the heating of the catalyst which performs reaction by batch process Microwaves may be used.

1 is a block diagram showing a schematic overall configuration of a microwave reformer according to an embodiment of the present invention. It is a schematic diagram which shows the cavity resonator which comprises the microwave reforming apparatus which concerns on embodiment of this invention. It is a perspective view showing typically a cavity resonator which constitutes a microwave reforming device concerning an embodiment of the present invention. It is a diagram which shows the heating profile of the catalyst layer by the microwave reformer which concerns on embodiment of this invention. It is a diagram which shows the relationship between the catalyst heating temperature and the reforming rate by the microwave reforming apparatus which concerns on embodiment of this invention.

Explanation of symbols

10 Microwave reformer (catalytic reactor)
24 Catalyst layer (catalyst, microwave absorber)
25 Microwave heating device 30 Cavity resonator (reactor)

Claims (11)

A catalyst layer configured by mixing a microwave absorber with a catalyst is incorporated , and a reforming gas is generated by bringing the reforming raw material gas and the reforming gas into contact with the catalyst layer. A reactor for,
Irradiating the catalyst layer with microwaves introduced into the reactor, thereby heating the catalyst layer to a set temperature that causes or maintains the reforming reaction ; and
A catalytic reaction apparatus comprising: Catalyst is mixed microwave absorbing material incorporates a catalyst layer formed, a gas mixture of hydrocarbon fuel and water is supplied, causing a reforming reaction of the mixed gas is brought into contact with the catalyst layer A reactor for obtaining a hydrogen-containing gas,
Irradiating the catalyst layer with microwaves introduced into the reactor, thereby heating the catalyst layer to a set temperature that causes or maintains the reforming reaction ; and
A catalytic reaction apparatus comprising:   The catalytic reaction apparatus according to claim 1 or 2, wherein the microwave heating apparatus heats the catalyst layer using microwaves in a range of 0.3 GHz to 30 GHz. Wherein the catalyst layer, the catalytic reactor according to any one of claims 1 to 3, wherein the microwave absorbing material in powder or fibrous are dispersed and held.   The catalytic reactor according to any one of claims 1 to 4, wherein the reactor is a rectangular parallelepiped cavity resonator capable of resonating in a single mode when microwaves are introduced.   The catalytic reaction apparatus according to claim 5, wherein the catalyst layer is disposed at a portion where the electric field strength is maximum in the cavity resonator in the resonance state. Over the catalyst heated by microwave irradiation to microwave absorbing material is mixed catalyst, the fuel reforming method of obtaining reformed gas and a gas for reforming raw material gas and the reforming by the reforming reaction. A fuel reforming method in which a hydrocarbon fuel and water are reacted on a catalyst to reform the hydrocarbon fuel to obtain a hydrogen-containing gas,
A fuel reforming method for causing the reforming reaction by irradiating the catalyst mixed with a microwave absorber with microwaves and heating the catalyst.   The fuel reforming method according to claim 7 or 8, wherein the catalyst is irradiated with microwaves in a range of 0.3 GHz to 30 GHz.   The fuel reforming method according to any one of claims 7 to 9, wherein the catalyst is irradiated with microwaves in a cavity resonator in which microwaves are introduced and brought into a resonance state.   11. The fuel reforming method according to claim 10, wherein the catalyst is placed at a position where the electric field intensity is maximum in a cavity resonator in which a microwave is introduced to be in a resonance state, and the microwave is irradiated.

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