JP4408214B2 - Hydrogen-containing gas production method and hydrogen-containing gas production apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for producing a hydrogen-containing gas from hydrocarbons.

In recent years, there has been a growing need for hydrogen-containing gas production apparatuses for use in fuel cell hydrogen supply sources, hydrogen combustion engines, hydrogenation engines, exhaust gas purification reducing agent supply systems, and the like mounted on electric vehicles.
As a hydrogen-containing gas production apparatus used for the above-mentioned application, an apparatus for producing a hydrogen-containing gas by reforming a hydrocarbon using a catalyst is widely used. As hydrocarbons, devices that use gasoline and light oil that are widely distributed as existing fuels are considered promising.

JP 2001-080906 A

The hydrogen generation process in the conventional hydrogen-containing gas production apparatus is not limited to the apparatus disclosed in Patent Document 1 described above, and the nickel generation and noble metal catalysts (for example, rhodium catalyst) widely used in industry are modified. Using a quality reaction catalyst, hydrogen-containing gas is obtained by decomposing hydrocarbons such as gasoline and light oil at a high temperature of 600 ° C. or higher.
Although it depends on the size of the device (the larger the device, the larger the heat capacity), a device that requires a reaction at a high temperature requires time to raise the reactor and catalyst of the device to a predetermined temperature. In addition, there is a problem that it takes time from the start of the apparatus to the start of generation of the hydrogen-containing gas.
Furthermore, a large amount of energy is required to maintain the reactor and the catalyst of the apparatus at a temperature at which hydrogen-containing gas can be generated, which may increase the running cost.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a hydrogen-containing gas production method and a production apparatus capable of producing a hydrogen-containing gas at a lower temperature.

A first invention includes an insulator, a reaction portion provided on one surface of the insulator, filled with a reforming reaction catalyst and connected to a power source, and a heat generating electrode provided on the other surface In addition, a reactor having an injection device for injecting hydrocarbons into the reaction section performs plasma discharge in an air atmosphere containing moisture and injects hydrocarbons into the reforming reaction catalyst to produce hydrogen from the hydrocarbons This is a gas production method .
By bringing the hydrocarbon into contact with the reforming reaction catalyst in the presence of water, oxygen, and nitrogen, a hydrogen-containing gas can be obtained.
For example, when C ₈ H ₁₈ is used as the hydrocarbon,
C ₈ H ₁₈ + 8H ₂ O + 4 (O ₂ + 4N ₂ ) → 8CO ₂ + 17H ₂ + 16N ₂
As a result, a hydrogen-containing gas is generated.
In the hydrogen desorption reaction, the hydrogen-containing gas is produced by causing the temperature to be lower than that in the past (for example, 250 to 350 ° C.) and performing plasma discharge to cause the reaction.
Since the reaction is performed at a low temperature, the time from the start of heating of the apparatus for producing the hydrogen-containing gas to the temperature at which the hydrogen-containing gas can be generated is shortened, and the atmosphere temperature of the hydrogen desorption reaction is kept high. Therefore, the running cost of the hydrogen reaction can be reduced.

Moreover, it is considered that the hydrogen desorption reaction occurs at a low temperature due to plasma discharge for the following reason.
In other words, atoms and molecules that have reached the active point at high temperatures gain active energy due to heat and react to leave the active point. The point is left blocked, and the hydrogen desorption reaction is less likely to occur.
The active site in this specification is a place where a hydrogen desorption reaction actually occurs on the surface of the reforming reaction catalyst.
In the first invention, since the reaction is performed in the plasma discharge, high-energy electrons and molecules generated by the plasma discharge exist in the atmosphere. It is thought that these electrons and molecules collide with low-energy atoms and molecules attached to the active sites to give energy or physically blow them off to release the active sites.
Therefore, hydrocarbon hydrogen desorption reaction occurs at a low temperature, and a hydrogen-containing gas can be obtained.

  Moreover, plasma discharge acts directly on hydrocarbons, which can be decomposed and lowered. The decomposition of hydrocarbons is known to occur at lower temperatures as the hydrocarbons are lower (= lower molecular weight), so the energy of the plasma discharge breaks the bonds between the hydrocarbon molecules. By lowering, hydrocarbon hydrogen desorption reaction occurs at a low temperature, and a hydrogen-containing gas can be obtained.

In addition, the plasma discharge generates highly reactive radical atoms and radical molecules in the reaction atmosphere (for example, oxygen radicals), and another reaction that does not exist in the conventional hydrogen desorption reaction occurs. Hydrogen desorption reaction is generated from the hydrocarbon, and a hydrogen-containing gas can be obtained.
Moreover, even if the plasma discharge heats the reforming reaction catalyst locally and the atmospheric temperature of the reaction is low, the hydrogen desorption reaction is likely to occur.

The second invention comprises an insulator, a reaction portion provided on one surface of the insulator, filled with a reforming reaction catalyst and connected to a power source, and a heat generating electrode provided on the other surface. ,
The hydrogen-containing gas production apparatus comprises a reactor having an injection device for injecting hydrocarbons into the reaction section.

In the production apparatus according to the second invention, the reactor has an injection device for injecting hydrocarbons into the reaction part, and the reaction part is made of an insulator including a discharge electrode and a heating electrode. A reforming reaction catalyst is supported on the discharge electrode.
Therefore, by injecting hydrocarbons from the injection device to the reforming reaction catalyst in the reaction section, a hydrogen desorption reaction occurs in the hydrocarbons and a hydrogen-containing gas is generated.
At this time, since the periphery of the reforming reaction catalyst is a discharge electrode, the discharge electrode is connected to a power source, and the insulator is provided with a heating electrode, so that a discharge is generated between the discharge electrode and the surface of the insulator. As a result, this discharge generates a plasma. Further, the insulator has a heating electrode, and the insulator can be heated.
Therefore, by using the production apparatus according to the present invention, a hydrogen-containing gas can be produced from a hydrogen desorption reaction in a heated atmosphere during plasma discharge, and a hydrogen-containing gas can be obtained at a lower temperature than conventional. .

  As mentioned above, this invention can provide the hydrogen containing gas manufacturing method and manufacturing apparatus which can manufacture hydrogen containing gas at lower temperature.

In the first and second inventions, any hydrocarbon can be used as a raw material hydrocarbon for producing a hydrogen-containing gas, regardless of chain, cyclic, saturated, or unsaturated.
Among these, it is desirable to use an easily available hydrocarbon fuel. For example, gasoline and light oil. In addition, methane, propane, natural gas, naphtha, kerosene, liquefied petroleum gas, city gas, etc. can be used. In order to utilize the liquid film reaction described later, it is more preferable to use liquid hydrocarbons.

In the first and second inventions, when the hydrocarbon is injected onto the reforming reaction catalyst, the liquid hydrocarbon is used in the form of fine droplets, and a liquid film is formed on the surface of the reforming reaction catalyst. It is preferable to form a very thin film of about one molecule that causes a reaction.
Considering the state of hydrocarbons in contact with the reforming reaction catalyst, the problem is that the concentration is low in gas, the hydrogen-containing gas after hydrogen desorption reaction is difficult to be released in liquid, and the temperature of the reforming reaction catalyst is difficult to increase. In order to solve this problem, it is preferable to form a liquid film on the surface of the reforming reaction catalyst to cause a hydrogen desorption reaction.
In the first invention, the discharge can be generated by arc discharge, glow discharge, high frequency discharge or the like.

In the second aspect of the invention, the discharge electrode is provided on the surface of the insulator so that a discharge is generated at the discharge electrode and the hydrogen desorption reaction is promoted by utilizing the plasma generated by the discharge. .
In the second invention, either an AC power source or a DC power source can be used as the power source. For example, by using an AC power supply, creeping discharge can be generated at the discharge electrode, and plasma can be generated therefrom. Furthermore, for example, a direct current pulse power supply is used to generate a barrier discharge, and plasma can be generated therefrom.

A hydrogen-containing gas production apparatus according to the second invention will be described.
It is preferable that the discharge electrode is made of aluminum having a porous oxide film oxidized on the outer surface.

Since the outer surface of the discharge electrode is filled with the reforming reaction catalyst, a larger surface area is preferable. By using a porous oxide film, it is possible to increase the surface area, increase the amount of the reforming reaction catalyst supported, and facilitate the hydrogen desorption reaction.
Furthermore, since it is necessary to pass an electric current through the discharge electrode, it is preferable from the viewpoint of conductivity that the inside remains as aluminum.
In addition, as the aluminum on which the porous oxide film is formed, alumite-treated aluminum is specifically used.

  The heating electrode also serves as a ground electrode for the discharge electrode, and further functions as a heating resistor. For this reason, it is preferable to use a conductive material known as a heating resistor, such as tungsten alone, nichrome, or Inconel.

Next, a discharge electrode carrying a mesh-shaped reforming reaction catalyst in close contact with the outer surface of the insulator,
Alternatively, it is preferable that a mesh-like discharge electrode is provided in close contact with the reforming reaction catalyst supported on the outer surface of the insulator.
That is, either the discharge electrode or the insulator can be selected as the loading destination of the reforming reaction catalyst. Of course, it can carry | support to both.
The insulator can also be made of a suitable insulating ceramic or the like. Usually, glass or the like is often used.

Next, it is preferable that the heat generating electrode is configured on the opposite side of the mesh-like discharge electrode with the insulator interposed therebetween.
According to this configuration, the heating electrode can be easily fixed to the insulator.

Then, before Symbol the reforming reaction catalyst, it can be used consisting of catalyst carrier to form a metal oxide on a carrier).
Specifically, the metal oxide constituting the catalyst carrier is made of at least one material selected from the group consisting of silica, alumina, silica / alumina, titanium oxide, zirconium oxide, magnesium oxide, and calcium oxide. Is preferred.

The carrier constituting the catalyst carrier is preferably made of at least one material selected from mesoporous material, microporous material, porous zeolite, activated carbon, carbon nanofiber, carbon nanotube, and carbon nanohorn ( Claim 8).
Here, the mesoporous material is a porous material having pores of 2 to 50 nm, and the microporous material is a porous material having pores of 2 nm or less.
Moreover, as a microporous body, porous zeolites having a micropore diameter such as ZSM-5, MSM-22, NaY, and LY can be used. As a mesoporous body, FSM-16, MCM-41, and the like can be used. A porous material having a mesopore diameter can be used.
In particular, a catalyst composed of nickel-manganese, nickel-tungsten, rhodium simple substance, ruthenium simple substance, and rhodium-ceria is more preferable because it has high activity and high selectivity in a reaction for obtaining hydrogen from hydrocarbon.

Example 1
A method for producing a hydrogen-containing gas according to the present invention and an apparatus used for the production will be described with reference to FIGS.
In this example, plasma discharge is performed in an atmosphere containing moisture, and hydrocarbons are injected onto the reforming reaction catalyst. Thereby, hydrogen is desorbed from the hydrocarbon to produce a hydrogen-containing gas.
As shown in FIGS. 1 to 3, the hydrogen-containing gas production apparatus 1 used for producing the hydrogen-containing gas is provided on the insulator 20 and one surface 201 of the insulator 20 and is filled with the reforming reaction catalyst. A reactor 10 having a reaction part 2 having a discharge electrode 21 connected to an AC power source 230 and a heating electrode 22 provided on the other surface 202, and an injector 11 for injecting hydrocarbon 12 into the reaction part 2. Consists of.

This will be described in detail below.
As shown in FIG. 2, the hydrogen-containing gas production apparatus 1 of this example includes a reactor 10, an injection device 11, a reaction unit 2, and the like.
The injection device 11 includes a nozzle 111 connected to a transfer pipe 110 through which a hydrocarbon 31 is delivered by a high-pressure pump 112 from a tank (not shown). The hydrocarbon 31 is ejected from the tip nozzle 111 into the reaction unit 2 as fine droplets having a diameter of about 2 to 100 μm.
In addition, in order to spray hydrocarbons on the surface of the discharge electrode 21 provided with the reforming reaction catalyst in the reactor 10, a flow rate control device for sending liquid hydrocarbons in the form of mist by controlling the spray force and spray interval. A needle valve 121 to which a transfer pipe 120 having 122 is connected is provided.
Furthermore, a needle valve 131 is provided to which a liquid supply device 133 for sending water 34 to the reactor 10 and a transfer pipe 130 having a flow rate control device 132 for sending the atmosphere 33 are connected.
Further, a needle valve 122 connected to a transfer pipe 120 that sends out the carrier gas 32 is provided.
The nozzle 111 and needle valves 121 and 131 are installed in the upper part of the reactor 10.

The reaction unit 2 is installed at the bottom of the reactor 10 using a flange 14.
As shown in FIGS. 1 and 3, the reaction unit 2 has a mesh-like discharge electrode 21 wound around an outer surface 201 of a cylindrical insulator 20, and a heat generating electrode 22 made of a thin wire is spirally installed on an inner surface 202. To do.
The discharge electrode 21 is made of an aluminum mesh whose surface is anodized, and the heating electrode 22 is made of a metal wire made of tungsten and having a thickness of 0.5 mm. The insulator 20 is made of a quartz glass tube.
The surface of the discharge electrode 21 is filled with a reforming reaction catalyst. As the reforming reaction catalyst, a powder catalyst made of Ni—Mn was used. The carrying amount is 10.1 g / m ^{2. The} discharge electrode 21 and the heating electrode 22 are connected to a circuit 23 having an AC power source 230, and one end of the circuit 23 is grounded (reference numeral 245).
Further, the heating electrode 22 is connected to a circuit 24 having a DC power supply 240. One end of the circuit 24 is also grounded (reference numeral 245).
The AC power supply 230 is a 9 kVp-p inverter neon transformer power supply (M-5 manufactured by LECIP CORPORATION).
In addition, an oscilloscope 231 is connected to the circuit 23 for monitoring the status of the AC power supply 230, and the temperature of the reaction part 2 in the reactor 10 is measured to control the operation of the DC power supply 240 that applies a voltage to the heating electrode 22. The controller 241 to be connected is connected to the circuit 241, and a thermocouple 242 connected to the controller 241 is installed in the vicinity of the reaction unit 2.

Further, an outlet 100 for taking out the produced hydrogen-containing gas 41 is provided further below the reaction section 2 of the reactor 10.
The outlet 100 is connected to a vent 156 via two switching valves 151 and 153 and a gas flow meter 155. A gas analyzer 152 that measures the hydrocarbon concentration is connected between the switching valves 151 and 153, and a gas analyzer 154 that measures the hydrogen concentration is connected between the switching valve 153 and the gas flow meter 155.
These analyzers 152 and 154, each gas flow meter 155, etc. are measuring devices used for analyzing the operating state of the hydrogen-containing gas production apparatus 1.

The operation of the hydrogen-containing gas production apparatus 1 will be described.
Air containing moisture (atmosphere 33) and carrier gas 32 (N ₂ or an inert gas such as helium or argon and hydrogen) are introduced into the reactor 10 from the needle valves 121 and 131.
Here, an inert gas such as N _2, helium, or argon is used to provide an inert atmosphere by exchanging the internal gas in the reactor 10 and to adjust the oxygen supply amount in the air. Hydrogen is used for the activity and reduction of the reforming reaction catalyst.

Further, the hydrocarbon is sprayed from the nozzle 111 to the reaction unit 2 in a fine droplet state.
When the discharge electrode 21 and the heating electrode 22 are energized from the AC power source 230 and the DC power source 240, respectively, creeping discharge occurs between the mesh and the outer surface 201 of the insulator 20, and the heating electrode 22 generates heat. Then, the discharge electrode 21 together with the insulator 20 and the reforming reaction catalyst supported on the discharge electrode 21 are heated.
On the discharge electrode 21, the hydrocarbon 31 is decomposed together with water and oxygen to generate a gas containing hydrogen. The composition of the hydrogen-containing gas 35 varies depending on the type of hydrocarbon 31 used as a raw material, but when C ₈ H ₁₈ is used,
C ₈ H ₁₈ + 8H ₂ O + 4 (O ₂ + 4N ₂ ) → 8CO ₂ + 17H ₂ + 16N ₂
As a result, a hydrogen-containing gas 35 in which carbon dioxide, nitrogen, and the remaining air and moisture are mixed is generated.
The hydrogen-containing gas 35 can be taken out from the outlet 100 through the vent 156.

In order to compare the method for producing a hydrogen-containing gas according to this example with a conventional method, a test was performed as follows.
In the hydrogen-containing gas production apparatus 1 according to FIG. 2, isooctane C ₈ H ₁₈ is used as the hydrocarbon 31 to be supplied, the supply pressure of isooctane is 12 Pa, the voltage of the AC power supply 230 for performing plasma discharge is ± 9 kV, and nickel as the catalyst The time for spraying the manganese catalyst into the reactor 2 of the hydrocarbon 31 is 1000 seconds. This spraying was performed intermittently at intervals of 2 milliseconds.
Then, hydrogen was desorbed using the controller 241 such that the temperature measured by the thermocouple 242 was 300 ° C. or 600 ° C.
For comparison, the AC power supply 230 is turned off, and the production of the hydrogen-containing gas is performed only by the thermal energy obtained from the heating electrode 22, and the case where the temperature of the thermocouple 242 is 300 ° C. or 600 ° C. went.
Then, the amount of hydrogen contained in the hydrogen-containing gas 35 taken out from the outlet 100 was measured. Further, the hydrogen conversion rate (= residual isooctane / introduced isooctane) was determined from the amount of isooctane remaining in the hydrogen-containing gas 35 and the amount of isooctane introduced into the reactor 10. These results are shown in Table 1.

From Table 1, it was found that by performing discharge, the amount of hydrogen produced and the conversion rate increased, and even at a high temperature of 600 ° C., a sufficient amount of hydrogen production and conversion rate could be obtained at 300 ° C.
Further, when the power consumption in the AC power supply 230 and the DC power supply 240 is evaluated, when discharging is performed at 300 ° C., the power consumption of the DC power supply 240 is 98.6 W, the power consumption of the AC power supply 230 is 12.6 W, and the total is 111. It became 2W.
When the discharge was not performed at 600 ° C., the power consumption of the AC power supply 230 was zero, but the power consumption of the DC power supply 240 was 294 W because the reaction unit 2 had to be heated to a higher temperature.

As described above, in this example, in the hydrogen desorption reaction, the hydrogen-containing gas is produced by performing plasma discharge (for example, 250 to 350 ° C.) and performing the reaction at a temperature lower than the conventional temperature.
Since the reaction is performed at a low temperature, the time from the start of heating of the hydrogen-containing gas production apparatus to the temperature at which the hydrogen-containing gas can be generated can be shortened.
Further, as is clear from the above test, since the power consumed by the heating electrode is small even if the power required for discharging is added, the power consumption can be reduced compared with the conventional method, and the running cost of the apparatus is low. It can be.
As described above, according to this example, it is possible to provide a method and apparatus for producing a hydrogen-containing gas capable of producing a hydrogen-containing gas at a lower temperature, and to provide a method and apparatus for producing a hydrogen-containing gas with low power consumption. it can.

As shown in FIG. 4, a cylindrical insulating support in which a mesh-like discharge electrode 21 is provided in close contact with the outer surface 201 of a cylindrical insulator 20 and a spiral groove (not shown) is provided on the outer surface 209. A thin wire can be wound around the body 208 along the spiral groove and inserted through the cylindrical insulator 20.
In this configuration, the heating electrode 22 can be fixed to the insulator 20 so as not to be in close contact with and misaligned.
Therefore, the heat of the heating electrode 22 can be efficiently transmitted to the discharge electrode 21 and the catalyst supported on the discharge electrode 21 through the insulator 20.
Other details are the same as those of the reaction section 2 having the configuration shown in FIG.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a main part explanatory view showing a reaction part according to Example 1; 1 is an explanatory diagram of a configuration of a hydrogen-containing gas production apparatus according to Embodiment 1. FIG. 3 is an explanatory diagram showing a structure of a reaction unit according to Example 1; BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the reaction part which wound the thin wire around the cylindrical insulation support body provided with the spiral groove concerning Example 1, and comprised the heating electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrogen-containing gas production apparatus 11 Injection apparatus 10 Reactor 2 Reaction part 20 Insulator 21 Discharge electrode 22 Heating electrode 230 AC power supply 240 DC power supply 31 Hydrocarbon

Claims (9)

A reaction portion provided on one surface of the insulator, filled with a reforming reaction catalyst and connected to a power source, and a heat generating electrode provided on the other surface; and carbonizing the reaction portion. A hydrogen-containing gas characterized by producing hydrogen from a hydrocarbon by performing plasma discharge in an atmosphere containing moisture in a reactor having an injector for injecting hydrogen and injecting hydrocarbon onto a reforming reaction catalyst Production method.   A reaction portion provided on one surface of the insulator, filled with a reforming reaction catalyst and connected to a power source, and a heat generating electrode provided on the other surface; and carbonizing the reaction portion. A hydrogen-containing gas production apparatus comprising a reactor having an injection device for injecting hydrogen. Before Symbol discharge electrodes, the hydrogen-containing gas production apparatus according to claim 2, characterized in that it characterized in that it consists of aluminum porous oxide film which is oxidized to the outer surface of which is formed. Provided discharge electrodes meshed in close contact with the front Symbol discharge electrode carrying a mesh of the reforming reaction catalyst in close contact with the outer surface of the insulator reforming reaction catalyst or supported on an outer surface of the insulator, The hydrogen-containing gas production apparatus according to claim 2 or 3, wherein Before SL heating electrode before Symbol hydrogen-containing gas production apparatus according to claim 4, wherein the configuring the opposite side of the mesh-like discharge electrodes sandwiching the insulator. Before Kiaratame reforming reaction catalyst is at least one selected nickel, manganese, palladium, platinum, rhodium, iridium, ruthenium, molybdenum, rhenium, tungsten, vanadium, osmium, chromium, iron, cobalt, lanthanum, from the group consisting of cerium The hydrogen-containing gas production apparatus according to any one of claims 2 to 5, wherein the hydrogen-containing gas production apparatus is made of the following material. Before Kiaratame reforming reaction catalyst, a hydrogen-containing gas production apparatus according to any one of claims 2 to 6, characterized in that it consists of catalyst carrier to form a metal oxide on a carrier. Metal oxides constituting the front Symbol catalyst support, silica, alumina, silica-alumina, titanium oxide, zirconium oxide, magnesium oxide, characterized in that it consists of at least one material selected from the group of calcium oxide The hydrogen-containing gas production apparatus according to claim 7 . Carrier which constitutes prior Symbol catalyst support, mesoporous, microporous member, and wherein the porous zeolite, activated carbon, carbon nanofiber, carbon nanotube, in that it consists of at least one material selected from carbon nanohorn The hydrogen-containing gas production apparatus according to claim 7 .

Images