JP2020070485A - Electric field catalytic reaction apparatus and electric field catalytic reaction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of electric discharge between electrodes used for applying an electric field when a dehydrogenation reaction for desorbing hydrogen from an organic hydride is carried out by an electric field catalytic reaction. SOLUTION: A dehydrogenation reactor 1 has a pair of electrodes 21A and 21B, a reactor 10 having a dehydrogenation catalyst arranged between the electrodes, and a raw material supply line L2 for supplying organic hydride to the reactor. A voltage application device 30 for applying a DC voltage to the electrodes 21A and 21B and a hydrogen supply line L3 for supplying hydrogen to the reactor 10 are provided, and the dehydrogenation catalyst applies a DC voltage to at least the electrodes 21A and 21B. In the state before the hydrogen is supplied, the catalyst including the catalyst reduced by the hydrogen supplied from the hydrogen supply line L3 is included. [Selection diagram] Fig. 1

Description

  TECHNICAL FIELD The present invention relates to an electric field catalytic reaction apparatus and an electric field catalytic reaction method for performing a chemical reaction in the presence of a catalyst to which an electric field is applied.

  Conventionally, a technique relating to an electric field catalytic reaction in which a chemical reaction is performed in the presence of a catalyst to which a weak electric field is applied has been developed (see Non-Patent Document 1). According to this electric field catalytic reaction, it becomes possible to proceed the chemical reaction even at a relatively low temperature where the reaction does not proceed in the conventional catalytic reaction, so that the effect of suppressing (decreasing) the reaction temperature and preventing the deterioration of the catalyst can be obtained. Is expected.

Sakurai, S., Ogo, S., & Sekine, Y. (Saori Sakurai, Shuhei Ogawa, Yasushi Sekine) (2016). Hydrogen production by steam reforming of ethanol over Pt / CeO2 catalyst in electric field at low temperature (Ceria Hydrogen production by steam reforming of ethanol in a low-temperature electric field using a supported platinum catalyst. Journal of the Japan Petroleum Institute, 59 (5), 174-183. DOI: 10.1627 / jpi.59.174

  By the way, as a result of diligent study by the inventors of the present application, the electric field catalytic reaction as described above can also be applied to a dehydrogenation reaction for desorbing hydrogen from an organic hydride under predetermined conditions, whereby It has been confirmed that effects such as suppression of the reaction temperature in the dehydrogenation reaction which is an endothermic reaction can be obtained.

  Furthermore, the inventors of the present application, in a reactor that performs such an electric field catalytic reaction, when applying a predetermined voltage between a pair of electrodes arranged so as to sandwich the catalyst layer, the insulating property of the catalyst layer It has been found that when the temperature is relatively high, a discharge occurs between the electrodes and a good dehydrogenation reaction is hindered.

  The present invention has been devised in view of such problems of the prior art, and when performing a dehydrogenation reaction for desorbing hydrogen from an organic hydride by an electric field catalytic reaction, an interelectrode electrode used for applying an electric field. The main object of the present invention is to provide an electric field catalytic reaction apparatus and an electric field catalytic reaction method capable of suppressing the occurrence of electric discharge in the electric field.

  In the first aspect of the present invention, there is provided a dehydrogenation reactor (1) for desorbing hydrogen from organic hydride, comprising a pair of electrodes (electrodes 21A, 21B) and a dehydrogenation catalyst arranged between the electrodes. A reactor (10) having the same, a raw material supply line (L2) for supplying the organic hydride to the reactor, a voltage applying device (30) for applying a DC voltage to the electrode, and hydrogen for supplying to the reactor. A hydrogen supply line (L3), and the dehydrogenation catalyst includes a catalyst reduced by the hydrogen supplied from the hydrogen supply line at least in a state before a DC voltage is applied to the electrode. It is characterized by

  According to this, when the dehydrogenation reaction for desorbing hydrogen from the organic hydride is performed by the electrocatalytic reaction, the dehydrogenation catalyst is reduced by reducing the dehydrogenation catalyst with hydrogen supplied from the hydrogen supply line to the reactor. Since it is possible to reduce the insulation properties of the, it is possible to suppress the occurrence of discharge between the electrodes used for applying the electric field.

  The second aspect of the present invention is characterized by further comprising a shutoff valve (25) capable of shutting off the flow of the hydrogen in the hydrogen supply line.

  According to this, since hydrogen is generated in the reactor as the dehydrogenation reaction progresses, after the dehydrogenation reaction stabilizes, the shutoff valve shuts off the flow of hydrogen in the hydrogen supply line, thereby eliminating unnecessary reaction to the reactor. It becomes possible to avoid the supply of hydrogen.

  In the third aspect of the present invention, the dehydrogenation catalyst contains platinum supported on a predetermined support, and the reduced catalyst has different valences with respect to a spectrum measured by X-ray photoelectron spectroscopy. The degree of reduction calculated as a percentage of the area of the platinum peak having a valence of zero out of the total area of the respective platinum peaks is 19% or more.

  According to this, it becomes possible to suppress the occurrence of discharge between the electrodes used for applying the electric field, based on an appropriate index relating to the reduction state of the dehydrogenation catalyst.

  In a fourth aspect of the present invention, the different valences of platinum are 0 valence, +2 valence, and +4 valence.

  According to this, it becomes possible to suppress the occurrence of discharge between the electrodes used for applying the electric field, based on an appropriate index relating to the reduction state of the dehydrogenation catalyst.

  The fifth aspect of the present invention is characterized in that the degree of reduction is 24% or more.

  According to this, it becomes possible to more reliably suppress the occurrence of discharge between the electrodes used for applying the electric field, based on an appropriate index relating to the reduction state of the dehydrogenation catalyst.

  According to a sixth aspect of the present invention, there is provided a dehydrogenation reaction method for desorbing hydrogen from an organic hydride, wherein the organic hydride is added to a reactor having a pair of electrodes and a dehydrogenation catalyst arranged between the electrodes. Is supplied, in the reactor, a dehydrogenation reaction of the organic hydride is performed in a state in which a DC voltage is applied between the electrodes, and hydrogen is supplied to the reactor at least before the start of the dehydrogenation reaction. Characterize.

  According to this, when the dehydrogenation reaction for desorbing hydrogen from the organic hydride is carried out by the electrocatalytic reaction, the dehydrogenation catalyst is reduced by the reduction of the dehydrogenation catalyst by the hydrogen supplied from the hydrogen supply line to the reactor. Since the insulating property of the catalyst for use can be reduced, it is possible to suppress the occurrence of discharge between the electrodes used for applying the electric field.

  The seventh aspect of the present invention is characterized in that the supply of the hydrogen to the reactor is stopped after the start of the dehydrogenation reaction.

  According to this, since hydrogen is generated by the dehydrogenation reaction in the reactor, it is possible to avoid unnecessary hydrogen supply by stopping the hydrogen supply to the reactor after the dehydrogenation reaction has stabilized. Becomes

  As described above, according to the present invention, when the dehydrogenation reaction for desorbing hydrogen from the organic hydride is performed by the electric field catalytic reaction, it is possible to suppress the occurrence of discharge between the electrodes used for applying the electric field. ..

Configuration diagram of a dehydrogenation reactor according to an embodiment Explanatory drawing which shows the detailed structure of the reactor shown in FIG. Explanatory drawing which shows the detailed structure of the electrode shown in FIG. The figure which shows the modification of the reactor shown in FIG. The figure which shows the modification of the dehydrogenation reaction apparatus shown in FIG. Explanatory diagram showing the effect of electric field application on hydrogen yield Explanatory diagram showing the effect of electric field application on the conversion rate of MCH Explanatory diagram showing the effect of catalyst type on hydrogen yield Explanatory diagram showing the effect of catalyst type on hydrogen yield Explanatory drawing showing the effect of LHSV on the MCH conversion rate Explanatory diagram showing the influence of the distance between electrodes on the MCH conversion rate Explanatory diagram showing the effect of MCH concentration in the raw material gas on the MCH conversion rate Explanatory drawing showing influence of surface area of catalyst on hydrogen yield Explanatory diagram showing the effect of the amount of catalyst carried on the hydrogen yield Explanatory drawing which shows the analysis result by XPS about several catalysts from which a reduction state differs. Explanatory drawing which shows the analysis result by XPS about several catalysts from which a reduction state differs. Explanatory drawing showing influence of reduction state of catalyst on hydrogen yield

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

  FIG. 1 is a configuration diagram of a dehydrogenation reaction apparatus 1 according to an embodiment of the present invention, and FIGS. 2 and 3 show detailed configurations of essential parts of a reactor 10 and electrodes 21A and 21B shown in FIG. 1, respectively. It is an explanatory view shown, and Drawing 4 is a figure showing a modification of reactor 10 shown in Drawing 1.

  The dehydrogenation reactor 1 is a device that desorbs hydrogen from organic hydride by a dehydrogenation reaction. The present embodiment shows an example in which methylcyclohexane (hereinafter referred to as MCH) is used as the organic hydride, and in the dehydrogenation reactor 1, hydrogen and toluene are mainly produced by the dehydrogenation reaction of MCH.

  As shown in FIG. 1, the dehydrogenation reaction apparatus 1 includes a raw material container 2 that contains MCH (liquid) that is a raw material for the dehydrogenation reaction. The raw material container 2 is supplied with an inert gas (here, Ar gas) via the gas supply line L1. The downstream end of the gas supply line L1 is in a state of being inserted into the liquid of MCH in the raw material container 2, whereby the MCH is bubbled by Ar gas introduced from the gas supply line L1 and mixed with Ar gas. The raw material gas is sent from the raw material container 2 to the raw material supply line L2. The MCH in the raw material container 2 is heated to a predetermined temperature (for example, about 60 ° C.) by a heater (not shown).

  The gas supply line L1 is provided with a flow rate adjusting valve 3 and a flow meter 4 for adjusting the flow rate of Ar gas. The operation of the flow rate adjusting valve 3 is controlled by a control command sent from the flow rate controller 5 according to the measurement value of the flow meter 4. In the dehydrogenation reaction apparatus 1, it is possible to control the flow rate of the source gas (here, a mixed gas of MCH and Ar) in the source supply line L2 by controlling the flow rate of the Ar gas by the flow rate adjusting valve 3.

  Here, the ratio of MCH in the source gas is about 20 mol% (that is, Ar gas is about 80 mol%), but the present invention is not limited to this, and the ratio of MCH can be appropriately changed. As described later, MCH alone (100% MCH) may be used as the source gas.

  The dehydrogenation reaction apparatus 1 includes a reactor 10 in which an electric field catalytic reaction is applied to the dehydrogenation reaction of MCH (that is, the MCH dehydrogenation reaction is performed in the presence of a catalyst to which an electric field is applied). The downstream end of the raw material supply line L2 is connected to the reactor 10, whereby the raw material gas is supplied from the raw material container 2. The raw material gas flowing through the raw material supply line L2 is heated to a predetermined temperature (for example, about 110 ° C.) by a heater (not shown).

  A hydrogen supply line L3 into which external hydrogen (or a gas containing hydrogen as a main component) is introduced is connected to the raw material supply line L2, whereby external hydrogen is supplied to the reactor 10 as needed. It is possible to The hydrogen supply line L3 is provided with a control valve 25 for controlling the flow rate of hydrogen from the outside (including the case where hydrogen is completely shut off).

  Hydrogen flowing through the hydrogen supply line L3 is supplied at the start of the dehydrogenation reaction in the reactor 10 (that is, until the dehydrogenation reaction becomes stable), and can be used for reduction of the dehydrogenation catalyst in the reactor 10. After the dehydrogenation reaction in the reactor 10 is stabilized, hydrogen is generated by the dehydrogenation reaction, so that the hydrogen flowing through the hydrogen supply line L3 can be shut off by the control valve 25. This makes it possible to avoid unnecessary supply of hydrogen to the reactor 10.

  The reactor 10 is provided with a heater 11 for controlling the temperature of the dehydrogenation reaction by supplying heat. The heater 11 is arranged so as to surround the outer periphery of the reactor 10, and its operation is controlled by the heating controller 12. As the heater 11, for example, a known device using Joule heat or induction heating can be used, but the heater 11 is not limited to this, and another known device such as a heat exchanger may be used.

  Further, the reactor 10 is provided with a temperature measuring device 13 for measuring a reaction temperature (here, a temperature of the catalyst layer 22 described later) and a temperature measuring device 14 for measuring a heater temperature. The heating controller 12 can control the operation of the heater 11 based on the measurement value of the temperature measuring device 14. As will be described later, it is preferable to control the heater 11 so that the reaction temperature is within the range of room temperature to 300 ° C.

  As shown in FIG. 2, the reactor 10 includes a pair of electrodes 21A and 21B arranged vertically in a substantially cylindrical outer shell 20 so as to face each other, and between the electrodes 21A and 21B. It has a substantially cylindrical catalyst layer 22 composed of the dehydrogenation catalyst. The electrodes 21A and 21B are attached to substantially disc-shaped support plates 23A and 23B that define the upper surface and the lower surface of the catalyst layer 22, respectively. The tips of the electrodes 21A and 21B are arranged so as to penetrate the central portions of the support plates 23A and 23B and project into the catalyst layer 22. The support plates 23A and 23B are not necessarily installed, and may be omitted if at least the catalyst layer 22 can be stably held.

  Further, as shown in FIG. 3, a plurality of through holes 24 for allowing the MCH before the reaction to pass through are provided at appropriate places on the support plate 23A. Although illustration is omitted, similarly, a plurality of through holes through which hydrogen and toluene after the reaction are passed are provided at appropriate places on the support plate 23B.

  The configuration of the electrodes in the reactor 10 is not limited to the configurations shown in FIGS. 1 to 3, and various changes can be made. For example, as shown in FIG. 4, in the reactor 10, a rod-shaped electrode 121A extending in the axial direction of the outer shell 20 having a substantially cylindrical shape, and a cylindrical shape arranged so as to surround the electrode 121A. It is also possible to have a configuration in which the electrode 121B of No. 1 is provided and the catalyst layer 122 is arranged between the electrodes 121A and 121B.

  Referring again to FIG. 1, one of the electrodes 21A and 21B is connected to the voltage applying device 30 that applies a DC voltage, and the other is connected to the ground. Accordingly, in the reactor 10, it is possible to apply a predetermined electric field to the catalyst layer 22 during the dehydrogenation reaction. In order to properly carry out the dehydrogenation reaction, the potential gradient between the electrodes 21A and 21B may be set in the range of 0.1 to 1000 V / mm, for example.

  The reaction products (hydrogen, toluene, and by-products) produced in the reactor 10 are sent to the gas-liquid separator 31 via the product transport line L4. The reaction product supplied to the gas-liquid separator 31 is cooled to a predetermined temperature (for example, about −5 ° C.) by a cooler (not shown).

  In the gas-liquid separator 31, the reaction product from the reactor 10 is separated into a gas containing mainly hydrogen and a liquid containing mainly toluene. The separated gas is sent to the outside (for example, a storage tank) via the hydrogen transportation line L5. In addition, the separated liquid is discharged to the outside (for example, a storage tank) via the liquid discharge line L6. A part of the liquid discharged from the liquid discharge line L6 is analyzed by, for example, a gas chromatograph using a hydrogen flame ionization type detector, and the concentrations of MCH, toluene and the like are measured.

  A flow meter (here, a volume flow meter) 32 that measures the flow rate of the gas separated by the gas-liquid separator 31 is provided in the hydrogen transportation line L5. A sampling line L7 for sampling a part of the flowing gas is connected to the hydrogen transport line L5 upstream of the flow meter 32. The gas sampled from the sampling line L7 is analyzed by, for example, a gas chromatograph using a hydrogen flame ionization type detector or a thermal conductivity type detector, and the concentrations of hydrogen and hydrocarbons are measured.

  The organic hydride used in the dehydrogenation reactor 1 is not limited to MCH, but may be a monocyclic hydrogenated aromatic compound such as cyclohexane or a bicyclic hydrogenated aromatic compound such as tetralin, decalin or methyldecalin. , A tricyclic hydrogenated aromatic compound such as tetradecahydroanthracene, or the like can be used alone or as a mixture of two or more kinds.

  Examples of the dehydrogenation catalyst constituting the catalyst layer 22 include platinum (Pt) and nickel on a carrier selected from cerium oxide, a solid solution of cerium oxide and zirconium oxide, titanium oxide, and porous titanium oxide. (Ni) and a Group 10 element such as palladium (Pd) and at least one active metal selected from rhodium (Rh), iridium (Ir), ruthenium (Ru), etc. However, the present invention is not limited to this, and a known catalyst used for the dehydrogenation reaction of organic hydride can be used.

  Further, as the material of the electrodes 21A and 21B, a stainless material is used here, but the material is not limited to this, and other known materials may be used.

  FIG. 5: is a figure which shows the modification of the dehydrogenation reaction apparatus 1 shown in FIG. In FIG. 5, the same components as those shown in FIG. 1 described above are designated by the same reference numerals.

In this modification, the gas supply line L1 for Ar gas shown in FIG. 1 is omitted, and the MCH (liquid) in the raw material container 2 is transported by the raw material pump 41 provided in the raw material supply line L2. It is supplied to the vaporizer 42. The MCH is supplied to the reactor 10 after being vaporized in the vaporizer 42. With such a configuration in which the flow rate of MCH is adjusted by the raw material pump 41, 100% of MCH can be used as the raw material gas in the modified example.

  Below, the Example of the dehydrogenation reaction by the above-mentioned dehydrogenation reaction apparatus 1 is described. However, the dehydrogenation reaction apparatus 1 or the dehydrogenation reaction method thereof according to the present invention can be performed under the specific conditions (for example, the size and operation of each component constituting the dehydrogenation reaction apparatus 1 and the catalyst). And the composition, the composition of raw material gas and reaction product, the flow rate, the pressure, etc.), and those skilled in the art can make various modifications within the scope of the present invention.

(Example 1)
As a dehydrogenation catalyst constituting the catalyst layer 22, 3 wt% Pt / CeO ₂ (3 wt% platinum supported on Ce-containing oxide: Japan reference catalyst JRC-CEO-1) was used. The carried precursor of Pt is Pt (NH ₃ ) ₄ (NO ₃ ) ₂ . The inner diameter of the reactor 10 was 6 mm, and the height of the catalyst layer 22 was 4.5 mm. The inner diameter of the reactor 10 is the inner diameter of the quartz glass tube forming the outer shell 20, and corresponds to the outer diameter of the catalyst layer 22 having a substantially columnar shape. The particle size of the dehydrogenation catalyst constituting the catalyst layer 22 was in the range of about 355 to 500 μm, and the weight of the catalyst layer 22 was 200 mg. It was used without reducing the calcined dehydrogenation catalyst (that is, without supplying hydrogen to the reactor 10 from the hydrogen supply line L3).

The raw material gas was supplied as a mixed gas of MCH and Ar (MCH: 6.4 ml / min, Ar gas: 30 ml / min). At this time, LHSV (Liquid Hourly Space Velocity) was 15.8 h ⁻¹ .

  The reaction temperature of the reactor 10 was changed between 150 ° C. and 500 ° C., and a dehydrogenation reaction of MCH was performed in a state where a DC voltage of 219 V (3 mA constant current) was applied to the electrodes 21A and 21B. At this time, the potential gradient between the electrodes 21A and 21B is about 50 V / mm.

(Comparative Example 1)
A conventional dehydrogenation reaction of MCH was performed under the same configuration and conditions as in Example 1 except that no voltage was applied to the electrodes 21A and 21B.

  FIG. 6 is an explanatory view showing the influence of the electric field application on the hydrogen yield in the above Example 1 and Comparative Example 1, and FIG. 7 is an explanation showing the influence of the above in Example 1 on the conversion rate of MCH. It is a figure. Table 1 shows the concentration of by-product methane in the reaction product of the dehydrogenation reaction.

<Evaluation of influence of electric field application on hydrogen yield>
As shown in FIG. 6, regarding Example 1 and Comparative Example 1 described above, the hydrogen yield (mol%) in the dehydrogenation reaction tends to increase as the catalyst temperature (reaction temperature) rises. Also, in Example 1, the same hydrogen yield as in Comparative Example 1 is achieved at a lower catalyst temperature. For example, in Example 1, the hydrogen yield is 90% when the catalyst temperature is about 300 ° C., whereas in Comparative Example 1, the similar hydrogen yield is achieved when the catalyst temperature is about 400 ° C. (Refer to the broken line in FIG. 6). That is, by applying the electric field catalytic reaction to the dehydrogenation reaction of MCH, the hydrogen yield similar to the conventional one (without applying the electric field) is realized at a lower temperature.

<Evaluation of the effect of electric field application on the production of by-product methane>
Further, as shown in Table 1, in Example 1, the production of by-product methane is suppressed as compared with Comparative Example 1. For example, when the hydrogen yield is set to 90%, 2852 ppm (catalyst temperature of 400 ° C.) by-product methane is produced in Comparative Example 1, whereas 202 ppm (catalyst temperature of 300 ° C.) of by-product is produced in Example 1. Raw methane is produced. That is, in order to achieve the same hydrogen yield, by applying the electrocatalytic reaction to the dehydrogenation reaction of MCH, the production of by-product methane is effectively suppressed as compared with the conventional reaction in which no electric field is applied. ..

<Evaluation of influence of electric field application on conversion rate of MCH>
Further, as shown in FIG. 7, in Example 1 above, when the reaction temperature is 200 ° C. or lower, the conversion rate of MCH exceeding the equilibrium conversion rate is realized. In this electric field catalytic reaction, it is considered that a reaction mechanism different from the conventional one occurs, and the reaction temperature is lower than the conventional dehydrogenation reaction temperature (for example, 300 to 400 ° C.) in a range of 300 ° C. or lower (more preferably At a reaction temperature of about 200 ° C.) is more advantageous with respect to the conversion of MCH.

  Although the data of less than 150 ° C. for Example 1 is omitted in FIG. 7, in Example 1 above, the conversion rate of MCH exceeding the equilibrium conversion rate was realized at the reaction temperature of room temperature (25 ° C.) or higher. It Therefore, it is advisable to control the heating (supply of heat) to the reactor 10 so that the reaction temperature falls within the range of room temperature to 300 ° C.

(Example 2)
As the dehydrogenation catalyst constituting the catalyst layer 22, 3 wt% Pt / TiO ₂ (a Ti-containing oxide on which 3 wt% platinum was supported) was used. The inner diameter of the reactor 10 was 6 mm, and the height of the catalyst layer 22 was 7 mm. The particle size of the dehydrogenation catalyst was in the range of about 355 to 500 μm, and the weight of the catalyst layer 22 was 200 mg. The calcined dehydrogenation catalyst was used without reduction treatment.

The raw material gas was supplied as a mixed gas of MCH and Ar (MCH: 6.4 ml / min, Ar gas: 30 ml / min). At this time, LHSV was 10.2 h ^-1 .

  The reaction temperature of the reactor 10 was set to about 150 ° C., and a dehydrogenation reaction of MCH was carried out for 120 minutes while applying a DC voltage of 178 V (constant current of 3 mA) to the electrodes 21A and 21B. At this time, the potential gradient between the electrodes 21A and 21B is about 25 V / mm.

(Comparative example 2)
The dehydrogenation reaction of MCH was carried out for 120 minutes under the same conditions as in Example 1 above.

  FIG. 8 is an explanatory diagram showing the influence of the type of catalyst on the hydrogen yield regarding Example 2 and Comparative Example 2 described above, and Table 2 shows the concentration of by-product methane in the reaction product of the dehydrogenation reaction. Show.

<Evaluation of explanatory diagram showing influence of catalyst type on hydrogen yield (1)>
As shown in FIG. 8, it was confirmed that the hydrogen yield (mol%) of Example 2 was slightly lower than that of Comparative Example 2.

<Evaluation of the effect of catalyst type on the production of by-product methane (1)>
On the other hand, as shown in Table 2, in Example 2, after the dehydrogenation reaction became stable (after 25 minutes had elapsed), the concentration of by-product methane became zero, which was higher than that in Comparative Example 2 (corresponding to Example 1). As a result, the production of by-product methane is suppressed more effectively. That is, using 3 wt% Pt / TiO ₂ (that is, a carrier containing titanium oxide) as the dehydrogenation catalyst forming the catalyst layer 22 is effective in reducing the amount of by-produced methane.

(Example 3)
As the dehydrogenation catalyst constituting the catalyst layer 22, 3 wt% Pt / HBT (HBT-containing oxide on which 3 wt% of platinum was supported) was used. HBT is a porous titanium oxide carrier having an inorganic oxide as a nucleus and titanium oxide supported on the surface thereof. More specifically, HBT contains 13 mass% or more of titanium oxide and is supported on the surface of an inorganic oxide, and the repeating length of the crystal lattice plane of titanium oxide on the surface of the inorganic oxide is 50 Å or less. Which is a porous titanium oxide carrier. The inner diameter of the reactor 10 was 6 mm, and the height of the catalyst layer 22 was 5.3 mm. The weight of the dehydrogenation catalyst was 70 mg. For details of the HBT, refer to Japanese Patent No. 3781417 of the applicant of the present application. HBT is also known as a hybrid titania catalyst (CT-HBT (registered trademark)).

The raw material gas was supplied as a mixed gas of MCH and Ar (MCH: 6.4 ml / min, Ar gas: 30 ml / min). At this time, LHSV was 13.4 h ^-1 .

  The reaction temperature of the reactor 10 was set to about 150 ° C., and a DC voltage of 160 V (3 mA constant current) was applied to the electrodes 21A and 21B to carry out a dehydrogenation reaction of MCH for 120 minutes. At this time, the potential gradient between the electrodes 21A and 21B is 30 V / mm.

(Comparative example 3)
The dehydrogenation reaction of MCH was carried out for 120 minutes under the same conditions as in Example 1 above.

  FIG. 9 is an explanatory diagram showing the influence of the type of catalyst on the hydrogen yield regarding Example 3 and Comparative Example 3 above, and Table 3 shows the concentration of by-product methane in the reaction product of the dehydrogenation reaction. Show.

<Evaluation of explanatory diagram showing influence of catalyst type on hydrogen yield (2)>
As shown in FIG. 9, it was confirmed that the hydrogen yield (mol%) of Example 3 was slightly lower than that of Comparative Example 3.

<Evaluation of the effect of catalyst type on the production of by-product methane (2)>
On the other hand, as shown in Table 3, in Example 3, after the dehydrogenation reaction became stable (after 25 minutes had elapsed), the concentration of by-product methane became zero, which was higher than that in Comparative Example 3 (corresponding to Example 1). As a result, the production of by-product methane is effectively suppressed. That is, using 3 wt% Pt / HBT as the dehydrogenation catalyst forming the catalyst layer 22 is effective in reducing the amount of by-produced methane.

(Example 4)
As the dehydrogenation catalyst forming the catalyst layer 22, 3 wt% Pt / CeO ₂ was used. The inner diameter of the reactor 10 was 10 mm, and the distance between the electrodes 21A and 21B (that is, the height of the catalyst layer 22) was 9 mm (or 18 mm). The particle size of the dehydrogenation catalyst was in the range of about 0.85 to 1.18 mm.

The raw material gas was a mixed gas of MCH and Ar, and when the distance between the electrodes 21A and 21B was 9 mm, the LHSV was 4 h ⁻¹ (MCH: 8.1 Ncm ³ / min, Ar gas: 25 Ncm ³ / min), 8 h ^{−. 1} (MCH: 16.9 Ncm ³ / min, Ar gas: 60 Ncm ³ / min) or 12 h ^-1 (MCH: 25.2 Ncm ³ / min, Ar gas: 94 Ncm ³ / min).

  The reaction temperature of the reactor 10 was set to about 150 ° C., and the dehydrogenation reaction of MCH was performed while changing the input power to the electrodes 21A and 21B.

<Evaluation of influence of LHSV on MCH conversion>
FIG. 10 is an explanatory diagram showing the effect of LHSV on the MCH conversion rate with respect to Example 4 above. Here, the distance between the electrodes 21A and 21B is 9 mm. As shown in the figure, the MCH conversion rate increases as the input power increases. Further, the MCH conversion rate decreases as the LHSV increases.

<Evaluation of influence of distance between electrodes on MCH conversion rate>
FIG. 11 is an explanatory diagram showing the influence of the inter-electrode distance on the MCH conversion rate in Example 4 described above. LHSV was 12 h ^−1, and when the distance between the electrodes 21A and 21B was 18 mm, the source gas was MCH: 50.4 Ncm ³ / min and Ar gas: 198 Ncm ³ / min. As shown in the figure, the MCH conversion rate decreases as the distance between the electrodes increases. The influence of the distance between the electrodes on the MCH conversion rate was the same when the inner diameter of the reactor 10 was 22 mm.

(Example 5)
As the dehydrogenation catalyst forming the catalyst layer 22, 3 wt% Pt / CeO ₂ was used. The inner diameter of the reactor 10 was 22 mm, and the distance between the electrodes 21A and 21B was 18 mm. The particle size of the dehydrogenation catalyst was in the range of about 0.85 to 1.18 mm.

The raw material gas was a mixed gas of MCH and Ar (MCH: 20%, Ar gas: 80%) or MCH 100%. For mixed gas of MCH and Ar, LHSV was set to 6 h ^−1, and for MCH 100%, LHSV was set to 8 h ⁻¹ .

  The reaction temperature of the reactor 10 was set to about 150 ° C., and the dehydrogenation reaction of MCH was performed while changing the input power to the electrodes 21A and 21B.

<Evaluation of influence of MCH concentration in raw material gas on MCH conversion rate>
FIG. 12 is an explanatory diagram showing the influence of the MCH ratio in the raw material gas on the MCH conversion rate in Example 5 described above. As shown in the figure, when the MCH concentration in the source gas is high (here, 100%), the MCH conversion rate is slightly lower than when the MCH concentration is low (here, 20%), but dehydration The elementary reaction proceeds without problems.

(Example 6)
A conventional dehydrogenation reaction of MCH was carried out under the same structure and conditions as in Example 1 except that the BET specific surface area of the catalyst was changed. BET specific surface area of the ^catalyst was ^{141.1m 2 /g,85.7m 2 /g,29.9m 2 /g,3.1m 2} / g or 1.7 m ² / g,. These BET specific surface areas are realized by setting the calcination temperature of the catalyst to 600 ° C., 700 ° C., 900 ° C., or 1100 ° C. without calcination, respectively.

<Evaluation of Effect of Surface Area of Catalyst on Hydrogen Yield>
FIG. 13 is an explanatory diagram showing the influence of the surface area of the catalyst on the hydrogen yield in Example 6 described above. As shown in the figure, as the BET specific surface area of the catalyst decreases, the catalyst activity decreases. When the BET specific surface area of the catalyst is 1.7 m ² / g (the calcination temperature of the catalyst is 1100 ° C.), the hydrogen yield becomes substantially zero. Therefore, the specific surface area of the catalyst is preferably 3.1 m ² / g or more.
(Example 7)
A conventional dehydrogenation reaction of MCH was performed under the same configuration and conditions as in Example 1 except for the change in the amount of Pt supported. The amount of Pt supported on the catalyst was set to 1 wt%, 3 wt%, or 5 wt%.

<Evaluation of influence of catalyst loading amount on hydrogen yield>
FIG. 14 is an explanatory diagram showing the effect of the amount of catalyst carried on the hydrogen yield in Example 6 above. As shown in the figure, when the Pt supported amount is 1 wt%, the hydrogen yield is lower than when the Pt supported amount is 3 wt% or 5 wt%, but the electric field dehydrogenation reaction proceeds. Therefore, the supported amount of Pt is preferably at least 1 wt% or more.

  Next, the reduction state of the dehydrogenation catalyst that affects the occurrence of discharge between the electrodes 21A and 21B will be described.

  When performing the dehydrogenation reaction in the reactor 10 shown in FIG. 1 or FIG. 5, if the insulating property of the catalyst layer 22 is relatively high, when a predetermined voltage is applied between the electrodes 21A and 21B. The discharge may occur between the electrodes 21A and 21B, and the dehydrogenation reaction (that is, application of an appropriate electric field to the catalyst) may be hindered. Therefore, as shown below, a part of the configuration of the above-described Example 1 was changed to perform a test for confirming the occurrence of discharge between the electrodes 21A and 21B.

3 wt% Pt / CeO ₂ (3 wt% platinum supported on Ce-containing oxide) was used as a dehydrogenation catalyst constituting the catalyst layer 22. The carried precursor of Pt is Pt (NH ₃ ) ₄ (NO ₃ ) ₂ . After supporting Pt, it was baked in air at 500 ° C. for 2 hours. The inner diameter of the reactor 10 was 10 mm, and the height of the catalyst layer 22 was 18 mm. The inner diameter of the reactor 10 is the inner diameter of the quartz glass tube forming the outer shell 20, and corresponds to the outer diameter of the catalyst layer 22 having a substantially columnar shape. The particle size of the dehydrogenation catalyst constituting the catalyst layer 22 was in the range of about 0.85 to 1.18 mm, and the weight of the catalyst layer 22 was 3.3 g.

Ar gas of 25 Ncm ³ / min and H ₂ gas of 2.5 Ncm ³ / min were supplied to the reactor 10, the catalyst temperature of the reactor 10 was set to about 25 ° C., and a DC voltage higher than the breakdown voltage was applied to the electrodes 21A and 21B. Was applied.

In addition, a plurality of catalysts having different reduction states were used as the catalysts forming the catalyst layer 22. Regarding the reduction state of the catalyst (here, the reduction state of Pt), (A) 25 ° C. reduction (Ar gas and H ₂ gas mentioned in the preceding paragraph were supplied and hydrogen reduction was performed at 25 ° C. for 30 minutes), ( B) 150 ° C. reduction (Ar gas and H ₂ gas mentioned in the preceding paragraph were supplied, hydrogen reduction was carried out at 150 ° C. for 30 minutes and then returned to 25 ° C.), (C) 500 ° C. reduction (referred to in the previous paragraph) The Ar gas and the H ₂ gas are supplied, hydrogen reduction is performed at 500 ° C. for 30 minutes and then returned to 25 ° C., and (D) reaction is performed (2 by the dehydrogenation reaction at about 150 ° C. in the reactor 10). (Reduced with hydrogen for an hour).

<Evaluation of influence of reduction state of catalyst on discharge generation between electrodes>
As a result of visual observation inside the reactor 10, when the catalyst in the reduced state (A) was used, discharge was generated between the electrodes 21A and 21B when the electric field was applied. That is, in the reduced state (A) at 25 ° C., the insulating property of the catalyst layer 22 is relatively high, which is considered to cause the discharge between the electrodes 21A and 21B.

  When the catalysts in the other reduced states (B) and (C) were used, no discharge was generated between the electrodes 21A and 21B when the electric field was applied. From this, it was confirmed that the discharge between the electrodes 21A and 21B can be suppressed by using the catalyst that has been reduced to some extent.

  However, as in the above-mentioned reduction states (A) to (D), in the method of identifying the reduction state of the catalyst by the difference in the reduction treatment, the degree of reduction of the catalyst necessary for suppressing discharge should be quantitatively evaluated. Is difficult Therefore, in order to quantitatively evaluate the reduction state of the dehydrogenation catalyst, an index (hereinafter referred to as reduction degree) based on the result of measurement by XPS (X-ray photoelectron spectroscopy) was introduced.

  15 and 16 are explanatory diagrams showing the measurement results by XPS (X-ray photoelectron spectroscopy) of a plurality of catalysts having different reduction states. FIG. 15 shows the analysis results for the reduction states (A) and (B) of the catalyst, and FIG. 16 shows the analysis results for the reduction states (C) and (D) of the catalyst. There is. Further, FIG. 17 is an explanatory diagram showing the influence of the reducing state of the catalyst on the hydrogen yield in the dehydrogenation reaction regarding the reducing states (B) and (C) shown in FIGS. 15 and 16, respectively. Here, the configuration and conditions of the dehydrogenation reaction other than the catalyst are the same as in the case of FIG. 14 described above.

VersaProbe 2 (manufactured by ULVAC-PHI, Inc.) was used as a device for measuring XPS. XPS measurement of Pt, 4f _7/2 orbit was performed using Al Kα ray as an X-ray source. The sample after each treatment was transferred from a reaction tube that could be sealed in a glove box purged with nitrogen so as not to be exposed to the atmosphere to a sample holder in a vessel, and then moved in a measurement chamber in vacuum. The parameters at the time of measurement are 200 times the number of sweeps and Pass Energy is 187.85 eV.

As analysis software, Multipak was used. For background correction, the C1s peak of the carbon double-sided tape used when fixing the sample to the holder was corrected to 284.8 eV. As the fitting function, the Gauss-Lorentz function is used, and the full width at half maximum FWHM (peak thickness) at the time of fitting is 2.62, 2.82 and 2.82 for Pt ⁰ , Pt ²⁺ and Pt ⁴⁺ , respectively. Since Pt4f ^7/2 and Pt4f ^5/2 have doublet peaks, the values of FWHM, etc. described above remain the same, and the theoretical value of energy shift +3.3 eV and the peak height ratio of 0.75 times are reflected to make the deconversion. The volume was implemented. In each sample, the residue was analyzed so that the residue was as small as possible while the position of the peak top was not displaced by 0.2 or more. For the position of peak top, refer to academic papers.

15 and 16, the degree of reduction of the catalyst (here, Pt) is Pt ⁰ , Pt ²⁺ , Pt ⁴⁺ for the peak of Pt (4f _7/2 , 4f _5/2 ) in the spectrum measured by XPS. The peak area (A (Pt ⁰ ), A (Pt ²⁺ ), A (Pt ⁴⁺ )) is calculated by split fitting with the three peaks, and the peak attributed to Pt ⁰ in the total area of each peak. The area ratio (area percentage) of the area (A (Pt ⁰ )) was defined as the degree of reduction.
Degree of reduction (%) = A (Pt ⁰ ) / (A (Pt ⁰ ) + A (Pt ²⁺ ) + A (Pt ⁴⁺ )) × 100

Table 4 shows the calculation results of the degree of reduction.

  As a result, the reduction degrees in the above-mentioned reduction states (A) to (D) are (A) 23.7%, (B) 37.2%, (C) 68.2%, and (D) 39.8, respectively. It became%. From these results, the degree of reduction of the dehydrogenation catalyst is higher than that of the catalyst in the reduced state (A) (for example, 24% or more) at least before the electric field is applied between the electrodes 21A and 21B. ), And more preferably, the degree of reduction of the catalyst in the reduced state (B) is not less than (37.2%).

  Since the reduction degrees of the reduced states (B) and (D) are almost the same, 37.2% and 39.8%, respectively, the reduction of the catalyst (Pt) dramatically progresses by the electric field reaction. There is no such thing.

  Further, as shown in FIG. 17, it was confirmed that the electric field reaction proceeds even when the reduced state (C) having the highest reduction degree among the reduced states (A) to (D) described above is used. However, in the reduced state (C), the catalyst is reduced at a higher temperature than in the reduced state (B) or (D), and as a result, the Pt particles aggregate to increase the particle size (sintering). Therefore, the activity of the catalyst may have decreased. That is, it is considered that the fact that the activity in the reduced state (C) is lower than that in the reduced state (B) is not directly due to the degree of reduction of the catalyst. Regarding the range of the degree of reduction of the catalyst for stable generation of electric field (suppression of discharge generation), at least as long as it does not significantly inhibit the activity of the catalyst (that is, the activity of the catalyst is within an allowable range for the desired reaction) The upper limit is not limited, and it is possible to adopt a degree of reduction that is larger than that in the reduced state (C).

  In the electric field dehydrogenation reaction, protons (H +) are generated from hydrogen supplied from the outside or hydrogen generated by the dehydrogenation reaction, and protons that move by the electric field and methylcyclohexane adsorbed on the Pt particles form an interface between the Pt particles and the carrier. I think it will react and proceed. If Pt at this interface is not reduced, protons cannot move and an electric field is not generated.

  As described above, in the dehydrogenation reactor 1 shown in FIG. 1 or FIG. 5, since the hydrogen supply line L3 for introducing the external hydrogen into the reactor 10 is provided, for example, the above-mentioned reduction state (B) It is possible to use a dehydrogenation catalyst substantially corresponding to

  More specifically, first, in the preparation step for the dehydrogenation reaction, the dehydrogenation catalyst after firing is placed between the electrodes 21A and 21B. Then, the reactor 10 is heated to 150 ° C., and the raw material gas is supplied to the reactor 10 through the raw material supply line L2. At this time, external hydrogen is mixed with the source gas via the hydrogen supply line L3. As a result, a part of the dehydrogenation catalyst in the reactor 10 is reduced by external hydrogen. Then, an electric field is applied to the electrodes 21A and 21B, and the dehydrogenation reaction in the reactor 10 is started. With such a configuration, the insulating property of the dehydrogenation catalyst can be reduced before the electric field is applied to the dehydrogenation catalyst, and thus it is possible to suppress the occurrence of discharge between the electrodes 21A and 21B. Become.

  The supply of external hydrogen via the hydrogen supply line L3 can be shut off by a control valve (shutoff valve) 25 at the start of the dehydrogenation reaction in the reactor 10. More preferably, the external hydrogen is supplied until the dehydrogenation reaction (that is, the generation of hydrogen) is stabilized. Depending on the case, it is also possible to continuously supply hydrogen to the reactor 10 during the dehydrogenation reaction without blocking external hydrogen.

  Further, in the dehydrogenation reaction apparatus 1, when using a dehydrogenation catalyst that has been reduced in advance (for example, reduction states (B) to (D)), external hydrogen supply (that is, the hydrogen supply line L3) is performed. It can be omitted.

  The present invention has been described above based on the specific embodiments, but these embodiments are merely examples, and the present invention is not limited to these embodiments.

  For example, the effect of suppressing the occurrence of discharge between the electrodes based on the adjustment of the reduction degree (reduction degree) of the catalyst used in the electric field catalytic reaction is the dehydrogenation reaction for desorbing hydrogen from the organic hydride and the dehydrogenation catalyst used therefor. However, the present invention is not limited to this, and can be similarly applied to other chemical reactions and catalysts used therefor.

  Further, each component of the electric field catalytic reaction device and the electric field catalytic reaction method according to the present invention shown in the above-mentioned embodiment is not necessarily all essential, as long as those skilled in the art do not deviate from the scope of the present invention at least. It is possible to select appropriately.

1: Dehydrogenation reactor 2: Raw material container 3: Flow control valve 4: Flow meter 5: Flow controller 10: Reactor 11: Heater 12: Heating controller 13: Temperature measuring device 20: Outer shells 21A, 21B: Electrode 22: Catalyst layers 23A, 23B: Support plate 24: Through hole 25: Control valve 30: Voltage application device 31: Gas-liquid separator 32: Flow meter 41: Raw material pump 42: Vaporizer 121A, 121B: Electrode 122: Catalyst Layer L1: Gas supply line L2: Raw material supply line L3: Hydrogen supply line L4: Product transport line L5: Hydrogen transport line L6: Liquid discharge line L7: Sampling line

Claims (7)

A dehydrogenation reactor for desorbing hydrogen from organic hydride,
A reactor having a pair of electrodes and a dehydrogenation catalyst disposed between the electrodes;
A raw material supply line for supplying the organic hydride to the reactor,
A voltage applying device for applying a DC voltage to the electrodes,
A hydrogen supply line for supplying hydrogen to the reactor,
Equipped with
The dehydrogenation reaction apparatus, wherein the dehydrogenation catalyst includes a catalyst reduced by the hydrogen supplied from the hydrogen supply line at least in a state before a DC voltage is applied to the electrodes.   The dehydrogenation reactor according to claim 1, further comprising a shutoff valve capable of shutting off the flow of the hydrogen in the hydrogen supply line. The dehydrogenation catalyst contains platinum supported on a predetermined carrier,
The reduced catalyst is related to the spectrum measured by X-ray photoelectron spectroscopy and is calculated as a percentage of the area of the platinum peak of zero valence among the total area of each peak of platinum of different valence. The degree is 24% or more, The dehydrogenation reaction apparatus of Claim 1 or Claim 2 characterized by the above-mentioned.   The dehydrogenation reactor according to claim 3, wherein different valences of the platinum are 0 valence, +2 valence, and +4 valence.   The dehydrogenation reactor according to claim 3 or 4, wherein the degree of reduction is 37.2% or more. A dehydrogenation reaction method for desorbing hydrogen from organic hydride,
Supplying the organic hydride to a reactor having a pair of electrodes and a dehydrogenation catalyst arranged between the electrodes,
In the reactor, a dehydrogenation reaction of the organic hydride is performed with a DC voltage applied between the electrodes,
A dehydrogenation reaction method comprising supplying hydrogen to the reactor at least before the start of the dehydrogenation reaction.   The dehydrogenation reaction method according to claim 6, wherein the supply of the hydrogen to the reactor is stopped after the start of the dehydrogenation reaction.

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