Reaction apparatus

Abstract

To provide a reaction apparatus capable of reducing catalyst deactivation.SOLUTION: The reaction apparatus comprises a first reactor that removes oxygen contained in exhaust gas containing carbon dioxide by a catalytic reaction between the exhaust gas and hydrogen to produce a product, and a second reactor that generates an energy carrier by a catalytic reaction between the product and hydrogen, wherein a first catalyst disposed in the first reactor is different in type from a second catalyst disposed in the second reactor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reactor for producing an energy carrier from exhaust gas. [Background technology]

[0002] The technology for producing energy carriers such as methane through a catalytic reaction between exhaust gas containing carbon dioxide and hydrogen has a problem in that the catalyst is deactivated when oxygen contained in the exhaust gas combines with the catalyst. The prior art disclosed in Patent Document 1 supplies a feed gas containing hydrogen, oxygen, and carbon dioxide to a reactor equipped with a catalyst, and methanation is initiated and continued using heat including reaction heat from catalytic combustion of hydrogen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 045101 Summary of the Invention [Problem to be solved by the invention]

[0004] In prior art, methanation can occur during catalytic combustion, resulting in the consumption of hydrogen. When hydrogen is consumed, there is a shortage of hydrogen to burn oxygen, and the oxygen can combine with the catalyst, deactivating the catalyst.

[0005] The present invention has been made to solve this problem, and has as its object to provide a reaction apparatus capable of reducing catalyst deactivation. [Means for solving the problem]

[0006] A first aspect to achieve this object includes a first reactor that removes oxygen contained in exhaust gas through a catalytic reaction between exhaust gas containing carbon dioxide and hydrogen to produce a product, and a second reactor that produces an energy carrier through a catalytic reaction between the product and hydrogen, wherein the first catalyst housed in the first reactor is of a different type from the second catalyst housed in the second reactor.

[0007] In a second embodiment, in the first embodiment, the first catalyst comprises a noble metal.

[0008] In a third aspect, in the first or second aspect, the second catalyst comprises nickel and the energy carrier is methane. [Effects of the Invention]

[0009] According to the present invention, an energy carrier is generated in the second reactor through a catalytic reaction between the product generated in the first reactor and hydrogen. In the first reactor, oxygen contained in the exhaust gas containing carbon dioxide is removed through a catalytic reaction between the exhaust gas and hydrogen, thereby reducing deactivation of the second catalyst housed in the second reactor. The first catalyst housed in the first reactor is of a different type from the second catalyst, and a catalyst suitable for removing oxygen can be used, thereby reducing deactivation of the first catalyst. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a reaction device according to a first embodiment. [Figure 2] FIG. 10 is a block diagram of a reaction device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a block diagram of a reaction apparatus 10 according to a first embodiment. The reaction apparatus 10 includes a first reactor 11 containing a first catalyst 12 and a second reactor 15 containing a second catalyst 16. An exhaust gas supply unit 13 supplies exhaust gas containing carbon dioxide to the first reactor 11. A first hydrogen supply unit 14 supplies hydrogen to the first reactor 11.

[0012] The exhaust gas supply unit 13 is not particularly limited as long as it can supply exhaust gas containing carbon dioxide, and examples thereof include a unit including a tank filled with exhaust gas containing carbon dioxide, a unit including a device that produces high-temperature gas for heating, or a device that simply combusts the gas. Examples of such devices include a boiler or an incinerator. Examples of places where exhaust gas is generated include power plants, factories, waste treatment facilities, natural gas fields, and oil fields.

[0013] The first hydrogen supply unit 14 is not particularly limited as long as it can supply hydrogen gas, and examples include a tank for storing compressed hydrogen or liquefied hydrogen, a hydrogen storage material, or a hydrogen production device such as a membrane reformer that produces hydrogen from natural gas or an electrolysis device that produces hydrogen by electrolysis of water.

[0014] The amount of hydrogen supplied by the first hydrogen supply unit 14 to the first reactor 11 is set according to the amount of oxygen in the exhaust gas supplied by the exhaust gas supply unit 13 to the first reactor 11. The amount of oxygen in the exhaust gas may be calculated by constantly detecting the flow rate of the exhaust gas supplied by the exhaust gas supply unit 13 to the first reactor 11 and the oxygen concentration of the exhaust gas, or may be calculated by measuring the oxygen concentration of the exhaust gas in advance and detecting the flow rate of the exhaust gas. The first hydrogen supply unit 14 supplies a required amount of hydrogen to the first reactor 11 so that the reaction represented by the chemical reaction formula 2H2 + O2 → 2H2O proceeds in the first reactor 11.

[0015] The first catalyst 12 promotes the reaction between oxygen and hydrogen contained in the exhaust gas through a surface reaction, maintaining combustion. The first catalyst 12 is suitable for catalytic combustion. Examples of the first catalyst 12 include a support carrying a precious metal such as Pd, Pt, Rh, Ru, or Ir. Examples of the support include a powder, pellet, or porous structure of an oxide containing one or more of alumina, silica, magnesia, titania, zirconia, niobia, silica-alumina, zeolite, and calcium phosphate. The porous structure is permeable, allowing gas to pass through. Gas also passes through the gaps between the powder and pellets.

[0016] The first reactor 11 removes oxygen contained in the exhaust gas through a surface reaction on the first catalyst 12 to generate products. The first reactor 11 may oxidize carbon monoxide, unburned hydrocarbons, black smoke, and the like contained in the exhaust gas through catalytic combustion. The products of the first reactor 11 by the catalytic reaction include carbon dioxide and water. The products may include oxides such as carbon monoxide, unburned hydrocarbons, and black smoke oxidized by catalytic combustion. The amount of oxygen contained in the products by the first reactor 11 can be made smaller than the amount of oxygen contained in the exhaust gas.

[0017] The second hydrogen supply unit 17 supplies hydrogen to the second reactor 15. The second hydrogen supply unit 17 is similar to the first hydrogen supply unit 14. The first hydrogen supply unit 14 and the second hydrogen supply unit 17 do not need to be provided separately, and the second hydrogen supply unit 17 may be omitted. In this case, a pipe connecting the first hydrogen supply unit 14 and the second reactor 15 is provided in addition to a pipe connecting the first hydrogen supply unit 14 and the first reactor 11, and hydrogen is supplied from the first hydrogen supply unit 14 to the first reactor 11 and the second reactor 15, respectively.

[0018] The amount of hydrogen supplied by the second hydrogen supply unit 17 to the second reactor 15 is set according to the amount of carbon dioxide in the exhaust gas supplied by the exhaust gas supply unit 13 to the first reactor 11. The amount of carbon dioxide in the exhaust gas may be calculated by constantly detecting the flow rate of the exhaust gas supplied by the exhaust gas supply unit 13 to the first reactor 11 and the carbon dioxide concentration of the exhaust gas, or may be calculated by measuring the carbon dioxide concentration of the exhaust gas in advance and detecting the flow rate of the exhaust gas. The amount of carbon dioxide in the product flowing through the pipe connecting the first reactor 11 and the second reactor 15 may be detected, and the second hydrogen supply unit 17 may supply hydrogen to the second reactor 15 in accordance with the amount of carbon dioxide detected.

[0019] The second reactor 15 generates an energy carrier through a catalytic reaction between the product and hydrogen. Examples of energy carriers include methane and methanol. When generating methane, the second hydrogen supply unit 17 supplies a required amount of hydrogen to the second reactor 15 so that the reaction represented by the chemical reaction formula CO2 + 4H2 → CH4 + 2H2O proceeds in the second reactor 15. When generating methanol, the second hydrogen supply unit 17 supplies a required amount of hydrogen to the second reactor 15 so that the reaction represented by the chemical reaction formula CO2 + 3H2 → CH3OH + H2O proceeds in the second reactor 15.

[0020] The second catalyst 16 can be any catalyst suitable for various chemical reactions that generate energy carriers. The second catalyst 16 reduces the activation energy of the chemical reaction that generates energy carriers, while the first catalyst 12 reduces the activation energy of catalytic combustion. Because the first catalyst 12 and the second catalyst 16 have different functions, the second catalyst 16 is of a different type from the first catalyst 12.

[0021] The second catalyst 16 is exemplified by a powder, pellet, or porous structure in which a catalytic solid material is supported on a carrier. The carrier is exemplified by a powder, pellet, or porous structure of an oxide containing one or more of alumina, silica, magnesia, titania, zirconia, niobia, silica-alumina, zeolite, and calcium phosphate. The porous structure is permeable to gas. Gas also passes through the gaps between the powder and pellets. The catalytic solid material is exemplified by a metal containing one or more of Fe, Co, Ni, Cu, and Ag. When methane is used as the energy carrier, the second catalyst 16 contains nickel.

[0022] Since the chemical reaction that generates energy carriers in the second reactor 15 is an exothermic reaction, once the chemical reaction starts in the second reactor 15, the reaction proceeds spontaneously. Because the product of the first reactor 11 is heated by catalytic combustion, the chemical reaction in the second reactor 15 is more likely to start.

[0023] Since the amount of oxygen contained in the product of the catalytic reaction in the first reactor 11 is smaller than the amount of oxygen contained in the exhaust gas, in the second reactor 15 where the catalytic reaction of the product with hydrogen occurs, it is possible to reduce deactivation of the second catalyst 16 due to bonding between the second catalyst 16 and oxygen. Because the amount of oxygen contained in the product is small, it is also possible to reduce the reaction heat due to the chemical reaction between oxygen and hydrogen in the second reactor 15. Therefore, it is possible to prevent thermal runaway of the exothermic reaction that generates energy carriers.

[0024] A cooler 18 is connected to the second reactor 15. Any cooler that can cool the produced gas, such as a heat exchanger, can be used as the cooler 18, without any restrictions. A separator 19 that separates water from the produced gas is connected downstream of the cooler 18. The cooler 18 cools the produced gas to the dew point, and the separator 19 separates the water condensed in the cooler 18. This makes it possible to increase the purity of energy carriers such as methane and methanol.

[0025] A second embodiment will be described with reference to Fig. 2. In the second embodiment, a reactor 20 will be described in which a separation device 22 is disposed between a first reactor 11 and a second reactor 15. In the second embodiment, the same parts as those described in the first embodiment will be assigned the same reference numerals as in the first embodiment, and detailed description thereof will be omitted.

[0026] 2 is a block diagram of a reaction apparatus 20 in the second embodiment. The reaction apparatus 20 includes a cooler 21 connected between the first reactor 11 and the second reactor 15, and a separator 22 connected between the cooler 21 and the second reactor 15. The cooler 21 can be any device that can cool the product, such as a heat exchanger, without any restrictions. The cooler 21 cools the product to the dew point, and the separator 22 separates the water condensed in the cooler 21.

[0027] When the amount of water contained in the product is reduced by the separator 22, the rate of the forward reaction of the chemical reaction that produces the energy carrier can be made higher than the rate of the reverse reaction in the second reactor 15 downstream of the separator 22. This makes it possible to increase the conversion rate of the energy carrier in the second reactor 15.

[0028] The reactor 20 is provided with a heating section 23 between the separator 22 and the second reactor 15, which heats the product flowing toward the second reactor 15. The heating section 23 heats the product cooled by the cooler 21 to the minimum temperature at which a chemical reaction that produces energy carriers starts. Because the chemical reaction that produces energy carriers is an exothermic reaction, the forward reaction predominates in the chemical reaction between the product heated to the minimum temperature at which the chemical reaction that produces energy carriers starts and hydrogen. This can improve the conversion rate of the energy carrier.

[0029] The heating section 23 is heated by the reaction heat of the first reactor 11. Since the heating section 23 is heated by utilizing the waste heat of the first reactor 11, the energy efficiency of the reactor 20 (the ratio of energy carriers to the total energy supplied to the reactor 20) can be improved compared to when the heating section 23 is heated by a heat source that uses energy supplied from an external source.

[0030] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention.

[0031] In the embodiments, the reactors 10 and 20 are described as being equipped with the separators 19 and 22 that separate the water condensed in the coolers 18 and 21, but the separators 19 and 22 are not limited to this. The separators 19 and 22 may be ones that separate water vapor without condensing it in the coolers 18 and 21, using a desiccant such as slaked lime, an adsorbent such as activated carbon or zeolite, a water separation membrane, or the like.

[0032] In the second embodiment, the heating unit 23 heats the product to the lowest temperature at which the chemical reaction that generates energy carriers starts, but this is not necessarily limited to this. The temperature to which the heating unit 23 heats the product may be lower than the temperature at which the chemical reaction that generates energy carriers reaches an equilibrium state. [Explanation of symbols]

[0033] 10,20 Reactor 11 First reactor 12 The First Catalyst 15 Second reactor 16 The Second Catalyst

Claims

1. A reactor for generating an energy carrier from exhaust gas containing carbon dioxide, a first reactor that removes oxygen contained in the exhaust gas through a catalytic reaction between the exhaust gas and hydrogen to produce a product; a second reactor that generates the energy carrier by a catalytic reaction between the product and hydrogen; A reactor in which a first catalyst housed in the first reactor is of a different type from a second catalyst housed in the second reactor.

2. 10. The reactor of claim 1, wherein the first catalyst comprises a precious metal.

3. the second catalyst comprises nickel; 3. The reactor according to claim 1, wherein the energy carrier is methane.

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