Nitrous oxide purification system, internal combustion engine system, and nitrous oxide purification method

Abstract

The invention provides a nitrous oxide purification system, an internal combustion engine system, and a nitrous oxide purification method, which can easily obtain the effect of sufficient decomposition or reduction of nitrous oxide. A nitrous oxide purification system (10) is provided with an intake unit (14) and a purification unit (1). The intake unit (14) takes nitrous oxide in a state in which O2 and / or H2O coexist. The purification unit (1) decomposes or reduces the nitrous oxide taken in by the taking-in unit (14).

Description

Technical Field

[0001] The present invention relates to a nitrous oxide purification system for decomposing or reducing nitrous oxide, an internal combustion engine system and a nitrous oxide purification method. Background Art

[0002] As a related art, a catalyst composite for removing nitrous oxide (N2O) is known (see, for example, Patent Document 1). In this related art, a catalyst material is contained on a support, and the catalyst material comprises a rhodium (Rh) component supported on a cerium oxide-based carrier. Measurement of the catalyst composite by hydrogen temperature reduction (H2-TPR) reveals an H2 consumption peak below approximately 100°C.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2017-538573 Summary of the Invention

[0006] However, the catalyst composite according to the related art has difficulty in achieving a sufficient decomposition or reduction effect on, for example, nitrous oxide in exhaust gas from an engine in a temperature range comparable to the exhaust heat of the engine.

[0007] An object of the present invention is to provide a nitrous oxide purification system, an internal combustion engine system, and a nitrous oxide purification method that can easily achieve a sufficient decomposition or reduction effect of nitrous oxide.

[0008] A nitrous oxide purification system according to one embodiment of the present invention includes an intake unit and a purification unit. The intake unit takes in nitrous oxide in the presence of O2 and / or H2O. The purification unit decomposes or reduces the nitrous oxide taken in by the intake unit.

[0009] A nitrous oxide purification system according to one embodiment of the present invention includes an intake unit and a purification unit. The intake unit takes in nitrous oxide. The purification unit decomposes or reduces the nitrous oxide taken in by the intake unit. The purification unit includes a catalyst for decomposing or reducing the nitrous oxide and an electrode for applying an electric field to the catalyst.

[0010] An internal combustion engine system according to one embodiment of the present invention includes the nitrous oxide purification system and an engine. The nitrous oxide purification system is disposed in an exhaust gas path originating from the engine.

[0011] A nitrous oxide purification method according to one embodiment of the present invention comprises the steps of: taking in nitrous oxide in the presence of O 2 and / or H 2 O; and decomposing or reducing the taken-in nitrous oxide.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide a nitrous oxide purification system, an internal combustion engine system, and a nitrous oxide purification method that can easily achieve a sufficient decomposition or reduction effect of nitrous oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram showing the configuration of an internal combustion engine system according to the first embodiment.

[0015] Figure 2 This is a schematic diagram showing the configuration of the nitrous oxide purification system according to the first embodiment.

[0016] Figure 3 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the temperature of the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0017] Figure 4 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the material of the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0018] Figure 5 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the material of the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0019] Figure 6 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the material of the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0020] Figure 7 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the material of the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0021] Figure 8 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the composition of the gas causing the catalyst to act is changed in the nitrous oxide purification system according to the first embodiment.

[0022] Figure 9This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the composition of the gas causing the catalyst to act is changed in the nitrous oxide purification system according to the first embodiment.

[0023] Figure 10 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the composition of the gas causing the catalyst to act is changed in the nitrous oxide purification system according to the first embodiment.

[0024] Figure 11 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the space velocity of the gas causing the catalyst to act is changed in the nitrous oxide purification system according to the first embodiment.

[0025] Figure 12 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the current value flowing through the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0026] Figure 13 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when the current value flowing through the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0027] Figure 14 This is a graph showing an example of an actual value of the nitrous oxide purification rate when a reducing agent is used in the nitrous oxide purification system according to the first embodiment.

[0028] Figure 15 This is a graph showing an example of an actual value of the nitrous oxide purification rate when a reducing agent is used in the nitrous oxide purification system according to the first embodiment.

[0029] Figure 16 This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when hydrogen is used as a reducing agent in the nitrous oxide purification system according to the first embodiment.

[0030] Figure 17 This is a graph showing an example of an actual value of the nitrous oxide purification rate when ammonia is used as a reducing agent in the nitrous oxide purification system according to the first embodiment.

[0031] Figure 18 This is a graph showing an example of an actual value of the nitrous oxide purification rate when a reducing agent is used in the nitrous oxide purification system according to the first embodiment.

[0032] Figure 19This is a graph showing an example of actual values ​​of the nitrous oxide purification rate when a reducing agent is used and the material of the catalyst is changed in the nitrous oxide purification system according to the first embodiment.

[0033] Description of Reference Numerals

[0034] 1…Purification unit; 2…Control unit; 3…Power supply device; 4…Heating unit; 10…Nitrous oxide purification system; 11…Catalyst; 12, 13…Electrodes; 14…Intake unit; 100…Internal combustion engine system; 101…Engine. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiments are examples of implementing the present invention, and their purpose is not to limit the technical scope of the present invention. In addition, the detailed shapes of various parts are appropriately omitted in the accompanying drawings.

[0036] (Implementation 1)

[0037] [1] Overall structure of the internal combustion engine system

[0038] First, refer to Figure 1 The overall configuration of the internal combustion engine system 100 according to the present embodiment will be described. Figure 1 Schematically illustrating the structure of each portion of the internal combustion engine system 100 , and the flow of gas or liquid is indicated by bold arrows.

[0039] like Figure 1 As shown, the internal combustion engine system 100 according to this embodiment includes an engine 101, which constitutes the main component of the internal combustion engine system 100. The term "engine" herein refers to a heat engine that generates mechanical energy (power) by burning fuel, and includes an internal combustion engine, which is a prime mover that burns fuel within the heat engine and uses combustion gas as working gas to convert thermal energy into mechanical energy. Specifically, the engine 101 generates power (mechanical energy) using the supplied fuel.

[0040] In this embodiment, an internal combustion engine system 100 for a ship is described as an example. That is, the internal combustion engine system 100 is mounted on the hull of the ship. The engine 101 of the internal combustion engine system 100 is used as a driving source for generating a propulsion force for propelling the hull. In this embodiment, the engine 101 of the internal combustion engine system 100 can also be used as a driving source for driving a generator that generates electrical energy (electricity) used in the hull. That is, the engine 101 of the internal combustion engine system 100 is used as a driving source for generating propulsion force for the hull or for driving the generator of the hull. The electrical energy generated by the generator can be stored in the power storage device.

[0041] A ship is a mobile object that travels (sails) on water, such as oceans, lakes, or rivers. In this embodiment, as an example, the ship is a vessel, such as an ocean liner, that travels long distances after a single refueling. The ship's hull has a propeller. The propeller is connected to the engine 101 of the internal combustion engine system 100 via a propeller shaft. The ship receives power generated by the engine 101, which rotates the propeller about the propeller shaft, thereby generating propulsion force to move the ship forward or backward.

[0042] Furthermore, in this embodiment, the vessel is configured to operate based on human (operator) control (including remote control), and is specifically designed to be manned and capable of being operated by a human operator. Therefore, the vessel includes an operating panel on the hull for receiving the operator's operations. The operation of the operating panel drives the engine 101 of the internal combustion engine system 100. Thus, the vessel can drive the engine 101 based on the operator's operations, rotating the propeller and moving the vessel forward or backward. The vessel also includes various onboard equipment, including a rudder mechanism, a display device, a communication device, and lighting.

[0043] However, the engine 101 involved in the present embodiment is an engine that uses at least hydrogen as a fuel or an oxidant. That is, with respect to the internal combustion engine system 100, the hydrogen stored in the hydrogen container 102 is supplied to the engine 101 by the hydrogen fuel supply device 103 to drive the engine 101. In particular, in the present embodiment, with respect to the engine 101, a mixed combustion engine that burns a gas mixed with hydrogen (H2) and ammonia (NH3) is described as an example of the engine 101. Furthermore, the engine 101 is set as a lean burn engine that burns on a side leaner than the theoretical air-fuel ratio (excess air). Therefore, with respect to the internal combustion engine system 100 involved in the present embodiment, ammonia stored in the ammonia container 104 is supplied to the engine 101 by the ammonia fuel supply device 105. Thus, hydrogen and ammonia are supplied to the engine 101, and the engine 101 is driven by using hydrogen and ammonia as fuel.

[0044] This engine 101 is a kind of ammonia engine with ammonia as main fuel, and has the advantage that the emission of carbon dioxide can be suppressed to be less compared with the engine with fossil fuel (light oil or gasoline, etc.) as main fuel. Moreover, about this engine 101, both sides of hydrogen and ammonia are used as fuel (or combustion-supporting agent), therefore, hydrogen can be utilized to make up for the weakness of ammonia that is difficult to ignite and burn. That is, by utilizing the mixed gas of ammonia and hydrogen, compared with the situation that ammonia is set as fuel and only ammonia is set as fuel, engine 101 is easy to improve combustibility and is easy to use in a relatively large operating area (load area). In addition, compared with the situation that only hydrogen is set as fuel, this engine 101 is easy to appropriately control combustion efficiency, therefore, it is easy to suppress the generation of abnormal combustion and it is easy to achieve high output.

[0045] Here, in the internal combustion engine system 100 according to the present embodiment, hydrogen obtained by decomposing ammonia is supplied to the engine 101 as fuel (or combustion aid). Therefore, an ammonia decomposition unit 108 is used to decompose ammonia. The ammonia decomposition unit 108 decomposes ammonia to obtain hydrogen and nitrogen. That is, when ammonia (NH3) is supplied to the ammonia decomposition unit 108, hydrogen (H2) and nitrogen (N2) as well as residual ammonia (NH3) that remains undecomposed are output from the ammonia decomposition unit 108. In this way, the internal combustion engine system 100 according to the present embodiment includes the ammonia decomposition unit 108 and the engine 101. The engine 101 is driven by receiving the supply of gas (hydrogen) output from the ammonia decomposition unit 108.

[0046] Specifically, the internal combustion engine system 100 includes an ammonia decomposition unit 108, a vaporizer 106, and a compressor 107 in addition to an engine 101, a hydrogen tank 102, a hydrogen fuel supply device 103, an ammonia tank 104, and an ammonia fuel supply device 105. The ammonia tank 104 stores liquid ammonia (liquefied ammonia). The vaporizer 106 vaporizes the liquefied ammonia in the ammonia tank 104 and supplies the ammonia, which is a gas (gas), to the ammonia decomposition unit 108. The ammonia decomposition unit 108 outputs the gas (hydrogen) obtained by decomposing the ammonia to the hydrogen tank 102. Thus, the hydrogen supplied to the engine 101 as fuel is generated from ammonia in the ammonia decomposition unit 108 and (temporarily) stored in the hydrogen tank 102. The compressor 107 compresses air (atmosphere) drawn in from the surroundings of the internal combustion engine system 100 and supplies the compressed air and fuel (hydrogen and ammonia) to the engine 101.

[0047] According to the internal combustion engine system 100 of the above structure, hydrogen as fuel for the engine 101 can be supplied effectively and safely. That is, ammonia has a higher volume energy density than hydrogen, for example, and can be liquefied under milder conditions. Therefore, with respect to the internal combustion engine system 100, the ammonia stored in the ammonia container 104 is decomposed by the ammonia decomposition unit 108 each time to obtain hydrogen as fuel, thereby achieving an increase in the volume energy density of the stored material compared to the case where hydrogen as fuel is stored in the form of compressed gas or liquid. Therefore, if the capacity of the container (ammonia container 104) is the same, more fuel can be stored, and if the same amount of fuel (hydrogen) is stored, a smaller container (ammonia container 104) is sufficient. In this way, hydrogen as fuel can be supplied effectively (with a smaller container) and safely, which is particularly useful for ships such as ocean liners that sail long distances after refueling once.

[0048] As described above, in the internal combustion engine system 100 according to the present embodiment, the engine 101 uses hydrogen obtained by the ammonia decomposition unit 108 as at least a portion of the fuel. This allows hydrogen to be supplied efficiently and safely as fuel to the engine 101.

[0049] Furthermore, the engine 101 uses the hydrogen and ammonia obtained by the ammonia decomposition unit 108 as fuel. This allows for lower carbon dioxide emissions compared to engines using fossil fuels (such as light oil or gasoline) as their primary fuel. Furthermore, by using ammonia and hydrogen as fuel, the engine 101 can more easily improve its combustibility and operate over a wider operating range (load range) than when using only ammonia as fuel. Furthermore, compared to when using only hydrogen as fuel, it is easier to suppress abnormal combustion and achieve higher output.

[0050] Furthermore, in this embodiment, ammonia serving as fuel for engine 101 and ammonia decomposed by ammonia decomposition unit 108 are stored together in a common container (ammonia container 104). Specifically, ammonia stored in a single ammonia container 104 is supplied as fuel to engine 101 via ammonia fuel supply device 105, while ammonia is supplied to ammonia decomposition unit 108 for decomposition by vaporizer 106. Therefore, while both hydrogen and ammonia are used as fuel for engine 101, both fuels can be stored in a single container (ammonia container 104), making the container more compact and simplifying refilling.

[0051] However, the internal combustion engine system 100 according to the present embodiment further includes a nitrous oxide purification system 10 in addition to the engine 101, the hydrogen tank 102, the hydrogen fuel supply device 103, the ammonia tank 104, the ammonia fuel supply device 105, the ammonia decomposition unit 108, the vaporizer 106, and the compressor 107. That is, the internal combustion engine system 100 includes the nitrous oxide purification system 10 and the engine 101. The nitrous oxide purification system 10 is arranged in an exhaust gas path 109 starting from the engine 101. The nitrous oxide purification system 10 takes in the exhaust gas from the engine 101, decomposes or reduces the nitrous oxide (N2O) in the exhaust gas, and purifies the nitrous oxide contained in the exhaust gas.

[0052] In a word, about the internal combustion engine system 100 involved in the present embodiment, engine 101 at least uses ammonia as fuel.Therefore, compared with the engine using fossil fuel (light oil or gasoline etc.) as main fuel, there is the advantage that the discharge of the carbon dioxide of engine 101 can be suppressed less.On the other hand, the exhaust gas discharged from engine 101 may contain nitrous oxide (laughing gas) as greenhouse gas. Known nitrous oxide has the greenhouse effect of roughly 265 times of carbon dioxide (CO2). About the ammonia engine using ammonia as main fuel, the purification of exhaust gas (nitrous oxide in) becomes a larger technical issue. About the internal combustion engine system 100 involved in the present embodiment, nitrous oxide purification system 10 is configured in the exhaust gas path 109 starting from this engine 101 and can realize the purification of exhaust gas.

[0053] [2] Definition

[0054] "Decomposition" as used herein is a type of chemical reaction, meaning chemical decomposition of a compound into monomeric components or simpler compounds, and is the opposite of chemical synthesis. Decomposition generally requires external energy supply, and there are various decompositions such as thermal decomposition, photodecomposition, electrodecomposition, or radiation decomposition, depending on the energy source. In this embodiment, as an example, a nitrous oxide purification system 10 utilizes a catalyst 11 to decompose nitrous oxide (N2O) into oxygen (O2) and nitrogen (N2).

[0055] "Reduction," as used herein, is a type of chemical reaction, meaning a chemical reaction in which a target substance receives electrons or a chemical reaction in which the oxidation number of an atom decreases. Specifically, this includes reactions that remove oxygen from a substance or reactions in which a substance combines with hydrogen, and is the opposite of oxidation. In this embodiment, as an example, the nitrous oxide purification system 10 utilizes a catalyst 11 to remove oxygen (O) from nitrous oxide (N2O) to produce nitrogen (N2).

[0056] In the present disclosure, the nitrous oxide purification system 10 that decomposes or reduces nitrous oxide only needs to decompose or reduce at least a portion of the supplied nitrous oxide, and is not limited to decomposing or reducing all of it. Nitrous oxide that remains undecomposed or unreduced despite being supplied to the nitrous oxide purification system 10 is also referred to as "residual nitrous oxide."

[0057] The "catalyst" mentioned in this disclosure is a substance that does not change in a chemical reaction such as decomposition but promotes the chemical reaction. Strictly speaking, the "catalyst" produces a certain interaction with the reaction, and sometimes the "catalyst" itself changes and changes the path of the reaction to promote the reaction. Moreover, the "catalyst" returns to its original state after the reaction, and as a result, the "catalyst" itself does not change and remains. In the present embodiment, as an example, the purification unit 1 of the nitrous oxide purification system 10 has a catalyst 11 that decomposes or reduces nitrous oxide, and the catalyst 11 is used to decompose or reduce nitrous oxide.

[0058] As used herein, the term "purification rate" refers to the ratio of the amount of a compound actually purified during the purification (decomposition or reduction) of a compound relative to the total amount of that compound. For the same amount of compound, a higher purification rate means a greater amount of the compound is purified, while a lower purification rate means a smaller amount of the purified product is purified. In this embodiment, as an example, percentages ranging from "0%" to "100%" represent the purification rates associated with the purification (decomposition or reduction) of nitrous oxide in the nitrous oxide purification system 10. For example, if the purification rate is "0%," all of the nitrous oxide supplied to the nitrous oxide purification system 10 is not purified, and all of it remains as residual nitrous oxide. Conversely, if the purification rate is "100%," all of the nitrous oxide supplied to the nitrous oxide purification system 10 is purified, and no residual nitrous oxide is generated. If the purification rate is "50%," half of the nitrous oxide supplied to the nitrous oxide purification system 10 is purified, and the remaining half remains as residual nitrous oxide.

[0059] [3] Structure of nitrous oxide purification system

[0060] Next, refer to Figure 2The structure of the nitrous oxide purification system 10 according to this embodiment will be described. Figure 2 It is a schematic diagram schematically showing the structure of the purification unit 1.

[0061] A catalyst composite for removing nitrous oxide (N2O) is known as a related technology. This technology comprises a catalyst material on a support, comprising a rhodium (Rh) component supported on a ceria-based carrier. Measurement of this catalyst composite by hydrogen temperature reduction (H2-TPR) reveals an H2 consumption peak below approximately 100°C.

[0062] However, the catalyst composites involved in the related art, for example, have difficulty achieving a sufficient decomposition or reduction effect on nitrous oxide in the exhaust gas from the engine 101 in a temperature range similar to the exhaust heat of the engine 101. Specifically, the exhaust gas from the engine 101 contains co-existing gases such as O2 and / or H2O in amounts on the order of percentage relative to the nitrous oxide. Thus, the nitrous oxide purification performance in the presence of co-existing gases such as O2 and / or H2O decreases due to the influence of these co-existing gases. In particular, achieving a sufficient decomposition or reduction effect may be difficult in the low-temperature range of the exhaust heat of the engine 101.

[0063] Therefore, the nitrous oxide purification system 10 according to the present embodiment adopts the configuration described below in order to easily obtain the effect of sufficient decomposition or reduction of nitrous oxide.

[0064] That is, the nitrous oxide purification system 10 involved in this embodiment includes an intake unit 14 and a purification unit 1. The intake unit 14 takes in nitrous oxide in a state where O2 and / or H2O coexist. The purification unit 1 decomposes or reduces the nitrous oxide taken in by the intake unit 14. In other words, the intake unit 14 takes in a gas in a state where nitrous oxide and O2 and / or H2O coexist. The purification unit 1 decomposes or reduces the nitrous oxide in the gas taken in by the intake unit 14. That is, the nitrous oxide purification system 10 uses the purification unit 1 to purify (decompose or reduce) the nitrous oxide in a state where O2 and / or H2O coexist, which is supplied from the outside (exhaust gas path 109) to the intake unit 14. In this embodiment, as an example, the purification unit 1 decomposes nitrous oxide into nitrogen and other gases. That is, the nitrous oxide purification system 10 decomposes nitrous oxide and purifies it.

[0065] According to the above-described configuration, even in a situation where a percentage of O2 and / or H2O coexists with nitrous oxide, such as in the exhaust gas from engine 101, the purification unit 1 can decompose or reduce nitrous oxide by taking into account the influence of the coexisting gases. Therefore, the nitrous oxide purification system 10 has the advantage of easily achieving a sufficient decomposition or reduction effect of nitrous oxide.

[0066] In short, the nitrous oxide purified by the nitrous oxide purification system 10 is supplied to the nitrous oxide purification system 10 in the form of a mixed gas mixed with O2 and / or H2O. Here, the proportion of O2 and / or H2O in the mixed gas is 1% (volume percentage) or more. Even in this mixed gas state, the nitrous oxide purification system 10 can fully purify (decompose or reduce) the nitrous oxide.

[0067] In addition, regarding the nitrous oxide purification system 10 involved in this embodiment, as shown in FIG. Figure 2 As shown, the purification unit 1 has a catalyst 11 that decomposes or reduces nitrous oxide. Furthermore, the purification unit 1 has electrodes 12 and 13 that apply an electric field to the catalyst 11. In summary, in this embodiment, the purification unit 1 has, for example, a pair of electrodes 12 and 13 arranged so as to sandwich the catalyst 11, and an electric field (electric field) is applied to the catalyst 11 from the pair of electrodes 12 and 13. As a result, compared to a case where an electric field is not applied to the catalyst 11, particularly in an environment where coexisting gases of O2 and / or H2O are present, and in an environment where the temperature of the catalyst 11 is low, the purification (decomposition or reduction) of nitrous oxide can be promoted by the catalyst 11.

[0068] Specifically, if Figure 2 As shown, the nitrous oxide purification system 10 includes a purification unit 1 including a catalyst 11 and electrodes 12 and 13, and an intake unit 14, and further includes a power supply unit 3. The power supply unit 3 is electrically connected to the pair of electrodes 12 and 13 of the purification unit 1 and applies a DC voltage between the pair of electrodes 12 and 13. The DC voltage is applied between the pair of electrodes 12 and 13 from the power supply unit 3, and an electric field is applied to the catalyst 11 from the pair of electrodes 12 and 13. The power supply unit 3 generates a DC voltage of, for example, several hundred volts and applies the voltage between the pair of electrodes 12 and 13.

[0069] In the present embodiment, as an example, the power supply device 3 sets the electrode 12 as the negative electrode and the electrode 13 as the positive electrode and applies a DC voltage between the pair of electrodes 12 and 13. Thus, the power supply device 3 applies a DC voltage between the pair of electrodes 12 and 13 so that the electrode 12 is at the low potential side and the electrode 13 is at the high potential side. Here, the power supply device 3 sets the electrode 13 at the positive electrode side as the reference potential point (ground electrode) and applies a negative voltage between the pair of electrodes 12 and 13. However, it is not limited to this structure, as long as an electric field is applied to the catalyst 11, therefore, the power supply device 3 may also, for example, set the electrode 12 on the low potential side as the ground electrode and the electrode 13 on the high potential side as the positive potential, thereby applying a positive voltage between the pair of electrodes 12 and 13.

[0070] In more detail, Figure 2 As shown, the purification unit 1 includes, in addition to the catalyst 11 and the pair of electrodes 12 and 13 , an exhaust port 15 , a cylindrical body 16 , a catalyst fixed layer 17 , a mesh 18 , and a temperature sensor 19 .

[0071] Intake portion 14 communicates with an opening of purification unit 1, through which gas (nitrous oxide) purified in purification unit 1 is introduced. Exhaust port 15 is an opening through which gas obtained by purifying nitrous oxide in purification unit 1 is discharged. Tubular body 16 is formed, for example, in a cylindrical shape and accommodates at least catalyst 11.

[0072] The intake portion 14 is provided at one end of the cylindrical body 16 in the longitudinal direction, and the discharge port 15 is provided at the other end of the cylindrical body 16 in the longitudinal direction. Thus, the gas introduced from the intake portion 14 can pass through the cylindrical body 16 and be discharged from the discharge port 15. Furthermore, the gas (nitrous oxide) is purified by the catalyst 11 housed in the cylindrical body 16, and thus is purified (decomposed or reduced) as it passes through the cylindrical body 16.

[0073] The catalyst fixed layer 17 and the mesh 18 are housed in the cylindrical body 16. The catalyst 11 is stacked on the catalyst fixed layer 17 with the mesh 18 interposed therebetween. Here, the pair of electrodes 12 and 13 are rod-shaped electrodes, inserted into the catalyst 11 from both ends of the cylindrical body 16 in the longitudinal direction. Furthermore, as an example, the temperature sensor 19 is a thermocouple, inserted into the catalyst from the other end of the cylindrical body 16 in the longitudinal direction, to measure the temperature of the reaction field (catalyst temperature) in real time. The catalyst temperature measured by the temperature sensor 19 is output to the control unit 2.

[0074] In this embodiment, an inert gas (for example, argon) is introduced into the purification unit 1 in addition to the coexisting gas composed of O2 and / or H2O. Figure 2As shown, nitrous oxide (N2O), oxygen (O2), H2O and argon (Ar) are introduced from the intake portion 14, the nitrous oxide is decomposed or reduced by the catalyst 11 of the purification portion 1, and nitrogen (N2), NO x , (residual) nitrous oxide (N2O) and argon (Ar) are discharged. However, inert gas is not essential for the purification of nitrous oxide.

[0075] In addition, in this embodiment, a reducing agent is introduced into the purification unit 1 together with nitrous oxide. The "reducing agent" mentioned here is a substance that has the effect of reducing nitrous oxide by reacting with nitrous oxide, and as an example, it is hydrogen (H2) and ammonia (NH3). Therefore, if Figure 2 As shown, hydrogen (H2) and ammonia (NH3) are introduced in addition to nitrous oxide (N2O), oxygen (O2), H2O, and argon (Ar) from the intake portion 14. However, a reducing agent is not essential for the purification of nitrous oxide.

[0076] As described above, the purification unit 1 of the nitrous oxide purification system 10 is a structure that applies an electric field (electric field) to the catalyst 11 from (a pair of) electrodes 12 and 13. Therefore, in particular, even in an environment where there is a co-existing gas of O2 and / or H2O, and in an environment where the temperature of the catalyst 11 is relatively low, it is possible to promote the purification of nitrous oxide by the catalyst 11. In particular, in an environment where the heat exhausted from the engine 101 of the internal combustion engine system 100 is insufficient, it is sometimes difficult to sufficiently increase the temperature of the catalyst 11 only by the temperature of the exhaust gas, and sometimes it is impossible to fully exert the purification performance of nitrous oxide by the catalyst 11. In contrast, as in the present embodiment, regarding a structure that can promote the purification of nitrous oxide by the catalyst 11 even in a low temperature region by applying an electric field to the catalyst 11, there is no need to raise the temperature of the catalyst 11 to such an extent, and the purification performance of nitrous oxide by the catalyst 11 can be fully exerted.

[0077] In addition, the nitrous oxide purification system 10 involved in this embodiment further includes a control unit 2. The control unit 2 controls the purification rate of the nitrous oxide used by the purification unit 1. That is, with respect to the nitrous oxide purification system 10 involved in this embodiment, the purification rate of the nitrous oxide in the purification unit 1 is not fixed and can be controlled (regulated) by the control unit 2. The control unit 2, for example, changes the purification rate of the nitrous oxide (nitrous oxide purification rate) within a variable range of "0%" or more and "100%" or less. If the control unit 2 controls the purification rate to "0%", the nitrous oxide is not purified (decomposed or reduced) by the purification unit 1 at all. On the contrary, if the control unit 2 controls the purification rate to "100%", the nitrous oxide is completely decomposed by the purification unit 1.

[0078] With this configuration, the nitrous oxide purification system 10 according to this embodiment can vary the purification rate of nitrous oxide in the purification unit 1 . Therefore, for example, nitrous oxide can be purified at a minimum required purification rate depending on the state of the exhaust gas from the engine 101 .

[0079] In addition, the nitrous oxide purification system 10 involved in this embodiment is also provided with a heating unit 4 for heating the catalyst 11. The heating unit 4 makes the temperature of the catalyst 11 range from 50°C to 600°C. That is, in order to improve the purification rate of nitrous oxide by the catalyst 11, the heating unit 4 heats the catalyst 11 in a manner that makes the temperature of the catalyst 11 range from 50°C to 600°C. The heating unit 4 can indirectly heat the catalyst 11 by heating the nitrous oxide supplied from the exhaust gas path 109 to the nitrous oxide purification system 10, or can directly heat the catalyst 11 by using a heater or the like. Moreover, in this embodiment, an electric field is applied to the catalyst 11 in the above-mentioned manner. Therefore, as the heating unit 4, even if the catalyst 11 is not heated to a high temperature of 300°C or more, for example, the decomposition of nitrous oxide by the catalyst 11 can be fully achieved.

[0080] However, the lower limit of the temperature of the catalyst 11 heated by the heating unit 4 is not limited to 50°C. For example, it may be less than 50°C, and may be 100°C, 150°C, 200°C, 250°C, or 300°C. Similarly, the upper limit of the temperature of the catalyst 11 heated by the heating unit 4 is not limited to 600°C. For example, it may be a temperature higher than 600°C, and may be 350°C, 400°C, 450°C, 500°C, or 550°C. As an example, it is more preferable that the heating unit 4 heats the catalyst 11 so that the temperature of the catalyst 11 is within the range of 100°C to 400°C.

[0081] Furthermore, in this embodiment, the purification unit 1 is heated using exhaust heat from the engine 101. Specifically, the exhaust gas from the engine 101 is already high in temperature (e.g., approximately 350°C) due to the exhaust heat from the engine 101. Therefore, this exhaust gas is taken into the purification unit 1 and heated using the exhaust heat from the engine 101. Therefore, the heating unit 4 can heat at least the catalyst 11 using the exhaust heat from the engine 101.

[0082] In this way, the heat exhausted by the engine 101 is effectively utilized, and the energy required to heat the catalyst 11 in the heating unit 4 can be suppressed to a low level. In particular, when the catalyst 11 is used in a low temperature range of 300°C or less, the catalyst 11 can be fully heated solely by the heat exhausted by the engine 101. Therefore, there is no need to provide a separate heating device, and the nitrous oxide purification system 10 can be easily miniaturized and simplified.

[0083] However, the nitrous oxide purification system 10 according to the present embodiment can control (adjust) the nitrous oxide purification rate (nitrous oxide purification rate) of the purification unit 1 using the control unit 2 in the above-described manner. Here, the control unit 2 changes the nitrous oxide purification rate of the purification unit 1 by changing at least one of the temperature of the catalyst 11, the current value flowing through the catalyst 11, the amount of reducing agent input, and the space velocity.

[0084] The "space velocity" referred to here is SV (Space Velocity), which refers to the relationship between the volume of the reactor and the feed rate of the raw materials. Specifically, it is the value obtained by dividing the capacity (volume) of the catalyst 11 by the flow rate of nitrous oxide passing through the catalyst 11. In other words, if the flow rate of nitrous oxide is constant, the larger the size of the catalyst 11, the lower the space velocity.

[0085] In short, the nitrous oxide purification rate is changed by changing at least one of the four parameters: the temperature of the catalyst 11, the current flowing through the catalyst 11, the amount of reducing agent added, and the space velocity. In this embodiment, as an example, the control unit 2 is configured to be able to control all of the temperature of the catalyst 11, the current flowing through the catalyst 11, the amount of reducing agent added, and the space velocity.

[0086] For example, the control unit 2 changes the (nitrous oxide) purification rate at least according to the current value, such that the larger the current value flowing through the catalyst 11, the higher the (nitrous oxide) purification rate. Specifically, the control unit 2 is configured to control the power supply device 3, and controls the magnitude (current value) of the current flowing through the catalyst 11 by controlling the magnitude (current value) of the current supplied from the power supply device 3 to the purification unit 1 (between a pair of electrodes 12 and 13). That is, the output current of the power supply device 3 is not constant, but variable, and its current value is controlled by the control unit 2. The control unit 2 can change the current value flowing through the catalyst 11 continuously or in stages (discontinuously).

[0087] Moreover, basically, if the output current of the power supply device 3 increases, the current value flowing through the catalyst 11 increases, the nitrous oxide purification rate improves, and therefore, the purification rate of the exhaust gas from the engine 101 improves. Conversely, if the output current of the power supply device 3 decreases, the current value flowing through the catalyst 11 decreases, the nitrous oxide purification rate decreases, and therefore, the purification rate of the exhaust gas from the engine 101 decreases. Thus, the nitrous oxide purification rate can be controlled (regulated) with a relatively simple structure, and the nitrous oxide purification rate has a high responsiveness to changes in the current value, so the control unit 2 can easily control the nitrous oxide purification rate in real time.

[0088] Furthermore, the control unit 2 varies the (nitrous oxide) purification rate at least according to the temperature of the catalyst 11, such that the higher the temperature (higher temperature) of the catalyst 11, the higher the (nitrous oxide) purification rate. Specifically, the control unit 2 is configured to control the heating unit 4, and controls the temperature of the catalyst 11 by controlling the amount of thermal energy applied from the heating unit 4 to the catalyst 11. That is, the output of the heating unit 4 is not constant but variable, and its output (thermal energy) is controlled by the control unit 2. The control unit 2 can vary the temperature of the catalyst 11 continuously or in stages (discontinuously).

[0089] Furthermore, basically, if the temperature of the catalyst 11 increases, the nitrous oxide purification rate increases, thereby increasing the purification rate of the exhaust gas from the engine 101. Conversely, if the temperature of the catalyst 11 decreases, the nitrous oxide purification rate decreases, thereby decreasing the purification rate of the exhaust gas from the engine 101. Thus, the nitrous oxide purification rate can be controlled (adjusted) with a relatively simple structure. Moreover, the nitrous oxide purification rate has high responsiveness to changes in the temperature of the catalyst 11, making it easy for the control unit 2 to control the nitrous oxide purification rate in real time.

[0090] In addition, the control unit 2 changes the purification rate (of nitrous oxide) at least according to the space velocity of nitrous oxide passing through the catalyst 11, in such a manner that the smaller the space velocity of nitrous oxide passing through the catalyst 11, the higher the purification rate (of nitrous oxide). Specifically, the control unit 2 is configured to control the flow rate (flow velocity) of nitrous oxide supplied to the purification unit 1, and controls the space velocity of nitrous oxide passing through the catalyst 11 by controlling the flow rate of nitrous oxide supplied to the purification unit 1. That is, the flow rate (flow velocity) of nitrous oxide passing through the catalyst 11 is not constant but variable, and its value (flow rate) is controlled by the control unit 2. The control unit 2 can continuously change the flow rate of nitrous oxide passing through the catalyst 11, or can change it in stages (discontinuously).

[0091] Moreover, basically, if the flow rate of the nitrous oxide passing through the catalyst 11 decreases, the space velocity decreases and the nitrous oxide purification rate increases, so the purification rate of the exhaust gas from the engine 101 increases. On the contrary, if the flow rate of the nitrous oxide passing through the catalyst 11 increases, the space velocity increases and the nitrous oxide purification rate decreases, so the purification rate of the exhaust gas from the engine 101 decreases. Thus, the nitrous oxide purification rate can be controlled (regulated) with a relatively simple structure, and the responsiveness of the nitrous oxide purification rate to the flow rate of the nitrous oxide passing through the catalyst 11 is high, so it is easy for the control unit 2 to control the nitrous oxide purification rate in real time.

[0092] Alternatively, the control unit 2 may control the space velocity of the nitrous oxide passing through the catalyst 11 based on the flow rate (flow velocity) of the nitrous oxide or alternatively based on the size (volume) of the catalyst 11 through which the nitrous oxide passes. That is, basically, if the size of the catalyst 11 through which the nitrous oxide passes increases, the space velocity decreases and the nitrous oxide purification rate increases, thereby improving the purification rate of the exhaust gas from the engine 101. Conversely, if the size of the catalyst 11 through which the nitrous oxide passes decreases, the space velocity increases and the nitrous oxide purification rate decreases, thereby reducing the purification rate of the exhaust gas from the engine 101.

[0093] Furthermore, the control unit 2 varies the (nitrous oxide) purification rate at least in accordance with the amount of reducing agent fed, such that the purification rate increases as the amount of reducing agent fed increases. Specifically, the control unit 2 is configured to control the amount of reducing agent (e.g., hydrogen and ammonia) fed into the purification unit 1, thereby controlling the amount of reducing agent fed. The control unit 2 may vary the amount of reducing agent fed continuously or in stages (discontinuously).

[0094] Furthermore, basically, if the reducing agent input amount increases, the nitrous oxide purification rate increases, thereby improving the purification rate of the exhaust gas from the engine 101. Conversely, if the reducing agent input amount decreases, the nitrous oxide purification rate decreases, thereby reducing the purification rate of the exhaust gas from the engine 101. Thus, the nitrous oxide purification rate can be controlled (adjusted) with a relatively simple structure. Moreover, the nitrous oxide purification rate is highly responsive to changes in the reducing agent input amount, making it easy for the control unit 2 to control the nitrous oxide purification rate in real time.

[0095] Here, catalyst 11 comprises an active metal and a catalyst support. The active metal is at least one of rhodium (Rh), palladium (Pd), platinum (Pt), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), tungsten (W), and vanadium (V), and the catalyst support contains, as a main component, one of cerium (Ce), zirconium (Zr), yttrium (Y), lanthanum (La), neodymium (Nd), and praseodymium (Pr). Specifically, catalyst 11 comprises a catalyst support composed of an active metal such as rhodium and an oxide such as cerium.

[0096] More specifically, in this embodiment, the oxides used as catalyst supports are CeO2, Ce x Zr (1-x) Here, "x" is any value in the range of "0" or more and "1" or less (ie, "0≤x≤1"). For example, if Ce x Zr (1-x) O2, for example, includes Ce 0.5 Zr 0.5 O2, etc.

[0097] According to the nitrous oxide purification system 10 of the above structure, a nitrous oxide purification method is embodied, which includes the steps of taking nitrous oxide in the coexistence of O2 and / or H2O, and the steps of decomposing or reducing the taken nitrous oxide (in the coexistence of O2 and / or H2O). This nitrous oxide purification method can be embodied without using the nitrous oxide purification system 10.

[0098] [4] Actual value

[0099] Hereinafter, regarding the nitrous oxide purification system 10 according to this embodiment, refer to Figures 3 to 19 The following describes actual values ​​of the nitrous oxide purification rate when the temperature of the catalyst 11, the current flowing through the catalyst 11, the amount of reducing agent added, or the space velocity (the flow rate of nitrous oxide passing through the catalyst 11 or the amount of the catalyst 11) are varied. Furthermore, the nitrous oxide purification rate also varies depending on the material (components) of the catalyst 11, and therefore, the following also describes actual values ​​of the nitrous oxide purification rate when the material of the catalyst 11, etc., is varied. Figures 3 to 19 This is a graph showing an example of various parameters such as the temperature of the catalyst 11 and actual values ​​of the nitrous oxide purification rate (nitrous oxide purification rate) on the horizontal axis and the vertical axis.

[0100] Figure 3 This is a graph showing the actual value of the purification rate of nitrous oxide when the temperature (horizontal axis) of the catalyst 11 is changed. Figure 3 The test conditions, other than the temperature of catalyst 11, were as follows: the current flowing through catalyst 11 (in the "electric field" condition) was 3 mA, the amount of catalyst 11 was 356 mg, the flow rate of nitrous oxide was 200 mL / min, and the reaction pressure was atmospheric pressure. Furthermore, the composition of the gas used to activate catalyst 11 was 1000 ppm of nitrous oxide (N2O), 10% of oxygen (O2), and a balance of argon (Ar). Figure 3 The left side shows the case where the material of catalyst 11 is "5wt% Rh / CeO2". Figure 3 The right side of FIG shows the case where the material of catalyst 11 is "5 wt% Cu / CeO2". Figure 3 In FIG. 1 , data D1 represents “with electric field” data in which an electric field is applied to the catalyst 11 , and data D2 represents “without electric field” data in which no electric field is applied to the catalyst 11 .

[0101] according to Figure 3It is clear that when the material of the catalyst 11 is "5wt% Rh / CeO2", the following trend is shown: as the temperature of the catalyst 11 increases, the nitrous oxide purification rate increases. Moreover, in the range where the temperature of the catalyst 11 is "300°C" or less, the effect of promoting the purification (decomposition or reduction) of nitrous oxide and improving the nitrous oxide purification rate becomes significant when the "electric field" is used compared to when the "electric field is not used". For example, in the low temperature region where the temperature of the catalyst 11 is "200°C", the nitrous oxide purification rate is approximately "20%" when there is "no electric field". In contrast, the nitrous oxide purification rate is close to "100%" when there is an electric field. In addition, even when inexpensive copper (Cu) is used as the active metal of the catalyst 11, it is confirmed that the effect of the electric field can be reflected.

[0102] Figure 4 This is a graph showing actual values ​​of the purification rate of nitrous oxide when the material (component) of the catalyst 11 is changed. Figure 4 The test conditions, other than the temperature of catalyst 11, were as follows: the current flowing through catalyst 11 (in the presence of an electric field) was 6 mA, the amount of catalyst 11 was 200 mg, the flow rate of nitrous oxide was 100 mL / min, and the reaction pressure was atmospheric pressure. Furthermore, the composition of the gas used to activate catalyst 11 was 1000 ppm of nitrous oxide (N2O), 10% of oxygen (O2), and a balance of argon (Ar). Figure 4 The left side of represents the data of "with electric field", Figure 4 The right side of shows the data for “no electric field”. Figure 4 , the loading amount of catalyst 11 is "5wt%", the catalyst carrier is "CeO2", data D1 represents the data when the active metal is Rh, data D2 represents the data when the active metal is Pd, data D3 represents the data when the active metal is Pt, data D4 represents the data when the active metal is Fe, data D5 represents the data when the active metal is Ni, and data D6 represents the data when the active metal is Cu.

[0103] according to Figure 4 It is clear that the sensitivity of the nitrous oxide purification promotion to temperature varies depending on the material (active metal) of the catalyst 11. Regarding the active metal of the catalyst 11, precious metals (Rh, Pd, Pt) have a higher purification rate than base metals (Fe, Cu, Ni).

[0104] Figure 5 This is a graph showing actual values ​​of the purification rate of nitrous oxide when the material (component) of the catalyst 11 is changed. Figure 5The test conditions, other than the temperature of catalyst 11, were as follows: the current flowing through catalyst 11 was 6 mA, the amount of catalyst 11 was 200 mg, the flow rate of nitrous oxide was 100 mL / min, and the reaction pressure was atmospheric pressure. Furthermore, the composition of the gas used to activate catalyst 11 was 1000 ppm of nitrous oxide (N2O), 10% of oxygen (O2), and a balance of argon (Ar). Figure 5 The left side shows data when the temperature of the catalyst 11 is changed. Figure 5 The right side of shows the result of selecting the data when the temperature of the catalyst 11 is "150° C." and arranging the values ​​of x of the catalyst carrier of the catalyst 11 in a bar graph. Figure 5 In the figure, the loading amount of catalyst 11 is "5 wt %", the active metal is "Rh", and the catalyst carrier "Ce (1-x) Zr x The data D1 when “x” of O2” is “0”, the data D2 when it is “0.1”, the data D3 when it is “0.2”, the data D4 when it is “0.3”, the data D5 when it is “0.4”, and the data D6 when it is “0.5”.

[0105] according to Figure 5 It is clear that the sensitivity of the nitrous oxide purification promotion to temperature varies depending on the material (catalyst carrier) of the catalyst 11. Regarding the catalyst carrier of the catalyst 11, the purification rate is more excellent when zirconium (Zr) is mixed.

[0106] Figure 6 This is a graph showing actual values ​​of the purification rate of nitrous oxide when the material (component) of the catalyst 11 is changed. Figure 6 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "6 mA", the amount of the catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that makes the catalyst 11 work is set to "nitrous oxide (N2O): 1000 ppm, oxygen (O2): 10%, argon (Ar): balance". Figure 6 The loading amount of catalyst 11 is "5wt%", and the catalyst carrier is "Ce 0.7 Zr 0.3 O2", the left side shows the data when the active metal is Co, and the right side shows the data when the active metal is Cu. Figure 6 In FIG, data D1 represents data of “with electric field”, and data D2 represents data of “without electric field”.

[0107] according to Figure 6It is clear that the sensitivity of the promotion of nitrous oxide purification to temperature varies depending on the material (active metal) of the catalyst 11 .

[0108] Figure 7 This is a graph showing actual values ​​of the purification rate of nitrous oxide when the material (component) of the catalyst 11 is changed. Figure 7 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "6 mA", the amount of the catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that makes the catalyst 11 work is set to "nitrous oxide (N2O): 1000 ppm, oxygen (O2): 10%, argon (Ar): balance". Figure 7 In the data, data D1 represents data obtained when an electric field was applied to catalyst 11 composed of 5 wt% Cu / CeO2, and data D2 represents data obtained when an electric field was not applied to catalyst 11. Furthermore, data D3 represents data obtained when an electric field was applied to catalyst 11 composed of CeO2, and data D4 represents data obtained when an electric field was not applied to catalyst 11.

[0109] according to Figure 7 It is clear that applying an electric field can purify nitrous oxide even in the absence of an active metal, but the purification rate is lower than in the presence of an active metal.

[0110] Figure 8 This is a graph showing actual values ​​of the nitrous oxide purification rate when the composition of the gas on which the catalyst 11 is activated is changed. Figure 8 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (under the condition of "with electric field") is "6 mA", and the material of the catalyst 11 is "5 wt% Rh / Ce 0.7 Zr 0.3 O2", the amount of catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that enables the catalyst 11 to work is set to "nitrous oxide (N2O): 1000 ppm, argon (Ar): balance". Figure 8 The left side of represents the data of "with electric field", Figure 8 The right side of shows the data for “no electric field”. Figure 8In the data, data D1 shows data with "oxygen (O2): 10%" coexisting, data D2 shows data with "water (H2O): 10%" coexisting, data D3 shows data with "oxygen (O2): 10%" and "water (H2O): 10%" coexisting, and data D4 shows data with no coexisting gas (nitrous oxide only). Data D4 shows only the case of "no electric field."

[0111] according to Figure 8 It is clear that the nitrous oxide purification rate decreases particularly due to the coexistence of water (H 2 O). Even so, nitrous oxide purification can be performed in a low temperature range of 300° C. or lower by applying an electric field to the catalyst 11 .

[0112] Figure 9 This is a graph showing actual values ​​of the nitrous oxide purification rate when the composition of the gas on which the catalyst 11 is activated is changed. Figure 9 The test conditions are as follows: the temperature of catalyst 11 is 160°C, the current flowing through catalyst 11 is 6 mA, and the material of catalyst 11 is 5 wt% Rh / Ce 0.7 Zr 0.3 O2", the amount of catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the data are shown when the composition of the gas that makes the catalyst 11 work is based on "nitrous oxide (N2O): 1000 ppm, oxygen (O2): 10%, argon (Ar): balance" and "water (H2O): 10%" is set to ON / OFF. That is, in Figure 9 During the "OFF" period, the gas that causes the catalyst 11 to function does not contain "water (H2O: 10%), and during the "ON" period, the gas that causes the catalyst 11 to function contains "water (H2O: 10%)".

[0113] according to Figure 9 It is clear that the nitrous oxide purification rate decreases due to the coexistence of water (H2O), but the nitrous oxide purification rate recovers when the coexistence of water (H2O) stops. Therefore, it can be inferred that the catalyst 11 itself is not damaged, and the performance is temporarily reduced due to the adsorption of H2O at the reaction sites of nitrous oxide.

[0114] Figure 10 This is a graph showing actual values ​​of the nitrous oxide purification rate when the composition of the gas on which the catalyst 11 is activated is changed. Figure 10 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "6 mA", and the material of the catalyst 11 is "5 wt% Rh / Ce 0.7 Zr0.3 O2", the amount of catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that makes the catalyst 11 work is set to "nitrous oxide (N2O): 1000 ppm, oxygen (O2): 10%, water (H2O): 10%, carbon dioxide (CO2): 10%, nitric oxide (NO): 1000 ppm, argon (Ar): balance". Figure 10 In FIG, data D1 represents data of “with electric field”, and data D2 represents data of “without electric field”.

[0115] according to Figure 10 It is clear that even if it is close to the X By applying an electric field to the catalyst 11 under actual exhaust gas conditions such as , nitrous oxide can be purified in a low temperature range of 300° C. or lower.

[0116] Figure 11 This is a graph showing actual values ​​of the nitrous oxide purification rate when the space velocity of the gas that causes the catalyst 11 to function is changed. Figure 11 The test conditions are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "6 mA", the material of the catalyst 11 is "5wt% Cu / CeO2", the amount of the catalyst 11 is "200 mg", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that enables the catalyst 11 to function is set to "nitrous oxide (N2O): 1000 ppm, oxygen (O2): 10%, argon (Ar): balance". Here, the space velocity (SV) is changed by changing the flow rate of nitrous oxide in the range of "50 mL / min" to "200 mL / min". Figure 11 The left side shows the data when the temperature of the catalyst 11 is 120-135°C. Figure 11 The right side of shows the data when the temperature of the catalyst 11 is 400°C. Figure 11 In FIG, data D1 represents data of “with electric field”, and data D2 represents data of “without electric field”.

[0117] according to Figure 11 It is clear that by applying an electric field to the catalyst 11 , the reaction can be controlled according to the space velocity even in a low temperature region of about 130° C.

[0118] Figure 12 This is a graph showing the actual value of the purification rate of nitrous oxide when the current value flowing through the catalyst 11 is changed. Figure 12The test conditions other than the current value are as follows: the material of catalyst 11 is "5wt% Cu / CeO2", the amount of catalyst 11 is "200mg", the flow rate of nitrous oxide is "100mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that makes catalyst 11 work is set to "nitrous oxide (N2O): 1000ppm, oxygen (O2): 10%, argon (Ar): balance". Figure 12 , data when the temperature of the catalyst 11 is "103.3° C.", "129.3° C.", "141° C.", "156° C.", and "170.2° C." are shown.

[0119] according to Figure 12 It is clear that even in a low temperature region of about 130° C., increasing the current value flowing through the catalyst 11 improves the purification rate of nitrous oxide in the low temperature region.

[0120] Figure 13 This is a graph showing the actual value of the purification rate of nitrous oxide when the current value flowing through the catalyst 11 is changed. Figure 13 The test conditions other than the current value are that the material of catalyst 11 is "5wt% Rh / Ce 0.7 Zr 0.3 O2", the amount of catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that enables the catalyst 11 to work is set to "nitrous oxide (N2O): 1000 ppm, oxygen (O2): 10%, water (H2O): 10%, carbon dioxide (CO2): 10%, nitric oxide (NO): 1000 ppm, argon (Ar): balance".

[0121] according to Figure 13 It is clear that even if it is close to the X Under actual exhaust gas conditions such as those described above, by increasing the current value flowing through the catalyst 11, the purification rate of nitrous oxide in the low temperature region can also be improved.

[0122] Figure 14 This is a graph showing the actual value of the purification rate of nitrous oxide when using a reducing agent. Figure 14The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "3 mA", the material of the catalyst 11 is "5wt% Rh / CeO2", the amount of the catalyst 11 is "100-150 mg", the flow rate of nitrous oxide is "200 mL / min", and the reaction pressure is "atmospheric pressure". In addition, regarding the components of the gas that enables the catalyst 11 to function, when hydrogen (H2) is used as a reducing agent, it is set to "nitrous oxide (N2O): 1000 ppm, hydrogen (H2): 1000 ppm, argon (Ar): balance", and when ammonia (NH3) is used as a reducing agent, it is set to "nitrous oxide (N2O): 1500 ppm, ammonia (NH3): 1000 ppm, argon (Ar): balance". Figure 14 In the case where hydrogen (H2) is used as a reducing agent, data D1 indicates data with an electric field, and data D2 indicates data without an electric field. Figure 14 In the case where ammonia (NH 3 ) is used as the reducing agent, data D3 indicates data of “with electric field”, and data D4 indicates data of “without electric field”.

[0123] according to Figure 14 It is clear that by using "5wt% Rh / CeO2" as catalyst 11, the reduction reaction originally proceeds at a low temperature under the condition that oxygen (O2) or water (H2O) does not coexist, and the reactivity with ammonia (NH3) is slightly improved due to the electric field.

[0124] Figure 15 This is a graph showing the actual value of the purification rate of nitrous oxide when using a reducing agent. Figure 15 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "3mA", the material of the catalyst 11 is "5wt% Cu / CeO2", the amount of the catalyst 11 is "356mg", the flow rate of nitrous oxide is "200mL / min", and the reaction pressure is "atmospheric pressure". In addition, the components of the gas that enables the catalyst 11 to work are set to "nitrous oxide (N2O): 1500ppm, ammonia (NH3): 1000ppm, argon (Ar): balance". Figure 15 In the data D1, data D2 represents data with “electric field” and data D3 and D4 represent data with “electric field” and “no electric field” respectively for the second time.

[0125] according to Figure 15It is clear that even when copper (Cu) is used as the active metal of catalyst 11, the reduction reaction in the low-temperature region is significantly enhanced by the electric field under the condition that oxygen (O2) or water (H2O) does not coexist, and the effect based on the electric field is greater than when rhodium (Rh) is used as the active metal.

[0126] Figure 16 This is a graph showing the actual value of the purification rate of nitrous oxide when hydrogen (H2) is used as a reducing agent. Figure 16 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "3mA" or "6mA", the amount of the catalyst 11 is "100mg" or "200mg", the flow rate of nitrous oxide is "100mL / min" or "200mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that makes the catalyst 11 work is set to "nitrous oxide (N2O): 1000ppm, hydrogen (H2): 1000ppm, argon (Ar): balance". Figure 16 On the left side, the material of catalyst 11 is "5wt% Rh / CeO2", the space velocity (SV) is "170000h -1 In the case of ", data D1 represents data of "with electric field", and data D2 represents data of "without electric field". In addition, data D3 and D4 represent oxygen (O 2 ) Data of "with electric field" and "without electric field" when 10% of the two coexist. Figure 16 On the right side, the material of catalyst 11 is "1wt% Rh / CeO2" and the space velocity (SV) is "50000h -1 ", and when oxygen (O2) coexists at 10%, data D1 represents data of "with electric field", and data D2 represents data of "without electric field".

[0127] according to Figure 16 It is clear that the reduction reaction by the reducing agent (H2) is significantly reduced due to the coexistence of oxygen (O2), but the purification rate of nitrous oxide in the low temperature region can be sufficiently ensured by adjusting the space velocity, etc.

[0128] Figure 17 This is a graph showing the actual value of the purification rate of nitrous oxide when ammonia (NH3) is used as a reducing agent. Figure 17The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "3mA" or "6mA", the amount of the catalyst 11 is "100mg" or "200mg", the flow rate of nitrous oxide is "100mL / min" or "200mL / min", and the reaction pressure is "atmospheric pressure". In addition, the composition of the gas that makes the catalyst 11 work is set to "nitrous oxide (N2O): 1500ppm, ammonia (NH3): 1000ppm, argon (Ar): balance". Figure 17 On the left side, the material of catalyst 11 is "5wt% Rh / CeO2", the space velocity (SV) is "170000h -1 In the case of ", data D1 represents the data of "with electric field", and data D2 represents the data of "without electric field". In addition, data D3 and D4 respectively represent the data of "with electric field" and "without electric field" when oxygen (O2) coexists at 10%. Figure 17 On the right side, the material of catalyst 11 is "1wt% Rh / CeO2" and the space velocity (SV) is "50000h -1 ", and when oxygen (O2) coexists at 10%, data D1 represents data of "with electric field", and data D2 represents data of "without electric field".

[0129] according to Figure 17 It is clear that the reduction reaction by the reducing agent (NH 3) is significantly reduced due to the coexistence of oxygen (O 2 ), but the purification rate of nitrous oxide in the low temperature region can be sufficiently ensured by adjusting the space velocity, etc.

[0130] Figure 18 This is a graph showing the actual value of the purification rate of nitrous oxide when using a reducing agent. Figure 18 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "6 mA", the material of the catalyst 11 is "5wt% Cu / CeO2", the amount of the catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, the components of the gas that enables the catalyst 11 to function are set to "nitrous oxide (N2O): 1500 ppm, oxygen (O2): 10%, argon (Ar): balance". Figure 18 In the case where ammonia (NH3): 1000ppm is used as a reducing agent, data D1 represents data of "with electric field" and data D2 represents data of "without electric field". In the case where hydrogen (H2): 1500ppm is used as a reducing agent, data D3 represents data of "with electric field" and data D4 represents data of "without electric field".

[0131] according to Figure 18 It is clear that even when inexpensive copper (Cu) is used as the active metal of the catalyst 11, the purification rate of nitrous oxide in the low temperature region can be sufficiently ensured by adjusting the space velocity under the condition of coexistence of oxygen (O2).

[0132] Figure 19 This is a graph showing actual values ​​of the nitrous oxide purification rate when a reducing agent is used and the material of the catalyst 11 is changed. Figure 19 The test conditions other than the temperature of the catalyst 11 are as follows: the current value flowing through the catalyst 11 (in the case of "electric field") is "6 mA", the amount of the catalyst 11 is "200 mg", the flow rate of nitrous oxide is "100 mL / min", and the reaction pressure is "atmospheric pressure". In addition, ammonia (NH3): 1000 ppm is used as a reducing agent, and the components of the gas that enables the catalyst 11 to function are set to "nitrous oxide (N2O): 1500 ppm, ammonia (NH3): 1000 ppm, oxygen (O2): 10%, argon (Ar): balance". Figure 19 The left side shows the data of "with electric field". Figure 19 The right side of shows the data for "no electric field". Figure 19 In the figure, data of each active metal of catalyst 11 are shown, data D1 represents data of "5wt% Cu / CeO2", data D2 represents data of "5wt% Fe / CeO2", data D3 represents data of "5wt% Co / CeO2", data D4 represents data of "5wt% Ni / CeO2", and data D5 represents data of "5wt% W / CeO2".

[0133] according to Figure 19 It is clear that even when various materials are used as the active metal of the catalyst 11, a sufficient nitrous oxide purification rate in a low temperature region can be ensured by applying an electric field to the catalyst 11 under the condition of coexistence of oxygen (O2).

[0134] [5] Modification

[0135] The following lists modified examples of Embodiment 1. The modified examples described below can be applied in combination as appropriate.

[0136] The nitrous oxide purification system 10 of the present disclosure includes a computer system as a control unit 2. The computer system is mainly composed of one or more processors and one or more memories as hardware. The processor executes the program recorded in the memory of the computer system to realize the function of the control unit 2 of the present disclosure. The program can be pre-recorded in the memory of the computer system, or provided through an electrical communication line, or recorded in a non-temporary recording medium such as a memory card, an optical disk, a hard disk drive, etc. that can be read by the computer system. In addition, some or all of the functional units included in the control unit 2 can be composed of electronic circuits.

[0137] In addition, it is not essential for the nitrous oxide purification system 10 to have at least a portion of its functions integrated into a single housing. The components of the nitrous oxide purification system 10 may also be dispersed across multiple housings. Conversely, in the first embodiment, the functions dispersed across multiple devices may be integrated into a single housing.

[0138] Furthermore, at least a portion of the internal combustion engine system 100 is not limited to being mounted on the ship's hull and may also be installed separately from the hull. For example, if the control unit 2 of the nitrous oxide purification system 10 is embodied as a server device installed separately from the hull, the internal combustion engine system 100 can be controlled by the control unit 2 through communication between the server device and (the communication device of) the hull. At least a portion of the functions of the control unit 2 may be implemented via the cloud (cloud computing), etc.

[0139] In addition, the ship equipped with the internal combustion engine system 100 is not limited to a ship that sails a long distance with a single fuel refueling like an ocean liner. For example, it can be a small ship used for sports or entertainment in the ocean, such as a "yacht". In addition, the ship equipped with the internal combustion engine system 100 can be a merchant ship including cargo ships and cargo and passenger ships, a work ship including tugboats and lifeboats, a special ship including weather observation ships and training ships, a fishing boat, and a naval vessel. In addition, the ship is not limited to a manned type with an operator, but can also be an unmanned type ship that is remotely operated by a person (operator) or can sail autonomously. In addition, the ship can have one or more power sources such as a motor (electric motor) in addition to the engine 101 on the hull. The internal combustion engine system 100 can be used in structures other than ships, such as operating machinery, vehicles, or aircraft.

[0140] Furthermore, the nitrous oxide purification system 10 can be used in structures other than the internal combustion engine system 100. For example, the nitrous oxide purification system 10 can be used in facilities where nitrous oxide may be generated, such as farmland (including dry fields and greenhouses), pastures, fermentation processing facilities, or sewage treatment facilities. In such cases, the nitrous oxide purification system 10 uses a collection device to collect the nitrous oxide generated in these facilities and takes it into the intake unit 14, thereby purifying (decomposing or reducing) the nitrous oxide.

[0141] Furthermore, as long as an electric field is applied to the catalyst 11, the purification unit 1 is not necessarily required to include a pair of electrodes 12 and 13. For example, the purification unit 1 may include only a single electrode 12. Furthermore, the nitrous oxide purification system 10 is not necessarily required to include the power supply device 3. A voltage may be applied to the catalyst 11 (between the pair of electrodes 12 and 13) from a power supply device external to the nitrous oxide purification system 10.

[0142] Furthermore, the control unit 2 that controls the nitrous oxide purification rate of the purification unit 1 is not essential for the nitrous oxide purification system 10, and the control unit 2 may be omitted. Furthermore, the purifier 1 having the catalyst 11 and the electrodes 12 and 13 is not essential for the nitrous oxide purification system 10. The control unit 2 that changes the nitrous oxide purification rate of the purification unit 1 by changing at least one of the temperature of the catalyst 11, the current flowing through the catalyst 11, the amount of reducing agent added, and the space velocity is not essential for the nitrous oxide purification system 10. The control unit 2 that changes the purification rate at least according to the current value so that the larger the current value, the higher the purification rate is is not essential for the nitrous oxide purification system 10.

[0143] Furthermore, the heating unit 4 for heating the catalyst 11 is not an essential structure for the nitrous oxide purification system 10 and may be omitted. It is also not essential for the nitrous oxide purification system 10 that the active metal of the catalyst 11 is at least one of Rh, Pd, Pt, Fe, Cu, Ni, Co, W, and V, or that the catalyst carrier of the catalyst 11 includes any one of Ce, Zr, Y, La, Nd, and Pr.

[0144] Furthermore, heating the purification unit 1 using exhaust heat from the engine 101 is not an essential configuration for the internal combustion engine system 100. It is also not an essential configuration for the internal combustion engine system 100 that the engine 101 uses at least ammonia as fuel.

[0145] [Supplementary Notes on the Invention]

[0146] The following is a supplementary note on the outline of the invention extracted from the above embodiments. In addition, the various structures and processing functions described in the following supplementary notes can be selected and combined arbitrarily.

[0147] Note 1

[0148] A nitrous oxide purification system, wherein:

[0149] The nitrous oxide purification system comprises:

[0150] an intake unit that takes in nitrous oxide in the presence of O 2 and / or H 2 O; and

[0151] A purification unit decomposes or reduces the nitrous oxide taken in by the intake unit.

[0152] Note 2

[0153] According to the nitrous oxide purification system described in Appendix 1,

[0154] The purification unit has:

[0155] a catalyst that decomposes or reduces the nitrous oxide; and

[0156] Electrodes apply an electric field to the catalyst.

[0157] Note 3

[0158] According to the nitrous oxide purification system described in Appendix 2,

[0159] The nitrous oxide purification system further includes a power supply device for applying a voltage to the electrodes.

[0160] Note 4

[0161] The nitrous oxide purification system according to Appendix 2 or 3, wherein:

[0162] The nitrous oxide purification system further includes a control unit that changes the nitrous oxide purification rate of the purification unit by changing at least one of a temperature of the catalyst, a current value flowing through the catalyst, an amount of reducing agent input, and a space velocity.

[0163] <Note 5>

[0164] According to the nitrous oxide purification system described in Appendix 4,

[0165] The control unit changes the purification rate at least according to the current value so that the purification rate increases as the current value increases.

[0166] <Note 6>

[0167] The nitrous oxide purification system according to any one of Supplementary Notes 2 to 5, wherein

[0168] The nitrous oxide purification system further includes a heating unit for heating the catalyst.

[0169] The heating unit controls the temperature of the catalyst to be within a range of 50° C. to 600° C.

[0170] <Note 7>

[0171] The nitrous oxide purification system according to any one of Supplementary Notes 2 to 6, wherein

[0172] The catalyst comprises an active metal and a catalyst support,

[0173] The active metal is at least one of Rh, Pd, Pt, Fe, Cu, Ni, Co, W, and V.

[0174] The catalyst carrier includes any one of Ce, Zr, Y, La, Nd, and Pr.

[0175] <Note 8>

[0176] A nitrous oxide purification system, wherein:

[0177] The nitrous oxide purification system comprises:

[0178] an intake portion for taking in nitrous oxide; and

[0179] a purification unit that decomposes or reduces the nitrous oxide taken in by the intake unit,

[0180] The purification unit has:

[0181] a catalyst that decomposes or reduces the nitrous oxide; and

[0182] Electrodes apply an electric field to the catalyst.

[0183] <Note 9>

[0184] An internal combustion engine system, wherein:

[0185] The internal combustion engine system comprises: the nitrous oxide purification system according to any one of Supplementary Notes 1 to 8; and an engine,

[0186] The nitrous oxide purification system is arranged in an exhaust gas path originating from the engine.

[0187] <Note 10>

[0188] The internal combustion engine system according to Supplementary Note 9, wherein:

[0189] The purification unit is heated using exhaust heat from the engine.

[0190] <Note 11>

[0191] The internal combustion engine system according to Supplement 9 or 10, wherein:

[0192] The engine uses at least ammonia as fuel.

Claims

1. A nitrous oxide purification system, wherein: The nitrous oxide purification system comprises: an intake unit that takes in nitrous oxide in the presence of O 2 and / or H 2 O; and A purification unit decomposes or reduces the nitrous oxide taken in by the intake unit.

2. The nitrous oxide purification system according to claim 1, wherein: The purification unit has: a catalyst that decomposes or reduces the nitrous oxide; and Electrodes apply an electric field to the catalyst.

3. The nitrous oxide purification system according to claim 2, wherein: The nitrous oxide purification system further includes a power supply device for applying a voltage to the electrodes.

4. The nitrous oxide purification system according to claim 2 or 3, wherein: The nitrous oxide purification system further includes a control unit that changes the nitrous oxide purification rate of the purification unit by changing at least one of a temperature of the catalyst, a current value flowing through the catalyst, an amount of reducing agent input, and a space velocity.

5. The nitrous oxide purification system according to claim 4, wherein: The control unit changes the purification rate at least according to the current value so that the purification rate increases as the current value increases.

6. The nitrous oxide purification system according to claim 2 or 3, wherein: The nitrous oxide purification system further includes a heating unit for heating the catalyst. The heating unit controls the temperature of the catalyst to be within a range of 50° C. to 600° C.

7. The nitrous oxide purification system according to claim 2 or 3, wherein: The catalyst comprises an active metal and a catalyst support, The active metal is at least one of Rh, Pd, Pt, Fe, Cu, Ni, Co, W, and V. The catalyst carrier includes any one of Ce, Zr, Y, La, Nd, and Pr.

8. A nitrous oxide purification system, wherein: The nitrous oxide purification system comprises: an intake portion for taking in nitrous oxide; and a purification unit that decomposes or reduces the nitrous oxide taken in by the intake unit, The purification unit has: a catalyst that decomposes or reduces the nitrous oxide; and Electrodes apply an electric field to the catalyst.

9. An internal combustion engine system, wherein: The internal combustion engine system comprises: the nitrous oxide purification system according to any one of claims 1 to 3; and an engine. The nitrous oxide purification system is arranged in an exhaust gas path originating from the engine.

10. The internal combustion engine system according to claim 9, wherein: The purification unit is heated using exhaust heat from the engine.

11. The internal combustion engine system according to claim 9, wherein: The engine uses at least ammonia as fuel.

12. A method for purifying nitrous oxide, wherein: The nitrous oxide purification method comprises the following steps: Intake of nitrous oxide in the presence of O2 and / or H2O; and The taken-in nitrous oxide is decomposed or reduced.

Images