Hydrogen separation and recovery apparatus and method for separating and recovering hydrogen using the apparatus

Abstract

To provide a hydrogen separation and recovery apparatus capable of separating and recovering high-purity hydrogen in a high yield and capable of being used over a long period of time without generating the problem of membrane deterioration.MEANS: The apparatus for separating and recovering hydrogen includes a cylindrical body made of a proton conductor, an ammonia decomposition means, and a hydrogen pump, wherein the ammonia decomposition means includes an electrode for decomposing ammonia passing through an external space of the cylindrical body made of the proton conductor into hydrogen and nitrogen, and the hydrogen pump includes an electrode for passing hydrogen through an internal space of the cylindrical body made of the proton conductor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for separating and recovering hydrogen, and a method for separating and recovering hydrogen using the apparatus. [Background technology]

[0002] Global warming has become a major issue in recent years. Its cause is the emission of greenhouse gases from the use of fossil fuels. As greenhouse gases cover the entire Earth, heat accumulates, causing global warming. As a result, hydrogen has been attracting attention as an alternative energy source to fossil fuels. Hydrogen is considered a clean energy source, as it does not emit greenhouse gases when burned and only produces water.

[0003] However, hydrogen is difficult to store and transport. To solve this problem, it has been considered to convert hydrogen into ammonia for storage and transportation. However, if ammonia is used as an energy storage medium, the ammonia will corrode the materials of storage tanks and other structures in high-temperature environments. Therefore, it is considered to temporarily store and transport hydrogen in ammonia form, and ultimately extract hydrogen from the ammonia to use as fuel.

[0004] As a method for extracting hydrogen from ammonia, a method has been proposed in which ammonia is decomposed via a catalyst, and hydrogen is extracted from the resulting mixed gas of hydrogen and nitrogen by membrane separation or cryogenic separation (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-001105 [Patent Document 2] Patent Publication No. 2024-421560 Summary of the Invention [Problem to be solved by the invention]

[0006] However, membrane separation methods have the problem that the separation membrane deteriorates over time, and in the case of cryogenic separation, there is also the problem that the energy cost becomes excessive.

[0007] Therefore, an object of the present invention is to provide a hydrogen separation and recovery device that is capable of separating and recovering high-purity hydrogen with a high yield and that can be used for a long period of time without the problem of membrane degradation, and a method for separating and recovering hydrogen using the device. [Means for solving the problem]

[0008] As a result of extensive research into the above-mentioned problems, the present inventors have made the following findings. By combining an ammonia decomposition means, a hydrogen pump, and a cylindrical body made of a proton conductor, high-purity hydrogen can be recovered with a high yield from the hydrogen and nitrogen mixed gas obtained by decomposing ammonia. -By using the ammonia decomposition method as a hydrogen sensor and controlling the hydrogen pump based on the results obtained, it is possible to improve the hydrogen recovery rate.

[0009] Based on the above findings, the present inventors have completed the following invention. [1] A proton conductor cylindrical body, an ammonia decomposition means, and a hydrogen pump are provided. the ammonia decomposition means includes an electrode for decomposing ammonia passing through the external space of the cylindrical body made of the proton conductor into hydrogen and nitrogen; The hydrogen pump is a hydrogen separation and recovery device that includes electrodes that allow the hydrogen to pass through the internal space of the cylindrical body made of the proton conductor.

[0010] [2] The hydrogen separation and recovery device according to [1], wherein the ammonia decomposition means comprises a pair of electrodes arranged on the inside and outside of the cylindrical body made of the proton conductor.

[0011] [3] The hydrogen separation and recovery device according to [2], wherein the pair of electrodes is made of one metal selected from the group consisting of Pt, Ru, Rh, Pd and Ir, or an alloy of two or more metals.

[0012] [4] The hydrogen separation and recovery device according to [1], wherein the ammonia decomposition means is a hydrogen sensor, and controls the amount of hydrogen in the internal space and the external space of the cylindrical body made of the proton conductor so that they approach equal amounts.

[0013] [5] The hydrogen separation and recovery device according to [1], wherein the hydrogen pump comprises a pair of electrodes arranged on the inside and outside of the cylindrical body made of the proton conductor.

[0014] [6] The hydrogen separation and recovery device according to [5], wherein the pair of electrodes is made of one metal selected from the group consisting of Pt, Ru, Rh, Pd and Ir, or an alloy of two or more metals.

[0015] [7] The hydrogen separation and recovery device according to [1], wherein in the hydrogen pump, the electrode on the outside of the cylindrical body made of the proton conductor is an anode, and the electrode on the inside is a cathode.

[0016] [8] A hydrogen separation and recovery device as described in [4], which controls the output of the hydrogen pump based on the measurement results of the hydrogen sensor so that the amount of hydrogen in the internal space and external space of the cylindrical body made of the proton conductor approaches equal amounts.

[0017] [9] A method for separating and recovering hydrogen using the hydrogen separation and recovery device according to any one of [1] to [8]. [Effects of the Invention]

[0018] The hydrogen separation and recovery device of the present invention makes it possible to recover high-purity hydrogen with high efficiency from a hydrogen-nitrogen mixed gas obtained by decomposing ammonia. Furthermore, because it does not use a separation membrane, the material does not deteriorate with use, and it can be used for a long period of time. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a hydrogen separation and recovery apparatus according to the present invention. [Figure 2] FIG. 2 is a conceptual diagram showing the main components of the hydrogen separation and recovery device of the present invention. [Figure 3] FIG. 3 is a conceptual diagram showing how the hydrogen pump is controlled based on the measurement results of the hydrogen sensor in the hydrogen separation and recovery device of the present invention. [Figure 4] FIG. 4 is a graph showing the results of the example. DETAILED DESCRIPTION OF THE INVENTION

[0020] <Hydrogen separation and recovery device 100> FIG. 1 shows a schematic diagram of one embodiment of a hydrogen separation and recovery apparatus 100 of the present invention. In the schematic diagram of FIG. 1, the housing 40 and the interior of the cylindrical body 10 are shown so as to be visible. The hydrogen separation and recovery device 100 of the present invention comprises a cylindrical body 10 made of a proton conductor, an ammonia decomposition means 20, and a hydrogen pump 30. FIG. 2 is a conceptual diagram showing the configuration of the claimed components of the hydrogen separation and recovery device 100 of the present invention, namely, a cylindrical body 10 made of a proton conductor, an ammonia decomposition means 20 (hydrogen sensor 20S), and a hydrogen pump 30.

[0021] (Cylindrical body 10 made of proton conductor) The hydrogen separation and recovery device 100 comprises an external space W1 in which ammonia introduced from the outside and hydrogen gas and nitrogen gas formed by decomposition of the ammonia exist, and an internal space W2 in which the separated and recovered hydrogen gas exists, and the external space W1 and the internal space W2 are separated by a cylindrical body 10 made of a proton conductor.

[0022] A proton conductor is a material that transfers protons (hydrogen ions) when an external electric field is applied. The proton conductor constituting the cylindrical body 10 is CaZr 0.9In 0.1 O 3-a , BaZr 0.8 Y 0.2 O 3-a Examples include: The cylindrical body 10 made of a proton conductor can be manufactured by, for example, a powder sintering method.

[0023] Although the cross-sectional shape of the cylindrical body 10 is illustrated as being circular in Fig. 1, the cross-sectional shape is not limited to being circular and may be elliptical, triangular, rectangular, or other polygonal. The length of the cylindrical body 10 in the X direction (longitudinal direction) in Fig. 1 is preferably 50 mm to 1000 mm, more preferably 100 mm to 700 mm. The cross-sectional diameter of the cylindrical body 10 (the diameter of the circle if the cross section is circular, or the diameter of the smallest circle that can encompass the shape other than the circle if the cross section is other than circular) is preferably 5 mm to 50 mm, more preferably 7 mm to 30 mm. The thickness of the cylindrical body 10 is preferably 0.1 mm or more and 10 mm or less, more preferably 0.5 mm or more and 5 mm or less, and even more preferably 0.8 mm or more and 2 mm or less.

[0024] (Ammonia decomposition means 20) The ammonia decomposition means 20 is equipped with electrodes that decompose ammonia passing through the external space W1 of the cylindrical body 10 made of a proton conductor into hydrogen and nitrogen. The electrodes are preferably a pair of electrodes 22, 24 arranged respectively on the inside and outside of the cylindrical body 10 made of a proton conductor, as shown in Fig. 2, and it is preferable that both the inner electrode 24 and the outer electrode 22 of the cylindrical body 10 are formed continuously in the circumferential direction of the cylindrical body 10.

[0025] The ammonia decomposition means 20 is preferably formed upstream of the hydrogen pump 30, which will be described later, in the flow direction of ammonia introduced from the inlet 42. By decomposing ammonia into hydrogen gas and nitrogen gas upstream of the hydrogen pump, it becomes possible for the downstream hydrogen pump to efficiently introduce hydrogen gas into the inside of the cylindrical body 10 made of a proton conductor.

[0026] The width of the electrodes in the ammonia decomposition means 20 in the X direction is preferably 5 mm or more and 30 mm or less, more preferably 5 mm or more and 15 mm or less, in order to decompose ammonia sufficiently.

[0027] The material of the pair of electrodes in the ammonia decomposition means 20 is not particularly limited as long as it is a metal that is not corroded by ammonia, but it is preferably made of one metal selected from the group consisting of Pt, Ru, Rh, Pd, and Ir, or an alloy of two or more metals. Among these, Pt is preferred from the viewpoint of stable use over a long period of time.

[0028] As shown in Fig. 2, a voltage is preferably applied to a pair of electrodes formed on the inside and outside of the cylindrical body 10 made of a proton conductor. This allows the decomposition of ammonia to proceed more efficiently. The voltage is controlled depending on the desired ammonia decomposition speed, but is preferably 0 V or more and -5.0 V or less, and more preferably 0 V or more and -2.0 V or less.

[0029] Hydrogen sensor The ammonia decomposition means 20 preferably also functions as a hydrogen sensor 20S. The hydrogen sensor 20S measures the amount of hydrogen present in the internal space W2 of the cylindrical body 10 made of a proton conductor and the amount of hydrogen present in the external space W1, and controls the output of a hydrogen pump 30 (described later) so that these amounts of hydrogen approach equal amounts.

[0030] The amount of hydrogen V present inside the cylindrical body 10 made of a proton conductor 1 (ml) and the amount of hydrogen present on the outside, V 2 (ml) is V 1 / V 2 However, it is preferably controlled to 0.7 to 1.3, more preferably 0.8 to 1.2, even more preferably 0.9 to 1.1, particularly preferably 0.95 to 1.05, and most preferably 1.00.

[0031] (Hydrogen Pump 30) The hydrogen pump 30 has the function of selectively passing hydrogen from a mixed gas of nitrogen and hydrogen present in the external space W1 of the cylindrical body 10 made of a proton conductor into the internal space W2 of the cylindrical body 10 made of a proton conductor.

[0032] As shown in FIG. 2, the hydrogen pump 30 preferably comprises a pair of electrodes 32, 34 arranged on the inside and outside of a cylindrical body 10 made of a proton conductor, and it is preferable that both the inner electrode 34 and the outer electrode 32 of the cylindrical body 10 are formed continuously in the circumferential direction of the cylindrical body 10.

[0033] The hydrogen pump 30 is preferably located downstream of the ammonia decomposition means 20 in the flow direction of the decomposition gas in the external space W1 through which the decomposition gas of ammonia, that is, a mixed gas of nitrogen and hydrogen, flows.

[0034] The width of the electrodes 32, 24 in the hydrogen pump 30 in the X direction is preferably 5 mm or more and 30 mm or less, more preferably 5 mm or more and 15 mm or less, in order to ensure sufficient transfer of hydrogen to the internal space W2.

[0035] The material of the pair of electrodes in the hydrogen pump 30 is not particularly limited as long as it is a metal that is not corroded by ammonia, but it is preferably made of one metal selected from the group consisting of Pt, Ru, Rh, Pd, and Ir, or an alloy of two or more metals. Among these, Pt is preferred from the viewpoint of stable use over a long period of time. In the hydrogen pump 30, it is preferable that the electrode 32 on the outside of the cylindrical body 10 made of a proton conductor is an anode, and the electrode 34 on the inside is a cathode. At the anode 32, hydrogen is converted into protons, which then permeate the cylindrical body 10 made of a proton conductor and are converted back into hydrogen at the anode 34. This allows hydrogen to be selectively transported from the hydrogen-nitrogen mixed gas in the external space W1 to the internal space W2, enabling the separation and recovery of hydrogen.

[0036] The hydrogen transferred to the internal space W2 is preferably transferred to the right in the figure by an inert gas introduced from the left side Y1 in Fig. 1 and recovered together with the inert gas at Y2. As the inert gas, for example, argon can be used.

[0037] (Control of output of hydrogen pump 30 by hydrogen sensor 20) In the hydrogen separation and recovery device 100 of the present invention, it is preferable to control the output of the hydrogen pump 30 based on the measurement results of the hydrogen sensor 20S so that the amount of hydrogen in the internal space W2 inside the cylindrical body 10 made of a proton conductor and the external space W1 outside it approach equal amounts. For example, as shown in FIG. 3, the above control can be realized by connecting the hydrogen sensor 20S and the hydrogen pump 30 via a potentiogalvanostat.

[0038] (Other parts) External enclosure 40 The hydrogen separation and recovery apparatus 100 according to one embodiment of the present invention further includes an external housing 40. The external housing 40 includes an ammonia inlet 42 and a waste gas outlet 44, and an external space W1 is formed between the external housing 40 and the cylindrical body 10 made of a proton conductor.

[0039] The material of the outer housing 40 is not particularly limited as long as it can withstand the heat generated during the ammonia decomposition reaction, but heat-resistant glass, for example, can be used. Examples of heat-resistant glass include borosilicate glass, quartz glass, Neoceram, and Virex glass.

[0040] The external casing 40 only needs to have a length in the X direction sufficient to cover the above-described cylindrical body 10 made of a proton conductor, and a cross-sectional shape in a direction perpendicular to the X direction sufficient to form a sufficient external space W1. Therefore, the external casing 40 preferably has a cross-sectional shape similar to that of the cylindrical body 10 made of a proton conductor, and when the cross-sectional shape of the cylindrical body 10 made of a proton conductor is circular, the cross-sectional shape of the external casing 40 is also circular, and these are preferably concentric circles.

[0041] The length of external housing 40 is preferably 50 mm to 1000 mm, and more preferably 100 mm to 700 mm. The cross-sectional diameter of external housing 40 (the diameter of the circle if the cross-section is circular, or the diameter of the smallest circle that can encompass the non-circular shape if the cross-section is non-circular) is preferably 15 mm to 70 mm, and more preferably 20 mm to 50 mm.

[0042] Connection members 52, 54 The hydrogen separation and recovery apparatus 100 according to one embodiment of the present invention further includes connecting parts 52, 54 for connecting to external components. The connecting parts 52, 54 only need to have heat resistance and strength as connecting members, and can be made of metal such as brass, pure iron, nickel, stainless steel, etc. Furthermore, the connecting members 52 and 54 may be formed integrally with the external housing 40 described above. The connecting member 52 on the left side of FIG. 1 is connected to an apparatus for supplying inert gas, and the connecting member 54 on the right side is connected to a hydrogen recovery apparatus, a hydrogen tank, or the like.

[0043] ·Sealing member 60 The hydrogen separation and recovery apparatus 100 according to one embodiment of the present invention further includes a sealing member 60 for connecting and sealing the outer housing 40, the cylindrical body 10 made of a proton conductor, and the connecting members 52 and 54. The sealing member 60 can be made of, for example, a heat-resistant resin.

[0044] <Method for separating and recovering hydrogen> The method for separating and recovering hydrogen of the present invention is carried out using the hydrogen separation and recovery apparatus of the present invention described above.

[0045] (Raw material ammonia) The raw material ammonia is preferably introduced in a gaseous state into the external space W1 from the inlet 42. The amount of ammonia introduced is, for example, preferably 0.05 mL / min or more and 10 mL / min or less, more preferably 0.1 mL / min or more and 5 mL / min or less.

[0046] Furthermore, the raw ammonia may contain other gases in addition to ammonia, and even in this case, it is possible to selectively recover hydrogen from the mixed gas using the hydrogen pump 30 described above. Examples of other gases include inert gases such as nitrogen gas and argon. For example, it is preferable from the viewpoint of safety to introduce a mixture of an inert gas such as argon and ammonia, but from the viewpoint of recovery efficiency, it is preferable that the amount of other gases is small, preferably 30 vol% or less, more preferably 10 vol% or less, even more preferably 5 vol% or less, particularly preferably 1 vol% or less, and it is most preferable that no other gases are contained and the raw material gas consists only of ammonia.

[0047] (exhaust gas) Hydrogen is selectively recovered from the mixed gas obtained by decomposition by the ammonia decomposition means 20, and the remaining gas is discharged to the outside from the exhaust port 44 of the housing 40. The hydrogen concentration in the discharged exhaust gas is preferably 10 vol% or less, more preferably 5 vol% or less, even more preferably 3 vol% or less, even more preferably 1 vol% or less, even more preferably 0.1 vol% or less, even more preferably 0.05 vol% or less, particularly preferably 0.01 vol% or less, and most preferably 0.00 vol%, and it is preferable that hydrogen be completely recovered by the hydrogen pump 30.

[0048] (Heating temperature) The hydrogen separation and recovery apparatus 100 needs to be placed in a heated environment to decompose ammonia in the ammonia decomposition means 20. The heating temperature is preferably 500°C or higher, more preferably 600°C or higher, to promote the decomposition reaction, and is preferably 1000°C or lower, more preferably 900°C or lower, from the viewpoint of the heat resistance of the components. The heating may be performed by heating the entire hydrogen separation and recovery apparatus 100 of the present invention, or by locally heating the periphery of the ammonia decomposition means 20 . The heating temperature can be measured, for example, by the thermocouple 46 shown in FIG.

[0049] (inert gas) The hydrogen introduced into the cylindrical body 10 made of a proton conductor is recovered using an inert gas as a medium. For example, the inert gas is introduced from the left side Y1 in FIG. 1 and recovered together with the inert gas from the right side Y2. As the inert gas, for example, argon can be used.

[0050] The hydrogen concentration in the gas recovered from Y2 is preferably 0.1 vol% or more, more preferably 0.2 vol% or more, and even more preferably 0.5 vol% or more, from the viewpoint of utilizing hydrogen in subsequent processes, and is preferably 50 vol% or less, more preferably 40 vol% or less, even more preferably 20 vol% or less, and particularly preferably 10 vol% or less, from the viewpoint of efficient hydrogen recovery.

[0051] The lower limit of the argon introduction rate is preferably 5 ml / min or more, more preferably 10 ml / min or more, and even more preferably 20 ml / min or more, and the upper limit is preferably 100 ml / min or less, more preferably 70 ml / min or less, even more preferably 50 ml / min or less, and particularly preferably 40 ml / min or less. [Example]

[0052] Using the hydrogen separation and recovery device shown in Figure 1, hydrogen was separated and recovered from the raw material gas, ammonia. The raw material gas used was a mixed gas of 80 vol % argon and 20 vol % ammonia, which was introduced into the external space W1 from the inlet 42 at a rate of 1.5 ml / min.

[0053] The external casing 40 and the cylindrical body 10 made of proton conductor have the same length in the X direction, both 1900 mm, and both have circular cross sections perpendicular to the X direction. The diameter of the external casing 40 is 26 mm, and the diameter of the cylindrical body 10 made of proton conductor is 10 mm, and each is a double tube with a cross-sectional shape of a concentric circle.

[0054] The electrodes of the ammonia decomposition means 20 (hydrogen sensor 20S) are provided continuously in the circumferential direction on both the inside and outside of the cylindrical body 10, have a width in the X direction of 10 mm, a thickness of 100 μm, and are made of Pt.

[0055] The electrodes of the hydrogen pump 30 are provided continuously in the circumferential direction on both the inside and outside of the cylindrical body 10, have a width in the X direction of 10 mm, a thickness of 100 μm, and are made of Pt.

[0056] The material of the cylindrical body 10 made of a proton conductor is CaZr 0.9 In 0.1 O 3-a and the thickness is 1 mm.

[0057] The outer housing 40 is made of quartz glass, which is heat-resistant glass, the connecting members 52 and 54 are made of brass, and the sealing member 60 is made of heat-resistant silicone. The hydrogen sensor 20S and the hydrogen pump 30 were connected by a potentiogalvanostat 70, and controlled so that the amount of hydrogen in the space W1 and the space W2 approached the same amount.

[0058] The results are shown in Figure 4. The current applied to the hydrogen pump 30 is shown on the right side, and the hydrogen partial pressure of the gas obtained at Y2 on the left side of the figure is shown on the left side. The hydrogen partial pressure rises with a delay after the current (hydrogen supply current) applied to the hydrogen pump 30, and after a certain amount of hydrogen is maintained for a certain period of time, when the hydrogen supply current is stopped, the hydrogen partial pressure also drops. Thus, it was demonstrated that a constant amount of hydrogen could be obtained according to the current applied to the hydrogen pump. In addition, the composition of the gas obtained was analyzed using a hydrogen sensor, and it was found to be 99.00 vol% argon and 1.00 vol% hydrogen, indicating that hydrogen had been completely separated from nitrogen within the accuracy of the analytical equipment used.

Claims

1. a cylindrical body made of a proton conductor, an ammonia decomposition means, and a hydrogen pump; the ammonia decomposition means includes an electrode for decomposing ammonia passing through the external space of the cylindrical body made of the proton conductor into hydrogen and nitrogen; The hydrogen pump is a hydrogen separation and recovery device that includes electrodes that allow the hydrogen to pass through the internal space of the cylindrical body made of the proton conductor.

2. 2. The hydrogen separation and recovery device according to claim 1, wherein the ammonia decomposition means comprises a pair of electrodes disposed on the inside and outside of the cylindrical body made of the proton conductor.

3. 3. The hydrogen separation and recovery device according to claim 2, wherein the pair of electrodes is made of one metal selected from the group consisting of Pt, Ru, Rh, Pd and Ir, or an alloy of two or more metals.

4. 2. The hydrogen separation and recovery device according to claim 1, wherein the ammonia decomposition means is a hydrogen sensor that controls the amount of hydrogen in the internal space and the external space of the cylindrical body made of the proton conductor so that they approach the same amount.

5. 2. The hydrogen separation and recovery device according to claim 1, wherein the hydrogen pump comprises a pair of electrodes disposed on the inside and outside of the cylindrical body made of the proton conductor.

6. 6. The hydrogen separation and recovery device according to claim 5, wherein the pair of electrodes is made of one metal selected from the group consisting of Pt, Ru, Rh, Pd and Ir, or an alloy of two or more metals.

7. 2. The hydrogen separation and recovery device according to claim 1, wherein in said hydrogen pump, the electrode on the outside of said cylindrical body made of said proton conductor is an anode, and the electrode on the inside is a cathode.

8. 5. The hydrogen separation and recovery device according to claim 4, wherein the output of the hydrogen pump is controlled based on the measurement results of the hydrogen sensor so that the amounts of hydrogen in the internal space and the external space of the cylindrical body made of the proton conductor approach equal amounts.

9. A method for separating and recovering hydrogen using the hydrogen separation and recovery device according to any one of claims 1 to 8.

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