Methods for ammonia decomposition

Abstract

The present invention relates to a method for decomposing ammonia, producing hydrogen, and generating electricity at low temperatures using an ammonia synthesis catalyst, including the electrolysis of water in the supplied ammonia (2), evaporation (3), preheating (5), and decomposition of the ammonia (6).

Description

Technical Field

[0001] Field of the Invention The present invention provides a method for decomposing ammonia and a method for producing hydrogen, including electrolyzing water in feed ammonia upstream of an ammonia decomposer. The present invention also provides a method for generating electricity. The method of the present invention improves the efficiency of ammonia decomposition or cracking (decomposition) at low temperatures, reduces costs, while increasing the total yield of hydrogen produced. The present invention relates to all technical fields using ammonia as an energy source and / or for the production of hydrogen and electricity.

Background Art

[0002] Background Art Liquid ammonia is an important energy carrier for producing hydrogen and is particularly an important source for generating electricity in areas with little fuel source. As an energy carrier, liquid ammonia can also function as a supply source for equalizing fluctuating electricity production by renewable energy technologies such as wind power, solar power, and hydroelectric power.

[0003] To use ammonia as an energy carrier or hydrogen carrier, ammonia can be directly utilized in combustion engines / gas turbines or fuel cells and can be decomposed / cracked into hydrogen and nitrogen. The decomposed ammonia can be supplied to a gas turbine or hydrogen can be recovered for fuel cells and other applications. Today's well-known and commonly used ammonia is produced from steam reforming of natural gas or gasification of coal. Also, a small amount of ammonia is produced by supplying power to water electrolysis for hydrogen production, and growth of this method is expected in the future. The produced ammonia contains water because generally the synthesis gas formed contains water, and this water is advantageous for ammonia storage to prevent stress corrosion cracking of the walls of storage tanks made of metal. If the synthesis gas does not contain water, that water is added to the produced ammonia.

[0004] The advantage of ammonia as an energy carrier is that liquid ammonia is easier to transport and store than, for example, natural gas or hydrogen gas. Furthermore, storing energy in ammonia is cheaper than using hydrogen or batteries. Due to transportation needs, traded liquid ammonia, even what is called anhydrous, usually contains water. The water content of makeup ammonia is typically in the range of 0.2 to 0.5 mass%. Ammonia produced from water, air, or renewable energy from water electrolysis does not contain water, but water is added again for storage and transport.

[0005] In the ammonia decomposition process, gaseous ammonia is reversibly dissociated into a mixture of hydrogen and nitrogen gases. [ka]

[0006] Reaction (A) is endothermic and requires heat to continue the ammonia decomposition reaction.

[0007] Ammonia synthesis catalysts are known to be usable for the decomposition and cracking of ammonia. However, it is also well known that water or other oxygen-containing compounds can poison ammonia synthesis catalysts. Since water is the major compound in the liquid ammonia being traded, the poisoning of these synthesis catalysts is considered a problem that affects the performance of the catalyst and, therefore, how effective and efficient the decomposition process is. This is at least one reason why other, more expensive catalysts are commonly used in ammonia decomposition.

[0008] The most common method for removing water from ammonia before decomposition or cracking is distillation. The present invention's method of removing water from ammonia by electrolysis is more efficient and effective than distillation because the hydrogen produced thereby contributes to the final yield of hydrogen gas, and the energy expended to electrolyze the water into oxygen and hydrogen is not lost. In contrast, with distillation, all the energy expended to separate the water from the ammonia is simply lost.

[0009] US20130266506 discloses a method for producing hydrogen from ammonia, in which the ammonia decomposition step uses an oxidation catalyst to achieve the generation of heat necessary for ammonia decomposition (by the reaction of some of the introduced ammonia with oxygen) at a relatively low temperature, preferably between 400°C and 650°C. The aim is to reduce the amount of catalyst required for ammonia decomposition and hydrogen production, thereby reducing the cost of the said production. This method appears to be an alternative to the method of the present invention, but it still requires the use of expensive catalysts for both the oxidation and decomposition of ammonia in order to decompose ammonia at a relatively low temperature. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] US20130266506 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Other literature discloses the use of different catalysts to decompose ammonia at relatively low temperatures, i.e., around 400°C, in order to optimize hydrogen production parameters. However, these are expensive catalysts, which would increase production costs compared to those of the present invention. When using inexpensive catalysts such as the Fe-based ammonia synthesis catalyst used in the method of the present invention, a much higher temperature range is usually required to achieve similar efficiency.

[0012] Purging (removing) the water accumulated at the bottom of the evaporator (3) is necessary to remove water from the ammonia before ammonia cracking or decomposition (5), particularly to evaporate the ammonia solution. The water purged from the bottom of the ammonia evaporator still contains ammonia (about 10%), which will be lost or recovered during the distillation process. If not recovered, the ammonia loss during water purging will be about 10% of the water content of the purchased ammonia, or 0.02-0.05% of the total amount of ammonia raw material. Next, the contaminated water purge needs to be safely disposed of. [Means for solving the problem]

[0013] Summary of the Invention The present invention relates to a method for decomposing ammonia, comprising electrolysis (2), evaporation (3), preheating (5), and decomposition (6) of water in a supply ammonia, at a temperature of 300 to 700°C, using an ammonia synthesis catalyst, preferably an Fe-based catalyst.

[0014] In a second embodiment, the present invention relates to a method for producing hydrogen at a temperature of 300 to 700°C using an ammonia synthesis catalyst, preferably an Fe-based catalyst, comprising electrolysis (2), evaporation (3), preheating (5), and decomposition of ammonia (6) of water in a feed ammonia, wherein at least one of (i) hydrogen produced by electrolysis (2) and (ii) hydrogen produced by ammonia decomposition (6) contributes to the final yield of hydrogen.

[0015] In a third embodiment, the present invention relates to a method for generating electricity to be supplied to, for example, a gas turbine (10) (Figure 3) using ammonia gas, hydrogen, and nitrogen as feedstocks, wherein the decomposition of ammonia (6) is carried out at a temperature between 300 and 700°C using an ammonia synthesis catalyst, and at least one of (i) hydrogen produced by electrolysis (2) and (ii) hydrogen produced from ammonia decomposition (6) contributes to the final hydrogen yield, and waste heat is recovered (11) in an ammonia evaporator (3).

[0016] In a preferred embodiment, hydrogen is produced alternately by electrolysis and / or ammonia decomposition. For example, during the day, hydrogen can be obtained mainly by the electrolysis of water, and at night, hydrogen can be obtained mainly by ammonia decomposition. In another preferred embodiment, electricity can be generated by utilizing the combustion of ammonia. [Effects of the Invention]

[0017] The method of the present invention offers the following advantages: - The electrolysis of water into hydrogen and oxygen is more efficient than distillation for removing water from ammonia, because the energy expended on the electrolysis is compensated for by the additional hydrogen gas produced; - Purge from the ammonia evaporator downstream of the electrolytic unit is limited and processed within the electrolytic unit; - Ammonia synthesis catalysts, preferably Fe-based catalysts, can still be used for ammonia decomposition at relatively low temperatures, for example, about 300-700°C, preferably 350-550°C, and are less expensive than customized catalysts to achieve high efficiency over similar temperature ranges, and can be used especially when considerable quantities are required, such as in large-scale ammonia decomposition industrial facilities; When used at temperatures of approximately -300 to 700°C, the cost of materials and equipment is lower compared to the maintenance costs and frequency of high-grade materials required when used at high temperatures. Furthermore, lower temperatures result in less waste heat to recover, enabling lower costs and greater efficiency in the process. - When using the decomposed ammonia obtained by the method of the present invention as a raw material for power generation, since the energy required for ammonia decomposition is small and the waste heat from the decomposer and the decomposition process is also small, the resulting overall efficiency is significantly high. - In particular, since ammonia can react with an iron-based catalyst to form iron nitride, Fe2N or Fe4N, protection / life extension of the iron-based catalyst by the presence of hydrogen. This reaction becomes prominent especially at high temperatures, typically 500 °C or higher, in pure ammonia. The formation of iron nitride leads to physical decomposition of the catalyst. Therefore, the catalyst is deactivated, the pressure loss on the catalyst bed increases, which may lead to an increase in the process cost (process cost). Therefore, hydrogen contained in the process gas inhibits the formation of iron nitride. These considerations are also valid for the materials of the reactor, and hydrogen protects the material from nitridation.

Brief Description of the Drawings

[0018] Brief Description of the Drawings Figure 1 shows the electrolysis of water in the pretreatment before ammonia decomposition (2).

[0019] Figure 2 shows the method of the present invention. In the ammonia decomposer, the following reaction occurs: 2NH3 = N2 + 3H2 Since this reaction is hardly or never completed, a considerable amount of unreacted ammonia remains after the ammonia decomposer. This unreacted ammonia is cooled and recovered in a scrubber by absorbing ammonia in water, or condensed by cooling (7), and the liquid ammonia can be recycled back to the electrolytic cell (when water is included) or the evaporator (when water is not included). If it is selected to use water in the cooling stage to remove traces of ammonia, it is ensured that the product gases, H2 and N2, are ammonia-free. With such a configuration, hydrogen can be produced partially or completely from electrolysis during the day and from partial or complete ammonia decomposition at night. Furthermore, hydrogen purification can be achieved by PSA or other appropriate techniques.

[0020] Figure 3 shows the integration with a gas turbine to maximize the overall efficiency of electricity production. The product gases hydrogen and nitrogen are used as gas turbine fuel, and ammonia may also be present, either unreacted ammonia from the decomposition (6) or ammonia bypassed (9) before decomposition. It is also possible to add ammonia gas to the decomposition process.

Explanation of symbols

[0021] The reference numbers used are as follows: (1) Makeup ammonia (0.2 - 0.5% water) (2) Water electrolyzer (3) Evaporation (4) Purge H2O / NH3 (5) Preheating (6) Cracking or decomposition (7) Cooling (8) Recycling condensed unreacted ammonia (with water, without water). (9) Bypassed ammonia (10) Gas turbine (11) Waste heat

Mode for carrying out the invention

[0022] Definition Ammonia cracking or decomposition is a process that breaks down gaseous anhydrous ammonia (NH3) into a mixture of hydrogen (H2) and nitrogen (N2), with the reaction equation being: 2NH3 = N2 + 3H2. This reaction is endothermic. This process is typically carried out at high temperatures of 1560–1740°F (850–950°C) in the presence of nickel as a catalyst. Due to the high temperature, thermal sintering of the catalyst shortens its lifespan. The resulting gas mixture contains hydrogen and nitrogen in a ratio of 3:1 (75% H2, 25% N2), with a small amount (20–100 ppm) of undissociated ammonia remaining at a dew point of -60°F to -20°F (-51°C to -29°C). When carried out under the conditions of the present invention, the catalyst is preferably Fe-based, and the process is carried out at lower temperatures between approximately 300–700°C.

[0023] An ammonia decomposer means any suitable reactor in which ammonia decomposition (6) can be carried out, and includes a calcination reactor, preferably an SMR.

[0024] In the context of this invention, an ammonia synthesis catalyst is any catalyst suitable for synthesizing ammonia and any catalyst suitable for decomposing ammonia. These catalysts are preferably iron (Fe) based, but may include other catalysts suitable for the same purpose and operating under similar conditions.

[0025] Ammonia slip refers to unconverted ammonia (ammonia that did not dissociate during the decomposition process) that passes through an ammonia decomposer.

[0026] Electrolysis of water is the process of breaking down water into oxygen and hydrogen gas by passing an electric current through it.

[0027] The supplied ammonia or ammonia supply raw material refers to a solution containing makeup ammonia and additional water. The supplied ammonia is the solution supplied to or provided to the electrolytic cell (2).

[0028] High-pressure electrolysis (HPE) is a process that involves passing an electric current through water at a high pressure, usually exceeding 10 bar, to decompose water (H2O) into oxygen (O2) and hydrogen gas (H2), thereby electrolyzing water.

[0029] Makeup ammonia, or traded ammonia, contains ammonia (NH3) and water (H2O), preferably with a water content of 0.2-0.5%. It is usually supplied as a liquid, but may also be a solution containing different physical states. The impact of water in the ammonia raw material during the ammonia decomposition process is primarily due to the poisoning of processes that must normally be carried out at high temperatures. This increases the process cost of ammonia decomposition and the cost of plant construction materials. According to the National Bureau of Standards, ammonia must meet the following characteristics: a minimum purity of 99.98% (by mass), a maximum of 0.0005% (by mass) of oil, and a maximum of 0.02% (by mass) of water.

[0030] Nitriding refers to the process of producing nitrogen compounds by reacting them with ammonia.

[0031] PSA stands for Pressure Swing Adsorption.

[0032] The amount of water remaining due to slip from the electrolysis unit is accumulated in the evaporator and needs to be purged (4). This purge contains water, and the ammonia is recycled into ammonia raw material (1) and then back into the electrolysis unit, meaning that the water content in the evaporated ammonia will be close to zero.

[0033] Detailed description of the invention To make ammonia suitable as a fuel for power generation, it is necessary to at least partially decompose it into a mixed gas containing gaseous hydrogen, nitrogen, and ammonia. When using ammonia as an energy carrier for hydrogen production and having only ammonia as an energy source, it is economically essential to maximize the amount of hydrogen produced per ton of ammonia consumed. This is because cracking or decomposing ammonia at the lowest possible temperature reduces the amount of waste heat recovered. In this case, the waste heat recovered as steam is of little value because hydrogen is the desired product.

[0034] In the ammonia decomposition process, gaseous ammonia is reversibly dissociated into a mixture of hydrogen and nitrogen: [ka]

[0035] This reaction is endothermic and requires heat to sustain the ammonia decomposition reaction.

[0036] Traditionally, ammonia synthesis catalysts have been used for the decomposition and cracking of ammonia. However, it is also well known that water and other oxygen-containing compounds poison ammonia synthesis catalysts, such as Fe-based catalysts. Since water is the main component of liquid ammonia and makeup ammonia (1), the poisoning of these synthesis catalysts is considered a problem that affects the performance of the catalyst, i.e., the effectiveness and efficiency of the decomposition process. This is at least one reason why other, more expensive catalysts are commonly used in ammonia decomposition.

[0037] The most common method for removing water from ammonia before decomposition is distillation. The present invention's method of removing water from ammonia by electrolysis is more efficient and effective than typical distillation because the hydrogen produced ultimately contributes to the product gas, thus eliminating the loss of energy spent electrolyzing water into oxygen and hydrogen. In contrast, with distillation, all the energy expended to separate water from ammonia is simply lost.

[0038] In conventional ammonia decomposers using water-tolerant catalysts, 0.2–0.5% water in makeup ammonia (1) does not harm the catalyst. These catalysts operate at high temperatures exceeding 600°C, up to approximately 950°C.

[0039] By removing water from makeup ammonia (1), it will be possible to use alternative catalysts similar to those used in ammonia synthesis at low temperatures, typically in the range of 300–700°C, preferably 350–550°C. Such ammonia synthesis catalysts are preferably iron (Fe)-based, or other catalysts suitable for the same purpose, and can usually be purchased at a much lower cost than high-temperature catalysts that tolerate water and other oxygen-containing compounds, which are commonly used for ammonia decomposition.

[0040] Operating the ammonia decomposer at a low temperature allows for the use of lower-grade materials, reducing equipment costs. Furthermore, lower temperatures result in less waste heat being recovered, making the process more cost-effective and efficient.

[0041] Makeup ammonia contains approximately 0.2-0.5% water, which is electrolyzed together with any supplemental amount of water added to the makeup ammonia before it enters the electrolytic cell (2) (2). Supply ammonia is a liquid composition supplied to the electrolytic cell (2) and contains makeup ammonia and the aforementioned supplemental amount, depending on the desired amount of hydrogen obtained by electrolysis. The effect of adding water is to increase the amount of hydrogen obtained by electrolysis and to regulate hydrogen production from renewable energy in the electrolytic cell. In addition, hydrogen has the effect of protecting catalysts and materials from nitriding.

[0042] In a preferred embodiment, if there are multiple decomposers (6), water is added to the makeup ammonia derived from the supply ammonia (1), which is electrolyzed (2) into hydrogen and oxygen to adjust the hydrogen content in the evaporated ammonia supplied to the first ammonia decomposer (Figure 2).

[0043] In a preferred embodiment of the present invention, the decomposed ammonia gas becomes a raw material for a gas turbine for power generation. As shown in Figure 3, the overall efficiency can be greatly improved by bypassing a sufficient amount of ammonia gas to the decomposer. The overall efficiency is high because less energy is required for ammonia decomposition and less waste heat is generated from the decomposition process. In this case, it is expected that there will not be enough waste heat to evaporate the ammonia raw material, but since the temperature level required for ammonia evaporation is below about 100°C and therefore usable, it is possible to recover waste heat from the gas turbine exhaust without reducing the gas turbine combined cycle efficiency. A sufficient amount of ammonia gas to be bypassed is usable up to about 98% of the available ammonia, in which case heat from the gas turbine exhaust is required. Depending on the gas turbine technology, if the amount of bypass is too large, there will not be enough heat to evaporate all the ammonia. Therefore, heat from the gas turbine is utilized. The higher the ammonia content, the higher the overall efficiency.

[0044] Preferred Embodiment 1. A method for decomposing ammonia, comprising: a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation (3); d) Decomposition (6); and Here, the decomposition of ammonia (6) is carried out using an ammonia synthesis catalyst at a temperature between 300 and 700°C, most preferably between 350 and 550°C.

[0045] 2. A method for producing hydrogen from makeup ammonia (1), comprising: a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation (3); d) Decomposition (6); and e) Cooling of the gas phase resulting from decomposition (6) (7), Here, the decomposition of ammonia (6) is carried out using an ammonia synthesis catalyst at a temperature of 300 to 700°C, most preferably 350 to 550°C, and at least one of (i) hydrogen produced by electrolysis (2) and (ii) hydrogen produced from the decomposition of ammonia (6) contributes to the final yield of hydrogen.

[0046] 3. The method according to Embodiments 1 and 2, wherein ammonia is preheated (5) before the decomposition (6) step. 4. The method according to Embodiments 1 to 3, wherein the makeup ammonia (1) contains about 0.2 to about 2% water.

[0047] 5. The method according to Embodiments 1 to 4, wherein the ammonia synthesis catalyst is an Fe-based catalyst. 6. The method according to Embodiments 1 to 4, wherein the catalyst used is Co, Ru, or Ni-based.

[0048] 7. The method according to Embodiments 1 to 5, wherein the solution containing liquid ammonia and non-evaporating water is removed (4) from the evaporator (3) and recycled back into the supply ammonia. 8. The method according to Embodiments 1 to 6, wherein the electrolysis is high-voltage electrolysis.

[0049] 9. The method according to Embodiments 1 to 7, wherein the hydrogen obtained from ammonia decomposition is recycled by an external compressor. 10. Cooling (7) The method according to Embodiments 1 to 9, wherein water is added to step e) and a scrubber is used to remove any traces of unconverted ammonia.

[0050] 11. The method according to Embodiment 10, wherein unconverted ammonia is condensed (8) and recycled to an electrolytic cell (2) if it contains water, or to an evaporator (3) if it does not contain water. 12. A method for removing water from ammonia, comprising the following steps: a) Electrolysis of water in the feed ammonia (2), where the feed ammonia contains makeup ammonia; and b) Evaporation (3).

[0051] 13. Use of ammonia obtained by the method according to Embodiment 12 in ammonia decomposition and / or hydrogen production using a catalyst, for example, an Fe-based catalyst. 14. Use of ammonia obtained by the method according to Embodiment 12 in ammonia decomposition and / or hydrogen production, in which a Co, Ru, or Ni-based catalyst may be used.

[0052] 15. A method for generating electricity, wherein a gas turbine (10) a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation (3); c) Decomposition (6), and d) Cooling of the gas phase produced from decomposition (6) (7), Supply at least one of hydrogen, nitrogen, and ammonia obtained from: Here, the decomposition of ammonia (6) is carried out at 300 to 700°C, most preferably 350 to 550°C, using an ammonia synthesis catalyst, and at least one of (i) hydrogen produced by electrolysis (2) and (ii) hydrogen produced from ammonia decomposition (6) contributes to the final hydrogen yield, and waste heat is recovered (11) in an ammonia evaporator (3). 16. The method according to Embodiment 15, wherein ammonia is preheated (5) before the decomposition (6) step.

[0053] 17. The method according to embodiments 15 and 16, wherein some of the ammonia is decomposed (6) and some of the ammonia is bypassed (9) and supplied to a gas turbine (10). 18. The method according to embodiments 15-17, wherein hydrogen is produced periodically and / or alternatively, for example, by partial or whole electrolysis during the day and by partial or whole decomposition of ammonia at night.

[0054] 19. Use of the methods according to embodiments 15-18 for generating electricity by supplying at least one of hydrogen (2,7), nitrogen (7), and ammonia (7,9) to a gas turbine (10). 20. Use of the methods according to Embodiments 15-18 for producing hydrogen and oxygen (2), evaporated ammonia (3), and hydrogen gas, nitrogen, and ammonia from makeup ammonia. This invention includes the following items. [Item 1] a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation (3); c) Decomposition (6); A method for decomposing ammonia, including, The method wherein the decomposition of ammonia (6) is carried out at a temperature of 300 to 700°C using an ammonia synthesis catalyst. [Item 2] a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation (3); c) Decomposition (6); and d) Cooling of the gas phase produced from decomposition (6) (7), A method for producing hydrogen from makeup ammonia (1), comprising: The decomposition of ammonia (6) is carried out at a temperature of 300-700°C using an ammonia synthesis catalyst. (i) Hydrogen produced by electrolysis (2), and (ii) Hydrogen produced from the decomposition of ammonia (6) The method wherein at least one of the elements contributes to the final hydrogen yield. [Item 3] The method according to item 1 or 2, wherein ammonia is preheated (5) before the decomposition (6) step. [Item 4] The method according to any one of items 1 to 3, wherein the makeup ammonia (1) contains approximately 0.2 to approximately 2% water. [Item 5] The method according to any one of items 1 to 4, wherein the ammonia synthesis catalyst is Fe-based. [Item 6] The method according to any one of items 1-4, wherein the catalyst used is Co, Ru, or Ni based. [Item 7] The method according to any one of items 1 to 6, wherein a solution containing liquid ammonia and non-evaporating water is purged (4) from the evaporator (3) and recycled back into the supply ammonia. [Item 8] The method described in any one of items 1-7, wherein the electrolysis is high-voltage electrolysis. [Item 9] The method described in any one of items 1-8, wherein hydrogen obtained from ammonia decomposition is recycled in an external compressor. [Item 10] The method according to any one of items 1-9, wherein water is added to step (7) e) for cooling, and a scrubber is used to remove any traces of unconverted ammonia. [Item 11] The method described in item 10, wherein unconverted ammonia is condensed and recycled to an electrolytic cell if it contains water, or to an evaporator if it does not contain water. [Item 12] The following steps are included: a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; and b) Evaporation (3), A method for removing water from ammonia. [Item 13] Use of ammonia obtained by the method described in item 12 in ammonia decomposition and / or hydrogen production, using a catalyst, for example, an Fe-based catalyst. [Item 14] A method for generating electricity, wherein a gas turbine (10) a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation (3); c) Decomposition (6), and d) Cooling of the gas phase produced from decomposition (6) (7), Supply at least one of hydrogen, nitrogen, and ammonia obtained from: Here, the decomposition of ammonia (6) is carried out at a temperature of 300-700°C using an ammonia synthesis catalyst. (i) Hydrogen produced by electrolysis (2), and (ii) Hydrogen produced from ammonia decomposition (6), At least one of these contributes to the final hydrogen yield, The method wherein waste heat is recovered (11) in an ammonia evaporator (3). [Item 15] The method according to item 14, wherein some of the ammonia is decomposed (6) and some of the ammonia is bypassed (9) and supplied to a gas turbine (10). [Item 16] The use of the method described in item 14 or 15 for generating electricity by supplying at least one of hydrogen (2,7), nitrogen (7), and ammonia (7,9) to a gas turbine (10).

Claims

1. a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation of ammonia (3); c) decomposition (6); A method for decomposing ammonia, including, The decomposition of ammonia (6) is carried out at a temperature of 300 to 700°C using an ammonia synthesis catalyst, and a), b), and c) are performed in this order. The aforementioned method.

2. a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation of ammonia (3); c) Decomposition (6); and d) Cooling of the gas phase produced from decomposition (6) (7), A method for producing hydrogen from makeup ammonia (1), including, The decomposition of ammonia (6) is carried out at a temperature of 300 to 700°C using an ammonia synthesis catalyst, and a), b), c), and d) are carried out in this order. (i) Hydrogen produced by electrolysis (2), and (ii) Hydrogen produced from the decomposition of ammonia (6) The method wherein at least one of the elements contributes to the final hydrogen yield.

3. The method according to claim 1 or 2, wherein ammonia is preheated (5) before the decomposition (6) step.

4. The method according to any one of claims 1 to 3, wherein the makeup ammonia (1) contains about 0.2 to about 2% water.

5. The method according to any one of claims 1 to 4, wherein the ammonia synthesis catalyst is Fe-based.

6. The method according to any one of claims 1 to 4, wherein the catalyst used is Co, Ru, or Ni-based.

7. The method according to any one of claims 1 to 6, wherein a solution containing liquid ammonia and non-evaporating water is purged (4) from an evaporator (3) and recycled back into the supply ammonia.

8. The method according to any one of claims 1 to 7, wherein the electrolysis is high-voltage electrolysis.

9. The method according to any one of claims 1 to 8, wherein hydrogen obtained from ammonia decomposition is recycled by an external compressor.

10. The method according to any one of claims 1 to 9, wherein water is added to step (e) cooling and a scrubber is used to remove any traces of unconverted ammonia.

11. The method according to claim 10, wherein unconverted ammonia is condensed and recycled to an electrolytic cell if it contains water, or to an evaporator if it does not contain water.

12. The following steps are included: a) Electrolysis of water in feed ammonia (2), where the feed ammonia contains makeup ammonia; and b) Evaporation of ammonia (3) a) and b) are carried out in this order. A method for removing water from ammonia.

13. Use of ammonia obtained by the method of claim 12 in ammonia decomposition and / or hydrogen production, in which an Fe-based catalyst is used.

14. A method for generating electricity, wherein a gas turbine (10) a) Electrolysis of water in the supply ammonia (2), where the supply ammonia contains makeup ammonia; b) Evaporation of ammonia (3); c) Decomposition (6), and d) Cooling of the gas phase produced from decomposition (6) (7), Supply at least one of hydrogen, nitrogen, and ammonia obtained from: Here, the decomposition of ammonia (6) is carried out at a temperature of 300 to 700°C using an ammonia synthesis catalyst, and a), b), c), and d) are carried out in this order. (i) Hydrogen produced by electrolysis (2), and (ii) Hydrogen produced from ammonia decomposition (6), At least one of these contributes to the final hydrogen yield, The method wherein waste heat is recovered (11) in an ammonia evaporator (3).

15. The method according to claim 14, wherein some of the ammonia is decomposed (6) and some of the ammonia is bypassed (9) and supplied to a gas turbine (10).

16. Use of the method according to claim 14 or 15 for generating electricity by supplying at least one of hydrogen (2, 7), nitrogen (7), and ammonia (7, 9) to a gas turbine (10).

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