A reactor system for the conversion of hydrogen to ammonia and vice versa

Abstract

The present disclosure concerns a reactor system (10) designed for the conversion of hydrogen to ammonia and vice versa. The reactor system (10) is capable of operating two distinct chemical reactions under separate sets of operating conditions. The first reaction involves synthesizing ammonia from a mixture of hydrogen and nitrogen under a first set of operating conditions that favor ammonia synthesis. These conditions encompass a specific range of temperature, of pressure and of residence time. The second reaction entails cracking ammonia to produce hydrogen and nitrogen under a second set of operating conditions that favor ammonia cracking. The pressure values in the second set of conditions are lower than those in the first set. The reactor system (10) can include devices such as heating means, an ammonia storage structure (16), and various other components designed to optimize the process of ammonia synthesis and cracking.

Description

A reactor system for the conversion of hydrogen to ammonia and vice versaDescriptionTECHNICAL FIELD

[0001] The present disclosure pertains to the field of chemical engineering, specifically to reactor systems designed for the conversion of hydrogen and nitrogen to ammonia and vice versa. It provides a solution for handling hydrogen under safe conditions by synthesizing ammonia from hydrogen and nitrogen and subsequently cracking of ammonia to provide hydrogen ready for use. The reactor system is configured to operate these two different chemical reactions under two different sets of operating conditions. The reactor system can utilize a catalyst for both synthesizing ammonia and cracking ammonia or can use different catalysts. Additionally, the reactor system can be part of a transportable structure. The invention has significant applications in industries where hydrogen is used extensively and needs to be handled safely, such as in energy production, chemical manufacturing, and transportation.BACKGROUND ART

[0002] The realm of chemical reactions involving ammonia, particularly its synthesis from a mixture of hydrogen and nitrogen, and its subsequent cracking to produce hydrogen and nitrogen, is an area ripe with potential for innovation. This field has significant implications for various industries that rely on the safe handling and utilization of hydrogen under varying conditions.

[0003] The challenges associated with hydrogen storage and transportation prompt the adoption of ammonia as a hydrogen carrier, given its high hydrogen content, ease of handling, and existing infrastructures for its production, storage and transportation. The advantages of using ammonia as hydrogen carrier comprise the following: ammonia has high volumetric energy density, which means low energy consumption for transportation; ammonia can be used to transport larger amounts of energy over long distances in less space;ammonia has high capacity for hydrogen storage, 17.6 wt.%, based on its molecular structure; liquid ammonia contains 121 kg IHb / m3, which is 1.7 times more hydrogen per cubic meter than liquid hydrogen; a global infrastructure for transporting ammonia, that is safe and efficient, is already established; ammonia will be used as a transition fuel for ship transportation in the future instead of heavy fuel oil; ammonia liquefaction occurs at ambient pressure at temperatures below -33°C, while hydrogen requires temperatures of -253 °C for liquefaction.

[0004] Therefore, according to the current art, hydrogen produced through green processes comprising hydrolyzation exploiting photovoltaic energy is first converted to ammonia in a plant for ammonia synthesis, then ammonia is stored and transported to the final destination, where hydrogen is obtained from ammonia in a plant for ammonia cracking.

[0005] However, the use of ammonia as hydrogen carrier faces several challenges, comprising: energy intensive cracking process; high costs of the cracker equipment; added logistical consideration of co-siting with crackers to convert ammonia back into hydrogen.

[0006] Additionally, comparative and quantitative studies of ammonia safety reveals that it had a risk level similar to hydrogen or the common fuels like gasoline, liquefied petroleum gas (LPG), compressed natural gas (CNG) and methanol.

[0007] Accordingly, an improved system and method for handling hydrogen under safe conditions by synthesizing ammonia from hydrogen and nitrogen to address the issues of technological and economical unfeasibility of the H2-to-NH3-to-H2 value chain of the systems of the current art would be beneficial and welcomed in the technology. More in general, it would be desirable to provide methods and systems adapted to more efficiently address problems entailed by the energy-intensive process with large footprint for ammonia production and cracking to hydrogen, which hinders the feasibility of hydrogen-to-ammonia-to-hydrogen value chain.SUMMARY

[0008] In one aspect, the subject matter disclosed herein is directed to a reactor system and method for the conversion of hydrogen, together with nitrogen, to ammonia and vice versa. The reactor system is designed to operate two different chemical reactions under two distinct sets of operating conditions within a single or more reactors. This integration leads to process intensification, thereby enhancing overall process and energy efficiencies while simultaneously reducing the required footprint, which renders the H2-to-NH3-to-H2 value chain feasible.

[0009] In another aspect, the present disclosure concerns a method for handling hydrogen under safe conditions, which includes synthesizing ammonia from hydrogen and nitrogen, and subsequently cracking ammonia to provide hydrogen ready for use. The method comprises the steps of providing a reactor system for synthesizing ammonia from a mixture of hydrogen and nitrogen under a first set of operating conditions, and cracking ammonia to hydrogen and nitrogen under a second set of operating conditions. Both steps are performed in the same reactor system, preferably in the same reactor, which enables process intensification and reduces the overall footprint of the system.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein Fig.1 illustrates a schematic view of an infrastructure for hydrogen transportation through a compact and mobile reactor system for the conversion of hydrogen to ammonia and vice versa, according to an embodiment.DETAILED DESCRIPTION OF EMBODIMENTS

[0011] According to one aspect, the present subject matter is directed to a reactor system comprising one or more reactors wherein each reactor is configured to operate, in the same space at different times, two different chemical reactions under two different sets of operating conditions: a) ammonia synthesis from a mixture of hydrogen andnitrogen under a first set of operating conditions promoting ammonia synthesis reaction, the first set of operating conditions comprising a first temperature range, a first pressure range and a first residence time range and b) ammonia cracking to produce hydrogen and nitrogen under a second set of operating conditions promoting ammonia cracking reaction, the second set of operating conditions comprising a second temperature range, a second pressure range and a second residence time range, the values of the second pressure range being lower than the values of the first pressure range.

[0012] In one aspect, the object of the present disclosure is to provide a compact and mobile reactor system that can efficiently produce ammonia from hydrogen and nitrogen, and subsequently crack the ammonia to produce hydrogen when needed. This approach combines discrete ammonia formation and cracking plants into a single reactor system with a smaller footprint and enhanced efficiency.

[0013] Another aspect of the disclosure is to employ a single catalyst or multiple catalysts to promote both ammonia formation and its cracking to produce hydrogen under controlled conditions. The catalyst can be used in bulk form, such as in the form of granules or extrudes or similar forms, or coated on the internal surface of the reactor or utilized as metal foam or monolith structures to enhance catalytic productivity compared to similar-sized conventional reactors.

[0014] A further aspect of the disclosure is to supply the duty requirements for the reactions advantageously by renewable sources, including green electricity, or by exhaust gas streams from gas turbines, combustors, or combustion engines burning either ammonia or hydrogen or mixture of thereof. This approach eliminates carbon oxides emissions particularly carbon dioxide and promotes the use of sustainable energy sources.

[0015] The reactor system of the present disclosure comprises a reactor configured to operate two different chemical reactions under two different sets of operating conditions. The first reaction involves ammonia synthesis from a mixture of hydrogen and nitrogen under a first set of operating conditions promoting the ammonia synthesis reaction. The first set of operating conditions comprises a first temperature range, a first pressure range and a first residence time range. The second reaction involves am-monia cracking to produce hydrogen and nitrogen under a second set of operating conditions promoting the ammonia cracking reaction. The second set of operating conditions comprises a second temperature range, a second pressure range and a second residence time range, with the values of the second pressure range being lower than the values of the first pressure range.

[0016] The reactor system may further comprise heating means configured to heat the reactor. This feature allows for precise temperature control during the ammonia synthesis and cracking reactions, ensuring optimal reaction conditions.

[0017] An ammonia storage structure may be included in the reactor system, configured to receive ammonia produced by the reactor through the synthesis reaction, store the ammonia, and subsequently feed the ammonia to the reactor for the cracking reaction. This feature enables the safe storage and handling of ammonia, which can be later used to produce hydrogen on-demand.

[0018] Heating means may be arranged between the ammonia storage structure and the reactor and / or at the ammonia storage structure to heat and evaporate the ammonia upstream of the reactor. This feature ensures that the ammonia is in the appropriate state for the cracking reaction.

[0019] A cooling system may be arranged between the reactor and the ammonia storage structure and / or at the ammonia storage structure to condense the ammonia and store it in liquid form. This feature allows for efficient storage and transportation of ammonia. The cooling system may comprise a NH3 purification unit, such as a distillation unit, and an energy recovery unit to improve energy efficiency. In particular, expanders and heat exchangers or combination thereof could be used to recover energy from high pressure and high temperature outlet streams.

[0020] The reactor system may include one or more inlet structures configured to supply nitrogen and hydrogen to the reactor. In particular, the inlet structures are connected to external sources, from which hydrogen and nitrogen are provided to the reactor for the ammonia synthesis reaction. Moreover, the reactor system may include one or more outlet structures configured to supply nitrogen and hydrogen obtained through the ammonia cracking reaction to external users. This feature allows for theintegration of the reactor system with external hydrogen and nitrogen sources and users. An energy recovery unit can be provided between the reactor and the outlet structures, or along the reactor structures, to improve energy efficiency by recovering energy from the ammonia cracking reaction.

[0021] The inlet structure may further comprise a pre-heating system for pre-heating nitrogen and hydrogen upstream of the reactor. This feature ensures that the reactants are at the appropriate temperature for the ammonia synthesis reaction, improving reaction efficiency.

[0022] A compression system may be included for compressing nitrogen and hydrogen upstream of the reactor. This feature increases the pressure of the reactants, which is necessary for the ammonia synthesis reaction.

[0023] An ammonia purification apparatus may be located inside or downstream of the reactor to purify the ammonia produced during the synthesis reaction. The ammonia purification apparatus may comprise a cooling and distillation or filter or membrane to remove impurities from the ammonia stream.

[0024] A hydrogen purification apparatus may be located inside or downstream of the reactor to purify the hydrogen produced during the ammonia cracking reaction. The hydrogen purification apparatus may comprise a pressure swing adsorber and / or a temperature swing adsorber downstream of the reactor. Alternatively, the hydrogen purification apparatus may comprise a membrane system inside or downstream of the reactor, configured to separate hydrogen gas from nitrogen gas and non-reacted ammonia.

[0025] The reactor system may be designed as a structure configured to be transported on a means of transport, such as a ship, vessel, or truck. This feature enables the mobile deployment of the reactor system to various locations, making it suitable for decentralized hydrogen production and storage applications. The structure may also provide fuel for the means of transport, further enhancing the self-sufficiency of the system.

[0026] The reactor system may comprise at least one catalyst to promote the ammo-nia synthesis and cracking reactions. The catalyst may be configured to promote ammonia synthesis from a mixture of hydrogen and nitrogen under the first set of operating conditions and / or promote ammonia cracking to hydrogen and nitrogen under the second set of operating conditions. Additionally, at least one different catalyst may be included to specifically promote the ammonia cracking reaction under the second set of operating conditions. The catalysts may be chosen from transition metals such as Ru, Ni, Fe, Co, or a combination thereof, based on their suitability for the respective reactions.

[0027] The catalyst or catalysts may be used in bulk form, such as in the form of granules or extrudes or similar forms and / or coated on the internal surface of the reactor and / or configured as metal foam and / or as monolith structures to enhance catalytic activity and surface area. The catalyst or catalysts may form a fixed bed or a packed bed within the reactor.

[0028] The reactor may be configured as multi -tubular reactor, or shell-and-tube heat exchanger reactor, wherein the catalyst is contained, for example filled or packed, inside the tubes and heated from shell side or vice versa. In the case two different catalysts are used, a first catalyst for the synthesis of ammonia and a second catalyst for the cracking of ammonia, some tubes are used only for the synthesis reaction and contain the first catalyst, the remaining tubes being used only for the cracking reaction and contain the second catalyst. Alternatively, the ammonia synthesis catalyst can be contained inside the tube and ammonia cracking catalyst in the shell or vice versa; for example, it can be filled or packed inside the tube. Heating means can be provided inside at least some of the tubes and / or inside the shell and / or outside the shell. The reactor may be configured as a microchannel reactor, comprising a plurality of channels with a reduced hydraulic diameter and in particular as a microchannel heat exchanger reactor, also comprising heating means configured to provide heat to the channels. This configuration enhances heat transfer and improves temperature control within the reactor and heat recovery, leading to higher reaction and energy efficiencies.

[0029] The heating means of the reactor system may be supplied by renewable sources of energy, such as electric power from solar, wind, hydro, or geothermal sources. This feature promotes the use of sustainable energy sources and reduces the carbon footprint of the ammonia synthesis and cracking processes. Alternatively, theheating means may be supplied by heat from exhaust streams of a gas turbine or a burner, combustor or combustion engine burning either ammonia or hydrogen or a mixture thereof, further improving the energy efficiency of the system.

[0030] The present disclosure also provides a method for handling hydrogen under safe conditions, which includes synthesizing ammonia from hydrogen and nitrogen to allow safe handling of hydrogen in the form of ammonia, and subsequently cracking ammonia to provide hydrogen ready for use. The method comprises the steps of providing a reactor system as described above, synthesizing ammonia from a mixture of hydrogen and nitrogen under a first set of operating conditions, and cracking ammonia to hydrogen and nitrogen under a second set of operating conditions. Both steps are performed in the same reactor, which enables process intensification and reduces the overall footprint of the system.

[0031] The method may include a sub-step of providing heat to the reactor to ensure optimal reaction conditions. The method may also comprise the steps of storing ammonia from the ammonia synthesizing step in a storage structure and feeding ammonia from the storage structure to the ammonia cracking step. This feature allows for the safe storage and handling of ammonia, which can be later used to produce hydrogen on-demand.

[0032] The method may further comprise a step of heating and evaporating ammonia to be fed to the ammonia cracking step, ensuring that the ammonia is in the appropriate state for the reaction. Additionally, a step of cooling, condensing, and purifying ammonia from the synthesizing step may be included to facilitate efficient storage and transportation of ammonia. A step of compressing the ammonia from the synthesizing step may also be included to reduce the storage volume required and facilitate transportation.

[0033] The method may include the steps of supplying a mixture of nitrogen and hydrogen from external sources to the synthesizing step and supplying nitrogen and hydrogen from the ammonia cracking step to external users. This feature allows for the integration of the reactor system with external hydrogen and nitrogen sources and users. A step of pre-heating nitrogen and hydrogen before the synthesis step may be included to ensure that the reactants are at the appropriate temperature for the ammoniasynthesis reaction, improving reaction efficiency. A step of compressing nitrogen and hydrogen before the synthesizing step may also be included to increase the pressure of the reactants, which is necessary for the ammonia synthesis reaction.

[0034] The method may further comprise a step of purifying ammonia after the synthesizing step to remove impurities from the ammonia stream. A step of purifying hydrogen after the ammonia cracking step may also be included to obtain high-purity hydrogen for various applications.

[0035] The method may include the step of transporting the reactor system, including the ammonia storage apparatus, on a means of transport, such as a ship, vessel, or truck. This feature enables the mobile deployment of the reactor system to various locations, making it suitable for distributed hydrogen production and storage applications. The method may also comprise a step of providing fuel from the reactor system to the means of transport, further enhancing the self-sufficiency of the system.

[0036] The method may include the step of providing at least one catalyst to promote the ammonia synthesis and cracking reactions. The step of providing at least one catalyst may comprise choosing at least one catalyst suitable for promoting ammonia synthesis from a mixture of hydrogen and nitrogen under the first set of operating conditions. The chosen catalyst may also be suitable for promoting ammonia cracking to hydrogen and nitrogen under the second set of operating conditions. Alternatively, the step of providing at least one catalyst may comprise choosing at least one different catalyst suitable for promoting ammonia cracking to hydrogen and nitrogen under the second set of operating conditions.

[0037] The sub-step of providing heat to the reactor system, the step of heating and evaporating the ammonia to be fed to the ammonia cracking step, and the step of preheating nitrogen and hydrogen before the synthesizing step may include providing heat supplied by renewable sources of energy, such as electric power from solar, wind, hydro, or geothermal sources. This feature promotes the use of sustainable energy sources and reduces the carbon footprint of the ammonia synthesis and cracking processes.

[0038] The reactor system contains recycle means to recycle unreacted ammonia tothe reactor after separation for cracking reaction. The recycle stream will be utilized for recycling hydrogen, nitrogen and mixtures thereof to the reactor for ammonia synthesis.

[0039] In summary, the present disclosure provides a compact and mobile reactor system and method for the efficient conversion of hydrogen to ammonia and vice versa. The integration of ammonia synthesis and cracking reactions within a single reactor system leads to process intensification, enhanced energy efficiency, and a reduced footprint. The use of renewable energy sources and the ability to transport the reactor system further enhance the sustainability and flexibility of the disclosure. The reactor system and method of the present disclosure offer a viable solution for the hydrogen-to-ammonia-to-hydrogen value chain, enabling the safe and efficient storage and transportation of hydrogen in the form of ammonia.

[0040] Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase “in one embodiment” or “in an embodiment” or “in some embodiments” in various places throughout the specification is not necessarily referring to the same embodiment s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0041] When introducing elements of various embodiments the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0042] Referring now to the drawings, Fig.l shows a schematic of an infrastructure for hydrogen transportation wherein a compact and mobile reactor system is used forthe conversion of hydrogen to ammonia and vice versa. In particular, the reactor system 10 is designed to operate two different chemical reactions under two different sets of operating conditions. The first reaction is the synthesis of ammonia from a mixture of hydrogen and nitrogen. The second reaction is the cracking of ammonia to produce hydrogen and nitrogen. The reactor system 10 is configured to switch between these two reactions by changing the operating conditions and the feedstock introduced to the reactor. In particular, the reactor system 10 of Fig.1 is composed of a microchannel heat exchanger reactor 11, a type of reactor that is configured with a plurality of channels 11’ with a reduced hydraulic diameter. Different kind of reactors, in particular multi-tubular reactors or shell-and-tube heat exchanger reactors can be used. Heating means provide heat to the reactor 11. At least one catalyst is used in the reactor system10 to promote the synthesis of ammonia from a mixture of hydrogen and nitrogen under the first set of operating conditions, and / or to promote the cracking of ammonia to hydrogen and nitrogen under the second set of operating conditions. The catalyst may be chosen from transition metals, in particular Ru, Ni, Fe, Co or a combination thereof, and may form a fixed bed or a packed bed. In particular, the catalyst may be coated on the internal surfaces of the reactor, configured as metal foam, or as monolith structures, or as bulk extrude structures.

[0043] An inlet structure 12 and an outlet structure 13 respectively supply nitrogen and hydrogen from external sources 14 to the reactor 11 for the ammonia synthesis reaction, and supply nitrogen and hydrogen from the ammonia cracking reaction from the reactor 11 to external users 15. Ammonia obtained by the synthesis reaction is directed from the reactor 11 to an ammonia storage structure 16 by means of an ammonia storage inlet-outlet line 17. The same ammonia storage inlet-outlet line 17 (or a separate line) is also used to route ammonia to the reactor 11 for ammonia cracking. A first recirculation line (not shown) connects the ammonia storage inlet-outlet line 17 with the inlet structure 12, to recycle unreacted hydrogen and nitrogen back to reactor11 during the synthesis reaction. A second recirculation line (not shown) connects the outlet structure 13 with the ammonia storage inlet-outlet line 17, to recycle unreacted ammonia back to reactor 11 during the cracking reaction. According to alternative embodiments, a same recirculation line can be used to recycle either unreacted nitrogen and hydrogen from the synthesis reaction or unreacted ammonia from the cracking reaction back to the reactor 11.

[0044] The external sources 14 of hydrogen can comprise electrolysers 14’ exploiting renewable sources of energy, such as photovoltaic energy 18. Examples of renewable sources of energy include electric power from solar 18, wind 18’, hydro, and geothermal sources. In the context of the reactor system 10, these sources of energy can also be used to supply the heating means (not shown) used to heat and evaporate the ammonia upstream of the reactor 11. The heating means can be arranged between the ammonia storage structure 16 and the reactor 11, or at the ammonia storage structure 16 itself.

[0045] In the embodiment of Fig. 1, the ammonia storage structure 16 is arranged on a ship 19 and on a truck 20 and is designed to receive and store the ammonia produced by the reactor 11 during the synthesis reaction. This stored ammonia is then fed back into the reactor 11 for the cracking reaction.

[0046] A cooling system (not shown) is used to condense and purify the produced ammonia and store it in liquid form. It can be arranged between the reactor 11 and the ammonia storage structure 16, or at the ammonia storage structure 16 itself. The cooling system may include an energy recovery unit.

[0047] An ammonia purification apparatus (not shown) is arranged inside the reactor 11. Alternatively, it can be arranged downstream of the reactor 11. The ammonia purification apparatus may include a cooling and distillation or filter or membrane.

[0048] A hydrogen purification apparatus is also arranged inside the reactor 11. As the ammonia purification apparatus, it can also be arranged downstream of the reactor 11. The hydrogen purification apparatus may include a pressure swing adsorber and / or a temperature swing adsorber downstream of the reactor 11, or a membrane system inside or downstream of the reactor 11.

[0049] While aspects of the invention have been described in terms of various specific embodiments, it will be apparent to those of ordinary skilled in the art that many modifications, changes, and omissions are possible without departing form the spirt and scope of the claims. In addition, unless specified otherwise herein, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments.

Claims

CLAIMS1. A reactor system (10) comprising one or more reactors (11) each reactor (11) being configured to operate, in the same space, two different chemical reactions under two different sets of operating conditions: a) ammonia synthesis from a mixture of hydrogen and nitrogen under a first set of operating conditions promoting ammonia synthesis reaction, the first set of operating conditions comprising a first temperature range, a first pressure range and a first residence time and b) ammonia cracking to produce hydrogen and nitrogen under a second set of operating conditions promoting ammonia cracking reaction, the second set of operating conditions comprising a second temperature range, a second pressure range, and a second residence time, the values of the second pressure range being lower than the values of the first pressure range.

2. The reactor system (10) of claim 1, further comprising heating means configured to heat the one or more reactors (11), said heating means being optionally arranged inside the one or more reactors (11).

3. The reactor system (10) of claim 1 or 2, further comprising an ammonia storage structure (16) configured to receive ammonia produced by the one or more reactors (11) through the synthesis reaction, store said ammonia and subsequently feed said ammonia to the one or more reactors (11) for the cracking reaction.

4. The reactor system (10) of claim 3, further comprising heating means arranged between the ammonia storage structure (16) and the one or more reactors (11) and / or at the ammonia storage structure (16), said heating means being configured to heat and evaporate said ammonia upstream the one or more reactors (11).

5. The reactor system (10) of claim 3 or 4, further comprising a cooling system arranged between the one or more reactors (11) and the ammonia storage structure (16) and / or at the ammonia storage structure (16), said cooling system being configured to condense said ammonia and store it in liquid form.

6. The reactor system (10) of one or more of the preceding claims, further comprising inlet structures (12) configured to supply nitrogen and hydrogen fromexternal sources (14) to the one or more reactors (11) for the ammonia synthesis reaction and an outlet structure (13) configured to supply ammonia from synthesis reaction or nitrogen and hydrogen from the ammonia cracking reaction from the one or more reactors (11) to external users (15).

7. The reactor system (10) of claim 6, wherein said inlet structure (12) further comprises a pre-heating system for pre-heating nitrogen and hydrogen or ammonia upstream said one or more reactors (11).

8. The reactor system (10) of claim 6 or 7, further comprising a compression system for compressing nitrogen and hydrogen or ammonia upstream said one or more reactors (11).

9. The reactor system (10) of one or more of the preceding claims, further comprising an ammonia purification apparatus inside or downstream said one or more reactors (11), said ammonia purification apparatus preferably comprising a cooling and distillation or filter or membrane.

10. The reactor system (10) of one or more of the preceding claims, further comprising a hydrogen purification apparatus inside or downstream said one or more reactors, the said hydrogen purification apparatus preferably comprising a pressure swing adsorber and / or a temperature swing adsorber downstream said one or more reactors (11) and / or a membrane system inside or downstream said one or more reactors (11), the membrane system being configured to separate hydrogen gas from nitrogen gas and non-reacted ammonia.

11. The reactor system (10) of one or more of the preceding claims, further comprising recycle means configured to recycle unreacted ammonia from the cracking reaction and / or unreacted hydrogen and nitrogen from ammonia synthesis reaction to the one or more reactors (11).

12. The reactor system (10) of one or more of the preceding claims, further comprising a structure configured to be transported on a means of transport (19, 20), such as a ship (19) or a vessel or a truck (20).

13. The reactor system (10) of claim 12, wherein said structure configured to be transported on a means of transport (19, 20) also provides fuel for the means of transport (19, 20).

14. The reactor system (10) of one or more of the preceding claims, further comprising at least one catalyst.

15. The reactor system (10) of claim 14, wherein said at least one catalyst is configured to promote ammonia synthesis from a mixture of hydrogen and nitrogen under said first set of operating conditions.

16. The reactor system (10) of claim 14, wherein said at least one catalyst is configured to promote ammonia cracking to hydrogen and nitrogen under said second set of operating conditions.

17. The reactor system (10) of claim 14, further comprising at least one different catalyst configured to promote said ammonia cracking to hydrogen and nitrogen under said second set of operating conditions.

18. The reactor system (10) of one or more of claims 14-17, wherein said at least one catalyst and / or said at least one different catalyst is coated on the internal surface of the one or more reactors (11) and / or configured as metal foam and / or as monolith or bulk or supported shaped structures.

19. The reactor system (10) of one or more of the preceding claims, wherein the one or more reactors (11) are configured as a multi-tubular reactor, or shell-and-tube reactor, or microchannel reactor or microchannel heat exchanger reactor or combined arrangement thereof.

20. The reactor system (10) of claim 19, wherein the heating means are arranged inside at least some of the tubes or channels and / or outside the tubes or channels and / or inside the shell and / or outside the shell.

21. The reactor system of one or more of the preceding claims, wherein said heating means are supplied by renewable sources of energy, including electric power from solar, wind, hydro, geothermal and / or by heat from exhaust streams of gas turbine or a burner, or combustor, or combustion engine burning preferably either NH3or H2 or a mixture thereof.

22. A method for handling hydrogen under safe conditions, the method including synthesizing ammonia from hydrogen and nitrogen, to allow safe handling of ammonia as a hydrogen carrier, and subsequently cracking ammonia to provide hydrogen ready for use; the method comprising the steps of: providing a reactor system, comprising one or more reactors, as defined in claims 1-21; synthesizing ammonia from a mixture of hydrogen and nitrogen under a first set of operating conditions, comprising a first temperature range, a first pressure range and a first residence time; and cracking ammonia to hydrogen and nitrogen under a second set of operating conditions, comprising a second temperature range, a second pressure range, and a second residence time; wherein both steps are performed in the same reactor system.

23. The method of claim 22, wherein both said step of synthesizing ammonia and said step of cracking ammonia include a sub-step of providing heat.

24. The method of claim 22 or 23, further comprising the steps of: storing ammonia from the ammonia synthesizing step in a storage structure, and- feeding ammonia from the storage structure to the step of cracking ammonia.

25. The method of claim 24, further comprising a step of heating and evaporating said ammonia to be fed to the step of cracking ammonia.

26. The method of claim 24 or 25, further comprising a step of cooling and condensing said ammonia from said step of synthesizing ammonia.

27. The method of one or more of claims 22-26, further comprising a step of pre-heating nitrogen and hydrogen before said step of synthesizing ammonia.

28. The method of one or more of claims 22-27, further comprising a step of compressing nitrogen and hydrogen before said step of synthesizing ammonia.

29. The method of one or more of claims 22-28, further comprising a step of purifying ammonia after said step of synthesizing ammonia.

30. The method of one or more of claims 22-29, further comprising a step of purifying hydrogen after said ammonia cracking step.

31. The method of one or more of claims 22-30, further comprising the step of transporting the reactor system (10), including the ammonia storage apparatus (16), on a means of transport (19, 20).

32. The method of claim 31, further comprising a step of providing fuel from said reactor system to said means of transport (19, 20).

33. The method of one or more of claims 22-32, further comprising the step of providing at least one catalyst.

34. The method of claim 33, wherein said step of providing at least one catalyst comprises a step of choosing at least one catalyst suitable for promoting ammonia synthesis from a mixture of hydrogen and nitrogen under said first set of operating conditions.

35. The method of claim 33 or 34, wherein said step of providing at least one catalyst comprises a step of choosing at least one catalyst also suitable for promoting ammonia cracking to hydrogen and nitrogen under said second set of operating conditions.

36. The method of claim 33 or 34, wherein said step of providing at least one catalyst comprises a step of choosing at least one different catalyst suitable for promoting ammonia cracking to hydrogen and nitrogen under said second set of operating conditions.

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