Optimization system for realizing hydrogen conversion from ortho-position to para-position by using MOF (Metal Organic Framework) catalyst

Abstract

A system for effecting conversion of hydrogen from an ortho-isomer to a para-isomer is disclosed. The system comprises at least one reactor (10) comprising at least one reaction chamber (11) filled with a catalytic bed comprising a metal organic framework (MOF), characterized in that the at least one reaction chamber (11) is surrounded by a housing (12) through which a flow of cooling fluid is susceptible to pass.

Description

Technical Field

[0001] This disclosure relates to industrial-scale hydrogen production. The embodiments disclosed herein specifically relate to systems for achieving ortho-to-para hydrogen conversion using catalysts, particularly metal-organic framework catalysts. Background Technology

[0002] Hydrogen has emerged as a new energy carrier and a viable fuel route. This is not only because hydrogen is the least polluting fuel, but also because different energy sources can be used to produce hydrogen, and because hydrogen can meet many energy needs, including residential applications, hydrogen fuel cell vehicles, energy carriers, and integrated heating and power generation systems.

[0003] However, hydrogen production technology faces technical challenges, including feedstock type, conversion efficiency, carbon emissions, energy intensity of the production process, and the need for safe integration of H2 production systems with H2 purification and storage technologies.

[0004] Hydrogen production can be based on renewable energy sources (so-called green hydrogen); coal gasification and natural gas with carbon capture systems (blue hydrogen); and conventional fossil fuels (gray hydrogen). Currently, most hydrogen is produced via carbon oxide-intensive steam reforming processes. Electrolysis is a typical method that uses electric current to separate water into oxygen and hydrogen, producing green hydrogen without any direct carbon dioxide emissions. Renewable energy sources can be used to generate the necessary electricity. The cost of producing hydrogen, especially green hydrogen, is a significant barrier. Producing hydrogen using steam reforming costs approximately three times as much as producing one unit of energy using natural gas. Electrolysis, using 5 cents / kWh of energy, costs almost twice as much as producing hydrogen using natural gas. Lower hydrogen concentrations can be transported via existing natural gas pipeline infrastructure, which will also help reduce carbon oxide emissions from existing natural gas reforming facilities.

[0005] With the development of efficient hydrogen production systems, the importance of hydrogen storage technology is expected to rise sharply in the future. The most efficient transport of hydrogen is in the form of liquid hydrogen, which contains approximately 2.3 kWh / L of usable energy. However, the liquefaction and storage of liquid hydrogen is accompanied by significant losses due to boil-off gas (BOG) and its corresponding hazards, primarily caused by spontaneous ortho-para (OP) hydrogen conversion. It is well known that hydrogen has two nuclear spin isomers: ortho and para isomers (ortho hydrogen or ortho H2 and para hydrogen or para H2). At room temperature, approximately 75% of gaseous H2 is found to be in the form of ortho hydrogen, while gaseous and liquid H2 in thermodynamic equilibrium at T < 30 K contains almost 100% para H2.

[0006] The exothermic conversion from ortho-hydrogen to para-hydrogen at 20 K is approximately 254 calories / mol, while the vaporization of liquid hydrogen is endothermic at 216 calories / mol. Therefore, liquefying H2 from ortho / para-H2 mixtures for subsequent storage results in significant losses due to the ortho-to-para transition accompanied by heat release. This can be remedied by initially converting all or most of the gaseous H2 molecules to the para-H2 state. In this respect, the ortho-to-para H2 conversion is crucial for liquefaction processes, storage, and transportation, and is therefore generally also true for the widespread use of liquid hydrogen.

[0007] At low temperatures, the ortho-to-para transition in gases can occur at the rate of natural spin relaxation; however, this process can be significantly accelerated by catalytic interaction with paramagnetic centers. Typically, hydrogen liquefaction processes involve first converting the ortho-hydrogen content of the feed gas to para-hydrogen, and then liquefying the resulting para-hydrogen gas.

[0008] The most significant improvement in ortho-to-para conversion occurs through the interaction of hydrogen with paramagnetic catalysts. Hydrated iron oxide (FeO(OH), Ionex-type ortho-to-para catalysts, or similar) is commonly used to induce ortho-to-para conversion. However, these materials have poor porosity and low metal ion accessibility, making them inefficient in interacting with H2. Metal-organic frameworks (MOFs), on the other hand, offer much better porosity and accessibility, attracting considerable attention in recent years. The crystal structure of MOFs consists of structural units such as ions or metal clusters and organic linkers. Due to the wide variety of possible structural units, various properties of MOFs can be finely tuned.

[0009] Daniil M. Polyukhov et al., “Efficient MOF-Catalyzed Ortho-Para Hydrogen Conversion for Practical Liquefaction and Energy Storage”, ACS Energy Lett. 2022, 7, 4336-4341, demonstrate the remarkable potential of metal-organic frameworks (MOFs) as ortho-to-para hydrogen conversion catalysts. In particular, they discovered that Ni-MOF-74 has a specific conversion constant 145 times greater than industrially used catalysts (e.g., hydrated iron oxide), opening new horizons in hydrogen liquefaction and storage, and ultimately in the widespread use of hydrogen energy.

[0010] In other embodiments of the prior art, an apparatus for liquefying hydrogen has been proposed, comprising at least one heat exchanger comprising two separate sections, namely a first section and a second section, which are arranged to exchange heat with each other, a cooling fluid flowing into the first section, and hydrogen to be liquefied flowing in the second section, which is filled with a catalyst that participates in the conversion of para-hydrogen to ortho-hydrogen.

[0011] WO2022 / 223909 relates to an apparatus for liquefying gaseous dihydrogen, which is produced by the evaporation of liquid dihydrogen stored in at least one tank. The liquefaction apparatus includes at least one heat exchanger, at least one feed branch, and at least one cooling branch. The at least one feed branch is configured to deliver at least a portion of the gaseous dihydrogen from the tank to a gaseous dihydrogen consumer. A portion of the feed branch passes through the heat exchanger, inside which is placed a catalyst involved in the conversion of para-hydrogen to ortho-hydrogen. The at least one cooling branch includes at least one compression member. The portion of the cooling branch passing through the heat exchanger exchanges heat with a first channel to liquefy at least a portion of the dihydrogen circulating in the cooling branch and to heat the dihydrogen circulating in the feed branch.

[0012] WO2022135515A1 discloses a hydrogen liquefaction system with ortho-para hydrogen conversion function, consisting of seven hydrogen liquefaction cold boxes arranged in series. Each hydrogen liquefaction cold box includes a shell composed of an inner shell and an outer shell; the shell contains a spiral heat exchange tube for conveying hydrogen liquefaction refrigerant, a first hydrogen delivery pipe and a second hydrogen delivery pipe for conveying hydrogen / liquid hydrogen, and a catalyst feed pipe and a catalyst discharge pipe for loading or discharging the ortho-para hydrogen conversion catalyst into or out of the inner shell; the first and second hydrogen delivery pipes are respectively equipped with pipe filter nozzles; and the hydrogen liquefaction refrigerant arranged in the first hydrogen liquefaction cold box is liquefied propane, while the hydrogen liquefaction refrigerant arranged in the second to seventh hydrogen liquefaction cold boxes is entirely liquid nitrogen. This system can simultaneously perform hydrogen / liquid hydrogen conversion between the ortho and para states, ensuring that para hydrogen accounts for more than 95% during hydrogen liquefaction.

[0013] EP4089358 relates to a heat exchanger comprising a stack of plates parallel to each other and parallel to a longitudinal direction, the plates being stacked at intervals to define a first series of channels between them for flow of at least one first fluid in an overall flow direction parallel to the longitudinal direction, each channel being defined by a closing rod arranged between the plates. According to this prior art document, a filtration device is arranged in at least one channel of the first series, the filtration device extending on one hand between two adjacent plates defining the channel and on the other hand between two closing rods defining the channel, the filtration device comprising a sheet metal material selected from metal mesh, nonwoven fabric of metal fibers, sintered metal powder or metal fibers, metal foam, and microperforated plates.

[0014] Furthermore, US10035127B2 relates to a metal-organic framework (MOF) comprising multiple cores, wherein the multiple cores comprise two or more metals, metal ions, and / or metal-containing complexes, which are covalently linked together by oxide and / or carboxylic acid ester linker clusters based on 4,6-dioxo-1,3-phthalic acid ester (“m-dobdc”) linker moieties. In addition to the M2(m-dobdc)-based cores, US10035127B2 relates to methods of using it, including gas separation, gas storage, catalysis, filtering, and sensors. This disclosure shows that this MOF has a higher H2 binding capacity than other MOFs. Unlike conventional H4(dobdc) linkers (where dobdc represents 2,5-dioxo-1,4-phthalic acid ester), which have a para-carboxylic acid functional group and a para-phenolic group, H4(m-dobdc) has a meta-carboxylic acid group and a meta-phenolic group. This resulted in a previously unknown metal-organic framework structure with one-dimensional hexagonal channels and a high density of open metal coordination sites. This framework is particularly excellent for binding H2; it exhibits a higher isochoric heat of adsorption for H2 compared to other metal-organic frameworks, including M2(dobdc).

[0015] Specifically, US10035127B2 discloses MOFs containing M2(m-dobdc), where M is a metal ion, a metal, or a metal-containing complex. In the experiments presented in US10035127B2, M2(m-dobdc) was synthesized using M selected from Mg, Mn, Fe, Co, and Ni. The Mn2(m-dobdc), Fe2(m-dobdc), CO2(m-dobdc), and Ni2(m-dobdc) frameworks exhibit higher isosteric heats of adsorption for H2 compared to their metalloid M2(dobdc) counterparts. It is hypothesized that tuning the electronics around open metal coordination sites leads to these increased isosteric heats of adsorption. Neutron diffraction combined with infrared spectroscopy of D2-loaded samples was used to further confirm this stronger H2 binding enthalpy. The calculations attribute this increased binding strength to increased polarization interactions with the metal, as well as stronger feedback of H2 from delocalized π orbitals on both the metal and the connector by the metal-ligand complex.

[0016] US 2007 / 180998 A1 discloses an apparatus for selectively adsorbing a gas during an adsorption process and selectively desorbing a gas during a desorption process. A tube has porous sidewalls and end fittings are hermetically attached to each end. A particulate porous gas storage material is located inside the tube, wherein the porosity prevents material passage but allows gas passage. Selected gas from the porous inner tube, a heating coil, or a heat exchanger located inside the tube can provide heat for the desorption process, and the selected gas or heat exchanger can provide cooling during the adsorption process. The apparatus is also disclosed as being filled with MOF and therefore suitable for performing ortho-para conversion of hydrogen. Specifically, the gas to be adsorbed, such as hydrogen, flows within the inner tube and enters the tube through the internal porous sidewalls at suitable temperature and pressure, and a portion of the gas is adsorbed by the highly porous gas storage material inside the tube. The unadsorbed portion of the gas is heated by the heat generated during the adsorption process and exits the tube through the external porous sidewalls, thus acting as a convective cooling medium. The heat exchanger providing cooling during the adsorption process is located inside the tube. Therefore, the absorption of hydrogen through the inner sidewall and the desorption of hydrogen through the outer sidewall are improved. However, the space available for the cooling medium and / or heat exchanger is limited.

[0017] The devices according to the prior art are not optimized for the high ortho-to-para hydrogen conversion efficiency allowed by MOF catalysts, including MOF catalysts of the type disclosed in US10035127B2, which involve a large amount of exothermic conversion and require very efficient heat exchange between the cooling fluid and the hydrogen feed stream flowing in a section of a heat exchanger filled with catalyst.

[0018] Therefore, an improved system for utilizing MOF catalysts to achieve ortho-to-para hydrogen conversion to address the problem of increased heat exchange requirements in existing technologies would be beneficial and technically desirable. Summary of the Invention

[0019] In one aspect, the subject matter disclosed herein relates to a system for realizing the conversion of hydrogen from ortho-isomers to para-isomers, the system comprising a reactor having at least one reaction chamber filled with a catalytic bed comprising a metal-organic framework (MOF), wherein the at least one reaction chamber is surrounded by an outer shell through which a cooling fluid flows.

[0020] On the other hand, the subject matter disclosed herein relates to a system for realizing the conversion of hydrogen from the ortho isomer to the para isomer, wherein the reaction chamber has a tubular shape, and the outer shell through which the cooling fluid passes is alternatively a single conduit surrounding the reaction chamber, such as a cylindrical or prismatic conduit coaxial with the outer shell, or multiple conduits arranged side by side to surround the reaction chamber, each outer shell enclosing only one reaction chamber. The cooling fluid surrounding the reaction chamber allows for optimal heat exchange. Throughout the specification, the term "cylindrical conduit" refers to a conduit having a circular or elliptical cross-section, while the term "prismatic conduit" refers to a conduit having a polygonal cross-section, including but not limited to triangular, quadrilateral, pentagonal, hexagonal, heptagonal, and octagonal cross-sections.

[0021] On the other hand, this paper discloses a system for realizing the conversion of hydrogen from the ortho-isomer to the para-isomer, wherein the system comprises multiple reactors, each reactor having its shell in contact with the shells of adjacent reactors. Specifically, each shell may be a prismatic conduit, with at least one side of each shell sharing a corresponding side of an adjacent shell. More specifically, each shell may be a hexagonal conduit, with each side of the shell sharing a corresponding side of an adjacent shell, in order to eliminate any space between adjacent shells and thereby increase heat exchange between adjacent shells. The resulting structure of the system consists of multiple reactors, each reactor comprising a reaction chamber surrounded by shells having a hexagonal conduit shape, wherein each shell is surrounded by six shells of the same shape and size, in addition to the shells arranged around the periphery of the system.

[0022] According to an alternative aspect, this document discloses a system for realizing the conversion of hydrogen from the ortho-isomer to the para-isomer, wherein the outer shell comprises a plurality of conduits arranged side-by-side to surround each reaction chamber. Specifically, the reaction chamber may have a regular hexagonal cross-section with sides of a first length, and the conduits have regular hexagonal cross-sections with sides of the same length as the reaction chamber, in order to eliminate any space between the reaction chamber and the conduits, and between different conduits, thereby increasing heat exchange. More particularly, at least one side of the reaction chamber may be shared with a corresponding side of one of the conduits surrounding the reaction chamber, and each side of each conduit adjacent to the adjacent side of the conduit sharing the reaction chamber may be shared with the side of the adjacent conduit.

[0023] In another aspect of this disclosure, the MOF catalyst may be selected from Zn-MOF-74, Mn-MOF-74(1), Cu-MOF-74, Ni-MOF-74, and preferably Ni-MOF-74.

[0024] In another aspect of this disclosure, the MOF catalyst is a meta-MOF, namely M2(m-dobdc), wherein M is a metal, a metal ion, or a metal ion-containing complex, and m-dobdc is 4,6-dioxo-1,3-phthalic acid ester. Specifically, M2(m-dobdc) can be synthesized from M selected from Mg, Mn, Fe, and Co, and preferably M is Ni, to obtain Mn2(m-dobdc), Fe2(m-dobdc), Co2(m-dobdc), and preferably Ni2(m-dobdc), also known as Ni-meta-MOF-74.

[0025] In one aspect of this disclosure, the cooling fluid must be capable of heat exchange at 200 K and below, and may be helium, hydrogen, or a mixture thereof. Attached Figure Description

[0026] When considered in conjunction with the accompanying drawings, the embodiments disclosed in this invention and their many accompanying advantages will become better understood by referring to the following detailed description, thereby readily providing a more comprehensive understanding of them, wherein:

[0027] Figure 1 A schematic diagram of a portion of a system for converting hydrogen from the ortho-isomer to the para-isomer is shown, illustrating this portion of the system with multiple reactors; and

[0028] Figure 2 It shows Figure 1 An enlarged view of a sub-part of the system. Detailed Implementation

[0029] According to one aspect, this subject matter relates to a system for realizing the conversion of hydrogen from the ortho-isomer to the para-isomer, the system comprising at least one reactor having at least one reaction chamber having a tubular shape, wherein each reaction chamber is surrounded by a hexagonal shell. Specifically, each reaction chamber having a tubular shape is filled with a catalyst bed comprising a metal-organic framework (MOF) and is through which a hydrogen feed stream passes, thereby forming a reaction chamber for converting hydrogen from the ortho-isomer to the para-isomer, while each shell is through which a cooling fluid stream passes.

[0030] Reference will now be made in detail to embodiments of this disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of interpretation and not limitation of this disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations may be made to this disclosure without departing from its scope or substance. Throughout this specification, references to “one embodiment”, “an embodiment”, or “some embodiments” mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the disclosed subject matter. Therefore, the phrases “in one embodiment”, “in an embodiment”, or “in some embodiments” appearing in various places throughout the specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0031] When describing the elements of various implementation schemes, the articles “a,” “an,” “the,” and “the” are intended to indicate the presence of one or more elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may exist in addition to those listed.

[0032] Now refer to the attached diagram, Figure 1A schematic diagram of an exemplary portion of a system for converting hydrogen from the ortho isomer to the para isomer is shown. The system includes multiple reactors 10 for converting hydrogen from the ortho isomer to the para isomer. Specifically, each reactor 10 is surrounded by other identical reactors 10, except for an outer reactor 10. More specifically, each reactor 10 consists of a reaction chamber 11 having a tubular shape, filled with a catalytic bed comprising a metal-organic framework (MOF) for converting hydrogen from the ortho isomer to the para isomer, and operates as reaction chamber 11. Each reaction chamber 11 is surrounded by a hexagonal outer shell 12. At one end, the reaction chamber 11 is connected to a first inlet collector (not shown), and at the other end to a first outer collector (not shown). Conversely, the outer shell 12 is connected at one end to a second inlet collector (not shown), and at the other end to a second outlet collector (not shown). The first inlet collector connected to the reaction chamber 11 is separate from the second inlet collector connected to the outer shell 12. Additionally, the first outlet collector connected to the reaction chamber 11 is separate from the second inlet collector connected to the outer shell 12. Specifically, the first inlet collector is also connected to the hydrogen supply line, and the first outlet collector is connected to the hydrogen storage device. The second inlet and outlet collectors are connected to the cooling fluid refrigeration circuit. The catalyst bed in reaction chamber 11 is composed of a metal-organic framework (MOF), which can be selected from Zn-MOF-74, Mn-MOF-74(1), Cu-MOF-74, and Ni-MOF-74. In particular, the MOF catalyst can be in the form of meta-MOF, i.e., M2(m-dobdc), where M is a metal, a metal ion, or a metal ion-containing complex, and m-dobdc is 4,6-dioxo-1,3-phthalic acid ester. Specifically, M2(m-dobdc) can be synthesized using M selected from Mg, Mn, Fe, and Co, and preferably M is Ni, to obtain Mn2(m-dobdc), Fe2(m-dobdc), Co2(m-dobdc), and preferably Ni2(m-dobdc), also known as Ni-meta-MOF-74. In one particular embodiment, a high thermal conductivity material is present together with the MOF inside the reaction chamber 11. Specifically, the thermal conductivity of this material is in the range of 3000-5000 W / mK at room temperature. In one particular embodiment, the high thermal conductivity material is, for example, carbon nanotubes, fullerenes, or graphene.

[0033] Specifically, each shell 12 is a hexagonal conduit and shares a side with a corresponding side of one of the six surrounding shells 12 having the same shape and size. Thus, each shell 12 is surrounded by six shells 12, leaving no space between them. The resulting structure of the system consists of multiple reactors 10, each surrounded by six reactors 10 with shells 12 of the same shape and size, except for the reactors 10 arranged along the periphery of the system.

[0034] The system operates as follows: A hydrogen feed stream is guided through reaction chamber 11, where ortho-hydrogen is converted to para-hydrogen by a catalyst present in the chamber, generating heat. A cooling fluid, at a temperature below 80 K, is guided through outer shell 12 and exchanges heat with the hydrogen feed stream within reaction chamber 11 through the wall of chamber 11. As a result, the temperature of the hydrogen feed stream decreases while the conversion from ortho-hydrogen to para-hydrogen is completed. Simultaneously, the temperature of the cooling fluid increases. The cooling fluid is then directed to a refrigeration cycle, specifically a thermal refrigeration cycle, to be cooled before being sent back to a cooling fluid collector upstream of outer shell 12. The hydrogen feed stream from the system, formed from para-hydrogen, is collected for storage or directed to other devices.

[0035] Continue to refer to Figure 1 , Figure 2 It shows Figure 1 An enlarged view of a sub-section of the system. The same reference numerals have already been used. Figure 2 The same or corresponding parts, elements or components are shown in the text and will not be described again.

[0036] In another embodiment, the shape of the housing 12 may be, for example, a cylindrical conduit with a circular or elliptical cross-section or a prismatic conduit with any of the following cross-sections: triangular, quadrilateral, pentagonal, hexagonal, heptagonal, or octagonal. In one example, the system may have multiple housings, all having the same shape, including but not limited to prismatic conduits with triangular, quadrilateral, pentagonal, hexagonal, heptagonal, or octagonal cross-sections. In another example, the system may have a mixture of multiple housings having different shapes combined together, including but not limited to cylindrical conduits with circular or elliptical cross-sections and / or prismatic conduits with triangular, quadrilateral, pentagonal, hexagonal, heptagonal, or octagonal cross-sections.

[0037] Although various aspects of the invention have been described with reference to various specific embodiments, it will be apparent to those skilled in the art that many modifications, variations, and omissions are possible without departing from the spirit and scope of the claims.

Claims

1. A system for realizing the conversion of hydrogen from ortho-isomer to para-isomer, the system comprising at least one reactor (10), the reactor (10) comprising at least one reaction chamber (11) filled with a catalyst bed comprising a metal-organic framework (MOF), characterized in that The at least one reaction chamber (11) is surrounded by an outer shell (12) through which a cooling fluid can easily flow.

2. The system according to claim 1, wherein the reaction chamber (11) has a tubular shape.

3. The system according to claim 1 or 2, wherein the housing (12) is a conduit (12) surrounding the at least one reaction chamber (11).

4. The system according to claim 3, wherein the housing (12) is implemented as a cylindrical or prismatic conduit (12).

5. The system according to claim 4, wherein the prismatic conduit (12) has a regular hexagonal cross-section.

6. The system according to one or more of claims 3 to 5, wherein a reaction chamber (11) is arranged within each housing (12).

7. The system according to claim 6, wherein the reaction chamber (11) is coaxial with the outer shell (12).

8. The system according to one or more of claims 2 to 7, the system comprising at least two reactors (10), wherein the shell (12) of each reactor (10) contacts the shell (12) of the adjacent reactor (10).

9. The system according to claim 8, wherein each housing (12) is a prismatic conduit (12), and at least one side of each housing (12) is shared with the corresponding side of the adjacent housing (12).

10. The system according to claim 1 or 2, wherein the housing (12) is a plurality of conduits (12) arranged side by side to surround each of the at least one reaction chamber (11).

11. The system according to claim 10, wherein the at least one reaction chamber (11) has a regular hexagonal cross-section with a side length of a first length, and the conduit (12) has a regular hexagonal cross-section with a side length of the same as the length of the reaction chamber.

12. The system of claim 11, wherein the side of the at least one reaction chamber (11) is shared with the corresponding side of one of the conduits (12) surrounding the reaction chamber (11), and each side of each conduit (12) adjacent to the adjacent side of the conduit (12) shared with the reaction chamber (11) is shared with the side of the adjacent conduit (12).

13. The system according to one or more of the preceding claims, wherein the MOF is selected from Zn-MOF-74, Mn-MOF-74(1), Cu-MOF-74, Ni-MOF-74.

14. The system of claim 13, wherein the MOF is Ni-MOF-74.

15. The system according to one or more of claims 1 to 12, wherein the MOF is a meta-MOF, namely M2(m-dobdc), wherein M is a metal, a metal ion or a metal ion-containing complex, and m-dobdc is 4,6-dioxo-1,3-phthalate.

16. The system according to claim 15, wherein M is selected from Mg, Mn, Fe, Co, and Ni.

17. The system of claim 16, wherein M is Ni, and the meta-MOF is Ni-meta-MOF-74.

18. The system according to one or more of the preceding claims, wherein the high thermal conductivity material is also present in the reaction chamber (11) together with the MOF.

19. The system according to one or more of the preceding claims, wherein the cooling fluid is capable of heat exchange at 80K and below.

20. The system according to one or more of the preceding claims, wherein the cooling fluid is selected from helium, hydrogen, or mixtures thereof.

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