HYDROGEN STORAGE DEVICE

Abstract

A hydrogen storage device 200 comprises: a first vessel 230, having a first fluid inlet 210 and/or a first fluid outlet 220, having therein a thermally conducting network 240 thermally coupled to a first heater (not shown); wherein the first vessel 230 is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network 240; wherein the thermally conducting network 240 has a lattice geometry, a gyroidal geometry and/or a fractal geometry in two and/or three dimensions, comprising a plurality of nodes, having thermally conducting arms therebetween, with voids between the arms; and wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier, LOHC.

Claims

1. A hydrogen storage device comprising: a first vessel, having a first fluid inlet and/or a first fluid outlet, having therein a thermally conducting network thermally coupled to a first heater; wherein the first vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; wherein the thermally conducting network has a lattice geometry, a gyroidal geometry and/or a fractal geometry in two and/or three dimensions, comprising a plurality of nodes, having thermally conducting arms therebetween, with voids between the arms; wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier (LOHC); and wherein the thermally conducting network comprises a LOHC hydrogenation and/or dehydrogenation catalyst provided on and/or in a surface thereof.

2. The hydrogen storage device according to claim 1, wherein the hydrogen storage device is arrangeable in: a first arrangement wherein the thermally conducting network is within the first vessel; and a second arrangement wherein the thermally conducting network is outside the first vessel; wherein the first vessel comprises a circumferential releasable joint.

3. The hydrogen storage device according to claim 1, wherein the thermally conducting network comprises fluidically interconnected passageways within the arms and/or the nodes thereof, for flow therethough of a fluid.

4. The hydrogen storage device according to claim 1, wherein the thermally conducting network comprises a LOHC hydrogenation and/or dehydrogenation catalyst, provided on and/or in a surface thereof.

5. The hydrogen storage device according to claim 1, wherein the thermally conducting network has a porosity in a range from 50% to 99% by volume of the thermally conducting network.

6. The hydrogen storage device according to claim 1, wherein the thermally conducting network has a specific surface area in a range from 0.1 m.sup.−1 to 100 m.sup.−1.

7. The hydrogen storage device according to claim 1, wherein the first heater is arranged to provide a heat output in a range from 0.1 MW m.sup.−3 to 50 MW m.sup.−3, preferably in a range from 1 MW m.sup.−3 to 25 MW m.sup.−3, more preferably in a range from 2.5 MW m.sup.−3 to 10 MW m.sup.−3.

8. The hydrogen storage device according to claim 1, wherein the first heater is arranged heat the hydrogen storage material to temperature in a range from 50° C. to 400° C.

9. The hydrogen storage device according to claim 1, comprising a pump arranged to flow the hydrogen storage material through the first vessel.

10. The hydrogen storage device according to claim 1, wherein the LOHC comprises and/or is a saturated cycloalkene, aromatic, heterocyclic aromatic and/or a mixture thereof.

11. The hydrogen storage device according to claim 1, wherein the LOHC comprises and/or is a compound selected from a group consisting of: N-ethylcarbazole (NEC), monobenzyltoluene (MBT), dibenzyltoluene (DBT), 1,2-dihydro-1,2-azaborine (AB), toluene (TOL), naphthalene (NAP), benzene, phenanthrene, pyrene, pyridine, chinoline, flurene, carbazole, methanol, formic acid, phenazine, ammonia, and mixtures thereof.

12. The hydrogen storage device according to claim 1, wherein the hydrogen storage material comprises a dopant, is provided in a solvent, or both.

13. The hydrogen storage device according to claim 1, having a hydrogen storage density of at least 0.01 wt. % of the hydrogen storage material.

14. The hydrogen storage device according to claim 1, wherein the fractal geometry is selected from a group consisting of: a Quadratic Koch Island, a Quadratic Koch surface, a Von Koch surface, a Koch Snowflake, a Sierpinski carpet, a Sierpinski tetrahedron, a Mandelbox, a Mandelbulb, a Dodecahedron fractal, a Icosahedron fractal, a Octahedron fractal, a Menger sponge, a Jerusalem cube, and a 3D H-fractal.

15. The hydrogen storage device according to claim 1, wherein an effective density of the lattice geometry is uniform in a first dimension and non-uniform in mutually orthogonal second and third dimensions.

16. The hydrogen storage device according to claim 1, wherein the lattice geometry is Bravais lattice; a monoclinic lattice; an orthorhombic lattice; a tetragonal lattice; a hexagonal lattice; or a cubic lattice.

17. The hydrogen storage device according to claim 1, wherein the thermally conducting arms have a cross sectional dimension in a range from 0.1 mm to 10 mm.

18. The hydrogen storage device according to claim 1, wherein the thermally conducting network is formed, at least in part, by additive manufacturing and/or by casting.

19. The hydrogen storage device according to claim 1, comprising a thermally-conducting foam attached and/or attachable to the thermally conducting network.

20. The hydrogen storage device according to claim 1, wherein the thermally conducting network partially fills an internal volume of the first vessel, of at least 50% by volume of the first vessel, thereby defining an unfilled volume.

21. The hydrogen storage device according to claim 1, wherein the first heater comprises a Joule heater, a recirculating heater and/or a hydrogen catalytic combustor and the hydrogen storage device is arranged to interchangeably receive the Joule heater and the recirculating heater therein and/or thereon.

22. The hydrogen storage device according to claim 1, wherein the hydrogen storage device comprises a heat exchanger configured to exchange heat from and/or to the LOHC.

23. The hydrogen storage device according to claim 1, wherein the hydrogen storage device comprises thermal insulation, configured to thermally insulate the first vessel.

24. The hydrogen storage device according to claim 1, wherein the first vessel comprises a set of expansion tanks, including a first expansion tank and a second expansion tank, wherein the first expansion tank and the second expansion tank are mutually fluidically coupled.

25. A method of storing hydrogen comprising passing hydrogen gas into a hydrogen storage device according to claim 1, comprising heating the thermally conducting network using the first heater.

26. A method of providing hydrogen comprising releasing hydrogen gas from a hydrogen storage device according to claim 1, comprising heating the thermally conducting network using the first heater.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

[0060] FIG. 1A is a CAD partial cutaway perspective view of a hydrogen storage device according to an exemplary embodiment; FIG. 1B is a CAD longitudinal perspective cross-sectional view of the hydrogen storage device; and FIG. 1C is a CAD perspective view of the thermally conducting network, in more detail;

[0061] FIG. 2 schematically depicts hydrogenation and dehydrogenation of a LOHC;

[0062] FIG. 3 is a graph showing rates of heat transfer for a hydrogen storage device according to an exemplary embodiment and a comparative example;

[0063] FIGS. 4A to 4E schematically depict hydrogenation and dehydrogenation for N-ethylcarbazole (NEC), dibenzyltoluene (DBT), 1,2-dihydro-1,2-azaborine (AB), toluene (TOL) and naphthalene (NAP), respectively;

[0064] FIG. 5 schematically depicts an apparatus and a method according to an exemplary embodiment;

[0065] FIG. 6 schematically depicts the apparatus and the method of FIG. 5, in more detail;

[0066] FIGS. 7A to 7G are CAD perspective views of thermally conducting networks, particularly Bravais lattices, for a hydrogen storage device according to an exemplary embodiment;

[0067] FIG. 8A is a graph of effective thermal conductivity as a function of porosity for the thermally conducting networks of FIGS. 7A to 7G; and FIG. 8B is a graph of effective thermal conductivity as a function of surface area for the thermally conducting networks of FIGS. 7A to 7G;

[0068] FIG. 9 is a graph of concentration of dehydrogenation products of NEC as a function of time;

[0069] FIGS. 10A to 10D are graphs of concentration of dehydrogenation products of NEC as a function of time;

[0070] FIGS. 11A to 11B schematically depict computational fluid dynamic (CFD) modelling of dehydrogenation of a hydrogen storage material in a hydrogen storage device according to an exemplary embodiment;

[0071] FIG. 12A is a graph of dehydrogenation of NEC-H12 as a function of first vessel volume for different heat inputs; and FIG. 12B is a graph of conversion as a function of time for different porosities of the thermally conducting network.

[0072] FIG. 13A is a cutaway perspective view of a hydrogen storage device according to an exemplary embodiment; and FIG. 13B is a cutaway perspective exploded view of a related hydrogen storage device;

[0073] FIG. 14 is a cutaway perspective view of a hydrogen storage device according to an exemplary embodiment;

[0074] FIGS. 15A to 15C schematically depict hydrogen storage devices according to exemplary embodiments;

[0075] FIG. 16 is a photograph of a foam for a hydrogen storage device according to an exemplary embodiment;

[0076] FIG. 17 is a CAD cutaway perspective view of a thermally conducting network for a hydrogen storage device according to an exemplary embodiment;

[0077] FIG. 18A is a CAD cutaway perspective view of a hydrogen storage device according to an exemplary embodiment; FIG. 18B is a CAD axial cross-section perspective view of the hydrogen storage device; and FIG. 18C is a CAD perspective view of the thermally conducting network of the hydrogen storage device; and

[0078] FIG. 19A is a CAD perspective view of a hydrogen storage device according to an exemplary embodiment; FIG. 19B is a CAD perspective semi-transparent view of the hydrogen storage device of FIG. 19A; and FIG. 19C is a CAD axial cross-section view of the hydrogen storage device of FIG. 19A.

DETAILED DESCRIPTION OF THE DRAWINGS

[0079] FIG. 1A is a CAD partial cutaway perspective view of a hydrogen storage device 200 according to an exemplary embodiment; FIG. 1B is a CAD longitudinal perspective cross-sectional view of the hydrogen storage device 200; and FIG. 1C is a CAD perspective view of the thermally conducting network 240, in more detail.

[0080] The hydrogen storage device 200 comprises: a first vessel 230, having a first fluid inlet 210 and a first fluid outlet 220, having therein a thermally conducting network 240 thermally coupled to a first heater (not shown); wherein the first vessel 230 is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network 240; wherein the thermally conducting network 240 has a lattice geometry in three dimensions, comprising a plurality of nodes, having thermally conducting arms therebetween, with voids between the arms; and wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier, LOHC. In this example, the hydrogen storage device 200 is a dynamic hydrogen storage device 200. In this example, the first fluid inlet 210 and the first fluid outlet 220 are mutually spaced apart at opposed ends of the first vessel 230, thereby defining, at least in part, a path for flow of the hydrogen storage material and/or hydrogen therebetween, for example via the voids of the thermally conducting network 240. In this example, the first fluid inlet 210 and the first fluid outlet 220 comprise releasable couplings, thereby providing coupling thereto and uncoupling therefrom, for example repeatedly, of corresponding couplings. In this example, the lattice geometry is Bravais lattice particularly a cubic lattice specifically a primitive cubic lattice, as shown also in FIG. 7G. In this example, the thermally conducting arms have a cross sectional dimension (for example a diameter or a width) of about 0.5 mm. In this example, the thermally conducting network 240 partially fills an internal volume of the first vessel 230, of at least 90%, by volume of the first vessel 230. In this example, the thermally conducting network 240 comprises a LOHC hydrogenation and/or dehydrogenation catalyst, for example provided on and/or in a surface thereof. In this example, the thermally conducting network 240 has a porosity in a range from 75% to 95%, by volume of the thermally conducting network 240. In this example, the thermally conducting network 240 has a specific surface area in a range from 1 m.sup.−1 to 10 m.sup.−1, particularly about 7 m.sup.−1. In this example, the thermally conducting network 240 comprises a LOHC hydrogenation and/or dehydrogenation catalyst, for example provided on and/or in a surface thereof. In this example, the first heater is arranged heat the hydrogen storage material to temperature in a range from 150° C. to 300° C. In this example, the hydrogen storage device 200 comprises a pump (not shown) arranged to flow the hydrogen storage material through the first vessel 230. In this example, the hydrogen storage device 200 is a reactor.

[0081] Generally, the first vessel 230 is an elongated cylinder formed from a Ti alloy (to withstand an operating pressure of about 2 bar at a temperature of about 260° C. for dehydrogenation), having a bore extending therethrough for the first heater, particularly a Joule cartridge heater. The first fluid inlet 210 and the first fluid outlet 220 are provided with Swagelok releasable couplings. The first fluid inlet 210 is arranged at an acute angle to the axis of the first vessel and the first fluid outlet is arranged parallel to the axis, to suit the particular application.

[0082] FIG. 2 schematically depicts hydrogenation and dehydrogenation of a LOHC. Hydrogentation, from H.sub.0LOHC (also known as LOC) to H.sub.nLOHC (also known as LOHC), is typically catalysed, optionally in the presence of a solvent, at a relatively higher pressure of typically 20 to 50 bar and a temperature of typically 5° C. to 250° C. and is exothermic. H.sub.nLOHC effectively stores up to 12.1 wt. % H.sub.2, representing an energy storage density of 3.3 kWh L.sup.−1. Dehydrogentation, from H.sub.nLOHC to H.sub.0LOHC, is typically catalysed by, optionally in the presence of a solvent, at a relatively lower pressure of typically 1 bar and a temperature of typically 50° C. to 420° C. and is endothermic. Hydrogenation and dehydrogenation are reversible, for example repeatedly. Hence, LOHCs provide relatively high H.sub.2 gravimetric values (compared with conventional storage), require benign operating conditions (high pressures not needed for dehydrogenation), provide efficiency gains (no cryogenic cooling or compression efficiency losses), are zero-emission as hydrogen separated from carrier, carriers are reusable with easy off/on site regeneration using electrolysers/compressed gas and hydrogenation systems, employ similar infrastructure as existing fossil fuels and offer fast refuelling times (removal of spent LOCs and fuelling of LOHC can happen simultaneously in minutes).

[0083] FIG. 3 is a graph showing rates of heat transfer for a hydrogen storage device according to an exemplary embodiment E and a comparative example CE, for heating of water as an example, using the hydrogen storage device of FIGS. 18A to 18C. The comparative example did not include the thermally conducting network of the hydrogen storage device of FIGS. 18A to 18C but otherwise identical. For the same heat input, heating via the thermally conducting network results in a 60% reduction in time until maximum temperature is reached from commencement of heating while the maximum temperature is also about 10° C. higher.

[0084] FIGS. 4A to 4E schematically depict hydrogenation and dehydrogenation for N-ethylcarbazole (NEC), dibenzyltoluene (DBT), 1,2-dihydro-1,2-azaborine (AB), toluene (TOL) and naphthalene (NAP), respectively.

[0085] FIG. 4A schematically depicts hydrogenation and dehydrogenation for N-ethylcarbazole (NEC). Hydrogentation, from H.sub.0NEC to H.sub.12NEC, is catalysed by, for example, Pt/C at a pressure of 50 to 70 bar and a temperature of 130° C. to 180° C. and is exothermic, releasing 53 kJ mol.sup.−1 of H.sub.2. Hydrogenation catalysed by Pd and/or Ru on an Al.sub.2O.sub.3 support completes within about 180 minutes at 50 bar and 150° C. H.sub.12NEC effectively stores 5.8 wt. % H.sub.2, representing an energy storage density of 1.8 kWh L.sup.−1. Dehydrogentation, from H.sub.12NEC to H.sub.0NEC, is catalysed by, for example, Pd on an Al.sub.2O.sub.3 support at a pressure of 1 bar and a temperature of 180° C. to 230° C. and is endothermic, requiring 53 kJ mol.sup.−1 of H.sub.2 and completes within about 25 minutes at 270° C. or 250 minutes at 180° C.

[0086] Table 1 summarises properties and requirements of NEC.

TABLE-US-00001 Criteria Notes Comments Storage 5.8 wt. % (not liq.) but limit to 90% Weight percentage OK and very so 5.2 wt. %, 2.5 kWh/L and 2.25 good volume (67 g H.sub.2/L) kWh/L Availability 40 euro/kg (distillation), global Only 120 euros, price insensitive production <10,000 t/a market and limited amount needed Toxicity 5.1 TPI/mg Low Temperature 180-270° C. Lower range is preferred Energy 53.2 kJ/mol Relatively high (22% of total demand hydrogen energy) Material health hazard, low vapor pressure No liquid evaporation, but need to handling (0.05-4.4 Pa), high viscosity spec pump (5.9-121 mPas) Process Solid at ambient, restrict No extra equipment design dehydrogenation to avoid solvent, 99.99% pure no purification Stability 72 h at 270° C. (<2%), 500,000 kg Relatively stable mat/kg cat Gas flow 180° C. 68 g/Lhour, 270° C. 163.1 152 g H.sub.2/hour at 180° C. g/Lhour

[0087] FIG. 4B schematically depicts hydrogenation and dehydrogenation for dibenzyltoluene (DBT). Hydrogentation, from H.sub.0DBT to H.sub.18DBT, is catalysed by, for example, Pt on an Al.sub.2O.sub.3 support at a pressure of 20 to 50 bar and a temperature of 80° C. to 180° C. and is exothermic, releasing 65.4 kJ mol.sup.−1 of H.sub.2. Hydrogenation catalysed by Pt and/or Ru on an Al.sub.2O.sub.3 support completes within about 240 minutes at 50 bar and 150° C. H.sub.18DBT effectively stores 6.2 wt. % H.sub.2, representing an energy storage density of 1.9 kWh L.sup.−1. Dehydrogentation, from H.sub.18DBT to H.sub.0DBT, is catalysed by, for example, Pt on a C support at a pressure of 1 to 5 bar and a temperature of 290° C. to 310° C. and is endothermic, requiring 65.4 kJ mol.sup.−1 of H.sub.2 and completes within about 120 minutes at 310° C.

[0088] Table 2 summarises properties and requirements of DBT.

TABLE-US-00002 Criteria Notes Comment Storage 6.2 wt. %, 1.9 kWh/L, but limited to 6 Ideal weight and volume (54 gH2/L) wt. % and 1.8 kWh/L Availability 4 euro/kg Less than 12 euros for material Toxicity 13.8 TPI/mg Relatively low Temperature 310° C. Prefer about 200° C., but usable Energy 65.4 kJ/mol Higher than used to (27% of total demand hydrogen energy) Material Environmental hazard, low vapor No liquid evaporation, but need to handling pressure (0.04-0.07 Pa), high spec pump viscosity (44.1-258 mPas) Process Liquid, no purification No extra equipment design Stability 72 h at 270° C. (<0.01%), 14,000 h Highly stable (hydrogenation), 8,000 h (dehydrogenation) Gas flow 270° C. 11.3 g/Lhour, 310° C. 27.5 Est. 76 gH.sub.2/hour, need 100 gH.sub.2/hour g/Lhour

[0089] FIG. 4C schematically depicts hydrogenation and dehydrogenation for 1,2-dihydro-1,2-azaborine (AB). AB is a heterocyclic molecule including B and N heteroatoms. Hydrogentation, from H.sub.0AB to H.sub.6AB, is catalysed by, for example, Pd on a C support, in the presence of a solvent such as tetrahydrofuran, at a pressure of 10 bar and a temperature of 80° C. and is exothermic, releasing 35.9 kJ mol.sup.−1 of H.sub.2. Hydrogenation catalysed by Pd on a C support, with a two-step addition by hydride (KH) and proton (HCl) completes to about 95% at 10 bar and 90° C. H.sub.6AB effectively stores 7.1 wt. % H.sub.2, representing an energy storage density of 2.4 kWh L.sup.−1. Dehydrogenation, from H.sub.6AB to H.sub.0AB, is catalysed by, for example, FeCl.sub.2 or CoCl.sub.2, in the presence of a solvent such as tetrahydrofuran at a pressure of 1 bar and a temperature of 80° C. and is endothermic, requiring 35.9 kJ mol.sup.−1 of H.sub.2 and completes within about 20 minutes (FeCl.sub.2) and about 10 minutes (CoCl.sub.2) at 1 bar and 80° C.

[0090] Table 3 summarises properties and requirements of AB.

TABLE-US-00003 Criteria Notes Comments Storage 7.1 wt. % 2.4 kWh/L, tetrahydrofuran Addition of solvent has a detrimental solvent gives 2.3 wt. % and 0.8 effect (24 gH2/L) kWh/L, trimerization gives 4.7 wt. % and 1.6 kWh/L Availability Price of Boron — Toxicity Low Low Temperature 80° C. Very good Energy 35.9 kJ/mol Low enthalpy, coupling of demand exothermic hydrogenation of B and N Material high vapor pressure (18,300 Pa), Difficult storage with low vapor handling low viscosity (0.55-0.57 mPas) pressure Process Tetrahydrofuran solvent, low Hydrogen purification with solvent, design flashpoint, multi stage can ignite on hot surface hydrogenation Stability Air and moisture stable, thermally Highly stable stable up to 150° C., no side reactions Gas flow 132.5 gH.sub.2/Lh CoCl.sub.2, 66.2 gH.sub.2/Lh More than enough FeCl.sub.2 (with solvent)

[0091] FIG. 4D schematically depicts hydrogenation and dehydrogenation for toluene (TOL). Hydrogentation, from H.sub.0TOL to H.sub.0TOL, is catalysed by, for example, Pt on a CBV-780 support, at a pressure of 30 bar and a temperature of 120° C. and is exothermic, releasing 68.3 kJ mol.sup.−1 of H.sub.2. Hydrogenation catalysed by Pt on a zeolite support occurs at 30 bar and 120° C. while hydrogenation catalysed by NiCoMo on a zeolite support completes in about 2 hours at 20 bar and 200° C. Dehydrogenation, from H.sub.0TOL to H.sub.0TOL, is catalysed by, for example, K—Pt on an Al.sub.2O.sub.3 support at a pressure of 1 bar and a temperature of 250 to 450° C. and is endothermic, requiring 68.3 kJ mol.sup.−1 of H.sub.2. Dehydrogenation catalysed by Pt or Ni on an Al.sub.2O.sub.3 support occurs at about 350 to 450° C. Dehydrogenation catalysed by Raney-Ni gives a yield of about 65% after about 30 minutes at 250° C., but with isomerization and disproportionation. Dehydrogenation catalysed by K—Pt on an Al.sub.2O.sub.3 support gives a yield of about 95% at 320° C.

[0092] Table 4 summarises properties and requirements of TOL.

TABLE-US-00004 Criteria Notes Comments Storage 6.2 wt. % and 1.6 kWh/L, with limit of Good (45 gH.sub.2/L) 95% it is 5.9 wt. % and 1.5 kWh/L Availability 0.3 euros per kg Very cheap Toxicity 19.3 TPI/mg, probably toxic to reproduction Temperature 250-450° C. (310° C.) Energy 68.3 kJ/mol Higher than we are used to (29% of demand total hydrogen energy) Material Flammable, health hazard, irritating Lots of dangers and need to deal handling to eyes and skin, dangerous to with vapor pressure environment, high vapor pressure (7880-10900 Pa), low viscosity (0.6-0.7 mPas) Process Hydrogen purification, toluene gas Hydrogen purification from toluene, design means use of fixed bed, low ignition chance of ignition temp of product Stability Side reactions, catalyst Issues deactivation, can add rhenium, 6,000 h with K—Pt/Al.sub.2O.sub.3. Gas flow 61.6 gH.sub.2/Lh More than enough

[0093] FIG. 4E schematically depicts hydrogenation and dehydrogenation for naphthalene (NAP). Hydrogentation, from H.sub.0NAP to H.sub.10NAP, is catalysed by, for example, Pd on a MCM-41 support, in the presence of a solvent such as toluene, at a pressure of 69 bar and a temperature of 200° C. to 300° C. and is exothermic, releasing 66.3 kJ mol.sup.−1 of H.sub.2. Hydrogenation catalysed by aluminium mobile composition of matter (Al-MCM), completes in about 150 minutes at 69 bar and 300° C. or about 480 minutes at 69 bar and 200° C. H.sub.6NAP effectively stores 7.3 wt. % H.sub.2, representing an energy storage density of 2.17 kWh L.sup.−1. Dehydrogentation, from H.sub.10NAP to H.sub.0NAP, is catalysed by, for example, Pt—Re on a C support, in the presence of a solvent such as toluene at a pressure of 1 bar and a temperature of 210° C. to 320° C. and is endothermic, requiring 66.3 kJ mol.sup.−1 of H.sub.2 and completes within about 150 minutes (Pt on a C support) and about 120 minutes (Pt—Re) at 1 bar and 280° C.

Table 5 summarises properties and requirements of AB.

TABLE-US-00005 Criteria Notes Comments Storage 7.4 wt. % and 2.2 kWh/L, toluene Adding solvent is detrimental solvent makes 3.8 wt. % and 1.1 (33 gH.sub.2/L) kWh/L Availability 0.6 euros per kg Very cheap Toxicity Highly toxic 45.8 TPI/mg and Very toxic probably carcinogenic. Temperature 280° C. Relatively high Energy 66.3 kJ/mol Higher than we are used to (28% of demand total hydrogen energy) Material Flammable, health hazard, irritating Handling and storage dangers handling to eyes and skin, dangerous to environment, toxic and corrosive, low vapor pressure (235-540 Pa), low viscosity (2-3 mPas) Process Solid at RT, need to add toluene, Hydrogen purification from toluene, design low ignition temperature chance of ignition Stability Stable to 450° C., high temperature Manageable within used causes catalyst deactivation and temperature range carbon deposits Gas flow 16.1 gH.sub.2/Lh Unlikely to be enough

[0094] FIG. 5 schematically depicts an apparatus and a method according to an exemplary embodiment. LOHC is pumped, by pump 2, from LOHC container 1 through flexible pipe 3, pipe adapter 4, check valve 4 and Swagelok piping 6 into reactor 7, corresponding with the hydrogen storage device 200 described with reference to FIGS. 1A to 1C. The LOHC received in the reactor 7 is heated by first heater 8, particularly a cartridge heater, via the thermally conducting network as the LOHC flows therethrough, from first fluid inlet to first fluid outlet, thereby releasing hydrogen. The reactor 7 is thermally insulated by insulation, to reduce heat losses and hence improve an efficiency of dehydrogenation. LOC and hydrogen exit the reactor through the first fluid outlet and Swagelok piping 9 into an enclosed gas beaker 10. LOC collects in the beaker while hydrogen gas flow outwards to a flow controller and hence to a hydrogen fuel cell, for example.

[0095] FIG. 6 schematically depicts the apparatus and the method of FIG. 5, in more detail.

[0096] FIGS. 7A to 7G are CAD perspective views of thermally conducting networks, particularly Bravais lattices, for a hydrogen storage device according to an exemplary embodiment. Dimensions of the outlining cubes are identical, for comparison. FIG. 7A shows cubic diamond lattice (face centered cubic); FIG. 7B shows a single unit cell of a body-centred cubic lattice; FIG. 7C shows cubic fluorite lattice (face centered cubic); FIG. 7D shows eight unit cells (2×2×2) of a body-centred cubic lattice, having arms of a first diameter; FIG. 7E shows eight unit cells (2×2×2) of a body-centred cubic lattice, having arms of a second diameter, greater than the first diameter; FIG. 7F shows eight unit cells (2×2×2) of a body-centred cubic lattice, having arms of a third diameter, greater than the second diameter; and FIG. 7G shows sixty four unit cells (4×4×4) of a body-centred cubic lattice, having arms of a fourth diameter, similar to the first diameter. Porosity and surface area of the thermally conducting networks increase from FIG. 7A to FIG. 7G

[0097] FIG. 8A is a graph of effective thermal conductivity as a function of porosity for the thermally conducting networks of FIGS. 7A to 7G; and FIG. 8B is a graph of effective thermal conductivity as a function of surface area for the thermally conducting networks of FIGS. 7A to 7G. Particularly, FIG. 8A shows that the effective thermal conductivity decreases linearly as a function of porosity. Particularly, FIG. 8B shows that the effective thermal conductivity increases as a function of surface, with a significant upwards step from D to F via E. A primary determining factor for enhanced thermal conductivity is lattice porosity. Secondary factors include surface area. Lattice G is preferred as there is a big increase in surface area for very little volume sacrifice (i.e. porosity sacrifice), compared with lattice F.

[0098] FIG. 9 is a graph of concentration of dehydrogenation products of NEC as a function of time. NECH12 undergoes a stepwise dehydrogenation according to the following reactions, producing the following species and hydrogen:

[00001]$\begin{array}{cc}\mathrm{NECH}12\stackrel{k1}{.fwdarw.}\mathrm{NECH}8+2H_2& \left(1\right)\end{array}$$\begin{array}{cc}\mathrm{NECH}8\stackrel{k2}{.fwdarw.}\mathrm{NECH}4+2H_2& \left(2\right)\end{array}$$\begin{array}{cc}\mathrm{NECH}4\stackrel{k3}{.fwdarw.}\mathrm{NEC}+2H_2& \left(3\right)\end{array}$

[0099] The respective rate equations are:

[00002]$\begin{array}{cc}r1=\frac{{\mathrm{dC}}_{\mathrm{NECH}12}}{\mathrm{dt}}=-k1C_{\mathrm{NECH}12}& \left(4\right)\end{array}$$\begin{array}{cc}r2=\frac{{\mathrm{dC}}_{\mathrm{NECH}8}}{\mathrm{dt}}=-k2C_{\mathrm{NECH}8}& \left(5\right)\end{array}$$\begin{array}{cc}r3=\frac{{\mathrm{dC}}_{\mathrm{NECH}4}}{\mathrm{dt}}=-k1C_{\mathrm{NECH}4}& \left(6\right)\end{array}$

[0100] These equations may be solved according to OD and 3D models. Data for the models were obtained from: Stark et al. (2015) Liquid organic hydrogen carriers: thermophysical and thermochemical studies of carbazole and fully hydrogenated derivatives (https://doi.org/10.1021/acs.jecr.5b01841); Mehranfar et al. (2105) N-ethyl carbazole-doped fullerene as a potential for hydrogen storage, a kinetics approach (https://doi.org/10.1039/C5RA09264G); and Wang et al. (2014) A comparative study of catalytic dehydrogenation of perhydro-N-ethylcarbazole over noble metal catalysts (https://doi.org/10.1016/j.ijhydene.2014.09.123). The experimental details from the latter were included in a OD multi component batch reaction model, including first vessel size and concentrations and temperature of 180° C. FIG. 9 shows the resulting concentrations of each species from equations (1) to (3) above. The species are successively formed before decomposing.

[0101] FIGS. 10A to 10D are graphs of concentration of dehydrogenation products of NEC as a function of time. Particularly, FIGS. 10A to 10D show experimental data for dehydrogenation products of NEC, catalysed by 5 wt. % of Rh, Ru, Pt and Pd, respectively, based on Wang et al. Good agreement between the model of FIG. 9 and experimental data of FIGS. 10A to 10D, particularly with respect to rates and concentrations.

[0102] FIGS. 11A to 11B schematically depict computational fluid dynamic (CFD) modelling of dehydrogenation of a hydrogen storage material in a hydrogen storage device according to an exemplary embodiment. FIGS. 11A to 11B show end perspective views of a 3D model of dehydrogenation in a cylindrical first vessel according to an embodiment, in which the loaded LOHC flows into the first vessel from the left while LOC and hydrogen exit from the right, as shown by the arrows. The colours indicate concentration of hydrogen, with blue relatively low (left) and red relatively high (right). Particularly, FIG. 11A shows both the flux of material into and out of the system (blue arrows) and the resulting concentration of H.sub.2. It can be seen that the concentration of H.sub.2 starts at 0 mol m.sup.−3, and increases as the LOHC is heated. This behaviour is as expected. FIG. 11B shows the resulting pressure (in bar) in the first vessel as a result of H.sub.2 generation. The concentration is used in the ideal gas law to generate hydrogen pressure. The maximum pressure calculated (1.6 bar) is in line with literature.

[0103] FIG. 12A is a graph of dehydrogenation of NEC-H12 as a function of first vessel volume for different heat inputs; and FIG. 12B is a graph of conversion as a function of time for different porosities of the thermally conducting network. Particularly, FIG. 12A was determined by plug flow reactor (PFR) steady state modelling, thereby modelling dehydrogenation in terms of first vessel volume and chemical conversion. A reactor volume can be determined for a desired conversion. However, this is highly dependent on inlet concentrations and flow rates. Particularly, FIG. 12B shows the effect of porosity of the thermally conducting network, determined by modelling. The porosity affects every stage of the model—from fluid flow, to temperature distribution. A sample of the energy balance equations are shown below (after https://digital.csic.es/bitstream/10261/155394/1/metal%20hydride.pdf):

[00003]$\frac{\partial \stackrel{\_}{\rho c_p}T}{\partial t}+\nabla .Math.\left({\rho }^{ℊ}{c}_p^{ℊ}\stackrel{.fwdarw.}{u}T\right)=\nabla .Math.\left(k^{\mathrm{eff}}\nabla T\right)+S_T$$k^{\mathrm{eff}}=\left(1-\epsilon \right)k^m+\epsilon k^{ℊ}$$\stackrel{\_}{\rho c_p}=\left(1-\epsilon \right){\rho }^m{c}_p^m+{\mathrm{\epsilon \rho }}^{ℊ}{c}_p^{ℊ}$$S_T=S_m\left[\Delta H-T\left(c_p^{ℊ}-c_p^m\right)\right]$

[0104] It can be seen that the temperature is highly dependent on c epsilon (porosity). Therefore, changing porosity changes the impact of the lattice on the model. As epsilon tends to 0, the lattice becomes less porous and as epsilon tends to 1, it becomes more porous. By changing epsilon we can understand the impact of our heat transfer network on temperature evolution and H.sub.2 concentration. FIG. 12B shows that increasing porosity has a preferential impact on the overall conversion, shown here as the molar concertation of H.sub.2.

[0105] FIG. 13A is a cutaway perspective view of a hydrogen storage device 200 according to an exemplary embodiment. The hydrogen storage device 200 comprises: a first vessel 230, having a first fluid inlet 210 and a first fluid outlet 220, having therein a thermally conducting network 240 thermally coupled to a first heater (not shown); wherein the first vessel 230 is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network 240; wherein the thermally conducting network 240 has a lattice geometry in three dimensions, comprising a plurality of nodes, having thermally conducting arms therebetween, with voids between the arms; and wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier, LOHC. In this example, the hydrogen storage device 200 is a static hydrogen storage device 200.

[0106] In this example, the vessel 230 is generally cylindrical, having a generally internally dished first end and a flanged second end opposed thereto, and having a single aperture providing both the first fluid inlet 210 and the first fluid outlet 220. In other words, the vessel 230 is can-shaped. An inner wall portion 230I of the vessel 230 provides an axial cylindrical, elongate blind passageway P, arranged to optionally receive a second heater 300B (not shown) of the set of heaters 300, particularly a cartridge heater (not shown), that extends from the first end towards the second end and that is coaxial with an outer wall portion 230O of the vessel 230. Blind passageways in the second end are arranged to receive thermocouples TC. In this example, the first heater 300A is provided by a recirculating heater, for example heated using waste heat from a fuel cell coupled thereto, and includes a double helix heating tube 350, having an inlet 310 and an outlet 320, in thermal contact with the thermally conducting network 20, which is arranged between the inner 350I and outer 350O helices of the heating tube 350. The double helix heating tube 350 extends from the second end towards the first end is coaxial with an outer wall portion 230O of the vessel 230. The inner 350I and outer 350O helices of the double helix heating tube 350 are directly in thermal contact with the inner wall portion 230I and the outer wall portion 230O of the vessel 230, respectively. A pressure gauge PG is provided in the second end. The second end is mechanically releasably coupled to the vessel 230, using mechanical fasteners.

[0107] In this example, the thermally conducting network 240 has a lattice geometry in three dimensions, in which generally each node is connected by four arms to four other nodes, respectively, in an axially adjacent preceding layer, such that generally each node is thus connected by eight arms to eight other nodes, four nodes in the axially adjacent preceding layer and four nodes in an axially adjacent proceeding layer. Nodes proximal the inner 350I and outer 350O helices of the heating tube 350 are in mutual thermal contact therewith. In this example, an effective density of the lattice geometry is uniform in a first dimension, particularly axially, and non-uniform in mutually orthogonal second and third dimensions, particularly radially. In this example, the thermally conducting network 240 has a porosity of at least 90%. In this example, the thermally conducting network 240 is formed from an aluminium alloy. In this example, the thermally conducting network 240 comprises inner 240I and outer 240O portions, having annular shapes. The outer portion 240O is received in thermal contact with and between the inner 350I and outer 350O helices of the double helix heating tube 350 while the inner portion 240I is received in thermal contact with and within the inner helix 350I.

[0108] FIG. 13B is a cutaway perspective exploded view of a related hydrogen storage device 200. In contrast with the hydrogen storage device 200 of FIG. 13A, the thermally conducting network 240 of the hydrogen storage device 200 of FIG. 13B comprises inner 240I, middle 240M and outer 240O portions. The inner portion 240I has a cylindrical shape and the middle 240M and outer 240O portions have annular shapes. The outer portion 240O is received in thermal contact and without the outer 350O helices of the double helix heating tube 350, the middle portion 240M is received in thermal contact with and between the inner 350I and outer 350O helices while the inner portion 240I is received in thermal contact with and within the inner helix 350I.

[0109] FIG. 14 is a cutaway perspective view of a hydrogen storage device according to an exemplary embodiment. The hydrogen storage device 200 is generally as described with respect to the hydrogen storage devices 200 of FIGS. 13A and 13B and like reference signs denote like features.

[0110] In contrast with the hydrogen storage device 200 of FIGS. 13A and 13B, the hydrogen storage device 200 does not include the inner wall portion 230I of the vessel 230 of FIGS. 13A and 13B and does not include blind passageways in the second end to receive thermocouples. In contrast with the hydrogen storage device 200 of FIGS. 13A and 13B, the thermally conducting network 240 is cylindrical, to be received in thermal contact with the outer wall portion 230O of the vessel 230. In contrast with the hydrogen storage device 200 of FIGS. 13A and 13B, the inner 350I and outer 350O helices of the double helix heating tube 350 are integrated within the thermally conducting network 240. Hence, the inner 350I and outer 350O helices of the double helix heating tube 350 are mutually spaced apart from and only indirectly in thermal contact with the outer wall portion 230O of the vessel 230, respectively, via the thermally conducting network 240. In this example, the hydrogen storage device 200 includes a bed compression disc 231, internal to the vessel 230 proximal the first end and bed compression disc bolts 232 mechanically coupled thereto, extending through the first end, for uniaxially compressing the hydrogen storage material to improve thermal contact with the thermally conducting network. O-rings 233 are arranged in the outer wall portion 230O to prevent loss of the hydrogen storage material during compression thereof.

[0111] FIGS. 15A to 15C schematically depict thermally conducting networks for a hydrogen storage device according to an exemplary embodiment. Particularly, FIG. 15 shows three alternative fractal networks (A) Gosper Island; (B) ‘Snowflake’ design; and (C) Koch Snowflake for the thermally conducting network of the hydrogen storage device 200. The 2D radially symmetric fractal patterns extend axially. Axial cross-sections, midpoint radial cross-sections and perspective views for the fractal networks are shown.

[0112] FIG. 16 is a photograph of a foam for a hydrogen storage device according to an exemplary embodiment. FIG. 16 shows a photograph of voids (i.e. open space) in a metal foam, particularly aluminium foam. The aluminium foam is produced from 6101 aluminium alloy, retaining 99% purity of the parent alloy. The foam has a reticulated structure in which cells (i.e. pores) are open and have a dodecahedral shape. The foam has a bulk density of 0.2 gcm.sup.−3; a porosity of 93% porosity and about 8 pores/cm.

[0113] FIG. 17 is a CAD cutaway perspective view of a thermally conducting network for a hydrogen storage device according to an exemplary embodiment. Particularly, the thermally conducting network is gyroidal.

[0114] FIG. 18A is a CAD cutaway perspective view of a hydrogen storage device 200′″ according to an exemplary embodiment; FIG. 18B is a CAD axial cross-section perspective view of the hydrogen storage device 200′″; and FIG. 18C is a CAD perspective view of the thermally conducting network of the hydrogen storage device 200′″. In this example, the first vessel 201′″ has an internal volume of about 50 cm.sup.3, thereby providing a hydrogen storage capacity of about 2.5 g H.sub.2. FIG. 18C is a CAD radial cross-section of a thermally conducting network of the hydrogen storage device of FIG. 12. Generally, the lattice geometry is as described with respect to FIG. 1C.

[0115] In more detail, in this example, the hydrogen storage device 200′″ comprises: a first vessel 201″, having a first fluid inlet 208′″ and/or a first fluid outlet 209′″, having therein a thermally conducting network 204′″ thermally coupled to a first heater (not shown); wherein the first vessel 201′″ is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network 204′″; wherein the thermally conducting network 203′″ has a lattice geometry in three dimensions, comprising a plurality of nodes, having thermally conducting arms therebetween, with voids between the arms; and; and wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier, LOHC.

[0116] In this example, the first vessel 201′″ is generally cylindrical, having a generally flat first end and a necked second end opposed thereto, and having a single aperture providing both the first fluid inlet 208′″ and the first fluid outlet 209′″. In other words, the first vessel 201″ is bottle-shaped. An inner wall portion 201I″ of the first vessel 201″ provides an axial cylindrical, elongate blind passageway 210′″, arranged to receive a first heater 206′″ (not shown), that extends from the first end towards the second end and that is coaxial with an outer wall portion 201O″ of the first vessel 201′″. A second blind passageway in the first end is arranged to receive a thermocouple (not shown).

[0117] In this example, the thermally conducting network 204′″ has a lattice geometry in three dimensions. In this example, an effective density of the lattice geometry is uniform in a first dimension, particularly axially, and non-uniform in mutually orthogonal second and third dimensions, particularly radially. Particularly, the effective density decreases radially outwards, such that there is faster heat transfer proximal the passageway 210′″ and hence the first heater. In this example, the thermally conducting network 204′″ is formed from an aluminium alloy. Alternatively, the thermally conducting network 204′″ may be formed from copper, respective alloys thereof such as brass or bronze alloys, and/or stainless steel, as described previously.

[0118] FIG. 19A is a CAD perspective view of a hydrogen storage device 300 according to an exemplary embodiment; FIG. 19B is a CAD perspective semi-transparent view of the hydrogen storage device 300 of FIG. 19A; and FIG. 19C is a CAD axial cross-section view of the hydrogen storage device 300 of FIG. 19A.

[0119] In this example, the hydrogen storage device 300 comprises: a first vessel 330, having a first fluid inlet 310 and/or a first fluid outlet 320, having therein a thermally conducting network 340 optionally thermally coupled to a first heater and/or a first cooler; wherein the first vessel 330 is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network 340; wherein the thermally conducting network 340 has a fractal geometry in two dimensions, comprising a plurality of nodes 341, having thermally conducting arms 342 therebetween, with voids V between the arms 342; and wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier, LOHC. In this example, the thermally conducting network 340 comprises fluidically interconnected passageways 343 therein, within the arms 342 and the nodes 341 thereof, for flow therethough of a fluid. In this example, the first vessel 330 is generally cylindrical, having dished ends. In this example, a passageway 350, provided by a tube having a circular cross-section, extends between the dished ends longitudinally. In this example, the thermally conducting network 240 partially fills an internal volume of the first vessel 330. In this example, the thermally conducting network 240B is thermally coupled to at least a part of an internal surface of the first vessel 230B and an external surface of the tube.

Alternatives

[0120] Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

Summary

[0121] In summary, the invention provides a hydrogen storage device comprising: a first vessel, having a first fluid inlet and/or a first fluid outlet, having therein a thermally conducting network thermally coupled to a first heater; wherein the first vessel is arranged to receive therein a hydrogen storage material in thermal contact, at least in part, with the thermally conducting network; wherein the thermally conducting network has a lattice geometry, a gyroidal geometry and/or a fractal geometry in two and/or three dimensions, comprising a plurality of nodes, having thermally conducting arms therebetween, with voids between the arms; and wherein the hydrogen storage material comprises and/or is a liquid organic hydrogen carrier, LOHC.

[0122] In this way, control for charging and/or release (also known as loading and unloading, respectively) of hydrogen from the hydrogen storage material is improved because the flow of heat through the thermally conducting network provides for faster, more homogenous, more accurate and/or more precise heating and cooling of the hydrogen storage material in thermal contact therewith. In this way, release of hydrogen is with less delay or lag time, thereby providing hydrogen more responsively, for example in response to a demand. Conversely, storage of hydrogen is more efficient, allowing faster mass or volume flow of the hydrogen storage material through the hydrogen storage device.

DISCLOSURE

[0123] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0124] All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at most some of such features and/or steps are mutually exclusive.

[0125] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0126] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.