Method for preparing metal borohydride from metal boron oxide

Abstract

A metal boron oxide Me(BO2) n Preparation of metal borohydride Me(BH4) n A method wherein Me is a metal or a molecule that exhibits metal-like behavior and can function as a metal, and n is an integer that can be correlated with the valence of the metal, wherein in a first fluidized bed step, a metal boron oxide is provided in a first fluidized bed. The first fluidized bed uses a gas selected from at least one of nitrogen N2 gas and a rare gas, optionally, the rare gas is selected from at least one of helium He; neon Ne; argon Ar; and xenon Xe, and oxygen atoms are removed from the metal boron oxide to provide a metal boride MeB. n The particles, which may be ions, are fluidized in an environment, particularly pressure and temperature. In a subsequent second fluidized bed step, the metal boride particles are provided in a second fluidized bed, which is fluidized using hydrogen gas, H2 gas, in an environment in which the hydrogen gas chemically reacts with the metal boride particles to provide metal borohydride.

Description

Technical Field

[0001] The present invention relates to a method for producing metal borohydrides from metal boron oxides (metal boron oxides) and an apparatus for carrying out the method. Background Art

[0002] Hydrogen (H2) is widely considered one of the most promising energy sources of the future due to its high energy density and considerable abundance and availability in nature. In addition, H2 is considered one of the cleanest fuels because the only waste product after its use is water.

[0003] However, despite extensive technological efforts over the past few decades, the costs involved in producing, storing, and transporting hydrogen remain high and have hindered its widespread use as a fuel. This is especially true when hydrogen is used in gaseous form, as its very low specific gravity means that additional costs are required to continuously cool or compress it in containers suitable for storing this highly reactive element.

[0004] In view of this, the use of metal borohydrides Me(BH4) has recently been developed n Promising methods and systems for storing hydrogen, from which H2 can be released by hydrolysis.

[0005] In metal borohydride Me(BH4) n In the reaction with water, many reaction products such as Me(BO2) n and possibly MeCl n A spent fuel mixture can be generated, which can also contain other compounds of metals, boron and oxygen. Some of these reaction products can be recycled again. However, it is not possible to regenerate metal borohydride Me(BH4) starting from the spent fuel mixture. n The known methods are still very inefficient in terms of the energy required and the reconversion rate from spent fuel to metal borohydrides. Summary of the Invention

[0006] An object of the present invention is to provide an efficient method for converting the hydrolysis products of metal borohydrides back into metal borohydrides.

[0007] It is another or alternative object of the present invention to provide an efficient process for converting the hydrolyzate of a metal borohydride back into a metal borohydride using at least one fluidized bed.

[0008] It is another or alternative object of the present invention to provide an efficient process for converting metal boron oxides to metal borohydrides using at least one fluidized bed.

[0009] It is another or alternative object of the present invention to provide an efficient process for converting solid metal boron oxides to metal borohydrides in a fluidized bed.

[0010] It is another or alternative object of the present invention to provide an efficient process for converting solute metal boron oxide dissolved in a fluidized bed to metal borohydride.

[0011] It is another or alternative object of the present invention to provide a waste-free process for converting metal boron oxides to metal borohydrides.

[0012] Yet another or alternative object of the present invention is to provide a method for storing H2 in the form of metal borohydrides starting from the hydrolysis products of the metal borohydrides.

[0013] It is yet another or alternative object of the present invention to provide a method for efficiently recycling spent fuel where metal borohydrides and water are used as the hydrogen extraction fuel.

[0014] It is yet another or alternative object of the present invention to provide a method for efficiently converting metal borohydride hydrolysate into metal boron oxides that can be used for further conversion into metal borohydrides.

[0015] At least one of these objects is achieved by a method comprising preparing a metal boron oxide Me(BO2) n Production of metal borohydride Me(BH4) n wherein Me is a metal or a molecule exhibiting metal-like behavior and capable of acting as a metal, and n is an integer related to the valence of the metal, wherein

[0016] In the first fluidized bed step, metal boron oxide is provided in a first fluidized bed using at least one gas selected from nitrogen, N2 gas and a noble gas, optionally the noble gas is selected from at least one of helium, He; neon, Ne; argon, Ar; and xenon, Xe, and oxygen atoms are removed from the metal boron oxide to provide metal boride MeB. n The particles (which may be ions) are fluidized in this environment, particularly under pressure and temperature; and

[0017] In the subsequent second fluidized bed step, the metal boride particles are provided in a second fluidized bed. The second fluidized bed is fluidized using hydrogen, H2 gas, in an environment where the hydrogen reacts chemically with the metal boride particles to provide metal borohydride.

[0018] In one embodiment, the metal boron oxide is provided in the first fluidized bed in the first fluidized bed step (B1) in the form of metal boron oxide dissolved in a suitable first liquid, which first liquid optionally includes water, optionally includes water provided by reverse osmosis, and optionally includes ultrapure water, UPW.

[0019] In one embodiment, the water meets at least one of having a conductivity of less than 1 μS / cm, optionally less than 0.5 μS / cm, optionally less than 0.1 μS / cm, optionally less than 0.06 μS / cm, optionally 0.056 μS / cm or less and optionally having an ASTM electronic and semiconductor grade water E-1 type classification or better.

[0020] In one embodiment, the metal boroxide is provided in the first fluidized bed step as a solid in a suitable second liquid, optionally ethanol, and optionally the metal boroxide is first dried and then provided in the suitable second liquid.

[0021] In one embodiment, oxygen gas O2 formed by the chemical reaction of two oxygen atoms removed from the metal boron oxide is separated from the first fluidized bed in the first fluidization step using a suitable membrane.

[0022] In one embodiment, the metal boride MeB n The particles are provided in the second fluidised bed step in a state where the metal boride particles are dissolved in a suitable third liquid, which may optionally include toluene.

[0023] In one embodiment, the metal boride MeB n The particles are provided in the second fluidised bed step in a second fluidised bed where the metal boride particles are provided in solid form in a suitable fourth liquid, which may optionally include diethylene glycol (di-etylene).

[0024] In one embodiment, in the first fluidized bed step, the temperature of the first fluidized bed is lower than the maximum temperature at which the MeB bond breaks to keep the MeB bond intact.

[0025] In one embodiment, the metal boron oxide Me(BO2)n provided in the first fluidized bed step is produced by a recycling process comprising a recycled mixture of compounds of metal, boron and oxygen.

[0026] In one embodiment, the recycling process includes a recycling method as described below.

[0027] In another aspect, the present invention provides a method for preparing ...n and a recycled mixture of compounds containing metal, boron and oxygen (oxide) to produce metal boron oxide Me(BO2) n A recycling method wherein Me is a metal or a molecule exhibiting metal-like behavior and capable of acting as a metal, and n is an integer related to the valence of the metal, wherein the metal chloride is separated from the mixture and the metal hydroxide MeOH is provided in the mixture to chemically react with the compound to produce a metal boron oxide.

[0028] In one embodiment, the compound comprises a metal tetraborate.

[0029] In one embodiment, the metal chloride is separated from the mixture by using centrifugal force.

[0030] In one embodiment, the separated metal chloride is mixed with water, optionally water provided by reverse osmosis, optionally ultrapure water UPW, and the aqueous mixture of metal chlorides is subjected to an electrolysis step E to produce metal hydroxide MeOH and chlorine atoms, which then further react chemically with water to form hydrogen chloride HCl.

[0031] In one embodiment, metal hydroxide from the electrolysis step is provided in the recycle mixture.

[0032] In one embodiment, the water satisfies at least one of the following: has an electrical conductivity of less than 1 μS / cm, optionally less than 0.5 μS / cm, optionally less than 0.1 μS / cm, optionally less than 0.06 μS / cm, optionally 0.056 μS / cm or less, and optionally has an ASTM electronic and semiconductor grade water E-1 type classification or better.

[0033] In one embodiment, the hydrogen chloride is allowed to escape as pumped hydrogen chloride gas.

[0034] In one embodiment, the recycled mixture is heated to convert the compound comprising metal, boron and oxygen, particularly metal tetraborate, to metal boron oxide.

[0035] In an embodiment, the metal is selected from at least one of sodium, Na; potassium, K; lithium, Li; and magnesium, Mg.

[0036] In yet another aspect, the present invention provides an apparatus suitable for carrying out the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In the description of the present invention, other features and advantages of the present invention will become apparent by way of non-limiting and non-exclusive embodiments. These embodiments should not be interpreted as limiting the scope of protection. Those skilled in the art will recognize that other alternatives and equivalent embodiments of the present invention can be conceived and simplified without departing from the scope of the present invention. The embodiments of the present invention will be described with reference to the accompanying drawings, in which similar or identical reference symbols represent similar, identical or corresponding parts, and wherein

[0038] Figure 1 shows a schematic overview of a method for producing a metal borohydride according to one embodiment of the present invention; and

[0039] Figure 2 A schematic overview of a method for producing metal boron oxide according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0040] Figure 1 A schematic diagram of one embodiment of the method of the present invention is shown. Spent fuel (comprising metal boron oxide Me(BO2)) is typically in wet form. n and possibly metal chlorides MeCl n ) is converted into the metal borohydride Me(BH4) by utilizing two fluidized beds in two different steps of the process n . The energy required in the fluidized bed process is provided in particular in the form of pressure and / or heat. The metal includes any material commonly referred to as a metal, including alkali metals, alkaline earth metals, transition metals and complex metals. The process method below is further described mainly with reference to sodium as the metal, but other metals, such as in particular potassium, K; lithium, Li; and magnesium, Mg; or any molecule that can exhibit metal-like behavior and act as a metal, can also be used. The metal of the metalloid-acting molecule acts as a carrier for the groups BO2, B, BH4, B4O7, etc. Spent fuel S generally refers to a mixture of compounds produced by the reaction process of converting metal borohydrides into hydrogen H2, which can be used in fuel cells to generate electricity. Depending on the actual situation driving the conversion, the conversion of metal borohydrides can produce a spent fuel mixture of various compounds. This conversion can be driven by a catalyst and / or by an acid. In the latter case, when, for example, hydrogen chloride has been used as the reaction-accelerating acid, the spent fuel S can contain metal chlorides.

[0041] exist Figure 1In the process shown, for example, an aqueous mixture of borax Na2B4O7(aq), sodium borate NaBO2(aq) and sodium chloride NaCl, referred to as spent fuel S, is converted into sodium borate NaBO2 in a recycling process R. Sodium borate (sodium metaborate) can be in the form of a hydrate, generally written as NaBO2·xH2O. Figure 2 One embodiment of the recycling process R is described.

[0042] In the first fluidized bed step B1, a first fluidized bed is provided. The first fluidized bed is composed of a suitable fluid at a predetermined pressure and heated to a predetermined temperature, and is filled with a rare gas or molecular nitrogen (N2) gas. The rare gas or molecular nitrogen introduced into the first fluidized bed acts as a bombarding element, promoting the release of oxygen atoms from the sodium boron oxide (NaBO2) provided in the first fluidized bed.

[0043] In one embodiment of the present invention, the sodium borate oxide is provided in the first fluidized bed as a solid, for example, as one of its hydrates, in a suitable fluid. In this case, the liquid constituting the first fluidized bed is ethanol C2H6O. In another embodiment of the present invention, NaBO2 is provided in the first fluidized bed as a concentrated liquid. In this case, the liquid constituting the first fluidized bed is ultrapure water UPW. UPW can be defined as meeting at least one of the following: having an electrical conductivity of less than 1 μS / cm, optionally less than 0.5 μS / cm, optionally less than 0.1 μS / cm, optionally less than 0.06 μS / cm, optionally 0.056 μS / cm or less, and optionally having an electronic and semiconductor grade water ASTM E-1 type classification or better. The water can be provided by a reverse osmosis process. Providing metal borate oxide Me(BO2) n One advantage of being a concentrated liquid could be that the bond energy between oxygen atoms and boron atoms is much greater than that in Me(BO2). n In this case, the metal boron oxide Me(BO2) is smaller. n When supplied in concentrated liquid form, it is obtained from metal boron oxide Me(BO2) n Less energy is required to release the oxygen atoms.

[0044] In one embodiment of the present invention, the rare gas present in the first fluidized bed has a mass greater than the mass of oxygen. In this case, krypton, Kr or xenon, Xe can be used. In view of the difference in mass and size between the atoms of these heavier rare gases and oxygen atoms, it is beneficial for oxygen atoms to dissociate from the metal boron oxide. In another embodiment of the present invention, the rare gas present in the first fluidized bed is argon Ar. The advantage of using Ar in the first fluidized bed is due to the fact that Ar is cheaper among the rare gases and has a mass close to the mass of oxygen. This makes Ar a very suitable element that can be used to promote the dissociation of oxygen from the metal boron oxide. Those skilled in the art will understand that any rare gas can be used in the above process and that the present invention is not limited to the above embodiment. When the metal is sodium, the temperature of the first fluidized bed in the first fluidized bed step B1 is lower than the maximum temperature at which the NaB bond breaks to maintain the integrity of the bond in NaB or generally the MeB bond.

[0045] After promoting the dissociation of oxygen atoms from the metal boron oxide, the noble gas or nitrogen can leave the fluidized bed. The released elements can then be captured and stored, and subsequently reintroduced into the process. The removed oxygen atoms react to form molecular oxygen. Membrane filters are used to separate the oxygen and possibly other gases from the fluidized bed.

[0046] The remaining MeB n Group ( Figure 1 In the embodiment, NaB (produced in the first fluidized bed step B1 after oxygen removal) is separated from free oxygen in the first fluidized bed. When a heavier noble gas is used, the significant difference in mass and size between the noble gas atoms and oxygen atoms or molecules facilitates the separation of the noble gas or nitrogen atoms from the oxygen atoms remaining in the first fluidized bed.

[0047] In the next second fluidized bed step B2 of the process, the generated radical MeB n Provided in a second fluidized bed. The second fluidized bed is composed of a suitable fluid at a predetermined pressure and a predetermined temperature, into which molecular hydrogen H2 is charged. Molecular hydrogen and MeB n The reaction generates metal borohydride Me(BH4) n .

[0048] In one embodiment of the present invention, the group MeB n In another embodiment of the present invention, MeB n The liquid constituting the second fluidized bed may be toluene.

[0049] MeB n The second fluidized bed is circulated, while the hydrogen is transported in the form of bubbles under the influence of pressure and temperature. At the end of this step, the hydrogen is combined with the MeB supplied to the second fluidized bed. n The reaction generates Me(BH4) n .

[0050] Throughout the process, all liquids used in the first and second fluidized beds, as well as all added gases and elements, can be reused in subsequent processes. For these reasons, the process can be considered waste-free, as no pollutants or waste are generated.

[0051] like Figure 2 As shown in the embodiment of FIG, spent fuel S, in the form of wet Na2B4O7(aq) (sodium tetraborate), NaBO2(aq), and NaCl, is supplied to a first recycling process step R1. The metal chlorides are separated from the spent fuel (recycled mixture) by a separation process, such as a separation process using centrifugal force. The separated metal chlorides are dissolved in water, H2O, and electrolysis E is performed in this solution. This electrolysis produces metal hydroxides, in the disclosed embodiment, NaOH, and chlorine atoms.

[0052] The metal hydroxide is supplied to the recycled mixture (spent fuel mixture) to allow the sodium tetraborate to chemically react (convert) into sodium borohydride, while simultaneously heating the recycled mixture to promote the chemical reaction. Metal hydroxide is also separately supplied to the recycled mixture to initiate the process. After electrolysis E, the chlorine atoms in the aqueous solution further react with water to form hydrogen chloride (HCl), which is allowed to escape from the solution and be pumped out. The hydrogen chloride can be used again as an acidic promoter to drive the conversion reaction of the metal borohydride into hydrogen. Figure 2 The dissolution of sodium chloride in water, the electrolysis process E, and the reaction of chlorine atoms with water are shown as three reaction blocks, but actually occur in one process environment.

[0053] The sodium oxyboride from the recycling process step R1 is provided to a further process step to provide sodium borohydride. Figure 2 In an embodiment, sodium borohydride is provided Figure 1 The first fluidized bed step B1 of the embodiment. Figure 2 And also Figure 1The water used in the various process steps shown is provided by a reverse osmosis process RO, and in particular, ultrapure water UPW, which is provided in an ultrapurification process UP following the RO process. The water satisfies at least one of having a conductivity of less than 1 μS / cm, optionally less than 0.5 μS / cm, optionally less than 0.1 μS / cm, optionally less than 0.06 μS / cm, optionally 0.056 μS / cm or less, and optionally having an ASTM electronic and semiconductor grade water E-1 type classification or better.

[0054] The disclosed method is generally applicable to the processing of any metal boron oxide into the related metal borohydride. In one embodiment, the metal used in the process may be sodium (Na), given its abundance and the high free energy values of its compounds. When the metal is used in the form of sodium, the basic values of the Gibbs energy and the molar masses of the elements involved in the recycling process are shown in the table below.

[0055]

[0056] *https: / / en.wikipedia.org / wiki / List_of_standard_Gibbs_free_energies_of_formation

[0057] **Handbook of Chemistry and Physics, 76th Edition th edition)

[0058] ***www.citrination.com

[0059] If sodium (Na) is the metal involved in the process, the spent fuel can contain borax Na2B4O7, which can be easily converted into metal boron oxide NaBO2 by providing energy in the form of temperature to the spent fuel.

Claims

1. A metal boron oxide Me(BO2) n Preparation of metal borohydride Me(BH4) n wherein Me is a metal or a molecule exhibiting metal-like behavior and capable of acting as a metal, and n is an integer related to the valence of the metal, wherein In the first fluidized bed step (B1), the metal boron oxide is provided in the first fluidized bed in the form of a fluid, and the first fluidized bed uses at least one gas selected from nitrogen N2 gas and a rare gas to remove oxygen atoms from the metal boron oxide to provide a metal boride MeB n fluidizing the environment of the particles; and In the subsequent second fluidized bed step (B2), the metal boride particles are provided in a second fluidized bed which is fluidized using hydrogen H2 gas in an environment where the hydrogen chemically reacts with the metal boride particles to provide metal borohydride. The method of claim 1 , wherein the particles are ions.

3. The method according to claim 1, wherein the environment in the first fluidized bed step (B1) includes pressure and temperature. The method according to claim 1 , wherein the rare gas is selected from at least one of helium (He), neon (Ne), argon (Ar), and xenon (Xe).

5. The method according to claim 1, wherein the metal boron oxide is provided in the first fluidized bed in the first fluidized bed step (B1) in a state where the metal boron oxide is dissolved in a suitable first liquid. The method of claim 5 , wherein the first liquid comprises water.

7. The method of claim 6, wherein the first liquid comprises water provided by reverse osmosis. The method according to claim 6 , wherein the first liquid comprises ultrapure water (UPW).

9. The method of claim 6, wherein the water has a conductivity of less than 1 μS / cm.

10. The method of claim 6, wherein the water has a conductivity of less than 0.5 μS / cm.

11. The method of claim 6, wherein the water has a conductivity of less than 0.1 μS / cm.

12. The method of claim 6, wherein the water has a conductivity of less than 0.06 μS / cm.

13. The method of claim 6, wherein the water has a conductivity of 0.056 μS / cm or less.

14. The method of claim 6, wherein the water has an ASTM Electronic and Semiconductor Grade Water E-1 type classification or stricter.

15. The method of claim 1, wherein the metal boron oxide is provided in the first fluidized bed in the first fluidized bed step (B1) in a state where the metal boron oxide is provided in a solid form in a suitable second liquid.

16. The method of claim 15, wherein the second liquid is ethanol.

17. The method of claim 15, wherein the metal boron oxide is first dried and then provided in the suitable second liquid.

18. The process according to any one of claims 1 to 17, wherein oxygen O2 gas formed by the chemical reaction of two oxygen atoms removed from the metal boron oxide is separated from the first fluidized bed in the first fluidization step (B1) using a suitable membrane.

19. The process according to any one of claims 1 to 17, wherein in the second fluidized bed step (B2), the metal boride MeB n The particles are provided in the second fluidized bed in the form of the metal boride particles dissolved in a suitable third liquid.

20. The method of claim 19, wherein the third liquid comprises toluene.

21. The method according to any one of claims 1 to 17, wherein the metal boride MeB n The particles are provided in the second fluidised bed in the second fluidised bed step (B2) in the form of the metal boride particles in a solid form in a suitable fourth liquid.

22. The method of claim 21, wherein the fourth liquid comprises diethylene glycol.

23. The method according to any one of claims 1 to 17, wherein in the first fluidized bed step (B1), the temperature of the first fluidized bed is lower than the maximum temperature at which MeB bonds break to keep the MeB bonds intact.

24. A process according to any one of claims 1 to 17, comprising recycling of a recycled mixture of metal, boron and oxygen compounds to produce the metal boron oxide Me(BO2) provided to the first fluidised bed step (B1). n .

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