Method for producing metal borohydride from metal boron oxide

Abstract

Metal boron oxide Me(BO2) n From metal boron hydrides Me(BH4) n wherein Me is a metal or a molecule that exhibits metallic-like behavior and can function as a metal, and n is an integer related to the valence of said metal, and in a first fluidized bed step, a metal boron oxide is fed to a first fluidized bed. The first fluidized bed step is carried out by removing oxygen atoms from the metal boron oxide to produce metal boron, MeB. n The boron metal particles are fluidized using a gas selected from nitrogen (N2) gas and at least one of a noble gas optionally selected from at least one of helium (He); neon (Ne); argon (Ar); and xenon (Xe) under conditions, particularly pressure and temperature, to produce particles, and optionally ions. In a subsequent second fluidized bed step, the boron metal particles are fed to a second fluidized bed fluidized using hydrogen (H2) gas under conditions such that the hydrogen chemically reacts with the boron metal particles to produce a boron metal hydride.

Description

Technical Field

[0001] The present invention relates to a method for producing metal borohydride from metal boron oxide. The present invention further relates to an apparatus for carrying out such a method.

Background Art

[0002] Hydrogen (H2) is widely recognized as one of the most promising future energy sources because of its high energy density, relatively abundant presence in nature, and availability. Furthermore, H2 is considered to be one of the cleanest fuels in that the only waste product produced after use is water.

[0003] However, despite extensive technological efforts over the past few decades, the costs associated with the production, storage, and transportation of H2 remain quite high, hindering the widespread use of H2 as a fuel. This is particularly true when hydrogen is used in gaseous form, as hydrogen has a very low specific gravity, meaning that additional costs are incurred in continuously cooling or compressing H2 in a container suitable for storing such a highly reactive element.

[0004] In view of this, promising methods and systems for storing hydrogen using metal borohydride Me(BH4) n which can release hydrogen by hydrolysis have recently been developed.

[0005] In the reaction of metal borohydride Me(BH4) n with water, several reaction products such as Me(BO2) n and optionally MeCl n may be formed in the spent fuel mixture, which may also contain other compounds of metal, boron, and oxygen. Some of these reaction products can be recycled. However, starting from the spent fuel mixture to metal borohydride Me(BH4) nKnown methods for regeneration are still very inefficient in terms of the energy required and the conversion rate from spent fuel to metal borohydride. Summary of the Invention Problems to be Solved by the Invention

[0006] One object of the present invention is to provide an efficient method for re-converting the hydrolysis product of metal borohydride into metal borohydride.

[0007] Another or alternative object of the present invention is to provide an efficient method for re-converting the hydrolysis product of metal borohydride into metal borohydride using at least one fluidized bed.

[0008] Another or alternative object of the present invention is to provide an efficient method for converting metal borate into metal borohydride using at least one fluidized bed.

[0009] Another or alternative object of the present invention is to provide an efficient method for converting solid metal borate into metal borohydride in a fluidized bed.

[0010] Another or alternative object of the present invention is to provide an efficient method for converting solute metal borate dissolved in a fluidized bed into metal borohydride.

[0011] Another or alternative object of the present invention is to provide a waste-free method for converting metal borate into metal borohydride.

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

[0013] Yet another or alternative object of the present invention is to provide a method for efficiently recycling spent fuel when using metal borohydride and water as fuels for hydrogen extraction.

[0014] Yet another or alternative object of the present invention is to provide a method capable of efficiently supplying hydrolysis products of metal borohydride to metal boron oxide and further converting the same to metal borohydride.

Means for Solving the Problems

[0015] At least one of these objects is a method for producing metal borohydride Me(BH4) from metal boron oxide Me(BO2), where Me is a metal or a molecule that exhibits metal-like behavior and can function as a metal, and n is an integer related to the valence of the metal. n In a first fluidized bed step, the metal boron oxide is supplied to a first fluidized bed fluidized using a gas selected from nitrogen N2 gas and at least one of rare gases optionally selected from helium He; neon Ne; argon Ar; and xenon Xe, in a situation where oxygen atoms are removed from the metal boron oxide to give metal boron MeB particles, optionally ions, especially under pressure and temperature. n In a subsequent second fluidized bed step, the metal boron particles are supplied to a second fluidized bed fluidized using hydrogen H2 gas under conditions such that hydrogen chemically reacts with the metal boron particles to yield metal borohydride, which is achieved by a method. In a first fluidized bed step, the metal boron oxide is supplied to the first fluidized bed in a state of being dissolved in a suitable first liquid that may contain water, water provided by reverse osmosis, and ultrapure water UPW in some cases. n In a subsequent second fluidized bed step, the metal boron particles are supplied to a second fluidized bed fluidized using hydrogen H2 gas under conditions such that hydrogen chemically reacts with the metal boron particles to yield metal borohydride, which is achieved by a method. In one embodiment, the metal boron oxide is supplied to the first fluidized bed in a state of being dissolved in a suitable first liquid that may contain water, water provided by reverse osmosis, and ultrapure water UPW in some cases.

[0016] In one embodiment, the metal boron oxide is supplied to the first fluidized bed in a state of being dissolved in a suitable first liquid that may contain water, water provided by reverse osmosis, and ultrapure water UPW in some cases.

[0017] In one embodiment, the water satisfies at least one of the following conditions: a conductivity of less than 1 μS / cm, in some cases less than 0.5 μS / cm, in some cases less than 0.1 μS / cm, in some cases less than 0.06 μS / cm, in some cases 0.056 μS / cm or less, and in some cases a classification of ASTM Electronic and Semiconductor Grade Water Type E-1 or higher.

[0018] In one embodiment, in the first fluidized bed process, the metal borate is supplied to the first fluidized bed in solid form in a suitable second liquid, in some cases ethanol, and in some cases the metal borate is first dried and then supplied to the suitable second liquid.

[0019] In one embodiment, the oxygen O2 gas formed from the chemical reaction of two oxygen atoms removed from the metal borate is separated from the first fluidized bed using a suitable membrane in the first fluidization process.

[0020] In one embodiment, the metal boride MeB n particles are supplied to the second fluidized bed in a state where the metal boride particles are dissolved in a suitable third liquid that may contain toluene in some cases.

[0021] In one embodiment, the metal boride MeB n particles are supplied to the second fluidized bed in a state where the metal boride particles are in solid form in a suitable fourth liquid that may contain di-ethylene in some cases.

[0022] In one embodiment, in the first fluidized bed process, the temperature of the first fluidized bed is lower than the maximum temperature at which the bond of MeB is broken in order to maintain the bond of MeB as it is.

[0023] In one embodiment, to obtain the metal borate Me(BO2) supplied in the first fluidized bed process, a recycling process of a recycling mixture of a compound of metal, boron, and oxygen is included. n ​

[0024] In one embodiment, the recycling process includes the recycling method referred to below.

[0025] In another aspect, the present invention provides a recycling method for producing metal borate Me(BO2) from a recycling mixture of metal chloride Me(Cl) n and a compound containing a metal, boron, and an oxide, wherein Me is a metal or a molecule that exhibits metal-like behavior and can function as a metal, n is an integer related to the valence of the metal, the metal chloride is separated from the mixture, and metal hydroxide MeOH is supplied to the mixture and chemically reacts with the compound to produce the metal borate. n The method is provided, where Me is a metal or a molecule that exhibits metal-like behavior and can function as a metal, n is an integer related to the valence of the metal, the metal chloride is separated from the mixture, and metal hydroxide MeOH is supplied to the mixture and chemically reacts with the compound to produce the metal borate.

[0026] In one embodiment, the compound includes a metal tetraborate.

[0027] In one embodiment, the metal chloride is separated from the mixture using centrifugal force.

[0028] In one embodiment, the separated metal chloride is mixed with water, optionally water provided by reverse osmosis, and optionally ultrapure water UPW, and the aqueous mixture of the metal chloride is subjected to an electrolysis step E to produce metal hydroxide MeOH and chlorine atoms. Subsequently, the chlorine atoms further chemically react with water to form hydrogen chloride HCl.

[0029] In one embodiment, the metal hydroxide from the electrolysis step is supplied to the recycling mixture.

[0030] In one embodiment, the water satisfies at least one of the following conditions: 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 less than or equal to 0.056 μS / cm, and optionally meets the ASTM electronic equipment and semiconductor grade water type E-1 classification or higher.

[0031] In one embodiment, hydrogen chloride is discharged and taken out as hydrogen chloride gas.

[0032] In one embodiment, the recycle mixture is heated to convert a compound containing metal, boron, and oxide, particularly a metal tetraborate, into a metal boron oxide.

[0033] In embodiments, the metal is selected from at least one of sodium Na; potassium K; lithium Li; and magnesium Mg.

[0034] In yet another aspect, the present invention provides an apparatus suitable for implementing the aforementioned method.

[0035] Further features and advantages of the present invention will become apparent from the description of the present invention according to non-limiting and non-exclusive embodiments. These embodiments should not be construed as limiting the scope of protection. Those skilled in the art will understand that other alternative and equivalent embodiments of the present invention can be devised and implemented without departing from the scope of the present invention. Embodiments of the present invention are described with reference to the accompanying drawings, where similar or identical reference numerals indicate similar, identical, or corresponding parts.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0037] A schematic view of an embodiment of the method of the present invention is shown in FIG. 1. Metal boron oxide Me(BO2) n and optionally metal chloride MeCl nSpent fuel in generally wet form, containing, is converted to metal borohydride Me(BH4) by using two different fluidized beds in two different steps of the process. n The energy required for the fluidized bed process is provided, inter alia, as pressure and / or heat. Metals include any material generally called a metal, including alkali metals, alkaline earth metals, transition metals, and composite metals. The following process will be further mainly described with reference to sodium as the metal, but other metals, such as, inter alia, potassium K; lithium Li; and magnesium Mg; or any molecule showing metal-like behavior and capable of functioning as a metal can equally be used. The metal of the metal-like acting molecule functions as a carrier for groups such as BO2, B, BH4, B4O7. Spent fuel S generally refers to a mixture of compounds resulting from a reaction process that converts metal borohydride to produce hydrogen H2 gas, and this hydrogen gas can be used in a fuel cell for the generation of electrical energy. The conversion of metal borohydride can result in spent fuel mixtures of various compounds depending on the actual situation driving the conversion. Such conversion can be driven by a catalyst and / or an acid. In the latter case, for example, when hydrogen chloride is used as the reaction-promoting acid, spent fuel S may contain metal chlorides.

[0038] In the process shown in Figure 1, an aqueous mixture of, for example, borax Na2B4O7 (aqueous solution); sodium metaborate NaBO2 (aqueous solution), and sodium chloride NaCl, called spent fuel S, is converted to sodium metaborate NaBO2 in the recycling process R. Sodium metaborate (sodium metaborate) can be in a hydrated form generally denoted as NaBO2·xH2O. An embodiment of the recycling process R will be described below with reference to Figure 2.

[0039] In the first fluidized bed step B1, a first fluidized bed composed of an appropriate fluid heated to a predetermined temperature at a predetermined pressure is provided, and a rare gas or molecular nitrogen N2 gas is added thereto. The rare gas or molecular nitrogen introduced into the first fluidized bed acts as a collision element that promotes the release of oxygen atoms from sodium borate oxide NaBO2 supplied to the first fluidized bed.

[0040] In one embodiment of the present invention, sodium borate oxide is supplied to the first fluidized bed in an appropriate fluid as a solid, for example, as one of its hydrates. In this case, the liquid constituting the first fluidized bed is ethanol C2H6O. In another embodiment of the present invention, NaBO2 is supplied to 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 satisfying at least one of an electrical conductivity of less than 1 μS / cm, in some cases less than 0.5 μS / cm, in some cases less than 0.1 μS / cm, in some cases less than 0.06 μS / cm, in some cases less than 0.056 μS / cm, and in some cases water of electronic equipment and semiconductor grade ASTM type E-1 classification or higher. The water can be supplied by a reverse osmosis process. Metal borate Me(BO2) n The advantage of supplying as a concentrated liquid is that the binding energy between the oxygen atom and the boron atom is smaller than when supplying Me(BO2) n as a solid. Therefore, when metal borate Me(BO2) n is supplied as a concentrated liquid, the energy required to release oxygen atoms from metal borate Me(BO2) n will be less.

[0041] In one embodiment of the present invention, the noble 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. Considering the differences in mass and size between the atoms of these heavier noble gases and oxygen atoms, the dissociation of oxygen atoms from the metal borate is promoted. In another embodiment of the present invention, the noble gas present in the first fluidized bed is argon (Ar). The advantage of using Ar in the first fluidized bed is that Ar is inexpensive among noble gases and has a mass close to that of oxygen. Thus, Ar is a very suitable element that can be used to promote the dissociation of oxygen from the metal borate. Those skilled in the art will understand that any noble gas can be used in the above process and that the present invention is not limited to the above examples. When the metal is sodium, in order to maintain the NaB bond, or generally the MeB bond as it is, 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 is broken.

[0042] After promoting the dissociation of oxygen atoms from the metal borate, the noble gas or nitrogen gas may leave the fluidized bed. Then, such released elements can be captured and stored and then reintroduced into the process. The removed oxygen atoms react to form oxygen molecules. A membrane filter is used to separate oxygen gas and possibly other gases from the fluidized bed.

[0043] The residual MeB generated in the first fluidized bed step B1 after oxygen removal n In the embodiment of FIG. 1, the group, NaB in the first fluidized bed is separated from free oxygen. The separation of the noble gas or nitrogen atoms remaining in the first fluidized bed from the oxygen atoms is easily achieved when using a heavier noble gas because there is a significant difference in mass and size between such noble gas atoms and oxygen atoms or molecules.

[0044] Next, in the second fluidized bed step B2 of the process, the generated MeB nThe group is supplied to the second fluidized bed. The second fluidized bed consists of a suitable fluid at a predetermined pressure and temperature, to which molecular hydrogen H2 is added. The molecular hydrogen reacts with MeB n to produce the metal borohydride Me(BH4) n .

[0045] In one embodiment of the present invention, the MeB n group is supplied to the second fluidized bed in a dissolved liquid phase. In this case, the liquid constituting the second fluidized bed may be di-ethylene. In another embodiment of the present invention, the MeB n is supplied to the second fluidized bed as a solid. In this case, the liquid constituting the second fluidized bed may be toluene.

[0046] MeB n circulates in the second fluidized bed while hydrogen is sent in bubbles under the influence of pressure and temperature. At the end of this process, Me(BH4) n is produced by the reaction of hydrogen that reacts with the MeB n supplied to the second fluidized bed.

[0047] Throughout this process, all of the liquids used in the first and second fluidized beds, as well as all of the gases and elements added, can be reused in subsequent processes. For these reasons, such a process can be considered waste-free in that it does not produce pollutants and waste.

[0048] As shown in FIG. 2 as an embodiment, the spent fuel S of the wet form of Na2B4O 7(水溶液) (sodium tetraborate), NaBO 2(水溶液) , and NaCl is supplied to the first recycling process step R1. The metal chloride is separated from the spent fuel (recycling mixture) by a separation process, for example, one that utilizes centrifugal force. The separated metal chloride is dissolved in water H2O, and electrolysis E is performed on such a solution. This electrolysis produces metal hydroxide, NaOH in the disclosed embodiment, and chlorine atoms.

[0049] While heating the recycle mixture to promote the chemical reaction, a metal hydroxide is supplied to the recycle mixture (spent fuel mixture) to cause a chemical reaction (conversion) of sodium tetraborate to sodium borate oxide. To initiate the process, the metal hydroxide is also supplied separately to the recycle mixture. Chlorine atoms in the aqueous solution after electrolysis E further react with water to produce hydrogen chloride HCl, which is discharged from and removed from the solution. The hydrogen chloride can be reused as an acidic promoter to drive the reaction for converting metal borohydride to hydrogen. FIG. 2 shows the dissolution of sodium chloride in water, the electrolysis process E, and the reaction of chlorine atoms with water as three reaction blocks, but in reality, they occur in one process environment.

[0050] Sodium borate oxide from the recycle process step R1 is supplied to a further process step to obtain sodium borohydride. In the embodiment of FIG. 2, sodium borate oxide is supplied to the first fluidized bed step B1 of the embodiment of FIG. 1. The water used in the various process steps shown in FIGS. 2 and also FIG. 1 is provided by a reverse osmosis process RO, and in particular, is ultrapure water UPW provided in an ultra-purification process UP after the RO process. The water satisfies at least one of an electrical conductivity of less than 1 μS / cm, in some cases less than 0.5 μS / cm, in some cases less than 0.1 μS / cm, in some cases less than 0.06 μS / cm, in some cases less than or equal to 0.056 μS / cm, and in some cases a classification of ASTM electronic equipment and semiconductor grade water type E-1 or higher.

[0051] The disclosed method is generally used in a method for treating any metal borate oxide to the relevant metal borohydride. In one embodiment, the metal used in the process may be sodium Na as the metal, considering the abundance and the high value of the free energy of the compound. The basic values of the Gibbs energy and molar mass of the elements involved in the recycle process when the metal used is sodium are as shown in the table below.

[0052]

Table 1

[0053] When sodium Na is a metal involved in the process, the spent fuel can contain borax Na2B4O7, which can be easily converted to metal borate NaBO2 by giving energy to the spent fuel in the form of temperature.

Claims

1. A method for producing a metal borohydride Me(BH ２ ), from a metal borate Me(BO ｎ ), wherein Me is a metal or a molecule that exhibits metal-like behavior and can function as a metal, and n is an integer related to the valence of the metal, ４ ), ｎ ​ In the first fluidized bed step (B1), the metal boron oxide is supplied to a first fluidized bed fluidized using a gas selected from at least one of nitrogen N gas, and at least one of noble gases optionally selected from among helium He; neon Ne; argon Ar; and xenon Xe, under circumstances that result in the removal of oxygen atoms from the metal boron oxide to give metal boron MeB particles, optionally ions, particularly under pressure and temperature. ｎ Particles, circumstances that result in ions, particularly under pressure and temperature, nitrogen N ２ Gas, and at least one of noble gases optionally selected from among helium He; neon Ne; argon Ar; and xenon Xe, under circumstances that result in the removal of oxygen atoms from the metal boron oxide to give metal boron MeB particles, optionally ions, particularly under pressure and temperature. In a subsequent second fluidized bed process (B2), the metal boron particles are supplied to a second fluidized bed fluidized using hydrogen H ２ gas under circumstances such that hydrogen chemically reacts with the metal boron particles to yield a metal boron hydride. ２ A method.

2. The method according to claim 1, wherein the metal borate oxide is supplied to the first fluidized bed in the first fluidized bed step (B1) in a state where the metal borate oxide is dissolved in a suitable first liquid that may contain water, may contain water provided by reverse osmosis, and may contain ultrapure water UPW.

3. The method according to claim 2, wherein the water satisfies at least one of the following: an electrical conductivity of less than 1 μS / cm, in some cases less than 0.5 μS / cm, in some cases less than 0.1 μS / cm, in some cases less than 0.06 μS / cm, in some cases less than or equal to 0.056 μS / cm, and in some cases meets the ASTM electronic equipment and semiconductor grade water type E-1 classification or higher.

4. The method according to claim 1, wherein the metal borate oxide is supplied to the first fluidized bed in the first fluidized bed step (B1) in a state where the metal borate oxide is supplied in solid form to a suitable second liquid, which may be ethanol in some cases, and in some cases the metal borate oxide is first dried and then supplied to the suitable second liquid.

5. Oxygen O formed from the chemical reaction of two oxygen atoms removed from the metal borate oxide ２ The method according to any one of claims 1 to 4, wherein the gas is separated from the first fluidized bed using a suitable membrane in the first fluidization step (B1).

6. The metal boron MeB ｎ The method according to any one of claims 1 to 5, wherein the particles are supplied to the second fluidized bed in a state in which the metal boron particles are dissolved in a suitable third liquid optionally containing toluene in the second fluidized bed step (B2).

7. The metal boron MeB ｎ The method according to any one of claims 1 to 5, wherein the particles are fed to the second fluidized bed in a solid state in a suitable fourth liquid optionally containing di-ethylene in the second fluidized bed step (B2).

8. The method according to any one of claims 1 to 7, wherein in the first fluidized bed step (B1), the temperature of the first fluidized bed is lower than the maximum temperature at which the bond of MeB is broken in order to maintain the bond of MeB as it is.

9. The metal boron oxide Me(BO ２ ) ｎ obtained by supplying in the first fluidized bed step (B1) and including a recycling process of a compound of metal, boron, and oxygen, which is a recycling mixture, the method according to any one of claims 1 to 8.

10. Metal chloride Me(Cl) ｎ and a recycling method for producing metal borate Me(BO ２ from a recycling mixture of the compound containing the metal, boron, and oxide, wherein Me is a metal or a molecule that exhibits metal-like behavior and can function as a metal, n is an integer related to the valence of the metal, the metal chloride is separated from the mixture, and metal hydroxide MeOH is supplied to the mixture to chemically react with the compound to produce a metal borate. ｎ ​

11. The method according to claim 10, wherein the compound contains a metal tetraborate.

12. The method according to any one of claims 10 to 11, wherein the metal chloride is separated from the mixture using centrifugal force.

13. The separated metal chloride is mixed with water, which may be water provided by reverse osmosis in some cases, and may be ultrapure water UPW in some cases. The aqueous mixture of the metal chloride is subjected to an electrolysis step E to produce a metal hydroxide MeOH and chlorine atoms, and then the chlorine atoms further chemically react with water to form hydrogen chloride HCl. The method according to any one of claims 10 to 12.

14. The method according to claim 13, wherein the metal hydroxide from the electrolysis step is supplied to the recycle mixture.

15. The method according to any one of claims 13 to 14, wherein the water satisfies at least one of the following conditions: the electrical conductivity is less than 1 μS / cm, in some cases less than 0.5 μS / cm, in some cases less than 0.1 μS / cm, in some cases less than 0.06 μS / cm, in some cases less than or equal to 0.056 μS / cm, and in some cases ASTM electronic equipment and semiconductor grade water type E-1 classification or higher.

16. The method according to any one of claims 13 to 15, wherein the hydrogen chloride is discharged and taken out as hydrogen chloride gas.

17. The method according to any one of claims 13 to 16, wherein the recycled mixture is heated to convert the compound containing the metal, boron, and oxide, particularly the metal tetraborate, into a metal borate oxide.

18. The method according to any one of claims 1 to 17, wherein the metal is selected from at least one of sodium Na; potassium K; lithium Li; and magnesium Mg.

19. The method according to claim 9, wherein the recycling process includes the recycling method according to any one of claims 10 to 18.

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