Patent Application
20220298011
Described herein are compositions and methods for the chemical storage and release of hydrogen gas. The described compositions may be useful as fuel additives for hydrogen consuming applications, including aviation. The provided compositions are flexible and can be tailored to be lightweight, have high energy capacity, have various methods of activation, and rapidly release the stored hydrogen.
In an aspect, provided is a composition for storing and delivering hydrogen comprising: a substrate comprising at least one of a borohydride or an alkali aluminum hydride; and a first coating in physical communication with the substrate, wherein: the first coating comprises a hydrazinium halide having the formula N2H5X, X comprises a halogen, and the composition is capable of generating hydrogen (H2) when treated with at least one of an elevated temperature, exposure to light, or exposure to electrical energy. In an aspect, the substrate and coating combine to form magnesium hydrazinidoborane (Mg(N2H3BH3)2).
The substrate may be a metal borohydride comprising: NaBH4, LiBH4, Mg(BH4)2, Y(BH4)3, Be(BH4)2, or Ca(BH4)2. The substrate may be a borohydride comprising: (CH3)4CNH3BH4, CH3NH3BH4, NH4BH4 or a solid borane (BxHy). The substrate may be an alkali aluminum hydride comprising: LiAlH4, Li2AlH6, NaAlH4 or Na2AlH6. The halide (X) may be Br or Cl.
The composition may be capable of generating hydrogen (H2) when exposed to light and the composition further comprises a light-absorbing material. The light-absorbing material may comprise at least one of a nitride or gold. The light absorbing material may be randomly mixed within the substrate or the first coating. The light absorbing-material may be present as a second coating in physical communication with the first coating. The light-absorbing material and the coating may be at a ratio between about 1:10 and about 1:100. The light-absorbing material may be cable of absorbing light having a wavelength between about 300 nm and about 1200 nm, or between 300 nm and 1200 nm. The light-absorbing material may comprise a composition defined by AxN1-x, N is nitrogen, A comprises at least one of titanium, zirconium, or niobium, and 0≤x≤1.
The composition may be capable of generating hydrogen (H2) when heated to a temperature and the temperature is selected from the range of 1° C. to 500° C., 50° C. to 450° C., 50° C. to 350° C., or optionally, 80° C. to 250° C. The composition may be capable of generating hydrogen (H2) when exposed to electrical energy via direct electrical contact or electrochemical current generation.
The composition may be a liquid at temperatures less than or equal to 200° C., 100° C., 90° C., or optionally, 80° C. The liquid may be generated via melting or dissolving in solution. The composition may be a fuel additive. The substrate may be reusable by reapplying the coating after hydrogen has been generated.
In an aspect, provided is a method for storing and delivering hydrogen comprising: providing a borohydride or an alkali aluminum hydride substrate; applying a first coating comprising a hydrazinium halide and having the formula N2H5X, wherein X is F, Cl, Br or I, thereby generating a hydrogen storage composition; wherein the hydrogen storage composition is capable of generating hydrogen (H2) when treat to at least one of an elevated temperature, exposure to light or exposure to electrical energy.
The step of applying a coating may comprise depositing a mixture of hydrazine and a borohalide, thereby generating a hydrazinium halide. The borohalide may be boron trifluoride, boron trichloride, boron tribromide or boron triiodide.
The step of applying may comprise mechanical mixing of substrate and the coating. The step of applying may comprise using physical vapor deposition to apply the coating to the substrate, for example, atomic layer deposition. The step of applying may comprise using solution chemistry to apply the coating to the substrate.
The method may further comprise generating hydrogen gas by exposing the hydrogen containing composition to an elevated temperature, light or electrical energy.
Some embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.
The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, “some embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
As used herein the term “substantially” is used to indicate that exact values are not necessarily attainable. By way of example, one of ordinary skill in the art will understand that in some chemical reactions 100% conversion of a reactant is possible, yet unlikely. Most of a reactant may be converted to a product and conversion of the reactant may asymptotically approach 100% conversion. So, although from a practical perspective 100% of the reactant is converted, from a technical perspective, a small and sometimes difficult to define amount remains. For this example of a chemical reactant, that amount may be relatively easily defined by the detection limits of the instrument used to test for it. However, in many cases, this amount may not be easily defined, hence the use of the term “substantially”. In some embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 20%, 15%, 10%, 5%, or within 1% of the value or target. In further embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% of the value or target.
As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±20%, ±15%, ±10%, ±5%, or ±1% of a specific numeric value or target. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±1%, ±0.9%, ±0.8%, ±0.7%, ±0.6%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, or ±0.1% of a specific numeric value or target.
The provided discussion and examples have been presented for purposes of illustration and description. The foregoing is not intended to limit the aspects, embodiments, or configurations to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the aspects, embodiments, or configurations are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the aspects, embodiments, or configurations, may be combined in alternate aspects, embodiments, or configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the aspects, embodiments, or configurations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. While certain aspects of conventional technology have been discussed to facilitate disclosure of some embodiments of the present invention, the Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate aspect, embodiment, or configuration.
For a molecule or compound bearing covalently bound hydrogen, the electronegativity of the atom bound to hydrogen produces a polarization of electric charge across the two species. Hydrogen bond cleavage is facilitated when hydrogen species bearing electropositive polarity is in close proximity to hydrogen bearing electronegative polarity. This bond cleavage is known as heterolytic fission or heterolysis and is described generally by:
A-Hδ++X-Hδ−→AX+H2 [1 ],
where δ− or δ+ describes hydrogen with an abundance or deficiency of electron density, respectively. A contributing factor to equation [1] is the thermodynamic driving force from the formation of the AX compound. Practical examples of this type of chemistry are hydrolysis of metal hydrides equation [2] or thermal decomposition (thermolysis) equation [3] of ammonia borane (NH3BH3), respectively:
2(Hδ+)2O+NaB(Hδ−)4→4H2+NaBO2 [2],
N(Hδ+)3B(Hδ−)3→BN+3H2 [3].
The AX products of these reactions, boron nitride (BN) or NaBO2, are extremely stable compounds and are not useful for reversible hydrogen storage. Both reactions [2] and [3] are being considered for one-way hydrogen fuels for electric aviation powered by fuel cells. Hydrolysis via [2] reduces the specific energy density of the fuel and thermolysis of ammonia borane and similar chemicals can produce ammonia as a biproduct which contaminates the fuel.
A new class of chemical additives that use heterolysis of hydrogen with rapid dihydrogen (H2) release was observed from heating magnesium borohydride, Mg(BH4)2, that had been coated and/or modified by vapor deposition process employing boron tribromide and hydrazine. The compound identified is hydrazinium bromide, N2H5Br, also known as hydrazine monohydrobromide. Hydrazinium bromide accumulated on Mg(BH4)2 as a product of the deposition process.
The hydrogen release process, or desorption, occurred at approximately 100° C., and resulted in 6.6% hydrogen by total sample weight desorbed. The desorption occurred in less than 10 seconds (data sampling rate was 10s steps). The temperature, amount of hydrogen released, and rate are all performance results that could constitute a ‘disruptive’ technology. The rate alone is at least 100-fold greater than with no additive and may be one of the fastest known examples of hydrogen desorption. The low temperature is also of importance because many hydrogen storage applications with hydrides hit barriers due to desorption temperatures that are above 120° C. Subsequent investigations have identified temperatures as low as 85° C. for desorption. Heat transfer effects are likely the reason for observing temperatures above 120° C.
Analysis of the desorption products with mass spectrometry as a function of temperature show hydrogen, water, diborane, ammonia, nitrogen, and diborane. Hydrogen is the primary product, and the other products are released in concentrations 100-fold less than hydrogen at a minimum. The products are temperature dependent with hydrogen being released at the lowest temperature. The purity of the stream may be controlled through temperature.
Hydrazinium bromide and hydrazinium chloride (N2H5Cl) are both available commercially and manufactured for industry. Hydrazinium fluoride has been synthesized. Powders of N2H5Cl and N2H5Br were purchased from Millipore Sigma and mixed with Mg(BH4)2 and sodium borodeuteride (NaBD4) which has hydrogen substituted with deuterium (D). These powder mixtures were heated and also resulted in rapid hydrogen desorption at similar temperatures. Furthermore, mixture of NaBD4 and N2H5Cl showed release of H2, DH, and D2 which is evidence of the heterolysis described above. Also, the use of NaBD4 strongly suggests that the mechanism for hydrazinium halides, N2H5X (X=Br, Cl, F), will operate generally with borohydrides and possible other complex hydrides. Furthermore, it is likely that N2H5F will also produce the rapid desorption. Testing with N2H5Br via vapor deposition on simple metal hydrides like magnesium hydride (MgH2), titanium hydride (TiH2), and calcium hydride (CaH2) showed no activity. The melting of N2H5Cl or N2H5Br which occurs between 85-89° C. and thermal analysis of powder mixtures and vapor deposited materials indicates melting of the N2H5X occurs immediately prior to desorption.
The compounds and methods described herein have the following benefits:
Hydrazinium compounds as solid hydrogen fuel additives: Hydrazinium halides, N2H5X (X=Br, Cl, F), are the principle chemical additive that enable rapid hydrogen release that have not been heretofore identified as such. (Hereafter additive or chemical additive will refer to the hydrazinium halide) It has been confirmed for N2H5Br and N2H5Br and it is expected that N2H5F will also show similar rapid hydrogen release with borohydrides. One benefit for N2H5F would be to reduce the weight of the invention for vehicle and aircraft applications.
Formulations comprised of hydrazinium compounds and borohydrides: Mg(BH4)2, LiBH4, NaBH4 NaBD4, and Ca(BH4)2 have both shown activity to the hydrazinium halides. It is expected that all metal borohydrides will have activity to the N2H5X compounds. Additional borohydrides include Ca(BH4)2, tetramethylammonium borohydride, and sodium aluminum hydride. Borohydrides are complex hydrides and other examples of complex hydrides are sodium aluminum hydride (NaAlH4, Na2AlH6) and lithium aluminum hydride (LiAlH4, Li2AlH6) which also may show activity but also may not be ideal for weight. Formulations may be optimized for: total hydrogen content, specific energy (energy per mass) estimated from the lower heating value of hydrogen, efficiency of hydrogen release, temperature of the hydrogen release, purity of the fuel stream. The relevant fuel standards are SAE J2719 (See also ISO/PDTS 14687-2).
There are several other compositions that may be useful. As for chemical additives, in addition to the hydrazinium monohalides hydrazinium salts where the hydrazinium ion, N2H5+, bound to a negative ion like OH−, N2H5OH. Hydrazinium dihalides may also have activity: N2H6Cl2, N2H6Br2, N2H6F2. As for additional hydrides, NaBH4, LiBH4, Mg(BH4)2, Y(BH4)3, Be(BH4)2, Ca(BH4)2, (CH3)4CNH3BH4, CH3NH3BH4, NH4BH4, LiAlH4, Li2AlH6, NaAlH4, Na2AlH6, and solid boranes (BxHy) may be useful in the compositions and methods described herein.
The particle sizes may be modified for specific applications, for example, the substrate may have a characteristic length or effective diameter selected from the range of 1 nm to 50 nm. Solvents may be used to deliver, synthesize, modify (including modifying to the liquid phase) the various compositions described herein.
The described compositions may be prepared via mechanical mixing, vapor deposition of H2N5X on the hydride, or via solution chemistry. For mechanical mixing, mixtures of chemical additives and hydrides would be prepared by stirring, grinding, and/or other mechanical agitation of powders and/or fluids. For vapor deposition, the hydrazinium halide can be deposited directly on the borohydride with vapor deposition methods, including atomic layer deposition. The hydrazinium halide and/or hydride may also be prepared by solution chemistry.
Advantageously, the delivery and/or release of the hydrogen can be varied based on the formulation and additional factors, including:
The compositions and methods described herein may be further understood by the following non-limiting examples:
The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention and it will be apparent to one skilled in the art that the present invention may be carried out using a large number of variations of the devices, device components, methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional composition and processing elements and steps.
As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a cell” includes a plurality of such cells and equivalents thereof known to those skilled in the art. As well, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably. The expression “of any of claims XX-YY” (wherein XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form, and in some embodiments is interchangeable with the expression “as in any one of claims XX-YY.”
When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups, are disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and subcombinations possible of the group are intended to be individually included in the disclosure. For example, when a device is set forth disclosing a range of materials, device components, and/or device configurations, the description is intended to include specific reference of each combination and/or variation corresponding to the disclosed range.
Every formulation or combination of components described or exemplified herein can be used to practice the invention, unless otherwise stated.
Whenever a range is given in the specification, for example, a density range, a number range, a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.
All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the invention pertains. References cited herein are incorporated by reference herein in their entirety to indicate the state of the art as of their publication or filing date and it is intended that this information can be employed herein, if needed, to exclude specific embodiments that are in the prior art. For example, when composition of matter is claimed, it should be understood that compounds known and available in the art prior to Applicant's invention, including compounds for which an enabling disclosure is provided in the references cited herein, are not intended to be included in the composition of matter claims herein.
As used herein, “comprising” is synonymous with “including,” “containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, “consisting of” excludes any element, step, or ingredient not specified in the claim element. As used herein, “consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.
All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.
This application claims priority from U.S. Provisional Patent Application No. 63/164,365 filed on Mar. 22, 2022, the contents of which are incorporated herein by reference in their entirety.
This invention was made with government support under Contract No. DE-AC36-08GO28308 awarded by the Department of Energy. The government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 63164365 | Mar 2021 | US |
