EP1670578A2

EP1670578A2 - Hydrogen storage compositions and methods of manufacture thereof

Info

Publication number: EP1670578A2
Application number: EP04789538A
Authority: EP
Inventors: Susan Holt Townsend; William Pual Minnear; Ji-Cheng Zhao; John Lemmon; Luke Nathanial Brewer; Job Thomas Rijssenbeek
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2003-09-30
Filing date: 2004-09-30
Publication date: 2006-06-21
Also published as: JP2007512213A; KR20060120033A; WO2005032709A3; WO2005032709A2

Abstract

Disclosed herein is a method for making a combinatorial library comprising disposing on a substrate comprising silicon, graphite, boron, boron carbide, boron nitride, aluminum, germanium, silicon nitride, silicon carbide or silicon boride at least one reactant, wherein the reactants are lithium, magnesium, sodium, potassium, calcium, aluminum or a combination comprising at least one of the foregoing reactants; heat treating the - substrate to create a diffusion multiple having at least two phases; contacting the diffusion multiple with hydrogen; detecting any absorption of hydrogen; and/or detecting any desorption of hydrogen.

Description

HYDROGEN STORAGE COMPOSITIONS AND METHODS OF MANUFACTURE THEREOF

BACKGROUND

This disclosure is related to hydrogen storage compositions and methods of manufacture thereof.

Hydrogen is a "clean fuel" because it can be reacted with oxygen in hydrogen- consuming devices, such as a fuel cell or a combustion engine, to produce energy and water. Nirtually no other reaction byproducts are produced in the exhaust. As a result, the use of hydrogen as a fuel effectively solves many environmental problems associated with the use of petroleum based fuels. Safe and efficient storage of hydrogen gas is, however, essential for many applications that can use hydrogen. In particular, minimizing volume and weight of the hydrogen storage systems are important factors in mobile applications.

Several methods of storing hydrogen are currently used but these are either inadequate or impractical for wide-spread mobile consumer applications. For example, hydrogen can be stored in liquid foπn at very low temperatures. However, the energy consumed in liquefying hydrogen gas is about 40% of the energy available from the resulting hydrogen. In addition, a standard tank filled with liquid hydrogen will become empty in about a week through evaporation; thus dormancy is also a problem. These factors make liquid hydrogen impractical for most consumer applications.

An alternative is to store hydrogen under high pressure in cylinders. However, a 100 pound steel cylinder can only store about one pound of hydrogen at about 2200 psi, which translates into 1% by weight of hydrogen storage. More expensive composite cylinders with special compressors can store hydrogen at higher pressures of about 4,500 psi to achieve a more favorable storage ratio of about 4% by weight. Although even higher pressures are possible, safety factors and the high amount of energy consumed in achieving such high pressures have compelled a search for alternative hydrogen storage technologies that are both safe and efficient. In view of the above, there is a need for safer, more effective methods of storing and recovering hydrogen. In addition, there is a desire to minimize the overall system volume and weight.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a method for making a combinatorial library comprises disposing on a substrate comprising silicon, graphite, boron, boron carbide, boron nitride, aluminum, germanium, silicon nitride, silicon carbide or silicon boride a reactant comprising a light metal; heat treating the substrate to create a diffusion multiple having at least two phases; contacting the diffusion multiple with hydrogen; detecting any absorption of hydrogen; and/or detecting any desorption of hydrogen.

In another embodiment, a method of recovering hydrogen comprises contacting at least one compound selected from the group consisting of AlSi, Ca Si, CaSi, CaSi₂, KSi, K Si₂₃, Li₂₂Si₅, Li₁₃Si₄, Li₇Si₃, Li_]2Si₇, Mg₂Si, NaSi, NaSi₂, Na₄Si₂₃, A1B₂, A1B_]2, B₆Ca, B₆K, B₁₂Li, B₆Li, B₄Li, B₃Li, B₂Li, BLi, B₆Li₇, BLi₃, MgB₂, MgB₄, MgB₇, NaB₆, NaB₁₅, NaB₁₆, AlLi, Al₂Li₃, Al₄Li₉, Al₃Mg₂, Al₁₂Mg₁₇, AIB12, Ge₄K, GeK, GeK₃, GeLi₃, Ge₅Li₂₂, Mg₂Ge, Ge₄Na, GeNa, GeNa₃, aluminum doped Ge₄K, aluminum doped GeK, aluminum doped GeK₃, aluminum doped GeLi₃, aluminum doped Ge₅Li ₂, aluminum doped Mg Ge, aluminum doped Ge₄Na, aluminum doped GeNa, aluminum doped GeNa₃, A1₄C₃, Na₄C₃, Li₄C₃, K C₃, LiC, LiC₆, Mg₂C₃, MgC₂, AlTi₂C, AlTi₃C, AlZrC₂, Al₃Zr₅C, Al₃Zr₂C₄, Al₃Zr₂C₇, KC₄, NaC₄, or a combination comprising at least one of the foregoing compounds in hydrogen to form a hydrogenated compound; and heating the hydrogenated compound to recover the hydrogen.

In yet another embodiment, a method of regenerating hydrogen comprises contacting a compound with hydrogen to fonri a hydrogenated compound; wherein the compound has at least one of the formulas (I) through (V)

(Li_a, Na_b, Kc, Al_d, Mg_c, Ca_f)_x (B, C, N, Si)_y (I)

(Li_a, Na_b, Mg_c, K_d, Ca_e, Ge_r)_x (Al)_y (II) (Li_a, Na_b, Mg_c, K_d, Ca_e, Al_f)_x (Ge)_y (III)

(LU, Na_b, K_c, Al_d, Mg_e, Ca_f)_x (B, C, N)_y (IV)

(Li_a, Na_b, K_c, Ai_d, Mge, Ca_f)_x (B, N, C)_y (V)

where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Al is aluminum; Ge is germanium, B is boron, C is carbon and N is nitrogen, Si is silicon; a, b, c, d, e and f may be the same or different and have values from 0 to 1 ; and x and y have values of about 1 to about 22; and heating the hydrogenated compound to recover the hydrogen.

In a fourth embodiment, a compound of a diffusion multiple has at least one of the formulas (I) through (V)

(Li_a, Na_b, Kc, Ai_d, Mg_e, Ca_f)_x (B, C, N, Si)_y (I)

(Li_a, Na_b, Mgc, K_d, Ca_e, Ge_{t x} (Al)_y (II)

(Li_a, Na_b, Mg_c, K_d, Ca_e, Al_f)_x (Ge)_y (III)

(Li_a, Na_b, K_c, Ai_d, Mg_e, Ca_f)_x (B, C, N)_y (IN)

(Lia, Νa_b, Kc, Aid, Mge, Ca_f)_x (B, N, C)_y (V)

where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Al is aluminum; B is boron, C is carbon and N is nitrogen, Si is silicon; a, b, c, d, e and f may be the same or different and have values from 0 to 1 ; and x and y have values of about 1 to about 22.

In a fifth embodiment, a composition comprises a hydride of a compound, wherein the compound is AlSi, Ca₂Si, CaSi, CaSi₂, KSi, K4S.2₃, Li₂₂Si5, Lil3Si4, Li7Si3, Lil2Si7, Mg2Si, NaSi, NaSi2, Na4Si23, A1B2, A1B12, B6Ca, B6K, B12Li, B₆Li, B₄Li, B₃Li, B₂Li, BLi, B₆Li₇, BLi₃, MgB₂, MgB₄, MgB₇, NaB₆, NaB,₅, NaBι₆, AlLi, AI2L.3, Al₄Li₉, Al₃Mg₂, Al|₂Mg,7, A1B₁₂, Ge₄K, GeK, GeK₃, GeLi₃, Ge₅Li₂₂, Mg₂Ge, Ge₄Na, GeNa, GeNa₃, aluminum doped Ge K, aluminum doped GeK, aluminum doped GeK₃, aluminum doped GeLi₃, aluminum doped Ge₅Li₂2, aluminum doped Mg₂Ge, aluminum doped Ge₄Na, aluminum doped GeNa, aluminum doped GeNa₃, A1₄C₃, Na₄C₃, Li₄C₃, K₄C₃, LiC, LiC₆, Mg₂C₃, MgC₂, AlTi₂C, AlTi₃C, AlZrC₂, Al₃Zr₅C, Al₃Zr₂C , Al₃Zr₂C₇, KC₄, NaC , or a combination comprising at least one of the foregoing compounds.

In a sixth embodiment, a hydrogen storage composition comprises a catalyst composition disposed upon a storage composition; wherein the catalyst composition consists essentially of calcium, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium.

In a seventh embodiment, a hydrogen storage composition comprises a catalyst composition disposed upon a storage composition; wherein the catalyst composition comprises an alloy of calcium, barium, platinum, palladium, nickel, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, iridium, or a combination comprising at least one of the foregoing metals.

In an eighth embodiment, a method for storing hydrogen comprises immersing in a gaseous mixture comprising hydrogen, a hydrogen storage composition comprising a catalyst composition disposed upon a storage composition, wherein the catalyst composition comprises an alloy of calcium, platinum, palladium, nickel, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium; dissociating the hydrogen into atomic hydrogen; and storing the atomic hydrogen in the storage composition.

In a ninth embodiment, a method for generating hydrogen comprises heating a hydrogen storage composition comprising a catalyst composition disposed upon a storage composition, wherein the catalyst composition catalyst composition consists essentially of calcium, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium; or wherein the catalyst composition comprises an alloy of calcium, platinum, palladium, nickel, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium.

In a tenth embodiment, a method for the storage and recovery of hydrogen comprises contacting a hydrogen storage composition with a first gaseous mixture comprising a first concentration of hydrogen; dissociating the hydrogen into atomic hydrogen; storing the atomic hydrogen in the storage composition; contacting the hydrogen storage composition with a second gaseous mixture comprising a second concentration of hydrogen; and heating the hydrogen storage to a temperature effective to facilitate the desorption of hydrogen from the hydrogen storage composition.

In a eleventh embodiment, a system for the storage and recovery of hydrogen comprises a hydrogen generation reactor in fluid communication with a hydride recycle reactor, wherein the hydrogen generation reactor utilizes hydrides of light metal suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides to recover hydrogen.

Disclosed herein too is a method for the storage of hydrogen comprising contacting a hydrogen storage composition with a gaseous mixture comprising hydrogen; and irradiating the hydrogen storage composition with radio frequency radiation or microwave radiation in an amount effective to facilitate the absorption, adsorption and/or chemisorption of hydrogen into the hydrogen storage composition.

Disclosed herein too is a method for the storage and recovery of hydrogen comprising contacting a hydrogen storage composition with a first gaseous mixture comprising a first concentration of hydrogen; irradiating the hydrogen storage composition with a radio frequency radiation or microwave radiation having a first frequency in an amount effective to facilitate the absorption, adsorption and/or chemisorption of hydrogen into the hydrogen storage composition; contacting the hydrogen storage composition with a second gaseous mixture comprising a second concentration of hydrogen; and irradiating the hydrogen storage composition with a radio frequency radiation or microwave radiation having a second frequency in an amount effective to facilitate the desorption of hydrogen from the hydrogen storage composition.

Disclosed herein too is a system for the storage and recovery of hydrogen comprising a hydrogen generation reactor, wherein the hydrogen generation reactor utilizes radio frequency radiation and/or microwave frequency radiation to recover hydrogen.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic showing the arrangement of a diffusion multiple assembly in a silicon substrate;

Figure 2 is a schematic showing the arrangement of diffusion multiples in an aluminum substrate;

Figure 3 is a schematic showing (a) the formation of a binary couple of magnesium and aluminum and (b) the formation of ternary diffusion triple of magnesium, lithium and aluminum;

Figure 4 is a schematic showing the arrangement of a diffusion multiple assembly comprising a boron substrate;

Figure 5 is a schematic showing the arrangement of a diffusion multiple assembly in an graphite substrate;

Figure 6 is a schematic showing how the diffusion multiple assembly is sliced for purposes of analysis; a silicon substrate is shown in the figure;

Figure 7 is a periodic table of elements indicating those metals which chemisorb hydrogen with a high sticking probability (+) and those which do not (-); Figure 8 is a schematic showing a system for the absorption and desorption (recovery) of hydrogen from a hydrogen storage composition; and

Figure 9 is another schematic showing a system for the absorption and desorption (recovery) of hydrogen from a hydrogen storage composition.

DETAILED DESCRIPTION

Disclosed herein is a method for developing a combinatorial library to determine suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides (germanium-containing compounds), borides, borocarbides, boronitrides, or carbides that may be advantageously used for the storage of hydrogen. Disclosed herein too are methods for manufacturing suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides that can be subsequently hydrogenated to efficiently store hydrogen. Disclosed herein too are hydrogen storage compositions comprising silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides that can store hydrogen for use in the generation of energy in fuel cell applications for automobiles, homes and apartments, manufacturing industries, and the like. In one embodiment, these, hydrogen storage compositions can comprise a catalyst composition, which can dissociate hydrogen if desired.

In those cases where the hydrogen storage composition comprises a catalyst composition, the catalyst composition is generally disposed upon the storage composition. The catalyst is capable of dissociating molecular hydrogen into atomic or ionic hydrogen and the storage composition stores the atomic hydrogen. Disclosed herein too is a method for storing hydrogen that comprises immersing the hydrogen storage composition into hydrogen gas, dissociating the hydrogen gas into atomic hydrogen which is then stored in the storage composition.

Disclosed herein too is a method for storing hydrogen that comprises using electromagnetic radiation in the radio wave frequency (radio frequency) and the microwave frequency region. The method may advantageously be used to facilitate the storage of hydrogen in hydrogen storage compositions such as carbon, aluminides, carbides, suicides, nitrides, borides, oxides, oxynitrides, hydroxides, silicates, aluminosilicates, or the like, or a combination comprising at least one of the foregoing. The use of electromagnetic energy may also advantageously enhance the amount of hydrogen stored in the hydrogen storage compositions. The hydrogen storage compositions may be used for the recovery of hydrogen in energy generating devices such as fuel cells, gas turbines, or the like.

The stored hydrogen may then be utilized for the recovery of hydrogen in energy generating devices such as fuel cells, gas turbines, or the like. This method of hydrogen storage and recovery may also be advantageously used in a land mobile such as an automobile, a train, and the like; a water craft such as a barge, ship, submarine, and the like; or an airborne carrier or a space ship such as an airplane, rocket, space station, and the like.

The aforementioned method for developing a combinatorial library to determine suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides that may be used for the storage of hydrogen advantageously permits the simultaneous large scale testing of a wide variety of materials. This high efficiency methodology facilitates the creation of a large number of controlled compositional variations in bulk samples for fast and systematic surveys of bulk properties of the suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides. These combinatorial libraries when used in conjunction with microanalytical techniques such as electron probe microanalysis, electron backscatter diffraction analysis, and the like, can be additionally used for efficient surveys of phase equilibria, coefficients, precipitation kinetics, properties and composition-phase-property relationships for accelerated design of multi-component alloys and systems.

Complex hydrides from which hydrogen can be obtained generally consist of a H-M complex, where M is a metal and H is hydrogen. Such hydrides may have ionic, covalent, metallic bonding or bonding comprising a combination of at least one of the foregoing types of bonding. These hydrides have a hydrogen to metal ratio of greater than or equal to about 1. The reaction between a metal and hydrogen to form a hydride is generally a reversible reaction and takes place according to the following equation:

M + (x/2) H₂ ^{^}«— * MH

Complex hydrides can store up to about 18 weight percent (wt%) of hydrogen, and have high volumetric storage densities. The volumetric storage density of hydrides is greater than either liquid or solid hydrogen, which makes them very useful in energy storage applications. The process of hydrogen adsorption, absorption or chemisorption results in hydrogen storage and is hereinafter, for the sake of simplicity, referred to as absorption, while the process of desorption results in the release of hydrogen.

In an exemplary embodiment, compositions comprising light metal suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides can form hydrides that may be reversibly decomposed at relatively low temperatures of less than or equal to about 300°C to release hydrogen. The light metals are alkali metals and/or alkaline earth metals. Examples of suitable light metals are lithium, sodium, magnesium, potassium, aluminum, calcium and germanium. The suicides, borosilicides, carbosilicides and nitrosilicides have the formula (I)

(Li_a, Na_b, K_c, Al_d, Mg_e, Ca_r)_x (B, C, N, Si)_{y .} (I)

where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Al is aluminum; B is boron, C is carbon and N is nitrogen, Si is silicon; a, b, c, d, e and f may be the same or different and have values from 0 to 1 ; and x and y have values of about 1 to about 22. The sum of a+b+c+d+e+f can be equal to 1.

The light metal aluminides have the formula (II) while the light metal germanides have formula (III)

(Li_a, Na_b, Mg_c, K_d, Ca_e, Ge_r)_x (Al)_y (II)

(Li_a, Na_b, Mgc, K_d, Ca_e, Al_r)_x (Ge)_y (III) where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Ge is germanium, Al is aluminum; a, b, c, d, e and f may be the same or different and have values from 0 to 1; x , and y have values of 1 to 22. The sum of a+b+c+d+e+f can be equal to 1.

The borides, borocarbides and boronitrides have the formula (IN)

(Li_β, Νa_b, Mgc, K_d, Ca_e, Al_f)_x (B, C, N)_y (IN)

where Li is lithium, Νa is sodium, Mg is magnesium, K is potassium, Ca is calcium, Al is aluminum; B is boron, C is carbon and Ν is nitrogen; a, b, c, d, e and f may be the same or different and have values from 0 to 1 ; and x , and y have values of about 1 to about 22. The sum of a+b+c+d+e+f is can be equal to 1.

The carbides have the formula (V)

(Li_a, Νa_b, K_c, Al_d, Mge, Ca_f)_x (B, N, C)_y (V)

where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Al is aluminum; B is boron, C is carbon, Si is silicon; a, b, c, d, e and f may be the same or different and have values from 0 to 1 ; and x and y have values of about 1 to about 22. The sum of a+b+c+d+e+f is equal to 1.

In one embodiment, a method of developing a combinatorial library for determining the hydrogen storage capabilities of a suicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides is via the use of a diffusion multiple. A diffusion multiple is a compound that is the product of an interdiffusion reaction formed between a first reactant and a second reactant when both reactants are placed in closed proximity with each other and heated to a temperature effective to permit interdiffusion to take place. The temperature effective to permit the interdiffusion is one that can overcome the activation energy of diffusion and achieve at least a degree of interdiffusion of the reactants within a manageable time. Such a temperature is generally about 200 to about 2000°C, depending upon the reactants. Diffusion multiples are generally manufactured or prepared by placing reactants in a substrate to form a diffusion multiple assembly; optionally subjecting the diffusion multiple assembly to hot isostatic pressing; heat treating the diffusion multiple assembly to promote interdiffusion of the reactants with one another and/or interdiffusion between the reactants with the substrate; optionally cutting, polishing and grinding the diffusion multiple; identifying the elemental composition of the various phases present in the diffusion multiple; and charging the diffusion multiple with hydrogen by contacting it with a hydrogen rich gaseous mixture and determining the phases that absorb hydrogen.

Figure 1 shows an exemplary embodiment of a diffusion multiple assembly comprising light metal suicides. In Figure 1, the light elements are placed in holes that are drilled in a silicon substrate. Other substrates that can be used are silicon boride (SiB₄), silicon carbide (SiC) or silicon nitride (Si₃N₄) substrates. The holes generally end half-way through the thickness of the block. Some holes are spaced apart from one another such that during the heat treatment, there is only one reactant reacting with the substrate material to form binary couples and binary solid solutions. When the substrate comprises silicon boride, silicon carbide or silicon nitride, ternary triples may be formed.

In another manner of making a ternary triple, holes are spaced in close proximity in pairs with each other as shown in the Figure 1. This arrangement, i.e., where the holes are spaced in close proximity in pairs may be used to generate ternary diffusion triples (also termed ternary compounds and/or ternary solid solutions) upon subjecting the diffusion multiple assembly to heat treatment. The reactants are generally placed into the holes in a loose form i.e., they do not need to be a tight fit.

The following suicides can be obtained from the diffusion multiple assembly shown in Figure 1 and may be used for a determination of hydrogen potential: AlSi, Ca₂Si, CaSi, CaSi₂, KSi, K₄Si₂₃, Li₂₂Si₅, Li_] Si , Li₇Si₃, Liι₂Si₇, Mg₂Si, NaSi, NaSi , Na₄Si₂₃, or the like, or a combination comprising at least one of the foregoing suicides. Ternary suicides in general, and ternary suicides comprising the foregoing suicides in particular may be useful for hydrogenation and for generating hydrogen. In addition borosilicides, carbosilicides and nitrosilicides of lithium, magnesium calcium, sodium, potassium and aluminum may also be used for hydrogenation and for generating hydrogen.

The suicides, borosilicides, carbosilicides and nitrosilicides generally have at least one of potassium, lithium, magnesium or sodium. The presence of the potassium, lithium, magnesium and sodium promotes an affinity for hydrogen. Silicon on the other hand has a low affinity for the hydrogen and this feature is offset by the affinity of hydrogen displayed by potassium, lithium, magnesium and/or sodium. Without being limited to theory, it is believed that those elements of the diffusion multiple that have a high affinity for hydrogen generally facilitate absorption of hydrogen, while those elements such as silicon that have a low affinity for hydrogen generally facilitate the desorption.

Figure 2 shows an exemplary embodiment of a diffusion multiple assembly comprising light metal aluminides. In Figure 2, the diffusion multiple is prepared by drilling holes into an aluminum substrate. The following aluminides and germanides can be obtained from the diffusion multiple assembly shown in Figure 2 and may be used for a determination of hydrogen potential: AlLi, Al₂Li₃, Al₄Li , Al₃Mg₂, Al_]2Mgi₇, Ge₄K, GeK, GeK₃, GeLi₃, Ge₅Li₂₂, Mg₂Ge, Ge₄Na, GeNa, GeNa₃, or the like, or a combination comprising at least one of the foregoing aluminides and germanides. The above-mentioned germanides may also be doped with aluminum if desired.

When aluminum is used as the substrate, ternary triples can be formed. The ternary triples comprise lithium and magnesium with aluminum, lithium and germanium with aluminum, sodium and germanium with aluminum, magnesium and germanium with aluminum, and germanium and potassium with aluminum. The aluminides and germanides generally have at least one of either potassium, lithium, magnesium or sodium. The presence of the potassium, lithium magnesium and sodium promotes an affinity for hydrogen. Aluminum and germanium on the other hand have a low affinity for the hydrogen and this feature is offset by the affinity of hydrogen displayed by potassium, lithium, magnesium and/or sodium. Without being limited to theory it is believed that those elements of the diffusion multiple that have a high affinity for hydrogen generally facilitate absorption of hydrogen, while those elements such as aluminum and germanium that have a low affinity for hydrogen generally facilitate the desorption.

In Figure 3, the diffusion multiple is prepared by drilling holes into a boron substrate. The following borides can be obtained from the diffusion multiple assembly shown in Figure 3 and may be used for a determination of hydrogen potential: AIB₂, AIB₁₂, B₆Ca, B₆K, B₁₂L-, B₆Li, B₄Li, B₃Li, B₂Li, BLi, B₆Li₇, BLi₃, MgB₂, MgB₄, MgB₇, NaB_<5, NaBis, NaBι_6, or a combination comprising at least one of the foregoing borides or the like. Ternary borides in general, and ternary borides comprising the foregoing borides in particular may be useful for hydrogenation and for generating hydrogen. In addition borocarbides and boronitrides of lithium, magnesium calcium, sodium, potassium and aluminum may also be used for hydrogenation and for generating hydrogen. Ternary diffusion triples of the reactants may also prepared by drilling holes in close proximity to each other as may be seen in Figure 3. The ternary triples comprise magnesium and aluminum with boron, sodium and aluminum with boron, magnesium and potassium with boron, lithium and aluminum with boron, sodium and magnesium with boron, sodium and potassium with boron, lithium and sodium with boron, lithium and magnesium with boron, lithium and potassium with boron, and sodium and aluminum with boron.

The borides, borocarbides and boronitrides generally have at least one of potassium, lithium, magnesium, calcium or sodium. The presence of the potassium, lithium, magnesium, calcium and sodium promotes an affinity for hydrogen. Boron on the other hand has a low affinity for the hydrogen and this feature is offset by the affinity of hydrogen displayed by calcium, potassium, lithium, magnesium and/or sodium.

In the Figure 4, the diffusion multiple is prepared by drilling holes into a graphite substrate. The following carbides can be obtained from the diffusion multiple assembly shown in Figure 4 and may be used for a determination of hydrogen potential: A1₄C₃, Na₄C₃, Li₄C₃, K C3, LiC, LiC₆, Mg C₃, MgC₂, AlTi₂C, AlTi₃C, AlZrC₂, Al₃Zr₅C, Al₃Zr₂C₄, Al₃Zr₂C₇, KC₄, NaC or the like, or a combination comprising at least one of the foregoing carbides. Ternary carbides in general, and ternary carbides comprising the foregoing carbides in particular may be useful for hydrogenation and for generating hydrogen. In addition, borocarbides and nitrocarbides of lithium, magnesium, calcium, sodium, potassium and aluminum may also be used for hydrogenation and for generating hydrogen.

The presence of the potassium, lithium, magnesium and sodium promotes an affinity for hydrogen. Carbon on the other hand has a low affinity for the hydrogen and this feature is offset by the affinity of hydrogen displayed by potassium, lithium, magnesium and/or sodium. Without being limited by theory it is believed that those elements of the diffusion multiple that have a high affinity for hydrogen generally facilitate adsorption of hydrogen, while those elements such as carbon that have a low affinity for hydrogen generally facilitate the desorption.

When the substrate is manufactured from a single element, the number of holes drilled in the substrate is generally equal to the minimum number of diffusion multiples desired. Thus for example, if a binary diffusion couple is desired in a substrate made from a single element such as silicon, aluminum, boron, or the like, one hole is drilled into the substrate, while if a ternary diffusion triple is desired, two holes are drilled into the substrate in close proximity to one another. As stated above, another method of making a ternary triple comprises drilling a single hole into a substrate, wherein the substrate is made up of an alloy. The holes are about 1 to about 10 millimeters in diameter. An exemplary diameter is about 5 millimeter. The thickness of the substrate is generally about 5 to about 25 millimeters in diameter. An exemplary substrate thickness is about 25 millimeters.

The distance "d" between the holes in the substrate is maintained as close as possible for those drilled in pairs. The distance d is generally about 0.1 to about 2000 micrometers. Within this range, it is generally desirable to utilize the distance to be less than or equal to about 400 micrometers. In one embodiment, it is desirable to use a distance of less than or equal to about 200 micrometers, while in another embodiment, it is desirable to use a distance of less than or equal to about 100 micrometers. In an exemplary embodiment, in one manner of proceeding, a diffusion multiple assembly comprises a silicon substrate as shown in Figure 1. The silicon substrate is used to prepare a combinatorial library from alkali metals and/or alkaline earth metals. In other words, the alkali metals and/or the alkaline earth metals are placed in the holes in the substrate to form the diffusion multiples. The substrate has a diameter of 2.0 inches and the holes containing the reactants are drilled to a depth of 0.5 inch. The reactants selected for placement in the holes in the substrate are potassium, lithium, sodium, magnesium, aluminum and calcium. As may be seen from the Figure 1, the reactants sodium, potassium, lithium and aluminum are placed into individual holes in the substrate. These may be used to prepare binary diffusion couples of the reactants with silicon.

Ternary diffusion triples of the reactants may also prepared by drilling holes in close proximity to each other as may be seen in Figure 1. The ternary triples comprise lithium and sodium with silicon, lithium and potassium with silicon, sodium and potassium with silicon, lithium and aluminum with silicon, and sodium and aluminum with silicon.

The operation of placing the light metals into the hole in the substrate is carried out in a well-controlled environment such as a glove box filled with pure argon to prevent the light-elements from oxidation. The amount of light-elements in each hole is usually less than a quarter of the volume of the hole such that there will be no pure light elements left after the interdiffusion/heat treatment step. The silicon substrate with the light-elements in the holes are then transferred to a furnace or a reactor. The furnace or reactor is either in a vacuum or a protective environment such as argon. The substrate is then heated to an elevated temperature to allow significant interdiffusion to take place among the elements in the holes and the silicon substrate.

The silicon substrate with the light metals placed in the holes is heat treated from a temperature of about 580 to about 900°C to permit the melting of the reactants or their eutectic compounds. The heat treatment is generally conducted in a convection furnace. The heat treatment to form the diffusion couple may also include using radiant heating and/or conductive heating if desired. The melted reactants diffuse and react with the silicon substrate to form silicides, doped phases, and solid-solution compositions.

When silicon carbide is used as the substrate, the heat treatment is generally conducted at temperatures of about 580 to about 1,250°C so that the formation of a diffusion multiple is facilitated within a reasonable time. An exemplary temperature for heat treatment is 600°C.

When silicon nitride is used as the substrate, the heat treatment is generally conducted at temperatures of about 600 to about 1,250°C so that the formation of a diffusion multiple is facilitated within a reasonable time. An exemplary temperature for heat treatment is 600°C.

When silicon boride is used as the substrate, the heat treatment is generally conducted at temperatures of about 580 to about 1,250°C so that the formation of a diffusion multiple is facilitated within a reasonable time. An exemplary temperature for heat treatment is 600°C.

When aluminum or germanium is used as the substrate, the substrate is heat treated from a temperature of about 400 to about 600°C to permit the melting of the reactants or their eutectic compositions. The melted reactants diffuse and react with the aluminum substrate to form aluminides, germanides, doped phases, and solid-solution compositions. An exemplary temperature for heat treatment is 450°C.

The boron substrate is heat treated from a temperature of about 660 to about 1000°C to permit the melting of the reactants or their eutectic compositions. When boron carbide is used as the substrate, the heat treatment is generally conducted at temperatures of about 660 to about 1,250°C so that the formation of a diffusion multiple is facilitated within a reasonable time. An exemplary temperature for heat treatment is 700°C.

When boron nitride is used as the substrate, the heat treatment is generally conducted at temperatures of about 660 to about 1,250°C so that the formation of a diffusion multiple is facilitated within a reasonable time. An exemplary temperature for heat treatment is 700°C.

In one embodiment, in one method of manufacturing a diffusion multiple comprising a borocarbide, a boron substrate with the desired reactants is subjected to heat treatment in a carbonaceous atmosphere. The diffusion multiples are generally ternary triples comprising a borocarbide. The heat treatment temperature for the preparation of the borocarbides is about 660 to about 2000°C.

The diffusion multiple assembly comprising the graphite. substrate is heat treated from a temperature of about 500 to about 1000°C to permit the melting of the reactants or their eutectic compounds. An exemplary temperature for heat treatment is 670°C.

When boron carbide is used as the substrate, the heat treatment is generally conducted at temperatures of about 500 to about 1000°C so that the formation of a diffusion multiple is facilitated within a reasonable time. An exemplary temperature for heat treatment is 670°C. In one embodiment, the diffusion multiple assembly is heat treated in a nitrogen atmosphere to form diffusion multiples (binary couples and ternary triples) comprising carbonitride. The heat treatment in nitrogen generally takes place at a temperature of about 550 to about 1000°C. An exemplary temperature is about 670°C.

A reasonable time period for the heat treatment of the diffusion multiple assembly is about 5 to about 100 hours. In one embodiment, it is desirable to heat treat the diffusion multiple for about 10 to about 75 hours. In another embodiment, it is desirable to heat treat the diffusion multiple for about 15 to about 50 hours. In yet another embodiment, it is desirable to heat treat the diffusion multiple for about 17 to about 40 hours. An exemplary time period of heat treatment is about 24 hours.

An embodiment exemplifying the formation of a diffusion couple or triple is depicted in the Figure 5. Figure 5(a) shows the formation of a diffusion couple in an aluminum substrate. In Figure 5(a), magnesium is used as the reactant to produce a binary diffusion couple. The block is heated to 450°C, for a period of 24 hours to permit interdiffusion to take place between the aluminum substrate and the magnesium reactant. Although the melting point of magnesium is about 650°C, the interaction of magnesium with aluminum produces an eutectic composition with a melting point of 437°C. The melted elements diffuse and react with each other to form aluminides of various compositions as exemplified by the Figure 5. In the figure it may be seen that the aluminides formed further away from the boundaries of the original hole in the aluminum substrate have a greater proportion of aluminum when compared with the proportion of magnesium. In a similar manner, Figure 5(b) shows the formation of a diffusion triple involving the use of magnesium and lithium as reactants in an aluminum substrate. The block is heated to about 450°C for 24 hours. A number of different binary aluminides are formed at the interface of the lithium or the magnesium with the aluminum. Examples of these aluminides formed at the interface of lithium with aluminum are AlLi, Al₂Li₃, or Al₄Li , while examples of aluminides formed at the interface of magnesium with aluminum are Al₃Mg₂ and Al]₂Mg] . A number of different ternary compositions comprising aluminum, lithium and magnesium are formed at the interface between the aluminum, magnesium and lithium.

After the heat treatment to form the diffusion multiple, a slicing operation may be performed on the diffusion multiple assembly. The slicing step is designed to expose different compounds/solid solutions formed at different locations of the diffusion multiple assembly as shown in Figure 6. The slicing operation is generally performed using mechanical cutting using a saw or wire discharge electro-machining (EDM). Following slicing, the respective slices may be optionally subjected to grinding and polishing if desired. Following the optional grinding and polishing operation, the samples are subjected to electron microprobe analysis and electron backscatter diffraction (EBSD) analysis to identify the phases and compounds prior to being tested for the ability of the light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides for hydrogenation. The identification of the phases or compounds as defined herein implies locating and/or analyzing the phase or the compound.

After the electron microprobe and EBSD analysis of the light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides, the resulting diffusion multiples may be converted to hydrides by exposure to hydrogen or upon hydrogenation.

The diffusion multiple comprising the light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides can generally be tested for their ability to absorb and desorb hydrogen. The composition gradients formed during the preparation of a diffusion multiple can serve as a combinatorial library to determine which specific composition can absorb and desorb hydrogen.

The ability of a light metal diffusion multiple to reversibly absorb and desorb hydrogen may be detected by a variety of analytical techniques. In general, the process of absorption of hydrogen into the silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides results in a change in appearance because of a crystal structure change and/or a volumetric expansion. In addition, the absorption of hydrogen into the silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides is generally accompanied by an exotherm, while the desorption of the hydrogen is generally accomplished by the application of heat. The analytical techniques that can be used to measure the changes in the diffusion multiples are time of flight secondary mass ion spectrometry (ToF-SIMS), tungsten oxide (WO₃) coatings and thermography. In addition, the silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides can be screened by observing the diffusion multiple after hydrogenation, since the phases that do undergo hydrogenation (i.e., hydrides) generally become pulverized.

The ToF-SIMS has the capability to detect the absorption and desorption of all elements including hydrogen, which makes it useful for the determining those compositions present in the light metal diffusion multiple that can readily be used for the storage of hydrogen. This technique can operate at temperatures of about -100 to about 600°C, has a high sensitivity to hydrogen and is therefore a useful tool for investigating the combinatorial libraries generated by the diffusion multiples. The ToF-SIMS can therefore be effectively used to map-' the absorption temperatures and the reaction conditions during the hydrogenation process.

The tungsten oxide (WO₃) generally changes its color when it reacts with hydrogen. In order to use the tungsten oxide as a detector for the hydrogen uptake in the various compositions of the diffusion multiple, the diffusion multiple is coated with WO₃ after the hydrogenation reaction. When the diffusion multiple is heated up to release the hydrogen, the WO₃ changes color as the hydrogen desorbs from the diffusion multiple.

Thermography or thermal imaging (infrared imaging) may also be used to determine the absorption and desorption of hydrogen. When a phase in the diffusion multiple absorbs hydrogen, the local temperature rises, while when the phase desorbs hydrogen, the local temperature decreases. Thermography can therefore be used to image the compounds that absorb or desorb hydrogen.

In one embodiment, the diffusion multiples disclosed above, such as the light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides can be coated with a catalyst composition and used as a hydrogen system. The diffusion multiple acts as a storage composition upon which is disposed the catalyst composition. The catalyst composition generally comprises metals that can chemisorb hydrogen with a higher sticking probability. Figure 7 shows a periodic table reflecting elements that display an appreciable sticking probability for hydrogen. In the table, all materials that have a high sticking probability are shown with plus (+) signs. Suitable examples of these metals are calcium, barium, titanium, chromium, manganese, iron, cobalt, nickel, copper, silicon, germanium, rhodium, palladium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, iridium, platinum, or a combination comprising at least one of the foregoing metals. In one embodiment the catalyst composition consists essentially of calcium, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium. In another embodiment, the catalyst composition comprises an alloy of calcium, platinum, palladium, nickel, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium.

As noted above, alloys of these metals may also be used. In one embodiment the alloys may contain platinum. In another embodiment, the alloys may contain palladium. In yet another embodiment, the alloys may contain nickel. Suitable examples of metals that may be alloyed with either platinum and/or palladium and/or nickel for the dissociation of molecular hydrogen into atomic hydrogen are calcium, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, iridium, or a combination comprising at least one of the foregoing metals.

The platinum and/or palladium and/or nickel may generally be present in an amount of about 0.1 to about 75 weight percent based on the total weight of the catalyst composition. In one embodiment, it is desirable for the platinum and/or palladium and/or nickel to be present in an amount of about 0.5 to about 70 wt%, based on the total weight of the catalyst composition. In another embodiment, it is desirable for the platinum and/or palladium and/or nickel to be present in an amount of about 3 to about 65 wt%, based on the total weight of the catalyst composition. In yet another embodiment, it is desirable for the platinum and/or palladium and/or nickel to be present in an amount of about 5 to about 50 wt%, based on the total weight of the catalyst composition.

The catalyst composition is disposed upon a storage composition. The storage composition advantageously facilitates the storage of atomic hydrogen. Suitable examples of materials that may be utilized in the storage compositions are carbon, carbides, silicides, sulfides, nitrides, oxides, oxynitrides, hydroxides, silicates, alanates, aluminosilicates, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or the like, or a combination comprising at least one of the foregoing. Exemplary forms of carbon that may be used in the storage composition are those having high surface areas such as carbon black and/or carbon nanotubes. Suitable carbon nanotubes are either vapor grown carbon fibers, single wall carbon nanotubes and/or multiwall carbon nanotubes.

Suitable oxides that may be used in the storage composition are silicon dioxide (e.g., fumed silica), alumina, ceria, titanium dioxide, zirconium oxide, tungsten oxide, vanadium pentoxide, or the like, or a combination comprising at least one of the foregoing oxides. The oxides may be prepared using aerogel technology. Metal oxides are desirable. The metal oxides generally comprise tungsten oxide (WO ), nickel oxide (MO₂), cobalt oxides (C0O₂), manganese oxides (Mn2O₄ and MnO₂), vanadium oxides (NO₂ and V₂O₅), molybdenum oxide (M0O₂), or the like, of combinations comprising at least one of the foregoing oxides.

It is generally desirable for the storage composition to have a surface area of greater than or equal to about 10 m /gm. In one embodiment, it is desirable for the storage composition to have a surface area of greater than or equal to about 50 m²/gm. In another embodiment, it is desirable for the storage composition to have a surface area of greater than or equal to about 100 m²/gm.

In one embodiment, the storage composition may comprise nanoparticles. The nanoparticles may have sizes of about 1 to about 200 nanometers upon which the catalyst composition may be disposed. In one embodiment, the particle size is about 3 to about 150 nanometers. In another embodiment, the particle size is about 5 to about 100 nanometers. In yet another embodiment, the particle size is about 10 to about 80 nanometers.

The catalyst composition is generally deposited onto the storage composition via sputtering, chemical vapor deposition, from solution, or the like. In one embodiment, the catalyst composition may completely cover a surface area of about 1 to about 100% of the total surface area of the storage composition. In one embodiment, the catalyst composition may cover a surface area of about 5 to about 90% of the total surface area of the storage composition. In another embodiment, the catalyst composition may cover a surface area of about 10 to about 75% of the total surface area of the storage composition, In yet another embodiment, the catalyst composition may cover a surface area of about 15 to about 50% of the total surface area of the storage composition.

When the catalyst composition does not cover 100% of the surface area of the storage composition, it may be desirable for the catalyst composition to be disposed onto the surface of the storage composition as isolated particulates. There is no particular limitation to the shape of the particles, which may be for example, spherical, irregular, plate-like or whisker like. Bimodal or higher particle size distributions may also be used. The particulates of the catalyst composition may have radii of gyration of about . 1 to about 200 nanometers (ran). In one embodiment, the particulates of the catalyst composition may have radii of gyration of about 3 to about 150 nanometers (nm). In another embodiment, the particulates of the catalyst composition may have radii of gyration of about 5 to about 100 nanometers (nm). In yet another embodiment, the particulates of the catalyst composition may have radii of gyration of about 10 to about 75 nanometers (nm).

In another embodiment, the nanoparticles and microparticles of the storage composition with the catalyst composition disposed upon them may be fused together under pressure to form the hydrogen storage composition. It is generally desirable for the storage composition to be present in an amount of about 30 to about 99 wt%, based on the total weight of the hydrogen storage composition. In one embodiment, it is desirable for the storage composition to be present in an amount of about 35 to about 95 wt%, based on the total weight of the hydrogen storage composition. In another embodiment, it is desirable for the storage composition to be present in an amount of about 40 to about 90 wt%, based on the total weight of the hydrogen storage composition. In yet another embodiment, it is desirable for the storage composition to be present in an amount of about 45 to about 85 wt%, based on the total weight of the hydrogen storage composition.

In one embodiment related to the storage of hydrogen, the hydrogen storage composition is immersed in an environment containing hydrogen. The hydrogen, which is molecular in structure is dissociated into atomic hydrogen by the catalyst composition and stored in the storage composition. The hydrogen is then desorbed from the hydrogen storage composition by the application of heat. The storage of hydrogen may be undertaken in a device termed an applicator. The applicator is the container that holds the hydrogen storage composition. In another embodiment, during the storage of hydrogen into the hydrogen storage composition, the hydrogen may be introduced into the applicator under pressure or the applicator may be pressurized after the introduction of hydrogen. The hydrogen storage composition may also be agitated during the storage process to obtain a uniform storage of hydrogen into the hydrogen storage composition. Since the storage of hydrogen is, in general, an exothermic reaction, the applicator may be cooled with water, liquid nitrogen, liquid carbon dioxide or air if desired during the storage of hydrogen.

As stated above, radio frequencies and microwave frequencies can be used for facilitating the storage as well as the recovery of hydrogen from the hydrogen storage compositions. The coupling of the radiation with the dipoles present in the hydrogen storage composition is used to facilitate the storage and recovery of hydrogen. In one embodiment, the frequency of the microwave and the radio wave radiation may be varied in order to effect an efficient coupling between the radiation and the dipoles of the hydrogen storage composition. Such a coupling may effectively promote the storage and/or the release of hydrogen. In another embodiment, the frequency of the microwave and the radio wave radiation may be varied with the temperature of the hydrogen storage composition in order to effectively promote the storage and/or the release of hydrogen.

In one embodiment, when the hydrogen storage composition is placed in an electromagnetic field, the power absorbed by the composition is shown in equation (VI) below:

P = ωε₀ε",E² (NI)

where P is the power absorbed per unit volume, ω = 2πf, where f is the applied frequency, ε₀ is the permittivity of free space, ε"_r is the dielectric loss factor of the material and E is the local applied electric field. From the equation (NI) it may be seen that the power absorbed is directly dependent upon the dielectric loss factor. The dielectric loss factor is dependent upon a number of factors, such as the dipole moment of various components present in the hydrogen storage composition, the temperature and the frequency of the radiation, amongst other factors.

In one embodiment, pertaining to the use of equation (VI), the dielectric loss factor in the hydrogen storage composition may be adjusted or optimized as desired to facilitate either the storage and/or release of hydrogen in the hydrogen storage composition. In another embodiment, while a first frequency (in either the microwave or radio wave range) in a first environment, may be used to facilitate the storage of hydrogen in the hydrogen storage composition, a second frequency in a second (or the first) environment, may be used to facilitate the recovery of hydrogen from the hydrogen storage composition. The environment as defined herein refers to the hydrogen storage composition as well as any agents contained in the composition that facilitate the storage and/or recovery of hydrogen when the hydrogen storage composition is coupled with radio frequency radiation and/or microwave radiation. Examples of such agents are materials having dipoles that can be heated when subjected to a radio frequency radiation and/or microwave radiation. Suitable examples of such materials are water, alcohols, dimethylformamide, acetone, carbon, silicon carbide, or the like, or combinations comprising at least one of the foregoing agents.

In general, when radio waves are utilized to effect the storage and/or desorption of hydrogen by the hydrogen storage composition, excellent uniformity and remarkable speed in absorption and/or desorption is possible. When microwaves are used, however, mechanical agitation may be utilized to facilitate uniform absorption and desorption of hydrogen by the hydrogen storage composition. Νon-uniform heating by microwaves may give rise to thermal runaway, which may result in an undesirable sintering of the hydrogen storage composition. Different frequencies within the electromagnetic spectrum may be utilized either simultaneously or sequentially to facilitate the storage and recovery of hydrogen in the hydrogen storage compositions. In one embodiment, in order to store hydrogen, it may be desirable to contact the hydrogen storage composition with a gaseous mixture containing hydrogen. In another embodiment, pertaining to the storage of hydrogen, the storage of hydrogen may occur by the exposure of the hydrogen storage composition to hydrogen that is just formed. For example, the hydrogen storage compositions may first be irradiated with radio frequency waves for a given time period, followed by irradiation at microwave frequencies during either the hydrogen storage or recovery process. Alternatively, it may be desirable to subject the hydrogen storage composition to both radio frequencies as well as microwave frequencies simultaneously during the storage and/or recovery of hydrogen. It is also envisioned that several different frequencies within the radio frequency range or within the microwave frequency range or both ranges may be sequentially or simultaneously utilized to facilitate the storage and recovery of hydrogen in the hydrogen storage composition.

In one embodiment, a method for the storage and recovery of hydrogen comprises contacting a hydrogen storage composition in a first gaseous mixture comprising hydrogen; irradiating the hydrogen storage composition with radio frequency radiation or microwave radiation having a first frequency, and wherein the irradiating is in an amount effective to facilitate the absorption, adsorption or chemisoφtion of hydrogen into the hydrogen storage composition; contacting the hydrogen storage composition with a second gaseous mixture comprising a second concentration of hydrogen; and irradiating the hydrogen storage composition with radio frequency radiation or microwave radiation having a second frequency, and wherein the irradiating is in an amount effective to facilitate the desoφtion of hydrogen from the hydrogen storage composition.

In one embodiment, the first frequency is not equal to the second frequency, but is either greater than or less than the second frequency. In one embodiment, the radio frequencies may be used to facilitate the storage of hydrogen from the hydrogen storage composition, while the microwave frequencies may be used to facilitate the recovery of hydrogen from the hydrogen storage composition. In another embodiment, microwave frequencies may be used to facilitate the storage of hydrogen from the hydrogen storage composition, while the radio frequencies may be used to facilitate the recovery of hydrogen from the hydrogen storage composition. In another embodiment, the first frequency is equal to the second frequency.

In yet another embodiment, the first concentration of hydrogen in which the hydrogen storage composition is immersed is greater than the second concentration of hydrogen, in which the hydrogen storage composition is immersed. In an exemplary embodiment, the process of contacting the hydrogen storage composition with an environment comprising a second concentration of hydrogen may involve physical movement of the hydrogen storage composition from a first location where the hydrogen storage occurs to a second location where the hydrogen recovery occurs. In another embodiment, the first location may be the same as the second location. In an exemplary embodiment, the first location may be a hydrogen storage composition generation reactor as shown in the Figure 9, while the second location may be a hydrogen generation reactor. As noted above, the hydrogen to be stored in the hydrogen storage composition may be present in a gaseous mixture comprising hydrogen or it may be formed and directly stored in the hydrogen storage composition without being mixed with other gases.

Energy generators for emitting electromagnetic radiation may be both continuous wave or pulsed wave generators and either of these types of generators may be utilized in the hydrogen storage and hydrogen generating process.

In one embodiment, combined sources of electromagnetic radiation may be utilized to facilitate the absoφtion and desoφtion of hydrogen. These sources may be from within the microwave and/or radio wave range or they may be from outside the aforementioned ranges as desired. In one exemplary embodiment, in addition to microwave and radio frequency radiation, other forms of electromagnetic energy such as infra-red radiation, ultraviolet radiation, X-ray radiation may also be used if desired.

In addition to utilizing combined sources of electromagnetic radiation (i.e., radio waves and microwaves) to facilitate the storage and recovery of hydrogen in the hydrogen storage composition, it may be desirable to supplement the energy derived from electromagnetic radiation with heating derived from other forms of thermal energy such as gas fired or electrically heated ovens or furnaces. In one embodiment, the hydrogen storage composition may be heated using convectional and/or conductive heating in conjunction with energy derived from radio frequency or microwave radiation. In such instances, while other forms of heating can be used to heat the hydrogen storage composition to any preset desired temperature, additional increases in temperature can be obtained via coupling with microwave and radio wave radiation. When conventional heating by means such as convection is alone utilized, a temperature gradient usually exists in the heated material, wherein the outer surface or skin temperature is greater than the internal or core temperature. This effect is commonly termed a 'skin-core' effect and gives rise to chemical or physical gradients within the hydrogen storage composition. Thus a combination of heating by convection or conduction as well as microwave and/or radio frequency heating can be advantageously used to enhance temperature uniformity, thereby reducing chemical concentration gradients or physical property gradients within the hydrogen storage composition.

In general, radio frequencies of about 10 kilohertz (kHz) to about 300 megahertz (MHz) can be used to facilitate the storage and recovery of hydrogen. In one embodiment, a frequency of about 1 MHz to about 250 MHz can be used. In another embodiment, a frequency of 50 to about 225 MHz can be used to facilitate the storage and recovery of hydrogen.

Microwave frequencies of about 300 MHz to about 300 gigahertz (GHz) may also effectively be used to facilitate the storage and recovery of hydrogen. In one embodiment, a frequency of about 400 MHz to about 280 GHz can be used. In another embodiment, a frequency of 600 to about 260 GHz can be used to facilitate the storage and recovery of hydrogen. In yet another embodiment, a frequency of 750 to about 250 GHz can be used to facilitate the storage and recovery of hydrogen. The frequencies of both the microwave radiation and the radio frequency radiation may be tuned to facilitate the absoφtion, adsoφtion, chemisoφtion or desoφtion of the hydrogen. In general, the electromagnetic energy delivered to the hydrogen storage composition is generally sufficient to bring about the storage without any sintering. This energy may be about 0.001 watts/gram to about 1,000 watts/gram of the hydrogen storage composition. The frequencies may be tuned to facilitate the absoφtion, adsoφtion, chemisoφtion or desoφtion of the hydrogen.

In one embodiment, during the storage of hydrogen into the hydrogen storage composition, the radio frequency or microwave energy may be introduced into the applicator or waveguide after the hydrogen storage composition is located in a desired position in the applicator. The hydrogen gas may then be introduced into the applicator. The hydrogen may optionally be introduced into the applicator under pressure or the applicator may be optionally pressurized after the introduction of hydrogen. The pressure in the applicator after the introduction of hydrogen is generally maintained at about 1 kilogram per square centimeter (kg/cm²) to about 100 kg/cm². An exemplary value of pressure in the applicator is about 30 kg/cm².

The hydrogen may be introduced into the applicator with other non-reactive gases in order to facilitate the storage process. Such a combination of hydrogen with other gases is referred to as a gaseous mixture. Examplary non-reactive gases are the inert gases. When other gases are introduced along with the hydrogen, the hydrogen content is generally about 50 to about 99 weight percent (wt%) based on the total weight of the gaseous mixture.

The radio frequency radiation or the microwave radiation can be applied to the applicator in the form of a continuous wave or in the form of a pulsed wave. The hydrogen storage composition may also be agitated during the storage process to obtain a uniform storage of hydrogen into the composition. Since the storage of hydrogen is in general an exothermic reaction, during the storage of hydrogen, the applicator may be cooled with water, liquid nitrogen, liquid carbon dioxide or air if desired.

During the recovery of hydrogen, heat may be supplied to the hydrogen storage composition to generate hydrogen. The radio frequency radiation and the microwave radiation may therefore be applied to heat the hydrogen storage composition. The heating of the composition may be accomplished by a combination of convectional heating and radio frequency radiation and/or microwave frequency radiation. During the recovery of hydrogen, the pressure in the applicator may be optionally lowered. The pressure in the applicator during the recovery of hydrogen is about 1 to about 300 millimeters of mercury (mm of Hg).

In one exemplary method of producing and storing hydrogen by using radio frequency waves (radio waves) and/or microwaves with hydrogen storage compositions, a system shown in the Figure 9 comprises an optional hydrogen storage composition reactor (a first applicator at a first location) upstream of and in fluid communication with a hydrogen generation reactor (a second applicator at a second location). As noted above, if desired, the first applicator may be different from the second applicator and the first location may be different from the second location. In another embodiment, the first applicator may be the same as the second applicator and the first location may be the same as the second location. The hydrogen storage composition reactor uses radio waves and/or microwaves to regenerate a hydrogen storage composition that is utilized to produce hydrogen in the hydrogen generation reactor. The hydrogen storage composition may be in the form of a slurry if desired.

At least a portion of the hydrogen storage composition in the hydrogen generation reactor is utilized for the recovery of hydrogen from the hydrogen storage compositions. When a hydrogen storage composition has released its hydrogen it is termed a spent hydrogen storage composition. The hydrogen generation reactor utilizes radio waves and/or microwaves to generate the hydrogen. The hydrogen generation reactor may also use convectional heating, conductional heating, PEM fuel cell exhaust, and the like, in addition to microwaves and radio waves to heat the hydrogen storage composition for puφoses of hydrogen generation. The hydrogen generation reactor is also upstream of and in fluid communication with an optional drying and separation reactor and the spent hydrogen storage composition may be optionally transferred to the drying and separation reactor. At least a portion of spent hydrogen storage composition generated in the hydrogen generation reactor is optionally recycled to the drying and separation reactor. The hydrogen generation reactor is optionally supplied with water. The optional drying and separation reactor separates any reusable fluids such as water from the spent hydrogen storage composition and recycles the fluid to the optional hydrogen storage composition reactor. The hydrogen storage composition is then recycled to the hydrogen storage composition reactor for mixing with the recycled carrier liquids and for regeneration. Besides hydrogen storage compositions, other materials such as carbon, alanates, and the like may be used to generate hydrogen in the hydrogen generation reactor.

In one embodiment, the hydrogen storage composition can be hydrogenated by subjecting them to a mixture of gases comprising hydrogen. As stated above, the hydrogen storage compositions generally release heat during the absoφtion of hydrogen. The desoφtion of hydrogen often requires thermal cycles. Such thermal cycles can be obtained by the application of electromagnetic fields or by passing electrical current through the material of interest. This can be accomplished because most hydrogenated hydrogen storage compositions are electrically conductive. The resistance of these materials changes with the extent of hydrogen storage.

In one embodiment, the desoφtion of stored hydrogen can be facilitated by the use of electromagnetic fields. Microwave energy can be directly applied to the hydrogenated hydrogen storage compositions or to a suitable medium such as water, alcohols, or the like, intermixed with the hydrogenated hydrogen storage compositions to allow for the local release of hydrogen under controlled conditions, without heating the whole system. This method provides a high efficiency of desoφtion, which generally occurs at temperatures lower than those achieved due to heating brought about by conduction and/or convection. This phenomena occurs due to a local excitation of the bonds in the hydrogen storage compositions by the microwaves. The desoφtion may be conducted by two different methods. The first of these methods comprises using microwaves to achieve a release of the entire hydrogen content. The second method comprises using a microwave treatment just to initialize the desoφtion process which then can be continued by either conductive and/or convective heating at lower temperatures and in a much easier manner than when heated by only conductive and/or convective heat from the start of the process.

In yet another embodiment, hydrogen desoφtion can be induced by the heat generated by an electrical resistor embedded in the hydrogen storage compositions. The energy of the current flowing into the resistor is converted into heat by the Joule effect. The amount of heat created locally by the current flow is particularly high in the case of a compressed powdered suicide material, with hot spots occurring on the current paths between powder particles, where the resistivity is very high. In extreme cases, powder welding may occur at the hot spots. Therefore, the current parameters should be adjusted properly to avoid sintering or powder welding. Depending on the conditions of the process, the hydrogen storage compositions may be heated directly, or by the use of multiple resistors as detailed above.

In yet another embodiment, hydrogen absoφtion and desoφtion is accomplished by mixing fine particles of the hydrogen storage compositions with an appropriate amount of another chemical composition that has a higher thermal conductivity to conduct heat faster to the hydrogenated compound for hydrogen release. In yet another embodiment, hydrogen desoφtion is accomplished by using the exhaust heat released from the proton exchange membrane (PEM) fuel cells to heat up the hydrogenated hydrogen storage compositions.

In yet another embodiment, dopants comprising titanium, vanadium zirconium, yttrium, lanthanum, nickel, manganese, cobalt, silicon, gallium, germanium, and the elements from the lanthanide series may be added to catalyze the desoφtion of hydrogen. The dopant may be added in an amount of up to about 20 wt%, of the total hydrogen storage composition prior to the storage of hydrogen. It is generally desirable to add the dopant in an amount of less than or equal to about 15 wt% of the total weight of the hydrogen storage composition. In one embodiment, the dopant can be added in an amount of less than or equal to about 10 wt%, or the total weight of the hydrogen storage composition, while in another embodiment, the dopant can be added in an amount of less than or equal to about 5 wt%, or the total weight of the hydrogen storage composition.

The hydrogen desorbed from these hydrogen storage systems comprising silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, and carbides can be about 1 to about 8 wt%, based on the total weight of the hydrogen storage composition. In one embodiment, the desorbed hydrogen is greater than or equal to about 4 wt%, based on the total weight of the hydrogen storage composition. In another embodiment, the desorbed hydrogen is greater- than or equal to about 5 wt%, based on the total weight of the hydrogen storage composition. In yet another embodiment, the desorbed hydrogen is greater than or equal to about 6 wt%, based on the total weight of the hydrogen storage composition.

As stated above, the combinatorial method of determining the capability of light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides to absorb and desorb hydrogen is quick and efficient. The light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides that are determined to absorb and desorb hydrogen may be utilized in fuel cells, gas turbines, and the like for the storage of energy.

In one exemplary method of producing and storing hydrogen from hydrides of the light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides, a system shown in Figure 8 comprises an optional slurry production reactor in upstream of and in fluid communication with a hydrogen generation reactor. The slurry production reactor regenerates a metal hydride slurry that is utilized to produce hydrogen in the hydrogen generation reactor. At least a portion of the metal hydride in the hydrogen generation reactor is oxidized to a metal hydroxide during the recovery of hydrogen from the light metal hydrides. The hydrogen generation reactor utilizes electromagnetic radiation, convectional heating, PEM fuel cell exhaust, and the like to heat the hydride for the generation of hydrogen. The hydrogen generation reactor is also upstream of and in fluid communication with an optional drying and separation reactor and the metal hydroxide is transferred to the drying and separation reactor. At least a portion of metal hydroxide generated in the hydrogen generation reactor is recycled to the drying and separation reactor. The hydrogen generation reactor is optionally supplied with water. The optional drying and separation reactor separates any reusable fluids such as water from the metal hydroxides and recycles the fluid to the optional slurry production reactor. The system also comprises a hydride recycle reactor in fluid communication with and downstream of the drying and separation reactor. Dry metal hydroxide from the drying and separation reactor is regenerated into a metal hydride in the hydride recycle reactor by contacting it with a mixture of gases comprising hydrogen. The hydride recycle reactor is supplied with carbon and oxygen in amounts effective to regenerate the metal hydride. The regenerated metal hydride is then recycled to the slurry production reactor for mixing with the recycled carrier liquids.

In another embodiment related to the storage and recovery of hydrogen from a hydrogen storage system containing a catalyst composition, the hydrogen storage composition is first contacted with a first gaseous mixture comprising a first concentration of hydrogen in a first location such as the hydrogen storage composition reactor of Figure 9. In the first location, hydrogen is dissociated into atomic hydrogen and stored in the storage composition. The hydrogen storage composition that now carries hydrogen is then contacted with a second gaseous mixture comprising a second concentration of hydrogen in a second location such as the hydrogen generation chamber of Figure 9. Here the hydrogen storage system is heated to a temperature effective to facilitate the desoφtion of hydrogen from the hydrogen storage composition. In one embodiment, the first concentration of hydrogen is greater than the second concentration. In another embodiment, the first location can be the same as the second location. In yet another embodiment, the first location is different from the second location.

This method of hydrogen storage and recovery may be advantageously be used for on board recovery of hydrogen in fuel cells placed on small vehicles such as automobiles having a weight of up to about 2,500 kilograms. This method of hydrogen storage and recovery may also be advantageously used in a land mobile such as an automobile, a train, and the like; a water craft such as a barge, ship, submarine, and the like; or an airborne carrier or a space ship such as an aiφlane, rocket, space station, and the like. It may also be used for the recovery of hydrogen in fuel cells used for power generation used for residential applications, factories, office buildings, and the like. While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method for making a combinatorial library comprising:

disposing on a substrate comprising silicon, graphite, boron, boron carbide, boron nitride, aluminum, germanium, silicon nitride, silicon carbide or silicon boride a reactant comprising a light metal;

heat treating the substrate to create a diffusion multiple having at least two phases;

contacting the diffusion multiple with hydrogen;

detecting any absoφtion of hydrogen; and/or

detecting any desoφtion of hydrogen.

2. The method of Claim 1, wherein the light metals are alkali metals or alkaline earth metals; and wherein the light metals are disposed in a hole in the substrate.

3. The method of Claim 1, wherein the light metals are lithium, magnesium, sodium, potassium, calcium, or aluminum, and wherein the light metals are disposed in a hole in the substrate.

4. The method of any of Claims 1 - 3, wherein the heat treatment is conducted at a temperature of about 200 to about 2000°C.

5. The method of any of Claims 1 - 4, wherein the heat treatment is conducted at a temperature of about 580 to about 900°C when the substrate is silicon; a temperature of about 580 to about 1250°C when the substrate is silicon boride; a temperature of about 580 to about 1250°C when the substrate is silicon carbide; a temperature of about 600 to about 1250°C when the substrate is silicon nitride; a temperature of about 400 to about 600°C when the substrate is aluminum or germanium; a temperature of about 660 to about 1000°C when the substrate is boron; a temperature of about 660 to about 1250°C when the substrate is boron nitride; or a temperature of about 500 to about 1000°C when the substrate is graphite.

6. The method of any of Claims 1 - 5, wherein at least a reactant is disposed in the substrate and forms a binary couple upon heat treatment.

7. The method of any of Claims 1 - 5, wherein at least a reactant is disposed in the substrate and forms a ternary triple upon heat treatment.

8. The method of any of Claims 1 - 5, wherein at least two reactants are disposed in the substrate and forms a ternary triple upon heat treatment.

9. The method of any of Claims 1 - 8, further comprising identifying and analyzing at least one phase of the diffusion couple using electron microprobe analysis.

10. The method of any of Claims 1 - 9, further comprising slicing and grinding the diffusion multiple.

11. The method of any of Claims 1 - 10, further comprising analyzing the diffusion multiple by electron microprobe analysis or electron backscatter diffraction.

12. A method of recovering hydrogen comprising:

contacting at least one compound selected from the group consisting of AlSi, Ca₂Si, CaSi, CaSi₂, KSi, K₄Si₂₃, Li₂ Si₅, Li_{] 3}Si₄, Li₇Si₃, Li,₂Si₇, Mg₂Si, NaSi, NaSi₂, Na₄Si₂₃, A1B₂, A1B,₂, B₆Ca, B₆K, B,₂Li, B₆Li, B₄Li, B₃Li, B₂Li, BLi, B₆Li₇, BLi₃, MgB₂, MgB₄, MgB₇, NaB₆, NaB₁₅, NaB_16, AlLi, Al₂Li₃, Al₄Li₉, Al₃Mg₂, Al_I2Mgι₇, A1B₁₂, Ge K, GeK, GeK , GeLi , Ge₅Li ₂, Mg₂Ge, Ge Na, GeNa, GeNa₃, aluminum doped Ge K, aluminum doped GeK, aluminum doped GeK , aluminum doped GeLi₃, aluminum doped Ge₅Li22, aluminum doped Mg₂Ge, aluminum doped Ge₄Na, aluminum doped GeNa, aluminum doped GeNa₃, A1₄C₃, Na₄C₃, Li₄C₃, K C₃, LiC, LiC₆, Mg₂C₃, MgC₂, AlTi₂C, AlTi₃C, AlZrC₂, Al₃Zr₅C, Al₃Zr₂C₄, Al₃Zr₂C₇, KC₄, NaC , or a combination comprising at least one of the foregoing compounds in hydrogen to form a hydrogenated compound; and

heating the hydrogenated compound to recover the hydrogen.

13. A method of regenerating hydrogen comprises : contacting a compound with hydrogen to form a hydrogenated compound; wherein the compound has at least one of the formulas (I) through (V)

(Li_a, Na_b, Kc, Al_d, Mge, Ca_f)_x (B, C, N, Si)_y (I)

(Li_a, Na_b, Mg_c, Kd, Ca_c, Ge_f)_x (Al)_y (II)

(Li_a, Na_b, Mg_c, K_d, Ca_e, Al_f)_x (Ge)_y (III)

(Li_a, Na_b, Kc, Ai_d, Mge, Ca_f)_x (B, C, N)_y (IV)

(Li_a, Na_b, Kc, Aid, Mge, Ca_f)_x (B, N, C)_y (V)

where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Al is aluminum; Ge is germanium, B is boron, C is carbon and N is nitrogen, Si is silicon; a, b, c, d, e and f may be the same or different and have values from 0 to 1 ; and x and y have values of about 1 to about 22; and

heating the hydrogenated compound to recover the hydrogen.

14. The method of any of Claims 12-13, wherein the heating is conducted using microwave radiation, convectional heating, electrical resistive heating, or a combination comprising at least one of the foregoing methods of heating.

15. The method of any of Claims 12-14, further comprising the step of adding a dopant comprising titanium, vanadium zirconium, yttrium, lanthanum, nickel, manganese, cobalt, silicon, gallium, germanium, and the elements from the lanthanide series to the compound in an amount of less than or equal to about 20 wt% of the diffusion multiple.

16. The method of any of Claims 12-15, wherein the heating is effected by exhaust heat of a fuel cell.

17. An energy generation device, wherein the method of any of Claims 12 - 16 is employed to generate energy.

18. A compound of a diffusion multiple having at least one of the formulas (I) through (V)

(Li_a, Na_b, K_c, Ald, Mge, Ca_f)_x (B, C, N, Si)_y (I)

(Li_a, Na_b, Mg_c, K_d, Ca_e, Ge_f)_x (Al)_y (II)

(Lia, Na_b, Mgc, K_d, Ca_e, Al_f)_x (Ge)_y (III)

(Li_a, Na_b, Kc, Al_d, Mg_e, Ca_f)_x (B, C, N)_y (IV)

(Li_a, Na_b, Kc, Ai_d, Mg_e, Ca_f)_x (B, N, C)_y (V)

19. The compound of Claim 18, wherein the sum of a, b, c, d, e, and f is equal to 1.

20. A composition comprising:

a hydride of a compound, wherein the compound is AlSi, Ca₂Si, CaSi, CaSi₂, KSi, K Si₂₃, Li₂₂Si₅, Liι₃Si₄, Li₇Si₃, Li₁₂Si₇, Mg₂Si, NaSi, NaSi₂, Na₄Si₂₃, A1B₂, AlBι₂, B₆Ca, B₆K, B,₂Li, B₆Li, B₄Li, B₃Li, B₂Li, BLi, B₆Li₇, BLi₃, MgB₂, MgB₄, MgB₇, NaB₆, NaB,₅, NaB,₆, AlLi, Al₂Li₃, Al₄Li₉, Al₃Mg₂, Al₁₂Mgι₇, A1B,₂, Ge₄K, GeK, GeK₃, GeLi₃, Ge₅Li₂₂, Mg₂Ge, Ge Na, GeNa, GeNa₃, aluminum doped Ge₄K, aluminum doped GeK, aluminum doped GeK₃, aluminum doped GeLi₃, aluminum doped Ge₅Li₂₂, aluminum doped Mg₂Ge, aluminum doped Ge₄Na, aluminum doped GeNa, aluminum doped GeNa₃, A1 C , Na₄C , Li C₃, K C₃, LiC, LiC₆, Mg₂C₃, MgC , AlTi₂C, AlTi₃C, AlZrC₂, Al₃Zr₅C, Al₃Zr₂C₄, AI₃Z1-₂C₇, KC₄, NaC₄, or a combination comprising at least one of the foregoing compounds.

21. A hydrogen storage composition comprising: a catalyst composition disposed upon a storage composition; wherein the catalyst composition consists essentially of calcium, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium.

22. A hydrogen storage composition comprising:

a catalyst composition disposed upon a storage composition; wherein the catalyst composition comprises an alloy of calcium, barium, platinum, palladium, nickel, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, iridium, or a combination comprising at least one of the foregoing metals.

23. The composition of any of Claims 21 - 22, wherein the storage composition comprises carbon, carbides, silicides, sulfides, nitrides, oxides, oxynitrides, hydroxides, silicates, alanates, aluminosilicates, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or a combination comprising at least one of the foregoing.

24. The composition of Claim 23, wherein the carbon comprises carbon black and/or carbon nanotubes; and wherein the oxides are metal oxides.

25. The composition of Claim 24, wherein the metal oxides are alumina, ceria, titanium dioxide, zirconium oxide, tungsten oxide (WO₃), nickel oxide (NiU₂), cobalt oxide (C0O₂), manganese oxides (Mn₂O and Mnθ2), vanadium oxides (VO₂ and V₂O₅), molybdenum oxide (MoO ), or a combination comprising at least one of the foregoing oxides.

26. The composition of any of Claims 22 - 25, wherein the alloy comprises platinum, palladium and/or nickel.

27. The composition of any of Claims 21 - 26, wherein the catalyst composition covers a surface area of about 1 to about 100% of the total surface area of a storage composition.

28. The composition of any of Claims 21 - 27, wherein the catalyst composition is disposed onto the surface of a storage composition as isolated particulates.

29. The composition of Claim 28, wherein the isolated particulates have a radius of gyration of about 1 to about 200 nanometers.

30. A method for storing hydrogen comprising:

immersing in a gaseous mixture comprising hydrogen, a hydrogen storage composition comprising a catalyst composition disposed upon a storage composition, wherein the catalyst composition comprises an alloy of calcium, platinum, palladium, nickel, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium;

dissociating the hydrogen into atomic hydrogen; and

storing the atomic hydrogen in the storage composition.

31. A method for generating hydrogen comprising:

heating a hydrogen storage composition comprising a catalyst composition disposed upon a storage composition, wherein the catalyst composition catalyst composition consists essentially of calcium, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium; or wherein the catalyst composition comprises an alloy of calcium, platinum, palladium, nickel, barium, titanium, chromium, manganese, iron, cobalt, copper, silicon, germanium, rhodium, rhodium, ruthenium, molybdenum, niobium, zirconium, yttrium, barium, lanthanum, hafnium, tungsten, rhenium, osmium, or iridium.

32. A method for the storage and recovery of hydrogen comprising: contacting a hydrogen storage composition with a first gaseous mixture comprising a first concentration of hydrogen;

dissociating the hydrogen into atomic hydrogen;

storing the atomic hydrogen in the storage composition;

contacting the hydrogen storage composition with a second gaseous mixture comprising a second concentration of hydrogen; and

heating the hydrogen storage to a temperature effective to facilitate the desoφtion of hydrogen from the hydrogen storage composition.

33. The method of Claim 34, wherein the first concentration of hydrogen is greater than the second concentration.

34. The method of any of Claims 32 - 33, wherein the contacting a hydrogen storage composition in a gaseous mixture comprising a first concentration of hydrogen is conducted at a first location, and wherein the contacting the hydrogen storage composition in an environment comprising a second concentration of hydrogen is conducted at a second location.

35. The method of Claim 34, wherein the first location is not the same as the second location.

36. The method of Claim 34, wherein the first location is the same as the second location.

37. A system for the storage and recovery of hydrogen comprising:

a hydrogen generation reactor in fluid communication with a hydride recycle reactor, wherein the hydrogen generation reactor utilizes hydrides of light metal silicides, borosilicides, carbosilicides, nitrosilicides, aluminides, germanides, borides, borocarbides, boronitrides, or carbides to recover hydrogen.

38. The system of Claim 37, wherein the hydrogen generation reactor is in fluid communication with and down stream of a slun production reactor.

39. The system of any of Claims 37 - 28, wherein the hydrogen generation reactor is in fluid communication with and up stream of a drying and separation reactor.

40. The system of any of Claims 38 - 39, wherein the slurry production reactor is in fluid communication with and downstream of a drying and separation reactor.

41. The system of any of Claims 38 - 40, wherein the hydride recycle reactor is in fluid communication with a slurry production reactor.

42. The system of any of Claims 37 - 41, wherein a metal hydride slurry is transferred to the hydrogen generation reactor from a slurry production reactor.

43. The system of Claim 37, wherein a regenerated metal hydride is transferred from the hydride recycle reactor to a slurry production reactor.

44. The system of Claim 39, wherein water is introduced into the hydrogen generation reactor.

45. The system of Claim 39, wherein hydrogen is generated in the hydrogen generation reactor by the use of heat from microwave radiation, convective heat, exhaust heat from a fuel cell.

46. A method for the storage of hydrogen comprising:

contacting a hydrogen storage composition with a gaseous mixture comprising hydrogen; and

irradiating the hydrogen storage composition with radio frequency radiation or microwave radiation in an amount effective to facilitate the absoφtion, adsoφtion or chemisorption of hydrogen into the hydrogen storage composition.

47. The method of Claim 48, wherein the contacting is conducted at a pressure of about 1 to about 100 kilogram per square centimeter.

48. The method of Claim 48, wherein the irradiating is conducted at about 10 kilohertz to about 300 gigahertz and wherein the irradiating imparts to the hydrogen storage composition an energy of about 0.001 watt/gram to about 1 ,000 watts/gram.

49. A method for the storage and recovery of hydrogen comprising:

contacting a hydrogen storage composition with a first gaseous mixture comprising a first concentration of hydrogen;

irradiating the hydrogen storage composition with a radio frequency radiation or microwave radiation having a first frequency in an amount effective to facilitate the absoφtion, adsoφtion and/or chemisoφtion of hydrogen into the hydrogen storage composition;

irradiating the hydrogen storage composition with a radio frequency radiation or microwave radiation having a second frequency in an amount effective to facilitate the desoφtion of hydrogen from the hydrogen storage composition.

50. The method of Claim 51 , wherein the first concentration of hydrogen is greater than the second concentration.

51. The method of Claim 51 , wherein the first frequency is not equal to the second frequency.

52. The method of Claim 51 , wherein the first frequency is equal to the second frequency.

53. The method of any of Claims 49 - 52, wherein the contacting a hydrogen storage composition in a gaseous mixture comprising a first concentration of hydrogen is conducted at a first location, and wherein the contacting the hydrogen storage composition in an environment comprising a second concentration of hydrogen is conducted at a second location.

54. The method of Claim 53, wherein the first location is not the same as the second location.

55. The method of Claim 53, wherein the first location is the same as the second location.

56. The method of Claim 51, wherein the irradiating is conducted at about 10 megahertz to about 300 gigahertz and wherein the irradiating imparts to the hydrogen storage composition an energy of about 0.001 watt/gram to about 1,000 watts/gram.

57. The method of any of Claims 49 - 56, wherein the hydrogen storage composition comprises carbon, aluminides, alanates, carbides, borides, nitrides, borocarbides, boronitrides, silicides, borosilicides, carbosilicides, or nitrosilicides.

58. A system for the storage and recovery of hydrogen comprising:

a hydrogen generation reactor, wherein the hydrogen generation reactor utilizes radio frequency radiation and/or microwave frequency radiation to recover hydrogen.

59. The system of Claim 58, wherein the hydrogen generation reactor is in fluid communication with and down stream of a hydrogen storage composition reactor.

60. The system of Claim 58, wherein the hydrogen generation reactor is in fluid communication with and up stream of a hydrogen storage composition reactor and further wherein the hydrogen storage composition reactor utilizes radio frequency radiation and/or microwave frequency radiation to store hydrogen.

61. The system of Claim 58, wherein the hydrogen generation reactor is in fluid communication with and up stream of a drying and separation reactor and further wherein the hydrogen storage composition reactor utilizes radio frequency radiation and/or microwave frequency radiation to store hydrogen.

62. The system of Claim 61 , wherein the hydrogen storage composition reactor is in fluid communication with and downstream of a drying and separation reactor.

63. The system of Claim 61 , wherein a hydrogen storage composition slurry is transferred to the hydrogen generation reactor from a hydrogen storage composition reactor.