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US-12624421-B2 - Aluminum based nanogalvanic compositions useful for generating hydrogen gas and low temperature processing thereof

US12624421B2US 12624421 B2US12624421 B2US 12624421B2US-12624421-B2

Abstract

Alloys comprised of a refined microstructure, ultrafine or nano scaled, that when reacted with water or any liquid containing water will spontaneously and rapidly produce hydrogen at ambient or elevated temperature are described. These metals, termed here as aluminum based nanogalvanic alloys will have applications that include but are not limited to energy generation on demand. The alloys may be composed of primarily aluminum and other metals e.g., tin bismuth, indium, gallium, lead, etc. and/or carbon, and mixtures and alloys thereof. The alloys may be processed by ball milling for the purpose of synthesizing powder feed stocks, in which each powder particle will have the above-mentioned characteristics. These powders can be used in their inherent form or consolidated using commercially available techniques for the purpose of manufacturing useful functional components.

Inventors

  • Billy C. Hornbuckle
  • Anthony J. Roberts
  • Thomas L Luckenbaugh
  • Anit K. Giri
  • Kristopher A. Darling

Assignees

  • U.S. Gov't as represented by Sec of Army

Dates

Publication Date
20260512
Application Date
20220907

Claims (12)

  1. 1 . A galvanic metal microstructure comprising: an anodic matrix comprising aluminum, an aluminum alloy or another aluminum-based composition; and a cathodic disperse phase comprising a second metal, second alloy or other second metal-based composition is selected from the group consisting of: tin (Sn), magnesium (Mg), silicon (Si), bismuth (Bi), lead (Pb), gallium (Ga), indium (In), zinc (Zn), and mixtures and alloys thereof, wherein said cathodic disperse phase comprises small particles of an aluminum alloy or aluminum-based composition comprised of aluminum and the second metal, the second alloy or the other second metal-based composition having a particle size, as measured along the longest axis of the particle, from about 2 nm to no more than about 100 nm, and forms galvanic couples with the anodic matrix to produce hydrogen gas when said galvanic metal microstructure contacts with water, a water containing liquid or another electrolyte, wherein, when said galvanic metal microstructure contacts water, a water containing liquid or another electrolyte, it produces at least 1000 mL of H 2 gas per gram of aluminum at 25° C. (298 K) and 1 atm. within about 5 minutes.
  2. 2 . The galvanic metal microstructure of claim 1 wherein the cathodic disperse phase comprises small particles having diameters between 2 nm and 10 nm.
  3. 3 . The galvanic metal microstructure of claim 1 wherein the cathodic disperse phase also comprises large particles having a size of about 10 nm to 1 mm.
  4. 4 . The galvanic metal microstructure of claim 3 wherein the small particles reside within grains of the anodic matrix and the large particles reside between grains of the anodic matrix.
  5. 5 . The galvanic metal microstructure of claim 3 wherein the large particles consist essentially of the second metal, the second alloy or the other second metal-based composition.
  6. 6 . The galvanic metal microstructure of claim 5 wherein the large particles comprise approximately 60 at. % Mg and 40 at % Sn.
  7. 7 . The galvanic metal microstructure of claim 1 wherein the cathodic disperse phase also comprises stringers having sizes from about 10 nm to about 10 mm in size.
  8. 8 . The galvanic metal microstructure of claim 1 wherein the galvanic metal microstructure comprises grains having a diameter of no more than about 10 cm.
  9. 9 . The galvanic metal microstructure of claim 1 wherein the small particles comprises at least 65 at. % Al, 2-15 at. % Sn and 2-20 at. % Mg.
  10. 10 . The galvanic metal microstructure of claim 1 wherein the small particles have a density of between about 10 15 and 10 25 per cubic meter.
  11. 11 . The galvanic metal microstructure of claim 1 wherein the aluminum alloy is selected from the group consisting of 1000, 2000, 3000, 5000, 6000 and 7000 series aluminum alloys.
  12. 12 . A method of generating hydrogen, comprising: providing a galvanic metal microstructure according to claim 1 ; causing a reaction by contacting the galvanic metal microstructure with a liquid comprising at least one hydroxyl group; and capturing or using spontaneously generated hydrogen.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application is a continuation-in-part (CIP) of U.S. patent application Ser. No. 16/579,089 filed on Sep. 23, 2019, now U.S. Pat. No. 12,054,809, which in turn is a divisional of U.S. patent application Ser. No. 16/042,632 filed on Jul. 23, 2018, now U.S. Pat. No. 11,198,923, that claims the benefit of U.S. Provisional Patent Application No. 62/536,143 titled “Aluminum Based Nanogalvanic Alloys for Hydrogen Generation” and filed on Jul. 24, 2017. The entire contents of the parent patent applications and the provisional patent application, including all attachments and documents referenced therein, are hereby incorporated by reference herein. GOVERNMENT INTEREST The embodiments described herein may be manufactured, used, and/or licensed by or for the United States Government without the payment of royalties thereon. BACKGROUND Technical Field The embodiments herein generally relate to aluminum alloys and aluminum-based microstructures that are useful for generating hydrogen gas. Hydrogen has one of the highest energy density values per unit mass, 142 MJ/kg which is equivalent to 39.4 kWh of combustible energy. With such a large energy content, hydrogen can be used to generate power. Hydrogen gas can be used in cars, in houses, for portable power, and in many more military and civilian applications. Hydrogen can be generated by any of the following processes: biomass gasification, biomass derived liquid forming, natural gas reforming, coal gasification, thermochemical water splitting, electrolysis, photobiological, and microbial biomass conversion (https://energy.gov/eere/fuelcells/hydrogen-production). Another way to produce hydrogen is reacting certain chemical compounds, metals and alloys with certain solvents e.g., methanol, water, etc. Aluminum reacts with water to produce hydrogen gas according to the following equations: 2Al+6H2O=2AL(OH)3+3H2+Heat 2Al+4H2O=2ALOOH+3H2+Heat 2Al+3H2O=2AL2O3+3H2+Heat However, it is often necessary for the solvent to be at high temperature and for the water to be additionally alkaline (e.g., sodium hydroxide and potassium hydroxide) or acidic (e.g., hydrochloric acid and nitric acid) for the hydrogen producing reaction to take place. It is also often necessary to use a catalyst e.g., expensive platinum, gallium metal and/or externally applied power etc. Moreover, many of the chemicals and the solvents are highly toxic e.g., methanol, sodium borohydride, lithium hydride, etc. and so also the reaction byproduct. It is well known that under certain conditions aluminum can react with water at room temperature to produce hydrogen and non-hazardous aluminum oxide/hydroxide or some combination thereof. This reaction releases heat equivalent to 4.3 kWh of energy per kg of aluminum. 1 kg of aluminum reacting water produces 111 g of hydrogen that is equivalent to 4.4 kWh of combustible energy. Thus, a total of 8.7 kWh of energy per kg of aluminum could be released from the aluminum-water reaction that could be utilized for a multitude of applications. Water is readily available almost everywhere so in many cases it is not necessary to carry it, thereby removing the associated energy density penalty. However, if it needs to be carried, the total potential energy per kg of Al+ water will be 4.3 kWh. For certain applications, e.g., fuel cell applications, it is possible to reclaim 50% of the water; and in that case the total potential energy available will be 5.8 kWh/kg. The energy density of gasoline and methanol, the two most common fuels, are 12.8 kWh and 5.5 kWh per kg., respectively. The gravimetric energy density of Al (with and/or without water) is similar to methanol, and 33%-66% of gasoline. In certain situations, it is more important to consider the volumetric energy density than the gravimetric. In this regard, aluminum has the highest volumetric energy density among non-nuclear fuels—more than twice that of gasoline and more than five times that of methanol. If water is available, aluminum is a very desirable choice to generate power via hydrogen generation. If the total required volume of water is considered, the volumetric energy density of aluminum is 65% that of gasoline. However, when the hydrogen is used in fuel cell technology, 50% of the water can be reclaimed and utilized (i.e. removing half of the amount of water) then the energy density equals approximately that of gasoline. Currently methanol is the principal choice as the source of hydrogen for fuel cells. Hydrogen generated from aluminum can replace methanol. Thus, it is an object of the present invention to generate hydrogen gas using aluminum and water or a water containing liquid such as waste water, gray water, urine or any other liquid that contains water. Aluminum reacts with water to produce hydrogen via the hydrolysis reaction. However in the case of aluminum powders, immediate oxidation (referred to in this case as passivation) occurs at room temper