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In the long term, hydrogen is expected to be the fuel of choice for both the power and transportation industries. Just as conventional cars need gas stations, hydrogen-powered fuel cell cars will need an infrastructure. Hydrogen separation technology is integral to successful fossil-based hydrogen production technologies. Thin, dense composite membranes fabricated from ceramic and hydrogen-transport metal may provide a simple, efficient means for separating hydrogen from fossil-based gas streams. New ceramic-metal composite (cermet) membranes developed at Argonne, called hydrogen transport membranes, could eliminate the need for costly, conventional hydrogen-manufacturing facilities; the membranes could one day be small and efficient enough to be installed at every gas station.
Membranes currently used by industry to separate gases are not selective enough to isolate pure hydrogen—the simplest and smallest of all elements. Argonne has developed a composite cermet that transports only atomic hydrogen, allowing the membrane to separate pure hydrogen for use as a clean-burning fuel and in production of fertilizers and other products. The new membrane material works on a different principle than conventional porous membranes; hydrogen is the only species that passes through it because it dissolves in, and diffuses rapidly through, the metal phase in the composite. Unlike most membrane systems, Argonne's hydrogen membrane tolerates temperatures as high as 900 degrees Celsius. Such elevated temperatures push more hydrogen atoms into the membrane, accelerating the rate of gas separation.
The most likely raw feedstock material for hydrogen separation is syngas, a mixture of hydrogen and carbon monoxide made by reacting natural gas with oxygen. Because syngas can be expensive to produce, Argonne is exploring the use of another membrane to extract oxygen. The team has demonstrated that the oxygen membranes successfully separate oxygen and that this separated oxygen, when reacted with methane, forms syngas. Because Argonne's oxygen and hydrogen membranes both function at the same high temperatures, they can work in tandem: one membrane adding oxygen to methane to create syngas and the other extracting hydrogen from the syngas.
Platinum is the most efficient electrocatalyst for accelerating the oxygen reduction reaction in fuel cells. It is also expensive. Palladium-cobalt particles have been used to replace platinum to catalyze this reaction, leading to a much lower cost electrocatalyst.
Ternary alloys of palladium, cobalt, and a third transition metal are formed into nanoparticles, bound to a conducting medium, and applied as the anode in a fuel cell to reduce oxygen. Palladium-cobalt alloys may also incorporate two additional transition metals to make a four-component, or quaternary, alloy. These alloys are deployed on the anode of fuel cells as electrocatalysts for the oxygen reduction reaction. Nickel and iron are preferred transition metal components.
Iowa State University and Ames Laboratory researchers have developed a process for the synthesis of alane with quantitative yields at ambient temperature and moderate hydrogen or ambient gas pressure while controlling side reactions.This novel synthesis route significantly increases yields and reduces the production costs for this compound.
Alane exceeds the DOE performance criteria for hydrogen storage for transportation vehicles, but does not have a cost-efficient production route. Synthesis of alane by metathesis reactions in organic solvents is inefficient because of the need to remove solvents from the resultant alane solvates that inevitably leads to thermal decomposition of a substantial fraction of the formed alane. Traditional mechanochemical synthetic routes require cryogenic processing to control side reactions leading to decomposition of more than 60% of the formed alane. This new method allows for the use of a mechanochemical process at ambient temperatures and slightly elevated hydrogen or inert gas pressures to produce alane while still suppressing side reactions to produce alane in quantitative yields. By eliminating the desolvation step inherent in the solvent-based route and the cryogenic environment of traditional mechanochemical synthesis, this novel synthesis route significantly increases yields and reduces the production costs for this compound.
Anisotropic growth of palladium nanoparticles on high surface area carbon supports is encouraged by the choice of surface preparation and electrochemical deposition parameters. The resultant nanorods and nanowires have extremely smooth surfaces, improving their catalytic activity for the oxygen reduction reaction in fuel cells, as well as for other reactions. These ultra-smooth surfaces can be used as-grown, or may be subjected to further processing, such as deposition of monolayers of platinum or gold, to further enhance catalytic activity. These materials are well suited to heterogeneous catalysis and electrocatalysis, especially at fuel cell electrodes.
Platinum is an excellent catalyst for many reactions. However, it is also easily poisoned by carbon monoxide and very expensive. Tolerance to carbon monoxide can be increased by using a particle composite consisting of clusters or an atomically thin layer of the platinum on a ruthenium particle. When used as an electrocatalyst for the oxidation of fuel at a fuel cell anode, this structure exhibits low platinum loading and elevated tolerance to carbon monoxide when compared to commercially available platinum/carbon electrocatalysts. These structures can be used in fuel cells and other electrocatalytic or heterogeneous catalytic applications.
Ruthenium nanoparticles are deposited on a conductive support and exposed to hydrogen at elevated temperature. The hydrogen-exposed nanoparticles are then cooled and placed in contact with a solution of Group VIII noble metal compound(s), such as platinum. The noble metal is deposited on the surface of the nanoparticles as clusters or an atomically thin layer, forming an active electrocatalyst.
Platinum is the most efficient electrocatalyst for accelerating the oxygen reduction reaction in fuel cells. Under operating conditions, though, platinum catalysts can dissolve. When used in place of pure platinum, platinum-metal oxide composites can spare the precious metal when used as fuel cell catalysts.
Metal oxides are not typically conductive enough to be good substrates for electrochemical deposition of metals. In the inventive method, non-noble metal cations are first adsorbed onto the surface of a metal oxide core. The cation adsorbate is then reduced to provide an appropriate surface for the subsequent deposition of noble metal from a solution of metal salts.
Platinum is a very good, albeit expensive, electrocatalyst. In order to increase the catalytic activity of an electrocatalyst per mass platinum (the platinum mass activity), nanoparticles of less expensive materials are coated with atomically thin layers of platinum. The nanoparticles have a core-shell structure and include palladium, gold, and their alloys with other transition metals. The platinum-coated composite can be used as an electrocatalyst in place of pure platinum, for example, in fuel cells.
A particle composite includes a nanoparticle having a core at least partially encapsulated by a shell of a different composition, the resulting core-shell nanoparticle at least partially encapsulated by an atomically thin layer of platinum. Particularly useful composites include platinum-encapsulated core-shell nanoparticles in which the core is a first-row transition metal and the shell is a noble metal other than platinum. The core-shell nanoparticles may be formed by subjecting a homogeneous allow of a noble metal and a non-noble metal to a heat treatment during which segregation of elements occurs, resulting in a core highly enriched in the non-noble metal and a shell highly enriched in the noble metal.
A typical membrane electrode assembly (MEA) consists of five distinct layers: A polymer electrolyte membrane (PEM) sandwiched between an anode and a cathode catalyst layers, each with a gas diffusion layer (GDL) to provide electrical connection and the path for inlet gaseous reactants in fuel cells or outlet products in hydrogen generators. To make highly efficient MEAs with low catalyst loadings, the nanocatalysts need to be well connected electronically to the GDLs and protonically to the PEM, yet the catalyst layer (CL) must be sufficiently porous to allow gases in or out.
This invention describes the advantages of coating nanocatalysts on a GDL, preferably with a microporous layer (MPL), for simultaneously minimizing electronic, protonic, and gas diffusion resistances, and thus, enhancing performance and lowering costs.
INL’s new phosphazene membrane technology provides a method for making polydichlorophosphazene using solid state reactants that simplifies previous processes with a “single pot” two-step process. The process eliminates use of chlorinated hydrocarbon solvents, reducing the costs of equipment and increasing economies. Polyphosphazene polymers are inorganic in nature and consist of alternating phosphorus and nitrogen atoms with alternating double and single bonds.
Phase one of the process requires ammonium sulfate and phosphorus pentachloride to be heated at 150 to 180oC for a period of time (e.g. 5-300 minutes depending on the desired production amount of P-trichloro-N; (dichlorophosphoryl) monophosphazene). In phase two, the product from phase one is heated in a dry nitrogen or argon atmosphere until oxyphosphoryltrichloride is distilled off. Temperatures of 200 to 300oC are required for this process and a time frame of 2 to 500 minutes.
These polymers can be used at both high and low temperatures and in caustic and acidic environments. Polyphosphazene can be used in a membrane to separate individual gases from gas mixtures, as well as to separate polar and nonpolar gases. Phosphazene Polymers are valuable in several industries including: environmental cleanup, mineral processing and potential for use in dentistry, aerospace and military. Other uses include producing “potable water” from sea water, recovering valuable constituents of solutions by electrolysis, and to separate, remove, purify, or partially recover individual components of gas mixtures.INL Technology ID: B-385
Metal aminoboranes of the formula M(NH.sub.2BH.sub.3).sub.n have been synthesized. Metal aminoboranes are hydrogen storage materials. Metal aminoboranes are also precursors for synthesizing other metal aminoboranes. Metal aminoboranes can be dehydrogenated to form hydrogen and a reaction product. The reaction product can react with hydrogen to form a hydrogen storage material. Metal aminoboranes can be included in a kit.
Berkeley Lab researchers Mike Tucker, Grace Lau, and Craig Jacobson have invented a novel layered structure for preparing a high-operating temperature electrochemical cell.
The structural support is porous metal, an unconventional approach which imparts strength, while use of the more expensive ceramic and cermet materials is confined to the thin active layers. Due to several unique processing techniques, a wider range of catalysts can be introduced into the structure than current methods allow. The Berkeley Lab process renders a robust, well-bonded electrochemical device that could be manufactured at significantly reduced cost.
Arlon Hunt and Samuel Mao and colleagues at Berkeley Lab have developed a new class of hydrogen and carbon dioxide (CO2) storage materials with favorable storage capacities under conditions suitable for on-board vehicle use.
The inventors are the first to use an oxide aerogel medium as the basic nanostructured framework for solid-based hydrogen and CO2 storage and capture. The highly porous medium is subjected to vapor infiltration with metal hydride or carbon to form a linked three-dimensional network of nanostructures.
The new Berkeley Lab materials take advantage of the high formula storage capacities of metal hydrides, for example, while overcoming their slow sorption kinetics and the need for high temperature desorption by incorporating the hydrides into an nanostructured template.