The rapid development in recent years of the proton-exchange membrane (PEM) fuel cell technology has stimulated research in all areas of fuel processor catalysts for hydrogen generation. The principal aim is to develop more active catalytic systems that allow for the reduction in size and increase the efficiency of fuel processors. The overall selectivity in generating a low CO content hydrogen stream as needed by the PEM fuel cell catalyst is dependent on the efficiency of the catalysts in each segment of the fuel processor. This article reviews the advances achieved during the past few years in the development of catalytic materials for hydrogen generation through fuel reforming, 1 water-gas shift and carbon monoxide preferential oxidation, as used or aimed to be of use in fuel processing for PEM fuel cell systems.

Review of fuel processing catalysts for hydrogen production in PEM fuel cell systems

The invention relates to a luminescence conversion led based illumination deice that emits primarily radiation in the range of from 370 and 430 nm of the optical spectrum (peak wavelength). Said radiation is converted to radiation having a longer wavelength using three luminescent substances that emit in the red, green and blue range.

Illumination device with at least one LED as the light source

Methods and apparatuses are provided for forming fine particles of a desired substance comprising dissolving said substance in a fluid such as water to form a solution and mixing the solution with a second fluid such as supercritical carbon dioxide which becomes a gas upon rapid pressure release, and with which the first fluid is at least partially immiscible, and releasing the pressure to form an air-borne dispersion or aerosol comprising particles having an average diameter between about 0.1 and about 6.5 μm.

Methods and apparatus for fine particle formation

An electrochemical fuel cell stack with improved reactant manifolding and sealing includes a pair of separator plates interposed between adjacent membrane electrode assemblies. Passageways fluidly interconnecting the anodes to a fuel manifold and interconnecting the cathodes to an oxidant manifold are formed between adjoining non-active surfaces of the pairs of separator plates. The passageways extend through one or more ports penetrating the thickness of one of the plates thereby fluidly connecting the manifold to the opposite active surface of that plate, and the contacted electrode. The non-active surfaces of adjoining separator plates in a fuel cell stack cooperate to provide passageways for directing both reactants from respective stack fuel and oxidant supply manifolds to the appropriate electrodes. The fuel and oxidant reactant streams passageways are fluidly isolated from each other, although they both traverse adjoining non-active surfaces of the same pair of plates. The present manifolding configuration simplifies the sealing mechanisms associated with the stack manifolds because reactant streams are not directed between the separator plates and resilient MEA seals. Coolant passages may also be conveniently provided between adjoining non-active surfaces of the pairs of separator plates.

Electrochemical fuel cell stack with improved reactant manifolding and sealing

Provided are low-cost, mechanically strong, highly electronically conductive porous substrates and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical device substrates (548) of novel composition and techniques for forming thin electrode/membrane/electrolyte coatings (546/544) on the novel or more conventional substrates. In particular, in one embodiment the invention provides techniques for co-firing of device substrate (548) (often an electrode) with an electrolyte or membrane layer (544) to form densified electrolyte/membrane films 5 to 20 microns thick. In another embodiment, densified electrolyte/membrane films 5 to 20 microns thick may be formed on a pre-sintered substrate by a constrained sintering process. In some cases, the substrate (548) may be a porous metal, alloy, or non-nickel cermet incorporating one or more of the transition metals Cr, Fe, Cu and Ag, or alloys thereof.

Structures and fabrication techniques for solid state electrochemical devices

A fuel cell stack is based on solid electrolytes, such as the oxygen-ion conducting solid oxide fuel cells and the proton conducting ceramic or polymer membrane fuel cells. The fuel cell has a radial, coflow planar stack with an integral, internal manifold and tubular porous elements for controlling the rate and uniformity of the radial fuel and oxidant fluid flows. Such construction minimizes the extent of sealing that may be required and provides for easy manifolding of stack arrays. In addition, the fuel cell construction has the potential for high mass and volume specific power densities and low fabrication costs.

Radial planar fuel cell stack construction for solid electrolytes

A method of processing sulfur-containing heavy hydrocarbon fuels in the substantial absence of steam through catalytic partial oxidation is described. The process comprises the steps of vaporizing a heavy hydrocarbon fuel and bringing the vaporized fuel and oxidizer mixture in contact with a noble metal catalyst supported on an open channel structure. The hydrocarbon fuel is considered to be a liquid hydrocarbon having at least six carbon atoms and a sulfur content of at least 50 ppm. The feed, containing only the vaporized fuel and oxygen in the oxidizer mixture, is subsequently routed through a reactor containing a noble metal catalyst (typically Rh/Alumina) at contact times of not more than about 500 milliseconds and a LHSV of not less than about 0.5 h −1 . The feed is partially oxidized by a catalytic reaction occurring at a temperature of no less than about 1050° C., with the catalytic partial oxidation process producing essentially complete conversion of hydrocarbons present in the feed to hydrogen and carbon monoxide. The sulfur compounds in the feed are predominantly converted into hydrogen sulfide. The product gas consisting mainly of carbon monoxide and hydrogen can then be recovered or, alternatively, directed to a solid oxide fuel cell system.

Catalytic partial oxidation of hydrocarbon fuels to hydrogen and carbon monoxide

A process is comprised of continuously producing a fine ceramic powder by drying at supercritical conditions. The feed is a sol of ceramic oxides or hydrous oxides which is continuously pressurized and heated to in excess of the critical temperature and pressure of the sol solvent. The solvent transforms to a gas and separates from the fine particulate ceramic oxide powder, which remains in a highly divided state.

Continuous process for production of fine particulate ceramics.

A lanthanum chromite ceramic powder mixture that consists essentially of 1 mol of LaCr1-xMxO3, where M is a divalent metal selected from the group consisting of magnesium, calcium and mixtures thereof and x ranges from 0.03 to 0.3; y mols of B2O3, where y ranges from 0.005 to 0.04; and z mols of La2O3, where the ratio z/y ranges from 1.1 to 3. The mixture is formed into powder compacts and sintered to near full density at temperatures as low as 1400 °C.

Beneficiated lanthanum chromite for low temperature firing.

A composite sealant for in-situ sealing a fuel cell stack is provided. A paste of the sealant mixture is initially formed by mixing a glass precursor powder and a reacting filler material. The sealant mixture paste is applied to selected sealing locations of the fuel cell stack. The sealant mixture paste is then transformed into a composite sealant material to seal the selected sealing locations by heat treatment in air to about 900° C. The composite sealant material comprises a glass matrix phase and a reinforcing phase including a plurality of interlocked elongated single crystal grains. The reacting fillers modify the CTE and significantly improve the gap filling capacity of the composite sealant material and provide superior pressure containment capability at elevated temperatures.

Jean Yamanis

Papers

Radial planar fuel cell stack construction for solid electrolytes

Catalytic partial oxidation of hydrocarbon fuels to hydrogen and carbon monoxide

Continuous process for production of fine particulate ceramics.

Beneficiated lanthanum chromite for low temperature firing.

Composite sealant materials based on reacting fillers for solid oxide fuel cells