Abstract: A method for the desulfurization of an NOx storage catalyst arranged in an exhaust system of an internal combustion engine, whereby, for the desulfurization, the internal combustion engine is alternatingly operated in a lean mode at ?>1 and a rich mode at ?<1. During the desulfurization process, the present invention provides for the progress of the desulfurization being monitored, using a change in a parameter relating to intervals (In), whereby the interval (In) lasts from the beginning of an nth rich operating phase (Tf,n), until the measured value drops below a predetermined lambda threshold value (Sf) downstream from the NOx storage catalyst (16). Furthermore, the progress of the desulfurization is monitored, using a change in a lambda probe voltage (Un) downstream from the NOx storage catalyst (16), which is determined at the end of a predetermined interval at the beginning of an nth rich operating phase (Tf,n).

Abstract: An oxygen storage material comprising cerium oxide and at least one second oxide of a metal M1 is disclosed as well as a process for manufacturing the material and the use of this material in an exhaust gas cleaning catalyst. In a preferred embodiment the oxygen storage material comprises particles from a Ce/M1 mixed oxide solid solution coated with an oxide of another metal M2. Metal M1 e.g. can be calcium or zirconium while metal M2 most preferably is aluminum.

Abstract: The present invention provides a continuous process for producing catalyst-coated polymeric electrolyte membranes and membrane electrode assemblies for fuel cells. The process of the invention uses an ionomer membrane having a polymeric backing film on the back side. After the first coating step, the membrane is dried, during which the residual solvent may be almost completely removed. After this, the polymeric backing film is removed and the back side of the membrane is coated in a second step. The front and back sides of the membrane can be coated by various methods, such as screen printing or stencil printing. Two gas distribution layers are applied to the two sides of the catalyst-coated membrane to produce a 5-layer membrane electrode assembly. The membrane electrode assemblies are used in polymeric electrolyte membrane fuel cells and in direct methanol fuel cells.

Abstract: The invention relates to a method for desulfating a nitrogen oxide storage catalyst that contains stored nitrogen oxides and sulfur oxides and that forms part of an exhaust gas purification system of a lean-burn engine. The method provides that, to initiate desulfation, the temperature of the catalyst is increased to the point where thermal desorption of the nitrogen oxides stored in the catalyst sets in, and the onset of thermal desorption of the nitrogen oxides is used as the signal to enrich the air/fuel mixture to perform the desulfation.

Abstract: The invention provides a process for coating a cylindrical carrier structure with a predetermined amount (target take-up) of a coating suspension, wherein the carrier structure has a cylinder axis, two end faces, an encasing face and an axial length L and a large number of channels running from the first end face to the second end face. The process comprises: a) vertically aligning the cylinder axis of the carrier structure and filling the empty volume of the channels up to a predetermined height H1 starting from the lower end face, b) removing the excess coating suspension through the lower end face of the carrier structure down to the target take-up, c) turning the carrier structure 180°, so that the upper and lower end faces are exchanged one for the other, and d) repeating steps a) and b), wherein the height H2, up to which the channels are filled in this case is given by H2=L−x·H1 where x is between 0.8 and 1.0.

Abstract: The present invention relates to the field of electrochemical cells and fuel cells, and more specifically to polymer-electrolyte-membrane (PEM) fuel cells. It provides a process for the manufacture of catalyst-coated substrates for membrane fuel cells. The catalyst-coated substrates (e.g. catalyst-coated membranes (“CCMs”), catalyst-coated backings (“CCBs”) and catalyst-coated tapes) are manufactured in a new process comprising the coating of the substrate with a water-based catalyst ink in a compartment maintaining controlled humidity and temperature. After deposition of the ink, the substrate is subjected to a leveling process at controlled humidity and temperature conditions. Very smooth and uniform catalyst layers are obtained and the production process is improved. The catalyst-coated membranes (CCMs), catalyst-coated backings (CCBs) and catalyst-coated tapes manufactured according to this process are used in the production of three-layer and five-layer MEAs.

Abstract: A process for the preparation of mono-, bi- or poly-functional biaryls in the presence of a metal complex of the general formula IV as catalyst.

Abstract: The invention herein relates to a PEM fuel cell stack consisting of one or more superimposed fuel cells (1), each containing a membrane electrode assembly (2) and electrically conductive bipolar plates (3, 4), whereby the membrane electrode assemblies each comprise a polymer electrolyte membrane (5), which is in contact on each side with a reaction layer (6, 7); whereby the reaction layers cover a smaller area than the polymer electrolyte membrane, and between each reaction layer and the adjacent bipolar plates—essentially congruent with the reaction layers—respectively one compressible gas distribution layer (8, 9) of carbon fiber material is provided, and gaskets (11, 12) are interposed in the region outside the area covered by the gas distribution layers; whereby the gas diffusion electrodes formed by the reaction layers and the gas distribution layers exhibit a no-load thickness of D1 and the gaskets a thickness D2.

Abstract: The present invention is directed to a method and device for operating an engine of a motor vehicle. Firstly, driving condition parameters of the engine and/or the motor vehicle are collected over a predetermined period of time. After that the probabilities of parameters for the future operation of the engine in relation to the captured driving condition parameters are ascertained. Finally, operating parameters of the engine are adjusted in relation to the ascertained probability values for the parameters.

Abstract: The invention relates to a catalyst for lowering the amount of NOx in the lean exhaust gas from lean burn engines, comprising active aluminum oxide, magnesium oxide and at least one noble metal of the platinum group of the periodic table of the elements, as well as at least one nitrogen oxide storage material. The catalyst is characterized in that the magnesium oxide forms a homogeneous mixed oxide with aluminum oxide and is present in a concentration of about 1 to about 40 wt.-%, based on the total weight of the mixed oxide.

Abstract: The present invention relates to a method for the production of a membrane electrode assembly comprising a polymer electrolyte membrane with two opposing membrane surfaces and a cathode and an anode electrode each comprising a catalyst layer and a gas distribution layer. Each catalyst layer is interposed between a membrane surface and the corresponding gas distribution layer. The catalyst layer of the cathode and/or the catalyst layer of the anode comprise at least two sub-layers. According to the present invention at least one of the sub-layers of the cathode electrode and/or the anode electrode is applied directly to the surface of the membrane while the remaining sub-layers are applied to the corresponding gas distribution layers. Finally the assembly of the coated membrane and the coated gas distribution layers is produced.

Abstract: The invention relates to a process for catalytic autothermal steam reforming of alcohols having two or more carbon atoms by directing a preheated educt or reactant mixture of the alcohols, oxygen and water or steam over a catalyst. The process is conducted in an adiabatic manner wherein the catalyst comprises at least one platinum group metal on an oxidic support selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide or mixed oxides thereof and zeolites, and that the educt or reactant mixture contains additional hydrocarbons, which are reformed at the same time as the alcohols.

Abstract: The invention provides platinum or platinum alloy powders for use in fuel cells and for chemical reactions. The powders are characterized by a high surface area and, at the same time, low chlorine contents. The powders are prepared by forming a melt which contains, as starting substances, a low melting mixture of alkali metal nitrates, a chlorine-free platinum compound and optionally chlorine-free compounds of alloying elements, the melt is then heated to a reaction temperature at which the platinum compound and the compounds of alloying elements thermally decompose to give oxides, the melt is then cooled and dissolved in water and the oxides or mixed oxides formed are converted into platinum or platinum alloy powders by subsequent reduction. Binary or ternary eutectic mixtures from the LiNO3—KNO3—NaNO3 system are suitable as a low melting mixture of nitrates of the alkali metals. Hexahydroxoplatinic-(IV)-acid is preferably used as a chlorine-free platinum compound.

Abstract: The invention comprises a process for making a membrane electrode assembly comprising a polymer electrolyte membrane having two opposite faces, on each face of which is applied a catalyst layer and a gas distribution layer. The two gas distribution layers in the membrane electrode assembly are formed by hydrophobized carbon substrates which, using appropriate inks containing at least one catalyst, dissolved ionomer and solvent, are each coated with a catalyst layer and are then laid on opposite faces of the polymer electrolyte membrane with the catalyst layers still in the moist state. Afterwards, a firm bond between electrolyte membrane, catalyst layers and carbon substrates is produced by treating the membrane electrode assembly at elevated temperature under pressure.

Abstract: The invention provides a noble metal-containing supported catalyst which contains one of the noble metals from the group Au, Ag, Pt, Pd, Rh, Ru, Ir, Os or alloys of one or more of these noble metals in the form of noble metal particles on a powdered support material. The particles deposited on the support material have a degree of crystallinity, determined by X-ray diffraction, of more than 2 and an average particle size between 2 and 10 nm. The high crystallinity and the small particle size of the noble metal particles lead to high catalytic activity for the catalyst. It is particularly suitable for use in fuel cells and for the treatment of exhaust gases from internal combustion engines.

Abstract: The invention provides a process for coating a cylindrical carrier structure with a predetermined amount (target take-up) of a coating suspension, wherein the carrier structure has a cylinder axis, two end faces, an encasing face and an axial length L and a large number of channels running from the first end face to the second end face. The process comprises: a) vertically aligning the cylinder axis of the carrier structure and filling the empty volume of the channels up to a predetermined height H1 starting from the lower end face, b) removing the excess coating suspension through the lower end face of the carrier structure down to the target take-up, c) turning the carrier structure 180°, so that the upper and lower end faces are exchanged one for the other, and d) repeating steps a) and b), wherein the height H2, up to which the channels are filled in this case is given by H2=L−x·H1 where x is between 0.8 and 1.0.

Abstract: The invention provides a process for preparing a platinum-ruthenium catalyst and the catalyst prepared therewith. The catalyst can be supported on a support material in powder form or may also be unsupported. To prepare the supported catalyst, the support material is suspended in water and the suspension is heated to at most the boiling point. While keeping the temperature of the suspension the same, solutions of hexachloroplatinic acid and ruthenium chloride are then added to the suspension, then the pH of the suspension is increased to a value between 6.5 and 10 by adding an alkaline solution and the noble metals are thus precipitated onto the support material. Afterwards, one or more organic carboxylic acids and/or their salts are added to the suspension and the catalyst is chemically reduced, washed, dried and optionally subsequently calcined under an inert or reducing atmosphere at a temperature between 300 und 1000° C.

Abstract: The invention provides a catalyst for removing carbon monoxide from a reformate gas. The catalyst is characterized in that it contains gold and ruthenium in a ratio by weight between 5:1 and 1:5 on a support material of aluminum oxide, titanium oxide, zirconium oxide, cerium oxide, lanthanum oxide and mixtures or mixed oxides thereof.

Abstract: The invention provides a multistep process for preparing a low-sulfur reformate gas for use in a fuel cell system by catalytic steam reforming of a reactant gas mixture comprising introducing a sulfur-containing hydrocarbons and steam in a first step to make a reformate, passing the reformate leaving the first step over a sulfur absorber either directly or only after passage through the second step, and reducing the carbon monoxide content of the reformate obtained in a second step, wherein the reactant gas mixture which comprises a steam/carbon ratio and desorbing the sulfur components optionally absorbed on the catalysts in both process steps by periodically raising the temperature and also passing the catalysts over the absorber, wherein the temperature of the absorber during operation of the process is always kept within a temperature interval which is an optimum for the absorber.

Abstract: The invention provides a process for removing soot particles from exhaust gas from produced by a diesel engine. The process uses a particle filter that collects soot particles with the aid of nitrogen dioxide which is generated by catalytic oxidation of nitrogen monoxide contained in the exhaust gas. The process is characterized in that the particle filter is a deep-bed particle filter, having a filtration efficiency for the soot particles. The particle filter is coated with a catalytic coating for oxidizing nitrogen monoxide to nitrogen dioxide and the exhaust gas leaving the particle filter subsequently filtered through a particle filter serving as a soot barrier. The filter can have a filtration efficiency of over 95%.