Abstract: A honeycomb body made from a ceramic material with improved radial pressure resistance that is of cylindrical shape and features a first and a second end face and a cylindrical shell and that is traversed from one end face to the other by axially parallel channels formed by channel walls and distributed across the cross section of the honeycomb body in a regular grid pattern, in which design an outer marginal zone of the honeycomb body, the thickness of which amounts to several channel diameters, encloses a central area. The increase in radial pressure resistance of the honeycomb body is achieved by reinforcing the ceramic material of the cylindrical shell and of the channel walls in the outer marginal zone of the honeycomb body by depositing on or in it one or several inorganic substances for the purpose of increasing its mechanical stability.

Abstract: A catalyst for purifying the exhaust gases of diesel engines, which catalyst contains at least one zeolite and, additionally, at least one of the support oxides aluminum oxide, silicon dioxide, titanium dioxide and aluminum silicate and at least one of the noble metals platinum, palladium, rhodium and iridium. In this catalyst the atoms of the noble metals have a mean oxidation number of less than +2.5, on average more than 3 metal ligands and less than 3 oxygen ligands and are present on the zeolites and support oxides in the form of crystallites having a mean particle size of from 1 to 6 nm.

Abstract: A process for coating, with a suspension, a ceramic honeycomb body which has a cylindrical shape with two flat end-faces and one jacket, and through which channels parallel to the axis, formed by channel walls, run from one flat end-face to the other, the honeycomb body being coated by suitable processes. The honeycomb body is partially wetted and then coated.

Abstract: A suspension, dispersion or emulsion is introduced into a burner. A two-stage after-treatment is then carried out. The resulting powder can be employed as a catalyst.

Abstract: A catalyst system for the treatment of exhaust gases from a diesel engine includes a first and a second catalyst reducing catalyst arranged in series in an exhaust gas treatment system. The first catalyst is located near the engine in a region of the exhaust gas treatment system in which the exhaust gas temperature reaches temperatures of more than 200° C. under full engine load. The second catalyst is located further from the engine in a region of the exhaust gas treatment system in which the exhaust gas temperature reaches a maximum of 500° C. under full engine load. The maximum nitrogen oxides reduction in the first catalyst takes place at a lower temperature than the maximum nitrogen oxides reduction in the second catalyst.

Abstract: A process is disclosed for operating an exhaust gas treatment unit for an internal combustion engine which is operated with lean normalized air/fuel ratios over most of the operating period. The exhaust gas treatment unit contains a nitrogen oxides storage catalyst with an activity window .DELTA.T.sub.NOX for the storage of nitrogen oxides at normalized air/fuel ratios of greater than 1 and release of the nitrogen oxides at normalized air/fuel ratios of less than or equal to 1 and a sulfur trap, located upstream of the nitrogen oxides storage catalyst, with a sulfur desorption temperature T.sub.S,DeSOx above which the sulfates stored on the sulfur trap are decomposed at normalized air/fuel ratios of less than or equal to 1. The nitrogen oxides contained in the exhaust gas are stored on the nitrogen oxides storage catalyst and the sulfur oxides are stored on the sulfur trap at normalized air/fuel ratios greater than 1 and exhaust gas temperatures T.sub.K within the activity window T.sub.

Abstract: A coating dispersion is shown for the production of catalysis-promoting coatings on an inert, structure-reinforcing element. The solids of the dispersion are present in various particle fractions and lead to a relatively rough coating surface with improved exchange between the exhaust gas and the catalyst surface. This results in improved heat-up behavior of the catalyst.

Abstract: A catalyst for purifying the exhaust gases from diesel engines. The catalyst contains a zeolite mixture of several zeolites with different moduli and platinum group metals as well as further metal oxides from the group aluminum silicate, aluminum oxide and titanium oxide, wherein the aluminum silicate has a ratio by weight of silicon dioxide to aluminum oxide of 0.005 to 1 and the platinum group metals are deposited on only the further metal oxides.

Abstract: A method for the sealing of flow channels in an annular zone of a cylindrical honeycomb body. The sealing of the flow channels takes place by introduction of a ceramic compound into the flow channels by means of a nozzle, wherein nozzle and honeycomb body are moved relative to one another with simultaneous guiding of the nozzle past the lateral surface and/or past the end face contour of the honeycomb body.

Abstract: A process for simultaneously reducing the amounts of hydrocarbons, carbon monoxide and nitrogen oxides contained in the exhaust gas from an internal combustion engine in the exhaust gas from gasoline or diesel engines with high amounts of oxygen in the exhaust gas is disclosed. A high reductive effect towards nitrogen oxides is enabled by using a homogeneous aluminum silicate as a high surface area support material for the catalytically active components.

Abstract: A method is disclosed for manufacturing a monolithic metal support with a coated, gas-permeable shaped body. The shaped body is formed of one or more smooth and/or corrugated metal foil strips previously coated with a dispersion coating. During or after formation of the shaped body, the metal foil strips are joined by soldering or welding to at least one adjacent metal foil strip or to at least one adjacent layer of the same metal foil strip.

Abstract: A process for applying a coating to honeycomb structures in an exhaust gas converter which contains two such honeycomb structures in a common housing or enveloping tube which are arranged one after the other and which are separated from each other by a gap. The coating dispersion is first supplied from one end of the exhaust gas converter up to the gap between the two honeycomb structures. Then excess coating dispersion is driven out using a blast of air from the direction of the uncoated honeycomb structure. To coat the second honeycomb structure, the exhaust gas converter is inverted and the coating dispersion is then applied in the same way but from the uncoated end. Following the dispersion coating procedure, production of the catalyst is completed by drying and optionally calcining.

Abstract: An open-cell, monolithic catalyst for the purification of diesel-engine exhaust gas with a coating of finely divided inorganic oxides containing vanadium and platinum group metal as active components. The active components of the oxidic coating are added as water-soluble precursors which are then converted by means of tempering, preferably in an atmosphere of hydrogen, into the active component.

Abstract: A coating dispersion is shown for the production of catalysis-promoting coatings on an inert, structure-reinforcing element. The solids of the dispersion are present in various particle fractions and lead to a relatively rough coating surface with improved exchange between the exhaust gas and the catalyst surface. This results in improved heat-up behavior of the catalyst.

Abstract: Monolithic catalysts with a metal carrier that includes a catalytically coated matrix having at least one stack of several sheet-metal strips of corrugated or alternately corrugated and flat metal strips folded or intertwined with one another are described. The free ends of the metal strips are connected by a joining process with a surrounding jacket tube of any required cross-section. The monolithic catalyst is produced very economically and with a catalytic coating that has a uniform thickness. The at least one stack of sheet-metal strips required for the monolithic catalyst with a metal carrier is assembled from coated metal ribbons cut to length so as to form metal stacks. The stacks may be folded and/or intertwined with themselves or with one another so as to form the matrix. The matrix with intertwined and coated strips is inserted into the jacket tube and the free ends of the metal strips are secured by joining to the jacket tube.

Abstract: An oxidative diesel control catalyst is disclosed which has a high conversion rate for hydrocarbons and carbon monoxide and an inhibited oxidation effect on nitrogen oxides and sulfur dioxides and which contains a monolithic catalyst element with throughflow passages of ceramic or metal coated with an activity-promoting dispersion coating of the fine-particle metal oxides aluminum oxide, titanium oxide, silicon oxide, zeolite or mixtures thereof as support of the catalytically active components, the active components being present in the form of platinum, palladium, rhodium and/or iridium doped with vanadium or in contact with an oxidic vanadium compound. The reduced oxidation effect on sulfur dioxide is obtained by virtue of the fact that the fine-particle metal oxides are surface-modified aluminum oxide, titanium oxide, silicon oxide, zeolite or mixtures thereof.

Abstract: A catalyst for purifying the exhaust gases of internal combustion engines with improved light-off behavior and improved durability with reduced specific noble-metal content is disclosed which uses active aluminum oxide provided with customary promoters as carrier and platinum and/or palladium and rhodium in customary amounts as noble metals. In addition, it contains one or more base metals in amounts up to 5 times the mass of the total noble metal which are brought into the immediate vicinity of the rhodium by means of a special manufacturing technique.

Abstract: An open-cell, monolithic catalyst for the purification of diesel-engine exhaust gas with a coating of finely divided inorganic oxides containing vanadium and platinum group metal as active components. The active components of the oxidic coating are added as water-soluble precursors which are then converted by means of tempering, preferably in an atmosphere of hydrogen, into the active component.

Abstract: The thermal shock resistance of monolithic catalysts is improved by pre-coating a ceramic monolithic carrier, before the application of catalytic components, with an organic filling material which can be melted and burned out and which comprises a dispersion of very fine solid particles, by heating the carrier above the melting point of the filling material, then applying the catalytic components and then burning out the filling material.

Abstract: A catalyst is described made of active aluminum oxide with additives of CeO.sub.2, ZrO.sub.2, and Fe.sub.2 O.sub.3 and/or NiO as carrier and an active phase, applied thereon and consisting of platinum, palladium and/or rhodium, and a base metal, which is obtainable by impregnation of the additive-containing carrier with solutions of salts of the metals for the active phase, wherein the base metal of the active phase is cerium, by drying, and by heating to 250.degree. to 650.degree. C. The catalyst can be used for the oxidation and/or reduction of exhaust gases from internal combustion engines.