Abstract: An exhaust gas purification device includes a porous body of catalytic material of the general formula AaBbO4 disposed in an exhaust gas stream of an engine. The porous body of catalytic material has a characteristic response temperature above which it is catalytically active to reduce pollutants in the presence of a reducing agent. The porous body stores at least 20% by volume hydrocarbons at temperatures below the response temperature. A represent at least one element selected from Mg, Ca, Mn, Fe, Ni, Co, Cu, Zn, Sn, Ti and A+B is less than 3, A is greater than 0 and B greater than 0.

Abstract: The present invention is directed to a purification device that includes a porous body and a catalyst. To reduce the emission of pollutants, a pollutant-containing stream of gas flows through the porous body.

Abstract: NO.sub.x, where x is 1 and 2, in exhaust gases is reduced over heterogeneous catalysts with hydrocarbons, carbon monoxide, hydrogen or mixtures thereof in the presence of oxygen from 100 to 650.degree. C. and an absolute pressure of from 0.5 to 50 bar by a process in which the heterogeneous catalysts used are bimodal or polymodal compounds of the general formula IA.sub.1-x M.sub.2 O.sub.4 (I),which, if required, are doped with rare earth metals, noble metal, titanium, vanadium, molybdenum, tungsten or mixtures thereof, and whereA is magnesium, calcium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, tin or mixtures thereof,M is aluminum, gallium, indium, tin, chromium, manganese, iron, cobalt, nickel, copper, zinc or mixtures thereof andx is from 0 to 0.

Abstract: A process for the catalytic reduction of NO.sub.x, the reduction taking place in the presence of a catalyst which comprises(a) from 20 to 97 wt % of A.sub.2 O.sub.3,(b) from 1 to 40 wt % of CuO,(c) from 1 to 50 wt % of ZnO,(d) from 1 to 40 wt % of Ag,(e) from 0 to 2 wt % of Pt,(f) from 0 to 20 wt % of oxides of rare earth metals, elements of the 3rd subgroup of the Periodic Table of the Elements or mixtures thereof,based on the total weight of the components (a) to (e), which adds up to 100 wt %, wherein, in each case, up to half the weight of the component (a) may be replaced by Fe.sub.2 O.sub.3, Cr.sub.2 O.sub.3, Ga.sub.2 O.sub.3 or mixtures thereof, of the component (b) by CoO, of the component (c) by MgO, of the component (d) by Au and of the component (e) by Pd, Ru, Os, Ir, Rh, Re or mixtures thereof, is used for reducing NO.sub.x, especially in combustion off-gases, the components (a), (b) and (c) forming a spinel which is doped with the components (d), (e) and (f).

Abstract: A method of catalytically reducing nitrogen oxides (NO.sub.x) and oxidizing hydrocarbons or carbon monoxide in exhaust gases of internal combustion engines or combustion power plants using a catalyst comprising a magnesium oxide/copper oxide/aluminum oxide spinel or a copper-impregnated copper oxide/aluminum oxide spinel.

Abstract: The present invention relates to a method for operating a catalyst for gases, especially for exhaust gases of stoichiometrically operated gasoline engines, wherein a catalyst is exposed to a gas stream and pollutants are catalytically converted. To improve the elimination of pollutants in the starting phase, hydrocarbons present in the gas are temporarily stored by the catalyst at temperatures below a response temperature of the catalyst, particularly below 200.degree. C., and preferably below 150.degree. C. The hydrocarbons are then released at temperatures above the response temperature and the pollutants, such as nitrogen oxides, are catalytically converted with reducing agents, such as hydrocarbons, carbon monoxide and mixtures thereof. The catalyst is a spinel, such as (MgCu)Al.sub.2 O.sub.4, which may also include a catalytically active species, such as WO.sub.3, V.sub.2 O.sub.5 and TiO.sub.2.

Abstract: The present invention relates to a method for operating a purification device, to a purification device and to the use of same. To reduce the emission of pollutants, a filter body through which a fluid can flow and comprising a catalyst, is exposed to a stream of gas which is to be purified. Before the gas enters the catalyst, a reducing agent is added in the flow direction of the gas, and after a certain treatment point, during which the gas, which is to be purified, is flowing in the catalyst, reducing agent is added once more to the flowing gas by a feeding mechanism and contact with the catalyst is maintained.

Abstract: A catalyst and a method for producing the catalyst, for catalytic reduction of NO.sub.x and oxidation of hydrocarbons, the catalyst comprises a zinc, copper and aluminum spinel to which, at least one element selected from palladium, platinum, rhodium, ruthenium, osmium, iridium, rhenium and/or rare earth metals, such as lanthanum and cerium, vanadium, titanium, niobium, molybdenum, tungsten and/or salts thereof and/or oxides thereof has been added.

Abstract: A catalyst and a process for producing the catalyst are provided. For the catalytic reduction of NO.sub.x and for the oxidation of hydrocarbons, the catalyst contains a spinel containing the metals copper, zinc and aluminum.

Abstract: A catalyst and a method for producing the catalyst, for catalytic reduction of NO.sub.x and oxidation of hydrocarbons, the catalyst comprises a zinc, copper and aluminum spinel to which, at least one element selected from palladium, platinum, rhodium, ruthenium, osmium, iridium, rhenium and/or rare earth metals, such as lanthanum and cerium, vanadium, titanium, niobium, molybdenum, tungsten and/or salts thereof and/or oxides thereof has been added.

Abstract: A material and a process for adsorbing and desorbing nitrogen oxides in exhaust gas systems of engines running on a lean mixture, which does not require a prior oxidation step, wherein a mixed oxide which has an oxygen-rich orthorhombic structure is used which changes to an oxygen-poor tetragonal structure as a function of temperature.

Abstract: A catalyst and a process for producing the catalyst are provided. For the catalytic reduction of NO.sub.x and for the oxidation of hydrocarbons, the catalyst contains a spinel containing the metals copper, zinc and aluminum.

Abstract: A description is given of superconducting substances having a content of Bi, Sr, Ca and Cu, and of processes for their preparation from the metal oxides within a range which is specified by the overall composition Bi.sub.a (Sr,Ca).sub.b -Cu.sub.6 O.sub.x, where a=3-24 and b=3.23-24, with an Sr/Ca atomic ratio of 1:9-9:1 and a Bi:(Ca+Sr) atomic ratio of 0.3-1.5. The transition temperature is at least 60 K. The principal phase crystallizes in the orthorhombic system. The pure compounds Bi.sub.4 (Sr,Ca).sub.4 Cu.sub.2 O.apprxeq..sub.12 and Bi.sub.4 (Sr,Ca).sub.6 Cu.sub.4 O.apprxeq..sub.20.

Abstract: The invention provides a catalyst, and a process for preparing the same, for the catalytic reduction of NO.sub.x and for the oxidation of hydrocarbons. The catalyst contains a copper oxide-zinc oxide-aluminum oxide spinel and a zeolitic support material.

Abstract: Black crystal compositions having the empirical composition Bi.sub.a Sr.sub.b Cu.sub.c O.sub.d are described where a+b+c=1, A=0.36-0.557, b=0.098-0.496, c=0.1-0.4 and d=approximately 1+a/2. These compositions have a superconducting transition temperature T.sub.c for superconductivity of greater than 20 K and contain a principal phase which crystallizes in the orthorhombic system. They can be prepared from the mixture of the oxides in the atomic ratio stated by heating to 700.degree.-1000.degree. C.