摘要:
The present invention relates to a process for improving the catalytic activity of a copper-promoted zeolitic catalyst with chabazite structure, to a copper-promoted zeolitic catalyst with chabazite structure and to a process for reducing nitrogen oxides in an offgas stream.
摘要:
The invention relates to a method for treating diesel engine exhaust gases containing nitrogen oxides (NOx) and hydrocarbons (HC) by selective catalytic reduction of the nitrogen oxides with ammonia or a compound, which can be decomposed to ammonia, as reducing agent (2), at an SCR catalyst (3) based on a molecular sieve. The catalyst used is such that the hydrocarbons, contained in the exhaust gas, are kept remote by the molecular sieve-like action of the zeolite contained in the catalyst from the catalytically active centers in the catalyst, at which the reactions take place. By these means, the degradation and aging effects, caused by the HC, are avoided and appreciably better nitrogen oxide conversions are attained in the HC-containing exhaust gas.
摘要:
Die vorliegende Erfindung betrifft ein SCR-aktives Material, das einen kleinporigen Zeolithen, Aluminiumoxid und Kupfer umfasst, dadurch gekennzeichnet, dass es bezogen auf das gesamte Material 5 bis 25 Gew.-% Aluminiumoxid enthält und das Kupfer auf dem Aluminiumoxid in einer ersten Konzentration und auf dem kleinporigen Zeolithen in einer zweiten Konzentration vorliegt.
摘要:
The invention relates to a catalyst system for reducing nitrogen oxides, which comprises a nitrogen oxide storage catalyst and an SCR catalyst, wherein the nitrogen oxide storage catalyst comprises at least two catalytically active washcoat layers on a supporting body, wherein a lower washcoat layer A contains cerium oxide, an alkaline earth compound and/or alkali compound, and platinum and palladium and an upper washcoat layer B, which is arranged over the washcoat layer A, contains cerium oxide, platinum and palladium and no alkli compound and no alkaline earth compound. The invention also relates to a method for converting NOx in exhaust gases of motor vehicles that are operated by means of engines that are operated in a lean manner.
摘要:
The invention relates to the possibility of improving selective catalytic reduction (SCR), which is the selective reaction of nitrogen oxides with ammonia in the exhaust gas of combustion processes on an exhaust-gas catalytic converter suitable therefor - the SCR catalytic converter. For this purpose, materials used in the catalytic converter for storing ammonia are distributed on the catalyst carrier in such a way that, viewed in the flow direction, a region having low ammonia storage capacity is followed by a region of higher ammonia storage capacity.
摘要:
The invention relates to a catalytically active material for reacting nitrogen oxides with ammonia in the presence of hydrocarbons. The material consists of an inner core (1) made of a zeolite exchanged with one or more transition metals or a zeolite-like compound exchanged with one or more transition metals. The core of the catalytically active material is encased by a shell (2), which is made of one or more oxides selected from silicon dioxide, germanium dioxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, zirconium dioxide, and mixed oxides thereof.