Catalyst for purifying the exhaust gases of diesel engines, and process for the preparation thereof
Assigneedmc2 Degussa Metals Catalysts Cerdec AG
InventorsRainer Domesle, Harald Klein, Thomas Kreuzer, Egbert Lox
Life of this patent
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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.
Claims25
A catalyst for purifying the exhaust gases of a diesel engine, comprising a support material containing at least one zeolite and, additionally, at least one of the support oxides selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide and aluminum silicate and mixed oxides thereof and at least one of the noble metals selected from the group consisting of platinum, palladium, rhodium, iridium, gold and silver, wherein atoms of the noble metals present in said catalyst 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 zeolite and support oxides in the form of crystallites having a mean particle size of from 1 to 6 nm.
The catalyst according to cliam 1 wherein said catalyst is in the form of a coating on inside walls of flow channels of a monolithic honeycomb carrier body in a concentration of from 50 to 400 grams per liter of volume of the honeycomb carrier body.
A monolithic honeycomb carrier for purifying the exhaust gases of a diesel engine, comprising an inert ceramic or metal carrier in the shape of a honeycomb having flow channels defined by the walls of the honeycomb, through which the exhaust gas passes, said walls having deposited on at least some surfaces thereof a support material containing at least one zeolite and, additionally, at least one of the support oxides selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide and aluminum silicate and mixed oxides thereof and at least one of the noble metals selected from the group consisting of platinum, palladium, rhodium, iridium, gold and silver, wherein atoms of the noble metals present in said catalyst 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 zeolite and support oxides in the form of crystallites having a mean particle size of from 1 to 6 nm.
An exhaust purification system for purifying the exhaust gases of diesel engines, comprising an inert honeycomb carrier having deposited on internal surfaces thereof a catalyst containing at least one zeolite and, additionally, at least one of the support oxides selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide and aluminum silicate and mixed oxides thereof and at least one of the noble metals selected from the group consisting of platinum, palladium, rhodium, iridium, gold and silver.
A catalyst for purifying the exhaust gases of a diesel engine, comprising a support material containing at least one zeolite and, additionally, at least one of the support oxides selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide and aluminum silicate and mixed oxides thereof and at least one of the noble metals selected from the group consisting of platinum, palladium, rhodium, iridium, gold and silver, wherein atoms of the noble metals present in said catalyst 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 zeolite and support oxides in the form of crystallites having a mean particle size of from 1 to 6 nm made by a proces wherein said support material is impregnated with an amine-complexed precursor of the noble metal to obtain an impregnated support material and then calcining said impregnated support material by spray calcination.
A process for producing a catalyst for purifying the exhaust gases of a diesel engine comprising a support material containing at least one zeolite and, additionally, at least one of the support oxides selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide and aluminum silicate and mixed oxides thereof and at least one of the noble metals selected from the group consisting of platinum, palladium, rhodium, iridium, gold and silver, wherein atoms of the noble metals present in said catalyst 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 zeolite and support oxides in the form of crystallites having a mean particle size of from 1 to 6 nm wherein said support material is impregnated with an amine-complexed precursor of the noble metal to obtain an impregnated support material and then calcining said impregnated support material by spray calcination.
Dependencies are inferred from the claim text.