Catalyst for purification of exhaust gases of diesel engines and method of use
AssigneeDegussa AG
InventorsRainer Domesle, Bernd Engler, Edgar Koberstein, Herbert Voelker
Life of this patent
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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.
Claims22
A catalyst capable of operating in a continuous manner without soot particulate separation and without cyclical regeneration for the oxidative purification of the exhaust gases of diesel engines and having a high conversion performance for hydrocarbons and carbon monoxide at low temperatures and inhibited oxidation action in respect of NO and SO.sub.2 comprising:
- an open-cell monolithic or honeycombed inert carrier of ceramic or metal,
- said inert carrier having a plurality of channels essentially parallel to the direction of flow of said exhaust gases, such that exhaust gas flows freely through the channels of the carrier, said channels having interior surfaces coated with an activity-enhancing support material selected from the group consisting of finely divided aluminum oxide, titanium oxide, silicon oxide, zeolite and mixtures thereof,
- said activity-enhancing support material having deposited thereon a catalytically active component of at least one platinum group metal selected from the group consisting of platinum, palladium, rhodium and iridium, the platinum group metal or metals being doped with vanadium or being in contact with an oxidic vanadium compound,
- said catalyst being prepared by impregnating said activity-enhancing support material with a solution of compounds of said platinum group metals and a solution of a vanadium compound, said impregnating taking place simultaneously or successively in any desired sequence,
- thereafter drying, optionally calcining at a temperature of at least 200.degree. C.
A method of making a catalyst capable of operating in a continuous manner without soot particulate separation and without cyclical regeneration and suitable for the oxidative purification of the exhaust gases of diesel engines, comprising the steps of:
- impregnating an activity-enhancing support material with a vanadium compound and at least one platinum group metal, said support material being selected from the group consisting of finely divided aluminum oxide, titanium oxide, silica, zeolite and mixtures thereof, and said impregnation being made with a solution of at least one compound including the platinum group or metals and a solution of a vanadium compound, said impregnating taking place simultaneously or successively in any desired sequence;
- drying the impregnated support material;
- and
- optionally calcining at a temperature of at least 200.degree. C., and wherein said impregnating with at least one of said vanadium compound and said platinum group metal takes place after depositing said activity-enhancing support material onto an open-celled monolithic or honeycombed inert carrier, said open celled carrier allowing exhaust gas to flow freely through the cells thereof.
A method of making a catalyst capable of operating in a continuous manner without soot particulate separation and without cyclical regeneration and suitable for the oxidative purification of the exhaust gases of diesel engines, comprising the steps of:
- impregnating an activity-enhancing support material with a vanadium compound and at least one platinum group metal, said support material being selected from the group consisting of finely divided aluminum oxide, titanium oxide, silica, zeolite and mixtures thereof, and said impregnation being made with a solution of at least one compound including the platinum group metal or metals and a solution of a vanadium compound, said impregnating taking place simultaneously or successively in any desired sequence;
- drying the impregnated support material;
- and
- optionally calcining at a temperature of at least 200.degree. C., and wherein said impregnating with at least one of said vanadium compound and said platinum group metal takes place before depositing said activity-enhancing support material onto an open-celled monolithic or honeycombed inert carrier, said open-celled carrier allowing exhaust gas to flow freely through the cells thereof.
Dependencies are inferred from the claim text.