Solid for storing/releasing nitrogen oxides as well as nitrogen oxide storage catalyst
AssigneeDornier GmbH
InventorsRenato Andorf, Carsten Plog, Guido Schaeffner
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Abstract
An Ag-containing solid, such as Ag2O, Ag2CO3, and AgOH, is used for storing/releasing nitrogen oxides in an exhaust gas from an engine during controlled cycling of the λ-value of the exhaust gas. The nitrogen oxides are stored at λ-values of the gas greater than 1 in the Ag-containing solid and the nitrogen oxides are released at λ-values of the gas less than or equal to 1 from the Ag-containing solid. The Ag-containing solid may include a precious metal or a microporous carrier, for example, ZrO2, SiO2, TiO2, Si—Al mixed oxide, and zeolites.
Claims7
A method of treating a gas comprising nitrogen oxides, comprising:
- controlling cycling of the λ-value of the gas to alternate in a predetermined manner between a λ-value that is greater than 1 and a λ-value that is less than or equal to 1;
- storing nitrogen oxides in a solid when the λ-value of the gas is greater than 1;
- and
- releasing said stored nitrogen oxides when the λ-value of the gas is less than or equal to 1,
- wherein the λ-value is a ratio of oxidizing constituents to reducing constituents contained in said gas,
- wherein the solid consists of a material selected from the group consisting of Ag2O, Ag2CO3 and AgOH;
- at least one other precious metal;
- and a microporous carrier substance.
Dependencies are inferred from the claim text.