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US 4,052,337 AGranted
Catalyst for reduction of nitrogen oxides and process for preparing same
AssigneeToa Nenryo Kogyo Kabushiki Kaisha
InventorsEiichiroh Nishikawa, Takuji Itoh, Tsugio Maeshima, Setsuo Kamiyama
Life of this patent
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Abstract
Nitrogen oxides are removed from gaseous mixtures comprising the same by contacting with a catalyst comprising a base metal component carried on a natural or synthetic zeolite in the presence of ammonia. The alkali metal content of the zeolite is carefully controlled through ion exchange with an alkaline earth metal compound.
Claims2
A process for preparing a catalyst for reduction of nitrogen oxides, characterized in that:
- a. a synthetic crystalline aluminosilicate is contacted with a solution containing one or more alkaline earth metal ions to ion-exchange the alkali metals in the synthetic crystalline aluminosilicate with the alkaline earth metal(s) so that the alkali metal content remaining will be within the range from 0.2 to 0.6 equivalents per gram atom of alumina;
- (b) the ion-exchanged synthetic crystalline aluminosilicate is calcined, if necessary;
- and (c) the synthetic crystalline aluminosilicate is contacted with a solution containing one or more active metal ions having an effect of reducing nitrogen oxides, whereby the active metal component(s) is (are) carried on the aluminosilicate by impregnation.
Dependencies are inferred from the claim text.