| 摘要 |
PURPOSE: To obtain a good rate of NOx purification in an excessive oxygen atmosphere by setting the α-conversion rate of alumina in a specified range and specifying the weight percentage of a catalyst element in a catalyst for purifying exhaust gas having the catalyst element comprising alumina and a catalytic metal supported on the alumina and CeO2 . CONSTITUTION: In a catalyst having a catalyst element 2 comprising alumina and a catalytic metal supported on the alumina and CeO2 , the alumina is modified alumina in which an α-conversion rate is set in a range 0.1%<=R<98%. When the content in weight of the catalyst element is A, and the content of CeO2 is B, the weight percentage of the catalyst element, A1 = A/(A+B)}×100 is set within a range from 20 to 88. The catalytic metal is at least one kind of metal selected from a platinum group, and the weight percentage a1 of the catalytic metal in the catalyst element is set within a range from 0.1 to 5. The average diameter D of CeO2 crystallite is set to be <500 angstrom. |
