New approach to enhance the NOx storage performance at high temperature using basic MgAl2O4 spinel support

With the purpose of improving the NOx storage performance of NOx storage and reduction (NSR) catalysts above 673 K, a new approach using a support with a higher basicity than γ-Al2O3 was proposed and exemplified by using the MgAl2O4 spinel as the support for an NSR catalyst containing the potassium NOx storage material. The NOx storage amounts on the fresh and thermally-aged K/Pt/MgAl2O4 catalysts at 873 K were apparently higher than those on the K/Pt/Al2O3 catalysts. The higher potassium basicity resulting from the interaction between the basic MgAl2O4 support and the potassium NOx storage material enhanced the stability of the stored NOx over the fresh and thermally-aged K/Pt/MgAl2O4 catalysts, which leads to their competitive NOx storage amounts versus those of the K/Pt/Al2O3 catalysts. These results indicated a breakthrough that improved the performance of the NSR catalysts at high temperature.