Deactivation of barium oxide-based NOx storage and reduction catalyst by hydrothermal treatment

The deactivation of a barium oxide-based NOx storage and reduction (NSR) catalyst with hydrothermal treatment was studied by treating it with 10 vol% water vapor diluted in nitrogen at 850°C. XRD, XPS, SEM, IR of CO adsorption, and the N2 adsorption was used to investigate the physical and chemical changes of the NSR catalyst caused by the hydrothermal treatment. The 12 h hydrothermal treatment decreased its NO2 storage capacity by 20%. However, the hydrothermal treatment significantly decreased its ability to reduce the stored NO2. The formation of an inactive phase consisting of platinum and aluminum is believed to be the cause of the severe deactivation of the NSR catalyst.