Study on hydrothermal deactivation of Pt/MnOx-CeO2 for NOx-assisted soot oxidation: redox property, surface nitrates, and oxygen vacancies

The study mainly focuses on surface properties to investigate the deactivation factors of Pt/MnOx-CeO2 by H-2 temperature-programmed reduction, CO chemical adsorption, NOx-temperature-programmed desorption (TPD), O-2-TPD, NO temperature-programmed oxidation, SEM, TEM, in situ diffuse reflectance infrared Fourier transform spectra, Raman, and thermogravimetric methods. The results show that there are three main factors to lead to hydrothermal deactivation of the catalyst: redox property, oxygen vacancy, and surface nitrates. The loss of oxygen vacancies decreases the generation and desorption of active oxygen and that of surface nitrates weakens the production of NO2 and surface peroxides (-O-2(-)). These factors greatly result in the damage of the C-NO2-O-2 cooperative reaction.