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The hydrothermal stability of NO oxidation is the key to the practical application of diesel oxidation catalysts in diesel engines, which in the laboratory requires that NO activity does not decrease after aging for 10 h with 10% H2O/air at 800 °C. On the one hand, the construction of a metal/oxide interface can lead to abundant oxygen vacancies (Ov), which compensate for the loss of activity caused by the aggregation of Pt particles after aging. On the other hand, YMn2O5(YMO) has excellent thermal stability and NO oxidation capacity. Therefore, a Pt/YMn2O5-La-Al2O3(Pt/YMO-LA) catalyst was prepared by the impregnation method. The support of the catalyst, YMn2O5-La-Al2O3(YMO-LA), was obtained by mixing high specific surface LA and YMO ball-milling. Under laboratory-simulated diesel exhaust flow, the NO oxidation performance of Pt/YMO-LA did not decrease after hydrothermal aging. Combining high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and oxygen temperature-programmed desorption (O2-TPD), the Pt/YMn2O5interface was formed after hydrothermal aging, and the increased Ovcan provide reactive oxygen to Pt and YMO. The cooperative catalysis of multiple active centers composed of Pt, YMO, and Ovis the crucial factor to maintain the NO oxidation performance. In addition, in situ diffuse reflectance infrared Fourier transform spectra (DRIFTs) show that an increase in Ovis beneficial to the adsorption and desorption of more nitrate and nitrite intermediates, thus achieving the hydrothermal stability of NO oxidation.

Pt/SiO2-Al2O3(Pt/SA) is commonly used as diesel oxidation catalysts (DOC) in industry, but it could be seriously deactivated caused by H2O at long-term high temperature. In this paper, the inhibition mechanism of water on Pt/SA for NO oxidation was studied. The fresh Pt/SA (Pt/SA-F) was treated in an air flow with/without 10% H2O at 700 °C for 10 h to obtain the hydrothermally/thermally aged catalysts named as Pt/SA-HA and -A, respectively. NO oxidation tests showed that Pt/SA-HA had lower activity than Pt/SA-A. A series of characterizations proved H2O didn’t affected Pt states and support structure as they were similar over two aged catalyst. 1H NMR and In-situDRIFTS testified that water deactivation was a result of the acidity loss of catalysts, which inhibited the decomposition and desorption of reaction intermediate, finally resulting in bad NO oxidation activity.