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Pt/SiO 2 -Al 2 O 3 (Pt/SA) is commonly used as diesel oxidation catalysts (DOC) in industry, but it could be seriously deactivated caused by H 2 O 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% H 2 O 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 H 2 O didn't affected Pt states and support structure as they were similar over two aged catalyst. 1H NMR and In-situ DRIFTS 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. [Display omitted] • H 2 O inhibition mechanism at hydrothermal aging on Pt/SiO 2 -Al 2 O 3 for NO oxidation was investigated. • H 2 O leaded to the loss of Brönsted acid sites (like-bridge Al-OH-Si). • The loss of acid sites induced by H 2 O suppressed decomposition of nitrate species resulting in low NO activity. [ABSTRACT FROM AUTHOR]

To improve the fuel economy, it is crucial to promote the low-temperature performance in eliminating diesel emissions. The work investigates the impact of different MnO 2 /Mn 2 O 3 phase ratio on the low-temperature performance of Pt-based monolithic diesel oxidation catalyst. Near equal ratio of MnO x phase could form the three-phase (platinum, MnO 2 , Mn 2 O 3) interfacial structure, leading to the smaller platinum particle size and exhibiting the higher interface rate (1.6–11.1 times) than other mono-manganese oxide with platinum. Besides, the higher oxygen mobility and more active oxygen species could be contributed to the positive effect of Pt/MnO x interface, which are prevalent to activate the reactant and greatly enhance the TOF value (1.4–20.8 times). The results imply that the modification of multi-phase metal/oxide interface is potential in dispersing platinum for greatly enhancing the catalytic efficiency. Catalyst with near equal ratio of MnO x phase could promote the formation of three phases interface structure, which has a relative higher interface rate and TOF value for the oxidation reaction, indicating the excellent low-temperature performance. [Display omitted] • Equal ratio of MnO x phase on catalysts form the three phases interface structure. • Catalyst with multi-interfacial structure has a relative higher interface rate. • Multi-interfacial structure improves the platinum dispersion and TOF value. • The low temperature oxidation performance was improved via controlling MnO x phase. [ABSTRACT FROM AUTHOR]

FeO x -doped Pt-based catalyst (PF) has a better platinum dispersion and higher platinum valence than CeO 2 -doped Pt-based catalyst (PC), presenting a better low-temperature activity in oxidizing CO/C 3 H 6 not only in fresh state(PF and PC) but also in aged state(PF-A and PC-A). In oxidizing NO, however, a higher NO max conversion appears on PC in fresh state and appears on PF in aged state, respectively. • FeO x -doped Pt-based catalyst (PF) presents a better low-temperature activity. • CeO 2 -doped Pt-based catalyst (PC) has a higher NO max conversion. • PF has a better dispersion and a higher valence of platinum than PC. • The specific performance promotes the configuration in aftertreatment system. Diesel emissions (CO/C 3 H 6 / NO) were eliminated on FeO x -doped and CeO 2 -doped Pt-based catalysts respectively to compare reaction mechanism and performance features. FeO x -doped catalyst has a higher platinum dispersion, a higher platinum valance state retarding CO adsorption and a higher oxygen mobility. Both of the higher dispersion and the oxygen mobility have a positive role in low-temperature catalytic oxidation performance, lower by 26 °C for CO light-off temperature and 12 °C for C 3 H 6 light-off temperature respectively than CeO 2 -doped catalyst. On FeO x -doped catalyst, the lesser surficial active oxygen species form the byproduct Fe(NO), resulting in an reduction of 10% NO maximum conversion. Besides, hydrothermal aged FeO x -doped catalyst with reduction treatment show a relatively lower light-off temperature and a higher NO max conversion. The difference in reaction characterization enlighten that the composition of oxidation catalyst would focus on the specific performance for the practical configuration in aftertreatment system for the better diesel emissions prevention. [ABSTRACT FROM AUTHOR]