Enhanced Thermal Stability of Lean Methane Combustion by Structural Interactions of CeO2 with Pt/3DOM LaFeO3 Catalysts

It is challenging to load precious metals nanoparticles on LaFeO3 perovskite with small specific surface, and to improve the thermal stability of precious metals is also very difficult. Therefore, it is of great significance to disperse precious uniformly on perovskite with low specific surface area and to make the catalyst with high catalytic activity and thermal stability. In this work, we develop series of perovskite-based methane combustion catalysts with good catalytic activity and stability. Compare with traditional LaFeO3 catalysts, the catalytic activity of three-dimensional ordered macroporous (3DOM)LaFeO3 significantly improves by loading Pt. In addition, its thermal stability is significantly improved by adding CeO2, especially at high roasting temperature (800 C). The 1 wt%Pt/10 %CeO2/3DOM LaFeO3 catalysts shows the highest catalytic activity in which the T10, T50 and T90 are 362 C, 433 C and 502 C, and its recaction temperature of T50 is decreased by 50 C compare with Pt/3DOM LaFeO3(800). The different physical and chemical characterizations suggest that the coupling of Ce3+ and Fe2+ induces the formation of a large number of oxygen vacancies, which promotes the oxygen mobility and th oxygen storage capacity during the methane oxidation process. More importantly, the CeO2 addition contributes to the Pt-CeO2 interaction with Ce-O-Pt bond formation, which greatly improves the thermal stability of the catalyst, and this Pt-CeO2 interaction strength becomes more obvious with the increase of calcination temperature. Furthermore, the in-situ DRIFT experiments indicate that M -K mechanism is probably involved in the reaction process.