Nano-sized alumina supported palladium catalysts for methane combustion with excellent thermal stability

Pd/Al 2 O 3 catalysts supported on Al 2 O 3 of different particle sizes were synthesized and applied in methane combustion. These catalysts were systematically characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM), high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), H 2 -temperature-programmed reduction (H 2 -TPR), O 2 -temperature-programmed oxidation (O 2 -TPO), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS). The characterization results indicated that nano-sized Al 2 O 3 enabled the uniform dispersion of palladium nanoparticles, thus contributing to the excellent catalytic performance of these nano-sized Pd/Al 2 O 3 catalysts. Among them, Pd/Al 2 O 3 -nano-10 (Pd/Al 2 O 3 supported by alumina with an average particle size of 10 nm) showed superior catalytic activity and stability for methane oxidation under harsh practical conditions. It maintained excellent catalytic performance for methane oxidation for 50 h and remained stable even after harsh hydrothermal aging in 10 vol.% steam at 800 °C for 16 h. Characterization results revealed that the strong metal-support interactions and physical barriers provided by Al 2 O 3 -nano-10 suppressed the coalescence ripening of palladium species, and thus contributed to the superior sintering resistance of the Pd/Al 2 O 3 -nano-10 catalyst.