Lower methane combustion temperature on palladium nanoparticles anchored on TiOx subnano-islets in stellate mesoporous silica nanospheres

Abstract

Palladium oxide nanoparticles of 9 nm stabilized on TiO_x subnano-islets (SNI) in monodispersed mesoporous silica nanospheres (MSN) having a stellate morphology are found to be very active for methane combustion. The characterization at various steps of the catalysts elaboration was performed using a panel of techniques including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visble reflectance spectroscopy. The catalytic performances were measured from methane combustion light-off experiments showing a remarkably low temperature light-off (T_10% ∼ 200 °C) of these particles in comparison to PdO nanophase on 2D TiO_x anchors (T_10% ∼ 280 °C) or those obtained without TiO_x anchors (T_10% ∼ 350 °C). The surprising performance of these new catalysts is attributed to a combination of parameters along with the stellate pore morphology likely favorable for high conversion and a diffusion-controlled regime.