Palladium redispersion at high temperature within the Pd@SiO2 core@shell structure

Maintaining high dispersion of palladium is critical for Pd-based catalysts, which suffer from deactivation due to sintering at high temperatures (≥800 °C). Here, we report direct evidence that Pd nanoparticles (~4 nm) of a palladium silica core@shell (Pd@SiO2) catalyst can redisperse into nanoclusters (≤2 nm) after aging at 800 °C, where severe Pd sintering would be expected on supported Pd catalysts. The Pd redispersion was confirmed by in situ, as well as ex situ, high resolution transmission electron microscopy, and is manifested by a remarkably decreased light-off temperature for CO oxidation after aging.