In-situ confinement of ultrasmall palladium nanoparticles in silicalite-1 for methane combustion with excellent activity and hydrothermal stability

Abstract

Maximizing the use of palladium without compromises in catalytic activity and stability in the combustion of methane is extremely challenging due to the harsh operation conditions. To achieve this goal, a series of core-shell-structured catalysts with different amounts of palladium nanoparticles confined in hydrophobic silicalite-1 (Pd@S-1) was designed. Unexpectedly, a volcanic trend between catalytic activity and palladium loading was found as the loading increased from 0.3 wt% to 1.6 wt%, among which the 0.6 wt%Pd@S-1 exhibited the highest catalytic activity with a complete combustion temperature of 380 °C. Besides, the 0.6 wt%Pd@S-1 showed an ultrahigh stability in the high temperature applications due to the spatial confinement of palladium inside the rigid zeolite matrix. Moreover, owing to the hydrophobicity of the pure silica zeolite, the Pd@S-1 could selectively hinder the diffusion of water vapor into the palladium sites, leading to the outstanding water-resistance ability.