Pd encapsulated by hollow silica spheres for enhanced total oxidation of methane in the presence of water

Unburnt methane emitted from stationary and internal combustion engines has raised concerns due to its strong greenhouse effect. Pd-based catalysts are considered as benchmark for total oxidation of methane at exhaust gas conditions. However, high content of water vapor drastically decreases their performance. Here we present an encapsulated Pd catalyst by hollow silica spheres that presents an enhanced catalytic activity in the presence of water vapor. The use of hydrophobic support alone showed limited improvement, whereas encapsulation of Pd in a confined volume efficiently combusted methane in wet conditions. The effect of Pd encapsulation was discussed. [Display omitted] •N-doping induced ligand effect and kept more PdO sites at working conditions.•Encapsulated volume with confined diffusion facilitated PdO regeneration in steam.•Hydrophobic support alone showed limited improvement of the activity in steam.•The intimated gas phase at the surroundings of Pd was evolved in the catalysis.