Methane combustion over palladium catalyst within the confined space of MFI zeolite

Abstract

Isolated cationic Pd species encapsulated in MFI zeolite, i.e., Pd@MFI, have been successfully prepared via in situ hydrothermal route followed by oxidative treatment. The as-prepared Pd@MFI samples are investigated as promising catalysts in the reaction of methane combustion. Typically, Pd@H-ZSM-5 shows remarkable activity in methane catalytic combustion with a low apparent activation energy value of 70.7 kJ/mol as well as good catalytic stability even in excess water vapor. Detailed characterization results demonstrate the strong interaction between Pd sites and zeolite framework in Pd@ZSM-5 and the efficient stabilization of isolated Pd sites by zeolite thereof. Spectroscopy analyses reveal that the presence of Brønsted acid sites is beneficial to methane adsorption and its subsequent activation on adjacent Pd sites, constructing cooperation between Brønsted acid sites and Pd sites within the confined space of MFI zeolite toward high-efficiency methane catalytic combustion. The reaction mechanism of methane combustion catalyzed by Pd@H-ZSM-5 model catalyst is finally discussed.