ULTRAFINE PALLADIUM NANOPARTICLES SUPPORTED ON THE MFI ZEOLITE FOR METHANE COMBUSTION REACRION

Abstract

The environmental impact of methane's incomplete combustion underscores the importance of catalytic oxidation, a process in which palladium (Pd) nanoparticles serve as a highly active catalyst despite their tendency to aggregate during synthesis and operation due to inherent high surface energy. Zeolites, as nanoporous materials with ordered micropore structures and excellent thermal stability, are considered ideal supports for stabilizing noble metal nanoparticles. Herein, MFI-type zeolite nanosheets rich in silanol defects were used as supports to prepare finely dispersed Pd nanocatalysts (Pd/SP-S-1 and Pd/SP-ZSM-5) via incipient wetness impregnation. The resulting catalysts exhibited excellent activity toward methane combustion. The T 90 (temperature for 90% methane conversion) value of Pd/SP-S-1 was 459 °C, which is lower than that of the catalyst supported on conventional S-1 zeolite. Introducing acidity further enhanced the catalytic performance, lowering the T 90 of Pd/SP-ZSM-5 to 426 °C. Moreover, the acidic zeolite framework improved the stability of Pd nanoparticles. The Pd/SP-ZSM-5 catalyst maintained stable activity for nearly 50 h at 430 °C. This work highlights the potential of zeolite-confined Pd catalysts for methane combustion and provides insights into designing synergistic catalytic systems combining metallic and acidic sites.