Exceptional Activity for Methane Combustion over Modular Pd@CeO ₂ Subunits on Functionalized Al ₂ O ₃

TLDR

Methane oxidation catalysts are needed to curb methane emissions and improve gas turbine performance, yet existing materials are either inactive below 400 °C or unstable at higher temperatures. The study aims to develop a highly active and thermally stable methane oxidation catalyst. This is achieved by preorganizing Pd core–CeO₂ shell subunits in solution and homogeneously depositing them onto hydrophobic alumina. The resulting catalyst retains isolated Pd cores after 850 °C treatment and, due to enhanced metal–support interactions, achieves complete methane conversion below 400 °C with exceptional thermal stability.

Abstract

There is a critical need for improved methane-oxidation catalysts to both reduce emissions of methane, a greenhouse gas, and improve the performance of gas turbines. However, materials that are currently available either have low activity below 400°C or are unstable at higher temperatures. Here, we describe a supramolecular approach in which single units composed of a palladium (Pd) core and a ceria (CeO(2)) shell are preorganized in solution and then homogeneously deposited onto a modified hydrophobic alumina. Electron microscopy and other structural methods revealed that the Pd cores remained isolated even after heating the catalyst to 850°C. Enhanced metal-support interactions led to exceptionally high methane oxidation, with complete conversion below 400°C and outstanding thermal stability under demanding conditions.