Methane Oxidation on Ion-Doped Ceria Catalysts

Abstract

This study investigates the oxidation of methane (CH4) on platinum (Pt) and palladium (Pd) ion-doped cerium dioxide (CeO2) catalysts through a multidisciplinary methodology that integrates continuous-flow experimental observations, density functional theory (DFT) modelling, and micro-kinetic analysis. Incorporating Pt or Pd in ionic form into the CeO2 reduces the CH4 oxidation by approximately 100~150 K compared to undoped CeO2. Under fuel-lean conditions, the reaction kinetics are predominantly influenced by CH4 concentration, exhibiting first-order kinetics, while the dependence on O2 is zero-order. DFT calculations reveal that CH4 dehydrogenation proceeds via hydrogen extraction from surface lattice oxygen, with the doping species facilitating increased reactivity between carbon atoms and lattice oxygen, thus generating carbon monoxide (CO) and carbon dioxide (CO2). The energy profiles obtained from DFT indicate that the rate-limiting steps involve the initial dehydrogenation of CH4 and water formation through surface lattice oxygen extraction.

Keywords: catalysis, DFT, Micro-Kinetics, Ceria, Oxidation