Methane oxidation on ion-doped ceria catalysts

This study investigates the oxidation of methane (CH 4 ) on platinum (Pt) and palladium (Pd) ion-doped cerium dioxide (CeO 2 ) 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 CeO 2 reduces the CH 4 oxidation by approximately 100∼150 K compared to undoped CeO 2 . Under fuel-lean conditions, the reaction kinetics are predominantly influenced by CH 4 concentration, exhibiting first-order kinetics, while the dependence on O 2 is zero-order. DFT calculations reveal that CH 4 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 (CO 2 ). The energy profiles obtained from DFT indicate that the rate-limiting steps involve the initial dehydrogenation of CH 4 and water formation through surface lattice oxygen extraction.