Theoretical study of the mechanism of dry reforming of methane over Pd-doped CeO2 supported-Ru catalyst: The importance of oxygen self-spillover behavior

Abstract

Carbon deposition negatively affects the dry reforming of methane (DRM). Thus, here, palladium (Pd) was doped to Ru/CeO2 to enhance the oxygen self-spillover behavior on the interface, and the obtained effects were studied using the density functional theory (DFT) and microkinetic modeling. After doping Pd, the lattice oxygen was active. To simulate conditions closer to those of an experiment, a dynamic model under realistic conditions and a static model were considered. For the dynamic model, lattice oxygen atoms spilled over from the surface to the Ru spontaneously. DFT calculations demonstrated that interfacial oxygen self-spillover plays a pivotal role in increasing C-O formation and enhancing the DRM reaction rate while inhibiting the rapid decomposition of CHx, which hinders C* formation. Coke formation analysis indicated that oxygen spillover inhibits the coupling of C*-C* (C*+C*→C2*), leading to strong resistance to coke deposition and preventing the deactivation of catalysts. Microkinetic simulations showed that the dynamic model has a higher turnover frequency (TOF) rate and a higher selectivity for the DRM reaction. The high catalytic activity of the dynamic model is mainly due to the low coverage by CH*/C* on the catalyst’s surface. We expect that our results will provide a strategy for the design of DRM catalysts by enhancing interfacial oxygen self-spillover, using doped atoms.