Generation of active oxygen species by CO2 dissociation over defect-rich Ni-Pt/CeO2 catalyst for boosting methane activation in low-temperature dry reforming: Experimental and theoretical study

Abstract

Herein, we demonstrated a one-pot complex combustion method to synthesize defect-rich Ni-Pt/CeO2 catalyst having oxygen vacancy sites (Vo) by incorporating Ni and Pt species into the ceria lattice. These Vo sites are highly active for dissociating CO2 into reactive oxygen species and CO at low temperature. CH4-TPSR demonstrated that surface reactive oxygen species are more selective than lattice oxygen toward the formation of syngas. The catalytic properties and activity of the synthesized catalysts were also compared with the conventionally impregnated catalyst. In-situ DRIFT and Raman study revealed reactive oxygen-assisted CH4 activation via the formation of CHxO intermediate. DFT calculation also showed the facile formation of CH3O and CH2O species over the bimetallic NiPt-CeO2(111) catalyst surface. The Ni-Pt/CeO2 (0.5 wt%Pt-2 wt%Ni) catalyst showed superior activity and stability with ∼86% conversion of CH4 and CO2 at 675 °C, where the H2/CO ratio is one. The catalyst was stable up to 700 h time-on-stream.