Ni/CexZr1-xO2 catalyst prepared via one-step co-precipitation for CO2 reforming of CH4 to produce syngas: role of oxygen storage capacity (OSC) and oxygen vacancy formation energy (OVFE)

摘要

Ceria-zirconia solid solution (Ce0.5Zr0.5O2)-supported Ni catalyst (15 wt. ) is prepared by one-step co-precipitation followed by calcination reduction for CO2 reforming of CH4 (DRM). Oxygen storage capacity (OSC) is measured by O-2 pulse injection at the reaction temperature. The solid solution is formed upon incorporating Zr4+ into ceria, subsequently accelerating oxygen mobility from lattice (bulk) to the surface, enhancing Ce3+ due to increased oxygen vacancies, and thus improving OSC, reducibility, surface basicity, and Ni dispersion compared to pure CeO2 and ZrO2. The solid solution exhibits better conversions of CH4 and CO2, a higher H-2/CO ratio, and low carbon deposition compared to its pure counterpart. The density functional theory (DFT) studies unveil oxygen vacancy formation energy (OVFE) as a descriptor that decreased for Ce0.5Zr0.5O2 due to the incorporation of Zr4+ and enhanced mobility of O anions, OSC, and reducibility.