Dynamic oxygen mobility and a new insight into the role of Ni doping in Pd/CeO2–ZrO2 three-way catalysts

CZ doped by nickel oxide with different loadings was prepared through a co-precipitation and supercritical dried method and the corresponding Pd-only TWCs were prepared and characterized. The results demonstrate that Pd/CZNi(3%) catalyst exhibits the best catalytic activity and the widest operation window before and after aging, compared with that of other catalysts. Moreover, the introduction of nickel oxide with 3% loading increases the average pore diameter and broadens the range of pore size distribution of sample, which is propitious to the formation of accumulative pore favoring the adsorption/desorption of reaction species. The introduction of nickel oxide with suitable loading (3%) promotes the thermal stability of CZ corresponding to the better surface composition and more concentration of Ce3+ or oxygen vacancy. Furthermore, the introduction of nickel oxide with 3% loading exhibits the best DOSC compared with other content doping, possibly due to the better structure and better surface composition and better thermal stability of CZNi(3%).

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► Pd/CZNi(3%) catalyst exhibits the best catalytic activity before and after aging.
► The introduction of Ni with 3% loading promotes the thermal stability of CZ.
► CZNi(3%) exhibits better surface composition and more concentration of Ce3+.
► The increasing of oxygen vacancies for CZNi leads to the enhancement of DOSC.