Promoting effect of synthesis method on the property of nickel oxide doped CeO2-ZrO2 and the catalytic behaviour of Pd-only three-way catalyst

CeO2-ZrO2 doped by nickel oxide (CZN) with different method and Pd-only three-way catalysts (Pd/CZN) were prepared and characterized. The catalyst prepared by co-precipitation and supercritical drying process (Pd/CZN-s) exhibits the best catalytic activity and the widest operation working window before and after aging. Compared with other samples, CZN-s shows the formation of more homogeneous ternary solid solution with the smallest lattice parameter and crystallite size. Moreover, CZN-s maintains the high thermal and structural stability with higher surface area and larger pore volume after aging. Pd/CZN-s exhibits higher relative concentration of Ce3+ associated with the formation of more oxygen vacancies before and after aging, confirmed by X-ray photoelectron spectroscopy and Raman results. The more concentration of Ce3+ or oxygen vacancies leads to the enhancement of oxygen storage complete capacity of CZN-s. Moreover, the higher the oxygen storage capacity, the wider the working ranges of air/fuel variations.

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► Pd/CZN-s exhibits the best catalytic performance and the widest operation window.
► CZN-s confirms the formation of homogeneous ternary solid solution.
► CZN-s maintains higher thermal and structural stability after aging.
► Pd/CZN-s shows higher concentration of Ce3+ or the formation of oxygen vacancies.
► The more concentration of Ce3+ over CZN-s leads to the enhancement of OSCC.