The strengthened Pd-(CeO2-ZrO2) interaction by κ-Ce2Zr2O8 and the improved three-way catalytic performance

The migration metallic species between Al 2 O 3 and CeO 2 -ZrO 2 (CZ) is one of the main causes for the deactiviation of the three-way catalysts (TWCs). In order to address this issue, κappa-phase κ -Ce 2 Zr 2 O 8 was constructed to strengthen Pd-CZ interaction and thus stabilize palladium species. For comparison, tetragonal-phase Ce 0.5 Zr 0.5 O 2 with κ -Ce 2 Zr 2 O 8 phase ( κ CZ) and without ( t CZ) were prepared. The ( κ CZ+Al 2 O 3 ) supported catalyst (Pd/ κ CZA) exhibited a higher activity than Pd/ t CZA even after aging at 900 °C or 1000 °C for 4 h. The larger reaction rate and TOF values of Pd/ κ CZA-900 evidenced its higher intrinsic activity, especially for C 3 H 8 conversion. The analyses proved that κ -Ce 2 Zr 2 O 8 could strengthen Pd-CZ interaction, subsequently induced Pd to selectively interact with CZ rather than Al 2 O 3 and inhibited palladium from migrating from CZ to Al 2 O 3 . Additionally, in situ DRIFTS analysis proved that the strengthened Pd-CZ interaction facilitated to regenerate active palladium and NO transforming to reactive monodentate nitrate/nitrite. • Constructing κ -Ce 2 Zr 2 O 8 enhances the catalytic performance of Pd-only catalyst. • κ -Ce 2 Zr 2 O 8 could induce Pd to selectively interact with CZ rather than Al 2 O 3 . • Strengthened Pd-CZ interaction can promote the regeneration of active palladium. • Monodentate nitrate/nitrite has a higher reactivity with C 3 H 8 than other ones.