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

The migration metallic species between Al2O3 and CeO2-ZrO2 (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-Ce2Zr2O8 was constructed to strengthen Pd-CZ interaction and thus stabilize palladium species. For comparison, tetragonal-phase Ce0.5Zr0.5O2 with κ-Ce2Zr2O8 phase (κCZ) and without (tCZ) were prepared. The (κCZ+Al2O3) supported catalyst (Pd/κCZA) exhibited a higher activity than Pd/tCZA even after aging at 900 °C or 1000 °C for 4 h. The larger reaction rate and TOF values of Pd/κCZA-900 evidenced its higher intrinsic activity, especially for C3H8 conversion. The analyses proved that κ-Ce2Zr2O8 could strengthen Pd-CZ interaction, subsequently induced Pd to selectively interact with CZ rather than Al2O3 and inhibited palladium from migrating from CZ to Al2O3. 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.