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, kappa appa-phase kappa-Ce2Zr2O8 was constructed to strengthen Pd-CZ interaction and thus stabilize palladium species. For comparison, tetragonal-phase Ce0.5Zr0.5O2 with kappa-Ce2Zr2O8 phase (kappa CZ) and without (tCZ) were prepared. The (kappa CZ+Al2O3) supported catalyst (Pd/kappa CZA) exhibited a higher activity than Pd/tCZA even after aging at 900 degrees C or 1000 degrees C for 4 h. The larger reaction rate and TOF values of Pd/kappa CZA-900 evidenced its higher intrinsic activity, especially for C3H8 conversion. The analyses proved that kappa-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.

Automated summary

In order to address the migration of metallic species between Al2O3 and CZ, kappa-Ce2Zr2O8 phase was constructed to strengthen Pd-CZ interaction. The Pd/kappa CZA catalyst exhibited higher catalytic activity, selectivity, and intrinsic activity.