Abstract: A new (CeO₂-ZrO₂-Al₂O₃)-(La₂O₃-Al₂O₃) complex oxide (CZA-LA) was prepared by the simultaneous co-precipitation method and then it was calcined at different temperatures. The samples calcined at different temperatures were used as support to prepare Pd/CZA-LA catalysts by impregnation and they were further fabricated as close-coupled catalysts in monolith form. The Pd loading of close-coupled catalysts was 2 g/L. The Pd/CZA-LA samples were characterized by N₂ adsorption-desorption and X-ray diffraction, and the corresponding catalyst was examined by temperature-programmed reduction of H₂ and C₃H₈ conversion in a simulated automobile exhaust. It was found that both textural properties of the CZA-LA and catalytic performance of the Pd/CZA-LA were remarkably affected by the calcination temperature of CZA-LA support. The new complex oxide samples showed good structural and textural properties and were more resistant to aging at high temperature. The surface area of CZA-LA support decreased with increasing calcination temperature; however, it was still 122 m²/g for S1000 (noted as the CZA-LA support calcined at 1000 °C for 5 h) sample. The pore volume was stable for all of the samples except S600 sample. The catalytic evaluation results showed that the catalytic performance of all fresh catalysts was very good and similar to each other. The light-off temperature (T₅₀ = 310 °C) and complete conversion temperature (T₉₀ = 341 °C) of propane over the Pd/S1000-Aged (noted as the Pd/S1000 catalyst aged at 1000 °C for 5 h) was the lowest among the tested aged catalysts, and the temperature difference, ΔT, between the Pd/S1000-Aged and Pd/S1000-Fresh was as less as 7 °C, indicating that the Pd/S1000-Fresh catalyst showed good catalytic performance for exhaust purification and good resistance to aging. The catalyst may have potential application in the field of advanced Pd close-coupled catalysts.

Key words: palladium, close-coupled catalyst, simultaneous co-precipitation, propane, thermal stability, automotive exhaust purification, calcination temperature