Introduction Perovskite-type materials, with general chemical composition of ABO3-δ, where A and B are cations that may have multiple valence states, can exhibit significant swings in oxygen non-stoichiometry δ through the reaction with gas phase oxygen. The present study focuses on a systematic screening of advanced perovskites as potential substitutes for commercial CZO in TWC. Novel perovskite-type materials CaCoxZr1-xO3-δ were synthesized for the first time and reported here to show outstanding redox property and oxygen mobility than the current state-of the-art perovskite materials and the commercial CZO. Pd-doped CaCoxZr1-xO3-δ showed profound catalytic activity towards NMHC and CO oxidation. Results and Discussion H2-TPR profiles of the as-synthesized perovskites and commercial ceria-based oxygen storage material (OSM) samples are presented by Figure 1(a). The novel CaCoxZr1-xO3-δ perovskites exhibit higher reducibility than commercial Ce-based OSMs, as represented by higher H2 consumption (4.1~13.4 times higher) at lower reduction temperatures (50~250 oC lower). Specifically, the H2 consumption of CoxZr1-xO3-δ increases with Co content. Doping of Pd into the perovskite structure further enhances the reducibility by lowering the reduction temperature. Catalytic oxidation activities of Pd doped perovskite OSMs are shown in Figure 1(b) and 1(c). Pd doped CoxZr1-xO3-δ exhibit excellent activity for CO and HC (C3H6) oxidation. Complete combustion of CO and HC was observed. The T50 for C3H6 oxidation was as low as 240 °C. The HC oxidation activities of all the Pd doped CaCoxZr1-xO3-δ TWCs are comparable to, if not higher than, state-of-the-art TWCs. These promising data clearly confirm the excellent potential for the proposed perovskite TWCs.

Pd doped CaCoxZr1-xO3-δ novel perovskites for automotive emissions control

255th National Meeting (2018)

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