Small platinum oxide particles are beneficial for forming Pt⁰active species under diesel exhaust conditions, hence showing better DOC reactivity.

CuCe-SAPO-34 (CuCe-x) catalysts with 3 wt% Cu and various content of Ce for selective catalytic reduction of NO_x by NH₃ (NH₃-SCR) were prepared by a wet co-impregnation method. The activities of the CuCe-x catalysts were better than that of Cu-SAPO-34 (Cu). In addition, the hydrocarbon (HC) resistance of the CuCe-x catalysts was examined and compared to that of the Cu catalyst. The NH₃-SCR performance after C₃H₆ poisoning of the CuCe-x catalysts was preferable to that of the Cu catalyst, since the C₃H₆ oxidation performance was improved by the addition of Ce. The XRD, UV-vis-DRS and H₂-TPR results confirmed that the addition of Ce could inhibit the aggregation of CuO crystallites and increase the amount of isolated copper ions. Furthermore, the NH₃-TPD and TGA results demonstrated that the addition of Ce decreased the amount and strength of strong acid sites, so that the amount of C₃H₆/O₂ adsorption on the CuCe-x catalysts was lower than that on the Cu catalyst. Therefore, the activity and HC resistance of Cu-SAPO-34 was improved by the addition of Ce.

Yttria in Pt/TiO₂ catalyst improved the Pt dispersion and stabilized the structure, and hence enhanced the low-temperature activity and stability.