Ceria-modified Pt/Al₂O₃ catalyst has been commonly prepared by the impregnation of platinum on ceria-modified alumina and widely applied in the chemical industry and automotive industry. The in situ diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS), and thermogravimetric (TG) analysis techniques were employed to investigate the typical mechanisms of the bis(ethanolammonium)hexahydroxyplatinate(IV) and cerium nitrate decomposition catalyzed by Pt^δ+ species for the facile synthesis of CeO₂-Pt/Al₂O₃ catalyst. It was found that Pt⁴⁺-catalyzed decomposition of cerium nitrate leads to the higher dispersity of ceria and forming more active oxygen species, on the basis of X-ray diffraction (XRD) and H₂ temperature-programmed reduction (H₂-TPR) results. The in situ activity measurements were also performed to investigate the reaction mechanisms and the specific activities for the catalytic CO, NO, C₃H₆ and C₃H₈ co-oxidation. The results indicate that undesirable N₂O by-product is formed by the selective catalytic reduction (SCR) of NO by C₃H₆ below 350 °C. The cerium addition effectively improves the activity of catalytic oxidation, but exhibits an increased N₂O yield, due to the increased reducibility.

Passive NOx adsorber (PNA) is one of the important means to effectively reduce NOx emission control in the cold start of a diesel engine. A series of Pd/SSZ-13 catalysts with different SiO₂/Al₂O₃ ratios (11, 17, and 25) were prepared using the impregnation method. Furthermore, the effect of the SiO₂/Al₂O₃ ratio on the adsorption performance of Pd/SSZ-13 at low-temperature NOx under realistic exhaust conditions was studied. The results show that the Pd/SSZ-13 catalyst with a low SiO₂/Al₂O₃ ratio after loading Pd has a higher specific surface area and palladium ion content. There is a negative correlation between NOx adsorption performance and the SiO₂/Al₂O₃ ratio. After high-temperature heat treatment, the acid sites closely related to palladium species increase and palladium species will redisperse, producing more palladium ions. The palladium ions coexist in Pd/SSZ-13 in the form of Pd²⁺ and Pd⁺, among which Pd²⁺ is divided into two types: Z⁻Pd²⁺Z⁻ and Z⁻[Pd(II)OH]⁺. The NOx adsorption performance of the Pd/SSZ-13 catalyst was significantly improved, and the higher the SiO₂/Al₂O₃ ratio, the more obviously the advantage of NOx adsorption performance increased after heat treatment. The NOx adsorption kinetic model of the Pd/SSZ-13 catalyst under realistic exhaust conditions was most suitably described by the pseudo-first-order model.