Transient analysis of oxygen storage capacity of Pt/CeO2–ZrO2 materials with millisecond- and second-time resolution

Effect of oxygen storage materials on the performance of Pt-based three-way catalysts

“…Compared to Al 2 O 3 -based commercial TWC supports [31][32][33][34][35] and other promising metal oxide supports, 36,37 oxygen storage materials (OSMs) such as CeO 2 and CeO 2 -ZrO 2 solidsolutions are effective for control of air-fuel ratios (AFRs) that deviate from the stoichiometric conditions (λ = 1) in realworld applications; that is because OSMs possess excellent oxygen storage capacity (OSC) due to the rapid redox reaction of Ce, between its 4+ and 3+ oxidation states. [38][39][40][41][42][43][44][45][46][47] Introducing the Zr 4+ cation into the lattice of CeO 2 increases the concentration of structural defects, improves the oxygen mobility, and enhances the Ce 3+ /Ce ratio on the surface of PGM-based catalysts, producing more oxygen vacancies and Ce in the Ce 3+ state. [48][49][50][51] Note that such structural defects should only be local perturbation and the overall structure should be homogeneous on average as the dynamic oxygen mobility in Pt/CeO 2 -ZrO 2 catalysts was proportional to the structural homogeneity arising from the introduction of Zr into the CeO 2 framework.…”

The effect of Pd precursor on Pd/Ce0.67Zr0.33O2 catalysts for automotive emission control

“…It also has the ability to increase the thermal and structural stability of the catalyst carrier [6]. The introduction of zirconia into the ceria lattice can significantly increase the oxygen va-cancies in the fluorite lattice by charge compensation, facilitate oxygen diffusion or transport and enhance the thermal stability of the solid solution [7]. Better results are obtained with CexZr1−xO2 with x ranging from 0.6 to 0.8 [8,9].…”

Proton-Conductor-Supported Ultra-Low Loading Pt–Rh Three-Way Catalysts

“…Catalytic purification of emissions from gasoline engines has been commonly performed by supported Pt–Rh–Pd catalysts. , In this three-way catalyst (TWC), unburned hydrocarbons (HCs) and carbon monoxide (CO) are oxidized, and at the same time, any nitrogen oxides (NO x ) produced are reduced, accomplished by controlling the air/fuel ratio of the exhaust close to a stoichiometric value of 14.6. The addition of cerium dioxide (ceria) or related compounds to TWCs promotes both HC oxidation under fuel-rich conditions and NO x reduction under fuel-lean conditions. − The reaction scheme over TWCs is very complicated; however, reactions on the noble metal surface can be explained using Langmuir–Hinshelwood kinetics and reactions on the ceria surface mainly follow the Eley–Rideal mechanism . The catalyst support is also an important component in TWCs for enhancing dispersion of reaction sites; however, it has a significantly smaller effect on the reaction scheme, compared to the catalyst and the promoter.…”