The effects of aging temperature and aging time on the oxygen storage capacity of Pt-Rh/CeZrO2 catalysts

Abstract

The effects of aging temperature and time on the oxygen storage capacity (OSC) of Pt-Rh-promoted Ce0.75Zr0.25O2 solid solutions were measured and correlated with the BET surface area and noble metal (NM) surface area in the catalysts. The NM surface area is better correlated with OSC than is with the BET surface area. On a practical level, our results demonstrated that, even when operating at 900°C with alternating oxidizing and reducing conditions, these materials deactivate slowly with a near t-1 time dependence. Deactivation rates for these catalysts are dependent on the NM loading with the highest loaded catalysts deactivating roughly half as fast as the lowest loaded catalysts. As the aging temperature is increased from 900°C to 1000°C, the deactivation rate becomes two to four2-4 times higher for all three properties (BET surface area, NM surface area and OSC). The lowest NM loaded samples are more sensitive to aging temperature than the highest loaded ones

Effect of Ce/Zr ratio on the performance of Pt/CeZrO2/Al2O3 catalysts for methane partial oxidation

“…The metal dispersion has a positive effect on the performance of catalysts on POM [14]. In spite of redox properties, ceria-zirconia supports generally exhibit low surface area and then, poor metal dispersion [16,17]. In order to limitations, different approaches have been pursued such as the deposition of ceria-zirconia over an oxide with a higher surface area.…”

New Results for Electron Transport, Chemical Diffusion and Stability of Solid Oxygen Ion Conductors

“…These materials have been investigated in many laboratories during the last years because of their interesting catalytic properties and oxygen storage effects [30][31][32][33][34][35][36][37][38]. It is known from these investigations that the electronic properties are distinctly different from pure doped ceria or zirconia.…”

O efeito da desativação térmica nas propriedades oxirredutoras e na atividade catalítica de catalisadores CZ e Pd-CZ

“…5,6 Vários trabalhos da literatura se dedicaram ao estudo do envelhecimento térmico de catalisadores automotivos comerciais e seu impacto nas propriedades oxirredutoras. [7][8][9][10][11][12][13][14][15][16] No entanto, nem sempre foi possível estabelecer uma relação direta entre os resultados de redutibilidade e o rigor usado no envelhecimento térmico, entre outros aspectos, devido à complexidade natural do catalisador automotivo que apresenta um grande número de compostos em sua formulação.…”