The Effects of P-Poisoning of Ce_xZr_1−xO₂ on the Transient Oxygen Storage and Release Kinetics

The present work reports on the investigation of the effects of chemical poisoning of Ce_xZr_1−xO₂ solids by phosphorous (P) on the kinetics of oxygen storage and release (OSR) of the thus derived P-contaminated solids, as a function of Ce_xZr_1−xO₂ solid composition (x = 0.3, 0.5 and 0.7) for the first time. Phosphorous deposition on the surface of Ce_xZr_1−xO₂ particles followed by calcination in air at 850 °C forms nano-crystals of CePO₄, which lead to a drastic decrease in the population of surface and subsurface reactive and mobile oxygen species due to the formation of P–O–Ce bonding. The concentration (μmol/g) of exchangeable ¹⁶O in the solid with ¹⁸O from the gas phase was found to increase, and the degree of reduction in the Oxygen Storage Capacity (OSC) to decrease with increasing Ce content in the Ce_xZr_1−xO₂ solid after P-poisoning. The increase in the Ce content of Ce_xZr_1−xO₂ makes its OSR properties more resistant against P-poisoning due to the increasing number of poison-free Ce atoms, which are able to participate in the Ce³⁺ ↔ Ce⁴⁺ redox cycle.