The effects of P-poisoning of CexZr1-xO2 on the transient oxygen storage and release kinetics

Abstract

The present work reports on the investigation of the effects of chemical poisoning of CexZr1-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 CexZr1-xO 2 solid composition (x = 0.3, 0.5 and 0.7) for the first time. Phosphorous deposition on the surface of CexZr1-xO 2 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 CexZr1-xO 2 solid after P-poisoning. The increase in the Ce content of Ce xZr1-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+ → Ce 4+ redox cycle. © 2013 Springer Science+Business Media New York.