Effect of synthesis condition on properties of Ce0.67Zr0.33O2 mixed oxides and its application in Pd-only three-way catalysts

Ce0.67Zr0.33O2 (CZ) mixed oxide was prepared by coprecipitation and effect of the synthesis conditions on CZ properties were investigated in this work, as well as the catalytic performance of Pd-only three-way catalyst (TWC) supported on the prepared CZ. With the increase of aging temperature during precipitation, the crystallite size of CZ increases significantly, while the oxygen storage capacity complete (OSCC) drops and no notable effect on porosity of CZ is observed. The porosity is mainly determined by drying temperature and pH value during precipitation. Prepared under optimized conditions (precipitation at the pH of 9.5, aging at 25 degrees C and then drying under supercritical condition in alcohol), the CZ samples exhibit good properties. This preparation procedure leads to CZ with proper pore size distribution, larger average pore size (20.42 nm), higher pore volume (0.69 cm(3)/g) and enhanced OSCC value (383.0 mu mol/g). Furthermore, the Pd-only TWC supported on the CZ synthesized under the optimized conditions exhibits satisfactory catalytic activity and very low reduction temperature (53 degrees C). Crown Copyright (c) 2010 Published by Elsevier B.V. All rights reserved.