Acidities of CeO2 and Ce0.5Zr0.5O2 solid solutions studied by NH3-TPD

Abstract

Ammonia temperature-programmed desorption (NH3-TPD) was used to study the acidities of CeO2 and Ce0.5Zr0.5O2 solid solutions. The NH3-TPD peaks of both CeO2 and Ce0.5Zr0.5O2 exist at 100–850 °C. The ratio of the lower and middle temperature peak areas to the higher temperature peak is decreased for Ce0.5Zr0.5O2 relative to CeO2 under all pretreatment conditions, which suggests that Ce0.5Zr0.5O2 has more acid sites of higher energy than CeO2. This may be one of the reasons why Ce0.5Zr0.5O2 is a more highly efficient catalyst for methane combustion than CeO2. Copyright © 1999 John Wiley & Sons, Ltd.