Ce0.9Zr0.1O2 Mixed Oxide Prepared by the Citrate Route: Impact of Synthesis Conditions on Physicochemical and Redox Properties

Abstract

The aim of this work is to study the effect of the citric acid to metal molar ratio (CA/M) used in the citrate synthesis route on the structural, morphological and redox properties of CeO2‐ZrO2 mixed oxides. The CA/M ratio strongly affects reducibility, crystallite size and texture. The increase in calcination temperature promotes sample crystallinity while nanometric sizes remain up to 1000 °C. H2‐TPR, in situ dispersive X‐ray absorption (DXAS) and Raman experiments show that samples calcined at 1000 °C exhibit a three‐step reduction kinetics and onset temperatures related to the initial oxygen vacancy content. Specific surface area and crystallite size influences the reduction profile mainly at low temperatures (≤ 600 °C) and high temperatures (> 600 °C) respectively. The increase of crystallite size with calcination temperature favors the diffusion of oxygen species from the bulk to the surface, enhancing reducibility and compensating for the drastic loss of surface area.