Effects of ammonia concentration in hydrothermal treatment on structure and redox properties of cerium zirconium solid solution

Cerium zirconium solid solution is a key washcoat material for automotive three-way catalysts (TWCs). However, improving the redox ability and high temperature thermal stability of cerium zirconium solid solution is still a challenge. In this paper, the cerium zirconium solid solution was prepared by a coprecipitation-hydrothermal method, and the effects of the ammonia concentration on their structures and redox properties were investigated. The results show that when the ammonia concentration is 0.8 mol/L, the aged sample (1100 °C/10 h) of cerium zirconium solid solution has the highest specific surface area of 23.01 m2/g. Additionally, the increase of ammonia concentration improves the uniformity of phase compositions and increases the oxygen vacancies. When the ammonia concentration reaches 0.4 mol/L, the cerium zirconium solid solution exhibits the best redox activity, with the lowest reduction temperature of 565 °C. Therefore, increasing ammonia concentration in the hydrothermal treatment is beneficial to the thermal stability and redox performance of cerium zirconium solid solution.