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 degrees C/10 h) of cerium zirconium solid solution has the highest specific surface area of 23.01 m(2)/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 degrees C. Therefore, increasing ammonia concentration in the hydrothermal treatment is beneficial to the thermal stability and redox performance of cerium zirconium solid solution. (C) 2020 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.

Automated summary

In this study, cerium zirconium solid solution was prepared by a coprecipitation-hydrothermal method, and it was found that the sample with an ammonia concentration of 0.8 mol/L had the highest specific surface area, while the sample with an ammonia concentration of 0.4 mol/L exhibited the best redox activity and the lowest reduction temperature. Increasing the ammonia concentration in the hydrothermal treatment was shown to be beneficial for the thermal stability and redox performance of cerium zirconium solid solution.