Abstract: High purity cerium hydroxideCe(OH)₄ was prepared in weakly acidic medium (pH at 5~6) with cerium nitrate as raw material,H₂O₂ as oxidant,and NH₃•H₂O as neutralizer.Influences of factors,such as amount-of-substance ratio of H₂O₂ to NH₃•H₂O,decomposition temperature,and time of decomposition with heat preservation on nitric acid solubility and oxidation rate of the product were studied.Meanwhile,the impact of the changing of pH after precipitated totally on MgO impurity of the product was also analyzed.Optimized conditions were obtained:n(H₂O₂)/n(NH₃•H₂O)=1.20~1.25;decomposition temperature was higher than 92 ℃;decomposition time with heat preservation was more than 40 min;and pH was at 8.5~9.0 after precipitated totally.Qualified high purity Ce(OH)₄ products can archeive 99.98% with this method. 

Key words: Ce(OH)₄, weakly acidic medium, H₂O₂, decomposition temperatures