Effect of Element Doping on Catalytic Activity of Precious Metal Three-way Catalysts and Deep Purification

Doped precious metal three-way catalysts were prepared by technology of impregnation-coating.The effects of doping content of Cu,Ni,Co,Pb,Sn and Bi on catalytic activity were investigated.The catalyst deactivation mechanism was preliminarily explored under doping.The effects of P204 content and saponification rate,phase ratio,pH,and extraction series on deep removal of impurity elements from precious metal solution were discussed.The results show that there is no obvious influence on catalyst activity when doping levels of Cu,Ni,Co,Pb,Sn and Bi impurity contents are below 10×10-6.The single-stage extraction rates of Cu、Co、Sn、Bi are 99%above under the conditions of pH=2.0and extraction duration of 20 min with 30%saponated P204,while content of Ni and Pb in solution can be reduced to 10×10-6 below after three-stage countercurrent extraction with extraction rate of 96.37%and 96.59%respectively.