Catalytic Reduction of SO_2 and NO over Rare Earth Oxides Ⅰ. Activation Behaviors and Mechanism of Catalysts
WANG Lei, MA Jianxin, LU Xiaofeng, ZONG Fang (Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai, 200237, China)
The rare earth oxide catalysts were prepared and used for the reduction of SO 2 and NO by CO. The activation course and the phase composition of catalysts before and after activation were investigated. It is found that the hydration pre treatment of the rare earth oxides has a determined effect on the activation in the reaction gas atmosphere. According to the XRD analysis, the oxides can be divided into three groups: the most easily activable oxides of La, Pr, Nd and Sm, which show a single oxysulfide phase; the mild activable oxides of Ce, Er and Ho, which show mixed phase structure of oxide and oxysulfide; and the inactive oxides of Tb and Dy, which remain their oxide phase. The ease of activation is related to the hydration properties of rare earth oxides. An activation mechanism is proposed to describe the experimental results. Active phases after activation are confirmed to be rare earth oxysulfide, RE 2O 2S.
【Fund】： 国家自然科学基金资助项目! (2 97770 0 8)