稀土氧化物上SO_2和NO的催化还原 Ⅰ.催化剂的活化特性和机理

Catalytic Reduction of SO_2 and NO over Rare Earth Oxides Ⅰ. Activation Behaviors and Mechanism of Catalysts

以稀土系列氧化物作为CO还原SO2 和NO的催化剂 ,考察了催化剂的活化过程以及催化剂体相结构的变化 .发现稀土系列氧化物的活化与其水合性能密切相关 ,而活化之后活性相为相应的稀土氧硫化物 .

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.