过渡金属硫化物催化剂上NH3还原SO2的反应

采用沉淀法制备过渡金属硫化物与TiO2的复合硫氧化物催化剂样品,考察了该催化剂上NH3选择性还原SO2反应。与相应的氧化物催化剂相比,过渡金属硫化物催化剂上NH3选择性还原SO2的反应活性增高,单质硫选择性增加。催化剂的活性与其自身的氧化还原能力、硫化物的比表面积及所属结构有一定的关系。过渡金属离子的电负性与催化剂活性呈明显的“火山型”曲线,电负性适中的CoS2—TiO2催化剂的活性较高。根据以上研究提出了硫化物催化剂上NH3还原SO2的反应机理,催化剂活性来源于硫化物物相和TiO2的双组分协同作用。

THE REDUCTION OF SO2 BY NH3 ON TRANSITION METAL SULFIDE CATALYST

The complex catalyst samples of transitional metal sulfide incorporated with TiO_2 were prepared by the precipitation method. As compared with the corresponding transitional metal oxide catalysts, transitional metal sulfide catalysts greatly improved the selective reduction of SO_2 to elemental sulfur by NH_3. Catalytic activity of these catalysts were in some extent related with their redox ability, the surface area and the structure of the sulfides. The relationship of the negativity of transitional metal ions and the catalyst activity presented a "volcano" type curve. Catalysts with medium electro-negativity, like CoS_2-TiO_2 showed a maximum activity. The reduction mechanism of SO_2 by NH_3 over sulfide catalysts was postulated. The source of catalyst activity is originated from the synergism of the two composites sulfide phase and TiO_2.