铈掺杂对钒催化剂催化氧化SO_(2)性能的促进机理研究

Study on the promoting mechanism of cerium on catalytic oxidation of SO_(2)over vanadium catalyst

采用超声浸渍法制备了氧化铈掺杂前后的V/SiO_(2)和x%Ce-V/SiO_(2)催化剂,利用BET和XRD对催化剂的物化性质进行表征,结合原位Raman技术探究CeO_(2)对钒催化剂实际催化过程的影响,并测定了两组催化剂的SO_(2)氧化转化率。结果表明,4%氧化铈掺杂时钒催化剂的孔径分布得到改善,同时有利于促进活性物质(V^(Ⅴ)O)_(2)O(SO_(4))_(4)^(4-)的生成,并提高五价钒的价态稳定性,避免熔融相中活性物种的损失,4%Ce-V/SiO_(2)催化剂在450℃和425℃的SO_(2)转化率分别比V/SiO_(2)催化剂提升了11.7%和30.1%,且在500~450℃的温度范围内维持着高于90%的转化率。

The vanadium catalysts V/SiO_(2)and x%Ce-V/SiO_(2)catalysts were prepared by ultrasonic impregnation method,and characterized by BET and XRD,and investigated the effect of CeO_(2)on the actual catalytic process of vanadium catalyst through in situ Raman technology.The catalytic activity of SO_(2)to SO_(3)were investigated.Results indicated that the introduction of cerium oxide optimizes the pore size distribution of vanadium catalyst,promotes the formation of active substance(V^(Ⅴ)O)_(2)O(SO_(4))_(4)^(4-),and improves the valence stability of VⅤspecies,thus avoiding the loss of active species from the molten phase.The 4%Ce-V/SiO_(2)catalyst improves the SO_(2)conversion by 11.7%and 30.1%at 450℃and 425℃,respectively,compared with V/SiO_(2)catalyst.And it also maintains the SO_(2)conversion higher than 90%in the temperature range of 500~450℃.