适用于流化催化裂化贫氧再生烟气的高效脱硫剂

为改善硫转移剂在贫氧条件下的脱硫效果，采用硝酸铝、柠檬酸、活性炭等添加剂对氧化铈进行改性，通过XRD、热重和微反等手段对改性前后氧化铈结构和脱硫活性的变化进行分析。结果表明：每种添加剂的引入都在定程度上降低了氧化铈的晶粒粒径，经多种添加剂复合改性后，氧化铈的晶粒从28 nm降到6.5 nm；调节硝酸铝添加剂用量，随着铝含量的增加，氧化铈的颗粒粒径不断降低，当铈铝比为3/7时，颗粒粒径为4.3 nm，而储氧量则先增加后降低；硫转移剂的脱硫活性与氧化铈的含量、储氧量、颗粒粒径密切相关；改性后硫转移剂的贫氧脱硫活性明显高于未改性样品，在铈铝比为7/3时，硫转移剂的贫氧脱硫活性达到最优，饱和硫容时间是未改性样品的1.4倍。
In this study, the aluminum nitrate, citric acid and activated carbon were employed as promotors for cerium oxide to improve its desulfurization activity in oxygen-lean FCC flue gas condition. The physico-chemical properties of cerium oxide catalysts before and after promotion treatments were characterized by XRD, thermogravimetry analysis and micro-reaction technique. The results show that the particle size of catalysts is always decreased after the modifications with one or more additives, the latter of which is more effective and results in a significantly reduction of particle size from 28 to 6.5 nm. Further study indicates that the particle sizes of samples decrease with the increase in the additive amount of aluminium nitrate. The particle size is 4.3 nm, when Ce/Al ratio is 3/7. And the capacity of oxygen storage increased first and then decreased. It is also found that the desulfurization activity of catalysts strongly depends on the content of Ce2O3, capacity of oxygen storage, and particle size. And the desulfurization activity of the modified sulfur transfer agent is much higher than that of the unmodified one. When the Ce/Al ratio is 7/3, the maximum desulfurization activity can be reached, which is about 1.4 times than that of unmodified sample