基于钾盐修饰Fe基载氧体的化学链燃烧研究

采用典型的钾盐和惰性载体对Fe基载氧体进行修饰，在热重和小型流化床反应器上，采用CO/N2对其还原活性和化学链燃烧特性进行测试，考察了钾盐种类、反应温度对和惰性载体种类的影响。结果表明：钾盐修饰（KCl、K2SO4和K2CO3）能提高载氧体还原反应速率，并以K2CO3效果最好，最大还原反应速率提高约30%，载氧体完全还原时间由50 min缩短到25 min，主要归因于K2CO3修饰促进形成高活性的Fe-K-O化合物及发达的孔隙结构；对于K2CO3修饰Fe基载氧体，SiO2和高岭土载体易与K2CO3发生烧结，造成活性下降，TiO2与载氧体反应生成复杂的化合物，其氧化过程变慢，影响整个进程，而Al2O3载体展现了最好的反应活性，随着反应循环的增加其活性略有下降并趋于稳定，9个循环后CO2捕集效率高达98.0%

Experiment investigation of chemical looping combustion using Fe-based oxygen carrier decorated with potassium salt

Fe-based oxygen carriers were modified with typical potassium salts and inert supports. The reduction activity and the chemical looping combustion were tested in a TGA and small fluidized bed reactor using CO/N2. The effects of the potassium salts, reaction temperature and inert supports were investigated. The results indicate that potassium salt decoration using KCl, K2SO4 and K2CO3 can enhance the reduction rate of oxygen carrier rt. K2CO3 exhibits the best performance with the maximum rt increase by about 30%, and the complete reduction of oxygen carrier is shortened from 50.0 to 25.0 min. It is mainly attributed to the formation of highly active Fe-K-O compounds and the developed pore structure promoted by K2CO3 modification. For the K2CO3 decorated Fe-based oxygen carrier, the supports of SiO2 and kaolin interact with K2CO3 to cause particle sintering, resulting in decreased activity of oxygen carrier. The reaction between TiO2 and oxygen carrier produces complex compounds causing the oxidation process to slow down affecting the whole process. Instead, Al2O3 support i.e., KFeAl oxygen carrier exhibits the best reaction activity. The reactivity of KFeAl decreases slightly with increasing of reaction cycle, and then tends to be stable. The CO2 capture efficiency is as high as 98% after 9 cycles.