Abstract: Nanosized lithium orthosilicate sorbent has been prepared by precipitation, and its CO₂ capture performance has been evaluated. The particle size of the adsorbent is small and uniform, which leads to a significant reduction of the calcination temperature and desorption temperature, thus greatly reducing the process energy consumption. Under optimum calcination temperature, relative higher kinetic absorption capacity, i.e., 17.8% within 5 minutes under volume fraction 12.5% CO₂ model flue gas stream by absorption⁃desorption cyclic test, has been obtained. Static CO₂ absorption test at different temperatures were well fitted by the double exponential model, demonstrating the double shell mechanism. The rate⁃determining step, Li diffusion rate from the bulk to the surface, was greatly improved even in low⁃CO₂⁃concentration model flue gas owing to its nano⁃scale character. Therefore, this study has provided a simple and efficient preparation method for nanosized ceramic sorbents, which is promising for thermo⁃swing fluidized bed process.

Key words: Lithium?based sorbent, Carbon dioxide, Precipitation, Kinetic

摘要： 利用沉淀法合成纳米级高温CO₂吸附剂，并对其进行了表征和吸附性能研究。发现该吸附剂颗粒小而均匀，导致焙烧温度和脱附温度均显著降低，从而大大降低过程能耗。在低体积分数CO₂（12.5%）气氛中采用热重法进行动态循环实验，5 min后CO₂吸附容量可达17.8%。且利用双指数模型对吸附剂不同温度的静态吸附曲线进行拟合，发现纳米级吸附剂有利于体相Li向外层扩散。提供了一种简单有效的方法合成纳米吸附剂，吸附速度快，在流化床变温吸附工艺中对工业烟气的大规模捕集有潜在的应用前景。

关键词: 正硅酸锂, CO₂, 沉淀法, 动力学