Abstract:

The traditional Na-based sorbent solid adsorbents have the bottleneck problem of large grain size, high gas diffusion resistance, and limited load, which leads to low CO₂ adsorption capability. A new adsorbent preparation method based on fluidized bed spray impregnation technology has been created. γ-Al₂O₃ was used as the support, and high-purity Na₂CO₃ was selected as the active component. The solution impregnation method and fluidized bed spray impregnation method were used to prepare several groups of adsorbents with different carrier structure and active component loading. Based on a fixed bed experimental setup combined with BET, XRD, SEM, XRF and other methods, the CO₂ adsorption capability of the adsorbents, as well as key parameters such as pore structure, crystal form, surface morphology, and loading capacity, were characterized. The results showed that the saturated adsorption capability and adsorption activity of the adsorbent prepared by the spray impregnation method were better than those of the traditional impregnation method under the same loading capacity of active components, because this method can control the loading depth of active components on the support. Meanwhile, the active components were mostly crystallized in needle or rod-shaped forms that were conducive to the reaction. The crystal size was generally 10%—20% smaller than that of traditional solution impregnation methods. Nevertheless, the pore structure of the carrier, such as specific surface area and pore size distribution, will still limit the reaction of the adsorbent prepared by the fluidized bed spray impregnation technology.

Key words: CO₂ capture, adsorbents, sodium carbonate, dry impregnation, fluidized-bed

摘要：

针对传统钠基CO₂固体吸附剂晶粒尺寸大、气体扩散阻力高、负载量有限导致的吸附量低的瓶颈问题，提出了基于流化床喷雾浸渍技术的吸附剂制备新方法。选取γ-Al₂O₃为载体，高纯度Na₂CO₃作为活性组分，利用溶液浸渍法和流化床喷雾浸渍法分别制备了载体结构、活性组分负载量不同的多组吸附剂，并基于固定床实验装置结合比表面积和孔隙度分析仪、X射线衍射仪、扫描电子显微镜、X射线荧光光谱分析等手段对吸附剂的CO₂吸附性能以及孔隙结构、晶型、表面形态及负载量等关键参数进行表征。研究结果表明，相同活性组分负载量下，采用喷雾浸渍法制备的吸附剂的饱和吸附量和吸附活性皆优于传统浸渍法，其原因在于该方法可以控制活性组分在载体上的负载深度；同时，活性组分多为针状或棒状等利于反应的形态结晶；晶体尺寸较传统溶液浸渍法普遍小10%~20%。尽管如此，载体的孔隙结构，具体如比表面积和孔径分布等参数仍会限制流化床喷雾浸渍技术制备的吸附剂的反应性能。

关键词: 二氧化碳捕集, 吸附剂, 碳酸钠, 喷雾浸渍, 流化床