Preparation of nano-Al2O3 support CaO-based sorbent pellets by novel methods for high-temperature CO2 capture

CaO-based sorbents show great promise as materials for CO₂ capture. In this paper, three novel preparation methods were proposed to prepare three sorbent pellets based on carbide slag, respectively. The CO₂ cyclic capture performance of the sorbent pellets was also investigated. These three novel preparations consist of different binders (agar, gelatine) and different hydrophobic materials (silicone oil, liquid paraffin and silicone mold), respectively. The capture performance of these three sorbent pellets was compared with that of sorbent pellet prepared by existing preparation methods, which used agar as a binder and silicone oil as a hydrophobic material. In addition, the effects of the contents of nano-Al₂O₃ supports on the sorbent pellets were explored. Among the four preparation methods, the sorbent pellets prepared with agar as binder and silicone mold as hydrophobic material showed exhibiting the highest total capture capacity of 7.70 gCO₂/g during 15 cyclic captures. The nano-Al₂O₃ was used as support to alleviate the sintering of the sorbent pellets prepared with agar as binder and silicone mold as hydrophobic material, preserving most of the CO₂ diffusion channels. Among the sorbent pellets with varying contents of nano-Al₂O₃ support, the pellets with a 10:100 molar ratio of nano-Al₂O₃ to CaO demonstrated excellent mechanical properties and the highest CO₂ cycle capture performance. These pellets exhibited a capture capacity of 0.626 gCO₂/g on the first cycle, maintaining a capacity of 0.503 gCO₂/g by the 15th cycle. This work introduced a novel method for preparing sorbent pellets of efficient and stable cyclic capture.