A review on granulation of CaO-based sorbent for carbon dioxide capture

• Five granulation methods of CaO-based sorbent were summarized. • Effects of granulation methods on performances were analyzed. • Influences of critical factors during granulation were reviewed. • Cyclic performances of pellets under distinct conditions were discussed. • Potential future research trends were recommended in this work. This review summarized the principles and processes of different granulation methods and analyzed the effects on the mechanical and CO 2 uptake performances. The extrusion method, extrusion-spheronization method, and casting method with the external force can compact the structure of sorbent to improve the compressive strength but decrease the initial CO 2 uptake capacity. The spheronization method and casting method without the external force only change the pellet shape to decrease unnecessary attrition without affecting the uptake performance. The performances of pellets prepared by the wrapped shell method are various primarily resulting from the structures of the shells. The pellets prepared from organic calcium precursor have larger CO 2 uptake performances but lower mechanical performances. The addition of inert binders can enhance the mechanical yet decrease the CO 2 uptake performance, however, the addition of pore-forming materials without extensive alkali elements can improve the uptake capacity but weaken mechanical performance. In addition, the increase of carbonator temperature can enhance the CO 2 uptake performance but decrease the CO 2 capture efficiency. The high calcination temperature can result in serious sintering and attrition, and the pellet with a small size owns a high carbonation rate and low attrition. Besides, the calcination at concentrated CO 2 and the presence of SO 2 during carbonation can also significantly deteriorate the cyclic uptake performance. However, the presence of water vapor during carbonation can relieve sintering. During fluidization, the large fluidization number can result in a high initial CO 2 uptake performance but enhance the attrition ratio. Besides, three prospective research aspects including enriching the research method, the systematic techno economic analysis, and the design of a continuous granulation system were suggested.