Routine Investigation of CO2 Sorption Enhancement for Extruded-Spheronized CaO-Based Pellets

摘要

For practical application in calcium looping, CaO-based sorbents need to be pelletized. However, the pelleting process, particularly the extrusion process, will lead to the loss of specific surface area, hence weakening CO2 sorption performance of sorbent pellets. In previous studies, only limited modification methods were developed for CO2 sorption performance enhancements of sorbent pellet, and the effects of modification are not satisfactory. In this work, the enhancement of CO2 sorption performance of extruded-spheronized pellets was achieved by incorporating the MgO support into CaO-based pellets. Three routines of pellet preparation were studied including soaking (routine I), mechanical mixing (routine II), and simultaneous hydration-incorporation (routine III). It was found that the sorbent pellets produced via routine III possess the best cyclic sorption performance because of the generation of additional pores within the pellets upon the release of CO2 derived from the decomposition of magnesium acetate. In addition, the content of incorporated MgO significantly affects the cyclic CO2 capture performance of sorbent pellets. The pellets introduced to 25 wt % MgO display the highest conversion of 66.39%, which is approximately 1.52 times that of the pellets introduced to 5 wt % MgO. Moreover, the MgO-incorporated pellets prepared via extrusion-spheronization possess a high capability to resist attrition.