Structurally Improved, Core-in-Shell, CaO-Based Sorbent Pellets for CO2 Capture

Abstract

The pelletization of CaO-based sorbents is necessary for its practical application in the calcium looping process. In this work, three groups of composite pellets with different structures (non-shell pellets, core-in-shell pellets with inert shells, and structurally improved core-in-shell pellets with semi-reactive shells) were prepared from limestone powder and calcium aluminate cement. For the core-in-shell pellets, 2 wt % rice husks were added to the shells to enable the formation of relatively porous and strong shells. Both the CO2 uptake and mechanical strength of the cement-bound pellets were investigated to find the promising structure for the pelletization of the CaO-based sorbent. Moreover, wet curing was used for the first time, and prolonging the curing time could be effective to enhance the mechanical strength of the pellets. It was found that the core-in-shell pellets with semi-reactive shells via adding a moderate amount of limestone to the outer shell was able to largely improve the overall...