Core-in-shell, glucose-templated, ZrO2-stabilized calcium/copper-based pellets with robust CO2 capture performance for Ca/Cu process

Calcium/copper-based pellets are crucial to the advancement of the Ca/Cu process, as CuO reduction provides the heat necessary for CaCO3 calcination. Yet, a significant challenge lies in preserving their CO2 capture performance, which tends to deteriorate rapidly. Thus in this study, we proposed a two-stage method to synthesize core-in-shell, glucose-templated, ZrO2-stabilized calcium/copper-based pellets that are highly efficient at capturing CO2. The designed pellets featured a core concentrated with CaO and CuO, surrounded by an outer shell of ZrO2. Initially, different particle size ranges of unstabilized calcium/copper-based pellets were fabricated, including 200-470, 210-600, 400-890, and 800-1090 mu m. A minor improvement in CO2 capture performance was observed with decreasing particle sizes, ranging from 0.16 to 0.20 gCO2/gmaterial. However, a noticeable decline in CO2 capture performance was observed in these unstabilized calcium/copper-based pellets during cycling. To address this issue, these pellets were then coated with a ZrO2 shell. The core-in-shell, ZrO2stabilized calcium/copper-based pellets possessed much-improved CO2 sorption stability, mainly due to that the ZrO2 shell mitigated the degradation of the pore structure resulting from sintering during cycling. Finally, glucose was incorporated as a pore-forming material into the core-in-shell, ZrO2-stabilized calcium/copper-based pellets, improving the pore structure and further boosting their reactivity. The incorporation of glucose proved to be beneficial, resulting in enhanced capacity and stability for CO2 sorption for the core-in-shell, glucose-templated, ZrO2-stabilized calcium/copper-based pellets. The best-performing sample, i.e., calcium/copper-based pellets with the simultaneous coating of a ZrO2 shell and the incorporation of glucose, demonstrated a sorption capacity of 0.26 gCO2/gmaterial in the initial cycle. This capacity decreased to 0.18 gCO2/gmaterial in the tenth cycle, retaining 70 % of its initial reactivity.