The morphology of CaO-based sorbents after different CO2 looping cycles

The behavior of two limestones in CO2 looping cycles and the morphology of calcines after different cycles are presented here. The CO2 cycles were performed in tube furnaces and the resulting samples were observed by a scanning electron microscopy. The sorbents surface area, porosity and pore size distribution were tested by nitrogen adsorption/desorption. It was found that the pore distribution show two peaks in each sample. With the cycles increasing, the total pore area and volume decrease, and the large pores show a decrease in number while an increase in diameter. An unexpected result is that the small pores do not eliminate markedly as cycles and which is not consistent with existing sintering model. The Spherical prominences on particle surface were observed under SEM images and their fusion phenomenon accounts for surface area and volume decrease in CO2 cycles.