Influence of morphology, porosity and crystal structure of CaCO3 precursors on the CO2 capture performance of CaO-derived sorbents

In this study, several different CaCO3 samples both natural and synthetic, showing diverse physico-chemical characteristics (particle morphology, crystal structure and porosity) were used as precursors of CaO-based sorbents for the capture of CO2. In order to identify the most favorable CaCO3 properties for a high stability and optimal CO2 uptake by CaO-derived sorbents, both series of materials were characterized using the following analytical techniques: X-ray diffraction, N-2 adsorption and scanning electron microscopy. Moreover, the main differences in chemical composition, particle morphology and sorbent porosity of the CaO-based materials were correlated to the maximum CO2 uptake and loss-in-capacity after several carbonation/calcination cycles. The results indicate that the crystal structure of CaCO3 parent samples strongly affects the physical properties of the calcium oxide formed during the calcination step, significantly influencing the maximum CO2 uptake. The agglomeration of CaO particles after the calcination of the CaCO3 precursors controlled to a certain extent the carbonation rate. However, this factor could not be correlated with the loss of activity of the Cao-derived sorbents in tests carried out over consecutive carbonation/calcination cycles. (C) 2012 Elsevier B.V. All rights reserved.