Calcium Looping Technology Using Improved Stability Nanostructured Sorbent for Cyclic CO₂ Capture

One of the post-combustion CO₂ capture technologies that have sufficiently been proved to be the best candidates for practical large scale post-combustion application is the calcium looping cycle. However, the CO₂ capture capacity of a calcium-based sorbent derived from natural limestone decays through long-term cyclic utilization; thus, the development of novel sorbents to achieve a high CO₂ capture capacity is an critical challenge for the calcium looping cycle technology. In this paper, we report the preparation and character of a new calcium-based sorbent produced via the combustion of a dry gel. The results show that the novel calcium-based sorbent has a much higher residual carbonation conversion as well as a better performance of anti-sintering when compared with the calcium-based sorbent derived from commercial micrometer grade CaCO₃ and nanometer grade CaCO₃. It is reasonable to propose that the different final carbonation performances are induced by their different pore structures and BET surface areas rather than by different particle sizes. Compared with the commercial nano CaO, the morphology of the new sorbent shows a more rough porous appearance with hollow nanostructure. During carbonation, CO₂ diffused more easily through the hollow structure than through a solid structure to reach the unreacted CaO. Besides, there is less chance for the hollow nanostructured particles to be merged together during the high temperature reactions.