Flame-made durable doped-CaO nanosorbents for CO capture

The present study deals with the design and development of novel calcium-oxide-based refractory sorbents synthesized by flame spray pyrolysis (FSP) for carbon dioxide capture. The FSP-derived sorbents inherently exhibit very large CO ₂ uptake capacity in the present investigation. Sorbents derived from conventional wet chemistry, possessing identical composition, were synthesized and evaluated. A wide range of refractory dopants (Si, Ti, Cr, Co, Zr, and Ce) were employed, aiming at developing sorbents with good mechanical strength. Among all of the doped CaO sorbents, Zr-doped CaO was found to exhibit the best CO ₂-capture performance under identical conditions of operation. To study the effect of Zr in depth and find out the optimal concentration of Zr needed in the CaO matrix, a series of Zr-incorporated CaO sorbents were synthesized by varying the relative composition of Zr in the CaO base matrix. The present studies suggest that Zr/Ca in the 3:10 atomic ratio results in the formation of the most robust nanosorbent for multicyclic operation. This sorbent retained, unchanged, its ability to capture CO ₂ during extended cycles. It also demonstrated excellent stability under operating in the presence of water vapor (10 vol %). The present paper represents two novel developments in the field of CO ₂ capture, first, the superiority of FSP process and, second, the role of ZrO ₂ dopant in improving the durability and robustness of the CaO-based sorbent.