Inert stabilizer enhanced CaO sorbents for CO2 capture: Insights through impregnated layer solution combustion synthesis

Abstract

Calcium Looping (CaL) holds great promise for high-temperature CO₂ capture in the post-combustion phase. In this work, impregnated layer solution combustion (ILSC) was employed to synthesize the highly efficient Al-stabilized CaO-based CO₂ sorbents. A comparative investigation was conducted on the dry and wet ILSC modes with discarded cigarette butts as the impregnated layer. The research delved into the impact of precursor solution concentration on the micromorphology, porosity, and CO₂ capture capacity of the synthesized Al-stabilized CaO-based sorbent, shedding light on the associated mechanisms. Research reveals that CaO-based sorbents made via the ILSC process with lower precursor solution concentrations (i.e., liquid-to-solid ratios of 3.0 and 3.75) outperform those made with higher concentrations (i.e., liquid-to-solid ratios of 1.0 and 1.5). Notably, the sorbent produced via the wet ILSC mode with a low concentration precursor solution at a liquid-to-solid ratio of 3.0 shows remarkable cyclic CO₂ capture capabilities. It maintains a capture capacity of 0.383 g CO₂/g calcined sorbent in the 17th cycle, which is 70.8 % of its initial capacity. The dilute precursor solution is capable of sustaining the initial fibrous integrity of cigarette butts, unlike its concentrated counterpart, which destroys the fiber structure. This solution also enhances the uniform dispersion of Ca and Al and suppresses the high-temperature agglomeration of CaO grains.