Chainmail-structured Ca(OH)2 encapsulated in nitrogen-doped ordered mesoporous carbon for efficient and stable SO2 capture

The development of efficient and reusable sorbents for SO 2 removal from flue gas has attracted considerable attention. Herein, we report a “chainmail” structured Ca-based SO 2 sorbent by encapsulating Ca species within ordered mesoporous carbon (OMC), denoted as Ca(OH) 2 @OMC- x , where  x  denotes the Ca(OH) 2 mass fraction (wt%). The OMC was prepared via a one-step solvent-free mechanochemical assembly: the precursors and a block copolymer template (Pluronic F127) were ground to form a preorganized composite, followed by solidothermal treatment and calcination to remove the template and carbonize the polymer. The obtained OMC was then impregnated with a Ca precursor and calcined to strengthen interfacial interactions, encapsulating the Ca species within the OMC framework. Finally, steam treatment converted the confined Ca species into finely dispersed Ca(OH) 2 active domains. The resulting Ca(OH) 2 @OMC- x exhibits a large BET surface area (169.4–290.3 m 2 /g), long-range ordered mesoporosity with a narrow pore size distribution (∼5.5 nm), and well-dispersed Ca active phases with enhanced stability. Consequently, Ca(OH) 2 @OMC- x serves as an efficient and reusable solid sorbent for SO 2 capture, exhibiting a high SO 2 adsorption capacity of 11.24 mmol/g and maintaining 98.6% of its initial capacity after five adsorption–desorption cycles. This study provides an effective “chainmail encapsulation” materials design strategy for scalable SO 2 abatement under complex flue gas conditions.