Synergistic additive engineering of high specific surface calcium hydroxide (Ca(OH)2) for efficient dry flue gas desulfurization at low temperature: Mechanism and industrial application study

Developing high-activity and low-cost desulfurizers is crucial for treating the steel industry low-temperature and highly volatile low-sulfur flue gas. This study proposes a simple and effective additive engineering strategy to convert traditional quicklime into Ca(OH) 2 desulfurizer with high activity via synergistic modification with triethanolamine (TEA), diethylene glycol (DEG), and sodium silicate (Na 2 SiO 3 ). The optimized Ca@TDS has a highly porous microstructure, characterized by a specific surface area as high as 42.19 m 2 /g, and pore volume reaching 0.186 cm 3 /g. It exhibited an elevated sulfur capacity at 37.97 mg/g, with breakthrough time extended to 93.8 min at 100°C, and excellent adaptability under high SO 2 concentrations and CO 2 -containing atmospheres. Comprehensive characterization and kinetic models indicated that the synergistic effect of additives enhanced pore connectivity, promoted internal diffusion, and suppressed surface carbonate deposition. This study also successfully employed 10 tons of industrial products Ind-Ca@TDS to control SO 2 emissions below the ultra-low standard of 35 mg/m 3 in the steel plant pilot test, which fully verified the scalability and industrial feasibility of the method. This work provided an expandable and cost-effective way for the production of high specific surface Ca(OH) 2 , providing practical reference for the development of dry low-temperature FGD technology in the steel industry.