Cost-effective sulfurized sorbents derived from one-step pyrolysis of wood and scrap tire for elemental mercury removal from flue gas

摘要

Sulfurized chars derived from one-step pyrolysis of wood and scrap tire are developed as cost-effective sorbents for elemental mercury (Hg-0) capture from flue gas. This method can modify chars and enhance their Hg-0 capture capability during samples preparation without additional modification. The sample characterization implies that a synergistic effect between wood and tire occurs during co-pyrolysis. For this reason, the BET surface area and pore volume of sulfurized chars have exceeded the weighted-average sum of biochar and tire-char. The existence forms of sulfur in sulfurized chars are sulfide, organic sulfur (sulfoxide, aliphatic sulfur, and thiophenic)/elemental sulfur and sulfate. At the optimum temperature (140 degrees C), the sulfurized chars present much higher Hg-0 capture capability compared to biochar and tire-char. The best pyrolysis temperature for preparing sulfurized sorbents is 800 degrees C, and the optimum wood/tire blending ratio is 50%:50%. The presence of SO2, NO, O-2, and HCl can promote mercury capture. The mechanisms responsible for Hg-0 removal are investigated by XPS and Hg-TPD analysis. The results demonstrate that chemisorption dominates the Hg-0 removal process, where organic sulfur/elemental sulfur can serve as active components for Hg-0 oxidization into HgS.