The Fe–Mn–Ce/CP catalyst prepared by the incipient-wetness impregnation method was investigated for elemental mercury (Hg 0 ) removal in simulated coal-fired flue gas . The incorporation of Fe could remarkably enhance the SO 2 -resistance of Fe–Mn–Ce/CP catalyst at low temperature, and the existence of water vapor had negative impact on Hg 0 removal efficiency. More than 95% of Hg 0 could be removed at 100 °C under the conditions of 60 ppm HCl, 3% O 2 ( v/v ), 5% H 2 O ( v/v ) and 400 ppm SO 2 . Hg-TPD results indicated that Hg 0 adsorption amount decreased after the addition of H 2 O or SO 2 . The XPS results revealed that the incorporation of Fe could enhance the contents of high valence Mn x + (i.e., Mn 3+ /Mn 4+ ) and Ce 3+ species in the composite catalysts, which are favorable for the oxidation process of elemental mercury. The surface characteristics were not the primary factor determining the catalytic activity . Overall, the catalytic performance of the Fe–Mn–Ce/CP catalyst was closely related to the Fe 3+ state, high ratios of (Mn 4+ + Mn 3+ )/Mn 2+ and high content of not fully coordinated cerium species.
A key challenge in elemental mercury (Hg 0 ) decontamination from flue gas lies in the design of a sorbent with abundant reactive adsorption sites that exhibit high affinity toward Hg 0 to simultaneously achieve rapid capture and large capacity. Herein, zeolitic imidazolate framework-8 (ZIF-8) supported copper selenide (CuSe) nanocomposites are synthesized by a newly designed two-step surfactant-assisted method. The as-prepared CuSe/ZIF-8 with CuSe to ZIF-8 mass ratio of 80% (0.8NC-ZIF) exhibits unparalleled performance toward Hg 0 adsorption with equilibrium capacity and average rate reaching 309.8 mg g −1 and 105.3 µg g −1 min −1 , respectively, surpassing all reported metal sulfides and traditional activated-carbon-based sorbents. The impressive performance of 0.8NC-ZIF for Hg 0 immobilization is primarily attributed to the adequate exposure of the Se-terminated sites with high affinity toward Hg 0 resulted from the layered structure of CuSe. The adsorbed mercury selenide exhibits even higher stability than the most stable natural mercury ore—that is, mercury sulfide—hence minimizing its environmental impact when the CuSe/ZIF-8 sorbent is dumped. This work provides a new mindset for future design of sorbents for efficient Hg 0 capture from industrial flue gas. The results also justify the candidature of CuSe/ZIF to be applicable for mercury pollution remediation in real-world conditions.
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