Mercury Removal from Flue Gases by Novel Regenerable Magnetic Nanocomposite Sorbents

Abstract

Magnetic zeolite composites with supported silver nanoparicles are a new class of multifunctional materials with potential applications as recyclable catalysts, disinfectants, and sorbents. This study evaluated the suitability of the magnetic composites as sorbents for the removal of elemental mercury vapor from flue gases of coal-fired power plants. The sorbents were found to completely capture mercury at temperatures up to 200 degrees C, and the mercury capacity of the sorbents was found to be affected by the state, content, and size of the silver particles in the composite. Cumulative or extended thermal treatments at 400 degrees C were found to improve the mercury capture capacity, allowing the sorbent to be regenerated and recycled multiple times without performance degradation. The magnetic sorbent was readily separated from fly ash by magnetic separation, leaving the fly ash essentially free of sorbent contamination. In initial in-plant tests, the sorbents were able to capture mercury from the flue gases of an operational, full-scale, coal-fired power plant The combination of mercury capacity, ease of separation and regeneration, and recyclability makes these multifunctional magnetic composites excellent candidate sorbentsforthe control of mercury emissions from coal-fired power plants.

Experimental study of mercury removal from exhaust gases

“…4.9 wt % of mercury was adsorbed). These findings indicate that it is possible that different gas than nitrogen is needed to regenerate silver impregnated zeolite, what seems to be supported by the other work -Dong et al [37] reported regeneration in argon, while Weekman et al -in methane [38]. Future work will aim to fully investigate zeolites regeneration potential along with the impact of gasification and combustion flue gas components on the sorbents mercury adsorption and its thermal stability.…”

Process migration and transformation of mercury in simulated wet flue gas desulfurization slurry system

“…However, higher operating costs and negative effects on fly ash quality limited its wide application. Thus, great efforts have been devoted to develop cost-effective and ultrafine sorbents with highly effective sorption capacities and rapid reaction kinetics [8,9]. Considering the attractive economical factors, wet flue gas desulfurization (WFGD), a selective technology for sulfur dioxide (SO 2 ) removal adopted by US coal-fired power plants was recommended for removal of Hg [7].…”

Zeolites and Other Structurally Microporous Solids as Acid–Base Materials

“…51 In this case the catalyst is prepared using a magnetic zeolite, i.e. a natural chabazite containing also erionite and clinoptilolite, treated with magnetite to make it Schematics of the mercury removal and drying section in natural gas plant, with mercury recovery from the regeneration gas.…”