In-Situ Capture of Mercury in Coal-Fired Power Plants Using High Surface Energy Fly Ash.

Abstract

Coal-fired power plants represent the largest source of mercury emissions worldwide. Using fly ash, a byproduct of these plants, as a sorbent to remove mercury has proven to be difficult. Here, we found that the fresh surface of modified fly ash has good adsorption performance, and it declines obviously with time because of unsaturation characteristics on surface. On the basis of this mechanism, our study provides a method to in situ capture mercury with high surface energy modified fly ash by mechanochemical and bromide treatment. Fresh modified fly ash with active sites is injected into the flue to directly adsorb mercury. A continuous system within a full-scale 300 MWe plant showed that the mercury adsorption performance of the modified fly ash is similar to that of activated carbon, which is the industry benchmark for the treatment of mercury emission in fossil power generation units. This is a breakthrough and indicates that modified fly ash can become an efficient and convenient industrial sorbent for the removal of mercury.