Recent developments in novel sorbents for flue gas clean up

Coal combustion is one of the most important energy sources for electricity generation, but also produces airborne pollutants. The amount of SO2 and NOx for example, is in the order of hundreds to thousands of ppm, and tens to hundreds of ppm, respectively, while Hg in flue gases could be up to tens to hundreds of ppb. Flue gas desulphurization technology is already in place for SO2 removal, and new sorbents such as zeolites are being investigated for such an application. NOx can be removed by selective catalytic reduction with various catalysts. Mercury is the hardest to remove due to its persistent nature and relatively low concentration in flue gases. New sorbents have also been developed for mercury removal applications. A current trend in flue gas emission control is to remove Hg, NOx and SO2 simultaneously. Various catalytic sorbents have been investigated to remove two or more of these pollutants concurrently. This article reviews recent developments made for emission control of coal-fired power plant flue gases using novel sorbents to target individual or multiple pollutants.