Effect of flue gas components on Hgsup0/sup oxidation and adsorption by modified walnut shell coke in Osub2/sub/COsub2/sub atmosphere

摘要

titleAbstract/titlepWalnut shell was pyrolyzed and then impregnated with NHsub4/subBr to make sorbent for Hgsup0/sup removal. The effect of flue gas components on Hgsup0/sup removal performance was studied in Osub2/sub/COsub2/sub atmosphere, and the results were compared with those in Osub2/sub/Nsub2/sub atmosphere. The mercury valence distribution during adsorption was obtained. NHsub4/subBr‐modified walnut shell coke promoted Hgsup0/sup removal, the Br‐containing chemisorption site was a crucial factor. Although addition of COsub2/sub did not introduce new oxygen‐containing functional groups or change the mercury species, Hgsup0/sup removal efficiency increased significantly. This may be because COsub2/sub can increase the active sites on the carbon surface. In Osub2/sub/Nsub2/sub atmosphere, Osub2/sub promoted formation of active center on the sorbent surface, which made Hgsup0/sup more easily adsorbed and then reacted with Br‐functional group to form more HgBrsub2/sub. In Osub2/sub/COsub2/sub atmosphere, Osub2/sub promoted formation of some reactive carbon–oxygen complexes which acted as catalyst to facilitate Hgsup0/sup oxidation and formation of HgO. NO improved removal of Hgsup0/sup, because the C─O functional group on the sorbent surface could catalyze the conversion of NO to NOsub2/sub in the adsorbed state and then formed Hgsub2/sub(NOsub3/sub)sub2/sub. SOsub2/sub consumed oxygen on the sorbent surface and inhibited the Hgsup0/sup removal./p