燃煤烟气中零价汞的催化氧化理论研究进展

摘要

汞是燃煤锅炉烟气重金属污染元素之一,主要存在形态为零价汞(Hg0)、氧化态汞(Hg2+)和颗粒态汞(Hg.),其中Hg0难以去除,通常需将其氧化为较易脱除的Hg2+后再脱除;催化剂可以促进Hg0的氧化,按照催化剂来源与功能的不同,将其分为3类,即燃煤飞灰、常规Hg0氧化催化剂及联合脱硝脱汞催化剂,综述了Hg0在不同催化剂作用下发生氧化反应的密度泛函理论(DFT)研究现状;对各种催化剂表面Hg0的吸附以及氧化反应机理进行了总结并比较了一些相近研究的内容与结果;指出了现有研究的不足,提出了Hg0氧化剂DFT理论计算研究今后的发展趋势.%Mercury is one of the heavy metal element pollution in the flue gas of coal-fired power generation,with elemental mercury (Hg0),oxidized mercury (Hg2+) and particulate mercury (HgP) as its main existing forms.Since Hg0 is difficult to be removed,it is usually oxidized to Hg2+,which can be removed easily with the help of catalysts.Hg0 oxidation catalyst can be divided into three major types according to their different sources and functions,i.e.,coal-fired fly ash,conventional Hg0 oxidation catalyst,and cooperative de-NOx and Hg-removal catalyst.In this paper,the present status of the density functional theory (DFT) study of oxidation reaction of Hg0 under different catalysts is reviewed.Then the mechanisms of adsorption and oxidation reaction of Hg0 on various catalysts are summarized and the contents and results of some similar studies are compared.In addition,the deficiency of the current research is pointed out and the future development trend of DFT calculation study of Hg0 oxidation catalyst is put forward.