烟气单质汞催化氧化技术研究进展

Research progress on catalytic oxidation technologies of gaseouselemental mercury in flue gases

本文综述了近年来单质汞(Hg^(0))催化氧化技术的研究进展,重点介绍了钒基催化剂、贵金属催化剂、过渡金属氧化物催化剂三类Hg^(0)氧化催化剂的研究现状。钒基催化剂汞氧化效率与烟气中HCl和Cl_(2)浓度密切相关;以Au、Ag、Pt、Ru、Pd等元素作为核心活性位点的贵金属催化剂由于其对汞原子的选择性强亲和力,是具有应用前景的Hg^(0)氧化催化剂;过渡金属氧化物(Cu、Mn、Fe、Mo、Ag、Pd、Cr等)表现出较好的中低温Hg^(0)氧化催化剂能力。大多数催化剂在一定温度下均具有很高的Hg^(0)氧化效率,但烟气中的NH_(3)和SO_(2)严重抑制了催化剂活性,分别从94.7%±3.9%和83.9%±4.8%降至66.8%±16.8%和57.1%±7.5%。在复杂的烟气条件下,单一氧化位点的金属氧化物不适合作为Hg^(0)氧化催化剂,采用多组分金属氧化物耦合建立多活性反应区域,有效分析烟气中的SO_(2)、NO、NH_(3)和Hg^(0)吸附反应区域,是设计构建NO、Hg^(0)等多污染物协同控制催化剂的关键。本文同时讨论了高效Hg^(0)氧化催化剂未来面临的挑战。

Mercury catalytic oxidation technologies in recent studies are summarized in this study to highlight the present research development and future perspective of catalysts.The mercury oxidation catalysts are classified into V-based catalyst,noble metal catalyst and transition metal oxides catalyst.The mercury oxidation efficiency(MOE)of V-based catalyst strongly depends on HCl and Cl_(2)concentrations in the flue gas.The noble metal catalyst(e.g.,Au,Ag,Pt,Ru and Pd-based)is a promising mercury oxidation catalyst because of its strong affinity toward mercury atom.The transition metal oxides(Cu,Mn,Fe,Mo,Ag,Pd,Cr,etc.)has also been used to develop low and middle temperature catalysts for Hg^(0)oxidation.Most of these catalysts have very high mercury oxidation efficiencies at a certain temperature,but NH_(3)and SO_(2)in the flue gas seriously suppress the catalyst activity from 94.7%±3.9%and 83.9%±4.8%to 66.8%±16.8%and 57.1%±7.5%,respectively.It is concluded that pure metal oxides serving as single oxidation site would not be suitable mercury oxidation catalysts in the complex flue gas environment.The multicomponent metallic oxide catalysts generate more species oxidation reaction sites for NO reduction and Hg^(0),which promotes the possibility of NO and Hg^(0)synergic removal.This work also proposes the future challenge of highly efficient Hg^(0)oxidation catalyst.