Kinetics of SO2 removal from flue gas by electron beam technique

Laboratory scale experiments were carried out in order to get more information about the oxidation of SO₂ by OH radicals (homogeneous reaction) and the oxidation of SO₂ at aerosol surfaces (heterogeneous reaction). For the experiment of homogeneous reaction, SO₂ was added to synthetic flue gas without initial NO and without ammonia and the mixture was irradiated with electron beam. The SO₂ removal was measured as a function of temperature and water vapour concentration at constant dose. For the experiment of heterogeneous reaction, SO₂ was added to nucleating sulfuric acid aerosol. No SO₂ removal was observed in this case. So, it can be concluded that the heterogeneous oxidation of SO₂ is negligible in the absence of ammonia. Therefore, the oxidation of SO₂ must be interpreted merely by homogeneous gas phase chemistry. The gas phase kinetics are derived from comparison of experimental results and computer modelling.     

Supported catalysts for simultaneous removal of SO2, NOx,and Hg0 from industrial exhaust gases: A review

The simultaneous removal of SO₂, NO_x and Hg⁰ from industrial exhaust flue gas has drawn worldwide attention in recent years. A particularly attractive technique is selective catalytic reduction, which effectively removes SO₂, NO_x and Hg⁰ at low temperatures. This paper first reviews the simultaneous removal of SO₂, NO_x and Hg⁰ by unsupported and supported catalysts. It then describes and compares the research progress of various carriers, eg., carbon-based materials, metal oxides, silica, molecular sieves, metal-organic frameworks, and pillared interlayered clays, in the simultaneous removal of SO₂, NO_x and Hg⁰. The effects of flue-gas components (such as O₂, NH₃, HCl, H₂O, SO₂, NO, and Hg⁰) on the removal of SO₂, NO_x, and Hg⁰ are discussed comprehensively and systematically. After summarizing the pollutant-removal mechanism, the review discusses future developments in the simultaneous removal of SO₂, NO_x and Hg⁰ by catalysts.