商用V/W/Ti系脱硝催化剂表面SO3生成的反应机理

基于燃煤烟气SO₃生成与排放给电厂运行及大气环境带来的严重影响，研究了一种在役典型商用蜂窝型V/W/Ti系脱硝催化剂表面的SO₃生成反应动力学及反应机理.结果表明，反应温度与SO₂浓度是影响催化剂表面SO₃生成的关键因素.在SO₂浓度为400×10^-6时，当反应温度从300℃升至360℃，SO₂-SO₃转化率从0.2%提高至0.65%，温度达到400℃后，催化剂表面V₂O₅活性增加更为显著，SO₂-SO₃转化率从0.65%增2.3%，SO₃生成反应的表观速率常数增加近3倍.SO₃在催化剂表面的生成路径为：SO₂与V⁵⁺-OH反应生成中间产物VOSO₄与HSO₄^-，随后进一步反应生成SO₃.SO₂主要通过其在催化剂表面的吸附、转化过程影响SO₃的生成，其本征动力学反应级数为0.52.O₂的本征动力学反应级数为0，SO₃生成反应可以在无O₂条件下进行，O₂存在会促进反应进行，但不会改变反应路径.

Generation mechanism of SO2 on the surface of commercial V/W/Ti DeNOx catalysts

Based on the serious impact of SO₃ generation and emission in coal-fired flue gas on the operation of power plants and the atmospheric environment, the SO₃ generation reaction kinetic and reaction mechanism in the surface of a typical commercial honeycomb V/W/Ti DeNO_x catalyst are studied. The reaction temperature and SO₂ were the key factors affecting the generation of SO₃ on the catalyst surface. SO₂-SO₃ conversion rate increased from 0.2% to 0.65% when the reaction temperature increased from 300℃ to 360℃ under 400×10^-6 SO₂ condition. After the reaction temperature reached to 400℃, the catalytic activity of V₂O₅ in catalyst surface increased more significantly, the SO₂-SO₃ conversion rate increased to 2.3%, and the apparent rate constant of SO₃ generation reaction also increased significantly by nearly 3times. The generation path of SO₃ on the catalyst surface is: SO₂ reacted with V⁵⁺-OH to generate intermediate products VOSO₄ and HSO₄^-, and then further reacted to generate SO₃. SO₂ mainly affected SO₃ generation through its adsorption and conversion on the catalyst surface, and its intrinsic kinetic reaction order is 0.52. The intrinsic kinetic reaction order of O₂ is 0, the generation reaction of SO₃ could be carried out without O₂. The presence of O₂ could promote SO₃ generation reaction, but did not change SO₃ generation path.