商用V/W/Ti系脱硝催化剂表面SO_(3)生成的反应机理

Generation mechanism of SO_(2) on the surface of commercial V/W/Ti DeNO_(x) catalysts

基于燃煤烟气SO_(3)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SO_(3)生成反应动力学及反应机理.结果表明,反应温度与SO_(2)浓度是影响催化剂表面SO_(3)生成的关键因素.在SO_(2)浓度为400×10^(-6)时,当反应温度从300℃升至360℃,SO_(2)-SO_(3)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,SO_(2)-SO_(3)转化率从0.65%增2.3%,SO_(3)生成反应的表观速率常数增加近3倍.SO_(3)在催化剂表面的生成路径为:SO_(2)与V_(5)+-OH反应生成中间产物VOSO_(4)与HSO_(4)^(-),随后进一步反应生成SO_(3).SO_(2)主要通过其在催化剂表面的吸附、转化过程影响SO_(3)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,SO_(3)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.

Based on the serious impact of SO_(3) generation and emission in coal-fired flue gas on the operation of power plants and the atmospheric environment,the SO_(3) 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 SO_(2) were the key factors affecting the generation of SO_(3) on the catalyst surface.SO_(2)-SO_(3) conversion rate increased from 0.2%to 0.65%when the reaction temperature increased from 300℃to 360℃under 400×10^(-6) SO_(2) condition.After the reaction temperature reached to 400℃,the catalytic activity of V2O5 in catalyst surface increased more significantly,the SO_(2)-SO_(3) conversion rate increased to 2.3%,and the apparent rate constant of SO_(3) generation reaction also increased significantly by nearly 3times.The generation path of SO_(3) on the catalyst surface is:SO_(2) reacted with V_(5)^(+)-OH to generate intermediate products VOSO4 and HSO^(4)^(-),and then further reacted to generate SO_(3).SO_(2) mainly affected SO_(3) 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 SO_(3) could be carried out without O2.The presence of O2 could promote SO_(3) generation reaction,but did not change SO_(3) generation path.