Mercury Oxidation over the V2O5(WO3)/TiO2 Commercial SCR Catalyst
Mercury Oxidation over the V2O5(WO3)/TiO2 Commercial SCR Catalyst
复制标题
DOI：
10.1021/ie800363g
复制
发表时间：
2008-11-05
影响因子：
4.2
通讯作者：
Yukimura, Akinori
中科院分区：
文献类型：
--
作者：
Kamata, Hiroyuki;Ueno, Shun-ichiro;Yukimura, Akinori
考察了V2O5(WO3)/TiO2SCR工业催化剂上盐酸氧化汞的反应性能。考察了蜂窝结构的新鲜催化剂和老化催化剂在燃煤锅炉中暴露在燃煤烟气中超过71000H的情况。用X射线和扫描电子显微镜-能谱分析对老化催化剂进行了表征，以考察催化剂表面是否有积灰现象。随着盐酸浓度的增加，汞的氧化速率增加，而NH3的存在对汞的氧化速率有强烈的抑制作用。这一行为可以用1动力学模型来解释，假设HCl与NH3竞争催化剂的活性中心。随着催化剂运行时间的延长，在NH3存在下，汞的氧化速率显著降低，而NO的还原速率几乎没有变化。通过考察老化催化剂，观察到飞灰和SO2/SO3产生的沉积物在催化剂表面不断积累。沉积在催化剂表面的灰分可能会部分堵塞催化剂的活性中心，使其数量减少。催化剂表面活性中心数目的减少导致NH3在蜂窝催化剂中保持未反应状态。催化剂中残留的NH3对Hg0氧化速率的降低是由于NH3的抑制作用所致。
Mercury oxidation by hydrochloric acid over the V2O5(WO3)/TiO2 commercial SCR catalyst was investigated. Both fresh and aged catalysts with honeycomb structure, which were exposed to a coal combustion flue gas in a coal-fired boiler for over 71 000 h. were examined. The aged catalysts were characterized by X-ray and SEM-EDX analysis to examine the presence of ash deposition oil the surface. The mercury oxidation rate was enhanced by increasing HCl concentrations and inhibited strongly by the presence of NH3. This behavior could be explained by 1 kinetic model assuming that HCl competes for the catalyst active sites against NH3. As the catalyst operation time increased, the mercury oxidation rate was observed to decrease considerably in the presence of NH3 while NO reduction rate was apparently nearly unchanged. By examining aged catalysts, deposits stemming from fly ash and SO2/SO3 were observed to accumulate continuously on the catalyst surface. The ash deposited on the surface may partially block the active catalyst sites and decrease their number. The decrease of the number of active sites on the catalyst surface caused NH3 to remain unreacted in the honeycomb catalyst. The decrease of the Hg-0 oxidation rate was caused by the inhibition effect of NH3 remaining in the catalyst.