Decomposition and Reactivity of NH4HSO4 on V2O5/AC Catalysts Used for NO Reduction with Ammonia
Decomposition and Reactivity of NH4HSO4 on V2O5/AC Catalysts Used for NO Reduction with Ammonia
复制标题
DOI：
10.1006/jcat.2000.2961
复制
发表时间：
2000-10
影响因子：
7.3
通讯作者：
Zhenping Zhu;H. Niu;Zhenyu Liu;Shou‐Heng Liu
中科院分区：
文献类型：
--
作者：
Zhenping Zhu;H. Niu;Zhenyu Liu;Shou‐Heng Liu
摘要：采用程序升温法，详细研究了不同v2o /AC和v2o / tio2催化剂上沉积或原位生成的nh4 hso4的分解和反应性。结果与催化剂在so2存在下nh3还原NO的行为直接相关。h2so4在h2o2 /AC催化剂上比在h2o2 / tio2催化剂上更容易分解和反应。在v2o5 /AC催化剂上，nh4 - hso4的分解和反应活性很大程度上取决于v2o5的负载，分解温度随v2o5负载的增加而增加，反应速率随v2o5负载的增加而增加。当钒负载低于5 wt%时，大部分沉积在钒/活性炭上的nh4hso4能在250℃下与NO反应。nh4 hso4与NO的反应活性，除了分解外，与so2存在下SCR反应催化剂的行为有关。在so2存在下，在低v2o5负载量的v2o5 /AC催化剂上进行SCR反应时，形成的硫酸盐种停留在催化剂表面，作为吸附nh3的酸位。同时，铵离子与NO持续反应，避免过量硫酸铵盐在表面沉积。这一过程有效地保证了催化剂被促进而不被so2毒害。AC和钒之间的相互作用导致了与硫酸盐相连的铵离子的活化和反应的协同作用。提出并讨论了一种桥式活性氨。
Abstract The decomposition and reactivity of NH 4 HSO 4 deposited or in situ formed on various V 2 O 5 /AC and V 2 O 5 /TiO 2 catalysts are studied in detail using a temperature-programmed method. The results are correlated directly with the behavior of the catalysts in the NO reduction with NH 3 in the presence of SO 2 . The decomposition and reaction of NH 4 HSO 4 are easier on the V 2 O 5 /AC catalysts than on the V 2 O 5 /TiO 2 catalysts. On the V 2 O 5 /AC catalysts, the decomposition and reactivity of NH 4 HSO 4 are greatly dependent upon V 2 O 5 loading, the temperatures for the decomposition, and reaction increase with increasing V 2 O 5 loading. Most of the NH 4 HSO 4 deposited on the V 2 O 5 /AC can react with NO at 250°C when V 2 O 5 loading is below 5 wt%. The reactivity of NH 4 HSO 4 with NO, other than its decomposition, is associated with the behavior of the catalysts for the SCR reaction in the presence of SO 2 . During the SCR reaction on the V 2 O 5 /AC catalysts of low V 2 O 5 loading in the presence of SO 2 , the formed sulfate species stay on the catalyst surface and act as acid sites for NH 3 adsorption. Simultaneously, the ammonium ions react continuously with NO to avoid the surface deposition of excess ammonium–sulfate salts. Such a process effectively ensures the catalyst being promoted but not poisoned by SO 2 . The interaction between the AC and vanadium species results in synergism in the activation and reaction of ammonium ions linked to sulfate species. A bridge-type activated ammonia species is proposed and discussed.