Fe-Exchanged Zeolites for Selective Catalytic Reduction of Nitric Oxide with Ammonia

本提案的目的是探索铁交换沸石作为氮氧化物（NOx）物种的选择性催化还原（SCR）催化剂的有效性。 在初步工作中，PI已经发现包括ZSM-5在内的几种沸石比目前在许多固定SCR系统中使用的商业氧化钒催化剂活性高得多。 此外，这些新催化剂更能抵抗硫氧化物和水的失活。 采用四种不同的方法制备了一系列铁交换沸石：常规溶液离子交换法、改进的水溶液离子交换法、化学气相沉积法和固态离子交换法。 具有小孔和低Si/Al比的沸石被认为是最有效的，并将用于该项目。 稀土阳离子和氧化物将作为促进剂进行研究。 催化剂将通过中子活化分析和其他表面分析技术来表征。 稳态动力学和NO还原的机制将与氨氧化平行研究。 燃烧产生的氮氧化物仍然是空气污染的主要来源。 本研究将为氨在铁分子筛上还原NO的催化反应机理提供基础性的认识，从而开发出性能优良的上级SCR催化剂。

The objective of this proposal is to explore the effectiveness of iron-exchanged zeolites as catalysts for the selective catalytic reduction (SCR) of nitrogen oxide (Nox) species. In preliminary work the PI has found that several zeolites including ZSM-5 are much more active than the commercial vanadia catalysts currently used in many stationary SCR systems. Also, these new catalysts are more resistant to deactivation by sulfur oxides and water. A series of iron-exchanged zeolites will be prepared using four different methods: conventional solution ion-exchange, improved aqueous ion-exchange, chemical vapor deposition, and solid-sate ion exchange. Zeolites with small pores and low Si/Al ratios were found to be most effective and will be used in this project. Rare earth cations and oxides will be studies as promoters. Catalysts will be characterized by neutron activation analysis and other surface analysis techniques. Steady-state kinetics and the mechanism for NO reduction will be studies in parallel with ammonia oxidation. Nitrogen oxides resulting from combustion remain a major source of air pollution. This study will provide a fundamental understanding of the catalytic reaction mechanism for NO reduction by ammonia on Fe-zeolites, leading to the development of superior SCR catalysts.