金属负载型分子筛催化剂在NH3-SCR反应中水热稳定性的研究进展

Research progress of hydrothermal stability of metal-based zeolite catalysts in NH3-SCR reaction

NOx控制是目前大气污染控制领域的重要研究内容,NH3选择性催化还原技术(NH3-SCR)是消除NOx最有效的技术之一,其核心是高性能催化剂的开发。本研究综述了金属负载型分子筛催化剂(Cu基和Fe基分子筛催化剂)的NH3-SCR活性、水热稳定性以及水热老化失活机制,并对影响催化剂水热稳定性的因素(包括Si/Al比、分子筛拓扑结构、活性金属负载量、粒径和合成方法等)进行了系统阐述,总结了一些有效提高催化剂水热稳定性的改性方法,比如磷改性、第二活性金属改性、碱金属改性和外表面改性等。最后,对进一步提高金属负载型分子筛催化剂在NH3-SCR反应中的水热稳定性进行了展望。

Emission of NOx from stationary and mobile sources had caused many environmental problems.NH3 selective catalytic reduction technology(NH3-SCR)is one of the most effective technologies to eliminate NOx based on developing high-efficient catalysts.In this review,the catalytic activity for NH3-SCR,hydrothermal stability and deactivation mechanism of metal-based zeolite catalysts(mainly Cu-and Fe-based zeolite catalysts)employed in NH3-SCR were summarized.The main factors affecting the hydrothermal stability of Cu-or Febased zeolite catalysts in NH3-SCR,such as Si/Al ratio,zeolite topological structure,metal content,particle size and preparation methods of catalysts,were systematically reviewed.The modification approaches addressed in recent researches which could effectively improve the hydrothermal stability of metal-based zeolites in NH3-SCR,such as element modification using phosphorus,second active metal,alkali(earth)metal,and surface modification,were discussed.Hopefully,this review could provide a fundamental understanding of the deactivation behaviors of Cu-and Fe-based zeolite catalysts and pave the way towards the improvement of hydrothermal stability of zeolite catalysts in NH3-SCR.