Theory and practice of metal oxide catalyst design for the selective catalytic reduction of NOx with NH3

For NOx control in the presence of excess oxygen, selective catalytic reduction with ammonia (NH3-SCR) has been successfully applied in the purification of coal-fired flue gas and diesel vehicle exhaust on a large scale. For both cases, various NH3-SCR catalysts have been developed, with the incorporation of desirable catalytic properties being the central issue. However, the fundamental principle for designing NH3-SCR catalysts with high activity, selectivity, and stability remain unclear. Generally, in the NH3-SCR reaction, the redox and acid sites on the catalyst are prerequisites that need to work together. Therefore, the close coupling of these dual functional sites is imperative for the design of NH3-SCR catalysts with high NOx removal efficiency. Taking this intrinsic principle into account, we successfully designed and developed various novel catalysts with excellent NH3-SCR performance. This review will focus on the theory and practice of designing metal oxide catalysts for NH3-SCR.