Zeolitic Materials for DeNOx Selective Catalytic Reduction

Selective catalytic reduction (SCR) of NOx has been proven to be the most efficient technique for the removal of NOx (deNO(x)) from flue gas of stationary sources and diesel engine exhaust of mobile sources. Among various SCR catalysts, zeolites are considered as the most promising candidates for heavy-duty trucks owing to their benign nature, very high NOx conversion and N-2 selectivity, as well as excellent hydrothermal stability at high temperatures. In recent years, a tremendous number of research articles have reported on the evolution of zeolitic materials for deNO(x), which makes a critical review timely to provide inspiration for future development. This paper first gives a chronological progress of zeolite catalysts specifically highlighting the CHA zeolites, the hotspot of present research and application, followed by a summary on the synthesis of CHA zeolites, the structure-activity relationships, as well as the reaction mechanisms and kinetics. Last but not least, a critical outlook is given together with expected research directions in developing zeolite-based catalysts for deNO(x).