Promotion effect of alkaline leaching on the catalytic performance over Cu/Fe-SSZ-13 catalyst for selective catalytic reduction of NOx with NH3

Cu-SSZ-13 is used to catalytic reduce the diesel NOx emissions, but its catalytic performance (catalytic activity, stability and sulfur resistance) is unsatisfactory in commercial application. So a novel strategy was desired to promote the catalytic ability. The raw zeolite H-SSZ-13 was firstly treated using NaOH, followed by loading Fe via impregnation and Cu modifying using ion-exchange, respectively. The influence mechanism of base leaching on structure and catalytic performance was evaluated by several characterization techniques. The base leaching can effectively promote the catalytic performance of Cu/Fe-SSZ-13. When the adopted NaOH concentration is 0.1 M, the as-synthesized catalyst exhibits superior catalytic activity, robust hydrothermal stability and good sulfur resistance compared with the commercial Cu-SSZ-13. The characterization results revealed that fine control of the base leaching could significantly promote the interaction between active metals and zeolite framework, induce the formation of Lewis acid sites, improve redox ability, effectively promote the generation of Cu2+-2Z. It also significantly accelerated the reaction rate of adsorbed NOx species with NH3 via promoting the generation of NO2 and NH3 activation, all of which were consequently responsible for the enhancement of catalytic performance. The NH3-SCR reaction over Cu/Fe-SSZ-13 followed a possible L-H mechanism.