The effect of zeolite framework during NH3-SCR reactions

Abstract

Zeolites are aluminosilicates with well-defined channels or pores containing metal cations. Zeolites are often used in automotive industries to reduce NOX emissions. This study aimed at synthesizing the zeolite SSZ-13 with different Si/Al ratio (SAR). Cu-SSZ-13 with SAR 12 and different Cu/Al molar ratio is the focus of this study. The purpose is to investigate the influence of framework structure on the formation of surface species during ammonia-SCR of NOX over Cu-based zeolites. The synthesis of the zeolites was carried out by the sol-gel method followed by hydrothermal crystallization in an autoclave, and Cuexchange was done by the incipient wetness impregnation method. To characterize the zeolites, ICP-SFMS, XRF, DRIFT, BET, BJH was used. XRD measurements showed no signs of impurities or structural changes since they matched the references. Synthesizing the zeolite with SAR 6 with different ratio of initial components was not successful. To evaluate the evolution of surface species during ammonia-SCR of NOX over Cu-based zeolites, DRIFT was used, which showed that Brønsted acid sites and Lewis acid sites could be found, which increased the catalytic activity and enhanced NOX conversion.