Crystal growth regulation of Cu-SSZ-13 zeolites for effective catalytic reduction of NOx from automotive exhausts

Abstract

In this study, glucose was used in the synthesis of SSZ-13 zeolites; it acted as a zeolite growth regulator to successfully change the morphology of SSZ-13 zeolites. The particle size of the SSZ-13 zeolites reduced from 10 to 3 μm, and the morphology of the zeolite surface changed from rough and irregular spherical to smooth and uniform cubic. The glucose-modified SSZ-13 zeolites were ion-exchanged with Cu2+ ions (named as Cu-SSZ-13-Glu) and tested for the catalytic reduction of NOx with NH3 (NH3–SCR). The results demonstrated that the catalyst Cu-SSZ-13-Glu exhibited better NH3–SCR catalytic performance than that of conventional Cu-SSZ-13, with a wider effective reaction window, superior low-temperature SCR performance, favorable anti-SO2 poisoning ability, and excellent hydrothermal stability. The characterization results of the Cu-SSZ-13-Glu sample revealed an increase in crystallinity as well as acidic sites, and an improvement in the redox properties. After hydrothermal aging, compared with traditional Cu-SSZ-13, the Cu-SSZ-13-Glu zeolites exhibited a more stable structure and maintained higher crystallinity, larger specific surface area, and microporous volume. Moreover, the Cu2+ ions in the Cu-SSZ-13-Glu zeolites were more stable, and fewer CuOx species were generated after hydrothermal aging, retaining more Cu2+ ions species and acidic sites. To summarize, the simply prepared Cu-SSZ-13-Glu zeolites exhibited excellent catalytic activity and hydrothermal stability, showing broad application prospects in the field of nitrogen oxide removal from automotive exhausts.