Redistributing Cu species in Cu-SSZ-13 zeolite as NH3-SCR catalyst via a simple ion-exchange

The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3 (NH3-SCR), but existing methods for adjusting the Cu distribution are complex and difficult to control. Herein, we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a “natural environment” for adjusting Cu distribution precisely. By using this proposed strategy, a series of Cu-SSZ-13x zeolites with different Cu contents and distributions were obtained. It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+ species and thus allows the redistribution of the Cu species. The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart. The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors (e.g., crystallinity, chemical composition, and porous structure) is responsible for the improved NH3-SCR performance and SO2 and H2O resistance. Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.