The effect of copper loading and silicon content on catalytic activity and hydrothermal stability of Cu-SAPO-18 catalyst for NH3-SCR

The effect of Cu loading and Si content on catalytic activity and hydrothermal stability of Cu-SAPO-18 catalysts prepared by incipient wetness impregnation method was investigated in ammonia selective catalytic reduction (NH3-SCR) reaction. The Cu-SAPO-18 catalyst with Cu loading of 2.49 wt.% shows superior NH3-SCR performance and hydrothermal stability due to the presence of more isolated Cu2+ species and the less amount of CuO species. What's more, the Cu-SAPO-18 catalysts with different Si content exhibit distinct NH3-SCR performance, though they contain similar Cu loading. The NH3-TPD, H-2-TPR and EPR results indicate that the number of acid sites and isolated Cu2+ ions over Cu-SAPO-18 catalysts rises with increasing Si content from 0.084 to 0.173, but decreases with the highest Si content of 0.204. Consequently, the Cu-SAPO-18 (0.173) catalyst shows the best NH3-SCR performance. After hydrothermal treatment, the Cu-SAPO-18 (0.173) catalyst exhibits excellent NO reduction efficiency which attributes to its stable framework and the most amount of acid sites and isolated Cu2+ ions. Additionally, the NH3-SCR kinetic analysis over Cu-SAPO-18 catalyst was also performed and suggesting that Cu loading and Si content do not influence the NH3-SCR reaction mechanism.