Alkali and Phosphorus Resistant Zeolite-like Catalysts for NO_x Reduction by NH_3

摘要

At present, the deactivation of selective catalytic reduction (SCR) catalysts caused by the coexistence of alkali metal and phosphorus (P) remains an urgent problem and lacks corresponding strategies against catalyst poisoning. Herein, a novel zeolite-like Ce-Si_5Al_2O_x catalyst derived from an ultrasmall nanozeolite EMT precursor was synthesized without organic templates at ambient temperature. This catalyst was able to maintain above 95% NO_x conversion in the 270-540 °C temperature range. Moreover, 1 wt % potassium (K) and 5 wt % P loading had no influence on the SCR performance of the Ce- Si_5Al_2O_x, catalyst at 300-480 °C. It was demonstrated that cerium (Ce) was highly dispersed in the amorphous aluminum (Al) silicate derived from EMT zeolites and expressed high catalytic performance. Besides, a large number of acid sites were reserved to absorb ammonia allowing effective participation in the SCR reaction and capturing alkali metals, thus improving the SCR performance and K resistance. Additionally, the strong interaction between Ce and aluminosilicate decreased cerium phosphate production, preventing deactivation of the catalysts. Thus, this novel low-cost zeolite-like Ce-Si_5Al_2O_x. catalyst with a highly active ion-exchanged metal phase and abundant surface acid sites paves a way for designing new efficient and poisoning-resistant SCR catalysts for practical applications.