Promotion of the performance of Cu-SSZ-13 for selective catalytic reduction of NOx by ammonia in the presence of SO2 during high temperature hydrothermal aging

Abstract

The influence of SO2 presence during high temperature hydrothermal aging (600, 700, and 800 °C) on the performance of Cu-SSZ-13 prepared by the conventional ion-exchange method for selective catalytic reduction of NOx by NH3 (NH3-SCR) was studied. The high-temperature activity of Cu-SSZ-13 is obviously enhanced by the SO2 presence for the 700 and 800 °C-aged samples and is not hampered for the 600 °C-aged sample. The presence of SO2 during hydrothermal aging has no influence on the framework Al. The interaction of Cu2+ with SO2 results in the formation of ZCuHSO4, which helps suppress the aggregation of Cu2+ into CuO and maintain more isolated Cu2+, leading to higher activity at high temperatures. The low Cu content yields higher relative population of Cu2+ species at more stable sites. The low-temperature (≤350 °C) activity is slightly lowered for the 600 and 700 °C-aged samples.