Unveiling the effect of SO2 on CO selective catalytic reduction of NOx in the presence of O2 over IrRb@SBA-15 catalyst

Selective catalytic reduction of NOx by CO (CO-SCR) is a promising technology to remove NOx by CO for the flue gas which both contain CO and NO simultaneously. However, it is quite difficult to acquire satisfied NOx removal efficiency in the presence of O2 which owing to the quick consumption of CO by O2. In this work, a Rb modified Ir@SBA-15 (IrRb0.5@SBA-15) is developed for CO-SCR reaction in the presence of 5 % O2 which 80.3 % NOx conversion can be obtained. The Ir species have loaded into the mesoporous channels of SBA-15 which then grew into Ir nanoparticles after pretreating by H2. The improved NOx removal efficiency of IrRb0.5@SBA-15 catalyst is owing to Rb modification can improve the adsorption ability of the catalyst for reactants and improve the antioxidation ability of Ir0 sites. The presence of SO2 inhibits the consumption of CO at high temperatures which leading to the increase of NOx conversion on the catalysts. Furthermore, the presence of CO at high temperatures also can inhibits the formation of NO2. This work provides a new insight for the effect of SO2 on CO-SCR reaction for Ir-based catalysts.