Effect of hydrothermal treatment on Cu-ZSM-5 catalyst in the selective reduction of NO

The effect of hydrothermal treatment on a Cu-ZSM-5 catalyst was analyzed during the reduction reaction of NO with propane in excess of oxygen (SCR-HC). The hydrothermal treatment decreased the conversion of NO at temperatures below 773 K. Fresh and hydrotreated catalysts were characterized by several techniques, including temperature-programmed reduction (TPR), XRD, TGA, and temperature-programmed desorption (TPD), to determine the effect of hydrotreatment both on catalytic solid and reaction. Samples hydrotreated at 973 K experienced zeolite crystallinity losses and Cu sintering. These factors, along with the possible competition of water and NO adsorption for active sites, would have caused the activity decrease and selectivity modifications observed during the reduction reaction.