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 du ring 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 severa l techniques, including temperature-programmed reduction (TPR), XRD, TGA, a nd temperature-programmed desorption (TPD), to determine the effect of hydr otreatment both on catalytic solid and reaction. Samples hydrotreated at 97 3 K experienced zeolite crystallinity losses and Cu sintering. These factor s, along with the possible competition of water and NO adsorption for activ e sites, would have caused the activity decrease and selectivity modificati ons observed during the reduction reaction.