Studies on Cu-containing MFI zeolites by H-2-TPR and O-2-TPD

Different metal ion-exchanged ZSM-5 zeolites were investigated by means of H-2-temperature-programmed reduction (H-2-TPR) and O-2-temperature-programm ed desorption (O-2-TPD). Pure Cu-ZSM-5 and in-situ synthesized Cu-ZSM-5/cor dierite monolithic catalysts were also characterized by H-2-TPR in order to compare the oxidation states of copper ions on them. The results show that the Cu-ZSM-5 catalyst has superior oxygen storage capacity than the Co-ZSM -5 and Fe-ZSM-5. The catalyst activity for NO decomposition is closely rela ted to this property. Copper ions are the active sites for the reaction. Th e addition of Ag and Ce, as promoters decreases the temperature of O-2 deso rption, which indicates that adding Ag and Ce favors the O-2 desorption fro m the catalyst surface. The state of Cu on the Cu-ZSM-5/cordierite monolith ic catalyst is different from that on the pure Cu-ZSM-5. Less Cu+ species i s found on the monolithic sample but it is more stable than that on the pur e Cu-ZSM-5.