A series of NaZSM-5 supported palladium catalysts have been prepared by impregnation method. Influences of the calcination temperature, reaction temperature, Pd content and reduction on CO oxidation have been studied. It is found that the catalytic activity decreased with the increase of the calcination temperature. the higher reaction temperature or Pd content resulted in the higher catalytic performance for CO oxidation, and H_2 reduction on catalyst resulted in lower catalytic performance. The results of XRD and TEM show that Pd species are highly dispersed over NaZSM-5 zeolite, which is dependent on the pretreatment temperatures and reaction conditions. Analysis of the surface by XPS proves the PdO_2 is easily reduced to PdO and Pd by CO and H_2, which is related to the deactivation of Pd/NaZSM-5 catalyst for CO complete oxidation.

Key words: PALLADIUM, ZSM-5, NO, CATALYTIC ACTIVITY