IDENTIFICATION OF CU SITES IN ZSM-5 ACTIVE IN NO DECOMPOSITION

Using Cu+ luminescence enabled the identification of two main Cu sites present in the MFI matrix and reflected in the 480 and 540 nm emissio n bands. It has been found that the activity of Cu-ZSM-5 in NO decompo sition is controlled by the concentration of the sites with the Cu+ em ission at 540 nm and by the reducibility of these Cu sites controlled by the framework Si/Al ratio. These Cu sites are incorporated into the zeolite as (Cu2+OH)(+) ions, bearing after calcination an extra frame work oxygen, and exchanged in the vicinity of one framework aluminum.