FORMATION OF CU-MFI NO DECOMPOSITION CATALYST VIA REDUCTIVE SOLID-STATE ION-EXCHANGE

High-temperature treatment of a mechanical mixture of CuO and H-MFI ze olite in the absence of O-2 produced a Cu ion-exchanged zeolite cataly st with a high activity for the catalytic decomposition of NO to N-2 a nd O-2. Cu is probably introduced as Cu+ cations in zeolite ion-exchan ge sites via a solid-state ion-exchange process which includes CuO aut oreduction to Cu+. ESR, 1-propanamine thermal desorption, and TPR char acterization are consistent with this model. This preparation techniqu e has a theoretical exchange limit of 1 Cu/framework Al, which is doub le the limit theoretically imposed on Cu2+ exchange. The preferred pre paration conditions give rise to a material which approaches this theo retical limit, and there are probably similarities between catalysts p repared by this method and ''overexchanged'' Cu2+-MFI materials often reported for NO decomposition.