X-RAY-ABSORPTION STUDIES OF COBALT ALUMINOPHOSPHATE ZEOLITES (COAPO-5)

XAS studies of cobalt-substituted aluminophosphate zeolites (CoAPO-5) indicate that Co+2 cations are incorporated in the zeolite framework, as evidenced by the intense 1s-3d pre-edge feature, the coordination n umber (4.0), the Co-O bond length (1.93 Angstrom) and the very small t emperature effect on Debye-Waller factor. Calcination of the as-synthe sized material either in air or in nitrogen results in an increased st ructural disorder. No structural changes due to ammonia exchange or hy drogen reduction are detected indicating framework cobalt is the only phase in our preparations.