NATURE OF THE ACTIVE-SITES AND CATALYTIC ACTIVITY OF SAPO-5 SYNTHESIZED IN THE PRESENCE OF NICKEL CATIONS

Ni-modified SAPO-5 (Ni/SAPO-5) has been synthesized via admixing nicke l ions in the gel for crystallization of SAPO-5. These materials posse ss a higher catalytic activity in acid catalyzed reactions than does S APO-5. The diffuse reflection IR spectra do not indicate significant c hanges in the acidic OH groups of Ni-containing samples compared to th ose of pure SAPO-5. Thus the enhanced catalytic activity of Ni/SAPO-5 can be attributed mostly to finely dispersed extra framework nickel sp ecies which could modify the environment of the Bronsted centers in th e SAPO-5 or act cooperatively with the protons in the catalytic conver sion of aromatic hydrocarbons.