IDENTIFICATION OF ISOLATED PT ATOMS IN H-MORDENITE

The state and dispersion of Pt supported on mordenite have been studie d using FTIR spectroscopy, CO chemisorption, and H-D isotope exchange of cyclopentane. Under conditions for which other criteria indicate th e presence of monatomic Pt-o, a characteristic IR band of adsorbed CO is identified at 2123 cm(-1). The position of this band does not chang e with CO coverage, indicating an interaction between CO and highly di spersed Pt. A significant blue shift of the band with respect to that of CO on multiatomic Pt clusters and the disappearance of this band up on neutralizing the acidic OH groups show that the Pt atoms are electr on-deficient and interact with zeolite protons. These FTIR data thus c onfirm the presence of extremely small Pt clusters, presumably [Pt-1-H -z](z+) adducts, in H-mordenite.