Au(I) ions were incorporated into NaY zeolite via solid-vapor reaction
between Au2Cl6 vapor and partially dehydrated zeolite in high vacuum.
The process involved the evolution of HCl, as monitored by temperatur
e-programmed desorption-mass, resulting in the reduction of Au(III) in
to Au(I). X-ray photoelectron spectroscopy characterization of Au-n+/N
aY revealed the Au 4f(7/2) peak exhibited a chemical shift by +1.95 eV
relative to that of Au-0, implying the formation of surface AuCl or l
ike species. Upon the introduction of Au2Cl6 into NaY zeolite, the IR
OH band at 3690 cm(-1) due to cation-water interaction in NaY zeolite
declined. On the other hand, a strong hydroxyl band at 3640 cm(-1) was
delivered due to polarization of H2O in zeolite by the electrostatic
potential associated with the Au-n+ (n > 1) ions. Adsorption of D2O on
to Au2Cl6/NaY at room temperature produced a peak at 2656 cm(-1) due t
o OD species associated with Au-n+ (n > 1). Degassing of D2O at 333 K
reduced this peak in favor of a new band at 2690 cm(-1) which is assig
ned to O-D stretching mode in the Au (OD)Cl moiety. The CO chemisorpti
on onto Au(I)/NaY at 77 K followed by evacuation to reduced pressures
showed a unique carbonyl band at 2188 cm(-1), which is characteristic
of Au(I) ions. The evolution of HCl during the solid-vapor reaction pr
oduced protonic sites, which were detected by Fourier transform infrar
ed of pyridine adsorption. The concentration of these sites increased
up to 353 K, where the solid-vapor reaction leveled off. The subsequen
t pyridine-Cl-2 adsorption did not lead to changes in the oxidation st
ate of Au(I) ions, indicating that NaY zeolite stabilized their struct
ure. (C) 1995 Academic Press, Inc.