SPECTROSCOPIC BEHAVIOR IN THE ADSORPTION OF CO-CL-2 MIXTURES ON NAY-FAU ZEOLITE

Fourier transform infrared spectroscopy was applied for a systematic i nvestigation of the adsorption of gaseous CO-Cl-2 gas mixtures on NaY- FAU zeolite. A doublet of Fermi resonance due to the phosgene (COCl2) molecule on the surface was detected independently of the sequence of adsorption of the reactants. When Cl-2 was adsorbed on a sample alread y loaded with CO, the Fermi doublet was accompanied by several additio nal new bands. A sharp band due to adsorbed CO2 was also detected. The se bands disappeared on heat treatment at 400 K and only the Fermi dou blet remained. With the reverse sequence of adsorption, only the Fermi doublet was detected at room temperature. Experiments with (CO)-C-13 revealed the Fermi doublet at lower wavenumbers. The calculated resona nce parameters indicated the Fermi resonance was stronger. (C) 1997 El sevier Science B.V.