Adsorption of Chloroform in NaY Zeolite:  A Computational and Vibrational Spectroscopy Study

The structure and energetics of chloroform binding sites in NaY zeolite have been studied by energy-minimization calculations and vibrational spectroscopy. A new force field for chlorocarbon-type molecules in zeolites has been developed. Our simulations predict the adsorption of chloroform in the 12-ring window where the hydrogen atom is involved in a hydrogen bond with the framework oxygens. This interaction is clearly revealed by inelastic neutron scattering and Raman spectroscopies, which show a typical softening of the stretching mode (ν 1 ) and a hardening of the bending mode (ν 4 ) involving the H atom of the adsorbed chloroform molecule. The overall host−guest interaction energy involves three components that have been identified as being typical of hydrohalocarbon adsorption in zeolites: (i) short-range interactions between chlorine and framework oxygens, (ii) electrostatic interactions between chlorine atoms and accessible Na ions, and (iii) hydrogen bonding with the framework oxygens.