FTIR spectroscopic evidence of formation of geminal dinitrogen species during the low-temperature N2 adsorption on NaY zeolites

Adsorption of N-2 on NaY zeolites at 85 K and equilibrium pressures higher than 1 kPa results in the formation of geminal dinitrogen complexes characterized by an IR band at 2333.5 cm(-1) (2255.4 cm(-1) after adsorption of N-15(2)). With decreasing equilibrium pressure the complexes tend to loose one N-2 ligand, thus forming linear species characterized by an IR band at 2336.8 cm(-1) (2258.7 cm(-1) after adsorption of N-15(2)). All species disappear completely after evacuation. Co-adsorption of N-2 and CO revealed that the dinitrogen complexes are formed on Na+ cations. The changes in the concentrations of the linear and geminal N-2 species with the changes in the equilibrium pressure are excellently described by equations of adsorption isotherms proposed earlier for mono- and di-carbonyls.