Location of benzene and cations in Si-rich NaY zeolites: a comparative and quantitative infrared spectroscopic study

The location of benzene molecules and Na+ ions in two Si-rich NaY (NaYs and NaYd) zeolites (Si/Al≈3.5), prepared by different methods, has been investigated using FTIR spectroscopy and compared with that in NaY (Si/Al=2.3), and NaEMT (Si/Al=3.6) zeolites. Two adsorption sites for benzene, Na+ ions and 12R windows, have been evidenced in two Si-rich NaY and in NaY zeolite instead of one, i.e. Na+ ions, in NaEMT. The desorption experiments have revealed that the interaction of benzene with Na+ ions is stronger than that with 12R windows and there are various strengths of interaction of benzene with Na+ ions in NaEMT. The total benzene adsorption capacity and the selectivity of benzene adsorbed have been quantitatively analyzed. The adsorption behavior of benzene has been correlated with the Al distribution, the location of Na+ ions, the average negative charge of oxygen atoms, the zeolite structure and the interaction strength of benzene with one site or another.