Adsorption of N2 and CO2 on zeolite X exchanged with potassium, barium, or lanthanum

The zeolite X ion exchanged with K Ba, or La was tested for the adsorption of N-2 and CO2. The physical adsorption of N-2 at 77 K confirmed that the zeolite framework remained intact after exchange and thermal treatment. The isotopic transient analysis of N-2 adsorbed on the samples at 303-333 K indicated that BaX had the highest uptake of N-2, with a heat of adsorption equal to 4.5 kcal mol(-1). In addition, the vibrational frequency of adsorbed N-2 was most perturbed by the presence of Ba cations. Results from Fourier transform infrared (FT-IR) spectroscopy showed that hydroxyl groups were associated with both the Ba and the La cations in the zeolites. FT-IR spectroscopy of adsorbed CO2 confirmed that the K form of zeolite X was the most basic with respect to forming surface carbonates.