Adsorption of N₂ and CO₂ on Zeolite X Exchanged with Potassium, Barium, or Lanthanum

Abstract

The zeolite X ion exchanged with K, Ba, or La was tested for the adsorption of N2 and CO2. The physical adsorption of N2 at 77 K confirmed that the zeolite framework remained intact after exchange and thermal treatment. The isotopic transient analysis of N2 adsorbed on the samples at 303−333 K indicated that BaX had the highest uptake of N2, with a heat of adsorption equal to 4.5 kcal mol-1. In addition, the vibrational frequency of adsorbed N2 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.

Advances in principal factors influencing carbon dioxide adsorption on zeolites

“…This phenomenon might be caused by a decrease of partial negative charge of oxygen atoms adjacent to Ba 2+ cations. In this matter, an analysis of the CO 2 adsorption on zeolites KX, BaX and LaX has effectively indicated that the zeolite KX was the most basic among these three zeolites [28]. In contrast, a study of CO 2 adsorption on the clinoptilolite has indicated that the substitution of Na + and K + by Ca 2+ caused a rise of the basicity of the framework oxygen acting as basic center [7].…”

“…The molecules that have a great permanent quadrupole moment might interact strongly with the gradient of the electric field induced by the zeolites cations [50]. The quadrupole moment of certain gas varies as following: CO 2 > CO > N 2 > H 2 > CH 4 ≈ Ar ≈ Kr [28]. Goj et al [51] have effectively showed that the zeolites ITQ-3 and ITQ-7 adsorb preferentially the CO 2 to detriment of N 2 .…”

Synthesis of zeolite from waste fly ash for adsorption of CO2

“…Also, the charge density of divalent cations is higher than that of monovalent cations. 21 Therefore, the amount of CO 2 adsorbed on calcium-impregnated sorbent would be expected to be quite high.…”

Gas adsorption microcalorimetry and modelling to characterise zeolites and related materials

“…In both processes, the role of the compensation cation can be crucial. In the past few years, some experimental studies [44][45][46][47][48] have been dealt with the influence of either the nature or distribution and density of these extra-framework cations on the adsorption properties of various zeolite systems. It was clearly established that these cations play a key role in the adsorption phenomena in such materials.…”