Study of ethylene adsorption on zeolite NaY modified with group I metal ions

The adsorption of ethylene by zeolite NaY and zeolite NaY modified by cation exchange with potassium, rubidium, and cesium ions was studied. Cation exchanges were carried out using KNO3, RbNO3, and CsNO3 in the concentration ranges of 0.2-10 mM. XRD patterns and specific surface areas illustrated that modification of NaY zeolite by very dilute solutions containing K+, Rb+ and Cs+ did not lead to significant changes in the crystallinity. Analysis of metals content (ICP-OES) showed that Cs+ can replace Na+ better than Rb+ and K+. Particle analysis indicated slight decreases in surface area but pore volumes and pore diameters remained unchanged. Ethylene adsorption isotherms indicated that Na-Y zeolite which was modified by 5.0 mM KNO3, 0.5 mM RbNO3 and 1.0 mM CsNO3 could adsorb ethylene better than zeolite Na-Y. K-NaY zeolite adsorbed up to 102.45 cm3/g ethylene, while Rb-NaY and Cs-NaY zeolites adsorbed up to 98.50 cm3/g and 90.15 cm3/g ethylene, respectively. Ethylene adsorption capacities depended on number of adsorption sites and surface interactions.