Adsorption of nitrogen from natural gas by clinoptilolite

Much of world’s natural gas reserves are impure, one of the principal contaminants being nitrogen which makes it unsuitable for application and, hence, its separation is important. In this research, clinoptilolite, the most abundant natural zeolite with an open aluminosilicate framework structure and high internal surface area, was modified by ion exchange process to highly exchanged forms of cations of Na+, K+ and H+. The adsorption of N2, CH4 and C2H6 on natural clinoptilolite (Cp) and on its cation-exchanged forms (Na-Cp, K-Cp and H-Cp) was studied at 25 °C. The influence of cation exchange on equilibrium adsorption of N2 showed that selectivity decreased in the order of Cp > Na-Cp > K-Cp and H-Cp has no affinity to nitrogen.