Separation of nitrogen, the major impurity of natural gas, is necessary for quality improvement of the gas. In this study, purified and some ion-exchanged forms of clinoptilolite were used to separate N2 from natural gas. Competitive adsorption of mixtures of N2, CH4 and C2H6 by Cu2+ (Cu-Cp)-, Zn2+ (Zn-Cp)-, Ni2+ (Ni-Cp)- and Mn2+ (Mn-Cp)-exchanged samples was studied at different pressures and ambient temperature. Among the cations studied, Cu2+ has the lowest selectivity towards N2. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, BET N2 adsorption and wet chemical analysis techniques.