Abstract: Mixed ion exchanged Li-Ca-LSX were prepared respectively from the starting materials Li-LSX and Ca-LSX and effects of the difference on ion exchanging degree, ion location and adsorption properties were investigated via the measurements of ICP-AES, ⁷Li MAS NMR, ²³Na MAS NMR and static adsorption method. The results show that the Li-Ca-LSX prepared from Ca-LSX as the starting material reaches the exchange maximum by 31.5% and the best properties, namely the specific adsorption capacity at 36.4mL/g for N₂ and 5.0mL/g for O₂; and the N₂/O₂ adsorption selectivity at 12.4. From the results of NMR, it is found that excepting the well-known site SIII, some Li⁺ locating at the site SI’ can also affect significantly on the adsorption properties of LSX.

Key words: low silica X-type zeolite(LSX), starting materials, ion location, specific adsorption capacity