Effects of Different Starting Materials on Preparation and Adsorption Properties of the Mixed Li~+ and Ca~(2+)Exchanged Low Silica X-type Zeolites(LSX)

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,~(23)Na 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 N_2 and 5.0mL/g for O_2;and the N_2/O_2 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.