Synthesis, ion-exchange, structural characterization and adsorption of K, Na-FER type zeolite

Synthesis of K, Na -FER type zeolite was studied in the reactant system of K O-2-Na O-2-Al2O3 -SiO2-CO3- HCO3-ndash; H2O. Sodium silicate, silica sol and fumed silica were tested as the silica source, and solid aluminum sulfa te, aluminum hydroxide and meta-kaolinite as the alumina source. The starti ng materials, the composition of the reactant, and the synthesis temperatur e greatly influence the phases crystallized. A pure phase of K, Na-FER zeol ite was hydrothermally prepared at 208 degrees C with sodium silicate and s olid aluminum sulfate as starting materials. The optimum composition of the reactant for synthesis of the pure FER zeolite was determined. Chemical an alysis, XRD, FT-IR, Si-29 and Al-27 MAS NMR, TG/DTA, and adsorption of nitr ogen, methanol and n-hexane were used to characterize the zeolite and compa red with the reference sample of perfect single crystals of siliceous FER z eolite. The content of K+ and Na+ in the zeolite decreases gradually with t he times of the treatment of ion-exchange/calcination, leading to an increa se in the adsorption capacities of nitrogen and methanol, and a decrease of the loading of n-hexane. The location of the K+, the stacking faults, and dealumination of the zeolite framework are discussed based on the ion excha nge and adsorption behavior.