Studies on CXN natural zeolite - II. Adsorption properties

The adsorption properties of H-STI and Na-STI, which were prepared from the natural CXN zeolite obtained in China, were investigated with N-2, NH3, CO 2, ethylene, propylene, water, methanol, ethanol and 1-propanol. The BET su rface area and pore volume of H-STI and Na-STI were about 420 m(2)/g and 0. 20 m(3)/g. The adsorption heat of NH3 and CO2 on H-STI calculated by the ad sorption isotherms at different temperature was 44.8 and 26.5 kJ/mol respec tively. The investigation of the adsorption isotherms of ethylene, propylen e, methanol, ethanol and 1-propanol on Na-STI reveals the unusual selectivi ty to the length of the carbon chain in the molecules of organics. The load ing of water is lower than that of methanol in lower partial pressure, whic h exhibits a somewhat hydrophobic property of the zeolite.