Pure Component\nand Binary Mixture Adsorption of Light\nAlkanes and Alkenes on Zeolite NaX at Low Temperatures: Influence\nof Chain Length

In this study, the separation of short-chain alkane/alkene\npairs\nby fixed-bed adsorption on zeolite NaX at low temperatures is investigated.\nExperiments are carried out with pure components and mixtures of ethane/ethene,\npropane/propene, and <i>n</i>-butane/1-butene in the temperature\nrange between −75 and +40 °C and partial pressures up\nto 450 Pa. For a short chain length, much stronger adsorption of the\nalkene is observed. In contrast, with an increase in chain length,\nthe isotherms of alkanes and alkenes of the same chain length become\nmore similar. In addition, a greater influence of temperature on capacity\nis seen, the shorter the chain length is. In binary mixtures, a strong\ncompetition occurs at high total loadings with the alkene displacing\nthe alkane. A characteristic curve is formed for the selectivity in\nthe mixture, which shifts to higher temperatures with an increase\nin the chain length.