Propylene/propane mixture adsorption on faujasite sorbents

The adsorption of propylene and propane on zeolite NaX with and without a saturated (36 wt%) amount of CuCl have been investigated. The single component adsorption isotherms could be well described with a Dual-Site Langmuir model. The dispersion of CuCl results in a decrease of the maximum adsorption capacity of the zeolite for both components. For propylene a strong adsorption via pi-complexation with CuCl is present, increasing the adsorption selectivity of the zeolite. The binary mixture (50:50) adsorption was determined via breakthrough/desorption experiments at 318, 358 and 408 K with a partial pressure of the two components between 0.8-54 kPa. For NaX the mixture loading could be well described with the IAS-theory and the single component isotherms, both qualitatively and quantitatively. A transition from an enthalpy controlled adsorption at lower loadings to an entropy affected adsorption at higher loadings was observed. The IAS-theory could only qualitatively describe the trends in the observed mixture adsorption for the CuCl/NaX adsorbent. The dispersion of CuCl in NaX results in a modest improvement of the adsorption selectivity for propylene over propane (from 3-7 to 15-30) but at the expense of a reduced capacity.