Selective adsorption of propylene from mixtures with propane over a lithium-exchanged zeolite 13X has been studied.
Adsorption equilibrium of pure gases has been evaluated at three different temperatures by volumetric and gravimetric methods. Propylene is adsorbed preferentially over propane, particularly at low pressures. Adsorption equilibrium can be well described with the multi-site Langmuir and the Virial models. At 1 bar and 323 K, the amount adsorbed of propylene is 2.5 mol/kg while the loading of propane is 2.0 mol/kg. The dynamic behavior of the sample has also been evaluated on the bench scale in a fixed-bed for binary breakthrough performance. Macropore adsorption controls the diffusion process within the extrudates of the zeolite. The mathematical model could satisfactorily predict the behavior of the bed. The data obtained in this work allows to model any adsorption-based process for propane/propylene separation, like vacuum pressure swing adsorption and simulated moving bed.