PERVAPORATION OF AROMATIC C-8-ISOMERS

A pervaporation process was applied to the separation of different mixtures of aromatic C8-isomers using a dense homogeneous polyethylene membrane. The influence of feed temperature and downstream pressure on the flux of pure components was investigated. For mixtures, the effect of feed composition on permeation rates and separation characteristics was determined. Molar fluxes and separation factors depend on the feed composition. Coupled transport occurs and the extent of coupling depends on the difference in the permeabilities of the pure components. The mass transport of pure components through the membrane was modelled for varying downstream pressures with diffusivities linearly dependent on the concentration of all the permeants in the membrane. On the basis of this model, molar fluxes of each component in the mixture of ethylbenzene and p-xylene were calculated and compared with the experimental data. The model and experimental data show good agreement.