(288e) The Rigid Adsorbent Lattice Fluid Model Applied to the Correlation of Liquid Phase Partition Coefficients of Different Solvents in MFI Zeolites

In this contribution we extend the use of the Rigid Adsorbent Lattice Fluid (RALF) model to the correlation of liquid phase partition coefficients. This is achieved through the formulation of the problem as a multicomponent equilibrium calculation where both the solid and the solvent are explicitly taken into account. The liquid phase fugacity can be calculated either from the Sanchez-Lacombe equation of state or directly from the knowledge of the infinite dilution activity coefficients of the solutes and the vapour pressure of the solvent.

The methodology is applied to the very interesting behaviour of liquid phase adsorption in MFI zeolites. The homogeneous RALF model is shown to reproduce the observed trends for smaller solvent molecules (methanol and n-hexane). For longer chain hydrocarbons this breaks down due to the difference in behaviour between adsorption in the straight and sinusoidal channels and channel intersections of MFI zeolites. A modified RALF model that takes into account the different adsorption sites is parametrised using molecular simulations.