Adsorbent Evaluation Based on Experimental Breakthrough Curves: Separation of p-Xylene from C₈ Isomers

The search for new adsorbents with enhanced capacity and selectivity, suitable for application on large-scale simulated moving-bed units for separation of p-xylene, requires efficient, reliable, and fast adsorbent characterization methods for this specific separation. Fixed-bed experiments were carried out under the conditions of the Parex process to evaluate a faujasite-type zeolite as adsorbent for the separation of p-xylene from its isomers in the proportions of the real Parex feed stream. The experimental breakthrough curves were used to evaluate the selected adsorbent in terms of nonselective and selective volumes, adsorption capacity, selectivity, and productivity, which can be applied to identify the feasible separation region for different operating conditions. A method based on experimental breakthrough curves for quickly evaluating adsorbents for a defined separation in terms of selective volume, capacity, selectivity and productivity is demonstrated under the conditions of the Parex process. Fixed-bed experiments are carried out in order to assess a barium-exchanged faujasite-type zeolite as adsorbent for the separation of p-xylene from its isomers.