Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation

The adsorption process was studied for separating para -xylene from xylene mixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO 2 /Al 2 O 3 was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para -xylene toward other C 8 aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C 8 aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para -xylene relative to each of meta -xylene, ortho -xylene and ethylbenzene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.