BINDER-FREE ADSORBENTS WITH IMPROVED MASS TRANSFER PROPERTIES AND USE THEREOF IN ADSORPTIVE SEPARATION OF PARA-XYLENE

摘要

FIELD: chemistry.;SUBSTANCE: described is a method of separating para-xylene from a mixture containing at least one other C₈ alkylaromatic hydrocarbon, which includes contacting, under adsorption conditions, the mixture with a binder-free adsorbent containing a first portion of zeolite X and a second portion of zeolite X; wherein said first portion of zeolite X has average crystallite size of 500 nm to 1.5 mcm, and said second portion of zeolite X has average crystallite size smaller than 500 nm or said second portion of zeolite X has average crystallite size greater than 1.8 mcm, wherein the combined first and second portions of zeolite X have average crystallite size smaller than 1.8 mcm, in order to adsorb para-xylene present in the adsorbed phase, preferably compared with at least one other C₈ alkylaromatic hydrocarbon present in the non-adsorbed phase; eliminating the non-adsorbed phase from contact with the adsorbent in order to obtain a raffinate stream containing said at least one other C₈ alkylaromatic hydrocarbon; and desorbing para-xylene of the adsorbed phase from the adsorbent to obtain an extract stream containing para-xylene; wherein the binder-free adsorbent does not contain amorphous material or contains amorphous in amount of less than 2 wt % in accordance with the defined X-ray diffraction method, wherein the first cycle of said method is less than 34 minutes.;EFFECT: using an adsorbent with improved capacity and mass-transfer, improved efficiency of the method at low temperature, short duration of the adsorptive separation cycle when operating in simulated moving bed mode.;15 cl, 9 dwg, 8 ex