Patent ID: 6706938
Filing Date: 2004-03-16
Classification: C07C

Abstract:
In a simulated moving bed adsorptive separation process for the separation of para-xylene from a feed mixture comprising other C8 aromatics, in which process the feed mixture is contacted with a zeolitic molecular sieve, which sieve has been exchanged with at least barium, at adsorption promoting conditions including a temperature ranging from 210-300Â° F., para xylene is selectively adsorbed on the molecular sieve and subsequently removed using a desorbent stream comprising toluene, the improvement which comprises maintaining a performance index (IP) above 90 at an A/F ratio of from about 0.5 to about 0.7 by operating with a desorbent stream purity above 98 vol. % allowing operation at an L3/A ratio of about 1.6 to about 2.3 whereA=rate of simulated circulation of selective pore volume through the process, F=volumetric feed rate of the feed mixture, L3=liquid flow rate through zone 3, and IP=square root of (yield % times purity %) of para xylene in the extract product stream of the process.