Patent ID: 6060634
Filing Date: 2000-05-09
Classification: C07C

Abstract:
A process for the preparation of para-xylene from a toluene feed, comprising:a) paraselectively disproportionating toluene in the presence of hydrogen and a catalyst in a disproportionation zone to produce an effluent containing benzene, toluene, para-xylene enriched xylenes, ethylbenzene and aromatic hydrocarbons containing at least 9 carbon atoms;b) distilling the effluent of (a) using at least two distillation columns to separately produce benzene, toluene and xylenes;c) crystallizing the xylenes of (b) using at least one crystallization zone to produce very high purity para-xylene and a mother liquor which is depleted in paraxylene,d) contacting said mother liquor of (c) with a zeolitic adsorption bed in a simulated moving bed adsorption zone in the presence of a desorbent, under conditions such that a first fraction is obtained which is depleted in para-xylene and contains desorbent and a second fraction is obtained which is enriched in para-xylene and contains desorbent; and(e) recycling at least a portion of said second fraction to the crystallization zone after distilling substantially all of the desorbent.