Patent ID: 9227888
Filing Date: 2016-01-05
CPC Classification: B01J,C07C,Y02P

Claim Text:
1. A process for the production of paraxylene from a feedstream comprising a mixture of C8 aromatic hydrocarbons, comprising: (a) separation of said feedstream into a first product enriched in C8+ species relative to said feedstream and a second product enriched in C7− aromatic species relative to said feedstream; (b) passing said first product to a fractionation tower to provide a third product enriched in xylenes relative to said first product and a fourth product depleted in xylenes relative to said first product; (c) passing the third product to a xylene separation step to provide a product enriched in paraxylene when compared with said third product, and a raffinate product, characterized as depleted of paraxylene when compared with said third product; (d) passing said raffinate product directly, without a fractionation step, to a liquid phase isomerization unit, to provide a product enriched in paraxylene when compared with said raffinate; wherein at least two adsorptive separation units are used for the xylene separation step (c); wherein each adsorptive separation unit provides a product enriched in paraxylene when compared with said third product, and a raffinate product, depleted of paraxylene when compared with said third product; wherein the first of said adsorptive separation units is a light adsorptive separation unit that uses toluene as a desorbent and is fluidly connected in series to said liquid phase isomerization unit, without an intervening fractionation tower, and the second of said adsorptive separation units is a heavy adsorptive separation unit that uses para-diethylbenzene as a desorbent and is fluidly connected in series to a fractionation tower and a vapor phase isomerization unit, and further wherein the raffinate product in step (d) comprises the raffinate product from said light adsorptive separation unit.