Process for Improved Meta-Xylene Yield from C8 Aromatics
AssigneeUop LLC
InventorsStanley J. Frey, Jason T. Corradi, Richard S. Kempf, David W. Liu
Life of this patent
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Abstract
Meta-xylene is recovered from admixture with other C8 aromatic hydrocarbons including ortho-xylene by liquid phase adsorptive separation. Performance is improved by reducing the concentration of ortho-xylene through adding a sidecut to a prefractionator preparing the feedstock to adsorptive separation.
Claims20
A process for recovering high-purity meta-xylene from a feedstock comprising C8 and heavier aromatic hydrocarbons which comprises:
- (a) distilling the feedstock to separate C8 aromatic hydrocarbons from heavier hydrocarbons in a xylene column which comprises a sidecut for obtaining an ortho-xylene concentrate;
- (b) contacting the C8 aromatic hydrocarbons in a selective-adsorption step at liquid-phase adsorption conditions with an adsorbent comprising a zeolite, adsorbing the meta-xylene, removing the nonadsorbed portion of said mixture from contact with said adsorbent by means of a raffinate stream and recovering the high-purity meta-xylene by desorption with a desorbent at desorption conditions.
A process for recovering high-purity meta-xylene from an unextracted feedstock comprising C8 and heavier aromatic hydrocarbons which comprises:
- (a) distilling the feedstock to separate C8 aromatic hydrocarbons from heavier hydrocarbons in a xylene column which comprises a sidecut for obtaining an ortho-xylene concentrate;
- (b) contacting the C8 aromatic hydrocarbons in a selective-adsorption step at liquid-phase adsorption conditions with an adsorbent comprising a zeolite, adsorbing the meta-xylene, removing the nonadsorbed portion of said mixture from contact with said adsorbent by means of a raffinate stream and recovering the high-purity meta-xylene by desorption with a desorbent at desorption conditions.
A process for recovering high-purity meta-xylene from a feedstock comprising C8 and heavier aromatic hydrocarbons which comprises:
- (a) distilling the feedstock to separate C8 aromatic hydrocarbons from heavier hydrocarbons in a xylene column which comprises a sidecut for obtaining an ortho-xylene concentrate;
- (b) contacting the C8 aromatic hydrocarbons in a selective-adsorption step at liquid-phase adsorption conditions with an adsorbent comprising a zeolite, adsorbing the meta-xylene, removing the nonadsorbed portion of said mixture from contact with said adsorbent by means of a raffinate stream and recovering the high-purity meta-xylene by desorption with a desorbent at desorption conditions;
- and,
- (c) isomerizing the raffinate stream with an isomerization catalyst at isomerization conditions to obtain an isomerized stream and distilling the isomerized stream along with the feedstock to separate C8 aromatic hydrocarbons from the heavier hydrocarbons and an ortho-xylene concentrate.
Dependencies are inferred from the claim text.