Separation and recovery of ethylbenzene by dual desorbent composition and temperature separation processes

Claim 2

In a process for continuously separating, in a liquid phase, the components of a liquid C 8 aromatic feedstream containing ethylbenzene wherein at least one of said components is selectively adsorbed by contact with a solid sorbent material, utilizing a simulated countercurrent flow system wherein liquid streams are allowed to flow downward through a desorption zone, a rectification zone and a sorption zone, each zone being serially and circularly interconnected and divided into a plurality of serially interconnected sections, each section being packed with a mass of said solid sorbent material, the improvement which comprises: a. introducing a first desorbent stream containing a desorbent and a diluent into the first section of said desorption zone; b. withdrawing a desorption effluent containing a selectively sorbed component from the last section of said desorption zone; c. introducing a second desorbent stream containing said diluent and at least about 15 weight percent of said desorbent into the first section of said rectification zone; d. introducing said hydrocarbon feedstream into the first section of said sorption zone; e. withdrawing a raffinate effluent containing a less sorbed component from the last section of said sorption zone; and f. wherein the concentration of said desorbent present in the first desorbent stream is higher than the concentration of said desorbent present in the second desorbent stream by at least 20 weight percent.

Claim 3

The process of claim 1 wherein the first desorbent stream employed in step (a) is heated, before it is introduced into the first section of said desorption zone, to a temperature higher than the temperature of the second desorbent stream employed in step (c).

Claim 4

The process of claim 1 wherein said diluent is a C 8 to C 16 paraffin.

Claim 5

The process of claim 1 wherein said desorbent is selected from the group consisting of toluene, m-diisopropylbenzene, p-diethylbenzene, o-dichlorobenzene and a mixture of diethylbenzene isomers.

Claim 6

The process of claim 1 wherein said sorbent material is a crystalline aluminosilicate selected from the group consisting of rubidium-exchanged sodium Type X and cesium-exchanged Type Y sieves.

Claim 7

The process of claim 5 wherein said selectively sorbed component withdrawn in step (b) is ethylbenzene.

Claim 8

The process of claim 5 wherein said less sorbed component withdrawn in step (c) is a xylene isomer.

Claim 9

The process of claim 1 wherein said sorbent material is a crystalline aluminosilicate selected from the group consisting of sodium Type Y, lithium Type Y, calcium Type Y, magnesium Type Y and potassium-exchanged steamed ammonium Type Y sieves.

Claim 10

The process of claim 8 wherein said selectively sorbed component withdrawn in step (b) is a xylene isomer.

Claim 11

The process of claim 9 wherein said less sorbed component withdrawn in step (c) is ethylbenzene.

Claim 12

In a process for continuously separating, in a liquid phase, the components of a liquid C 8 aromatic feedstream containing a xylene isomer and ethylbenzene wherein at least one of said components is selectively adsorbed by contact with a solid sorbent material, utilizing a simulated countercurrent flow system wherein liquid streams are allowed to flow downward through a desorption zone, a rectification zone and a sorption zone, each zone being serially and circularly interconnected and divided into a plurality of serially interconnected sections, each section being packed with a mass of said solid sorbent material, the improvement which comprises: a. introducing, into the first section of said desorption zone, a first desorbent stream comprising a desorbent selected from the group consisting of m-diisopropylbenzene, toluene, p-diethylbenzene, o-dichlorobenzene and a mixture of diethylbenzene isomers in an amount ranging from about 40 to about 100 weight percent and a paraffinic diluent having from 8 to 16 carbon atoms; b. withdrawing a desorption effluent containing ethylbenzene from the last section of said desorption zone; c. introducing, into the first section of said rectification zone, a second desorbent stream containing said paraffinic diluent and from about 15 to about 60 weight percent of said desorbent; b. introducing said hydrocarbon feedstream into the first section of said sorption zone; e. withdrawing a raffinate effluent containing said xylene isomer from the last section of said sorption zone; and f. wherein the concentration of said desorbent present in the first desorbent stream is higher than the concentration of said desorbent present in the second desorbent stream by at least 20 weight percent.

Claim 13

In a process for continuously separating, in a liquid phase, the components of a liquid C 8 aromatic feedstream containing a xylene isomer and ethylbenzene wherein at least one of said components is selectively adsorbed by contact with a solid sorbent material, utilizing a simulated countercurrent flow system wherein liquid streams are allowed to flow downward through a desorption zone, a rectification zone and a sorption zone, each zone being serially and circularly interconnected and divided into a plurality of serially interconnected sections, each section being packed with a mass of said solid sorbent material, the improvement which comprises: a. introducing, into the first section of said desorption zone, a first desorbent stream comprising a desorbent selected from the group consisting of m-diisopropylbenzene, toluene, p-diethylbenzene, o-dichlorobenzene and a mixture of diethylbenzene isomers in an amount ranging from about 40 to about 100 weight percent and a paraffinic diluent having from 8 to 16 carbon atoms; b. withdrawing a desorption effluent containing ethylbenzene from the last section of said desorption zone; c. introducing, into the first section of said rectification zone, a second desorbent stream containing said paraffinic diluent and from about 15 to about 60 weight percent of said desorbent; b. introducing said hydrocarbon feedstream into the first section of said sorption zone; e. withdrawing a raffinate effluent containing said xylene isomer from the last section of said sorption zone; and f. wherein the concentration of said desorbent present in the first desorbent stream is higher than the concentration of said desorbent present in the second desorbent stream by at least 20 weight percent.

Claim 14

The process of claim 11 wherein the first desorbent stream employed in step (a) is heated, before it is introduced into the first section of said desorption zone, to a temperature higher than the temperature of the second desorbent stream employed in step (c).

Claim 15

The process of claim 11 wherein said xylene isomer is selected from the group consisting of orthoxylene, metaxylene and paraxylene.

Claim 16

The process of claim 11 wherein said sorbent material is a crystalline aluminosilicate selected from the group consisting of rubidium-exchanged sodium Type X and cesium-exchanged Type Y sieves.

Claim 17

The process of claim 14 wherein said sorbent material is rubidium-exchanged sodium Type X zeolite sieve.

Claim 18

In a process for continuously separating, in a liquid phase, the components of a liquid C 8 aromatic feedstream containing a xylene isomer and ethylbenzene wherein at least one of said components is selectively adsorbed by contact with a solid sorbent material, utilizing a simulated countercurrent flow system wherein liquid streams are allowed to flow downward through a desorption zone, a rectification zone and a sorption zone, each zone being serially and circularly interconnected and divided into a plurality of serially interconnected sections, each station being packed with a mass of said solid sorbent materials, the improvement which comprises: a. introducing, into the first section of said desorption zone, a first desorbent stream comprising a desorbent selected from the group consisting of m-diisopropylbenzene, toluene, p-diethylbenzene, o-dichlorobenzene and a mixture of diethylbenzene isomers in an amount ranging from about 40 to about 100 weight percent and a paraffinic diluent having from 8 to 16 carbon atoms; b. withdrawing a desorption effluent containing said xylene isomer from the last section of said desorption zone; c. introducing, into the first section of said rectification zone, a second desorbent stream containing said paraffinic diluent and from about 15 to about 60 weight percent of said desorbent; d. introducing said hydrocarbon feedstream into the first section of said sorption zone; e. withdrawing a raffinate effluent containing ethylbenzene from the last section of said sorption zone; and f. wherein the concentration of said desorbent present in the first desorbent stream is higher than the concentration of said desorbent present in the second desorbent stream by at least 20 weight percent.

Claim 19

In a process for continuously separating, in a liquid phase, the components of a liquid C 8 aromatic feedstream containing a xylene isomer and ethylbenzene wherein at least one of said components is selectively adsorbed by contact with a solid sorbent material, utilizing a simulated countercurrent flow system wherein liquid streams are allowed to flow downward through a desorption zone, a rectification zone and a sorption zone, each zone being serially and circularly interconnected and divided into a plurality of serially interconnected sections, each station being packed with a mass of said solid sorbent materials, the improvement which comprises: a. introducing, into the first section of said desorption zone, a first desorbent stream comprising a desorbent selected from the group consisting of m-diisopropylbenzene, toluene, p-diethylbenzene, o-dichlorobenzene and a mixture of diethylbenzene isomers in an amount ranging from about 40 to about 100 weight percent and a paraffinic diluent having from 8 to 16 carbon atoms; b. withdrawing a desorption effluent containing said xylene isomer from the last section of said desorption zone; c. introducing, into the first section of said rectification zone, a second desorbent stream containing said paraffinic diluent and from about 15 to about 60 weight percent of said desorbent; d. introducing said hydrocarbon feedstream into the first section of said sorption zone; e. withdrawing a raffinate effluent containing ethylbenzene from the last section of said sorption zone; and f. wherein the concentration of said desorbent present in the first desorbent stream is higher than the concentration of said desorbent present in the second desorbent stream by at least 20 weight percent.

Claim 20

The process of claim 16 wherein the first desorbent stream employed in step (a) is heated, before it is introduced into the first section of said desorption zone, to a temperature higher than the temperature of the second desorbent stream employed in step (c).

Claim 21

The process of claim 16 wherein said sorbent material is a crystalline aluminosilicate selected from the group consisting of sodium Type Y, lithium Type Y, calcium Type Y, magnesium Type Y and potassium-exchanged steamed ammonium Type Y sieves.

Claim 22

The process of claim 16 wherein said xylene isomer is selected from the group consisting of orthoxylene, metaxylene and paraxylene.