Process for producing p-xylene and ethylbenzene from C8 aromatic containing ethylbenzene

Patent metadata

Field	Value
Publication number	US-11845718-B2
Application number	US-202017754285-A
Country	US
Kind code	B2
Filing date	Sep 28, 2020
Priority date	Sep 29, 2019
Publication date	Dec 19, 2023
Grant date	Dec 19, 2023

Abstract

A process for producing para-xylene and ethylbenzene from C8 aromatics containing ethylbenzene includes the steps of sending C8 aromatics containing ethylbenzene to an ethylbenzene liquid-phase adsorption separation device, wherein a suction liquid containing ethylbenzene and a suction residual liquid are obtained after the adsorption separation, and the desorbents in the suction liquid and the suction residual liquid are removed to obtain ethylbenzene and a suction residual oil; sending the suction residual oil to a para-xylene adsorption separation device, and unadsorbed components are discharged as a raffinate from the adsorbent bed; the adsorbent bed is rinsed with a desorbent to desorb the para-xylene therein and obtain an extract; the desorbents in the extract and the raffinate are respectively removed to obtain para-xylene and a raffinate oil; sending the raffinate oil to a xylene isomerization device to carry out xylene isomerization, and the isomerization product is fractionated.

First claim

The invention claimed is:

1. A process for producing para-xylene and ethylbenzene from C 8 aromatics containing ethylbenzene, comprising the following steps:
(1) sending a C 8 aromatics feed stream containing ethylbenzene to an ethylbenzene liquid-phase adsorption separation device, so that the ethylbenzene therein is adsorbed by a first adsorbent in an ethylbenzene adsorbent bed, and components not adsorbed by the first adsorbent are discharged from the ethylbenzene adsorbent bed as an adsorption residual liquid; rinsing the ethylbenzene adsorbent bed with a first desorbent to desorb the ethylbenzene therein and obtain an effluent, removing the first desorbent in the effluent to obtain ethylbenzene, and removing the first desorbent in the adsorption residual liquid to obtain an adsorption residual oil;
(2) feeding the adsorption residual oil obtained in step (1) to a para-xylene adsorption separation device, wherein the para-xylene is adsorbed by a second adsorbent in a para-xylene adsorbent bed, and components not adsorbed are discharged from the adsorbent bed as a raffinate; rinsing the para-xylene adsorbent bed with a second desorbent to desorb the para-xylene therein and obtain an extract, and removing the second desorbent in the extract to obtain a para-xylene product stream, and removing the second desorbent from the raffinate oil; and
(3) feeding the raffinate oil obtained in step (2) to a xylene isomerization device to carry out xylene isomerization in presence of a xylene isomerization catalyst, fractionating the isomerization product to obtain a C 7 − aromatics fraction, a C 8 aromatics-containing fraction, discharging the C 7 − aromatics fraction, and feeding the C 8 aromatics-containing fraction to the para-xylene adsorption separation device.

2. The process according to claim 1 , wherein, in step (1), the ethylbenzene liquid-phase adsorption separation device is a first liquid-phase simulated moving bed operating at a temperature of 70 to 180° C. and a pressure of 0.2 to 2.0 MPa.

3. The process according to claim 2 , wherein number of adsorbent beds of the first liquid-phase simulated moving bed is 8 to 24.

4. The process according to claim 1 , wherein the ethylbenzene adsorbent comprises 95-99.5 mass % of CsNaX zeolite and 0.5-5 mass % of binder, wherein a molar ratio of Cs/Na is 1.5-10.0, and the first desorbent is toluene.

5. The process according to claim 1 , wherein the ethylbenzene adsorbent comprises 95-99.5 mass % of X zeolite and 0.5-5 mass % of binder, wherein a cation site of the X zeolite is occupied by Ba or Ba and K, and the first desorbent is benzene.

6. The process according to claim 5 , wherein a Na 2 O content in the ethylbenzene adsorbent is less than 0.6 mass %; when the cation site of the X zeolite is occupied by Ba, the content of BaO in the adsorbent is 35-45 mass %; and when the cation site of the X zeolite is occupied by Ba and K, the content of BaO in the adsorbent is 25-35 mass % and the K 2 O content is 7-10 mass %.

7. The process according to claim 4 , wherein the first desorbent has a water content of 1 to 15 ppm.

8. The process according to claim 5 , wherein the desorbent has a water content of 50 to 100 ppm.

9. The process according to claim 4 , wherein a ratio of a volumetric flow of the first desorbent to a volumetric flow of the C 8 aromatics feed stream is 0.6 to 5.0 or 0.6 to 3.0.

10. The process according to claim 1 , wherein, in step (2), the para-xylene liquid-phase adsorption separation device is a second liquid-phase simulated moving bed operating at a temperature of 110 to 200° C. and a pressure of 0.4 to 2.0 MPa.

11. The process according to claim 10 , wherein a number of adsorbent beds of the second liquid-phase simulated moving bed is 8 to 24.

12. The process according to claim 1 , wherein the para-xylene adsorbent comprises 95-99.5 mass % of X zeolite and 0.5-5 mass % of binder, wherein a cation site of the X zeolite is occupied by Ba or Ba and K.

13. The process according to claim 1 , wherein the second desorbent is toluene or para-diethylbenzene.

14. The process according to claim 1 , wherein xylene isomerization is carried out at a temperature of 210-360° C. and a pressure of 0.1-4.0 MPa, a weight hourly space velocity of the raffinate oil passing through the catalyst of 11-20 h −1 , and a hydrogen/hydrocarbon molar ratio of 0-0.9.

15. The process according to claim 1 , wherein the isomerization product is fractionated to obtain the C 7 − aromatics fraction, a C 8 aromatics fraction, and a C 9+ aromatics fraction, and the C 7 − aromatics fraction and the C 9 + aromatics fraction are discharged, and the C 8 aromatics fraction is fed to the para-xylene adsorption separation device.

16. The process according to claim 1 , further comprising feeding an external stream containing C 8 aromatics to the para-xylene adsorption separation device.

17. The process according to claim 16 , wherein a mass ratio of the external stream containing C 8 aromatics component to the adsorption residual oil obtained in step (1) is 0.1 to 0.8.

18. The process according to claim 1 , wherein the C 8 aromatics feed stream contains 10 to 25 mass % of C 8 aromatics.

19. The process according to claim 1 , wherein the adsorption residual oil obtained in step (1) or the external stream containing C 8 aromatics contains not more than 3 mass % of C 8 aromatics.

20. The process according to claim 1 , wherein the xylene isomerization catalyst in step (3) comprises 15-90 mass % of a zeolite and 10-85 mass % of alumina, wherein the zeolite is ZSM-5, ZSM-11, or a mixture thereof.

21. The process according to claim 1 , wherein the xylene isomerization catalyst comprises 15-90 mass % of a zeolite, 1-5 mass % of mordenite, and 5-84 mass % of alumina, wherein the zeolite is ZSM-5, ZSM-11, or a mixture thereof.

Assignees

• China Petroleum & Chem Corp
• Sinopec Res Inst Petroleum

Inventors

• Yang Yanqiang
• Wang Dehua
• Wang Huiguo
• Ma Jianfeng
• Wang Hongchao
• Li Ben
• Liu Yusi
• Qiao Xiaofei
• Gao Ningning

Classifications

• C07C5/2737 Primary

  with crystalline alumino-silicates, e.g. molecular sieves · CPC title

• C07C7/13 Primary

  by molecular-sieve technique · CPC title

• C07C2529/80

  Mixtures of different zeolites · CPC title

• C07C7/12 Primary

  by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers · CPC title

• C07C2529/44

  Noble metals · CPC title