Separation method of aromatic compounds comprising simulated moving bed xylene mixture pre—treatment process and additional xylene isomerization process

1. A method for separating aromatic compounds using a simulated moving bed adsorptive chromatography and a crystallization process, comprising:

removing a non-aromatic compound from a mixture of aromatic compounds having 7 or less carbon atoms by a sulfolan process;

fractionating benzene/toluene;

fractionating an aromatic compound which separates aromatic compounds having 8 or more carbon atoms;

selectively disproportionating toluene;

transalkylating;

crystallizing to separate para-xylene;

separating para-xylene with a simulated moving bed; and

isomerizing xylene;

pretreating a xylene mixture with the simulated moving bed between the fractionating the aromatic compound step and the separating the para-xylene with the simulating moving bed step; and

an additional isomerizing of xylene to which the xylene mixture from the simulated moving bed xylene mixture pretreating is inputted, wherein

a resultant of the sulforan process is inputted to the fractionating of benzene/toluene step,

the toluene from the fractionating of benzene/toluene is inputted to the selectively disproportionating of toluene step and the transalkylating step,

some of the resultant of the selective disproportionating of toluene step is inputted again to the fractionating of benzene/toluene step,

a residual amount of the resultant of the selective disproportionating of toluene step is inputted to an additional benzene/toluene fractionating step,

the toluene separated from the additional benzene/toluene fractionating step is inputted to the selective disproportionating of toluene step again,

a xylene mixture separated from the additional benezene/toluene fractionating is inputted to the crystallizing for para-xylene separation step,

a residual xylene mixture other than the para-xylene is inputted to the simulated moving bed separating of para-xylene step,

the xylene mixture from the fractionating the aromatic compound step is inputted to the simulated moving bed separating the para-xylene, and

the xylene mixture from the simulated moving bed separating the para-xylene step is inputted to the isomerizing the xylene step.

2. The method for separating aromatic compounds according to claim 1 , wherein the pre-treating the xylene mixture step and the additional isomerizing the xylene step comprise the following steps:

(1) inputting a part of a xylene mixture that is to be inputted to the simulated moving bed separating the para-xylene step, to the simulated moving bed pre-treating the xylene mixture step;

(2) inputting a xylene mixture containing 80% by weight or more para-xylene in the resulted product obtained from said simulated moving bed pre-treating the xylene mixture, to the crystallizing step for para-xylene separation, and the remaining portion of the xylene mixture is inputted to the additional isomerizing the xylene step;

(3) re-inputting the resulted product obtained from the additional isomerizing the xylene step to the fractionating the aromatic compound step.

3. The method for separating aromatic compounds according to claim 2 , wherein a part of the xylene mixture containing 80% by weight or more para-xylene to be inputted to the crystallizing step for para-xylene separation of the step (2), is inputted to the separating para-xylene with the simulated moving bed step.

4. The method for separating aromatic compounds according to claim 2 , wherein a portion of the resulted products from the additional isomerizing of xylene step which are to be inputted to the fractionating of the aromatic compound of the step (3), is inputted to the fractionating of benzene/toluene step.

5. The method for separating aromatic compounds according to claim 1 , wherein the toluene is additionally supplied to the selective disproportionating of toluene step.

6. The method for separating aromatic compounds according to claim 1 , wherein the xylene mixture is additionally supplied to the fractionating of the aromatic compound step.

7. The method for separating aromatic compounds according to claim 2 , wherein the toluene is additionally supplied to the selective disproportionating of toluene step.

8. The method for separating aromatic compounds according to claim 3 , wherein the toluene is additionally supplied to the selective disproportionating of toluene step.

9. The method for separating aromatic compounds according to claim 4 , wherein the toluene is additionally supplied to the selective disproportionating of toluene step.

10. The method for separating aromatic compounds according to claim 2 , wherein the xylene mixture is additionally supplied to the fractionating of the aromatic compound step.

11. The method for separating aromatic compounds according to claim 3 , wherein the xylene mixture is additionally supplied to the fractionating of the aromatic compound step.

12. The method for separating aromatic compounds according to claim 4 , wherein the xylene mixture is additionally supplied to the fractionating of the aromatic compound step.

13. A method for separating aromatic compounds, comprising:

inputting a resultant of a sulfolan process which is a non-aromatic compound removed from a mixture of aromatic compounds having 7 or less carbon atoms to a fractionating of benzene/toluene step;

inputting toluene from the fractionating of benzene/toluene to a selective toluene disproportionating step and a transalkylating step;

inputting at least one resultant of the selective toluene disproportionating step to the fractionating of benzene/toluene step;

inputting a residual amount of the resultant of the selective disproportionating of toluene step to an additional step of fractionating benzene/toluene;

inputting the toluene separated from the additional fractionating of benzene/toluene step to the selective disproportionating of toluene step;

inputting a xylene mixture separated from the additional fractionating of benzene/toluene step to a crystallizing for para-xylene separation step;

inputting a residual xylene mixture other than the para-xylene to a step of separating para-xylene with a simulated moving bed;

inputting the xylene mixture from an aromatic compound fractionation to the step of separating para-xylene with the simulated moving bed, wherein

the aromatic compound fractionation separates aromatic compounds having 8 or more carbon atoms;

inputting the xylene mixture from the simulated moving bed para-xylene separating step to a xylene isomerizating step;

the pretreating of the xylene mixture with the simulated moving bed being between the aromatic compound fractionating and the simulated moving bed para-xylene separating; and

isomerizing an additional of the xylene mixture from the simulated moving bed xylene mixture pretreating.

14. The method for separating aromatic compounds according to claim 13 , wherein the pre-treating the xylene mixture step and the additional isomerizing the xylene step comprises:

(1) inputting a part of a xylene mixture that is to be inputted to the simulated moving bed para-xylene separating step, to the simulated moving bed xylene mixture pre-treating step;

(2) inputting a xylene mixture containing 80% by weight or more para-xylene in the resulted product obtained from said simulated moving bed xylene mixture pre-treating step, to the crystallizing for para-xylene separation step, wherein,

a remaining portion of the xylene mixture is inputted to the additional isomerizing of xylene step;

(3) re-inputting the resulted product obtained from the additional xylene isomerizing step to the step of fractionating the aromatic compound.

15. The method for separating aromatic compounds according to claim 14 , wherein a part of the xylene mixture containing 80% by weight or more para-xylene to be inputted to the crystallizing for para-xylene separation of the step (2), is inputted to the simulated moving bed separating step.

16. The method for separating aromatic compounds according to claim 14 , wherein a portion of the resulting products from the additional xylene isomerizing step which are to be inputted to the aromatic compound fractionating of the step (3), is inputted to the fractionation of benzene/toluene step.

17. The method for separating aromatic compounds according to claim 13 , wherein the toluene is additionally supplied to the step of selective disproportionating of toluene.

18. The method for separating aromatic compounds according to claim 13 , wherein the xylene mixture is additionally supplied to the fractionating of the aromatic compound step.