Combined heavy reformate dealkylation-transalkylation process for maximizing xylenes production
The present invention relates to a method of forming mixed xylenes from a heavy reformate using a dealkylation-transalkylation system that includes the step of introducing a heavy reformate containing methyl ethyl benzenes and tri-methyl benzenes and sufficiently free of toluene into the dealkylation stage with a hydrogen-containing material such that the heavy reformate and the hydrogen-containing material intermingle and contact a hydrodealkylation catalyst. The dealkylation-transalkylation system includes dealkylation stages, non-aromatic product gas separations and transalkylation stages. The BTEX component toluene forms from the reaction of methyl ethyl benzenes and hydrogen in the presence of the hydrodealkylation catalyst. The method also includes the step of introducing a dealkylated heavy reformate into the transalkylation stage such that the dealkylated heavy reformate contacts a transalkylation catalyst, forming a transalkylation stage product mixture that includes mixed xylenes.
1. A dealkylation-transalkylation system that is useful for forming mixed xylenes from a heavy reformate that includes both methyl ethyl benzenes and tri-methyl benzenes comprising:
a dealkylation stage that contains a hydrodealkylation catalyst, that is operable to receive both a hydrogen-containing material and the heavy reformate, and that is operable to produce a dealkylation stage product that contains toluene, tri-methyl benzenes and non-aromatic product gas;
a non-aromatic product gas separations stage that is fluidly coupled to the dealkylation stage, that is operable to receive the dealkylation stage product, and that is operable to produce separately the non-aromatic product gas and a dealkylation heavy reformate that contains toluene and tri-methyl benzenes; and
a transalkylation stage that is fluidly coupled to the non-aromatic product gas separations stage, that contains a transalkylation catalyst, that is operable to receive the dealkylation heavy reformate, and that is operable to produce a transalkylation stage product that contains mixed xylenes;
a recycle loop that fluidly couples the dealkylation stage to the non-aromatic product gas separations stage and that is operable to convey hydrogen to the dealkylation stage;
wherein the hydrodealkylation catalyst is operable to selectively convert methyl ethyl benzenes and hydrogen into toluene and the non-aromatic product gas;
wherein the transalkylation catalyst is operable to selectively convert tri-methyl benzenes and toluene into mixed xylenes;
wherein the hydrodealkylation catalyst and the transalkylation catalyst are not the same material, and
wherein the hydrodealkylation catalyst and the transalkylation catalyst are not contained in the same stage.
2. The system of claim 1 , wherein the non-aromatic product gas separations stage and the dealkylation stage are part of the same vessel.
3. The system of claim 1 , further comprising a post-dealkylation-transalkylation refining system that fluidly couples to the transalkylation stage, that is operable to receive the transalkylation stage product and that is operable to produce a benzene product, a toluene product, a mixed xylenes product and a C9+ alkyl aromatics.
4. The system of claim 3 , further comprising a recycle loop that fluidly couples the dealkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey the C9+ alkyl aromatics to the dealkylation stage.
5. The system of claim 3 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the benzene product to the transalkylation stage.
6. The system of claim 3 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the toluene product to the transalkylation stage.
7. The system of claim 3 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the mixed xylene product to the transalkylation stage.
8. The system of claim 3 , where the post-dealkylation-transalkylation refining system is further operable to produce a para-xylene product, an ortho-xylene product and a meta-xylene product from the mixed xylenes.
9. The system of claim 8 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the meta-xylene product to the transalkylation stage.
10. The system of claim 1 , wherein the transalkylation stage comprises a fluidized catalyst bed.
11. The system of claim 1 , wherein the transalkylation stage comprises a moving catalyst bed.
12. A dealkylation-transalkylation system that is useful for forming mixed xylenes from a heavy reformate that includes both methyl ethyl benzenes and tri-methyl benzenes comprising:
a dealkylation stage that contains a hydrodealkylation catalyst, that is operable to receive both a hydrogen-containing material and the heavy reformate, and that is operable to produce a dealkylation stage product that contains toluene, tri-methyl benzenes and non-aromatic product gas;
a non-aromatic product gas separations stage that is fluidly coupled to the dealkylation stage, that is operable to receive the dealkylation stage product, and that is operable to produce separately the non-aromatic product gas and a dealkylation heavy reformate that contains toluene and tri-methyl benzenes; and
a transalkylation stage that is fluidly coupled to the non-aromatic product gas separations stage, that contains a transalkylation catalyst, that is operable to receive the dealkylation heavy reformate, and that is operable to produce a transalkylation stage product that contains mixed xylenes;
a post-dealkylation-transalkylation refining system that fluidly couples to the transalkylation stage, that is operable to receive the transalkylation stage product and that is operable to produce a benzene product, a toluene product, a mixed xylenes product and a C9+ alkyl aromatics;
a recycle loop that fluidly couples the dealkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey the C9+ alkyl aromatics to the dealkylation stage;
wherein the hydrodealkylation catalyst is operable to selectively convert methyl ethyl benzenes and hydrogen into toluene and the non-aromatic product gas;
wherein the transalkylation catalyst is operable to selectively convert tri-methyl benzenes and toluene into mixed xylenes;
wherein the hydrodealkylation catalyst and the transalkylation catalyst are not the same material, and
wherein the hydrodealkylation catalyst and the transalkylation catalyst are not contained in the same stage.
13. The system of claim 12 , wherein the non-aromatic product gas separations stage and the dealkylation stage are part of the same vessel.
14. The system of claim 12 , further comprising a recycle loop that fluidly couples the dealkylation stage to the non-aromatic product gas separations stage and that is operable to convey hydrogen to the dealkylation stage.
15. The system of claim 12 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the benzene product to the transalkylation stage.
16. The system of claim 12 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the toluene product to the transalkylation stage.
17. The system of claim 12 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the mixed xylene product to the transalkylation stage.
18. The system of claim 12 , where the post-dealkylation-transalkylation refining system is further operable to produce a para-xylene product, an ortho-xylene product and a meta-xylene product from the mixed xylenes.
19. The system of claim 18 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the meta-xylene product to the transalkylation stage.
20. The system of claim 12 , wherein the transalkylation stage comprises a fluidized catalyst bed.
21. The system of claim 12 , wherein the transalkylation stage comprises a moving catalyst bed.
22. A dealkylation-transalkylation system that is useful for forming mixed xylenes from a heavy reformate that includes both methyl ethyl benzenes and tri-methyl benzenes comprising:
a dealkylation stage that contains a hydrodealkylation catalyst, that is operable to receive both a hydrogen-containing material and the heavy reformate, and that is operable to produce a dealkylation stage product that contains toluene, tri-methyl benzenes and non-aromatic product gas;
a non-aromatic product gas separations stage that is fluidly coupled to the dealkylation stage, that is operable to receive the dealkylation stage product, and that is operable to produce separately the non-aromatic product gas and a dealkylation heavy reformate that contains toluene and tri-methyl benzenes; and
a transalkylation stage that is fluidly coupled to the non-aromatic product gas separations stage, that contains a transalkylation catalyst, that is operable to receive the dealkylation heavy reformate, and that is operable to produce a transalkylation stage product that contains mixed xylenes;
a post-dealkylation-transalkylation refining system that fluidly couples to the transalkylation stage, that is operable to receive the transalkylation stage product and that is operable to produce a benzene product, a toluene product, a mixed xylenes product and a C9+ alkyl aromatics,
where the post-dealkylation-transalkylation refining system is further operable to produce a para-xylene product, an ortho-xylene product and a meta-xylene product from the mixed xylenes;
wherein the hydrodealkylation catalyst is operable to selectively convert methyl ethyl benzenes and hydrogen into toluene and the non-aromatic product gas;
wherein the transalkylation catalyst is operable to selectively convert tri-methyl benzenes and toluene into mixed xylenes;
wherein the hydrodealkylation catalyst and the transalkylation catalyst are not the same material, and
wherein the hydrodealkylation catalyst and the transalkylation catalyst are not contained in the same stage.
23. The system of claim 22 , wherein the non-aromatic product gas separations stage and the dealkylation stage are part of the same vessel.
24. The system of claim 22 , further comprising a recycle loop that fluidly couples the dealkylation stage to the non-aromatic product gas separations stage and that is operable to convey hydrogen to the dealkylation stage.
25. The system of claim 22 , further comprising a recycle loop that fluidly couples the dealkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey the C9+ alkyl aromatics to the dealkylation stage.
26. The system of claim 22 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the benzene product to the transalkylation stage.
27. The system of claim 22 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the toluene product to the transalkylation stage.
28. The system of claim 22 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the mixed xylene product to the transalkylation stage.
29. The system of claim 22 , further comprising a recycle loop that fluidly couples the transalkylation stage to the post-dealkylation-transalkylation refining system and that is operable to convey at least a portion of the meta-xylene product to the transalkylation stage.
30. The system of claim 22 , wherein the transalkylation stage comprises a fluidized catalyst bed.
31. The system of claim 22 , wherein the transalkylation stage comprises a moving catalyst bed.