Method for purification of mixtures comprising MTBE as well as production of isobutene by splitting of mixtures comprising MTBE
View Patent ↗The present invention relates to a process for efficient purification of MTBE-containing mixtures and for preparation of isobutene by cracking of MTBE-containing mixtures.
1. A process for purifying technical MTBE, the process comprising distillatively separating a technical MTBE (I) comprising MTBE, methanol, C 4 hydrocarbons, C 5 hydrocarbons and acetone, into:
a top product (II) comprising C 4 and C 5 hydrocarbons,
a side stream (III) comprising acetone, methanol and MTBE, and
a bottom product (IV) comprising MTBE.
2. The process according to claim 1 , wherein the bottom product (IV) comprises less than 50% by mass of the acetone present in the technical MTBE (I).
3. The process according to claim 1 , wherein the separating is performed in a distillation column and the side stream (III) is withdrawn in liquid form.
4. The process according to claim 1 , further comprising distillatively separating the bottom product (IV) into a top product (VI) comprising MTBE and a bottom product (V) comprising higher-boiling components than MTBE.
5. The process according to claim 4 , wherein the top product (VI) has a concentration of less than 2500 ppm by mass of 2-methoxybutane.
6. The process according to claim 4 , wherein the bottom product (IV) or the top product (VI) comprises less than 50 ppm by mass of acetone.
7. The process according to claim 4 , further comprising catalytically cracking the top product (VI) to obtain a cracking product (VII) comprising MTBE, isobutene and methanol.
8. The process according to claim 7 , wherein the cracking is performed over a solid catalyst in a gas phase within a temperature range from 150 to 500° C.
9. The process according to claim 7 , comprising separating the cracking product (VII) in a further distillation into a top product (IX) comprising isobutene and a bottom product (VIII) comprising MTBE and methanol.
10. The process according to claim 9 , wherein the top product (IX) comprises less than 10 ppm by mass of acetone.
11. The process according to claim 9 , comprising removing methanol by extraction, dimethyl ether by distillation, or both, from the top product (IX).
12. The process according to claim 11 , wherein the removing comprises:
extraction by means of an extractant;
removing an extraction stream (XI) comprising methanol; and
removing a stream (X) comprising isobutene.
13. The process according to claim 12 , comprising separating the extraction stream (XI) by a distillation into a top product (XII) comprising methanol and a bottom product (XIII) comprising the extractant.
14. The process according to claim 9 , wherein the bottom product (VIII) is fully or partly recycled into the distillatively separating of the technical MTBE into a top product (II), a side stream (III), and a bottom product (IV).
15. The process according to claim 14 , wherein the bottom stream (VIII) is separated in a distillation into a bottom product (XVIII) comprising methanol and a top product (XVII) comprising MTBE, and
the top product (XVII) is recycled fully or partly into the distillatively separating of the technical MTBE into a top product (II), a side stream (III), and a bottom product (IV).
16. The process according to claim 14 , wherein the bottom stream (VIII), a further stream (XXI) comprising methanol and a stream (XX) comprising isobutene are supplied to an MTBE synthesis (S 1 ); and
a product (XXII) comprising MTBE is recycled fully or partly into the distillatively separating of the technical MTBE into a top product (II), a side stream (III), and a bottom product (IV).
17. The process according to claim 2 , wherein the separating is performed in a distillation column and the side stream (III) is withdrawn in liquid form.
18. The process according to claim 2 , further comprising distillatively separating the bottom product (IV) into a top product (VI) comprising MTBE and a bottom product (V) comprising higher-boiling components than MTBE.
19. The process according to claim 3 , further comprising distillatively separating the bottom product (IV) into a top product (VI) comprising MTBE and a bottom product (V) comprising higher-boiling components than MTBE.
20. The process according to claim 5 , wherein the bottom product (IV) or the top product (VI) comprises less than 50 ppm by mass of acetone.