Method for producing 1-octene from crack-C
View Patent ↗The invention relates to a process for preparing 1-octene from a C 4 fraction from a cracker by telomerization of the 1,3-butadiene present in the C 4 fraction from a cracker by means of methanol in the presence of a catalyst, hydrogenation of the telomer obtained in this way, dissociation of the hydrogenated telomer and work-up of the resulting dissociation product to give pure 1-octene.
1. Process for preparing 1-octene comprising:
a) reacting catalytically a butadiene-containing stream with methanol to give a stream comprising at least 1-methoxy-2,7-octadiene,
b) hydrogenating catalytically the 1-methoxy-2,7-octadiene-containing stream to give a stream comprising at least 1-methoxyoctane, and
c) dissociating catalytically at least part of the 1-methoxyoctane to give a dissociation product comprising at least water and 1-octene,
wherein
d) the dissociation product from c) is separated by distillation into a gaseous low-boiling fraction comprising at least 1-octene and water and a liquid high-boiling fraction comprising at least 1-octene and 1-methoxyoctane,
e) the low-boiling fraction is completely or partially condensed and separated into an aqueous phase and a 1-octene-containing, nonpolar phase,
f) the nonpolar phase from e) is recirculated to step d) and
g) the high-boiling fraction from d) is separated into a 1-octene-containing fraction and a 1-methoxyoctane-containing fraction.
2. The process as claimed in claim 1 , wherein d1) the dissociation product from c) comprises dimethyl ether (DME) and is separated by distillation into a low-boiling fraction comprising at least DME and a high-boiling fraction which is at least partly passed to step d).
3. The process as claimed in claim 2 , wherein the high-boiling fraction from d1) comprises methanol and is washed with water to give a methanol-containing aqueous stream and a nonpolar stream which is passed to step d).
4. The process as claimed in claim 1 , wherein d2) comprises methanol as dissociation product from c) and is washed with water to give a methanol-containing, aqueous stream and a nonpolar stream which is passed at least partly to step d).
5. The process as claimed in claim 4 , wherein the nonpolar stream comprises at least DME and is separated by distillation into a low-boiling fraction comprising at least DME and a high-boiling fraction which is passed to step d).
6. The process as claimed in claim 1 , wherein the 1-octene-containing fraction from g) is separated in a step h) into a fraction comprising at least 1-octene and a fraction comprising at least C 8 - and C 9 -olefins.
7. The process as claimed in claim 1 , wherein the 1-methoxyoctane-containing fraction from g) is separated in a step i) into a low-boiling fraction comprising 1-methoxyoctane and a high-boiling fraction comprising at least dioctyl ether.
8. The process as claimed in claim 7 , wherein the low-boiling fraction is recirculated to step c).
9. The process as claimed in claim 1 , wherein k) the step a) comprises, after the catalytic reaction, a distillation step in which the C 4 -hydrocarbons are separated off by distillation and the remaining stream which has a C 4 -hydrocarbon content of less than 5% by weight is passed to step b).
10. The process as claimed in claim 1 , wherein l) the stream from step b) is separated by distillation into a low-boiling fraction comprising at least methanol, 3-methoxyoctane and C 8 -hydrocarbons and a low-boiling fraction comprising at least 1-methoxyoctane and the high-boiling fraction is passed to step c).
11. The process as claimed in claim 3 , wherein the methanol and/or the water is/are separated off from the aqueous, methanol-containing stream in a step o).
12. The process as claimed in claim 11 , wherein the aqueous phase from step e) is likewise fed to step o).
13. The process as claimed in claim 11 , wherein the low-boiling fraction from step e) is likewise fed to step o).
14. The process as claimed in claim 11 , wherein an organic phase is separated off from the stream in step o) and the aqueous phase is separated by distillation into a low-boiling fraction comprising methanol and a high-boiling fraction comprising water.
15. The process as claimed in claim 14 , wherein the organic phase is separated off by extraction.
16. The process as claimed in claim 11 , wherein all or part of the methanol is recirculated to step a) (telomerization).