Process for the production of alkyl ethers by the etherification of isobutene

Patent metadata

Field	Value
Publication number	US-9403744-B2
Application number	US-37373007-A
Country	US
Kind code	B2
Filing date	Jul 12, 2007
Priority date	Jul 18, 2006
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

Process for the production of alkyl ethers by the etherification of isobutene, contained in C 4 -C 5 hydrocarbon streams, with linear alcohol, in the presence of acid catalysts, comprising the following essential steps: a) feeding the isobutene contained in C 4 -C 5 hydrocarbon cuts, together with one or more streams containing linear alcohol, to a first reaction step; b) sending the stream leaving the first reaction step to a first distillation area, separating a light stream from a heavy stream containing the desired ether; c) feeding the light stream separated in the first distillation area, together with one or more streams containing linear alcohol, to a second reaction step; d) sending the stream leaving the second reaction step to a second distillation area separating a light stream from a heavy stream containing ether, C 4 hydrocarbons and alcohol which is recycled to the first distillation area; e) sending the light stream in the second distillation area to a recovery section of the linear alcohol contained therein; f) recycling the linear alcohol recovered in the recovery section to at least one of the two reaction steps. The present invention relates to plant solutions which allow the alcohol/isobutene molar ratio to be increased in the reaction steps and therefore maximizing the conversion of isobutene.

First claim

The invention claimed is:

1. A process for production of an alkyl ether, comprising:
a) feeding a C 4 -C 5 hydrocarbon stream comprising isobutene and a stream comprising a linear alcohol, to a first reaction unit;
b) reacting at least a portion of the linear alcohol and isobutene in the presence of an acid catalyst in the first reaction unit to obtain a first reaction stream comprising a ter-butyl ether of the linear alcohol, C 4 -C 5 hydrocarbons, the linear alcohol and unreacted isobutene;
c) removing the first reaction stream from the first reaction unit;
d) sending the first reaction stream to a first distillation unit and separating a light stream comprising an azeotropic mixture of the linear alcohol and the C 4 -C 5 hydrocarbons, and isobutene from a heavy stream comprising the ter-butyl ether;
e) feeding the light stream and a stream comprising the linear alcohol to a second reaction unit;
f) further reacting the linear alcohol and unreacted isobutene to obtain a second reaction stream comprising the ter-butyl ether of the linear alcohol, the C 4 -C 5 hydrocarbons, and the linear alcohol;
g) removing the second reaction stream from the second reaction unit;
h) sending the second reaction stream to a second distillation unit and separating a second light stream consisting of an azeotropic mixture of the linear alcohol and the C 4 -C 5 hydrocarbons from a second heavy stream comprising the ter-butyl ether, part of the C 4 -C 5 hydrocarbons and part of the linear alcohol;
i) sending the second heavy stream to the first distillation unit;
j) sending the second light stream to a linear alcohol recovery unit comprising a water washing column;
k) separating the linear alcohol as a water solution from the C 4 -C 5 hydrocarbons;
l) separating the water from the linear alcohol to obtained recovered linear alcohol; and
m) recycling the recovered linear alcohol to at least one of the first and second reaction units;
wherein
part of the first light stream is condensed and recycled to the first reaction unit; and/or
part of the second light stream is condensed and recycled to at least one of the first and second reaction units, and
wherein the C 4 -C 5 hydrocarbon stream from k) is partly recycled to at least one of the first and second reaction units, and
the linear alcohol is at least one of methanol and ethanol and correspondingly the ter-butyl ether is at least one of methyl ter-butyl-ether and ethyl ter-butyl ether.

2. The process according to claim 1 , wherein the heavy stream containing the ter-butyl ether, separated in the first distillation unit, is sent to a third distillation unit wherein a stream is separated, consisting of substantially pure ter-butyl ether from a stream containing a ter-butyl ether/alcohol azeotropic mixture, which is divided into two streams, one of which is recycled to the first reaction unit, the second is mixed with the stream consisting of the substantially pure ter-butyl ether.

3. The process according to claim 1 , wherein the light condensed stream leaving the first distillation unit is totally or partially sent to a water washing section.

4. The process according to claim 3 , wherein two streams leave the water washing section, one containing water and linear alcohol is sent to the washing column, the other substantially containing C 4 hydrocarbons, is either totally or partially recycled, as reflux, to the first distillation unit.

5. The process according to claim 1 , wherein the light condensed stream leaving the second distillation unit is totally or partially sent to a water washing column.

6. The process according to claim 5 , wherein two streams leave the water washing column, a first stream containing water and linear alcohol sent to the distillation column of the water washing unit downstream of the second distillation area, and a second stream substantially containing C 4 hydrocarbons, either totally or partially recycled, as reflux, to the second distillation unit.

7. The process according to claim 1 , wherein the light stream separated in the first distillation unit is in gaseous form.

8. The process according to claim 1 , wherein the light stream separated in the second distillation unit is in gaseous form.

9. The process according to claim 7 , wherein the light gaseous stream leaving the first distillation area is sent to a quenching section.

10. The process according to claim 9 , wherein two streams leave the quenching section, downstream with respect to the first distillation unit, one containing water and linear alcohol, sent to the washing column the other containing mainly C 4 hydrocarbons, partially sent to the second reaction unit and partially recycled, as reflux, to the first distillation unit.

11. The process according to claim 8 , wherein the light gaseous stream leaving the second distillation unit is sent to another quenching section.

12. The process according to claim 11 , wherein two streams leave the quenching section, downstream with respect to the second distillation unit, one containing water and linear alcohol, sent to the washing column, the other containing mainly C 4 hydrocarbons, partially sent to the washing column, and partially recycled, as reflux, to the second distillation unit.

13. The process according to claim 1 , wherein the second reaction unit comprises at least two reactors in series, between which an intermediate cooling system may optionally be present.

14. The process according to claim 13 , wherein part of the stream leaving the head of the distillation column of the washing step with water is fed to the second or to the last of the reactors in series.

15. The process according to claim 13 , wherein methanol is fed to the second or to the last of the reactors in series.

16. The process according to claim 1 , wherein at least one of the first reaction unit and the second reaction unit comprises at least one of a tubular reactor and an adiabatic reactor.

17. The process according to claim 1 , wherein the a temperature of the first reaction unit and the second reaction unit is from 30 to 100° C., at a pressure lower than 5 MPa and a feeding space velocity lower than 30 h −1 .

18. The process according to claim 17 , wherein the feeding space velocities range from 1 to 15 h −1 .

19. The process according to claim 1 wherein C 4 and C 5 olefins present in the hydrocarbon stream react with the linear alcohol.

20. The process according to claim 1 , wherein the isobutene content in the hydrocarbon stream is modified by dilution with C 4 -C 7 streams.

21. The process according to claim 1 , wherein the acid catalysts comprise sulfonated polymeric resins.

22. The process according to claim 13 , wherein part of the stream leaving the head of the washing column is fed to the second or to the last of the reactors in series.

23. The process according to claim 1 ,
wherein the heavy stream containing the ter-butyl ether, separated in the first distillation unit, is sent to a third distillation unit wherein a stream is separated, consisting of substantially pure ter-butyl ether from a stream containing the ter-butyl ether/alcohol azeotropic mixture, which is divided into two streams, one of which is recycled to the first reaction unit, the second is mixed with the stream consisting of the substantially pure ether.

24. The process according to claim 1 , wherein the alkyl ether is methyl ter-butyl-ether, the linear alcohol is methanol, and wh

Assignees

• Di Girolamo Marco
• Conte Massimo
• Sgambati Antonio
• Cipelli Alberto
• Saipem Spa

Inventors

• Di Girolamo Marco
• Conte Massimo
• Sgambati Antonio
• Cipelli Alberto

Classifications

• C07C41/06 Primary

  by addition of organic compounds only · CPC title

• C07C43/046

  Alkyl tert-alkyl ether, e.g. CH3OC(CH3)3 · CPC title

• C07C43/04 Primary

  Saturated ethers · CPC title