HCID 86742457, compound → HCID 19025147, compound

Another embodiment of the present invention is the use of pervaporation membranes to separate alcohols from ethers and/or hydrocarbons in a process for producing high purity alkenes by the decomposition of ethers. FIG. 4 depicts such a process for producing high purity isobutene by the decomposition of MTBE, although the present invention can be applied to other ether decomposition reactions. An impure C4 feed stream 70 is combined with a methanol feed stream 71 and recycled methanol stream 72 and fed to an MTBE synthesis system 74. The MTBE synthesis system 74 produces a MTBE product stream 76. A portion of the MTBE product stream 76 is collected as final MTBE product stream 78, while another portion of the MTBE product stream 76 is taken off at stream 80 and is heated and vaporized in the heat exchanger 81 and subsequently fed to a decomposition reactor 82 containing a fixed bed of acid cation exchange resin. The decomposition reactor 82 decomposes the MTBE feed to produce an effluent stream 83 containing isobutene/methanol/MTBE, which is cooled and condensed in heat exchanger 84 to produce a liquid mixture 85 which is subsequently fed through a pervaporation membrane system 86. The isobutene/methanol/MTBE mixture is separated by the pervaporation membrane system 86 to produce a high purity methanol permeate vapor 87 and a methanol-depleted liquid concentrate reject stream 88. The high purity methanol permeate vapor stream 87 is withdrawn from the membrane system, cooled and condensed if necessary, and subsequently recycled to the MTBE synthesis reactor 74 as stream 72. The methanol-depleted liquid concentrate reject stream 88 from the pervaporation membrane system 86 is fed to a distillation column 89 to undergo separation. The high purity isobutene stream 90 is taken as overhead product, and a high purity MTBE stream 91 is taken as bottom product and recycled to the feed to the MTBE decomposer 82. A liquid side draw containing isobutene/MTBE/methanol is taken from the distillation column 89 as stream 93 and is fed through a pervaporation membrane 94 where it is separated to form a high purity methanol vapor permeate stream 95 and isobutene/MTBE stream 96. The high purity methanol vapor permeate stream 95 is subsequently combined with the methanol permeate stream from the first pervaporation membrane system 86 and recycled as combined methanol stream 72 to the MTBE synthesis step 74. The isobutene/MTBE reject stream 96 from pervaporation membrane system 94 is returned to the distillation column 89 for further separation.

1. temperatureis cooled
2. customcondensed in heat exchanger 84
3. customThe isobutene/methanol/MTBE mixture is separated by the pervaporation membrane system 86
4. customto produce a high purity methanol permeate vapor 87
5. concentrationconcentrate
6. customThe high purity methanol permeate vapor stream 87 is withdrawn from the membrane system
7. temperaturecooled
8. customcondensed if necessary, and
9. concentrationconcentrate
10. distillationis fed to a distillation column 89
11. customseparation
12. additionA liquid side draw containing isobutene/MTBE/methanol
13. distillationis taken from the distillation column 89 as stream 93
14. customis separated

ORD record

ord-78c8fe9280de4960a432d83af7644151

Source dataset

uspto-grants-1988_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04774365