MTBE Production from Butane

The process under analysis comprises three major sections: (1) Butane Isomerization; (2) Isobutane Dehydration; and (3) Isobutylene Etherification.

Butane Isomerization. Fresh n-butane, recycled isobutane, and a recovered stream from the Depropanizer downstream are fed to the Deisobutanizer Column. The overhead stream, rich in isobutane, is sent to the Dehydrogenation Preheaters, while the bottom stream containing heavier components is burned as fuel, and a side stream rich in butane is directed to the Isomerization Reactor. Hydrogen recovered from the Cold Box downstream is also fed to this reactor, in which butane is converted into isobutane, and sent to the Lights Removal area, where it is recovered to the Deisobutanizer Column, while a light-ends stream is obtained and burned as fuel.

Isobutane Dehydration. The Deisobutanizer overhead stream is fed to heaters to reach the reaction temperature, and then Dehydrogenation Reactors, where isobutane is converted into isobutylene. A Catalyst Regeneration Unit recovers and returns catalyst to the reactors. The outlet stream from the last reactor is compressed and routed to the Cold Box, where it is liquefied and sent to the Etherification Reactor, while a gaseous stream is routed to a PSA Unit to recover light-ends, burned as fuel, and hydrogen, sent to the Isomerization Reactor upstream.

Isobutylene Etherification. The liquid stream from the Cold Box is mixed with methanol and fed to the Etherification Reactor, where isobutylene is converted into MTBE. The reactor effluent is sent to the Catalytic Distillation Column, where unreacted isobutylene is converted into MTBE, which is recovered from the bottom and sent to storage. The overhead stream is routed to a Wash Column, where methanol is recovered, distilled, and recycled to the reactor, while a hydrocarbon stream is sent to the Depropanizer Column, which recycles a C4 stream to the Deisobutanizer.