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Matouq, M., T. Tagawa and S. Goto.

 J. Chem. Eng. Jpn. 27 (1994): 302-306

Combine Process for Production of MTBE

from tert -Butyl Alcohol and Methanol

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A+B

C+D

R eaction

Separation

Combined Process Concept

C

D

(Animation)

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R eactive Distillation

RD is a simultaneous implementation of reaction and

separation in a column. Both homogeneous and heterogeneous

can be applied. First Patents in 1920s

The main advantages of RD over the sequential processes of 

reaction and distillation;

1) Simplification of reactants-products separation.

2) Achievement of higher yields for reversible reactions

(equilibrium limited reactions) using solid catalysts.

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Reactive Section

Temperature Indicator 

Voltage and CurrentMonitor 

Stripping 

Section

Pump

Feed

Vents

Distillate

Bottom 

Product

Multi-timer 

Heating Mantle

A + B C + D

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What is oxygenate?

Oxygenates are used as octane booster to promotemore complete combustion of gasoline and to reduce

carbon monoxide (CO) and volatile organic compounds

(VOC¶s) emitted from the exhaust pipes.

Examples of oxygenate are alcohols, e.g. methanol

and ethanol, and their derivative alkyl ethers, e.g. MTBE,

ETBE, TAME, TAEE

MeOH + IB = MTBE

MTBE Synthesis-Commercial Process

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Iso-Butene (IB) CH2=C-CH3

CH3

Methanol (MeOH) CH3-OH

O-CH3

Methyl tert-Butyl Ether (MTBE) CH3-C-CH3

CH3

+

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MeOH + TBA = MTBE + H2O

Synthesis of MTBE from TBA

tert -Butyl alcohol (TBA), which is a major by-product of 

 propylene oxide production from isobutene and propylene,

can be employed instead of IB as a reactant due to theshortage of IB .

However, the following side-reactions can be occurred.

TBA = IB + H2O

MeOH + IB = MTBE

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CH3

tert-ButylAlcohol(TBA) CH3-C- OH

CH3

Methanol (MeOH)

CH3-OH +

O-CH3

Methyl tert-Butyl Ether (MTBE) CH3-C-CH3

CH3

+ H2O

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Drawbacks of RD such as

1) can¶t separate azeotropic mixtures

2) significant energy consumption3) require large difference volatility

To overcome this  drawback , pervaporation unit  was 

applied.

What is pervaporation (PV)?

One of the membrane process.

The name is from permeate + vapor

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The transport mechanism of pervaopration process

1) sorption of liquid into the membrane at the feed side

2) transport (permeate) through the membrane

3) desorption into the vapor  phrase at the permeate side

www.p2pays.org

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Membrane - A material that allows selective permeation of certain molecules. Main classify; organic and

inorganic membrane.

Permeate - The part of the fluid stream that passes through

the membrane.

R etentate - The part of the fluid stream that does not pass

through the membrane.

Advantages of Pervaporation

It enables the separation of a liquid mixture withclose boiling points, azeotropic mixtures, isomers,

and mixtures consisting of heat-sensitive

compounds by partly vaporizing it through a dense

membrane.

Ter minologies of  membr ane pr ocessTer minologies of  membr ane pr ocess

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Feed

Treated Effluent

PervaporationModule

Vacuum

Pump

Condenser

Condensate

Schematic of a typical pervaporation system. 

Pervaporation is one of the membrane separation process. It can be applied as a membrane reactor.

So now we change the present topic to 

membr ane reactor 

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ConceptIntegrating reaction and separation by membrane

in one single unit

Membrane reactors are categorized into two types:

inert membrane reactor (IMR) and catalytic membrane

reactors (CMR)IMR, the catalytically active material does not form

a part of the membrane

Membrane R eactor

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Basic Functions of Membrane R eactors

I) Extractor-removal of reaction product

II) Distributor-addition of reactant

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I) Extractor

 

A+B

Sweep gas

Impermeable wall

D D D

D DSweep gas

Sweep gas, D

Sweep gas, D

DC

R emoval of reaction pr oduct therefore

shif t react ion equilibr i um

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Membrane reactor applications

 I n extract or mod e

1) Pervaporation membrane reactor

MeO

H + TBA MTBE + H2O

Synthesis of MTBE from TBA

By product, water, was removed from ether production

 by pervaporation

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Distillation and

Pervaporation Simple

Combined Process

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Reactant A

Reactant B

Product

II) Distributor

Controlled addition of a reactant.

Limitation of side reactions.

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