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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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