Reactive Distillation

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Reactive Distillation

• Reading - 3 Articles
• CH EN 4253
• Terry A. Ring

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Comparison of Processes for MeAC
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Requirements

• Mild Reaction Conditions
• Catalyzed Reaction
• Homogeneous Catalyst
• Heterogeneous Catalyst
• Adjustment of Operating Pressure/Temperature
• To give high reaction rate
• To allow separations
• Control Distillation Column
• Want high reactant concentration in reactive zone
• More temperature controllers on system

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Distillation

• Tray Columns

• Packed Columns

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Height of Transfer Unit
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Reaction types

• A?? R S
• A B ?? R
• A B ?? R S

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Catalysis

• Contact with Liquid and Gas

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Catalyst
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Phenomenon
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Examples of Reactive Distillation

• 2 C5 ?? C4 C6
• EO H2O ?? Ethylene Glycol
• Methanol methyl butene ??Tert amyl methyl ether
  (TAME)
• Acetic Acid MeOH ?? Methyl Acetate H2O
• MTBE

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2 C5 ?? C4 C6

• Catalyst
• The Grubbs' catalyst is a ruthenium carbenoid.
• molybdenum(VI )-based catalysts
• tungsten(VI)-based catalysts
• Note Extra Temperature Controllers

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EO H2O ?? Ethylene Glycol

• Catalyst
• Sulfuric Acid
• EO flow controller
• Determines production rate
• H2O (excess) flow controller is really a ratio
  controller to provide the reaction stoichiometry
• H2O (excess) is recycled
• Temperature Controllers
• Reaction kinetics

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Excess B (Heavy) reactant

• Needs 2nd Recovery Column

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AB?? CD

• More Complicated Case
• One or two Distillation Units
• Depends on Boiling points, A, B, C, D

Excess Reactant B
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Use of Inerts in Reactive Distillation

• Iso butane ethanol ?? Ethyl tert-butyl ether
• Catalyst
• Solid Acid on SiO2
• Inerts Control Reaction Rate and Thermal Run away

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TAME process

• Methanol methyl butene
• ??Tert amyl methyl ether (TAME)
• 4 bar Pressure
• Inerts iso-pentane
• Catalyst
• ion-exchange resin bead catalysts

Water is used to break an i-C5/methanol azeotrope
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Methyl Acetate Process

• Acetic Acid MeOH ?? Methyl Acetate H2O
• Catalyst - H2SO4

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Reactive Distillation in Process Simulation

• Aspen
• RadFrac

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Reactive Distillation in Process Simulation

• ProMax
• All Separate Units
• Reactor
• Reaction Phases
• Liquid
• Vapor
• Lower ½ of Distillation Column
• reboiler
• Upper ½ of Distillation Column
• condenser
• Mixer
• Flash (no Q stream)