Anhydrous Alcohol

8/7/2019 Anhydrous Alcohol

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Anhydrous Alcohol

Fermentation Industry


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The composition of vapor in

equilibrium with liquid on horizontal

line

Alcohol cant not be made stronger

than 95% by rectification

Why?

Constant Boiling Mixture


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Constant Boiling Mixtures An azeotrope is a mixture of two or more liquids in such

a ratio that its composition cannot be changed by simple

distillation This occurs because, when an azeotrope is

boiled, the resulting vapor has the same ratio of

constituents as the original mixture.

Because their composition is unchanged by distillation,

azeotropes are also called (especially in older texts)

constant boiling mixtures.

Azeotropes consisting of two constituents are called

binary azeotropes.

Those consisting of three constituents are called ternary

azeotropes.


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Minimum and Maximum Boiling

Azeotropes


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Anhydrous Alcohol

Absorbing 4 to 5%water from 95%alcohol

by quicklime with subsequent distillation

Expensive Forms azeotrope


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Minimum constant boiling mixtures

Boiling at temp. lower than 95% alcohol or water

Using benzene as the third component

Two homogenous mixtures

A heterogeneous mixture

ternary

Same concept can be used for separation of

organic liquids such as propyl alcohol and for

removing water formed in sulfonation

(benznesulfonic acid) and esterification (ethyl

acetate)


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Ternary ( boiling at 64.85C) (F)

starting composition must lie on

line CF to ensure that removal

of cbm will leave alcohol in still.

If the starting mixture is made

of adding benzene to

95%alcohol , starting

composition must lie on line

EB. Hence G represents

starting composition

Ifenough benzene is added

tothe 95% alcohol,constant

distillation wouldgive

ternaryconstant boiling

mixtureattopofcolumnand

absolutealcoholatthe

bottom ofthecolumn

Mand N represents the separationofcondensate intotwoliquidlayesTheratiooftop N to bottom layerM is equaltoMF/FN or84:16


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New Concepts

Dual distillation requires

Much more energy, exception being vacuum

distillation

Aluminum oxide and silicon oxide

Use liquid carbon dioxide to extract alcohol and

then depressurizing to flash off carbon dioxide

Other solvents such as dibutyl phthalate underinvestigation due to their solubility in alcohol

Cellulose or corn meal to adsorb water


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Energy Demand Cutoff

Much favored because of gasohol production

Energy liberated by burning 1L of 100% alcohol

is about 23MJ

Fermentation processes consume more than

42MJ

To make production viable require process that

need less energy Recent processes cut off energy demand to 11-

1.5MJ


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Thanks

Good Luck

Anhydrous Alcohol

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