Page 75 - Chemical and process design handbook

Speight_Part II_A 11/7/01 3:16 PM Page 2.16

ACETONE

Acetone (dimethyl ketone, 2-propanone, CH COCH , melting point:
3 3
o
o
–94.6 C, boiling point: 56.3 C, density: 0.783) is the simplest ketone and
is a colorless liquid that is miscible in all proportions with water, alcohol,
or ether.
There are two major processes for the production of acetone (2-propanone).
The feedstock for these is either iso-propyl alcohol [(CH ) CHOH] or
3 2
cumene [iso-propyl benzene, C H CH(CH ) ]. In the last few years there has
6 5 3 2
been a steady trend away from iso-propyl alcohol and toward cumene, but
iso-propyl alcohol should continue as a precursor since manufacture of ace-
tone from only cumene would require a balancing of the market with the
coproduct phenol from this process.
Acetone is made from iso-propyl alcohol by either dehydrogenation
o
(preferred) or air oxidation. These are catalytic processes at 500 C and 40
o
to 50 psi. The acetone is purified by distillation, boiling point 56 C and the
conversion per pass is 70 to 85 percent, with the overall yield being in
excess of 90 percent.
CH CH(OH)CH → CH C(=O)CH + H
3 3 3 3 2
2CH CH(OH)CH + O → CH C(=O)CH + 2H O
3 3 2 3 3 2
Cumene is also used as a feedstock for the production of acetone. In this
process, cumene first is oxidized to cumene hydroperoxide followed by the
decomposition of the cumene hydroperoxide into acetone and phenol.
The hydroperoxide is made by reaction of cumene with oxygen at 110 to
o
115 C until 20 to 25 percent of the hydroperoxide is formed. Concentration
of the hydroperoxide to 80% is followed by catalyzed rearrangement under
o
moderate pressure at 70 to 100 C. During the reaction, the palladium chlo-
ride (PdCl ) catalyst is reduced to elemental palladium to produce hydrogen
2
chloride that catalyzes the rearrangement, and reoxidation of the palladium
is brought about by use of cupric chloride (CuCl ) that is converted to
2
cuprous chloride (CuCl). The cuprous chloride is reoxidized during the cat-
alyst regeneration cycle.

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