Page 54 - Chemical and process design handbook

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OXO REACTION

The oxo reaction is the general or generic name for a process in which an
unsaturated hydrocarbon is reacted with carbon monoxide and hydrogen to
form oxygen function compounds, such as aldehydes and alcohols.
In a typical process for the production of oxo alcohols, the feedstock
comprises an olefin stream, carbon monoxide, and hydrogen. In a first step,
the olefin reacts with CO and H2 in the presence of a catalyst (often cobalt)
to produce an aldehyde that has one more carbon atom than the originat-
ing olefin:
RCH=CH + CO + H → RCH CH CH=O
2 2 2 2
This step is exothermic and requires an ancillary cooling operation.
The raw aldehyde exiting from the oxo reactor then is subjected to a
higher temperature to convert the catalyst to a form for easy separation
from the reaction products. The subsequent treatment also decomposes
unwanted by-products. The raw aldehyde then is hydrogenated in the pres-
ence of a catalyst (usually nickel) to form the desired alcohol:
RCH CH CH=O + H → RCH CH CH OH
2 2 2 2 2 2
The raw alcohol then is purified in a fractionating column. In addition
to the purified alcohol, by-products include a light hydrocarbon stream and
a heavy oil. The hydrogenation step takes place at about 150°C under a
pressure of about 1470 psi (10.13 MPa). The olefin conversion usually is
about 95 percent.
Among important products manufactured in this manner are substi-
tuted propionaldehyde from corresponding substituted ethylene, normal
and iso-butyraldehyde from propylene, iso-octyl alcohol from heptene,
and trimethylhexyl alcohol from di-isobutylene.

See Hydroformylation.

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