Environmental Engineering Reference
In-Depth Information
in multiple ways to provide mainstream industrial chemicals. Esterification
provides butyl acetate, a major industrial solvent, and butyl acrylate monomers,
which are the largest-volume commercial derivatives of butanol. Butyl phthalate
is a common plasticiser, while butyl paraben is widely used in personal care
formulations. Ethers of butanol also find sundry markets as solvents and
monomers. Dibutyl ether in particular is also a diesel additive of considerable
interest [203]. Finally, functional derivatives of butanol, such as amines, are used
in the production of agrochemicals and various other commodities.
Butanol can be catalytically oxidised to either butanal or butanoic acid, both of
which branch out towards their own sets of derivative markets. Alternatively,
dehydration gives 1-butene or, under some conditions, mixtures of 1- and
2-butenes. Butenes are a highly versatile platform in their own right, serving as a
feedstock for alkylate gasoline, a high-octane C
7
-C
9
product that is widely used in
commercial fuels. An alternative, cationic oligomerisation of butanes, leads to a
mixture of C
8
and C
12
alkane products called polymer gasoline. The largest non-
fuel market for butenes is in polymer formulations, that is, in polybutene,
polybutylene oxide and as a co-monomer with ethylene in polyethylene-type
polymers. Sec-butanol, available by hydration of
n
-butanol, is useful solvent
alcohol with its own range of applications. Simple hydrogenation of butene gives
butane, which is an important component of winter blend gasolines.
The dehydrogenation of butene to 1,3-butadiene is a mature technology, and the
vast market of butadiene is chiefly applied to the production of synthetic
elastomers. Isobutene is available from
n
-butenes by isomerisation, with multiple
additional applications to elastomers, polymers and industrial chemicals.
The virtually unlimited market reach of butanol in transportation fuels, materials
and chemicals provides a strong impetus for the biotechnological approach to
biomass valorisation to transition away from ethanol towards butanol. The full
realisation of this goal however awaits further refinements in biobutanol production
and the commercialisation of these technologies.
4.8.4
Triglyceride Platform: Extraction
Triglycerides are the main component of plant and animal lipids and they, along
with their constituent glycerol and fatty acids, have been utilised as building
blocks for chemical production since antiquity. Triglycerides are composed of
esters of long-chain fatty acids bonded to a central glycerol (1,2,3-trihydroxy-
propane) unit, therefore containing a total of three esters. Each fatty acid chain
can be different to the others of the same triglyceride and therefore vegetable
oils are not typically one distinct molecule but a range of different molecules. It
is for this reason that vegetable oils are typically viewed as a 'platform' (i.e.
triglyceride platform) rather than as individual platform molecules. Instead, the
constituent fragments of triglycerides are seen as individual platform molecules
(e.g. ricinoleic acid, oleic acid and glycerol), some of which are highlighted
