Environmental Engineering Reference
In-Depth Information
Hydrogenations are therefore used to form 1,3-propandiol and propylene glycol
while additional oxidation and dehydration steps yield acrolein, lactic acid and
acrylic acid [236]. Oxidation of glycerol is also possible, forming a range of
hydroxy acids, aldehydes and ketones (such as dihydroxyacetone). Deoxygenation
and dehydroxylation of glycerol can also be used to remove functionality,
eventually yielding alkenes and alkanes which are useful as drop-in replacements
for fossil equivalents [235, 237, 238]. Reaction with dimethyl carbonate or urea is
used to produce glycerol carbonate, useful as a solvent or for a variety of further
transformations [239], while reaction of glycerol with HCl is used to produce
epichlorohydrin. The ketal, solketal, is formed from the reaction of acetone with
glycerol and this protected glycerol is useful in forming mono-, di- and triglycerides
of controlled composition [240]. The Skraup reaction between glycerol and
anilines can be used in the production of substituted quinolones, finding use in
pharmaceuticals, dyes and chelating agents, for example [241]. Glycerol has also
been used for many years in the production of the commercial explosive
nitroglycerine (glycerol trinitrate).
4.9 Conclusion
As the age of cheap oil nears its end and environmental concerns relating to
the extraction of non-sustainable fossil resources apply pressure to the petro-
chemical industry, new sustainable resources for chemicals and materials will
be required. The traditional chemical industry relies heavily on a small set
of base chemical building blocks that are produced globally on an enormous
scale. Within this chapter it has been demonstrated how a new set of bio-
derived building blocks, so call platform molecules, can be used to supplant
these base chemicals and form the cornerstone of a more sustainable chemical
industry that is less reliant on fossil resources. First-hand knowledge from the
authors and a thorough review of recent scientific literature has been used to
compile a list of the most promising platform molecules, giving the reader an
appreciation of the diversity of chemicals readily obtainable from biomass.
The processing technologies involved in the conversion of biomass to chemi-
cals has been reviewed, as has the different constituent parts of biomass and
how these can be used to access different platform molecules. The higher
heteroatom content of platform molecules versus base chemicals has also been
discussed, and the effects of downstream chemistry considered. Finally, four
example platforms or platform molecules, one from each of the core process-
ing technologies, were reviewed in detail, highlighting how each can be used
as a versatile building block that can lead to many other valuable chemicals.
Although drop-in replacements for petrochemicals are in many cases deriva-
ble from biomass, there is also great potential for new chemistry, new materials
and new products to be developed within the context of the biorefinery, and
platform molecules form an essential part of these facilities. Evident from the
