Green Chemistry and the Biorefinery - The Economic Utilisation of Food Co-Products - page 19

(Solvay SA) and proplylene diol (Ashland/Cargill) from glycerol feedstocks.
The market volatility in the price of glycerol has caused concern for these
projects, however, the long-term fundamentals remain strong.
Glycerol has been known since 2800 BC mainly as a byproduct of soap
production. 17 Currently, glycerol has numerous applications in personal
care, food, tobacco, detergents, cellophane, explosives and pharmaceuticals. 18
Lengwell and Lesser identified 1582 applications for glycerol in 1945. 19
However, in recent times, many glycerol production plants are closing and
new plants utilising glycerol as a raw material are starting. 20 Global glycerol
production has increased from 60,000 tons in 2001 to 800,000 tons in 2005, partly
due to biodiesel production. The amount of glycerol being used in technical
applications is around 160,000 tons, and this is expected to grow at a rate of
2.8% per year. 21
Glycerol is a raw material for the production of flexible foams and rigid
polyurethane foams. It is known to provide properties including flexibility,
pliability and toughness in surface coatings and paint regenerated cellulose
films, meat casings and special quality papers. 22 Glycerol has the ability to
absorb moisture from the atmosphere and is therefore used in many adhesives
and glues to prevent early drying. In food applications, nontoxic glycerol is
used as solvent, sweetener and preservative. Many polyols such as sorbitol,
manitol and maltitol are used as sugar-free sweeteners; however, they are facing
fierce competition from glycerol. Glycerol has similar sweetness to sucrose and
has the same energy as sugar. Furthermore, it does not raise blood sugar levels
and does not feed plaque bacteria. Glycerol is also employed as an emollient,
humectant and lubricant in many products in the personal care industry
including toothpaste, mouthwashes, shaving cream and soaps. 23
A detailed revision on glycerol transforming processes and applications can
be found in 'The Future of Glycerol- New usages for a raw material' authored
by Mario Pagliaro and Michele Rossi. 23 The topic was published in 2008 and
focuses on key chemical and biochemical transformations with detailed
processing conditions. In this topic, relevant information on the sustainability
and economics of glycerol and biofuels production is discussed. The detailed
synthetic chemistry involved in the transforming processes has also been
reviewed by Behr et al. in his paper entitled ''Improved utilisation of renewable
resources: New important derivatives of glycerol''. 24
A more detailed revision on chemicals that can be derived from glycerol was
conducted in 2008 by Zheng, Chen, and Shen in ''Commodity Chemicals Derived
from Glycerol, an Important Biorefinery Feedstock''. 25 Many important
chemicals have been identified that can be produced from glycerol-derived
platform chemicals and their respective industrial applications are discussed.
Furthermore, this review maps the reaction pathways of a glycerol-derived
platform chemical that can form many other commodity chemicals that are not
easily identifiable. Some of the important commodity chemicals identified include
acrolein, dichloropropanol, epichlorohydrin, dihydroxyacetone, 1,3-propanediol,
1,2-propanediol, glycerol carbonate, diacylglycerol (DAG), monoglyceride
(MG), oxygenate fuels, glyceric acid, tartronic acid, and mesoxalic acid.

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