The Catalyst Review June 2017 - 8

SPECIAL FEATURE
One group of the bio-polymer production processes Figure 1: Bio-plastics supply chain and main competencies.
is based on polymers which are produced directly
by a micro-organism through fermentation
of biomass or other suitable feedstock, e.g.,
polyhydroxyalkanoates (PHA). The other group
regards bio-polymers in which the monomers
or other precursors are produced by a microorganism and are bio-based; then these monomers
are polymerized via a conventional chemical
polymerization. Examples include polylactic
acid (PLA) from the lactic acid monomer or biopolyethylene (PE) from the bio-ethylene monomer.
Table 1 lists the polymerization routes and bio-based
carbon content of some bio-polymers of interest
for this article. In Figure 1 you can see depicted all
the steps of the bio-plastics supply chain and the
Source: Ravenstijn 2014 modified by the Author
main competencies needed in the production steps
related to the
building blocks, bio- Table 1: Bio-based carbon content of some bio-polymers.
polymers and bioplastics compound
formulations. Since
2010, when Braskem
announced its
green polyethylene
from bio ethanol,
several other biobased monomer
initiatives have
subsequently been
announced. Rather
than looking at new
bio-plastics which Source: Nova Institute 2015 modified by the Author
require considerable
expense and time to commercialize, the bioFigure 2: Bio-based feedstock vs. building blocks.
plastics activities have essentially focused on the
development of "drop in" replacements for the
existing chemical building blocks. These monomers
are chemically identical to their petrochemical
counterparts and so can be used in the existing
capital assets in place. However, since the starting
point is no longer oil, new infrastructure may be
required to actually produce these intermediates.
Many initiatives have been started to develop a wide
range of building blocks and monomers (from C2
to C6) from renewable resources (Figure 2 shows a
scheme depicting the flow between the feedstock
and these building blocks). In the following sections,
some monomers and building blocks of interest for
Source: Tecnon Orbichem 2013 modified by the Author
this article, such as ethylene and other light olefins,
succinic acid, butanediol (BDO), propanediol (PDO), and isosorbide, are described.
The global olefins market is driven by demand for light olefins, specifically C2 ethylene and C3 propylene as the two highest-volume
production chemicals in the world, followed by C4 olefins, such as butadiene and isobutene. The main use for light olefins is as
monomer feedstock for production of the most popular plastics, such as polyethylene (PE) and polypropylene (PP), that have grown
to become an industry with global production capacity of over 190 million of tons/yr. in 2016 (Ali 2016a). Ethylene is also a key
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The Catalyst Review

June 2017

The Catalyst Review June 2017

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