The Catalyst Review - October 2015 - 9

SPECIal fEaTuRE
C3 Bio-olefins: Bio-Propylene
Propylene is the second largest volume chemical produced in the world, with almost two-thirds of production used to manufacture
polypropylene resins. Steam cracking and fluid catalytic cracking (FCC) of naphtha accounts for approximately 90% of global
propylene production, but the increase in the use of ethane rather than naphtha as feedstock, and its resulting lower propylene
production, has led to increased capacity in on-purpose propylene production through propane dehydrogenation (PDH) and other
technologies.
The real lure of bio-propylene is that it is a drop-in replacement for petrochemical propylene, making it very easy for producers to
bring bio-propylene to downstream products. However, cost, particularly for producing the bio-based feedstock from which biopropylene is processed, remains the biggest barrier, as many technologies used to produce bio-propylene are identical to existing
petrochemical processes.
As with bio-ethylene, there are a
number of different pathways to
produce propylene from bio-based
feedstocks. However, the nascent size
of the bio-propylene market means
no single technology has yet moved
into commercial scale and captured a
significant share of existing production.
The closest to commercial production
of bio-propylene is Braskem, who had
announced plans in 2010 for a plant
that would produce bio-propylene
from its sugarcane ethanol through
dehydration to bio-ethylene then
dimerization and metathesis in a
process identical to the one used with
petrochemical ethanol as feedstock
(Table I). However, Braskem continues
to delay construction and at this time
has not announced any plans to begin
the mothballed project.

Table I: Processes in development to produce bio-propylene.

Source: Author, 2015

Neste Oil Corporation produces renewable diesel from waste and vegetable oils through its NEXBTL process, a by-product of which
is a gas mixture that is more than half propane. The company is spending approximately €60 million (USD $80 million) for a unit
to purify and separate the propane from the gas mix at its Rotterdam refinery with a 30-40 ktpa capacity of bio-propane per year.
Neste has committed to selling the first four years of production to SHV Energy, who will sell the bio-propane further in the European
Market (Neste 2014]. At present, no company has announced plans to use the product with PDH to produce bio-propylene.
Global Bioenergies announced in 2014 the successful development of a bacteria strain that produces propylene in a one-step
fermentation process. However, the process is still only at the laboratory stage (Global Bioenergies 2014). Coskata is developing a
fermentation process to produce propanol from syngas feedstock in partnership with Total Petrochemicals (Coskata 2011) that could
be combined with dehydration technology to produce bio-propylene. However, there has been no new announcements on this
technology since 2011. Production of bio-propylene from bio-methanol through a MTO or even a dedicated methanol to propylene
(MTP) process is another very viable technology option, but there is no evidence of any commercial projects using this route.
Other Potential Bio-olefins
Beyond the C2 and C3 olefins discussed above is a smaller but no less useful market for higher carbon bio-based olefins. Global
Bioenergies is closest to commercialization of a bio-based C4 olefin, with a 10 tonne/year isobutene pilot plant in operation since
November 2014, a second larger pilot-scale facility being built in 2016 and announced plans for a 50 ktpa commercial plant.
Isobutene (also known as isobutylene) is a 4-carbon branched olefin used for producing isooctane fuel and synthetic rubber. The
company is also working on producing bio-butadiene through a similar direct fermentation process. Another company working to
produce bio-isobutene is Lanxess Inc., which hopes to use Gevo's bio-based isobutanol as feedstock and dehydrate the compound to
produce bio-isobutene at scale, although there has been no news on this project since 2011.
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October 2015

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