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Braskem has popularized "Green" polyethylene.
Now, the question is what does "Green" really
mean? When I joined the petrochemical industry back in the
day, if someone said a plastic was green, it implied the plastic
would be biodegradable. Today, the meaning of green has an
additional meaning, that is the plastic was made from a renewable
resource. And that is how Braskem means it. Braskem takes
bioethanol made via fermentation of sugar from
sugarcane and dehydrates it to ethylene and in
turn this green ethylene is polymerized to green
high density polyethylene.
This whole area of what constitutes a "green" plastic is very
confusing and industry participants, and especially consumers, may
have different notions of what this term "green" really means. To
illustrate some of the different products claiming "greenness", I
put together this chart which I use in my training course,
"Understanding the Global
Petrochemical Industry". I call it "The Many
Shades of Green".
On the upper left, is Braskem's green
polyethylene. It's made from a renewable feedstock but it
is not compostable or biodegradable. Its properties are identical
to petrochemical HDPE in every other respect. On the upper right is
Coca-Cola's Plant bottle. This plastic bottle is
polyethylene terephthalate or PET made by reacting
petrochemical-based PTA and renewable MEG. The renewable MEG is
made by reacting green ethylene from bioethanol (in the same way
Braskem does it) and then using conventional technology the green
ethylene is converted to green MEG. Thus, the resulting PET is 30%
renewable. But again, just like Braskem's green polyethylene, the
Plant bottle will not be compostable or biodegradable. Its
properties are identical to 100% petrochemical-based PET bottles.
On the lower left, is an example of Nature Works green
polylactic acid.This plastic is 100% made from renewable
resources and is compostable. But to fair, this plastic will only
biodegrade in commercial facilities using appropriate conditions.
And finally, to add additional complexity, on the lower right is a
BASF product, Eco Flex. This
plastic is 0% renewable, in other words made totally from
petrochemical-based feedstocks but yet is designed to be
compostable.
I think you would agree that there are a bunch nuances to this
whole area that I think are not appreciated by consumers and even
to many in the plastics business.
And now, Sumitomo has a new twist.
Sumitomo has recently announced that they are licensing
Axens' ethanol-to ethylene technology as a piece
in the puzzle to develop a circular waste-to-polyethylene project
in Japan. Axens' technology, registered as Atol,
is based upon catalytic dehydration of 1st or 2nd generation
bioethanol to give bio-ethylene. Axens claims 99+% ethanol
conversion per pass, close to stoichiometric ethylene
yield, and ethylene purity of up to 99.9%.
The key to making this approach circular is the
production technology that will be employed by Sumitomo to make the
bioethanol. In early 2020, Sumitomo had announced they were
cooperating with SEKISUI CHEMICAL to transform
waste into ethanol. In late 2017, and SEKISUI CHEMICAL in a joint
development effort with LanzaTech Inc. developed technology to
gasify waste to syngas (a mixture of carbon
monoxide and hydrogen) and convert the syngas into ethanol using
bio-catalysis.
Thus, putting all of these company's pieces together, Sumitomo,
Axens, SEKISUI CHEMICAL, and LanzaTech will allow for a
completely circular route to polyethylene.
Sumitomo hopes to pilot the project in 2022 with full scale
commercialization in 2025.
This is a great way to demonstrate that to solve the plastic
waste issue it will take a lot of collaboration as no one company
will likely have the skillset and experience to develop all of the
necessary pieces in the puzzle.
