che_november-2024 - 21

Eastman
FIGURE 3. The chemical recycling facility at Eastman's
Kingsport, Tenn. site began producing recycled
material from PET waste earlier this year
lective dissolution of one layer with
a solvent mix that does not dissolve
the other layers. The undissolved
portion is filtered out and the dissolved
polymer is precipitated with
low temperatures or antisolvents.
Marcian Lee says: " Dissolution
has a big role to play in engineered
plastics, because it is tolerant of
contaminants. While it is hard to get
to food-contact-grade material with
dissolution technologies, it is not
hindered by contaminants as long
as they don't dissolve in the solvent,
which are generally trade secrets. "
One company working on scaling
up a dissolution process is APK AG
(Merseberg, Germany; www.apk.
group). The company's NewCycling
process produces low-density PE
granules from mixed plastic packaging
waste by selectively dissolving
PE and separating it from other polymers,
additives and contaminants
in the waste stream. APK says its
recycling process lowers CO2 production
by 66% compared to new
plastic. The company has plans to
isolate other polymers as well. In
October, LyondellBasell completed
its acquisition of APK.
Another example of a dissolution
process is the solvent-targeted recovery
and precipitation (STRAP)
process, developed by scientists at
the University of Wisconsin-Madison
(www.wisc.edu) led by George
Huber. Construction of a pilot plant
for a continuous STRAP process
was begun last year at the Michigan
Technical University (www.mtu.edu),
in a collaboration led by MTU professor
Ezra Bar-Ziv.
Enzymatic depolymerization
Another approach to depolymerization
utilizes enzymes to cleave the
polymer bonds in plastic waste. This
technology, sometimes included
under the solvolysis umbrella, is
somewhat less mature than some
other chemical recycling technologies,
but it is attractive because it requires
less energy than many other
approaches. Thus far, enzymatic depolymerization
has been developed
with a focus on PET, but theoretically,
it could be used for other polymers.
A leader in this area is Carbios (St.
Beauzire, France; www.carbios.fr).
In May 2024, Carbios broke ground
on the world's first PET biorecycling
plant based on enzymatic depolymerization
in Longlaville, France. The
plant will have a processing capacity
of 50,000 tons/yr of prepared waste
when operating at full capacity, the
company says, and products are
expected to be delivered in 2026. It
will handle multilayered, colored and
opaque polyester packaging waste
and polyester textile waste.
Thermochemical approaches
Because many waste streams consist
of mixed plastics with contaminants
and additives, there is keen
interest in recycling processes that
can accommodate a broader range
of feedstocks. One approach is
using supercritical water to break
down plastic waste. Mura Technology
(London, U.K.; www.muratechnology.com)
developed Hydro-PRT,
a process that uses water above its
critical point to produce fossil-equivalent
oils from mixed, multi-layered
flexible and rigid plastic waste for the
petrochemicals industry to create
virgin-grade plastics.
The company says its first commercial-scale
Hydro-PRT plant, in
Teesside, U.K., will become the
world's largest advanced recycling
plant when it commences operations
later this year. Two further plants
being built under license with partners
in South Korea and Japan, are
expected to come online next year.
The application of microwaves to
as a method of energy transfer has
emerged as an alternative approach
to processing plastic waste streams.
Startups such as Pyrowave Inc.
(Montreal, Que.; www.pyrowave.
com) and Microwave Solutions
(Riehen, Switzerland; www.microwavesolutions.ch)
are among those
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
NOVEMBER 2024
pursuing the use of electrically powered
microwaves to replace thermal
methods for plastics recycling.
Microwave Chemical Co. Ltd.
(MWCC; Osaka, Japan; www.mwcc.
jp) is also pursuing this, and has partnered
with Asahi Kasei (Tokyo; www.
asahi-kasei.com) to scale up its technology,
known as the PlaWave platform.
MWCC and Asahi Kasei plan
to begin constructing a pilot plant
using microwaves to depolymerize
polyamide-66 (nylon) in 2025. The
partnership envisions expanding the
approach to other plastic types also.
MWCC's Yuri Katoda says " Microwaves
serve as a method of energy
transfer, rather than initiating a specific
chemical reaction . . . Each material
has its own unique microwave
absorption capability. And by leveraging
these characteristics, we are
engineering optimal depolymerization
conditions based on microwave
heat transfer principles. "
In the case of PA-66 recycling, the
microwave process directly generates
the monomers hexamethylenediamine
(HMD) and adipic acid
(ADA) at high yield with low energy
consumption, Katoda says. Advantages
of microwaves include precise
temperature control, smaller facility
footprint and decarbonization (use
of renewable energy possible).
" Our chemical recycling technology
is based on the microwave absorption
capabilities of different plastics, "
Katoda explains, " so we are basically
prepared to adapt our technology to
any type of plastic. " MWCC aims to
build a commercial plant within the
next several years, Katoda says.
Another recycling company employing
microwaves is GR3N S.A.
(Lugano, Switzerland; blog.gr3n-recycling.com).
GR3N has developed
microwave-assisted depolymerization
(MADE) to break down PET
into its monomers and create new
PET pellets with quality comparable
to virgin plastic. The technology
combines microwaves with alkaline
hydrolysis in a way that tolerates
higher levels of impurities than existing
methods, the company says.
The company is building a facility in
Spain to produce 40,000 tons/yr of
" virgin-like PET. "
n
Scott Jenkins
21
https://mwcc.jp/en/ http://www.asahi-kasei.com https://www.carbios.com/en/ https://www.apk.group/en/ https://www.apk.group/en/ http://www.muratechnology.com http://www.muratechnology.com https://blog.gr3n-recycling.com/ https://blog.gr3n-recycling.com/ http://www.wisc.edu http://www.mtu.edu http://www.pyrowave.com http://www.microwavesolutions.ch http://www.microwavesolutions.ch http://WWW.CHEMENGONLINE.COM
che_november-2024

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