Scientists develop new process to upcycle plastics and reduce greenhouse gas emissions

Date
10/03/22
Co-lead authors: Damien Guironnet, chemical and biomolecular engineering professor at Illinois, and Susannah Scott, Professor and Chair of Sustainable Catalytic Processing at UC Santa Barbara.

By Claire Benjamin


Scientists from the University of Illinois Urbana-Champaign, University of California, Santa Barbara, and Dow have developed a breakthrough process to transform the most widely produced plastic — polyethylene (PE) — into the second-most widely produced plastic, polypropylene (PP), which could reduce greenhouse gas emissions (GHG). 

“The world needs more and better options for extracting the energy and molecular value from its waste plastics,” said co-lead author Susannah Scott, Distinguished Professor and Mellichamp Chair of Sustainable Catalytic Processing at UC Santa Barbara.

Conventional plastic recycling methods result in low-value plastic molecules and, thus, offer little incentive to recycle the mountains of plastic waste that have accumulated over the past several decades.

But, Scott added, “turning polyethylene into propylene, which can then be used to make a new polymer, is how we start to build a circular economy for plastics.”

“We started by conceptualizing this approach and demonstrated its promise first through theoretical modeling — now we have proved that it can be done experimentally in a way that is scalable and potentially applicable to current industry demands,” said co-lead author Damien Guironnet, a professor of chemical and biomolecular engineering and chemistry at Illinois, who published the first study outlining the necessary catalytic reactions in 2020 with Illinois professor Baron Peters

The new study published in the Journal of the American Chemical Society announces a series of coupled catalytic reactions that transform PE, which is #2 and #4 plastic that make up 29% of the world’s plastic consumption, into the building block propylene that is the key ingredient to produce PP,  also known as #5 plastic that accounts for close to 25% of the world’s plastic consumption. 

This study establishes a proof-of-concept for upcycling PE plastic with more than 95% selectivity into propylene. The researchers have built a reactor that creates a continuous flow of propylene that can be converted into PP easily using current technology — making this discovery scalable and rapidly implementable. 

“Our preliminary analysis suggests that if just 20% of the world’s PE could be recovered and converted via this route, it could represent a potential savings of GHG emissions comparable to taking 3 million cars off the road," said Garrett Strong, a graduate student associated with the project.

The goal is to cut each very long PE molecule many times to obtain many small pieces, which are the propylene molecules. First, a catalyst removes hydrogen from the PE, creating a reactive location on the chain. Next, the chain is split in two at this location using a second catalyst, which caps the ends using ethylene. Finally, a third catalyst moves the reactive site along the PE chain so the process can be repeated. Eventually, all that is left are a large number of propylene molecules. 

“Think of cutting a baguette in half, and then cutting precisely-sized pieces off the end of each half — where the speed at which you cut controls the size of each slice,” Guironnet said. 

“Now that we have established the proof of concept, we can start to improve the efficiency of the process by designing catalysts that are faster and more productive, making it possible to scale up,” Scott said. “Since our end-product is already compatible with current industry separation processes, better catalysts will make it possible to implement this breakthrough rapidly.”

The work presented in this publication is highly complementary to a paper published in Science last week. Both groups used virgin plastics and similar chemistries. However, the Science team used a different process in an enclosed batch reactor, requiring much higher pressure — which is energy intensive — and the need to recycle more ethylene.

“If we are to upcycle a significant fraction of the over 100 million tons of plastic waste we generate each year, we need solutions that are highly scalable,” Guironnet said. “Our team demonstrated the chemistry in a flow reactor we developed to produce propylene highly selectively and continuously. This is a key advance to address the immense volume of the problem that we are facing.” 

Dow researchers were also involved in this work. “Dow is taking a leading role in driving a more circular economy by designing for circularity, building new business models for circular materials, and partnering to end plastic waste," said Dow senior scientist and co-author Ivan Konstantinov. "As a funder of this project, we are committed to finding new ways to eliminate plastic waste and are encouraged by this approach."

This research, in the news: 

Waste plastics unzipped into useful pieces | Research | Chemistry World

Directory

scheelinAlexander
Scheeline
bjmccallBenjamin
McCall
r-gennisRobert
Gennis
j-gerltJohn
Gerlt
sgranickSteve
Granick
mgruebelMartin
Gruebele
hergenroPaul
Hergenrother
huangRaven
Huang
mlkraftMary
Kraft
leckbandDeborah
Leckband
yi-luYi
Lu
martinisSusan
Martinis
snairSatish
Nair
eoldfielEric
Oldfield
cmsCharles
Schroeder
zanZaida
Luthey-Schulten
selvinPaul
Selvin
sksScott
Silverman
s-sligarStephen
Sligar
tajkhorsEmad
Tajkhorshid
zhao5Huimin
Zhao
pbraunPaul
Braun
mdburkeMartin
Burke
jeffchanJefferson
Chan
sdenmarkScott
Denmark
dlottDana
Dlott
foutAlison
Fout
agewirthAndrew
Gewirth
ggirolamGregory
Girolami
sohirataSo
Hirata
jainPrashant
Jain
jkatzeneJohn
Katzenellenbogen
nmakriNancy
Makri
douglasmDouglas
Mitchell
jsmooreJeffrey
Moore
murphycjCatherine
Murphy
r-nuzzoRalph
Nuzzo
dimerPhilip
Phillips
rauchfuzThomas
Rauchfuss
joaquinrJoaquín
Rodríguez-López
sarlahDavid
Sarlah
kschweizKenneth
Schweizer
jsweedleJonathan
Sweedler
vddonkWilfred
van der Donk
renskeRenske
van der Veen
vuraweisJosh
Vura-Weis
mcwhite7M.
White
sczimmerSteven
Zimmerman
beakPeter
Beak
wklemperWalter
Klemperer
jdmcdonaJ.
McDonald
pogoreloTaras
Pogorelov
mshen233Mei
Shen
dewoonDavid
Woon
wboulangWilliam
Boulanger
rxbRohit
Bhargava
qchen20Qian
Chen
jianjuncJianjun
Cheng
hy66Hong
Yang
andinomaJosé
Andino Martinez
decosteDonald
DeCoste
thhuangTina
Huang
tjhummelThomas
Hummel
dkellDavid
Kell
doctorkMichael
Koerner
marvilleKelly
Marville
crrayChristian
Ray
tlbrownTheodore
Brown
rmcoatesRobert
Coates
thdjrThom
Dunning
dykstraClifford
Dykstra
j-jonasJiri
Jonas
j-lisyJames
Lisy
shapleyJohn
Shapley
pshapleyPatricia
Shapley
zumdahl2Steven
Zumdahl
ksuslickKenneth
Suslick
jcoxJenny
Cox
sqdSean
Drummond
sheeleySarah
Sheeley
jsmaddenJoseph
Madden
cknight4Connie
Knight
schulzeHeather
Schulze
kbaumgarKeena
Finney
adkssnBeatrice
Adkisson
trabari1Katie
Trabaris
metclfKara
Metcalf
ljohnso2Lori
Johnson
lchenoweLeslie
Chenoweth
wdedoWolali
Dedo
spinnerDavid
Spinner
plblumPatricia
Simpson
stevens2Chad
Stevens
lsagekarLori
Sage-Karlson
bertholdDeborah
Berthold
kecarlsoKathryn
Carlson
sdesmondSerenity
Desmond
axelson2Jordan
Axelson
scbakerStephanie
Baker
pflotschPriscila
Falagan Lotsch
dgrayDanielle
Gray
thennes2Tom
Hennessey
holdaNancy
Holda
aibarrAlejandro
Ibarra
kimshSung Hoon
Kim
kocherg2Nikolai
Kocherginsky
philipk2Philip
Kocheril
legare2Stephanie
Legare
alewandoAgnieszka
Lewandowska
smccombiStuart
McCombie
jdm5Justin
McGlauchlen
egmooreEdwin
Moore
myerscouKathleen
Myerscough
snalla2Siva
Nalla
romanovaElena
Romanova
roubakhiStanislav
Rubakhin
shvedalxAlexander
Shved
asoudaAlexander
Soudakov
xywangXiying
Wang
kwilhelKaren
Wilhelmsen
wilkeyRandy
Wilkey
silongSilong
Zhang
schlembaMary
Schlembach
trimmellAshley
Trimmell
emccarr2Elise
McCarren
cmercierChristen
Mercier
atimpermAaron
Timperman
niesShuming
Nie
hshanHee-Sun
Han
mmgMutha
Gunasekera
kknightsKatriena
Knights
lisawLisa
Williamson
keinckKatie
Einck
kneef1Kate
Neef
txiang4Tiange
Xiang
j-hummelJohn
Hummel
i-paulIain
Paul
munjanjaLloyd
Munjanja
glnGayle
Nelsen
agerardAnna
Gerard
powerskaKimberly
Powers
lolshansLisa
Olshansky
miricaLiviu
Mirica
qingcao2Qing
Cao
lisa3Lisa
Johnson
tinalambTina
Lamb
baronpBaron
Peters
bransle2Sarah
Bransley
dylanmh2Dylan
Hamilton
raegansRaegan
Smith
apm8Angad
Mehta
leverittJohn
Leveritt
xingwXing
Wang
emillrEva
Miller
jmill24Jacqueline
Miller
jlbass2Julia
Bass
ramonarRamona
Rudzinski
tlcraneTracy
Crane
cejohnstCelia
Johnston
adlAmber
LaBau
cnsolomoCandice
Solomon-Strutz
mikaelbMikael
Backlund
jacksonnNick
Jackson