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two phenols, a class of aromatic
hydrocarbon compounds used in
perfumes and flavorings. A commonly
used artificial vanilla flavoring is cur-
rently produced using a phenol that
comes from petroleum, he said.
The team also developed an addition-
al process that uses another catalyst
to convert the two phenol products
into high-octane hydrocarbon fuel
suitable for use as drop-in gasoline.
The fuel produced has a research oc-
tane rating greater than100, whereas
the average gas we put into our cars
has an octane rating in the eighties,
he said.
The processes and resulting products
are detailed in a paper published
online in the Royal Society of Chemis-
try journal Green Chemistry. The U.S.
Department of Energy funded the
research.
In addition to Abu-Omar, co-authors
include Trenton Parsell, a visiting scholar in the Department of Chemistry; chemi-
cal engineering graduate students Sara Yohe, John Degenstein, Emre Gencer, and
Harshavardhan Choudhari; chemistry graduate students Ian Klein, Tiffany Jarrell,
and Matt Hurt; agricultural and biological engineering graduate student Barron
Hewetson; Jeong Im Kim, associate research scientist in biochemistry; Basudeb
Saha, associate research scientist in chemistry; Richard Meilan, professor of for-
estry and natural reserouces; Nathan Mosier, associate professor of agricultural and
biological engineering; Fabio Ribeiro, the R. Norris and Eleanor Shreve Professor of
Chemical Engineering; W. Nicholas Delgass, the Maxine S. Nichols Emeritus Profes-
sor of Chemical Engineering; Clint Chapple, the head and distinguished professor of
biochemistry; Hilkka I. Kenttamaa, professor of chemistry; and Rakesh Agrawal, the
Winthrop E. Stone Distinguished Professor of Chemical Engineering.
The catalyst is expensive, and the team plans to further study efficient ways to
recycle it, along with ways to scale up the entire process, Abu-Omar said.
¡°A biorefinery that focuses not only on ethanol, but on other products that can be
made from the biomass is more efficient and profitable overall,¡± he said. ¡°It is pos-
sible that lignin could turn out to be more valuable than cellulose and could subsi-
dize the production of ethanol from sustainable biomass.¡±
The U.S. Department of Energy-funded C3Bio center is an Energy Frontier Research
Center. It is part of Discovery Park¡¯s Energy Center and the Bindley Bioscience Cen-
ter at Purdue.
Purdue Research Foundation has filed patent applications and launched a startup
company, Spero Energy, which was founded by Abu-Omar.
Writer: Elizabeth K. Gardner, 765.494.2081, ekgardner@purdue.edu
(Source: Mahdi Abu-Omar, 765.494.5302, mabuomar@purdue.edu)
Bio ¡°Waste¡± Becomes Fragrances, Flavorings, High-octane Fuel
What biorefineries consider waste to be burned now turned into high-value molecules
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West Lafayette, Indiana: A new cata-
lytic process is able to convert what
was once considered biomass waste
into lucrative chemical products that
can be used in fragrances, flavor-
ings or to create high-octane fuel for
racecars and jets.
A team of researchers from Pur-
due University¡¯s Center for Direct
Catalytic Conversion of Biomass to
Biofuels, or C3Bio, has developed a
process that uses a chemical cata-
lyst and heat to spur reactions that
convert lignin into valuable chemical
commodities. Lignin is a tough and
highly complex molecule that gives
the plant cell wall its rigid structure.
Mahdi Abu-Omar, the R.B. Wetherill
Professor of Chemistry and Professor
of Chemical Engineering and associ-
ate director of C3Bio, led the team.
¡°We are able to take lignin - which
most biorefineries consider waste to
2015 FEBRUARY #6-1
be burned for its heat - and turn it into high-value molecules that have applications in
fragrance, flavoring and high-octane jet fuels,¡± Abu-Omar said. ¡°We can do this while
simultaneously producing from the biomass lignin-free cellulose, which is the basis of
ethanol and other liquid fuels. We do all of this in a one-step process.¡±
Plant biomass is made up primarily of lignin and cellulose, a long chain of sugar mol-
ecules that is the bulk material of plant cell walls. In standard production of ethanol,
enzymes are used to break down the biomass and release sugars. Yeast then feast on
the sugars and create ethanol.
Lignin acts as a physical barrier that makes it difficult to extract sugars from biomass
and acts as a chemical barrier that poisons the enzymes. Many refining processes
include harsh pretreatment steps to break down and remove lignin, he said.
¡°Lignin is far more than just a tough barrier preventing us from getting the good
stuff out of biomass, and we need to look at the problem differently,¡± Abu-Omar said.
¡°While lignin accounts for approximately 25 percent of the biomass by weight, it ac-
counts for approximately 37 percent of the carbon in biomass. As a carbon source
lignin can be very valuable, we just need a way to tap into it without jeopardizing the
sugars we need for biofuels.¡±
The Purdue team developed a process that starts with untreated chipped and milled
wood from sustainable poplar, eucalyptus or birch trees. A catalyst is added to initiate
and speed the desired chemical reactions, but is not consumed by them and can be
recycled and used again. A solvent is added to the mix to help dissolve and loosen up
the materials. The mixture is contained in a pressurized reactor and heated for several
hours. The process breaks up the lignin molecules and results in lignin-free cellulose
and a liquid stream that contains two additional chemical products, Abu-Omar said.
The liquid stream contains the solvent, which is easily evaporated and recycled, and
Biomass is biological material derived from living, or recently living organisms. In
the context of biomass for energy this is often used to mean plant based material.
Image credit: Spero Energy
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