The |
A
team of chemical engineers led by Paul J. Dauenhauer of the University
of Massachusetts Amherst has discovered a new, high-yield method of
producing the key ingredient used to make plastic bottles from biomass.
The process is inexpensive and currently creates the chemical p-xylene
with an efficient yield of 75%, using most of the biomass
feedstock, Dauenhauer says. The research is published in the journal ACS
Catalysis.
Dauenhauer,
an assistant professor of chemical engineering at UMass Amherst, says
the new discovery shows that there is an efficient, renewable way to
produce a chemical that has immediate and recognizable use for
consumers. He says the plastics industry currently produces p-xylene
from petroleum and that the new renewable process creates exactly the
same chemical from biomass.
‘You
can mix our renewable chemical with the petroleum-based material and
the consumer would not be able to tell the difference,” Dauenhauer says.
Consumers
will already know the plastics made from this new process by the
triangular recycling label “#1” on plastic containers. Xylene chemicals
are used to produce a plastic called PET (or polyethylene
terephthalate), which is currently used in many products including soda
bottles, food packaging, synthetic fibers for clothing and even
automotive parts.
The
new process uses a zeolite catalyst capable of transforming glucose
into p-xylene in a three-step reaction within a high-temperature biomass
reactor. Dauenhauer says this is a major breakthrough since other
methods of producing renewable p-xylene are either expensive (e.g.,
fermentation) or are inefficient due to low yields.
A
key to the success of this new process is the use of a catalyst that is
specifically designed to promote the p-xylene reaction over other less
desirable reactions. Dauenhauer says his research colleagues, professors
Wei Fan of UMass Amherst and Raul Lobo of the University of Delaware,
designed the catalyst. After a series of modifications, the team was
able to help enhance the yield of the reaction. He also says additional
modification of the process can further boost p-xylene yield and make
the process more economically attractive.
“We
discovered that the performance of the biomass reaction was strongly
affected by the nanostructure of the catalyst, which we were able to
optimize and achieve 75% yield,” Fan says. Computations conducted
by the team have been instrumental in understanding the reaction
mechanism and the role of the catalyst as well as making alteration to
the catalyst to improve the yield of the process.
Besides
Dauenhauer and Fan, the research team is made up of UMass Amherst’s C.
Luke Williams and Chun-Chih Chang, doctoral students in chemical
engineering, and their collaborators, professors Raul F. Lobo, Dionisios
G. Vlachos and Stavros Caratzoulas, as well as doctoral student Nima
Nikbin, and postdoctoral fellow Phuong Do from the University of
Delaware.
This
discovery is a part of a larger effort by the Catalysis Center for
Energy Innovation (CCEI) to create breakthrough technologies for the
production of biofuels and chemicals from lignocellulosic biomass. The
center is funded by the U.S. Department of Energy as part of the Energy
Frontiers Research Center (EFRC) program which combines more than 20
faculty members with complimentary research skills to collaborate on
solving the world’s most pressing energy challenges.
The
discovery for the production of plastics adds another dimension to the
portfolio of accomplishments of CCEI. In 2010, a CCEI research team led
by Mark Davis of Caltech discovered a new catalyst, called Tin-Beta,
which can convert glucose into fructose. This is the first step in the
production of a large number of targeted products including biofuels and
biochemicals, including p-xylene, from the building block of cellulose,
the major constituent of trees and switchgrass.
In
addition, a team led by Ray Gorte and John Vohs at the University of
Pennsylvania has developed a novel fuel cells technology that converts
solid biomass to electricity and another led by George Huber and Wei Fan
of UMass Amherst has improved the yield to aromatics that can be used
as drop-in fuels to gasoline.
