Chemical Engineering April 2015 - 7

Chementator
Biomass pretreatment approach can reduce
enzyme requirements
B
iomass is
a recalcitrant,
heterogeneous
THF
Biomass
Sulfuric
acid
CELF pretreatment
THF recycle
matrix of cellulose,
hemicellulose and
lignin that resists
microbial and enzymatic
breakdown.
Overcoming this
recalcitrance is the
major economic barrier
to the conversion
of biomass to sugars
or other chemicals.
Heat, acid and other chemicals are used
in pretreatment steps to open the biomass
structure so that it can be converted into fermentable
sugars by enzymes.
Engineers at the University of California
H
H+
Lignin Calcium
sulfate
Fresh water
Wastewater
Washed biomass solids
Solids separation, washing, THF recovery
lignin precipitation, and acid neutralization
Source: UCR
at Riverside (UCR; www.ucr.edu) have developed
a new pretreatment method (flowsheet)
that can reduce the need for enzymes
in downstream steps. The technique, known
as co-solvent-enhanced lignocellulosic fractionation
(CELF), employs aqueous solutions
of the polar, aprotic solvent tetrahydrofuran
(THF) to enhance the effectiveness of the
widely used dilute-acid pretreatment (flowsheet).
Using CELF, a substantial portion of
the fermentable sugars in hemicellulose are
recovered in solution, and about 90% of the
lignin is removed from the biomass, explains
research leader Charles Wyman, who is a
professor in the UCR Chemical and Environmental
Engineering Dept. and holds the
Ford Motor Company Chair in Environmental
Engineering of the Center for Environmental
Research and Technology in the Bourns College
of Engineering at UCR. Further, the solids
left after removing so much of the hemicellulose
and lignin " are readily converted to
glucose at enzyme loadings about one-tenth
or less of those needed for conventionally
pretreated biomass (such as with dilute sulfuric
acid), " he adds.
" THF appears to further catalyze hydrolysis
of biomass by speeding hydrolysis reactions
more than competing degradation reactions,
and by generally promoting the breakage of
lignin bonds, " says Wyman,
The research group published a paper in
ChemSusChem describing the application
of CELF to corn stover, an agricultural residue
material, but Wyman says the group has
also shown CELF's effectiveness with poplar
and red maple hardwoods.
Making bio-based PET monomer from furfural
T
he research group of Yuya Tachibana
at Gunma University (Gunma, Japan;
greenpolymer.chem-bio.st.gunma-u.
ac.jp) has developed a procedure for
the production of terephthalic acid (TPA), the
monomer of the widely used thermoplastic
polymer polyethylene terephthalate (PET),
from the inedible biomass-derived starting
material furfural. Alternative, commercially
available bio-based PET is made from biobased
ethylene glycol (derived from bioethanol)
and petroleum-based TPA, which is made
from p-xylene, so the amount of biomass
carbon content in the PET is only 20 wt.%.
This new route to TPA offers the possibility for
100% bio-based carbon in PET.
The production process consists of six
steps: (1) oxidation of furfural to fumaric and
maleic acids; (2) dehydration of the acids to
maleic anhydride; (3) Diels-Alder (DA) reaction
of anhydrous maleic acid and furan to
the exo-DA adduct; (4) dehydration of the
exo-DA adduct to phthalic anhydride; (5)
hydrolysis of phthalic anhydride to dipotassium
phthalate; and (6) transfer reaction
and acidification of dipotassium phthalate to
TPA. In laboratory trials, TPA was produced
with 19% yield and 95-98% purity.
Tachibana says the group aims to improve
the production process by reducing the number
of steps to two, increasing the yield to 35-40%
or even higher (50%). He says the use of biobased
TPA for plastics has the potential to fix
approximately 970,000 ton/yr of CO2 in Japan.
Note: For more information, circle the 56-digit number on p. 78, or use the website designation.
ChemiCal engineering www.Chemengonline.Com april 2015
Simultaneous saccharification and
fermentation (SSF)
Enzymes
Microorganism
Calcium
hydroxide
Enz.
Microorg. OH
CO2
Edited by:
Gerald Ondrey
NaNocellulose pilot
Ethanol
Sappi Ltd. (Johannesburg;
South Africa; www.sappi.
com) will build a pilot-scale
plant for low-cost nanocellulose
(Cellulose NanoFibrils;
CNF) production at
the Brightlands Chemelot
Campus (Sittard-Geleen,
the Netherlands; www.
brightlands.com). The pilot
plant will test the manufacturing
of dry re-dispersible
CNF using the proprietary
technology developed by
Sappi and Edinburgh Napier
University. The pilot plant is
expected to be operational
within nine months.
The pilot plant is the precursor
for Sappi to consider the
construction of a commercial
CNF plant. Products produced
using Sappi's CNF will
be optimally suitable for conversion
in lighter and stronger
fiber-reinforced composites
and plastics, in food and
pharmaceutical applications,
and in rheology modifiers, as
well as in barrier and other
paper and coating applications,
says the company.
Mos2 MoNolayers
Monolayers of molybdenum
disulfide (MoS2) are attracting
a lot of attention for their
atomic structure, which is
similar to that of the twodimensional
carbon material
graphene, and for their ability
to act as semiconductors
in single-layer sheets. Researchers
at the University
of Pennsylvania (Philadelphia;
www.upenn.edu) have
developed a chemical vapor
deposition method that
results in highly crystalline
flakes of monolayer MoS2
at locations that can be
precisely controlled. Using
" seeds " of Mo-containing
materials that are placed
on a silicon substrate using
conventional photolithography
techniques, the pro(Continues
on p. 13)
7

http://www.sappi http://www.brightlands.com http://www.ucr.edu http://www.ac.jp http://www.upenn.edu http://www.Chemengonline.Com

Chemical Engineering April 2015

Table of Contents for the Digital Edition of Chemical Engineering April 2015