Chemical Engineering September 2010 - 12

CHEMENTATOR
A more efficient, less expensive way
to continuously make bioethanol
A
n enhanced reactor technology that
boosts the speed of producing bioethanol
by a factor of four while decreasing
production costs by 25% compared to a
stirred batch fermenter has been developed
by IHI Corp. (IHI; Tokyo; www.ihi.
co.jp). The technology features a cohesive
strain of yeast to increase the number
density of microorganisms in the reactor,
and utilizes the flow created by the carbon
dioxide gas released by the fermentation
to enhance the contact (mixing) between
the yeasts and glucose feed solution. As a
result, the continuous process eliminates
the need for mechanical agitation and aeration,
thereby reducing operating costs,
maintenance and reactor size.
In IHI's process, glucose solution is continuously
fed to the bottom of the reactor
and flows upward by the gas generated
by fermentation. The gas is collected
by an umbrella-like structure at the top,
and then moves into a small side vessel.
There, the gas is separated from the fermentation
broth (yeast aggregates and
liquids), which is recycled to the bottom
of the reactor. Ethanol is recovered from
a side stream leaving the settlement part
of the reactor.
In a pilot reactor (8.6-L reactor volume,
1-m high and 10-cm dia.) operating at its Yokohama
facility, IHI has demonstrated the
technology with one month of continuous operation.
An ethanol production speed of 25 g/
Lh was achieved, and the average size of the
yeast aggregate maintained at 0.5-1.5 mm.
A new iodine-based catalyst for asymmetric synthesis
P
rofessor Kazuaki Ishihara and colleagues
at Nagoya University (Nagoya, Japan;
www.nubio.nagoya-u.ac.jp/nubio4/english/
main-e.htm) has discovered an efficient,
chiral, salt-based hypervalent iodine catalyst
that could replace toxic metal catalysts
without generating the waste or explosion
risks associated with hypervalent organoiodine
complexes. The researchers took the
radical step of swapping iodine bonded to
carbon for an iodite (IO2
-) or hypoiodite
(IO-) anion as the oxidant, which can be
generated from iodide (I-) by simple oxidants,
such as hydrogen peroxide. The team
also coupled the (hypo)iodite with a chiral,
quaternary-amine counter ion to solubilize
the inorganic iodite in organic solvents and
provide a chiral environment to control the
geometry of the reaction.
In the laboratory, the researchers performed
an enantio-selective, oxidative cycloetherification
of ketophenols to 2-acyl2,3-dihydrobenzofuran
derivatives - a key
structure in several biologically active comREMOVE
ARSENIC FROM WATER
(Continued from p. 11)
ticles. The graphene oxide was reduced
to RGO by hydrazine hydrate, which was
added slowly for 4 hours at 90°C.
In the composite that the team created,
the magnetite nanoparticles are well dispersed
in the RGO matrix with an average
particle size of 11 nm. The nanoparticles are
Small
vessel
Settlement
part
Ethanol
solution
Reaction
part
Recycle
tube
On-off
valve
(open
during
operation)
(glucose solution)
P
Raw
materials
pounds - catalyzed by in-situ-generated
chiral, quaternary-ammonium-(hypo)iodite
salts, with hydrogen peroxide as an environmentally
benign oxidant (only water
and alcohol are generated as byproducts).
After recrystallization, an optical purity of
99 ee % is achieved for this reaction, the
highest selectivity with the lowest catalyst
loading ever seen in asymmetric, hypervalent-iodine
catalysis, says Ishihara. The
team confirmed that asymmetric synthesis
using inorganic iodide catalyst occurred in
several hours for 10 mol% catalyst, which
is faster than the 17 hours required for the
same concentration of an organic iodine
catalyst, suggesting the possibility for real
industrial use.
Ishihara expects that a variety of oxidative
coupling reactions could be controlled
by these salts in place of transition metal
catalysts, and is aiming to make an intermolecular
version - joining two molecules
together rather than reacting two sites on
the same molecule.
not simply mixed in or blended with RGO,
rather, they are entrapped inside the RGO
sheets. The composite is especially effective
in arsenic removal - compared with bare
magnetite - because the graphene sheets
greatly increase the number of adsorption
sites. Also, the stability of magnetite is increased
by the RGO, so that it can be used in
continuous flow systems for longer periods.
12 ChemiCal engineering www.Che.Com September 2010
Nanofiber applications
last month, Dupont (wilmington,
Del.; www.dupont.com)
introduced the irst nanoiberbased
polymeric battery separator
that boosts the performance
and safety of lithium-ion batteries.
tradenamed energain, the
separators are said to increase
power by 15-20%, increase
battery life by up to 20% and improve
battery safety by providing
stability at high temperatures.
the battery separators are
made into a web using a proprietary
spinning process that creates
continuous ilaments with
diameters between 200 and
1,000 nm.
the company has begun
construction on a facility in
Chesterield, Va., to manufacture
product for development
and commercial sale. Slated
to startup in the irst quarter of
2011, the facility will initially have
the ability to supply 20% of today's
hybrid and electric vehicle
needs. while the initial uses
for the separator are in hybrid
vehicle batteries, the nanoiber
technology will target other
renewable-energy applications
as well as a broad range of liquid
iltration applications for the
biopharmaceutical, microelectronics,
and food-and-beverage
industries, offering " superior "
retention, ilter life and low resistance,
says Dupont.
(Continues on p. 13)
http://www.ihi http://www.co.jp http://www.dupont.com http://www.nubio.nagoya-u.ac.jp/nubio4/english/ http://www.Che.Com
Chemical Engineering September 2010

Table of Contents for the Digital Edition of Chemical Engineering September 2010
