Chemical Engineering June 2018 - 10

biofuels are produced from
crops, competing with food
production in the use of resources.
Currently, bioconversion
of cellulose to biofuels
requires several steps, including
pretreatment, enzymatic
saccharification, detoxification
and fermentation. It is
therefore desirable to develop
a bioconversion technology
for the direct conversion of
cellulosic biomass into biofuels
without the need for those
pretreatment steps.
Now, a team from the National
University of Singapore
(www.nus.edu.sg), led by
professor He Jianzhong has
found that a naturally occurring
bacterium - Thermoanaerobacterium
thermosaccharolyticum
strain TG57, isolated
from waste generated after
harvesting mushrooms - is
capable of directly converting
cellulose to biobutanol. The
TG57 strain evolves naturally
in the waste generated by
mushroom farming - typically
wheat straw and saw dust. The
fermentation process is simple
and requires no pretreatment
or genetic modification of the
bacteria. The TG57 strain uses
microcrystalline cellulose directly
to produce butanol (1.93
g/L) as the only final product,
without generating side products
acetone or ethanol.
MOLTEN SALT CSP
Thanks in large part to developing
and operating a facility
for testing molten salt reactor
(MSR) technologies, nuclear
experts at Oak Ridge National
Laboratory (ORNL; Tenn.;
www.ornl.gov) are now tackling
the next generation of
another type of clean energy
- concentrating solar thermal
power (CSP). The U.S. Energy
Dept.'s Solar Energy Technologies
Office selected the ORNLbased
team to develop a molten
chloride salt facility as part
of the Generation 3 Concentrating
Solar Power Systems
(Gen3 CSP) program. The
Gen3 CSP program supports
research in materials and facilities
that could allow future CSP
plants to operate at higher temperatures
and lower the cost of
electricity production.
Kevin Robb, a staff scientist
in ORNL's Reactor and Nu(Continues
on p. 11)
10
Taking UV/O3 VOC treatment
one cleaner step forward
Infuser
Primary pollution
Up to 60,000 m3/h
UV module
Secondary pollution:
* SemiOx VOC
* O3
* HCHO
* Particles
Water
* No soap
* No chemicals
Clean air to stack
Catalyst module
Waste water:
* Low volume
* High COD
* pH neutral
U
sing ultraviolet (UV) radiation or
ozone (or both) to oxidize air pollutants,
such as volatile organic compounds
(VOCs) is a well-established
treatment method in the chemical process
industries (CPI). What is not so well known,
however, is that for most pollutants, the oxidation
products of UV/O3 treatment, such as
O3, formaldehyde and a whole range of other
semi-oxidized compounds, can be significantly
more hazardous than the original VOC,
says Nicolai Bork, product manager - Industrial
Pollution Control at Infuser ApS (Copenhagen,
Denmark; www.infuser.eu). " Alarmingly,
we see many installations using just UV/
O3 where factory owners have never been
informed about these issues. "
Infuser has taken conventional UV/O3
technologies a step further by incorporating
a catalytic filter to the normal UV-treatment
section. Developed in close collaboration with
the University of Copenhagen, the company's
Climatic air-purification technology (diagram)
is based on accelerating the self-cleansing
mechanisms of the atmosphere - namely,
a carefully adjusted combination of gaseous
oxidants, water vapor and UV light, explains
O
ne of the major obstacles to making
hydrogen economically by splitting
water is the high cost of noble-metal
electrodes. Less expensive, nonnoble
metals only function as electrocatalysts
under alkaline conditions, where the reaction
requires more electricity.
Now, professor Ryoichi Ito at the University
of Tsukuba (Tsukuba City, www.tsukuba.
ac.jp), in collaboration with Osaka University
and Tohoku University, has developed
non-noble-metal electrodes capable of performing
the H2-evolution reaction (HER) as
efficiently as conventional Pt/C electrodes,
even under acidic conditions. The new electrodes
use nitrogen-doped graphene sheets
Bork. This produces OH radicals that oxidize
VOCs into oxidation products (OxVOCs) that
precipitate out of the gas phase as aerosol
particles. A second-stage treatment, using
a multibed O3-removal catalyst with VOCadsorption
capabilities, performs O3 removal
and oxidation of the semi-oxidized VOCs to
CO2. Furthermore, the filter is designed to
capture the produced aerosol particles. For
industrial applications, an automated washing
of the filter medium can be installed for largescale
continuous operation, he says.
Conventional cleaning technologies, such
as adsorption on activated carbon have
pressure drops that are 10-15 times higher
that a Climatic system, which can translate
to 20-100 kW of saved energy for fan power
alone, says Bork.
The process has been demonstrated at a
leading wind-turbine OEM factory in Europe,
which started up in 2017. Four units, totalling
210,000 m3/h, have been continuously reducing
styrene emissions by more than 90%,
while saving the operator " significant costs " of
replacing activated carbon. The company is
also targeting other applications in the styrene
and polymer industries, says Bork.
A Pt-free electrode for making H2 from water
to encapsulate a NiMo alloy electrode. Unlike
other graphene-based electrodes, the Tsukuba
system incorporates nanometer-sized
holes, which are ringed by chemically active
ridges known as fringes. These fringe defects
are more hydrophillic than normal graphene,
so they attract H3O+ ions in the acid solution,
which are involved in the HER reaction
mechanism. The fringes also adsorb H
atoms, thereby providing extra surface area
for another HER process. As a result, the H2
is generated as efficiently as with the more
expensive Pt/C electrode, and the remaining
hole-free part of graphene protects the metals
from corroding in the acid. The research is
described in a recent issue of ACS Catalyst.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JUNE 2018
http://www.nus.edu.sg http://www.infuser.eu http://www.ornl.gov http://www.tsukuba http://www.ac.jp http://WWW.CHEMENGONLINE.COM
Chemical Engineering June 2018

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