Chemical Engineering March 2017 - 7

Chementator
Single-step production of high-purity silicon
demonstrated
PyroGenesis Canada
HCl
Conventional
process
Quartz
Coal
Wood chips
H2
Electric
arc
furnace
Metallurgicalgrade
(MG)
silicon
MG silicon
dissolved in HCl
to form HSiCl3
Refining of
HSiCl3
Siemens
reactor
High-purity
silicon
Purevap
process
Quartz
Carbon
Reactive gas
A
chieving silicon of acceptable purity
for solar-energy applications
typically requires several purification
steps. Now, a new process has been
demonstrated that can produce high-purity
Si from low-quality quartz in a single step.
The PureVap technology from PyroGenesis
Canada Inc. (Montreal, Que.; www.pyrogenesis.com)
utilizes a powerful vacuum-arc furnace,
combining the carbothermic reduction
of silicon and purification into one process,
explains Pierre Carabin, chief technology officer
for PyroGenesis Canada.
Traditional arc furnaces produce relatively
low-purity Si, around 98.5% purity, requiring
subsequent purification. Inside the PureVap
furnace, low-quality (97.5%) quartz and a
carbon source are exposed to heat from a
plasma arc, creating CO2 and Si. The vacuum-arc
furnace allows for the vaporization
of contaminants, including boron and sulfur.
By manipulating the metallic vapors' partial
pressures, the contaminants are removed.
In 2016, following successful demonstration
of the PureVap process at the laboratory
scale, PyroGenesis announced a contract
worth over $6 million with Canadian mining
company HPQ Silicon Resources, Inc. to
develop a pilot plant to produce 200 metric
tons per year of high-purity Si. The company
expects the plant to start up in late 2017.
In January 2017, PyroGenesis announced
a series of successful trials, demonstrating
both the scalability and repeatability of
the PureVap system, as the company begins
scaling up production from grams to
kilograms. " We have proven that we can
remove the contaminants and make significant
quantities of silicon. We've also
proven that we can consistently produce
99.9% purity silicon. We have been able
to produce, on occasion, 99.99% purity, "
says Carabin. He goes on to say that the
company's current objective is to increase
this purity to at least 99.999%. According
to Carabin, this is the only process in the
world to convert low-quality quartz into Si
of higher than 99.9% purity. " As far as we
know, no one else is doing purification directly
from the quartz itself. "
Making bio-ethanol from cassava pulp
S
apporo Holdings Ltd. (SHL; Tokyo,
Japan; www.sapporoholdings.jp)
and Innotech Green Energy Company
Ltd. (IGE) in Thailand are collaborating
on a project to achieve the world's
first practical fermentation process to make
ethanol from cassava pulp.
The two companies have completed studies
on an 80,000-L/yr pilot demonstration
plant, which was part of a project funded by
the New Energy and Industrial Technology
Development Org. (NEDO, Kawasaki City,
Japan; www.nedo.go.jp) that began in 2014.
The next step will be the design and construction
of a plant with a capacity of 60 million L/yr
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
of ethanol. IGE has begun a feasibility study,
based on the results of the pilot project.
Cassava pulp is a waste product generated
during the extraction of starch from cassava
in the production of tapioca. In Thailand, it
is estimated that 2 million tons of cassava
pulp waste were generated in 2012, which
corresponds to 656 million L of bio-ethanol
if the new technology is used. Because of its
high fiber content, it has not been possible
to utilize cassava pulp as a raw material. A
new heat-tolerant yeast, developed by SHL
and Iwata Chemical Co., Ltd., makes it feasible
to ferment the pulp (for more details,
see Chem. Eng., June 2014, p. 12).
MARCH 2017
Vacuum
arc
furnace
High-purity
silicon
DENOX CATALYSTS
Last month, Haldor Topsøe
A/S (Lyngby, Denmark;
www.topsoe.com) announced
its participation in
ProNOx, a new four-year,
$4-million research program
to improve selective catalytic
reduction (SCR) catalysts.
Together with two research
teams from the Dept.
of Chemistry and the Interdisciplinary
Nanoscience
Center at Aarhus University
(Denmark; www.au.dk),
Topsøe aims to optimize titanium
dioxide nanoparticles
to improve the efficiency of
catalysts used for cleaning
off-gases from engines, industry
and power plants.
Currently, the most effective
catalyst for removing oxides
of nitrogen (NOx) consists of
TiO2 crystals covered with
highly dispersed vanadium
oxides. ProNOx researchers
aim to identify an industrially
viable
nano-design
of
the vanadium-covered
titanium oxides that will improve
the catalyst's performance
by 30%.
The program will utilize the
most recent research on
how to control materials synthesis
at the atomic scale by
closely integrating synthesis,
characterization, modeling
and tests. The end-goal is to
identify the optimal SCR catalysts
and how to produce
them in a controlled way.
Approximately $2.8 million
in funding for ProNOx is
provided by Innovation Fund
Denmark (Copenhagen;
www.innovationsfonden.dk).
NEW MATERIAL
A team of researchers, led by
scientists at the University of
California at Riverside (www.
ucr.edu) and the University of
Colorado at Boulder (www.
colorado.edu),
has
developed
the first self-healing,
mechanically stretchable,
conductive material for possible
applications in batteries,
electronic devices,
(Continues on p. 8)
7
Edited by:
Gerald Ondrey
http://www.topsoe.com http://www.au.dk http://www.pyrogen http://www.esis.com http://www.innovationsfonden.dk http://www.sapporoholdings.jp http://www.ucr.edu http://www.colorado.edu http://www.nedo.go.jp http://WWW.CHEMENGONLINE.COM
Chemical Engineering March 2017

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