Chemical Engineering November 2021 - 6

owned subsidiary of Vietnam
listed Masan High Tech Materials,
has developed a new process
for high-pressure reverse
osmosis in the production of
tungsten chemicals that significantly
reduces energy consumption
and CO2 emissions
compared to conventional
processes. To achieve this, the
Technology and Innovation department
cooperated closely
with process specialist OSMO
Membrane Systems GmbH
(Korntal-Münchingen, Germany;
www.osmo-membrane.
de). H.C. Starck is already using
the process at its Goslar site for
the concentration of ammonium
metatungstate (AMW)
solutions on an industrial scale.
In the production of AMW, a
very dilute solution is first obtained
from ammonium paratungstate
(APW), which then
has to be highly concentrated.
This is traditionally done by
evaporation, which is energy
intensive. With the new patentpending
process, the solution
is pressed under high pressure
through a semi-permeable
membrane. The membranebased
approach reduces energy
consumption by more
than 95% at a production volume
of around 1,000 ton/yr of
AMW, says the company.
CO2-NEUTRAL CH3OH
Haldor Topsoe A/S (Lyngby,
Denmark; www.topsoe.com)
has started up a demonstration
plant for the production of
sustainable methanol from biogas.
The demonstration plant,
which is part of a project supported
by the EUDP Energy
Technology Development and
Demonstration Program and is
developed together with Aarhus
University, aims to validate
Topsoe's electrified steammethane-reforming
(eSMR)
technology for cost-competitive
production of sustainable
methanol from biogas as well
as other sustainable products.
As with conventional SMR,
eSMR reforms methane into
synthesis gas (syngas), which
can then be used for methanol
synthesis (or other chemicals).
However, instead of heating
the catalyst-packed reformer
tubes indirectly by the combustion
of fuels, eSMR uses
smaller-diameter tubes, which
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6
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
NOVEMBER 2021
Recovering phosphoric acid from sewage-sludge
incineration ash
his month, SusPhos B.V. (Amsterdam,
the Netherlands; www.susphos.com)
is increasing the capacity ten-fold of
its 25-kg/d pilot plant in Leeuwarden,
the Netherlands. The pilot plant, which began
operating in January, is being used to develop
a process that recovers phosphorus from
sewage-sludge incinerator ash, and produces
merchant-grade phosphoric acid (MGA), and
mono- and diammonium phosphate (MAP,
DAP), while recovering other metal salts. " Our
main goal is to recover phosphorus without
generating any waste - to recycle everything, "
says chief technology officer Willem Schipper.
In the process (diagram), incinerator ash is
first treated with acid to generate phosphoric
acid. In a second step, a proprietary organic
solvent is used to selectively extract this H3PO4,
which is then stripped of solvent to produce
75-80 wt.% H3PO4 with very low metals content.
Meanwhile,
the
remaining
solids are
treated to
r ecover
iron and
aluminum
salts as
side products,
leavSusPhos
T
ing
behind an insoluble, inert-mineral stream in
which heavy metals are fixed. The process is
flexible, so that the phosphate can alternatively
be recovered as a MAP or DAP flame retardant
and fertilizer in a simple add-on step.
The SusPhos process uses an order of magnitude
less water and energy, when compared
to alternative phosphorus-recovery methods
that require energy-intensive water evaporation
to concentrate the acid or salt solutions,
says Schipper.
The company is simultaneously carrying out
the basic engineering and design for a fullscale
plant that can treat 50,000 ton/yr of incinerator
ash. " We are ready to offer a 'ripe'
technology for when it is needed, " says Schipper,
who expects a first plant within the next
two years. In Germany, for example, phosphorus-recovery
from sewage will be required in
2029, he says.
Self-healing hydrophobic coatings enhance
heat transfer in steam condensers
U
ltrathin (less than 100 nm) hydrophobic
coatings on alloys and other
engineering
materials could
enhance
heat and mass transfer in a
range of processing applications, but achieving
lasting durability for such thin coatings
in real-world settings has been a major ongoing
challenge. Now, researchers at the
University of Illinois (Champaign, Ill.; www.
illinois.edu) have developed a coating material
that can repair itself after scratching, cutting
and other damage, extending its durability
even at nanoscale thicknesses.
The current research project, led by University
of Illinois engineering professor Nenad
Miljkovic and published in Nature Communications,
focused on using the coatings to boost
the efficiency of condensers in power-plant
steam systems. Hydrophobic coatings render
the metals more water-resistant and efficient
at forming water droplets, which enhances
heat transfer, the team notes. In steam power
plants, thin coatings can break down quickly.
Thicker coatings can be more durable, but they
reduce heat transfer and erode the associated
benefit of the coating.
To avoid this tradeoff, the researchers designed
and synthesized a vitrimer thin film with
polydimethylsiloxane network strands and dynamic
boronic ester crosslinks. Named dynPDMS,
the coating material takes advantage
of the inherent hydrophobic nature of silicones,
and provides a mechanism for self-healing, due
to the dynamic exchange of bonds in their network
strands, the researchers say. Vitrimers
refer to a class of materials with covalent bond
networks that can undergo bond exchange.
The film " maintains excellent hydrophobicity
and optical transparency after scratching,
cutting, and indenting, " the researchers say.
In addition to enhanced heat transfer, the
coating material could have a range of other
potential applications, such as self-cleaning,
anti-icing, anti-fogging, anti-bacterial or antifouling
coatings.
The dyn-PDMS can be easily dip-coated onto
surfaces - including silicon, aluminum, copper
and steel - in nanoscale layers.
http://www.susphos.com http://www.osmo-membrane.de http://www.topsoe.com http://www.illinois.edu http://WWW.CHEMENGONLINE.COM
Chemical Engineering November 2021

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