Chemical Engineering July 2022 - 8

adding coffee grounds and tea
leaves to a sodium phosphate
buffer, then incubating this solution
while shaking it. In the
presence of the buffer, SCG
and TLR interacted with O2 to
produce H2O2. This method is
much simpler and more environmentally
friendly than the
conventional anthraquinone
process.
The study - published last
month in ACS Omega - also
details the use of this H2O2
produced from biomass to
synthesize other chemicals,
for example, the H2O2-promoted
enzymatic oxidations
of 4-methoxy-1-naphthol to
Russig's blue (a model reaction
to test the peroxygenation
activity of enzymes),
and the enzymatic oxidation
of styrene to styrene oxide
and phenylacetaldehyde.
RECYCLING TEXTILES
Worn Again Technologies (Nottingham,
U.K.; www.wornagain.co.uk)
is in the final planning
stages of a demonstration
plant that will showcase its
ground-breaking polymer processing
technologies for textile
recycling. The facility, which will
be built and operated by the
company, is to be constructed
in Winterthur, Switzerland and
will have the capacity to recycle
1,000 m.t./yr of textiles.
The new industrial-scale infrastructure
will help validate
the
closed-loop
chemical
recycling solution that has
been developed by Worn
Again Technologies and its
strategic
partners,
Switzerland; www.
Iron catalyst shows promise for improving
economics of metathesis reactions
T
he olefin metathesis reaction produces
new carbon-carbon double
bonds by swapping the carbon
atoms in olefins, and is important
for producing a number of chemicals.
Currently, the most popular catalysts for
this reaction are made from the precious
metal ruthenium or molybdenum. Now,
researchers from Okinawa Institute of Science
and Technology Graduate University
(OIST; Japan; www.oist.jp) have designed
an iron-based catalyst as an economical
alternative to conventional Ru-based
catalysts. Described in a June issue of
Nature Catalysis, the new catalyst is a
three-coordinate iron(II) catalyst (diagram,
right), which was demonstrated to perform
ring-opening metathesis polymerization
of olefins.
For example,
OIST's
catalyst was
shown to enable
the
formation
of polynorbornene
(diagram)
with
stereoregularity
and high molecular weight (greater
than 107 g/mol). The polymerization of
norbornene in the presence of styrene
revealed cross-metathesis reactivity with
the iron catalysts. A mechanism was also
developed to describe the reaction.
Despite the success of this research,
OIST researcher Satoshi Takebayashi,
and lead author of the study, cautions that
more work is required, and that today's
state-of-the-art Ru-based catalysts are
still much more applicable than the newly
created iron-based ones. For example,
the iron catalyst is unstable and less active
when exposed to air and moisture.
These limitations need to be addressed
before the iron-based catalyst can replace
the Ru one, he says.
2n
Iron catalyst
N
P
n
OIST
Iron catalyst
Recycling Portland cement - emissions-free
T
including
Sulzer Chemtech Ltd. (Winterthur,
sulzer.com).
The process obtains
polyethylene terephthalate
(PET) and cellulose from
non-reusable, hard-to-recycle
textiles that constitute postindustrial
and post-consumer
waste. Additionally, the process
purifies the products by
removing dyes, contaminants
and impurities, a step
forward
from traditional recycling
methods, the company says.
Last month, Worn Again
Technologies launched the
Swiss Textile Recycling Ecosystem,
an initiative that
brings together key industry
players across the entire textile
value chain.
(Continues on p. 9)
8
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JULY 2022
he production of clinker used for
making cement continues to be a
major source of global CO2 emissions.
Now, three engineers from
the University of Cambridge (U.K.; eng.
cam.ac.uk) have filed a patent and been
awarded new research funding for their
invention of what is said to be the world's
first emissions-free route to recycle Portland
cement.
The inspiration for the so-called Cambridge
Electric Cement struck inventor
Cyrille Dunant when he noticed that the
chemistry of used cement is virtually identical
to that of the lime-flux that is already
being used in conventional steel-recycling
processes that use electric-arc furnaces
(EAF). The new cement is therefore made
in a virtuous recycling loop, which not
only eliminates the emissions of cement
production, but also saves raw materials,
and even reduces the emissions required
in making lime-flux.
The new process begins with concrete
waste from the demolition of old buildings.
This is crushed, to separate the
stones and sand that form concrete from
the mixture of cement powder and water
that bind them together. The old cement
powder is then used instead of lime-flux in
steel recycling. As the steel melts, the flux
forms a slag that floats on the liquid steel,
to protect it from oxygen in the air. After
the recycled steel is tapped off, the liquid
slag is cooled rapidly in air, and ground
up into a powder that is virtually identical
to the clinker which is the basis of new
Portland cement.
In pilot-scale trials of the new process, the
Cambridge team have demonstrated this
combined recycling process, and the results
show that it has the chemical composition of
a clinker made with today's process.
The new cement was invented as part
of the large multi-university UK FIRES
program, led by professor Julian Allwood,
which aims to enable a rapid transition to
zero emissions based on using today's
technologies differently, rather than waiting
for the new energy technologies of
hydrogen and carbon storage. Invention
of the cement has been rewarded with a
new research grant of £1.7 million ($2.1
million) from the Engineering and Physical
Sciences Research Council (EPSRC;
Swindon, U.K.) for further development.
Fe
SiMe3
http://www.oist.jp http://www.wornagain.co.uk http://www.wornagain.co.uk http://eng.cam.ac.uk http://eng.cam.ac.uk http://www.sulzer.com http://www.sulzer.com http://WWW.CHEMENGONLINE.COM
Chemical Engineering July 2022

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