Chemical Engineering December 2022 - 8

method is based on spatial atomic
layer deposition (sALD) technology,
which applies extremely thin
layers of functional materials to
large surface areas. TNO initially
developed this technology for the
next generation of television, tablet
and smartphone displays. Now,
the research team has also made
the technology applicable to electrolyzers,
and a patent application
has been filed.
TNO has spent the last two years
experimenting with the sALD technology.
Researchers applied an ultrathin
layer of iridium as a catalyst
material on a porous transport layer
of titanium, instead of on a membrane,
as is presently customary.
The functioning and stability of the
new method has been proven after
different laboratory tests. Little to
no degradation occurred after initial
stress testing.
Together with a group of leading
industrial partners and within the
Voltachem program, TNO is working
on moving this promising technology
from the laboratory to practice.
For this, the method needs
to be scaled up to pilot scale to
demonstrate its functioning under
real-life conditions.
CHEMICALS FROM AIR
It is possible to capture CO2 from
the surrounding atmosphere and
repurpose it into useful chemicals
usually made from fossil
fuels, according to a study from
the University of Surrey (Guilford,
U.K.; www.surrey.ac.uk) that was
recently published in Nanoscale.
The technology uses patentpending
switchable dual-function
materials (DFMs), which capture
CO2 on their surface and catalyze
the conversion of captured
CO2 directly into chemicals. The
" switchable " nature of the DFMs
comes from their ability to produce
multiple chemicals, depending
on the operating conditions
or the composition of the added
reactant. This makes the technology
responsive to variations in the
demand for chemicals, as well as
availability of renewable hydrogen
as a reactant.
The DFMs are composed of Ni-Ru
bimetallic catalyst with Na2O, K2O
or CaO adsorbent supported on
CeO2-Al2O3, and can be designed
to flexibly produce chemicals from
dilute sources of CO2 through the
combination of CO2 adsorption
and subsequent chemical reactions
(methanation, reverse water(Continues
on p. 10)
8
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
DECEMBER 2022
Supercritical extraction drives 'molecular
washing machine' for plastic waste
A
new recycling process has
been developed for scrap polypropylene
(PP), a waste stream
that is currently underserved by
many plastics-recycling facilities. The
process, developed by PureCycle (Orlando,
Fla.; www.purecycle.com), aims
to " wash the plastic molecules " using a
series of purification processes to eliminate
contaminants, odors and colors,
yielding a high-purity stream of PP, unlike
in mechanical recycling where the
contaminants are still included in the
final product. And unlike depolymerization,
PureCycle's technology is a physical
separation process, with no reactive
chemistry - just phase-change and
physical-property separations, explains
Dustin Olson, CEO of PureCycle.
" We effectively manage the solubility
of PP in a way that allows us to remove
other contaminants that are not soluble.
We have a supercritical extraction
step where we remove all the organics,
and then we have a phase-change
management scheme where we are
able to separate all of the non-soluble
components, leaving PP in the soluble
phase, " adds Olson.
The key to PureCycle's technology is
the extraction step, which uses a recyclable,
widely available solvent, and
takes advantage of supercritical phase
conditions. " Taking what we've learned
with supercritical CO2 extraction, at
the temperature and pressure that
puts the process into the supercritical
regime, you see hyper-extraction behavior,
which gives us the capability to
really 'wash' the molecules in an effective
way, " says Olson.
PureCycle has tested its process in a
pilot plant using a range of PP grades,
including homopolymer, copolymer and
impact copolymer, and has shown that
the process successfully removes the
range of contaminants present, from
other plastics, such as polyethylene, to
talc and rubber. Another benefit of the
process, says Olson, is that the contaminant-containing
potentially
saleable
streams are also
coproducts, with
one coproduct resembling pyrolysis oil
and the other coproduct resembling
mechanically recycled polyethylene.
The company is preparing to start
up its first commercial-scale recycling
plant in Ironton, Ohio in early 2023,
and plans are underway for additional
commercial plants in Europe and
South Korea to come onstream in the
next few years.
New smelting furnace enables the use of
lower-grade ore in DRI ironmaking
n late October, Metso Outotec Corp.
(Helsinki, Finland; www.mogroup.
com) introduced the DRI (direct reduced
iron) Smelting Furnace to
substitute blast furnaces used in ironand
steelmaking. The furnace was developed
to tolerate high-slag volumes,
which are problematic for a conventional
electric-arc furnace (EAF). When a
conventional EAF is used to melt hydrogen-based
DRI, gangue content of iron
ore needs to be low, otherwise, the slag
generation and iron losses will increase
drastically in the EAF process, according
to the company. Only less than 3%
of the world's iron ore fulfills the requirement,
the company adds.
" Combined with a direct
I
reduction
plant, the DRI Smelting Furnace will substitute
blast furnaces in the production of
hot metal. This is an optimal solution for
primary steel producers aiming for a significant
reduction in their CO2 emissions
with minimal changes to the rest of the
steel plant. The furnace can be integrated
with Metso Outotec's H2-based Circored
process [Chem. Eng., June 2022, p. 5]
or
other
direct-reduction
processes, "
says Kimmo Vallo, product manager,
DRI Smelting Furnace at Metso Outotec.
Replacing blast furnaces with direct-reduction
plants and DRI Smelting Furnace
technology using " green " H2 and energy
can avoid 80-90% of CO2 emissions
from steelmaking, the company says.
DRI Smelting Furnace technology is
based on proven Metso Outotec equipment
- electrode equipment; furnace
structure, based on the company's
Flash Smelter; Venturi scrubber; cooling
elements; and advanced automation
tools and digital twins. The Furnace
and related products are complete and
ready for implementation. User-specific
pilot-scale testing will be conducted in
the Metso Outotec research facilities to
demonstrate large-scale DRI smelting.
The new 6-in.-line DRI Smelting Furnace
offers high productivity with capacities
above 1.2 million ton/yr.
http://www.purecycle.com http://www.surrey.ac.uk http://www.mogroup.com http://www.mogroup.com http://WWW.CHEMENGONLINE.COM
Chemical Engineering December 2022

Table of Contents for the Digital Edition of Chemical Engineering December 2022
