che_april-2024 - 6

plant will be built onsite
next to Yara's existing
ammonia plant.
After startup in 2026,
it will be a part of one
of the first commercial
carbon-capturestorage
(CCS) ventures
in Europe.
SCRUBBER PILOT
Metso Corp. (Espoo,
Finland; www.metso.
com) has installed a
fully automated multipurpose
scrubber
pilot plant at its R&D
center in Frankfurt
am Main, Germany.
The new plant will be
used for developing
and optimizing gascleaning
processes.
The first focus will be
on the development of
simultaneous scrub(Continues
on p. 8)
Membrane-free water electrolysis
R
esearchers at KTH Royal Institute of
Technology (Stockholm, Sweden;
www.kth.se) have developed a way
to decouple the production of hydrogen
and oxygen in water electrolysis, thereby
reducing the explosion potential of mixing
the two gases. The method, described in a
recent issue of Science Advances, combines
the electrocatalytic reactions of an electrolyzer
with a capacitive-storage mechanism.
In a conventional alkaline electrolyzer, the
cathode and anode are separated by an ionpermeable
membrane. When an electric current
is applied, water reacts at the cathode
by forming H2 and OH-
ions, which diffuse
through the barrier to the anode to produce
O2. But the barrier causes resistance, and if
the electric charge fluctuates, the risk of an explosive
mix between O2 and H2 is heightened.
To avoid this, one of the electrodes is replaced
with a super capacitive electrode
made from carbon. When the electrode is
negatively charged and producing H2, the
super capacitor stores energy-rich OH- ions.
When the direction of current is reversed, the
super capacitor releases the absorbed OH-,
and O2 is produced at the now-positive electrode.
" One electrode does the evolution of
both oxygen and hydrogen, " explains Joydeep
Dutta, professor of applied physics at
KTH. " It's a lot like a rechargeable battery
producing H2 - alternately charging and discharging.
It's all about completing the circuit. "
According to the Science Advances article,
an energy efficiency of 69% lower heating
value (48 kWh/kg) at 10 mA/cm2 (5 cm ×
5 cm cell) was achieved using a cobalt-iron
phosphide bifunctional catalyst with 99%
Faradaic efficiency at 100 mA/cm2. The researchers
also report that laboratory tests
showed no apparent electrode degradation
as a result of long-term tests, which is important
for commercial applications.
Dutta and Esteban Toledo, a doctoral student
at KTH who co-authored the paper,
have patented the system. With support
from KTH Innovation, a company, Caplyzer
AB (Stockholm, Sweden; www.caplyzer.
com), was already formed in 2021 to scale
up the technology.
This cooling and water-harvesting system requires no heat
A
novel technology for cooling and dehumidification
is nearing commercialization through several
strategic partnerships, including GE Vernova,
BASF and Carrier Global. Montana Technologies'
(Ronan, Mont.; www.mt.energy) AirJoule technology employs
a metal-organic-framework (MOF) desiccant material
that exhibits higher water-uptake capacity and faster atmospheric
water extraction when compared to traditional
desiccant systems, and with significantly reduced energy
consumption. " When desiccant dehumidifier systems
remove water from air, a significant heat of adsorption is
naturally generated that up to now has been transferred to
the air stream and warms it up. In addition, most desiccant
systems require adding even more external heat to regenerate
the desiccant media, which is often added to the
system's cooling load. With AirJoule, we use a pressureswing
approach and do not introduce any external heat. In
addition, we capture that heat of adsorption and use it for
regeneration. We
basically
have a net-zero thermal energy
balance when extracting
water from an airstream, "
explains Pete McGrail, chief
technology officer of Montana
Technologies. The AirJoule
system is configured
as two chambers working
in tandem. As humid air is
drawn into one chamber, the
MOF media adsorbs water
vapor. Simultaneously, the
heat of adsorption is transferred
to the other chamber
6
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
APRIL 2024
to begin regenerating the media. " Air is flowing through
one chamber all the time, while the other chamber is being
regenerated under a modest vacuum, " says McGrail. The
system cycles between chambers every 5-10 min.
However, there are limitations on the system's ability to
compress water vapor while maintaining its energy balance.
" We're compressing the water vapor just enough to
condense it. We have designed specialized equipment to
handle low-pressure water vapor and minimize the energy
requirement, " adds McGrail. Once the water is a liquid, it
takes a trivial amount of energy to bring it up to atmospheric
pressure for discharge and use.
Many applications for AirJoule are in HVAC and waterheating
installations, but the company has also seen interest
in applying the technology as a replacement for
evaporative cooling systems in aluminum-smelting and
data-center applications.
Montana Technologies
http://www.kth.se http://www.metso.com http://www.caplyzer.com http://www.mt.energy http://WWW.CHEMENGONLINE.COM
che_april-2024

Table of Contents for the Digital Edition of che_april-2024
