Air
separation
and
carbon
dioxide
capture
are
essential
processes
used
in
various
industries.
In
particular,
the
supply
of
small-scale
medical
oxygen
generators
has
been
emphasized
during
worldwide
spread
respiratory-related
diseases,
such
as
COVID-19
pandemic.
This
study
investigated
adsorption
equilibria
kinetics
O2,
N2,
CO2
dynamic
performance
four
commercial
zeolite
LiX
pellets
because
pelletized
zeolites
can
be
different
by
their
heterogeneity
adding
binders
pelletizing
methods.
Three
binder
were
selected
compared
with
one
binderless
pellet
a
reference.
The
isotherms,
measured
using
volumetric
system
at
293–323
K
up
to
100
kPa,
correlated
dual-site
Langmuir
Sips
models.
For
all
adsorbents,
order
amount
isosteric
heat
was
≫
N2
>
O2.
Differences
capacity
clearly
observed,
indicating
that
had
highest
capacity.
According
analysis
non-isothermal
diffusion
model,
rate
faster
than
for
adsorbents.
difference
apparent
diffusional
constants
observed
low-pressure
range,
showing
among
owing
effects
adsorption,
dissipation,
thermal
resistance.
pellet,
which
relatively
slow
but
N2/O2
selectivity,
exhibited
best
breakthrough
experiments.
Separation and Purification Technology,
Год журнала:
2024,
Номер
349, С. 127662 - 127662
Опубликована: Апрель 25, 2024
CO2
capture
is
important
in
solving
one
of
the
major
current
environmental
problems,
namely
global
warming.
Among
different
approaches,
adsorption
considered
most
promising
and
CaX
zeolite
materials
with
highest
capacity.
However,
knowledge
on
mechanism
its
interaction
still
not
complete
which
hinders
further
optimization.
In
this
work
we
report
results
a
combined
study
by
in-situ
FTIR
spectroscopy,
measurements
DFT
calculations.
It
was
found
that
at
ambient
temperature
initially
forms
linear
Ca2+−OCO
species
which,
increasing
equilibrium
pressure,
are
first
converted
to
Ca2+(CO2)2
then
Ca2+(CO2)3
species.
This
reason
for
very
high
capacity
material.
Because
practical
importance,
effect
H2O
processes
also
studied.
Water
suppress
but
softened
formation
mixed
ligand
Ca2+(CO2)x(H2O)y
complexes
(x
+
y
=
2
or
3).
agreement
spectroscopic
it
material
increases
rise
activation
up
673
K
due
dehydration.
Its
value,
22.2
wt%
273
490
mbar,
among
values
reported
literature
similar
conditions.
Molecules,
Год журнала:
2024,
Номер
29(13), С. 3153 - 3153
Опубликована: Июль 2, 2024
Activated
carbon
has
an
excellent
porous
structure
and
is
considered
a
promising
adsorbent
electrode
material.
In
this
study,
activated
fibers
(ACFs)
with
abundant
microporous
structures,
derived
from
natural
cotton
fibers,
were
successfully
synthesized
at
certain
temperature
in
Ar
atmosphere
then
KOH.
The
obtained
ACFs
characterized
by
field
emission
scanning
electron
microscopy
(FESEM),
transmission
(TEM),
elemental
analysis,
nitrogen
dioxide
adsorption-desorption
X-ray
diffraction
(XRD),
photoelectron
spectroscopy
(XPS)
N
Air
separation
and
carbon
dioxide
capture
are
essential
processes
used
in
various
industries.
In
particular,
the
supply
of
small-scale
medical
oxygen
generators
has
been
emphasized
during
worldwide
spread
respiratory-related
diseases,
such
as
COVID-19
pandemic.
This
study
investigated
adsorption
equilibria
kinetics
O2,
N2,
CO2
dynamic
performance
four
commercial
zeolite
LiX
pellets
because
pelletized
zeolites
can
be
different
by
their
heterogeneity
adding
binders
pelletizing
methods.
Three
binder
were
selected
compared
with
one
binderless
pellet
a
reference.
The
isotherms,
measured
using
volumetric
system
at
293–323
K
up
to
100
kPa,
correlated
dual-site
Langmuir
Sips
models.
For
all
adsorbents,
order
amount
isosteric
heat
was
≫
N2
>
O2.
Differences
capacity
clearly
observed,
indicating
that
had
highest
capacity.
According
analysis
non-isothermal
diffusion
model,
rate
faster
than
for
adsorbents.
difference
apparent
diffusional
constants
observed
low-pressure
range,
showing
among
owing
effects
adsorption,
dissipation,
thermal
resistance.
pellet,
which
relatively
slow
but
N2/O2
selectivity,
exhibited
best
breakthrough
experiments.
